WorldWideScience

Sample records for geochemically variable soil

  1. Geochemical variability of soils and biogeochemical variability of plants in the Piceance Basin, Colorado

    Science.gov (United States)

    Tuttle, M.L.; Severson, R.C.; Dean, W.E.; Klusman, R.W.

    1986-01-01

    Geochemical baselines for native soils and biogeochemical baselines for plants in the Piceance basin provide data that can be used to assess geochemical and biogeochemical effects of oil-shale development, monitor changes in the geochemical and biogeochemical environment during development, and assess the degree of success of rehabilitation of native materials after development. Baseline values for 52 properties in native soils, 15 properties in big sagebrush, and 13 properties in western wheatgrass were established. Our Study revealed statistically significant regional variations of the following properties across the basin: in soil&-aluminum, cobalt, copper, iron, manganese, sodium, nickel, phosphorus, lead, scandium, titanium, vanadium, zinc, organic and total carbon, pH, clay, dolomite, sodium feldspar, and DTPA-extractable calcium, cadmium, iron, potassium, manganese, nickel, phosphorus, yttrium, and zinc; in big sagebrush-barium, calcium, copper, magnesium, molybdenum, sodium, strontium, zinc, and ash; and in western wheatgrass-boron, barium, calcium, magnesium, manganese, molybdenum, strontium, zinc, and ash. These variations show up as north-south trends across the basin, or they reflect differences in elevation, hydrology, and soil parent material. Baseline values for properties that do not have statistically significant regional variations can be represented by geometric means and deviations calculated from all values within the basin. Chemical and mineralogical analyses of soil and chemical analyses of western wheatgrass samples from Colorado State University's experimental revegetation plot at Anvil Points provide data useful in assessing potential effects on soil and plant properties when largescale revegetation operations begin. The concentrations of certain properties are related to the presence of topsoil over spent shale in the lysimeters. In soils, calcium, fluorine, lithium, magnesium, sodium, phosphorus, strontium, carbonate and total carbon

  2. National Geochemical Database: Soil

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemical analysis of soil samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are from the continental US...

  3. Relative spatial soil geochemical variability along two transects across the United States and Canada

    Science.gov (United States)

    Garrett, Robert G.

    2009-01-01

    To support the development of protocols for the proposed North American Soil Geochemical Landscapes project, whose objective is to establish baselines for the geochemistry of North American soils, two continental-scale transects across the United States and Canada were sampled in 2004. The sampling employed a spatially stratified random sampling design in order to estimate the variability between 40-km linear sampling units, within them, at sample sites, and due to sample preparation and analytical chemical procedures. The 40-km scale was chosen to be consistent with the density proposed for the continental-scale project. The two transects, north–south (N–S) from northern Manitoba to the USA–Mexico border near El Paso, Texas, and east–west (E–W) from the Virginia shore north of Washington, DC, to north of San Francisco, California, closely following the 38th parallel, have been studied individually. The purpose of this study was to determine if statistically significant systematic spatial variation occurred along the transects. Data for 38 major, minor and trace elements in A- and C-horizon soils where less than 5% of the data were below the detection limit were investigated by Analysis of Variance (ANOVA). A total of 15 elements (K, Na, As, Ba, Be, Ce, La, Mn, Nb, P, Rb, Sb, Th, Tl and W) demonstrated statistically significant (p<0.05) variability at the between-40-km scale for both horizons along both transects. Only Cu failed to demonstrate significant variability at the between-40-km scale for both soil horizons along both transects.

  4. The impact of local geochemical variability on quantifying hillslope soil production and chemical weathering

    Science.gov (United States)

    Heimsath, Arjun M.; Burke, Benjamin C.

    2013-10-01

    Soil-mantled upland landscapes are widespread across the habitable world, support extensive life, and are the interface between the atmosphere, hydrosphere, and lithosphere but typically are not cultivated. Soil found across such landscapes fits the conceptual framework of a physically mobile layer derived from the underlying parent material along with some locally derived organic content. The extent and persistence of these upland soils depend on the long-term balance between soil production and erosion. Here we briefly review methods used to quantify the physical and chemical processes of soil production and erosion and revisit three granitic study areas in southeastern Australia and northern California that enabled early quantification of the soil production function and topographic controls on chemical weathering. We then present new major and trace element data from 2-m by 2-m pits dug at each field site to quantify local variability of Zr concentrations and the chemical index of alteration (CIA), weathering indices used to determine chemical weathering rates and extents in soils and saprolites. Using both new and previously published data, we compare differences between local variability and regional, as well as intersite variability of these important indices. For each of the 2-m pits, we collected 25 samples and found that the simple mean and the 2σ standard deviation best describe the local variation in the data. We also find that the variability in the 2-m pit data lies within variability observed in the same data from samples collected in individual soil pits across each of the field sites and that the differences between sites are consistent with previously published results. These observations highlight the importance of quantifying local scale variability in studies that use similar, multifaceted measurements to quantify hillslope soil production and erosion processes.

  5. The geochemical atlas of Italian soils

    Science.gov (United States)

    De Vivo, Benedetto; Cicchella, Domenico; Albanese, Stefano; Dinelli, Enrico; Giaccio, Lucia; Lima, Annamaria; Valera, Paolo

    2014-05-01

    The geochemical Atlas of Italian agricultural and grazing land soils was carried out as part of GEMAS project whose objective was to characterize soils of rural areas of the whole Europe. Soil samples were collected at an average sampling density of 1 site per 2500 km2. Two different sample types were collected: (1) 121 agricultural soils (Ap) on regularly ploughed land to a depth of 20 cm and (2) 121 grazing land soils (Gr) (land under permanent grass cover) to a depth of 10 cm. All soil samples were air dried, sieved to pH, TOC, total carbon and total sulphur, LOI, CEC, Sr-isotopes, Pb-isotopes, MIR-spectra. By means of a GIS software, georeferenced data of the Italian territory were used to produce the geochemical maps of all the analysed elements for both agricultural and grazing land soils. Specifically, for each element and sampling media a map reporting interpolated data and graduated dots was produced; univariate statistics and graphs were also associated to each map. The Atlas also contain: 5 maps for regional variability of factor scores of elemental associations resulting from R-mode factor analysis and 15 baseline and land use maps for some selected elements (As, Be, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, Se, Sn, Tl, V, Zn) following the Italian intervention criteria.

  6. Heavy metal accumulation in balsam pear and cowpea related to the geochemical factors of variable-charge soils in the Pearl River Delta, South China.

    Science.gov (United States)

    Chang, Chun-Ying; Xu, Xiang-Hua; Liu, Chuan-Ping; Li, Shu-Yi; Liao, Xin-Rong; Dong, Jun; Li, Fang-Bai

    2014-07-01

    Variable-charge (v-c) soils in subtropical areas contain considerable amounts of iron/aluminum (Fe/Al) oxides that can strongly influence the fate of heavy metals in agricultural ecosystems. However, the relationship between heavy metal accumulation in vegetables and the geochemical factors associated with v-c soils in subtropical regions remains unknown. The present study investigated heavy metal accumulation under field conditions in the Pearl River Delta (PRD) by measuring the content of 8 heavy metals (zinc (Zn), arsenic (As), copper (Cu), mercury (Hg), lead (Pb), chromium (Cr), nickel (Ni) and cadmium (Cd)) in 43 pairs of v-c soil and vegetable (balsam pear and cowpea) samples. Soil physicochemical properties including pH, texture, organic matter and oxide minerals (Fe2O3, SiO2, Al2O3, CaO, MgO, K2O and Na2O) were also analyzed. Heavy metal accumulation from soil to vegetables was assessed based on bioconcentration factors (BCFs). The results showed that soil extractable Fe, oxide minerals and chemical weathering indices of v-c soils strongly affected heavy metal accumulation, whereas the content of Zn, Cu, Cr and Ni in vegetables was strongly affected by the soil clay content. Significant correlations were found between the BCFs of heavy metals and oxide minerals. However, no significant relationship was found between pH and heavy metal accumulation (except for Cu) in balsam pear and cowpea. Correlation analyses showed that a lower oxalate/DCB- extractable Fe content might indicate greater heavy metal (Zn, Cu, Hg, Cr and Ni) accumulation in vegetables. Therefore, it can be deduced that oxalate/DCB- extractable Fe content is a critical geochemical factor that determines the bioavailability of heavy metals and that iron biogeochemical cycles play vital roles in the fate of heavy metals in vegetable fields in this area. These findings provide new insights into the behaviors and fate of heavy metals in subtropical v-c soils and can be used to develop possible

  7. Geochemical baseline studies of soil in Finland

    Science.gov (United States)

    Pihlaja, Jouni

    2017-04-01

    The soil element concentrations regionally vary a lot in Finland. Mostly this is caused by the different bedrock types, which are reflected in the soil qualities. Geological Survey of Finland (GTK) is carrying out geochemical baseline studies in Finland. In the previous phase, the research is focusing on urban areas and mine environments. The information can, for example, be used to determine the need for soil remediation, to assess environmental impacts or to measure the natural state of soil in industrial areas or mine districts. The field work is done by taking soil samples, typically at depth between 0-10 cm. Sampling sites are chosen to represent the most vulnerable areas when thinking of human impacts by possible toxic soil element contents: playgrounds, day-care centers, schools, parks and residential areas. In the mine districts the samples are taken from the areas locating outside the airborne dust effected areas. Element contents of the soil samples are then analyzed with ICP-AES and ICP-MS, Hg with CV-AAS. The results of the geochemical baseline studies are published in the Finnish national geochemical baseline database (TAPIR). The geochemical baseline map service is free for all users via internet browser. Through this map service it is possible to calculate regional soil baseline values using geochemical data stored in the map service database. Baseline data for 17 elements in total is provided in the map service and it can be viewed on the GTK's web pages (http://gtkdata.gtk.fi/Tapir/indexEN.html).

  8. Geochemical patterns in the soils of Cyprus.

    Science.gov (United States)

    Cohen, David R; Rutherford, Neil F; Morisseau, Eleni; Zissimos, Andreas M

    2012-03-15

    The soil geochemical atlas of Cyprus is a recent addition to the series of national to continental-scale geochemical mapping programmes implemented over the last two decades for environmental and resource applications. The study has been conducted at the high sampling density of 1 site per 1km(2), with multi-element and multi-method analysis performed on samples of top soil (0-25cm) and sub soil (50-75cm) from a grid of over 5350 sites across a major portion of Cyprus. Major and most trace elements display sharp concentration changes across the main geological boundaries but a high degree of spatial continuity and consistency of values within those boundaries. Some elements display one to two orders of magnitude difference in median concentrations between the soils developed over ultramafic or mafic units and those developed over sedimentary rocks or alluvial units. The ratio of aqua regia-extractable to total metal contents provides an indication of the general mineralogical host for a number of trace elements. The majority of soils are near-neutral to alkaline with the small proportion of areas with soil pHgeochemical values. Where the concentrations of some elements (including Pb, Hg and Sn) are indicative of contamination, the values are typically higher in the top soil samples in these areas. Variations in the concentration of elements with strong redox controls on mobility are linked to changes in sedimentary environment between deep and shallow marine conditions. Some element patterns can be related to the effects of urbanisation and sulphide mining operations; however the dominant control on soil geochemistry is the parent geology and regolith forming processes. The atlas demonstrates the effectiveness of high-density sampling in mapping local to regional-scale features of the geochemical landscape.

  9. Reconnaissance soil geochemical survey of Gibraltar.

    Science.gov (United States)

    Mesilio, Liesl; Farago, Margaret E; Thornton, Iain

    2003-03-01

    The extreme density of population of Gibraltar, situated at the southern tip of Spain, exerts considerable pressure on land use and thus future planning is of utmost importance. An initial reconnaissance soil geochemical survey of Gibraltar was based on 120 surface samples (0-15 cm) taken from a wide range of exposed, either bare soil or vegetated sites, to provide the optimum geographical distribution. The 'total' elemental concentrations of 26 elements (Li, Na, K, Be, Mg, Ca, Sr, Ba, Al, La, Ti, V, Cr, Mo, Mn, Fe, Co, Ni, Cu, Ag, Zn, Cd, Pb, P, S, As) were determined by nitric/percholric acid digestion followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. The reconnaissance data shows that the spatial distribution of various elements depended on previous and present land use. Most elements (Ca, Cr, Mg and Mn excluded) exhibited relatively high concentrations in civilian and natural soils. Trends have been established for many elements, and concentrations exceeding guideline values have been found in certain areas of Gibraltar. This reconnaissance of Gibraltar is at present being followed by a more detailed baseline geochemical survey, which will establish the extent and magnitude of the variations in major and trace elements in soils and dusts, assess the impact of industrial, commercial and urban development on the geochemical landscape and to make recommendations concerning sustainable development.

  10. Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations.

    Science.gov (United States)

    Sengupta, Aditi; Wang, Yadi; Meira Neto, Antonio A; Matos, Katarena A; Dontsova, Katerina; Root, Rob; Neilson, Julie W; Maier, Raina M; Chorover, Jon; Troch, Peter A

    2016-09-11

    Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

  11. Use of Geochemical Indices in Environmental Assessment of Soil; the Predictable and the Predictably Unpredictable

    Science.gov (United States)

    Mikkonen, Hannah; Clarke, Bradley; van de Graaff, Robert; Reichman, Suzie

    2016-04-01

    Geochemical correlations between common contaminants (Pb, Ni, As, Cr, Co and Zn) and earth metals, Fe and Mn, have been recommended as empirical tools to estimate "background" concentrations of metals in soil. A limited number of studies indicate that geochemical ratios between Pb, Ni, As, Cr, Co, V and Zn with scavenger metals Fe or Mn, are consistent between soils collected from different regions (Hamon et al. 2004, Myers and Thorbjornsen 2004). These studies have resulted in the incorporation of geochemical indices into Australian guidance, for derivation of ecological investigation levels for Ni, Cr, Cu and Zn. However, little research has been undertaken to assess the variation of geochemical patterns between soils derived from different parent materials or different weathering environments. A survey of background soils derived from four different parent materials, across Victoria, Australia, was undertaken, comprising collection of samples (n=640) from the surface (0 to 0.1 m) and sub-surface (0.3 to 0.6 m). Soil samples were collected from urban and rural areas of low disturbance, away from point sources of contamination. Samples were analysed for metals/metalloids and soil physical and chemical properties. Statistical review of results included regression and multivariate analysis. The results of the soil survey were compared against geochemical relationships reported within Australia and internationally. Compilation of results from this study and international data sets, indicates that geochemical relationships for metals Cr and V (in the format of log[Cr] = alog[Fe] +c) are predictable, not only between soils derived from different parent materials, but also between soils of different continents. Conversely, relationships between Zn and Fe, Pb and Fe, Cu and Fe, Co and Mn are variable, particularly within soils derived from alluvial sediments, which may have undergone periods of reducing conditions, resulting in dissociation from metal oxides. Broad

  12. Linking the climatic and geochemical controls on global soil carbon cycling

    Science.gov (United States)

    Doetterl, Sebastian; Stevens, Antoine; Six, Johan; Merckx, Roel; Van Oost, Kristof; Casanova Pinto, Manuel; Casanova-Katny, Angélica; Muñoz, Cristina; Boudin, Mathieu; Zagal Venegas, Erick; Boeckx, Pascal

    2015-04-01

    Climatic and geochemical parameters are regarded as the primary controls for soil organic carbon (SOC) storage and turnover. However, due to the difference in scale between climate and geochemical-related soil research, the interaction of these key factors for SOC dynamics have rarely been assessed. Across a large geochemical and climatic transect in similar biomes in Chile and the Antarctic Peninsula we show how abiotic geochemical soil features describing soil mineralogy and weathering pose a direct control on SOC stocks, concentration and turnover and are central to explaining soil C dynamics at larger scales. Precipitation and temperature had an only indirect control by regulating geochemistry. Soils with high SOC content have low specific potential CO2 respiration rates, but a large fraction of SOC that is stabilized via organo-mineral interactions. The opposite was observed for soils with low SOC content. The observed differences for topsoil SOC stocks along this transect of similar biomes but differing geo-climatic site conditions are of the same magnitude as differences observed for topsoil SOC stocks across all major global biomes. Using precipitation and a set of abiotic geochemical parameters describing soil mineralogy and weathering status led to predictions of high accuracy (R2 0.53-0.94) for different C response variables. Partial correlation analyses revealed that the strength of the correlation between climatic predictors and SOC response variables decreased by 51 - 83% when controlling for geochemical predictors. In contrast, controlling for climatic variables did not result in a strong decrease in the strength of the correlations of between most geochemical variables and SOC response variables. In summary, geochemical parameters describing soil mineralogy and weathering were found to be essential for accurate predictions of SOC stocks and potential CO2 respiration, while climatic factors were of minor importance as a direct control, but are

  13. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    Science.gov (United States)

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  14. Geochemical Cycling of Iodine Species in Soils

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Q; Moran, J E; Blackwood, V

    2007-08-23

    Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine in soils is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we applied new analytical techniques to study the content and speciation of stable iodine in representative surface soils, and sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at numerous nuclear facilities in the United States, where anthropogenic {sup 129}I from prior nuclear fuel processing activities poses an environmental risk. The surface soil samples were chosen for their geographic locations (e.g., near the ocean or nuclear facilities) and for their differing physico-chemical characteristics (organic matter, texture, etc). Extracted solutions were analyzed by IC and ICP-MS methods to determine iodine concentrations and to examine iodine speciation (iodide, iodate, and organic iodine). In natural soils, iodine is mostly (nearly 90% of total iodine) present as organic species, while inorganic iodine becomes important (up to 50%) only in sediments with low organic matter. Results from laboratory column studies, aimed at examining transport of different iodine species, showed much greater retardation of 4-iodoaniline than iodide or iodate. Careful attention must be given to potential interconversion among species when interpreting the biogeochemical behavior of iodine in the environment. In addition to speciation, input concentration and residence time effects will influence the biogeochemical cycling of anthropogenic 129I deposited on surface soils.

  15. Geochemical Cycling of Iodine Species in Soils

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Q; Moran, J E; Blackwood, V

    2007-08-23

    Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine in soils is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we applied new analytical techniques to study the content and speciation of stable iodine in representative surface soils, and sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at numerous nuclear facilities in the United States, where anthropogenic {sup 129}I from prior nuclear fuel processing activities poses an environmental risk. The surface soil samples were chosen for their geographic locations (e.g., near the ocean or nuclear facilities) and for their differing physico-chemical characteristics (organic matter, texture, etc). Extracted solutions were analyzed by IC and ICP-MS methods to determine iodine concentrations and to examine iodine speciation (iodide, iodate, and organic iodine). In natural soils, iodine is mostly (nearly 90% of total iodine) present as organic species, while inorganic iodine becomes important (up to 50%) only in sediments with low organic matter. Results from laboratory column studies, aimed at examining transport of different iodine species, showed much greater retardation of 4-iodoaniline than iodide or iodate. Careful attention must be given to potential interconversion among species when interpreting the biogeochemical behavior of iodine in the environment. In addition to speciation, input concentration and residence time effects will influence the biogeochemical cycling of anthropogenic 129I deposited on surface soils.

  16. Geochemical Fate and Transport of Diphenhydramine and Cetirizine in Soil

    Science.gov (United States)

    Wireman, R.; Rutherford, C. J.; Vulava, V. M.; Cory, W. C.

    2015-12-01

    Pharmaceuticals compounds presence in natural soils and water around the world has become a growing concern. These compounds are being discharged into the environment through treated wastewater or municipal sludge applications. The main goal of this study is determine their geochemical fate in natural soils. In this study we investigated sorption and transport behavior of diphenhydramine (DPH) and cetirizine (CTZ) in natural soils. These two commonly-used antihistamines are complex aromatic hydrocarbons with polar functional groups. Two clean acidic soils (pH~4.5) were used for these studies - an A-horizon soil that had higher organic matter content (OM, 7.6%) and a B-horizon soil that had lower OM (1.6%), but higher clay content (5.1%). Sorption isotherms were measured using batch reactor experiments. Data indicated that sorption was nonlinear and that it was stronger in clay-rich soils. The pKa's of DPH and CTZ are 8.98 and 8.27 respectively, i.e., these compounds are predominantly in cationic form at soil pH. In these forms, they preferentially sorb to negatively charged mineral surfaces (e.g., clay) present in the soils. Soil clay mineral characterization indicated that kaolinite was the dominant clay mineral present along with small amount of montmorillonite. The nonlinear sorption isotherms were fitted with Freundlich model. Transport behavior of both compounds was measured using glass chromatography columns. As expected both DPH and CTZ were strongly retained in the clay-rich soil as compared with OM-rich soil. The asymmetrical shape of the breakthrough curves indicated that there were likely two separate sorption sites in the soil, each with different reaction rates with each compound. A two-region advection-dispersion transport code was used to model the transport breakthrough curves. There was no evidence of transformation or degradation of the compounds during our sorption and transport studies.

  17. Soil Geochemical Control Over Nematode Populations in Bull Pass, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Poage, M. A.; Barrett, J. E.; Virginia, R. A.; Wall, D. H.

    2005-12-01

    The McMurdo Dry Valleys occupy the largest ice-free region of Antarctica and are characterized by climatic conditions among the most extreme on Earth. Despite the harsh environmental conditions, some soils of the dry valleys host simple low-diversity ecosystems dominated by microbes and several taxa of metazoans, predominantly nematodes. Distributions, abundance, and diversity of these biota appear to be related to the highly variable soil geochemistry (pH, conductivity, nitrate, sulfate, chloride) of the dry valleys. Bull Pass is a glacially carved valley within the dry valleys. An ancient lake margin near the valley floor creates a continuous gradient spanning the full range of geochemical parameters found across the entire McMurdo Dry Valleys system. This unique setting provides the opportunity to systematically investigate the soil geochemical control on local biodiversity and establish, on the spatial scale of hundreds of meters, correlations between nematode populations and individual geochemical parameters that have application at the regional scale. We measured soil geochemistry and nematode population data from a 1500-meter transect across this ancient lake margin. There were significant negative correlations between live nematode abundance and concentrations of soil nitrate, sulfate and chloride as well as total soil salinity, consistent with recent laboratory experiments showing strong salinity inhibition of nematode survival. A logistical regression analysis based on a compilation of published datasets from across the dry valleys was designed to calculate the probably of live nematode populations occurring given a particular soil chemistry, using the dataset from the Bull Pass transect as a case study to field-test the model. Small-scale chemical and biological gradients can provide insights on the distribution of soil biota at much larger regional scales.

  18. Geochemical variability of copper and iron in Oman margin sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.

    : Microchem. J.: 91(1); 2009; 111-117 Geochemical variability of copper and iron in Oman Margin sediments R. ALAGARSAMY * Chemical Oceanography Division, National Institute of Oceanography, Council of Scientific and Industrial Research (C... in the upper 100 mm. The Mn 5 distribution in core 12687#8 (Fig. 3d) showed a similar distribution to that observed for copper. As determined by sequential leaching, however, there was no detectable non-detrital Mn observed in core 12687#10 (only Mn 5...

  19. Geostatistical discrimination between different sources of soil pollutants using a magneto-geochemical data set.

    Science.gov (United States)

    Zawadzki, Jarosław; Szuszkiewicz, Marcin; Fabijańczyk, Piotr; Magiera, Tadeusz

    2016-12-01

    The primary goal of this work was to distinguish between soil pollution from long-range and local transport of atmospheric pollutants using soil magnetometry supported by geochemical analyses. The study area was located in the Izery region of Poland (within the "Black Triangle" region, which is the nickname for one of Europe's most polluted areas, where Germany, Poland and the Czech Republic meet). One site of the study area was situated in the Forest Glade and was exposed to anthropogenic pollution from a former glasswork. The second site of the study area was located on a neighboring hill (Granicznik) of which the western, northwestern and southwestern parts of the slope were exposed to the long-range transport of atmospheric pollutants from the Czech Republic, Germany and Poland. Magnetic susceptibility was measured on the soil surface and in the soil samples using a MS2 Bartington meter equipped with MS2D and MS2C sensors, respectively. Using soil magnetometry, it was possible to discriminate between long-range transport of atmospheric pollutants and anthropogenic pollution related to the former glasswork located in the Forest Glade. Additionally, using MS2C measurements and geochemical analyses of sixteen trace elements, it was possible to discriminate between natural and anthropogenic origins of a soil magnetic susceptibility signal. Our results indicate that the Forest Glade site is characterized by relatively significant anthropogenic translocation of topsoil horizons, presence of artefacts, more hot spots, very high spatial variability, and higher nugget effect than on the Granicznik Hill.

  20. Alaska Geochemical Database (AGDB) - Geochemical Data for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping,...

  1. Geochemical and physical properties of soils and shallow sediments at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Looney, B.B.; Eddy, C.A.; Ramdeen, M.; Pickett, J. (Savannah River Lab., Aiken, SC (USA)); Rogers, V. (Soil Conservation Service, Aiken, SC (USA). Savannah River Site Savannah River Lab., Aiken, SC (USA)); Scott, M.T.; Shirley, P.A. (Sirrine Environmental Consultants, Greenville, SC (USA))

    1990-08-31

    A program to characterize the geochemical and physical properties of the unimpacted soils and shallow sediments at the Savannah River Site (SRS) has been completed. The maximum, minimum, median, standard deviation, and mean values for metals, radionuclides, inorganic anions, organic compounds, and agricultural indicator parameters are summarized for six soil series that were identified as representative of the 29 soil series at SRS. The soils from unimpacted areas of SRS are typical of soils found in moderately aggressive weathering environments, including the southeastern United States. Appendix 8 organic compounds were detected in all samples. Since these constituents are not generally present in soil, this portion of the investigation was intended to assess possible laboratory artifacts. An additional objective of the SRS Soil Study was to determine if the composition of the split spoon sampler biased chemical analysis of the soils. Twenty-five duplicate samples were analyzed for a number of metals, radiological and agricultural parameters, and organics by two laboratories currently contracted with to analyze samples during waste site characterization. In all cases, the absolute values of the average differences are relatively small compared to the overall variability in the population. 31 refs., 14 figs., 48 tabs.

  2. Major- and Trace-Element Concentrations in Soils from Northern California: Results from the Geochemical Landscapes Project Pilot Study

    Science.gov (United States)

    Morrison, Jean M.; Goldhaber, Martin B.; Holloway, JoAnn M.; Smith, David B.

    2008-01-01

    In 2004, the U.S. Geological Survey (USGS), the Geological Survey of Canada (GSC), and the Mexican Geological Survey (Servicio Geologico Mexicano, or SGM) initiated pilot studies in preparation for a soil geochemical survey of North America called the Geochemical Landscapes Project. The purpose of this project is to provide a better understanding of the variability in chemical composition of soils in North America. The data produced by this survey will be used to construct baseline geochemical maps for regions within the continent. Two initial pilot studies were conducted: (1) a continental-scale study involving a north-south and east-west transect across North America and (2) a regional-scale study. The pilot studies were intended to test and refine sample design, sampling protocols, and field logistics for the full continental soils geochemical survey. Smith and others (2005) reported the results from the continental-scale pilot study. The regional-scale California study was designed to represent more detailed, higher resolution geochemical investigations in a region of particular interest that was identified from the low-sample-density continental-scale survey. A 20,000-km2 area of northern California (fig. 1), representing a wide variety of topography, climate, and ecoregions, was chosen for the regional-scale pilot study. This study area also contains diverse geology and soil types and supports a wide range of land uses including agriculture in the Sacramento Valley, forested areas in portions of the Sierra Nevada, and urban/suburban centers such as Sacramento, Davis, and Stockton. Also of interest are potential effects on soil geochemistry from historical hard rock and placer gold mining in the foothills of the Sierra Nevada, historical mercury mining in the Coast Range, and mining of base-metal sulfide deposits in the Klamath Mountains to the north. This report presents the major- and trace-element concentrations from the regional-scale soil geochemical

  3. The geochemical transformation of soils by agriculture and its dependence on soil erosion: An application of the geochemical mass balance approach.

    Science.gov (United States)

    Yoo, Kyungsoo; Fisher, Beth; Ji, Junling; Aufdenkampe, Anthony; Klaminder, Jonatan

    2015-07-15

    Agricultural activities alter elemental budgets of soils and thus their long-term geochemical development and suitability for food production. This study examined the utility of a geochemical mass balance approach that has been frequently used for understanding geochemical aspect of soil formation, but has not previously been applied to agricultural settings. Protected forest served as a reference to quantify the cumulative fluxes of Ca, P, K, and Pb at a nearby tilled crop land. This comparison was made at two sites with contrasting erosional environments: relatively flat Coastal Plain in Delaware vs. hilly Piedmont in Pennsylvania. Mass balance calculations suggested that liming not only replenished the Ca lost prior to agricultural practice but also added substantial surplus at both sites. At the relatively slowly eroding Coastal Plain site, the agricultural soil exhibited enrichment of P and less depletion of K, while both elements were depleted in the forest soil. At the rapidly eroding Piedmont site, erosion inhibited P enrichment. In similar, agricultural Pb contamination appeared to have resulted in Pb enrichment in the relatively slowly eroding Coastal Plain agricultural soil, while not in the rapidly eroding Piedmont soils. We conclude that agricultural practices transform soils into a new geochemical state where current levels of Ca, P, and Pb exceed those provided by the local soil minerals, but such impacts are significantly offset by soil erosion.

  4. GEOCHEMICAL MODELING OF F AREA SEEPAGE BASIN COMPOSITION AND VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Millings, M.; Denham, M.; Looney, B.

    2012-05-08

    From the 1950s through 1989, the F Area Seepage Basins at the Savannah River Site (SRS) received low level radioactive wastes resulting from processing nuclear materials. Discharges of process wastes to the F Area Seepage Basins followed by subsequent mixing processes within the basins and eventual infiltration into the subsurface resulted in contamination of the underlying vadose zone and downgradient groundwater. For simulating contaminant behavior and subsurface transport, a quantitative understanding of the interrelated discharge-mixing-infiltration system along with the resulting chemistry of fluids entering the subsurface is needed. An example of this need emerged as the F Area Seepage Basins was selected as a key case study demonstration site for the Advanced Simulation Capability for Environmental Management (ASCEM) Program. This modeling evaluation explored the importance of the wide variability in bulk wastewater chemistry as it propagated through the basins. The results are intended to generally improve and refine the conceptualization of infiltration of chemical wastes from seepage basins receiving variable waste streams and to specifically support the ASCEM case study model for the F Area Seepage Basins. Specific goals of this work included: (1) develop a technically-based 'charge-balanced' nominal source term chemistry for water infiltrating into the subsurface during basin operations, (2) estimate the nature of short term and long term variability in infiltrating water to support scenario development for uncertainty quantification (i.e., UQ analysis), (3) identify key geochemical factors that control overall basin water chemistry and the projected variability/stability, and (4) link wastewater chemistry to the subsurface based on monitoring well data. Results from this study provide data and understanding that can be used in further modeling efforts of the F Area groundwater plume. As identified in this study, key geochemical factors

  5. GEMAS: Geochemical Distribution of Thallium in European Soil

    Science.gov (United States)

    Demetriades, Alecos; Birke, Manfred; Reimann, Clemens; Mann, Alan; Kaminari, Maria

    2014-05-01

    Thallium concentrations are reported for the Vesuvius, Campi Felgrei and Mount Vulture); similar anomalous patterns are shown by Be, Pd and Pt. Most granitic intrusions are also marked by high Tl values (e.g., northern Portugal, Massif Central in France, and Bohemian Massif in Czechia). The median Tl concentration of Ap soil samples in the mobile metal ion (MMI®) partial extraction is 0.0006 mg/kg, and almost 50% of all samples report concentrations below detection. There is no pronounced difference between northern and southern Europe anymore, and the ice age limit of the last glaciation remains invisible. The main anomaly is related to the alkaline volcanic rocks in Italy. Many granitic intrusions are indicated by somewhat enhanced Tl concentrations (e.g., northern Portugal, north-western Spain, Massif Central in France, south-west England, and Bohemian Massif in Czechia). An interesting NE to SW anomalous pattern occurs in Scotland, partly following the Great Glen fault, and occurrences of granitic intrusions. Almost all of central Europe is marked by enhanced Tl values, and one wonders whether agriculture might have had an impact on this unusual pattern. Finally, the GEMAS data set defines the geochemical background variation of Tl in aqua regia and MMI® extraction for European agricultural and grazing land soil at the 2008 timeline.

  6. Geochemical Implication of Rare Earth Elements in Process of Soil Development

    Institute of Scientific and Technical Information of China (English)

    黄成敏; 龚子同

    2001-01-01

    The geochemical characteristics and behavior of rare earth elements (REE) in soils developed on the basalts in the northern part of Hainan Island erupted in different time were studied as well as the REE partition in the soil-formation process and its implication on soil development degree. The results show that the total REE content in soils is correlative with soil age significantly and can be selected as the index to show soil evolution. With the soil developing intensively, light rare earth elements (LREE) gain and heavy rare earth elements (HREE) lose. The trends of positive Ce-anomaly and negative Eu-anomaly are remarkable with soil development.

  7. Comparison on humus and soil geochemical baselines in Southern Finland

    Science.gov (United States)

    Minolfi, Giulia; Tarvainen, Timo; Jarva, Jaana

    2016-04-01

    Humus has been recognized since a survey in 1977 (Allen and Steinnes, 1980) as one of the best sampling media for mapping regional environmental contamination because of the strong geochemical contrast between anomalous and background concentrations resulting from its capacity to accumulate high levels of trace metals. This study is in the framework of the comparison between humus, topsoil and moss deposition data, in order to analyze the humus behavior and to find possible similarities to underlying geology and long-range atmospheric deposition. The analyzed samples are part of a geochemical mapping programme carried out by the Geological Survey of Finland (GTK); subsoil, topsoil and humus samples have been collected in a large area in Southern Finland since 2002. 816 sample pairs (humus and topsoil samples) were selected for statistical analysis. Statistical graphs, like histograms, CP plots and box plots, were realized for 31 elements, and showed that most of the elements have completely different distribution of concentrations in humus and in topsoil samples. Then the correlation between the element concentrations in humus and minerogenic topsoil has been evaluated measuring the Spearman rank correlation value and elaborating scatter plots between the element concentrations in humus and minerogenic topsoil, and between the content of the element vs. the content of organic C. The concentrations of some elements, like K, Mg, Fe, Al, in humus samples are controlled by the content of mineral matter, derived by the soil dust. Other elements, such as As, Bi, Cd, Co, Cu, Mn, Mo, Ni, Pb, Rb, Th, V and Zn showed evident outliers, with probable anthropogenic origin. In order to explain these anomalous high values in humus, the geographic distributions of these elements in humus and topsoil were analyzed and then compared to the deposition data obtained by the national moss data. High values appear in areas where the anthropogenic impact is strong, like the Harjavalta

  8. Soil variability in engineering applications

    Science.gov (United States)

    Vessia, Giovanna

    2014-05-01

    Natural geomaterials, as soils and rocks, show spatial variability and heterogeneity of physical and mechanical properties. They can be measured by in field and laboratory testing. The heterogeneity concerns different values of litho-technical parameters pertaining similar lithological units placed close to each other. On the contrary, the variability is inherent to the formation and evolution processes experienced by each geological units (homogeneous geomaterials on average) and captured as a spatial structure of fluctuation of physical property values about their mean trend, e.g. the unit weight, the hydraulic permeability, the friction angle, the cohesion, among others. The preceding spatial variations shall be managed by engineering models to accomplish reliable designing of structures and infrastructures. Materon (1962) introduced the Geostatistics as the most comprehensive tool to manage spatial correlation of parameter measures used in a wide range of earth science applications. In the field of the engineering geology, Vanmarcke (1977) developed the first pioneering attempts to describe and manage the inherent variability in geomaterials although Terzaghi (1943) already highlighted that spatial fluctuations of physical and mechanical parameters used in geotechnical designing cannot be neglected. A few years later, Mandelbrot (1983) and Turcotte (1986) interpreted the internal arrangement of geomaterial according to Fractal Theory. In the same years, Vanmarcke (1983) proposed the Random Field Theory providing mathematical tools to deal with inherent variability of each geological units or stratigraphic succession that can be resembled as one material. In this approach, measurement fluctuations of physical parameters are interpreted through the spatial variability structure consisting in the correlation function and the scale of fluctuation. Fenton and Griffiths (1992) combined random field simulation with the finite element method to produce the Random

  9. Soil-geochemical factors of rocket fuel migration in the landscape

    Science.gov (United States)

    Krechetov, P. P.; Kasimov, N. S.; Koroleva, T. V.

    2015-10-01

    The effect of different soil-geochemical factors on the migration of asymmetric dimethylhydrazine (UDMH) in the landscape has been studied. Experimental studies have been performed on soil and rock samples with specified parameters of the material composition. The effect of organic matter, acid-base properties, particle size distribution, and mineralogy on the decrease in the concentration of UDMH in equilibrium solutions has been studied. It has been found that the soil-geochemical factors are arranged in the following series according to the effect on UDMH mobility: acid-base properties > organic matter content > clay fraction mineralogy > particle size distribution.

  10. Landscape and bio- geochemical strategy for monitoring transformation and reclamation of the soil mining sites

    Science.gov (United States)

    Korobova, Elena

    2010-05-01

    Sites of active or abandoned mining represent areas of considerable technogenic impact and need scientifically ground organization of their monitoring and reclamation. The strategy of monitoring and reclamation depends on the scale and character of the physical, chemical and biological consequences of the disturbances. The geochemical studies for monitoring and rehabilitation of the career-dump complexes should methodically account of formation of the particular new landforms and the changes in circulation of the remobilized elements of the soil cover. However, the general strategy should account of both the initial and transformed landscape geochemical structure of the area with due regard to the natural and new content of chemical elements in the environmental components. For example the tailings and waste rocks present new geochemical fields with specifically different concentration of chemical elements that cause formation of new geochemical barriers and landscapes. The way of colonization of the newly formed landscapes depends upon the new geochemical features of the technogenic environment and the adaptive ability of local and intrusive flora. The newly formed biogeochemical anomalies need organization of permanent monitoring not only within the anomaly itself but also of its impact zones. Spatial landscape geochemical monitoring combined with bio-geochemical criteria of threshold concentrations seems to be a helpful tool for decision making on reclamation and operation of the soil mining sites to provide a long-term ecologically sustainable development of the impact zone as a whole.

  11. Central Colorado Assessment Project (CCAP)-Geochemical data for rock, sediment, soil, and concentrate sample media

    Science.gov (United States)

    Granitto, Matthew; DeWitt, Ed H.; Klein, Terry L.

    2010-01-01

    This database was initiated, designed, and populated to collect and integrate geochemical data from central Colorado in order to facilitate geologic mapping, petrologic studies, mineral resource assessment, definition of geochemical baseline values and statistics, environmental impact assessment, and medical geology. The Microsoft Access database serves as a geochemical data warehouse in support of the Central Colorado Assessment Project (CCAP) and contains data tables describing historical and new quantitative and qualitative geochemical analyses determined by 70 analytical laboratory and field methods for 47,478 rock, sediment, soil, and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed either in the analytical laboratories of the USGS or by contract with commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects. In addition, geochemical data from 7,470 sediment and soil samples collected and analyzed under the Atomic Energy Commission National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program (henceforth called NURE) have been included in this database. In addition to data from 2,377 samples collected and analyzed under CCAP, this dataset includes archived geochemical data originally entered into the in-house Rock Analysis Storage System (RASS) database (used by the USGS from the mid-1960s through the late 1980s) and the in-house PLUTO database (used by the USGS from the mid-1970s through the mid-1990s). All of these data are maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB and from the NURE database were used to generate most of this dataset. In addition, USGS data that have been excluded previously from the NGDB because the data predate earliest USGS geochemical databases, or were once excluded for programmatic reasons

  12. Evaluation of the Single Dilute (0.43 M) Nitric Acid Extraction to Determine Geochemically Reactive Elements in Soil

    NARCIS (Netherlands)

    Groenenberg, Jan E.; Römkens, Paul F.A.M.; Zomeren, van André; Rodrigues, S.M.; Comans, Rob N.J.

    2017-01-01

    Recently a dilute nitric acid extraction (0.43 M) was adopted by ISO (ISO-17586:2016) as standard for extraction of geochemically reactive elements in soil and soil like materials. Here we evaluate the performance of this extraction for a wide range of elements by mechanistic geochemical modeling

  13. Geochemical and mineralogical maps for soils of the conterminous United States

    Science.gov (United States)

    Smith, David B.; Cannon, William F.; Woodruff, Laurel G.; Solano, Federico; Ellefsen, Karl J.

    2014-01-01

    The U.S. Geological Survey began sampling in 2007 for a low-density (1 site per 1,600 square kilometers, 4,857 sites) geochemical and mineralogical survey of soils in the conterminous United States as part of the North American Soil Geochemical Landscapes Project. The sampling protocol for the national-scale survey included, at each site, a sample from a depth of 0 to 5 centimeters, a composite of the soil A horizon, and a deeper sample from the soil C horizon or, if the top of the C horizon was at a depth greater than 1 meter, a sample from a depth of approximately 80–100 centimeters. The elements by methods that yield the total or near-total elemental content. The major mineralogical components in the samples from the soil A and C horizons were determined by a quantitative X-ray diffraction method using Rietveld refinement. Sampling in the conterminous United States was completed in 2010, with chemical and mineralogical analyses completed in May 2013. The resulting data set provides an estimate of the abundance and spatial distribution of chemical elements and minerals in soils of the conterminous United States and represents a baseline for soil geochemistry and mineralogy against which future changes may be recognized and quantified. This report releases geochemical and mineralogical maps along with a histogram, boxplot, and empirical cumulative distribution function plot for each element or mineral.

  14. The potential of lacquer-peel soil profiles for palaeo-geochemical analysis using XRF analysis

    NARCIS (Netherlands)

    Arnoldussen, Stijn; van Os, B.J.H.

    2015-01-01

    This paper discusses the suitability of hand-held XRF analysis to extract palaeo-geochemical information from lacquer-peel soil sections that have been taken to document pedological information at geological and archaeological sites. This not only allows the study of sections from archaeological and

  15. Geochemical and mineralogical data for soils of the conterminous United States

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — In 2007, the U.S. Geological Survey began a low-density (1 site per 1,600 sq. km., 4857 sites) geochemical and mineralogical survey of soils of the conterminous...

  16. A comparison study on detection of key geochemical variables and factors through three different types of factor analysis

    Science.gov (United States)

    Hoseinzade, Zohre; Mokhtari, Ahmad Reza

    2017-10-01

    Large numbers of variables have been measured to explain different phenomena. Factor analysis has widely been used in order to reduce the dimension of datasets. Additionally, the technique has been employed to highlight underlying factors hidden in a complex system. As geochemical studies benefit from multivariate assays, application of this method is widespread in geochemistry. However, the conventional protocols in implementing factor analysis have some drawbacks in spite of their advantages. In the present study, a geochemical dataset including 804 soil samples collected from a mining area in central Iran in order to search for MVT type Pb-Zn deposits was considered to outline geochemical analysis through various fractal methods. Routine factor analysis, sequential factor analysis, and staged factor analysis were applied to the dataset after opening the data with (additive logratio) alr-transformation to extract mineralization factor in the dataset. A comparison between these methods indicated that sequential factor analysis has more clearly revealed MVT paragenesis elements in surface samples with nearly 50% variation in F1. In addition, staged factor analysis has given acceptable results while it is easy to practice. It could detect mineralization related elements while larger factor loadings are given to these elements resulting in better pronunciation of mineralization.

  17. Geochemical characterization of elements in Vitis vinifera cv. Negroamaro grape berries grown under different soil managements.

    Science.gov (United States)

    Pepi, Salvatore; Coletta, Antonio; Crupi, Pasquale; Leis, Marilena; Russo, Sabrina; Sansone, Luigi; Tassinari, Renzo; Chicca, Milvia; Vaccaro, Carmela

    2016-04-01

    The present geochemical study concerns the impact of viticultural practices in the chemical composition of the grape cultivar "Negroamaro" in Apulia, a southern Italian region renowned for its quality wine. Three types of soil management (SM), two cover cropping with different mixtures, and a soil tillage were considered. For each SM, the vines were irrigated according to two irrigation levels. Chemical composition of soil and of berries of Vitis vinifera cultivar "Negroamaro" were analyzed by X-ray fluorescence, inductively coupled plasma-mass spectrometry and multivariate statistics (linear discrimination analysis). In detail, we investigated major and trace elements behavior in the soil according to irrigation levels, the related index of bioaccumulation (BA) and the relationship between trace element concentration and soil management in "Negroamaro" grapes. The results indicate that soil management affects the mobility of major and trace elements. A specific assimilation of these elements in grapes from vines grown under different soil management was confirmed by BA. Multivariate statistics allowed to associate the vines to the type of soil management. This geochemical characterization of elements could be useful to develop fingerprints of vines of the cultivar "Negroamaro" according to soil management and geographical origin.

  18. Ecological-geochemical assessment of soil of the Dniester canyon.

    Directory of Open Access Journals (Sweden)

    Zorin D.O.

    2008-05-01

    Full Text Available An method of calculation of background and anomalous heavy metals, petroleum products and pesticides in soil of the Dniester canyon area for the environmental assessment of the future national park.

  19. Factors of the accumulation of heavy metals and metalloids at geochemical barriers in urban soils

    Science.gov (United States)

    Kosheleva, N. E.; Kasimov, N. S.; Vlasov, D. V.

    2015-05-01

    The bulk contents and concentrations of mobile (extracted by an ammonium acetate buffer with EDTA) Cd, Pb, Sb, As, Bi, Zn, and Cu were determined in the surface horizons of urban soils in the Eastern administrative okrug of Moscow. The regression analysis showed that the accumulation of these metals and metalloids in the soils is controlled by the physicochemical soil properties and by number of anthropogenic factors and landscape conditions (geochemical position, type of loose deposits, character of land use, dust load, vehicle emissions, building pattern, percent of green areas, and the extent of sealed soils). The precipitation of studied elements on the geochemical barriers had the following regularities: Cd, Cu, and Zn accumulated on the alkaline barriers; Bi, Sb, As, Cu, Pb, and Zn, on chemisorption barriers; Sb, As, and Pb, on organomineral barriers; and Cd and Cu, on the sorption-sedimentation barriers. Technogenic transformation of the physicochemical properties of urban soils resulted in the increase of the mean bulk contents of heavy metals and metalloids by 33-99%; the portion of elements fixed on the geochemical barriers increased by 26-50%.

  20. [Environmental geochemical baseline of heavy metals in soils of the Ili river basin and pollution evaluation].

    Science.gov (United States)

    Zhao, Xin-Ru; Nasier, Telajin; Cheng, Yong-Yi; Zhan, Jiang-Yu; Yang, Jian-Hong

    2014-06-01

    Environmental geochemical baseline models of Cu, Zn, Pb, As, Hg were established by standardized method in the ehernozem, chestnut soil, sierozem and saline soil from the Ili river valley region. The theoretical baseline values were calculated. Baseline factor pollution index evaluation method, environmental background value evaluation method and heavy metal cleanliness evaluation method were used to compare soil pollution degrees. The baseline factor pollution index evaluation showed that As pollution was the most prominent among the four typical types of soils within the river basin, with 7.14%, 9.76%, 7.50% of sampling points in chernozem, chestnut soil and sierozem reached the heavy pollution, respectively. 7.32% of sampling points of chestnut soil reached the permitted heavy metal Pb pollution index in the chestnut soil. The variation extent of As and Pb was the largest, indicating large human disturbance. Environmental background value evaluation showed that As was the main pollution element, followed by Cu, Zn and Pb. Heavy metal cleanliness evaluation showed that Cu, Zn and Pb were better than cleanliness level 2 and Hg was the of cleanliness level 1 in all four types of soils. As showed moderate pollution in sierozem, and it was of cleanliness level 2 or better in chernozem, chestnut soil and saline-alkali soil. Comparing the three evaluation systems, the baseline factor pollution index evaluation more comprehensively reflected the geochemical migration characteristics of elements and the soil formation processes, and the pollution assessment could be specific to the sampling points. The environmental background value evaluation neglected the natural migration of heavy metals and the deposition process in the soil since it was established on the regional background values. The main purpose of the heavy metal cleanliness evaluation was to evaluate the safety degree of soil environment.

  1. Geochemical background values for trace elements in arable soils developed from sedimentary rocks of glacial origin.

    Science.gov (United States)

    Czarnowska, K; Gworek, B

    1990-12-01

    The total content of trace elements was examined in some arable soils developed from boulder loam and silt formations of the Middle Poland and Baltic glaciations (62 profiles). Mean element concentrations calculated on the basis of chemical and statistical analyses were as follows: Mn = 322; Zn = 36; Cr = 30; Ni = 12.7; Pb = 10.3; Cu = 8.8; Co = 4.7; and Cd = 0.27 in mg kg(-1) of soil dry weight. The authors propose to accept these figures as the geochemical background values for soils derived from sedimentary rocks of glacial origin.

  2. Geochemical Modeling of Trivalent Chromium Migration in Saline-Sodic Soil during Lasagna Process: Impact on Soil Physicochemical Properties

    Directory of Open Access Journals (Sweden)

    Salihu Lukman

    2014-01-01

    Full Text Available Trivalent Cr is one of the heavy metals that are difficult to be removed from soil using electrokinetic study because of its geochemical properties. High buffering capacity soil is expected to reduce the mobility of the trivalent Cr and subsequently reduce the remedial efficiency thereby complicating the remediation process. In this study, geochemical modeling and migration of trivalent Cr in saline-sodic soil (high buffering capacity and alkaline during integrated electrokinetics-adsorption remediation, called the Lasagna process, were investigated. The remedial efficiency of trivalent Cr in addition to the impacts of the Lasagna process on the physicochemical properties of the soil was studied. Box-Behnken design was used to study the interaction effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil pH, electroosmotic volume, soil electrical conductivity, current, and remedial efficiency of trivalent Cr in saline-sodic soil that was artificially spiked with Cr, Cu, Cd, Pb, Hg, phenol, and kerosene. Overall desirability of 0.715 was attained at the following optimal conditions: voltage gradient 0.36 V/cm; polarity reversal rate 17.63 hr; soil pH 10.0. Under these conditions, the expected trivalent Cr remedial efficiency is 64.75 %.

  3. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    Directory of Open Access Journals (Sweden)

    Anđelković Darko H.

    2012-01-01

    Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

  4. Geochemical research of soil and attic dust in Litija area, Slovenia

    Directory of Open Access Journals (Sweden)

    Mateja Jemec

    2007-12-01

    Full Text Available Geochemical research was carried as part of the environmental research project at the Geological Survey of Slovenia. The aim of the project was to determine the impact on the environment caused by heavy metals released in the environment during mining and smeltingactivity in the area of Litija. The samples of attic dust and soil (0–5 cm were examined with the view to separate the natural distribution of chemical elements in the environment from the one caused by past mining and smelting activities. Based on chemically analyses we determine two main geochemical associations and their spatial distribution. First geochemical association (Al, Co, Ce, K, La, Li, Nb, Rb, Sc, Ta, Th in Ti is influencedmainlybynatural source, the second man-made association (As, Cd, Hg, Pb, Sb, Sn in Zn is caused mainly because of mining and lead smelting.

  5. Geochemical and mineralogical data for soils of the conterminous United States

    Science.gov (United States)

    Smith, David B.; Cannon, William F.; Woodruff, Laurel G.; Solano, Federico; Kilburn, James E.; Fey, David L.

    2013-01-01

    In 2007, the U.S. Geological Survey initiated a low-density (1 site per 1,600 square kilometers, 4,857 sites) geochemical and mineralogical survey of soils of the conterminous United States as part of the North American Soil Geochemical Landscapes Project. Sampling and analytical protocols were developed at a workshop in 2003, and pilot studies were conducted from 2004 to 2007 to test and refine these recommended protocols. The final sampling protocol for the national-scale survey included, at each site, a sample from a depth of 0 to 5 centimeters, a composite of the soil A horizon, and a deeper sample from the soil C horizon or, if the top of the C horizon was at a depth greater than 1 meter, from a depth of approximately 80–100 centimeters. The elements by methods that yield the total or near-total elemental content. The major mineralogical components in the samples from the soil A and C horizons were determined by a quantitative X-ray diffraction method using Rietveld refinement. Sampling in the conterminous United States was completed in 2010, with chemical and mineralogical analyses completed in May 2013. The resulting dataset provides an estimate of the abundance and spatial distribution of chemical elements and minerals in soils of the conterminous United States and represents a baseline for soil geochemistry and mineralogy against which future changes may be recognized and quantified. This report (1) describes the sampling, sample preparation, and analytical methods used; (2) gives details of the quality control protocols used to monitor the quality of chemical and mineralogical analyses over approximately six years; and (3) makes available the soil geochemical and mineralogical data in downloadable tables.

  6. Pilot study of the application of Tellus airborne radiometric and soil geochemical data for radon mapping.

    Science.gov (United States)

    Appleton, J D; Miles, J C H; Green, B M R; Larmour, R

    2008-10-01

    The scope for using Tellus Project airborne gamma-ray spectrometer and soil geochemical data to predict the probability of houses in Northern Ireland having high indoor radon concentrations is evaluated, in a pilot study in the southeast of the province, by comparing these data statistically with in-house radon measurements. There is generally good agreement between radon maps modelled from the airborne radiometric and soil geochemical data using multivariate linear regression analysis and conventional radon maps which depend solely on geological and indoor radon data. The radon maps based on the Tellus Project data identify some additional areas where the radon risk appears to be relatively high compared with the conventional radon maps. One of the ways of validating radon maps modelled on the Tellus Project data will be to carry out additional indoor measurements in these areas.

  7. Spatial Variability of Soil Morphorlogical and Physico-Chemical ...

    African Journals Online (AJOL)

    Spatial Variability of Soil Morphorlogical and Physico-Chemical Properties in ... the spatial variability of soil morphological, physical and chemical properties in the ... organic matter (g/kg), and available phosphorus were extremely variable soil ...

  8. Geochemical and physical properties of wetland soils at the Savannah River site

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, K.L; Rogers, V.A.; Conner, S.P.; Cummings, C.L.; Gladden, J.B.; Weber, J.M.

    1996-05-01

    The Savannah River Site (SRS), located in Aiken, Allendale, and Barnwell Counties, South Carolina, is a nuclear production facility operated for the U.S. Department of Energy (DOE) by Westinghouse Savannah River Company (WSRC). To facilitate future human health and ecological risk assessments, treatability studies, remedial investigations, and feasibility studies for its wetland areas, SRS needs a database of background geochemical and physical properties of wetland soils. These data are needed for comparison to data collected from wetland soils that may have been affected by SRS operations. SRS contains 36,000 acres of wetlands and an additional 5,000 acres of bottom land soils subject to flooding. Recent studies of wetland soils near various waste units at SRS show that some wetlands have been impacted by releases of contaminants resulting from SRS operations (WSRC, 1992). Waste waters originating from the operations facilities typically have been discharged into seepage basins located in upland soils, direct discharge of waste water to wetland areas has been minimal. This suggests that impacted wetland areas have been affected indirectly as a result of transport mechanisms such as surface runoff, groundwater seeps, fluvial or sediment transport, and leaching. Looney et al. (1990) conducted a study to characterize the geochemical and physical properties of upland soils and shallow sediments on the SRS. A primary objective of the upland study was to collect the data needed to assess the qualitative and quantitative impacts of SRS operations on the environment. By comparing the upland soils data to data collected from waste units located in similar soils, SRS impacts could be assessed. The data were also intended to aid in selection of remediation alternatives. Because waste units at SRS have historically been located in upland areas, wetland soils were not sampled. (Abstract Truncated)

  9. Soil Aeration Variability as Affected by Reoxidation

    Institute of Scientific and Technical Information of China (English)

    A.WOLI(N)SKA; Z.ST(E)PNIEWSKA

    2013-01-01

    The interplay between soil physical parameters during the recovery from anoxic stresses (reoxidation) is largely unrecognized.This study was conducted to characterise the soil aeration status and derive correlations between variable aeration factors during reoxidation.Surface layers (0-30 cm) of three soil types,Haplic Phaeozem,Mollic Gleysol,and Eutric Cambisol (FAO soil group),were selected for analysis.The moisture content was determined for a range of pF values (0,1.5,2.2,2.7,and 3.2),corresponding to the available water for microorganisms and plant roots.The variability of a number of soil aeration parameters,such as water potential (pF),air-filled porosity (Eg),oxygen diffusion rate (ODR),and redox potential (Eh),were investigated.These parameters were found to be interrelated in most cases.There were significant (P < 0.001) negative correlations of pF,Eg,and ODR with Eh.A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment.These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.

  10. Provenance and geochemical behavior of fluorine in the soils of an endemic fluorosis belt, central Iran

    Science.gov (United States)

    Dehbandi, Reza; Moore, Farid; Keshavarzi, Behnam

    2017-05-01

    The concentration of fluorine, major, trace and rare earth elements (REEs) were used to estimate the probable sources and provenance of fluorine in the soils of an endemic fluorosis belt in central Iran. Total fluorine (TF) in soils varied from 146 to 406 mg/kg with a mean of 277.5 mg/kg. Calculated enrichment factor (EF) and single factor pollution index (SFPI) revealed that the majority of soil samples were moderately contaminated by fluorine. The very strong positive correlation of TF with weathering indices and soil's fine sized fractions indicated that chemical weathering and alteration of parent rocks/soils are the main controlling factors of fluorine behavior in soils. Fluorine affinity to immobile transition trace elements and REEs suggested the role of heavy minerals as the potential F host phases. Modal mineralogy along with SEM-EDX analysis indicated that apatite, fluorapophyllite, epidote, biotite, muscovite and chlorite, as well as, clay minerals are the main F-bearing minerals in the studied soils. Discriminant, bivariate and ternary diagrams of elemental compositions displayed similar geochemical signature of soils to intermediate-acidic rocks and local shales. Based on the weathering indices, soils were immature and showed a non-steady state weathering trend from upper continental crust (UCC), acidic and intermediate igneous source rocks towards shale composition possibly due to mixing of moderately weathered and un-weathered sources of different primary compositions.

  11. Quantifying soil and critical zone variability in a forested catchment through digital soil mapping

    Science.gov (United States)

    Holleran, M.; Levi, M.; Rasmussen, C.

    2015-01-01

    Quantifying catchment-scale soil property variation yields insights into critical zone evolution and function. The objective of this study was to quantify and predict the spatial distribution of soil properties within a high-elevation forested catchment in southern Arizona, USA, using a combined set of digital soil mapping (DSM) and sampling design techniques to quantify catchment-scale soil spatial variability that would inform interpretation of soil-forming processes. The study focused on a 6 ha catchment on granitic parent materials under mixed-conifer forest, with a mean elevation of 2400 m a.s.l, mean annual temperature of 10 °C, and mean annual precipitation of ~ 85 cm yr-1. The sample design was developed using a unique combination of iterative principal component analysis (iPCA) of environmental covariates derived from remotely sensed imagery and topography, and a conditioned Latin hypercube sampling (cLHS) scheme. Samples were collected by genetic horizon from 24 soil profiles excavated to the depth of refusal and characterized for soil mineral assemblage, geochemical composition, and general soil physical and chemical properties. Soil properties were extrapolated across the entire catchment using a combination of least-squares linear regression between soil properties and selected environmental covariates, and spatial interpolation or regression residual using inverse distance weighting (IDW). Model results indicated that convergent portions of the landscape contained deeper soils, higher clay and carbon content, and greater Na mass loss relative to adjacent slopes and divergent ridgelines. The results of this study indicated that (i) the coupled application of iPCA and cLHS produced a sampling scheme that captured the greater part of catchment-scale soil variability; (ii) application of relatively simple regression models and IDW interpolation of residuals described well the variance in measured soil properties and predicted spatial correlation of soil

  12. Geochemical and Isotopic (Sr, U) Tracing of Weathering Processes Controlling the Recent Geochemical Evolution of Soil Solutions in the Strengbach Catchment (Vosges, France)

    Science.gov (United States)

    Chabaux, F. J.; Prunier, J.; Pierret, M.; Stille, P.

    2012-12-01

    The characterization of the present-day weathering processes controlling the chemical composition of waters and soils in natural ecosystems is an important issue to predict and to model the response of ecosystems to recent environmental changes. It is proposed here to highlight the interest of a multi-tracer geochemical approach combining measurement of major and trace element concentrations along with U and Sr isotopic ratios to progress in this topic. This approach has been applied to the small granitic Strengbah Catchment, located in the Vosges Mountain (France), used and equipped as a hydro-geochemical observatory since 1986 (Observatoire Hydro-Géochimique de l'Environnement; http://ohge.u-strasbg.fr). This study includes the analysis of major and trace element concentrations and (U-Sr) isotope ratios in soil solutions collected within two soil profiles located on two experimental plots of this watershed, as well as the analysis of soil samples and vegetation samples from these two plots The depth variation of elemental concentration of soil solutions confirms the important influence of the vegetation cycling on the budget of Ca, K, Rb and Sr, whereas Mg and Si budget in soil solutions are quasi exclusively controlled by weathering processes. Variation of Sr, and U isotopic ratios with depth also demonstrates that the sources and biogeochemical processes controlling the Sr budget of soil solutions is different in the uppermost soil horizons and in the deeper ones, and clearly influence by the vegetation cycling.

  13. Connectivity clues from short-term variability in settlement and geochemical tags of mytilid mussels

    Science.gov (United States)

    Fodrie, F. Joel; Becker, Bonnie J.; Levin, Lisa A.; Gruenthal, Kristen; McMillan, Pat A.

    2011-01-01

    The use of geochemical tags in calcified structures of fish and invertebrates is an exciting tool for investigating larval population connectivity. Tag evaluation over relatively short intervals (weeks) may detect environmental and ecological variability at a temporal scale highly relevant to larval transport and settlement. We collected newly settled mussels ( Mytilus californianus and M. galloprovincialis) weekly during winter/spring of 2002 along the coast of San Diego, CA, USA, at sites on the exposed coast (SIO) and in a protected coastal bay (HI), to investigate temporal patterns of geochemical tags in mussel shells. Analyses of post-settlement shell via LA-ICP-MS revealed statistically significant temporal variability for all elements we examined (Mg, Mn, Cu, Sr, Cd, Ba, Pb and U). Despite this, our ability to distinguish multielemental signatures between sites was largely conserved. Throughout our 13-week study, SIO and HI mussels could be chemically distinguished from one another in 78-87% of all cases. Settlement varied between 2 and 27 settlers gram-byssus -1 week -1 at SIO and HI, and both sites were characterized by 2-3 weeks with "high" settlement. Geochemical tags recorded in early larval shell of newly settled mussels differed between "high" and "low" settlement weeks at both sites (MANOVA), driven by Mg and Sr at SIO (p = 0.013) and Sr, Cd, Ba and Pb at HI (p < 0.001). These data imply that shifts in larval sources or transport corridors were responsible for observed settlement variation, rather than increased larval production. In particular, increased settlement at HI was observed concurrent with the appearance of geochemical tags (e.g., elevated Cd), suggesting that those larvae were retained in upwelled water near the mouth of the bay. Such shifts may reflect short-term changes in connectivity among sites due to altered transport corridors, and influence the demography of local populations.

  14. Using geochemical indicators to distinguish high biogeochemical activity in floodplain soils and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Kenwell, Amy [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Navarre-Sitchler, Alexis, E-mail: asitchle@mines.edu [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Prugue, Rodrigo [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Spear, John R. [Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Hering, Amanda S. [Department of Applied Mathematics and Statistics, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Maxwell, Reed M. [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Carroll, Rosemary W.H. [Desert Research Institute, Division of Hydrologic Sciences, 2215 Raggio Parkway, Reno, NV 89512 (United States); Williams, Kenneth H. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-09-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict potential elevated rates of biogeochemical activity (microbial “hotspots”) in subsurface environments by correlating microbial DNA and aspects of the community structure with the spatial distribution of geochemical indicators in subsurface sediments. Multiple linear regression models of simulated precipitation leachate, HCl and hydroxylamine extractable iron and manganese, total organic carbon (TOC), and microbial community structure were used to identify sample characteristics indicative of biogeochemical hotspots within fluvially-derived aquifer sediments and overlying soils. The method has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 16 alluvial samples were taken from 8 sediment cores, and at the East River, 46 soil/sediment samples were collected across and perpendicular to 3 active meanders and an oxbow meander. Regression models using TOC and TOC combined with extractable iron and manganese results were determined to be the best fitting statistical models of microbial DNA (via 16S rRNA gene analysis). Fitting these models to observations in both contaminated and natural floodplain deposits, and their associated alluvial aquifers, demonstrates the broad applicability of the geochemical indicator based approach. - Highlights: • Biogeochemical characterization of alluvial floodplain soils and sediments was performed to investigate parameters that may indicate microbial hot spot formation. • A correlation between geochemical parameters (total organic carbon and

  15. VARIABLE CHARGE SOILS: MINERALOGY AND CHEMISTRY

    Energy Technology Data Exchange (ETDEWEB)

    Van Ranst, Eric; Qafoku, Nikolla; Noble, Andrew; Xu, Ren-Kou

    2016-09-19

    Soils rich in particles with amphoteric surface properties in the Oxisols, Ultisols, Alfisols, Spodosols and Andisols orders (1) are considered to be variable charge soils (2) (Table 1). The term “variable charge” is used to describe organic and inorganic soil constituents with reactive surface groups whose charge varies with pH and ionic concentration and composition of the soil solution. Such groups are the surface carboxyl, phenolic and amino functional groups of organic materials in soils, and surface hydroxyl groups of Fe and Al oxides, allophane and imogolite. The hydroxyl surface groups are also present on edges of some phyllosilicate minerals such as kaolinite, mica, and hydroxyl-interlayered vermiculite. The variable charge is developed on the surface groups as a result of adsorption or desorption of ions that are constituents of the solid phase, i.e., H+, and the adsorption or desorption of solid-unlike ions that are not constituents of the solid phase. Highly weathered soils and subsoils (e.g., Oxisols and some Ultisols, Alfisols and Andisols) may undergo isoelectric weathering and reach a “zero net charge” stage during their development. They usually have a slightly acidic to acidic soil solution pH, which is close to either the point of zero net charge (PZNC) (3) or the point of zero salt effect (PZSE) (3). They are characterized by high abundances of minerals with a point of zero net proton charge (PZNPC) (3) at neutral and slightly basic pHs; the most important being Fe and Al oxides and allophane. Under acidic conditions, the surfaces of these minerals are net positively charged. In contrast, the surfaces of permanent charge phyllosilicates are negatively charged regardless of ambient conditions. Variable charge soils therefore, are heterogeneous charge systems.

