A national-scale geochemical and mineralogical survey of soils of the conterminous United States

International Nuclear Information System (INIS)

Smith, David B.; Cannon, William F.; Woodruff, Laurel G.

2011-01-01

Highlights: → Sampling for national-scale soil geochemical and mineralogical survey completed for conterminous USA. → Natural variation for most elements is approximately three orders of magnitude. → Composition of soil parent material is the major controlling factor. → Climate (average annual precipitation) is also an important controlling factor for some elements. → Sample archive (4800 sites) available for future investigations. - Abstract: In 2007, the US Geological Survey initiated a low-density (1 site per 1600 km 2 , c. 4800 sites) geochemical and mineralogical survey of soils of the conterminous USA. 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 3 , HClO 4 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 was completed in 2010 with chemical and mineralogical analysis currently underway. Preliminary results for a swath from the central USA 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.

Seasonal variability of microbial biomass phosphorus in urban soils.

Science.gov (United States)

Halecki, W; Gąsiorek, M

2015-01-01

Urban soils have been formed through human activities. Seasonal evaluation with time-control procedure are essential for plant, and activity of microorganisms. Therefore, these processes are crucial in the urban area due to geochemical changes in the past years. The purpose of this study was to investigate the changes of content of microbial biomass phosphorus (P) in the top layer of soils throughout the season. In this research, the concentration of microbial biomass P ranged from 0.01 to 6.29 mg·kg(-1). We used single-factor repeated-measure analysis of variance to test the effect of season on microbial biomass P content of selected urban soils. We found no statistically significant differences between the concentration of microbial biomass P in the investigated urban and sub-urban soils during the growing season. This analysis explicitly recognised that environmental urban conditions are steady. Specifically, we have studied how vegetation seasonality and ability of microbial biomass P are useful for detecting quality deviations, which affect the equilibrium of urban soil. In conclusion, seasonal variability of the stringency of assurance across the different compounds of soil reveals, as expected, the stable condition of the urban soils. Seasonal responses in microbial biomass P under urban soil use should establish a framework as a reference to the activity of the microorganisms. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of soil geochemical and microbiological components on selenium behaviour in oxic and anoxic conditions

International Nuclear Information System (INIS)

Darcheville, O.

2008-09-01

Selenium (Se) is naturally present in the environment. Se is essential for living organisms at trace concentrations, but it becomes rapidly toxic with their increases. The 79 Se radioactive isotopes of Se, is found in nuclear wastes that may be buried in deep geological formations. In soil, Se exists in many forms and its mobility is affected by the redox potential and microbial activity. Very few studies have focused on Se behaviour at trace concentration. We have tried to distinguish the major abiotic geochemical and microbiological processes involved in the fate of trace selenite (Se(IV)) in a soil. The study was based on batch incubation in oxic or anoxic conditions of slurry suspension artificially contaminated with Se (IV) to 0.4 mg Se.kg -1 dry soil. The incubation involved sterilized and non-sterile soil samples with or without organic amendment to stimulate microbial activities. For each incubation, we followed the distribution of Se between solid, liquid and gaseous phases as well as the geochemical evolution of the solution, the composition of the atmosphere gas bottles and the soil microflora. The results showed that Se was relatively few mobile in the soil studied. Geochemical processes played a major role in controlling the Se mobility. Over time, some abiotic transformations in the solid phase contributed to increase the Se immobilisation. The microbiological processes contributed to this increase in the solid phase. Moreover, in oxic as in anoxic conditions, some microbial processes were responsible, to a lesser extent, for a dispersion of Se in the atmosphere by the production of volatile compounds. (author)

[Geochemical characteristics of radon and mercury in soil gas in Lhasa, Tibet, China].

Science.gov (United States)

Zhou, Xiao-Cheng; Du, Jian-Guo; Wang, Chuan-Yuan; Cao, Zhong-Quan; Yi, Li; Liu, Lei

2007-03-01

The geochemical characteristics of radon and mercury in soil gas in Lhasa and vicinity are investigated based on the measurements of Rn and Hg concentrations, and environmental quality for Rn and Hg in soil gas was evaluated by means of the index of geoaccumulation. The data of Rn and Hg of 1 579 sampling site indicate that the values of environmental-geochemical background of Rn and Hg are 7 634.9 Bq/m3, 41.5 ng/m3 with standard deviations of 2.7 Bq/m3, 2.2 ng/m3, respectively. The environmental quality for Rn in soil gas is better in the west and east parts of studied area, but becomes moderate pollution (level III) in the north part of the central area. Rn is derived from radioactive elements in granitic sediments in the intermountain basin and granite base, which are the major sources of pollution. The environmental quality for Hg in soil gas becomes gradually polluted from the suburban to the center of urban, and the highest pollution reaches level IV. The background of Hg in soil gas is mainly controlled by compositions of sediments, but the Hg pollution caused by human waste and religionary use of mercury.

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.

Distribution of cadmium among geochemical fractions in floodplain soils of progressing development

International Nuclear Information System (INIS)

Lair, G.J.; Graf, M.; Zehetner, F.; Gerzabek, M.H.

2008-01-01

Initial soil development in river floodplains influences soil properties and processes. In this study, suites of young floodplain soils sampled at three European rivers (Danube/Austria, Ebro/Spain and Elbe/Germany) were used to link soil development to the soils' retention capacity for cadmium. Geochemichal fractionation of original and metal-spiked soils was conducted. Cadmium remained in weakly bound fractions in both original and spiked soils, representing an entirely different behaviour than observed for copper in an earlier study. The tendency of incorporation into more stable forms over time was only slightly expressed. Correlation analysis revealed the involvement of different sorption surfaces in soil, with no single soil constituent determining cadmium retention behaviour. Nevertheless, in the calcareous soils of the Danube floodplain, we found increased cadmium retention and decreased portions of desorbable cadmium with progressing soil development. - Distribution of cadmium among geochemical fractions in floodplain soils reveals high mobility but increased retention capacity with increasing soil age and development

The geochemical atlas of Alaska, 2016

Science.gov (United States)

Lee, Gregory K.; Yager, Douglas B.; Mauk, Jeffrey L.; Granitto, Matthew; Denning, Paul; 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.

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

History and progress of the North American Soil Geochemical Landscapes Project, 2001-2010

Science.gov (United States)

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

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 20032004 and pilot studies were conducted from 20042007. The ideal sampling protocol at each site includes a sample from 05 cm depth, a composite of the soil A horizon, and a sample from the soil C horizon. The 3, 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.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Top Soils Geochemical and Radioactivity Survey of Naples (Italy) Metropolitan.

Science.gov (United States)

Somma, R.; De Vivo, B.; Cicchella, D.

2001-05-01

The metropolitan area of Naples due to intense human activities is an emblematic area affected by various environmental pollution of soils and waters in addition to hydrogeological volcanic, seismic and bradyseismic hazards. The geology of the area is prevailing represented by volcanics erupted, from the Upper Pleistocene to Recent by Mt. Somma-Vesuvius on the east and the Campi Flegrei fields on the west. The morphology of the metropolitan area of Naples city can be subdivided in flat areas, constituted by reworked pyroclastic terrains, and by hills originated by the overlapping of different welded pyroclastic flows (i.e.: Campanian Ignimbrite and Neapoletan Yellow Tuff) intercalated with pyroclastic deposits of different origins (i.e.: Campi Flegrei, Mt. Somma-Vesuvius, Ischia) and ages. In order to compile a multi-element baseline geochemical and radioactivity mapping of the metropolitan area of the Napoli we have sampled for this study, in situ top soil and imported filling material (mainly soil, volcanic ash, pumice and scoriae). The sampling and radioactivity survey has been carried out on about 200 sampling sites covering an area of about 150 Km2, with a grid of 0.5 x 0.5 km in the urbanised downtown and 1 km x 1 km in the sub urban areas. In each site has been determined a radioactivity by a Scintrex GRS-500 at different emission spectra as total radioactivity (> 0.08 MeV and > 0.40 MeV), 238U (at 1.76 MeV mostly from 214Bi), 232Th (at 2.6 MeV mostly from 208Tl) and 40K (at 1.46 MeV mostly for 40K). The range of values of in situ soils are as follow for the in situ soils (Total radioactivity: 1327- 360 and 114- 47; 238U: 2.6- 1.3; 40K: 8.1- 3.1; 232U: 0.5- 0.1). Analyses of major, metallic elements and pH of each soil sample are in progress, while Pb isotopes compositions, for a selected number of samples, will be determined to discriminate the natural (geogenic) from the anthropogenic components in the soils by versus the anthropogenetic origin. The data

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.

Computer analysis to the geochemical interpretation of soil and stream sediment data in an area of Southern Uruguay

International Nuclear Information System (INIS)

Spangenberg, J.

2010-01-01

In southern Uruguay there are several known occurrences of base metal sulphide mineralization within an area of Precambrian volcanic sedimentary rocks. Regional geochemical stream sediment reconnaissance surveys revealed new polymetallic anomalies in the same stratigraphic zone. Geochemical interpretation of multi-element data from a soil and stream sediment survey carried out in one of these anomalous areas is presented.

Determination of geochemical and anthropogenic uranium sources in soil and tailing

International Nuclear Information System (INIS)

Stojanovic, M.; Potpara, D.; Tesmanovic, L.

2002-01-01

The origin of uranium in soil (geochemical or anthropogenic) influences the degree of its accessibility to plants. Uranium originating from the geochemical sources is much less, if not quite inaccessible to plants. On the other hand uranium accumulated in soil as a result of anthropogenic activity (use of phosphate fertilisers, dissemination of flying ash from the thermal power plants, dissemination of mining wastes, disposal of nuclear waste and use of ammunition produced from depleted uranium) is most often present in forms much more accessible to plants. The aim of this work was to determine the efficiency of different methods of uranium extraction from soil (used to determine the 'mobile' and accessible contents) which could give the answer on the level of its accessibility to plants, and to determine uranium distribution in various chemical fractions by the method of fractional extraction.The applied method of fractional extraction is based on the idea that all metals form bonds of different strength with the solid phase of soil and such bonds can be completely broken under the effect of reagents such as: 0.1M CaCl 2 (pH - 7.0) for extraction of water-soluble and alternately adsorbed forms of metals; 1M CH 3 COONa (pH - 5.0) for the extraction of specifically adsorbed forms of metals bonded to carbonates; 0.04M hydroxylamine hydrochloride in 25% CH 3 COOH (pH - 3.0) for extraction of metals bonded to Fe and Mn oxide; 0.02M HNO 3 in 30% H 2 O 2 for metals bonded to organic matter. Structurally bonded forms of metals in silicates are determined from the difference of the total uranium content and sum of the metal quantity from the first four fractions. Determination of uranium content in samples was performed by the fluorimetric method. (author)

Evolution of hillslope soils: The geomorphic theater and the geochemical play

International Nuclear Information System (INIS)

Yoo, Kyungsoo; Weinman, Beth; Mudd, Simon Marius; Hurst, Martin; Attal, Mikael; Maher, Kate

2011-01-01

Highlights: → We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. → Over wide range of denudation rates, soil thicknesses do not vary significantly. → Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. → In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. → Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of ∼700 m to the plateau at an elevation of ∼1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil erosion rates. From

Evolution of hillslope soils: The geomorphic theater and the geochemical play

Energy Technology Data Exchange (ETDEWEB)

Yoo, Kyungsoo, E-mail: kyoo@umn.edu [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Weinman, Beth [Dept. of Soil, Water, and Climate, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108-6028 (United States); Mudd, Simon Marius; Hurst, Martin; Attal, Mikael [School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, Scotland (United Kingdom); Maher, Kate [Dept. of Geological and Environmental Sciences, Braun Hall 118, 450 Serra Mall, Bldg. 320, Stanford, CA 94305-2115 (United States)

2011-06-15

Highlights: > We ask 'how and how fast do hillslope soils form as the landscape's morphology changes over time?'. > Over wide range of denudation rates, soil thicknesses do not vary significantly. > Colluvial soils with lower denudation rates (above the knick point) are enriched in fine size fractions, Zr, and pedogenic crystalline Fe oxides. > In the two steep hillslopes below the knickpoint, no systematic topgraphic trends were found for soil geochemistry. > Soils show increasing Zr enrichment in the downslope direction only in the hillslope above the knickpoint. - Abstract: How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evolution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the authors are investigating a tributary basin to the Middle Fork Feather River. A major incision signal from the river is well marked in a knickpoint within the tributary basin which stretches from its mouth to the Feather River at an elevation of {approx}700 m to the plateau at an elevation of {approx}1500 m. Hillslopes are significantly steeper below the knickpoint. The area's total denudation rates are currently being constrained using cosmogenic radio nuclides, but a previous study suggested an order of magnitude difference in total denudation rates below and above the knickpoint. When compared with topographic attributes calculated from LIDAR data, physical erosion rates can be modeled as a linear function of ridge top curvature. Surprisingly, over the wide range of total denudation rates, soil thicknesses do not vary significantly until a threshold point where soil mantled landscapes abruptly shift to bedrock dominated landscapes. Bioturbation by tree falls appear to buffer soil thickness over the wide range of physical soil

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

Soil variability in mountain areas

OpenAIRE

Zanini, E.; Freppaz, M.; Stanchi, S.; Bonifacio, E.; Egli, M.

2015-01-01

The high spatial variability of soils is a relevant issue at local and global scales, and determines the complexity of soil ecosystem functions and services. This variability derives from strong dependencies of soil ecosystems on parent materials, climate, relief and biosphere, including human impact. Although present in all environments, the interactions of soils with these forming factors are particularly striking in mountain areas.

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.

[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.

Computer analysis to the geochemical of soil and stream sediments data in an area of Southern Uruguay

International Nuclear Information System (INIS)

Spangenberg, J.

2012-01-01

This work is about geochemical interpretation of multi-element data from a soil and stream sediment survey carried out in Southern of Uruguay .This zone has several occurrences of metal sulphide mineralization

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

Energy Technology Data Exchange (ETDEWEB)

Appleton, J.D. [British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG (United Kingdom)], E-mail: jda@bgs.ac.uk; Miles, J.C.H.; Green, B.M.R. [Health Protection Agency (HPA) - Radiation Protection Division, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom); Larmour, R. [Environment and Heritage Service, Department of the Environment, Belfast BT7 2JA (United Kingdom)

2008-10-15

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.

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

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.

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

International Nuclear Information System (INIS)

Zhou Xu; Xia Beicheng

2010-01-01

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 -100mT /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 200 mg/kg; zinc 230 mg/kg; lead 190 mg/kg and cadmium 1.85 mg/kg) Cu, Zn and Cd exceeded the soil Grade II limits (for pH < 6.5) from the Chinese Environmental Quality Standard for Soils (GB 15618-1995) (EQSS) which are 100, 200, 250 and 0.3 mg/kg for Cu, Zn, Pb and Cd, respectively. In particular, the geochemical 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.

Geochemical dispersion of Si, Al, Fe, Mn, Na, K, Cu and Zn elements in soils and their use for characterization areas geochemically homogeneous

International Nuclear Information System (INIS)

Silva, W.R.L. da.

1982-01-01

Variations in the chemical composition of soils are used to characterize sub-areas geochemically - homogenous. The application of this methodology in a tropical humid region of accentuated topography constitute the principal objective of the present research. Samples of red latosols (Horizon B) developed over granite, sandstone and basalt occurring in the Central Granite Region of the Serra dos Carajas, Para State, Brazil were analized for the elements Si, Al, Fe, Mn, Na, K, Cu e Zn, by atomic absorption spectrophotometry. Based on the criterion of similarity in the chemical composition (Cluster Analysis, Factor Analysis) the soils were separeted in to different groups. The geographical distribution of the different groups permit the establishment of a close relationship between the different parent lithologies and their corresponding soils. (author)

The water-soluble fraction of potentially toxic elements in contaminated soils: relationships between ecotoxicity, solubility and geochemical reactivity.

Science.gov (United States)

Rocha, L; Rodrigues, S M; Lopes, I; Soares, A M V M; Duarte, A C; Pereira, E

2011-09-01

To better understand the impacts posed by soil contamination to aquatic ecosystems it is crucial to characterise the links between ecotoxicity, chemical availability and geochemical reactivity of potentially toxic elements (PTE's) in soils. We evaluated the adverse effects of water extracts obtained from soils contaminated by chemical industry and mining, using a test battery including organisms from different trophic levels (bacteria, algae and daphnids). These tests provided a quick assessment of the ecotoxicity of soils with respect to possible adverse effects on aquatic organisms although the ecotoxicological responses could be related to the solubility of PTE's only to a limited extent. The analysis of results of bioassays together with the chemical characterisation of water extracts provided additional relevant insight into the role of conductivity, pH, Al, Fe, and Mn of soil extracts on toxicity to organisms. Furthermore, an important conclusion of this study was that the toxicity of extracts to the aquatic organisms could also be related to the soil properties (pH, Org C and Fe(ox)) and to the reactivity of PTE's in soils which in fact control the soluble fraction of the contaminants. The combined assessment of ecotoxicity in water fractions, solubility and geochemical reactivity of PTE's in soils provided a more comprehensive understanding of the bioavailability of inorganic contaminants than ecotoxicological or chemical studies alone and can therefore be most useful for environmental risks assessment of contaminated soils. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

2014-01-01

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. - 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

Determining baselines and variability of elements in plants and soils near the Kenai National Wildlife Refuge, Alaska

Science.gov (United States)

Crock, J.G.; Severson, R.C.; Gough, L.P.

1992-01-01

Recent investigations on the Kenai Peninsula had two major objectives: (1) to establish elemental baseline concentrations ranges for native vegetation and soils; and, (2) to determine the sampling density required for preparing stable regional geochemical maps for various elements in native plants and soils. These objectives were accomplished using an unbalanced, nested analysis-of-variance (ANOVA) barbell sampling design. Hylocomium splendens (Hedw.) BSG (feather moss, whole plant), Picea glauca (Moench) Voss (white spruce, twigs and needles), and soil horizons (02 and C) were collected and analyzed for major and trace total element concentrations. Using geometric means and geometric deviations, expected baseline ranges for elements were calculated. Results of the ANOVA show that intensive soil or plant sampling is needed to reliably map the geochemistry of the area, due to large local variability. For example, producing reliable element maps of feather moss using a 50 km cell (at 95% probability) would require sampling densities of from 4 samples per cell for Al, Co, Fe, La, Li, and V, to more than 15 samples per cell for Cu, Pb, Se, and Zn.Recent investigations on the Kenai Peninsula had two major objectives: (1) to establish elemental baseline concentrations ranges for native vegetation and soils; and, (2) to determine the sampling density required for preparing stable regional geochemical maps for various elements in native plants and soils. These objectives were accomplished using an unbalanced, nested analysis-of-variance (ANOVA) barbell sampling design. Hylocomium splendens (Hedw.) BSG (feather moss, whole plant), Picea glauca (Moench) Voss (white spruce, twigs and needles), and soil horizons (02 and C) were collected and analyzed for major and trace total element concentrations. Using geometric means and geometric deviations, expected baseline ranges for elements were calculated. Results of the ANOVA show that intensive soil or plant sampling is needed to

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

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.

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

2017-08-01

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.

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

Process recognition in multi-element soil and stream-sediment geochemical data

Science.gov (United States)

Grunsky, E.C.; Drew, L.J.; Sutphin, D.M.

2009-01-01

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on

Bio-geochemical behavior of 90Sr, 137Cs and 60Co in tropical soil

International Nuclear Information System (INIS)

Wasserman, M.A.; Gonzales Viana, A.; Bartoly, F.; Carvalho Conti, C. de; Janvrot Vivone, R.; Perez, V.; Wasserman, J.C.

2004-01-01

One manner to assess the bio-geochemical behavior of radionuclides in soils is the integration of experimental methods results obtained in the laboratory with results obtained in field experiments. In this work was used an alternative sequential chemical extraction protocol to evaluate mobility of radionuclides as a function of some physico-chemical conditions operationally defined: Slightly acidic phase: CH 3 COOH + CH 3 COONa 1:1, pH 4.7, shacked at room temperature; Easily reducible phase: NH 2 OH.HCl (0.1 M), pH 2, shacked at room temperature;Oxidizable phase: H 2 O 2 (30%) + HNO 3 , pH 2, CH 3 COONH 4 (1 M);shacked at room temperature; Alkaline phase: NaOH (0.1 M), pH 12, shacked at room temperature; Resistant phase: Aqua regia heated to 50 deg C / 30 min. The results obtained experimentally indicate the vulnerability of some Brazilian soils due to the higher radionuclide transfer to plant. Although it seems clear that it is difficult to identify which soil property will determine a given TF, the results of geochemical partition for 137 Cs, 90 Sr and 60 Co obtained in slightly acidic phase were very consistent with the TF data for reference plants or with some of the soil properties recognized in the specialized literature as related with mechanisms of sorption of Cs (e.g. exchangeable K, organic matter and iron oxides content), Co (e.g. manganese oxide) and Sr (pH and exchangeable Ca). The 137 Cs distribution in soil showed that Fe oxides are the main sink for this element in all type of soil and 16 years after contamination the 137 Cs the TF remains almost the same in Goiania soil. The 60 Co distribution in soil showed that Mn oxides are the main sink for this element in all type of soils and in the Nitisol, 5 years after contamination, the 60 Co was not detected as bioavailable (in the slightly acidic phase) neither detected in plant or were detectable with values very close to the detection limit. In the Nitisol, it is possible that reduction in 137 Cs

A regional soil and sediment geochemical study in northern California

International Nuclear Information System (INIS)

Goldhaber, Martin B.; Morrison, Jean M.; Holloway, JoAnn M.; Wanty, Richard B.; Helsel, Dennis R.; Smith, David B.

2009-01-01

Regional-scale variations in soil geochemistry were investigated in a 20,000-km 2 study area in northern California that includes the western slope of the Sierra Nevada, the southern Sacramento Valley and the northern Coast Ranges. Over 1300 archival soil samples collected from the late 1970s to 1980 in El Dorado, Placer, Sutter, Sacramento, Yolo and Solano counties were analyzed for 42 elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry following a near-total dissolution. These data were supplemented by analysis of more than 500 stream-sediment samples from higher elevations in the Sierra Nevada from the same study site. The relatively high-density data (1 sample per 15 km 2 for much of the study area) allows the delineation of regional geochemical patterns and the identification of processes that produced these patterns. The geochemical results segregate broadly into distinct element groupings whose distribution reflects the interplay of geologic, hydrologic, geomorphic and anthropogenic factors. One such group includes elements associated with mafic and ultramafic rocks including Cr, Ni, V, Co, Cu and Mg. Using Cr as an example, elevated concentrations occur in soils overlying ultramafic rocks in the foothills of the Sierra Nevada (median Cr = 160 mg/kg) as well as in the northern Coast Ranges. Low concentrations of these elements occur in soils located further upslope in the Sierra Nevada overlying Tertiary volcanic, metasedimentary and plutonic rocks (granodiorite and diorite). Eastern Sacramento Valley soil samples, defined as those located east of the Sacramento River, are lower in Cr (median Cr = 84 mg/kg), and are systematically lower in this suite compared to soils from the west side of the Sacramento Valley (median Cr = 130 mg/kg). A second group of elements showing a coherent pattern, including Ca, K, Sr and REE, is derived from relatively silicic rocks types. This group occurs at elevated

A regional soil and sediment geochemical study in northern California

Science.gov (United States)

Goldhaber, M.B.; Morrison, J.M.; Holloway, J.M.; Wanty, R.B.; Helsel, D.R.; Smith, D.B.

2009-01-01

Regional-scale variations in soil geochemistry were investigated in a 20,000-km2 study area in northern California that includes the western slope of the Sierra Nevada, the southern Sacramento Valley and the northern Coast Ranges. Over 1300 archival soil samples collected from the late 1970s to 1980 in El Dorado, Placer, Sutter, Sacramento, Yolo and Solano counties were analyzed for 42 elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry following a near-total dissolution. These data were supplemented by analysis of more than 500 stream-sediment samples from higher elevations in the Sierra Nevada from the same study site. The relatively high-density data (1 sample per 15 km2 for much of the study area) allows the delineation of regional geochemical patterns and the identification of processes that produced these patterns. The geochemical results segregate broadly into distinct element groupings whose distribution reflects the interplay of geologic, hydrologic, geomorphic and anthropogenic factors. One such group includes elements associated with mafic and ultramafic rocks including Cr, Ni, V, Co, Cu and Mg. Using Cr as an example, elevated concentrations occur in soils overlying ultramafic rocks in the foothills of the Sierra Nevada (median Cr = 160 mg/kg) as well as in the northern Coast Ranges. Low concentrations of these elements occur in soils located further upslope in the Sierra Nevada overlying Tertiary volcanic, metasedimentary and plutonic rocks (granodiorite and diorite). Eastern Sacramento Valley soil samples, defined as those located east of the Sacramento River, are lower in Cr (median Cr = 84 mg/kg), and are systematically lower in this suite compared to soils from the west side of the Sacramento Valley (median Cr = 130 mg/kg). A second group of elements showing a coherent pattern, including Ca, K, Sr and REE, is derived from relatively silicic rocks types. This group occurs at elevated

Geochemical analysis of leachates from cement/low-level radioactive waste/soil systems

International Nuclear Information System (INIS)

Criscenti, L.J.; Serne, R.J.

1988-09-01

Laboratory experiments were conducted as part of the Special Waste Form Lysimeters/endash/Arid Program. These experiments were conducted to investigate the performance of solidified low-level nuclear waste in a typical arid, near-surface disposal site, and to evaluate the ability of laboratory tests to predict leaching in actual field conditions. Batch leaching, soil adsorption column, and soil/waste form column experiments were conducted using Portland III cement waste forms containing boiling-water reactor evaporator concentrate and ion-exchange resin waste. In order to understand the reaction chemistry of the cement waste form/soil/ground-water system, the compositions of the leachates from the laboratory experiments were studied with the aid of the MINTEQ ion speciation/solubility and mass transfer computer code. The purpose of this report is to describe the changes in leachate composition that occur during the course of the experiments, to discuss the geochemical modeling results, and to explore the factors controlling the major element chemistry of these leachates. 18 refs., 84 figs., 14 tabs

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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Mineralogical and geochemical patterns of urban surface soils, the example of Pforzheim, Germany

International Nuclear Information System (INIS)

Norra, Stefan; Lanka-Panditha, Mahesh; Kramar, Utz; Stueben, Doris

2006-01-01

This study presents a combined geochemical and mineralogical survey of urban surface soils. Many studies on urban soils are restricted to purely chemical surveys in order to investigate soil pollution caused by anthropogenic activities such as traffic, heating, industrial processing, waste disposal and many more. In environmental studies, chemical elements are often distinguished as lithogenic and anthropogenic elements. As a novel contribution to those studies, the authors combined the analysis of a broad set of chemical elements with the analysis of the main mineralogical phases. The semi-quantification of mineralogical phases supported the assignment of groups of chemical elements to lithogenic or anthropogenic origin. Minerals are important sinks for toxic elements. Thus, knowledge about their distribution in soils is crucial for the assessment of the environmental hazards due to pollution of urban soils. In Pforzheim, surface soils (0-5 cm depth) from various land use types (forest, agriculture, urban green space, settlement areas of various site densities) overlying different geological units (clastic and chemical sediments) were investigated. Urban surface soils of Pforzheim reflect to a considerable degree the mineral and chemical composition of parent rocks. Irrespective of the parent rocks, elevated concentrations of heavy metals (Zn, Cu, Pb, Sn, Ag) were found in soils throughout the whole inner urban settlement area of Pforzheim indicating pollution. These pollutants will tend to accumulate in inner urban surface soils according to the available adsorption capacity, which is normally higher in soils overlying limestone than in soils overlying sandstone. However, inner urban surface soils overlying sandstone show elevated concentrations of carbonates, phyllo-silicates and Fe and elevated pH values compared with forest soils overlying sandstone. Thus, in comparison to forest soils overlying sandstones, inner urban soils overlying sandstone affected by

Effect of mineralogical, geochemical and biological properties on soils reflectance to assess temporal and spatial dynamics of BSCs in Sahelian ecosystems

Science.gov (United States)

Bourguignon, A.; Cerdan, O.; Desprats, J. F.; Marin, B.; Malam Issa, O.; Valentin, C.; Rajot, J. L.

2012-04-01

pressure on land use Soil surface disturbances due to the intensification of human activities. Spectral field and laboratory data were acquired in 2009, 2010 and 2011 with the FieldSpec Pro®. The spectra of soils with respect to different parameters are studied in details and their separability from BSCs, vegetation and vegetation residue as well are be analysed. First, the effect of the mineralogy and the geochemical variables on the soil reflectance properties is studied and then the feasibility to resolve some of these effects with satellite imagery (e. g., ASTER) will be tested in order to define the potential capability for identifying the locations of sensitive areas affected by soil degradation and appearance of BSCs.

Variability of atmospheric depositions of artificial radioelements and their transfer into soils

International Nuclear Information System (INIS)

Pourcelot, Laurent

2008-01-01

In this Habilitation thesis, I present the results and prospects of the main research topics that contribute to bettering our knowledge of the behaviour of artificial radioelements in the geosphere and biosphere. In the first chapter I present a summary of the research carried out for my thesis on the Oklo reactors. In the subsequent chapters I present my research work at the IRSN. The second chapter concerns the atmospheric depositions of radioactive contaminants. I have studied the principal environmental parameters involved in the empirical modelling of the transfer of artificial radioelements from the atmosphere to the soil. Here I essentially use measurements of artificial radioelements ( 137 Cs, plutonium, americium) in soils that reveal the variability of accidental depositions further to the Chernobyl disaster (paragraph 2.1) and chronic radioactive depositions coming from the atmospheric testing of nuclear weapons (paragraph 2.2). In the third chapter I address the problem of transfers of artificial radioelements into the soil. The interest of this lies in the fact that these transfers represent serious risks for man. Taken over the long term (in the months and years that follow the depositing of radioactive elements on the ground and plants), the transfers of radioactive pollutants into the soil are responsible for the contamination of both plants (transfer via the roots) and underground water and surface water (transfer after vertical migration). My research work into the transfers of radioactive pollutants in soils is centred on vertical migrations and root transfers, as both these processes can be studied through environmental samplings and measurements. More precisely, I have studied the migrations of radioactive pollutants and their geochemical analogues in different types of soils (paragraph 3.1) and the variability of the activities of radiostrontium and radiocesium in the compartments of permanent grassland zones (soil, grass, milk and cheese

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.

Geochemical Exploration Techniques Applicable in the Search for Copper Deposits

Science.gov (United States)

Chaffee, Maurice A.

1975-01-01

Geochemical exploration is an important part of copper-resource evaluation. A large number of geochemical exploration techniques, both proved and untried, are available to the geochemist to use in the search for new copper deposits. Analyses of whole-rock samples have been used in both regional and local geochemical exploration surveys in the search for copper. Analyses of mineral separates, such as biotite, magnetite, and sulfides, have also been used. Analyses of soil samples are widely used in geochemical exploration, especially for localized surveys. It is important to distinguish between residual and transported soil types. Orientation studies should always be conducted prior to a geochemical investigation in a given area in order to determine the best soil horizon and the best size of soil material for sampling in that area. Silty frost boils, caliche, and desert varnish are specialized types of soil samples that might be useful sampling media. Soil gas is a new and potentially valuable geochemical sampling medium, especially in exploring for buried mineral deposits in arid regions. Gaseous products in samples of soil may be related to base-metal deposits and include mercury vapor, sulfur dioxide, hydrogen sulfide, carbon oxysulfide, carbon dioxide, hydrogen, oxygen, nitrogen, the noble gases, the halogens, and many hydrocarbon compounds. Transported materials that have been used in geochemical sampling programs include glacial float boulders, glacial till, esker gravels, stream sediments, stream-sediment concentrates, and lake sediments. Stream-sediment sampling is probably the most widely used and most successful geochemical exploration technique. Hydrogeochemical exploration programs have utilized hot- and cold-spring waters and their precipitates as well as waters from lakes, streams, and wells. Organic gel found in lakes and at stream mouths is an unproved sampling medium. Suspended material and dissolved gases in any type of water may also be useful

Geochemical processes during managed aquifer recharge with desalinated seawater

Science.gov (United States)

Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

2017-12-01

In this work we study the geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW) to an infiltration pond at the Menashe site, located above the Israeli coastal aquifer. The DSW is post-treated by calcite dissolution (remineralization) in order to meet the Israeli desalinated water quality criteria. Suction cups and monitoring wells inside the pond were used to monitor water quality during two MAR events on 2015 and 2016. Results show that cation exchange is dominant, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the composition of the shallow groundwater is similar to the recharged DSW, but with enrichment of Mg2+, Na+, Ca2+ and HCO3-. A calibrated variably-saturated reactive transport model was used to predict the geochemical evolution during 50 years of MAR with two water quality scenarios: post-treated DSW and soft DSW (without post-treatment). The latter scenario was aimed to test soil-aquifer-treatment as an alternative post-treatment technique. In terms of water quality, the results of the two scenarios were found within the range of the desalinated water criteria. Mg2+ enrichment was stable ( 2.5 mg L-1), higher than the zero concentration found in the Israeli DSW. Calcite content reduction was low (<1%) along the variably-saturated profile, after 50 years of MAR. This suggests that using soil-aquifer-treatment as a remineralization technique for DSW is potentially a sustainable practice, which is limited only by the current hydraulic capacity of the Menashe MAR site.