  16. Trace elements assessment in agricultural and desert soils of Aswan area, south Egypt: Geochemical characteristics and environmental impacts

    Science.gov (United States)

    Darwish, Mohamed Abdallah Gad; Pöllmann, Hebert

    2015-12-01

    Determination of chemical elements, Al, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, P, Pb, Sc, Sr, Ti, Y, and Zn have been performed in agricultural and desert soils and alfalfa (Medicago sativa) at Aswan area. Consequently, the pollution indices, univariate and multivariate statistical methods have been applied, in order to assess the geochemical characteristics of these elements and their impact on soil environmental quality and plant, and to reach for their potential input sources. The investigation revealed that the mean and range values of all element concentrations in agricultural soil are higher than those in desert soil. Furthermore, the agricultural soil displayed various degrees of enrichment and pollution of Cd, Zn, Mo, Co, P, Ti, Pb. The geochemical pattern of integrated pollution indices gave a clear image of extreme and strong pollution in the agricultural soil stations, their poor quality with high risk to human health and considered as a tocsin for an alert. In contrast, the desert soil is the good environmental quality and safe for plant, animal and human health. Alfalfa is tolerant plant and considered as a biomarker for P and Mo in polluted agricultural soil. Four geochemical associations of analyzing elements in agricultural soil and three ones in desert soil have been generated, and their enhancements were essentially caused by various anthropogenic activities and geogenic sources. The investigation also revealed that the broad extended desert soil is fruitful and promising as cultivable lands for agricultural processes in the futures.

  17. Variable Charge Soils: Mineralogy and Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Nik; Van Ranst, Eric; Noble, Andrew; Baert, Geert

    2003-11-01

    Soils rich in particles with amphoteric surface properties in the Oxisols, Ultisols, Alfisols, Spodosols and Andisols orders (1) are considered variable charge soils (2). The term “variable charge” is used to describe organic and inorganic soil constituents with reactive surface groups whose charge varies with pH, ionic concentration and composition of the soil solution. Such groups are the surface carboxyl, phenolic and amino functional groups of organic materials in soils, and surface hydroxyl groups of Fe and Al oxides, allophane and imogolite. The hydroxyl surface groups are also present on edges of some phyllosilicate minerals such as kaolinite, mica, and hydroxyl-interlayered vermiculite. The variable charge is developed on the surface groups as a result of adsorption or desorption of ions that are constituents of the solid phase, i.e., H+, and the adsorption or desorption of solid-unlike ions that are not constituents of the solid. Highly weathered soils usually undergo isoeletric weathering and reach a “zero net charge” stage during their development. They have a slightly acidic to acidic soil solution pH, which is close to either point of zero net charge (PZNC) (3) or point of zero salt effect (PZSE) (3). They are characterized by high abundances of minerals with a point of zero net proton charge (PZNPC) (3) at neutral and slightly basic pHs; the most important being Fe and Al oxides and allophane. Under acidic conditions, the surfaces of these minerals are net positively charged. In contrast, the surfaces of permanent charge phyllosilicates are negatively charged regardless of ambient conditions. Variable charge soils therefore, are heterogeneous charge systems. The coexistence and interactions of oppositely charged surfaces or particles confers a different pattern of physical and chemical behavior on the soil, relatively to a homogeneously charged system of temperate regions. In some variable charge soils (Oxisols and some Ultisols developed on

  18. Using geochemical indicators to distinguish high biogeochemical activity in floodplain soils and sediments.

    Science.gov (United States)

    Kenwell, Amy; Navarre-Sitchler, Alexis; Prugue, Rodrigo; Spear, John R; Hering, Amanda S; Maxwell, Reed M; Carroll, Rosemary W H; Williams, Kenneth H

    2016-09-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict potential elevated rates of biogeochemical activity (microbial "hotspots") in subsurface environments by correlating microbial DNA and aspects of the community structure with the spatial distribution of geochemical indicators in subsurface sediments. Multiple linear regression models of simulated precipitation leachate, HCl and hydroxylamine extractable iron and manganese, total organic carbon (TOC), and microbial community structure were used to identify sample characteristics indicative of biogeochemical hotspots within fluvially-derived aquifer sediments and overlying soils. The method has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 16 alluvial samples were taken from 8 sediment cores, and at the East River, 46 soil/sediment samples were collected across and perpendicular to 3 active meanders and an oxbow meander. Regression models using TOC and TOC combined with extractable iron and manganese results were determined to be the best fitting statistical models of microbial DNA (via 16S rRNA gene analysis). Fitting these models to observations in both contaminated and natural floodplain deposits, and their associated alluvial aquifers, demonstrates the broad applicability of the geochemical indicator based approach.

  19. Geochemical disturbance of soil cover in the nonferrous mining centers of the Selenga River basin.

    Science.gov (United States)

    Timofeev, Ivan V; Kosheleva, Natalia E

    2016-07-04

    The anthropogenic geochemical transformation of soil cover in large nonferrous mining centers of the Selenga River basin was assessed. The results of the geochemical survey of 2010-2012 revealed the spatial distribution patterns and abundances of 18 hazardous heavy metals and metalloids in the soils of Erdenet (Mongolia) and Zakamensk (Buryat republic, Russian Federation). In both cities, mining activities disturbed soil cover which accumulates Mo, Cu, As, Sb, W in Erdenet and Bi, W, Cd, Be, Pb, Mo, Sb in Zakamensk. Maximum accumulation of elements in Erdenet is restricted to the industrial zone. In Zakamensk, it has spread on ½ of the territory with the degree of multielemental pollution exceeding the extremely dangerous level by 16 times. The effect of mining centers on the state of the river system is local and does not spread to the Selenga River. Downstream from Erdenet, an artificial pool intercepts heavy metal and metalloid flows of the Erdenetii-Gol River. By contrast, downstream from the tailing dumps of the Dzhida tungsten-molybdenum plant the concentrations of ore elements W and Mo and their accessories Bi and Cd in the Modonkul River exceed background values by 146, 20, 57, and 21 times, respectively, decreasing by an order of magnitude 30 km downstream.

  20. Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties

    Science.gov (United States)

    Bastianelli, Carole; Ali, Adam A.; Beguin, Julien; Bergeron, Yves; Grondin, Pierre; Hély, Christelle; Paré, David

    2017-07-01

    At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW) are spreading southward at the expense of more productive closed-canopy black spruce-moss forests (MF). The objective of this study was to investigate whether soil properties could distinguish MF from LW in the transition zone where both ecosystem types coexist. This study brings out clear evidence that differences in vegetation cover can lead to significant variations in soil physical and geochemical properties.Here, we showed that soil carbon, exchangeable cations, and iron and aluminium crystallinity vary between boreal closed-canopy forests and open lichen woodlands, likely attributed to variations in soil microclimatic conditions. All the soils studied were typical podzolic soil profiles evolved from glacial till deposits that shared a similar texture of the C layer. However, soil humus and the B layer varied in thickness and chemistry between the two forest ecosystems at the pedon scale. Multivariate analyses of variance were used to evaluate how soil properties could help distinguish the two types at the site scale. MF humus (FH horizons horizons composing the O layer) showed significantly higher concentrations of organic carbon and nitrogen and of the main exchangeable base cations (Ca, Mg) than LW soils. The B horizon of LW sites held higher concentrations of total Al and Fe oxides and particularly greater concentrations of inorganic amorphous Fe oxides than MF mineral soils, while showing a thinner B layer. Overall, our results show that MF store three times more organic carbon in their soils (B+FH horizons, roots apart) than LW. We suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the vegetation structure (stand density

  1. Geochemical pattern of soils in Bobovdol valley, Bulgaria. Assessment of Cd and Co contents

    Directory of Open Access Journals (Sweden)

    Ivona Nikova

    2016-07-01

    Full Text Available The chemical composition of soils spread in the Bobov dol valley was studied in order to reveal the natural and anthropogenic patterns of Cd and Co spatial distribution. A sampling procedure based on the irregular grid of points and validated analytical methods were used in the field and laboratory studies. It is found that Cd content varies from 0.21 to 0.90 mg kg-1 in studied soils and the average value of 0.55 mg kg-1 coincides with concentration demarcating soil pollution (0.5 mg kg-1. Co content ranges from 2.22 to 15.76 mg kg-1 and in 70 % of sampled points exceeds the natural background content of 7.8 mg kg-1 found in local rocks. Still, Cd enrichment of studied soils is more significant than Co’s with coefficient of Clarke concentration of 3.67. Hence, the secondary deposition of studied elements as a result of the Bobov dol Thermal power plant air emissions is verified by results obtained. The spatial distribution of Cd and Co is featured with an altitudinal gradient in deposition and a trend of quantitative depletion in the South of Plant. Soil organic matter and pH have no influence on the content and spatial distribution of studied elements. Elements iron affinity governs their geochemical linkage in soils although cobalt occurs allied with aluminum and titanium.

  2. Influence of geochemical properties and land-use types on the microbial reduction of Fe(III) in subtropical soils.

    Science.gov (United States)

    Liu, Chengshuai; Wang, Yongkui; Li, Fangbai; Chen, Manjia; Zhai, Guangshu; Tao, Liang; Liu, Chuanping

    2014-08-01

    Microbial Fe(III) reduction significantly impacts the geochemical processes and the composition of most subsurface soils. However, up to now, the factors influencing the efficiency of Fe(III) reduction in soils have not been fully described. In this study, soil Fe(III) reduction processes related to geochemical properties and land-use types were systematically investigated using iron-rich soils. The results showed that microbial Fe(III) reduction processes were efficient and their rates varied significantly in different types of soils. Fe(III) reduction rates were 1.1-5.6 times as much in soils with glucose added as in those without glucose. Furthermore, Fe(III) reduction rates were similar in soils from the same parent materials, while they were highest in soils developed from sediments, with a mean rate of 1.87 mM per day when supplemented with glucose. In addition, the Fe(III) reduction rates, reaching 0.99 and 0.59 mM per day on average with and without glucose added, respectively, were higher in the paddy soils affected heavily by human activities than those in the forest soils (average rates of 0.38 and 0.15 mM per day when with and without glucose, respectively). All the soil weathering indices correlated linearly with Fe(III) reduction rates, even though the reduction of iron in soils with higher weathering degrees was partly inhibited by a higher soil protonation trend and fewer available iron reduction sites in the soils, which gives lower reduction rates. These results clearly illustrate that soil Fe(III) reduction rates are greatly dependent on soil geochemical properties and land-use types and help define which soil types exhibit similar degrees of Fe(III) reduction under field conditions.

  3. Monitoring of Ecological and Geochemical State of the Soil Cover in the City of Voronezh

    Directory of Open Access Journals (Sweden)

    Sereda Lyudmila Olegovna

    2015-09-01

    Full Text Available Soil cover in the city of Voronezh accumulates a lot of pollutants and indicates the centers of technological pollution. The high rates of housing construction, functioning and development of urban infrastructure cause infringement to the soil cover. The paper contains main results of an ecological and geochemical research of the soil cover in Voronezh, its characteristics, properties of the horizons of the different types of soils. During spring and summer of 2014 75 samples of soil were collected in special points of monitoring (according to GOST 17.4.3.01-83 and GOST 17.4.4.02-84. During the research the following methods were applied – volt-ampermetric method was used for detecting the concentration of heavy metals, the method of cholophorm-hexan extraction – for petrochemicals, the method of I.V. Tyurin – for humus concentration, potentiometric method and biotesting methods (analysis of seedlings of the following indicating plants – Lepidium sativum, Avena sativa, as well as defining the phytotoxic effect – for actual acidity detection. The obtained results are used for creating an overview soil map of Voronezh. Urbanozems are dominating in the soil cover of Voronezh. There era large areas of them in the majority of the city districts. A smaller part of a total urban area is presented by soils, which are slightly touched by human economic activity. Urban soils of industrial and transport city zones have disadvantageous properties – low rate of humus and alkali reaction of soil environment, high rate of pollution by petrochemicals and heavy metals. The least rate of pollution of a soil cover by heavy metals is detected in residential areas, situated far from industrial objects and highways. We have detected dependence between accumulation of polluting substances in soil cover and functional and planning peculiarities of the city. For example, accumulation of zinc takes place in soils with alkali reaction of soil and low

  4. Gemas: Geochemical mapping of the agricultural and grasing land soils of Europe

    Science.gov (United States)

    Reimann, Clemens; Fabian, Karl; Birke, Manfred; Demetriades, Alecos; Matschullat, Jörg; Gemas Project Team

    2017-04-01

    Geochemical Mapping of Agricultural and grazing land Soil (GEMAS) is a cooperative project between the Geochemistry Expert Group of EuroGeoSurveys and Eurometaux. During 2008 and until early 2009, a total of 2108 samples of agricultural (ploughed land, 0-20 cm, Ap-samples) and 2023 samples of grazing land (0-10 cm, Gr samples)) soil were collected at a density of 1 site/2500 km2 each from 33 European countries, covering an area of 5,600,000 km2. All samples were analysed for 52 chemical elements following an aqua regia extraction, 42 elements by XRF (total), and soil properties, like CEC, TOC, pH (CaCl2), following tight external quality control procedures. In addition, the Ap soil samples were analysed for 57 elements in a mobile metal ion (MMI®) extraction, Pb isotopes, magnetic susceptibility and total C, N and S. The results demonstrate that robust geochemical maps of Europe can be constructed based on low density sampling, the two independent sample materials, Ap and Gr, show very comparable distribution patterns across Europe. At the European scale, element distribution patterns are governed by natural processes, most often a combination of geology and climate. The geochemical maps reflect most of the known metal mining districts in Europe. In addition, a number of new anomalies emerge that may indicate mineral potential. The size of some anomalies is such that they can only be detected when mapping at the continental scale. For some elements completely new geological settings are detected. An anthropogenic impact at a much more local scale is discernible in the immediate vicinity of some major European cities (e.g., London, Paris) and some metal smelters. The impact of agriculture is visible for Cu (vineyard soils) and for some further elements only in the mobile metal ion (MMI) extraction. For several trace elements deficiency issues are a larger threat to plant, animal and finally human health at the European scale than toxicity. Taking the famous step

  5. Geochemical investigation as a tool in determining of the potential hazard for soil contamination (Kremna Basin, Serbia

    Directory of Open Access Journals (Sweden)

    Perunović Tamara

    2015-01-01

    Full Text Available Geochemical composition of soils and underlying sediments in the Kremna Basin was investigated. The aim was to assess whether observed heavy metal concentrations in soil samples represent geogenic or anthropogenic contamination. The second objective is to show that geochemical data of underlying sediments should be used as a tool in determining of potential hazard for soil contamination. For this purpose, comparison of contents of As, Cr, Cu, Hg, Ni, Pb and Zn of soil samples with standard values, the reference soil sample and local background values of underlying sediments was performed. The soil samples are unpolluted regarding to contents of As, Hg, Pb and Zn. All samples have higher contents of Cr and Ni, whereas three samples have higher content of Cu than the limit standard values. Geochemical parameters showed that higher concentration of Cr, Cu and Ni in soils can be attributed to geogenic impact. This conclusion is supported by Chemical Proxy of Alteration and Chemical Index of Weathering values, which indicate intense weathering of sediments. The obtained results show that Kremna area is under slight to moderate hazard if land use change would occur, and prove the importance of geochemical composition of underlying sediments in the interpretation of heavy metal pollution.

  6. Geochemical effects on the behavior of LLW radionuclides in soil/groundwater environments

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, K.M.; Sterne, R.J. [Pacific Northwest Lab., Richland, WA (United States)

    1995-12-31

    Assessing the migration potential of radionuclides leached from low-level radioactive waste (LLW) and decommissioning sites necessitates information on the effects of sorption and precipitation on the concentrations of dissolved radionuclides. Such an assessment requires that the geochemical processes of aqueous speciation, complexation, oxidation/reduction, and ion exchange be taken into account. The Pacific Northwest National Laboratory (PNNL) is providing technical support to the U.S. Nuclear Regulatory Commission (NRC) for defining the solubility and sorption behavior of radionuclides in soil/ground-water environments associated with engineered cementitious LLW disposal systems and decommissioning sites. Geochemical modeling is being used to predict solubility limits for radionuclides under geochemical conditions associated with these environments. The solubility limits are being used as maximum concentration limits in performance assessment calculations describing the release of contaminants from waste sources. Available data were compiled regarding the sorption potential of radionuclides onto {open_quotes}fresh{close_quotes} cement/concrete where the expected pH of the cement pore waters will equal to or exceed 10. Based on information gleaned from the literature, a list of preferred minimum distribution coefficients (Kd`s) was developed for these radionuclides. The K{sub d} values are specific to the chemical environments associated with the evolution of the compositions of cement/concrete pore waters.

  7. Adsorption of Phosphate on Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    HUGUO-SONG; ZHUZU-XIANG; 等

    1992-01-01

    The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isothems of phosphate on 4 soils and there was a maximum adsorption on Al-oxide-typed surfaces between pH 3.5 to pH 5.5 as suspension pH changed from 2 to 9,but the adsorption amount of phosphate decreased continually as pH rose on Fe-oxide typed surfaces.The adsorption amount of phosphate and the maximum phosphate adsorption pH decreased in the order of yellow-red soil> lateritic red soil> red soil> paddy soil,which was coincided with the content order of amorphous Al oxide.The removement of organic matter and Fe oxide made the maximum phosphate adsorption pH rise from 4.0 to 5.0 and 4.5,respectively.The desorption curves with pH of four soils showed that phosphate desorbed least at pH 5.Generally the desorption was contrary to the adsorption with pH changing.There was a good accordance between adsorption or desorption and the concentration of Al in the suspension.The possible mechanisms of phosphate adsorption are discussed.

  8. Identifying the role of historical anthropogenic activities on urban soils: geochemical impact and city scale mapping

    Science.gov (United States)

    Le Guern, Cecile; Baudouin, Vivien; Conil, Pierre

    2017-04-01

    Recently, European cities have faced several changes including deindustrialization and population increase. To limit urban sprawl, urban densification is preferred. It conducts to (re)develop available areas such as brownfields. Although these areas can be attractive for housing due to their location (in proximity to the city centre or to a riverside), their soils and subsoils are often contaminated. They are therefore potentially harmful for human health and the environment, and potentially costly to remediate. Currently, in case of contamination suspicion, depth geochemical characterization of urban soil and subsoil are carried out at site scale. Nevertheless, large redevelopment project occur at quarter to city scale. It appears therefore useful to acquire the preliminary knowledge on the structure and quality of soil and subsoils, as well as on the potential sources of contamination at quarter to city scale. In the frame of the Ile de Nantes (France) redevelopment project, we considered more particularly anthropogenic deposits and former industrial activities as main sources of contamination linked to human activities. To face the low traceability of the use of anthropogenic deposits and the lack of synthesis of former industrial activities, we carried out a historical study, synthetizing the information spread in numerous archive documents to spatialize the extent of the deposits and of the former activities. In addition we developed a typology of made grounds according to their contamination potential to build a 3D geological model with a geochemical coherence. In this frame, we valorized existing borehole descriptions coming mainly from pollution diagnosis and geotechnical studies. We also developed a methodology to define urban baseline compatibility levels using the existing analytical data at depth from pollution diagnosis. These data were previously gathered in a local geodatabase towards with borehole descriptions (more than 2000 borehole descriptions

  9. Elemental Composition and Geochemical Characteristics of Iron-Manganese Nodules in Main Soils of China

    Institute of Scientific and Technical Information of China (English)

    TAN Wen-Feng; LIU Fan; LI Yong-Hua; HU Hong-Qing; HUANG Qiao-Yun

    2006-01-01

    Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of ironmanganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1)Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.

  10. Geochemical markers of soil anthropogenic contaminants in polar scientific stations nearby (Antarctica, King George Island).

    Science.gov (United States)

    Prus, Wojciech; Fabiańska, Monika J; Łabno, Radosław

    2015-06-15

    The organic contamination of Antarctic soils and terrestrial sediments from nearby of five polar scientific stations on King George Island (Antarctica) was investigated. Gas chromatography-mass spectrometry (GC-MS) was applied to find composition of dichloromethane extracts of soil and terrestrial sediments. The presence of geochemical markers, such as n-alkanes, steranes, pentacyclic triterpenoids, and alkyl PAHs, their distribution types, and values of their ratios indicates the predominating source of organic fossil fuels and products of their refining rather than from the natural Antarctic environment. Fossil fuel-originated compounds well survived in conditions of Antarctic climate over long times thus enabling to characterize geochemical features of source fossil fuel identified as petroleum expelled from kerogen II of algal/bacterial origins deposited in sub-oxic conditions and being in the middle of catagenesis. Both microbial activity and water leaching play an important role in degradation of terrestrial oil spills in the Antarctica climate, and petroleum alteration occurs lowly over long periods of time. Synthetic anthropogenic compounds found in terrestrial Antarctica sediments included diisopropylnaphthalenes, products of their sulfonates degradation in paper combustion, and organophosporus compounds used as retardants and plasticizers.

  11. Cadmium speciation assessed by voltammetry, ion exchange and geochemical calculation in soil solutions collected after soil rewetting.

    Science.gov (United States)

    Cornu, J Y; Parat, C; Schneider, A; Authier, L; Dauthieu, M; Sappin-Didier, V; Denaix, L

    2009-07-01

    Analytical techniques and speciation models have been developed to characterize the speciation of Cd in soil solution. They provide an estimate of operationally defined species of Cd that need to be compared, especially for soil solutions highly concentrated in organic matter as are the solutions collected after soil rewetting. This work deals with the comparison between the speciation of Cd measured by anodic stripping voltammetry (ASV) and ion exchange and the speciation of Cd calculated using Visual MINTEQ. The aim of this study was to quantify and explain the differences in Cd speciation observed between the three approaches. Cd speciation was assessed in soil solutions collected 4, 8, 24, 48, 96 and 144h after the rewetting of an air-dried contaminated soil. To optimize the computed speciation of Cd, other physico-chemical parameters were followed (e.g. pH, ionic strength and the concentrations of major anions, major cations and dissolved organic carbon) and a brief characterisation of dissolved organic matter (DOM) was performed. The discrepancy between model predictions and analytical measurements highlighted the need for caution in the interpretation of geochemical speciated data for Cd. The major result of this study was that a characterization of DOM based on its specific UV-absorbance at 254 nm improved the accuracy of model predictions. Another finding is that labile Cd complexes, even organic, may have been included in the electrochemically labile fraction of Cd measured by ASV.

  12. Testing single extraction methods and in vitro tests to assess the geochemical reactivity and human bioaccessibility of silver in urban soils amended with silver nanoparticles

    NARCIS (Netherlands)

    Cruz, N.; Rodrigues, S.M.; Tavares, D.; Monteiro, R.J.R.; Carvalho, L.; Trindade, T.; Duarte, A.C.; Pereira, E.; Romkens, Paul

    2015-01-01

    To assess if the geochemical reactivity and human bioaccessibility of silver nanoparticles (AgNPs) in soils can be determined by routine soil tests commonly applied to other metals in soil, colloidal Ag was introduced to five pots containing urban soils (equivalent to 6.8mgAgkg-1 soil)

  13. Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania)

    Science.gov (United States)

    Bove, M.A.; Ayuso, R.A.; de Vivo, B.; Lima, A.; Albanese, S.

    2011-01-01

    Lead isotope applications have been widely used in recent years in environmental studies conducted on different kinds of sampled media. In the present paper, Pb isotope ratios have been used to determine the sources of metal pollution in soils and waters in the Agro Aversano area. During three different sampling phases, a total of 113 surface soils (5-20. cm), 20 samples from 2 soil profiles (0-1. m), 11 stream waters and 4 groundwaters were collected. Major element concentrations in sampled media have been analyzed by the ICP-MS technique. Surface soils (20 samples), all soil profiles and all waters have been also analyzed for Pb isotope compositions by thermal ionization (TIMS). The geochemical data were assessed using statistic methods and cartographically elaborated in order to have a clear picture of the level of disturbance of the area. Pb isotopic data were studied to discriminate between anthropogenic and geologic sources. Our results show that As (5.6-25.6. mg/kg), Cu (9-677. mg/kg), Pb (22-193. mg/kg), Tl (0.53-3.62. mg/kg), V (26-142. mg/kg) and Zn (34-215. mg//kg) contents in analyzed soils, exceed the intervention limits fixed by the Italian Environmental Law for residential areas in some of the sampled sites, while intervention limit for industrial areas is exceeded only for Cu concentrations. Lead isotopic data, show that there is a high similarity between the ratios measured in the leached soil samples and those deriving from anthropic activities. This similarity with anthropogenic Pb is also evident in the ratios measured in both groundwater and stream water samples. ?? 2010 Elsevier B.V.

  14. Geochemical Legacies and the Future Health of Cities: An Analysis of two Neurotoxins in Urban Soils

    Science.gov (United States)

    Filippelli, G. M.; Risch, M.

    2015-12-01

    The past and future of cities are inextricably linked, a linkage that can be seen clearly in the long-term impacts of urban geochemical legacies. As loci of population as well as the means of employment and industry to support these populations, cities have a long history of co-locating contaminating practices and people, sometimes with negative implications for human health. Working at the intersection between geochemical processes, communities, and human health is critical to grapple with environmental legacies and to support healthy, sustainable, and growing urban populations. An emerging area of environmental health research is to understand the impacts of chronic exposures and exposure mixtures—these impacts are very poorly studied, yet have materialized as perhaps the greatest threat to large-scale population health. Acute exposure to lead (Pb), a powerful neurotoxin to which children are particularly susceptible, has largely been eliminated in the U.S. and other countries through policy-based restrictions on leaded gasoline and lead-based paints. But these legacy Pb sources are still around in the form of surface soil Pb contamination, a common problem in cities and one that has only recently emerged as a pernicious and widespread chronic exposure mechanism in cities. Some urban soils are also contaminated with another neurotoxin, mercury (Hg), although very little work has been done to understand human exposures to low levels of this element in soils. The most documented human exposure to Hg is through fish consumption, so eating fish caught in urban areas presents risks for above average dietary Hg exposure. The potential double impact of chronic exposure to these two neurotoxins is pronounced in cities. Many aspects of the dose-response curves for individual elements and mixtures are poorly understood, especially at lower levels, leaving unanswered several interesting and provocative questions about environmental impacts on neurological and

  15. Combination of geo- pedo- and technogenic magnetic and geochemical signals in soil profiles - Diversification and its interpretation: A new approach.

    Science.gov (United States)

    Szuszkiewicz, Marcin; Łukasik, Adam; Magiera, Tadeusz; Mendakiewicz, Maria

    2016-07-01

    Magnetic and geochemical parameters of soils are determined with respect to geology, pedogenesis and anthropopression. Depending on local conditions these factors affect magnetic and geochemical signals simultaneously or in various configurations. We examined four type of soils (Entic Podzol, Eutric Cambisol, Humic Cambisol and Dystric Cambisol) developed on various bedrock (the Tumlin Sandstone, basaltoid, amphibolite and serpentinite, respectively). Our primary aim was to characterize the origin and diversification of the magnetic and geochemical signal in soils in order to distinguish the most reliable methods for correct interpretation of measured parameters. Presented data include selected parameters, both magnetic (mass magnetic susceptibility - χ, frequency-dependent magnetic susceptibility - χfd and thermomagnetic susceptibility measurement - TSM), and geochemical (selected heavy metal contents: Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn). Additionally, the enrichment factor (EF) and index of geoaccumulation (Igeo) were calculated. Our results suggest the following: (1) the χ/Fe ratio may be a reliable indicator for determining changes of magnetic signal origin in soil profiles; (2) magnetic and geochemical signals are simultaneously higher (the increment of χ and lead and zinc was noted) in topsoil horizons because of the deposition of technogenic magnetic particles (TMPs); (3) EF and Igeo evaluated for lead and zinc unambiguously showed anthropogenic influence in terms of increasing heavy metal contents in topsoil regardless of bedrock or soil type; (4) magnetic susceptibility measurements supported by TSM curves for soil samples of different genetic horizons are a helpful tool for interpreting the origin and nature of the mineral phases responsible for the changes of magnetic susceptibility values.

  16. Comparison of microbial and sorbed soil gas surgace geochemical techniques with seismic surveys from the Southern Altiplano, Bolivia

    Energy Technology Data Exchange (ETDEWEB)

    Aranibar, O.R.; Tucker, J.D.; Hiltzman, D.C.

    1995-12-31

    Yacimientos Petroliferos Fiscales Bolivianos (YPFB) undertook a large seismic evaluation in the southern Altiplano, Bolivia in 1994. As an additional layer of information, sorbed soil gas and Microbial Oil Survey Technique (MOST) geochemical surveys were conducted to evaluate the hydrocarbon microseepage potential. The Wara Sara Prospect had 387 sorbed soil gas samples, collected from one meter depth, and 539 shallow soil microbial samples, collected from 15 to 20 centimeter depth. The sorbed soil gas samples were collected every 500 meters and microbial samples every 250 meters along geochemical traverses spaced 1 km apart. The presence of anmalous hydrocarbon microseepage is indicated by (1) a single hydrocarbon source identified by gas crossplots, (2) the high gas values with a broad range, (3) the high overall gas average, (4) the clusters of elevated samples, and (5) the right hand skewed data distributions.

  17. Geochemical Evidence for the Formation of Soils by Interaction Between Guano and Volcanic Rocks, Rata Island, Fernando de Noronha (Pernambuco

    Directory of Open Access Journals (Sweden)

    Sonia Maria Barros de Oliveira

    2009-10-01

    Full Text Available The phosphatic soils found in the northern part of the Rata island, in the Fernando de Noronha Archipelago, wereformed by reaction of bird guano with weathered mafi c rocks of the Quixaba Formation. Phosphate minerals identifi edinclude crandallite as a major constituent. The unique guano signature preserved in soil is characterized by high levelsof Cu, Pb, Zn, As, U, and Sr. On the other hand, the inheritance of the geochemical signature of the nepheline-basalts isdemonstrated by the anomalous concentrations of Ba, Nb, Ta, Cr, Hf, V and Zr in soils, and by the remarkable similaritybetween REE patterns in rock and soils.

  18. History and Progress of the North American Soil Geochemical Landscapes Project,2001-2010

    Institute of Scientific and Technical Information of China (English)

    David B.Smith; William F.Cannon; Laurel G.Woodruff; Francisco Moreira Rivera; Andrew N.Rencz; Robert G.Garrett

    2012-01-01

    In 2007,the U.S.Geological Survey,the Geological Survey of Canada,and the Mexican Geological Survey initiated a low-density(1 site per 1600 km2,13323 sites) geochemical and mineralogical survey of North American soils(North American Soil Geochemical Landscapes Project).Sampling and analytical protocols were developed at a series of workshops in 2003-2004 and pilot studies were conducted from 2004-2007.The ideal sampling protocol at each site includes a sample from 0-5 cm depth,a composite of the soil A horizon,and a sample from the soil C horizon.The 2-mm fraction of each sample is analyzed for Al,Ca,Fe,K,Mg,Na,S,Ti,Ag,Ba,Be,Bi,Cd,Ce,Co,Cr,Cs,Cu,Ga,In,La,Li,Mn,Mo,Nb,Ni,P,Pb,Rb,Sb,Sc,Sn,Sr,Te,Th,Tl,U,V,W,Y,and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl,HNO3,HClO4,and HF.Separate methods are used for As,Hg,Se,and total C on this same size fraction.The major mineralogical components are determined by a quantitative X-ray diffraction method.Sampling in the conterminous U.S.was completed in 2010(c.4800 sites) with chemical and mineralogical analysis currently underway.In Mexico,approximately 66% of the sampling(871 sites) had been done by the end of 2010 with completion expected in 2012.After completing sampling in the Maritime provinces and portions of other provinces(472 sites,7.6% of the total),Canada withdrew from the project in 2010.Preliminary results for a swath from the central U.S.to Florida clearly show the effects of soil parent material and climate on the chemical and mineralogical composition of soils.A sample archive will be established and made available for future investigations.

  19. Soil Gas Geochemical Behaviour across Buried and Exposed Faults during the 24 August 2016 Seismic Sequence

    Science.gov (United States)

    Bigi, S.; Ciotoli, G.; Sciarra, A.; Ruggiero, L.; Annunziatellis, A.

    2016-12-01

    Following the earthquake (ML=6.0) of 24 August 2016 that affected large part of the central Apennine between the municipalities of Norcia (PG) and Amatrice (RI) (Central Italy), soil gas profiles (i.e., 222Rn, 220Rn, CO2 and CO2 flux) were carried out crossing buried and exposed coseismic fault rupture of the Mt. Vettore fault during the seismic sequence. The objective of the survey was to explore the migration mechanisms and the behaviour of different gas species near still-degassing active fault. Results provide higher gas and CO2 flux values (about twice for 222Rn and CO2 flux) in correspondence of the buried sector of the fault than those measured across the exposed fault rupture. Anomalous peaks due to advective migration are clearly visible along profile 1 on both side of the buried fault, whereas soil gas concentrations measured along profile 2 are mainly caused by shallow and still acting diffusive degassing associated faulting. The results confirm the usefulness of the soil gas survey to spatially recognise the shallow geometry of hidden faults, and to discriminate the geochemical migration mechanisms occurring at buried and exposed faults related to the seismic activity.

  20. Suspended Sediment Variability and Erosion Geochemical Budget of the Ganga Basin

    Science.gov (United States)

    France-Lanord, C.; Galy, V.; Galy, A.; Singh, S. K.

    2005-12-01

    Himalayan erosion generates one of the world largest sediment transport system. Assessing modern fluxes is difficult in such large river system as there is a large seasonal variability and because floodplain sequestration and the bedload transport are potentially important but not measurable. Measurements on rivers in Bangladesh provide data on dissolved and particulate fluxes. Galy and France-Lanord [1] used a geochemical budget to approach these additional fluxes and proposed that they should be approximately equal to that of the suspended load flux (about 400 Mt/yr for the Ganga). However, such budget relies on the representativeness of the chemical composition attributed to the different endmembers. Here we present new data on river sediments of the Ganga in Bangladesh and in the Gangetic plain that allow a much more reliable assessment of the suspended sediment composition. Sampling has been performed during monsoon periods of 2001, 02 and 04. Sampling includes depth profiling in order to take into account the mineral sorting during transport. Depth profiles show systematic trends. For instance, Al2O3/SiO2 ratio evolve from 0.25-0.35 at the surface down to 0.15-0.27 at 10 m depth mainly as a response to the progressive decrease of the (micas+clays)/quartz ratio. Grain size distribution also evolves in parallel from an unimodal distribution around 20 μm at the surface to a bimodal distribution with a second mode around 200 μm at depth. Elements like Na, which is controlled by plagioclase, and Ca controlled by carbonates do no not show any systematic evolution with depth. Along the Ganga course, the suspended sediments are more progressively depleted in SiO2 likely as a response to the deposition of quartz rich sediments in the floodplain. The data show that in Bangladesh, the suspended sediments are clearly enriched in Al and Fe relative to the average Himalayan sources. Using a simple geochemical mass balance and assuming steady state erosion of the

  1. An integrated geochemical and mineralogical approach for the evaluation of arsenic mobility in mining soils

    Energy Technology Data Exchange (ETDEWEB)

    Kreidie, Nadia; Mottana, Annibale [Rome Univ. (Italy). Dipt. Scienze Geologiche; Armiento, Giovanna; Crovato, Cinzia; Nardi, Elisa; Pacifico, Renata; Cremisini, Carlo [ENEA-Agenzia Nazionale per le Nuove Tecnologie, l' Energia e lo Sviluppo Economico Sostenibile-C.R. Casaccia, Rome (Italy); Cibin, Giannantonio; Cinque, Gianfelice [INFN-Laboratori Nazionali Frascati (Italy)

    2011-01-15

    Purpose: The assessment of risk related to the presence of potentially toxic elements in soils is strictly related to the knowledge of their form and mobility. These relevant properties depend on the complex interactions of the elements of concern with the soil particles that generally cannot be addressed by a single technique. This study presents an integrated approach implementing geochemical and mineralogical investigation techniques on samples from a former mining area (Tolfa Mountains district, northern Latium, Italy), where exploiting activities occurred until the recent past. In particular, the As total concentration and the As distribution in solid phases is studied with the aim to evaluate the possibility of environmental pollution and consequent risks for the health of people living in the area and possibly affected in case of significant mobilization of this toxic element. Materials and methods: Chemical (ICP-MS, ICP-OES) and mineralogical (X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray absorption near-edge structure (XANES)) analyses and the evaluation of the heavy metal mobility (by means of a sequential extraction procedure) were performed. Results and discussion: Chemical analyses show a high As content in the soils collected immediately downstream the marcasite mine waste deposit, that is the starting point of As pollution over the whole area. XANES analyses show that As occurs in two oxidation states (As{sup III} and As{sup V}) simultaneously in the tailing samples and nearby, while it has been mainly or totally transformed into As{sup V} at increasing distance from the mine. XRD data show that sheet silicates don't affect As behavior, whereas sequential extractions and SEM-EDX analyses reveal the evident association of As and Fe oxyhydroxides content. Conclusions: The use of an integrated geochemical-mineralogical approach allows to single out the contaminant forms and the relative potential

  2. Geochemical evolution of lacustrine brines from variable-scale groundwater circulation

    Science.gov (United States)

    Donovan, Joseph J.; Rose, Arthur W.

    1994-02-01

    Evaporative groundwater-fed lakes in the glaciated North American Great Plains vary widely in chemistry. A contributing cause is chemical variability of source groundwater intercepted by specific lakes, caused in part by differing depths of groundwater circulation. Aqueous chemical characteristics of 61 lakes and 160 groundwater samples were compared for an area where such lakes are common in eastern Montana-western North Dakota. Results indicate that groundwater chemistry varies according to depth in a similar fashion within different aquifers. Lake water evaporation from initial groundwater solutions typical of three depths was geochemically modeled using PHRQPITZ, based on a Pitzer treatment of activities and equilibria. Results show that chemistry of most lake waters in the study area may correspond to that predicted from evaporation of shallow- and intermediate-depth groundwater, but not of deep groundwater as postulated in some previous investigations. Lakes in shallow surface depressions receive water primarily from shallow (local) groundwater flow; lakes located in deep or broad topographic depressions may additionally receive groundwater from deeper circulation. In the field area studied, relative dominance of anions (sulfate vs. carbonate) in brines is a signature for inferred depth of source. Also diagnostic is the suite of brine salts formed (NaSO 4Mg salts for shallow flow; these plus NaCO 3 salts for intermediate depth flow). Such source signatures will vary from area to area according to depth variations in groundwater chemistry and in stratigraphy. Chemical evolution of lake water is a two-stage process, with a groundwater path (influenced by residence time, depth of circulation, aquifer mineralogy, and related factors) and a surface path (influenced by evaporation rates, lake-aquifer hydraulics, and lake geochemical reactions). Groundwater flow patterns may affect the former set of factors, thereby indirectly controlling lake water

  3. Geochemical characterization and biomonitoring of reclaimed soils in the Po River Delta (Northern Italy): implications for the agricultural activities.

    Science.gov (United States)

    Di Giuseppe, Dario; Bianchini, Gianluca; Vittori Antisari, Livia; Martucci, Annalisa; Natali, Claudio; Beccaluva, Luigi

    2014-05-01

    This geochemical study is focused on the easternmost part of the Po River alluvial plain in Northern Italy, which is interested by widespread agricultural activities, investigating a reclaimed sector of the Province of Ferrara, known as "Valle del Mezzano" (Mezzano Low Land, hereafter reported as MLL) characterized by peat-rich soils. The chemical-mineralogical characterization of these reclaimed soils is important to compare the local geochemical backgrounds with those recorded in other sectors of the River Po plain and to monitor if the observed concentration exceeds critical thresholds. The reported analyses include (a) measurement of the soil salinity, (b) nutrient evaluation, (c) major and trace element concentrations carried out on bulk soils, (d) tests of metal extraction with both aqua regia and EDTA to highlight the distinct elemental mobility and (e) phyto-toxicological measurement of heavy metal concentrations in plants (Lactuca sativa acephala) grown on the studied soils. The results indicate (1) high soil salinity, often with drastic increase of sodium and chloride along the soil profiles, (2) high nitrogen content (in part related to anthropogenic activities) on superficial horizons and nitrate decrease along the soil profiles and (3) comparative enrichments in heavy metals with respect to other soils of the province, which indicate that peat deposits are effective in trapping metals from anthropogenic sources. This, in turn, implies potential geochemical risks for the agricultural activities. In this regard, specific concerns are related to the high nickel and arsenic content of MLL soils due to the mobility of these elements and their attitude to be taken up by plants.

  4. Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

    Directory of Open Access Journals (Sweden)

    C. Martín-Puertas

    2010-12-01

    Full Text Available A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G and terrestrial (Zoñar Lake, Andalucia, Spain geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP. Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean.

  5. Geochemical behaviour of rare earths in Vitis vinifera grafted onto different rootstocks and growing on several soils.

    Science.gov (United States)

    Censi, P; Saiano, F; Pisciotta, A; Tuzzolino, N

    2014-03-01

    The geochemical behaviour of lanthanides and yttrium (Rare Earth Elements, REEs) has been investigated mainly in geological systems where these elements represent the best proxies of processes involving the occurrence of an interface between different media. This behaviour is assessed according to features recorded in sequences of REE concentrations along the REE series normalised with respect to a reference material. In this study, the geochemical behaviour of REE was investigated in different parts of Vitis vinifera specimens grown off-soil, on soils of different nature and grafted onto several rootstocks in order to evaluate effects induced by these changes. The results indicated that roots are the plant organs where REEs are preferentially concentrated, in particular elements from Sm to Ho (middle REE, MREE) whereas Eu enrichments occur in aerial parts. The geochemical behaviour of REE suggests that MREE enrichments in roots are due to preferential MREE interactions with biological membranes or to surface complexation with newly formed phosphates. Eu-positive anomalies suggest that Eu(3+) can form stable organic complexes in place of Ca(2+) in several biological processes in xylem fluids. The possibility that Eu mobility in these fluids can be enhanced by its reductive speciation as Eu(2+) cannot be ruled out. The assessment of the geochemical behaviour of REE according to the theory of the Tetrad Effect carried out confirms that REEs coming from soil are scavenged onto root tissues or mineral surfaces whereas their behaviour in aerial parts of V. vinifera is driven by dissolved complexation.

  6. Stability of aggregates of some weathered soils in south-eastern Nigeria in relation to their geochemical properties

    Indian Academy of Sciences (India)

    C A Igwe; M Zarei; K Stahr

    2013-10-01

    The stability of some highly weathered soils of the tropics is controlled by their organo-mineral substances. Highly weathered soils from 10 different locations were sampled from their A and B horizons to determine their aggregate stability. The objective of the study was to determine the aggregate stability of the soils and their relationships with geochemical constituents. The major geochemical elements of the soils are quartz and kaolinite, SiO2, Al2O3 and Fe2O3, while the dithionite extractable Fe and Al was greater than their corresponding oxalate and pyrophosphate forms. The mean-weight diameter from dried aggregates (MWDd) and their corresponding wet mean-weight diameter (MWDw) were related significantly (r = 0.64*). The dithionite extracted Al and Fe or the crystalline forms of these elements were outstanding in the stability of the aggregates. However, this did not diminish the influence of SOC reduced to third order level in the stability of the soils. The influence of SOC in these soils, however, indirectly manifested on the role of Fep and Alp in the aggregation of these soils. The crystalline Fe and Al sesquioxides were very prominent in the aggregation and stability of these soils.

  7. Geochemical cartography as a tool for assessing the degree of soil contamination with heavy metals in Poland

    Science.gov (United States)

    Szymon Borkowski, Andrzej; Kwiatkowska-Malina, Jolanta

    2016-04-01

    Spatial disposition of chemical elements including heavy metals in the soil environment is a very important information during preparation of the thematic maps for the environmental protection and/or spatial planning. This knowledge is also essential for the earth's surface and soil's monitoring, designation of areas requiring improvement including remediation. The main source of anthropogenic pollution of soil with heavy metals are industry related to the mining coal and liquid fuels, mining and metallurgy, chemical industry, energy production, waste management, agriculture and transport. The geochemical maps as a kind of specific thematic maps made on the basis of datasets obtained from the Polish Geological Institute's resources allow to get to know the spatial distribution of different chemical elements including heavy metals in soil. The results of the research carried out by the Polish Geological Institute showed strong contamination in some regions in Poland mainly with arsenic, cadmium, lead and nickel. For this reason it was the point to prepare geochemical maps showing contamination of soil with heavy metals, and determine main sources of contamination and zones where heavy metals concentration was higher than acceptable contents. It was also presented a summary map of soil contamination with heavy metals. Additionally, location of highly contaminated zones was compiled with predominant in those areas types of arable soils and then results were thoroughly analyzed. This information can provide a base for further detailed studies on the soil contamination with heavy metals.

  8. Assessing heavy metal pollution in the water level fluctuation zone of China's Three Gorges Reservoir using geochemical and soil microbial approaches.

    Science.gov (United States)

    Ye, Chen; Li, Siyue; Zhang, Yulong; Tong, Xunzhang; Zhang, Quanfa

    2013-01-01

    The water level fluctuation zone (WLFZ) in the Three Gorges Reservoir is located in the intersection of terrestrial and aquatic ecosystems, and assessing heavy metal pollution in the drown zone is critical for ecological remediation and water conservation. In this study, soils were collected in June and September 2009 in natural recovery area and revegetation area of the WLFZ, and geochemical approaches including geoaccumulation index (I (geo)) and factor analysis and soil microbial community structure were applied to assess the spatial variability and evaluate the influence of revegetation on metals in the WLFZ. Geochemical approaches demonstrated the moderate pollutant of Cd, the slight pollutant of Hg, and four types of pollutant sources including industrial and domestic wastewater, natural rock weathering, traffic exhaust, and crustal materials in the WLFZ. Our results also demonstrated significantly lower concentrations for elements of As, Cd, Pb, Zn, and Mn in the revegetation area. Moreover, soil microbial community structure failed to monitor the heavy metal pollution in such a relatively clean area. Our results suggest that revegetation plays an important role in controlling heavy metal pollution in the WLFZ of the Three Gorges Reservoir, China.

  9. Soil formation and mineralogy of a Rhodic Luvisol — insights from magnetic and geochemical studies

    Science.gov (United States)

    Jordanova, Neli; Jordanova, Diana; Liu, Qingsong; Hu, Pengxiang; Petrov, Petar; Petrovský, Eduard

    2013-11-01

    Relict terra rossa soil from the most south-eastern part of Bulgaria, characterized by transitional Mediterranean climate, has been comprehensively studied by integrating magnetic, geochemical and spectroscopic methods to reveal the origin, pedogenic processes and phases in soil development of this particular soil type. The red colored Rhodic Luvisol is developed on metamorphosed Triassic limestones. Magnetic methods, which include thermomagnetic analysis of susceptibility, isothermal remanent magnetization (IRM) acquisition and thermal demagnetization, IRM component analysis, hysteresis measurements, low-temperature (down to 10 K) IRM behavior, anhysteretic remanence and frequency dependent susceptibility, indicate the presence of three major magnetic phases - maghemite, hematite (Hm) and goethite (Gt). Hematite and goethite are identified also by diffuse reflectance spectroscopy (DRS). Depth variations of the ratio Hm/(Hm + Gt), deduced from the DRS spectra show higher hematite content in the upper soil horizons (A + B), while goethite's contribution is enriched in the lowermost part of the profile. A similar ratio, based on the established magnetic proxies for hematite and goethite, was constructed and its variations were compared with the DRS data. The magnetic proxy for Hm/(Hm + Gt) reflects the variations in the remanence-carrying mineral fraction of hematite and goethite and the obtained difference with the DRS data are ascribed to the presence of the paramagnetic (or superparamagnetic) goethite in the A and illuvial Bt1 and Bt2 horizons. The low ratio Feo/Fed between dithionite (Fed)- and oxalate (Feo)-extractable iron, and the large proportion of extractable iron with respect to total iron (Fed/Fetot) indicate an advanced degree of weathering. Depth variations of magnetic parameters and ratios (χlf, χfd, S-ratio) suggest magnetic enhancement with SP-SD maghemite grains, accompanied by magnetically stable magnetic carriers in the soil, while the parent

  10. Maghemite soil nodules reveal the impact of fire on mineralogical and geochemical differentiation at the Earth's surface

    Science.gov (United States)

    Löhr, Stefan C.; Murphy, David T.; Nothdurft, Luke D.; Bolhar, Robert; Piazolo, Sandra; Siegel, Coralie

    2017-03-01

    Fires occur frequently over large parts of the Earth's surface. They potentially exert a significant influence on the mineralogical and geochemical characteristics of an environment that is otherwise considered to be dominated by low temperature processes. We test this hypothesis by comparing the mineralogy and geochemistry of (i) magnetic, iron-rich soil nodules, (ii) non-magnetic iron soil nodules and (iii) a published dataset of surficial sediments from eastern Australia. Maghemite-rich nodules are present in soils from around the world. It has been argued that they are thermal alteration products of non-magnetic precursors, but this remains controversial. We use detailed petrographic and mineralogical analyses to demonstrate that maghemite occurs as part of a high temperature mineral assemblage including hematite and χ-alumina, within a magnetic nodule microfabric indicative of fire-induced dehydroxylation and sintering of non-magnetic precursors at temperatures of up to 600 °C. The genetic link between magnetic and non-magnetic nodules means that their comparison offers insights into the geochemical impact of fire. Our results show that magnetic nodules are depleted in Si, Y, Zr and HREE but enriched in Fe and Cr relative to non-magnetic nodules that occur in close spatial proximity. Magnetic nodules also show variable but distinctly low Y/Ho (21.4 ± 0.4) and Zr/Hf (29.3 ± 0.8) as well as anomalously low La relative to the other LREE. In situ laser ablation analyses show that this is largely due to the presence of χ-alumina that is depleted in HREEs and has extremely low Y/Ho (mainly magnetic nodule precursors into proto-magnetic nodules. This is associated with thermal transformation of clays as well as Fe and Al oxyhydroxides, followed by isochemical segregation into a sintered core with low Si, Y/Ho, Zr/Hf and La/Gd and a reciprocal cortex. Preferential loss of the weathering-sensitive cortex, which is rarely preserved on the magnetic nodules, then

  11. A comparison of rock and soil samples for geochemical mapping of two porphyry-metal systems in Colorado

    Science.gov (United States)

    Neuerburg, George J.; Barton, H.N.; Watterson, J.R.; Welsch, E.P.

    1978-01-01

    Paired rock and soil samples were collected at widely spaced locations in large segments of the porphyry-metal systems of the Montezuma district in central Colorado and of a northwestward extension of the Summitville district into Crater Creek in southern Colorado. The paired samples do not covary closely enough for one sample medium to proxy for the other. However, the areal distributions of elements in both rocks and soils in these two districts conform to alteration zoning as defined by mineralogy. Differing geochemical patterns of rocks and soils reflect species-dependent responses to weathering. Soils appear to be statistically enriched in ore elements and depleted in rock elements as compared to the matching rocks. These differences are largely artificial s owing to different methods of sample preparation and chemical analysis for rocks and for soils. The distributions of metals in soils delineate the occurrence of ore-metal minerals mostly from vein deposits whereas the distributions of metals in rocks conform to zones of pervasive hydrothermal alteration and to the distribution of varied mineral deposits among these zones. Rock and soil samples are equally useful s of comparable map resolution and complement one another as a basis for geochemically mapping these porphyry-metal systems.

  12. Geochemical proxies and millennial-scale climate variability during MIS 3 at Lake Chalco, central Mexico

    Science.gov (United States)

    Torres, E.; Lozano, S.; Roy, P.; Ortega, B.; Caballero, M.

    2013-05-01

    The Basin of Mexico (20N, 99W; 2240 m.a.s.l.) is present at the northern limit of the American tropics and is surrounded by up to 5400 m high mountains. The Lake Chalco is situated at the southern part of the basin and spreads over 120 km2. The precipitation in the modern era is influenced by the seasonal displacement of the Intertropical Convergence Zone and the high-pressure belt located at about 35 N. Five cores were drilled (up to 122.5 m depth) in order to document climate variability in paleohydrological conditions during the late Quaternary. The age model includes several 14C dates and tephra layers present in the upper 25 m of the core. We documented millennial-scale events during MIS 3 based on geochemical data (total organic carbon (TOC), total inorganic carbon (TIC), C/N ratio) and abundance of charcoal particles. By temporal correlation with GISP2 core we founded that Greenland interstadials match with TOC percentages suggesting wet conditions while stadials match with high TIC percentages and high charcoal concentrations suggesting dry conditions. We compared our data with speleothem records (δ18O) from Fort Station Cave (New Mexico) and Terciopelo Cave (Costa Rica), our preliminary results indicate that Chalco record has a similar climatic signal as Terciopelo Cave, both presented wet interstadials and dry stadials which appear to have been regulated by the seasonal migration of the ITCZ.

  13. Climate variability effects on spatial soil moisture dynamics

    NARCIS (Netherlands)

    Teuling, A.J.; Hupet, F.; Uijlenhoet, R.; Troch, P.A.

    2007-01-01

    We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics

  14. Geochemical Speciation of Soil 7Be,137Cs,226Ra and 228Ra as Tracers to Particle Trnsport

    Institute of Scientific and Technical Information of China (English)

    BALZHANGUO; WANGUOJIANG; 等

    1997-01-01

    A brunisolic soil collected from an erosive forest land(HF-1-1) and a yellow soil from and accumulative shallow basin(HF-6-1) in the watershed of Lake Hongfeng (HF) were used for activity measurements of 7Be,137Cs,226Ra and 228Ra in different geochemical speciation.More than 85% of 7Be,137Cs,226Ra and 228Ra in the soils were bound to organic Fe-Mn oxy-hydroxide and residual fractions.They could move with soil particlesw and be used as tracers for the erosion and /or accumulation of soil particles.7Be gohemical specition in the soils agreed with its trace for seasonal particle transport.137Cs geohemial speciaiton was suitable for tracing soil particle accumulation and for sediment aating.226Ra and 228Ra were ombined in crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble,exchangeable and carbonate fractions.The differentiation of 226 Ra/228Ra activity ratios in different geoheical fractions in the soils could be used as a parameter to trace accumulation and /or erosion of soil particles.

  15. Geochemical legacies and the future health of cities: A tale of two neurotoxins in urban soils

    Directory of Open Access Journals (Sweden)

    Gabriel M. Filippelli

    2015-07-01

    Full Text Available Abstract The past and future of cities are inextricably linked, a linkage that can be seen clearly in the long-term impacts of urban geochemical legacies. As loci of population as well as the means of employment and industry to support these populations, cities have a long history of co-locating contaminating practices and people, sometimes with negative implications for human health. Working at the intersection between environmental processes, communities, and human health is critical to grapple with environmental legacies and to support healthy, sustainable, and growing urban populations. An emerging area of environmental health research is to understand the impacts of chronic exposures and exposure mixtures—these impacts are poorly studied, yet may pose a significant threat to population health. Acute exposure to lead (Pb, a powerful neurotoxin to which children are particularly susceptible, has largely been eliminated in the U.S. and other countries through policy-based restrictions on leaded gasoline and lead-based paints. But the legacy of these sources remains in the form of surface soil Pb contamination, a common problem in cities and one that has only recently emerged as a widespread chronic exposure mechanism in cities. Some urban soils are also contaminated with another neurotoxin, mercury (Hg. The greatest human exposure to Hg is through fish consumption, so eating fish caught in urban areas presents risks for toxic Hg exposure. The potential double impact of chronic exposure to these two neurotoxins is pronounced in cities. Overall, there is a paradigmatic shift from reaction to and remediation of acute exposures towards a more nuanced understanding of the dynamic cycling of persistent environmental contaminants with resultant widespread and chronic exposure of inner-city dwellers, leading to chronic toxic illness and disability at substantial human and social cost.

  16. Geochemical speciation and dynamic of copper in tropical semi-arid soils exposed to metal-bearing mine wastes

    Energy Technology Data Exchange (ETDEWEB)

    Perlatti, Fabio [Department of Environmental Technology, National Department of Mineral Production – DNPM, Rua Dr. José Lourenço, 90560115-280 Fortaleza, CE (Brazil); Graduate Course of Ecology and Natural Resources, Department of Biology, Federal University of Ceará – UFC, Building 906, 60455-760, Fortaleza, CE (Brazil); Otero, Xosé Luis; Macias, Felipe [Department of Edaphology and Agricultural Chemistry, Faculty of Biology, University of Santiago de Compostela – USC, Rúa Lope Gómez de Marzoa, s/n. Campus sur, 15782 Santiago de Compostela (Spain); Ferreira, Tiago Osório, E-mail: toferreira@usp.br [Department of Soil Science, University of São Paulo (ESALQ/USP), Av. Pádua Dias, 11, 13418-900, Piracicaba, SP (Brazil); Graduate Course of Ecology and Natural Resources, Department of Biology, Federal University of Ceará – UFC, Building 906, 60455-760, Fortaleza, CE (Brazil)

    2014-12-01

    The potentially hazardous effects of rock wastes disposed at open pit in three different areas (Pr: Ore processing; Wr: Waste rock and Bd: Border) of an abandoned copper mine were evaluated in this study, with emphasis on acid drainage generation, metal contamination and copper geochemical dynamics in soils. Samples of waste rock were analyzed by Energy dispersive X-ray fluorescence (XRF), scanning electron microscopy with microanalysis (SEM-EDS) and X-ray diffraction (XRD). Soil samples were analyzed to determine the total metal contents (XRF), mineralogy (XRD), pH (H2O and H2O2), organic and inorganic carbon, % of total N, S and P, particle size, and a sequential extraction procedure was used to identify the different copper fractions. As a result of the prevalence of carbonates over sulphides in the wastes, the soil pH remained close to neutral, with absence of acid mine drainage. The geochemical interaction between these mineral phases seems to be the main mechanism to release Cu{sup 2+} ions. Total Cu in soils from the Pr area reached 11,180 mg.kg{sup −1}, while in Wr and Bd areas the values reached, on average, 4683 and 1086 mg.kg{sup −1}, respectively, indicating a very high level of soil contamination. In the Pr and Wr, the Cu was mainly associated with carbonates and amorphous iron oxides. In the Bd areas, the presence of vegetation has influenced the geochemical behavior of copper by increasing the dissolution of carbonates, affecting the buffer capacity of soils against sulphide oxidation, reducing the pH levels and enhancing the proportion of exchangeable and organic bound Cu. The present findings show that the use of plants or organic amendments in mine sites with high concentration of Cu carbonate-containing wastes should be viewed with caution, as the practice may enhance the mobilization of copper to the environment due to an increase in the rate of carbonates dissolution. - Highlights: • The hazardous effects of mine waste rocks at

  17. Simulation of Soil Water Content Variability in a Heavy Clay Soil under Contrasting Soil Managements

    Science.gov (United States)

    Pedrera, A.; Vanderlinden, K.; Martínez, G.; Espejo, A. J.; Giráldez, J. V.

    2012-04-01

    Soil water content (SWC) is a key variable for numerous physical, chemical and biological processes that take place at or near the soil surface. Understanding the spatial and temporal variability of SWC at the field scale is of prime importance for implementing efficient measurement strategies in applications. The aim of this study was to characterize the spatial and temporal variation of gravimetric SWC in a heavy clay soil, in a wheat-sunflower-legume rotation under conventional (CT) and no-till (NT) using a simple water balance model. An experimental field in SW Spain, where conventional (CT) and no-till (NT) management of a heavy clay soil are being compared since 1983, was sampled for gravimetric SWC on 38 occasions during 2008 and 2009. Topsoil clay content across the six plots was on average 55%, with a standard deviation of 2.7%. The soil profile was sampled at 54 locations, evenly distributed over the three CT and NT plots, at depths of 0-10, 25-35, and 55-65 cm. Topsoil water retention curves (SWRC) were determined in the laboratory on undisturbed soil samples from each of the 54 locations. A weather station recorded daily precipitation and evapotranspiration, as calculated by the Penman-Monteith FAO equation. The water balance was calculated using the Thornthwaite-Mather model with a daily time step. Three parameters, water holding capacity, and water evaporation corrector coefficients for each of the two years, were inversely estimated at the 54 SWC observation points and probability density functions were identified. Spatial variability of SWC was estimated using a Monte Carlo approach, and simulated and observed variability were compared. This Monte Carlo scheme, using a simple water balance model with only three parameters, was found to be useful for evaluating the influence of soil management on the variability of SWC in heavy clay soils.

  18. Leg 197 synthesis: Southward motion and geochemical variability of the Hawaiian hotspot

    Science.gov (United States)

    Duncan, R.A.; Tarduno, J.A.; Scholl, D. W.

    2006-01-01

    The bend in the Hawaiian-Emperor volcanic chain is an often-cited example of a change in plate motion with respect to a stationary hotspot. Growing evidence, however, suggests that the bend might instead record variable drift of the Hawaiian hotspot within a convecting mantle. Paleomagnetic and radiometric age data from samples recovered during Ocean Drilling Program (ODP) Leg 197 define an age-progressive paleolatitude history, indicating that the Emperor Seamounts volcanic trend was formed principally by rapid (4-5 cm/yr) southward motion of the Hawaiian hotspot during Late Cretaceous to early Tertiary time (81-47 Ma). Paleointensity data derived from Leg 197 suggest an inverse relationship between field strength and reversal frequency, consistent with an active lower mantle that controls the efficiency of the geodynamo. Petrochemical data and observations of volcanic products (lava flows and volcaniclastic sediments) from Detroit, Nintoku, and Koko Seamounts provide records of the evolution of these volcanic systems for comparison with recent activity in the Hawaiian Islands. We find that the Emperor Seamounts formed from similar mantle sources for melting (plume components and lithosphere) and in much the same stages of volcanic activity and time span as the Hawaiian volcanoes. Changes in major and trace element and Sr isotopic compositions of shield lavas along the lineament can be related to variations in thickness of the lithosphere overlying the hotspot that control the depth and extent of partial melting. Other geochemical tracers, such as He, Pb, and Hf isotopic compositions, indicate persistent contributions to melting from the plume throughout the volcanic chain.

  19. Pilot studies for the North American Soil Geochemical Landscapes Project - Site selection, sampling protocols, analytical methods, and quality control protocols

    Science.gov (United States)

    Smith, D.B.; Woodruff, L.G.; O'Leary, R. M.; Cannon, W.F.; Garrett, R.G.; Kilburn, J.E.; Goldhaber, M.B.

    2009-01-01

    In 2004, the US Geological Survey (USGS) and the Geological Survey of Canada sampled and chemically analyzed soils along two transects across Canada and the USA in preparation for a planned soil geochemical survey of North America. This effort was a pilot study to test and refine sampling protocols, analytical methods, quality control protocols, and field logistics for the continental survey. A total of 220 sample sites were selected at approximately 40-km intervals along the two transects. The ideal sampling protocol at each site called for a sample from a depth of 0-5 cm and a composite of each of the O, A, and C horizons. The acid digestion. A separate sample of 0-5-cm material was collected at each site for determination of organic compounds. A subset of 73 of these samples was analyzed for a suite of 19 organochlorine pesticides by gas chromatography. Only three of these samples had detectable pesticide concentrations. A separate sample of A-horizon soil was collected for microbial characterization by phospholipid fatty acid analysis (PLFA), soil enzyme assays, and determination of selected human and agricultural pathogens. Collection, preservation and analysis of samples for both organic compounds and microbial characterization add a great degree of complication to the sampling and preservation protocols and a significant increase to the cost for a continental-scale survey. Both these issues must be considered carefully prior to adopting these parameters as part of the soil geochemical survey of North America.