Soil physics and the water management of spatially variable soils

International Nuclear Information System (INIS)

Youngs, E.G.

1983-01-01

The physics of macroscopic soil-water behaviour in inert porous materials has been developed by considering water flow to take place in a continuum. This requires the flow region to consist of an assembly of representative elementary volumes, repeated throughout space and small compared with the scale of observations. Soil-water behaviour in swelling soils may also be considered as a continuum phenomenon so long as the soil is saturated and swells and shrinks in the normal range. Macroscale heterogeneity superimposed on the inherent microscale heterogeneity can take many forms and may pose difficulties in the definition and measurement of soil physical properties and also in the development and use of predictive theories of soil-water behaviour. Thus, measurement techniques appropriate for uniform soils are often inappropriate, and criteria for soil-water management, obtained from theoretical considerations of behaviour in equivalent uniform soils, are not applicable without modification when there is soil heterogeneity. The spatial variability of soil-water properties is shown in results from field experiments concerned with water flow measurements; these illustrate both stochastic and deterministic heterogeneity in soil-water properties. Problems of water management of spatially variable soils when there is stochastic heterogeneity appear to present an insuperable problem in the application of theory. However, for soils showing deterministic heterogeneity, soil-water theory has been used in the solution of soil-water management problems. Thus, scaling using similar media theory has been applied to the infiltration of water into soils that vary over a catchment area. Also, the drain spacing to control the water-table height in soils in which the hydraulic conductivity varies with depth has been calculated using groundwater seepage theory. (author)

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.

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.

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)

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)

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

Seasonal variability of soil aggregate stability

Czech Academy of Sciences Publication Activity Database

Rohošková, M.; Kodešová, R.; Jirků, V.; Žigová, Anna; Kozák, J.

2009-01-01

Roč. 11, - (2009), , , EGU2009-6341-3-EGU2009-6341-3 ISSN 1029-7006. [European Geosciences Union General Assembly. 19.04.2009-24.04.2009, Vienna] R&D Projects: GA ČR GA526/08/0434 Institutional research plan: CEZ:AV0Z30130516 Keywords : seasonal variability * soil aggregate stability * soil types Subject RIV: DF - Soil Science

Predictor variable resolution governs modeled soil types

Science.gov (United States)

Soil mapping identifies different soil types by compressing a unique suite of spatial patterns and processes across multiple spatial scales. It can be quite difficult to quantify spatial patterns of soil properties with remotely sensed predictor variables. More specifically, matching the right scale...

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

International Nuclear Information System (INIS)

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

2015-01-01

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. - Highlights: • Pu in the contaminated soils is associated with the recalcitrant

Descriptive statistics and spatial distributions of geochemical variables associated with manganese oxide-rich phases in the northern Pacific

Science.gov (United States)

Botbol, Joseph Moses; Evenden, Gerald Ian

1989-01-01

Tables, graphs, and maps are used to portray the frequency characteristics and spatial distribution of manganese oxide-rich phase geochemical data, to characterize the northern Pacific in terms of publicly available nodule geochemical data, and to develop data portrayal methods that will facilitate data analysis. Source data are a subset of the Scripps Institute of Oceanography's Sediment Data Bank. The study area is bounded by 0° N., 40° N., 120° E., and 100° W. and is arbitrarily subdivided into 14-20°x20° geographic subregions. Frequency distributions of trace metals characterized in the original raw data are graphed as ogives, and salient parameters are tabulated. All variables are transformed to enrichment values relative to median concentration within their host subregions. Scatter plots of all pairs of original variables and their enrichment transforms are provided as an aid to the interpretation of correlations between variables. Gridded spatial distributions of all variables are portrayed as gray-scale maps. The use of tables and graphs to portray frequency statistics and gray-scale maps to portray spatial distributions is an effective way to prepare for and facilitate multivariate data analysis.

Mineralogical and geochemical study of contaminated soils on abandoned Sb deposits Dubrava and Poproc

International Nuclear Information System (INIS)

Klimko, T.; Jurkovic, L.

2010-01-01

In this paper we present initial results of mineralogical and geochemical study of secondary mineral phases, often with a high content of Sb and As, resulting from oxidation of sulphide minerals in the soil environment on two, now abandoned Sb deposits. Dubrava deposit is situated on the northern slopes of the Dumbier Low Tatras and Poproc deposit is located in the eastern part of Spis-Gemer Rudohorie. Both studied sites were in the past (second half of 20 th century) significant producers of antimony ore and Dubrava deposit belonged to medium-sized Sb deposits in the world.

Effects of short-term variability of meteorological variables on soil temperature in permafrost regions

Science.gov (United States)

Beer, Christian; Porada, Philipp; Ekici, Altug; Brakebusch, Matthias

2018-03-01

Effects of the short-term temporal variability of meteorological variables on soil temperature in northern high-latitude regions have been investigated. For this, a process-oriented land surface model has been driven using an artificially manipulated climate dataset. Short-term climate variability mainly impacts snow depth, and the thermal diffusivity of lichens and bryophytes. These impacts of climate variability on insulating surface layers together substantially alter the heat exchange between atmosphere and soil. As a result, soil temperature is 0.1 to 0.8 °C higher when climate variability is reduced. Earth system models project warming of the Arctic region but also increasing variability of meteorological variables and more often extreme meteorological events. Therefore, our results show that projected future increases in permafrost temperature and active-layer thickness in response to climate change will be lower (i) when taking into account future changes in short-term variability of meteorological variables and (ii) when representing dynamic snow and lichen and bryophyte functions in land surface models.

Assessment of diagenetic alteration of dinosaur eggshells through petrography and geochemical analysis

Science.gov (United States)

Enriquez, M. V.; Eagle, R.; Eiler, J. M.; Tripati, A. K.; Ramirez, P. C.; Loyd, S. J.; Chiappe, L.; Montanari, S.; Norell, M.; Tuetken, T.

2012-12-01

Carbonate clumped isotope analysis of fossil eggshells has the potential to constrain both the physiology of extinct animals and, potentially, paleoenvironmental conditions, especially when coupled with isotopic measurements of co-occurring soil carbonates. Eggshell samples from both modern vertebrates and Cretaceous Hadrosaurid, Oviraptorid, Titanosaur, Hypselosaurus, Faveoolithus, dinosaur fossils have been collected from Auca Mahuevo, Argentina and Rousett, France, amongst other locations, for geochemical analysis to determine if isotopic signatures could be used to indicate warm- or cold-bloodedness. In some locations soil carbonates were also analyzed to constrain environmental temperatures. In order to test the validity of the geochemical results, an extensive study was undertaken to establish degree of diagenetic alteration. Petrographic and cathodoluminescence characterization of the eggshells were used to assess diagenetic alteration. An empirical 1-5 point scale was used to assign each sample an alteration level, and the observations were then compared with the geochemical results. Specimens displayed a wide range of alteration states. Some of which were well preserved and others highly altered. Another group seemed to be structural intact and only under cathodoluminescence was alteration clearly observed. In the majority of samples, alteration level was found to be predictably related to geochemical results. From specimens with little evidence for diagenesis, carbonate clumped isotope signatures support high (37-40°C) body temperature for Titanosaurid dinosaurs, but potentially lower body temperatures for other taxa. If these data do, in fact, represent original eggshell growth temperatures, these results support variability in body temperature amongst Cretaceous dinosaurs and potentially are consistent with variations between adult body temperature and size — a characteristic of 'gigantothermy'.

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

Geochemical modeling of reactions and partitioning of trace metals and radionuclides during titration of contaminated acidic sediments.

Science.gov (United States)

Zhang, Fan; Luo, Wensui; Parker, Jack C; Spalding, Brian P; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

2008-11-01

Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This studywas undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/ dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO4(2-) for contaminated sediments indicated close agreement suggesting that the model could potentially be used to predictthe acid-base behavior of the sediment-solution system under variable pH conditions.

Geochemical assessment of light gaseous hydrocarbons in near ...

Indian Academy of Sciences (India)

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 ... Kalpana1 D J Patil1 A M Dayal1. National Geophysical Research Institute, Uppal Road, Hyderabad 500606, India.

Geochemical Modeling Of F Area Seepage Basin Composition And Variability

International Nuclear Information System (INIS)

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

2012-01-01

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 affecting basin

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

Directory of Open Access Journals (Sweden)

C. Bastianelli

2017-07-01

Full Text Available 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

Geochemical controls on the composition of soil pore waters beneath a mixed waste disposal site in the unsaturated zone

International Nuclear Information System (INIS)

Rawson, S.A.; Hubbell, J.M.

1989-01-01

Soil pore waters are collected routinely to monitor a thick unsaturated zone that separates a mixed waste disposal site containing transuranic and low-level radioactive wastes from the Snake River Plain aquifer. The chemistry of the soil pore waters has been studied to evaluate the possible control on the water composition by mineral equilibria and determine the extent, if any, of migration of radionuclides from the disposal site. Geochemical codes were used to perform speciation calculations for the waters. The results of speciation calculations suggest that the installation of the lysimeters affects the observed silica contents of the soil pore waters. The results also establish those chemical parameters that are controlled by secondary mineral precipitation. 15 refs., 6 figs., 1 tab

Regional geochemical maps of uranium in Northern Scotland. Environmental and economic considerations

International Nuclear Information System (INIS)

Plant, J.

1978-01-01

The Institute of Geological Studies geochemical mapping programme is outlined. The natural levels of uranium in rocks, soils and waters are discussed. Some practical details of geochemical mapping are given. Applications of geochemical maps of uranium in Scotland are considered: economic applications and medical geography and agriculture. A list of 38 references is appended. (U.K.)

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

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

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.

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

International Nuclear Information System (INIS)

Mao, L.C.; Young, S.D.; Tye, A.M.; Bailey, E.H.

2017-01-01

Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-value as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu solubility was dependent on humic acid content. Lead solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables. Trace metal reactivity in urban soils depends on both soil properties and the original source material

Geochemical approach to evaluate deforest of mangroves

OpenAIRE

Ishiga, Hiroaki; Diallo, Ibrahima M'bemba; Bah Mamadou Lamine Malick,; Ngulimi. Faustine Miguta,; Magai. Paschal Justin,; Shati Samwel Stanley,

2016-01-01

Processes of mangrove deforest related human activities were examined. To evaluate changes of soil feature, multielements geochemical compositions of mangrove muds and soils of deforest were analyzed. To describe present situation of the mangrove, Conakry in Guinea, Dar es Salaam in Tanzania, Sundarbans of Bangladesh and Nago in Okinawa of Japan were selected. Soil samples of the forests were evaluated enrichment of biologically concentrated heavy metals such as Zn, Cu and Fe, and TS (total s...

Geochemical composition of permafrost-affected soils around the town Tiksi, Northern Yakutia, Russia

Science.gov (United States)

Antcibor, Iuliia; Eschenbach, Annette; Pfeiffer, Eva-Maria

2014-05-01

Northeastern Siberia represents an area remote from evident anthropogenic trace metal sources. However, a risk of airborne pollution by trace metals from anthropogenic sources connected to the settlements exists. The largest of these are the settlements Tiksi (71° 42' 55.6" N, 128° 48' 46.3" E) and Kyusyur (70° 45' 41.7" N, 127° 23' 04.7" E). The area of Tiksi is located between the Lena River and the Kharaulach River mouths. It covers parts of Primorsky Ridge and Kharaulach Mountains which are a part of the Verkhoyansk Range. The objective of this study was to investigate features of the spatial element distribution in representative landscape-geochemical units of the Tiksi area and to identify whether local pollution from the settlement takes place. The physical and chemical properties of soils were accessed at three sites located radially in the immediate vicinity to the town Tiksi and one control site remote 10 km south from the settlement. The elements measured were As, Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn in soils. Differences in the element content were found for various relief forms (depressions, slopes, and elevations). The coefficient of soil buffer capacity (Bf) for the surface soil horizons in depressions was the highest (Bf > 40 %) for the majority of elements indicating their intensive accumulation there. In the surface soil horizons of elevated landscape forms the coefficient, by contrast showed low to very low soil buffer capacity to accumulate metals (0 % acid-base barriers. No significant difference in metal distribution among studied sites was revealed, except for the western site which was characterized by the highest median Ni concentration. The data suggest that ecological impacts at the studied sites were low except for one site north to Tiksi where signs of local pollution probably as a result of local emissions of fuel and mining operations were detected. Keywords: Trace metals; Russian Arctic; Northeastern Siberia; Permafrost

Magnetic and geochemical characterization of Andosols developed on basalts in the Massif Central, France

Science.gov (United States)

Grison, Hana; Petrovsky, Eduard; Stejskalova, Sarka; Kapicka, Ales

2015-05-01

Identification of Andosols is primarily based upon the content of their colloidal constituents—clay and metal-humus complexes—and on the determining of andic properties. This needs time and cost-consuming geochemical analyses. Our primary aim of this study is to describe the magnetic and geochemical properties of soils rich in iron oxides derived from strongly magnetic volcanic basement (in this case Andosols). Secondary aim is to explore links between magnetic and chemical parameters of andic soils with respect to genesis factors: parent material age, precipitation, and thickness of the soil profile. Six pedons of andic properties, developed on basaltic lavas, were analyzed down to parent rock by a set of magnetic and geochemical methods. Magnetic data of soil and rock samples reflect the type, concentration, and particle-size distribution of ferrimagnetic minerals. Geochemical data include soil reaction (pH in H2O), cation exchange capacity, organic carbon, and different forms of extractable iron and aluminum content. Our results suggest the following: (1) magnetic measurements of low-field mass-specific magnetic susceptibility can be a reliable indicator for estimating andic properties, and in combination with thermomagnetic curves may be suitable for discriminating between alu-andic and sil-andic subtypes. (2) In the studied Andosols, strong relationships were found between (a) magnetic grain-size parameters, precipitation, and exchangeable bases; (b) concentration of ferrimagnetic particles and degree of crystallization of free iron; and (c) parameters reflecting changes in magneto-mineralogy and soil genesis (parent material age + soil depth).

Behaviour of nature and technogenic radioisotopes in buried geochemical barriers

International Nuclear Information System (INIS)

Kuznetsov, V.A.; Onoshko, M.P.; Generalova, V.A.

1998-01-01

Behaviour of potassium 40, radium 226, thorium 232, strontium 90 and cesium 137 on geochemical barriers connected with buried soils and cut-off meander sediments of the Holocene age of the Sozh river valley are examined. Some sides of the barrier geochemical structure caused by syngeneic and epigenetic processes have been taken into consideration

Influence of management history and landscape variables on soil organic carbon and soil redistribution

Science.gov (United States)

Venteris, E.R.; McCarty, G.W.; Ritchie, J.C.; Gish, T.

2004-01-01

Controlled studies to investigate the interaction between crop growth, soil properties, hydrology, and management practices are common in agronomy. These sites (much as with real world farmland) often have complex management histories and topographic variability that must be considered. In 1993 an interdisiplinary study was started for a 20-ha site in Beltsville, MD. Soil cores (271) were collected in 1999 in a 30-m grid (with 5-m nesting) and analyzed as part of the site characterization. Soil organic carbon (SOC) and 137Cesium (137Cs) were measured. Analysis of aerial photography from 1992 and of farm management records revealed that part of the site had been maintained as a swine pasture and the other portion as cropped land. Soil properties, particularly soil redistribution and SOC, show large differences in mean values between the two areas. Mass C is 0.8 kg m -2 greater in the pasture area than in the cropped portion. The pasture area is primarily a deposition site, whereas the crop area is dominated by erosion. Management influence is suggested, but topographic variability confounds interpretation. Soil organic carbon is spatially structured, with a regionalized variable of 120 m. 137Cs activity lacks spatial structure, suggesting disturbance of the profile by animal activity and past structures such as swine shelters and roads. Neither SOC nor 137Cs were strongly correlated to terrain parameters, crop yields, or a seasonal soil moisture index predicted from crop yields. SOC and 137Cs were weakly correlated (r2 ???0.2, F-test P-value 0.001), suggesting that soil transport controls, in part, SOC distribution. The study illustrates the importance of past site history when interpreting the landscape distribution of soil properties, especially those strongly influenced by human activity. Confounding variables, complex soil hydrology, and incomplete documentation of land use history make definitive interpretations of the processes behind the spatial distributions

Topographic variability influences the carbon sequestration potential of arable soils

DEFF Research Database (Denmark)

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

2012-01-01

There is presently limited knowledge on the influence of field spatial variability on the carbon (C) sink-source relationships in arable landscapes. This is accompanied by the fact that our understanding of soil profile C dynamics is also limited. This study aimed at investigating how spatial...... results indicated that variability across arable landscapes makes footslope soils both a larger sink of buried soil C and a bigger potential CO2 source than upslope soils....

Contemporaneous deposition of phyllosilicates and sulfates: Using Australian acidic saline lake deposits to describe geochemical variability on Mars

Science.gov (United States)

Baldridge, A.M.; Hook, S.J.; Crowley, J.K.; Marion, G.M.; Kargel, J.S.; Michalski, J.L.; Thomson, B.J.; de Souza, Filho C.R.; Bridges, N.T.; Brown, A.J.

2009-01-01

Studies of the origin of the Martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked, global-scale change in the Mars environment from circum-neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to Hesperian. However, terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation.Western Australian acidic playa lakes have large pH differences separated vertically and laterally by only a few tens of meters, demonstrating how highly variable chemistries can coexist over short distances in natural environments. We suggest diverse and variable Martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the Australian sites are analogs for regions where phyllosilicates and sulfates coexist on Mars. In these systems, Fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater, whereas aluminous phyllosilicates and sulfates represent near-surface evaporitic facies formed from more acidic brines. Copyright 2009 by the American Geophysical Union.

Applications of prospecting geochemical techniques to the search for and to the study of uranium deposits in metropolitan France

International Nuclear Information System (INIS)

Grimbert, Arnold

1957-01-01

After having recalled facts which leaded the CEA to use new geochemical techniques for the prospecting of uranium deposits through sampling and analysis of soils and waters, the author describes the organisation and methods implemented for this prospecting activity: team composition for sampling and analysis, role of each engineer and technician in the prospecting stages (preliminary study, routine prospecting, result interpretation), sampling and analysis processes. He also reports campaigns of geochemical prospecting: study of the La Chapelle Largeau deposit (objectives, geological context, preliminary study, routine prospecting, study of geochemical anomalies), tactical research on Verneix indices (study of radioactivity anomaly discovered by radio-prospecting), strategical searches in a non prospected area in the South of Avallon. The author discusses the issues of efficiency and cost price of this geochemical prospecting technique in soils and in waters. Appendices present the equipment and operation modality for soil sampling, and for soil sample preparation, and principles, equipment and products for soil analysis and for water analysis [fr

Concerning evaluation of eco-geochemical background in remediation strategy

Science.gov (United States)

Korobova, Elena; Romanov, Sergey

2015-04-01

The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

Statistical treatment of geochemical data and its application in the geologic mapping and in the definition of the geochemical anomalies in the Alvo 2-Corpo 4 -Provincia Mineral de Carajas

International Nuclear Information System (INIS)

Moura, C.A.V.

1982-01-01

It was given a statistical treatment for the geochemical data about soil in the are named Alvo2 - Corpo4- in the Provincia Mineral de Carajas, Para, Brazil, for application of the geological mapping and definition of geochemical anomalies. (A.B.) [pt

Integrated assessment of space, time, and management-related variability of soil hydraulic properties

Energy Technology Data Exchange (ETDEWEB)

Es, H.M. van; Ogden, C.B.; Hill, R.L.; Schindelbeck, R.R.; Tsegaye, T.

1999-12-01

Computer-based models that simulate soil hydrologic processes and their impacts on crop growth and contaminant transport depend on accurate characterization of soil hydraulic properties. Soil hydraulic properties have numerous sources of variability related to spatial, temporal, and management-related processes. Soil type is considered to be the dominant source of variability, and parameterization is typically based on soil survey databases. This study evaluated the relative significance of other sources of variability: spatial and temporal at multiple scales, and management-related factors. Identical field experiments were conducted for 3 yr. at two sites in New York on clay loam and silt loam soils, and at two sites in Maryland on silt loam and sandy loam soils, all involving replicated plots with plow-till and no-till treatments. Infiltrability was determined from 2054 measurements using parameters, and Campbell's a and b parameters were determined based on water-retention data from 875 soil cores. Variance component analysis showed that differences among the sites were the most important source of variability for a (coefficient of variation, CV = 44%) and b (CV = 23%). Tillage practices were the most important source of variability for infiltrability (CV = 10%). For all properties, temporal variability was more significant than field-scale spatial variability. Temporal and tillage effects were more significant for the medium- and fine-textured soils, and correlated to initial soil water conditions. The parameterization of soil hydraulic properties solely based on soil type may not be appropriate for agricultural lands since soil-management factors are more significant. Sampling procedures should give adequate recognition to soil-management and temporal processes at significant sources of variability to avoid biased results.

Role of environmental variables on radon concentration in soil

International Nuclear Information System (INIS)

Climent, H.; Bakalowicz, M.; Monnin, M.

1998-01-01

In the frame of an European project, radon concentrations in soil and measurements of environmental variables such as the nature of the soil or climatic variables were monitored. The data have been analysed by time-series analysis methods, i.e. Correlation and Spectrum Analysis, to point out relations between radon concentrations and some environmental variables. This approach is a compromise between direct observation and modelling. The observation of the rough time series is unable to point out the relation between radon concentrations and an environmental variable because of the overlapping of the influences of several variables, and the time delay induced by the medium. The Cross Spectrum function between the time series of radon and of an environmental variable describes the nature of the relation and gives the response time in the case of a cause to effect relation. It requires the only hypothesis that the environmental variable is the input function and radon concentration the output function. This analysis is an important preliminary study for modelling. By that way the importance of soil nature has been pointed out. The internal variables of the medium (permeability, porosity) appear to restrain the influence of the environmental variables such as humidity, temperature or atmospheric pressure. (author)

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.

[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 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 variable temperature mainly influenced SOC mineralization by changing microbial community activity rather than by changing microbial quantity.

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.

Soil gas radon response to environmental and soil physics variables

International Nuclear Information System (INIS)

Thomas, D.M.; Chen, C.; Holford, D.

1991-01-01

During the last three years a field study of soil gas radon activities conducted at Poamoho, Oahu, has shown that the primary environmental variables that control radon transport in shallow tropical soils are synoptic and diurnal barometric pressure changes and soil moisture levels. Barometric pressure changes drive advective transport and mixing of soil gas with atmospheric air; soil moisture appears to control soil porosity and permeability to enhance or inhibit advective and diffusive radon transport. An advective barrier test/control experiment has shown that advective exchange of soil gas and air may account for a substantial proportion of the radon loss from shallow soils but does not significantly affect radon activities at depths greater than 2.3 m. An irrigation test/control experiment also suggests that, at soil moisture levels approaching field capacity, saturation of soil macroporosity can halt all advective transport of radon and limit diffusive mobility to that occurring in the liquid phase. The results of the authors field study have been used to further refine and extend a numerical model, RN3D, that has been developed by Pacific Northwest Laboratories to simulate subsurface transport of radon. The field data have allowed them to accurately simulate the steady state soil gas radon profile at their field site and to track transient radon activities under the influence of barometric pressure changes and in response to changes in soil permeability that result from variations in soil moisture levels. Further work is continuing on the model to enable it to properly account for the relative effects of advective transport of soil gas through cracks and diffusive mobility in the bulk soils

The Guadiamar soils: characterization and evolution of soils affected by the pyrite sludge; Los suelos del Guadiamar: estudios de caracterizacion y de la evolucion de los suelos contaminados por el lodo

Energy Technology Data Exchange (ETDEWEB)

Alonso, C.; Anton-Pacheco, C.; Barettino, D.; Lopez Pamo, E. [Instituto Geologico y Minero de Espana. Madrid (Spain); Cabrera, F.; Fernandez, J. E.; Giron, I. F.; Moreno, F. [Instituto de Recursos Naturales y Agrobiologia de Sevilla (Spain); Fernandez, A. M.; Garcia-Gutierrez, M.; Pelayo, M.; Rivas, P.; Villar, M. V. [Ciemat. Madrid (Spain); Giraldez, J. V.; Vanderlinden, K. [Universidad de Cordoba (Spain); Ordonez, R. [CIFA. Cordoba (Spain)

2001-07-01

The study of the geochemical background shows the evidence of high contents in heavy metals in the soils from the affected area of the Guadimar basin before the Aznalcollar mine spill. This means a previous contamination due to the Aznalcollar mineralizations, and above all, to the intense mining works of the last two decades. Two areas been defined, with different geochemical background: Guadiamar alluvial soils and soils over the marsh deposits in the southern area of the affected zone. These southern soils have, higher contents of iron, zinc and copper and slightly lower of lead and arsenic, compared to the contents from the alluvial. The soils of the affected area of the Guadiamar basin are quite heterogeneous and show a high spatial variability of its physical and mineralogical characteristics. Once the sludge removal operations are finished, a high spatial variability of the concentration of soils of different elements related to the contamination has been observed. This variability is observed at a very small scale, so that in a few metres this concentrations vary in some order of magnitude. This variability is also related to the remnant sludge, because the cleanup did not remove the whole of the mining waste, and this remaining part has been incorporated to the soils during the soil remediation operations. At a basin scale, an important increase of the contaminant concentrations has been observed in the upper part of the soils. This concentration mean values are from 3 to 6 times the geochemical background levels, depending on the element considered. These increase are higher for zinc, and lower for lead, arsenic and copper, in that order. The concentrations of these elements in soils decrease with the depth. The highest concentrations for arsenic and lead were observed in the zone where the pyritic sludge was deposited, whereas the highest zinc concentrations are determined in the southern part, where the acid water were retained. After the soil

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

Science.gov (United States)

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

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 n-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 n-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.

Geochemical Investigations In Soils And Waters Of Ischia Island (southern Italy)

Science.gov (United States)

Avino, R.; Capaldi, G.; Di Matteo, V.; Pece, R.

The island of Ischia is localized in the Gulf of Naples and is a volcanic field belonging to the volcanic district of the Phlegraean Fields. It covers an area of about 42 Km2 and is characterized by a complex system of faults and fractures of tectonic and volcano- tectonic origin. The highest peak of the island is Mt Epomeo (787 m), situated in the central part of Ischia. The last eruption on this island took place in 1302 (Arso) and from that time the volcanic activity has reduced only to hydrothermal manifestations (fumaroles and thermal springs) localized especially along the faults that border Mt Epomeo. So the area around the Epomeo is an area of great interest for geochemical investigations, and in fact in this place high concentration of mercury, carbon dioxide and radon have been measured. In this work are presented the data of a study on the concentration of CO2 and mercury and of the activity of radon in the soils and in the waters of the island of Ischia. For these investigations 184 samples of soils have been collected and analyzed in laboratory to calculate the concentration of mercury using the Jerome 511 Mercury Vapor Analyzer. In the same sampling sites measurements of CO2 and of the activity of radon-222 in the soils have also been made using the Track- etch@ method. As regards the waters, a sampling of 50 wells localized all around the coast of the island has been carried out. In these waters measures of mercury and of the activity of some radioactive elements have been done. The measures of radioactivity has been carried out by gamma spectrometry with a HPE Ge detector. All the investigations (in soils and in waters) allow to have preliminary information about the concentrations of these investigated elements and will be a starting-point for a more detailed sampling in those place where anomalies have been found. This set of data can also help to better understand the degassing process of these elements through the principal structures of the

Soil erodibility variability in laboratory and field rainfall simulations

Science.gov (United States)

Szabó, Boglárka; Szabó, Judit; Jakab, Gergely; Centeri, Csaba; Szalai, Zoltán

2017-04-01

Rainfall simulation experiments are the most common way to observe and to model the soil erosion processes in in situ and ex situ circumstances. During modelling soil erosion, one of the most important factors are the annual soil loss and the soil erodibility which represent the effect of soil properties on soil loss and the soil resistance against water erosion. The amount of runoff and soil loss can differ in case of the same soil type, while it's characteristics determine the soil erodibility factor. This leads to uncertainties regarding soil erodibility. Soil loss and soil erodibility were examined with the investigation of the same soil under laboratory and field conditions with rainfall simulators. The comparative measurement was carried out in a laboratory on 0,5 m2, and in the field (Shower Power-02) on 6 m2 plot size where the applied slope angles were 5% and 12% with 30 and 90 mm/h rainfall intensity. The main idea was to examine and compare the soil erodibility and its variability coming from the same soil, but different rainfall simulator type. The applied model was the USLE, nomograph and other equations which concern single rainfall events. The given results show differences between the field and laboratory experiments and between the different calculations. Concerning for the whole rainfall events runoff and soil loss, were significantly higher at the laboratory experiments, which affected the soil erodibility values too. The given differences can originate from the plot size. The main research questions are that: How should we handle the soil erodibility factors and its significant variability? What is the best solution for soil erodibility determination?

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

A hydro-geochemical study of Nahr-Ibrahim catchment area: Fluvial metal transport

International Nuclear Information System (INIS)

Korfali, Samira

2004-01-01

Author.Metals enter water bodies geological weathering, soil erosion, industrial and domestic waste discharges, as well as atmospheric deposition. The metal content in sediments is a reflection of the nature of their background whether of geologic and/or anthropogenic origin. The depositional process of metals in sediment are controlled by river discharge, turbulence of river, morphology and river geometry, as well as the geochemical phases of sediment and soils. Thus a study of metal content in river and /or metal transport with a water body should include a hydrological study of the river, types of minerals in sediment and soil, sediment and soil textures, and metal speciation in the different geochemical phases of sediment, bank and soils. A contaminated flood plain is a temporary storage system for pollutants and an understanding of soil-sediment-interactions is important prerequisite for modeling fluvial pollutant transport. The determination of metal speciation in sediment and soil chemical fraction can provide information on the way in which these metals are bound to sediment and soil, their mobilization potential, bioavailability and possible mechanism of fluvial pollutant transport. Sequential extraction techniques yielding operationally defined chemical pools have been used by many workers to examine the partitioning of metals among the various geochemical phases of sediment or soil. The sequential extraction method specifies metals in sediment fractions as: exchangeable, specifically sorbed, easily reducible, moderately reducible, organic, residual. Previously, I have conducted a study on speciation of metals (Fe, Mn, Zn, Cu, Pb and Cd) in the dry season bed-load sediments only at five sites 13 km stretch upstream from the mouth of Nahr Ibrahim. The reported data revealed that the specifically sorbed sediment fraction was the prime fraction for deposition of Mn, Z, CU, Pb and Cd metals in sediments. X-ray diffraction analysis of bed sediments showed

Modeling Short-Range Soil Variability and its Potential Use in Variable-Rate Treatment of Experimental Plots

Directory of Open Access Journals (Sweden)

A Moameni

2011-02-01

Full Text Available Abstract In Iran, the experimental plots under fertilizer trials are managed in such a way that the whole plot area uniformly receives agricultural inputs. This could lead to biased research results and hence to suppressing of the efforts made by the researchers. This research was conducted in a selected site belonging to the Gonbad Agricultural Research Station, located in the semiarid region, northeastern Iran. The aim was to characterize the short-range spatial variability of the inherent and management-depended soil properties and to determine if this variation is large and can be managed at practical scales. The soils were sampled using a grid 55 m apart. In total, 100 composite soil samples were collected from topsoil (0-30 cm and were analyzed for calcium carbonate equivalent, organic carbon, clay, available phosphorus, available potassium, iron, copper, zinc and manganese. Descriptive statistics were applied to check data trends. Geostatistical analysis was applied to variography, model fitting and contour mapping. Sampling at 55 m made it possible to split the area of the selected experimental plot into relatively uniform areas that allow application of agricultural inputs with variable rates. Keywords: Short-range soil variability, Within-field soil variability, Interpolation, Precision agriculture, Geostatistics

Spatial variability of soil CO2 emission in different topographic positions

Directory of Open Access Journals (Sweden)

Liziane de Figueiredo Brito

2010-01-01

Full Text Available The spatial variability of soil CO2 emission is controlled by several properties related to the production and transport of CO2 inside the soil. Considering that soil properties are also influenced by topography, the objective of this work was to investigate the spatial variability of soil CO2 emission in three different topographic positions in an area cultivated with sugarcane, just after mechanical harvest. One location was selected on a concave-shaped form and two others on linear-shaped form (in back-slope and foot-slope. Three grids were installed, one in each location, containing 69 points and measuring 90 x 90 m each. The spatial variability of soil CO2 emission was characterized by means of semivariance. Spatial variability models derived from soil CO2 emission were exponential in the concave location while spherical models fitted better in the linear shaped areas. The degree of spatial dependence was moderate in all cases and the range of spatial dependence for the CO2 emission in the concave area was 44.5 m, higher than the mean value obtained for the linear shaped areas (20.65 m. The spatial distribution maps of soil CO2 emission indicate a higher discontinuity of emission in the linear form when compared to the concave form.