  20. Geochemical behaviour of rare earths in Vitis vinifera grafted onto different rootstocks and growing on several soils

    Energy Technology Data Exchange (ETDEWEB)

    Censi, P., E-mail: paolo.censi@unipa.it [DISTEM, University of Palermo, Via Archirafi, 22-90123 Palermo (Italy); Saiano, F.; Pisciotta, A. [SAF Department, University of Palermo, Viale delle Scienze, 13-90128 Palermo (Italy); Tuzzolino, N. [DISTEM, University of Palermo, Via Archirafi, 22-90123 Palermo (Italy)

    2014-03-01

    The geochemical behaviour of lanthanides and yttrium (Rare Earth Elements, REEs) has been investigated mainly in geological systems where these elements represent the best proxies of processes involving the occurrence of an interface between different media. This behaviour is assessed according to features recorded in sequences of REE concentrations along the REE series normalised with respect to a reference material. In this study, the geochemical behaviour of REE was investigated in different parts of Vitis vinifera specimens grown off-soil, on soils of different nature and grafted onto several rootstocks in order to evaluate effects induced by these changes. The results indicated that roots are the plant organs where REEs are preferentially concentrated, in particular elements from Sm to Ho (middle REE, MREE) whereas Eu enrichments occur in aerial parts. The geochemical behaviour of REE suggests that MREE enrichments in roots are due to preferential MREE interactions with biological membranes or to surface complexation with newly formed phosphates. Eu-positive anomalies suggest that Eu{sup 3+} can form stable organic complexes in place of Ca{sup 2+} in several biological processes in xylem fluids. The possibility that Eu mobility in these fluids can be enhanced by its reductive speciation as Eu{sup 2+} cannot be ruled out. The assessment of the geochemical behaviour of REE according to the theory of the Tetrad Effect carried out confirms that REEs coming from soil are scavenged onto root tissues or mineral surfaces whereas their behaviour in aerial parts of V. vinifera is driven by dissolved complexation. - Highlights: • REE behaviour is driven by scavenging onto authigenic solids or membranes in roots. • REE behaviour is driven by dissolved complexation in aerial plant parts. • Positive Eu anomalies are a consequence of the REE translocation by xylem fluids. • Significant REE tetrad effects are observed in Vitis vinifera plants.

  1. Climate variability effects on spatial soil moisture dynamics

    OpenAIRE

    A. J. Teuling; Hupet, F.; R. Uijlenhoet; P. A. Troch

    2007-01-01

    We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics are simulated with a comprehensive model for the period 1989-2003. The results show that climate variability induces non-uniqueness and two distinct hysteresis modes in the yearly relation between...

  2. Alaska Geochemical Database Version 2.0 (AGDB2) - Including "Best Value" Data Compilations for Geochemical Data for Rock, Sediment, Soil, Mineral, and Concentrate Sample Media

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Alaska Geochemical Database Version 2.0 (AGDB2) contains new geochemical data compilations in which each geologic material sample has one "best value"...

  3. Impact of soil variability on irrigated and rainfed cotton

    Science.gov (United States)

    Cotton is a vital component of the economies of Mid-South states. Producers and landowners are looking for ways to reduce the variability of irrigated yields and soil apparent electrical conductivity (ECa) is a readily obtained parameter that can indicate soil variability. A study was conducted in 2...

  4. Sources of organic pollution in particulate matter and soil of Silesian Agglomeration (Poland): evidence from geochemical markers.

    Science.gov (United States)

    Fabiańska, Monika J; Kozielska, Barbara; Konieczyński, Jan; Kowalski, Adam

    2016-06-01

    The exact input of particular sources to polycyclic aromatic hydrocarbons (PAHs) concentrations in urban and industrial agglomerations is still not well recognized. The major breakthrough is possible using geochemical markers. In the air aerosol and soil samples from areas located in the direct influence of industry/traffic in Silesian Agglomeration (Poland), PAHs and other organic compounds were analyzed, including geochemical markers (biomarkers) and polar compounds from fossil fuels and biomass. Gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS) were applied to investigate the composition of particulate matter and soil extracts. The results suggest that the predominant source of PAHs is fossil fuel. The presence and distribution of steranes, pentacyclic triterpenoids (i.e., hopanes and moretanes) and alkyl PAHs point to traffic emissions and fossil fuel combustion, mainly bituminous coal for power and heat purposes, as the main source of PAHs in the region. Moreover, the presence of fossil fuel biomarker in particulate matter and soil extracts from a rural site, previously considered to be free of organic pollution, requires a cautious interpretation for PAHs results. Apart from the fossil fuel, also other sources of contamination were identified in particulate matter extracts by their markers: phenols and levoglucosan for biomass and diisopropylnaphthalenes for printing materials combustion. The absence of polar biomass combustion indicators in soil extracts might be related to their higher reactivity.

  5. Geochemical and mineralogical maps for soils of the conterminous United States

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemical and mineralogical maps along with a histogram, boxplot, and empirical cumulative distribution function plot for each element or mineral whose data are...

  6. The spatial relationship between human activities and C, N, P, S in soil based on landscape geochemical interpretation.

    Science.gov (United States)

    Yu, Huan; He, Zheng-Wei; Kong, Bo; Weng, Zhong-Yin; Shi, Ze-Ming

    2016-04-01

    The development and formation of chemical elements in soil are affected not only by parent material, climate, biology, and topology factors, but also by human activities. As the main elements supporting life on earth system, the C, N, P, S cycles in soil have been altered by human activity through land-use change, agricultural intensification, and use of fossil fuels. The present study attempts to analyze whether and how a connection can be made between macroscopical control and microcosmic analysis, to estimate the impacts of human activities on C, N, P, S elements in soil, and to determine a way to describe the spatial relationship between C, N, P, S in soil and human activities, by means of landscape geochemical theories and methods. In addition, the disturbances of human activities on C, N, P, S are explored through the analysis of the spatial relationship between human disturbed landscapes and element anomalies, thereby determining the diversified rules of the effects. The study results show that the rules of different landscapes influencing C, N, P, S elements are diversified, and that the C element is closely related to city landscapes; furthermore, the elements N, P, and S are shown to be closely related to river landscapes; the relationships between mine landscapes and the elements C, N, P, S are apparent; the relationships between the elements C, N, P, S and road landscapes are quite close, which shows that road landscapes have significant effects on these elements. Therefore, the conclusion is drawn that the response mechanism analysis of human disturbance and soil chemical element aggregation is feasible, based on the landscape geochemical theories and methods. The spatial information techniques, such as remote sensing and geographic information systems, are effective for research on soil element migration.

  7. Predicting sub-grid variability of soil water content from basic soil information

    Science.gov (United States)

    Qu, Wei; Bogena, Heye; Huisman, Johan Alexander; Vanderborght, Jan; Schuh, Max; Priesack, Eckart; Vereecken, Harry

    2015-04-01

    Knowledge of unresolved soil water content variability within model grid cells (i.e. sub-grid variability) is important for accurate predictions of land-surface energy and hydrologic fluxes. Here, we derived a closed-form expression to describe how soil water content variability depends on mean soil water content using stochastic analysis of 1D unsaturated gravitational flow based on the van Genuchten-Mualem (VGM) model. A sensitivity analysis of this closed-form expression showed that the n parameter strongly influenced both the shape and magnitude of the maximum of this relationship. In a next step, the closed-form expression was used to predict soil water content variability for eight datasets with varying soil texture using VGM parameters obtained from pedotransfer functions that rely on readily available soil information. Generally, there was good agreement between observed and predicted soil water content variability despite the obvious simplifications that were used to derive the closed-form expression (e.g. gravity flow in dry soils). A simplified closed-form expression that neglected the effect of pressure head fluctuations showed that the good performance in the dry soil range is related to the dominant role of the variability in MVG parameters determining water retention as compared to the effect of water flow. Furthermore, the novel closed-form expression was successfully used to inversely estimate the variability of hydraulic properties from observed data on soil water content variability from several test sites in Germany, China and Australia.

  8. Factors Affecting Sensitivity of Variable Charge Soils to Acid Rain

    Institute of Scientific and Technical Information of China (English)

    WANGJING-HUA

    1995-01-01

    The sensitivity of a large number of variable charge soils to acid rain was evaluated through examining pH-H2SO4 input curves.Two derivative parameters,the consumption of hydrogen ions by the soil and the acidtolerant limit as defined as the quantity of sulfuric acid required to bring the soil to pH 3.5 in a 0.001mol L-1 Ca(NO3)2 solution,were used.The sensitivity of variable charge soils was higher than that of constant charge soils,due to the predominance of kaolinite in clay mineralogical composition.Among these soils the sensitivity was generally of the order lateritic red soil>red soil> latosol.For a given type of soil within the same region the sensitivity was affected by parent material,due to differences in clay minerals and texture.The sensitivity of surface soil may be lower or higher than that of subsiol,depending on whether organic matter or texture plays the dominant role in determining the buffering capacity.Paddy soils consumed more acid within lower range of acid input when compared with upland soils,due to the presence of more exchangeable bases,but consumed less acid within higher acid input range,caused by the decrease in clay content.

  9. Searching for nonlocal lithologies in the Apollo 12 regolith: a geochemical and petrological study of basaltic coarse fines from the Apollo lunar soil sample 12023,155

    OpenAIRE

    Alexander, Louise; Snape, Joshua F.; Crawford, Ian; Joy, K. H.; Downes, Hilary

    2014-01-01

    New data from a petrological and geochemical examination of 12 coarse basaltic fines from the Apollo 12 soil sample 12023,155 provide evidence of additional geochemical diversity at the landing site. In addition to the bulk chemical composition, major, minor, and trace element analyses of mineral phases are employed to ascertain how these samples relate to the Apollo 12 lithological basalt groups, thereby overcoming the problems of representativeness of small samples. All of the samples studi...

  10. Geochemical speciation and dynamic of copper in tropical semi-arid soils exposed to metal-bearing mine wastes.

    Science.gov (United States)

    Perlatti, Fabio; Otero, Xosé Luis; Macias, Felipe; Ferreira, Tiago Osório

    2014-12-01

    The potentially hazardous effects of rock wastes disposed at open pit in three different areas (Pr: Ore processing; Wr: Waste rock and Bd: Border) of an abandoned copper mine were evaluated in this study, with emphasis on acid drainage generation, metal contamination and copper geochemical dynamics in soils. Samples of waste rock were analyzed by Energy dispersive X-ray fluorescence (XRF), scanning electron microscopy with microanalysis (SEM-EDS) and X-ray diffraction (XRD). Soil samples were analyzed to determine the total metal contents (XRF), mineralogy (XRD), pH (H2O and H2O2), organic and inorganic carbon, % of total N, S and P, particle size, and a sequential extraction procedure was used to identify the different copper fractions. As a result of the prevalence of carbonates over sulphides in the wastes, the soil pH remained close to neutral, with absence of acid mine drainage. The geochemical interaction between these mineral phases seems to be the main mechanism to release Cu(2)(+) ions. Total Cu in soils from the Pr area reached 11,180mg.kg(-1), while in Wr and Bd areas the values reached, on average, 4683 and 1086mg.kg(-1), respectively, indicating a very high level of soil contamination. In the Pr and Wr, the Cu was mainly associated with carbonates and amorphous iron oxides. In the Bd areas, the presence of vegetation has influenced the geochemical behavior of copper by increasing the dissolution of carbonates, affecting the buffer capacity of soils against sulphide oxidation, reducing the pH levels and enhancing the proportion of exchangeable and organic bound Cu. The present findings show that the use of plants or organic amendments in mine sites with high concentration of Cu carbonate-containing wastes should be viewed with caution, as the practice may enhance the mobilization of copper to the environment due to an increase in the rate of carbonates dissolution. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Geochemical behavior of radionuclides and heavy metals in soils from Corumbatai River basin (SP), Brazil; Comportamento geoquimico de radionuclideos e metais pesados em solos da bacia do Rio Corumbatai (SP)

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, Fabiano Tomazini da

    2004-07-01

    The purpose of this research was to study the geochemical behavior of radionuclides and heavy metals in soils of agricultural use at Corumbatai River basin (SP). The natural concentration and variability in sedimentary rocks at Corumbatai river basin follow the trend Ca > Mg > K > Na, with the concentration of heavy metals and radionuclides. The distribution of exposure rate in soils shows the occurrence of higher values towards south of the Corumbatai river basin, region where are applied phosphate fertilizers, amendments and 'vinhaca' in sugar cane crops. Heavy metals and radionuclides incorporated in phosphate fertilizers and amendments are annually added during the fertilization process in the sugar cane crops, but if they are utilized in accordance with the recommended rate, they do not rise the concentration levels in soils up to hazards levels. Thus, they are lower transferred from soils to sugar cane at Corumbatai river basin, not offering hazard to the ecosystem and animal or human health. (author)

  12. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    Directory of Open Access Journals (Sweden)

    José Paulo Molin

    2013-02-01

    Full Text Available Soil electrical conductivity (ECa is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semivariogram models, adjusted for soil moisture, had strong spatial dependence, but the relationship between soil moisture and soil ECa was obtained only in one of the experimental fields, where soil moisture and clay content range was higher. In this same field, coefficients of determinations between soil moisture and clay content were above 0.70. In the second field, the low soil moisture and clay content range explain the absence of a relationship between soil ECa and soil moisture. Data repetition over the years, suggested that ECa is a qualitative indicator in areas with high spatial variability in soil texture.

  13. REGIONAL SOIL WATER RETENTION IN THE CONTIGUOUS US: SOURCES OF VARIABILITY AND VOLCANIC SOIL EFFECTS

    Science.gov (United States)

    Water retention of mineral soil is often well predicted using algorithms (pedotransfer functions) with basic soil properties but the spatial variability of these properties has not been well characterized. A further source of uncertainty is that water retention by volcanic soils...

  14. REGIONAL SOIL WATER RETENTION IN THE CONTIGUOUS US: SOURCES OF VARIABILITY AND VOLCANIC SOIL EFFECTS

    Science.gov (United States)

    Water retention of mineral soil is often well predicted using algorithms (pedotransfer functions) with basic soil properties but the spatial variability of these properties has not been well characterized. A further source of uncertainty is that water retention by volcanic soils...

  15. Geochemical features of heavy metals distribution in soils under the influence of the non-ferrous metallurgy enterprises

    Directory of Open Access Journals (Sweden)

    YakovenkoO.V.

    2015-09-01

    Full Text Available Objects of researches are soil adjournment under the influence of the non-ferrous metallurgy enterprises. The total maintenance and the maintenance of mobile forms of heavy metalsdefined by means of a method of nuclear adsorption and the spectral analysis. Definition of forms of heavy metals spent with use of a method of consecutive extraction. As a result of researches it is established that the basic source of issue of heavy metals in environment is functioning of svintsovo-zinc industrial complex. It is established that heavy metals are in soils in residual, sorbed on hydroxides and organic forms. The share of the mobile form makes 16 %. It is shown that the maintenance of mobile forms of metals in the polluted soils exceeds indicators of pure soils. On geochemical indicators define level of pollution of soils. On factor of total pollution an ecological situation in a zone of influence of industrial complex it is estimated as catastrophic (ZC = 1,7·104.

  16. Geochemical assessment of light gaseous hydrocarbons in near-surface soils of Kutch–Saurashtra: Implication for hydrocarbon prospects

    Indian Academy of Sciences (India)

    P Lakshmi Srinivasa Rao; T Madhavi; D Srinu; M S Kalpana; D J Patil; A M Dayal

    2013-02-01

    Light hydrocarbons in soil have been used as direct indicators in geochemical hydrocarbon exploration, which remains an unconventional path in the petroleum industry. The occurrence of adsorbed soil gases, methane and heavier homologues were recorded in the near-surface soil samples collected from Kutch–Saurashtra, India. Soil gas alkanes were interpreted to be derived from deep-seated hydrocarbon sources and have migrated to the surface through structural discontinuities. The source of hydrocarbons is assessed to be thermogenic and could have been primarily derived from humic organic matter with partial contribution from sapropelic matter. Gas chromatographic analyses of hydrocarbons desorbed from soil samples through acid extraction technique showed the presence of methane through -butane and the observed concentrations (in ppb) vary from: methane (C1) from 4–291, ethane (C2) from 0–84, propane (C3) from 0–37, i-butane (iC4) from 0–5 and -butane (nC4) from 0–4. Carbon isotopes measured for methane and ethane by GC-C-IRMS, range between −42.9‰ to −13.3‰ (Pee Dee Belemnite – PDB) and −21.2‰ to −12.4‰ (PDB), respectively. The increased occurrence of hydrocarbons in the areas near Anjar of Kutch and the area south to Rajkot of Saurashtra signifies the area potential for oil and gas.

  17. Geochemical analysis of soils and sediments, Coeur d'Alene drainage basin, Idaho: sampling, analytical methods, and results

    Science.gov (United States)

    Box, Stephen E.; Bookstrom, Arthur A.; Ikramuddin, Mohammed; Lindsay, James

    2001-01-01

    This report presents the locations, descriptions, analytical procedures used, and an inter-lab comparison of over 1100 geochemical analyses of samples of soil and sediment in and downstream of a major lead-zinc-silver mining district in the Coeur d'Alene (CdA) drainage basin of northern Idaho. The samples fall in 3 broad categories: (1) samples from vertical profiles of floodplain soils in the valley of the main stem of the CdA River (767 samples) and of the South Fork of the CdA River (38 samples), (2) size fractionated surficial samples of sediment bedload within the channel of the South Fork of the CdA River (68 samples), and (3) samples from vertical profiles of sediment bedload within the channel of the main stem of the CdA River (260 samples). Five different laboratories contributed geochemical data for this report. Four of the five laboratories employed analytical methods that require sample dissolution prior to analysis; one laboratory (US Geological Survey) used analytical instrumentation (energy dispersive x-ray fluorescence [EDXRF]) that is applied to pulverized samples. Some dissolution procedures use four acids (hydrochloric, nitric, perchloric, and hydrofluoric; Eastern Washington University [EWU] Geochemical Laboratory and XRAL Laboratories, Inc.), others use two acids (nitric acid and aqua regia; CHEMEX Labs, Inc.), and some use only concentrated nitric acid (ACZ Laboratories, Inc.). Most analyses of dissolved samples were done by Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES) or by ICP - MS (Mass Spectroscopy). Some analyses for Ag and K were done by Flame Atomic Absorption (FAA). Inter-laboratory comparisons are made for 6 elements: lead (Pb), zinc (Zn), iron

  18. Plant uptake and geochemical phase distribution of Cd, Pb and Zn from soils after application of baghouse dust from the electric arc furnace production of steel

    Energy Technology Data Exchange (ETDEWEB)

    Rule, J.H. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Chemistry and Biochemistry; Adriano, D.C. [Georgia Univ., Savannah River Ecology Laboratory, Aiken (United States)

    1997-12-31

    The objectives of this study are to determine the uptake of Cd, Pb and Zn from two soils (silt loam and sandy loam) by the common dandelion, Taraxacum officinale Weber, and ragweed, Ambrosia artemisiifolia L., after application of varying rates of flue dust, to determine the geochemical phase distribution of Cd, Pb and Zn of treated soils, to examine the effect of pH on the phase distribution and plant uptake and to measure the correlation between plant uptake and metals in the geochemical phases. Carbonate, including metal hydroxides, was the major geochemical phase for the metals in the flue dust and treated soils. Especially for the plants grown on the silt loam, yield decreased dramatically as flue dust treatment rate increased and a significant pH effect was observed. Plant uptake of the metals increased with increasing treatment level but the pattern of uptake varied with the element and plant species. Concentrations of the metals were generally greater in plant roots than leaves or stems. Due to very low biomass at high treatment levels, neither species seems to have potential for stabilization of highly contaminated soils but further studies are warranted on the use of the dandelion as a phyto-monitor. Typically, there was a significant correlation between plant concentrations and levels in all soil geochemical phases for all metals. The results of this study confirm the utility of selective sequential chemical extractants in predicting plant uptake of trace metals from contaminated soils

  19. The geochemical characteristics of soils of vineyards and tea gardens before and after their use in the South of Russia

    Science.gov (United States)

    Alekseenko, Vladimir; Alekseenko, Alexey; Vlasova, Elena; Voronets, Svetlana

    2013-04-01

    The concentrations of 25 chemical elements in the forest soils, where formerly the vineyards and tea gardens were cultivated, and in the soils of functioning and abandoned 5, 10, 25, 30 and 50 years ago vineyards and tea gardens were considered. The loss and accumulation of elements were studied in the top-horizon (30 centimeters) during the human impact and after its ending. All the data are given with the probability of 95 %. The analyses of more than 1000 samples were used. Comparing to the forest soils, in the tea gardens soils has accumulated P (+702) and leached away Ge (-0.36), Yb (-0.54), Be (-0.84), Ba (-114) (in the gapes - concentration, tons per square kilometer). The leaching of row of elements has continued in the soils of abandoned plantations comparing to the forest soils with some changes in intensity; besides the accumulation of Mn (+318) and Ti (+804) had been occurred during the last 50 years. Comparing to the contemporary plantations in the soils of abandoned ones had been taken place the accumulation of elements during the last 50 years. Its maximum had manifested after 30 years: Mn (366) > Zn (34.8) > V (28.2) > Ni (6.6) > Ga (1.8) > Sn (0.4). The loss was detected for P. The intensity of all considered processes of loss and accumulation was spasmodic changing in the different time periods. During the last 50 years ecology-geochemical "recovery" of abandoned tea gardens soil has not happened. In the functioning vineyards soils, comparing to the initial forest soils has raised the concentrations of Cu (+16.1) and P (+96); declined - Bi (-0.12), Mo (-0.4), Co (-3), Ga (-4.3), Pb (-5.3), Li (-5.5), Mn (-126) and Ti (-684). In the soils of abandoned vineyards, comparing to the forest soils, during the last 25 years had been taken place accumulation of Mo (+0.7), Cr (+29.4), Cu (+50.3) and leaching away Co (-1.8), Ga (-3.7), Ni (-4.2), Li (-7.4). In the soils of abandoned vineyards, comparing to the functioning ones, during the last 25 years had

  20. Alaska Geochemical Database, Version 2.0 (AGDB2)--including “best value” data compilations for rock, sediment, soil, mineral, and concentrate sample media

    Science.gov (United States)

    Granitto, Matthew; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2013-01-01

    The Alaska Geochemical Database Version 2.0 (AGDB2) contains new geochemical data compilations in which each geologic material sample has one “best value” determination for each analyzed species, greatly improving speed and efficiency of use. Like the Alaska Geochemical Database (AGDB, http://pubs.usgs.gov/ds/637/) before it, the AGDB2 was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This relational database, created from the Alaska Geochemical Database (AGDB) that was released in 2011, serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables in several different formats describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey personnel and analyzed in U.S. Geological Survey laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various U.S. Geological Survey programs and projects from 1962 through 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy-mineral concentrate samples are included in this database. The AGDB2 includes historical geochemical data originally archived in the U.S. Geological Survey Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the U.S. Geological Survey PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate

  1. Characterization of soil water content variability and soil texture using GPR groundwave techniques

    Energy Technology Data Exchange (ETDEWEB)

    Grote, K.; Anger, C.; Kelly, B.; Hubbard, S.; Rubin, Y.

    2010-08-15

    Accurate characterization of near-surface soil water content is vital for guiding agricultural management decisions and for reducing the potential negative environmental impacts of agriculture. Characterizing the near-surface soil water content can be difficult, as this parameter is often both spatially and temporally variable, and obtaining sufficient measurements to describe the heterogeneity can be prohibitively expensive. Understanding the spatial correlation of near-surface soil water content can help optimize data acquisition and improve understanding of the processes controlling soil water content at the field scale. In this study, ground penetrating radar (GPR) methods were used to characterize the spatial correlation of water content in a three acre field as a function of sampling depth, season, vegetation, and soil texture. GPR data were acquired with 450 MHz and 900 MHz antennas, and measurements of the GPR groundwave were used to estimate soil water content at four different times. Additional water content estimates were obtained using time domain reflectometry measurements, and soil texture measurements were also acquired. Variograms were calculated for each set of measurements, and comparison of these variograms showed that the horizontal spatial correlation was greater for deeper water content measurements than for shallower measurements. Precipitation and irrigation were both shown to increase the spatial variability of water content, while shallowly-rooted vegetation decreased the variability. Comparison of the variograms of water content and soil texture showed that soil texture generally had greater small-scale spatial correlation than water content, and that the variability of water content in deeper soil layers was more closely correlated to soil texture than were shallower water content measurements. Lastly, cross-variograms of soil texture and water content were calculated, and co-kriging of water content estimates and soil texture

  2. Characterization of soil water content variability and soil texture using GPR groundwave techniques

    Energy Technology Data Exchange (ETDEWEB)

    Grote, K.; Anger, C.; Kelly, B.; Hubbard, S.; Rubin, Y.

    2010-08-15

    Accurate characterization of near-surface soil water content is vital for guiding agricultural management decisions and for reducing the potential negative environmental impacts of agriculture. Characterizing the near-surface soil water content can be difficult, as this parameter is often both spatially and temporally variable, and obtaining sufficient measurements to describe the heterogeneity can be prohibitively expensive. Understanding the spatial correlation of near-surface soil water content can help optimize data acquisition and improve understanding of the processes controlling soil water content at the field scale. In this study, ground penetrating radar (GPR) methods were used to characterize the spatial correlation of water content in a three acre field as a function of sampling depth, season, vegetation, and soil texture. GPR data were acquired with 450 MHz and 900 MHz antennas, and measurements of the GPR groundwave were used to estimate soil water content at four different times. Additional water content estimates were obtained using time domain reflectometry measurements, and soil texture measurements were also acquired. Variograms were calculated for each set of measurements, and comparison of these variograms showed that the horizontal spatial correlation was greater for deeper water content measurements than for shallower measurements. Precipitation and irrigation were both shown to increase the spatial variability of water content, while shallowly-rooted vegetation decreased the variability. Comparison of the variograms of water content and soil texture showed that soil texture generally had greater small-scale spatial correlation than water content, and that the variability of water content in deeper soil layers was more closely correlated to soil texture than were shallower water content measurements. Lastly, cross-variograms of soil texture and water content were calculated, and co-kriging of water content estimates and soil texture

  3. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    National Research Council Canada - National Science Library

    Anđelković Darko H; Anđelković Tatjana D; Nikolić Ružica S; Purenović Milovan M; Blagojević Srđan D; Bojić Aleksandar Lj; Ristić Milica M

    2012-01-01

    Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction...

  4. Does Soil Moisture Influence Climate Variability and Predictability over Australia?.

    Science.gov (United States)

    Timbal, B.; Power, S.; Colman, R.; Viviand, J.; Lirola, S.

    2002-05-01

    Interannual variations of Australian climate are strongly linked to the El Niño-Southern Oscillation (ENSO) phenomenon. However, the impact of other mechanisms on prediction, such as atmosphere-land surface interactions, has been less frequently investigated. Here, the impact of soil moisture variability on interannual climate variability and predictability is examined using the Bureau of Meteorology Research Centre atmospheric general circulation model. Two sets of experiments are run, each with five different initial conditions. In the first set of experiments, soil moisture is free to vary in response to atmospheric forcing in each experiment according to a set of simple prognostic equations. A potential predictability index is computed as the ratio of the model's internal variability to its external forced variability. This estimates the level of predictability obtained assuming perfect knowledge of future ocean surface temperatures. A second set of five experiments with prescribed soil moisture is performed. A comparison between these two sets of experiments reveals that fluctuations of soil moisture increase the persistence, the variance, and the potential predictability of surface temperature and rainfall. The interrelationship between these two variables is also strongly dependent upon the soil water content. Results are particularly marked over Australia in this model. A novel feature of this study is the focus on the effectiveness of ENSO-based statistical seasonal forecasting over Australia. Forecasting skill is shown to be crucially dependent upon soil moisture variability over the continent. In fact, surface temperature forecasts in this manner are not possible without soil moisture variability. This result suggests that a better representation of land-surface interaction has the potential to increase the skill of seasonal prediction schemes.

  5. Geochemical Investigation of Selected Elements in an Agricultural Soil: Case Study in Sumani Watershed West Sumatera in Indonesia

    Directory of Open Access Journals (Sweden)

    Aflizar

    2016-01-01

    Full Text Available This paper presents the geochemical study of agricultural soil and river sediments along Sumani watershed, West Sumatra in Indonesia. We examined the distribution and abundances of 16 elements (Pb, Zn, Cu, Ni, Cr,V, Sr, Rb, Ce, Th, Zr, Si, Ti, Fe Ca, and P in vegetable soil, sawah soil =and river sediment sample, to evaluate the factors controlling their abundances, possible sources, and environmental implications. Average concentrations of Pb, Zn, Cu, Ni, Cr,V, Sr, Rb, Ce, Th, Zr at vegetable (1 soil were 38, 88.3, 38.7, 3, 8, 101, 96, 98, 87, 31 and 218 mg kg-1 , 26, 39.05, 8.8, 13.5, 31, 231.5, 37, 19, 78, 16 and 303.5 mg kg-1 at sawah soil (3, 4 and 30, 61.6, 35.7, 9, 22, 294, 65, 12, 78, 14 and 232 mg kg-1 at river sediment (2, respectively. The concentration of Pb, Rb, Th and Zr at upland vegetables, V and Zr at sawah soil and river sediment were mostly two time Sumatra BCSCST or BCC in several samples. Enrichment factor values showed low to moderate enrichment of Pb, Zn, Cu, Rb, Ce and Zr, whereas Th showed significant contamination at vegetables soil, suggesting contributions from anthropogenic sources. Anthropogenic contributions of most metals mainly originate from natural processes. However, Pb, Ce, Th and Zr ranges of 527–108, 41-89, 66-117 and 35-100%, respectively, at Vegetable and sawah soil and river sediment confirm their anthropogenic contribution. Factor analysis and correlation matrices suggested that elevated metal concentrations at agricultural soil in Sumani watershed might be controlled by pH, CEC, Fe-oxy-hydroxides. Deposition of metals at vegetable and sawah soil and river sediment might be controlled by non-ferrous metal (i.e., aluminosilicates, sediment grain size, or source rock composition (andesite, alluvial fan, undifferentiated volcanic material, granite and gneiss.

  6. Identification of hydrologic and geochemical pathways using high frequency sampling, REE aqueous sampling and soil characterization at Koiliaris Critical Zone Observatory, Crete

    Energy Technology Data Exchange (ETDEWEB)

    Moraetis, Daniel, E-mail: moraetis@mred.tuc.gr [Department of Environmental Engineering, Technical University of Crete, 73100 Chania (Greece); Stamati, Fotini; Kotronakis, Manolis; Fragia, Tasoula; Paranychnianakis, Nikolaos; Nikolaidis, Nikolaos P. [Department of Environmental Engineering, Technical University of Crete, 73100 Chania (Greece)

    2011-06-15

    Highlights: > Identification of hydrological and geochemical pathways within a complex watershed. > Water increased N-NO{sub 3} concentration and E.C. values during flash flood events. > Soil degradation and impact on water infiltration within the Koiliaris watershed. > Analysis of Rare Earth Elements in water bodies for identification of karstic water. - Abstract: Koiliaris River watershed is a Critical Zone Observatory that represents severely degraded soils due to intensive agricultural activities and biophysical factors. It has typical Mediterranean soils under the imminent threat of desertification which is expected to intensify due to projected climate change. High frequency hydro-chemical monitoring with targeted sampling for Rare Earth Elements (REE) analysis of different water bodies and geochemical characterization of soils were used for the identification of hydrologic and geochemical pathways. The high frequency monitoring of water chemical data highlighted the chemical alterations of water in Koiliaris River during flash flood events. Soil physical and chemical characterization surveys were used to identify erodibility patterns within the watershed and the influence of soils on surface and ground water chemistry. The methodology presented can be used to identify the impacts of degraded soils to surface and ground water quality as well as in the design of methods to minimize the impacts of land use practices.

  7. THE SOIL-GEOCHEMICAL SUBSTANTIATION PRINCIPLES OF AN ESTIMATION OF HALOMORPHIC SOIL WITH THE PURPOSES OF FOREST MELIORATION

    Directory of Open Access Journals (Sweden)

    Gheorghe Jigau

    2006-10-01

    Full Text Available In Prut - Dniester interfluves the halomorphic soil meets practically in all soilgeographical areas and is characterized by a significant genetic variety. To them concern as interzones types sodium soil, saline soil and halomorphic soil of the large and small river valleys, and alkalized and solonchak genuses of zones chernozem’s soil. They are distributed both in flood land of the rivers, and outside of flood land. In outside flood lands they form large missives. On an outside flood lands territories they form island sites with the small area dated to an exit on a surface of salt Neogene clays or to territories testing constant or periodic humidifying more often.

  8. The origin of Cenozoic continental basalts in east-central China: Constrained by linking Pb isotopes to other geochemical variables

    Science.gov (United States)

    Xu, Zheng; Zheng, Yong-Fei; Zhao, Zi-Fu

    2017-01-01

    Cenozoic continental basalts in east-central China are characterized by OIB-like trace element patterns with more depleted to less enriched Sr-Nd isotope compositions. Such geochemical signatures are attributable to variable contributions to their mantle sources from crustal components in the oceanic subduction zone. A combined study of basalt Pb isotope variations with other geochemical variables indicates that four mantle and crustal components were involved in the basalt petrogenesis. Model calculations verify the geochemical transfer from the subducted crustal components to the mantle sources. The depleted MORB mantle component is indicated by the depleted Sr-Nd isotope compositions of basalts. Relatively high 206Pb/204Pb and low Δ8/4 ratios are ascribed to contributions from the igneous oceanic crust with high U/Pb and low Th/U ratios, low 206Pb/204Pb and high Δ8/4 ratios are ascribed to the lower continental crust, and high 206Pb/204Pb and high Δ8/4 ratios are linked to the seafloor sediment. This generates different compositions of mantle sources for these OIB-like continental basalts. The basalts with the most depleted Sr-Nd isotope compositions show Pb isotope compositions distinct from Pacific MORB but similar to Indian MORB, suggesting the occurrence of Indian type asthenospheric mantle beneath the continental lithosphere of eastern China. The depleted MORB mantle would be metasomatized by the three crustal components at the slab-mantle interface in oceanic subduction channel, generating the mantle sources that are enriched in melt-mobile incompatible trace elements and their pertinent radiogenic isotopes. Nevertheless, the crustal components were not directly incorporated in the forms of crustal rocks into the mantle sources, but underwent partial melting to produce the felsic melts that predominate the composition of those trace elements and their pertinent radiogenic isotopes in the basalts. As such, the depleted MORB mantle component was

  9. Geochemical soil survey of the Netherlands. Atlas of major and trace elements in topsoil and parent material; assessment of natural and anthropegenic enrichment factors

    NARCIS (Netherlands)

    Veer, G. van der

    2006-01-01

    Geochemical surveying is a generic tool to provide high quality, multi-element databases of the Earth’s surface compartments such as soil, sediment, and stream water. Such databases are not only an essential component of environmental knowledge, but also of relevance to other fields such as spatial

  10. Solid-solution partitioning of heavy metals in floodplain soils of the rivers Rhine and Meuse : Field sampling and geochemical modelling

    NARCIS (Netherlands)

    Schröder, T.J.

    2005-01-01

    In this study, the solid-solution partitioning of Cd, Cr, Cu, Ni, Pb, Zn and As in floodplain soils of the Dutch part of the rivers Rhine and Meuse is assessed by combining extensive field sampling with advanced geochemical modelling. The aim of this study was threefold: to develop tools to study th

  11. Constraints on the formation of geochemically variable plagiogranite intrusions in the Troodos Ophiolite, Cyprus

    Science.gov (United States)

    Freund, Sarah; Haase, Karsten M.; Keith, Manuel; Beier, Christoph; Garbe-Schönberg, Dieter

    2014-02-01

    The geochemistry and petrology of tonalitic to trondhjemitic samples ( n = 85) from eight different plagiogranite intrusions at the gabbro/sheeted dyke transition of the Troodos Ophiolite were studied in order to determine their petrogenetic relationship to the mafic plutonic section and the lava pile. The plagiogranitic rocks have higher SiO2 contents than the majority of the glasses of the Troodos lava pile, but lie on a continuation of the chemical trends defined by the extrusive rocks, indicating that the shallow intrusions generally represent crystallised magmas. We define three different groups of plagiogranites in the Troodos Ophiolite based on different incompatible element contents and ratios. The first and most common plagiogranite group has geochemical similarities to the tholeiitic lavas forming the lavas and sheeted dyke complex in the Troodos crust, implying that these magmas formed at a spreading axis. The second plagiogranite group occurs in one intrusion that is chemically related to late-stage and off-axis boninitic lavas and dykes. One intrusion next to the Arakapas fault zone consists of incompatible element-enriched plagiogranites which are unrelated to any known mafic crustal rocks. The similarities of incompatible element ratios between plagiogranites, lavas and mafic plutonic rocks, the continuous chemical trends defined by plagiogranites and mafic rocks, as well as incompatible element modelling results, all suggest that shallow fractional crystallisation is the dominant process responsible for formation of the felsic magmas.

  12. Pedogenesis, geochemical forms of heavy metals, and artifact weathering in an urban soil chronosequence, Detroit, Michigan

    Energy Technology Data Exchange (ETDEWEB)

    Howard, Jeffrey L., E-mail: jhoward@wayne.edu [Department of Geology, Wayne State University, Detroit, MI 48202 (United States); Olszewska, Dorota [Department of Geology, Wayne State University, Detroit, MI 48202 (United States)

    2011-03-15

    An urban soil chronosequence in downtown Detroit, MI was studied to determine the effects of time on pedogenesis and heavy metal sequestration. The soils developed in fill derived from mixed sandy and clayey diamicton parent materials on a level late Pleistocene lakebed plain under grass vegetation in a humid-temperate (mesic) climate. The chronosequence is comprised of soils in vacant lots (12 and 44 years old) and parks (96 and 120 years old), all located within 100 m of a roadway. An A-horizon 16 cm thick with 2% organic matter has developed after only 12 years of pedogenesis. The 12 year-old soil shows accelerated weathering of iron (e.g. nails) and cement artifacts attributed to corrosion by excess soluble salts of uncertain origin. Carbonate and Fe-oxide are immobilizing agents for heavy metals, hence it is recommended that drywall, plaster, cement and iron artifacts be left in soils at brownfield sites for their ameliorating effects. - Research highlights: > An A horizon has developed in these urban soils after only 12 years of pedogenesis. > Iron and cement artifacts have undergone accelerated weathering due to deicing salts. > One soil is contaminated by lead derived from weathered paint. > Artifact weathering can have ameliorating effects on urban soils contaminated by heavy metals. - Weathering of artifacts can have ameliorating effects on heavy metal-polluted soils at brownfield sites.

  13. Adsorption of Potassium and Calcium Ions by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    LIHONG-YAN; JIGUO-LIANG

    1992-01-01

    Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.

  14. Soil gas geochemical behaviour across buried and exposed faults during the 24 august 2016 central Italy earthquake

    Directory of Open Access Journals (Sweden)

    Giancarlo Ciotoli

    2016-12-01

    Full Text Available Following the earthquake (ML=6.0 of 24 August 2016 that affected large part of the central Apennine between the municipalities of Norcia (PG and Amatrice (RI (central Italy, two soil gas profiles (i.e., 222Rn, 220Rn, CO2 and CO2 flux were carried out across buried and exposed coseismic fault rupture of the Mt. Vettore fault during the seismic sequence. The objective of the survey was to explore the mechanisms of migration and the spatial behaviour of different gas species near still-degassing active fault. Results provide higher gas and CO2 flux values (about twice for 222Rn and CO2 flux in correspondence of the buried sector of the fault than those measured across the exposed coseismic rupture. Anomalous peaks due to advective migration are clearly visible on both side of the buried fault (profile 1, whereas the lower soil gas concentrations measured across the exposed coseimic rupture (profile 2 are mainly caused by shallow and still acting diffusive degassing associated to faulting during the seismic sequence. These results confirm the usefulness of the soil gas survey to spatially recognise the shallow geometry of hidden faults, and to discriminate the geochemical migration mechanisms occurring at buried and exposed faults related to seismic activity.

  15. Factor analysis of rock, soil and water geochemical data from Salem magnesite mines and surrounding area, Salem, southern India

    Science.gov (United States)

    Satyanarayanan, M.; Eswaramoorthi, S.; Subramanian, S.; Periakali, P.

    2017-09-01

    Geochemical analytical data of 15 representative rock samples, 34 soil samples and 55 groundwater samples collected from Salem magnesite mines and surrounding area in Salem, southern India, were subjected to R-mode factor analysis. A maximum of three factors account for 93.8 % variance in rock data, six factors for 84 % variance in soil data, five factors for 71.2 % in groundwater data during summer and six factors for 73.7 % during winter. Total dissolved solids are predominantly contributed by Mg, Na, Cl and SO4 ions in both seasons and are derived from the country rock and mining waste by dissolution of minerals like magnesite, gypsum, halite. The results also show that groundwater is enriched in considerable amount of minor and trace elements (Fe, Mn, Ni, Cr and Co). Nickel, chromium and cobalt in groundwater and soil are derived from leaching of huge mine dumps deposited by selective magnesite mining activity. The factor analysis on trivalent, hexavalent and total Cr in groundwater indicates that most of the Cr in summer is trivalent and in winter hexavalent. The gradational decrease in topographical elevation from northern mine area to the southern residential area, combined regional hydrogeological factors and distribution of ultramafic rocks in the northern part of the study area indicate that these toxic trace elements in water were derived from mine dumps.

  16. Factor analysis of rock, soil and water geochemical data from Salem magnesite mines and surrounding area, Salem, southern India

    Science.gov (United States)

    Satyanarayanan, M.; Eswaramoorthi, S.; Subramanian, S.; Periakali, P.

    2016-04-01

    Geochemical analytical data of 15 representative rock samples, 34 soil samples and 55 groundwater samples collected from Salem magnesite mines and surrounding area in Salem, southern India, were subjected to R-mode factor analysis. A maximum of three factors account for 93.8 % variance in rock data, six factors for 84 % variance in soil data, five factors for 71.2 % in groundwater data during summer and six factors for 73.7 % during winter. Total dissolved solids are predominantly contributed by Mg, Na, Cl and SO4 ions in both seasons and are derived from the country rock and mining waste by dissolution of minerals like magnesite, gypsum, halite. The results also show that groundwater is enriched in considerable amount of minor and trace elements (Fe, Mn, Ni, Cr and Co). Nickel, chromium and cobalt in groundwater and soil are derived from leaching of huge mine dumps deposited by selective magnesite mining activity. The factor analysis on trivalent, hexavalent and total Cr in groundwater indicates that most of the Cr in summer is trivalent and in winter hexavalent. The gradational decrease in topographical elevation from northern mine area to the southern residential area, combined regional hydrogeological factors and distribution of ultramafic rocks in the northern part of the study area indicate that these toxic trace elements in water were derived from mine dumps.

  17. [Soil nutrients spatial variability and soil fertility suitability in Qujing tobacco-planting area].

    Science.gov (United States)

    Li, Qiang; Zhou, Ji-heng; Yang, Rong-sheng; Zhang, Zheng-yan; Xie, Yan; Zhang, Yi-yang; Huang, Kua-ke; Li, Wei

    2011-04-01

    By adopting GPS technique, 2088 sampling sites were installed in the tobacco-planting area of Qujing City, Yunnan Province, with 0-20 cm soil samples collected to determine their main nutrients contents. The overall characteristics and spatial variability of the tobacco soil nutrients were analyzed by classic statistics and geo-statistics, and the soil fertility suitability in planting tobacco was evaluated by the methods of fuzzy mathematics. In the study area, soil pH and soil organic matter, available S, and water-soluble Cl contents were appropriate, soil total N and alkalihydrolyzable N contents were too high, soil available K, Ca, Mg, Cu, Fe, Zn, Mo, and Mn contents were abundant, soil available P content was at medium level, while soil total P and K and available B contents were insufficient. All the nutrient indices presented anisotropic distribution, among which, the spatial variability of soil available P and B was mainly caused by random factors, and that of other nutrients was caused by the co-effects of structural and random factors. The spatial distribution map of soil fertility suitability index (SFI) showed that there was no the excellent grade region for tobacco-planting, good grade region accounted for 8.0%, general grade region accounted for 51.6%, moderate grade region accounted for 39.0%, and low grade region accounted for 1.4%.

  18. Geochemical Properties of Rocks and Soils in Gusev Crater, Mars: APXS Results from Cumberland Ridge to Home Plate

    Science.gov (United States)

    Ming, D. W.; Gellert, R.; Morris, R. V.; Yen, A. S.; Arvidson, E.; Brueckner, J.; Clark, B. C.; Cohen, B. A.; Fleischer, I.; Klingelhoefer, G.; McCoy, T. J.; Mittlefehldt, D. W.; Schmidt, M. E.; Schroeder, C.; Squyres, S. W.; Zipfel, J.

    2008-01-01

    The Mars Exploration Rover Spirit landed in Gusev crater on Jan. 4, 2004. Spirit has traversed the Gusev crater plains, ascended to the top of Husband Hill, and entered into the Inner Basin of the Columbia Hills. The Athena science payload onboard Spirit has recorded numerous measurements on the chemistry and mineralogy of materials encountered during nearly 2 Mars years of operation within the crater. Rocks and soils have been grouped into classes based upon their unique differences in mineralogy and chemistry [1-3]. Some of the most significant chemical discoveries include the composition of Adirondack class flood basalts [4-6]; high sulfur in Clovis and Peace Class rocks [7,2]; high P and Ti in Wishstone Class rocks [7,2]; composition of alkalic basalts [2,6]; very high S in Paso Robles class soils [7,2], and the possible occurrence of a smectite-like chemical composition in Independence class rocks [8]. Water has played a significant role in the alteration of rocks and soils in the Columbia Hills. The occurrence of goethite and ferric sulfate alone suggests that liquid water was involved in their formation [3]. The pervasively altered materials in Husband Hill outcrops and rocks may have formed by the aqueous alteration of basaltic rocks, volcaniclastic materials, and/or impact ejecta by solutions that were rich in acid-volatile elements [2]. The objective of this paper is to provide an update on the health of the Alpha Particle X-ray Spectrometer (APXS) and to expand the geochemical dataset from sol 470 to sol 1368. Specific objectives are to (1) update the rock and soil classifications, (2) characterize elemental relationships among the major rock and soil classes, and (3) evaluate the involvement of water in the formation or alteration of the materials in these classes.

  19. Effect of Particle Size and Soil Compaction on Gas Transport Parameters in Variably Saturated, Sandy Soils

    DEFF Research Database (Denmark)

    Hamamoto, Shoichiro; Møldrup, Per; Kawamoto, Ken

    2009-01-01

    the water retention curve), both exhibiting similar and exponential relationships with D50. Under variably saturated conditions, higher Dp and ka in coarser sand (larger D50) were observed due to rapid gas diffusion and advection through the less tortuous large-pore networks. In addition, soil compaction......The soil gas diffusion coefficient (Dp) and air permeability (ka) and their dependency on soil air content ( ) control gas diffusion and advection in soils. This study investigated the effects of average particle size (D50) and dry bulk density ( b) on Dp and ka for six sandy soils under variably...... saturated conditions. Data showed that particle size markedly affects the effective diameter of the drained pores active in leading gas through the sample at –100 cm H2O of soil water matric potential (calculated from Dp and ka) as well as the average pore diameter at half saturation (calculated from...

  20. Geochemical sources, forms and phases of soil contamination in an industrial city.

    Science.gov (United States)

    Harvey, P J; Rouillon, M; Dong, C; Ettler, V; Handley, H K; Taylor, M P; Tyson, E; Tennant, P; Telfer, V; Trinh, R

    2017-04-15

    This study examines current soil contamination in an Australian industrial city, Newcastle. Public (roadside verges and parks) and private (homes) surface soils (n=170) contained metal(loid)s elevated above their respective Australian Health Investigation Levels (HIL). Lead (Pb), the most common contaminant in the city, exceeds the HIL for residential soils (HIL-A, 300mg/kg) in 88% of private soils (median: 1140mg/kg). In-vitro Pb bio-accessibility analysis of selected soils (n=11) using simulated gastric fluid showed a high affinity for Pb solubilisation (maximum Pb concentration: 5190mg/kg, equating to 45% Pb bio-accessibility). Highly soluble Pb-laden Fe- and Mn-oxides likely contribute to the bio-accessibility of the Pb. Public and private space surface soils contain substantially less radiogenic Pb (range: (208)Pb/(207)Pb: 2.345-2.411, (206)Pb/(207)Pb: 1.068-1.312) than local background soil ((208)Pb/(207)Pb: 2.489, (206)Pb/(207)Pb: 1.198), indicating anthropogenic contamination from the less radiogenic Broken Hill type Pb ores ((208)Pb/(207)Pb: 2.319, (206)Pb/(207)Pb: 1.044). Source apportionment using Pb isotopic ratio quantification and soil mineralogy indicate the city's historic copper and steel industries contributed the majority of the soil contaminants through atmospheric deposition and use of slag waste as fill material. High-temperature silicates and oxides combined with rounded particles in the soil are characteristic of smelter dust emissions. Additionally, a preliminary investigation of polycyclic aromatic hydrocarbons in soils, sometimes associated with ferrous metal smelting, coal processing or burning of fossil fuels, shows that these too pose a health exposure risk (calculated in comparison to benzo(a)pyrene: n=12, max: 13.5mg/kg, HIL: 3mg/kg). Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Sensitivity of soil respiration to variability in soil moisture and temperature in a humid tropical forest

    Science.gov (United States)

    Tana Wood; M. Detto; W.L. Silver

    2013-01-01

    Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m2), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal...

  2. Failure of geomaterials in variably saturated soils

    Science.gov (United States)

    Song, X.; Borja, R. I.

    2013-12-01

    The first law of thermodynamics suggests an energy-conjugate relationship among degree of saturation, suction stress, and density of an unsaturated porous material. Experimental evidence affirms that this constitutive relationship exists, and that the water retention curves are dependent on the specific volume or density of the material. This constitutive feature must be incorporated into the mathematical formulation of boundary-value problems involving finite deformation. We present a fully coupled hydromechanical formulation in the finite deformation range that incorporates the variation of degree of saturation with the Kirchhoff suction stress and the Jacobian determinant of the solid-phase motion. A numerical simulation of solid deformation-fluid flow in unsaturated soil with a random microstructure demonstrates an intricate but well-established coupling of the hydromechanical processes. As deformation localizes into a persistent shear band, we show that bifurcation of the hydromechanical response manifests itself not only in the form of a softening behavior but also through bifurcation of the state paths on the water-retention surface.

  3. Is Regional Root Reinforcement Controlled by Soil Moisture Variability?

    Science.gov (United States)

    Hales, T.; Ford, C. R.

    2011-12-01

    of "bound water" (water present in the cell wall), which in turn affected the strength of the cellulose fibrils that provide tensile strength. This phenomenon, which is the reason any wet wood is weaker than dry wood, results in a 50% difference in root tensile strength within the range of soil moisture measured in the field. We used a one-dimensional finite difference model to explore the effects of soil moisture on root cohesion. Our model shows that changes in the distribution of root biomass represent the primary control on root cohesion (representing up to 50% of intra-specific variability in root cohesion). Local changes in soil moisture result in ~20% change in the overall root cohesion. Our work suggest a feed-forward process in precipitation (and thus soil moisture), root strength changes, and debris flow hazard.

  4. Use of microwave digestion for estimation of heavy metal content of soils in a geochemical survey.

    Science.gov (United States)

    McGrath, D

    1998-07-01

    A procedure for the rapid and safe analysis of soils with widely differing organic matter contents has been investigated and validated. Surface soils, totalling 295 and sampled on a grid basis, representing 22% of the land-base of the Republic of Ireland, have been analysed for cadmium, chromium, copper, nickel, lead and zinc. Soil concentrations of cadmium, chromium, lead and nickel exhibit patterns of regionalised elevation. Implications of this elevation are considered in relation to sewage sludge application to land, future requirement for baseline surveys and concerns over concentrations in food products.

  5. Spatial Variability of Soil Cation Exchange Capacity in Hilly Tea Plantation Soils Under Different Sampling Scales

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies on the spatial variability of the soil cation exchange capacity (CEC) were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, (1) on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; (2) on the microscale, the soil CEC was also consumingly spatially dependent,and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to outhwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots.From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.

  6. Investigating soil controls on soil moisture spatial variability: Numerical simulations and field observations

    Science.gov (United States)

    Wang, Tiejun; Franz, Trenton E.; Zlotnik, Vitaly A.; You, Jinsheng; Shulski, Martha D.

    2015-05-01

    Due to its complex interactions with various processes and factors, soil moisture exhibits significant spatial variability across different spatial scales. In this study, a modeling approach and field observations were used to examine the soil control on the relationship between mean (θ bar) and standard deviation (σθ) of soil moisture content. For the numerical experiments, a 1-D vadose zone model along with van Genuchten parameters generated by pedotransfer functions was used for simulating soil moisture dynamics under different climate and surface conditions. To force the model, hydrometeorological and physiological data that spanned over three years from five research sites within the continental US were used. The modeling results showed that under bare surface conditions, different forms of the θ bar -σθ relationship as observed in experimental studies were produced. For finer soils, a positive θ bar -σθ relationship gradually changed to an upward convex and a negative one from arid to humid conditions; whereas, a positive relationship existed for coarser soils, regardless of climatic conditions. The maximum σθ for finer soils was larger under semiarid conditions than under arid and humid conditions, while the maximum σθ for coarser soils increased with increasing precipitation. Moreover, vegetation tended to reduce θ bar and σθ, and thus affected the θ bar -σθ relationship. A sensitivity analysis was also conducted to examine the controls of different van Genuchten parameters on the θ bar -σθ relationship under bare surface conditions. It was found that the residual soil moisture content mainly affected σθ under dry conditions, while the saturated soil moisture content and the saturated hydraulic conductivity largely controlled σθ under wet conditions. Importantly, the upward convex θ bar -σθ relationship was mostly caused by the shape factor n that accounts for pore size distribution. Finally, measured soil moisture data from a

  7. Soil respiration (CO2 efflux) response to spatio-temporal variability of soil water repellency

    Science.gov (United States)

    Urbanek, Emilia; Doerr, Stefan

    2017-04-01

    Soil water repellency (SWR) is a common feature of many soils which restricts water infiltration and movement within the soil. SWR is expected to become more spread according to current climatic prediction, but its effect on soil carbon dynamics and specifically on soil CO2 fluxes is still not clear. Based on previous laboratory experiments it has been suggested that water repellency reduces soil respiration, but the responses of soil CO2 efflux to naturally varying hydrological conditions created by SWR are not yet known. This is the first field-based study testing the hypothesis that water repellency indeed reduces soil CO2 efflux. In situ field measurements of soil CO2 fluxes, temperature, water contents and water repellency were carried out over three consecutive years at a grassland and pine forest site under the humid temperate climate of the UK. SWR was observed for the majority of the warmer period, but exhibited high spatial variability. Soils showed similar levels of extreme water repellency only on a few occasions following long dry spells and this indeed resulted in reduction in CO2 efflux. Spatially patchy SWR with variable soil moisture content induced the highest respiration rates, significantly higher than when SWR was absent. This rather unexpected behaviour can be explained by SWR-induced preferential flow which created flow paths with water and nutrients supply to the microorganisms, while water repellent zones provided air-filled pathways to facilitate soil-atmosphere gas exchanges. This study demonstrates that SWR can have contrasting effects on CO2 fluxes and, when spatially-variable, enhance CO2 efflux.

  8. Defining and modeling the soil geochemical background of heavy metals from the Hengshi River watershed (southern China): integrating EDA, stochastic simulation and magnetic parameters.

    Science.gov (United States)

    Zhou, Xu; Xia, Beicheng

    2010-08-15

    It is crucial to separate the soil geochemical background concentrations from anthropogenic anomalies and to provide a realistic environmental geochemical map honoring the fluctuations in original data. This study was carried out in the Hengshi River watershed, north of Guangdong, China and the method proposed combined exploratory data analysis (EDA), sequential indicator co-simulation (SIcS) and the ratio of isothermal remnant magnetization (S(100)=-IRM(-100 mT)/SIRM). The results showed that this is robust procedure for defining and mapping soil geochemical background concentrations in mineralized regions. The rock magnetic parameter helps to improve the mapping process by distinguishing anthropogenic influences. In this study, the geochemical backgrounds for four potentially toxic heavy metals (copper 200mg/kg; zinc 23 0mg/kg; lead 190 mg/kg and cadmium 1.85 mg/kg) Cu, Zn and Cd exceeded the soil Grade II limits (for pHgeochemical background level for Cd exceeds standard six times. Results suggest that local public health is at high-risk along the riparian region of the Hengshi River, although the watershed ecosystem has not been severely disturbed.

  9. On the role of "internal variability" on soil erosion assessment

    Science.gov (United States)

    Kim, Jongho; Ivanov, Valeriy; Fatichi, Simone

    2017-04-01

    Empirical data demonstrate that soil loss is highly non-unique with respect to meteorological or even runoff forcing and its frequency distributions exhibit heavy tails. However, all current erosion assessments do not describe the large associated uncertainties of temporal erosion variability and make unjustified assumptions by relying on central tendencies. Thus, the predictive skill of prognostic models and reliability of national-scale assessments have been repeatedly questioned. In this study, we attempt to reveal that the high variability in soil losses can be attributed to two sources: (1) 'external variability' referring to the uncertainties originating at macro-scale, such as climate, topography, and land use, which has been extensively studied; (2) 'geomorphic internal variability' referring to the micro-scale variations of pedologic properties (e.g., surface erodibility in soils with multi-sized particles), hydrologic properties (e.g., soil structure and degree of saturation), and hydraulic properties (e.g., surface roughness and surface topography). Using data and a physical hydraulic, hydrologic, and erosion and sediment transport model, we show that the geomorphic internal variability summarized by spatio-temporal variability in surface erodibility properties is a considerable source of uncertainty in erosion estimates and represents an overlooked but vital element of geomorphic response. The conclusion is that predictive frameworks of soil erosion should embed stochastic components together with deterministic assessments, if they do not want to largely underestimate uncertainty. Acknowledgement: This study was supported by the Basic Science Research Program of the National Research Foundation of Korea funded by the Ministry of Education (2016R1D1A1B03931886).

  10. The Baltic Sea: Geophysical and geochemical properties of Holocene sediment sequences as indicators of past environmental variability

    Science.gov (United States)

    Lenz, Conny; Reinholdsson, Maja; Zillén, Lovisa; Conley, Daniel J.; Snowball, Ian

    2010-05-01

    The Baltic Sea has undergone large environmental changes since the retreat of the Weischselian Ice-sheet. In the Late Glacial Period and the early Holocene these changes were most likely caused by natural environmental changes (i.e. changes in the morphology and depths of the Baltic basin and the sills). In more recent time anthropogenic impacts have become more important as a possible and likely cause for changes. During the whole Holocene period climate variability played an important role. However, the relative importance between humans and nature is largely unknown. Here we present the results of a combined geophysical and geochemical study on selected sediment sequences from the Baltic Sea within the two BONUS (Baltic Organisations Network For Funding Science) funded projects HYPER (HYPoxia mitigation for Baltic Sea Ecosystem Restoration) and Baltic GAS (GAS storage and effects of climate change and eutrophication). The over-all aim of these projects is to understand large-scale Baltic Sea ecosystem responses to environmental, climate and anthropogenic forcing. During two Baltic Sea research cruises in 2009 long sediment cores from 8 different locations were recovered. We present preliminary results from one site (LL19) located in the north central Baltic Proper at 169 m water depth. The Littorina Sea sediment record (i.e. the last c. 8000 years) is characterised by alternating periods of homogenised sediments (indicative of oxic conditions) and laminated sediments (indicative of hypoxic/anoxic conditions). Mineral magnetic properties illustrate clear changes between laminated and non-laminated sections of the core. The concentration of ferrimagnetic minerals, as revealed by initial magnetic susceptibility (χ) and saturation isothermal remanent magnetization (SIRM) is variable. The laminated sections in particular show high concentrations and to reveal the origin of the ferrimagnetic signal additional magnetic properties were measured, specifically the

  11. The Source, Spatial Distribution and Risk Assessment of Heavy Metals in Soil from the Pearl River Delta Based on the National Multi-Purpose Regional Geochemical Survey.

    Science.gov (United States)

    Zhang, Lingyan; Guo, Shuhai; Wu, Bo

    2015-01-01

    The data on the heavy metal content at different soil depths derived from a multi-purpose regional geochemical survey in the Pearl River Delta (PRD) were analyzed using ArcGIS 10.0. By comparing their spatial distributions and areas, the sources of heavy metals (Cd, Hg, As and Pb) were quantitatively identified and explored. Netted measuring points at 25 ×25 km were set over the entire PRD according to the geochemical maps. Based on the calculation data obtained from different soil depths, the concentrations of As and Cd in a large area of the PRD exceeded the National Second-class Standard. The spatial disparity of the geometric centers in the surface soil and deep soil showed that As in the surface soil mainly came from parent materials, while Cd had high consistency in different soil profiles because of deposition in the soil forming process. The migration of Cd also resulted in a considerable ecological risk to the Beijiang and Xijiang River watershed. The potential ecological risk index followed the order Cd ≥ Hg > Pb > As. According to the sources, the distribution trends and the characteristics of heavy metals in the soil from the perspective of the whole area, the Cd pollution should be repaired, especially in the upper reaches of the Xijiang and Beijiang watershed to prevent risk explosion while the pollution of Hg and Pb should be controlled in areas with intense human activity, and supervision during production should be strengthened to maintain the ecological balance of As.

  12. Comparing the Ability of Conventional and Digital Soil Maps to Explain Soil Variability using Diversity Indices

    Directory of Open Access Journals (Sweden)

    zohreh mosleh

    2017-06-01

    Full Text Available Introduction: Effective and sustainable soil management requires knowledge about the spatial patterns of soil variation and soil surveys are important and useful sources of data that can be used. Prior knowledge about the spatial distribution of the soils is the first essential step for this aim but this requires the collection of large amounts of soil information. However, the conventional soil surveys are usually not useful for providing quantitative information about the spatial distribution of soil properties that are used in many environmental studies. Recently, by the rapid development of the computers and technology together with the availability of new types of remote sensing data and digital elevation models (DEMs, digital and quantitative approaches have been developed. These new techniques relies on finding the relationships between soil properties or classes and the auxiliary information that explain the soil forming factors or processes and finally predict soil patterns on the landscape. Different types of the machine learning approaches have been applied for digital soil mapping of soil classes, such as the logistic and multinomial logistic regressions, neural networks and classification trees. In reality, soils are physical outcomes of the interactions happening among the geology, climate, hydrology and geomorphic processes. Diversity is a way of measuring soil variation. Ibanez (9 first introduced ecological diversity indices as measures of diversity. Application of the diversity indices in soil science have considerably increased in recent years. Taxonomic diversity has been evaluated in the most previous researches whereas comparing the ability of different soil mapping approaches based on these indices was rarely considered. Therefore, the main objective of this study was to compare the ability of the conventional and digital soil maps to explain the soil variability using diversity indices in the Shahrekord plain of

  13. Geochemical legacies and the future health of cities: A tale of two neurotoxins in urban soils

    Science.gov (United States)

    Fillipelli, Gabriel M.; Risch, Martin R.; Laidlaw, Mark A. S.; Nichols, Deborah E.; Crewe, Julie

    2015-01-01

    The past and future of cities are inextricably linked, a linkage that can be seen clearly in the long-term impacts of urban geochemical legacies. As loci of population as well as the means of employment and industry to support these populations, cities have a long history of co-locating contaminating practices and people, sometimes with negative implications for human health. Working at the intersection between environmental processes, communities, and human health is critical to grapple with environmental legacies and to support healthy, sustainable, and growing urban populations. An emerging area of environmental health research is to understand the impacts of chronic exposures and exposure mixtures—these impacts are poorly studied, yet may pose a significant threat to population health.

  14. Pedo-geochemical baseline content levels and soil quality reference values of trace elements in soils from the Mediterranean (Castilla La Mancha, Spain)

    Science.gov (United States)

    Ballesta, Raimundo; Bueno, Paz; Rubi, Juan; Giménez, Rosario

    2010-12-01

    To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg-1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg-1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination.

  15. Geochemical study of urban soils in public areas of an industrialized town (Ajka, western Hungary)

    Science.gov (United States)

    Zacháry, D.; Jordán, Gy.; Szabó, Cs.

    2012-04-01

    Soil is one of the most essential parts of urban ecosystem contributing to the biogeochemical cycles along the rock-soil-plant-animal and human pathway. Soil plays a fundamental role in plant nutrient uptake and groundwater filtration, too. Urban soils differ from non-urban soils in many aspects, including their origin, and they may also concentrate contaminants in large quantities due to intensive human activities. The pollution sources are industry, traffic, fertilizer, tailing and waste. In addition to the increasing rate of urban areas, urban soils are under growing interest and their pollution have received significant attention in the past few decades. This work focuses on the toxic element (As, Hg, Pb, Cu, Zn, Cd, Ni) content of soils and their spatial distribution in order to find a link between contamination sources and the receiving urban soils at sensitive receptor locations such as children's playgrounds and parks. Ajka town is located in western Hungary. It has an old-established industrial history with multiple contamination sources of heavy alumina industry and coal-based power plants supplied by the nearby bauxite and coal mines. At 44 locations 46 soil samples have been collected at a depth of 0-10 cm along a 1x1 km grid. The whole grid covers an area of 48 km2. In each grid cell a sampling site was selected at public areas. Sample preparation included drying at 40 C°, thorough homogenization and sieving to 2 mm fine earth before chemical analysis. Grain size distribution and soil pH were also determined. Samples were analyzed with ICP-OES and SEM methods. The As, Hg, Pb, Cu, Zn, Cd and Ni concentrations range from 2.07 ppm to 9.48 ppm, 0.02 ppm to 2.84 ppm, 5.08 ppm to 35.74 ppm, 2.55 ppm to 47.78 ppm, 17.00 ppm to 91.00 ppm, 0.07 ppm to 0.61 ppm and 5.57 ppm to 32.09 ppm, respectively. The results revealed the contaminated areas associated with past industrial sites. This study also identified locations with considerable contamination at

  16. Miscellaneous additives can enhance plant uptake and affect geochemical fractions of copper in a heavily polluted riparian grassland soil.

    Science.gov (United States)

    Rinklebe, Jörg; Shaheen, Sabry M

    2015-09-01

    The problem of copper (Cu) pollution in riverine ecosystems is world-wide and has significant environmental, eco-toxicological, and agricultural relevance. We assessed the suitability and effectiveness of application rate of 1% of activated charcoal, bentonite, biochar, cement kiln dust, chitosan, coal fly ash, limestone, nano-hydroxyapatite, organo-clay, sugar beet factory lime, and zeolite as soil amendments together with rapeseed as bioenergy crop as a possible remediation option for a heavily Cu polluted floodplain soil (total Cu=3041.9mgkg(-1)) that has a very high proportion of sorbed/carbonate fraction (484.6mgkg(-1)) and potential mobile fraction of Cu (1611.9mgkg(-1)). Application changed distribution of Cu among geochemical fractions: alkaline materials lead to increased carbonate bounded fraction and the acid rhizosphere zone might cause release of this Cu. Thus, mobilization of Cu and uptake of Cu by rapeseed were increased compared to the control (except for organo-clay) under the prevailing conditions.

  17. Spatial variability of soils in a seasonally dry tropical forest

    Science.gov (United States)

    Pulla, Sandeep; Riotte, Jean; Suresh, Hebbalalu; Dattaraja, Handanakere; Sukumar, Raman

    2016-04-01

    Soil structures communities of plants and soil organisms in tropical forests. Understanding the controls of soil spatial variability can therefore potentially inform efforts towards forest restoration. We studied the relationship between soils and lithology, topography, vegetation and fire in a seasonally dry tropical forest in southern India. We extensively sampled soil (available nutrients, Al, pH, and moisture), rocks, relief, woody vegetation, and spatial variation in fire burn frequency in a permanent 50-ha plot. Lower elevation soils tended to be less moist and were depleted in several nutrients and clay. The availability of several nutrients was, in turn, linked to whole-rock chemical composition differences since some lithologies were associated with higher elevations, while the others tended to dominate lower elevations. We suggest that local-scale topography in this region has been shaped by the spatial distribution of lithologies, which differ in their susceptibility to weathering. Nitrogen availability was uncorrelated with the presence of trees belonging to Fabaceae, a family associated with N-fixing species. No effect of burning on soil parameters could be discerned at this scale.

  18. SPATIAL VARIABILITY OF SOIL PROPERTIES IN AN AGRARIAN REFORM SETTLEMENT

    Directory of Open Access Journals (Sweden)

    James Ribeiro de Azevedo

    2015-12-01

    Full Text Available ABSTRACT The study of soil chemical and physical properties variability is important for suitable management practices. The aim of this study was to evaluate the spatial variability of soil properties in the Malhada do Meio settlement to subsidize soil use planning. The settlement is located in Chapadinha, MA, Brazil, and has an area of 630.86 ha. The vegetation is seasonal submontane deciduous forest and steppe savanna. The geology is formed of sandstones and siltstones of theItapecuru Formation and by colluvial and alluvial deposits. The relief consists of hills with rounded and flat tops with an average altitude of 67 m, and frequently covered over by ferruginous duricrusts. A total of 183 georeferenced soil samples were collected at the depth of 0.00-0.20 m inPlintossolos, Neossolo andGleissolo. The following chemical variables were analyzed: pH(CaCl2, H+Al, Al, SB, V, CEC, P, K, OM, Ca, Mg, SiO2, Al2O3, and Fe2O3; along with particle size variables: clay, silt, and sand. Descriptive statistical and geostatistical analyses were carried out. The coefficient of variation (CV was high for most of the variables, with the exception of pH with a low CV, and of sand with a medium CV. The models fitted to the experimental semivariograms of these variables were the exponential and the spherical. The range values were from 999 m to 3,690 m. For the variables pH(CaCl2, SB, and clay, there are three specific areas for land use planning. The central part of the area (zone III, where thePlintossolos Pétricos and Neossolos Flúvicos occur, is the most suitable for crops due to higher macronutrient content, organic matter and pH. Zones I and II are indicated for environmental preservation.

  19. Geochemical indicators and characterization of soil water repellence in three dominant ecosystems of Western Australia

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; Jordan, Antonio; Zavala, Lorena M.; Stevens, Jason; González-Pérez, Jose Antonio

    2016-04-01

    Introduction Soil water repellency (SWR) has critical implications for restoration of vegetation in degraded areas as it is responsible of poor plant establishment and a high incidence of erosion processes. Different organic substances are capable of inducing SWR but polar molecules such as certain fatty acids, and waxes i.e. esters and salts of fatty acids, appear to be the main constituents of hydrophobic coatings on soil mineral particles (Doerr et al., 2005). Plant species most commonly associated with SWR are evergreen trees with a considerable amount of resins, waxes or aromatic oils such as eucalypts and pines. Most of these substances are abundant in ecosystems and are released to soil by plants as root exudates or decaying organic debris, and by soil fauna, fungi and other microorganisms, but a thorough knowledge of substances capable of inducing hydrophobicity in soils is still not complete (Jordan et al., 2013). Although SWR has been reported in most continents of the world for different soil types, climate conditions and land uses, there are still many research gaps in this area, particularly in semi-arid areas largely affected by this phenomenon. Materials and methods This research was conducted in three dominant ecosystems of Western Australia (WA), e.g. semi-arid grassland in the Pilbara region (North WA), Banksia woodland, and a coastal dune (both located in South WA). These environments have different climate characteristics and soil types but similar vegetation communities. Soil samples were collected under the canopy of a broad range of plant species that compose the dominant vegetation communities of these ecosystems, and SWR was measured under lab conditions in oven-dry samples (48 h, 105 °C). Soil microbial activity was measured with the 1-day CO2 test, a cost-effective and rapid method to determine soil microbial respiration rate based on the measurement of the CO2 burst produced after moistening dry soil (Muñoz-Rojas et al., 2016). Soil p

  20. Soil fauna and its relation with environmental variables in soil management systems

    Directory of Open Access Journals (Sweden)

    Dilmar Baretta

    Full Text Available The present study aims to generate knowledge about the soil fauna, its relation to other explanatory environmental variables, and, besides it, to select edaphic indicators that more contribute to separate the land use systems (LUS. Five different LUS were chosen: conventional tillage with crop rotation (CTCR; no-tillage with crop rotation (NTCR; conventional tillage with crop succession (CTCS; no-tillage with crop succession (NTCS and minimum tillage with crop succession (MTCS. The samples were made in the counties Chapecó, Xanxerê and Ouro Verde located in the state of Santa Catarina, Brazil, and were considered the true replicates of the LUS. In each site, nine points were sampled in a sampling grid of 3 x 3. At the same points, soil was sampled for the physical, chemical and biological attributes (environmental variables. Pitfall traps were used to evaluate the soil fauna. Data were analyzed using principal component analysis (PCA and canonical discriminant analysis (CDA. The soil fauna presented potential to be used as indictors of soil quality, since some groups proved to be sensible to changes of the environmental variables and to soil management and tillage. The soil management using crop rotation (NTCR and CTCR presented higher diversity, compared to the systems using crop succession (NTCS, MTCS and NTCS, evidencing the importance of the soil tillage, independent of the season (summer or winter. The variable that better contributed to explain these changes were the chemical variables (potassium, pH, calcium, organic matter, available phosphorus, potential acidity, and biological variables (Shannon diversity index, Collembola, Pielou equitability index and microbial biomass carbon, respectively.

  1. Random spatial processes and geostatistical models for soil variables

    Science.gov (United States)

    Lark, R. M.

    2009-04-01

    Geostatistical models of soil variation have been used to considerable effect to facilitate efficient and powerful prediction of soil properties at unsampled sites or over partially sampled regions. Geostatistical models can also be used to investigate the scaling behaviour of soil process models, to design sampling strategies and to account for spatial dependence in the random effects of linear mixed models for spatial variables. However, most geostatistical models (variograms) are selected for reasons of mathematical convenience (in particular, to ensure positive definiteness of the corresponding variables). They assume some underlying spatial mathematical operator which may give a good description of observed variation of the soil, but which may not relate in any clear way to the processes that we know give rise to that observed variation in the real world. In this paper I shall argue that soil scientists should pay closer attention to the underlying operators in geostatistical models, with a view to identifying, where ever possible, operators that reflect our knowledge of processes in the soil. I shall illustrate how this can be done in the case of two problems. The first exemplar problem is the definition of operators to represent statistically processes in which the soil landscape is divided into discrete domains. This may occur at disparate scales from the landscape (outcrops, catchments, fields with different landuse) to the soil core (aggregates, rhizospheres). The operators that underly standard geostatistical models of soil variation typically describe continuous variation, and so do not offer any way to incorporate information on processes which occur in discrete domains. I shall present the Poisson Voronoi Tessellation as an alternative spatial operator, examine its corresponding variogram, and apply these to some real data. The second exemplar problem arises from different operators that are equifinal with respect to the variograms of the

  2. [Factors influencing the spatial variability in soil respiration under different land use regimes].

    Science.gov (United States)

    Chen, Shu-Tao; Liu, Qiao-Hui; Hu, Zheng-Hua; Liu, Yan; Ren, Jing-Quan; Xie, Wei

    2013-03-01

    In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated. Results indicated that land use regimes had significant effects on soil respiration. Soil respiration varied significantly (P DBH) of trees can be explained by a natural logarithmic function. A model composed of soil organic carbon (C, %), available phosphorous (AP, g x kg(-1)) and diameter at breast height (DBH, cm) explained 92.8% spatial variability in soil respiration for forest ecosystems.

  3. Soil moisture variability across different scales in an Indian watershed for satellite soil moisture product validation

    KAUST Repository

    Singh, Gurjeet

    2016-05-05

    Strategic ground-based sampling of soil moisture across multiple scales is necessary to validate remotely sensed quantities such as NASA’s Soil Moisture Active Passive (SMAP) product. In the present study, in-situ soil moisture data were collected at two nested scale extents (0.5 km and 3 km) to understand the trend of soil moisture variability across these scales. This ground-based soil moisture sampling was conducted in the 500 km2 Rana watershed situated in eastern India. The study area is characterized as sub-humid, sub-tropical climate with average annual rainfall of about 1456 mm. Three 3x3 km square grids were sampled intensively once a day at 49 locations each, at a spacing of 0.5 km. These intensive sampling locations were selected on the basis of different topography, soil properties and vegetation characteristics. In addition, measurements were also made at 9 locations around each intensive sampling grid at 3 km spacing to cover a 9x9 km square grid. Intensive fine scale soil moisture sampling as well as coarser scale samplings were made using both impedance probes and gravimetric analyses in the study watershed. The ground-based soil moisture samplings were conducted during the day, concurrent with the SMAP descending overpass. Analysis of soil moisture spatial variability in terms of areal mean soil moisture and the statistics of higher-order moments, i.e., the standard deviation, and the coefficient of variation are presented. Results showed that the standard deviation and coefficient of variation of measured soil moisture decreased with extent scale by increasing mean soil moisture. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  4. Geochemical properties of soils surrounding the Deliklitaş Au deposit, Turkey

    Science.gov (United States)

    Kirat, Güllü; Aydin, Nasuh

    2016-08-01

    The Deliklitaş gold deposit is in northwest Turkey, where a renowned gold province containing many major hydrothermal deposits related to Tertiary volcanic rocks. Because of the limited outcrops in the region, one of the most effective ways to prospect for new deposits is soil sampling. In this study, 183 soil samples were systematically collected from the area around the Deliklitaş Au deposit. Metal content of the samples, and their relationships and distribution according to distance away from the ore body were statistically investigated. The analysis of metals and metalloids in soil samples yielded the following metal ranges: Au from 0.005 to 0.54 mg/kg (average 0.04); Ag from 0.03 to 2.66 (average 0.22); As from 3.4 to 315 (average 30.3); Sb from 0.15 to 19.25 (average 1.62); Cu from 2.5 to 35 (average 11.73); Pb from 17.4 to 545 (average 73.76) and from Zn 14-1240 mg/kg of soil (average 106.71). For the areal distribution of metals 50%, 70%, 90% and 95% of the cumulative data were used for contouring element contents in the soils, using 50% as the baseline value and 95% as the anomalous value. Eigen values, Varimax Rotation method with Kaiser Normalization tested and determined the suitability of the number of data sets. Factor numbers were determined as 3, according to Eigen values determined for the soil samples. Factor 1 refers to ore minerals of epithermal system, Factor 2 refers to main rock sources of Pb and Zn and Factor 3 refers to environmental effects. Agsbnd Au, Pbsbnd Zn and Sbsbnd As pairs show high correlation in the cluster analysis indicating element relations. Please add an overarching sentence here, on implications etc.

  5. Utilization of humus-rich forest soil (mull) in geochemical exploration for gold

    Science.gov (United States)

    Curtin, Gary C.; Lakin, H.W.; Neuerburg, G.J.; Hubert, A.E.

    1968-01-01

    Distribution of gold in humus-rich forest soil (mull) reflects the known distribution of gold deposits in bedrock in the Empire district, Colorado. Gold from the bedrock is accumulated by pine and aspen trees and is concentrated in the mull by the decay of organic litter from the trees. Anomalies in mull which do not coincide with known gold deposits merit further exploration. The gold anomalies in soil (6- to 12-inch depth) and in float pebbles and cobbles poorly reflect the known distribution of gold deposits in bedrock beneath the extensive cover of colluvium and glacial drift.

  6. Geochemistry of soils along a transect from Central Mexico to the Pacific Coast: a pilot study for continental-scale geochemical mapping

    Science.gov (United States)

    Chiprés, J.A.; de la Calleja,; Tellez, J.I.; Jiménez, F.; Cruz, Carlos; Guerrero, E.G.; Castro, J.; Monroy, M.G.; Salinas, J.C.

    2009-01-01

    The Mexican Geological Survey (SGM), the National Institute of Statistics, Geography and Informatics (INEGI) and the Autonomous University of San Luis Potosi (UASLP) have established a multidisciplinary team with the objective of creating a national program of geochemical mapping of soils in Mexico. This is being done as part of the North American Soil Geochemical Landscapes Project in partnership with the US Geological Survey and the Geological Survey of Canada. As the first step, a pilot study was conducted over a transect that extends from the Mexico–US border near Ciudad Juarez in the north to the Pacific Ocean in the south. This pilot transect was conducted in two phases, and this paper presents results from the first phase, which sampled soils at about a 40-km spacing along a 730-km transect beginning in Central Mexico and ending at the Pacific Coast. Samples were collected from the A and C horizons at each site and 60 elements were analyzed. This pilot study demonstrates that geochemical mapping based on a 40-km spacing is adequate to identify broad-scale geochemical patterns. Geologic influence (i.e., soil parent material) was the most important factor influencing the distribution of elements along the transect, followed by the influence of regional mineralization. The study also showed that influence by human activities over the transect is minimal except possibly in large mining districts. A comparison of element abundance in the A horizon with the environmental soil guidelines in Mexico showed that the natural concentrations of the studied soils were lower than the established threshold for soil restoration with the exception of V and As. The former had a median value (75 mg/kg) approximately equal to the value established in Mexico for soil restoration in agricultural and residential lands (78 mg/kg), and the latter had three values higher than the 22 mg/kg threshold for soil restoration in agricultural and residential lands. These cases demonstrate

  7. Adsorption of Potassium and Sodium Ions by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    LIHONG-YAN; JIGUO-LIANG

    1992-01-01

    Adsorption of potassium and sodium ions by four typical variable charge soils of South China was studied.The results indicated that the variable charge soils saturated with H and Al showed a much higher preference for potassium ions relative to sodium ions,and this tendence could not be changed by such factors as the pH,the concentration of the cations,the dielectric constant of solvent,the accompanying anions and the iron oxide content etc.,suggesting that this difference in affinity is caused by the difference in the nature of the two cations.It was observed that a negative adsorption of sodium ions by latosol and lateritic red soil in a mixed system containing equal amount of potassium and sodium ions at low pH,which is caused by a competitive adsorption of potassium and sodium ions and repulsion of positive charge on the surfaces of soil particles for cations.The adsorption of potassium and sodium ions increased with the decreases in the dielectric constant of solvent and the iron oxide content.Sulfate affected the adsorption of potassium and sodium ions through changing the surface properties of the soils.

  8. Geochemical and microbial effects on the mobilization of arsenic in mine tailing soils.

    Science.gov (United States)

    Lee, Keun-Young; Kim, Kyoung-Woong; Kim, Soon-Oh

    2010-02-01

    Arsenic (As) contamination has become a serious environmental problem in many countries. We have performed batch-type leaching experiments on mine tailing soils collected from three abandoned mine areas in South Korea with the objective of evaluating the effect of indigenous bacterial activity on As mobilization. The analysis of physicochemical properties and mineralogical compositions of the samples indicated that the secondary minerals or phases formed as a result of the oxidation or alteration of primary minerals were associated with the labile and bioleachable fractions of As. Compared to simulated abiotic processes using sterilization, the indigenous bacteria activated using a carbon source were able to enhance the dissolution of As under both aerobic and anaerobic conditions. The bacterial dissolution of iron (Fe) and manganese (Mn) was found to occur simultaneously with the dissolution of As, suggesting that the main bacterial mechanism was via the dissimilatory reduction of Fe(III), Mn(IV), and As(V). An anaerobic environment was more favorable for the prominent dissolution of As in the tailing soils. These results indicate that the mobilization of As can be enhanced in the oxygen-depleted part of the tailing dump, particularly with the infiltration of organic substrates. The difference in the degree of As lixiviation between the three tailing soils was found to be related to the bioavailability of As as well as the original biomass in the tailing soils.

  9. Assessing the geochemical variability of oil shale in the Attarat Um Ghudran deposit, Jordan

    Directory of Open Access Journals (Sweden)

    Margus Voolma

    2016-05-01

    Full Text Available The Cretaceous to Palaeogene oil shale (OS of Jordan is predominantly calcareous mudstone with intervals of mostly siliceous minerals, quartz and cristobalite–tridymite. Oil shale is rich in organic sulphur and trace elements. According to preliminary micropalaeontological data, the OS succession of the studied area, the south-central part of the Attarat Um Ghudran (AUG deposit in central Jordan, is of Maastrichtian age. A representative collection of 392 samples from 9 drill cores reliably characterizes the sequence of the OS seam, on average 70 m thick. The composition of AUG OS varies significantly. The major compounds CaO and SiO2 range within 3–70 wt% and 10–50 wt%, respectively, and also the contents of organic matter, MgO, P2O5, Al2O3 and S change. The concentrations of metals (especially Zn, V, Cr, Ni and Mo change many dozens of times in the cross section. The aim of our statistical analysis was to determine the most significant OS types and their positions in the OS sequence. Two multivariate statistical analysis methods, principal components analysis (PCA and hierarchical clustering of PCA groups, gave an interpretable result. Four principal components account for 88.6% of data variability. Variation in six main chemical components or groups of components is reflected in parameters of the four principal components. The component PC1 accounts for 47% of the data variance, expressing the highest correlation with organic matter, S, Cr, Cu, Ni, Zn, Mo, and PC2 accounts for 22.82% of the data variability, being strongly correlated with TiO2, Al2O3, Fe2O3, SiO2 and K2O and negatively correlated with CaO. The next two significant component groups express covariance with CaO and MgO. The applied statistical analysis proves to be a powerful tool for the interpretation of the chemically variable structure of the OS unit when using a representative enough sample collection. In the complex study of the OS unit, variation in the chemical

  10. The geochemical atlas of Alaska, 2016

    Science.gov (United States)

    Lee, Gregory K.; Yager, Douglas B.; Mauk, Jeffrey L.; Granitto, Matthew; Denning, Paul D.; Wang, Bronwen; Werdon, Melanie B.

    2016-06-21

    A rich legacy of geochemical data produced since the early 1960s covers the great expanse of Alaska; careful treatment of such data may provide significant and revealing geochemical maps that may be used for landscape geochemistry, mineral resource exploration, and geoenvironmental investigations over large areas. To maximize the spatial density and extent of data coverage for statewide mapping of element distributions, we compiled and integrated analyses of more than 175,000 sediment and soil samples from three major, separate sources: the U.S. Geological Survey, the National Uranium Resource Evaluation program, and the Alaska Division of Geological & Geophysical Surveys geochemical databases. Various types of heterogeneity and deficiencies in these data presented major challenges to our development of coherently integrated datasets for modeling and mapping of element distributions. Researchers from many different organizations and disparate scientific studies collected samples that were analyzed using highly variable methods throughout a time period of more than 50 years, during which many changes in analytical techniques were developed and applied. Despite these challenges, the U.S. Geological Survey has produced a new systematically integrated compilation of sediment and soil geochemical data with an average sample site density of approximately 1 locality per 10 square kilometers (km2) for the entire State of Alaska, although density varies considerably among different areas. From that compilation, we have modeled and mapped the distributions of 68 elements, thus creating an updated geochemical atlas for the State.

  11. EVALUATION OF GEOCHEMICAL QUALITY CONTROL IN DETERMINATION OF Mn IN SOILS USING A SEQUENTIAL CHEMICAL EXTRACTION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Sequential chemical extraction procedure has been widely used to partition particulate trace metals into various fractions and to describe the distribution and the statue of trace metals in geo-environment. One sequential chemical extraction procedure was employed here to partition various fractions of Mn in soils. The experiment was designed with quality controlling concept in order to show sampling and analytical error. Experimental results obtained on duplicate analysis of all soil samples demonstrated that the precision was less than 10% (at 95% confidence level). The accuracy was estimated by comparing the accepted total concentration of Mn in standard reference materials (SRMs) with the measured sum of the individual fractions. The recovery of Mn from SRM1 and SRM2 was 94.1% and 98.4% , respectively. The detection limit, accuracy and precision of the sequential chemical extraction procedure were discussed in detailed. All the results suggest that the trueness of the analytical method is satisfactory.

  12. Spatial variability of soil salinity in coastal saline soil at different scales in the Yellow River Delta, China.

    Science.gov (United States)

    Wang, Zhuoran; Zhao, Gengxing; Gao, Mingxiu; Chang, Chunyan

    2017-02-01

    The objectives of this study were to explore the spatial variability of soil salinity in coastal saline soil at macro, meso and micro scales in the Yellow River delta, China. Soil electrical conductivities (ECs) were measured at 0-15, 15-30, 30-45 and 45-60 cm soil depths at 49 sampling sites during November 9 to 11, 2013. Soil salinity was converted from soil ECs based on laboratory analyses. Our results indicated that at the macro scale, soil salinity was high with strong variability in each soil layer, and the content increased and the variability weakened with increasing soil depth. From east to west in the region, the farther away from the sea, the lower the soil salinity was. The degrees of soil salinization in three deeper soil layers are 1.14, 1.24 and 1.40 times higher than that in the surface soil. At the meso scale, the sequence of soil salinity in different topographies, soil texture and vegetation decreased, respectively, as follows: depression >flatland >hillock >batture; sandy loam >light loam >medium loam >heavy loam >clay; bare land >suaeda salsa >reed >cogongrass >cotton >paddy >winter wheat. At the micro scale, soil salinity changed with elevation in natural micro-topography and with anthropogenic activities in cultivated land. As the study area narrowed down to different scales, the spatial variability of soil salinity weakened gradually in cultivated land and salt wasteland except the bare land.

  13. Spatial variability of soil properties and soil erodibility in the Alqueva dam watershed, Portugal

    Science.gov (United States)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-01-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this, three areas representative of different land uses (agroforestry grassland, Lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while K factor increased with intensive cultivation. The HJ-biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  14. Spatial variability of soil properties and soil erodibility in the Alqueva reservoir watershed

    Science.gov (United States)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-04-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this end, three areas representative of different land uses (agroforestry grassland, lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while the K factor increased with intensive cultivation. The HJ-Biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. The K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  15. Spatial variability of soil properties and soil erodibility in the Alqueva dam watershed, Portugal

    Directory of Open Access Journals (Sweden)

    V. Ferreira

    2015-01-01

    Full Text Available The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this, three areas representative of different land uses (agroforestry grassland, Lucerne crop and olive orchard were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation, vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while K factor increased with intensive cultivation. The HJ-biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  16. Temporal Changes in the Spatial Variability of Soil Nutrients

    Energy Technology Data Exchange (ETDEWEB)

    R. L. Hoskinson; J. R. Hess; R. S. Alessi

    1999-07-01

    This paper reports the temporal changes in the spatial variability of soil nutrient concentrations across a field during the growing season, over a four-year period. This study is part of the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. Uniform fertilization did not produce a uniform increase in fertility. During the growing season, several of the nutrients and micronutrients showed increases in concentration although no additional fertilization had occurred. Potato plant uptake did not explain all of these changes. Some soil micronutrient concentrations increased above levels considered detrimental to potatoes, but the plants did not show the effects in reduced yield. All the nutrients measured changed between the last sampling in the fall and the first sampling the next spring prior to fertilization. The soil microbial community may play a major role in the temporal changes in the spatial variability of soil nutrient concentrations. These temporal changes suggest potential impact when determining fertilizer recommendations, and when evaluating the results of spatially varying fertilizer application.

  17. Predicting subgrid variability of soil water content from basic soil information

    Science.gov (United States)

    Qu, W.; Bogena, H. R.; Huisman, J. A.; Vanderborght, J.; Schuh, M.; Priesack, E.; Vereecken, H.

    2015-02-01

    Knowledge of unresolved soil water content variability within model grid cells (i.e., subgrid variability) is important for accurate predictions of land-surface energy and hydrologic fluxes. Here we derived a closed-form expression to describe how soil water content variability depends on mean soil water content (σθ()) using stochastic analysis of 1-D unsaturated gravitational flow based on the van Genuchten-Mualem (VGM) model. A sensitivity analysis showed that the n parameter strongly influenced both the shape and magnitude of the maximum of σθ(). The closed-form expression was used to predict σθ() for eight data sets with varying soil texture using VGM parameters obtained from pedotransfer functions that rely on available soil information. Generally, there was good agreement between observed and predicted σθ() despite the obvious simplifications that were used to derive the closed-form expression. Furthermore, the novel closed-form expression was successfully used to inversely estimate the variability of hydraulic properties from observed σθ() data.

  18. Phosphate stable oxygen isotope variability within a temperate agricultural soil.

    Science.gov (United States)

    Granger, Steven J; Harris, Paul; Peukert, Sabine; Guo, Rongrong; Tamburini, Federica; Blackwell, Martin S A; Howden, Nicholas J K; McGrath, Steve

    2017-01-01

    In this study, we conduct a spatial analysis of soil total phosphorus (TP), acid extractable phosphate (PO4) and the stable oxygen (O) isotope ratio within the PO4 molecule (δ(18)OPO4 ) from an intensively managed agricultural grassland site. Total P in the soil was found to range from 736 to 1952 mg P kg(- 1), of which between 12 and 48% was extractable using a 1 M HCl (HClPO4 ) solution with the two variables exhibiting a strong positive correlation. The δ(18)OPO4 of the extracted PO4 ranged from 17.0 to 21.6‰ with a mean of 18.8‰ (± 0.8). While the spatial variability of Total P has been researched at various scales, this is the first study to assess the variability of soil δ(18)OPO4 at a field-scale resolution. We investigate whether or not δ(18)OPO4 variability has any significant relationship with: (i) itself with respect to spatial autocorrelation effects; and (ii) HClPO4 , elevation and slope - both globally and locally. Results indicate that δ(18)OPO4 was not spatially autocorrelated; and that δ(18)OPO4 was only weakly related to HClPO4 , elevation and slope, when considering the study field as a whole. Interestingly, the latter relationships appear to vary in strength locally. In particular, the δ(18)OPO4 to HClPO4 relationship may depend on the underlying soil class and/or on different field managements that had operated across an historical north-south field division of the study field, a division that had been removed four years prior to this study.

  19. Geochemical Assessment of the Impact of Mine Tailings Reclamation on the Quality of Soils at AngloGold Concession, Obuasi, Ghana

    Directory of Open Access Journals (Sweden)

    Enoch Boateng

    2012-04-01

    Full Text Available This study assessed the geochemical impact of mine tailings reclamation on the quality of soils from the AngloGold Concession, Obuasi, Ghana. Soil samples from mine tailings reclamation sites were evaluated for the concentrations of plant nutrients and trace metals. Contaminations of trace metals, using geochemical pollution indices were used to assess possible effects on agriculture and livelihoods. The average pH ranges from 7.6 to 8.4 at the ex-tailing sites whiles the control site is 6.0. Organic carbon and nitrogen levels at the extailings site are low due to topsoil loss. Average available P and K levels were low or very low; i.e., <20 and <40 mg/kg, respectively at both ex-tailing and control sites. Average EC values as well as individual values of all the soils were less than 2 dS/m, while average ESP and individual soil values were less than 15%, indicating that the soils are non saline. Average ECEC levels, contributed by Ca and Mg, are medium at the ex-tailing sites but low at the control sites. The concentrations of arsenic (As, copper (Cu, lead (Pb and zinc (Zn were compared to their respective background concentrations to calculate their contamination factors and geo-accumulation indices at all the examined areas. Average concentration values for As are consistently high; presenting the highest value of 426.67 mg/kg at Area 3 and the least of 72.03 mg/kg at the control site, above the Netherlands soil/sediment intervention guideline value of 55 mg/kg for remediation. Furthermore, estimates from the geochemical evaluations indicated that As contamination was very high and therefore poses a threat to agricultural land use as well as general environmental quality.

  20. Use of Soil Moisture Variability in Artificial Neural Network Retrieval of Soil Moisture

    Directory of Open Access Journals (Sweden)

    Bert Veenendaal

    2009-12-01

    Full Text Available Passive microwave remote sensing is one of the most promising techniques for soil moisture retrieval. However, the inversion of soil moisture from brightness temperature observations is not straightforward, as it is influenced by numerous factors such as surface roughness, vegetation cover, and soil texture. Moreover, the relationship between brightness temperature, soil moisture and the factors mentioned above is highly non-linear and ill-posed. Consequently, Artificial Neural Networks (ANNs have been used to retrieve soil moisture from microwave data, but with limited success when dealing with data different to that from the training period. In this study, an ANN is tested for its ability to predict soil moisture at 1 km resolution on different dates following training at the same site for a specific date. A novel approach that utilizes information on the variability of soil moisture, in terms of its mean and standard deviation for a (sub region of spatial dimension up to 40 km, is used to improve the current retrieval accuracy of the ANN method. A comparison between the ANN with and without the use of the variability information showed that this enhancement enables the ANN to achieve an average Root Mean Square Error (RMSE of around 5.1% v/v when using the variability information, as compared to around 7.5% v/v without it. The accuracy of the soil moisture retrieval was further improved by the division of the target site into smaller regions down to 4 km in size, with the spatial variability of soil moisture calculated from within the smaller region used in the ANN. With the combination of an ANN architecture of a single hidden layer of 20 neurons and the dual-polarized brightness temperatures as input, the proposed use of variability and sub-region methodology achieves an average retrieval accuracy of 3.7% v/v. Although this accuracy is not the lowest as comparing to the research in this field, the main contribution is the ability of ANN in

  1. Kinetics and Mechanism of Metal Retention/Release in Geochemical Processes in Soil - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Robert W.

    2000-12-29

    Effective, remediation of soils contaminated with heavy metals requires a better understanding of the mechanisms by which the metals are retained/released in soils over a long period of time. Studies on reaction of Cr(VI) with iron-rich clays indicated that structural iron (II) in these surfaces is capable of reducing chromate to chromium (III). We found that iron (II) either found naturally or produced by treatment of clay with sodium dithionite, effectively reduced Cr (VI) to Cr (III). Thus, in situ remediation of chromium combines reduction of Cr (VI) to Cr (III) and immobilization of chromium on mineral surfaces. During this study, lead sorption on a kaolin surface was found to be a rapid and a pH dependant process in which lead sorption significantly increased with the amount of phosphate on the clay surface. This study verifies that methylmercury cation remains intact when it binds to humic acids, forming a monodentate complex with some sub-population of humic thiol ligands .

  2. EVALUATION OF GEOCHEMICAL QUALITY CONTROL IN DETERMINATION OF Mn IN SOILS USING A SEQUENTIAL CHEMICAL EXTRACTION

    Institute of Scientific and Technical Information of China (English)

    DONGDe-ming; FANGChun-sheng; 等

    2002-01-01

    Sequential chemical extraction procedure has been widely used to partition particulate trace metals into vari-ous fractions and to describe the distribution and the statue of trace metals in geo-environment.One sequential chemical extraction procedure was employed here to partition various fractions of Mn in soils.The experiment was designed with quality controlling concept in order to show sampling and analytical error.Experimental results obtained on duplicate analy-sis of all soil samples demonstrated that the precision was less than 10%(at 95% confidence level).The accuracy was estimated by comparing the accepted total concentration of Mn in standard reference materials (SRMs) with the measured sum of the individual fractions.The recovery of Mn from SRM1 and SRM2 was 94.1% and 98.4%,respectively.The detection limit,accuracy and precision of the sequential chemical extraction procedure were discussed in detailed.All the results suggest that the trueness of the analytical method is satisfactory.

  3. Geochemical signature and phytoremediation of urban soil: a case in Barcelona city

    Science.gov (United States)

    Rodríguez-Bocanegra, Javier; Roca, Núria; Febrero, Anna; Bort, Jordi

    2016-04-01

    The cleanup of contaminated places with heavy metals is necessary, but environmental remediation strategies are often expensive and energy consuming. Thus, it is important to develop low-cost and environmentally friendly strategies. Phytoremediation-based technologies could provide a long-lasting solution. The study area is located in Sants, a neighbourhood in Barcelona city (Catalonia, Spain). This place was an industrial area in the last century, which was occupied by a metal smelting industry. Nowadays, the neighbours want to cultivate vegetables in this location, but the history of this area suggests that the soil is polluted by elevated concentrations of heavy metals. The aim of this work was to determine heavy metal concentration in: a) soil, to know the degree of the soil pollution; b) roots and leaves of two plant species, Brassica juncea as an accumulator plant and Solanum lycopersicum as a crop plant, to know the capacity of each species to accumulate metals, and c) drainage water, to evaluate the heavy metal mobility. The main pollutants are Cu, Pb and Zn with topsoil total concentrations about 1355, 2230 and 6239 mg•kg-1, respectively. The established background upper limits in this area in mg•kg-1 were: Cu 145, Pb 91 and Zn 326. The same soil elements for available fractions, extracted with DTPA, were slightly elevated (9.6, 5.8 and 6.7 % of total concentration). The environmental pollution implies great extractability, suggesting the plants in these soils have facility with potentially toxic elements absorption. Instead, the concentrations in subsoil are lower than in topsoil. The concentrations of Cu, Pb and Zn in the plants' leaves are greater in B. juncea 170 ± 52.7, 137 ± 46.3 and 2365 ± 860.4 mg•kg-1, than in S. lycopersicum 102.5 ± 7.1, 22.5 ± 1.3 and 1002 ± 85.2 mg•kg-1 respectively. Furthermore, they are also greater in roots than in leaves. All of them are lower than the threshold to be considered like a hyperaccumulator species

  4. Effect of Selected Organic Acids on Cadmium Sorption by Variable-and Permanent-Charge Soils

    Institute of Scientific and Technical Information of China (English)

    HU Hong-Qing; LIU Hua-Liang; HE Ji-Zheng; HUANG Qiao-Yun

    2007-01-01

    Batch equilibrium experiments were conducted to investigate cadmium (Cd) sorption by two permanent-charge soils, a yellow-cinnamon soil and a yellow-brown soil, and two variable-charge soils, a red soil and a latosol, with addition of selected organic acids (acetate, tartrate, and citrate). Results showed that with an increase in acetate concentrations from 0 to 3.0 mmol L-1, Cd sorption percentage by the yellow-cinnamon soil, the yellow-brown soil, and the latosol decreased. The sorption percentage of Cd by the yellow-cinnamon soil and generally the yellow-brown soil (permanent-charge soils)decreased with an increase in tartrate concentration, but increased at low tartrate concentrations for the red soil and the latosol. Curves of percentage of Cd sorption for citrate were similar to those for tartrate. For the variable-charge soils with tartrate and citrate, there were obvious peaks in Cd sorption percentage. These peaks, where organic acids had maximum influence, changed with soil type, and were at a higher organic acid concentration for the variable-charge soils than for the permanent charge soils. Addition of cadmium after tartrate adsorption resulted in higher sorption increase for the variable-charge soils than permanent-charge soils. When tartrate and Cd solution were added together, sorption of Cd decreased with tartrate concentration for the yellow-brown soil, but increased at low tartrate concentrations and then decreased with tartrate concentration for the red soil and the latosol.

  5. Effect of Zn Adsorption on Charge of Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    SUNHAN-YUAN

    1993-01-01

    The variation in appa rent carge of two typical variable charge soils resulting from Zn adsorption were studied by KCl saturation and NH4NO3 replacement methods.Results showed that zinc were adsorbed specifically to those sites with negative charge.As in different pH ranges,the percantages of specific and electrostatic adsorptions of zine and the mechanisms of specific adsorption were different,the effects of Zn adsorption on apparent charge were varied and could be characterized as:when 1 mmol Zn2+ was adsorbed,a change about 1 mmol in the apparent charge was observed in the low pH range(1),1.4 to 1.5mmol in the moderate pH range(II) and 0.55 to 0.6mmol in the high pH range (III).These experimental data,in terms of soil charge,proved once more author's conclusion in the preceding paper(Sun,1993) that in accordance with the behaviors of Zn adsorption by the variable charge soils in relation to pH,three pH ranges with different adsorption mechanisms were delineated;that is,in Range I,specific adsorption was the predominant mechanism,in Ranges II and III,specific and electrostatic adsorptions co-existed,but their specific adsorption mechanisms were not identical.

  6. Spatial variability of total carbon and soil organic carbon in agricultural soils in Baranja region, Croatia

    Science.gov (United States)

    Bogunović, Igor; Trevisani, Sebastiano; Pereira, Paulo; Šeput, Miranda

    2017-04-01

    Climate change is expected to have an important influence on the crop production in agricultural regions. Soil carbon represents an important soil property that contributes to mitigate the negative influence of climate change on intensive cropped areas. Based on 5063 soil samples sampled from soil top layer (0-30 cm) we studied the spatial distribution of total carbon (TC) and soil organic carbon (SOC) content in various soil types (Anthrosols, Cambisols, Chernozems, Fluvisols, Gleysols, Luvisols) in Baranja region, Croatia. TC concentrations ranged from 2.10 to 66.15 mg/kg (with a mean of 16.31 mg/kg). SOC concentrations ranged from 1.86 to 58.00 mg/kg (with a mean of 13.35 mg/kg). TC and SOC showed moderate heterogeneity with coefficient of variation (CV) of 51.3% and 33.8%, respectively. Average concentrations of soil TC vary in function of soil types in the following decreasing order: Anthrosols (20.9 mg/kg) > Gleysols (19.3 mg/kg) > Fluvisols (15.6 mg/kg) > Chernozems (14.2 mg/kg) > Luvisols (12.6 mg/kg) > Cambisols (11.1 mg/kg), while SOC concentrations follow next order: Gleysols (15.4 mg/kg) > Fluvisols (13.2 mg/kg) = Anthrosols (13.2 mg/kg) > Chernozems (12.6 mg/kg) > Luvisols (11.4 mg/kg) > Cambisols (10.5 mg/kg). Performed geostatistical analysis of TC and SOC; both the experimental variograms as well as the interpolated maps reveal quite different spatial patterns of the two studied soil properties. The analysis of the spatial variability and of the spatial patterns of the produced maps show that SOC is likely influenced by antrophic processes. Spatial variability of SOC indicates soil health deterioration on an important significant portion of the studied area; this suggests the need for future adoption of environmentally friendly soil management in the Baranja region. Regional maps of TC and SOC provide quantitative information for regional planning and environmental monitoring and protection purposes.

  7. Accumulation, sources and health risks of trace metals in elevated geochemical background soils used for greenhouse vegetable production in southwestern China.

    Science.gov (United States)

    Zhang, Haidong; Huang, Biao; Dong, Linlin; Hu, Wenyou; Akhtar, Mohammad Saleem; Qu, Mingkai

    2017-03-01

    Greenhouse vegetable cultivation with substantive manure and fertilizer input on soils with an elevated geochemical background can accumulate trace metals in soils and plants leading to human health risks. Studies on trace metal accumulation over a land use shift duration in an elevated geochemical background scenario are lacking. Accumulation characteristics of seven trace metals in greenhouse soil and edible plants were evaluated along with an assessment of the health risk to the consumers. A total of 118 greenhouse surface soils (0-20cm) and 30 vegetables were collected from Kunming City, Yunnan Province, southwestern China, and analyzed for total Cd, Pb, Cu, Zn, As, Hg, and Cr content by ICP-MS and AFS. The trace metals were ordered Cu>Cd>Hg>Zn>Pb>As>Cr in greenhouse soils accumulation level, and the geo-accumulation index suggested the soil more severely polluted with Cd, Cu, Hg and Zn. The greenhouse and open-field soils had significant difference in Cd, Cr and Zn. The duration of shift from paddy to greenhouse land-use significantly influenced trace metal accumulation with a dramatic change during five to ten year greenhouse land-use, and continuous increase of Cd and Hg. A spatial pattern from north to south for Cd and Hg and a zonal pattern for Cu and Zn were found. An anthropogenic source primarily caused trace metal accumulation, where the principal component analysis/multiple linear regression indicated a contribution 61.2%. While the assessment showed no potential risk for children and adults, the hazard health risks index was greater than one for adolescents. The extended duration of land use as greenhouses caused the trace metal accumulation, rotation in land use should be promoted to reduce the health risks. Copyright © 2016. Published by Elsevier Inc.

  8. Geochemical association of Pu and Am in selected host-phases of contaminated soils from the UK and their susceptibility to chemical and microbiological leaching.

    Science.gov (United States)

    Kimber, Richard L; Corkhill, Claire L; Amos, Sean; Livens, Francis R; Lloyd, Jonathan R

    2015-04-01

    Understanding the biogeochemical behaviour and potential mobility of actinides in soils and groundwater is vital for developing remediation and management strategies for radionuclide-contaminated land. Pu is known to have a high Kd in soils and sediments, however remobilization of low concentrations of Pu remains a concern. Here, some of the physicochemical properties of Pu and the co-contaminant, Am, are investigated in contaminated soils from Aldermaston, Berkshire, UK, and the Esk Estuary, Cumbria, UK, to determine their potential mobility. Sequential extraction techniques were used to examine the host-phases of the actinides in these soils and their susceptibility to microbiological leaching was investigated using acidophilic sulphur-oxidising bacteria. Sequential extractions found the majority of (239,240)Pu associated with the highly refractory residual phase in both the Aldermaston (63.8-85.5 %) and Esk Estuary (91.9-94.5%) soils. The (241)Am was distributed across multiple phases including the reducible oxide (26.1-40.0%), organic (45.6-63.6%) and residual fractions (1.9-11.1%). Plutonium proved largely resistant to leaching from microbially-produced sulphuric acid, with a maximum 0.18% leached into solution, although up to 12.5% of the (241)Am was leached under the same conditions. If Pu was present as distinct oxide particles in the soil, then (241)Am, a decay product of Pu, would be expected to be physically retained in the particle. The differences in geochemical association and bioleachability of the two actinides suggest that this is not the case and hence, that significant Pu is not present as distinct particles. These data suggest the majority of Pu in the contaminated soils studied is highly recalcitrant to geochemical changes and is likely to remain immobile over significant time periods, even when challenged with aggressive "bioleaching" bacteria.

  9. The Toxicological Geochemistry of Dusts, Soils, and Other Earth Materials: Insights From In Vitro Physiologically-based Geochemical Leach Tests

    Science.gov (United States)

    Plumlee, G. S.; Ziegler, T. L.; Lamothe, P.; Meeker, G. P.; Sutley, S.

    2003-12-01

    Exposure to mineral dusts, soils, and other earth materials results in chemical reactions between the materials and different body fluids that include, depending upon the exposure route, lung fluids, gastrointestinal fluids, and perspiration. In vitro physiologically-based geochemical leach tests provide useful insights into these chemical reactions and their potential toxicological implications. We have conducted such leach tests on a variety of earth materials, including asbestos, volcanic ash, dusts from dry lake beds, mine wastes, wastes left from the roasting of mercury ores, mineral processing wastes, coal dusts and coal fly ash, various soils, and complex dusts generated by the World Trade Center collapse. Size-fractionated samples of earth materials that have been well-characterized mineralogically and chemically are reacted at body temperature (37 C) for periods from 2 hours up to multiple days with various proportions of simulated lung, gastric, intestinal, and/or plasma-based fluids. Results indicate that different earth materials may have quite different solubility and dissolution behavior in vivo, depending upon a) the mineralogic makeup of the material, and b) the exposure route. For example, biodurable minerals such as asbestos and volcanic ash particles, whose health effects result because they dissolve very slowly in vivo, bleed off low levels of trace metals into the simulated lung fluids; these include metals such as Fe and Cr that are suspected by health scientists of contributing to the generation of reactive oxygen species and resulting DNA damage in vivo. In contrast, dry lake bed dusts and concrete-rich dusts are highly alkaline and bioreactive, and cause substantial pH increases and other chemical changes in the simulated body fluids. Many of the earth materials tested contain a variety of metals that can be quite soluble (bioaccessible), depending upon the material and the simulated body fluid composition. For example, due to their acidic

  10. Principal Component and Time Series Analysis of a 500-year Stalagmite Geochemical Record from Yucatán, Mexico Reveals Climate Variability, Land-use changes, and Volcanic Ashfall

    Science.gov (United States)

    Kuklewicz, K. B.; Frappier, A. E.

    2015-12-01

    Principal Component Analysis of stalagmite multivariate geochemical records can provide insight into climate variability as well as the frequency of high-magnitude events (i.e. volcanic eruptions) and even land use changes above cave systems. For most environmental proxies, large trace element data sets can pose difficulties for analysis and interpretation due to natural processes acting across wide ranges of time scales and magnitudes with overlapping influences on individual chemical species. To reduce the complexity of geochemical data, we applied Principal Component Analysis (PCA) and Evolutionary Spectral Analysis to a large high-resolution Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS) stalagmite trace element data set from northern Yucatán, Mexico (CH-1), from about 1500-2007 CE. In our study, PCA identified five significant principal components (PCs) in this CH-1 record, which explain >83% of the data set's variability. Our analysis reveals that PC1 responds to overall trace element loading, including both short-lived trace element influxes associated with volcanic eruptions, and sustained land use changes associated with the Spanish settlement and Henequen (succulent plant) production. PC2 reflects prior calcite precipitation associated with regional dry climate anomalies by increasing Sr and Mg substitution in calcite. High loadings for B and Na indicate that PC3 is sensitive to wet climate anomalies. PCs 4 and 5 reflect related but lagged trace element transport mechanisms. Evolutionary spectral analysis results for the PCs reveal the changing influence of solar 11 and 22-year cycles and the 3-7 year El Niño/Southern Oscillation (ENSO) system over the last 500 years. This study adds to growing evidence that speleothems can record multivariate trace element fingerprints of volcanic eruptions, soil erosion, and different styles of climate variability, which can be useful for model verification and sensitivity testing studies.

  11. Geochemical and isotopic evolution of soil solutions over the last 25 years in a forested granitic catchment (the experimental Strengbach watershed case, France).

    Science.gov (United States)

    Pierret, M.-C.; Prunier, J.; Stille, P.; Chabaux, F.

    2009-04-01

    The upper most meter of the soil represents the most sensitive and the most reactive zone of surface facing anthropological or global changes. Indeed, the processes and the exchanges which take place in this zone, in particular between soils, plants, waters, and atmosphere can be strongly modified by the disturbances of the environment. It is the reason why it is essential to study the various compartments of the soil and in particular theirs time evolutions. The soil solutions represent an essential vector of migration of elements within the soil profile and until the deeper levels feeding springs and rivers. Besides, they also reflect the atmospheric contributions and the processes such as the chemical weathering, the root uptake or the biological recycling. Our study presents the variations over more than 20 years of the elemental and isotopic compositions of soil solutions along two profiles in a granitic environment undergoing acid rains in the 60s-80s, as well as an extensive forestry development. Two experimental plots were monitored, which are part of the Environmental Hydro-Geochemical Observatory (OHGE; http://ohge.u-strasbg.fr) located on the small granitic watershed of the Strengbach creek, in the Vosges Mountain (North-East of France). Meteorological, hydrological and geochemical data are recorded since 1986. The soil solutions and the soils were analysed (elemental and isotopic compositions) at different depths, under beeches and spruces, and in both podzolic and acid brown soils. The data covering more than 2 decades show important evolutions with time in the geochemical composition of the soil solutions from the both plots, both with respect to the elementary data and the isotopic ratios. For instance, the annual chemical flux in soil solutions of certain nutrients such as the Ca strongly decreased in depth for more than 20 years, while they remained constant or increased for lithogenic elements as Na or Si. The rain and throughfall records show

  12. Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements.

    Science.gov (United States)

    Baize, D; Sterckeman, T

    2001-01-08

    In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than

  13. Spatial variability in the soil water content of a Mediterranean agroforestry system with high soil heterogeneity

    Science.gov (United States)

    Molina, Antonio Jaime; Llorens, Pilar; Aranda, Xavier; Savé, Robert; Biel, Carmen

    2013-04-01

    Variability of soil water content is known to increase with the size of spatial domain in which measurements are taken. At field scale, heterogeneity in soil, vegetation, topography, water input volume and management affects, among other factors, hydrologic plot behaviour under different mean soil water contents. The present work studies how the spatial variability of soil water content (SWC) is affected by soil type (texture, percentage of stones and the combination of them) in a timber-orientated plantation of cherry tree (Prunus avium) under Mediterranean climatic conditions. The experimental design is a randomized block one with 3 blocks * 4 treatments, based on two factors: irrigation (6 plots irrigated versus 6 plots not irrigated) and soil management (6 plots tillaged versus 6 plots not tillaged). SWC is continuously measured at 25, 50 and 100 cm depth with FDR sensors, located at two positions in each treatment: under tree influence and 2.5 m apart. This study presents the results of the monitoring during 2012 of the 24 sensors located at the 25 cm depth. In each of the measurement point, texture and percentage of stones were measured. Sandy-loam, sandy-clay-loam and loam textures were found together with a percentage of stones ranging from 20 to 70 %. The results indicated that the relationship between the daily mean SWC and its standard deviation, a common procedure used to study spatial variability, changed with texture, percentage of stones and the estimation of field capacity from the combination of both. Temporal stability analysis of SWC showed a clear pattern related to field capacity, with the measurement points of the sandy-loam texture and the high percentage of stones showing the maximun negative diference with the global mean. The high range in the mean relative difference observed (± 75 %), could indicate that the studied plot may be considered as a good field-laboratory to extrapolate results at higher spatial scales. Furthermore, the

  14. Environmental response to past and recent climate variability in the Trondheimsfjord region, central Norway - A multiproxy geochemical approach

    OpenAIRE

    2014-01-01

    Norwegian fjords have a great potential for providing high-resolution sedimentary records that reflect local terrestrial and marine processes and therefore, fjords offer unique opportunities for the investigation of sedimentological and geochemical climatically induced processes. However, the complexity of fjord systems in terms of bathymetry and oceanography requires a profound knowledge of the fjord environmental setting before starting to interpret past climatic signals in Holocene sedimen...

  15. ENSO and interdecadal climate variability over the last century documented by geochemical records of two coral cores from the South West Pacific

    Directory of Open Access Journals (Sweden)

    T. Ourbak

    2006-01-01

    Full Text Available The south west Pacific is affected by climatic phenomena such as ENSO (El Niño Southern Oscillation or the PDO (Pacific Decadal Oscillation. Near-monthly resolution calibrations of Sr/Ca, U/Ca and δ18Oc were made on corals taken from New Caledonia and Wallis Island. These geochemical variations could be linked to SST (sea surface temperature and SSS (sea surface salinity variations over the last two decades, itselves dependent on ENSO occurrences. On the other hand, near-half-yearly resolution over the last century smoothes seasonal and interannual climate signals, but emphasizes low frequency climate variability.

  16. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110462 Chen Furong(Anhui Institute of Geological Survey,Hefei 230001,China)Ore-Search Prospects of Gold and Tungsten Geochemical Anomalies in Ningdun Area,Anhui Province(Geophysical and Geochemical Exploration,ISSN1000-8918,CN11-1906/P,34(2),2010,p.150-153,5 illus.,2 tables,6 refs.)Key words:gold ores,tungsten ores,geochemical exploration,AnhuiGeochemical anomalies of gold and tungsten in Ningdun area are dominated by the element association of Au-As-W-Bi.These anomalies are well coincident with

  17. VARIABILITY OF ARABLE AND FOREST SOILS PROPERTIES ON ERODED SLOPES

    Directory of Open Access Journals (Sweden)

    Paweł Wiśniewski

    2014-10-01

    Full Text Available The basic method of reducing soil and land erosion is a change of land use, for example, from arable to forest. Particularly effective as a protective role – according to the Polish law – soil-protecting forests. The thesis presents differences in the deformation of the basic soil properties on moraine slopes, depending on land use. There has been presented the function and the efficiency of the soil-protecting forests in erosion control. The soil cross section transects and soil analysis displayed that soil-protecting forests are making an essential soil cover protection from degradation, inter alia, limiting the decrease of humus content, reduction of upper soil horizons and soil pedons layer. On the afforested slopes it was stated some clear changes of grain size and chemical properties of soils in relation to adjacent slopes agriculturally used.

  18. Study on the spatiotemporal variability and affecting factors in soil moisture at a humid area

    Science.gov (United States)

    Liu, H.; Yu, Z.

    2008-12-01

    The spatiotemporal variability of soil moisture and its affecting factors in a humid area were examined based on the field measuring date in the Tai lake drainage basin, China. 24 sensors near the soil surface and 12 sensors in 2 profiles (6 in each) were set up for collecting hourly soil moisture data with the Frequency Domain Reflectometry (FDR) sensors in 2006. Coefficient of variation (CV) and semi-variogram were calculated to evaluate the temporal variability in different locations and the spatial variability in different periods. The surface soil moisture appears middle or weak variability, and most of the CV values are in the range of 0.13-0.26. Soil characteristics, topography, vegetation, meteorological factors and human activities influenced the soil moisture spatiotemporal variability significantly. The factors appear having different affecting abilities on the spatiotemporal variability, and the domain factors are different in four seasons. Soil characteristics mainly influence the temporal variability in the scale of hill slope. Coarser texture on the upper part of the slope results in a larger variability. Topography and micro-topography affects the spatial variability in all 3 dimensions. The variability is larger at upper locations and chine of the slope. The effect of vegetation on the soil moisture variability is stronger in spring, summer, and autumn than in winter, according to the different growth activities and water demand. The trees on the slope influence the CV values along the slope. Meteorological factors are the forcing factors of the soil water variation. Higher rainfall and evaporation variations produce higher variability in soil moisture while the rainfall has more influence in the summer and the evaporation has more in the fall. The results provide better understanding of soil moisture variation and base for further study on how the soil moisture variation could affect the rainfall runoff partitioning.

  19. Geochemical background/baseline values in top soils of Campania region: assessment of the toxic elements threat to ecosystem and human health

    Science.gov (United States)

    de Vivo, B.; Lima, A.; Albanese, S.; Bove, M.; Cicchella, D.; Civitillo, D.; Cosenza, A.; Grezzi, G.

    2009-04-01

    In the late years an intense geochemical prospecting activity on the whole territory of Campania region (Southern Italy) has been carried aiming at the definition of the geochemical backgrounds/baselines at both regional and local scale. At the end of 2003 the first edition of an atlas containing 200 maps showing the distribution patterns of 40 chemical elements on the whole regional territory was published (De Vivo et al., 2003, 2006a; Albanese et al., 2007a). The atlas provided a base knowledge of environmental status of the region and allowed to individuate some critical areas to be further investigated by topsoils sampling follow up activity; the topsoils are considered as the best media in order to examine closely the sources and the distribution patterns of harmful elements at a local scale. The topsoils sampling was mainly focused on anthropized areas (at urban and metropolitan scale), industrial settlments, brownfields and intensely cultivated zones, aimed at: • showing the distribution of concentration values and to determine baseline values (or backgrounds, depending on local conditions) of each analyzed element (38) in the top soils; • assessing harmful elements pollution levels and their geographic distribution; • providing reliable analytical data for assessment of toxic element pollution threat to ecosystem and human health; • creating a sound basis for policy makers and legislators who need to address the public concerns regarding environmental pollution. Five atlases (De Vivo et al., 2006b; Albanese et al., 2007b; Lima et al., 2007; Fedele et al., 2007 Cicchella et al., 2009) were produced reporting soil geochemical maps compiled using 1620 samples collected both in the metropolitan and provincial area of Napoli and in the cities of Avellino, Benevento, Caserta and Salerno. Further studies were also carried out taking into account Pb isotopes (Cicchella et al., 2008a), PGE's (Cicchella et al., 2003; 2008b) and bioavailability of harmful

  20. Key indicator tools for shallow slope failure assessment using soil chemical property signatures and soil colour variables.

    Science.gov (United States)

    Othman, Rashidi; Hasni, Shah Irani; Baharuddin, Zainul Mukrim; Hashim, Khairusy Syakirin Has-Yun; Mahamod, Lukman Hakim

    2017-07-18

    Slope failure has become a major concern in Malaysia due to the rapid development and urbanisation in the country. It poses severe threats to any highway construction industry, residential areas, natural resources and tourism activities. The extent of damages that resulted from this catastrophe can be lessened if a long-term early warning system to predict landslide prone areas is implemented. Thus, this study aims to characterise the relationship between Oxisols properties and soil colour variables to be manipulated as key indicators to forecast shallow slope failure. The concentration of each soil property in slope soil was evaluated from two different localities that consist of 120 soil samples from stable and unstable slopes located along the North-South Highway (PLUS) and East-West Highway (LPT). Analysis of variance established highly significant difference (P < 0.0001) between the locations, the total organic carbon (TOC), soil pH, cation exchange capacity (CEC), soil texture, soil chromaticity and all combinations of interactions. The overall CIELAB analysis leads to the conclusion that the CIELAB variables lightness L*, c* (Chroma) and h* (Hue) provide the most information about soil colour and other related soil properties. With regard to the relationship between colour variables and soil properties, the analysis detected that soil texture, organic carbon, iron oxide and aluminium concentration were the key factors that strongly correlate with soil colour variables at the studied area. Indicators that could be used to predict shallow slope failure were high value of L*(62), low values of c* (20) and h* (66), low concentration of iron (53 mg kg(-1)) and aluminium oxide (37 mg kg(-1)), low soil TOC (0.5%), low CEC (3.6 cmol/kg), slightly acidic soil pH (4.9), high amount of sand fraction (68%) and low amount of clay fraction (20%).

  1. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    OpenAIRE

    José Paulo Molin; Gustavo Di Chiacchio Faulin

    2013-01-01

    Soil electrical conductivity (ECa) is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semiv...

  2. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20081182 Chen Guoguang(China University of Geosciences,Wuhan 430074,China);Zhou Guohua Eco-Geochemical Assessment Based On Geosciences(Resources Survey & Environment,ISSN1671-4814,CN32-1640/N,28(2),2007,p.79-84,2 tables,6 refs.)Key words:regional geochemical

  3. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131784 An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China);Lei Yingping Geochemical Characteristics and Metallogenic Prospecting Areas in Yunkai Area,Guangxi(Geophysical and Geochemical Exploration,ISSN1000-8918,CN11-1906/P,36

  4. The effect of land use on spatial variability of soil water repelency

    Science.gov (United States)

    Hrabovský, Andrej; Dlapa, Pavel; Chrenková, Katarína; Šimkovic, Ivan

    2016-04-01

    Soil water repellency was identified as a fundamental phenomenon during a soil survey dedicated to soil hydrological properties and processes in watersheds of the Little Carpathians Mts. (SW Slovakia). The investigated area represents the viticulture region with various soil management practices. Thus, soils of the region are influenced by deep ploughing during vineyard establishment, by cultivation of vineyards, by reforestation of abandoned vineyards as well as by long-term forestry practices. The soils developed from granitic rocks are naturally susceptible to water repellency development. The obtained results showed marked variability in physical and chemical soil properties. In particular, the soil pH values, the clay and organic carbon contents differed significantly depending on soil management. Due to these differences, the soil water repellency increased from wettable to extremely water repellent approximately in order: deeply ploughed vineyard soils water repellency on infiltration process was observed by means of field experiments.

  5. Exploiting biogeochemical and spectroscopic techniques to assess the geochemical distribution and release dynamics of chromium and lead in a contaminated floodplain soil.

    Science.gov (United States)

    Rinklebe, Jörg; Shaheen, Sabry M; Schröter, Felix; Rennert, Thilo

    2016-05-01

    Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) combined with a seven steps sequential extraction technique were used to assess the geochemical distribution of chromium (Cr) and lead (Pb) in a contaminated floodplain soil. Total contents of Cr and Pb were 490.3 and 402.1 mg kg(-1), respectively. The residual fraction was 59.5 and 56.3% of total Cr and Pb. The crystalline iron (Fe) oxide was the dominant non-residual fraction of Cr (35.9% of total Cr). Considerable amounts of Pb were found in the organic fraction (35.4%). Using (13)C nuclear magnetic resonance spectroscopy, the soil organic matter was identified as 48.9% aromatic carbon, which indicated that a certain portion of Pb and Cr might be associated with aromatic compounds. The SEM-EDX images demonstrate a concomitant occurrence of Pb, manganese (Mn), Fe, and aluminum (Al) as well as a coexistence of Cr and Fe. The release dynamics of dissolved Cr and Pb as affected by redox potential (EH), pH, Fe, Mn, dissolved organic carbon, and sulfate was quantified using an automated biogeochemical microcosm apparatus. Soil pH decreased under oxic conditions. The release of Cr, Pb, Fe, and Mn increased under acidic oxic (pH = 3.7, EH = 521 mV) conditions due to the associated decrease of pH (7.1-3.7). The mobilization of Cr and Pb was affected by the Fe and Mn. In conclusion, our multi-technique approach identified the geochemical distribution of Cr and Pb and verified major factors that explain mobilization of Cr and Pb in floodplain soils.

  6. Moisture variability resulting from water repellency in Dutch soils

    OpenAIRE

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency can lead to the development of unstable wetting and preferential flow paths. Preferential flow has wide-ranging significance for rapi...

  7. Spatial Variability and Geostatistical Prediction of Some Soil Hydraulic Coefficients of a Calcareous Soil

    Directory of Open Access Journals (Sweden)

    Ali Akbar Moosavi

    2017-02-01

    Full Text Available Introduction: Saturated hydraulic conductivity and the other hydraulic properties of soils are essential vital soil attributes that play role in the modeling of hydrological phenomena, designing irrigation-drainage systems, transportation of salts and chemical and biological pollutants within the soil. Measurement of these hydraulic properties needs some special instruments, expert technician, and are time consuming and expensive and due to their high temporal and spatial variability, a large number of measurements are needed. Nowadays, prediction of these attributes using the readily available soil data using pedotransfer functions or using the limited measurement with applying the geostatistical approaches has been receiving high attention. The study aimed to determine the spatial variability and prediction of saturated (Ks and near saturated (Kfs hydraulic conductivity, the power of Gardner equation (α, sorptivity (S, hydraulic diffusivity (D and matric flux potential (Фm of a calcareous soil. Material and Methods: The study was carried out on the soil series of Daneshkadeh located in the Bajgah Agricultural Experimental Station of Agricultural College, Shiraz University, Shiraz, Iran (1852 m above the mean sea level. This soil series with about 745 ha is a deep yellowish brow calcareous soil with textural classes of loam to clay. In the studied soil series 50 sampling locations with the sampling distances of 16, 8 , and 4 m were selected on the relatively regular sampling design. The saturated hydraulic conductivity (Ks, near saturated hydraulic conductivity (Kfs, the power of Gardner equation (α, sorptivity (S, hydraulic diffusivity (D and matric flux potential (Фm of the aforementioned sampling locations was determined using the Single Ring and Droplet methods. After, initial statistical processing, including a normality test of data, trend and stationary analysis of data, the semivariograms of each studied hydraulic attributes were

  8. An ice-ocean model study to explore climate change mechanisms in comparison with interannual-to-decadal variability of geochemical tracers

    Institute of Scientific and Technical Information of China (English)

    Motoyoshi Ikeda

    2014-01-01

    One way to identify the mechanisms that are crucial to Arctic climate change is to use existing data that exhibit interannual-to-decadal variability in the sea ice and ocean interior due to atmospheric forcing. Since around 1960s, valuable geochemical data of the ocean interior, together with atmospheric and sea ice data, have been analyzed and examined in a coupled ice–ocean model with an idealized configuration of the Arctic Basin. This is fundamentally driven by negative salt flux, in addition to atmospheric circulation and cooling. This strategy has a clear advantage over more sophisticated models with higher resolution that require extensive data collections for veriifcation. Around 1990, the dominant atmospheric mode shifted from the Northern Annular Mode (NAM) to the Arctic Dipole Mode (ADM). The variability of sea ice cover was explained by these two modes sequentially and reproduced in the model. In particular, the geochemical ifelds indicated a movement of the Transpolar Drift Stream due to the NAM and an oscillation of the Paciifc water between the Atlantic and Paciifc sides due to the ADM. Both these features were reproduced reasonably well by the oceanic tracers in the model, including the time lags of about one third of the oscillation periods. Thus, this strategy can suggest methods and locations for monitoring oceanographic responses to Arctic climate change.