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

International Nuclear Information System (INIS)

Hofman, Jakub; Hovorková, Ivana; Semple, Kirk T.

2014-01-01

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 14 C-phenanthrene and 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

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.

The spatial variability in studies of soil physical condition

International Nuclear Information System (INIS)

Madero M, Edgar; Herrera G Oscar A; Castano C, Alirio

2000-01-01

The testing procedure was carried out in 1996-2 at the experimental station of the Universidad Nacional de Colombia in Palmira using vertical tillage (by chiseling) in coherent vertisol (typic Haplustert isohiperthermic fine loamy 1%). eight physical properties in depth of 15-25 cm were studied. the sampling methodology for soil physical properties and corn yield accounted the regionalized variable, and the analysis of results was carried out accounting a map of each variable. the results proved that geostatystics is versatile and give accuracy results. it showed in most of the area that vertical tillage was more favorable than conventional tillage to improve coherence (more soil penetrability without degradation) in seedbed zone. it was not found influence over corn yield. soil organic matter; clay and silt had influence over the soil response to mechanical strengths

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

Science.gov (United States)

Reichstein, Markus; Rey, Ana; Freibauer, Annette; Tenhunen, John; Valentini, Riccardo; Banza, Joao; Casals, Pere; Cheng, Yufu; Grünzweig, Jose M.; Irvine, James; Joffre, Richard; Law, Beverly E.; Loustau, Denis; Miglietta, Franco; Oechel, Walter; Ourcival, Jean-Marc; Pereira, Joao S.; Peressotti, Alessandro; Ponti, Francesca; Qi, Ye; Rambal, Serge; Rayment, Mark; Romanya, Joan; Rossi, Federica; Tedeschi, Vanessa; Tirone, Giampiero; Xu, Ming; Yakir, Dan

2003-12-01

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g., leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical nonlinear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content, and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and intersite variability of soil respiration with a mean absolute error of 0.82 μmol m-2 s-1. The parameterized model exhibits the following principal properties: (1) At a relative amount of upper-layer soil water of 16% of field capacity, half-maximal soil respiration rates are reached. (2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. (3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly timescale, we employed the approach by [2002] that used monthly precipitation and air temperature to globally predict soil respiration (T&P model). While this model was able to

Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

Science.gov (United States)

Reichstein, M.; Rey, A.; Freibauer, A.; Tenhunen, J.; Valentini, R.; Soil Respiration Synthesis Team

2003-04-01

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g. leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical non-linear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and inter-site variability of soil respiration with a mean absolute error of 0.82 µmol m-2 s-1. The parameterised model exhibits the following principal properties: 1) At a relative amount of upper-layer soil water of 16% of field capacity half-maximal soil respiration rates are reached. 2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. 3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly time-scale we employed the approach by Raich et al. (2002, Global Change Biol. 8, 800-812) that used monthly precipitation and air temperature to globally predict soil respiration (T

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).

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

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

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 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...

Predictive geochemical mapping using environmental correlation

International Nuclear Information System (INIS)

Wilford, John; Caritat, Patrice de; Bui, Elisabeth

2016-01-01

The distribution of chemical elements at and near the Earth's surface, the so-called critical zone, is complex and reflects the geochemistry and mineralogy of the original substrate modified by environmental factors that include physical, chemical and biological processes over time. Geochemical data typically is illustrated in the form of plan view maps or vertical cross-sections, where the composition of regolith, soil, bedrock or any other material is represented. These are primarily point observations that frequently are interpolated to produce rasters of element distributions. Here we propose the application of environmental or covariate regression modelling to predict and better understand the controls on major and trace element geochemistry within the regolith. Available environmental covariate datasets (raster or vector) representing factors influencing regolith or soil composition are intersected with the geochemical point data in a spatial statistical correlation model to develop a system of multiple linear correlations. The spatial resolution of the environmental covariates, which typically is much finer (e.g. ∼90 m pixel) than that of geochemical surveys (e.g. 1 sample per 10-10,000 km 2 ), carries over to the predictions. Therefore the derived predictive models of element concentrations take the form of continuous geochemical landscape representations that are potentially much more informative than geostatistical interpolations. Environmental correlation is applied to the Sir Samuel 1:250,000 scale map sheet in Western Australia to produce distribution models of individual elements describing the geochemical composition of the regolith and exposed bedrock. As an example we model the distribution of two elements – chromium and sodium. We show that the environmental correlation approach generates high resolution predictive maps that are statistically more accurate and effective than ordinary kriging and inverse distance weighting interpolation

Multiscale analysis of the spatial variability of heavy metals and organic matter in soils and groundwater across Spain

Science.gov (United States)

Luque-Espinar, J. A.; Pardo-Igúzquiza, E.; Grima-Olmedo, J.; Grima-Olmedo, C.

2018-06-01

During the last years there has been an increasing interest in assessing health risks caused by exposure to contaminants found in soil, air, and water, like heavy metals or emerging contaminants. This work presents a study on the spatial patterns and interaction effects among relevant heavy metals (Sb, As and Pb) that may occur together in different minerals. Total organic carbon (TOC) have been analyzed too because it is an essential component in the regulatory mechanisms that control the amount of metal in soils. Even more, exposure to these elements is associated with a number of diseases and environmental problems. These metals can have both natural and anthropogenic origins. A key component of any exposure study is a reliable model of the spatial distribution the elements studied. A geostatistical analysis have been performed in order to show that selected metals are auto-correlated and cross-correlated and type and magnitude of such cross-correlation varies depending on the spatial scale under consideration. After identifying general trends, we analyzed the residues left after subtracting the trend from the raw variables. Three scales of variability were identified (compounds or factors) with scales of 5, 35 and 135 km. The first factor (F1) basically identifies anomalies of natural origin but, in some places, of anthropogenics origin as well. The other two are related to geology (F2 and F3) although F3 represents more clearly geochemical background related to large lithological groups. Likewise, mapping of two major structures indicates that significant faults have influence on the distribution of the studied elements. Finally, influence of soil and lithology on groundwater by means of contingency analysis was assessed.

Spatial variability of physical properties of tropical soil

International Nuclear Information System (INIS)

Reichardt, K.; Libardi, P.L.; Queiroz, S.V.; Grohmann, F.

1976-04-01

A basic study with objectives of improving the use of soil and water resources under a particular condition and of developing means for controlling the dynamics of soil-water movement are presented. Special emphasis is given to the variability in space of geometric soil properties such as bulk density, particle density and texture in order to make it possible to define representative means which ideed will be usable to describe the movement of water and of salt in the entire field

Aspect-related Vegetation Differences Amplify Soil Moisture Variability in Semiarid Landscapes

Science.gov (United States)

Yetemen, O.; Srivastava, A.; Kumari, N.; Saco, P. M.

2017-12-01

Soil moisture variability (SMV) in semiarid landscapes is affected by vegetation, soil texture, climate, aspect, and topography. The heterogeneity in vegetation cover that results from the effects of microclimate, terrain attributes (slope gradient, aspect, drainage area etc.), soil properties, and spatial variability in precipitation have been reported to act as the dominant factors modulating SMV in semiarid ecosystems. However, the role of hillslope aspect in SMV, though reported in many field studies, has not received the same degree of attention probably due to the lack of extensive large datasets. Numerical simulations can then be used to elucidate the contribution of aspect-driven vegetation patterns to this variability. In this work, we perform a sensitivity analysis to study on variables driving SMV using the CHILD landscape evolution model equipped with a spatially-distributed solar-radiation component that couples vegetation dynamics and surface hydrology. To explore how aspect-driven vegetation heterogeneity contributes to the SMV, CHILD was run using a range of parameters selected to reflect different scenarios (from uniform to heterogeneous vegetation cover). Throughout the simulations, the spatial distribution of soil moisture and vegetation cover are computed to estimate the corresponding coefficients of variation. Under the uniform spatial precipitation forcing and uniform soil properties, the factors affecting the spatial distribution of solar insolation are found to play a key role in the SMV through the emergence of aspect-driven vegetation patterns. Hence, factors such as catchment gradient, aspect, and latitude, define water stress and vegetation growth, and in turn affect the available soil moisture content. Interestingly, changes in soil properties (porosity, root depth, and pore-size distribution) over the domain are not as effective as the other factors. These findings show that the factors associated to aspect-related vegetation

Year-round estimation of soil moisture content using temporally variable soil hydraulic parameters

Czech Academy of Sciences Publication Activity Database

Šípek, Václav; Tesař, Miroslav

2017-01-01

Roč. 31, č. 6 (2017), s. 1438-1452 ISSN 0885-6087 R&D Projects: GA ČR GA16-05665S Institutional support: RVO:67985874 Keywords : hydrological modelling * pore-size distribution * saturated hydraulic conductivity * seasonal variability * soil hydraulic parameters * soil moisture Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Hydrology Impact factor: 3.014, year: 2016

All-union Conference. Principles and methods of regional and geochemical investigations into radionuclide migration

International Nuclear Information System (INIS)

Khitrov, L.M.

1989-01-01

The collection presents abstracts of papers concerning landscape-geochemical research of radionuclides migration; aspects of 'hot particles' study; radionuclides forms and behaviour in soils, in soil-plant; soil-natural water systems, as well as in water ecosystems. Methods of natural objects artificial radioactivity study are reviewed. Distribution of natural radionuclides in soils. natural waters, etc. is discussed

Application of cluster analysis to geochemical compositional data for identifying ore-related geochemical anomalies

Science.gov (United States)

Zhou, Shuguang; Zhou, Kefa; Wang, Jinlin; Yang, Genfang; Wang, Shanshan

2017-12-01

Cluster analysis is a well-known technique that is used to analyze various types of data. In this study, cluster analysis is applied to geochemical data that describe 1444 stream sediment samples collected in northwestern Xinjiang with a sample spacing of approximately 2 km. Three algorithms (the hierarchical, k-means, and fuzzy c-means algorithms) and six data transformation methods (the z-score standardization, ZST; the logarithmic transformation, LT; the additive log-ratio transformation, ALT; the centered log-ratio transformation, CLT; the isometric log-ratio transformation, ILT; and no transformation, NT) are compared in terms of their effects on the cluster analysis of the geochemical compositional data. The study shows that, on the one hand, the ZST does not affect the results of column- or variable-based (R-type) cluster analysis, whereas the other methods, including the LT, the ALT, and the CLT, have substantial effects on the results. On the other hand, the results of the row- or observation-based (Q-type) cluster analysis obtained from the geochemical data after applying NT and the ZST are relatively poor. However, we derive some improved results from the geochemical data after applying the CLT, the ILT, the LT, and the ALT. Moreover, the k-means and fuzzy c-means clustering algorithms are more reliable than the hierarchical algorithm when they are used to cluster the geochemical data. We apply cluster analysis to the geochemical data to explore for Au deposits within the study area, and we obtain a good correlation between the results retrieved by combining the CLT or the ILT with the k-means or fuzzy c-means algorithms and the potential zones of Au mineralization. Therefore, we suggest that the combination of the CLT or the ILT with the k-means or fuzzy c-means algorithms is an effective tool to identify potential zones of mineralization from geochemical data.

The Impact of Soil Sampling Errors on Variable Rate Fertilization

Energy Technology Data Exchange (ETDEWEB)

R. L. Hoskinson; R C. Rope; L G. Blackwood; R D. Lee; R K. Fink

2004-07-01

Variable rate fertilization of an agricultural field is done taking into account spatial variability in the soil’s characteristics. Most often, spatial variability in the soil’s fertility is the primary characteristic used to determine the differences in fertilizers applied from one point to the next. For several years the Idaho National Engineering and Environmental Laboratory (INEEL) has been developing a Decision Support System for Agriculture (DSS4Ag) to determine the economically optimum recipe of various fertilizers to apply at each site in a field, based on existing soil fertility at the site, predicted yield of the crop that would result (and a predicted harvest-time market price), and the current costs and compositions of the fertilizers to be applied. Typically, soil is sampled at selected points within a field, the soil samples are analyzed in a lab, and the lab-measured soil fertility of the point samples is used for spatial interpolation, in some statistical manner, to determine the soil fertility at all other points in the field. Then a decision tool determines the fertilizers to apply at each point. Our research was conducted to measure the impact on the variable rate fertilization recipe caused by variability in the measurement of the soil’s fertility at the sampling points. The variability could be laboratory analytical errors or errors from variation in the sample collection method. The results show that for many of the fertility parameters, laboratory measurement error variance exceeds the estimated variability of the fertility measure across grid locations. These errors resulted in DSS4Ag fertilizer recipe recommended application rates that differed by up to 138 pounds of urea per acre, with half the field differing by more than 57 pounds of urea per acre. For potash the difference in application rate was up to 895 pounds per acre and over half the field differed by more than 242 pounds of potash per acre. Urea and potash differences

Orientation geochemical survey for uranium exploration using 230Th

International Nuclear Information System (INIS)

Xia Dingliang.

1985-01-01

The distribution of 230 Th in soils, rocks and ores and its relationship with respect to uranium ore formation are discussed for its possible use in geochemical exploration for U. 230 Th, U and Ra, being members of the same decay series, are different in their geochemical behavior upon which the study is orientated. Twenty uranium deposits and occurrences located in western and southern Hunan province are tested. Geochemical data obtained are comprehensively correlated. It is suggested that 230 Th is useful not only in U-Ra disequilibrium study but also in understanding the geochemical evolution of U ores. The data aid to interpret the genesis of uranium deposits and to assess the radioactive anomalies and uranium-bearing zones. Therefore, it can be adopted as a tool for searching in deep-buried uranium ores. The field procedure is rather simple and flexible to meet any geological environment. It is easy to read out and is less influnced by any kind of interference. In case of disequilibrium caused by oxidation and reduction during the period of ore formation it still gives good indication compared with that of radiometry, radonmetry and geochemical sampling for U

Soil chemistry in lithologically diverse datasets: the quartz dilution effect

Science.gov (United States)

Bern, Carleton R.

2009-01-01

National- and continental-scale soil geochemical datasets are likely to move our understanding of broad soil geochemistry patterns forward significantly. Patterns of chemistry and mineralogy delineated from these datasets are strongly influenced by the composition of the soil parent material, which itself is largely a function of lithology and particle size sorting. Such controls present a challenge by obscuring subtler patterns arising from subsequent pedogenic processes. Here the effect of quartz concentration is examined in moist-climate soils from a pilot dataset of the North American Soil Geochemical Landscapes Project. Due to variable and high quartz contents (6.2–81.7 wt.%), and its residual and inert nature in soil, quartz is demonstrated to influence broad patterns in soil chemistry. A dilution effect is observed whereby concentrations of various elements are significantly and strongly negatively correlated with quartz. Quartz content drives artificial positive correlations between concentrations of some elements and obscures negative correlations between others. Unadjusted soil data show the highly mobile base cations Ca, Mg, and Na to be often strongly positively correlated with intermediately mobile Al or Fe, and generally uncorrelated with the relatively immobile high-field-strength elements (HFS) Ti and Nb. Both patterns are contrary to broad expectations for soils being weathered and leached. After transforming bulk soil chemistry to a quartz-free basis, the base cations are generally uncorrelated with Al and Fe, and negative correlations generally emerge with the HFS elements. Quartz-free element data may be a useful tool for elucidating patterns of weathering or parent-material chemistry in large soil datasets.

Effect of source integration on the geochemical fluxes from springs

International Nuclear Information System (INIS)

Frisbee, Marty D.; Phillips, Fred M.; White, Art F.; Campbell, Andrew R.; Liu, Fengjing

2013-01-01

Geochemical fluxes from watersheds are typically defined using mass-balance methods that essentially lump all weathering processes operative in a watershed into a single flux of solute mass measured in streamflow at the watershed outlet. However, it is important that we understand how weathering processes in different hydrological zones of a watershed (i.e., surface, unsaturated, and saturated zones) contribute to the total geochemical flux from the watershed. This capability will improve understanding of how geochemical fluxes from these different zones may change in response to climate change. Here, the geochemical flux from weathering processes occurring solely in the saturated zone is investigated. This task, however, remains exceedingly difficult due to the sparsity of subsurface sampling points, especially in large, remote, and/or undeveloped watersheds. In such cases, springflow is often assumed to be a proxy for groundwater (defined as water residing in fully saturated geologic formations). However, springflow generation may integrate different sources of water including, but not limited to, groundwater. The authors’ hypothesis is that long-term estimates of geochemical fluxes from groundwater using springflow proxies will be too large due to the integrative nature of springflow generation. Two conceptual models of springflow generation are tested using endmember mixing analyses (EMMA) on observations of spring chemistries and stable isotopic compositions in a large alpine watershed in the San Juan Mountains of southwestern Colorado. In the “total springflow” conceptual model, springflow is assumed to be 100% groundwater. In the “fractional springflow” conceptual model, springflow is assumed to be an integration of different sources of water (e.g., groundwater, unsaturated flow, preferential flow in the soil, etc.) and groundwater is only a fractional component. The results indicate that groundwater contributions in springflow range from 2% to 100

Environmental-geochemical characteristics of Cu in the soil and water in copper-rich deposit area of southeastern Hubei Province, along the middle Yangtze River, Central China

International Nuclear Information System (INIS)

Zhang Ling; Wang Lu; Yin Kedong; Lv Ying; Zhang Derong

2009-01-01

In this study, the natural Cu background concentration and Cu natural and anthropogenic contamination in soil, water and crop were investigated systematically in Huangshi area. The results show that regional geology is the dominant factor controlling the natural Cu background concentration in soil and water, and that pH is important to control the vertical distribution of Cu in soil under the same geographical and climatic conditions. The mineralization of rock bodies causes the natural Cu increase in soil and water, whereas, a large number of mining-smelting plants and chemical works are the main sources of Cu anthropogenic contamination. Cu in naturally and anthropogenically polluted soil displays differences in total and available contents, vertical distribution patterns and physico-chemical properties, the same happens in water. - Consider the rock-soil-water-crop as a system to study the geochemical activities and environmental pollution of copper.

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.

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

Associations between soil variables and vegetation structure and composition of Caribbean dry forests

Science.gov (United States)

Elvia M. Melendez-Ackerman; Julissa Rojas-Sandoval; Danny S. Fernandez; Grizelle Gonzalez; Hana Lopez; Jose Sustache; Mariely Morales; Miguel Garcia-Bermudez; Susan Aragon

2016-01-01

Soil–vegetation associations have been understudied in tropical dry forests when compared to the amount of extant research on this issue in tropical wet forests. Recent studies assert that vegetation in tropical dry forests is highly heterogeneous and that soil variability may be a contributing factor. In this study, we evaluated the relationship between soil variables...

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.

Temporal Changes in the Spatial Variability of Soil Nutrients

Energy Technology Data Exchange (ETDEWEB)

Hoskinson, Reed Louis; Hess, John Richard; Alessi, Randolph Samuel

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.

Geochemical Constraints for Mercury's PCA-Derived Geochemical Terranes

Science.gov (United States)

Stockstill-Cahill, K. R.; Peplowski, P. N.

2018-05-01

PCA-derived geochemical terranes provide a robust, analytical means of defining these terranes using strictly geochemical inputs. Using the end members derived in this way, we are able to assess the geochemical implications for Mercury.

Variability of Measured Runoff and Soil Loss from Field Plots

Directory of Open Access Journals (Sweden)

F. Asadzadeh

2016-02-01

Full Text Available Introduction: Field plots are widely used in studies related to the measurements of soil loss and modeling of erosion processes. Research efforts are needed to investigate factors affecting the data quality of plots. Spatial scale or size of plots is one of these factors which directly affects measuring runoff and soil loss by means of field plots. The effect of plot size on measured runoff or soil loss from natural plots is known as plot scale effect. On the other hand, variability of runoff and sediment yield from replicated filed plots is a main source of uncertainty in measurement of erosion from plots which should be considered in plot data interpretation processes. Therefore, there is a demand for knowledge of soil erosion processes occurring in plots of different sizes and of factors that determine natural variability, as a basis for obtaining soil loss data of good quality. This study was carried out to investigate the combined effects of these two factors by measurement of runoff and soil loss from replicated plots with different sizes. Materials and Methods: In order to evaluate the variability of runoff and soil loss data seven plots, differing in width and length, were constructed in a uniform slope of 9% at three replicates at Koohin Research Station in Qazvin province. The plots were ploughed up to down slope in September 2011. Each plot was isolated using soil beds with a height of 30 cm, to direct generated surface runoff to the lower part of the plots. Runoff collecting systems composed of gutters, pipes and tankswere installed at the end of each plot. During the two-year study period of 2011-2012, plots were maintained in bare conditions and runoff and soil loss were measured for each single event. Precipitation amounts and characteristics were directly measured by an automatic recording tipping-bucket rain gauge located about 200 m from the experimental plots. The entire runoff volume including eroded sediment was measured on

Spatial variability of atrazine dissipation in an allophanic soil.

Science.gov (United States)

Müller, Karin; Smith, Roger E; James, Trevor K; Holland, Patrick T; Rahman, Anis

2003-08-01

The small-scale variability (0.5 m) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) concentrations and soil water contents in a volcanic silt loam soil (Haplic Andosol, FAO system) was studied in an area of 0.1 ha. Descriptive and spatial statistics were used to analyse the data. On average we recovered 102% of the applied atrazine 2 h after the herbicide application (CV = 35%). An increase in the CV of the concentrations with depth could be ascribed to a combination of extrinsic and intrinsic factors. Both variables, atrazine concentrations and soil water content, showed a high horizontal variability. The semivariograms of the atrazine concentrations exhibited the pure nugget effect, no pattern could be determined along the 15.5-m long transects on any of the seven sampling days over a 55-day period. Soil water content had a weak spatial autocorrelation with a range of 6-10 m. The dissipation of atrazine analysed using a high vertical sampling resolution of 0.02 m to 0.2 m showed that 70% of the applied atrazine persisted in the upper 0.02-m layer of the soil for 12 days. After 55 days and 410 mm of rainfall the centre of the pesticide mass was still at a soil depth of 0.021 m. The special characteristics of the soil (high organic carbon content, allophanic clay) had a strong influence on atrazine sorption and mobility. The mass recovery after 55 days was low. The laboratory degradation rate for atrazine, determined in a complementary incubation study and corrected for the actual field temperature using the Arrhenius equation, only accounted for about 35% of the losses that occurred in the field. Results suggest field degradation rates to be more changeable in time and much faster than under controlled conditions. Preferential flow is discussed as a component of the field transport process.

Geochemical Processes During Managed Aquifer Recharge With Desalinated Seawater

Science.gov (United States)

Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

2018-02-01

We study geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW). The DSW, post-treated at the desalination plant by calcite dissolution (remineralization) to meet the Israeli water quality standards, is recharged into the Israeli Coastal Aquifer through an infiltration pond. Water quality monitoring during two MAR events using suction cups and wells inside the pond indicates that cation exchange is the dominant subsurface reaction, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the shallow groundwater composition is similar to the recharged DSW, except for enrichment of Mg2+, Na+, Ca2+, and HCO3-. A calibrated variably-saturated reactive transport model is used to predict the geochemical evolution during 50 years of MAR for two water quality scenarios: (i) post-treated DSW (current practice) and (ii) soft DSW (lacking the remineralization post-treatment process). The latter scenario was aimed to test soil-aquifer-treatment (SAT) as an alternative post-treatment technique. Both scenarios provide an enrichment of ˜2.5 mg L-1 in Mg2+ due to cation exchange, compared to practically zero Mg2+ currently found in the Israeli DSW. Simulations of the alternative SAT scenario provide Ca2+ and HCO3- remineralization due to calcite dissolution at levels that meet the Israeli standard for DSW. The simulated calcite content reduction in the sediments below the infiltration pond after 50 years of MAR was low (<1%). Our findings suggest that remineralization using SAT for DSW is a potentially sustainable practice at MAR sites overlying calcareous sandy aquifers.

Geochemical mapping study of Panjang island

International Nuclear Information System (INIS)

Sutisna; Sumardjo

2010-01-01

Impact of industrial and regional development are not only related to an improvement of socio-economic, but also to an environmental conservation and sustainable. This impact could be observed on a change of geochemical mapping before and after an operational of the industry. In the relation with a regional development and resources utilization, the geochemical mapping have been done in the aim to know a resources and an elemental distribution at Panjang island. In this research, ko-Instrumental Neutron Activation Analysis (k_0-INAA) have been applied in an elemental quantification on the geochemical mapping. Pencuplikan of geochemical sample have been carried out by using a grid systematic method with a sample density of about 10 sample per square kilometre involved 85 pencuplikan point. The geochemical sample of sediment and soil have been provided as a dry weight of 100 mesh. Internal quality control have done by using a number of Standard Reference Materials obtained from US. Geological Survey. Fifteen elements of Sc, Co, In, Rb, Mo, Ba, Ce, Nd, Eu, La, Yb, Th, U, lr and Hf contained in standard materials have been evaluated. The analysis result show that a relative standard deviation less than 11 %, except for Mo (13 %) and lr (26 %). Fourteen elements of Al, Br, Ca, Co, Eu, Fe, La, U, Na, Ce, Mn, As, Sc and Th have been mapped and presented in this paper. The major elements of Ca, Al and Fe, and minor elements of Mn, U and Sc are distributed at all region. The lanthanide elements of La, Ce and Eu have vary concentration and could be found at the middle to the north of the island. (author)

Wet-dry seasonal and vertical geochemical variations in soil water and their driving forces under different land covers in southwest China karst

Science.gov (United States)

Wang, Peng; Hu, Bill X.; Wu, Chuanhao; Xu, Kai

2017-04-01

Karst aquifers supply drinking water for 25% of the world's population, and they are, however, vulnerable to climate change. Bimonthly hydrochemical data in karst soil water samples from July 2010 to July 2011 were obtained to reveal the seasonal and vertical geochemical variations in soil water under five vegetation types in Qingmuguan, a small karst catchment in southwest China. Soil water chemistry was dominated by Ca2+, HCO3-, and SO42- because of the dissolution of limestone, dolomite, and gypsum minerals in the strata. The predominant hydrochemical types in soil water were Ca2+-HCO3-, Ca2+-SO42-, and mixed Ca2+-HCO3-SO42-. Ca2+ and HCO3- concentrations ranked in the following order: shrub land > dry land > afforestation farmland > bamboo land > grassland. In warm and wet seasons, the main ion concentrations in soil water from grasslands were low. Na+, K+, Ca2+, Mg2+, HCO3-, SO42-, and Cl- concentrations in soil water from other lands were high. An opposite trend was observed in cold and dry seasons. Marked seasonal variations were observed in Ca2+, HCO3-, and NO3- in soil water from dry land. The main ion concentrations in soil water from bamboo lands decreased as soil depth increased. By contrast, the chemistry of soil water from other lands increased as soil depth increased. Their ions were accumulated in depth. A consistent high and low variation between the main ions in soil water and the contents of carbonate and CO2 was found in the soil. Hydrochemical changes in soil water were regulated by the effects of dilution and soil CO2.

Research on geochemical exploration in geotherm development

International Nuclear Information System (INIS)

Hirowatari, Kazuo; Imaizumi, Yukio; Koga, Akito; Iwanaga, Tatsuto.

1987-01-01

The decisive factor of geotherm development is to improve the exploration techniques. By effectively carrying out the selection of promising development spots and the decision of well drilling positions, the geotherm development exceeding existing energy sources becomes feasible. There have been many problems in conventional geotherm exploration such as the high cost and long work period, therefore, it was decided to advance the research on geochemical exploration techniques which are relatively simple and can be carried out with low cost. When the techniques of geochemistry are used, for example, in the case that there are hot springs or fumaroles, the temperature, origin, properties and so on of underground hot water reservoirs can be estimated from their chemical composition. The method of examining the mercury concentration in soil and soil air has been in practical use in the geothermal districts where the ground surface symptom lacks. This time, the method of investigation using radon, thoron and gamma ray as the exploration indices was newly studied. The index compositions for geochemical exploration, new exploration index compositions, the method of measurement, the basic investigation and on-the-spot investigation are reported. (Kako, I.)

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.

Amplification and dampening of soil respiration by changes in temperature variability

Science.gov (United States)

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

2011-01-01

Accelerated release of carbon from soils is one of the most important feed backs 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 vari-ability. 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 there release of carbon through soil respiration as climate regimes change. The 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.

Generalized Density-Corrected Model for Gas Diffusivity in Variably Saturated Soils

DEFF Research Database (Denmark)

Chamindu, Deepagoda; Møldrup, Per; Schjønning, Per

2011-01-01

models. The GDC model was further extended to describe two-region (bimodal) soils and could describe and predict Dp/Do well for both different soil aggregate size fractions and variably compacted volcanic ash soils. A possible use of the new GDC model is engineering applications such as the design...... of highly compacted landfill site caps....

Relating soil geochemical properties to arsenic bioaccessibility

Data.gov (United States)

U.S. Environmental Protection Agency — soil element total concentration, soil pH and arsenic bioaccessibility values. This dataset is not publicly accessible because: EPA cannot release personally...

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.

Geochemical characterization of arsenic-rich coal-combustion ashes buried under agricultural soils and the release of arsenic

International Nuclear Information System (INIS)

Veselská, Veronika; Majzlan, Juraj; Hiller, Edgar; Peťková, Katarína; Jurkovič, Ľubomír; Ďurža, Ondrej; Voleková-Lalinská, Bronislava

2013-01-01

Highlights: ► Sources, mineralogy and mobility of As in coal-combustion ashes were investigated. ► After a dam failure in 1965, the spilled ashes were buried under agricultural soils. ► Primary carriers of As within coal-combustion ashes are aluminosilicate glasses. ► The most probable secondary carriers of labile As are oxyhydroxides of Si, Al, and Fe. ► Arsenic stored in ashes is a long-term contamination source for the environment. - Abstract: A combination of geochemical and mineralogical methods was used to determine the concentrations, mobility, and sources of As in coal-combustion ashes and soils in the vicinity of a thermal power plant at Nováky, central Slovakia. Fresh lagooned ash, ashes buried under agricultural soils for 45 a, and the overlying soils, contain high concentrations of As ranging from 61 to 1535 mg/kg. There is no differences in the water extractable percentages of As between the fresh lagooned ash and buried ashes, which range from 3.80% to 6.70% of the total As. This small amount of As may perhaps reside on the surfaces of the ash particles, as postulated in the earlier literature, but no evidence was found to support this claim. Electron microprobe analyses show that the dominant primary As carriers are the aluminosilicate glasses enriched in Ca and Fe. The acid NH 4 + -oxalate extraction hints that the oxyhydroxides of Si, Al, and Fe are the most probable secondary carriers of labile As. The X-ray absorption spectroscopy (XAS) analyses show that As in the lagooned and buried ashes occurs mostly as As(V). The long-term burial of the coal-combustion ash under agricultural soil did not cause any major change of its chemical composition or As lability compared to the fresh lagooned ash

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.

Geochemical landscapes of the conterminous United States; new map presentations for 22 elements

Science.gov (United States)

Gustavsson, N.; Bolviken, B.; Smith, D.B.; Severson, R.C.

2001-01-01

Geochemical maps of the conterminous United States have been prepared for seven major elements (Al, Ca, Fe, K, Mg, Na, and Ti) and 15 trace elements (As, Ba, Cr, Cu, Hg, Li, Mn, Ni, Pb, Se, Sr, V, Y, Zn, and Zr). The maps are based on an ultra low-density geochemical survey consisting of 1,323 samples of soils and other surficial materials collected from approximately 1960-1975. The data were published by Boerngen and Shacklette (1981) and black-and-white point-symbol geochemical maps were published by Shacklette and Boerngen (1984). The data have been reprocessed using weighted-median and Bootstrap procedures for interpolation and smoothing.