  9. Temporal Variability in Soil CO2 Emission in an Orchard Forest Ecosystem

    Institute of Scientific and Technical Information of China (English)

    LI Yue-Lin; D.OTIENO; K.OWEN; ZHANG Yun; J.TENHUNEN; RAO Xing-Quan; LIN Yong-Biao

    2008-01-01

    Temporal variability in soil CO2 emission from an orchard was measured using a dynamic open-chamber system for measuring soil CO2 efflux in Heshan Guangdong Province,in the lower subtropical area of China.Intensive measurements were conducted for a period of 12 months.Soil COs emissions were also modeled by multiple regression analysis from dally air temperature,dry-bulb saturated vapor pressure,relative humidity,atmospheric pressure,soil moisture,and soil temperature.Data was analyzed based on soil moisture levels and air temperature with annual data being grouped into either hot-humid season or relatively cool season based on the precipitation patterns.This was essential in order to acquire simplified exponential models for parameter estimation.Minimum and maximum daily mean soil CO2 efflux rates were observed in November and July,with respective rates of 1.98 ± 0.66 and 11.04 ± 0.96/μmol m-2 s-1 being recorded.Annual average soil CO2 emission (FCO2) was 5.92/μmol m-2 s-1.Including all the weather variables into the model helped to explain 73.9% of temporal variability in soil CO2 emission during the measurement period.Soil CO2 efflux increased with increasing soil temperature and soil moisture.Preliminary results showed that Q10,which is defined as the difference in respiration rates over a 10 ℃ interval,was partly explained by fine root biomass.Soil temperature and soil moisture were the dominant factors controlling soil CO2 efflux and were regarded as the driving variables for CO2 production in the soil.Including these two variables in regression models could provide a useful tool for predicting the variation of CO2 emission in the commercial forest soils of South China.

  10. Effect of Soil Sampling Density on Detected Spatial Variability of Soil Organic Carbon in a Red Soil Region of China

    Institute of Scientific and Technical Information of China (English)

    YU Dong-Sheng; ZHANG Zhong-Qi; YANG Hao; SHI Xue-Zheng; TAN Man-Zhi; SUN Wei-Xia; WANG Hong-Jie

    2011-01-01

    Spatial variability of soil organic carbon (SOC) of different land use patterns and soil types was examined in a county-wide red soil region of South China, using six sampling densities, 14, 34, 68, 130, 255, and 525 samples designed by the method of grid sampling in 6 different grid sizes, labeled as D14, D34, D68, D130, D255, and D525, respectively. The results showed that the coefficients of variation (CVs) of SOC decreased gradually from 62.8% to 47.4% with the increase in soil sampling densities. The SOC CVs in the paddy field change slightly from 30.8% to 28.7%, while those of the dry farmland and forest land decreased remarkably from 58.1%to 48.7% and from 99.3% to 64.4%, respectively. The SOC CVs of the paddy soil change slightly, while those of red soil decreased remarkably from 82.8% to 63.9%. About 604, 500, and 353 (P < 0.05) samples would be needed a number of years later if the SOC change was supposedly 1.52 g kg-2, based on the CVs of SOC acquired from the present sampling densities of D14, D68, and D525,respectively. Moreover, based on the same SOC change and the present time CVs at D255, the ratio of samples needed for paddy field, dry farmland, and forest land should be 1:0.81:3.33, while the actual corresponding ratio in an equal interval grid sampling was 1:0.74:0.46. These indicated that the sampling density had important effect on the detection of SOC variability in the county-wide region, the equal interval grid sampling was not efficient enough, and the respective CV of each land use or soil type should be fully considered when determining the sampling number in the future.

  11. Climate, soil or both? Which variables are better predictors of the distributions of Australian shrub species?

    Directory of Open Access Journals (Sweden)

    Yasmin Hageer

    2017-06-01

    Full Text Available Background Shrubs play a key role in biogeochemical cycles, prevent soil and water erosion, provide forage for livestock, and are a source of food, wood and non-wood products. However, despite their ecological and societal importance, the influence of different environmental variables on shrub distributions remains unclear. We evaluated the influence of climate and soil characteristics, and whether including soil variables improved the performance of a species distribution model (SDM, Maxent. Methods This study assessed variation in predictions of environmental suitability for 29 Australian shrub species (representing dominant members of six shrubland classes due to the use of alternative sets of predictor variables. Models were calibrated with (1 climate variables only, (2 climate and soil variables, and (3 soil variables only. Results The predictive power of SDMs differed substantially across species, but generally models calibrated with both climate and soil data performed better than those calibrated only with climate variables. Models calibrated solely with soil variables were the least accurate. We found regional differences in potential shrub species richness across Australia due to the use of different sets of variables. Conclusions Our study provides evidence that predicted patterns of species richness may be sensitive to the choice of predictor set when multiple, plausible alternatives exist, and demonstrates the importance of considering soil properties when modeling availability of habitat for plants.

  12. Climate, soil or both? Which variables are better predictors of the distributions of Australian shrub species?

    Science.gov (United States)

    Hageer, Yasmin; Esperón-Rodríguez, Manuel; Baumgartner, John B; Beaumont, Linda J

    2017-01-01

    Shrubs play a key role in biogeochemical cycles, prevent soil and water erosion, provide forage for livestock, and are a source of food, wood and non-wood products. However, despite their ecological and societal importance, the influence of different environmental variables on shrub distributions remains unclear. We evaluated the influence of climate and soil characteristics, and whether including soil variables improved the performance of a species distribution model (SDM), Maxent. This study assessed variation in predictions of environmental suitability for 29 Australian shrub species (representing dominant members of six shrubland classes) due to the use of alternative sets of predictor variables. Models were calibrated with (1) climate variables only, (2) climate and soil variables, and (3) soil variables only. The predictive power of SDMs differed substantially across species, but generally models calibrated with both climate and soil data performed better than those calibrated only with climate variables. Models calibrated solely with soil variables were the least accurate. We found regional differences in potential shrub species richness across Australia due to the use of different sets of variables. Our study provides evidence that predicted patterns of species richness may be sensitive to the choice of predictor set when multiple, plausible alternatives exist, and demonstrates the importance of considering soil properties when modeling availability of habitat for plants.

  13. Effects of uncertainty in major input variables on simulated functional soil behaviour

    NARCIS (Netherlands)

    Finke, P.A.; Wösten, J.H.M.; Jansen, M.J.W.

    1997-01-01

    Uncertainties in major input variables in water and solute models were quantified and their effects on simulated functional aspects of soil behaviour were studied using basic soil properties from an important soil map unit in the Netherlands. Two sources of uncertainty were studied: spatial

  14. Effects of uncertainty in major input variables on simulated functional soil behaviour

    NARCIS (Netherlands)

    Finke, P.A.; Wösten, J.H.M.; Jansen, M.J.W.

    1996-01-01

    Uncertainties in major input variables in water and solute models were quantified and their effects on simulated functional aspects of soil behaviour were studied using basic soil properties from an important soil map unit in the Netherlands. Two sources of uncertainty were studied: spatial

  15. Soil Physical and Environmental Conditions Controlling Patterned-Ground Variability at a Continuous Permafrost Site, Svalbard

    DEFF Research Database (Denmark)

    Watanabe, Tatsuya; Matsuoka, Norikazu; Christiansen, Hanne Hvidtfeldt

    2017-01-01

    This study examines soil physical and environmental conditions controlling patterned-ground variability on an alluvial fan in a continuous permafrost landscape, at Adventdalen, Svalbard. On-site monitoring of ground temperature, soil moisture and snow depth, laboratory analyses of soil physical...

  16. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091835 Cheng Hangxin(School of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China);Zhuang Guangmin The Cd Geochemical Province in the Source Area of the Yangtze River and the Output Fluxes of Cd for Its Major Water Systems(Earth Science Frontiers,ISSN1005-2321,CN11-3370/P,15(5),2008,p.203-211,5 illus.,5 tables,25 refs.,with English abstract)Key words:cadmium,geochemical province,Qinghai-Tibetan Plateau20091836 Cheng Hangxin(School of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China);Yang Zhongfang A New Round of Global Geochemical

  17. Temporal variability in California grasslands: soil type and species functional traits mediate response to precipitation.

    Science.gov (United States)

    Fernandez-Going, B M; Anacker, B L; Harrison, S P

    2012-09-01

    Plant communities on infertile soils may be relatively resistant to climatic variation if species in these communities have "stress-tolerant" functional traits that limit their ability to respond to climate. Alternatively, such communities may be more sensitive to climatic variation if their relatively sparse vegetative cover exposes species to more extreme changes in factors such as temperature or wind. We compared temporal variability in species richness and composition over 10 years between grasslands on infertile serpentine and "normal" sedimentary soils. Variability in species richness and species composition tracked mean annual precipitation on both soils, but variability was lower in serpentine grasslands. Communities on serpentine had lower functional diversity and had species with more "stress-tolerant" traits than non-serpentine communities (i.e., shorter stature, lower specific leaf area, and lower leaf area). Within and between soils, variability in species richness and temporal turnover were lower in communities scoring as more stress tolerant on a multivariate index of these traits; however, community variability was unrelated to functional diversity. Within 41 species found commonly on both soils, variability in occurrence and cover were also lower on serpentine soils, even though intraspecific trait differences between soils were minimal; this suggests a direct effect of soil type on species variability in addition to the indirect, trait-mediated effect. Communities with higher biomass had higher annual variability in species occurrence and cover. Our results suggest that infertile soils reduce compositional variability indirectly by selecting for stress-tolerant traits and directly by limiting productivity. We conclude that communities on infertile soils may respond more conservatively to predicted changes in precipitation, including increased variability, than communities on soils of normal fertility.

  18. Moisture variability resulting from water repellency in Dutch soils.

    NARCIS (Netherlands)

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water in

  19. Moisture variability resulting from water repellency in Dutch soils

    NARCIS (Netherlands)

    Dekker, L.W.

    1998-01-01

    The present study suggests that many soils in the Netherlands, in natural as well as in agricultural areas, may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard

  20. The Spatial Variability of Soil Dehydrogenase Activity: A Survey in Urban Soils

    OpenAIRE

    Ridvan Kizilkaya; Tayfun Aşkin

    2007-01-01

    Information on soil microorganisms and their activity used to determine microbiological characteristics are very important for soil quality and productivity. Studies of enzyme activities provide information on the biochemical processes occurring in soil. There is growing evidence that soil biological parameters may be potential and sensitive indicators of soil ecological conditions and soil management. Soil microbiological parameters may be evaluated statistically due to application of geosta...

  1. Geochemical mapping of polluted soils and environmental risk assessment associated to mining activities: a comparison case study in El Campillo (Huelva, Spain) and the Zambales (Luzon Island,The Philippines)

    Science.gov (United States)

    Zuluaga, Maria Clara; Albanese, Stefano; de Vivo, Benedetto; Nieto, Jose Miguel; David, Carlos Primo C.; Norini, Gianluca

    2014-05-01

    The soil is one of the environmental systems which could be most affected by the dispersion of pollutant, also because of the close relationship with the atmosphere and meteoric waters. The distribution and type of contamination depends closely on the climate, precipitations, drainage, vegetation, lithology and human activities. As a matter of fact, soil contamination due to heavy metals and metalloids, such as As, Cd, Cr, Cu, Ni, Pb and Zn, represents the source of a severe potential hazard for the ecosystem equilibrium and the health of living beings. This study is carried out in two abandoned mining zones near to populated areas, which underwent similar mining history, but in very different climatic and environmental conditions. The aim of the research is to analyze the influence of precipitation amounts, soil thickness, drainage density and vegetation cover on pollutant distribution. The first zone is in El Campillo, a town at the Rio Tinto mining district and belongs to the Iberic Pyritic Belt of the southwest Iberian peninsula. This mining site is characterized by a Mediterranean climate with low precipitation (700 mm/year), low vegetation cover and poor soil development. The second case study is the Zambales Mountain Range, a mining district in the Luzon Island of the Philippines dominated by a tropical weather, forests, intense rainfalls (2350 mm/year) and good soil development. The wide spectrum of climatic variables in the case studies requires to develop a single flexible methodology for the mapping and monitoring of the environmental degradation in both semi-arid and tropical environments, allowing comparative studies. The methodological approach comprises remote sensing, Geographic Information System (GIS), spatial statistical analysis, field sampling, ICP analysis and isotopic geochemical analysis. The presentation illustrates the first stage of the project. The processing of multispectral (Aster) and hyperspectral (Hyperion) images, in comparison

  2. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20152642 Baoyinwuliji(Inner Mongolia Institute of Geological Survey,Hohhot 010020,China);Zhao Wentao Geochemical Anomaly and Metallogenic Potential of the Naomugengsumu Lithium Mineralization Area in Inner Mongolia(Geology and Resources,ISSN1671

  3. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>20122626 Li Dongfeng ( Liaoning Institute of Mineral Resources Exploration,Shenyang 110032,China ) Application of Comprehensive Geophysical-Geochemical Method in Toudao-yingzi Gold Field ( Journal of Liaoning Technical University ( Natural Sciences ), ISSN1008-0562,CN21-1379 / N,30 ( 6 ), 2011,p.849-852,1illus.,2tables,10refs. ) Key words:gold ores,geophysical exploration,geochemical exploration,Liaoning Province

  4. Geomorphometric tool associated with soil types and properties spatial variability at watersheds under tropical conditions

    Directory of Open Access Journals (Sweden)

    Sérgio Henrique Godinho Silva

    2016-08-01

    Full Text Available ABSTRACT The application of quantitative methods to digital soil and geomorphological mapping is becoming an increasing trend. One of these methods, Geomorphons, was developed to identify the ten most common landforms based on digital elevation models. This study aimed to make a quantitative assessment of the relationships between Geomorphons units, determined at three spatial resolutions and nine radii, and soil types and properties of two watersheds with different soil-landscape relationships in Brazil to help soil surveying and mapping under tropical conditions. The study was conducted at Lavrinha Creek (LCW and Marcela Creek (MCW watersheds, located in the state of Minas Gerais, Brazil. Spatial resolutions of 10, 20 and 30 m were the basis for generating Geomorphons at 9 radii of calculation for the watersheds. They were overlapped to detailed soil maps of the watersheds and a chi-square test was carried out to assess their relationship with soil types. Observation points were compared with the most highly correlated Geomorphons to also assess relationships with soil properties. Geomorphons with resolution of 30-m and radii of 20 and 50 cells, respectively for LCW and MCW, were more highly correlated with the variability of soil types, in accordance with the terrain features of these watersheds. The majority of observation points for each soil type was located in the same Geomorphon unit that was dominant when analyzing soil maps. There was less variability in soil properties between Geomorphon units, which was probably due to the highly weathered-leached stage of soils. Geomorphons can help to improve soil maps in tropical conditions when assessing soil variability due to its high correlation with tropical soil types variability.

  5. Spatial variability and its scale dependency of observed and modeled soil moisture under different climate conditions

    Directory of Open Access Journals (Sweden)

    B. Li

    2012-09-01

    Full Text Available Past studies on soil moisture spatial variability have been mainly conducted in catchment scales where soil moisture is often sampled over a short time period. Because of limited climate and weather conditions, the observed soil moisture often exhibited smaller dynamic ranges which prevented the complete revelation of soil moisture spatial variability as a function of mean soil moisture. In this study, spatial statistics (mean, spatial variability and skewness of in situ soil moisture measurements (from a continuously monitored network across the US, modeled and satellite retrieved soil moisture obtained in a warm season (198 days were examined at large extent scales (>100 km over three different climate regions. The investigation on in situ measurements revealed that their spatial moments strongly depend on climates, with distinct mean, spatial variability and skewness observed in each climate zone. In addition, an upward convex shape, which was revealed in several smaller scale studies, was observed for the relationship between spatial variability of in situ soil moisture and its spatial mean across dry, intermediate, and wet climates. These climate specific features were vaguely or partially observable in modeled and satellite retrieved soil moisture estimates, which is attributed to the fact that these two data sets do not have climate specific and seasonal sensitive mean soil moisture values, in addition to lack of dynamic ranges. From the point measurements to satellite retrievals, soil moisture spatial variability decreased in each climate region. The three data sources all followed the power law in the scale dependency of spatial variability, with coarser resolution data showing stronger scale dependency than finer ones. The main findings from this study are: (1 the statistical distribution of soil moisture depends on spatial mean soil moisture values and thus need to be derived locally within any given area; (2 the boundedness of soil

  6. Field scale spatio-temporal soil moisture variability for trafficability and crop water availability

    Science.gov (United States)

    Carranza, Coleen; van der Ploeg, Martine; Ritsema, Coen

    2016-04-01

    Spatio-temporal patterns of soil moisture have been studied mostly for inputs in land surface models for weather and climate predictions. Remote sensing techniques for estimation of soil moisture have been explored because of the good spatial coverage at different scales. Current available satellite data provide surface soil moisture as microwave systems only measure soil moisture content up to 5cm soil depth. The OWAS1S project will focus on estimation of soil moisture from freely available Sentinel-1 datasets for operational water management in agricultural areas. As part of the project, it is essential to develop spatio-temporal methods to estimate root zone soil moisture from surface soil moisture. This will be used for crop water availability and trafficability in selected agricultural fields in the Netherlands. A network of single capacitance sensors installed per field will provide continuous measurements of soil moisture in the study area. Ground penetrating radar will be used to measure soil moisture variability within a single field for different time periods. During wetter months, optimal conditions for traffic will be assessed using simultaneous soil strength and soil moisture measurements. Towards water deficit periods, focus is on the relation (or the lack thereof) between surface soil moisture and root zone soil moisture to determine the amount of water for crops. Spatio-temporal distribution will determine important physical controls for surface and root zone soil moisture and provide insights for root-zone soil moisture. Existing models for field scale soil-water balance and data assimilation methods (e.g. Kalman filter) will be combined to estimate root zone soil moisture. Furthermore, effects of root development on soil structure and soil hydraulic properties and subsequent effects on trafficability and crop water availability will be investigated. This research project has recently started, therefore we want to present methods and framework of

  7. The variability of standard artificial soils: Behaviour, extractability and bioavailability of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Hofman, Jakub, E-mail: hofman@recetox.muni.cz [Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 753/5, Brno CZ-62500 (Czech Republic); Hovorková, Ivana [Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 753/5, Brno CZ-62500 (Czech Republic); Semple, Kirk T. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2014-01-15

    Highlights: • Artificial soils from different laboratories revealed different fates, behaviour and bioavailability of lindane and phenanthrene. • Lindane behaviour was related to organic carbon. • Phenanthrene behaviour was significantly affected by degrading microorganisms from peat. • Sterilization of artificial soils might reduce unwanted variability. -- Abstract: Artificial soil is an important standard medium and reference material for soil ecotoxicity bioassays. Recent studies have documented the significant variability of their basic properties among different laboratories. Our study investigated (i) the variability of ten artificial soils from different laboratories by means of the fate, extractability and bioavailability of phenanthrene and lindane, and (ii) the relationships of these results to soil properties and ageing. Soils were spiked with {sup 14}C-phenanthrene and {sup 14}C-lindane, and the total residues, fractions extractable by hydroxypropyl-β-cyclodextrin, and the fractions of phenanthrene mineralizable by bacteria were determined after 1, 14, 28 and 56 days. Significant temporal changes in total residues and extractable and mineralizable fractions were observed for phenanthrene, resulting in large differences between soils after 56 days. Phenanthrene mineralization by indigenous peat microorganisms was suggested as the main driver of that, outweighing the effects of organic matter. Lindane total residues and extractability displayed much smaller changes over time and smaller differences between soils related to organic matter. Roughly estimated, the variability between the artificial soils was comparable to natural soils. The implications of such variability for the results of toxicity tests and risk assessment decisions should be identified. We also suggested that the sterilization of artificial soils might reduce unwanted variability.

  8. 洞庭湖区土壤地球化学基准值与污染等级划分%Soil geochemical baseline and pollution level division in Dongting lake area

    Institute of Scientific and Technical Information of China (English)

    张建新

    2014-01-01

    Deep soil and its geochemical significance in multi-objective investigation are hot topics among environmental scientists. The author compared 54 indexes and their geochemical distribution characteristics in surface soil and deep soil of Dongting plain and hillock area, and studied the element content variation from natural differentiation and anthropogenic influence in the pedogenic process. With deep soil as the reference, the author obtained regional soil geochemical background value and baseline and proposed a method for the classification of surface soil pollution levels.%通过洞庭湖平原与周边丘岗山地区深、表层土壤中54项指标的地球化学分析对比,研究成壤过程中元素的自然分异和人为叠加作用造成的土壤元素含量在垂向上的差异;以深层土壤为参照,求解区域土壤的地球化学背景值和基准值,并以此为标准提出表层土壤污染等级划分的地球化学方法。

  9. Soil contamination assessment for Pb, Zn and Cd in a slag disposal area using the integration of geochemical and microbiological data.

    Science.gov (United States)

    Kasemodel, Mariana Consiglio; Lima, Jacqueline Zanin; Sakamoto, Isabel Kimiko; Varesche, Maria Bernadete Amancio; Trofino, Julio Cesar; Rodrigues, Valéria Guimarães Silvestre

    2016-12-01

    Improper disposal of mining waste is still considered a global problem, and further details on the contamination by potentially toxic metals are required for a proper assessment. In this context, it is important to have a combined view of the chemical and biological changes in the mining dump area. Thus, the objective of this study was to evaluate the Pb, Zn and Cd contamination in a slag disposal area using the integration of geochemical and microbiological data. Analyses of soil organic matter (SOM), pH, Eh, pseudo-total concentration of metals, sequential extraction and microbial community by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were conducted. Metal availability was evaluated based on the geoaccumulation index (I geo), ecological risk ([Formula: see text]), Risk Assessment Code (RAC) and experimental data, and different reference values were tested to assist in the interpretation of the indices. The soil pH was slightly acidic to neutral, the Eh values indicated oxidized conditions and the average SOM content varied from 12.10 to 53.60 g kg(-1). The average pseudo-total concentrations of metals were in the order of Zn > Pb > Cd. Pb and Zn were mainly bound to the residual fraction and Fe-Mn oxides, and a significant proportion of Cd was bound to the exchangeable and carbonate fractions. The topsoil (0-20 cm) is highly contaminated (I geo) with Cd and has a very high potential ecological risk ([Formula: see text]). Higher bacterial diversity was mainly associated with higher metal concentrations. It is concluded that the integration of geochemical and microbiological data can provide an appropriate evaluation of mining waste-contaminated areas.

  10. Relic components within the soil cover of Mexico: regional variability

    Science.gov (United States)

    Solleiro Rebolledo, Elizabeth; Sedov, Sergey

    2015-04-01

    The case of paleosols persisting on the land surface (non-buried paleosols or relict soils) besides paleoecological interest has specific implications for studies of soil geography, ecology and management. In fact these soil bodies form part of the modern soil mantle and provide ecological services for the current (agro)ecosystems but are neither formed nor re-produced by these ecosystems, conforming locally extinct soils (although similar profiles can develop at present under other bioclimatic conditions). In consequence, they are a heritage of past climatic and biotic conditions now extinct, thus presenting a non-restorable component of the present landscape. Mexico has so abundant and diverse paleosols, both surface and buried, that really could be considered to be a "paleopedological paradise". Two groups of factors promote generation of this abundance: Major part of territory of Mexico is occupied by mountainous landscapes with high intensity of tectonic, volcanic and geomorphic processes. These processes create a complex mosaic of geological materials and landforms of different age (like alluvial and lake terraces, eroded slopes, and volcanic deposits of various eruptions). Meanwhile younger landsurfaces are occupied by the recently developed soils, the older ones could bear the relict soil bodies. The same processes produce sedimentary strata (alluvial, colluvial, pyroclastic, etc.) which frequently cover the pre-existing landsurfaces and soils, producing series of buried paleosols. In this work we present three study cases of relict paleosols that are integrated to the modern soil cover of Mexico: the case of reddish-brown soils in the arid landscapes of Sonora (in the north); the pedosediments (tepetates) in central Mexico; and the red soils developed under humid conditions in Yucatan (in the south).

  11. 海南岛农田土壤Se的地球化学特征%Geochemical Characteristics of Soil Selenium in Farmland of Hainan Island

    Institute of Scientific and Technical Information of China (English)

    杨忠芳; 余涛; 侯青叶; 杨奕; 傅杨荣; 赵相雷

    2012-01-01

    Se是人和动物必需的微量元素之一,具有广阔的开发应用前景,研究土壤中Se的地球化学分布规律和生物有效性控制因素意义重大.系统总结了海南岛27 426 km2范围内土壤Se的含量特征和影响因素.结果表明,研究区69.98%土地面积为足硒和富硒土壤,表层土壤Se含量在一定程度上继承了成土母岩(或深层土壤)Se含量,但不同成土母岩形成的表层土壤Se含量富集贫化趋势不同.进一步研究显示,土壤中Se含量与有机碳、Al2O3、TFe2O3、Mn和CIA等具有显著的正相关关系,说明土壤中粘土矿物、有机碳、铁锰氧化物及风化淋溶程度对Se的地球化学行为有重要影响,同时这些指标又是影响土壤Se生物有效性的重要参数.土壤有机碳、粘粒、CEC等含量或指标越高,Se的生物有效性越低.研究区土壤pH >6.5时,土壤Se含量较低;土壤pH<6.5时,土壤Se含量随pH下降而增加;当土壤pH为5.5~7.5时,土壤Se生物有效性相对较高.因此,开发富硒农产品不但要依据土壤总Se含量,还必须考虑土壤pH、TOC、CEC、粘粒等指标含量.%Selenium is one of the most important trace elements for human and animal, which also has a bright application future. The research of geochemical distribution and bioavailability controlling factors of soil selenium has important significance. In this paper, characteristics and influencing factors of soil selenium content all over the Hainan Island covering the range of 27,426 km2 were summarized. The results showed that the selenium-full and selenium-rich soil was up to 69. 98% of the study area and topsoil selenium content to a certain extent inherited into the soil parent rock ( or deep soil) , but the difference among soil parent rock formation generated enrichment or dilution of soil selenium content. Further studies have shown that the selenium content in soil has a significant positive correlation with organic carbon, aluminum

  12. [Study on three-dimension spatial variability of regional soil salinity based on spectral indices].

    Science.gov (United States)

    Liu, Guang-Ming; Wu, Ya-Kun; Yang, Jin-Song; Yu, Shi-Peng

    2013-10-01

    In order to illustrate the three-dimension spatial variability of soil salinity in central China flood area of the Yellow river, integrated soil sampling data and remote sensing data, spectral indices and inverse distance weighting (IDW) method were applied to the estimation and simulation of three-dimension spatial distribution of soil salinity. The study was carried out in typical central China flood area of the Yellow river in Fengqiu County, Henan Province, China. The electrical conductivity of the saturation extract (EC1: 5) of 505 soil samples collected at 101 points was measured. The results indicated that the coefficient of variation of soil salinity at each soil layer is from 0.218 to 0.324 and exhibited the moderate spatial variability. The average of soil electrical conductivity is from 0.121 to 0.154 ds x m(-1). The 2 820 three-dimension spatial scattered data for soil electrical conductivity were taken at soil salinity mapping interpreted by spectral indices and soil electrical conductivity. Three-dimension IDW interpolation showed that a large area of high soil salinity mainly located in the region of Tianran canal and the along of the Yellow river. The shape of the soil salinity profile was downward flowed, revealing soil salinity increasing with depth in whole soil profile and soil salinity accumulated in the subsoil. The accuracy of the predictions was tested using 20 soil sampled points. The root mean square error (RMSE) of calibration for three-dimension distribution of soil salinity showed that the IDW method based on spectral indices was ideal. The research results can provide theoretical foundations to the management and utilization of salt-affected land in China flood area, especially in the Yellow river zone.

  13. 7Be:A Geochemical Tracer for Seasonal Erosion of Surface Soil in Watershed of Lake Hongfeng,Guizahou ,China

    Institute of Scientific and Technical Information of China (English)

    BAIZHANGUO; P.H.SANTSCHI; 等

    1996-01-01

    7Be penetrative depth in undisturbed surface soil is within 4mm.7Be activity shows exponential decrease with soil depth,which is expressed as a diffusion process.7Be penetrative depth in undisturbed surface soil is apparently deeper in the fall (0.22-0.37g cm-1) than in the spring (0.11-0.28g cm-2) at the same site;Whereas,7Be apparent activity at the top of surface soil is higher in the spring (0.3-2.2Bq g-1)than in the fall (0.2-0.5Bqg-1) at the same site,The 7Be inventory(189-544Bq m-2)changes with both locations and seasons.Although the 7Be flux to the earth's surface increases with amount of precipitation,its maximum inventory in the soil profiles decreases to 30%-40% after the rainy period.Calculated by the diffusion equation,the erosion and accumulation rates of soil particles are agreeable with the observation in situ,Which shows that the rates in fall are 1.5 times those in spring.The eroded soil particles almost all have been removed on the tablelands rathel than transported into the drainage system.This indicates that the soil erosion process in the karst region is only partial transportation within a short distance.

  14. Geochemical and mineralogical investigation of domestic archaeological soil features at the Tiel-Passewaaij site, The Netherlands

    NARCIS (Netherlands)

    Oonk, S.; Slomp, C.P.; Huisman, D.J.; Vriend, S.P.

    2008-01-01

    Archaeological soil features can be defined as areas of staining in ancient cultural soil horizons and are frequently used in surveys to locate sites and activity areas. Visual observation of these features, however, provides only limited information on their origin and the processes leading to thei

  15. Identification and mapping of associations among soil variables

    NARCIS (Netherlands)

    Braimoh, A.; Stein, A.; Vlek, P.

    2005-01-01

    Assessment and management of soil quality for agricultural land use planning in Northern Ghana is important as a consequence of increasing competition for land among many land uses. It requires information about soil properties that are typically intercorrelated. This study identifies associations a

  16. Topographic variability influences the carbon sequestration potential of arable soils

    DEFF Research Database (Denmark)

    Chirinda, Ngoni; Elsgaard, Lars; Thomsen, Ingrid Kaag

    2012-01-01

    cm soil depths. Concurrently, gas was sampled from 40, 50, and 80 cm depths using steel rods connected to a sampling port. Concentrations of CO2 in the gas samples were analyzed by gas chromatography. The results show that at the upslope position, soils from the topsoil horizon clearly had higher C...

  17. A Simple Model of the Variability of Soil Depths

    Directory of Open Access Journals (Sweden)

    Fang Yu

    2017-06-01

    Full Text Available Soil depth tends to vary from a few centimeters to several meters, depending on many natural and environmental factors. We hypothesize that the cumulative effect of these factors on soil depth, which is chiefly dependent on the process of biogeochemical weathering, is particularly affected by soil porewater (i.e., solute transport and infiltration from the land surface. Taking into account evidence for a non-Gaussian distribution of rock weathering rates, we propose a simple mathematical model to describe the relationship between soil depth and infiltration flux. The model was tested using several areas in mostly semi-arid climate zones. The application of this model demonstrates the use of fundamental principles of physics to quantify the coupled effects of the five principal soil-forming factors of Dokuchaev.

  18. Effect of Low-Molecular-Weight Organic Acids on Cl- Adsorption by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    XU Ren-Kou; ANG Ma-Li; WANG Qiang-Sheng; JI Guo-Liang1

    2004-01-01

    Low-molecular-weight (LMW) organic acids exist widely in soils and have been implicated in many soil processes.The objective of the present paper was to evaluate effect of two LMW organic acids, citric acid and oxalic acid, on Cl- adsorption by three variable charge soils, a latosol, a lateritic red soil and a red soil, using a batch method. The results showed that the presence of citric acid and oxalic acid led to a decrease in Cl- adsorption with larger decreases for citric acid. Among the different soils Gl- adsorption in the lateritic red soil and the red soil was more affected by both the LMW organic acids than that in the latosol.

  19. Geochemical fractions and risk assessment of trace elements in soils around Jiaojia gold mine in Shandong Province, China.

    Science.gov (United States)

    Cao, Feifei; Kong, Linghao; Yang, Liyuan; Zhang, Wei

    2015-09-01

    Soils located adjacent to the Jiaojia gold mine were sampled and analyzed to determine the degree of which they were contaminated by trace elements (Hg, As, Cd, Pb, Cu, and Zn) in Shandong Province, China. All 18 samples exhibited mean Hg, As, Cd, and Pb concentrations in excess of local background values, while the mean concentrations of Cu and Zn were below the background values. In addition, the concentrations of trace elements in gold smelter (GS) soils were higher than in the gold mine (GM) soils. The result from a modified Tessier sequential extraction procedure was that with the exception of Cu in soils near the smelter, the trace elements were predominantly associated with the residual fraction. After residual fraction, most Hg was mainly humic acid and strong organic fraction, while most As was the humic acid. Cd was associated with the water soluble, ion exchange, and carbonate fractions compared with the other trace elements. Furthermore, Cu, Pb, and Zn were more concentrated in the humic acid and Fe/Mn oxide fraction. The fractions of trace elements were affected by soil pH and Ec (Electrical conductivity). The humic acid fraction of Hg as well as the ion exchange fraction of Cd and Zn displayed negative correlations with soil pH. The strong organic fraction of Hg, the Fe/Mn oxide fraction of Cd, and the carbonate fraction of Zn were positively related to the soil Ec. The strong organic fraction and ion exchange fraction of Zn were negatively related to soil Ec. However, the ion exchange and carbonate fractions of As showed significant positive correlations with soil pH. A calculated individual availability factor (A f (i) ) is used; the values of each trace element in the soils are in the following order: Cu > Cd > Pb > Zn > As > Hg. When combined with a risk assessment code, data suggest that Hg, As, Pb, and Zn levels showed low risk for the environment, whereas Cd levels in soils adjacent to the GM and Cu levels in soils adjacent to the GS showed

  20. Spatial Variability of Soil Chemical Properties in the Reclaiming Marine Foreland to Yellow Sea of China

    Institute of Scientific and Technical Information of China (English)

    WEI Yi-chang; BAI You-lu; JIN Ji-yun; ZHANG Fang; ZHANG Li-ping; LIU Xiao-qiang

    2009-01-01

    Precise information about the spatial variability of soil properties is essential in developing site-specific soil management,such as variable rate application of fertilizers.In this study the sampling grid of 100 m×100 m was established to collect 1703 soil samples at the depth of 0-20 cm,and examine spatial patterns including 13 soil chemical properties (pH,OM,NH4+,PK,Ca,Mg,S,B,Cu,Fe,Mn,and Zn) in a 1760 ha rice field in Haifeng farm,China,from 6th to 22nd of April,2006,before fertilizer application and planting.Soil analysis was performed by ASI (Agro Services International) and data were analyzed both statistically and geostatistically.Results showed that the contents of soil OM,NH4+,and Zn in Haifeng farm were very low for rice production and those of others were enough to meet the need for rice cultivation.The spatial distribution model and spatial dependence level for 13 soil chemical properties varied in the field.Soil Mg and B showed strong spatial variability on both descriptive statistics and geostatistics,and other properties showed moderate spatial variability.Themaximum ranges for K,Ca,Mg,S,Cu and Mn were all~3990.6m and the minimum ranges for soil pH,OM,NH4+,P,Fe,and Zn ranged from 516.7 to 1166.2 m.Clearpatchy distribution of N,P,K,Mg,S,B,Mn,and Zn were found from their spatial distribution maps.This proved that sampling strategy for estimating variability should be adapted to the different soil chemical properties and field management.Therefore,the spatial variability of soil chemical properties with strong spatial dependence could be readily managed and a site-specific fertilization scheme for precision farming could be easily developed.

  1. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    Science.gov (United States)

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles.

  2. The Seasonal Difference in Soil Moisture Patterns Considering the Meteorological Variables Throughout the Korean Peninsula

    Directory of Open Access Journals (Sweden)

    Eunsang Cho

    2016-01-01

    Full Text Available This study focuses on the seasonal differences in soil moisture patterns considering the impact of meteorological variables (air/ground temperature, precipitation, and the amount of insolation on soil moisture variability over the Korean peninsula between January 2012 and February 2013. We found that soil moisture spatial distributions changed differently with the mean soil moisture content according to the season using statistical metrics (skewness and kurtosis (summer: 1 June to 31 August, winter: 1 November to 31 January. Daily variations in meteorological variables had different relationships with the changes in soil moisture for two seasons. Air and soil temperature changes clearly had negative relationships with the soil moisture change during the summer period while they had positive relationships during the winter period. Temporal stability testing showed that the representative soil moisture sites on a regional scale could be changed with seasonal periods, especially in the Asian monsoon region. In conclusion, these results provide evidence that there are clear differences in soil moisture patterns according to seasonal characteristics. This study might be useful for further researches relating to climate-meteorological effects on soil moisture patterns on a regional scale.

  3. Drivers for spatial variability in agricultural soil organic carbon stocks in Germany

    Science.gov (United States)

    Vos, Cora; Don, Axel; Hobley, Eleanor; Prietz, Roland; Heidkamp, Arne; Freibauer, Annette

    2017-04-01

    Soil organic carbon is one of the largest components of the global carbon cycle. It has recently gained importance in global efforts to mitigate climate change through carbon sequestration. In order to find locations suitable for carbon sequestration, and estimate the sequestration potential, however, it is necessary to understand the factors influencing the high spatial variability of soil organic carbon stocks. Due to numerous interacting factors that influence its dynamics, soil organic carbon stocks are difficult to predict. In the course of the German Agricultural Soil Inventory over 2500 agricultural sites were sampled and their soil organic carbon stocks determined. Data relating to more than 200 potential drivers of SOC stocks were compiled from laboratory measurements, farmer questionnaires and climate stations. The aims of this study were to 1) give an overview of soil organic carbon stocks in Germany's agricultural soils, 2) to quantify and explain the influence of explanatory variables on soil organic carbon stocks. Two different machine learning algorithms were used to identify the most important variables and multiple regression models were used to explore the influence of those variables. Models for predicting carbon stocks in different depth increments between 0-100 cm were developed, explaining up to 62% (validation, 98% calibration) of total variance. Land-use, land-use history, clay content and electrical conductivity were main predictors in the topsoil, while bedrock material, relief and electrical conductivity governed the variability of subsoil carbon stocks. We found 32% of all soils to be deeply anthropogenically transformed. The influence of climate related variables was surprisingly small (≤5% of explained variance), while site variables explained a large share of soil carbon variability (46-100% of explained variance), in particular in the subsoil. Thus, the understanding of SOC dynamics at regional scale requires a thorough description

  4. Vegetation-induced soil water repellency as a strategy in arid ecosystems. A geochemical approach in Banksia woodlands (SW Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, Jose Antonio; Zavala, Lorena M.; Stevens, Jason; Jordan, Antonio

    2016-04-01

    Introduction Banksia woodlands (BW) are iconic ecosystems of Western Australia (WA) composed by an overstorey dominated by Proteaceae, e.g. Banksia menziesii and Banksia attenuata, in combination with other species, such as Eucalyptus spp., Verticordia spp. or Melaleuca spp. Although located in very poor dune soils, BW provide numerous ecosystem services and sustain a high biodiversity. In this area, annual rainfall is relatively high (about 800 mm) but permeability of the sandy substrate leads to a functionally arid ecosystem. Currently, BW are threatened by sand mining activities and urban expansion; therefore conservation and restoration of these woodlands are critical. Despite numerous efforts, the success of restoration plans is usually poor mostly due to the high sensitivity to drought stress and poor seedling survival rates (5-30%) (Benigno et al., 2014). A characteristic feature of BW is their root architecture, formed by a proteoid (cluster) system that spreads to form thick mats below the soil surface, favouring the uptake of nutrients (especially, P), and preventing soil erosion. Root exudates are related to numerous plant functions, as they facilitate penetration of roots in soil and enhance the extraction of scarce mineral nutrients and its further assimilation. Exudates may also interact directly with soil or indirectly through microbial mediated events being also related to soil water repellency (SWR; Lozano et al, 2014). Knowledge about the specific compounds able to induce SWR is limited (Doerr et al., 2000), but it is generally accepted that is caused by organic molecules coating the surface of soil mineral particles and aggregates (Jordán et al., 2013). Proteaceae release short-chained organic acids to enhance phosphate acquisition, which have been also reported to be related with SWR (Jiménez-Morillo et al., 2014). It is hypothesized that disruption of water dynamics in mature BW soils is underlying the failure of restoration plans. This

  5. Temporal Dynamics of Soil Moisture Variability at the Landscape Scale: Implications for Land Surface Models.

    Science.gov (United States)

    Montaldo, N.; Albertson, J. D.

    2001-12-01

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends directly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, microbial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances affect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a conservation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spatial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calculate land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions using the proposed soil moisture

  6. Temporal Dynamics of Soil Moisture Variability: Implications For Land Surface Models

    Science.gov (United States)

    Montaldo, N.; Albertson, J. D.

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends di- rectly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, mi- crobial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances af- fect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a con- servation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spa- tial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calcu- late land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions us- ing the proposed

  7. Geochemical and mineralogical evidence for Sahara and Sahel dust additions to Quaternary soils on Lanzarote, eastern Canary Islands, Spain

    Science.gov (United States)

    Muhs, D.R.; Budahn, J.; Skipp, G.; Prospero, J.M.; Patterson, D.; Bettis, E. Arthur

    2010-01-01

    Africa is the most important source of dust in the world today, and dust storms are frequent on the nearby Canary Islands. Previous workers have inferred that the Sahara is the most important source of dust to Canary Islands soils, with little contribution from the Sahel region. Soils overlying a late Quaternary basalt flow on Lanzarote, Canary Islands, contain, in addition to volcanic minerals, quartz and mica, exotic to the island's bedrock. Kaolinite in the soils also likely has an exotic origin. Trace-element geochemistry shows that the soils are derived from varying proportions of locally derived basalt and African dust. Major-element geochemistry, clay mineralogy and interpretation of satellite imagery suggest that dust additions to the Canary Islands come not only from the Sahara Desert, but also from the Sahel region. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

  8. Spatial variability of soil fertility and its relation with cocoa yield

    Directory of Open Access Journals (Sweden)

    Railton O. dos Santos

    Full Text Available ABSTRACT The knowledge on the spatial variability of soil properties and crops is important for decision-making on agricultural management. The objective of this study was to evaluate the spatial variability of soil fertility and its relation with cocoa yield. The study was conducted over 14 months in an area cultivated with cocoa. A sampling grid was created to study soil chemical properties and cocoa yield (stratified in season, off-season and annual. The data were analyzed using descriptive and exploratory statistics, and geostatistics. The chemical attributes were classified using fuzzy logic to generate a soil fertility map, which was correlated with maps of crop yield. The soil of the area, except for the western region, showed possibilities ranging from medium to high for cocoa cultivation. Soil fertility showed positive spatial correlation with cocoa yield, and its effect was predominant only for the off-season and annual cocoa.

  9. Geostatistical independent simulation of spatially correlated soil variables

    Science.gov (United States)

    Boluwade, Alaba; Madramootoo, Chandra A.

    2015-12-01

    The selection of best management practices to reduce soil and water pollution often requires estimation of soil properties. It is important to find an efficient and robust technique to simulate spatially correlated soils parameters. Co-kriging and co-simulation are techniques that can be used. These methods are limited in terms of computer simulation due to the problem of solving large co-kriging systems and difficulties in fitting a valid model of coregionalization. The order of complexity increases as the number of covariables increases. This paper presents a technique for the conditional simulation of a non-Gaussian vector random field on point support scale. The technique is termed Independent Component Analysis (ICA). The basic principle underlining ICA is the determination of a linear representation of non-Gaussian data so that the components are considered statistically independent. With such representation, it would be easy and more computationally efficient to develop direct variograms for the components. The process is presented in two stages. The first stage involves the ICA decomposition. The second stage involves sequential Gaussian simulation of the generated components (which are derived from the first stage). This technique was applied for spatially correlated extractable cations such as magnesium (Mg) and iron (Fe) in a Canadian watershed. This paper has a strong application in stochastic quantification of uncertainties of soil attributes in soil remediation and soil rehabilitation.

  10. Variability in soil CO2 efflux across distinct urban land cover types

    Science.gov (United States)

    Weissert, Lena F.; Salmond, Jennifer A.; Schwendenmann, Luitgard

    2015-04-01

    As a main source of greenhouse gases urban areas play an important role in the global carbon cycle. To assess the potential role of urban vegetation in mitigating carbon emissions we need information on the magnitude of biogenic CO2 emissions and its driving factors. We examined how urban land use types (urban forest, parklands, sportsfields) vary in their soil CO2 efflux. We measured soil CO2 efflux and its isotopic signature, soil temperature and soil moisture over a complete growing season in Auckland, New Zealand. Soil physical and chemical properties and vegetation characteristics were also measured. Mean soil CO2 efflux ranged from 4.15 to 12 μmol m-2 s-1. We did not find significant differences in soil CO2 efflux among land cover types due to high spatial variability in soil CO2 efflux among plots. Soil (soil carbon and nitrogen density, texture, soil carbon:nitrogen ratio) and vegetation characteristics (basal area, litter carbon density, grass biomass) were not significantly correlated with soil CO2 efflux. We found a distinct seasonal pattern with significantly higher soil CO2 efflux in autumn (Apr/May) and spring (Oct). In urban forests and sportsfields over 80% of the temporal variation was explained by soil temperature and soil water content. The δ13C signature of CO2 respired from parklands and sportsfields (-20 permil - -25 permil) were more positive compared to forest plots (-29 permil) indicating that parkland and sportsfields had a considerable proportion of C4 grasses. Despite the large intra-urban variability, our results compare to values reported from other, often climatically different cities, supporting the hypothesis of homogenization across urban areas as a result of human management practices.

  11. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20151884 An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing100083,China)Regional Geochemistry of Sanjiang Region in Yunnan Province and Its Copper-Polymetallic Prospecting Significance(Geophysical and Geochemical Exploration,ISSN1000-8918,

  12. Magnetic, Geochemical and Mineralogical Charac-teristics of Soils in Qiangtang Basin, Tibet, China:Implications for Prospective Oil and Gas Land

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The alteration of iron-bearing minerals induced by hydrocarbon microseepage above oil/gas reservoirs has been evaluated using measurements of soil magnetic susceptibility κ, geochemical compositions (gas hydrocarbon and alteration carbonate ΔC), and composition and concentration of iron-bearing minerals. The analyses were performed along two profiles across the Qiangtang basin in Tibet, China: the Nuoermahu-Xuehuanhu profile (C) and the Mugari-Huochetoushan profile (E). Results show that three strong magnetic anomalies (C1, E1 and E2 anomalies) are related to the distribution of Neogene volcanic rocks on the surface in the Gangmacuo-Xiyaergang uplift. Two other anomalies (C2 and E4 anomalies), characterized by both moderately amplitude magnetic susceptibility and elevated soil gas hydrocarbons, occur near fault zones in the Cuoni-Donghu synclinorium. These latter anomalies display characteristics of hydrocarbon microseepage anomalies commonly associated with oil and gas accumulations. Their presence in the Cuoni-Donghu synclinorium suggests that parts of the Qiangtang basin may have significant petroleum potential.

  13. Regional Variability of the Effects of Land Use Systems on Soil Properties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to explore the regional variability of the effects of land use systems on soil properties, Shouyang County in Shanxi Province and Danling County in Sichuan Province of China were selected as the study areas. Field soil samples of the four land use systems (natural forest, forest plantation, shrubland, and cropland) were collected, respectively, from the two areas. The general statistical tools were used to analyze soil data. The results showed that the influence of land use systems on soil properties was significant. In general, soils in slightly human-disturbed land use systems presented a higher fertility level than those in strongly human-disturbed land use systems in both areas. Furthermore, the impacts of the same land use systems on soil properties showed a distinct regional variability, and even in the same land use system,different farming systems and site management measures (such as irrigation, fertilization, and pesticides) could also lead to the regional heterogeneity in soil properties. The regional variability of land use effects on soil properties reveals the regional variability of the effects of human activities on environmental changes, and could explain the complex relationship between humans and the natural environment in certain ways.

  14. Amplification and dampening of soil respiration by changes in temperature variability

    Science.gov (United States)

    C.A. Sierra; M.E. Harmon; E.A. Thomann; S.S. Perakis; H.W. Loescher

    2011-01-01

    Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic...

  15. [Spatial pattern of soil fertility in Bashan tea garden: a prediction based on environmental auxiliary variables].

    Science.gov (United States)

    Qin, Le-feng; Yang, Chao; Lin, Fen-fang; Yang, Ning; Zheng, Xin-yu; Xu, Hong-wei; Wang, Ke

    2010-12-01

    Taking topographic factors and NDVI as auxiliary variables, and by using regression-kriging method, the spatial variation pattern of soil fertility in Bashan tea garden in the hilly area of Fuyang City was explored. The spatial variability of the soil fertility was mainly attributed to the structural factors such as relative elevation and flat/vertical curvature. The lower the relative elevation, the worse the soil fertility was. The overall soil fertility level was relatively high, and the area with lower soil fertility only accounted for 5% of the total. By using regression-kriging method with relative elevation as auxiliary variable, the prediction accuracy of soil fertility was obviously higher than that by using ordinary kriging method, with the mean error and root mean square error being 0. 028 and 0. 108, respectively. It was suggested that the prediction method used in this paper could fully reflect the effects of environmental variables on soil fertility , improve the prediction accuracy about the spatial pattern of soil fertility, and provide scientific basis for the precise management of tea garden.

  16. Soil salinity and acidity: Spatial variability and effects on rice production in West Africa's mangrove zone.

    NARCIS (Netherlands)

    Sylla, M.

    1994-01-01

    In the mangrove environment of West Africa, high spatial and temporal variability of soil constraints (salinity and acidity) to rice production is a problem for the transfer and adoption of new agronomic techniques, for land use planning, and for soil and water management. Recently, several National

  17. Geochemical control of microbial Fe(III) reduction potential in wetlands: Comparison of the rhizosphere to non-rhizosphere soil

    Science.gov (United States)

    Weiss, J.V.; Emerson, D.; Megonigal, J.P.

    2004-01-01

    We compared the reactivity and microbial reduction potential of Fe(III) minerals in the rhizosphere and non-rhizosphere soil to test the hypothesis that rapid Fe(III) reduction rates in wetland soils are explained by rhizosphere processes. The rhizosphere was defined as the area immediately adjacent to a root encrusted with Fe(III)-oxides or Fe plaque, and non-rhizosphere soil was 0.5 cm from the root surface. The rhizosphere had a significantly higher percentage of poorly crystalline Fe (66??7%) than non-rhizosphere soil (23??7%); conversely, non-rhizosphere soil had a significantly higher proportion of crystalline Fe (50??7%) than the rhizosphere (18??7%, Psoil Fe(III)-oxide pool. Similarly, microbial reduction consumed 75-80% of the rhizosphere pool in 10 days compared to 30-40% of the non-rhizosphere soil pool. Differences between the two pools persisted when samples were amended with an electron-shuttling compound (AQDS), an Fe(III)-reducing bacterium (Geobacter metallireducens), and organic carbon. Thus, Fe(III)-oxide mineralogy contributed strongly to differences in the Fe(III) reduction potential of the two pools. Higher amounts of poorly crystalline Fe(III) and possibly humic substances, and a higher Fe(III) reduction potential in the rhizosphere compared to the non-rhizosphere soil, suggested the rhizosphere is a site of unusually active microbial Fe cycling. The results were consistent with previous speculation that rapid Fe cycling in wetlands is due to the activity of wetland plant roots. ?? 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

  18. Temporal and spatial variability of soil biological activity at European scale

    Science.gov (United States)

    Mallast, Janine; Rühlmann, Jörg

    2015-04-01

    The CATCH-C project aims to identify and improve the farm-compatibility of Soil Management Practices including to promote productivity, climate change mitigation and soil quality. The focus of this work concentrates on turnover conditions for soil organic matter (SOM). SOM is fundamental for the maintenance of quality and functions of soils while SOM storage is attributed a great importance in terms of climate change mitigation. The turnover conditions depend on soil biological activity characterized by climate and soil properties. Soil biological activity was investigated using two model concepts: a) Re_clim parameter within the ICBM (Introductory Carbon Balance Model) (Andrén & Kätterer 1997) states a climatic factor summarizing soil water storage and soil temperature and its influence on soil biological activity. b) BAT (biological active time) approach derived from model CANDY (CArbon and Nitrogen Dynamic) (Franko & Oelschlägel 1995) expresses the variation of soil moisture, soil temperature and soil aeration as a time scale and an indicator of biological activity for soil organic matter (SOM) turnover. During an earlier stage both model concepts, Re_clim and BAT, were applied based on a monthly data to assess spatial variability of turnover conditions across Europe. This hampers the investigation of temporal variability (e.g. intra-annual). The improved stage integrates daily data of more than 350 weather stations across Europe presented by Klein Tank et al. (2002). All time series data (temperature, precipitation and potential evapotranspiration and soil texture derived from the European Soil Database (JRC 2006)), are used to calculate soil biological activity in the arable layer. The resulting BAT and Re_clim values were spatio-temporal investigated. While "temporal" refers to a long-term trend analysis, "spatial" includes the investigation of soil biological activity variability per environmental zone (ENZ, Metzger et al. 2005 representing similar

  19. Spatial and temporal variability of microbes in selected soils at the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Angerer, J.P.; Winkel, V.K.; Ostler, W.K.; Hall, P.F.

    1993-12-31

    Large areas encompassing almost 800 hectares on the Nevada Test Site, Nellis Air Force Range and the Tonopah Test Range are contaminated with plutonium. Decontamination of plutonium from these sites may involve removal of plants and almost 370,000 cubic meters of soil. The soil may be subjected to a series of processes to remove plutonium. After decontamination, the soils will be returned to the site and revegetated. There is a paucity of information on the spatial and temporal distribution of microbes in soils of the Mojave and Great Basin Deserts. Therefore, this study was initiated to determine the biomass and diversity of microbes in soils prior to decontamination. Soils were collected to a depth of 10 cm along each of five randomly located 30-m transects at each of four sites. To ascertain spatial differences, soils were collected from beneath major shrubs and from associated interspaces. Soils were collected every three to four months to determine temporal (seasonal) differences in microbial parameters. Soils from beneath shrubs generally had greater active fungi and bacteria, and greater non-amended respiration than soils from interspaces. Temporal variability also was found; total and active fungi, and non-amended respiration were correlated with soil moisture at the time of sampling. Information from this study will aid in determining the effects of plutonium decontamination on soil microorganisms, and what measures, if any, will be required to restore microbial populations during revegetation of these sites.

  20. Ten years of continuous monitoring of soil CO2 flux: results and implications from the first geochemical monitoring network on Mount Etna.

    Science.gov (United States)

    Liuzzo, Marco; Gurrieri, Sergio; Giuffrida, Giovanni; Gaetano, Giudice; Cappuzzo, Santino

    2013-04-01

    Throughout the Mediterranean area, Mt. Etna is well known for its frequent eruptions and considerable lava flows, being, among all of the basaltic volcanoes, one of the most active in the world. The frequent activity of the last two decades has induced the scientific community and the Civil Defence to pay more attention to the surveillance of the volcano and, in view of this, a diverse range of monitoring systems have been developed, making Mt. Etna one of the most intensively studied volcanoes in the world. The measurement of soil CO2 flux for the purpose of identifying a possible correlation between CO2 flux variations and volcanic activity has been carried out for a long time on several active volcanoes around the world. Whilst almost all of these measurements have been made using direct sampling methods in the field, various kinds of automatic devices have more recently been developed to record real-time data, allowing a continuous remote monitoring of volcanic areas. On Mt. Etna the first network of continuous monitoring of geochemical parameters was developed in 2002 by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) of Palermo to monitor CO2 flux from the soil (EtnaGAS network) and was installed at various sites (18 in total) on the flanks of Mt. Etna. The very large quantity of soil CO2 flux data recorded by the network, during which several interesting eruptive phenomena took place, has provided the possibility to make an extensive statistical analysis, the outcome of which strongly suggests that anomalous measurements of CO2 flux was attributable to a volcanic origin and, in almost all cases, preceded the onset of volcanic activity. Here we present an interpretative model of the expected behaviour of CO2 flux from the soil (in terms of cycles of increase-decrease) during and between eruptions, and the actual data-series recorded by EtnaGAS which we found corresponded well with our model. A comparative multidisciplinary approach, incorporating

  1. [Nutrient spatial variability of tobacco soil restoration area and fertility suitability level evaluation].

    Science.gov (United States)

    Xu, Da-Bing; Deng, Jian-Qiang; Liu, Dong-Bi; Si, Guo-Han; Peng, Cheng-Lin; Yuan, Jia-Fu; Zhao, Shu-Jun; Wang, Rui

    2014-03-01

    By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH soils taken from the suburb, Baiyang and Qingjiangyuan, respectively. In conclusion, attentions should be paid on soil acidification in Baiyang, soil fertility and equalization in the suburb, and soil fertility in the region of Qingjiangyuan with low SFI.

  2. A Coupled Model of Hydro- Transport- Thermal in Variable Saturated Porous Media Considering Geochemical Process%地球化学作用下饱和-非饱和介质水力-传质-传热耦合模型

    Institute of Scientific and Technical Information of China (English)

    姜利国; 梁冰

    2011-01-01

    Geochemical process is one of the fftost important factors influenced fluid movement, solute transport and heat transfer in porous media such as rock and soil. Based on the unsaturated soil theory established by Fredlund, in which the unsaturated soil porous media has been considered as a media which has four phases, assumed the effect of precipitation/dissolution to be an individual phase. With some hypotheses, the porosity and water content of porous media are modified by solute concentration, a new coupled relation between solute transport and hydraulic parameters has been built. The new relation updates the traditional coupled model in which the impact from solute field acts On seepage flow field by only density and viscosity. Here, a coupled model of multi-phases and multi components hydraulic-transport-thermal and geochemical processes in variable saturated porous media is established. Using a infiltrate experiment for reactive coal mine gangue in the laboratory, the coupled numerical model is tested. The results show that the water seepage velocity calculated from experiment matches well the outcome from numerical model which considered the precipitation/dissolution coupling variable. Thus the applicability of the numerical model is verified.%地球化学作用是影响岩土类多孔介质中流体流动、传质、传热的重要因素之一.基于Fredlund所提出的非饱和土四相理论,将地球化学作用所产生的溶解/沉淀视为一个独立相,在一定的假设基础上,利用溶质浓度对介质孔隙度、含水率进行修正,从而建立起传质过程与介质水力性质之间的关系,改进了传统模型中传质过程与流体密度、黏度之间单一的耦合关系;并以此为基础建立了考虑地球化学作用下饱和-非饱和介质中多组分、多相流体渗流场-浓度场-温度场耦合的数学模型.通过在实验室内对反应性煤矸石进行渗透实验的结果对笔者所建模型进行了验证,

  3. Nanomineralogy as a new dimension in understanding elusive geochemical processes in soils: The case of low-solubility-index elements

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Michael; Hochella, Michael F.

    2016-05-20

    Nanomineralogy is a new dimension in understanding chemical processes in soils. These processes are revealed at the nanoscale within the structures and compositions of phases that heretofore were not even known to exist in the soils in which they are found. The discovery and understanding of soil chemistry in this way is best accessible via a combination of focused ion beam technology (for sample preparation) and high resolution, analytical transmission electron microscopy (for phase identification). We have used this scientific framework and these techniques to decipher past and present chemical processes in a soil in Sudbury, Ontario, Canada that has been impacted by both smelter contamination (acidification) and subsequent remediation within the past century. In this study, we use these methods to investigate mobilization and sequestration of the relatively immobile elements Al, Ti and Zr. In a micrometer-thick alteration layer on an albite grain, a first generation of clay minerals represents weathering of the underlying mineral prior to the acidification of the soils. Complex assemblages of Ti- and Zr-bearing nanophases occur on the surfaces of Fe-(hydr)oxide crystals and are the result of the dissolution of silicates and oxides and the mobilization of Ti- and Zr-bearing colloids under acidic conditions. These phases include anatase (TiO2), kleberite (Fe3+Ti6O11(OH)5) Ti4O7, baddelyite (ZrO2), a structural analogue to kelyshite (NaZr[Si2O6(OH)]) and authigenic zircon (ZrSiO4). Subsequent remediation of the acidic soils has resulted in the sequestration of Al and in the neoformation of the clay minerals kaolinite, smectite and illite. These complex mineral assemblages form a porous layer that controls the interaction of the underlying mineral with the environment.

  4. [Effects of variable temperature on organic carbon mineralization in typical limestone soils].

    Science.gov (United States)

    Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti

    2014-11-01

    Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P organic carbon in the limestone soil from forest land (SL) under the variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P soil organic carbon in both temperature treatments, which implied that controlling DOC production was an important way for the temperature influence of SOC mineralization. During the incubation

  5. Spatial variability of soil attributes and sugarcane yield in relation to topographic location

    OpenAIRE

    de Souza, Zigomar M.; Domingos G. P. Cerri; Paulo S. G. Magalhães; Siqueira, Diego S.

    2010-01-01

    Soils submitted to the same management system in places with little variation of landscape, manifest differentiated spatial variability of their attributes and crop yield. The aim of this work was to investigate the correlation between spatial variability of the soil attributes and sugarcane yield as a result of soil topography. To achieve this objective, a test area of 42 ha located at the São João Sugar Mill, in Araras, in the State of São Paulo, Brazil, was selected. Sugarcane yield was me...

  6. Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

    Science.gov (United States)

    Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

    2017-06-01

    Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

  7. Spatial and Temporal Variability of Soil Redistribution in a Heterogeneous Shrub Dominated Landscape

    Science.gov (United States)

    Van Pelt, R. S.; Zobeck, T. M.

    2015-12-01

    Redistribution of soil by wind results when the erosive force of the wind impacts bare, susceptible soil surfaces. In semi-arid and arid environments, many grasslands with protected surfaces are being replaced by heterogeneous shrub communities with bare, susceptible soil surfaces between the individual shrubs. The development of nutrient islands and the increases of fugitive dust in these areas is indicative of increases of soil redistribution, but few quantitative measurements have been made to date. We fenced three 1 ha areas in an approximately 100 ha coppice dune area of southeast New Mexico dominated by shinnery oak, sand sage, and mesquite and installed a 4 X 4 grid of MWAC sampler masts spaced at 20 m from each other. Weather data were collected at an automated weather station in each of the fenced areas. We found the patterns of soil redistribution to be highly variable in space and time. Differences in vegetation patterns and wind fields were noted among the plots for the same discrete time period that could explain some of the spatial variability. We also noted seasonality of wind fields that accounted for the temporally variable spatial patterns of soil redistribution. We conclude that accurate measurement of soil redistribution patterns in a heterogeneous shrub community requires a very large number of samplers and a long period of study and we believe that net soil loss from an area is limited to fine dust emissions.

  8. Spatial variability of soil potassium in sugarcane areas subjected to the application of vinasse

    Directory of Open Access Journals (Sweden)

    LAÉRCIO A. DE CARVALHO

    2014-12-01

    Full Text Available When deposited on land the vinasse can promote improvement in fertility, however, often fertilizer application occurs in areas considered homogeneous, without taking into account the variability of the soil. The objective of this study was to evaluate the effect of vinasse application on potassium content in two classes of soils cultivated with sugarcane, and characterize the spatial variability of soil using geostatistical techniques. In the 2010 and 2011 crop year, soil samples were collected from an experimental grid at 0-0.2 and 0.2-0.4 m depth in three soils cultivated with sugarcane, totaling 90 samplings in each grid, for the determination of pH, calcium (Ca, magnesium (Mg, potassium (K, phosphorus (P, aluminum (Al and potential acidity (H + Al. The data have been submitted to analysis of descriptive statistics and the K attribute was subjected to geostatistical analysis. The coefficient of variation indicated medium and high variability of K for the three soils. The results showed that the spatial dependence of K increased in depth to FRce and decreased to PHlv, indicating that the attribute could have followed the pattern of distribution of clay in depth. The investigation of the spatial variability of K on the surface and subsurface soils provided the definition of management zones with different levels of fertility, which can be organized into sub-areas for a more efficient management of the resources and the environment.

  9. Adsorption properties of subtropical and tropical variable charge soils: Implications from climate change and biochar amendment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ren-Kou; Qafoku, Nikolla; Van Ranst, Eric; Li, Jiu-yu; Jiang, Jun

    2016-01-25

    This review paper attempts to summarize the progress made in research efforts conducted over the last years to study the surface chemical properties of the tropical and subtropical soils, usually called variable charge soils, and the way they response to different management practices. The paper is composed of an introductory section that provides a brief discussion on the surface chemical properties of these soils, and five other review sections. The focus of these sections is on the evolution of surface chemical properties during the development of the variable charge properties (second section), interactions between oppositely charged particles and the resulting effects on the soil properties and especially on soil acidity (third section), the surface effects of low molecular weight organic acids sorbed to mineral surfaces and the chemical behavior of aluminum (fourth section), and the crop straw derived biochar induced changes of the surface chemical properties of these soils (fifth section). A discussion on the effect of climate change variables on the properties of the variable charge soils is included at the end of this review paper (sixth section).

  10. Field Scale Studies on the Spatial Variability of Soil Quality Indicators in Washington State, USA

    Directory of Open Access Journals (Sweden)

    Jeffrey L. Smith

    2011-01-01

    Full Text Available Arable lands are needed for sustainable agricultural systems to support an ever-growing human population. Soil quality needs to be defined to assure that new land brought into crop production is sustainable. To evaluate soil quality, a number of soil attributes will need to be measured, evaluated, and integrated into a soil-quality index using the multivariable indicator kriging (MVIK procedure. This study was conducted to determine the spatial variability and correlation of indicator parameters on a field scale with respect to soil quality and suitability for use with MVIK. The variability of the biological parameters decreased in the order of respiration > enzyme assays and qCO2 > microbial biomass C. The distribution frequency of all parameters except respiration were normal although the spatial distribution across the landscape was highly variable. The biological parameters showed little correlation with each other when all data points were considered; however, when grouped in smaller sections, the correlations were more consistent with observed patterns across the field. To accurately assess soil quality, and arable land use, consideration of spatial and temporal variability, soil conditions, and other controlling factors must be taken into account.