GEOBASI: The geochemical Database of Tuscany Region (Italy

Directory of Open Access Journals (Sweden)

Brunella Raco

2015-03-01

Full Text Available In this study the new Regional Geochemical Database (RGDB, called GEOBASI, is presented and illustrated in the framework of a joint collaboration among the three Tuscan universities (Florence, Pisa and Siena, CNR-IGG (Institute of Geosciences and Earth Resources of Pisa, ARPAT (Regional Agency for the Environmental Protection, LAMMA (Environmental Modelling and Monitoring Laboratory for Sustainable Development Consortium and S.I.R.A. (Territorial and Environmental Informative System of Tuscany. The database has permitted the construction of a repository where the geochemical information (compositional and isotopic has been stored in a structured way so that it can be available for different groups of users (e.g. institutional, public and private companies. The information contained in the database can in fact be downloaded freely and queried to correlate geochemistry to other non compositional variables. The first phase of the project was aimed at promoting the use of the geochemical data already available from previous investigations through a powerful Web-GIS interface to implement the exploratory statistics graphical-numerical tools used to: 1 analyse the spatial variability of the investigated context, 2 highlight the geographic location of data pertaining to classes of values or single cases, 3 compare the results of different analytical methodologies applied to the determination of the same element and/or chemical species, 4 extract the geochemical data related to specific monitoring plans and/or geographical areas, and finally 5 recover information about data below the detection limit to understand their impact on the behaviour of the investigated variable. Developments of this project will be focused on the definition of rules and standardized methods in a way that external users could also interactively pursue the RGDB. Furthermore, a detailed investigation of the Scarlino-Follonica plain will permit the improvement and test of

Spatial variability of nitrogen-15 and its relation to the variability of other soil properties

International Nuclear Information System (INIS)

Selles, F.; Karamanos, R.E.; Kachanoski, R.G.

1986-01-01

The spatial variability of natural 15 N abundance of a cultivated Chernozemic soil and its native prairie counterpart were smaller than that of total N, organic C, and the C/N ratio. Further, the number of samples required to estimate the true mean of total N with a given precision at various probability levels were twofold those required to estimate the true mean of total N with a given precision at various probability levels were twofold those required to determine the mean 15 N abundance of total soil N in the surface horizons may reflect the isotopic composition of the nitrogenous substances entering the soil system or changes in the isotopic composition of soil N due to humification processes, probably induced by variations in topographic and microrelief features of the soil

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.

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

Directory of Open Access Journals (Sweden)

Yan Guo

Full Text Available 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.

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. PMID:26020969

Podoconiosis: non-infectious geochemical elephantiasis.

Science.gov (United States)

Davey, Gail; Tekola, Fasil; Newport, Melanie J

2007-12-01

This article reviews peer-reviewed publications and book chapters on the history, epidemiology, genetics, ecology, pathogenesis, pathology and management of podoconiosis (endemic non-filarial elephantiasis). Podoconiosis is a non-infectious geochemical elephantiasis caused by exposure of bare feet to irritant alkalic clay soils. It is found in at least 10 countries in tropical Africa, Central America and northwest India, where such soils coexist with high altitude, high seasonal rainfall and low income. Podoconiosis develops in men and women working barefoot on irritant soils, with signs becoming apparent in most patients by the third decade of life. Colloid-sized silicate particles appear to enter through the skin, are taken up into macrophages in the lower limb lymphatics and cause endolymphangitis and obliteration of the lymphatic lumen. Genetic studies provide evidence for high heritability of susceptibility to podoconiosis. The economic burden is significant in affected areas dependent on subsistence farming. Podoconiosis is unique in being an entirely preventable non-communicable disease. Primary prevention entails promoting use of footwear in areas of irritant soil; early stages are reversible given good foot hygiene, but late stages result in considerable economic and social difficulties, and require extended periods of elevation and occasionally nodulectomy.

Bench Scale Treatability Studies of Contaminated Soil Using Soil Washing Technique

OpenAIRE

Gupta, M. K.; Srivastava, R. K.; Singh, A. K.

2010-01-01

Soil contamination is one of the most widespread and serious environmental problems confronting both the industrialized as well as developing nations like India. Different contaminants have different physicochemical properties, which influence the geochemical reactions induced in the soils and may bring about changes in their engineering and environmental behaviour. Several technologies exist for the remediation of contaminated soil and water. In the present study soil washing technique using...

Geochemical orientation for mineral exploration in the Hashemite Kingdom of Jordan

Science.gov (United States)

Overstreet, W.C.; Grimes, D.J.; Seitz, J.F.

1982-01-01

This report is a supplement to previous accounts of geochemical exploration conducted in the Hashemite Kingdom of Jordan by the Natural Resources Authority of the Royal Government of Jordan and the U.S. Geological Survey. The field work on which this report is based was sponsored by the U.S. Agency for International Development, U.S. Department of State. Procedures used in collecting various kinds of rocks, ores, slags, eluvial and alluvial sediments, heavy-mineral concentrates, and organic materials for use as geochemical sample media are summarized, as are the laboratory procedures followed for the analysis of these sample materials by semiquantitative spectrographic, atomic absorption, fluorometric, and X-ray diffraction methods. Geochemical evaluations of the possibilities for economic mineral deposits in certain areas are presented. The results of these preliminary investigations open concepts for further use in geochemical exploration in the search for metallic mineral deposits in Jordan. Perhaps the most desirable new activity would be hydrogeochemical exploration for uranium and base metals, accompanied by interpretation of such remote-sensing data as results of airborne radiometric surveys and computer-enhanced LANDSAT imagery. For more conventional approaches to geochemical exploration, however, several fundamental problems regarding proper choice of geochemical sample media for different geologic and geographic parts of the Country must be solved before effective surveys can be made. The present results also show that such common geochemical exploration techniques as the determination of the trace-element contents of soils, plant ash, and slags have direct application also toward the resolution of several archaeological problems in Jordan. These include the relation of trace-elements chemistry of local soils to the composition of botanic remains, the trace-elements composition of slags to the technological development of the extractive metallurgy of

Application of nanoparticle of rock phosphate and biofertilizer in increasing some soil chemical characteristics of variable charge soil

Science.gov (United States)

Devnita, Rina; Joy, Benny; Arifin, Mahfud; Hudaya, Ridha; Oktaviani, Nurul

2018-02-01

Soils in Indonesia are dominated by variable charge soils where the technology like fertilization did not give the same result as the soils with permanent charge. The objectives of this research is to increase some chemical characteristic of variable charge soils by using the high negative charge ameliorations like rock phosphate in nanoparticle combined with biofertilizer. The research used a complete randomized experimental design in factorial with two factors. The first factor was nanoparticle of rock phosphate consists of four doses on soil weight percentage (0%, 2.5%, 5.0% and 7.5%). The second factor was biofertilizer consisted of two doses (without biofertilizer and 1 g.kg-1 soil biofertilizer). The combination treatments replicated three times. Variable charge soil used was Andisol. Andisol and the treatments were incubated for 4 months. Soil samples were taken after one and four months during incubation period to be analyzed for P-retention, available P and potential P. The result showed that all combinations of rock phosphate and biofertilizer decreased the P-retention to 75-77% after one month. Independently, application of 7.5% of rock phosphate decreased P-retention to 87.22% after four months, increased available P (245.37 and 19.12 mg.kg-1) and potential P (1354.78 and 3000.99 mg/100) after one and four months. Independently, biofertilizer increased the P-retention to 91.66% after four months, decreased available P to 121.55 mg.kg-1 after one month but increased to 12.55 mg.kg-1 after four months, decreased potential P to 635.30 after one month but increased to 1810.40 mg.100 g-1 after four months.

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.

Mapping The Temporal and Spatial Variability of Soil Moisture Content Using Proximal Soil Sensing

Science.gov (United States)

Virgawati, S.; Mawardi, M.; Sutiarso, L.; Shibusawa, S.; Segah, H.; Kodaira, M.

2018-05-01

In studies related to soil optical properties, it has been proven that visual and NIR soil spectral response can predict soil moisture content (SMC) using proper data analysis techniques. SMC is one of the most important soil properties influencing most physical, chemical, and biological soil processes. The problem is how to provide reliable, fast and inexpensive information of SMC in the subsurface from numerous soil samples and repeated measurement. The use of spectroscopy technology has emerged as a rapid and low-cost tool for extensive investigation of soil properties. The objective of this research was to develop calibration models based on laboratory Vis-NIR spectroscopy to estimate the SMC at four different growth stages of the soybean crop in Yogyakarta Province. An ASD Field-spectrophotoradiometer was used to measure the reflectance of soil samples. The partial least square regression (PLSR) was performed to establish the relationship between the SMC with Vis-NIR soil reflectance spectra. The selected calibration model was used to predict the new samples of SMC. The temporal and spatial variability of SMC was performed in digital maps. The results revealed that the calibration model was excellent for SMC prediction. Vis-NIR spectroscopy was a reliable tool for the prediction of SMC.

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...

Genetic and geochemical signatures to prevent frauds and counterfeit of high-quality asparagus and pistachio.

Science.gov (United States)

Zannella, Carmela; Carucci, Francesca; Aversano, Riccardo; Prohaska, Thomas; Vingiani, Simona; Carputo, Domenico; Adamo, Paola

2017-12-15

A fingerprinting strategy based on genetic (simple sequence repeat) and geochemical (multielement and 87 Sr/ 86 Sr ratio) analysis was tested to prove the geographical origin of high-quality Italian products "White Asparagus from Bassano del Grappa" and "Green Pistachio from Bronte". Genetic analysis generated many polymorphic alleles and different specific amplified fragments in both agriproducts. In addition, a core set of markers was defined. According to variability within production soils and products, potential candidate elements linking asparagus (Zn, P, Cr, Mg, B, K) and pistachio (Mn, P, Cr, Mg, Ti, B, K, Sc, S) to the production areas were identified. The Sr isotopic signature was an excellent marker when Italian asparagus was compared with literature data for Hungarian and Peruvian asparagus. This work reinforces the use of Sr isotope composition in the soil bioavailable fraction, as assessed by 1mol/L NH 4 NO 3 , to distinguish white asparagus and pistachio originating from different geographical areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Variability in urban soils influences the health and growth of native tree seedlings

Science.gov (United States)

Clara C. Pregitzer; Nancy F. Sonti; Richard A. Hallett

2016-01-01

Reforesting degraded urban landscapes is important due to the many benefits urban forests provide. Urban soils are highly variable, yet little is known about how this variability in urban soils influences tree seedling performance and survival. We conducted a greenhouse study to assess health, growth, and survival of four native tree species growing in native glacial...

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.

Assessment of soil variability of South moravian region based on the satellite imagery

Czech Academy of Sciences Publication Activity Database

Novák, J.; Lukas, V.; Rodriguez Moreno, Fernando; Křen, J.

2018-01-01

Roč. 66, č. 1 (2018), s. 119-129 ISSN 1211-8516 Institutional support: RVO:86652079 Keywords : Coefficient of variation * lpis * ndvi * pca * RapidEye * Remote sensing * sentinel 2 * Soil variability Subject RIV: DF - Soil Science OBOR OECD: Soil science

Potential Phosphorus Mobilisation in Peat Soils

DEFF Research Database (Denmark)

Forsmann, Ditte M.; Kjærgaard, Charlotte

2012-01-01

Re-establishment of wetlands on peat soils containing phosphorus bound to iron(III)-oxides can lead to an undesirable phosphorus loss to the aquatic environment due to the reductive dissolution of iron(III)-oxides. Thus it is important to be able to assess the potential phosphorus mobilisation from...... peat soils before a re-establishment takes place. The potential phosphorus mobilisation from a peat soil depends not only on the geochemical characteristics but also on the redox conditions, the hydrological regime in the area as well as the hydro-physical properties of the soil. The hypothesis...... for this study is (i) the release of phosphorus in peat is controlled by the geochemistry; (ii) the mobilisation of phosphorus is controlled by both geochemistry and hydro-physics of the soil. For this study, 10 Danish riparian lowland areas with peat soil were selected based on their geochemical characteristics...

Analysis of the spatial variability of crop yield and soil properties in small agricultural plots

Directory of Open Access Journals (Sweden)

Vieira Sidney Rosa

2003-01-01

Full Text Available The objective of this study was to assess spatial variability of soil properties and crop yield under no tillage as a function of time, in two soil/climate conditions in São Paulo State, Brazil. The two sites measured approximately one hectare each and were cultivated with crop sequences which included corn, soybean, cotton, oats, black oats, wheat, rye, rice and green manure. Soil fertility, soil physical properties and crop yield were measured in a 10-m grid. The soils were a Dusky Red Latossol (Oxisol and a Red Yellow Latossol (Ultisol. Soil sampling was performed in each field every two years after harvesting of the summer crop. Crop yield was measured at the end of each crop cycle, in 2 x 2.5 m sub plots. Data were analysed using semivariogram analysis and kriging interpolation for contour map generation. Yield maps were constructed in order to visually compare the variability of yields, the variability of the yield components and related soil properties. The results show that the factors affecting the variability of crop yield varies from one crop to another. The changes in yield from one year to another suggest that the causes of variability may change with time. The changes with time for the cross semivariogram between phosphorus in leaves and soybean yield is another evidence of this result.

Controls of Soil Spatial Variability in a Dry Tropical Forest.

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Sandeep Pulla

Full Text Available We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2 soil spatial variability in a seasonally dry tropical forest (SDTF in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10 cm, rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH, and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3(--N nor NH4(+-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief.

Advanced cost-effective surface geochemical techniques for oil/gas/uranium exploration, environmental assessments and pipeline monitoring - a template for India

International Nuclear Information System (INIS)

Lafleur, Paul; Chanrasekharan, G.Y.V.N.; Rajender Rao, S.

2011-01-01

Advanced geochemical soil gas methods have been successfully developed for the exploration of oil/gas/uranium and for environmental assessments. Application of these cost-effective technologies in India can substantially reduce exploration risk while accelerating the development of oil/gas/uranium onshore resources. A reliable and effective monitoring system using geochemical soil gas surveys ensures that CO 2 Enhanced Oil Recovery operations as well as CO 2 sequestration projects are safe and acceptable for the disposal of CO 2 , Soil gas surveys along with other technologies can also be applied for monitoring of oil/gas pipelines for leakage, especially those that are old or pass through populated regions

The potential of mid- and near-infrared diffuse reflectance spectroscopy for determining major- and trace-element concentrations in soils from a geochemical survey of North America

Science.gov (United States)

Reeves, J. B.; Smith, D.B.

2009-01-01

In 2004, soils were collected at 220 sites along two transects across the USA and Canada as a pilot study for a planned soil geochemical survey of North America (North American Soil Geochemical Landscapes Project). The objective of the current study was to examine the potential of diffuse reflectance (DR) Fourier Transform (FT) mid-infrared (mid-IR) and near-infrared (NIRS) spectroscopy to reduce the need for conventional analysis for the determination of major and trace elements in such continental-scale surveys. Soil samples (n = 720) were collected from two transects (east-west across the USA, and north-south from Manitoba, Canada to El Paso, Texas (USA), n = 453 and 267, respectively). The samples came from 19 USA states and the province of Manitoba in Canada. They represented 31 types of land use (e.g., national forest, rangeland, etc.), and 123 different land covers (e.g., soybeans, oak forest, etc.). The samples represented a combination of depth-based sampling (0-5 cm) and horizon-based sampling (O, A and C horizons) with 123 different depths identified. The set was very diverse with few samples similar in land use, land cover, etc. All samples were analyzed by conventional means for the near-total concentration of 49 analytes (Ctotal, Ccarbonate and Corganic, and 46 major and trace elements). Spectra were obtained using dried, ground samples using a Digilab FTS-7000 FT spectrometer in the mid- (4000-400 cm-1) and near-infrared (10,000-4000 cm-1) at 4 cm-1 resolution (64 co-added scans per spectrum) using a Pike AutoDIFF DR autosampler. Partial least squares calibrations were develop using: (1) all samples as a calibration set; (2) samples evenly divided into calibration and validation sets based on spectral diversity; and (3) samples divided to have matching analyte concentrations in calibration and validation sets. In general, results supported the conclusion that neither mid-IR nor NIRS would be particularly useful in reducing the need for conventional

Effects of Recent Regional Soil Moisture Variability on Global Net Ecosystem CO2 Exchange

Science.gov (United States)

Jones, L. A.; Madani, N.; Kimball, J. S.; Reichle, R. H.; Colliander, A.

2017-12-01

Soil moisture exerts a major regional control on the inter-annual variability of the global land sink for atmospheric CO2. In semi-arid regions, annual biomass production is closely coupled to variability in soil moisture availability, while in cold-season-affected regions, summer drought offsets the effects of advancing spring phenology. Availability of satellite solar-induced fluorescence (SIF) observations and improvements in atmospheric inversions has led to unprecedented ability to monitor atmospheric sink strength. However, discrepancies still exist between such top-down estimates as atmospheric inversion and bottom-up process and satellite driven models, indicating that relative strength, mechanisms, and interaction of driving factors remain poorly understood. We use soil moisture fields informed by Soil Moisture Active Passive Mission (SMAP) observations to compare recent (2015-2017) and historic (2000-2014) variability in net ecosystem land-atmosphere CO2 exchange (NEE). The operational SMAP Level 4 Carbon (L4C) product relates ground-based flux tower measurements to other bottom-up and global top-down estimates to underlying soil moisture and other driving conditions using data-assimilation-based SMAP Level 4 Soil Moisture (L4SM). Droughts in coastal Brazil, South Africa, Eastern Africa, and an anomalous wet period in Eastern Australia were observed by L4C. A seasonal seesaw pattern of below-normal sink strength at high latitudes relative to slightly above-normal sink strength for mid-latitudes was also observed. Whereas SMAP-based soil moisture is relatively informative for short-term temporal variability, soil moisture biases that vary in space and with season constrain the ability of the L4C estimates to accurately resolve NEE. Such biases might be caused by irrigation and plant-accessible ground-water. Nevertheless, SMAP L4C daily NEE estimates connect top-down estimates to variability of effective driving factors for accurate estimates of regional

Nitrate and dissolved organic carbon mobilization in response to soil freezing variability

Science.gov (United States)

Colin B. Fuss; Charles T. Driscoll; Peter M. Groffman; John L. Campbell; Lynn M. Christenson; Timothy J. Fahey; Melany C. Fisk; Myron J. Mitchell; Pamela H. Templer; Jorge Durán; Jennifer L. Morse

2016-01-01

Reduced snowpack and associated increases in soil freezing severity resulting from winter climate change have the potential to disrupt carbon (C) and nitrogen (N) cycling in soils. We used a natural winter climate gradient based on elevation and aspect in a northern hardwood forest to examine the effects of variability in soil freezing depth, duration, and frequency on...

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

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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

Exploring innovative techniques for identifying geochemical elements as fingerprints of sediment sources in an agricultural catchment of Argentina affected by soil erosion.

Science.gov (United States)

Torres Astorga, Romina; de Los Santos Villalobos, Sergio; Velasco, Hugo; Domínguez-Quintero, Olgioly; Pereira Cardoso, Renan; Meigikos Dos Anjos, Roberto; Diawara, Yacouba; Dercon, Gerd; Mabit, Lionel

2018-05-15

Identification of hot spots of land degradation is strongly related with the selection of soil tracers for sediment pathways. This research proposes the complementary and integrated application of two analytical techniques to select the most suitable fingerprint tracers for identifying the main sources of sediments in an agricultural catchment located in Central Argentina with erosive loess soils. Diffuse reflectance Fourier transformed in the mid-infrared range (DRIFT-MIR) spectroscopy and energy-dispersive X-ray fluorescence (EDXRF) were used for a suitable fingerprint selection. For using DRIFT-MIR spectroscopy as fingerprinting technique, calibration through quantitative parameters is needed to link and correlate DRIFT-MIR spectra with soil tracers. EDXRF was used in this context for determining the concentrations of geochemical elements in soil samples. The selected tracers were confirmed using two artificial mixtures composed of known proportions of soil collected in different sites with distinctive soil uses. These fingerprint elements were used as parameters to build a predictive model with the whole set of DRIFT-MIR spectra. Fingerprint elements such as phosphorus, iron, calcium, barium, and titanium were identified for obtaining a suitable reconstruction of the source proportions in the artificial mixtures. Mid-infrared spectra produced successful prediction models (R 2  = 0.91) for Fe content and moderate useful prediction (R 2  = 0.72) for Ti content. For Ca, P, and Ba, the R 2 were 0.44, 0.58, and 0.59 respectively.

Spatial variability of soil erosion and soil quality on hillslopes in the Chinese loess plateau

International Nuclear Information System (INIS)

Li, Y.; Lindstrom, M.J.; Zhang, J.; Yang, J.

2000-01-01

Soil erosion rates and soil quality indicators were measured along two hillslope transects in the Loess Plateau near Yan'an, China. The objectives were to: (a) quantify spatial patterns and controlling processes of soil redistribution due to water and tillage erosion, and (b) correlate soil quality parameters with soil redistribution along the hillslope transects for different land use management systems. Water erosion data were derived from 137 Cs measurements and tillage erosion from the simulation of a Mass Balance Model along the hillslope transects. Soil quality measurements, i.e. soil organic matter, bulk density and available nutrients were made at the same sampling locations as the 137 Cs measurements. Results were compared at the individual site locations and along the hillslope transect through statistical and applied time series analysis. The results showed that soil loss due to water erosion and soil deposition from tillage are the dominant soil redistribution processes in range of 23-40 m, and soil deposition by water erosion and soil loss by tillage are dominant processes occurring in range of more than 80 m within the cultivated landscape. However, land use change associated with vegetation cover can significantly change both the magnitudes and scale of these spatial patterns within the hillslope landscapes. There is a strong interaction between the spatial patterns of soil erosion processes and soil quality. It was concluded that soil loss by water erosion and deposition by tillage are the main cause for the occurrence of significant scale dependency of spatial variability of soil quality along hillslope transects. (author)

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...

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).

Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.

Science.gov (United States)

Zampella, Mariavittoria; Adamo, Paola

2010-01-01

A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability.

Adjustment of geochemical background by robust multivariate statistics

Science.gov (United States)

Zhou, D.

1985-01-01

Conventional analyses of exploration geochemical data assume that the background is a constant or slowly changing value, equivalent to a plane or a smoothly curved surface. However, it is better to regard the geochemical background as a rugged surface, varying with changes in geology and environment. This rugged surface can be estimated from observed geological, geochemical and environmental properties by using multivariate statistics. A method of background adjustment was developed and applied to groundwater and stream sediment reconnaissance data collected from the Hot Springs Quadrangle, South Dakota, as part of the National Uranium Resource Evaluation (NURE) program. Source-rock lithology appears to be a dominant factor controlling the chemical composition of groundwater or stream sediments. The most efficacious adjustment procedure is to regress uranium concentration on selected geochemical and environmental variables for each lithologic unit, and then to delineate anomalies by a common threshold set as a multiple of the standard deviation of the combined residuals. Robust versions of regression and RQ-mode principal components analysis techniques were used rather than ordinary techniques to guard against distortion caused by outliers Anomalies delineated by this background adjustment procedure correspond with uranium prospects much better than do anomalies delineated by conventional procedures. The procedure should be applicable to geochemical exploration at different scales for other metals. ?? 1985.

Geochemical and biogeochemical investigations in national parks [Badania geochemiczne i biogeochemiczne w parkach narodowych

Science.gov (United States)

Migaszewski, Z.M.; Lamothe, P.J.; Crock, J.G.

1998-01-01

National parks hold a key position among nature protection areas including a diversity of resources - natural, cultural, recreational and scenic. These "inviolable sanctuaries" are simultaneosuly ecologic knots and pristine nature refuges due to the presence of a number of unique plant and animal species. These species make up a natural gene bank. Classically, the level of biologic degradation in national parks is determined on the basis of qualitative and quantitative studies of plant bioindicators. Their scope encompasses phytosociologic survey the purpose of which is to identify floral assemblages with a detailed list of species to record future changes in their number. The best biomonitors of air quality are epiphytic lichens, ground mosses and conifers. Geochemical and biogeochemical investigations are widely performed in the U.S.A. to evaluate the degree of pollution in the nature protection areas including national parks (Gough et al., 1988a, b; Crock et al., 1992a, 1993; Jackson et al., 1995). Variability of element concentrations in soils and plants is assessed by using unbalanced, nested analysis-of-variance (ANOVA). It enables obtaining important statistical information with a minimum number of samples. In some cases a combined grid and barbell sampling design is applied (Jackson et al., 1995). In specific mountainous parks a method of 2-3 transects parallel to the extent of range (crest) is recommended. To determine the impact of a single pollution source on a given park, traverse sampling beginning near the emitter is used (Crock et al., 1992, 1993). The obtained results are a "snapshot" of chemical composition of soils and plant bioindicators that can be a reference for any future changes in the concentration level of chemical elements and organics. In addition, baseline element and organics composition of the media mentioned above can be compared with that obtained for geochemical atlases of polluted urban and industrial areas. Geochemical and

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.

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

Geochemical Cycling of Iodine Species in Soils

International Nuclear Information System (INIS)

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

2007-01-01

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 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

Geochemical patterns and microbial contribution to iron plaque formation in the rice plant rhizosphere

Science.gov (United States)

Maisch, Markus; Murata, Chihiro; Unger, Julia; Kappler, Andreas; Schmidt, Caroline

2015-04-01

Rice is the major food source for more than half of the world population and 80 percent of the worldwide rice cultivation is performed on water logged paddy soils. The establishment of reducing conditions in the soil and across the soil-water interface not only stimulates the microbial production and release of the greenhouse gas methane. These settings also create optimal conditions for microbial iron(III) reduction and therefore saturate the system with reduced ferrous iron. Through the reduction and dissolution of ferric minerals that are characterized by their high surface activity, sorbed nutrients and contaminants (e.g. arsenic) will be mobilized and are thus available for uptake by plants. Rice plants have evolved a strategy to release oxygen from their roots in order to prevent iron toxification in highly ferrous environments. The release of oxygen to the reduced paddy soil causes ferric iron plaque formation on the rice roots and finally increases the sorption capacity for toxic metals. To this date the geochemical and microbiological processes that control the formation of iron plaque are not deciphered. It has been hypothesized that iron(II)-oxidizing bacteria play a potential role in the iron(III) mineral formation along the roots. However, not much is known about the actual processes, mineral products, and geochemical gradients that establish within the rhizosphere. In the present study we have developed a growth set-up that allows the co-cultivation of rice plants and iron(II)-oxidizing bacteria, as well as the visual observation and in situ measurement of geochemical parameters. Oxygen and dissolved iron(II) gradients have been measured using microelectrodes and show geochemical hot spots that offer optimal growth conditions for microaerophilic iron(II) oxidizers. First mineral identification attempts of iron plaque have been performed using Mössbauer spectroscopy and microscopy. The obtained results on mineraology and crystallinity have been

Geochemical approach values to the base line (Cu, Cr, Pb, Zn and P) for environmental studies in Montevideo coastal zone

International Nuclear Information System (INIS)

Brugnoli, E.; Burone, L.; Hutton, M.; Tuduri, A.; Bueno, C.; Muniz, P.; Venturini, N.; Garcia-Rodriguez, F.

2012-01-01

The geochemical base line values (background) represent the natural chemical concentrations (heavy metals) in sediments and soils. These are used in archaeological surveys to identify anomalies, and environmental studies of contaminated areas. In Montevideo coastal zone are explored the base line values for geochemical application and enrichment index

Geochemical variability of heavy metals in soil after land use conversions in Northeast China and its environmental applications.

Science.gov (United States)

Jiao, Wei; Ouyang, Wei; Hao, Fanghua; Liu, Bing; Wang, Fangli

2014-04-01

The long-term agricultural reclamation since the 1950s has resulted in significant land use change from natural landscape to cultivated land in the Sanjiang Plain of Northeast China, which has had important consequences for many soil physical, chemical and biological processes. To understand the impact of land use conversions on heavy metal geochemistry, soil samples were collected from natural wetland, natural forestland, paddy land and dry farmland in a case study area and analyzed for total concentrations and chemical fractions of six heavy metals. Results showed that the natural wetland reclamation for the paddy land has caused obvious losses of Cd, Cu and Zn from the soils. In addition, a significant decrease in the Zn concentration was found after the land conversion from natural forestland to dry farmland. Because all the analyzed heavy metals predominated in the stable residual fraction regardless of the land use type, the response of metal mobility to the land use conversions was generally weak. Consequently, soil erosion was identified as the major factor that enhances heavy metal losses in the cultivated lands, especially in the paddy land. The close link between heavy metal loss and the reduction of clay and organic matter contents after land reclamation suggested that the diffuse heavy metal pollution occurred mainly in small erosion events. Considering the continuous paddy land expansion, special attention should be paid to the bioaccumulation of Pb in the paddy rice. Overall, these findings can help to improve the sustainability and safety of intensive agricultural activities in Northeast China as well as other similar areas.

Temporal variability of structure and hydraulic properties of topsoil of three soil types

Czech Academy of Sciences Publication Activity Database

Jirků, V.; Kodešová, R.; Nikodem, A.; Mühlhanselová, M.; Žigová, Anna

204/205, August (2013), s. 43-58 ISSN 0016-7061 R&D Projects: GA ČR GA526/08/0434 Institutional support: RVO:67985831 Keywords : aggragate stability * soil -water retention curve * hydraulic conductivity * soil micromorphology * seasonal and annual variability Subject RIV: DF - Soil Science Impact factor: 2.509, year: 2013

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.

Controls on the spatial variability of key soil properties: comparing field data with a mechanistic soilscape evolution model

Science.gov (United States)

Vanwalleghem, T.; Román, A.; Giraldez, J. V.

2016-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of a geostatistical versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

Chemical elements in the environment: multi-element geochemical datasets from continental to national scale surveys on four continents

Science.gov (United States)

Caritat, Patrice de; Reimann, Clemens; Smith, David; Wang, Xueqiu

2017-01-01

During the last 10-20 years, Geological Surveys around the world have undertaken a major effort towards delivering fully harmonized and tightly quality-controlled low-density multi-element soil geochemical maps and datasets of vast regions including up to whole continents. Concentrations of between 45 and 60 elements commonly have been determined in a variety of different regolith types (e.g., sediment, soil). The multi-element datasets are published as complete geochemical atlases and made available to the general public. Several other geochemical datasets covering smaller areas but generally at a higher spatial density are also available. These datasets may, however, not be found by superficial internet-based searches because the elements are not mentioned individually either in the title or in the keyword lists of the original references. This publication attempts to increase the visibility and discoverability of these fundamental background datasets covering large areas up to whole continents.

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 Ca, Fe, K, Mg, Na, S, Ti, Ag, As, 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 were used for Hg, Se, total C, and carbonate-C on this same size fraction. Only Ag, In, and Te had a large percentage of concentrations below the detection limit. Quality control (QC) of the analyses was monitored at three levels: the laboratory performing the analysis, the USGS QC officer, and the principal investigator for the study. This level of review resulted in an average of one QC sample for every 20 field samples, which proved to be minimally adequate for such a large-scale survey. Additional QC samples should be added to monitor within-batch quality to the extent that no more than 10 samples are analyzed between a QC sample. Only Cr (77%), Y (82%), and Sb (80%) fell outside the acceptable limits of accuracy (% recovery between 85 and 115%) because of likely residence in mineral phases resistant to 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

GEMAS: Geochemical distribution of iodine in European agricultural soil

Science.gov (United States)

Birke, Manfred; Reimann, Clemens; Ladenberger, Anna; Négrel, Philippe; Rauch, Uwe; Demetriades, Alecos; Korte, Frank; Dinelli, Enrico

2017-04-01

Iodine concentrations are reported for the climate, soil formation processes, and geology (parent material, in some cases mineralisation). The distribution of anomalous I concentrations is likely a reflection of I input from atmospheric and marine sources, as well as the accumulation of I as a result of sorption on organic material. Across Europe, high I areas correlate well with soil with elevated TOC values. This is particularly evident for the western coastal areas of Ireland, UK, Norway, Galicia and France, where the organic matter content in the soil is generally high. The continuous supply of I from sea spray represents a potential source for high and elevated I concentrations. In the coastal zones of SE Spain, SE Ukraine and SW Croatia the I concentration in Ap samples is usually high. Along the eastern Adriatic coast as well as in South-East Ukraine and in the Crimea the elevated and anomalous I concentrations correspond well with the distribution of terra rossa soils developed on karst and organic-rich soils (black soil). In SE Spain the I enriched soils are most likely related to the occurrence of evaporites. The comparison of I background values (medians) based on the parent materials demonstrates a higher I content in soils over limestone and shale. Iodine-low soil areas (Iberian Peninsula) and glacial and aeolian deposits (NW Ukraine).

Soil contamination in the impact zone of mining enterprises in the Bashkir Transural region

Science.gov (United States)

Opekunova, M. G.; Somov, V. V.; Papyan, E. E.

2017-06-01

The results of long-term studies of the contents of bulk forms of metals (Cu, Zn, Fe, Ni, Pb, Mn, Co, and Cd) and their mobile compounds in soils of background and human-disturbed areas within the Krasnoural'sk-Sibai-Gai copper-zinc and Baimak-Buribai mixed copper mineralization zones in the Bashkir Transural region are discussed. It is shown that soils of the region are characterized by abnormally high natural total contents of heavy metals (HMs) typomorphic for ore mineralization: Cu, Zn, and Fe for the Sibai province and Cu, Zn, and Ni for the Baimak province. In the case of a shallow depth of the ores, the concentrations of HMs in the soils are close to or higher than the tentative permissible concentration values. The concentrations of mobile HM compounds in soils of background areas and their percentage in the total HM content strongly vary from year to year in dependence on weather conditions, position in the soil catenas, species composition of vegetation, and distance from the source of technogenic contamination. The high natural variability in the content of mobile HM compounds in soils complicates the reliable determination of the regional geochemical background and necessitates annual estimation of background parameters for the purposes of the ecological monitoring of soils. The bulk content of Cu and Zn content in soils near mining enterprises exceeds the regional geochemical background values by 2-12 times and the tentative permissible concentrations of these metals by 2-4 times. Anthropogenic contamination results in a sharp rise in the content of mobile HM compounds in soils. Their highest concentrations exceed the maximum permissible concentrations by 26 times for Cu, 18 times for Zn, and 2 times for Pb. Soil contamination in the impact zone of mining enterprises is extremely dangerous or dangerous. However, because of the high temporal variability in the migration and accumulation of HMs in the soils, the recent decline in the ore mining

Screening variability and change of soil moisture under wide-ranging climate conditions: Snow dynamics effects.

Science.gov (United States)

Verrot, Lucile; Destouni, Georgia

2015-01-01

Soil moisture influences and is influenced by water, climate, and ecosystem conditions, affecting associated ecosystem services in the landscape. This paper couples snow storage-melting dynamics with an analytical modeling approach to screening basin-scale, long-term soil moisture variability and change in a changing climate. This coupling enables assessment of both spatial differences and temporal changes across a wide range of hydro-climatic conditions. Model application is exemplified for two major Swedish hydrological basins, Norrström and Piteälven. These are located along a steep temperature gradient and have experienced different hydro-climatic changes over the time period of study, 1950-2009. Spatially, average intra-annual variability of soil moisture differs considerably between the basins due to their temperature-related differences in snow dynamics. With regard to temporal change, the long-term average state and intra-annual variability of soil moisture have not changed much, while inter-annual variability has changed considerably in response to hydro-climatic changes experienced so far in each basin.

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

International Nuclear Information System (INIS)

Bolan, Nanthi; Mahimairaja, Santiago; Kunhikrishnan, Anitha; Naidu, Ravi

2013-01-01

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

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

Modeling impacts of human footprint and soil variability on the potential distribution of invasive plant species in different biomes

Science.gov (United States)

Wan, Ji-Zhong; Wang, Chun-Jing; Yu, Fei-Hai

2017-11-01

Human footprint and soil variability may be important in shaping the spread of invasive plant species (IPS). However, until now, there is little knowledge on how human footprint and soil variability affect the potential distribution of IPS in different biomes. We used Maxent modeling to project the potential distribution of 29 IPS with wide distributions and long introduction histories in China based on various combinations of climatic correlates, soil characteristics and human footprint. Then, we evaluated the relative importance of each type of environmental variables (climate, soil and human footprint) as well as the difference in range and similarity of the potential distribution of IPS between different biomes. Human footprint and soil variables contributed to the prediction of the potential distribution of IPS, and different types of biomes had varying responses and degrees of impacts from the tested variables. Human footprint and soil variability had the highest tendency to increase the potential distribution of IPS in Montane Grasslands and Shrublands. We propose to integrate the assessment in impacts of human footprint and soil variability on the potential distribution of IPS in different biomes into the prevention and control of plant invasion.

A preliminary report of geochemical investigations in the Blackbird District

Science.gov (United States)

Canney, F.C.; Hawkes, H.E.; Richmond, G.M.; Vhay, J. S.

1953-01-01

This paper reviews an experimental geochemical prospecting survey in the Blackbird cobalt-copper mining district. The district is in east-central Idaho, about 20 miles west-southwest of Salmon. The area is one of deeply weathered nearly flat-topped upland surfaces cut by steep-walled valleys which are tributary to the canyon of Panther Creek. Most of the area has a relatively heavy vegetative cover, and outcrops are scarce except on the sides of the steeper valleys* Because of the importance of the surficial deposits and soils and the physiographic history of the region on the interpretation of the geochemical data, a separate chapter on this subject by Gerald H. Richmond follows the following brief description of the geology of the district.

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

African Journals Online (AJOL)

Spatial Variability of Soil Morphorlogical and Physico-Chemical Properties in Ladoke Akintola University of Technology Cashew Plantation, Ogbomoso. ... Colour (AP, B1 B2 and B3), structure (B2 and B3), stoniness (B1, B2 and B3), concretion (AP B1, B2 and B3) and boundary forms (B1, B2 and B3) have extremely ...

Landsat thematic mapper (TM) soil variability analysis over Webster County, Iowa

Science.gov (United States)

Thompson, D. R.; Henderson, K. E.; Pitts, D. E.

1984-01-01

Thematic mapper simulator (TMS) data acquired June 7, June 23, and July 31, 1982, and Landsat thematic mapper (TM) data acquired August 2, September 3, and October 21, 1982, over Webster County, Iowa, were examined for within-field soil effects on corn and soybean spectral signatures. It was found that patterns displayed on various computer-generated map products were in close agreement with the detailed soil survey of the area. The difference in spectral values appears to be due to a combination of subtle soil properties and crop growth patterns resulting from the different soil properties. Bands 4 (0.76-.90 micron), 5 (1.55-1.75 micron), and 7 (2.08-2.35 micron) were found to be responding to the within-field soil variability even with increasing ground cover. While these results are preliminary, they do indicate that the soil influence on the vegetation is being detected by TM and should provide improved information relating to crop and soil properties.

Spatial Variability of Physical Soil Quality Index of an Agricultural Field

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Sheikh M. Fazle Rabbi

2014-01-01

Full Text Available A field investigation was carried out to evaluate the spatial variability of physical indicators of soil quality of an agricultural field and to construct a physical soil quality index (SQIP map. Surface soil samples were collected using 10  m×10 m grid from an Inceptisol on Ganges Tidal Floodplain of Bangladesh. Five physical soil quality indicators, soil texture, bulk density, porosity, saturated hydraulic conductivity (KS, and aggregate stability (measured as mean weight diameter, MWD were determined. The spatial structures of sand, clay, and KS were moderate but the structure was strong for silt, bulk density, porosity, and MWD. Each of the physical soil quality indicators was transformed into 0 and 1 using threshold criteria which are required for crop production. The transformed indicators were the combined into SQIP. The kriged SQIP map showed that the agricultural field studied could be divided into two parts having “good physical quality” and “poor physical soil quality.”

A stochastic analysis of the influence of soil and climatic variability on the estimate of pesticide ground water polution potential

Science.gov (United States)

Jury, William A.; Gruber, Joachim

1989-12-01

Soil and climatic variability contribute in an unknown manner to the leaching of pesticides below the surface soil zone where degradation occurs at maximum levels. In this paper we couple the climatic variability model of Eagleson (1978) to the soil variability transport model of Jury (1982) to produce a probability density distribution of residual mass fraction (RMF) remaining after leaching below the surface degradation zone. Estimates of the RMF distribution are shown to be much more sensitive to soil variability than climatic variability, except when the residence time of the chemical is shorter than one year. When soil variability dominates climatic variability, the applied water distribution may be replaced by a constant average water application rate without serious error. Simulations of leaching are run with 10 pesticides in two climates and in two representative soil types with a range of soil variability. Variability in soil or climate act to produce a nonnegligible probability of survival of a small value of residual mass even for relatively immobile compounds which are predicted to degrade completely by a simple model which neglects variability. However, the simpler model may still be useful for screening pesticides for groundwater pollution potential if somewhat larger residual masses of a given compound are tolerated. Monte Carlo simulations of the RMF distribution agreed well with model predictions over a wide range of pesticide properties.

Geochemical modeling of uranium mill tailings: a case study

International Nuclear Information System (INIS)

Peterson, S.R.; Felmy, A.R.; Serne, R.J.; Gee, G.W.

1983-08-01

Liner failure was not found to be a problem when various acidic tailings solutions leached through liner materials for periods up to 3 y. On the contrary, materials that contained over 30% clay showed a decrease in permeability with time in the laboratory columns. The decreases in permeability noted above are attributed to pore plugging resulting from the precipitation of minerals and solids. This precipitation takes place due to the increase in pH of the tailings solution brought about by the buffering capacity of the soil. Geochemical modeling predicts, and x-ray characterization confirms, that precipitation of solids from solution is occurring in the acidic tailings solution/liner interactions studied. X-ray diffraction identified gypsum and alunite group minerals, such as jarosite, as having precipitated after acidic tailings solutions reacted with clay liners. The geochemical modeling and experimental work described above were used to construct an equilibrium conceptual model consisting of minerals and solid phases. This model was developed to represent a soil column. A computer program was used as a tool to solve the system of mathematical equations imposed by the conceptual chemical model. The combined conceptual model and computer program were used to predict aqueous phase compositions of effluent solutions from permeability cells packed with geologic materials and percolated with uranium mill tailings solutions. An initial conclusion drawn from these studies is that the laboratory experiments and geochemical modeling predictions were capable of simulating field observations. The same mineralogical changes and contaminant reductions observed in the laboratory studies were found at a drained evaporation pond (Lucky Mc in Wyoming) with a 10-year history of acid attack. 24 references, 5 figures 5 tables

Infiltration Variability in Agricultural Soil Aggregates Caused by Air Slaking

Science.gov (United States)

Korenkova, L.; Urik, M.

2018-04-01

This article reports on variation in infiltration rates of soil aggregates as a result of phenomenon known as air slaking. Air slaking is caused by the compression and subsequent escape of air captured inside soil aggregates during water saturation. Although it has been generally assumed that it occurs mostly when dry aggregates are rapidly wetted, the measurements used for this paper have proved that it takes place even if the wetting is gradual, not just immediate. It is a phenomenon that contributes to an infiltration variability of soils. In measuring the course of water flow through the soil, several small aggregates of five agricultural soils were exposed to distilled water at zero tension in order to characterize their hydraulic properties. Infiltration curves obtained for these aggregates demonstrate the effect of entrapped air on the increase and decrease of infiltration rates. The measurements were performed under various moisture conditions of the A-horizon aggregates using a simple device.

Spatial variability of chemical properties of soil under pasture

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Samuel Ferreira da Silva

2016-04-01

Full Text Available The objective of this study was to analyze the spatial variability of soil chemical attributes under pasture, as well as lime and fertilizer recommendations based on the interpretation of soil chemical analysis from two sampling methods: conventional and systematic depths of 0 to 10 and 10 to 20 cm. The study was conducted at IFES-campus Alegre-ES. Data analysis was performed using descriptive statistics and geostatistics. Results indicate that the spatial method enabled the identification of deficit areas and excessive liming and fertilization, which could not be defined by the conventional method.

ASSESSMENT SPATIAL VARIABILITY OF SOIL ERODIBILITY BY USING OF GEOSTATISTIC AND GIS (Case study MEHR watershed of SABZEVAR

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Ayoubi, S.A

2005-05-01

Full Text Available Soil erodibility is one of the key factors on some sediment and soil erosion models such as USLE, MUSLE, RUSLE, AUSLE (USLE modified in LS factor and MMF and represents like K factor and is function of particle distribution, organic mater, soil structure and ermeability. Traditional methods do not take spatial variability and estimate precision of variables in to consideration and amount of them are constant across the whole of soil series .This study was performed to assess spatial variability of soil erodibility and its relevant variables at MEHR watershed from Khorasan province, in northern Iran. Interested network was designed by 110 samples like nested- systematic with distance about 50, 100, 250 and 500 meter across the study area by preparing point map at GIS. Sampling points were identified in field by an Global Positioning system. Soil sampling was done at depth of 0-5cm of ground surface and permeability was studied at depth of 5-30 cm. Some soil properties such as particle distribution and organic mater were measured at laboratory. Particle size distribution was determined by Hydrometer method and Organic matter was measured by wet oxidation approach. Then spatial analysis was done. Variography analysis on soil attributes according to soil erodibility, showed that Gaussian, exponential and spherical models were the most models to predict spatial variability of soil parameters. The range of spatial dependencies was changed from 320 to 3200 m. Soil attribute maps prepared by kriging technique using models parameters. Then soil attributes were composed by Wischmeier (1978 formula in Illwis media to calculate K factor. Amount of soil erodibility changed from 0.13 to 0.91 that it's maximum and minimum was identified in east and southwest of studiedarea. Soil spatial variability pattern, is similar to silt pattern due to high effect of silt on soil rodibility, Also that is partially confirmed with geology map, indicated which soil

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

Novel geochemical techniques integrated in exploration for uranium deposits at depth

International Nuclear Information System (INIS)

Kyser, K.

2014-01-01

Mineral deposits are in fact geochemical anomalies, and as such their detection and assessment of their impact on the environment should be facilitated using geochemical techniques. Although geochemistry has been used directly in the discovery of uranium deposits and more indirectly in shaping deposit models, the novel applications of geochemistry and integration with other data can be more effective in formulating exploration and remediation strategies. Recent research on the use of geochemistry in detecting uranium deposits at depth include: (1) more effective integration of geochemical with geophysical data to refine targets, (2) revealing element distributions in and around deposits to adequately assess the total chemical environment associated with the deposit, (3) the use of element tracing using elemental concentrations and isotopic compositions in the near surface environment to detect specific components that have migrated to the surface from uranium deposits at depth, (4) understand the effects of both macro- and micro-environments on element mobility across the geosphere-biosphere interface to enhance exploration using select media for uranium at depth. Geophysical data used in exploration can identify areas of conductors where redox contrasts may host mineralization, structures that act to focus fluids during formation of the deposits and act as conduits for element migration to the surface, and contrasts in geology that are required for the deposits. However, precision of these data is greatly diminished with depth, but geochemical data from drill core or surface media can enhance target identification when integrated with geophysical data. Geochemical orientation surveys over known unconformity-related deposits at depth clearly identify mineralization 900m deep. Drill core near the deposit, clay-size fractions separated from soil horizons and vegetation over and far from the deposit record element migration from the deposit as radiogenic He, Rn and Pb

Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils

International Nuclear Information System (INIS)

Jerden, James L. Jr.

2007-01-01

A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group

The Fingerprint of Present and Past Rainfall on Soil Geochemistry

Science.gov (United States)

Amundson, R.; Owen, J.; Ewing, S.; Nishiizumi, K.; Finkel, R.; Chadwick, O.; Dietrich, W.

2007-12-01

Research conducted in many locations show that soil weathering rates vary with time and environmental conditions. Here, we assemble long-term (105 to 106 y) chronosequence studies of soil chemistry in sites varying in MAP from ~1 to ~4000 mm y-1 to examine how the rate and magnitude of chemical weathering varies with climate, particularly at the dry end of the spectrum. In humid, vegetated landscapes, soil chemical weathering generally releases an array of rock forming elements that are removed via leaching, causing a subsequent mass loss and volumetric collapse. The rate of this process is non-linear, with instantaneous weathering rates declining greatly with time. In general, the rates and magnitude (for a soil of a given age) of chemical weathering decline greatly with decreasing rainfall. At the arid/hyperarid boundary, where rainfall decreases to the point that biota are essentially absent, chemical weathering nearly ceases, retention of atmospheric solutes and dust increases, and soil chemistry becomes mainly inorganic. The rates of mass gain and volumetric expansion in extremely hyperarid regions is hypothesized to be linear, differing from the non- linearity of processes in more humid regions. While the "fingerprint" of rainfall on soil properties is greatly magnified with increasing soil age, ancient soils commonly bear the imprint of multiple climate changes. In humid regions, detecting these changes in soil chemistry is difficult, whereas an increase in aridity, and a shift from net mass loss to net mass gain, produces a unique geochemical signal, and additionally preserves the weathering signal that occurred during the earlier pluvial episode. In two ancient (Miocene) well-preserved landscapes along a modern (and ancient) rainfall gradient in the Atacama Desert, the geochemical signal of climate change is clearly evident. Paleoclimate reconstructions suggest that northern Chile was under a permanent El Nino-like condition until the late Pliocene, and

Probabilistic, sediment-geochemical parameterisation of the groundwater compartment of the Netherlands for spatially distributed, reactive transport modelling

Science.gov (United States)

Janssen, Gijs; Gunnink, Jan; van Vliet, Marielle; Goldberg, Tanya; Griffioen, Jasper

2017-04-01

Pollution of groundwater aquifers with contaminants as nitrate is a common problem. Reactive transport models are useful to predict the fate of such contaminants and to characterise the efficiency of mitigating or preventive measures. Parameterisation of a groundwater transport model on reaction capacity is a necessary step during building the model. Two Dutch, national programs are combined to establish a methodology for building a probabilistic model on reaction capacity of the groundwater compartment at the national scale: the Geological Survey program and the NHI Netherlands Hydrological Instrument program. Reaction capacity is considered as a series of geochemical characteristics that control acid/base condition, redox condition and sorption capacity. Five primary reaction capacity variables are characterised: 1. pyrite, 2. non-pyrite, reactive iron (oxides, siderite and glauconite), 3. clay fraction, 4. organic matter and 5. Ca-carbonate. Important reaction capacity variables that are determined by more than one solid compound are also deduced: 1. potential reduction capacity (PRC) by pyrite and organic matter, 2. cation-exchange capacity (CEC) by organic matter and clay content, 3. carbonate buffering upon pyrite oxidation (CPBO) by carbonate and pyrite. Statistical properties of these variables are established based on c. 16,000 sediment geochemical analyses. The first tens of meters are characterised based on 25 regions using combinations of lithological class and geological formation as strata. Because of both less data and more geochemical uniformity, the deeper subsurface is characterised in a similar way based on 3 regions. The statistical data is used as input in an algoritm that probabilistically calculates the reaction capacity per grid cell. First, the cumulative frequency distribution (cfd) functions are calculated from the statistical data for the geochemical strata. Second, all voxel cells are classified into the geochemical strata. Third, the

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

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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.

Ecological Role of Soils upon Radioactive Contamination

Science.gov (United States)

Tsvetnov, Evgeny; Shcheglov, Alexei; Tsvenova, Olga

2016-04-01

The ecological role of soils upon radioactive contamination is clearly manifested in the system of notions about ecosystems services, i.e., benefits gained by humans from ecosystems and their components, including soils (Millennium Ecosystem Assessment, 2005). For the soils, these services are considered on the basis of soil functions in the biosphere that belong to the protective ecosystem functions within the group of soil functions known under the names of "Buffer and protective biogeocenotic shield" (at the level of particular biogeocenoses) and "Protective shield of the biosphere" (at the global biospheric level) (according to Dobrovol'skii & Nikitin, 2005). With respect to radionuclides, this group includes (1) the depositing function, i.e., the accumulation and long-term sequestration of radioactive substances by the soil after atmospheric fallout; (2) the geochemical function, i.e., the regulation of horizontal and vertical fluxes of radionuclides in the system of geochemically conjugated landscapes and in the soil-groundwater and soil-plant systems; and (3) the dose-forming function that is manifested by the shielding capacity of the soil with respect to the external ionizing radiation (lowering of the dose from external radiation) and by the regulation of the migration of radionuclides in the trophic chain (lowering of the dose from internal radiation). The depositing and geochemical functions of the soils are interrelated, which is seen from quantitative estimates of the dynamics of the fluxes of radionuclides in the considered systems (soil-plant, soil-groundwater, etc.). The downward migration of radionuclides into the lower soil layers proceeds very slowly: for decades, more than 90% of the pool of radionuclides is stored in the topmost 10 cm of the soil profile. In the first 3-5 years after the fallout, the downward migration of radionuclides with infiltrating water flows decreases from several percent to decimals and hundredths of percent from the

Variability in soil-water retention properties and implications for physics-based simulation of landslide early warning criteria

Science.gov (United States)

Thomas, Matthew A.; Mirus, Benjamin B.; Collins, Brian D.; Lu, Ning; Godt, Jonathan W.

2018-01-01

Rainfall-induced shallow landsliding is a persistent hazard to human life and property. Despite the observed connection between infiltration through the unsaturated zone and shallow landslide initiation, there is considerable uncertainty in how estimates of unsaturated soil-water retention properties affect slope stability assessment. This source of uncertainty is critical to evaluating the utility of physics-based hydrologic modeling as a tool for landslide early warning. We employ a numerical model of variably saturated groundwater flow parameterized with an ensemble of texture-, laboratory-, and field-based estimates of soil-water retention properties for an extensively monitored landslide-prone site in the San Francisco Bay Area, CA, USA. Simulations of soil-water content, pore-water pressure, and the resultant factor of safety show considerable variability across and within these different parameter estimation techniques. In particular, we demonstrate that with the same permeability structure imposed across all simulations, the variability in soil-water retention properties strongly influences predictions of positive pore-water pressure coincident with widespread shallow landsliding. We also find that the ensemble of soil-water retention properties imposes an order-of-magnitude and nearly two-fold variability in seasonal and event-scale landslide susceptibility, respectively. Despite the reduced factor of safety uncertainty during wet conditions, parameters that control the dry end of the soil-water retention function markedly impact the ability of a hydrologic model to capture soil-water content dynamics observed in the field. These results suggest that variability in soil-water retention properties should be considered for objective physics-based simulation of landslide early warning criteria.

Temporal variability of selected chemical and physical propertires of topsoil of three soil types

Czech Academy of Sciences Publication Activity Database

Jirků, V.; Kodešová, R.; Nikodem, A.; Mühlhanselová, M.; Žigová, Anna

2013-01-01

Roč. 15, - (2013) ISSN 1607-7962. [EGU General Assembly /10./. 07.04.2013-12.04.2013, Vienna] R&D Projects: GA ČR GA526/08/0434 Institutional support: RVO:67985831 Keywords : soil properties * soil types * temporal variability Subject RIV: DF - Soil Science http://meetingorganizer.copernicus.org/EGU2013/EGU2013-7650-1.pdf

Urban soil geochemistry in Athens, Greece: The importance of local geology in controlling the distribution of potentially harmful trace elements.

Science.gov (United States)

Argyraki, Ariadne; Kelepertzis, Efstratios

2014-06-01

Understanding urban soil geochemistry is a challenging task because of the complicated layering of the urban landscape and the profound impact of large cities on the chemical dispersion of harmful trace elements. A systematic geochemical soil survey was performed across Greater Athens and Piraeus, Greece. Surface soil samples (0-10cm) were collected from 238 sampling sites on a regular 1×1km grid and were digested by a HNO3-HCl-HClO4-HF mixture. A combination of multivariate statistics and Geographical Information System approaches was applied for discriminating natural from anthropogenic sources using 4 major elements, 9 trace metals, and 2 metalloids. Based on these analyses the lack of heavy industry in Athens was demonstrated by the influence of geology on the local soil chemistry with this accounting for 49% of the variability in the major elements, as well as Cr, Ni, Co, and possibly As (median values of 102, 141, 16 and 24mg kg(-1) respectively). The contribution to soil chemistry of classical urban contaminants including Pb, Cu, Zn, Sn, Sb, and Cd (medians of 45, 39, 98, 3.6, 1.7 and 0.3mg kg(-1) respectively) was also observed; significant correlations were identified between concentrations and urbanization indicators, including vehicular traffic, urban land use, population density, and timing of urbanization. Analysis of soil heterogeneity and spatial variability of soil composition in the Greater Athens and Piraeus area provided a representation of the extent of anthropogenic modifications on natural element loadings. The concentrations of Ni, Cr, and As were relatively high compared to those in other cities around the world, and further investigation should characterize and evaluate their geochemical reactivity. Copyright © 2014 Elsevier B.V. All rights reserved.

Spatial variability of caesium-137 activities in soils in the Jura mountains

International Nuclear Information System (INIS)

Pimou-Heumou, G.; Lucot, E.; Crini, N.; Briot, M.; Badot, P.M.

2011-01-01

275 soil samples were taken in the catchment area of the upper part of the Doubs river located in the Jura mountains according to a sampling strategy designed to evaluate the extent of the spatial variability of 137 Cs activities and to identify its main sources. 137 Cs activities ranged between about 1000 and 12000 Bq.m -2 with an average of approximately 3600 Bq.m -2 . The spatial variability of the contamination is high: 137 Cs activity shows statistically significant links with altitude, soil organic matter and land cover, whereas the other studied parameters, i.e. soil type and topographic position, do not constitute significant sources of variation. These results are discussed in terms of evaluation of the radioactive contamination on a regional scale. They show that to be satisfactory, a sampling strategy must necessarily take into account the various types of land cover. (authors)

The effects of spatial variability of the aggressiveness of soil on system reliability of corroding underground pipelines

International Nuclear Information System (INIS)

Sahraoui, Yacine; Chateauneuf, Alaa

2016-01-01

In this paper, a probabilistic methodology is presented for assessing the time-variant reliability of corroded underground pipelines subjected to space-variant soil aggressiveness. The Karhunen-Loève expansion is used to model the spatial variability of soil as a correlated stochastic field. The pipeline is considered as a series system for which the component and system failure probabilities are computed by Monte Carlo simulations. The probabilistic model provides a realistic time and space modelling of stochastic variations, leading to appropriate estimation of the lifetime distribution. The numerical analyses allow us to investigate the impact of various parameters on the reliability of underground pipelines, such as the soil aggressiveness, the pipe design variables, the soil correlation length and the pipeline length. The results show that neglecting the effect of spatial variability leads to pessimistic estimation of the residual lifetime and can lead to condemn prematurely the structure. - Highlights: • The role of soil heterogeneity in pipeline reliability assessment has been shown. • The impact of pipe length and soil correlation length has been examined. • The effect of the uncertainties related to design variables has been observed. • Pipe thickness design for homogeneous reliability has been proposed.

An examination of the spatial variability of CO2 in the profile of managed forest soils

International Nuclear Information System (INIS)

Black, M.; Kellman, L.; Beltrami, H.

2005-01-01

Soil carbon dioxide (CO 2 ) profiles are typically used in soil-gas exchange studies. Although surface flux measuring methods may be more efficient for deriving surface soil CO 2 exchange budgets, they do not provide enough information about the generation of gas through depth. This poses a challenge in quantifying the CO 2 generated from different zones and soil carbon pools through time. The combination of subsurface concentration profiles and estimates of soil diffusivity reveal where CO 2 is being generated in the soil. This combined approach offers greater awareness into processes controlling CO 2 production in soils through depth, and clarifies how soil CO 2 exchange processes in these ecosystems can be changed by management regimes and climate change. Although information about spatial variability in subsurface concentrations within forested soils is limited, it is assumed to be high because of the high spatial variability in soil CO 2 flux estimates and the large variation in vegetation distribution and topography within sites. In this study, the soil CO 2 profile was monitored during the fall of 2004 at depths of 0, 5, 20 and 35 cm at 10 microsites of a clear-cut and an 80 year old intact mixed forest in Atlantic Canada. Microsites were about 10 meters apart and represented a range of microtopographical conditions that typically encompass extremes in soil CO 2 profile patterns. Preliminary results reveal predictable patterns in concentration profiles through depth, and increasing CO 2 concentration with depth, consistent with a large soil source of CO 2 . The significant variability in the soil carbon profile between microsites in the clear-cut and intact forest sites will be investigated to determine if distinct microsite patterns can be identified. The feasibility of using this method for providing process-based versus soil C exchange budgeting information at forested sites will also be examined

Evaluating Genetic Variability of Sorghum Mutant Lines Tolerant to Acid Soil

International Nuclear Information System (INIS)

Puspitasari, W.; Human, S.; Wirnas, D.; Trikoesoemaningtyas

2012-01-01

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 (author)

Environmental and management impacts on temporal variability of soil hydraulic properties

Science.gov (United States)

Bodner, G.; Scholl, P.; Loiskandl, W.; Kaul, H.-P.

2012-04-01

Soil hydraulic properties underlie temporal changes caused by different natural and management factors. Rainfall intensity, wet-dry cycles, freeze-thaw cycles, tillage and plant effects are potential drivers of the temporal variability. For agricultural purposes it is important to determine the possibility of targeted influence via management. In no-till systems e.g. root induced soil loosening (biopores) is essential to counteract natural soil densification by settling. The present work studies two years of temporal evolution of soil hydraulic properties in a no-till crop rotation (durum wheat-field pea) with two cover crops (mustard and rye) having different root systems (taproot vs. fibrous roots) as well as a bare soil control. Soil hydraulic properties such as near-saturated hydraulic conductivity, flow weighted pore radius, pore number and macroporosity are derived from measurements using a tension infiltrometer. The temporal dynamics are then analysed in terms of potential driving forces. Our results revealed significant temporal changes of hydraulic conductivity. When approaching saturation, spatial variability tended to dominate over the temporal evolution. Changes in near-saturated hydraulic conductivity were mainly a result of changing pore number, while the flow weighted mean pore radius showed less temporal dynamic in the no-till system. Macroporosity in the measured range of 0 to -10 cm pressure head ranged from 1.99e-4 to 8.96e-6 m3m-3. The different plant coverage revealed only minor influences on the observed system dynamics. Mustard increased slightly the flow weighted mean pore radius, being 0.090 mm in mustard compared to 0.085 mm in bare soil and 0.084 mm in rye. Still pore radius changes were of minor importance for the overall temporal dynamics. Rainfall was detected as major driving force of the temporal evolution of structural soil hydraulic properties at the site. Soil hydraulic conductivity in the slightly unsaturated range (-7 cm to -10

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

Geochemical and hydrologic controls on the mobilization of arsenic derived from herbicide application

International Nuclear Information System (INIS)

Fitzmaurice, Arthur G.; Bilgin, A. Azra; O'Day, Peggy A.; Illera, Virginia; Burris, David R.; Reisinger, H. James; Hering, Janet G.

2009-01-01

The fate and transport of As was examined at an industrial site where soil- and groundwater contamination are derived from the application of As 2 O 3 as a herbicide. Application of arsenical herbicides was discontinued in the 1970s and soils in the source area were partially excavated in 2003. Arsenic contamination (up to 280 mg/kg) remains in the source area soils and a plume of As-contaminated groundwater persists in the surficial aquifer downgradient of the source area with maximum observed As concentrations of 1200 μg/L near the source area. The spatial extent of As contamination as defined by the 10 μg/L contour appears to have remained relatively stable over the period 1996-2006; the boundary of the 1000 μg/L contour has retreated over the same time period indicating a decrease in total As mass in the surficial groundwater. In column experiments conducted with source area soil, the As concentrations in the column effluent were comparable to those observed in groundwater near the source area. A substantial fraction of the As could be leached from the source area soil with ammonium sulfate and ammonium phosphate. Exhaustive extraction with background groundwater removed most of the total As. These results indicate that As in the source area soils is geochemically labile. Source area soils are low in extractable Fe, Mn and Al, and characterization by X-ray absorption spectroscopy and electron microscopy indicated that As is present primarily as arsenate sorbed to (alumino)silicate minerals. Batch sorption experiments showed much less sorption on surficial aquifer sediments than on sediments from the Jackson Bluff Formation (JBF), a presumed confining layer. This limited capacity of the surficial aquifer sediments for As sorption is consistent with the similar As contents observed for these sediments within and upgradient of the As plume. The apparent stability of the As plume cannot be explained by sequestration of As within the surficial aquifer. Sorption

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

OpenAIRE

Avdić Senada

2007-01-01

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 r...

Baseline Geochemical Data for Medical Researchers in Kentucky

Science.gov (United States)

Anderson, W.