  11. Spatial Variability of Soil Properties in Archeological Dark Earth Sites under Cacao Cultivation

    Directory of Open Access Journals (Sweden)

    Douglas Marcelo Pinheiro da Silva

    2016-01-01

    Full Text Available ABSTRACT Soils with an A horizon formed by human activity, an anthropogenic A horizon, are found in the Amazon Region. Few studies have examined the spatial distribution of the properties of these soils. We mapped the spatial variability of some soil properties in an area of Archaeological Dark Earth (ADE in the Brazilian Amazon. A sampling grid was defined over an area of 42 × 88 m under cacao cultivation in which sampling points were established at a spacing of 6 × 8 m, for a total of 88 points. Samples were collected from the 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m depth layers. Soil texture, aggregate stability, and organic carbon (OC analyses were performed on disturbed soil samples. Undisturbed samples were used to determine soil macroporosity (Macro, microporosity (Micro, total porosity (TP, and soil resistance to penetration (RP. The results were analyzed by descriptive statistic, Pearson correlation (p<0.01, and geostatistics. Soil bulk density, total pore volume, and geometric mean diameter are dependent on the total amount of OC in the ADE area. Increased soil bulk density and RP are proportional to a decrease in OC content and lower Micro and TP. Moreover, soil resistance to penetration is influenced by soil water and clay content with depth.

  12. Discrimination between long-range transport and local pollution sources and precise delineation of polluted soil layers using integrated geophysical-geochemical methods.

    Science.gov (United States)

    Magiera, Tadeusz; Szuszkiewisz, Marcin; Szuszkiewicz, Maria; Żogała, Bogdan

    2017-04-01

    The primary goal of this work was to distinguish between soil pollution from long-range and local transport of atmospheric pollutants using soil magnetometry in combination with geochemical analyses and precise delineation of polluted soil layers by using integrated magnetic (surface susceptibility, gradiometric measurement) and other geophysical techniques (conductivity and electrical resistivity tomography). The study area was located in the Izery region of Poland (within the "Black Triangle" region, which is the nickname for one of Europe's most polluted areas, where Germany, Poland and the Czech Republic meet). The study area was located in the Forest Glade where the historical local pollution source (glass factory) was active since and of 18th until the end of 19th century. The magnetic signal here was the combination of long-range transport of magnetic particles, local deposition and anthropogenic layers containing ashes and slags and partly comprising the subsoil of modern soil. Application of the set of different geophysical techniques enabled the precise location of these layers. The effect of the long-range pollution transport was observed on a neighboring hill (Granicznik) of which the western, northwestern and southwestern parts of the slope were exposed to the transport of atmospheric pollutants from the Czech Republic and Germany and Poland. Using soil magnetometry, it was possible to discriminate between long-range transport of atmospheric pollutants and anthropogenic pollution related to the former glasswork located in the Forest Glade. The magnetic susceptibility values (κ) as well as the number of "hot-spots" of volume magnetic susceptibility is significantly larger in the Forest Glade than on the Granicznik Hill where the κ is fact that the western part was subjected mostly to the long-range pollution originating from lignite power plants along the Polish border, while the southeastern part of the hill was shielded by crag and tail formation

  13. Land agroecological quality assessment in conditions of high spatial soil cover variability at the Pereslavskoye Opolye.

    Science.gov (United States)

    Morev, Dmitriy; Vasenev, Ivan

    2015-04-01

    The essential spatial variability is mutual feature for most natural and man-changed soils at the Central region of European territory of Russia. The original spatial heterogeneity of forest soils has been further complicated by a specific land-use history and human impacts. For demand-driven land-use planning and decision making the quantitative analysis and agroecological interpretation of representative soil cover spatial variability is an important and challenging task that receives increasing attention from private companies, governmental and environmental bodies. Pereslavskoye Opolye is traditionally actively used in agriculture due to dominated high-quality cultivated soddy-podzoluvisols which are relatively reached in organic matter (especially for conditions of the North part at the European territory of Russia). However, the soil cover patterns are often very complicated even within the field that significantly influences on crop yield variability and have to be considered in farming system development and land agroecological quality evaluation. The detailed investigations of soil regimes and mapping of the winter rye yield have been carried in conditions of two representative fields with slopes sharply contrasted both in aspects and degrees. Rye biological productivity and weed infestation have been measured in elementary plots of 0.25 m2 with the following analysis the quality of the yield. In the same plot soil temperature and moisture have been measured by portable devices. Soil sampling was provided from three upper layers by drilling. The results of ray yield detailed mapping shown high differences both in average values and within-field variability on different slopes. In case of low-gradient slope (field 1) there is variability of ray yield from 39.4 to 44.8 dt/ha. In case of expressed slope (field 2) the same species of winter rye grown with the same technology has essentially lower yield and within-field variability from 20 to 29.6 dt/ha. The

  14. Characteristics and controls of variability in soil moisture and groundwater in a headwater catchment

    Science.gov (United States)

    McMillan, H. K.; Srinivasan, M. S.

    2015-04-01

    Hydrological processes, including runoff generation, depend on the distribution of water in a catchment, which varies in space and time. This paper presents experimental results from a headwater research catchment in New Zealand, where we made distributed measurements of streamflow, soil moisture and groundwater levels, sampling across a range of aspects, hillslope positions, distances from stream and depths. Our aim was to assess the controls, types and implications of spatial and temporal variability in soil moisture and groundwater tables. We found that temporal variability in soil moisture and water table is strongly controlled by the seasonal cycle in potential evapotranspiration, for both the mean and extremes of their distributions. Groundwater is a larger water storage component than soil moisture, and this general difference increases even more with increasing catchment wetness. The spatial standard deviation of both soil moisture and groundwater is larger in winter than in summer. It peaks during rainfall events due to partial saturation of the catchment, and also rises in spring as different locations dry out at different rates. The most important controls on spatial variability in storage are aspect and distance from the stream. South-facing and near-stream locations have higher water tables and showed soil moisture responses for more events. Typical hydrological models do not explicitly account for aspect, but our results suggest that it is an important factor in hillslope runoff generation. Co-measurement of soil moisture and water table level allowed us to identify relationships between the two. Locations where water tables peaked closer to the surface had consistently wetter soils and higher water tables. These wetter sites were the same across seasons. However, patterns of strong soil moisture responses to summer storms did not correspond to the wetter sites. Total catchment spatial variability is composed of multiple variability sources, and the

  15. Spatial variability of soil moisture regimes at different scales: implications in the context of precision agriculture.

    Science.gov (United States)

    Voltz, M

    1997-01-01

    Precision agriculture is based on the concept of soil-specific management, which aims to adapt management within a field according to specific site conditions in order to maximize production and minimize environmental damage. This paper examines how the nature and sources of variation in soil moisture regimes affect our ability to simulate soil water behaviour within a field with adequate precision in order to advise optimal soil-specific management. Field examples of variation in soil moisture regimes are described to illustrate the difficulties involved. A discussion identifies three main points. First, it is recognized that the current modelling approaches to soil moisture regimes do not sufficiently account for local heterogeneities in soil and crop characteristics such as soil morphology and rooting patterns. Second, the estimation of within-field variation of soil hydraulic properties is difficult because of large short-range variation of the properties and general lack of observed data; one way to overcome this problem is to seek new measurement techniques or to find easy-to-measure auxiliary variables spatially correlated to the variables of interest. Last, as pollution impacts often become noticeable to society at scales larger than the scale of agricultural management, hydrological modelling can serve for linking both scales and advising agricultural practices that minimize undesirable pollution effects.

  16. Spatial variability of the properties of marsh soils and their impact on vegetation

    Science.gov (United States)

    Sidorova, V. A.; Svyatova, E. N.; Tseits, M. A.

    2015-03-01

    Spatial variability of the properties of soils and the character of vegetation was studied on seacoasts of the Velikii Island in the Kandalaksha Bay of the White Sea. It was found that the chemical and physicochemical properties of marsh soils (Tidalic Fluvisols) are largely dictated by the distance from the sea and elevation of the sampling point above sea level. The spatial distribution of the soil properties is described by a quadratic trend surface. With an increase in the distance from the sea, the concentration of ions in the soil solution decreases, and the organic carbon content and soil acidity become higher. The spatial dependence of the degree of variability in the soil properties is moderate. Regular changes in the soil properties along the sea-land gradient are accompanied by the presence of specific spatial patterns related to the system of temporary water streams, huge boulders, and beached heaps of sea algae and wood debris. The cluster analysis made it possible to distinguish between five soil classes corresponding to the following plant communities: barren surface (no permanent vegetation), clayey-sandy littoral with sparse halophytes, marsh with large rhizomatous grasses, and grass-forb-bunchberry vegetation of forest margins. The subdivision into classes is especially distinct with respect to the concentration of chloride ions. The following groups of factors affect the distribution of vegetation: the composition of the soil solution, the height above sea level, the pH of water suspensions, and the humus content.

  17. Geochemical features and sources of hydrocarbons and fatty acids in soils from the McMurdo Dry Valleys in the Antarctic

    Science.gov (United States)

    Matsumoto, Genki I.; Honda, Eisuke; Sonoda, Kazuhiko; Yamamoto, Shuichi; Takemura, Tetsuo

    2010-08-01

    We studied the geochemical features and compound-specific (CS)-δ 13C of hydrocarbons and fatty acids in soil samples from the McMurdo Dry Valleys in the Antarctic to elucidate their source organisms and characteristics of their environments. Total organic carbon contents in soil samples were extremely low reflecting extremely harsh environments for organisms. Normal-alkanes ranging in carbon chain length from n-C 14 to n-C 38 with the predominance of odd-carbon numbers were found, together with n-alkenes ( n-C 23:1 to n-C 27:1). Normal-alkanoic acids ranging in carbon chain length from n-C 10 to n-C 30 with the predominance of even-carbon numbers were detected in the samples, along with small amounts of branched ( iso and anteiso) and n-alkenoic acids. CS-δ 13C values of long-chain n-alkanes ( n-C 20 to n-C 29) ranged from -30.4 to -26.6‰. CS-δ 13C values of n-alkanoic acids with short-chain carbon numbers ( n-C 14 to n-C 19) ranging from -27.7 to -21.7‰ were much higher than those of long-chain carbon numbers ( n-C 20 to n-C 30, -32.5 to -25.3‰). The geochemical features and CS-δ 13C values of long-chain n-alkanes and n-alkanoic acids revealed that they are originated from lichen and/or vascular plant debris from the pre- and inter-glacial periods in this region, whereas short-chain n-alkanoic acids are come from microalgae and cyanobacterial debris. CS-δ 13C values suggest that they are derived from gymnosperms and/or C 4 plants in the cold and dry environments of the pre- and inter-glacial periods of the McMurdo Dry Valleys region.

  18. Exploring the spatial variability of soil properties in an Alfisol Catena

    Energy Technology Data Exchange (ETDEWEB)

    Rosemary, F.; Vitharana, U. W. A.; Indraratne, S. P.; Weerasooriya, R.; Mishra, U.

    2016-11-10

    Detailed digital soil maps showing the spatial heterogeneity of soil properties consistent with the landscape are required for site-specific management of plant nutrients, land use planning and process-based environmental modeling. We characterized the short-scale spatial heterogeneity of soil properties in an Alfisol catena in a tropical landscape of Sri Lanka. The impact of different land-uses (paddy, vegetable and un-cultivated) was examined to assess the impact of anthropogenic activities on the variability of soil properties at the catenary level. Conditioned Latin hypercube sampling was used to collect 58 geo-referenced topsoil samples (0–30 cm) from the study area. Soil samples were analyzed for pH, electrical conductivity (EC), organic carbon (OC), cation exchange capacity (CEC) and texture. The spatial correlation between soil properties was analyzed by computing crossvariograms and subsequent fitting of theoretical model. Spatial distribution maps were developed using ordinary kriging. The range of soil properties, pH: 4.3–7.9; EC: 0.01–0.18 dS m–1 ; OC: 0.1–1.37%; CEC: 0.44– 11.51 cmol (+) kg–1 ; clay: 1.5–25% and sand: 59.1–84.4% and their coefficient of variations indicated a large variability in the study area. Electrical conductivity and pH showed a strong spatial correlation which was reflected by the cross-variogram close to the hull of the perfect correlation. Moreover, cross-variograms calculated for EC and Clay, CEC and OC, CEC and clay and CEC and pH indicated weak positive spatial correlation between these properties. Relative nugget effect (RNE) calculated from variograms showed strongly structured spatial variability for pH, EC and sand content (RNE < 25%) while CEC, organic carbon and clay content showed moderately structured spatial variability (25% < RNE < 75%). Spatial dependencies for examined soil properties ranged from 48 to 984 m. The mixed effects model fitting followed by Tukey's post

  19. Can we quantify the variability of soil moisture across scales using Electromagnetic Induction ?

    Science.gov (United States)

    Robinet, Jérémy; von Hebel, Christian; van der Kruk, Jan; Govers, Gerard; Vanderborght, Jan

    2017-04-01

    Soil moisture is a key variable in many natural processes. Therefore, technological and methodological advancements are of primary importance to provide accurate measurements of spatial and temporal variability of soil moisture. In that context, ElectroMagnetic Induction (EMI) instruments are often cited as a hydrogeophysical method with a large potential, through the measurement of the soil apparent electrical conductivity (ECa). To our knowledge, no studies have evaluated the potential of EMI to characterize variability of soil moisture on both agricultural and forested land covers in a (sub-) tropical environment. These differences in land use could be critical as differences in temperature, transpiration and root water uptake can have significant effect, notably on the electrical conductivity of the pore water. In this study, we used an EMI instrument to carry out a first assessment of the impact of deforestation and agriculture on soil moisture in a subtropical region in the south of Brazil. We selected slopes of different topographies (gentle vs. steep) and contrasting land uses (natural forest vs. agriculture) within two nearby catchments. At selected locations on the slopes, we measured simultaneously ECa using EMI and a depth-weighted average of the soil moisture using TDR probes installed within soil pits. We found that the temporal variability of the soil moisture could not be measured accurately with EMI, probably because of important temporal variations of the pore water electrical conductivity and the relatively small temporal variations in soil moisture content. However, we found that its spatial variability could be effectively quantified using a non-linear relationship, for both intra- and inter-slopes variations. Within slopes, the ECa could explained between 67 and 90% of the variability of the soil moisture, while a single non-linear model for all the slopes could explain 55% of the soil moisture variability. We eventually showed that combining

  20. Variability of the soil-to-plant radiocaesium transfer factor for Japanese soils predicted with soil and plant properties.

    Science.gov (United States)

    Uematsu, Shinichiro; Vandenhove, Hildegarde; Sweeck, Lieve; Van Hees, May; Wannijn, Jean; Smolders, Erik

    2016-03-01

    Food chain contamination with radiocaesium (RCs) in the aftermath of the Fukushima accident calls for an analysis of the specific factors that control the RCs transfer. Here, soil-to-plant transfer factors (TF) of RCs for grass were predicted from the potassium concentration in soil solution (mK) and the Radiocaesium Interception Potential (RIP) of the soil using existing mechanistic models. The mK and RIP were (a) either measured for 37 topsoils collected from the Fukushima accident affected area or (b) predicted from the soil clay content and the soil exchangeable potassium content using the models that had been calibrated for European soils. An average ammonium concentration was used throughout in the prediction. The measured RIP ranged 14-fold and measured mK varied 37-fold among the soils. The measured RIP was lower than the RIP predicted from the soil clay content likely due to the lower content of weathered micas in the clay fraction of Japanese soils. Also the measured mK was lower than that predicted. As a result, the predicted TFs relying on the measured RIP and mK were, on average, about 22-fold larger than the TFs predicted using the European calibrated models. The geometric mean of the measured TFs for grass in the affected area (N = 82) was in the middle of both. The TFs were poorly related to soil classification classes, likely because soil fertility (mK) was obscuring the effects of the soil classification related to the soil mineralogy (RIP). This study suggests that, on average, Japanese soils are more vulnerable than European soils at equal soil clay and exchangeable K content. The affected regions will be targeted for refined model validation.

  1. Spatial variability of soil structure and its impact on transport processes and some associated land qualities.

    NARCIS (Netherlands)

    Finke, P.A.

    1992-01-01

    This thesis treats the impact of soil spatial variability on spatial variability of simulated land qualities. A sequence of procedures that were done to determine this impact is described in chapters 2 and 3. The subchapters correspond to seven manuscripts that either have appeared in or have been s

  2. Determinants of spatial variability of methane emissions from wet grasslands on peat soil

    NARCIS (Netherlands)

    Pol-Van Dasselaar, van den A.; Beusichem, van M.L.; Oenema, O.

    1999-01-01

    Methane (CH4) emissions from soils, representing the consequence of CH4 production, CH4 consumption and CH4 transport, are poorly characterised and show a large spatial variability. This study aimed to assess the determinants of field-scale spatial variability of CH4 emissions from wet grasslands on

  3. Temporal and spatial variability of soil hydraulic properties with implications on soil moisture simulations and irrigation scheduling

    Science.gov (United States)

    Feki, Mouna; Ravazzani, Giovanni; Mancini, Marco

    2017-04-01

    The increase in consumption of water resources, combined with climate change impacts, calls for new sources of water supply and/or different managements of available resources in agriculture. One way to increase the quality and quantity of agricultural production is using modern technology to make farms more "intelligent", the so-called "precision agriculture" also known as 'smart farming'. To this aim hydrological models play crucial role for their ability to simulate water movement from soil surface to groundwater and to predict onset of stress condition. However, optimal use of mathematical models requires intensive, time consuming and expensive collection of soil related parameters. Typically, soils to be characterized, exhibit large variations in space and time as well during the cropping cycle, due to biological processes and agricultural management practices: tillage, irrigation, fertilization and harvest. Soil properties are subjected to diverse physical and chemical changes that lead to a non-stability in terms of water and chemical movements within the soil and to the groundwater as well. The aim of this study is to assess the variability of soil hydraulic properties over a cropping cycle. The study site is a surface irrigated Maize field located in Secugnago (45◦13'31.70" N, 9 ◦36'26.82 E), in Northern Italy-Lombardy region. The field belongs to the Consortium Muzza Bassa Lodigiana, within which meteorological data together with soil moisture were monitored during the cropping season of 2015. To investigate soil properties variations, both measurements in the field and laboratory tests on both undisturbed and disturbed collected samples were performed. Soil samples were taken from different locations within the study area and at different depths (surface, 20cm and 40cm) at the beginning and in the middle of the cropping cycle and after the harvest. During three measuring campaigns, for each soil samples several parameters were monitored (Organic

  4. Iron speciation in soft-water lakes and soils as determined by EXAFS spectroscopy and geochemical modelling

    Science.gov (United States)

    Sjöstedt, Carin; Persson, Ingmar; Hesterberg, Dean; Kleja, Dan Berggren; Borg, Hans; Gustafsson, Jon Petter

    2013-03-01

    Complexation of iron by organic matter can potentially compete with toxic metals for binding sites. Iron(III) forms both monomeric and di/trimeric complexes with fulvic and humic acids, but the nature and extent of complexation with natural organic matter samples from soft-water lakes has not been extensively studied. The aim of this study was to determine the coordination of iron in complexes with organic matter in two soft-water lakes and in the surrounding Oe soil horizons. Iron K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was performed on particles and large colloids (>0.45 μm) collected by in-line pre-filtration, and on smaller colloids isolated both on an AGMP-1 anion-exchange column and by concentration using 1000 Da ultrafiltration. The results showed that iron(III) was mainly present in monomeric complexes with organic matter, both in the lake water smaller colloids and in the soil samples. Evidence for iron(III) (hydr)oxides was found for the lake particles, in the ultrafiltration retentates, and in some of the soils. Overall, the results suggest that complexation of iron(III) to organic matter prevents hydrolysis into polymeric forms. Strong complexation of iron(III) would lead to competition with other metals for organic-matter binding sites.

  5. Climatic Variability in Davis Sea Sector (east Antarctica) Over the Past 250 Years Based on the 105 KM Ice Core Geochemical Data

    Science.gov (United States)

    Vladimirova, Diana; Ekaykin, Alexey

    2014-05-01

    In this study we present the air temperature and snow accumulation rate reconstruction in the Davis sea sector of East Antarctica over the past 250 years based on the geochemical investigations of the ice core from 105 km borehole (105 km inland from Mirny Station) drilled in 1988. The core was dated by the counting of the annual layers in the stable water isotope content (dD and d18O) profile and using the absolute date marker (Tambora volcano layer). The accumulation values were deduced from the thickness of the layers multiplied by the core density. The isotope content was transformed into the air temperature by comparing to the instrumental meteorological data from Mirny station. The reconstructed temperature series demonstrates a 0.5°C warming over the last 250 years. At the same time, snow accumulation rate was decreasing at least since the middle of the XIXth century. The climatic characteristics demonstrate cyclic variability with the periods of 6, 9, 19, 32 and about 120 years. Interestingly, in frames of 19-year cycle the temperature and isotope content are negatively related, which could be explained by a zonal shift of the moisture source area. Based on the data of the sodium concentration and "deuterium excess" values in the ice core, we assumed an increased sea ice extent in the XIXth century comparing to the present day.

  6. Factorial kriging and stepwise regression approach to identify environmental factors influencing spatial multi-scale variability of heavy metals in soils.

    Science.gov (United States)

    Lv, Jianshu; Liu, Yang; Zhang, Zulu; Dai, Jierui

    2013-10-15

    The knowledge about spatial variations of heavy metals in soils and their relationships with environmental factors is important for human impact assessment and soil management. Surface soils from Rizhao city, Eastern China with rapid urbanization and industrialization were analyzed for six key heavy metals and characterized by parent material and land use using GIS-based data. Factorial kriging analysis and stepwise multiple regression were applied to examine the scale-dependent relationships among heavy metals and to identify environmental factors affecting spatial variability at each spatial scale. Linear model of coregionalization fitting showed that spatial multi-scale variation of heavy metals in soils consisted of nugget effect, an exponential structure with the range of 12 km (short-range scale), as well as a spherical structure with the range of 36 km (long-range scale). The short-range variation of Cd, Pb and Zn were controlled by land use, with higher values in urban areas as well as cultivated land in mountain area, and were related to human influence; while parent material dominated the long structure variations of these elements. Spatial variations of Cr and Ni were associated with natural geochemical sources at short- and long-range scales. At both two scales, Hg dominated by land use, corresponded well to spatial distributions of urban areas, and was attributed to anthropic emissions and atmosphere deposition.

  7. Investigation of the reduction in uncertainty due to soil variability when conditioning a random field using Kriging

    NARCIS (Netherlands)

    Lloret Cabot, M.; Hicks, M.A.; Van den Eijnden, A.P.

    2012-01-01

    Spatial variability of soil properties is inherent in soil deposits, whether as a result of natural geological processes or engineering construction. It is therefore important to account for soil variability in geotechnical design in order to represent more realistically a soil’s in situ state. This

  8. Field potential soil variability index to identify precision agriculture opportunity

    Science.gov (United States)

    Precision agriculture (PA) technologies used for identifying and managing within-field variability are not widely used despite decades of advancement. Technological innovations in agronomic tools, such as canopy reflectance or electrical conductivity sensors, have created opportunities to achieve a ...

  9. TAPIR--Finnish national geochemical baseline database.

    Science.gov (United States)

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  10. Use of the Regularities of Within-Field Variability of Arable Soil Fertility in Precision Agrotechnologies

    Directory of Open Access Journals (Sweden)

    Afanasyev Rafail Aleksandrovich

    2015-04-01

    Full Text Available The paper states the regularities of the within-field variation of soil fertility which are important for variable rate fertilizer application under conditions of precision agrotechnologies including the technologies which limit the agroeconomic efficiency. As it is well known, the usual (traditional fertilizer practice stipulates their application taking into account average indices of soil fertility: mobile plant food elements (N, P, K etc. content in the plow layer. At the same time, one part of the plants gets excess of mineral nutrition, and the other part – its deficiency. That results in shortage of agricultural products, their deterioration and also the pollution of the environment and the soil with the excesses of agrochemicals in overfertilized plots. In the last decades traditional technologies give place to high-precision agrotechnologies with differentiated fertilizer application taking into account within-field heterogeneity of soil fertility. There are several constraints for widespread adoption of high-precision agrotechnologies including the underestimation of the character of within-field variability of soil quality. Our investigations reveal eight regularities of the within-field variation of agrochemical indices, which characterize soil fertility in arable soils. These regularities would allow to more seriously estimate the efficiency of variable rate fertilizer application under conditions of precision agrotechnologies.

  11. A study of soil moisture variability for landmine detection by the neutron technique

    Directory of Open Access Journals (Sweden)

    Avdić Senada

    2007-01-01

    Full Text Available This paper is focused on the space and temporal variability of soil moisture experimental data acquired at a few locations near landmine fields in the Tuzla Canton, as well as on the quantification of the statistical nature of soil moisture data on a small spatial scale. Measurements of soil water content at the surface were performed by an electro-magnetic sensor over 1 25, and 100 m2 grids, at intervals of 0.2, 0.5, and 1 m, respectively. The sampling of soil moisture at different spatial resolutions and over different grid sizes has been investigated in order to achieve the quantification of the statistical nature of soil moisture distribution. The statistical characterization of spatial variability was performed through variogram and correlogram analysis of measurement results. The temporal variability of the said samples was examined over a two-season period. For both sampling periods, the spatial correlation length is about 1 to 2 m, respectively, or less. Thus, sampling should be done on a larger spatial scale, in order to capture the variability of the investigated areas. Since the characteristics of many landmine sensors depend on soil moisture, the results of this study could form a useful data base for multisensor landmine detection systems with a promising performance.

  12. Geochemical behaviour of palladium in soils and Pd/PdO model substances in the presence of the organic complexing agents L-methionine and citric acid.

    Science.gov (United States)

    Zereini, Fathi; Wiseman, Clare L S; Vang, My; Albers, Peter; Schneider, Wolfgang; Schindl, Roland; Leopold, Kerstin

    2016-01-01

    Risk assessments of platinum group metal (PGE) emissions, notably those of platinum (Pt), palladium (Pd) and rhodium (Rh), have been mostly based on data regarding the metallic forms used in vehicular exhaust converters, known to be virtually biologically inert and immobile. To adequately assess the potential impacts of PGE, however, data on the chemical behaviour of these metals under ambient conditions post-emission is needed. Complexing agents with a high affinity for metals in the environment are hypothesized to contribute to an increased bioaccessibility of PGE. The purpose of this study is to examine the modulating effects of the organic complexing agents, L-methionine and citric acid, on the geochemical behavior of Pd in soils and model substances (Pd black and PdO). Batch experimental tests were conducted with soils and model substances to examine the impacts of the concentration of complexing agents, pH and length of extraction period on Pd solubility and its chemical transformation. Particle surface chemistry was examined using X-ray photoelectron spectroscopy (XPS) on samples treated with solutions under various conditions, including low and high O2 levels. Pd was observed to be more soluble in the presence of organic complexing agents, compared to Pt and Rh. Pd in soils was more readily solubilized with organic complexing agents compared to the model substances. After 7 days of extraction, L-methionine (0.1 M) treated soil and Pd black samples, for instance, had mean soluble Pd fractions of 12.4 ± 5.9% and 0.554 ± 0.024%, respectively. Surface chemistry analyses (XPS) confirmed the oxidation of metallic Pd surfaces when treated with organic complexing agents. The type of organic complexing agent used for experimental purposes was observed to be the most important factor influencing solubility, followed by solution pH and time of extraction. The results demonstrate that metallic Pd can be transformed into more bioaccessible species in the presence of

  13. Quantifying soil and critical zone variability in a forested catchment through digital soil mapping

    Science.gov (United States)

    Quantifying catchment scale soil property variation yields insights into critical zone evolution and function. The objective of this study was to quantify and predict the spatial distribution of soil properties within a high elevation forested catchment in southern AZ, USA using a combined set of di...

  14. Plant trait diversity buffers variability in denitrification potential over changes in season and soil conditions.

    Directory of Open Access Journals (Sweden)

    Bonnie M McGill

    Full Text Available BACKGROUND: Denitrification is an important ecosystem service that removes nitrogen (N from N-polluted watersheds, buffering soil, stream, and river water quality from excess N by returning N to the atmosphere before it reaches lakes or oceans and leads to eutrophication. The denitrification enzyme activity (DEA assay is widely used for measuring denitrification potential. Because DEA is a function of enzyme levels in soils, most ecologists studying denitrification have assumed that DEA is less sensitive to ambient levels of nitrate (NO(3(- and soil carbon and thus, less variable over time than field measurements. In addition, plant diversity has been shown to have strong effects on microbial communities and belowground processes and could potentially alter the functional capacity of denitrifiers. Here, we examined three questions: (1 Does DEA vary through the growing season? (2 If so, can we predict DEA variability with environmental variables? (3 Does plant functional diversity affect DEA variability? METHODOLOGY/PRINCIPAL FINDINGS: The study site is a restored wetland in North Carolina, US with native wetland herbs planted in monocultures or mixes of four or eight species. We found that denitrification potentials for soils collected in July 2006 were significantly greater than for soils collected in May and late August 2006 (p<0.0001. Similarly, microbial biomass standardized DEA rates were significantly greater in July than May and August (p<0.0001. Of the soil variables measured--soil moisture, organic matter, total inorganic nitrogen, and microbial biomass--none consistently explained the pattern observed in DEA through time. There was no significant relationship between DEA and plant species richness or functional diversity. However, the seasonal variance in microbial biomass standardized DEA rates was significantly inversely related to plant species functional diversity (p<0.01. CONCLUSIONS/SIGNIFICANCE: These findings suggest that

  15. Geochemical and isotopic variability in lavas from the eastern Trans-Mexican Volcanic Belt: Slab detachment in a subduction zone with varying dip

    Science.gov (United States)

    Orozco-Esquivel, Teresa; Petrone, Chiara M.; Ferrari, Luca; Tagami, Takahiro; Manetti, Piero

    2007-01-01

    Strong compositional variations are observed in the late-Miocene to Quaternary volcanic rocks of the eastern Trans-Mexican Volcanic Belt. Geochemical and isotopic analyses of samples well constrained in age indicate an abrupt change in magma composition in the late-Miocene (˜ 7.5 Ma), when calc-alkaline, subduction-related magmatism was replaced by mafic, alkaline, OIB-like volcanism. Afterwards, volcanism migrated toward the trench and the erupted lavas showed increasing contributions of subduction components reflected in higher Th/Nb, La/Sm(n), Ba/Nb, and Ba/Th ratios. Lavas from volcanic fields located closer to the trench show clearer, although strongly variable, arc signatures as well as evidence of subducted sediment contributions. Farther from the trench, only lavas emplaced in late-Pliocene time appear to be slightly modified by subduction components, whereas the youngest Quaternary lavas can be regarded as intraplate lavas modified by crustal assimilation. The sudden change in magma composition in the late-Miocene is related to detachment of the subducting slab, which allowed the infiltration of enriched asthenospheric mantle into the mantle wedge. After detachment, the subducting plate started to increase its dip because of the loss of slab pull. This caused (1) the migration of the arc toward the trench, (2) convection of enriched asthenosphere into the mantle wedge, and (3) an increasing contribution of slab components to the melts, in a process that resulted in a highly heterogeneous source mantle. The variable contribution of subduction-related components to the magmas is controlled by the heterogeneous character of the source, the depth of the subducting plate, and the previous magmatic history of the areas.

  16. Brine Migration from a Flooded Salt Mine in the Genesee Valley, Livingston County, New York: Geochemical Modeling and Simulation of Variable-Density Flow

    Science.gov (United States)

    Yager, Richard M.; Misut, Paul E.; Langevin, Christian D.; Parkhurst, David L.

    2009-01-01

    The Retsof salt mine in upstate New York was flooded from 1994 to 1996 after two roof collapses created rubble chimneys in overlying bedrock that intersected a confined aquifer in glacial sediments. The mine now contains about 60 billion liters of saturated halite brine that is slowly being displaced as the weight of overlying sediments causes the mine cavity to close, a process that could last several hundred years. Saline water was detected in the confined aquifer in 2002, and a brine-mitigation project that includes pumping followed by onsite desalination was implemented in 2006 to prevent further migration of saline water from the collapse area. A study was conducted by the U.S. Geological Survey using geochemical and variable-density flow modeling to determine sources of salinity in the confined aquifer and to assess (1) processes that control movement and mixing of waters in the collapse area, (2) the effect of pumping on salinity, and (3) the potential for anhydrite dissolution and subsequent land subsidence resulting from mixing of waters induced by pumping. The primary source of salinity in the collapse area is halite brine that was displaced from the flooded mine and transported upward by advection and dispersion through the rubble chimneys and surrounding deformation zone. Geochemical and variable-density modeling indicate that salinity in the upper part of the collapse area is partly derived from inflow of saline water from bedrock fracture zones during water-level recovery (January 1996 through August 2006). The lateral diversion of brine into bedrock fracture zones promoted the upward migration of mine water through mixing with lower density waters. The relative contributions of mine water, bedrock water, and aquifer water to the observed salinity profile within the collapse area are controlled by the rates of flow to and from bedrock fracture zones. Variable-density simulations of water-level recovery indicate that saline water has probably not

  17. Effects of short term bioturbation by common voles on biogeochemical soil variables.

    Directory of Open Access Journals (Sweden)

    Burkhard Wilske

    Full Text Available Bioturbation contributes to soil formation and ecosystem functioning. With respect to the active transport of matter by voles, bioturbation may be considered as a very dynamic process among those shaping soil formation and biogeochemistry. The present study aimed at characterizing and quantifying the effects of bioturbation by voles on soil water relations and carbon and nitrogen stocks. Bioturbation effects were examined based on a field set up in a luvic arenosol comprising of eight 50 × 50 m enclosures with greatly different numbers of common vole (Microtus arvalis L., ca. 35-150 individuals ha-1 mth-1. Eleven key soil variables were analyzed: bulk density, infiltration rate, saturated hydraulic conductivity, water holding capacity, contents of soil organic carbon (SOC and total nitrogen (N, CO2 emission potential, C/N ratio, the stable isotopic signatures of 13C and 15N, and pH. The highest vole densities were hypothesized to cause significant changes in some variables within 21 months. Results showed that land history had still a major influence, as eight key variables displayed an additional or sole influence of topography. However, the δ15N at depths of 10-20 and 20-30 cm decreased and increased with increasing vole numbers, respectively. Also the CO2 emission potential from soil collected at a depth of 15-30 cm decreased and the C/N ratio at 5-10 cm depth narrowed with increasing vole numbers. These variables indicated the first influence of voles on the respective mineralization processes in some soil layers. Tendencies of vole activity homogenizing SOC and N contents across layers were not significant. The results of the other seven key variables did not confirm significant effects of voles. Thus overall, we found mainly a first response of variables that are indicative for changes in biogeochemical dynamics but not yet of those representing changes in pools.

  18. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    Science.gov (United States)

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides.

  19. Unsaturated flow processes in structurally-variable pathways in wildfire-affected soils and ash

    Science.gov (United States)

    Ebel, B. A.

    2016-12-01

    Prediction of flash flood and debris flow generation in wildfire-affected soils and ash hinges on understanding unsaturated flow processes. Water resources issues, such as groundwater recharge, also rely on our ability to quantify subsurface flow. Soil-hydraulic property data provide insight into unsaturated flow processes and timescales. A literature review and synthesis of existing data from the literature for wildfire-affected soils, including ash and unburned soils, facilitated calculating metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and the Green-Ampt wetting front parameter (Ψf) were significantly lower in burned soils compared to unburned soils, while field-saturated hydraulic conductivity (Kfs) was not significantly different. The magnitude and duration of the influence of capillarity was substantially reduced in burned soils, leading to faster ponding times in response to rainfall. Ash had large values of S and Kfs compared to unburned and burned soils but intermediate values of Ψf, suggesting that ash has long ponding times in response to rainfall. The ratio of S2/Kfs was nearly constant ( 100 mm) for unburned soils, but was more variable in burned soils. Post-wildfire changes in this ratio suggested that unburned soils had a balance between gravity and capillarity contributions to infiltration, which may depend on soil organic matter, while burning shifted infiltration more towards gravity contributions by reducing S. Taken together, the changes in post-wildfire soil-hydraulic properties increased the propensity for surface runoff generation and may have enhanced subsurface preferential flow through pathways altered by wildfire.

  20. McMaster Mesonet soil moisture dataset: description and spatio-temporal variability analysis

    Directory of Open Access Journals (Sweden)

    K. C. Kornelsen

    2013-04-01

    Full Text Available This paper introduces and describes the hourly, high-resolution soil moisture dataset continuously recorded by the McMaster Mesonet located in the Hamilton-Halton Watershed in Southern Ontario, Canada. The McMaster Mesonet consists of a network of time domain reflectometer (TDR probes collecting hourly soil moisture data at six depths between 10 cm and 100 cm at nine locations per site, spread across four sites in the 1250 km2 watershed. The sites for the soil moisture arrays are designed to further improve understanding of soil moisture dynamics in a seasonal climate and to capture soil moisture transitions in areas that have different topography, soil and land cover. The McMaster Mesonet soil moisture constitutes a unique database in Canada because of its high spatio-temporal resolution. In order to provide some insight into the dominant processes at the McMaster Mesonet sites, a spatio-temporal and temporal stability analysis were conducted to identify spatio-temporal patterns in the data and to suggest some physical interpretation of soil moisture variability. It was found that the seasonal climate of the Great Lakes Basin causes a transition in soil moisture patterns at seasonal timescales. During winter and early spring months, and at the meadow sites, soil moisture distribution is governed by topographic redistribution, whereas following efflorescence in the spring and summer, soil moisture spatial distribution at the forested site was also controlled by vegetation canopy. Analysis of short-term temporal stability revealed that the relative difference between sites was maintained unless there was significant rainfall (> 20 mm or wet conditions a priori. Following a disturbance in the spatial soil moisture distribution due to wetting, the relative soil moisture pattern re-emerged in 18 to 24 h. Access to the McMaster Mesonet data can be provided by visiting www.hydrology.mcmaster.ca/mesonet.

  1. Spatial Variability of Soil Properties and Rice Yield Along Two Catenas in Southeast China

    Institute of Scientific and Technical Information of China (English)

    B. R(U)TH; B. LENNARTZ

    2008-01-01

    In the light of an increasing demand for staple food, especially rice, in southeast China, investigations on the specific site potential expressed as the relationship between soil and crop yield parameters gain increasing importance. Soil texture and several soil chemical parameters as well as plant properties such as crop height, biomass and grain yield were investigated along two terraced catenas with contrasting soil textures cropped with wet rice. We were aiming at identifying correlative relationships between soil and crop properties. Data were analyzed both statistically and geostatistically on the basis of semivariograms. Statistical analysis indicated a significant influence of the relief position on the spatial distribution of soil texture, total carbon and total nitrogen contents. Significant correlations were found for the catena located in a sandstone area (Catena A) between rice yield and silt as well as total nitrogen content. Corresponding relationships were not detectable for paddy fields that developed from Quaternary clays (Catena B). As suggested by the nugget to sill ratio,spatial variability of soil texture, total carbon and nitrogen was mainly controlled by intrinsic factors, which might be attributed to the erosional transport of fine soil constituents, indicating the importance of the relief position and slope in soil development even in landscapes that are terraced. The crop parameters exhibited short ranges of influence and about one third of their variability was unexplained. Comparable ranges of selected crop and soil parameters, found only for Catena A, are indicative of close spatial interactions between rice yield and soil features. Our findings show that especially in sandstone-dominated areas, a site-specific management can contribute to an environmentally safe rice production increase.

  2. Interaction Between Charge Characteristics and Cu2+ Adsorption-Desorption of Soils with Variable or Permanent Charge

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Charge characteristics and Cu2+ adsorption-desorption of soils with variable charge (latosol) and per-manent charge (brown soil) and the relationship between them were studied by means of back-titration andadsorption equilibrium respectively. The amount of variable negative charge was much less in variable-chargesoil than in permanent-charge soil and increased with the pH in the system, but the opposite trend occurredin the points of zero charge (PZCs). The amount of Cu2+ ions sorbed by permanent-charge soil was morethan that by variable-charge soil and increased with the increase of Cu2+ concentration within a certainrange in the equilibrium solution. The amount of Cu2+ ions desorbed with KCl from permanent-chargesoil was more than that from variable-charge soil, but the amount of Cu2+ ions desorbed with de-ionizedwater from permanent-charge soil was extremely low whereas there was still a certain amount of desorptionfrom variable-charge soil. The increase of PZC of soils with variable or permanent charge varied with theincrement of Cu2+ ions added. When the same amount of Cu2+ ions was added, the increments of PZC andvariable negative surface charge of permanent-charge soil were different from those of variable-charge soil.

  3. Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines

    DEFF Research Database (Denmark)

    Kendrick, Joseph A.; Ribbons, Relena Rose; Classen, Aimee Taylor

    2015-01-01

    (richness and abundance) of ants increases rapidly as T. canadensis is lost from the stands. Because ants live and forage at the litter-soil interface, we hypothesized that environmental changes caused by hemlock loss (e.g., increased light and warmth at the forest floor, increased soil pH) and shifts...... in ant species composition would interact to alter soil ecosystem variables. In the Harvard Forest Hemlock Removal Experiment (HF-HeRE), established in 2003, T. canadensis in large plots were killed in place or logged and removed to mimic adelgid infestation or salvage harvesting, respectively. In 2006......, we built ant exclosure subplots within all of the canopy manipulation plots to examine direct and interactive effects of canopy change and ant assemblage composition on soil and litter variables. Throughout HF-HeRE, T. canadensis was colonized by the adelgid in 2009, and the infested trees are now...

  4. Neural Network Ensemble Residual Kriging Application for Spatial Variability of Soil Properties

    Institute of Scientific and Technical Information of China (English)

    SHEN Zhang-Quan; SHI Jie-Bin; WANG Ke; KONG Fan-Sheng; J. S. BAILEY

    2004-01-01

    High quality, agricultural nutrient distribution maps are necessary for precision management, but depend on initial soil sample analyses and interpolation techniques. To examine the methodologies for and explore the capability of interpolating soil properties based on neural network ensemble residual kriging, a silage field at Hayes, Northern Ireland, UK, was selected for this study with all samples being split into independent training and validation data sets. The training data set, comprised of five soil properties: soil pH, soil available P, soil available K, soil available Mg and soil available S,was modeled for spatial variability using 1) neural network ensemble residual kriging, 2) neural network ensemble and 3) kriging with their accuracies being estimated by means of the validation data sets. Ordinary kriging of the residuals provided accurate local estimates, while final estimates were produced as a sum of the artificial neural network (ANN)ensemble estimates and the ordinary kriging estimates of the residuals. Compared to kriging and neural network ensemble,the neural network ensemble residual kriging achieved better or similar accuracy for predicting and estimating contour maps. Thus, the results demonstrated that ANN ensemble residual kriging was an efficient alternative to the conventional geo-statistical models that were usually used for interpolation of a data set in the soil science area.

  5. Environmental controls on the spatial variability of soil water dynamics in a small watershed

    Science.gov (United States)

    Hu, Wei; Chau, Henry Wai; Qiu, Weiwen; Si, Bingcheng

    2017-08-01

    Soil water content (SWC) in the root zone is controlled by a suite of environmental variables. Complication arises from the cross-correlation between these environmental variables. Therefore, there is still a poor understanding on the controls of root zone SWC dynamics due, in part, to a lack of an appropriate method to untangle the controls. The objective of this study was to reveal the dominant controls of root zone soil water dynamics in a small watershed using an appropriate method based on empirical orthogonal function (EOF). For this purpose, SWC of 0-0.8 m layer in a small watershed on the Chinese Loess Plateau was used. The space-variant temporal anomaly (Rtn) of SWC, which is responsible for the spatial variability of soil water dynamics, was decomposed using the EOF. Results indicated that 86% of the total variations of Rtn were explained by three significant spatial structures (EOFs). Sand content and grass yield dominated the EOF1 of Rtn and elevation and aspect dominated EOF2 and EOF3 of Rtn , respectively. Moreover, their effects on soil water dynamics were time-dependent. The EOF analysis showed that three independent groups of factors (i.e., soil and vegetation dominated earth surface condition, elevation related near surface air humidity, and aspect regulated energy input) may drive the variability in soil water dynamics. Traditional correlation analysis, however, indicated that SWC was greater at higher elevation and sun-facing slopes, which distorted the soil water dynamics controls. Although original SWC-based partial correlation basically supported our findings, the results highly depended on the controlling factors selected. This study implied that Rtn rather than original SWC should be preferred for understanding soil water dynamics controls.

  6. Influence of spatial and temporal variability of subsurface soil moisture and temperature on vapour intrusion

    Science.gov (United States)

    Bekele, Dawit N.; Naidu, Ravi; Chadalavada, Sreenivasulu

    2014-05-01

    A comprehensive field study was conducted at a site contaminated with chlorinated solvents, mainly trichloroethylene (TCE), to investigate the influence of subsurface soil moisture and temperature on vapour intrusion (VI) into built structures. Existing approaches to predict the risk of VI intrusion into buildings assume homogeneous or discrete layers in the vadose zone through which TCE migrates from an underlying source zone. In reality, the subsurface of the majority of contaminated sites will be subject to significant variations in moisture and temperature. Detailed site-specific data were measured contemporaneously to evaluate the impact of spatial and temporal variability of subsurface soil properties on VI exposure assessment. The results revealed that indoor air vapour concentrations would be affected by spatial and temporal variability of subsurface soil moisture and temperature. The monthly monitoring of soil-gas concentrations over a period of one year at a depth of 3 m across the study site demonstrated significant variation in TCE vapour concentrations, which ranged from 480 to 629,308 μg/m3. Soil-gas wells at 1 m depth exhibited high seasonal variability in TCE vapour concentrations with a coefficient of variation 1.02 in comparison with values of 0.88 and 0.74 in 2 m and 3 m wells, respectively. Contour plots of the soil-gas TCE plume during wet and dry seasons showed that the plume moved across the site, hence locations of soil-gas monitoring wells for human risk assessment is a site specific decision. Subsurface soil-gas vapour plume characterisation at the study site demonstrates that assessment for VI is greatly influenced by subsurface soil properties such as temperature and moisture that fluctuate with the seasons of the year.

  7. Adsorption of Cd(II) by two variable-charge soils in the presence of pectin.

    Science.gov (United States)

    Wang, Ru-Hai; Zhu, Xiao-Fang; Qian, Wei; Zhao, Min-Hua; Xu, Ren-Kou; Yu, Yuan-Chun

    2016-07-01

    Batch experiments were conducted to investigate cadmium(II) (Cd(II)) adsorption by two variable-charge soils (an Oxisol and an Ultisol) as influenced by the presence of pectin. When pectin dosage was less than 30 g kg(-1), the increase in Cd(II) adsorption with the increasing dose of pectin was greater than that when the pectin dosage was >30 g kg(-1). Although both Langmuir and Freundlich equations fitted the adsorption isotherms of Cd(II) and electrostatic adsorption data of Cd(II) by the two soils well, the Langmuir equation showed a better fit. The increase in the maximum total adsorption of Cd(II) induced by pectin was almost equal in both the soils, whereas the increase in the maximum electrostatic adsorption of Cd(II) was greater in the Oxisol than in the Ultisol because the former contained greater amounts of free Fe/Al oxides than the latter, which, in turn, led to a greater increase in the negative charge on the Oxisol. Therefore, the presence of pectin induced the increase in Cd(II) adsorption by the variable-charge soils mainly through the electrostatic mechanism. Pectin increased the adsorption of Cd(II) by the variable-charge soils and thus decreased the activity and mobility of Cd(II) in these soils.

  8. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil.

    Science.gov (United States)

    Ceddia, Marcos Bacis; Villela, André Luis Oliveira; Pinheiro, Érika Flávia Machado; Wendroth, Ole

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0-30 and the 0-100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km(2) and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m(-2), respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock.

  9. Adsorption of Chloride,Nitrate and Perchlorate by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    JIGUO-LIANG; KONGXIAO-LING

    1992-01-01

    Two cells consisting of a chloride-selective eloectrode and a nitrate-selective electrode or of a chloride-selectrive electrode and a perchlorate-selective electrode were directly put in the soil suspension to determine the concentration rations Cl-/NO3- or Cl-/ClO4- for studying the adsorption of the three anions by variable charge soils.It was found that all the concentration ration CCl-/CNO3- and CCl-/CClO4- in suspension were smaller than unity when soil samples were in equilibrium with mixed KCl and KNO3 or KCl and KClO4 solutions of equal concentration.The order of the amount of chloride,nitrate and perchlorate adsorbed by variable charge soils was Cl->NO3->ClO4- when the soils adsorbed these anions from the solution containing equal concentrations of Cl-,NO3- and ClO4-.Such factors as the pH of the suspension,the iron oxide content of the soil etc.Could affect the amounts and the ratios of anions adsorbed.The adsorption was chiefly caused by coulombic attraction,but a covalent force between the anion and the metal atom on the surface of soil particles may also be involved,at least for Cl- ions,even for NO3- ions.

  10. Spatial variability of soil nutrient in paddy plantation: Sites FELCRA Seberang Perak

    Science.gov (United States)

    Kamarudin, H.; Adnan, N. A.; Mispan, M. R.; Athirah. A, A.

    2016-06-01

    The conventional methods currently used for rice cultivation in Malaysia are unable to give maximum yield although the yield production of paddy is increasing. This is due to the conversional method being unable to include soil properties as one of their parameters in agriculture management. Soil properties vary spatially in farm scale due to differences in topography, parent material, vegetation or land management and soil characteristics; also plantation productivity varies significantly over small spatial scales. Knowledge of spatial variability in soil fertility is important for site specific nutrient management. Analysis of spatial variability of soil nutrient of nitrogen (N), phosphorus (P) and potassium (K) were conducted in this study with the aid of GIS (i.e ArcGIS) and statistical softwares. In this study different temporal and depths of soil nutrient were extracted on the field and further analysis of N,P,K content were analysed in the chemical laboratory and using spatially technique in GIS sofware. The result indicated that for the Seberang Perak site of 58 hactares area, N and K are met minimum requirements nutrient content as outlines by the MARDI for paddy cultivation. However, P indicated poor condition in the study area; therefore the soil needs further attention and treatment.

  11. An integrated geochemical, geophysical and mineralogical study of river sediments in alpine area and soil samples near steel plant, in Austria

    Science.gov (United States)

    Irfan, M. I.; Meisel, T.

    2012-04-01

    Concentration of nickel and chromium in any part of the ecosystem is important for environmental concerns in particular human health due to the reason that some species of them can cause health problem e.g. dermatitis and cancer. Sediment samples collected form a river Vordernberger Bach (Leoben, Austria) in an alpine region and soil samples collected in an area adjacent to steel production unit in same narrow valley were investigated. In previous studies a correlation between magnetic susceptibility values and concentration of nickel and chromium showed that a magnetic susceptibility meter can be used to point out the contaminated areas as in-situ device. The purpose of the whole study is to understand the real (point or diffuse, anthropogenic or geogenic) sources of contamination of soils, water and river sediments through heavy metal deposition. Unseparated, magnetic and non-magnetic fractions of soil samples were investigated for geochemical and mineralogical aspects with XRF, ICP-MS, EMPA, Multi-Functional Kappabridge (MFK1) and laser ablation coupled with ICP-MS. Mineralogical study of sediment samples for several sampling points with higher Ni and Cr content was performed. Sediment samples were sieved below 1.4 mm and then a concentrate of heavy minerals was prepared in the field through panning. Concentrated heavy minerals were then subjected for heavy liquid separation in the laboratory. Separated magnetic and non-magnetic fractions below 0.71/0.1 mm and density greater than 2.9 g/cm3 were selected for mineralogical investigation. The abundance of typical anthropogenic particles, e.g., spherical, tinder, roasted ores, iron and steel mill slag was observed under the microscope. Magnetite (mostly anthropogenic), maghemite, chromspinel, chromite (type I & II), (Ca,Al)-ferrite, wustite, apatite (anthropogenic), olivine mixed crystals, calcium silicate and spinel (anthropogenic) are found in magnetic fraction. Non-magnetic fractions contain hematite, siderite

  12. High-resolution mapping and spatial variability of soil organic carbon storage of permafrost-affected soils

    Science.gov (United States)

    Siewert, Matthias; Hugelius, Gustaf

    2017-04-01

    Permafrost-affected soils store large amounts of soil organic carbon (SOC). Mapping of this SOC provides a first order spatial input variable for research that relates carbon stored in permafrost regions to carbon cycle dynamics. High-resolution satellite imagery is becoming increasingly available even in circum-polar regions. The presented research highlights findings of high-resolution mapping efforts of SOC from five study areas in the northern circum-polar permafrost region. These study areas are located in Siberia (Kytalyk, Spasskaya Pad /Neleger, Lena delta), Northern Sweden (Abisko) and Northwestern Canada (Herschel Island). Our high spatial resolution analyses show how geomorphology has a strong influence on the distribution of SOC. This is organized at different spatial scales. Periglacial landforms and processes dictate local scale SOC distribution due to patterned ground. Such landforms are non-sorted circles and ice-wedge polygons of different age and scale. Palsas and peat plateaus are formed and can cover larger areas in Sub-Arctic environments. Study areas that have not been affected by Pleistocene glaciation feature ice-rich Yedoma sediments that dominate the local relief through thermokarst formation and create landscape scale macro environments that dictate the distribution of SOC. A general trend indicates higher SOC storage in Arctic tundra soils compared to forested Boreal or Sub-Arctic taiga soils. Yet, due to the shallower active layer depth in the Arctic, much of the SOC may be permanently frozen and thus not be available to ecosystem processes. Significantly more SOC is stored in soils compared to vegetation, indicating that vegetation growth and incorporation of the carbon into the plant phytomass alone will not be able to offset SOC released from permafrost. This contribution also addresses advances in thematic mapping methods and digital soil mapping of SOC in permafrost terrain. In particular machine-learning methods, such as support

  13. Addressing geographic variability in the comparative toxicity potential of copper and nickel in soils.

    Science.gov (United States)

    Owsianiak, Mikołaj; Rosenbaum, Ralph K; Huijbregts, Mark A J; Hauschild, Michael Z

    2013-04-02

    Comparative toxicity potentials (CTP), in life cycle impact assessment also known as characterization factors (CF), of copper (Cu) and nickel (Ni) were calculated for a global set of 760 soils. An accessibility factor (ACF) that takes into account the role of the reactive, solid-phase metal pool in the soil was introduced into the definition of CTP. Geographic differences in fate, accessibility, bioavailability, and terrestrial toxicity were assessed by combining the USEtox characterization model, empirical regression models, and terrestrial biotic ligand models. The median CTPs for Cu and Ni with 95% geographic variability intervals are 1.4 × 10(3) (1.7 × 10(2) to 2.0 × 10(4)) and 1.7 × 10(3) (2.1 × 10(2) to 1.1 × 10(4)) m(3)/kg · day, respectively. The geographic variability of 3.5 orders of magnitude in the CTP of Cu is mainly associated with the variability in soil organic carbon and pH. They largely influence the fate and bioavailability of Cu in soils. In contrast, the geographic variability of 3 orders of magnitude in the CTP of Ni can mainly be explained by differences in pore water concentration of magnesium (Mg(2+)). Mg(2+) competes with Ni(2+) for binding to biotic ligands, influencing the toxicity. Our findings stress the importance of dealing with geographic variability in the calculation of CTPs for terrestrial ecotoxicity of metals.

  14. Spatial variability of soil organic carbon in the forestlands of northeast China

    Institute of Scientific and Technical Information of China (English)

    Ling Liu; Haiyan Wang; Wei Dai; Xiangdong Lei; Xiaojuan Yang; Xu Li

    2014-01-01

    Soil organic carbon (SOC) is an effective indicator of soil fertility and productivity, and it varies spatially and temporally in relation to other soil properties. Spatial variability of SOC in the forestlands of northeast China was characterized using geostatistics. Soil samples at the depths of 0-20 cm, 20-40 cm and 40-60 cm were collected from six-ty-three temporary plots to evaluate SOC concentration and density (SOCD) and other soil properties. We analyzed correlations between SOC and soil properties. Soil organic carbon concentrations were high. The total amount of C stored in soil (0-60 cm) was 16.23 kg·m-2 with the highest SOCD of 7.98 kg×m-2 in topsoil. Soil properties in most cases differed by horizon, suggesting different processes and effects in each horizon. Soil organic carbon had positive relationships with total N, P and K as well as readily available K, but did not show a significant posi-tive correlation with available P. Spatial factors including elevation, slope and aspect affected SOC distribution. Soil organic carbon at 0-60 cm had strong spatial autocorrelation with nugget/sill ratio of 5.7%, and moderate structured dependence was found at 0-20 cm, which indicated the existence of a highly developed spatial structure. Spatial distributions of SOC concentration and SOCD were estimated using regres-sion-kriging, with higher prediction accuracy than ordinary kriging. The fractal dimension of SOC indicated the preferential pattern of SOC dis-tribution, with the greatest spatial heterogeneity and strongest spatial dependence in the northeast-southwest direction.

  15. Spatial Variability of Nutrient Properties in Black Soil of Northeast China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xing-Yi; SUI Yue-Yu; ZHANG Xu-Dong; MENG Kai; S.J.HERBERT

    2007-01-01

    A total of 1400 soil samples from the plow layer (0-20 cm) at an approximate interval of 5 km were collected in the autumn of 2002 over the entire black soil arable crops region to determine the spatial variability of seven variables, such as total organic matter content (OMC), total N, total P, total K, alkali-dissolvable N (AN), available P (AP) and available K (AK), with classical statistics and geostatistical analysis across the entire black soil area in Northeast China. In nonsampled areas ordinary kriging was utilized for interpolation of estimated nutrient determinations. Classical statistics revealed highly significant (P ≤ 0.01) correlations with all seven of the soil properties, except for OMC with AP and total K with AK. In addition, using coefficients of variation, all soil properties, except for total K, were moderately variable. A geostatistical analysis indicated that structural factors, such as parent material, terrain, and water table, were the main causes of the spatial correlations. Strong spatial correlations were noted with OMC, total N, total P, AN, and AP, while they were moderate for total K and AK. The effective spatial autocorrelation of OMC, total N, total P, and AN ranged from 1 037 to 1 353 km, whereas the ranges of total K, AP, and AK were only from 6 to 138 km. The fit of the experimental semi-variograms to the theoretical models indicated that except for AN, kriging could successfully interpolate other six variables. Thus, the geostatistical method used on a large scale could accurately evaluate the spatial variability of most black soil nutrient properties in Northeast China.

  16. Temporal Variability of Soil Respiration in Experimental Tree Plantations in Lowland Costa Rica

    Directory of Open Access Journals (Sweden)

    James W. Raich

    2017-02-01

    Full Text Available The principal objective of this study was to determine if there is consistent temporal variability in soil respiration from different forest plantations in a lowland tropical rainforest environment. Soil respiration was measured regularly over 2004 to 2010 in replicated plantations of 15- to 20-year-old evergreen tropical trees in lowland Costa Rica. Statistically significant but small differences in soil respiration were observed among hours of the day; daytime measurements were suitable for determining mean fluxes in this study. Fluxes varied more substantially among months, with the highest average emissions (5.9 μmol·m−2·s−1 occurring in September and low emissions (3.7 μmol·m−2·s−1 occurring in January. Three of the six tree species had significantly increasing rates of soil respiration across 2004–2010, with fluxes increasing at an average of 0.09 μmol·m−2·s−1 per year: the three other species had no long-term trends. It was hypothesized that there would be a tradeoff between carbon allocation aboveground, to produce new leaves, and belowground, to sustain roots and mycorrhizae, but the relationship between canopy leaf fall—a surrogate for canopy leaf flushing—and soil respiration was significantly positive. The similarities observed among temporal trends across plantation types, and significant relationships between soil respiration, soil water content and soil temperature, suggest that the physical environment largely controlled the temporal variability of soil respiration, but differences in flux magnitude among tree species were substantial and consistent across years.

  17. An integrated crop- and soil-based strategy for variable-rate nitrogen management in corn

    Science.gov (United States)

    Roberts, Darrin F.

    Nitrogen (N) management in cereal crops has been the subject of considerable research and debate for several decades. Historic N management practices have contributed to low nitrogen use efficiency (NUE). Low NUE can be caused by such things as poor synchronization between soil N supply and crop demand, uniform application rates of fertilizer N to spatially variable landscapes, and failure to account for temporally variable influences on soil N supply and crop N need. Active canopy reflectance sensors and management zones (MZ) have been studied separately as possible plant- and soil-based N management tools to increase NUE. Recently, some have suggested that the integration of these two approaches would provide a more robust N management strategy that could more effectively account for soil and plant effects on crop N need. For this reason, the goal of this research was to develop an N application strategy that would account for spatial variability in soil properties and use active canopy reflectance sensors to determine in-season, on-the-go N fertilizer rates, thereby increasing NUE and economic return for producers over current N management practices. To address this overall goal, a series of studies were conducted to better understand active canopy sensor use and explore the possibility of integrating spatial soil data with active canopy sensors. Sensor placement to assess crop N status was first examined. It was found that the greatest reduction in error over sensing each individual row for a hypothetical 24-row applicator was obtained with 2-3 sensors estimating an average chlorophyll index for the entire boom width. Next, use of active sensor-based soil organic matter (OM) estimation was compared to more conventional aerial image-based soil OM estimation. By adjusting regression intercept values for each field, OM could be predicted using either a single sensor or image data layer. The final study consisted of validation of the active sensor algorithm

  18. Integrating Remote Sensing and Proximal Sensors for the Detection of Soil Moisture and Salinity Variability in Coastal Areas

    Institute of Scientific and Technical Information of China (English)

    GUO Yan; SHI Zhou; ZHOU Lian-qing; JIN Xi; TIAN Yan-feng; TENG Hong-fen

    2013-01-01

    Soil moisture and salinity are two crucial coastal saline soil variables, which influence the soil quality and agricultural productivity in the reclaimed coastal region. Accurately characterizing the spatial variability of these soil parameters is critical for the rational development and utilization of tideland resources. In the present study, the spatial variability of soil moisture and salinity in the reclaimed area of Hangzhou gulf, Shangyu City, Zhejiang Province, China, was detected using the data acquired from radar image and the proximal sensor EM38. Soil moisture closely correlates radar scattering coefficient, and a simplified inversion model was built based on a backscattering coefficient extracted from multi-polarization data of ALOS/PALSAR and in situ soil moisture measured by a time domain reflectometer to detect soil moisture variations. The result indicated a higher accuracy of soil moisture inversion by the HH polarization mode than those by the HV mode. Soil salinity is reflected by soil apparent electrical conductivity (ECa). Further, ECa can be rapidly detected by EM38 equipment in situ linked with GPS for characterizing the spatial variability of soil salinity. Based on the strong spatial variability and interactions of soil moisture and salinity, a cokriging interpolation method with auxiliary variable of backscattering coefficient was adopted to map the spatial variability of ECa. When compared with a map of ECa interpolated by the ordinary kriging method, detail was revealed and the accuracy was increased by 15.3%. The results conclude that the integrating active remote sensing and proximal sensors EM38 are effective and acceptable approaches for rapidly and accurately detecting soil moisture and salinity variability in coastal areas, especially in the subtropical coastal zones of China with frequent heavy cloud cover.

  19. Proton Dissociation from Surfaces of Variable Charge Soil and Minerals

    Institute of Scientific and Technical Information of China (English)

    LUYA-HAI; HUANGCHANG-YONG; 等

    1994-01-01

    Experiments on proton dissociation from the surfaces of goethite,amorphous Al oxide.kaolinite and latosol were carried out,showing amphoteric behavior with reacions of proton dissociation-association on the surfaces and buffering capacity in such a sequence as amorphous Al oxide>latosol>kaolinite>goethite.Dissociation constants of surface proton,pKsa are significantly correlated with surface charge density,which has been proved with an elecrochemical model.The intrinsic constants of proton dissociation,Ksa(int),gained by eptrapolation to zero charge conditions of plots of pKsa against σ0,could be used to estimate the acidity strength of variable charge surfaces,The value of pKsa(int) is 8.08 for goethite,1.2 for a morphous Al oxide,6.62 for kaolinite and 5.32 for latosol.