2017-12-01

According to the Centers for Disease Control, Kentucky has the highest cancer incidence and death rates in the country. New efforts by geochemists and medical researchers are examining ways to diagnose the origin and sources of carcinogenesis. In an effort to determine if naturally occurring geochemical or mineral elements contributes to the cancer causation, the Kentucky Geological Survey has established a Minerals and Geochemical Database that is available to medical researchers for examination of baseline geochemistry and determine if naturally occurring mineral or chemical elements contribute to the high rate of cancers in the state. Cancer causation is complex, so if natural sources can be accounted for, then researchers can focus on the true causation. Naturally occurring minerals, metals and elements occur in many parts of the state, and their presence is valuable for evaluating causation. For example, some data in the database contain maps showing (a) statewide elemental geochemistry, (b) areas of black shale oxidation occurrence, which releases metals in soil and surface waters, (c) some clay deposits in the state that can contain high content of rare earth elements, and (d) site-specific uranium occurrences. Knowing the locations of major ore deposits in the state can also provide information related to mineral and chemical anomalies, such as for base metals and mercury. Radionuclide data in soil and water analyses are limited, so future research may involve obtaining more analyses to determine radon potential. This database also contains information on faulting and geology in the state. Although the metals content of trees may not seem relevant, the ash and humus content of degraded trees affects soil, stream sediment and water geochemistry. Many rural homes heat with wood, releasing metals into the surrounding biosphere. Stressed vegetation techniques can be used to explore for ore deposits and look for high metal contents in soils and rocks. These

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

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.......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...

Soil pollution indices conditioned by medieval metallurgical activity - A case study from Krakow (Poland).

Science.gov (United States)

Kowalska, Joanna; Mazurek, Ryszard; Gąsiorek, Michał; Setlak, Marcin; Zaleski, Tomasz; Waroszewski, Jaroslaw

2016-11-01

The studied soil profile under the Main Market Square (MMS) in Krakow was characterised by the influence of medieval metallurgical activity. In the presented soil section lithological discontinuity (LD) was found, which manifests itself in the form of cultural layers (CLs). Moreover, in this paper LD detection methods based on soil texture are presented. For the first time, three different ways to identify the presence of LD in the urban soils are suggested. The presence of LD had an influence on the content and distribution of heavy metals within the soil profile. The content of heavy metals in the CLs under the MMS in Krakow was significantly higher than the content in natural horizons. In addition, there were distinct differences in the content of heavy metals within CLs. Profile variability and differences in the content of heavy metals and phosphorus within the CLs under the MMS were activity indicators of Krakow inhabitants in the past. This paper presents alternative methods for the assessment of the degree of heavy metal contamination in urban soils using selected pollution indices. On the basis of the studied total concentration of heavy metals (Zn, Pb, Cu, Mn, Cr, Cd, Ni, Sn, Ag) and total phosphorus content, the Geoaccumulation Index (I geo ), Enrichment Factor (EF), Sum of Pollution Index (PI sum ), Single Pollution Index (PI), Nemerow Pollution Index (PI Nemerow ) and Potential Ecological Risk (RI) were calculated using different local and reference geochemical backgrounds. The use of various geochemical backgrounds is helpful to evaluate the assessment of soil pollution. The individual CLs differed from each other according to the degree of pollution. The different values of pollution indices within the studied soil profile showed that LDS should not be evaluated in terms of contamination as one, homogeneous soil profile but each separate CL should be treated individually. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimation of geochemical parameters for assessing subsurface transport at the Savannah River Plant: Environmental information document

International Nuclear Information System (INIS)

Looney, B.B.; Grant, M.W.; King, C.M.

1987-03-01

Geochemical parameter estimates to be used in assessing the subsurface transport of chemicals from Savannah River Plant (SRP) waste sites are presented. Specifically, reference values for soil-solution distribution coefficients, solubility, leach rates, and retardation coefficients are estimated for 31 inorganic chemicals (assuming speciation is governed by reasonable assumptions about controlling variables such as Eh and pH) and 36 organic compounds. Additionally, facilitated transport (the association of chemicals with inorganic and organic ligands or colloids resulting in relatively high mobility) was estimated using field data to derive a fraction of the disposal mass which was assumed to be mobile. Hydrologic parameters such as dispersion coefficient, average moisture content in vadose zone, bulk density, and effective porosity are also presented. The estimates are based on site-specific studies when available, combined with technical literature

Recalcitrant soil organic matter : how useful is radiocarbon for estimating its amount and variability?

International Nuclear Information System (INIS)

Tate, K.; Parshotam, A.; Scott, Neal

1997-01-01

The role of the terrestrial biosphere in the global carbon (C) cycle is poorly understood because of the complex biology underlying C storage, the spatial variability of vegetation and soils, and the effects of land use. Little is known about the nature, amount and variability of recalcitrant C in soils, despite the importance of determining whether soils behave as sources or sinks of CO 2 . 14 C dating indicates that most soils contain this very stable C fraction, with turnover times of millennia. The amount of this fraction, named the Inert Organic Matter (IOM) in one model, is estimated indirectly using the 'bomb' 14 C content of soil. In nine New Zealand grassland and forest ecosystems, amounts of IOM-C ranged between 0.03 to 2.9 kg C m -2 (1-18% of soil C to 0.25m depth). A decomposable C fraction, considered to be more susceptible to the effects of climate and land use, was estimated by subtracting the IOM-C fraction from the total soil organic C. Turnover times ranged between 8 and 36 years, and were inversely related to mean annual temperature (R 2 0.91, P 13 C NMR and pyrolysis-mass spectrometry as alkyl C. Paradoxically, for some ecosystems, the variation in IOM-C appears to be best explained by differences in soil hydrological conditions rather than by the accumulation of a discrete C fraction. Thus characterisation of environmental factors that constrain decomposition could be most useful for explaining the differences observed in IOM across different ecosystems, climates and soils. Despite the insights the modelling approach using 'bomb' 14 C provides into mechanisms for organic matter stabilisation, on theoretical grounds the validity of using 14 C measurements to estimate a recalcitrant C fraction that by definition contains no 14 C is questionable. We conclude that more rigorous models are needed with pools that can be experimentally verified, to improve understanding of the spatial variability of soil C storage. (author)

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

Soil properties show signifficant spatial variability at local, regional and continental scales. This is a challenge for life cycle impact assessment (LCIA) of metals, because fate, bioavailability and effect factors are controlled by environmental chemistry and can vary orders of magnitude...... 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...

Spatio-temporal variability of soil respiration in a spruce-dominated headwater catchment in western Germany

Science.gov (United States)

Bossa, A. Y.; Diekkrüger, B.

2014-08-01

CO2 production and transport from forest floors is an important component of the carbon cycle and is closely related to the global atmosphere CO2 concentration. If we are to understand the feedback between soil processes and atmospheric CO2, we need to know more about the spatio-temporal variability of this soil respiration under different environmental conditions. In this study, long-term measurements were conducted in a spruce-dominated forest ecosystem in western Germany. Multivariate analysis-based similarities between different measurement sites led to the detection of site clusters along two CO2 emission axes: (1) mainly controlled by soil temperature and moisture condition, and (2) mainly controlled by root biomass and the forest floor litter. The combined effects of soil temperature and soil moisture were used as a time-dependent rating factor affecting the optimal CO2 production and transport at cluster level. High/moderate/weak time-dependent rating factors were associated with the different clusters. The process-based, most distant clusters were identified using specified pattern characteristics: the reaction rates in the soil layers, the activation energy for bio-chemical reactions, the soil moisture dependency parameter, the root biomass factor, the litter layer factor and the organic matter factor. A HYDRUS-1D model system was inversely used to compute soil hydraulic parameters from soil moisture measurements. Heat transport parameters were calibrated based on observed soil temperatures. The results were used to adjust CO2 productions by soil microorganisms and plant roots under optimal conditions for each cluster. Although the uncertainty associated with the HYDRUS-1D simulations is higher, the results were consistent with both the multivariate clustering and the time-dependent rating of site production. Finally, four clusters with significantly different environmental conditions (i.e. permanent high soil moisture condition, accumulated litter amount

[Effects of land use and environmental factors on the variability of soil quality indicators in hilly Loess Plateau region of China].

Science.gov (United States)

Xu, Ming-Xiang; Liu, Guo-Bin; Zhao, Yun-Ge

2011-02-01

Classical statistics methods were adopted to analyze the soil quality variability, its affecting factors, and affecting degree at a regional scale (700 km2) in the central part of hilly Loess Plateau region of China. There existed great differences in the variability of test soil quality indicators. Soil pH, structural coefficient, silt content, specific gravity, bulk density, total porosity, capillary porosity, and catalase activity were the indicators with weak variability; soil nutrients (N, P, and K) contents, CaCO3 content, cation exchange capacity (CEC), clay content, micro-aggregate mean mass diameter, aggregate mean mass diameter, water-stable aggregates, respiration rate, microbial quotient, invertase and phosphatase activities, respiratory quotient, and microbial carbon and nitrogen showed medium variation; while soil labile organic carbon and phosphorus contents, erosion-resistance, permeability coefficient, and urease activity were the indicators with strong variability. The variability of soil CaCO3, total P and K, CEC, texture, and specific gravity, etc. was correlated with topography and other environmental factors, while the variability of dynamic soil quality indicators, including soil organic matter content, nitrogen content, water-stable aggregates, permeability, microbial biomass carbon and nitrogen, enzyme activities, and respiration rate, was mainly correlated with land use type. Overall, land use pattern explained 97% of the variability of soil quality indicators in the region. It was suggested that in the evaluation of soil quality in hilly Loess Plateau region, land use type and environmental factors should be fully considered.

Spatial Variability of Soil-Water Storage in the Southern Sierra Critical Zone Observatory: Measurement and Prediction

Science.gov (United States)

Oroza, C.; Bales, R. C.; Zheng, Z.; Glaser, S. D.

2017-12-01

Predicting the spatial distribution of soil moisture in mountain environments is confounded by multiple factors, including complex topography, spatial variably of soil texture, sub-surface flow paths, and snow-soil interactions. While remote-sensing tools such as passive-microwave monitoring can measure spatial variability of soil moisture, they only capture near-surface soil layers. Large-scale sensor networks are increasingly providing soil-moisture measurements at high temporal resolution across a broader range of depths than are accessible from remote sensing. It may be possible to combine these in-situ measurements with high-resolution LIDAR topography and canopy cover to estimate the spatial distribution of soil moisture at high spatial resolution at multiple depths. We study the feasibility of this approach using six years (2009-2014) of daily volumetric water content measurements at 10-, 30-, and 60-cm depths from the Southern Sierra Critical Zone Observatory. A non-parametric, multivariate regression algorithm, Random Forest, was used to predict the spatial distribution of depth-integrated soil-water storage, based on the in-situ measurements and a combination of node attributes (topographic wetness, northness, elevation, soil texture, and location with respect to canopy cover). We observe predictable patterns of predictor accuracy and independent variable ranking during the six-year study period. Predictor accuracy is highest during the snow-cover and early recession periods but declines during the dry period. Soil texture has consistently high feature importance. Other landscape attributes exhibit seasonal trends: northness peaks during the wet-up period, and elevation and topographic-wetness index peak during the recession and dry period, respectively.

Using Environmental Variables for Studying of the Quality of Sampling in Soil Mapping

Directory of Open Access Journals (Sweden)

A. Jafari

2016-02-01

profiles, which were then described, sampled, analyzed and classified according to the USDA soil classification system (16. The basic rationale is to set up a hypercube, the axes of which are the quantiles of rasters of environmental covariates, e.g., digital elevation model. Sampling evaluation was made using the HELS algorithm. This algorithm was written based on the study of Carre et al., 2007 (3 and run in R. Results and Discussion: The covariate dataset is represented by elevation, slope and wetness index (Table 2. All data layers were interpolated to a common grid of 30 m resolution. The size of the raster layer is 421 by 711 grid cells. Each of the three covariates is divided into four quantiles (Table 2. The hypercube character space has 43, i.e. 64 strata (Figure 5. The average number of grid cells within each stratum is therefore 4677 grid cells. The map of the covariate index (Figure 6 shows some patterns representative of the covariate variability. The values of the covariate index range between 0.0045 and 5.95. This means that some strata are very dense compared to others. This index allows us to explain if high or low relative weight of the sampling units (see below is due to soil sampling or covariate density. The strata with the highest density are in the areas with high geomorphology diversity. It means that geomorphology processes can cause the diversity and variability and it is in line with the geomorphology map (Figure 2. Of the 64 strata, 30.4% represent under-sampling, 60.2% represent adequate sampling and 9.4% represent over-sampling. Regarding the covariate index, most of the under-sampling appears in the high covariate index, where soil covariates are then highly variable. Actually, it is difficult to collect field samples in these highly variable areas (Figure 7. Also, most of the over-sampling was observed in areas with alow covariate index (Figure 7. We calculated the weights of all the sampling units and showed the results in Figure 8. One 64

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

2017-05-01

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.

Geochemical study of military bases impact on the environment in Belarus

International Nuclear Information System (INIS)

Kudelsky, A.V.; Lukashev, V.K.; Kovalyov, A.A.

2000-01-01

It has been established that the geochemical and ecological situation in the sites formerly occupied by military bases does not satisfy nature management and living standards. The concentrations of heavy metals (Pb, Zn, Cd, Mo and Cu), oil products and semi-volatile organic compounds in soil and ground which exceed the permissible contamination limits make them dangerous for utilisation and require cleaning up measures

Environmental and management influences on temporal variability of near saturated soil hydraulic properties☆

Science.gov (United States)

Bodner, G.; Scholl, P.; Loiskandl, W.; Kaul, H.-P.

2013-01-01

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (− 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average

Environmental and management influences on temporal variability of near saturated soil hydraulic properties.

Science.gov (United States)

Bodner, G; Scholl, P; Loiskandl, W; Kaul, H-P

2013-08-01

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (- 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r 2  = 0.43 to 0.59). Our results suggested that beside considering average

Geochemical Anomalies in the Sediments of Lake Druksiai

International Nuclear Information System (INIS)

Kleinas, A.

1999-01-01

In order to evaluate the impact of Ignalina Nuclear Power Plant (NPP) on natural processes in Lake Druksiai and accumulation of pollutants, in 19931997, carrying on the state scientific program, the Marine Geochemistry Division of the Institute of Geography performed lithological geochemical mapping of lake bottom sediments on a scale of 1 .50 000. The results obtained enabled to distinguish zones of higher anthropogenous geochemical load, where geochemical anomalies of pollutants, including oil hydrocarbons and heavy metals, had been taken into account. Applying concentration coefficients for oil hydrocarbons and heavy metals (Cr, Cu, Ni, Pb, and Zn) and their natural background, the attempt was made to differentiate natural and technogenous components in the geochemical anomalies As expected, the finer sediments -aleurite-pelite mud - showed amounts of oil hydrocarbons and heavy metals being 12.1 times higher than in fine sand - the most coarse of the sediments studied Sediments with organic mater exceeding 20% contained 11.7 times more pollutants than those with organic matter below 1 .5%. Calculations of concentration coefficients (CC) showed no elements in no stations exceeded 10 - the sediments did not reach the category of high pollution However, in many sites, the coefficients exceeded values of 1-2, thus, showing sediments attributable to the categories of weakly polluted or just polluted. Mapping model done by GIS methods (by superimposing schemes of pollutant CCs distribution in the lake and summing them) for geochemical anomalies two derivative map-schemes were obtained for oil hydrocarbons and heavy metals. They showed that clean sediments cover just 24.75% (according to the pollutant background for soil types) and 12.35% (according to the organic matter background for its amount intervals) lake bottom area. Zones slightly polluted by an element at least cover 69.7 and 80.29% of lake area, correspondingly; whereas zones slightly polluted by all

Geochemical exploration for uranium

International Nuclear Information System (INIS)

1988-01-01

This Technical Report is designed mainly to introduce the methods and techniques of uranium geochemical exploration to exploration geologists who may not have had experience with geochemical exploration methods in their uranium programmes. The methods presented have been widely used in the uranium exploration industry for more than two decades. The intention has not been to produce an exhaustive, detailed manual, although detailed instructions are given for a field and laboratory data recording scheme and a satisfactory analytical method for the geochemical determination of uranium. Rather, the intention has been to introduce the concepts and methods of uranium exploration geochemistry in sufficient detail to guide the user in their effective use. Readers are advised to consult general references on geochemical exploration to increase their understanding of geochemical techniques for uranium

Effect of land-use practice on soil moisture variability for soils covered with dense forest vegetation of Puerto Rico

Science.gov (United States)

Tsegaye, T.; Coleman, T.; Senwo, Z.; Shaffer, D.; Zou, X.

1998-01-01

Little is known about the landuse management effect on soil moisture and soil pH distribution on a landscape covered with dense tropical forest vegetation. This study was conducted at three locations where the history of the landuse management is different. Soil moisture was measured using a 6-cm three-rod Time Domain Reflectometery (TDR) probe. Disturbed soil samples were taken from the top 5-cm at the up, mid, and foothill landscape position from the same spots where soil moisture was measured. The results showed that soil moisture varies with landscape position and depth at all three locations. Soil pH and moisture variability were found to be affected by the change in landuse management and landscape position. Soil moisture distribution usually expected to be relatively higher in the foothill (P3) area of these forests than the uphill (P1) position. However, our results indicated that in the Luquillo and Guanica site the surface soil moisture was significantly higher for P1 than P3 position. These suggest that the surface and subsurface drainage in these two sites may have been poor due to the nature of soil formation and type.

Latin Hypercube Sampling (LHS) at variable resolutions for enhanced watershed scale Soil Sampling and Digital Soil Mapping.

Science.gov (United States)

Hamalainen, Sampsa; Geng, Xiaoyuan; He, Juanxia

2017-04-01

Latin Hypercube Sampling (LHS) at variable resolutions for enhanced watershed scale Soil Sampling and Digital Soil Mapping. Sampsa Hamalainen, Xiaoyuan Geng, and Juanxia, He. AAFC - Agriculture and Agr-Food Canada, Ottawa, Canada. The Latin Hypercube Sampling (LHS) approach to assist with Digital Soil Mapping has been developed for some time now, however the purpose of this work was to complement LHS with use of multiple spatial resolutions of covariate datasets and variability in the range of sampling points produced. This allowed for specific sets of LHS points to be produced to fulfil the needs of various partners from multiple projects working in the Ontario and Prince Edward Island provinces of Canada. Secondary soil and environmental attributes are critical inputs that are required in the development of sampling points by LHS. These include a required Digital Elevation Model (DEM) and subsequent covariate datasets produced as a result of a Digital Terrain Analysis performed on the DEM. These additional covariates often include but are not limited to Topographic Wetness Index (TWI), Length-Slope (LS) Factor, and Slope which are continuous data. The range of specific points created in LHS included 50 - 200 depending on the size of the watershed and more importantly the number of soil types found within. The spatial resolution of covariates included within the work ranged from 5 - 30 m. The iterations within the LHS sampling were run at an optimal level so the LHS model provided a good spatial representation of the environmental attributes within the watershed. Also, additional covariates were included in the Latin Hypercube Sampling approach which is categorical in nature such as external Surficial Geology data. Some initial results of the work include using a 1000 iteration variable within the LHS model. 1000 iterations was consistently a reasonable value used to produce sampling points that provided a good spatial representation of the environmental

Chemical weathering and loess inputs to soils in New Zealand's Wairarapa region

Science.gov (United States)

Lukens, C. E.; Norton, K. P.

2017-12-01

Geochemical mass-balance approaches are commonly used in soils to evaluate patterns in chemical weathering. In conjuction with cosmogenic nuclide measurements of total denudation or soil production, mass-balance approaches have been used to constrain rates of chemical weathering across a variety of landscapes. Here we present geochemical data from a series of soil pits in the Wairarapa region of New Zealand's North Island, where rates of soil production equal rates of total denudation measured using 10Be at sites nearby (i.e., the landscape is in steady state). Soil density increases with depth, consistent with steady weathering over the average soil residence time. However, soil geochemistry indicates very little chemical weathering has occurred, and immobile elements (Zr, Ti, and V) are depleted in soils relative to bedrock. This is contrary to the expected observation, wherein immobile elements should be enriched in soils relative to parent bedrock as weathered mobile solutes are progressively removed from soil. Our geochemical measurements suggest contributions from an exernal source, which has a different chemical composition than the underlying bedrock. We hypothesize that loess constitutes a substantial influx of additional material, and use a mixing model to predict geochemical patterns within soil columns. We evaluate the relative contributions of several likely loess sources, including tephra from the nearby Taupo Volcanic Center, local loess deposits formed during glacial-interglacial transitions, and far-travelling Australian dust. Using an established mass-balance approach with multiple immobile elements, we calculate the fraction of mass in soils contributed by loess to be as much as 25%. Combined with 10Be-derived estimates of soil production, we calculate average loess fluxes up to 320 t/km2/yr, which are consistent with previous estimates of loess acculumation over the late Holocene. Accounting for loess input, we find that chemical weathering

Geochemical sensitivity analysis: Identification of important geochemical parameters for performance assessment studies

International Nuclear Information System (INIS)

Siegel, M.; Guzowski, R.; Rechard, R.; Erickson, K.

1986-01-01

The EPA Standard for geologic disposal of high level waste requires demonstration that the cumulative discharge of individual radioisotopes over a 10,000 year period at points 5 kilometers from the engineered barrier system will not exceed the limits prescribed in 40 CFR Part 191. The roles of the waste package, engineered facility, hydrogeology and geochemical processes in limiting radionuclide releases all must be considered in calculations designed to assess compliance of candidate repositories with the EPA Standard. In this talk, they will discuss the geochemical requirements of calculations used in these compliance assessments. In addition, they will describe the complementary roles of (1) simple models designed to bound the radionuclide discharge over the widest reasonable range of geochemical conditions and scenarios and (2) detailed geochemical models which can provide insights into the actual behavior of the radionuclides in the ground water. Finally, they will discuss development of sensitivity/uncertainty techniques designed to identify important site-specific geochemical parameters and processes using data from a basalt formation

EXPERIMENTAL DETERMINATION OF VARIABILITY IN PERMEABILITY OF SANDY SILT SOIL MIXED WITH FLY ASH IN PROPORTIONATE

OpenAIRE

Rasna Sharma*, Dr. M.K. Trivedi

2016-01-01

This paper presents the experimental determination of variability in permeability of sandy silt soil by blending with fly ash. The grain size, porosity, structure of the soil, specific gravity of the soil, viscosity and temperature are important factors in varying the permeability of the soil. Permeability is the flow conduction property of the soil. The void ratio with in the soil plays a vital role in varying the permeability. By blending with finer grains like fly ash in the soil with sand...

Effect of Crop-Straw Derived Biochars on Pb(II) Adsorption in Two Variable Charge Soils

Institute of Scientific and Technical Information of China (English)

JIANG Tian-yu; XU Ren-kou; GU Tian-xia; JIANG Jun

2014-01-01

Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb(II) adsorption using batch experiments. The results showed soil cation exchange capacity (CEC) and pH signiifcantly increased after 30 d of incubation with the biochars added. The incorporation of the biochars markedly increased the adsorption of Pb(II), and both the electrostatic and non-electrostatic adsorption mechanisms contributed to Pb(II) adsorption by the variable charge soils. Adsorption isotherms illustrated legume-straw derived biochars more greatly increased Pb(II) adsorption on soils through the non-electrostatic mechanism via the formation of surface complexes between Pb(II) and acid functional groups of the biochars than did non-legume straw biochars. The adsorption capacity of Pb(II) increased, while the desorption amount slightly decreased with the increasing suspension pH for the studied soils, especially in a high suspension pH, indicating that precipitation also plays an important role in immobilizing Pb(II) to the soils.

Modeling Background Radiation in our Environment Using Geochemical Data

Energy Technology Data Exchange (ETDEWEB)

Malchow, Russell L.; Marsac, Kara [University of Nevada, Las Vegas; Burnley, Pamela [University of Nevada, Las Vegas; Hausrath, Elisabeth [Uniiversity of Nevada, Las Vegas; Haber, Daniel [University of Nevada, Las Vegas; Adcock, Christopher [University of Nevada, Las Vegas

2015-02-01

Radiation occurs naturally in bedrock and soil. Gamma rays are released from the decay of the radioactive isotopes K, U, and Th. Gamma rays observed at the surface come from the first 30 cm of rock and soil. The energy of gamma rays is specific to each isotope, allowing identification. For this research, data was collected from national databases, private companies, scientific literature, and field work. Data points were then evaluated for self-consistency. A model was created by converting concentrations of U, K, and Th for each rock and soil unit into a ground exposure rate using the following equation: D=1.32 K+ 0.548 U+ 0.272 Th. The first objective of this research was to compare the original Aerial Measurement System gamma ray survey to results produced by the model. The second objective was to improve the method and learn the constraints of the model. Future work will include sample data analysis from field work with a goal of improving the geochemical model.

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.

Reactive transport modeling in variably saturated porous media with OGS-IPhreeqc

Science.gov (United States)

He, W.; Beyer, C.; Fleckenstein, J. H.; Jang, E.; Kalbacher, T.; Shao, H.; Wang, W.; Kolditz, O.

2014-12-01

Worldwide, sustainable water resource management becomes an increasingly challenging task due to the growth of population and extensive applications of fertilizer in agriculture. Moreover, climate change causes further stresses to both water quantity and quality. Reactive transport modeling in the coupled soil-aquifer system is a viable approach to assess the impacts of different land use and groundwater exploitation scenarios on the water resources. However, the application of this approach is usually limited in spatial scale and to simplified geochemical systems due to the huge computational expense involved. Such computational expense is not only caused by solving the high non-linearity of the initial boundary value problems of water flow in the unsaturated zone numerically with rather fine spatial and temporal discretization for the correct mass balance and numerical stability, but also by the intensive computational task of quantifying geochemical reactions. In the present study, a flexible and efficient tool for large scale reactive transport modeling in variably saturated porous media and its applications are presented. The open source scientific software OpenGeoSys (OGS) is coupled with the IPhreeqc module of the geochemical solver PHREEQC. The new coupling approach makes full use of advantages from both codes: OGS provides a flexible choice of different numerical approaches for simulation of water flow in the vadose zone such as the pressure-based or mixed forms of Richards equation; whereas the IPhreeqc module leads to a simplification of data storage and its communication with OGS, which greatly facilitates the coupling and code updating. Moreover, a parallelization scheme with MPI (Message Passing Interface) is applied, in which the computational task of water flow and mass transport is partitioned through domain decomposition, whereas the efficient parallelization of geochemical reactions is achieved by smart allocation of computational workload over

Geochemical characterisation of Elbe river high flood sediments

Energy Technology Data Exchange (ETDEWEB)

Krueger, F. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Falkenberg (Germany). Sektion Boden-/Gewaesserforschung]|[UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Magdeburg (Germany). Sektion Gewaesserforschung; Rupp, H.; Meissner, R. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Falkenberg (Germany). Sektion Boden-/Gewaesserforschung; Lohse, M.; Buettner, O.; Friese, K. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Magdeburg (Germany). Sektion Gewaesserforschung; Miehlich, G. [Hamburg Univ. (Germany). Inst. fuer Bodenkunde

2001-07-01

Quality aims for land usage in flood plains have to be worked out in the Russian-German research project 'Effects of floods on the pollution of agricultural used flood plain soils of the Oka River and the Elbe River'. It is financed by the Germany Ministry of Education and Research (FKZ 02 WT 9617/0). Beside the characterisation of the present pollution of soils for the middle Elbe, it is necessary to prognosticate the current pollutant input. At the examination site nearby Wittenberge, Elbe River kilometers 435 and 440, natural deposited flood sediments were sampled by artificial lawn mats. By the geochemical characterisation it is possible to record the metal input into the flood plain and to win knowledge about the sedimentation process. The results of sediment investigation of the high flood in spring 1997 are presented. (orig.)

Analysis of the variability of some properties of a semi-deciduous forest soil

International Nuclear Information System (INIS)

Okae-Anti, D.; Ogoe, J.I.

2003-05-01

The formation of soils in any region is influenced by many factors such as the parent materials and the secondary materials derived from them, the vegetation and the history of land use. These factors vary from place to place and they contribute to the spatial variation in properties of the soil. Quantification of the magnitude, location and causes of spatial variability is an essential but insufficient ingredient of soil surveys. We took soil samples from the 0-20 cm depth covering soils in the Asuansi-Akroso-Nta-Ofin compound association (Lixisol, Cambisol and Fluvisol association) at the study site, following the nested balanced hierarchical sampling technique. This covered distances between 100 and 0.80 m. Standard laboratory analyses were performed to quantify the selected properties, namely, pH, organic carbon, total nitrogen, total phosphorus, exchangeable potassium and content of sand, silt and clay. Classical statistics and geostatistical procedures were performed on the data and models fitted to the variability patterns. Physical and the more stable properties such as sand, silt and clay were fitted with spherical variogram models. These models indicate a high level of spatial dependence and therefore such properties may be said to be fairly stable in the field. On the contrary, chemical properties such as exchangeable potassium, were fitted with exponential variogram models, indicating that these properties were less stable and showed dependence over longer distances. The scale of variation of the properties ranged between 35 m - 62 m. The degree of uncertainty associated with time and space can be reduced by improved documentation of field variability using the tools of geostatistics. (author)

Modelling carbon and nitrogen turnover in variably saturated soils

Science.gov (United States)

Batlle-Aguilar, J.; Brovelli, A.; Porporato, A.; Barry, D. A.

2009-04-01

Natural ecosystems provide services such as ameliorating the impacts of deleterious human activities on both surface and groundwater. For example, several studies have shown that a healthy riparian ecosystem can reduce the nutrient loading of agricultural wastewater, thus protecting the receiving surface water body. As a result, in order to develop better protection strategies and/or restore natural conditions, there is a growing interest in understanding ecosystem functioning, including feedbacks and nonlinearities. Biogeochemical transformations in soils are heavily influenced by microbial decomposition of soil organic matter. Carbon and nutrient cycles are in turn strongly sensitive to environmental conditions, and primarily to soil moisture and temperature. These two physical variables affect the reaction rates of almost all soil biogeochemical transformations, including microbial and fungal activity, nutrient uptake and release from plants, etc. Soil water saturation and temperature are not constants, but vary both in space and time, thus further complicating the picture. In order to interpret field experiments and elucidate the different mechanisms taking place, numerical tools are beneficial. In this work we developed a 3D numerical reactive-transport model as an aid in the investigation the complex physical, chemical and biological interactions occurring in soils. The new code couples the USGS models (MODFLOW 2000-VSF, MT3DMS and PHREEQC) using an operator-splitting algorithm, and is a further development an existing reactive/density-dependent flow model PHWAT. The model was tested using simplified test cases. Following verification, a process-based biogeochemical reaction network describing the turnover of carbon and nitrogen in soils was implemented. Using this tool, we investigated the coupled effect of moisture content and temperature fluctuations on nitrogen and organic matter cycling in the riparian zone, in order to help understand the relative

Uranium soils integrated demonstration: Soil characterization project report

International Nuclear Information System (INIS)

Cunnane, J.C.; Gill, V.R.; Lee, S.Y.; Morris, D.E.; Nickelson, M.D.; Perry, D.L.; Tidwell, V.C.

1993-08-01

An Integrated Demonstration Program, hosted by the Fernald Environmental Management Project (FEMP), has been established for investigating technologies applicable to the characterization and remediation of soils contaminated with uranium. Critical to the design of relevant treatment technologies is detailed information on the chemical and physical characteristics of the uranium waste-form. To address this need a soil sampling and characterization program was initiated which makes use of a variety of standard analytical techniques coupled with state-of-the-art microscopy and spectroscopy techniques. Sample representativeness is evaluated through the development of conceptual models in an effort to identify and understand those geochemical processes governing the behavior of uranium in FEMP soils. Many of the initial results have significant implications for the design of soil treatment technologies for application at the FEMP

Uranium soils integrated demonstration: Soil characterization project report

Energy Technology Data Exchange (ETDEWEB)

Cunnane, J.C. [Argonne National Lab., IL (United States); Gill, V.R. [Fernald Environmental Restoration Management Corp., Cincinnati, OH (United States); Lee, S.Y. [Oak Ridge National Lab., TN (United States); Morris, D.E. [Los Alamos National Lab., NM (United States); Nickelson, M.D. [HAZWRAP, Oak Ridge, TN (United States); Perry, D.L. [Lawrence Berkeley Lab., CA (United States); Tidwell, V.C. [Sandia National Labs., Albuquerque, NM (United States)

1993-08-01

An Integrated Demonstration Program, hosted by the Fernald Environmental Management Project (FEMP), has been established for investigating technologies applicable to the characterization and remediation of soils contaminated with uranium. Critical to the design of relevant treatment technologies is detailed information on the chemical and physical characteristics of the uranium waste-form. To address this need a soil sampling and characterization program was initiated which makes use of a variety of standard analytical techniques coupled with state-of-the-art microscopy and spectroscopy techniques. Sample representativeness is evaluated through the development of conceptual models in an effort to identify and understand those geochemical processes governing the behavior of uranium in FEMP soils. Many of the initial results have significant implications for the design of soil treatment technologies for application at the FEMP.

Soil properties related to 60Co bioavailability in tropical soils

International Nuclear Information System (INIS)

Bartoly, Flavia; Wasserman, Maria Angelica; Rochedo, Elaine Ruas Rodriguez; Viana, Aline Gonzalez; Souza, Rodrigo Camara; Oliveira, Giselle Rodrigues; Reis, Wagner Goncalves Soares; Perez, Daniel Vidal

2005-01-01

This work presents the results of field experiments to obtain soil to plants Transfer factor (TF) for 60 Co in reference plants cultivated in Ferralsol, Acrisol and Nitisol. These soils represent the majority of Brazilian agricultural area. Values of TF varied from 0.001 to 0.05 for corn and from 0.001 to 0.81 for cabbage. Results of 60 Co TF were discussed in relation to the physical and chemical properties of the soils and 60 Co geochemical partition. The sequential chemical extraction showed that more than 40% of the 60 Co present in the soils are associated to manganese oxides. These results will provide regional values for parameters used in the environmental radiological modeling aiming to optimize the planning of emergency interventions or the waste management related to tropical soils. (author)

SITE Technology Capsule. Demonstration of Rocky Mountain Remediation Services Soil Amendment

Science.gov (United States)

This report briefly summarizes the Rocky Mountain Remediation Services treatment technology demonstration of a soil amendment process for lead contaminated soil at Roseville, OH. The evaluation included leaching, bioavailability, geotechnical, and geochemical methods.

Decoupling of lignin and total litter decomposition across North American forest soils: a phenomenon to reconcile old and new paradigms of soil organic matter?

Science.gov (United States)

Hall, S. J.; Hammel, K.

2017-12-01

An "old" paradigm of soil organic matter (SOM) posited that biochemically "recalcitrant" lignin derivatives were a dominant constituent. Over the past decade(s), evidence for a newer paradigm has emerged which suggests that recalcitrance has little long-term impact on the biochemical composition of SOM, and that lignin is relatively unimportant in comparison with dead microbial biomass. Yet, methodological biases have hampered accurate quantification of lignin dynamics in mineral soils, and may have led to systematic underestimates of lignin stocks and turnover. Here, we sought to test this aspect of the "new" SOM paradigm. Synthetic position-specific 13C-labeled lignins provide a robust quantitative method to track the mineralization and fate of lignin moieties in mineral soils. Relatively few microbial taxa are known to depolymerize macromolecular lignin, and lignin derivatives can specifically associate with iron oxide mineral phases. Consequently, we hypothesized that decomposition of lignin is poorly correlated with total litter decomposition across ecosystems, and that lignin may represent a variable but significant component of decadal-cycling SOM. We incubated 10 forest soils spanning diverse North American ecosystems over seven months under laboratory conditions at constant temperature and moisture. Soils were incubated alone, with added C4 grass litter and natural isotope abundance lignin, and with added C4 litter and 13Cß-labeled lignin. These treatments allowed us to partition respiration for each soil from SOM, litter, and the Cß moiety of lignin—which is diagnostic for cleavage of the polymer. Consistent with our hypothesis, we found much greater variability (ten-fold) in cumulative lignin mineralization relative to bulk litter (two-fold) among soils. Multiple-pool first-order decay models implied that mean turnover times for lignin ranged from one to several decades among soils, relative to several years for bulk litter. Our results suggest a

Temporal variability in Cu speciation, phytotoxicity, and soil microbial activity of Cu-polluted soils as affected by elevated temperature.

Science.gov (United States)

Fu, Qing-Long; Weng, Nanyan; Fujii, Manabu; Zhou, Dong-Mei

2018-03-01

Global warming has obtained increasing attentions due to its multiple impacts on agro-ecosystem. However, limited efforts had been devoted to reveal the temporal variability of metal speciation and phytotoxicity of heavy metal-polluted soils affected by elevated temperature under the global warming scenario. In this study, effects of elevated temperature (15 °C, 25 °C, and 35 °C) on the physicochemical properties, microbial metabolic activities, and phytotoxicity of three Cu-polluted soils were investigated by a laboratory incubation study. Soil physicochemical properties were observed to be significantly altered by elevated temperature with the degree of temperature effect varying in soil types and incubation time. The Biolog and enzymatic tests demonstrated that soil microbial activities were mainly controlled and decreased with increasing incubation temperature. Moreover, plant assays confirmed that the phytotoxicity and Cu uptake by wheat roots were highly dependent on soil types but less affected by incubation temperature. Overall, the findings in this study have highlighted the importance of soil types to better understand the temperature-dependent alternation of soil properties, Cu speciation and bioavailability, as well as phytotoxicity of Cu-polluted soils under global warming scenario. The present study also suggests the necessary of investigating effects of soil types on the transport and accumulation of toxic elements in soil-crop systems under global warming scenario. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesizing Earth's geochemical data for hydrogeochemical analysis

Science.gov (United States)

Brantley, S. L.; Kubicki, J.; Miller, D.; Richter, D.; Giles, L.; Mitra, P.

2007-12-01

For over 200 years, geochemical, microbiological, and chemical data have been collected to describe the evolution of the surface earth. Many of these measurements are data showing variations in time or in space. To forward predict hydrologic response to changing tectonic, climatic, or anthropogenic forcings requires synthesis of these data and utilization in hydrogeochemical models. Increasingly, scientists are attempting to synthesize such data in order to make predictions for new regions or for future time periods. However, to make such complex geochemical data accessible requires development of sophisticated cyberinfrastructures that both invite uploading as well as usage of data. Two such cyberinfrastructure (CI) initiatives are currently developing, one to invite and promote the use of environmental kinetics data (laboratory time course data) through ChemxSeer, and the other to invite and promote the use of spatially indexed geochemical data for the Earth's Critical Zone through CZEN.org. The vision of these CI initiatives is to provide cyber-enhanced portals that encourage domain scientists to upload their data before publication (in private cyberspace), and to make these data eventually publicly accessible (after an embargo period). If the CI can be made to provide services to the domain specialist - e.g. to provide data analysis services or data comparison services - we envision that scientists will upload data. In addition, the CI can promote the use and comparison of datasets across disciplines. For example, the CI can facilitate the use of spatially indexed geochemical data by scientists more accustomed to dealing with time-course data for hydrologic flow, and can provide user-friendly interfaces with CI established to facilitate the use of hydrologic data. Examples of the usage of synthesized data to predict soil development over the last 13ky and its effects on active hydrological flow boundaries in surficial systems will be discussed for i) a N

A soil-landscape framework for understanding spatial and temporal variability in biogeochemical processes in catchments

Science.gov (United States)

McGuire, K. J.; Bailey, S. W.; Ross, D. S.

2017-12-01

Heterogeneity in biophysical properties within catchments challenges how we quantify and characterize biogeochemical processes and interpret catchment outputs. Interactions between the spatiotemporal variability of hydrological states and fluxes and soil development can spatially structure catchments, leading to a framework for understanding patterns in biogeochemical processes. In an upland, glaciated landscape at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA, we are embracing the structure and organization of soils to understand the spatial relations between runoff production zones, distinct soil-biogeochemical environments, and solute retention and release. This presentation will use observations from the HBEF to demonstrate that a soil-landscape framework is essential in understanding the spatial and temporal variability of biogeochemical processes in this catchment. Specific examples will include how laterally developed soils reveal the location of active runoff production zones and lead to gradients in primary mineral dissolution and the distribution of weathering products along hillslopes. Soil development patterns also highlight potential carbon and nitrogen cycling hotspots, differentiate acidic conditions, and affect the regulation of surface water quality. Overall, this work demonstrates the importance of understanding the landscape-level structural organization of soils in characterizing the variation and extent of biogeochemical processes that occur in catchments.

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

2017-10-01

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 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%).

The effect of short-range spatial variability on soil sampling uncertainty

Energy Technology Data Exchange (ETDEWEB)

Perk, Marcel van der [Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht (Netherlands)], E-mail: m.vanderperk@geo.uu.nl; De Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria [Agenzia per la Protezione dell' Ambiente e per i Servizi Tecnici (APAT), Servizio Laboratori, Misure ed Attivita di Campo, Via di Castel Romano, 100-00128 Roma (Italy); Fajgelj, Ales; Sansone, Umberto [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-1400 Vienna (Austria); Jeran, Zvonka; Jacimovic, Radojko [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

2008-11-15

This paper aims to quantify the soil sampling uncertainty arising from the short-range spatial variability of elemental concentrations in the topsoils of agricultural, semi-natural, and contaminated environments. For the agricultural site, the relative standard sampling uncertainty ranges between 1% and 5.5%. For the semi-natural area, the sampling uncertainties are 2-4 times larger than in the agricultural area. The contaminated site exhibited significant short-range spatial variability in elemental composition, which resulted in sampling uncertainties of 20-30%.

The effect of short-range spatial variability on soil sampling uncertainty.

Science.gov (United States)

Van der Perk, Marcel; de Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria; Fajgelj, Ales; Sansone, Umberto; Jeran, Zvonka; Jaćimović, Radojko

2008-11-01

This paper aims to quantify the soil sampling uncertainty arising from the short-range spatial variability of elemental concentrations in the topsoils of agricultural, semi-natural, and contaminated environments. For the agricultural site, the relative standard sampling uncertainty ranges between 1% and 5.5%. For the semi-natural area, the sampling uncertainties are 2-4 times larger than in the agricultural area. The contaminated site exhibited significant short-range spatial variability in elemental composition, which resulted in sampling uncertainties of 20-30%.

Prediction of the effects of soil-based countermeasures on soil solution chemistry of soils contaminated with radiocesium using the hydrogeochemical code PHREEQC.

Science.gov (United States)

Hormann, Volker; Kirchner, Gerald

2002-04-22

For agriculturally used areas, which are contaminated by the debris from a nuclear accident, the use of chemical amendmends (e.g. potassium chloride and lime) is among the most common soil-based countermeasures. These countermeasures are intended to reduce the plant uptake of radionuclides (mainly 137Cs and 90Sr) by competitive inhibition by chemically similar ions. So far, the impacts of countermeasures on soil solution composition - and thus, their effectiveness - have almost exclusively been established experimentally, since they depend on mineral composition and chemical characteristics of the soil affected. In this study, which focuses on caesium contamination, the well-established code PHREEQC was used as a geochemical model to calculate the changes in the ionic compositions of soil solutions, which result from the application of potassium or ammonium in batch equilibrium experiments. The simple ion exchange model used by PHREEQC was improved by taking into account selective sorption of Cs+, NH4+ and K+ by clay minerals. Calculations were performed with three different initial soil solution compositions, corresponding to particular soil types (loam, sand, peat). For loamy and sandy soils, our calculational results agree well with experimental data reported by Nisbet (Effectiveness of soil-based countermeasures six months and one year after contamination of five diverse soil types with caesium-134 and strontium-90. Contract Report NRPB-M546, National Radiation Protection Board, Chilton, 1995.). For peat, discrepancies were found indicating that for organic soils a reliable set of exchange constants of the relevant cations still has to be determined experimentally. For cesium, however, these discrepancies almost disappeared if selective sites were assumed to be inaccessible. Additionally, results of sensitivity analyses are presented by which the influence of the main soil parameters on Cs+ concentrations in solution after soil treatment has been systematically

Influence of Surface Roughness Spatial Variability and Temporal Dynamics on the Retrieval of Soil Moisture from SAR Observations

Directory of Open Access Journals (Sweden)

Jesús Álvarez-Mozos

2009-01-01

Full Text Available Radar-based surface soil moisture retrieval has been subject of intense research during the last decades. However, several difficulties hamper the operational estimation of soil moisture based on currently available spaceborne sensors. The main difficulty experienced so far results from the strong influence of other surface characteristics, mainly roughness, on the backscattering coefficient, which hinders the soil moisture inversion. This is especially true for single configuration observations where the solution to the surface backscattering problem is ill-posed. Over agricultural areas cultivated with winter cereal crops, roughness can be assumed to remain constant along the growing cycle allowing the use of simplified approaches that facilitate the estimation of the moisture content of soils. However, the field scale spatial variability and temporal variations of roughness can introduce errors in the estimation of soil moisture that are difficult to evaluate. The objective of this study is to assess the impact of roughness spatial variability and roughness temporal variations on the retrieval of soil moisture from radar observations. A series of laser profilometer measurements were performed over several fields in an experimental watershed from September 2004 to March 2005. The influence of the observed roughness variability and its temporal variations on the retrieval of soil moisture is studied using simulations performed with the Integral Equation Model, considering different sensor configurations. Results show that both field scale roughness spatial variability and its temporal variations are aspects that need to be taken into account, since they can introduce large errors on the retrieved soil moisture values.

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.

Spatiotemporal predictions of soil properties and states in variably saturated landscapes

Science.gov (United States)

Franz, Trenton E.; Loecke, Terrance D.; Burgin, Amy J.; Zhou, Yuzhen; Le, Tri; Moscicki, David

2017-07-01

Understanding greenhouse gas (GHG) fluxes from landscapes with variably saturated soil conditions is challenging given the highly dynamic nature of GHG fluxes in both space and time, dubbed hot spots, and hot moments. On one hand, our ability to directly monitor these processes is limited by sparse in situ and surface chamber observational networks. On the other hand, remote sensing approaches provide spatial data sets but are limited by infrequent imaging over time. We use a robust statistical framework to merge sparse sensor network observations with reconnaissance style hydrogeophysical mapping at a well-characterized site in Ohio. We find that combining time-lapse electromagnetic induction surveys with empirical orthogonal functions provides additional environmental covariates related to soil properties and states at high spatial resolutions ( 5 m). A cross-validation experiment using eight different spatial interpolation methods versus 120 in situ soil cores indicated an 30% reduction in root-mean-square error for soil properties (clay weight percent and total soil carbon weight percent) using hydrogeophysical derived environmental covariates with regression kriging. In addition, the hydrogeophysical derived environmental covariates were found to be good predictors of soil states (soil temperature, soil water content, and soil oxygen). The presented framework allows for temporal gap filling of individual sensor data sets as well as provides flexible geometric interpolation to complex areas/volumes. We anticipate that the framework, with its flexible temporal and spatial monitoring options, will be useful in designing future monitoring networks as well as support the next generation of hyper-resolution hydrologic and biogeochemical models.

Variability of standard artificial soils: Physico-chemical properties and phenanthrene desorption measured by means of supercritical fluid extraction

International Nuclear Information System (INIS)

Bielská, Lucie; Hovorková, Ivana; Komprdová, Klára; Hofman, Jakub

2012-01-01

The study is focused on artificial soil which is supposed to be a standardized “soil like” medium. We compared physico-chemical properties and extractability of Phenanthrene from 25 artificial soils prepared according to OECD standardized procedures at different laboratories. A substantial range of soil properties was found, also for parameters which should be standardized because they have an important influence on the bioavailability of pollutants (e.g. total organic carbon ranged from 1.4 to 6.1%). The extractability of Phe was measured by supercritical fluid extraction (SFE) at harsh and mild conditions. Highly variable Phe extractability from different soils (3–89%) was observed. The extractability was strongly related (R 2 = 0.87) to total organic carbon content, 0.1–2 mm particle size, and humic/fulvic acid ratio in the following multiple regression model: SFE (%) = 1.35 * sand (%) − 0.77 * TOC (%)2 + 0.27 * HA/FA. - Highlights: ► We compared properties and extractability of Phe from 25 different artificial soils. ► Substantial range of soil properties was found, also for important parameters. ► Phe extractability was measured by supercritical fluid extraction (SFE) at 2 modes. ► Phe extractability was highly variable from different soils (3–89%). ► Extractability was strongly related to TOC, 0.1–2 mm particles, and HA/FA. - Significant variability in physico-chemical properties exists between artificial soils prepared at different laboratories and affects behavior of contaminants in these soils.

Impact of long-term diesel contamination on soil microbial community structure

DEFF Research Database (Denmark)

Sutton, Nora; Maphosa, Farai; Morillo, Jose

2013-01-01

Microbial community composition and diversity at a diesel-contaminated railway site were investigated by pyrosequencing of bacterial and archaeal 16S rRNA gene fragments to understand the interrelationships among microbial community composition, pollution level, and soil geochemical and physical...... properties. To this end, 26 soil samples from four matrix types with various geochemical characteristics and contaminant concentrations were investigated. The presence of diesel contamination significantly impacted microbial community composition and diversity, regardless of the soil matrix type. Clean...... observed in contaminated samples. Redundancy analysis indicated that increased relative abundances of the phyla Chloroflexi, Firmicutes, and Euryarchaeota correlated with the presence of contamination. Shifts in the chemical composition of diesel constituents across the site and the abundance of specific...

When soils become sediments

NARCIS (Netherlands)

Vink, Jos P.M.; Zomeren, van Andre; Dijkstra, Joris J.; Comans, Rob N.J.

2017-01-01

Simulating the storage of aerobic soils under water, the chemical speciation of heavy metals and arsenic was studied over a long-term reduction period. Time-dynamic and redox-discrete measurements in reactors were used to study geochemical changes. Large kinetic differences in the

Geochemical surveys in the Lusi mud eruption

Science.gov (United States)

Sciarra, Alessandra; Mazzini, Adriano; Etiope, Giuseppe; Inguaggiato, Salvatore; Hussein, Alwi; Hadi J., Soffian

2016-04-01

The Lusi mud eruption started in May 2006 following to a 6.3 M earthquake striking the Java Island. In the framework of the Lusi Lab project (ERC grant n° 308126) we carried out geochemical surveys in the Sidoarjo district (Eastern Java Island, Indonesia) to investigate the gas bearing properties of the Watukosek fault system that crosses the Lusi mud eruption area. Soil gas (222Rn, CO2, CH4) concentration and flux measurements were performed 1) along two detailed profiles (~ 1km long), trending almost W-E direction, and 2) inside the Lusi embankment (about 7 km2) built to contain the erupted mud. Higher gas concentrations and fluxes were detected at the intersection with the Watukosek fault and the antithetic fault system. These zones characterized by the association of higher soil gas values constitute preferential migration pathways for fluids towards surface. The fractures release mainly CO2 (with peaks up to 400 g/m2day) and display higher temperatures (up to 41°C). The main shear zones are populated by numerous seeps that expel mostly CH4. Flux measurements in the seeping pools reveal that φCO2 is an order of magnitude higher than that measured in the fractures, and two orders of magnitude higher for φCH4. An additional geochemical profile was completed perpendicularly to the Watukosek fault escarpement (W-E direction) at the foots of the Penanngungang volcano. Results reveal CO2 and CH4 flux values significantly lower than those measured in the embankment, however an increase of radon and flux measurements is observed approaching the foots of the escarpment. These measurements are complemented with a database of ~350 CH4 and CO2 flux measurements and some soil gas concentrations (He, H2, CO2, CH4 and C2H6) and their isotopic analyses (δ13C-CH4, δD-CH4 and δ13C-CO2). Results show that the whole area is characterized by diffused gas release through seeps, fractures, microfractures and soil degassing. The collected results shed light on the origin of the

Decreasing DOC trends in soil solution along the hillslopes at two IM sites in southern Sweden--geochemical modeling of organic matter solubility during acidification recovery.

Science.gov (United States)

Löfgren, Stefan; Gustafsson, Jon Petter; Bringmark, Lage

2010-12-01

Numerous studies report increased concentrations of dissolved organic carbon (DOC) during the last two decades in boreal lakes and streams in Europe and North America. Recently, a hypothesis was presented on how various spatial and temporal factors affect the DOC dynamics. It was concluded that declining sulphur deposition and thereby increased DOC solubility, is the most important driver for the long-term DOC concentration trends in surface waters. If this recovery hypothesis is correct, the DOC levels should increase both in the soil solution as well as in the surrounding surface waters as soil pH rises and the ionic strength declines due to the reduced input of SO(4)(2-) ions. In this project a geochemical model was set up to calculate the net humic charge and DOC solubility trends in soils during the period 1996-2007 at two integrated monitoring sites in southern Sweden, showing clear signs of acidification recovery. The Stockholm Humic Model was used to investigate whether the observed DOC solubility is related to the humic charge and to examine how pH and ionic strength influence it. Soil water data from recharge and discharge areas, covering both podzols and riparian soils, were used. The model exercise showed that the increased net charge following the pH increase was in many cases counteracted by a decreased ionic strength, which acted to decrease the net charge and hence the DOC solubility. Thus, the recovery from acidification does not necessarily have to generate increasing DOC trends in soil solution. Depending on changes in pH, ionic strength and soil Al pools, the trends might be positive, negative or indifferent. Due to the high hydraulic connectivity with the streams, the explanations to the DOC trends in surface waters should be searched for in discharge areas and peat lands. Copyright © 2010 Elsevier B.V. All rights reserved.

Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

International Nuclear Information System (INIS)

Devau, Nicolas; Cadre, Edith Le; Hinsinger, Philippe; Jaillard, Benoit; Gerard, Frederic

2009-01-01

Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl 2 (P-CaCl 2 ) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH ∼ 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R 2 = 0.9, RMSE = 0.03 mg kg -1 ). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl 2 with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional contribution of soil organic matter.

Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

Energy Technology Data Exchange (ETDEWEB)

Devau, Nicolas [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Cadre, Edith Le [Supagro, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Hinsinger, Philippe; Jaillard, Benoit [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Gerard, Frederic, E-mail: gerard@supagro.inra.fr [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France)

2009-11-15

Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl{sub 2} (P-CaCl{sub 2}) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH {approx} 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R{sup 2} = 0.9, RMSE = 0.03 mg kg{sup -1}). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl{sub 2} with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional

Spatial variability of soil pH based on GIS combined with geostatistics in Panzhihua tobacco area

International Nuclear Information System (INIS)

Du Wei; Wang Changquan; Li Bing; Li Qiquan; Du Qian; Hu Jianxin; Liu Chaoke

2012-01-01

GIS and geostatistics were utilized to study the spatial variability of soil pH in Panzhihua tobacco area. Results showed that pH values in this area ranged from 4.5 to 8.3, especially 5.5 to 6.5, and in few areas were lower than 5.0 or higher than 7.0 which can meet the need of high-quality tobacco production. The best fitting model of variogram was exponential model with the nugget/sill of soil pH in 13.61% indicating strong spatial correlation. The change process was 5.40 km and the coefficient of determination was 0.491. The spatial variability of soil pH was mainly caused by structural factors such as cane, topography and soil type. The soil pH in Panzhihua tobacco area also showed a increasing trend of northwest to southeast trend. The pH of some areas in Caochang, Gonghe and Yumen were lower, and in Dalongtan were slightly higher. (authors)

Landscape controls and vertical variability of soil organic carbon storage in permafrost-affected soils of the Lena River Delta

DEFF Research Database (Denmark)

Siewert, Matthias Benjamin; Hugelius, Gustaf; Heim, Birgit

2016-01-01

To project the future development of the soil organic carbon (SOC) storage in permafrost environments, the spatial and vertical distribution of key soil properties and their landscape controls needs to be understood. This article reports findings from the Arctic Lena River Delta where we sampled 50...... in the permafrost. The major geomorphological units of a subregion of the Lena River Delta were mapped with a land form classification using a data-fusion approach of optical satellite imagery and digital elevation data to upscale SOC storage. Landscape mean SOC storage is estimated to 19.2 ± 2.0 kg C m− 2. Our...... results show that the geomorphological setting explains more soil variability than soil taxonomy classes or vegetation cover. The soils from the oldest, Pleistocene aged, unit of the delta store the highest amount of SOC per m2 followed by the Holocene river terrace. The Pleistocene terrace affected...

Methods for geochemical analysis

Science.gov (United States)

Baedecker, Philip A.

1987-01-01

The laboratories for analytical chemistry within the Geologic Division of the U.S. Geological Survey are administered by the Office of Mineral Resources. The laboratory analysts provide analytical support to those programs of the Geologic Division that require chemical information and conduct basic research in analytical and geochemical areas vital to the furtherance of Division program goals. Laboratories for research and geochemical analysis are maintained at the three major centers in Reston, Virginia, Denver, Colorado, and Menlo Park, California. The Division has an expertise in a broad spectrum of analytical techniques, and the analytical research is designed to advance the state of the art of existing techniques and to develop new methods of analysis in response to special problems in geochemical analysis. The geochemical research and analytical results are applied to the solution of fundamental geochemical problems relating to the origin of mineral deposits and fossil fuels, as well as to studies relating to the distribution of elements in varied geologic systems, the mechanisms by which they are transported, and their impact on the environment.

Role of the Soil Thermal Inertia in the short term variability of the surface temperature and consequences for the soil-moisture temperature feedback

Science.gov (United States)

Cheruy, Frederique; Dufresne, Jean-Louis; Ait Mesbah, Sonia; Grandpeix, Jean-Yves; Wang, Fuxing

2017-04-01

A simple model based on the surface energy budget at equilibrium is developed to compute the sensitivity of the climatological mean daily temperature and diurnal amplitude to the soil thermal inertia. It gives a conceptual framework to quantity the role of the atmospheric and land surface processes in the surface temperature variability and relies on the diurnal amplitude of the net surface radiation, the sensitivity of the turbulent fluxes to the surface temperature and the thermal inertia. The performances of the model are first evaluated with 3D numerical simulations performed with the atmospheric (LMDZ) and land surface (ORCHIDEE) modules of the Institut Pierre Simon Laplace (IPSL) climate model. A nudging approach is adopted, it prevents from using time-consuming long-term simulations required to account for the natural variability of the climate and allow to draw conclusion based on short-term (several years) simulations. In the moist regions the diurnal amplitude and the mean surface temperature are controlled by the latent heat flux. In the dry areas, the relevant role of the stability of the boundary layer and of the soil thermal inertia is demonstrated. In these regions, the sensitivity of the surface temperature to the thermal inertia is high, due to the high contribution of the thermal flux to the energy budget. At high latitudes, when the sensitivity of turbulent fluxes is dominated by the day-time sensitivity of the sensible heat flux to the surface temperature and when this later is comparable to the thermal inertia term of the sensitivity equation, the surface temperature is also partially controlled by the thermal inertia which can rely on the snow properties; In the regions where the latent heat flux exhibits a high day-to-day variability, such as transition regions, the thermal inertia has also significant impact on the surface temperature variability . In these not too wet (energy limited) and not too dry (moisture-limited) soil moisture (SM

Spatial variability of soil carbon, pH, available phosphorous and potassium in organic farm located in Mediterranean Croatia

Science.gov (United States)

Bogunović, Igor; Pereira, Paulo; Šeput, Miranda

2016-04-01

Soil organic carbon (SOC), pH, available phosphorus (P), and potassium (K) are some of the most important factors to soil fertility. These soil parameters are highly variable in space and time, with implications to crop production. The aim of this work is study the spatial variability of SOC, pH, P and K in an organic farm located in river Rasa valley (Croatia). A regular grid (100 x 100 m) was designed and 182 samples were collected on Silty Clay Loam soil. P, K and SOC showed moderate heterogeneity with coefficient of variation (CV) of 21.6%, 32.8% and 51.9%, respectively. Soil pH record low spatial variability with CV of 1.5%. Soil pH, P and SOC did not follow normal distribution. Only after a Box-Cox transformation, data respected the normality requirements. Directional exponential models were the best fitted and used to describe spatial autocorrelation. Soil pH, P and SOC showed strong spatial dependence with nugget to sill ratio with 13.78%, 0.00% and 20.29%, respectively. Only K recorded moderate spatial dependence. Semivariogram ranges indicate that future sampling interval could be 150 - 200 m in order to reduce sampling costs. Fourteen different interpolation models for mapping soil properties were tested. The method with lowest Root Mean Square Error was the most appropriated to map the variable. The results showed that radial basis function models (Spline with Tension and Completely Regularized Spline) for P and K were the best predictors, while Thin Plate Spline and inverse distance weighting models were the least accurate. The best interpolator for pH and SOC was the local polynomial with the power of 1, while the least accurate were Thin Plate Spline. According to soil nutrient maps investigated area record very rich supply with K while P supply was insufficient on largest part of area. Soil pH maps showed mostly neutral reaction while individual parts of alkaline soil indicate the possibility of penetration of seawater and salt accumulation in the

Geochemical investigation of UMTRAP designated site at Salt Lake City, Utah

International Nuclear Information System (INIS)

Markos, G.; Bush, K.J.

1983-09-01

This report is the result of a geochemical investigation of the former uranium mill and tailings site at Salt Lake City, Utah. This is one in a series of site specific geochemical investigations performed on the inactive uranium mill tailings included in the Uranium Mill Tailings Remedial Action Project. The objectives of the investigation are to characterize the geochemistry, to determine the contaminant distribution resulting from the former milling activities and tailings, and to infer chemical pathways and transport mechanisms from the contaminant distribution. The results will be used to model contaminant migration and to develop criteria for long-term containment media such as a cover system which is impermeable to contaminant migration. This report assumes a familiarity with the hydrologic conditions of the site and the geochemical concepts underlying the investigation. The results reported are based on a one-time sampling of waters and solid material from the background, the area adjacent to the site, and the site. The solid samples were water extracted to remove easily soluble salts and acid extracted to remove carbonates and hydroxides. The water extracts and solid samples were anlyzed for the major and trace elements. The report includes the methods of sampling, sample processing, analysis, and data interpretation. Four major conclusions are: (1) sediments in the ditches and creeks adjacent to the site contain tailings, however, the waters were generally not contaminated; (2) tailings are mixed with the soils within a meter below the tailings in some locations, however, water-soluble contaminants decrease to below background levels within 30 cm below the tailings; (3) there has not been significant acid seepage into the soils below the tailings; and (4) salt crusts on the tailings contain trace elements, with the elements that form chloride complexes having the greatest accumulation

Toxicity screening of soils from different mine areas—A contribution to track the sensitivity and variability of Arthrobacter globiformis assay

Energy Technology Data Exchange (ETDEWEB)

Marques, Catarina R., E-mail: crmarques@ua.pt [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Caetano, Ana L. [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Haller, Andreas [ECT Oekotoxikologie GmbH, Böttgerstraße 2–14, D-65439 Flörsheim a. M. (Germany); Gonçalves, Fernando [Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pereira, Ruth [Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto (Portugal); Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, P 4050-123 Porto (Portugal); Römbke, Jörg [ECT Oekotoxikologie GmbH, Böttgerstraße 2–14, D-65439 Flörsheim a. M. (Germany)

2014-06-01

Highlights: • The assay gave rapid and feasible discrimination of toxic soils to A. globiformis. • Sensitive and low variability response to soils from different regions. • Soil properties may interfere with metal toxicity and fluorescence measurements. • Proposal of a toxicity threshold for the contact assay regarding soils. • A. globiformis assay should be included in the Tier I of risk assessment frameworks. - Abstract: This study used the Arthrobacter globiformis solid-contact test for assessing the quality of soils collected in areas subjected to past and present mine activities in Europe (uranium mine, Portugal) and North Africa (phosphogypsum pile, Tunisia; iron mine, Morocco). As to discriminate the influence of soils natural variability from the effect of contaminants, toxicity thresholds were derived for this test, based on the dataset of each study area. Furthermore, the test sensitivity and variability was also evaluated. As a result, soils that inhibited A. globiformis dehydrogenase activity above 45% or 50% relatively to the control, were considered to be toxic. Despite the soil metal content determined, the properties of soils seemed to influence dehydrogenase activity. Overall, the contact test provided a coherent outcome comparing to other more time-consuming and effort-demanding ecotoxicological assays. Our results strengthened the feasibility and ecological relevance of this assay, which variability was quite reduced hence suggesting its potential integration within the test battery of tier 1 of soil risk assessment schemes.

Toxicity screening of soils from different mine areas—A contribution to track the sensitivity and variability of Arthrobacter globiformis assay

International Nuclear Information System (INIS)

Marques, Catarina R.; Caetano, Ana L.; Haller, Andreas; Gonçalves, Fernando; Pereira, Ruth; Römbke, Jörg

2014-01-01

Highlights: • The assay gave rapid and feasible discrimination of toxic soils to A. globiformis. • Sensitive and low variability response to soils from different regions. • Soil properties may interfere with metal toxicity and fluorescence measurements. • Proposal of a toxicity threshold for the contact assay regarding soils. • A. globiformis assay should be included in the Tier I of risk assessment frameworks. - Abstract: This study used the Arthrobacter globiformis solid-contact test for assessing the quality of soils collected in areas subjected to past and present mine activities in Europe (uranium mine, Portugal) and North Africa (phosphogypsum pile, Tunisia; iron mine, Morocco). As to discriminate the influence of soils natural variability from the effect of contaminants, toxicity thresholds were derived for this test, based on the dataset of each study area. Furthermore, the test sensitivity and variability was also evaluated. As a result, soils that inhibited A. globiformis dehydrogenase activity above 45% or 50% relatively to the control, were considered to be toxic. Despite the soil metal content determined, the properties of soils seemed to influence dehydrogenase activity. Overall, the contact test provided a coherent outcome comparing to other more time-consuming and effort-demanding ecotoxicological assays. Our results strengthened the feasibility and ecological relevance of this assay, which variability was quite reduced hence suggesting its potential integration within the test battery of tier 1 of soil risk assessment schemes

A snapshot of soil water composition as an indicator of contrasted redox environments in a hedged farmland plot.