  20. Spatial Variability of Soil Inorganic N in a Mature Oil Palm Plantation in Sabah, Malaysia

    Directory of Open Access Journals (Sweden)

    Abdul R. Anuar

    2008-01-01

    Full Text Available The identification and understanding of soil factors influencing yield variability of oil palm enable their efficient management. Soil samples were therefore collected from a fertilizer response trial on oil palm to study the spatial inorganic N distribution and some selected soil chemical properties as affected by long-term N fertilizer applications. The experiment was conducted on mature oil palms grown on Kumansi family (Typic Paleudults soil in Tawau, Sabah, Malaysia. The soil samples were taken from 2 areas; with and without N treatments for 8 years. They were analyzed for total N, NH4+-N, NO3--N, exchangeable K, and pH. Semivariance analysis was used to characterize the spatial variance of soil NH4+-N and NO3--N while point kriging method was used to illustrate their spatial distributions. Results showed that application of N in the palm circle increased soil NH4+-N above 150 mg kg-1 at 0 to 15 cm depth. In unmanured plot, the NH4+-N contents were similar in the different sites within a palm area although the frond heap area tended to have higher NH4+-N probably due to the N return from the decaying cut fronds. The coefficient of variations for both soil NH4+-N and NO3--N exceeded 30% even within each microsite of palm circle, interrow, frond heaps, and harvesting path. Semivariance analysis showed that the maximum range of soil NH4+-N could be reached at 10 m and 90 m in areas with and without N respectively, indicating that the application of N fertilizer reduced its spatial variability in mature oil palm agroecosystem. The kriged soil map showed localized spots of high NH4+-N content, which corresponded to the palm circles where N fertilizer was applied. Gradual changes in soil fertility were observed in area without N, moving from northern to southern portion of the field. Long-term applications of N caused significant downward movement of NH4+-N and NO3--N to the lower soil depth. They also decreased the soil pH from 4.2 to 3.7, and

  1. Sorption–bioavailability nexus of arsenic and cadmium in variable-charge soils

    Energy Technology Data Exchange (ETDEWEB)

    Bolan, Nanthi, E-mail: Nanthi.Bolan@unisa.edu.au [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA (Australia); CRC for Contamination Assessment and Remediation in the Environment, University of South Australia, Mawson Lakes, SA (Australia); Mahimairaja, Santiago [Department of Environmental Science, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu (India); Kunhikrishnan, Anitha [Chemical Safety Division, Department of Agro-Food Safety, National Academy of Agricultural Science, Suwon-si, Gyeonggi-do 441-707 (Korea, Republic of); Naidu, Ravi [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA (Australia); CRC for Contamination Assessment and Remediation in the Environment, University of South Australia, Mawson Lakes, SA (Australia)

    2013-10-15

    Highlights: ► Demonstrates the nexus between sorption and bioavailability of As and Cd in variable-charge soils. ► Liming variable-charge soils increase negative charge, thereby decreasing Cd bioavailability. ► Ageing of As and Cd increases their immobilization, thereby decreasing bioavailability. ► Phosphate enhances desorption and phytoavailability of As from sheep dip soil. ► Metal(loid)s transfer to food chain can be managed by controlling sorption reactions. -- Abstract: In this work, the nexus between sorption and bioavailability of arsenic (As) and cadmium (Cd) as affected by soil type, soil pH, ageing, and mobilizing agents were examined. The adsorption of As and Cd was examined using a number of allophanic and non-allophanic soils which vary in their charge components. The effect of pH and ageing on the bioavailability of As and Cd was examined using spiked soils in a plant growth experiment. The effect of phosphate (P)-induced mobility of As on its bioavailability was examined using a naturally contaminated sheep dip soil. The results indicated that the adsorption of both As and Cd varied amongst the soils, and the difference in Cd adsorption is attributed to the difference in surface charge. An increase in soil pH increased net negative charge by an average of 45.7 mmol/kg/pH thereby increasing cation (Cd) adsorption; whereas, the effect of pH on anion (As) adsorption was inconsistent. The bioavailability of As and Cd decreased by 3.31- and 2.30-fold, respectively, with ageing which may be attributed to increased immobilization. Phosphate addition increased the mobility and bioavailability of As by 4.34- and 3.35-fold, respectively, in the sheep dip soil. However, the net effect of P on As phytoavailability depends on the extent of P-induced As mobilization in soils and P-induced competition for As uptake by roots. The results demonstrate the nexus between sorption and bioavailability of As and Cd in soils, indicating that the effects of

  2. Patterns and variability in geochemical signatures and microbial activity within and between diverse cold seep habitats along the lower continental slope, Northern Gulf of Mexico

    Science.gov (United States)

    Bowles, Marshall; Hunter, Kimberley S.; Samarkin, Vladimir; Joye, Samantha

    2016-07-01

    We collected 69 sediment cores from distinct ecological and geological settings along the deep slope in the Northern Gulf of Mexico to evaluate whether specific geochemical- or habitat-related factors correlated with rates of microbial processes and geochemical signatures. By collecting replicate cores from distinct habitats across multiple sites, we illustrate and quantify the heterogeneity of cold seep geochemistry and microbial activity. These data also document the factors driving unique aspects of the geochemistry of deep slope gas, oil and brine seeps. Surprisingly little variation was observed between replicate (n=2-5) cores within sites for most analytes (except methane), implying that the common practice of collecting one core for geochemical analysis can capture the signature of a habitat in most cases. Depth-integrated concentrations of methane, dissolved inorganic carbon (DIC), and calcium were the predominant geochemical factors that correlated with a site's ecological or geological settings. Pore fluid methane concentration was related to the phosphate and DIC concentration, as well as to rates of sulfate reduction. While distinctions between seep habitats were identified from geochemical signatures, habitat specific geochemistry varied little across sites. The relative concentration of dissolved inorganic nitrogen versus phosphorus suggests that phosphorus availability limits biomass production at cold seeps. Correlations between calcium, chloride, and phosphate concentrations were indicative of brine-associated phosphate transport, suggesting that in addition to the co-migration of methane, dissolved organic carbon, and ammonium with brine, phosphate delivery is also associated with brine advection.

  3. Sensitivity of the Biosphere-Atmosphere Transfer Scheme (BATS) to the Inclusion of Variable Soil Characteristics.

    Science.gov (United States)

    Wilson, M. F.; Henderson-Sellers, A.; Dickinson, R. E.; Kennedy, P. J.

    1987-03-01

    The soils data of Wilson and Henderson-Sellers have been incorporated into the land-surface parameterization scheme of the NCAR Community Climate Model after Dickinson. A stand-alone version of this land-surface scheme, termed the Biosphere-Atmosphere Transfer Scheme (BATS), has been tested in a series of sensitivity experiments designed to assess the sensitivity of the scheme to the inclusion of variable soil characteristics. The cases investigated were for conditions designed to represent a low-latitude, evergreen forest; a low-latitude sand desert; a high-latitude coniferous forest; high-latitude tundra; and prairie grasslands, each for a specified time of year. The tundra included spring snowmelt and the grassland incorporated snow accumulation. The sensitivity experiments included varying the soil texture from a coarse texture typical of sand through a medium texture typical of loam to a fine texture typical of clay. The sensitivity of the formulation to the specified total and upper soil column depth and the response to altering the parameterization of the soil albedo dependence upon soil wetness and snow-cover were also examined. The biosphere-atmosphere transfer scheme showed the greatest sensitivity to the soil texture variation, particularly to the associated variation in the hydraulic conductivity and diffusivity parameters. There was only a very small response to the change in the soil albedo dependence on wetness and, although the sensitivity to the snow-covered soil albedo via the response to roughness length/snow-masking depth was significant, the results were predictable. Changing the total depth of the active soil column produced a much smaller response than altering the depth of the upper soil layer, primarily because the degree of saturation of the upper layer plays an important role in the parameterized hydrology. Soil moisture responses can also be initiated by changes in vegetation characteristics such as the stomatal resistance through

  4. Gamma-ray attenuation method as an efficient tool to investigate soil bulk density spatial variability

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F., E-mail: lfpires@uepg.b [Laboratory of Soil Physics and Environmental Sciences, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Rosa, J.A. [Laboratory of Soil Physics, Agricultural Research Institute of Parana, IAPAR, C.E.P. 84.001-970 Ponta Grossa, PR (Brazil); Pereira, A.B. [Laboratory of Agrometeorology, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Arthur, R.C.J.; Bacchi, O.O.S. [Laboratory of Soil Physics, Center for Nuclear Energy in Agriculture, USP/CENA, C.E.P. 13.400-970 Piracicaba, SP (Brazil)

    2009-11-15

    The spatial variability of soil bulk density (rho{sub b}) was measured by using the volumetric ring method (VRM) and the gamma-ray attenuation method (GAM). Collimated radiation from 3.7 GBq of {sup 241}Am was used to evaluate the soil mass attenuation coefficient and its bulk density. Circular lead collimators were adjusted and aligned between source (D = 1, 2 and 3 mm) and detector (D = 4.5 mm). Results of GAM for average rho{sub b} provided good agreement with the corresponding values obtained gravimetrically. Variations in bulk density for different collimator dimensions can be attributed to multiple scattering after photons interaction with soil, mainly for 3 mm collimator size. The best result of rho{sub b} by the nuclear technique was obtained when rho{sub b} represents an average of the measurements for collimators of 1 and 2 mm. Another cause for the differences in rho{sub b} by GAM and VRM is the heterogeneity of soil when the collimated beam can interact with stones or large air-filled holes or channels present in the sample. Therefore, the pattern of spatial variability obtained by VRM was confirmed by GAM for all collimator sizes. This result is a good indication that GAM can be used with success to analyze soil spatial variability.

  5. Precipitation- and soil moisture variability in Germany: Fully coupled WRF-Hydro vs. standard WRF

    Science.gov (United States)

    Arnault, Joel; Rummler, Thomas; Kunstmann, Harald

    2016-04-01

    Soil moisture plays a crucial role in land-atmosphere interactions. Land-atmosphere feedbacks are expected to be strongest in transition zones between wet and dry land surfaces. It is therefore questionable whether a physically-enhanced description of soil moisture variability in a numerical model would improve the realism of the simulated atmosphere. This question is investigated here for a two-year period in Germany, including a one-year spinup time, using the hydrologically enhanced version of the Weather Research and Forecasting WRF model, namely WRF-Hydro. The simulated domain covers Germany and neighboring areas. Atmospheric processes are resolved on a 4km resolution grid with explicit convection, whereas hydrological processes, namely overland flow, subsurface lateral flow and river flow, are resolved on a subgrid at 400 m resolution. This WRF-Hydro setup is run for several values of the surface infiltration parameter, in order to evaluate model result uncertainty originating from uncertainty in the description of terrestrial hydrological processes. Soil moisture variability deduced from this WRF-Hydro ensemble is compared with that deduced from a WRF-standalone ensemble. WRF and WRF-Hydro results are validated with daily gridded E-OBS datasets of precipitation and temperature from the European Climate Assessment & Dataset, and daily discharge data from the Global Runoff Data Center GRDC. The impact of the physically-enhanced description of soil moisture variability in WRF-Hydro is finally investigated with the concept of soil moisture memory.

  6. Spatial variability of some soil properties varies in oil palm (Elaeis guineensis Jacq.) plantations of west coastal area of India

    Science.gov (United States)

    Behera, Sanjib Kumar; Suresh, Kancherla; Narsimha Rao, Bezawada; Mathur, Ravi Kumar; Shukla, Arvind Kumar; Manorama, Kamireddy; Ramachandrudu, Kummari; Harinarayana, Parasa; Prakash, Chandra

    2016-06-01

    Mapping spatial variability of soil properties is the key to efficient soil resource management for sustainable crop yield. Therefore, the present study was conducted to assess the spatial variability of soil properties such as acidity (pH), salinity (electrical conductivity (EC)), organic carbon, available K, available P, exchangeable Ca2+, exchangeable Mg2+, available S and hot water soluble B in surface (0-20 cm) and subsurface (20-40 cm) soil layers of oil palm plantations in south Goa district of Goa located in west coastal area of India. A total of 128 soil samples were collected from 64 oil palm plantations of Goa located at an approximate interval of 1-2 km and analyzed. Soil was acidic to neutral in reaction. Other soil properties varied widely in both the soil layers. Correlations between soil pH and exchangeable Ca2+, between soil EC and available K, between available P and available S and between exchangeable Ca2+ and exchangeable Mg2+ in both the soil layers were found to be positive and significant (P < 0.01). Geostatistical analysis revealed a varied spatial distribution pattern for the measured soil properties. Best-fit models for measured soil properties were exponential, Gaussian, stable, K-Bessel and spherical with moderate to strong spatial dependency. The results revealed that site-specific fertilizer management options needed to be adopted in the oil palm plantations of the study area owing to variability in soil properties.

  7. Assessing spatial variability of soil petroleum contamination using visible near-infrared diffuse reflectance spectroscopy.

    Science.gov (United States)

    Chakraborty, Somsubhra; Weindorf, David C; Zhu, Yuanda; Li, Bin; Morgan, Cristine L S; Ge, Yufeng; Galbraith, John

    2012-11-01

    Visible near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) is a rapid, non-destructive method for sensing the presence and amount of total petroleum hydrocarbon (TPH) contamination in soil. This study demonstrates the feasibility of VisNIR DRS to be used in the field to proximally sense and then map the areal extent of TPH contamination in soil. More specifically, we evaluated whether a combination of two methods, penalized spline regression and geostatistics could provide an efficient approach to assess spatial variability of soil TPH using VisNIR DRS data from soils collected from an 80 ha crude oil spill in central Louisiana, USA. Initially, a penalized spline model was calibrated to predict TPH contamination in soil by combining lab TPH values of 46 contaminated and uncontaminated soil samples and the first-derivative of VisNIR reflectance spectra of these samples. The r(2), RMSE, and bias of the calibrated penalized spline model were 0.81, 0.289 log(10) mg kg(-1), and 0.010 log(10) mg kg(-1), respectively. Subsequently, the penalized spline model was used to predict soil TPH content for 128 soil samples collected over the 80 ha study site. When assessed with a randomly chosen validation subset (n = 10) from the 128 samples, the penalized spline model performed satisfactorily (r(2) = 0.70; residual prediction deviation = 2.0). The same validation subset was used to assess point kriging interpolation after the remaining 118 predictions were used to produce an experimental semivariogram and map. The experimental semivariogram was fitted with an exponential model which revealed strong spatial dependence among soil TPH [r(2) = 0.76, nugget = 0.001 (log(10) mg kg(-1))(2), and sill 1.044 (log(10) mg kg(-1))(2)]. Kriging interpolation adequately interpolated TPH with r(2) and RMSE values of 0.88 and 0.312 log(10) mg kg(-1), respectively. Furthermore, in the kriged map, TPH distribution matched with the expected TPH variability of the study site. Since the

  8. Spatial Variability Some Physical and Chemical Prpperties Soil surface In Dasht-e-Tabriz Different Landforms

    Science.gov (United States)

    Foroughifar, Hamed; Asghar Jafarzadeh, Ali; Torabi, Hosien; Aliasgharzad, Naser; Toomanian, Norair

    2010-05-01

    Spatial distribution of soil properties at the field and watershed scale(region scale) affect yield potential, hydrologic responses , and transport of herbicides and No3 to surface or groundwater.The present study aim was to evaluate some physical and chemical properties spatial variability and frequency distribution within and between landforms of Dash-e-Tabriz in the northwest of Iran.For this evaluation 98 samples from soils surface of layer according to grid sampling design and with 500-1000 meters distance based on soils variability were selected and analysed.Landforms were hill, piedmont plain, plain, river alluvial plain and lowland.The study of soil variables frequency distribution showed that Bd, CEC, Caco3, pH,clay and silt follow normal distribution ,which to study their variation one can use parametric statistical method.Variables such as MWD, N(total), SAR, EC, P(available) and sand showed log-normal distribution,that for their variation study,should first be transformed to a logarithmic scale.The variables frequency distribution increase within landforms,which in lowland, hill, and river alluvial plain they showed normal distribution and only EC in piedmont plain and sand, OC and N(total) in plain had log-normal distributions.The results indicate significantly differences of soil properties distribution among landforms,which clay ,pH, EC ,SAR and MWD, CEC, Bd, N(total), OC, P(available), sand, silt were strongly and moderately spatial dependent respectively and Caco3 had no spatial dependence and it is following nugget model.These results indicate that strong spatial dependence due to the effects of intrinsic factors such as parent material, relief and soil types. Also soil properties variations result from variation in depositional environments and or differences in pedogenic or hydrologic processes for different landform positions,and so it can be affected by the flood irrigation,fertilizeir addition,high watertable level or agriculture practices

  9. Petrographic, mineralogical and geochemical characterization of the Serrinha coal waste pile (Douro Coalfield, Portugal) and the potential environmental impacts on soil, sediments and surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J. [Centro de Geologia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Ferreira da Silva, E. [GeoBioTec, Geobiosciences, Geotechnologies and Geoengineering Research Center, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Li, Z.; Ward, C. [School of Biological, Earth and Environmental Sciences, University of New South Wales. Sydney, NSW 2052 (Australia); Flores, D. [Departamento de Geociencias, Ambiente e Ordenamento do Territorio, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)

    2010-09-01

    Serrinha is the largest coal waste pile resulting from mining activities in the Douro Coalfield, Portugal. The exploitation of anthracite in tens of small mines caused some environmental impacts, as is the case of the coal waste piles that exist in old mines and adjacent areas. The Serrinha waste pile is essentially made up of 2 million tonnes of shales and carbonaceous shales, deposited in a topographical depression over about 30 years. Despite the environmental restoration accomplished in the Serrinha waste pile, some environmental problems seem to persist. In this study a petrographic, mineralogical and geochemical characterization was done in order to recognize and understand these problems. The materials studied were coal waste, sediments and waters from the drainage system and decanting basins, soils from the surrounding areas, leachates from waste material and neoformed minerals formed at the bottom of the waste pile. The main lithologies (carbonaceous shale and lithic arenite) and coal from the Douro Coalfield were also analyzed. Petrographic analysis shows some evidence of weathering (on organic and inorganic matter) related to the time of exposure to the weathering agents and the easy access of air within the waste pile (due to both the poor compaction and the heterogeneity of the material). Mineralogically, the composition of coal waste material has contributions from both the coal and the associated lithologies. R-type cluster analysis of the waste pile material allows two distinct clusters to be identified. In the first cluster a sulfide fraction is represented by the association of As, Cd, Cu, Pb, Ni and Zn, while Fe clustered with Al, Co, and Ti indicates that some of the Fe and the other elements are likely associated with silicate minerals such as clays. The second cluster, represented by Cr, V, Zr, Rb, REE, Mn, Li and Ba, probably represent a silicate fraction, perhaps detrital accessory minerals. The waste pile material, leachates, soils

  10. Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines

    DEFF Research Database (Denmark)

    Kendrick, Joseph A.; Ribbons, Relena Rose; Classen, Aimee Taylor;

    2015-01-01

    in ant species composition would interact to alter soil ecosystem variables. In the Harvard Forest Hemlock Removal Experiment (HF-HeRE), established in 2003, T. canadensis in large plots were killed in place or logged and removed to mimic adelgid infestation or salvage harvesting, respectively. In 2006......, we built ant exclosure subplots within all of the canopy manipulation plots to examine direct and interactive effects of canopy change and ant assemblage composition on soil and litter variables. Throughout HF-HeRE, T. canadensis was colonized by the adelgid in 2009, and the infested trees are now...... declining. The experimental removal of T. canadensis from the canopy was associated with an increase in the rate of cellulose decomposition by >50%, and exclosure of ants from subplots directly reduced their soil nitrate availability by 56%. Partial least squares path models revealed sequential interactive...

  11. Adsorption of glyphosate on variable-charge, volcanic ash-derived soils.

    Science.gov (United States)

    Cáceres-Jensen, L; Gan, J; Báez, M; Fuentes, R; Escudey, M

    2009-01-01

    Glyphosate (N-phosphonometylglycine) is widely used due to its broad spectrum of activity and nonselective mode of action. In Chile it is the most used herbicide, but its adsorption behavior in the abundant and widespread variable charge soils is not well understood. In this study, three volcanic ash-derived soils were selected, including Andisols (Nueva Braunau and Diguillin) and Ultisols (Collipulli), to evaluate the adsorption kinetics, equilibrium isotherms, and the effect of pH in glyphosate adsorption. The influence of glyphosate on soil phosphorus retention was also studied. Glyphosate was rapidly and strongly adsorbed on the selected soils, and adsorption isotherms were well described by the Freundlich relationship with strong nonlinearity (n(fads) glyphosate (3200 mug mL(-1)) changed the adsorption behavior of phosphate at its maximum adsorption capacity. Andisol soils without the addition of glyphosate had similar mean K(ads) values for Nueva Braunau (5.68) and Diguillin (7.38). Collipulli had a mean K(ads) value of 31.58. During the successive desorption steps, glyphosate at the highest level increased K(ads) values for phosphate in the Andisol soils but had little effect in the Ultisol soil. This different behavior was probably due to the irreversible occupation of some adsorption sites by glyphosate in the Ultisol soil attributed to the dominant Kaolinite mineral. Results from this study suggest that in the two types of volcanic soils, different mechanisms are involved in glyphosate and phosphate adsorption and that long-term use of glyphosate may impose different effects on the retention and availability of phosphorus. Volcanic ash-derived soils have a particular environmental behavior in relation to the retention of organic contaminants, representing an environmental substrate that may become highly polluted over time due to intensive agronomic uses.

  12. Geochemical and physical properties, distribution coefficients of soils and sediments at the Olkiluoto Island and in the reference area in 2010-2011

    Energy Technology Data Exchange (ETDEWEB)

    Lahdenperae, A.-M. [Saanio and Riekkola Oy, Helsinki (Finland)

    2014-04-15

    The report summarises the chemical, physical and mineralogical data and the calculated 'in situ' distribution coefficients (K{sub d}) values of the indigenous elements from the different types of soil and sediment samples at the Olkiluoto Island and in the Reference area that were taken in 2010-2011. The data has been collected in order to extend the understanding of the site evolution and for radionuclide transport analyses and modelling. 'In situ' distribution coefficients, K{sub d} values are used to indicate the relevant mobility of elements and radionuclides. This report is part of the entirety of soil and sediment data from different soil types, soil layers and environmental conditions collected earlier for the biosphere site description and development. Soil and sediment samples were taken at various depths of humus, peat, gyttja, sandy/fine sandy till and cropland soils. The analyses procedure varied to some extent between the samples. In all samples were analysed pH, LOI, C, N, and the total concentrations of the elements using HNO{sub 3}-HF extraction. The 'in situ' K{sub d} values were calculated using the formula by Sheppard et al.. For selected samples the easily leachable fraction was analysed by NH{sub 4}Ac (pH 4.5). Bulk density and mineralogy was determined for a few samples. Grain size distribution was measured only from till samples. The results are discussed and the physical-chemical data and distribution coefficients of the results are presented. The cation exchange capacity and base saturation are calculated for the sandy/fine sandy till samples from Olkiluoto. The K{sub d} values of the important indigenous elements Ag, Cl, Cs, I, Mo, Ni, Se and Sr are of main interest in biosphere development due to the longest half-lives of the associated radionuclides, thus having long interaction times. The K{sub d} data are inherently extremely variable due to nature of practical quantity in question, aggregating a number of

  13. Areal variability of the mineral soil cover in a reclaimed soda waste dumping site

    Directory of Open Access Journals (Sweden)

    Klatka Sławomir

    2017-03-01

    Full Text Available Areal variability of the mineral soil cover in a reclaimed soda waste dumping site. This paper provides an analysis of the areal variability of the thickness and selected physical and chemical properties of the mineral cover formed in the process of settling ponds reclamation at the former Krakow Soda Plant “Solvay”. The topsoil is intended to provide a substrate for plants, therefore, its quality is the main determinant of the development for herbaceous and woody vegetation. Areal variability of the topsoil parameters was determined by kriging. In the context of the envisaged direction of management of the settling ponds, the analysis showed that electrical conductivity, thickness of the soil cover and the sand fraction content have potentially the highest impact on the diversification of vegetation. Understanding the spatial variability of the soil cover parameters, that are essential for vegetation, may contribute to increasing the efficiency of biological reclamation and also to cost reduction. Precise selection of the areas unsuitable for plant growth makes it possible to improve soil parameters on limited areas similarly as in the precision agriculture.

  14. Soil temperature variability in complex terrain measured using fiber-optic distributed temperature sensing

    Science.gov (United States)

    Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes but magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber optic distributed temperature sensing systems (FO-DTS) potentially measure Ts at high density over a large extent. ...

  15. Transport and Deposition of Variably Charged Soil Colloids in Saturated Porous Media

    DEFF Research Database (Denmark)

    Sharma, Anu; Kawamoto, Ken; Møldrup, Per

    2011-01-01

    A series of column experiments was conducted to investigate the transport and deposition of variably charged colloids in saturated porous media. Soil colloids with diameters colloids) and a red-yellow soil from...... Okinawa (RYS colloids) in Japan. The VAS colloids exhibited a negative surface charge with a high pH dependency, whereas the RYS colloids exhibited a negative surface charge with less pH dependency. The soil colloids were applied as colloidal suspensions to 10-cm-long saturated sand columns packed....... Breakthrough curves and deposition profiles for soil colloids were strong functions of the hydrodynamics, solution pH, and surface charge of the colloids and sand grains. Greater deposition was typical for lower flow rates and lower pH. The deposition of VAS colloids in both sands under low-pH conditions...

  16. Reconstructing late Quaternary palaeosol development and landscape connectivity from combined soil magnetic, geochemical and micromorphological analyses: insights from the Wilgerbosch River, Great Karoo, South Africa.

    Science.gov (United States)

    Oldknow, Chris; Hooke, Janet; Oldfield, Frank

    2017-04-01

    water table and wetlands on the valley floors. Inset clay coatings and calcite hypocoatings attest to fluctuating groundwater levels. The calcrete acted to blanket T1 and T2 reducing extent of connectivity in subsequent phases of terrace development. Sediment in inset fills (T3-4) exhibited diminished primary mineral concentrations and ferrimagnetism (XLF = 20-60) due to recycling of earlier deposits (T1/T2), disconnectivity with 1st order tributaries and episodic gleying and dissolution of organic matter due to fluctuating groundwater level. The terrace palaeosols in the Wilgerbosch catchment are therefore polygenetic reflecting both changing sources of sediment (slope or channel) and multiple phases of soil development under varied palaeohydrological conditions. Caution is therefore urged attempting to relate conventional magnetic (XLF, XARM, XFD) and geochemical (CIA, CIW) metrics of pedogenesis in morphologically similar catchments to palaeoclimatic records. The approach taken in this study is presently useful for reconstructing extent of connectivity between landscape components.

  17. Soil process-oriented modelling of within-field variability based on high-resolution 3D soil type distribution maps.

    Science.gov (United States)

    Bönecke, Eric; Lück, Erika; Gründling, Ralf; Rühlmann, Jörg; Franko, Uwe

    2016-04-01

    Today, the knowledge of within-field variability is essential for numerous purposes, including practical issues, such as precision and sustainable soil management. Therefore, process-oriented soil models have been applied for a considerable time to answer question of spatial soil nutrient and water dynamics, although, they can only be as consistent as their variation and resolution of soil input data. Traditional approaches, describe distribution of soil types, soil texture or other soil properties for greater soil units through generalised point information, e.g. from classical soil survey maps. Those simplifications are known to be afflicted with large uncertainties. Varying soil, crop or yield conditions are detected even within such homogenised soil units. However, recent advances of non-invasive soil survey and on-the-go monitoring techniques, made it possible to obtain vertical and horizontal dense information (3D) about various soil properties, particularly soil texture distribution which serves as an essential soil key variable affecting various other soil properties. Thus, in this study we based our simulations on detailed 3D soil type distribution (STD) maps (4x4 m) to adjacently built-up sufficient informative soil profiles including various soil physical and chemical properties. Our estimates of spatial STD are based on high-resolution lateral and vertical changes of electrical resistivity (ER), detected by a relatively new multi-sensor on-the-go ER monitoring device. We performed an algorithm including fuzzy-c-mean (FCM) logic and traditional soil classification to estimate STD from those inverted and layer-wise available ER data. STD is then used as key input parameter for our carbon, nitrogen and water transport model. We identified Pedological horizon depths and inferred hydrological soil variables (field capacity, permanent wilting point) from pedotransferfunctions (PTF) for each horizon. Furthermore, the spatial distribution of soil organic carbon

  18. Effect of rainfall interannual variability on the biomass and soil water distribution in a semiarid shrub community

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The dynamics of biomass and soil moisture in semiarid land is driven by both the current rainfall and the ecosystem memory.Based on a meta-analysis of existing experiments,an ecosystem model was used to calculate the effect of the rainfall interannual variability on the pattern of biomass and soil moisture in a shrub community.It was found that rainfall interannual variability enabled shrubs to be more competitive than grasses,and to maintain the dominant role over a longer time.The rainfall interannual variability resulted in complex soil moisture dynamics.The soil water recharge in wet years alternated with discharge in drought years.

  19. GEOCHEMICAL EXPLORATION

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111167 Cao Zhonghuang(Wuhan Iron & Steel Group Minerals Company,Wuhan 430063,China);Luo Xianrong Comparative Study of Copper-Nickel Deposit Exploration by the Geoelectro-chemical Extraction Method in Different Overburden Areas(Geology and Prospecting,ISSN0495-5331,CN11-2043/P,46(3),2010,p.476-482,4 illus.,5 tables,20 refs.)Key words:geo-electrochemical methods,copper ores,nickel ores,Gansu Province,Jilin Province The authors have made a comparative study of quantitative and qualitative analysis and application of the geoelectro-chemical extraction method in different overburden areas in southward extension of Jinchuan in Gansu Province and Hongqiling in Jilin Province.The authors found that this method extracted very few ions in arid areas covered with debris,but the prospecting effect was almost the same as that in moist areas covered with thick overburden.And this method could show objectively differences of geochemical characters

  20. Assessing geotechnical centrifuge modelling in addressing variably saturated flow in soil and fractured rock.

    Science.gov (United States)

    Jones, Brendon R; Brouwers, Luke B; Van Tonder, Warren D; Dippenaar, Matthys A

    2017-01-05

    The vadose zone typically comprises soil underlain by fractured rock. Often, surface water and groundwater parameters are readily available, but variably saturated flow through soil and rock are oversimplified or estimated as input for hydrological models. In this paper, a series of geotechnical centrifuge experiments are conducted to contribute to the knowledge gaps in: (i) variably saturated flow and dispersion in soil and (ii) variably saturated flow in discrete vertical and horizontal fractures. Findings from the research show that the hydraulic gradient, and not the hydraulic conductivity, is scaled for seepage flow in the geotechnical centrifuge. Furthermore, geotechnical centrifuge modelling has been proven as a viable experimental tool for the modelling of hydrodynamic dispersion as well as the replication of similar flow mechanisms for unsaturated fracture flow, as previously observed in literature. Despite the imminent challenges of modelling variable saturation in the vadose zone, the geotechnical centrifuge offers a powerful experimental tool to physically model and observe variably saturated flow. This can be used to give valuable insight into mechanisms associated with solid-fluid interaction problems under these conditions. Findings from future research can be used to validate current numerical modelling techniques and address the subsequent influence on aquifer recharge and vulnerability, contaminant transport, waste disposal, dam construction, slope stability and seepage into subsurface excavations.

  1. Future climate variability impacts on potential erosion and soil organic carbon in European croplands

    Directory of Open Access Journals (Sweden)

    M. van der Velde

    2014-01-01

    Full Text Available We investigate the impact of future climate variability on the potential vulnerability of soils to erosion and the consequences for soil organic carbon (SOC in European croplands. Soil erosion is an important carbon flux not characterized in Earth System Models. We use a~European implementation of EPIC, driven by reference climate data (CNTRL, and climate data with reduced variability (REDVAR. Whether erosion regimes will change across European cropland depends on the spatial conjunction of expected changes in climate variability and physiographic conditions conducive to erosion. We isolated the effect of erosion by performing simulations with and without erosion. Median CNTRL and REDVAR erosion rates equalled 14.4 and 9.1 ton ha−1, and 19.1 and 9.7, for 1981–2010 and 2071–2100, respectively. The total amount of carbon lost from European cropland due to erosion was estimated at 769 Tg C for 1981–2010 (from a total storage of 6197 Tg C without erosion under CNTRL climate. Climate trend impacts reduce the European cropland SOC stock by 578 Tg C without – and by 683 Tg C with erosion, from 1981 to 2100. Climate variability compounds these impacts and decreases the stock by an estimated 170 Tg without erosion and by 314 Tg C with erosion, by the end of the century. Future climate variability and erosion will thus compound impacts on SOC stocks arising from gradual climate change alone.

  2. Spatial variability of detrended soil plow layer penetrometer resistance transect in a sugarcane field

    Science.gov (United States)

    Pérez, Luis D.; Cumbrera, Ramiro; Mato, Juan; Millán, Humberto; Tarquis, Ana M.

    2015-04-01

    Spatial variability of soil properties is relevant for identifying those zones with physical degradation. In this sense, one has to face the problem of identifying the origin and distribution of spatial variability patterns (Brouder et al., 2001; Millán et al., 2012). The objective of the present work was to quantify the spatial structure of soil penetrometer resistance (PR) collected from a transect data consisted of 221 points equidistant. In each sampling, readings were obtained from 0 cm till 70 cm of depth, with an interval of 5 cm (Pérez, 2012). The study was conducted on a Vertisol (Typic Hapludert) dedicated to sugarcane (Saccharum officinarum L.) production during the last sixty years (Pérez et al., 2010). Recently, scaling approach has been applied on the determination of the scaling data properties (Tarquis et al., 2008; Millán et al., 2012; Pérez, 2012). We focus in the Hurst analysis to characterize the data variability for each depth. Previously a detrended analysis was conducted in order to better study de intrinsic variability of the series. The Hurst exponent (H) for each depth was estimated showing a characteristic pattern and differentiating PR evolution in depth. References Brouder, S., Hofmann, B., Reetz, H.F., 2001. Evaluating spatial variability of soil parameters for input management. Better Crops 85, 8-11. Millán, H; AM Tarquís, Luís D. Pérez, Juan Mato, Mario González-Posada, 2012. Spatial variability patterns of some Vertisol properties at a field scale using standardized data. Soil and Tillage Research, 120, 76-84. Pérez, Luís D. 2012. Influencia de la maquinaria agrícola sobre la variabilidad espacial de la compactación del suelo. Aplicación de la metodología geoestadística-fractal. PhD thesis, UPM (In Spanish). Pérez, Luís D., Humberto Millán, Mario González-Posada 2010. Spatial complexity of soil plow layer penetrometer resistance as influenced by sugarcane harvesting: A prefractal approach. Soil and Tillage

  3. Seasonal variability of near-saturated hydraulic conductivity on cultivated soil

    Science.gov (United States)

    Klípa, Vladimír; Zumr, David; Sněhota, Michal

    2014-05-01

    The soil structure and hydraulic properties of arable soils considerably vary during the year due to the periodical tillage and fertilization activities, soil compaction, plant and root grow, climate impact etc. The knowledge of the effect of temporal soil variability is essential when assessing water regime and associated dissolved substance transport in soils. The main aim of this contribution is to describe the temporal development of unsaturated hydraulic conductivity on arable land during a year. The experimental site is located in Nucice catchment (Central Bohemia, Czech republic), where also rainfall-runoff and soil erosion processes are studied. The soil is classified as Cambisol, typical texture ranges from loam to clay loam classes. Soil is conservatively tilled till depth of approximately 17 cm, below the topsoil a compacted subsoil was observed. Tension infiltration experiments were performed repeatedly at single location in order to determine the unsaturated hydraulic conductivity of the topsoil. So far four tension infiltration campaigns were carried out under tension h0 = -3.0 cm with different field conditions: (i) young winter barley (October 2012), (ii) between postharvest stubble breaking and seeding (April 2013), (iii) full-grown oat (June 2013) and (iv) after fresh postharvest stubble breaking (October 2013). Measurements were carried out using newly introduced automated multi minidisk tension infiltrometer (Klipa et al., EGU2014-7230). All experiments were performed on the levelled soil surface after removing upper soil layer (1 to 3 cm). A thin layer of quartz sand (thickness 1 - 2 mm, grain size 0.1 - 0.6 mm) was applied to improve contact between the infiltrometer and the soil surface. Each infiltration campaign consisted of six tension infiltration experiments, the total number of 24 infiltration data sets was obtained for this study. Results show that unsaturated hydraulic conductivity was significantly smaller in April, but rather the

  4. Phosphorus-arsenic interactions in variable-charge soils in relation to arsenic mobility and bioavailability.

    Science.gov (United States)

    Bolan, Nanthi; Mahimairaja, Santiago; Kunhikrishnan, Anitha; Choppala, Girish

    2013-10-01

    Phosphorus (P) influences arsenic (As) mobility and bioavailability which depends on the charge components of soil. The objective of this study was to examine P-As interaction in variable-charge allophanic soils in relation to P-induced As mobilization and bioavailability. In this work, the effect of P on arsenate [As(V)] adsorption and desorption was examined using a number of allophanic and non-allophanic soils which vary in their anion adsorption capacity. The effect of P on As uptake by Indian mustard (Brassica juncea L.) plants was examined using a solution culture, and a soil plant growth experiment involving two As-spiked allophanic and non-allophanic soils which vary in their anion adsorption capacity, and a field As-contaminated sheep dip soil. Arsenate adsorption increased with an increase in the anion adsorption capacity of soils. The addition of P resulted in an increase in As desorption, and the effect was more pronounced in the case of allophanic soil. In the case of both As-spiked soils and field contaminated sheep-dip soil, application of P increased the desorption of As, thereby increasing its bioavailability. The effect of P on As uptake was more pronounced in the high anion adsorbing allophanic than low adsorbing non-allophanic soil. In the case of solution culture, As phytoavailability decreased with increasing concentration of P which is attributed to the competition of P for As uptake by roots. While increasing P concentration in solution decreased the uptake of As, it facilitated the translocation of As from root to shoot. The net effect of P on As phytoavailability in soils depends on the extent of P-induced As mobilization in soils and P-induced competition for As uptake by roots. The P-induced mobilization of As could be employed in the phytoremediation of As-contaminated sites. However, care must be taken to minimize the leaching of As mobilized through the P-induced desorption, thereby resulting in groundwater and off site contamination

  5. Selecting minimum dataset soil variables using PLSR as a regressive multivariate method

    Science.gov (United States)

    Stellacci, Anna Maria; Armenise, Elena; Castellini, Mirko; Rossi, Roberta; Vitti, Carolina; Leogrande, Rita; De Benedetto, Daniela; Ferrara, Rossana M.; Vivaldi, Gaetano A.

    2017-04-01

    Long-term field experiments and science-based tools that characterize soil status (namely the soil quality indices, SQIs) assume a strategic role in assessing the effect of agronomic techniques and thus in improving soil management especially in marginal environments. Selecting key soil variables able to best represent soil status is a critical step for the calculation of SQIs. Current studies show the effectiveness of statistical methods for variable selection to extract relevant information deriving from multivariate datasets. Principal component analysis (PCA) has been mainly used, however supervised multivariate methods and regressive techniques are progressively being evaluated (Armenise et al., 2013; de Paul Obade et al., 2016; Pulido Moncada et al., 2014). The present study explores the effectiveness of partial least square regression (PLSR) in selecting critical soil variables, using a dataset comparing conventional tillage and sod-seeding on durum wheat. The results were compared to those obtained using PCA and stepwise discriminant analysis (SDA). The soil data derived from a long-term field experiment in Southern Italy. On samples collected in April 2015, the following set of variables was quantified: (i) chemical: total organic carbon and nitrogen (TOC and TN), alkali-extractable C (TEC and humic substances - HA-FA), water extractable N and organic C (WEN and WEOC), Olsen extractable P, exchangeable cations, pH and EC; (ii) physical: texture, dry bulk density (BD), macroporosity (Pmac), air capacity (AC), and relative field capacity (RFC); (iii) biological: carbon of the microbial biomass quantified with the fumigation-extraction method. PCA and SDA were previously applied to the multivariate dataset (Stellacci et al., 2016). PLSR was carried out on mean centered and variance scaled data of predictors (soil variables) and response (wheat yield) variables using the PLS procedure of SAS/STAT. In addition, variable importance for projection (VIP

  6. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ceddia, Marcos Bacis, E-mail: marcosceddia@gmail.com [Department of Soil, Institute of Agronomy, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, RJ 23890-000 (Brazil); Villela, André Luis Oliveira [Colégio Técnico da UFRRJ, RJ, Seropédica 23890-000 (Brazil); Pinheiro, Érika Flávia Machado [Department of Soil, Institute of Agronomy, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, RJ 23890-000 (Brazil); Wendroth, Ole [Department of Plant & Soil Sciences, University of Kentucky, College of Agriculture, Lexington, KY (United States)

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0–30 and the 0–100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km{sup 2} and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m{sup −2}, respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock. - Highlights: • The SOC stocks across 30 and 100 cm depth were 3.28 and 7.32 kg C m{sup −2}, respectively. • SOC stocks were 34 and 16

  7. Amplification and dampening of soil respiration by changes in temperature variability

    Directory of Open Access Journals (Sweden)

    C. A. Sierra

    2011-04-01

    Full Text Available Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  8. Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface.

    Science.gov (United States)

    Kristensen, Andreas H; Poulsen, Tjalfe G; Mortensen, Lars; Moldrup, Per

    2010-07-15

    Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused on the shallow unsaturated zone. Based on a data set comprising analysis of about 100 soil samples taken in a 16 m-deep unsaturated zone polluted with volatile petroleum compounds, we statistically and geostatistically analysed values of essential soil properties. The subsurface of the site was highly layered, resulting in an accumulation of pollution within coarse sandy lenses. Air-filled porosity, readily available phosphorous, and the first-order rate constant (k(1)) of benzene obtained from slurry biodegradation experiments were found to depend on geologic sample characterization (P<0.05), while inorganic nitrogen was homogenously distributed across the soil stratigraphy. Semivariogram analysis showed a spatial continuity of 4-8.6 m in the vertical direction, while it was 2-5 times greater in the horizontal direction. Values of k(1) displayed strong spatial autocorrelation. Even so, the soil potential for biodegradation was highly variable, which from autoregressive state-space modeling was partly explained by changes in soil air-filled porosity and gravimetric water content. The results suggest considering biological heterogeneity when evaluating the fate of contaminants in the subsurface.

  9. Interannual variability in soil nitric oxide emissions over the United States as viewed from space

    Directory of Open Access Journals (Sweden)

    R. C. Hudman

    2010-10-01

    Full Text Available We examine the interannual variability in the NO2 column over North America measured by the Ozone Monitoring Instrument (OMI in 2005–2008. By comparison to a model of soil NOx emissions driven by the North American Regional Reanalysis precipitation and 0–10 cm soil temperature fields, we show the source of this observed interannual variability over much of the central United States in June is fertilizer application. We find that dry, warm conditions followed by convective precipitation induces pulsed emissions of NOx over the agricultural Great Plains. In June 2006 we infer a 50% increase in soil NOx emission and a 30% increase in the tropospheric NO2 column relative to the June 2005–2008 mean. In a case-study of fertilized corn and soybean fields over SE South Dakota, we find an associated rain-induced pulsing event reaching 4.6×1015 molec cm−2, equivalent to a surface concentration of ~2 ppbv. We calculate that soil NOx emissions resulted in a mean daily maximum 8-h ozone enhancement over the agricultural Great Plains of 5 ppbv in June 2006 (with predicted events reaching 16 ppbv compared with a mean enhancement of 3 ppbv for soil NOx in the years 2005–2008.

  10. Interannual variability in soil nitric oxide emissions over the United States as viewed from space

    Science.gov (United States)

    Hudman, R. C.; Russell, A. R.; Valin, L. C.; Cohen, R. C.

    2010-10-01

    We examine the interannual variability in the NO2 column over North America measured by the Ozone Monitoring Instrument (OMI) in 2005-2008. By comparison to a model of soil NOx emissions driven by the North American Regional Reanalysis precipitation and 0-10 cm soil temperature fields, we show the source of this observed interannual variability over much of the central United States in June is fertilizer application. We find that dry, warm conditions followed by convective precipitation induces pulsed emissions of NOx over the agricultural Great Plains. In June 2006 we infer a 50% increase in soil NOx emission and a 30% increase in the tropospheric NO2 column relative to the June 2005-2008 mean. In a case-study of fertilized corn and soybean fields over SE South Dakota, we find an associated rain-induced pulsing event reaching 4.6×1015 molec cm-2, equivalent to a surface concentration of ~2 ppbv. We calculate that soil NOx emissions resulted in a mean daily maximum 8-h ozone enhancement over the agricultural Great Plains of 5 ppbv in June 2006 (with predicted events reaching 16 ppbv) compared with a mean enhancement of 3 ppbv for soil NOx in the years 2005-2008.

  11. Soil internal drainage: temporal stability and spatial variability in succession bean-black oat

    Science.gov (United States)

    Salvador, M. M. S.; Libardi, P. L.; Moreira, N. B.; Sousa, H. H. F.; Neiverth, C. A.

    2012-04-01

    There are a variety of studies considering the soil water content, but those who consider the flow of water, which are translated by deep drainage and capillary rise are scarce, especially those who assess their spatio-temporal variability, due to its laborious obtaining. Large areas have been considered homogeneous, but show considerable spatial variability inherent in the soil, causing the appearance of zones of distinct physical properties. In deep, sandy soils where the groundwater level is far below the root zone of interference, internal drainage is one of the factors limiting the supply of water to the soil surface, and possibly one of the biggest factors that determines what kinds satisfactory development of plants present in a given landscape. The forms of relief may also be indicators of changes in soil properties, because this variability is caused by small changes that affect the slope of the pedogenetic processes and the transport and storage of water in the soil profile, i.e., the different trajectories of water flow in different forms of the landscape, is the cause of variability. The objectives of this research were: i) evaluate the spatial and temporal stability of internal soil water drainage in a place near and another distant from the root system in a bean-black-oat succession and ii) verify their spatial variability in relation to relief. With the hydraulic conductivity obtained by the instantaneous profile method and the total potential gradient obtained from the difference in readings of tensiometers installed at depths of 0.35 and 0.45 and 0.75 and 0.85 m in 60 sampling points totaling 1680 and 1200 observations during the cultivation of beans and oats, respectively, was obtained so the internal drainage / capillary rise through the Darcy-Buckingham equation. To evaluate the temporal stability the method used was the relative difference and Spearman correlation test and the spatial variability was analyzed as geostatistical methodology

  12. Spatial aggregation for crop modelling at regional scales: the effects of soil variability

    Science.gov (United States)

    Coucheney, Elsa; Villa, Ana; Eckersten, Henrik; Hoffmann, Holger; Jansson, Per-Erik; Gaiser, Thomas; Ewert, Franck; Lewan, Elisabet

    2017-04-01

    Modelling agriculture production and adaptation to the environment at regional or global scale receives much interest in the context of climate change. Process-based soil-crop models describe the flows of mass (i.e. water, carbon and nitrogen) and energy in the soil-plant-atmosphere system. As such, they represent valuable tools for predicting agricultural production in diverse agro-environmental contexts as well as for assessing impacts on the environment; e.g. leaching of nitrates, changes in soil carbon content and GHGs emissions. However, their application at regional and global scales for climate change impact studies raises new challenges related to model input data, calibration and evaluation. One major concern is to take into account the spatial variability of the environmental conditions (e.g. climate, soils, management practices) used as model input and because the impacts of climate change on cropping systems depend strongly on the site conditions and properties (1). For example climate change effects on yield can be either negative or positive depending on the soil type (2). Additionally, the use of different methods of upscaling and downscaling adds new sources of modelling uncertainties (3). In the present study, the effect of aggregating soil input data by area majority of soil mapping units was explored for spatially gridded simulations with the soil-vegetation model CoupModel for a region in Germany (North Rhine-Westphalia, NRW). The data aggregation effect (DAE) was analysed for wheat yield, water drainage, soil carbon mineralisation and nitrogen leaching below the root zone. DAE was higher for soil C and N variables than for yield and drainage and were strongly related to the spatial coverage of specific soils within the study region. These 'key soils' were identified by a model sensitivity analysis to soils present in the NRW region. The spatial aggregation of the key soils additionally influenced the DAE. Our results suggest that a spatial

  13. Variability of soil fertility properties in areas planted to sugarcane in the State of Goias, Brazil

    Directory of Open Access Journals (Sweden)

    José Avelino Cardoso

    2014-04-01

    Full Text Available Soil sampling should provide an accurate representation of a given area so that recommendations for amendments of soil acidity, fertilization and soil conservation may be drafted to increase yield and improve the use of inputs. The aim of this study was to evaluate the variability of soil fertility properties of Oxisols in areas planted to sugarcane in the State of Goias, Brazil. Two areas of approximately 8,100 m² each were selected, representing two fields of the Goiasa sugarcane mill in Goiatuba. The sugarcane crop had a row spacing of 1.5 m and subsamples were taken from 49 points in the row and 49 between the row with a Dutch auger at depths of 0.0-0.2 and 0.2-0.4 m, for a total of 196 subsamples for each area. The samples were individually subjected to chemical analyses of soil fertility (pH in CaCl2, potential acidity, organic matter, P, K, Ca and Mg and particle size analysis. The number of subsamples required to compose a sample within the acceptable ranges of error of 5, 10, 20 and 40 % of each property were computed from the coefficients of variation and the Student t-value for 95 % confidence. The soil properties under analysis exhibited different variabilities: high (P and K, medium (potential acidity, Ca and Mg and low (pH, organic matter and clay content. Most of the properties analyzed showed an error of less than 20 % for a group of 20 subsamples, except for P and K, which were capable of showing an error greater than 40 % around the mean. The extreme variability in phosphorus, particularly at the depth of 0.2-0.4 m, attributed to banded application of high rates of P fertilizers at planting, places limitations on assessment of its availability due to the high number of subsamples required for a composite sample.

  14. Predicting infectivity of Arbuscular Mycorrhizal fungi from soil variables using Generalized Additive Models and Generalized Linear Models

    Directory of Open Access Journals (Sweden)

    IRNANDA AIKO FIFI DJUUNA

    2010-07-01

    Full Text Available Djuuna IAF, Abbott LK, Van Niel K (2010 Predicting infectivity of Arbuscular Mycorrhizal fungi from soil variables using Generalized Additive Models and Generalized Linear Models. Biodiversitas 11: 145-150. The objective of this study was to predict the infectivity of arbuscular mycorrhizal fungi (AM fungi, from field soil based on soil properties and land use history using generalized additive models (GAMs and generalized linear models (GLMs. A total of 291 soil samples from a farm in Western Australia near Wickepin were collected and used in this study. Nine soil properties, including elevation, pH, EC, total C, total N, P, K, microbial biomass carbon, and soil texture, and land use history of the farm were used as independent variables, while the percentage of root length colonized (%RLC was used as the dependent variable. GAMs parameterized for the percent of root length colonized suggested skewed quadratic responses to soil pH and microbial biomass carbon; cubic responses to elevation and soil K; and linear responses to soil P, EC and total C. The strength of the relationship between percent root length colonized by AM fungi and environmental variables showed that only elevation, total C and microbial biomass carbon had strong relationships. In general, GAMs and GLMs models confirmed the strong relationship between infectivity of AM fungi (assessed in a glasshouse bioassay for soil collected in summer prior to the first rain of the season and soil properties.

  15. Water storage variability in a vineyard soil in the southern highlands of Santa Catarina state

    Directory of Open Access Journals (Sweden)

    Rodrigo Vieira Luciano

    2014-02-01

    Full Text Available In the subtropical regions of southern Brazil, rainfall distribution is uneven, which results in temporal variability of soil water storage. For grapes, water is generally available in excess and water deficiency occurs only occasionally. Furthermore, on the Southern Plateau of Santa Catarina, there are differences in soil properties, which results in high spatial variability. These two factors affect the composition of wine grapes. Spatio-temporal analyses are therefore useful in the selection of cultural practices as well as of adequate soils for vineyards. In this way, well-suited areas can produce grapes with a more appropriate composition for the production of quality wines. The aim of this study was to evaluate the spatio-temporal variability of water storage in a Cambisol during the growth cycle of a Cabernet Sauvignon vineyard and its relation to selected soil properties. The experimental area consisted of a commercial 8-year-old vineyard in São Joaquim, Santa Catarina, Brazil. A sampling grid with five rows and seven points per row, spaced 12 m apart, was outlined on an area of 3,456 m². Soil samples were collected with an auger at these points, 0.30 m away from the grapevines, in the 0.00-0.30 m layer, to determine gravimetric soil moisture. Measurements were taken once a week from December 2008 to April 2009, and every two weeks from December 2009 to March 2010. In December 2008, undisturbed soil samples were collected to determine bulk density, macro- and microporosity, and disturbed samples were used to quantify particle size distribution and organic carbon content. Results were subjected to descriptive analysis and semivariogram analysis, calculating the mean relative difference and the Pearson correlation. The average water storage in a Cambisol under grapevine on ridges had variable spatial dependence, i.e., the lower the average water storage, the higher the range of spatial dependence. Water storage had a stable spatial

  16. Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface

    DEFF Research Database (Denmark)

    Kristensen, Andreas Houlberg; Poulsen, Tjalfe; Mortensen, Lars

    2010-01-01

    Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused...... on the shallow unsaturated zone. Based on a data set comprising analysis of about 100 soil samples taken in a 16-m-deep unsaturated zone polluted with volatile petroleum compounds, we statistically and geostatistically analyzed values of essential soil properties. The subsurface of the site was highly layered...

  17. Addressing Geographic Variability in the Comparative Toxicity Potential of Copper and Nickel in Soils

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Rosenbaum, Ralph K.; Huijbregts, Mark A. J.;

    2013-01-01

    in the soil was introduced into the definition of CTP. Geographic differences in fate, accessibility, bioavailability, and terrestrial toxicity were assessed by combining the USEtox characterization model, empirical regression models, and terrestrial biotic ligand models. The median CTPs for Cu and Ni with 95...... the fate and bioavailability of Cu in soils. In contrast, the geographic variability of 3 orders of magnitude in the CTP of Ni can mainly be explained by differences in pore water concentration of magnesium (Mg2+). Mg2+ competes with Ni2+ for binding to biotic ligands, influencing the toxicity. Our...

  18. Factors controlling spatial variability of DOC concentrations in soil solution at European level

    Science.gov (United States)

    Camino Serrano, Marta; Janssens, Ivan; Luyssaert, Sebastiaan; Gielen, Bert; Guenet, Bertrand; De Vos, Bruno; Ciais, Philippe

    2013-04-01

    The lateral transport of dissolved organic carbon (DOC) is an important and not well-understood process linking terrestrial and aquatic ecosystems. Up to day very few Earth System Models (ESMs) represent explicitly this process despite its crucial role in the global carbon cycle. However, to be able to integrate DOC leaching in ESMs, more accurate information is needed in order to better understand and predict DOC dynamics. DOC concentrations mainly vary by geographical location, soil and vegetation types, topography, season and climate. Within this framework, a database was designed to compile data on DOC in soil solution at different depths in different ecosystems around the world, with special focus on European sites. The database contains information on 349 sites, with 304 being forest, gathered from published literature and datasets accessible on the internet. A substantial dataset was provided by International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). The database also includes other meta-data related to the sites, such as land cover, soil properties, climate, annual water balance and other soil solution parameters. The analysis of the database has been focused on: 1) the study of the environmental and physical factors that are acting as drivers of DOC concentrations changes in soil solution across sites at European level , and 2) the DOC distribution through the soil profile and how this varies with different vegetation types and soil properties. The preliminary results show that variables related to biological processes (Dry weight of the organic layer, for example) are the most important in explaining the spatial distribution of the DOC concentration in soil solution at the European scale. However, the interactions between variables are complex and we will need further analysis in order to draw more robust conclusions. With regards to the vertical profile of DOC, we found that there is a

  19. Variability in the mobilization of sediment and phosphorus across 13 European soils.

    Science.gov (United States)

    Miller, Nicola; Quinton, John N; Barberis, Elisabetta; Presta, Manuela

    2009-01-01

    The objectives of this study were to examine the variability in mobilization and transport of primary particles and associated total phosphorus (TP) in sediments eroded by overland flow from 13 European arable soils and to consider the empirical support for more process-based alternatives to modeling phosphorus (P) transfers. The 13 soils were subjected to simulated rainfall in laboratory experiments. Rainfall was applied to a soil flume (0.5 x 0.25 m) for 30 min at intensity of 60 mm h(-1), and all overland flow generated during this period was collected. Two simulations were performed 5 d apart. The soils generated a wide range of overland flow (13.3-26.9 mm) and sediment (1.1-16.9 g). The sediments from the experiments were enriched with medium silt particles (6-20 mum). Except for one soil in the second simulation, all of the study soils produced overland flow sediments (OFS) that were enriched with P (TP 976-3884 mg kg(-1), P enrichment ratio 0.92-4.42). Sediment TP was positively correlated (P modeling of P transport in overland flow is to be successful at small scales.

  20. Agriculture at the Edge: Landscape Variability of Soil C Stocks and Fluxes in the Tropical Andes

    Science.gov (United States)

    Riveros-Iregui, D. A.; Peña, C.

    2015-12-01

    Paramos, or tropical alpine grasslands occurring right above the forest tree-line (2,800 - 4,700 m), are among the most transformed landscapes in the humid tropics. In the Tropical Andes, Paramos form an archipelago-like pattern from Northern Colombia to Central Peru that effectively captures atmospheric moisture originated in the Amazon-Orinoco basins, while marking the highest altitude capable of sustaining vegetation growth (i.e., 'the edge'). This study investigates the role of land management on mediating soil carbon stocks and fluxes in Paramo ecosystems of the Eastern Cordillera of Colombia. Observations were collected at a Paramo site strongly modified by land use change, including active potato plantations, pasture, tillage, and land abandonment. Results show that undisturbed Paramos soils have high total organic carbon (TOC), high soil water content (SWC), and low soil CO2 efflux (RS) rates. However, Paramo soils that experience human intervention show lower TOC, higher and more variable RS rates, and lower SWC. This study demonstrates that changes in land use in Paramos affect differentially the accumulation and exchange of soil carbon with the atmosphere and offers implications for management and protection strategies of what has been deemed the fastest evolving biodiversity ecosystem in the world.

  1. Spatial Variability of Soil Organic Carbon in a Watershed on the Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Yun-Qiang; ZHANG Xing-Chang; ZHANG Jing-Li; LI Shun-Ji

    2009-01-01

    Soil organic carbon (SOC) has great impacts on global warming,land degradation and food security.Classic statistical and geostatistical methods were used to characterize and compare the spatial heterogeneity of SOC and related factors,such as topography,soil type and land use,in the Liudaogou watershed on the Loess Plateau of North China.SOC concentrations followed a log-normal distribution with an arithmetic and geometric means of 23.4 and 21.3 g kg-1,respectively,were moderately variable (CV=75.9%),and demonstrated a moderate spatial dependence according to the nugget ratio (34.7%).The experimental variogram of SOC was best-fitted by a spherical model,after the spatial outliers had been detected and subsequently eliminated.Lower SOC concentrations were associated with higher elevations.Warp soils and farmland had the highest SOC concentrations,while aeolian sand soil and shrublands had the lowest SOC values.The geostatistical characteristics of SOC for the different soil and land use types were different.These patterns were closely related to the spatial structure of topography,and soil and land use types.

  2. Spatial Variability of Soil Carbon Stocks in a Subtropical Mangrove in Hong Kong

    Science.gov (United States)

    Lai, D. Y. F.; Neogi, S.; Law, M. S. M.; Xu, J.; Glatzel, S.; Buczko, U.; Karstens, S.

    2015-12-01

    "Blue carbon", a term used for carbon (C) sequestered in vegetated coastal wetlands, has received increasing attention recently as a potential option for mitigating future climate change. While coastal mangrove is considered as one of the most carbon-rich ecosystems of the world, there is a need to better characterize and compare the magnitude of carbon storage among mangroves in different geographical regions. In this study, we quantified the spatial variability of soil carbon stocks in a subtropical mangrove wetland in Hong Kong, and examined the effects of land cover change on soil carbon storage. Bare mudflats contained significantly lower amount of carbon than mangroves in the top 1 m soils (94.7 vs. 130.7-163.8 Mg C ha-1), indicating the importance of vegetation in enhancing C sequestration. Moreover, we observed higher soil C storage in sites dominated by Avicennia marina than those dominated by Kandelia obovata. Conversion of natural mangroves into freshwater marshes and brackish ponds with shallow islands significantly reduced the amount of C stored in the top 30 cm soils by 24-58%, when compared to sites dominated by mangrove trees. Our findings suggest that consideration should be given to plant species and land cover type in determining the overall magnitude of carbon stocks in subtropical mangrove soils.

  3. Spatial variability of microbial biomass and organic matter labile pools in a haplic planosol soil

    Directory of Open Access Journals (Sweden)

    Diego Campana Loureiro

    2010-01-01

    Full Text Available The objective of this work was to study the spatial variability of soil microbial biomass (SMB and labile soil organic matter pools (labile SOM, under different management systems and plant cover. The experiment was conducted in a Haplic Planosol soil on an Integrated Agroecological Production System (SIPA, in Seropédica, Rio de Janeiro. The evaluated management systems were: alley cropping, pasture, and bush garden, the late one was used as reference area. Three grids of regular spacing of 2.5 x 2.5 meters were used for sampling, consisting of 25 georeferenced points each, where soil samples were taken at 0-10 cm depth. The following labile constituents of soil organic matter were determined: free light fraction (FLF, water soluble C and N, C and N of SMB (SMB-C and SMB-N, and glomalin content. The textural fractions (sand, silt, and clay, pH in water, and chemical attributes (organic C, total N, Ca, Mg, Al, P, K, and CEC-cation exchange capacity were also determined. The areas of alley cropping and pasture showed spatial dependence to the attributes of SOM. The occurrence of high spatial dependence for the attributes associated to microbial biomass in the alley cropping system (C, FLF, SMB-N and respiration, probably was due to external factors related to management, such as: intensive rotational cropping system, diversity of crops and different inputs of organic matter to soil such as pruning material and organic compost.

  4. Iodine and selenium in natural water, their fixation on geochemical barriers in soils and rocks and explanation of I and Se behavior in water-solid phase system using thermodynamic modeling

    Science.gov (United States)

    Korobova, Elena; Ryzhenko, Boris; Cherkasova, Elena; Sedykh, Ivelina; Korsakova, Nadezhda; Berezkin, Victor; Kolmykova, Lyudmila; Danilova, Valentina; Khushvakhtova, Sabzbakhor

    2014-05-01

    Iodine and selenium are essential for normal functioning of thyroid gland. Their natural deficiency in areas subjected to radioiodine contamination during nuclear tests and accidents may increase the risk of thyroid cancer among the most sensitive groups of population. Deficiency is caused by both the low abundance of microelements in the environmental components of the local food chain and their fixation on geochemical barriers due to such processes as chemical transformation, sorption, chemisorption, complexing. The studies of iodine and selenium distribution in soils, herbs and drinking water in rural settlements of the Bryansk oblast' confirmed low level of iodine and selenium content in local soils, plants and water and revealed different character of their distribution in soils and waters formed in geochemically different conditions of water migration in areas of fluvioglacial, moraine and loess-like soil forming rocks (the polesje, moraine and opolje landscapes correspondingly). Iodine content in top horizons of the soils developed on loess-like sediments and rich in organic matter was considerably higher as compared to those formed on sandy moraine or fluvioglacial sediments. For selenium the difference was not pronounced. Iodine was noted for positive correlation with Corg and fixation in the soil profile on carbonate barrier. A negative correlation was found between selenium content in grasses and in topsoil of subordinated elementary landscapes characterized by waterlogged and reduction conditions in soils. Thermodynamic modeling performed for 47 water samples on the basis of their chemical composition helped to explain the established patterns of iodine and selenium behavior in soil-water system. It demonstrated the possibility of existence of CaI+ and MgI+ complexes in water and sedimentation of FeSe(cr) in presence of a considerable amount of Fe2+. Iodine complexation with Ca and Mg ions may explain its further fixation on carbonate barrier in soils

  5. Spatial and temporal variability of soil moisture in a restored reach of an Alpine river

    Science.gov (United States)

    Luster, Jörg

    2010-05-01

    In order to assess the effects of river restoration on water quality, the biogeochemical functions of restored river reaches have to be quantified, and soil moisture is a key environmental variable controlling this functionality. Restored sections of rivers often are characterized by a dynamic mosaic of riparian zones with varying exposure to flooding. In this presentation, the spatial and temporal variability of soil moisture in riparian soils of a restored reach of the Alpine river Thur in northeastern Switzerland is shown. The study was part of the interdisciplinary project cluster RECORD, which was initiated to advance the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The studied river reach comprised the following three functional processing zones (FPZ) representing a lateral successional gradient with decreasing hydrological connectivity (i.e. decreasing flooding frequency and duration). (i) The grass zone developed naturally on a gravel bar after restoration of the channelized river section (mainly colonized by canary reed grass Phalaris arundinacae). The soil is loamy sand to sandy loam composed of up to 80 cm thick fresh sediments trapped and stabilized by the grass roots. (ii) The bush zone is composed of young willow trees (Salix viminalis) planted during restoration to stabilize older overbank deposits with a loamy fine earth. (iii) The mixed forest is a mature riparian hardwood forest with ash and maple as dominant trees developed on older overbank sediments with a silty loamy fine earth. The study period was between spring 2009 and winter 2009/2010 including three flood events in June, July and December 2009. The first and third flood inundated the grass zone and lower part of the bush zone while the second flood was bigger and swept through all the FPZs. Water contents in several soil depths were measured continuously in 30 minute intervals using Decagon EC-5 and EC-TM sensors. There were six spatial

  6. Variability in apparent soil organic carbon turnover times across climate zones and vegetation classes

    Science.gov (United States)

    Khomik, M.; Reichstein, M.; Schrumpf, M.; Beer, C.; Curiel Yuste, J.; Janssens, I.; Luyssaert, S.; Subke, J.; Trumbore, S.; Wutzler, T.; Fluxnet Lathuile: Www. Fluxdata. Org

    2011-12-01

    Our understanding about the climatic controls on the rate of soil organic carbon (SOC) decomposition is still limited and greatly debated, especially the temperature sensitivity of SOC decomposition. Some argue that SOC turnover time (TO) decreases exponentially with increasing temperatures, while others disagree. Based on a number of assumptions, we calculated the ratio between soil CO2 efflux and soil bulk carbon stocks, from which we obtained an estimate of apparent TO for bulk soils across a selection of forested sites around the globe. We used data collected from site-PIs and from recently-available databases of: soil chamber flux measurements (Global soil respiration database: code.google.com/p/srdb/), ecosystem carbon flux measurements (FLUXNET LaThuile dataset: www.fluxdata.org), and global soil carbon stock estimates (Harmonized world soil database: www.iiasa.ac.at/Research/LUC/External-World-soil-database/HTML/). We investigated across-site variability of these apparent TO values in relation to climate (i.e. site's mean annual temperature, MAT, and total annual precipitation, TAP) and vegetation classes (i.e. broadleaf deciduous, needle-leaf deciduous, broadleaf evergreen, and needle-leaf evergreen). We found that, when all data points were considered, TO decreased exponentially with increasing MAT and TAP, in accordance with past studies, although the relationship with TAP was not as strong as with MAT. The overall negative exponential relationship was maintained even when the data was analyzed under the combined effects of MAT and TAP and vegetation class. TO at sites with low annual precipitation and low mean annual temperatures were high (i.e. the rate of decomposition was low). However, we also found that this overall global exponential relationship was largely driven by the difference in TO between sites located in the boreal climate zone and sites located in the other climate zones considered (i.e. tropical, Mediterranean and temperate climate

  7. Geochemical distribution of harmful elements in top soils of an Italian National Interest Area (S.I.N.): the Domizio-Flegreo Littoral and Agro Aversano case study

    Science.gov (United States)

    Bove, M.; Grezzi, G.; Albanese, S.; de Vivo, B.; Lima, A.

    2009-04-01

    The Domizio-Flegreo Littoral and Agro Aversano area has been classified by the Italian Ministry of Environment (Italian Ministero dell'Ambiente e della Tutela del Territorio e del Mare) as a S.I.N. (Sito di Interesse Nazionale, L. 426/98 - Decreto 10 Gennaio 2000 - G.U. 29/5/01). In this category have been included all those contaminated lands that, both for their extension and their historical and present land use, are considered to be particularly harmful for human health. In Italy have been selected a total of 54 S.I.N.; among all of these, the Domizio-Flegreo Littoral and Agro Aversano S.I.N. is one of the widest (1564 Km2). The study area is located in north-western Campania region, from the Avella Mountain to the coastline, and from the Campi Flegrei area to the northern boundaries between Campania and Latium Regions. It includes a total of 77 towns from both Naples and Caserta provinces. The Domizio-Flegreo Littoral and Agro Aversano S.I.N. is characterized by a strongly urbanization in its internal portions, and by intensive agricultural activities in its northern and coastal portions. During past years this wide area has been the set of an unknown number of illegal activities controlled by the organized crime, including toxic waste disposal of unknown sources from different Regions of Italy, unauthorized building, intensive uncontrolled agricultural practices and so on. Part of these environmental crimes have been and are under investigations by Italian Authorities. For a geochemical characterization of this contaminated land, between May 2006 and January 2008, a total of 292 (179 in the Litorale Domizio-Flegreo and 113 in the Agro Aversano) top soils (5-15 cm depth) have been collected, with a sampling density of about 1 sample/5 Km2. The <100 mesh soil fraction has been analyzed with ICP-MS to determine the concentration of the 39 elements: Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sc, Se, Sn

  8. Basal respiration - a proxy to understand spatial variability of soil CO2 emissions in urban regions

    Science.gov (United States)

    Vasenev, Viacheslav; Stoorvogel, Jetse; Ananyeva, Nadezhda; Ivashchenko, Kristina; Vizirskaya, Marya; Valentini, Riccardo

    2015-04-01

    Soil respiration (Rs) is an important terrestrial CO2 efflux and received significant attention at different scale levels. However, the sampling density is limited and global Rs databases are biased towards natural ecosystems and towards north America and Europe. This limits our understanding of the spatial variability of Rs. The methodological constraints of direct Rs measurements in the field limit the number of observations. As an alternative approach to approximate the spatial variability of Rs, we used basal respiration (BR) as an indirect measurement. First, the direct Rs and indirect BR measurements were compared at a 10 km2 test area in Moscow city, which included adjacent forests, croplands and urban lawn plots. Rs was monitored by in situ chamber approach with an IR Li-820 gas analyzer at 50 points during the growing season (June-October 2013, 9 time repetitions per point). In the same area, 32 locations were sampled and BR was measured under controlled conditions. Rs was affected by anthropogenic disturbance with the highest values in urban lawns. BR was mainly controlled by soil organic carbon (SOC) with maximum rates in the forested area. Total variability reported by direct observations was 10% higher, than one for BR, although the spatial variability captured by both approaches was similar confirmed by significant correlation between variance coefficients (CV) of the values. This shows that BR is a relevant proxy to analyze the spatial variability of Rs. Subsequently, the sampling area was expanded to the Moscow region for which respiration was mapped using digital soil mapping techniques and BR as a proxy for Rs. Although the absolute levels of respiration remained uncertain, the spatial patterns of BR are likely to correspond well with Rs patterns. Land use largely determined the spatial heterogeneity of soil respiration. Most variation occurred in the urban areas. BR is a relevant and straightforward proxy to understand patterns of Rs especially

  9. Effect of Sulfate on Adsorption of Zinc and Cadmium by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGGANGYA; G.W.BRUMMER; 等

    1998-01-01

    SO42- and Zn2+ or Cd2+ were added to three variable charge soils in different sequences.In one sequence sulfate was added first ,and in the other,Zn2+ or Cd2+ first.The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added,with the effect more remarkable whn the soil reacted with the sulfate prior to the metal.the shift in pH50 for both Zn and Cd adsorption was aslo comparatively larger in the first sequence of reactions .It was suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd,and the formaiton of the ternary surface complex-S-SO4-M might also play a role in the effect.

  10. Trace metal pyritization variability in response to mangrove soil aerobic and anaerobic oxidation processes.

    Science.gov (United States)

    Machado, W; Borrelli, N L; Ferreira, T O; Marques, A G B; Osterrieth, M; Guizan, C

    2014-02-15

    The degree of iron pyritization (DOP) and degree of trace metal pyritization (DTMP) were evaluated in mangrove soil profiles from an estuarine area located in Rio de Janeiro (SE Brazil). The soil pH was negatively correlated with redox potential (Eh) and positively correlated with DOP and DTMP of some elements (Mn, Cu and Pb), suggesting that pyrite oxidation generated acidity and can affect the importance of pyrite as a trace metal-binding phase, mainly in response to spatial variability in tidal flooding. Besides these aerobic oxidation effects, results from a sequential extraction analyses of reactive phases evidenced that Mn oxidized phase consumption in reaction with pyrite can be also important to determine the pyritization of trace elements. Cumulative effects of these aerobic and anaerobic oxidation processes were evidenced as factors affecting the capacity of mangrove soils to act as a sink for trace metals through pyritization processes.

  11. Compartmental modeling of PAH transport in soil column experiments under variably-saturated flow conditions

    Science.gov (United States)

    Sartori, F.; Sericano, J. L.; Wade, T. L.; Mohanty, B. P.

    2012-12-01

    Knowledge about the mobilization of polycyclic aromatic hydrocarbons (PAH) from PAH-laden soils or sediments is important to understand their bioavailability, and ultimately assess the environmental risk of PAH transport from surface soils into the groundwater. The transport and kinetics of three PAH from a spiked soil layer (2-3 cm soil depth), Phenanthrene-d10 (1900 ng/g), Naphthalene-d8 (1500 ng/g), and Pyrene-d10 (1800 ng/g), were investigated by performing a series of 8 rainfall events during 25 days in two large, replicate soil columns (length: 35 cm; diameter: 14.5 cm; 1 Pore Volume [PV]=2.29 L) under variably-saturated flow conditions. The water-methanol displacing solutions were at volumetric fractions of 0.3 and 0.6 during day 1 (E1) through E8 and E12-E22, respectively. Soil matric potential (h) was monitored at 5-cm and 20-cm depth and volumetric water content (θ) at 12.5-cm and 27.5-cm depth. Soil solution was sampled at 5 cm- (n=46) and 27.5-cm depth (n=46), and the effluent at the bottom of the column (n=163). HYDRUS-1D was used for inverse modeling of h and θ data and to predict θ at specific times and soil depth increments. First-order kinetics, compartmental models describing the transfer of PAH from the soil compartment to the soil solution compartment (desorption) and vice versa (sorption), were used to estimate mass transfer rates (φs, sorption; φd, desorption; φe, elimination), PAH mass in each compartment, and partition coefficients (Kd). Phenanthrene breakthrough curve could be interpreted through a two-parameter, two-compartment model corresponding to the common two-site sorption model, whose parameter estimates (and 95% confidence intervals) were φd=2.72 (2.31, 3.19) PV-1 and φe=4.67 (3.82, 5.7 ) PV-1. Naphthalene breakthrough curve followed a simple one-compartment elimination model, φe=2.0 (1.9, 2.1) PV-1, and that of Pyrene a three-parameter, two-compartment model, φs=0.0454 (0.00853, 0.0603) PV-1, φd=0.165 (0.0319, 0.855) PV

  12. Solute Spreading in Variably Saturated, Spatially Heterogeneous Formations: The Role of Water Saturation and Soil Texture

    Science.gov (United States)

    Russo, David

    2017-04-01

    Solute spreading provoked by the spatial heterogeneity in the soil hydraulic properties, and expressed in terms of the macrodispersion tensor, D, plays an important role in solute transport on the field scale. Under variably saturated flow conditions, quantification of D is rather complicated inasmuch as the relevant flow parameters, which depend on the formation properties, depend also on flow-controlled attributes in a highly nonlinear fashion, which, in turn, depends on the soil texture of the formation. The situation may be further complicated when the formation contains inclusions of different soil material and its hydraulic properties follow a bimodal distribution. The present talk focuses on the quantification of D in bimodal, heterogeneous, variably saturated formations, viewed as mixtures of two populations (background soil and embedded soil) of differing spatial structures. Two distinct cases are considered; in the first case, the texture of the embedded soil is finer than that of the background soil, while the second case conists of the reverse situation. First-order, Lagrangian stochastic analyses of vadose zone transport were used to invesigate the combined effect of the texture of the embedded soil and the mean pressure head on solute spreading in these formations. Results of the first-order analysis suggest that the embedded soil material may act as a capture zone for the solute particles, and, consequently, may enhance solute spreading in a manner which depends on both the texture of the embedded soil and the mean pressure head. In the first case, when the formation is relatively wet, the capture zone stems from the fine-textured embedded soil. In the second case, when the formation is relatively dry, the capture zone stems from coarse-textured embedded soil associated with very low unsaturated conductivity, which, in turn, may divert the flow into preferential flow paths around the coarse-texture, soil inclusions. Important finding of the first

  13. Comparing measured and modelled soil carbon: which site-specific variables are linked to high stability?

    Science.gov (United States)

    Robertson, Andy; Schipanski, Meagan; Ma, Liwang; Ahuja, Lajpat; McNamara, Niall; Smith, Pete; Davies, Christian

    2016-04-01

    Changes in soil carbon (C) stocks have been studied in depth over the last two decades, as net greenhouse gas (GHG) sinks are highlighted to be a partial solution to the causes of climate change. However, the stability of this soil C is often overlooked when measuring these changes. Ultimately a net sequestration in soils is far less beneficial if labile C is replacing more stable forms. To date there is no accepted framework for measuring soil C stability, and as a result there is considerable uncertainty associated with the simulated impacts of land management and land use change when using process-based systems models. However, a recent effort to equate measurable soil C fractions to model pools has generated data that help to assess the impacts of land management, and can ultimately help to reduce the uncertainty of model predictions. Our research compiles this existing fractionation data along with site metadata to create a simplistic statistical model able to quantify the relative importance of different site-specific conditions. Data was mined from 23 published studies and combined with original data to generate a dataset of 100+ land use change sites across Europe. For sites to be included they required soil C fractions isolated using the Zimmermann et al. (2007) method and specific site metadata (mean annual precipitation, MAP; mean annual temperature, MAT; soil pH; land use; altitude). Of the sites, 75% were used to develop a generalized linear mixed model (GLMM) to create coefficients where site parameters can be used to predict influence on the measured soil fraction C stocks. The remaining 25% of sites were used to evaluate uncertainty and validate this empirical model. Further, four of the aforementioned sites were used to simulate soil C dynamics using the RothC, DayCent and RZWQM2 models. A sensitivity analysis (4096 model runs for each variable applying Latin hypercube random sampling techniques) was then used to observe whether these models place

  14. Dissolution of Aluminum in Variably Charged Soils as Affected by Low-Molecular-Weight Organic Acids

    Institute of Scientific and Technical Information of China (English)

    LI Jiu-Yu; XU Ren-Kou; JI Guo-Liang

    2005-01-01

    Low-molecular-weight (LMW) organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and Al detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of Al in the two investigated soils in the following order: citric > oxalic > malonic > malic > tartaric > salicylic > lactic > maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of Al increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-1, the dissolution of Al changed little with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L-1,the dissolution of Al increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of Al were also related to their sorption-desorption equilibrium in the soils.

  15. Maxwell's Law Based Models for Liquid and Gas Phase Diffusivities in Variably-Saturated Soil

    DEFF Research Database (Denmark)

    Mamamoto, Shoichiro; Møldrup, Per; Kawamoto, Ken

    2012-01-01

    particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against D-s,D-g and D-s,D-l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law......The gas diffusion coefficient (D-s,D-g) and solute diffusion coefficient (D-s,D-l) and their dependencies on fluid content (kappa) (equal to soil-air content theta for D-s,D-g and soil-water content epsilon for D-s,D-l) are controlling factors for gas and solute transport in variably saturated......-s,D-l). Different percolation threshold terms adopted from recent studies for gas (D-s,D-g) and solute (D-s,D-l) diffusion were applied. For gas diffusion, epsilon(th) was a function of bulk density (total porosity), while for solute diffusion theta(th) was best described by volumetric content of finer soil...

  16. Spatial variability of 137Cs in the soil of Belgrade region (Serbia

    Directory of Open Access Journals (Sweden)

    Janković-Mandić Ljiljana J.

    2014-01-01

    Full Text Available Among radionuclides in the soil deposited after Chernobyl accident, 137Cs poses considerable environmental and radiological problems because of its relatively long half-life (30.17 y, its abundance in the fallout, high mobility and similarity to potassium as the major plant nutrient. In this study the samples of undisturbed surface soil (n=250 were taken from 70 regions in Belgrade, during 2006-2010. The specific activities of 137Cs were measured by gamma-ray spectrometry. Based on obtained results external effective dose rates were calculated according to the internationally accepted activity to dose rate conversion equations. The specific activities of 137Cs were geographically mapped. The presence of 137Cs has been detected in all soil samples, with high variability of its specific activity, ranging from 3 Bq kg-1 to 87 Bq kg-1. The mean specific activity of 137Cs was 23 Bq kg-1 and the corresponding absorbed dose was 1.5 nSv h-1. The observed range reflects the inhomogeneity of the deposition process following the Chernobyl accident. It could also be attributed to topographic differences and spatial differences in physicochemical and biological soil properties, soil type and vegetation cover. The results of the present study could be valuable database for future estimations of the impact of radioactive pollution.

  17. Variable pore connectivity model linking gas diffusivity and air-phase tortuosity to soil matric potential

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda; Møldrup, Per; Schjønning, Per;

    2012-01-01

    of a variable pore connectivity factor, X, as a function of soil matric potential, expressed as pF (=log |−ψ|), for pF values ranging from 1.0 to 3.5. The new model takes the form of X = X* (F/F*)A with F = 1 + pF−1, where X* is the pore network tortuosity at reference F (F*) and A is a model parameter...... that accounts for water blockage. The X–pF relation can be linked to drained pore size to explain the lower probability of the larger but far fewer air-filled pores at lower pF effectively interconnecting and promoting gas diffusion. The model with X* = 2 and A = 0.5 proved promising for generalizing Dp....../Do predictions across soils of wide geographic contrast and yielded results comparable to those from widely used predictive models. The X–pF model additionally proved valuable for differentiating between soils (providing a unique soil structural fingerprint for each soil layer) and also between the inter...

  18. [Spatial variability and management zone of soil major nutrients in tobacco fields in Qiannan mountainous region].

    Science.gov (United States)

    Wu, De-Chuan; Luo, Hong-Xiang; Song, Ze-Min; Guo, Guang-Dong; Chen, Yong-An; Li, Yu-Xiang; Jiang, Yu-Ping; Li, Zhang-Hai

    2014-06-01

    Spatial variability and management zone of soil major nutrients in tobacco fields in Qian-nan mountainous region were analyzed using geostatistics and fuzzy c-mean algorithm. Results indicated that the level of soil organic matter (OM) was moderate, and alkalytic nitrogen (AN), available phosphorus (AP) and available potassium (AK) were rich according to tobacco soil nutrient classification standards. Coefficients of variation (CV) of OM, AN, AP and AK were moderate. Contents of OM, AN, AP and AK fitted log-normal distributions. Correlation analysis showed moderate correlations between OM and AN, AP and AK. OM and AN were best described by Gaussian semivariogram models, while AP and AK were described by exponential models. The four nutrients displayed moderate spatial autocorrelation. There were significant differences among lag distances of four soil nutrients. OM, AN, AP and AK in the majority of studied regions varied at moderate to very rich levels, and deficiencies of OM, AN, AP and AK only accounted for 0.93%, 0.53%, 0.24% and 7.91% of the total studied region, respectively. Based on the results, the studied region was divided into two management zones (MZ), namely MZ1 and MZ2, accounting for 69. 8% and 30. 2% of the studied region respectively. The soil levels of OM, AN, AP and AK in MZ1 were significantly lower than those in MZ2 (P < 0.01).

  19. Mediterranean valleys revisited: Linking soil erosion, land use and climate variability in the Northern Levant

    Science.gov (United States)

    Casana, Jesse

    2008-10-01

    This paper presents results of geomorphological and archaeological investigations undertaken in several small drainage basins in the Jebel al-Aqra region of southern Turkey. By focusing intensive archaeological settlement survey in basins where securely dated sequences of sedimentary valley fills have been recorded, spatially and temporally linked, high-resolution records of land use and soil erosion have been generated. Sedimentary data show that throughout most of the Holocene, floodplains remained rather stable, allowing deep soils to form. But in the past two millennia, probably from AD 150-700, a phase of severe soil erosion was initiated and resulted in the deposition of 3.5-5.0 m of alluvial sediments on valley floors. Archaeological and historical evidence suggest that while these areas were occupied by agrarian communities since at least 2800 BC, nearly three millennia of cultivation during the Bronze and Iron Ages had relatively little effect on soil erosion. The intensification of settlement throughout the region and the conversion of upland areas to intensive agricultural production during the Hellenistic, Roman and late Roman periods (300 BC-AD 650), however, created the necessary preconditions for severe soil erosion to occur. These data are compared against modern and paleoclimate studies of the eastern Mediterranean, which show an extremely variable precipitation regime and the effects that it can have on erosion. A 400-year lag between the initial settlement of upland areas and the first evidence of soil erosion suggest that it may have been the intersection of extreme precipitation events with particular land use conditions of the Roman and late Roman periods which worked together to drive soil erosion.

  20. Dimensioning the Irrigation Variables for Table Grape Vineyards in Litho-soils

    Directory of Open Access Journals (Sweden)

    Pasquale Campi

    2010-10-01

    Full Text Available The pedo-climatic and farm characteristics of Bari’s hinterland have allowed for the diffusion of prestigious table viticulture. The typical “tendone” vineyard structure is set up after managing the surface of the soil. The karstic nature of the region and the thermo-rainfall trend during the vegetative season impede the vineyard from producing adequately without irrigation. Given the importance of water contributions to table grapes, it is necessary to correctly measure the water variables for economic and environmental reasons. Farmers often irrigate according to “fixed” turns and volumes, against the rules of “good irrigation practice” which consider monitoring the water status of the soil or plant as a prerequisite of irrigation scheduling. During this experiment, two methods of irrigation management were compared: “fixed-turn” and “on demand”. For “on demand” irrigation, the irrigation volume is calculated on the basis of the soil water status (estimated according to the “water balance” method described in the “Paper n. 56 FAO” and the irrigation is scheduled on the basis of the experimental relationship between “pre-dawn” leaf water potential and the water available in the soil. For this comparison, data from a 2-year “on farm” experimentation, in an area typical of table grape cultivation in Southern Italy, have been used. The results obtained show that, in respect to the “fixed-turn” management, the “on demand” management allows for a 20% reduction in water volumes, without compromising production. The water balance method proved to be a promising criterion for irrigation scheduling in these shallow soils, rich in stones (litho-soils. This only held true when the depth of the soil layer explored by the root system was defined by the “equivalent depth” and not by the actual soil’s depth.

  1. Soil moisture variability over Odra watershed: Comparison between SMOS and GLDAS data

    Science.gov (United States)

    Zawadzki, Jaroslaw; Kędzior, Mateusz

    2016-03-01

    Monitoring of temporal and spatial soil moisture variability is an important issue, both from practical and scientific point of view. It is well known that passive, L-band, radiometric measurements provide best soil moisture estimates. Unfortunately as it was observed during Soil Moisture and Ocean Salinity (SMOS) mission, which was specially dedicated to measure soil moisture, these measurements suffer significant data loss. It is caused mainly by radio frequency interference (RFI) which strongly contaminates Central Europe and even in particularly unfavorable conditions, might prevent these data from being used for regional or watershed scale analysis. Nevertheless, it is highly awaited by researchers to receive statistically significant information on soil moisture over the area of a big watershed. One of such watersheds, the Odra (Oder) river watershed, lies in three European countries - Poland, Germany and the Czech Republic. The area of the Odra river watershed is equal to 118,861 km2 making it the second most important river in Poland as well as one of the most significant one in Central Europe. This paper examines the SMOS soil moisture data in the Odra river watershed in the period from 2010 to 2012. This attempt was made to check the possibility of assessing, from the low spatial resolution observations of SMOS, useful information that could be exploited for practical aims in watershed scale, for example, in water storage models even while moderate RFI takes place. Such studies, performed over the area of a large watershed, were recommended by researchers in order to obtain statistically significant results. To meet these expectations, Centre Aval de Traitement des Donnes SMOS (CATDS), 3-days averaged data, together with Global Land Data Assimilation System (GLDAS) National Centers for Environmental Prediction/Oregon State University/Air Force/Hydrologic Research Lab (NOAH) model 0.25 soil moisture values were used for statistical analyses and mutual

  2. Alaskan soil carbon stocks: spatial variability and dependence on environmental factors

    Directory of Open Access Journals (Sweden)

    U. Mishra

    2012-09-01

    Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were found to be land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth system models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high-resolution mapping of soil carbon stock reveals the

  3. Variability of soil physical indicators imposed by beech and hornbeam individual trees in a local scale

    Directory of Open Access Journals (Sweden)

    YAHYA KOOCH

    2013-04-01

    Full Text Available Kooch Y, SM Hosseini, Hojjati SM, Fallah A. 2013. Variability of soil physical indicators imposed by beech and hornbeam individual trees in a local scale. Biodiversitas 14: 25-30. The objective of our study was to determine if soil physical indicators could be related to the influence of the individual trees in stands of mixed species growing on steep slopes in the Hyrcanian forests of Iran. Research was conducted in a forest dominated by beech (Fagus orientalis Lipsky and hornbeam (Carpinus betulus L. interspread with the other deciduous tree species. Due to, twenty hectare areas of Experimental Forest Station of Tarbiat Modares University was considered in northern Iran. The positions of trees with diameter at breast height more than 45cm were recorded by Geographical Position System (GPS. Three single-trees (trees with canopy cover separated from other trees and covered distinguished space considered for soil sampling from every tree species and diameter class as three replications. All of soil samples were excavated in north aspect and at the nearest point to tree collar for more precision. Soil samples were taken at 0-15, 15-30 and 30-45cm depths using auger soil sampler with 81cm2 cross section. The result of this research showed that bulk density was significantly greater under beech than under hornbeam. This character tends to be less in 0-15cm depth than in 15-30cm and 30-45cm depths. Variable amounts of this character were found among diameter classes of beech and hornbeam also. Silt and clay were significantly greater under hornbeam than under beech. Moisture was significantly higher under beech than under hornbeam, whereas soil depths and diameter classes did not show any significant difference. Current research has shown that the influence of individual trees with different diameter classes can be detected in forest floors and upper minerals soil layers even under mixed stands in steepy sloping landscapes. This subject should be

  4. Alaskan soil carbon stocks: spatial variability and dependence on environmental factors

    Directory of Open Access Journals (Sweden)

    U. Mishra

    2012-05-01

    Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially-resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were: land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth System Models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high resolution mapping of soil carbon stock reveals the potential

  5. National Geochemical Database: Sediment

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemical analysis of sediment samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are of stream sediment in...

  6. National Geochemical Database: Sediment

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemical analysis of sediment samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are of stream sediment...

  7. Fine scale spatial variability of microbial pesticide degradation in soil: scales, controlling factors, and implications

    Directory of Open Access Journals (Sweden)

    Arnaud eDechesne

    2014-12-01

    Full Text Available Pesticide biodegradation is a soil microbial function of critical importance for modern agriculture and its environmental impact. While it was once assumed that this activity was homogeneously distributed at the field scale, mounting evidence indicates that this is rarely the case. Here, we critically examine the literature on spatial variability of pesticide biodegradation in agricultural soil. We discuss the motivations, methods, and main findings of the primary literature. We found significant diversity in the approaches used to describe and quantify spatial heterogeneity, which complicates inter-studies comparisons. However, it is clear that the presence and activity of pesticide degraders is often highly spatially variable with coefficients of variation often exceeding 50% and frequently displays nonrandom spatial patterns. A few controlling factors have tentatively been identified across pesticide classes: they include some soil characteristics (pH and some agricultural management practices (pesticide application, tillage, while other potential controlling factors have more conflicting effects depending on the site or the pesticide. Evidence demonstrating the importance of spatial heterogeneity on the fate of pesticides in soil has been difficult to obtain but modelling and experimental systems that do not include soil’s full complexity reveal that this heterogeneity must be considered to improve prediction of pesticide biodegradation rates or of leaching risks. Overall, studying the spatial heterogeneity of pesticide biodegradation is a relatively new field at the interface of agronomy, microbial ecology, and geosciences and a wealth of novel data is being collected from these different disciplinary perspectives. We make suggestions on possible avenues to take full advantage of these investigations for a better understanding and prediction of the fate of pesticides in soil.

  8. The contribution of hydroxylamine content to spatial variability of N2O formation in soil of a Norway spruce forest

    Science.gov (United States)

    Liu, Shurong; Herbst, Michael; Bol, Roland; Gottselig, Nina; Pütz, Thomas; Weymann, Daniel; Wiekenkamp, Inge; Vereecken, Harry; Brüggemann, Nicolas

    2016-04-01

    Hydroxylamine (NH2OH), a reactive intermediate of several microbial nitrogen turnover processes, is a potential precursor of nitrous oxide (N2O) formation in the soil. However, the contribution of soil NH2OH to soil N2O emission rates in natural ecosystems is unclear. Here, we determined the spatial variability of NH2OH content and potential N2O emission rates of organic (Oh) and mineral (Ah) soil layers of a Norway spruce forest, using a recently developed analytical method for the determination of soil NH2OH content, combined with a geostatistical Kriging approach. Potential soil N2O emission rates were determined by laboratory incubations under oxic conditions, followed by gas chromatographic analysis and complemented by ancillary measurements of soil characteristics. Stepwise multiple regressions demonstrated that the potential N2O emission rates, NH2OH and nitrate (NO3-) content were spatially highly correlated, with hotspots for all three parameters observed in the headwater of a small creek flowing through the sampling area. In contrast, soil ammonium (NH4+) was only weakly correlated with potential N2O emission rates, and was excluded from the multiple regression models. While soil NH2OH content explained the potential soil N2O emission rates best for both layers, also NO3- and Mn content turned out to be significant parameters explaining N2O formation in both soil layers. The Kriging approach was improved markedly by the addition of the co-variable information of soil NH2OH and NO3- content. The results indicate that determination of soil NH2OH content could provide crucial information for the prediction of the spatial variability of soil N2O emissions.

  9. The methods of geomorphometry and digital soil mapping for assessing spatial variability in the properties of agrogray soils on a slope

    Science.gov (United States)

    Gopp, N. V.; Nechaeva, T. V.; Savenkov, O. A.; Smirnova, N. V.; Smirnov, V. V.

    2017-01-01

    The relationships between the morphometric parameters (MPs) of topography calculated on the basis of digital elevation model (ASTER GDEM, 30 m) and the properties of the plow layer of agrogray soils on a slope were analyzed. The contribution of MPs to the spatial variability of the soil moisture reached 42%; to the content of physical clay (digital soil mapping. The regression analysis showed statistically significant correlations between the properties of the plow layer and the MPs describing surface runoff, geometric forms of surface, and the soil temperature regime.

  10. Evaluating Genetic Variability of Sorghum Mutant Lines Tolerant to Acid Soil

    Directory of Open Access Journals (Sweden)

    W. Puspitasari

    2012-12-01

    Full Text Available High rainfall in some parts in Indonesia causes soil become acidic. The main constraint of acid soil is phosphor (P deficiency and aluminum (Al toxicity which decrease plant productivity. To overcome this problem, it is important to develop a crop variety tolerant to such conditions. Sorghum is probably one of the potential crops to meet that objective. Sorghum has been reported to have wide adaptability to various agro-ecology and can be used as food and animal feed. Unfortunately, sorghum is not Indonesian origin so its genetic variability is still low. From previous breeding works with induced mutation, some promising mutant lines have been developed. These mutant lines were included in the experiment carried out in Tenjo with soil condition was classified as acid soil with pH 4.8 and exchangeable-Al content 2.43 me/100 g. The objectives of this experiment were to study the magnitude of genetic variability of agronomy and grain quality characters in sorghum in order to facilitate the breeding improvement of the species. Plant materials used in this study were ten genotypes, including 6 mutant lines and 4 control varieties. The randomized block design with three replications was used in the experiment. The genetic variabilities of agronomic and grain quality characters existed among genotypes, such as plant height, number of leaves, stalk diameter, biomass weight, panicle length, grain yield per plant, 100 seed weight and tannin content in the grain. The broad sense heritabilities of agronomic characters were estimated ranging from medium to high. Grain yield showed significantly positive correlation with agronomic characters observed, but it was negatively correlated with protein content

  11. Evaluating Genetic Variability of Sorghum Mutant Lines Tolerant to Acid Soil

    Directory of Open Access Journals (Sweden)

    W. Puspitasari

    2012-08-01

    Full Text Available High rainfall in some parts in Indonesia causes soil become acidic. The main constraint of acid soil is phosphor (P deficiency and aluminum (Al toxicity which decrease plant productivity. To overcome this problem, it is important to develop a crop variety tolerant to such conditions. Sorghum is probably one of the potential crops to meet that objective. Sorghum has been reported to have wide adaptability to various agro-ecology and can be used as food and animal feed. Unfortunately, sorghum is not Indonesian origin so its genetic variability is still low. From previous breeding works with induced mutation, some promising mutant lines have been developed. These mutant lines were included in the experiment carried out in Tenjo with soil condition was classified as acid soil with pH 4.8 and exchangeable-Al content 2.43 me/100 g. The objectives of this experiment were to study the magnitude of genetic variability of agronomy and grain quality characters in sorghum in order to facilitate the breeding improvement of the species. Plant materials used in this study were ten genotypes, including 6 mutant lines and 4 control varieties. The randomized block design with three replications was used in the experiment. The genetic variabilities of agronomic and grain quality characters existed among genotypes, such as plant height, number of leaves, stalk diameter, biomass weight, panicle length, grain yield per plant, 100 seed weight and tannin content in the grain. The broad sense heritabilities of agronomic characters were estimated ranging from medium to high. Grain yield showed significantly positive correlation with agronomic characters observed, but it was negatively correlated with protein content

  12. Field scale variability of solute transport parameters and related soil properties

    Directory of Open Access Journals (Sweden)

    B. Lennartz

    1997-01-01

    Full Text Available The spatial variability of transport parameters has to be taken into account for a reliable assessment of solute behaviour in natural field soils. Two field sites were studied by collecting 24 and 36 small undisturbed soil columns at an uniform grid of 15 m spacing. Displacement experiments were conducted in these columns with bromide traced water under unsaturated steady state transport conditions. Measured breakthrough curves (BTCs were evaluated with the simple convective-dispersive equation (CDE. The solute mobility index (MI calculated as the ratio of measured to fitted pore water velocity and the dispersion coefficient (D were used to classify bromide breakthrough behaviour. Experimental BTCs were classified into two groups: type I curves expressed classical solute behaviour while type II curves were characterised by the occurrence of a bromide concentration maximum before 0.35 pore volumes of effluent (MI<0.35 resulting from preferential flow conditions. Six columns from site A and 8 from site B were identified as preferential. Frequency distributions of the transport parameters (MI and D of both sites were either extremely skewed or bimodal. Log-transformation did not lead to a normal distribution in any case. Contour maps of bromide mass flux at certain time steps indicated the clustering of preferential flow regions at both sites. Differences in the extent of preferential flow between sites seemed to be governed by soil structure. Linear cross correlations among transport parameters and independently measured soil properties revealed relations between solute mobility and volumetric soil water content at time of sampling, texture and organic carbon content. The volumetric field soil water content, a simple measure characterising the soil hydraulic behaviour at the sampling location, was found to be a highly sensitive parameter with respect to solute mobility and preferential flow situations. Almost no relation was found between solute

  13. Factors Influencing Spatial Variability in Nitrogen Processing in Nitrogen-Saturated Soils

    Directory of Open Access Journals (Sweden)

    Frank S. Gilliam

    2001-01-01

    Full Text Available Nitrogen (N saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF, West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4 and WS4 (untreated control. Samples of forest floor material (O1 horizon and mineral soil (to a 5-cm depth were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C, lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3- to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C, followed by 1 NKCl extraction and analysis for NH4+ and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of

  14. Effect of Specific Adsorption of Ions on Electrokinetic Properties of Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGHONG; ZHANGXIAO-NIAN

    1991-01-01

    Studies were carried out by using electrophoretic method on the effects of the specific adsorption of the anions,such as SO42-,PO43-,and F- ions,the cations,such as Ca2+,Mn2+,Zn2+,and Cu2+,ions,and the anions and cations coexisting,such as Zn2+ and SO42= ions,on electrokinetic properties of the red soils as typical variable charge soils in China concerning variation in the specific ion species and concentrations,with an emphasis on the interaction between soil colloid surfaces and the ions in soil solutions.The results showed that the adsorption of specific ions led to a very pronounced decrease in zeta potentials of the soil colloids and a shift of the IEPs to lower values for specific anions,and an obvious increase in zeta potentials of the soil colloids and a shift of the IEPs to higher values for specific cations.Under circumstances of the specific anions and cations coexisting,for instance,Zn2+ and SO42- ions,the zeta potentials changed with values higher than the value for SO42- alone and lower than that for Zn2+ alone,and the IEP was between that for Zn2+ and that for SO42-.The adsorption of Zn2+ and Cu2+ ions resulted in a reversal of the zeta potentials,and appearance of two IEPs for Zn2+ and no IEP for Cu2+,exhibiting interesting special effects of these kinds of metal ions.The higher the concentrations of the ions,the greater the change of the electrokinetic properties.

  15. Spatial variability of soil total and DTPA-extractable cadmium caused by long-term application of phosphate fertilizers, crop rotation, and soil characteristics.

    Science.gov (United States)

    Jafarnejadi, A R; Sayyad, Gh; Homaee, M; Davamei, A H

    2013-05-01

    Increasing cadmium (Cd) accumulation in agricultural soils is undesirable due to its hazardous influences on human health. Thus, having more information on spatial variability of Cd and factors effective to increase its content on the cultivated soils is very important. Phosphate fertilizers are main contamination source of cadmium (Cd) in cultivated soils. Also, crop rotation is a critical management practice which can alter soil Cd content. This study was conducted to evaluate the effects of long-term consumption of the phosphate fertilizers, crop rotations, and soil characteristics on spatial variability of two soil Cd species (i.e., total and diethylene triamine pentaacetic acid (DTPA) extractable) in agricultural soils. The study was conducted in wheat farms of Khuzestan Province, Iran. Long-term (27-year period (1980 to 2006)) data including the rate and the type of phosphate fertilizers application, the respective area, and the rotation type of different regions were used. Afterwards, soil Cd content (total or DTPA extractable) and its spatial variability in study area (400,000 ha) were determined by sampling from soils of 255 fields. The results showed that the consumption rate of di-ammonium phosphate fertilizer have been varied enormously in the period study. The application rate of phosphorus fertilizers was very high in some subregions with have extensive agricultural activities (more than 95 kg/ha). The average and maximum contents of total Cd in the study region were obtained as 1.47 and 2.19 mg/kg and DTPA-extractable Cd as 0.084 and 0.35 mg/kg, respectively. The spatial variability of Cd indicated that total and DTPA-extractable Cd contents were over 0.8 and 0.1 mg/kg in 95 and 25 % of samples, respectively. The spherical model enjoys the best fitting and lowest error rate to appraise the Cd content. Comparing the phosphate fertilizer consumption rate with spatial variability of the soil cadmium (both total and DTPA extractable) revealed the high

  16. The Late Pliocene mafic lavas from the Camusú Aike volcanic field (˜50°S, Argentina): Evidence for geochemical variability in slab window magmatism

    Science.gov (United States)

    D'Orazio, M.; Innocenti, F.; Manetti, P.; Haller, M. J.; Di Vincenzo, G.; Tonarini, S.

    2005-01-01

    The Camusú Aike volcanic field (CAVF), part of the discontinuous N-S-trending belt of Cenozoic mafic lava formations that occur in a backarc position along extra-Andean Patagonia, is located in southern Patagonia (˜50°S, Santa Cruz province), approximately 70 km east of the extensive Meseta de las Vizcachas and just south of the upper Río Santa Cruz valley. The CAVF volcanics cover a surface of ˜200 km 2 and occur mainly as lava flows and scoria cones. They are subdivided into two groups: Group I volcanics are high-TiO 2, low-Mg# olivine-hypersthene-normative basalts and trachybasalts that erupted at about 2.9 Ma; Group II lavas are much less abundant, more primitive basaltic andesites that erupted at about 2.5 Ma. Both groups show a within-plate geochemical signature, though it is more marked in Group I lavas. The main geochemical characteristics, age, and location of CAVF volcanics are consistent with the slab window opening model proposed by different authors for the genesis of the Miocene-Recent mafic magmatism of Patagonia south of 46.5°S. The whole-rock geochemical and Sr-Nd isotope features of Group I lavas ( 87Sr/ 86Sr=0.7035-0.7037; 143Nd/ 144Nd=0.51288-0.51291) indicate a genetic link between these lavas and the primitive basalts in southernmost Patagonia (Pali Aike volcanic field and Estancia Glencross area), which have been interpreted as melting products of an isotopically depleted asthenosphere. The relatively evolved compositions of the erupted Group I magmas are modeled by a polybaric crystal fractionation process without significant involvement of crustal contamination. The more primitive Group II lavas are strongly depleted in incompatible elements, have slightly higher (LREE+Ba+Th+U)/HFSE ratios, and have more enriched Sr-Nd isotope compositions ( 87Sr/ 86Sr≈0.7039; 143Nd/ 144Nd≈0.51277) that are more akin to the Patagonian basalts farther to the north. The most likely explanation for the geochemical features of Group II lavas is the

  17. Evaluation of spatial variability of metal bioavailability in soils using geostatistics

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Hauschild, Michael Zwicky; Rosenbaum, Ralph K.

    2012-01-01

    for different soils. Here, variography is employed to analyse spatial variability of bioavailability factors (BFs) of metals at the global scale. First, published empirical regressions are employed to calculate BFs of metals for 7180 topsoil profiles. Next, geostatistical interpretation of calculated BFs...... is performed using ArcGIS Geostatistical Analyst. Results show that BFs of copper span a range of 6 orders of magnitude, and have signifficant spatial variability at local and continental scales. The model nugget variance is signifficantly higher than zero, suggesting the presence of spatial variability...... at lags smaller than those in the data set. Geostatistical analyses indicate however, that BFs exhibit no signifficant spatial correlation at a range beyond 3200 km. Because BF is spatially correlated, its values at unsampled locations can be predicted, as demonstrated using ordinary kriggin method...

  18. Diurnal spatial variability of soil respiration estimated by ordinary kriging and sequential Gaussian simulation

    Science.gov (United States)

    de Bortoli Teixeira, Daniel; Rodrigo Panosso, Alan; Tadeu Pereira, Gener; Pelegrino Cerri, Carlos Eduardo; La Scala, Newton, Jr.

    2010-05-01

    The role of greenhouse gases in the climate change is well know, however, the balance of greenhouse gases due to land use and management is still lacking. Hence it is important to characterize the main aspects of soil respiration (or soil CO2 emission) in agricultural areas, including its spatial variability, as quantitatively as possible. The objective of this work was to study the diurnal spatial variability of the soil respiration including their estimations by different methods: ordinary kriging and sequential Gaussian simulation. Evaluations were conducted in a regular grid having 64 points installed over a bare Eutrustox clay texture during the morning and afternoon periods. Measurements were conducted from 7:30 - 10:30 am (morning) and 13:30 - 16:30 pm (afternoon) using a portable soil respiration system (LI-8100), Lincoln, NE, USA. In order to estimate the best interpolation method it was applied the so-called external validation, where the respiration values of 5 points in grid were removed from interpolation process and after were estimated in the same points by kriging or sequential Gaussian simulation methods. This evaluation was also based on the sum of the square of residues, comparing observed with predicted respiration values in each of the 5 points selected for external validation. The highest CO2 emission was observed in the afternoon period, with mean value of 6.24 µmol m-2 s-1, when compared to the morning (4.54 µmol m-2 s-1). Our results indicate that the measurement period (morning or afternoon) did not interfere into the definition of emission spatial variability structure, as coefficient of variation, spatial variability models and their parameters were quite similar in morning and afternoon. However, despite the high correlation between kriging and sequential Gaussian simulation respiration maps (R2 =0.99) sequential Gaussian simulation showed to be more efficient into the estimations of non-sampled emissions in both periods, mornings and

  19. Zn Adsorption by Variable Charge Soils in Relation to pH

    Institute of Scientific and Technical Information of China (English)

    SUNHAN-YUAN

    1993-01-01

    Zn adsorption by pure oxides or in the presence of a high concentration of inner electrolyte has been extensively studied.But,in studies on Zn adsorption in the complicated soil system,especially in variable charge soils,profound knowledge about the absorption mechanism still lacks.In this paper,taking Zn ion adsorption by two typical variable charge soils as the object of the study,author discusses the relation between Zn adsorption and pH and possible adsorption mechanisms.The results showed that in the low pH range where the amount of Zn adsorbed did not exceed 50% of Zn added,the specific adsorption was the diminant mechanism.The species of Zn specifically adsorbed was free Zn2+ ion.In the middle and high pH ranges,the mechanisms of specific and electrostatic adsorptions co-existed,accounting for about 70% and 30%,respectively.Noteworthily,in the high pH range,the hydroxyl Zn ion (ZnOH+) from Zn2+ hydrolysis probably was a preferable species for specific absorption.

  20. Spatial variability and hotspots of soil N2O fluxes from intensively grazed grassland

    Science.gov (United States)

    Cowan, N. J.; Norman, P.; Famulari, D.; Levy, P. E.; Reay, D. S.; Skiba, U. M.

    2015-03-01

    One hundred N2O flux measurements were made from an area of intensively managed grazed grassland in central Scotland using a high-resolution dynamic chamber method. The field contained a variety of features from which N2O fluxes were measured including a manure heap, patches of decaying grass silage, and areas of increased sheep activity. Individual fluxes varied significantly across the field varying from 2 to 79 000 μg N2O-N m-2 h-1. Soil samples were collected at 55 locations to investigate relationships between soil properties and N2O flux. Fluxes of N2O correlated strongly with soil NO3- concentrations. Distribution of NO3- and the high spatial variability of N2O flux across the field are shown to be linked to the distribution of waste from grazing animals and the resultant reactive nitrogen compounds in the soil which are made available for microbiological processes. Features within the field such as shaded areas and manure heaps contained significantly higher available nitrogen than the rest of the field. Although these features only represented 1.1% of the area of the field, they contributed to over 55% of the total estimated daily N2O flux.

  1. Interannual variability of plant phenology in tussock tundra: modelling interactions of plant productivity, plant phenology, snowmelt and soil thaw

    NARCIS (Netherlands)

    Wijk, van M.T.; Williams, M.; Laundre, J.A.; Shaver, G.R.

    2003-01-01

    We present a linked model of plant productivity, plant phenology, snowmelt and soil thaw in order to estimate interannual variability of arctic plant phenology and its effects on plant productivity. The model is tested using 8 years of soil temperature data, and three years of bud break data of Betu

  2. Soil salinity and acidity : spatial variabil[it]y and effects on rice production in West Africa's mangrove zone

    NARCIS (Netherlands)

    Sylla, M.

    1994-01-01

    In the mangrove environment of West Africa, high spatial and temporal variability of soil constraints (salinity and acidity) to rice production is a problem for the transfer and adoption of new agronomic techniques, for land use planning, and for soil and water management. Recently, several

  3. Spatial Variability of Salt Ions in Soils in Oasis of Delta of Weigan River-Kuqa River in Different Seasons

    Institute of Scientific and Technical Information of China (English)

    Yuanyuan XU; Tashpolat TIYIP; Fei ZHANG; Jun XIA; Guihong HAN; Mamat SAWUT

    2012-01-01

    Abstract [Objective] The aim was to research the spatial variability of salts' ions in soils of oases of Weigan River-Kuqa River to explore spatial correlation among soil ions and effects of seasonal changes on distribution of eight ions in soils. [Method] Based on soil salinizaiton, temporal and spatial distributions of eight ions in surface soils were researched and distribution maps were drawn with the help of classical statistics and geostatistics. [Result] All contents of salt ions were proved in consistent with normal distribution by K-S test, and variability of the ions changed with season, for example, variability of ions in soils in October was higher than that in April, which might be caused by little rainfall and high evaporation in October. It can be concluded from semivariance analysis that salt ions were all of high spatial autocorrelation. In addition, it can be concluded from spatial distribution that spatial structures of most ions are reasonable, except Ca2+ and Mg2' in soils collected in April of 2010 and Mg2+ in October of 2010, which were more suitable for linear model, and chloride-sulfate dominated in salinized soils in the researching area. [Conclusion] The research laid foundation for partition, improvement and use of salin- ized soils in delta of Weigan River-Kuqa River.

  4. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  5. Soil fertility dynamics in a semiarid basin: impact of scale level in weighing the effect of the landscape variables

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Navarro, A.; Barbera, G. G.; Albaladejo, J.

    2009-07-01

    Arid and semi-arid Mediterranean soils are particularly sensitive to degradation processes, and soil fertility could play important role in restoration/conservation practices. Our objective was to study the relationships between soil and landscape at different scales in order to understand the main drivers of soil fertility on a semiarid catchment. A stratified sampling plan was carried out to take soil and landscape representative variability. Multivariate statistic techniques were used to elucidate the relationship between both. The results showed that soil fertility are positively related with density of vegetation and topographical conditions favourable to soil moisture at small scale, while negatively with topographical factors that contributed erosion dynamic on ero debility lithologies at medium and large scale. (Author) 8 refs.

  6. Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

    Science.gov (United States)

    Seyfried, M. S.; Link, T. E.

    2013-12-01

    Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal

  7. Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface

    DEFF Research Database (Denmark)

    Kristensen, Andreas Houlberg; Poulsen, Tjalfe; Mortensen, Lars

    2010-01-01

    Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused...... on the shallow unsaturated zone. Based on a data set comprising analysis of about 100 soil samples taken in a 16-m-deep unsaturated zone polluted with volatile petroleum compounds, we statistically and geostatistically analyzed values of essential soil properties. The subsurface of the site was highly layered......, resulting in an accumulation of pollution within coarse sandy lenses. Air-filled porosity, readily available phosphorous, and the first-order rate constant (k1) of benzene obtained from slurry biodegradation experiments were found to depend on geologic sample characterization (P

  8. Temporal stability of soil moisture spatial variability at two scales and its implication for optimal field monitoring

    Directory of Open Access Journals (Sweden)

    X. Zhou

    2007-05-01

    Full Text Available Soil moisture spatial distribution is a key component in characterizing and modeling water movement at multiple scales. The temporal stability of soil moisture spatial distribution at multiple depths was investigated at the 7.9-ha Shale Hills Catchment in central Pennsylvania with a year-round monitoring of 77 sites distributed across the catchment. For this catchment with heterogeneous soils and landforms, integration of soils information into the temporal stability assessment provided a more accurate location of representative monitoring sites for capturing mean soil moisture. The temporal stability pattern of soil moisture at the swale scale was similar to that at the catchment scale, suggesting that the swale could be used as a representative unit in the catchment study in terms of mean soil moisture dynamics. The temporal stability of soil moisture variability in this catchment varied over space and seasons. Temporally stable sites were found in the northwestern and southeastern parts of the catchment, while the areas near the stream and some swale areas had lower temporal stability. The spatial distribution of soil moisture was more stable over time during wet seasons, but less stable during transitional periods (i.e. drying or recharging periods. The temporal stability concept helps the optimal design of field monitoring sites and sampling strategies. On the other hand, the temporally unstable sites provide insights regarding the hydrological processes behind the spatial variability of soil moisture.

  9. Simulating maize yield and bomass with spatial variability of soil field capacity

    Science.gov (United States)

    Ma, Liwang; Ahuja, Lajpat; Trout, Thomas; Nolan, Bernard T.; Malone, Robert W.

    2015-01-01

    Spatial variability in field soil properties is a challenge for system modelers who use single representative values, such as means, for model inputs, rather than their distributions. In this study, the root zone water quality model (RZWQM2) was first calibrated for 4 yr of maize (Zea mays L.) data at six irrigation levels in northern Colorado and then used to study spatial variability of soil field capacity (FC) estimated in 96 plots on maize yield and biomass. The best results were obtained when the crop parameters were fitted along with FCs, with a root mean squared error (RMSE) of 354 kg ha–1 for yield and 1202 kg ha–1 for biomass. When running the model using each of the 96 sets of field-estimated FC values, instead of calibrating FCs, the average simulated yield and biomass from the 96 runs were close to measured values with a RMSE of 376 kg ha–1 for yield and 1504 kg ha–1 for biomass. When an average of the 96 FC values for each soil layer was used, simulated yield and biomass were also acceptable with a RMSE of 438 kg ha–1 for yield and 1627 kg ha–1 for biomass. Therefore, when there are large numbers of FC measurements, an average value might be sufficient for model inputs. However, when the ranges of FC measurements were known for each soil layer, a sampled distribution of FCs using the Latin hypercube sampling (LHS) might be used for model inputs.

  10. Spatial variability of soil magnetic susceptibility in an agricultural field located in Eastern Ukraine

    Science.gov (United States)

    Menshov, Oleksandr; Pereira, Paulo; Kruglov, Oleksandr

    2015-04-01

    Magnetic susceptibility (MS) have been used to characterize soil properties. It gives an indirect information about heavy metals content and degree of human impacts on soil contamination derived from atmospheric pollution (Girault et al., 2011). This method is inexpensive in relation to chemical analysis and very useful to track soil pollution, since several toxic components deposited on soil surface are rich in particulates produced by oxidation processes (Boyko et al., 2004; Morton-Bernea et al., 2009). Thus, identify the spatial distribution of MS is of major importance, since can give an indirect information of high metals content (Dankoub et al., 2012). This allows also to distinguish the pedogenic and technogenic origin magnetic signal. For example Ukraine chernozems contain fine-grained oxidized magnetite and maghemite of pedogenic origin formed by weathering of the parent material (Jeleńska et al., 2004). However, to a correct understanding of variables distribution, the identification of the most accurate interpolation method is fundamental for a better interpretation of map information (Pereira et al., 2013). The objective of this work is to study the spatial variability of soil MS in an agricultural fields located in the Tcherkascy Tishki area (50.11°N, 36.43 °E, 162 m a.s.l), Ukraine. Soil MS was measured in 77 sampling points in a north facing slope. To estimate the best interpolation method, several interpolation methods were tested, as inverse distance to a weight (IDW) with the power of 1,2,3,4 and 5, Local Polynomial (LP) with the power of 1 and 2, Global Polynomial (GP), radial basis functions - spline with tension (SPT), completely regularized spline (CRS), multiquatratic (MTQ), inverse multiquatratic (IMTQ), and thin plate spline (TPS) - and some geostatistical methods as, ordinary kriging (OK), Simple Kriging (SK) and Universal Kriging (UK), used in previous works (Pereira et al., 2014). On average, the soil MS of the studied plot had 686

  11. Geospatial variability of soil CO2-C exchange in the main terrestrial ecosystems of Keller Peninsula, Maritime Antarctica.

    Science.gov (United States)

    Thomazini, A; Francelino, M R; Pereira, A B; Schünemann, A L; Mendonça, E S; Almeida, P H A; Schaefer, C E G R

    2016-08-15

    Soils and vegetation play an important role in the carbon exchange in Maritime Antarctica but little is known on the spatial variability of carbon processes in Antarctic terrestrial environments. The objective of the current study was to investigate (i) the soil development and (ii) spatial variability of ecosystem respiration (ER), net ecosystem CO2 exchange (NEE), gross primary production (GPP), soil temperature (ST) and soil moisture (SM) under four distinct vegetation types and a bare soil in Keller Peninsula, King George Island, Maritime Antarctica, as follows: site 1: moss-turf community; site 2: moss-carpet community; site 3: phanerogamic antarctic community; site 4: moss-carpet community (predominantly colonized by Sanionia uncinata); site 5: bare soil. Soils were sampled at different layers. A regular 40-point (5×8 m) grid, with a minimum separation distance of 1m, was installed at each site to quantify the spatial variability of carbon exchange, soil moisture and temperature. Vegetation characteristics showed closer relation with soil development across the studied sites. ER reached 2.26μmolCO2m(-2)s(-1) in site 3, where ST was higher (7.53°C). A greater sink effect was revealed in site 4 (net uptake of 1.54μmolCO2m(-2)s(-1)) associated with higher SM (0.32m(3)m(-3)). Spherical models were fitted to describe all experimental semivariograms. Results indicate that ST and SM are directly related to the spatial variability of CO2 exchange. Heterogeneous vegetation patches showed smaller range values. Overall, poorly drained terrestrial ecosystems act as CO2 sink. Conversely, where ER is more pronounced, they are associated with intense soil carbon mineralization. The formations of new ice-free areas, depending on the local soil drainage condition, have an important effect on CO2 exchange. With increasing ice/snow melting, and resulting widespread waterlogging, increasing CO2 sink in terrestrial ecosystems is expected for Maritime Antarctica.

  12. The Influence of the Soil Water Balance Within Catchment Hillslopes on Runoff Variability and Fluvial Incision

    Science.gov (United States)

    Rossi, M. W.; Whipple, K. X.; Vivoni, E. R.; DiBiase, R.; Heimsath, A. M.

    2014-12-01

    The variability of daily runoff has direct consequences on water availability, flood hazard, ecosystem function, and erosional processes. One component to predicting runoff variability is solid understanding of soil moisture dynamics and the runoff response to rainfall events. By using a point-scale soil water balance model that accounts for vegetation and soil properties, we test how daily rainfall statistics and vegetation response to water availability affect mean hydrologic partitioning and the runoff response during rare storms. Simulations span a transect in mean annual precipitation (MAP) from 200 to 1200 mm/year and are motivated by analysis of a long-term observational network of rainfall in the contiguous U.S. Whether driven by higher storm depths or increased frequency of storm arrivals, increases in MAP always lead to more fractional runoff generation due to the synchronous increase in mean antecedent soil moisture and probability of large rainfall events. Simulations also show that at any given MAP, there are important tradeoffs between increasing the probability of large rainfall events and associated decreases in the mean soil moisture state. Results from this ecohydrologic analysis are then used to drive 1-D simulations of the longitudinal river profile that account for runoff variability and thresholds to incision. We show that in natural settings where long-term hydrologic observations are available and where millennial-scale erosion rates were measured, much of the observed variation between local relief and long-term erosion rates can be explained by combining these two relatively simple models. However, we also show that large differences in MAP often lead to comparatively small differences in the geomorphically effective climate. This partially explains why prior studies have struggled to isolate a climatic control on long-term erosion rates. Expectations for how vegetation influences landscape evolution are often based on the seminal work by

  13. Significance of Ligand Exchange Relating to Sulfate in Retarding Acidification of Variable Charge Soils Caused by Acid Rain

    Institute of Scientific and Technical Information of China (English)

    WANGJINGHUA; YUTIANREN

    1996-01-01

    For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils,the changes in pH after the addition of different amounts of HNO3 or H2SO4 to representative soils of China were measured .A difference between pH changes caused by the two kinds of acids was observed only for variable charge soils and kaolinite,but not for constant charge soils and bentonite,The larger the proportion of H2SO4 in the HNO3-H2SO4 mixture,the lower the calculated H+ ion activities remained in the suspension.The difference in H+ ion activities between H2SO4 systems and HNO3 systems was larger for soils with a low base-saturation(BS) percentage than those with a high BS percentage.The removal of free iron oxides from the soil led to a decrease in the difference,while the coating of Fe2O3 on a bentonite resulted in a remarkable appearance of the difference.The effect of ligand exchange on the acidity status of the soil varied with the soil type.Surface soils with a high organic matter content showed a less pronounced effect of ligand exchange than subsoils did.It was estimated that when acid rain chiefly containing H2SO4 was deposited on variable charge soils the acidification rate might be slower by 20%-40% than that when the acid rain chiefly contained HNO3 for soils with a high organic matter content,and that the rate might be half of that caused by HNO3 for soils with a low organic matter content,especially for latosols.

  14. Spatial Variability of Soil Saturated Hydraulic Conductivity in a Small Watershed of Loess Hilly Region,China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Saturated hydraulic conductivity (Ks) is an important soil hydraulic parameter for charactering the rate of water flow across the soils and is mainly related to its high spatial variability. In a small watershed with the area of 0.27 km2 in the Loess Plateau, Ks of 197 soil samples under different vegetations and landforms were measured. Ks had a moderate variability for total samples. The forestland had high Ks with low coefficient of variation (CV), but the grassland in the watershed bottom had low Ks wit...

  15. Soil water and transpirable soil water fraction variability within vineyards of the Penedès DO (NE Spain) affected by management practices

    Science.gov (United States)

    Concepción Ramos, Maria

    2015-04-01

    This work investigated the variability in soil water recorded within the vineyard plots related to soil properties and management practices and its influence on the transpirable sol water fraction. The study was carried out in vineyards in the Penedès Designation of Origin, planted with Chardonnay, with different disturbance degree and with compost treated and untreated areas within the plots. The response in years with different rainfall distributions, included years with extreme situations were evaluated. The main soil types are Typic Xerorthent and Calcixerollic Xerorthent and soil is bare most of the time. Soil water content was measured at different depths using TDR probes. The transpirable soil water fraction was estimated as the ratio between available soil water (ASW) at a given date and the total transpirable soil water (TTSW). TTSW was estimated as the soil water reserve held between an upper and lower limit (respectively, the soil water content near field capacity and soil water content at the end of a dry summer) and integrated over the estimated effective rooting depth. Both minimum and maximum soil water values varied within the plot at all depths. On the surface the minimum values ranged between 4.45 to about 10%, while on deeper layers it ranged between 7.8 and 17.8%. Regarding the maximum value varied between 17.45 and 24.8%. The transpirable soil water fraction for a given year varied significantly within the plot, with differences greater than 20% between the treated and untreated areas. The results were more exacerbated in the driest years an in those with more irregular distribution. Water available has a significant effect on yield. The results indicate the need of using different strategies for water management within the plots.

  16. Cu Secondary Adsorption by Some Variable Charge Soils After Adsorbing SO42—

    Institute of Scientific and Technical Information of China (English)

    DONGYUAN-YAN; WANGSHU-YU

    1993-01-01

    Cu secondary adsorption by three variable charge soils collected from hubei Province and Hunan Province was investigated.The amount of Cu secondary adsorption increased with that of SO42- elementary adsorption and conformed with the Langmuir,freundlich and Temkin isotherms.Desorption of secondary-adsorbed Cu indicated that the hysteresis ratio decreased as Cu secondary adsorption increased,which meant that secondry-adsorbed Cu existed not only in the exchangeable form but also in the bridge form and specifically adsorbed form.The amount of Cu secondary adsorption increased with the temperature.

  17. Spatial variability of heavy metals in the coastal soils under long-term reclamation

    Science.gov (United States)

    Wang, Lin; Coles, Neil A.; Wu, Chunfa; Wu, Jiaping

    2014-12-01

    The coastal plain of Cixi City, China, has experienced over 1000 years of reclamation. With the rapid development of agriculture and industry after reclamation, successive inputs into agricultural soils have drastically modified the soil environment. To determine the spatial distribution of heavy metals and to evaluate the influence of anthropogenic activities, a total of 329 top soil samples were taken along a transect on the coastal plain. The samples collected across 11 sea dikes, were selected by a nested sampling methodology. Total Cu, Fe, Mn, Ni, Pb, and Zn concentrations, as well as their diethylenetriamine penta-acetic acid (DTPA) extractable (available) concentrations were determined. Results indicated that except for Zn concentrations, there was neither heavy metals pollution nor mineral deficiency in the soils. Heavy metals exhibited considerable spatial variability, obvious spatial dependence, and close relationships on the reclaimed land. For most metals, the reclamation history was the main influencing factor. Metals concentrations generally showed discontinuities around the position of sea dikes, and the longer reclamation histories tended to have higher metals concentrations than the recently reclaimed sectors. As for Cu and Zn total concentrations, stochastic factors, like industrial waste discharge, fertilization and pesticide application, probably led to the high nugget effect and altered this relationship. The 6th and 10th zones generally had the highest total metals concentrations, due to the concentration of household appliance manufacturers in these reclaimed areas. The first two zones were characterized by high available metals concentrations, probably due to the alternant flooding and emergence, low pH values and high organic matter contents in these paddy field soils. From the 3rd to 7th zones with the same land use history and soil type, metals concentrations, especially available concentrations, showed homogeneity. The nested sampling

  18. Adsorption edge study about cadmium, copper, nickel and zinc adsorption by variable charge soils

    Science.gov (United States)

    Casagrande, J. C.; Mouta, E. R.; Soares, M. R.

    2009-04-01

    The improper discharge of industrial and urban residues and the inadvertent use of fertilizers and pesticides can result in soil and water pollution and improve the potential of trace metals to enter in the human food chain. Adsorption reactions occur at the solid/liquid interface and are the most important mechanisms for controlling the activity of metal ions in soil solution. In a complex system with amphoteric behavior, the comprehension of the mobility, availability and fate of pollutants in the soil system is crucial for the prediction of the environmental consequences and for development of prevention/remediation strategies. A comparative study of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) adsorption by highly weathered soils was carried out. Surface (0-0.2m) and subsoil (B horizon) samples were taken from a Rhodic Kandiudalf (RH), an Anionic "Xanthic" Acrudox (XA) and an Anionic "Rhodic" Acrudox (RA), located in brazilian humid tropical area. As the pH and the ionic strength are important environmental factors influencing the solution chemistry of heavy metals in variable charge systems, adsorption envelopes, in a batch adsorption experiment, were elaborated by reacting, for 24 h, soil samples with individual 0.01, 0.1 and 1.0 mol L-1 Ca(NO3)2 aqueous solutions containing nitrate salts of the adsorptive heavy metal (Cd, Cu, Ni and Zn) at the initial concentration of 5 mg L-1, with an increasing pH value from 3.0 to 8.0. pH50-100%, the difference between the pH of 100 and 50 percent metal adsorption was determined. A sharp increase of adsorption density (adsorption edge) was observed within a very narrow pH range, usually less than two pH units. Commonly, the relative affinity of a soil for a metal cation increases with the tendency of the cation to form inner-sphere surface complexes. This may be caused by differences in extent of hydrolysis of Cu ions and in affinity of adsorption sites for Cu. In general, subsurface samples showed low pH50

  19. Spatial variability of isoproturon mineralizing activity within an agricultural field: geostatistical analysis of simple physicochemical and microbiological soil parameters.

    Science.gov (United States)

    El Sebai, T; Lagacherie, B; Soulas, G; Martin-Laurent, F

    2007-02-01

    We assessed the spatial variability of isoproturon mineralization in relation to that of physicochemical and biological parameters in fifty soil samples regularly collected along a sampling grid delimited across a 0.36 ha field plot (40 x 90 m). Only faint relationships were observed between isoproturon mineralization and the soil pH, microbial C biomass, and organic nitrogen. Considerable spatial variability was observed for six of the nine parameters tested (isoproturon mineralization rates, organic nitrogen, genetic structure of the microbial communities, soil pH, microbial biomass and equivalent humidity). The map of isoproturon mineralization rates distribution was similar to that of soil pH, microbial biomass, and organic nitrogen but different from those of structure of the microbial communities and equivalent humidity. Geostatistics revealed that the spatial heterogeneity in the rate of degradation of isoproturon corresponded to that of soil pH and microbial biomass.

  20. TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive geochemical Transport in Variable Saturated Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

    2004-05-24

    Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of mineral alteration in hydrothermal systems, waste disposal sites, acid mine drainage remediation, contaminant transport, and groundwater quality. A comprehensive non-isothermal multi-component reactive fluid flow and geochemical transport simulator, TOUGHREACT, has been developed. A wide range of subsurface thermo-physical-chemical processes is considered under various thermohydrological and geochemical conditions of pressure, temperature, water saturation, and ionic strength. The program can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions are considered, such as aqueous complexation, gas dissolution/exsolution, and cation exchange. Mineral dissolution/precipitation can proceed either subject to local equilibrium or kinetic conditions. Changes in por