Science.gov (United States)

Albéric, Patrick; Vennink, Aurélie; Cornu, Sophie; Bourennane, Hocine; Bruand, Ary

2009-10-15

While soil water composition has long been recognised as being related to soil type (characteristics of the horizons), the influence of structures resulting from agricultural activities (hedges, ditches, wheel ruts, etc) is still under discussion. This work was undertaken to show that a snapshot of spatial variability of the geochemical characteristics of soil water at the scale of a plot can improve our understanding of soil geochemistry in a farmland setting. We selected a 3 hectare hedged plot located on a hillside, limited by a stream and used as pasture where soils have developed in weathered gneiss. The water depth, electrical conductivity, major ions, temperature, pH, dissolved organic carbon (DOC) content, dissolved oxygen content, fluorescence, alkalinity, Fe(2+), Mn(2+), NO(2)(-), Fe(III) and F(-) contents were measured in 62 auger holes randomly drilled on the site. Four sectors were identified in order to describe the distribution of the main geochemical parameters. Electrical conductivity and some major ions, especially sulphate, had larger concentrations near hedges where oxic conditions prevailed. These features were attributed to the impact of the linear anthropogenic network on the circulation of subsurface soil waters and evapo-transpiration and represent sector I. Dissolved Mn was an indicator of well channelled runoff subsurfaces facilitating the circulation of more highly reducing water (sector III), while DOC probably marked areas drained less well, with a prolonged contact time between soil solutions and organic topsoil horizons (sector II). The presence of dissolved Mn and Fe(II) indicates bottomland anoxic conditions (sector IV). It is concluded that a survey of the chemical composition of soil water may be a direct approach to show the influence of permanent structures on current soil properties and dynamics.

Spatio-temporal variability of soil water content on the local scale in a Mediterranean mountain area (Vallcebre, North Eastern Spain). How different spatio-temporal scales reflect mean soil water content

Science.gov (United States)

Molina, Antonio J.; Latron, Jérôme; Rubio, Carles M.; Gallart, Francesc; Llorens, Pilar

2014-08-01

As a result of complex human-land interactions and topographic variability, many Mediterranean mountain catchments are covered by agricultural terraces that have locally modified the soil water content dynamic. Understanding these local-scale dynamics helps us grasp better how hydrology behaves on the catchment scale. Thus, this study examined soil water content variability in the upper 30 cm of the soil on a Mediterranean abandoned terrace in north-east Spain. Using a dataset of high spatial (regular grid of 128 automatic TDR probes at 2.5 m intervals) and temporal (20-min time step) resolution, gathered throughout a 84-day period, the spatio-temporal variability of soil water content at the local scale and the way that different spatio-temporal scales reflect the mean soil water content were investigated. Soil water content spatial variability and its relation to wetness conditions were examined, along with the spatial structuring of the soil water content within the terrace. Then, the ability of single probes and of different combinations of spatial measurements (transects and grids) to provide a good estimate of mean soil water content on the terrace scale was explored by means of temporal stability analyses. Finally, the effect of monitoring frequency on the magnitude of detectable daily soil water content variations was studied. Results showed that soil water content spatial variability followed a bimodal pattern of increasing absolute variability with increasing soil water content. In addition, a linear trend of decreasing soil water content as the distance from the inner part of the terrace increased was identified. Once this trend was subtracted, resulting semi-variograms suggested that the spatial resolution examined was too high to appreciate spatial structuring in the data. Thus, the spatial pattern should be considered as random. Of all the spatial designs tested, the 10 × 10 m mesh grid (9 probes) was considered the most suitable option for a good

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

The correlation of the Cs 137 lateral and radial migration in the Sozh valley soil

International Nuclear Information System (INIS)

Ryabova, L.N; Kuznetsov, V.A.; Glaz, A.S.

2002-01-01

Radiocesium distribution in soils of four geochemical landscapes: eluvial - watershed, transeluvial - terrace slope upper part, transaccumulative - slope lower part, accumulative - flood plain is discussed. Maximum concentration of Cs 137 (2,961...3,280 Bq/kg) was noted in the soil of eluvial landscapes, with a depth of the isotope migration being 26 cm. Its accumulation is associated with the biogeochemical and sorption geochemical barriers. Fe, Ca, Pb, Mn, Ni, Cr and Cu are accumulated simultaneously with Cs 137. The maximum concentration of Cs 137 is confined to the humus horizon of buried soils in the transition landscapes and in the upper part of relict horizons (geochemical barrier), where the Cs 137, Fe, Ca and Mn penetration increases. The lower part of the buried humus horizon is impermeable for Cs 137 migration and partly permeable for Fe, Ca, Mg, that migrate in soluble forms. Cs 137 is accumulated in the humus horizon of buried soils, that occur in the lower parts of slopes and are overlain by light deposits. Radiocesium is accumulated with Al, Fe, Ti, Ca, Mg and trace elements. By the value of a coefficient R9 the buried humus horizon is divided into the upper and lower parts. In the soils of accumulative landscapes radiocesium is accumulated in the sod of the central flood plain lows. In the elevated parts the radial migration is dominant and Cs-137 is accumulated in the humus horizons. Radiocesium is accumulated under the influence of different barriers in the river channel flood plain. A system of watershed - flood plain for Cs 137 is as follows: central flood plain low (6,045...1,955 Bq/kg) > watershed (2,961...3,280) > slope upper part (1,436) > central flood plain elevation (870...4,844), river channel flood plain (381 Bq/kg). Its accumulation in the humus horizons follows the pattern: central flood plain elevation (302...429 Bq/kg) > buried soils (1,055...1,941) > slope upper part (1,628) > river channel flood plain (424) > > watershed (52

Multivariate analysis of the geochemistry and mineralogy of soils along two continental-scale transects in North America

Science.gov (United States)

Drew, L.J.; Grunsky, E.C.; Sutphin, D.M.; Woodruff, L.G.

2010-01-01

Soils collected in 2004 along two North American continental-scale transects were subjected to geochemical and mineralogical analyses. In previous interpretations of these analyses, data were expressed in weight percent and parts per million, and thus were subject to the effect of the constant-sum phenomenon. In a new approach to the data, this effect was removed by using centered log-ratio transformations to 'open' the mineralogical and geochemical arrays. Multivariate analyses, including principal component and linear discriminant analyses, of the centered log-ratio data reveal the effects of soil-forming processes, including soil parent material, weathering, and soil age, at the continental-scale of the data arrays that were not readily apparent in the more conventionally presented data. Linear discriminant analysis of the data arrays indicates that the majority of the soil samples collected along the transects can be more successfully classified with Level 1 ecological regional-scale classification by the soil geochemistry than soil mineralogy. A primary objective of this study is to discover and describe, in a parsimonious way, geochemical processes that are both independent and inter-dependent and manifested through compositional data including estimates of the elements and corresponding mineralogy. ?? 2010.

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. Copyright �

Assessing soil hydrological variability at the cm- to dm-scale using air permeameter measurements

Science.gov (United States)

Beerten, K.; Vandersmissen, N.; Rogiers, B.; Mallants, D.

2012-04-01

Soils and surficial sediments are crucial elements in the hydrological cycle since they are the medium through which infiltrating precipitation percolates to the aquifer. At the same time, soil horizons and shallow stratigraphy may act as hydraulic barriers that can promote runoff or interflow and hamper deep infiltration. For most catchments little is known about the small-scale horizontal and vertical variability of soil hydrological properties. Such information is however required to calculate detailed soil water flow paths and estimate small scale spatial variability in recharge and run-off. We present the results from field air permeameter measurements to assess the small-scale variability of saturated hydraulic conductivity in heterogeneous 2-D soil profiles. To this end, several outcrops in the unsaturated zone (sandy soils with podzolisation) of an interfluve in the Kleine Nete river catchment (Campine area, Northern Belgium) were investigated using a hand-held permeameter. Measurements were done each 10 cm on ~ 2 x 1 m or ~ 2 x 0.5 m grids. The initial results of the measurements (air permeability Kair; millidarcy) are recalculated to saturated hydraulic conductivity (Ks; m/s) using specific transfer functions (Loll et al., 1999; Iversen et al., 2003). Validation of the results is done with independent lab-based constant head Ks measurements. The results show that field based Ks values generally range between 10-3 m/s and 10-7 m/s within one profile, but extremely high values (up to 10-1 m/s) have been measured as well. The lowest values are found in the organic- and silt-rich Bh horizon of podzol soils observed within the profiles (~ 10-6-10-7m/s), while the highest values are observed in overlying dune sands less than 40 cm deep (up to 10-3 m/s with outliers to 10-1 m/s). Comparison of field and laboratory based Ks data reveals there is fair agreement between both methods, apart from several outliers. Scatter plots indicate that almost all points

Multifractal and Singularity Maps of soil surface moisture distribution derived from 2D image analysis.

Science.gov (United States)

Cumbrera, Ramiro; Millán, Humberto; Martín-Sotoca, Juan Jose; Pérez Soto, Luis; Sanchez, Maria Elena; Tarquis, Ana Maria

2016-04-01

Soil moisture distribution usually presents extreme variation at multiple spatial scales. Image analysis could be a useful tool for investigating these spatial patterns of apparent soil moisture at multiple resolutions. The objectives of the present work were (i) to describe the local scaling of apparent soil moisture distribution and (ii) to define apparent soil moisture patterns from vertical planes of Vertisol pit images. Two soil pits (0.70 m long × 0.60 m width × 0.30 m depth) were excavated on a bare Mazic Pellic Vertisol. One was excavated in April/2011 and the other pit was established in May/2011 after 3 days of a moderate rainfall event. Digital photographs were taken from each Vertisol pit using a Kodak™ digital camera. The mean image size was 1600 × 945 pixels with one physical pixel ≈373 μm of the photographed soil pit. For more details see Cumbrera et al. (2012). Geochemical exploration have found with increasingly interests and benefits of using fractal (power-law) models to characterize geochemical distribution, using the concentration-area (C-A) model (Cheng et al., 1994; Cheng, 2012). This method is based on the singularity maps of a measure that at each point define areas with self-similar properties that are shown in power-law relationships in Concentration-Area plots (C-A method). The C-A method together with the singularity map ("Singularity-CA" method) define thresholds that can be applied to segment the map. We have applied it to each soil image. The results show that, in spite of some computational and practical limitations, image analysis of apparent soil moisture patterns could be used to study the dynamical change of soil moisture sampling in agreement with previous results (Millán et al., 2016). REFERENCES Cheng, Q., Agterberg, F. P. and Ballantyne, S. B. (1994). The separation of geochemical anomalies from background by fractal methods. Journal of Geochemical Exploration, 51, 109-130. Cheng, Q. (2012). Singularity theory and

Geochemical and Radiological Characteristics of Harvested Rainwater and Surficial Soil in El-Alamein-Alam El-Rum area, Western Mediterranean Coastal Zone, Egypt

International Nuclear Information System (INIS)

El-Sayed, S.A.; Ramadan, A.A.; Salama, M.H.; Diab, M.

2015-01-01

This study deals with investigating the geochemical and radiological properties of surficial soil and harvested rainwater in Al-Alamein-Alam El-Rum area located in the western Mediterranean coastal zone of Egypt. Forty five water and soil samples were investigated. The surficial soil has heterogeneous physical, chemical and radiological properties and the texture was dominated by sand clayey loam and sandy loam. The salinities were varied from non-saline (EC=1.25 dS/m) to strongly saline (EC=38 dS/m) and the pH ranged from slightly alkaline (7.6) to strongly alkaline (8.95). The major part of soil samples has chemical composition dominated by Na + and Cl - ions and occasionally Mg2 + and SO 4 2 - ions indicating the existence of different chemical facies. The radioactivity level indicated the dominance of 40 K followed by 226 Ra and 232 Th radionuclides and the average radioactivities in the surficial soil samples were 16.59, 11.75, 290.80 and 1.79 Bq/kg for 226 Ra, 232 Th, 40 K and 137 Cs, respectively. The heterogeneity in major ion and radioactivity concentrations were attributed to the variation in chemical and radionuclide compositions of the exposed rocks in the area where the soils are originated. The harvested rainwater is fresh (EC ranged from 0.24 to 0.83 dS/m) and has alkalinity nature varied between slightly alkaline (pH=7.27) and alkaline (pH=8.69). Its chemical composition was prevailed by Na + and HCO 3 - ions and sometimes Ca 2+ and/or Mg 2+ and SO 4 2 - ions reflecting the presence of various hydrochemical facies. It shows the same trend of radionuclide dominance of soils ( 40 K > 226 Ra > 232 Th). The radioactivity concentrations in harvested water samples were 19, 1.01 and 14.0 Bq/l for 226 Ra, 232 Th and 40 K, respectively, while the water samples have 137 Cs concentrations under the detection limit and the water rocks interaction is the main reason causing the variation in major ions and radionuclide concentrations. The obtained chemical and

Study on Characteristics of Soil Elements Bio-availability and Their Interrelationship in Black Soil Area of Jilin Province

Science.gov (United States)

Wang, D. Y.

2015-12-01

Abstract: Based on systematic field investigation and surface soil(0-20cm) sampling in the middle part of Jilin province where the soil type mainly consists of black soil and chernozem, soil total content and bio-available content of Fe, Fe, Ca, Mg, K, P, Cu, Zn, Ni, Cr, B, Cd, As were tested. This paper summarizes the geochemical characteristics of the soil elements and takes the ratio of bio-available content to total content as the bio-availability characteristic of each element in soil and studies the interrelationship between their geochemical characteristics of bio-availability by PCA and correlation analysis. Cd、Cr、Ni、Zn、P、Ca are selected out by PCA due to the similar impact under 4 principal components. And their correlation analysis results indicate: the correlation coefficients between heavy metal elements(Cr, Cd, Zn, Ni) bio-availability are significant positive, i.e., the same spatial variation trends are found between them in study area; the same relationships are also found between the bioavailability of P and 4 heavy metal elements (Cr, Cd, Zn, Ni), the promotion of the bioavailability of heavy metal elements goes with P; However, the correlation coefficients between heavy metal(Cr, Cd, Zn, Ni) bio-availability and Ca are mostly significant negative and the adverse spatial variation trends are found between them. The promotion of the bioavailability of heavy metal elements goes against Ca. Key words: soil geochemistry; soil heavy metals; elements interaction; bio-availability

Soil bacterial and fungal community responses to nitrogen addition across soil depth and microhabitat in an arid shrubland

Science.gov (United States)

Mueller, Rebecca C.; Belnap, Jayne; Kuske, Cheryl R.

2015-01-01

Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature, and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N) deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0–0.5 or 0–10 cm) across the N-amendment gradient (0, 7, and 15 kg ha−1 yr−1). We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

Variability of soil CO2 efflux in a semi-arid grassland in Arizona

Science.gov (United States)

Krishnan, P.; Meyers, T. P.; Heuer, M.

2017-12-01

Soil surface CO2 efflux or soil respiration (RS) is one of the most important components of the global carbon cycle. So it is critical to evaluate the response of soil respiration to environmental conditions to predict how future climate and land cover changes influence the ecosystem carbon balance. Continuous half-hourly measurements of RS were made between the end of March to December 2015 in a semi-arid temperate grassland located on the Audubon Research Ranch in south western Arizona (31.5907N, 110.5104W, elevation 1496 m), USA. This first time measurements of Rs over this site using an automated soil chamber were used to investigate the seasonal and diurnal variation of Rs and its relationship to environmental variables. The mean annual air temperature and precipitation at this site were 16 deg C and 370 mm with more than 60% of the annual precipitation was received during the North American monsoon period (July-September). Following the onset of the monsoon, drastic changes in vegetation growth occured turning the ecosystem to a carbon sink by August. Temporal variability in Rs was closely related to the changes in near surface soil temperature at 2 cm (Ts) and soil water content at 5 cm (θ). Half -hourly Rs varied from nearly 0.1 μmol m-2 s-1 in the winter months to a maximum of 5 μmol m-2 s-1 in the peak growing season in August. During the dry pre-monsoon period (May -June), Rs was relatively low ( 0.0.08 m3 m-3, RS was positively correlated to soil temperature at the 2 cm depth following an exponential relationship. Below this value of θ, RS was largely decoupled from TS dropping to less than half of their maximum values during wet soil conditions. Analysis of daily mean nighttime Rs for the year showed that for periods with θ below the threshold, the sensitivity of RS to temperature were substantially reduced resulting in a Q10 significantly < 2, thereby confirming that RS was less affected by soil temperature under low soil water conditions at this

Some isotopic and geochemical anomalies observed in Mexico prior to large scale earthquakes and volcanic eruptions

International Nuclear Information System (INIS)

Cruz R, S. de la; Armienta, M.A.; Segovia A, N.

1992-05-01

A brief account of some experiences obtained in Mexico, related with the identification of geochemical precursors of volcanic eruptions and isotopic precursors of earthquakes and volcanic activity is given. The cases of three recent events of volcanic activity and one large earthquake are discussed in the context of an active geological environment. The positive results in the identification of some geochemical precursors that helped to evaluate the eruptive potential during two volcanic crises (Tacana 1986 and Colima 1991), and the significant radon-in-soil anomalies observed during a volcanic catastrophic eruption (El Chichon, 1982) and prior to a major earthquake (Michoacan, 1985) are critically analysed. (Author)

Some isotopic and geochemical anomalies observed in Mexico prior to large scale earthquakes and volcanic eruptions

Energy Technology Data Exchange (ETDEWEB)

Cruz R, S. de la; Armienta, M A; Segovia A, N

1992-05-15

A brief account of some experiences obtained in Mexico, related with the identification of geochemical precursors of volcanic eruptions and isotopic precursors of earthquakes and volcanic activity is given. The cases of three recent events of volcanic activity and one large earthquake are discussed in the context of an active geological environment. The positive results in the identification of some geochemical precursors that helped to evaluate the eruptive potential during two volcanic crises (Tacana 1986 and Colima 1991), and the significant radon-in-soil anomalies observed during a volcanic catastrophic eruption (El Chichon, 1982) and prior to a major earthquake (Michoacan, 1985) are critically analysed. (Author)

Local Versus Remote Contributions of Soil Moisture to Near-Surface Temperature Variability

Science.gov (United States)

Koster, R.; Schubert, S.; Wang, H.; Chang, Y.

2018-01-01

Soil moisture variations have a straightforward impact on overlying air temperatures, wetter soils can induce higher evaporative cooling of the soil and thus, locally, cooler temperatures overall. Not known, however, is the degree to which soil moisture variations can affect remote air temperatures through their impact on the atmospheric circulation. In this talk we describe a two-pronged analysis that addresses this question. In the first segment, an extensive ensemble of NASA/GSFC GEOS-5 atmospheric model simulations is analyzed statistically to isolate and quantify the contributions of various soil moisture states, both local and remote, to the variability of air temperature at a given local site. In the second segment, the relevance of the derived statistical relationships is evaluated by applying them to observations-based data. Results from the second segment suggest that the GEOS-5-based relationships do, at least to first order, hold in nature and thus may provide some skill to forecasts of air temperature at subseasonal time scales, at least in certain regions.

Inter-Annual Variability of Soil Moisture Stress Function in the Wheat Field

Science.gov (United States)

Akuraju, V. R.; Ryu, D.; George, B.; Ryu, Y.; Dassanayake, K. B.

2014-12-01

Root-zone soil moisture content is a key variable that controls the exchange of water and energy fluxes between land and atmosphere. In the soil-vegetation-atmosphere transfer (SVAT) schemes, the influence of root-zone soil moisture on evapotranspiration (ET) is parameterized by the soil moisture stress function (SSF). Dependence of actual ET: potential ET (fPET) or evaporative fraction to the root-zone soil moisture via SSF can also be used inversely to estimate root-zone soil moisture when fPET is estimated by remotely sensed land surface states. In this work we present fPET versus available soil water (ASW) in the root zone observed in the experimental farm sites in Victoria, Australia in 2012-2013. In the wheat field site, fPET vs ASW exhibited distinct features for different soil depth, net radiation, and crop growth stages. Interestingly, SSF in the wheat field presented contrasting shapes for two cropping years of 2012 and 2013. We argue that different temporal patterns of rainfall (and resulting soil moisture) during the growing seasons in 2012 and 2013 are responsible for the distinctive SSFs. SSF of the wheat field was simulated by the Agricultural Production Systems sIMulator (APSIM). The APSIM was able to reproduce the observed fPET vs. ASW. We discuss implications of our findings for existing modeling and (inverse) remote sensing approaches relying on SSF and alternative growth-stage-dependent SSFs.

Impact of Subsurface Temperature Variability on Meteorological Variability: An AGCM Study

Science.gov (United States)

Mahanama, S. P.; Koster, R. D.; Liu, P.

2006-05-01

Anomalous atmospheric conditions can lead to surface temperature anomalies, which in turn can lead to temperature anomalies deep in the soil. The deep soil temperature (and the associated ground heat content) has significant memory -- the dissipation of a temperature anomaly may take weeks to months -- and thus deep soil temperature may contribute to the low frequency variability of energy and water variables elsewhere in the system. The memory may even provide some skill to subseasonal and seasonal forecasts. This study uses two long-term AGCM experiments to isolate the contribution of deep soil temperature variability to variability elsewhere in the climate system. The first experiment consists of a standard ensemble of AMIP-type simulations, simulations in which the deep soil temperature variable is allowed to interact with the rest of the system. In the second experiment, the coupling of the deep soil temperature to the rest of the climate system is disabled -- at each grid cell, the local climatological seasonal cycle of deep soil temperature (as determined from the first experiment) is prescribed. By comparing the variability of various atmospheric quantities as generated in the two experiments, we isolate the contribution of interactive deep soil temperature to that variability. The results show that interactive deep soil temperature contributes significantly to surface temperature variability. Interactive deep soil temperature, however, reduces the variability of the hydrological cycle (evaporation and precipitation), largely because it allows for a negative feedback between evaporation and temperature.

Geochemical Fate and Transport of Sildenafil and Vardenafil

Science.gov (United States)

Richter, L.; Boudinot, G.; Vulava, V. M.; Cory, W. C.

2015-12-01

The geochemical fate of pharmaceuticals and their degradation products is a developing environmental field. The geologic, chemical, and biological fate of these pollutants has become very relevant with the increase in human population and the resulting increase in pollutant concentrations in the environment. In this study, we focus on sildenafil (SDF) and vardenafil (VDF), active compounds in Viagra and Levitra, respectively, two commonly used erectile dysfunction drugs. The main objective is to determine the sorption potential and transport behavior of these two compounds in natural soils. Both SDF and VDF are complex organic molecules with multiple amine functional groups in their structures. Two types of natural acidic soils (pH≈4.5), an organic-rich soil (7.6% OM) and clay-rich soil (5.1% clay) were used in this study to determine which soil components influence sorption behavior of both compounds. Sorption isotherms measured using batch reactors were nearly linear, but sorption was stronger in soil that contained higher clay content. Both compounds have multiple pKas due to the amine functional groups, the relevant pKas of SDF are 5.97 and 7.27, and those of VDF's are 4.72 and 6.21. These values indicate that these compounds likely behave as cations in soil suspensions and hence were strongly sorbed to negatively-charged clay minerals present in both soils. The clay composition in both soils is predominantly kaolinite with smaller amount of montmorillonite, both of which have a predominantly negative surface charge. Transport experiments using glass chromatography columns indicated that both compounds were more strongly retarded in the clay-rich soils. Breakthrough curves from the transport experiments were modeled using convection-dispersion transport equations. The organic matter in the soil seemed to play a less dominant role in the geochemistry in this study, but is likely to transform both compounds into derivative compounds as seen in other studies.

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.

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...... (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......, 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...

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Source apportionment of soil heavy metals using robust absolute principal component scores-robust geographically weighted regression (RAPCS-RGWR) receptor model.

Science.gov (United States)

Qu, Mingkai; Wang, Yan; Huang, Biao; Zhao, Yongcun

2018-06-01

The traditional source apportionment models, such as absolute principal component scores-multiple linear regression (APCS-MLR), are usually susceptible to outliers, which may be widely present in the regional geochemical dataset. Furthermore, the models are merely built on variable space instead of geographical space and thus cannot effectively capture the local spatial characteristics of each source contributions. To overcome the limitations, a new receptor model, robust absolute principal component scores-robust geographically weighted regression (RAPCS-RGWR), was proposed based on the traditional APCS-MLR model. Then, the new method was applied to the source apportionment of soil metal elements in a region of Wuhan City, China as a case study. Evaluations revealed that: (i) RAPCS-RGWR model had better performance than APCS-MLR model in the identification of the major sources of soil metal elements, and (ii) source contributions estimated by RAPCS-RGWR model were more close to the true soil metal concentrations than that estimated by APCS-MLR model. It is shown that the proposed RAPCS-RGWR model is a more effective source apportionment method than APCS-MLR (i.e., non-robust and global model) in dealing with the regional geochemical dataset. Copyright © 2018 Elsevier B.V. All rights reserved.

The impact of soil moisture extremes and their spatiotemporal variability on Zambian maize yields

Science.gov (United States)

Zhao, Y.; Estes, L. D.; Vergopolan, N.

2017-12-01

Food security in sub-Saharan Africa is highly sensitive to climate variability. While it is well understood that extreme heat has substantial negative impacts on crop yield, the impacts of precipitation extremes, particularly over large spatial extents, are harder to quantify. There are three primary reasons for this difficulty, which are (1) lack of high quality, high resolution precipitation data, (2) rainfall data provide incomplete information on plant water availability, the variable that most directly affects crop performance, and (3) the type of rainfall extreme that most affects crop yields varies throughout the crop development stage. With respect to the first reason, the spatial and temporal variation of precipitation is much greater than that of temperature, yet the spatial resolution of rainfall data is typically even coarser than it is for temperature, particularly within Africa. Even if there were high-resolution rainfall data, the amount of water available to crops also depends on other physical factors that affect evapotranspiration, which are strongly influenced by heterogeneity in the land surface related to topography, soil properties, and land cover. In this context, soil moisture provides a better measure of crop water availability than rainfall. Furthermore, soil moisture has significantly different influences on crop yield depending on the crop's growth stage. The goal of this study is to understand how the spatiotemporal scales of soil moisture extremes interact with crops, more specifically, the timing and the spatial scales of extreme events like droughts and flooding. In this study, we simulate daily-1km soil moisture using HydroBlocks - a physically based land surface model - and compare it with precipitation and remote sensing derived maize yields between 2000 and 2016 in Zambia. We use a novel combination of the SCYM (scalable satellite-based yield mapper) method with DSSAT crop model, which is a mechanistic model responsive to water

Low-level gamma spectrometry of forest and moor soils from exposed mountain regions in Saxony (Erzgebirge)

Energy Technology Data Exchange (ETDEWEB)

Schleich, N [Technische Univ. Bergakademie Freiberg (Germany). Inst. of Applied Physics; Preusse, W [Technische Univ. Bergakademie Freiberg (Germany). Inst. of Applied Physics; Degering, D [Technische Univ. Bergakademie Freiberg (Germany). Inst. of Applied Physics; Unterricker, S [Technische Univ. Bergakademie Freiberg (Germany). Inst. of Applied Physics

1997-03-01

In soils with distinct organic and mineral horizons, radionuclides (RN) can be used to understand geochemical migration processes. In the study presented here high sensitivity HPGe-detectors with active and passive shielding were employed to determine the low activity levels of various natural, cosmogenic and artificial RN. Soils of a spruce forest and a moor from exposed mountain regions in Saxony (Erzgebirge) were investigated as they provide a good example of layered soil systems with vertical transfer of chemical elements. Different soil horizons were sub-sampled as thin slices and analysed to examine the migration processes at sub-horizon level. The depth distributions of chemically different RN were studied considering the geochemical and pedological soil characteristics of the profiles. (orig.)

Horizontal and vertical variability of soil moisture in savanna ecosystems

Science.gov (United States)

Caylor, K.; D'Odorico, P.; Rodriguez-Iturbe, I.

2004-12-01

Soil moisture is a key hydrological variable that mediates the interactions between climate, soil, and vegetation dynamics in water-limited ecosystems. Because of the importance of water limitation in savannas, a number of theoretical models of tree-grass coexistence have been developed which differ in their underlying assumptions about the ways in which trees and grasses access and use soil moisture. However, clarification of the mechanisms that allow savanna vegetation to persist as a mixture of grasses and trees remains a vexing problem in both hydrological and vegetation science. A particular challenge is the fact that the spatial pattern of vegetation is both a cause and effect of variation in water availability in semiarid ecosystems. At landscape to regional scales, climatic and geologic constraints on soil moisture availability are primary determinants of vegetation structural pattern. However, at local to landscape scales the patchy vegetation structural mosaic serves to redistribute the availability of soil moisture in ways that have important consequences for structural dynamics and community composition. In this regard, the emerging field of ecohydrology is well suited to investigate questions concerning couplings between the patchy structural mosaic of savanna vegetation and the kinds self-organizing dynamics known to exist in other light and nutrient-limited vegetation systems. Here we address the role of patchy vegetation structure through the use of a lumped model of soil moisture dynamics that accounts for the effect of tree canopy on the lateral and vertical distribution of soil moisture. The model includes mechanisms for the drying of the ground surface due to soil evaporation in the sites with no tree cover, and for the lateral water uptake due to root invading areas with no canopy cover located in the proximity of trees. The model, when applied to a series of sites along a rainfall gradient in southern Africa, is able to explain the cover

User manual of the multicompenent variably - saturated flow and transport model HP1

International Nuclear Information System (INIS)

Jacques, D.; Simunek, J.

2005-06-01

This report describes a new comprehensive simulation tool HP1 (HYDRUS1D-PHREEQC) that was obtained by coupling the HYDRUS-1D one-dimensional variably-saturated water flow and solute transport model with the PHREEQC geochemical code. The HP1 code incorporates modules simulating (1) transient water flow in variably-saturated media, (2) transport of multiple components, and (3) mixed equilibrium/kinetic geochemical reactions. The program numerically solves the Richards equation for variably-saturated water flow and advection-dispersion type equations for heat and solute transport. The flow equation incorporates a sink term to account for water uptake by plant roots. The heat transport equation considers transport due to conduction and convection with flowing water. The solute transport equations consider advective-dispersive transport in the liquid phase. The program can simulate a broad range of low-temperature biogeochemical reactions in water, soil and ground water systems including interactions with minerals, gases, exchangers, and sorption surfaces, based on thermodynamic equilibrium, kinetics, or mixed equilibrium-kinetic reactions. The program may be used to analyze water and solute movement in unsaturated, partially saturated, or fully saturated porous media. The flow region may be composed of nonuniform soils or sediments. Flow and transport can occur in the vertical, horizontal, or a generally inclined direction. The water flow part of the model can deal with prescribed head and flux boundaries, boundaries controlled by atmospheric conditions, as well as free drainage boundary conditions. The governing flow and transport equations were solved numerically using Galerkin-type linear finite element schemes. To test the accuracy of the coupling procedures implemented in HP1, simulation results were compared with (i) HYDRUS-1D for transport problems of multiple components subject to sequential first-order decay, (ii) PHREEQC for steady-state flow conditions, and

The distribution of selected elements and minerals in soil of the conterminous United States

Science.gov (United States)

Woodruff, Laurel G.; Cannon, William F.; Smith, David; Solano, Federico

2015-01-01

In 2007, the U.S. Geological Survey initiated a low-density (1 site per 1600 km2, 4857 sites) geochemical and mineralogical survey of soil of the conterminous United States as part of the North American Soil Geochemical Landscapes Project. Three soil samples were collected, if possible, from each site; (1) a sample from a depth of 0 to 5 cm, (2) a composite of the soil A-horizon, and (3) a deeper sample from the soil C-horizon or, if the top of the C-horizon was at a depth greater than 100 cm, from a depth of approximately 80–100 cm. The The major mineralogical components in samples from the soil A- and C-horizons were determined by a quantitative X-ray diffraction method using Rietveld refinement. Sampling ended in 2010 and chemical and mineralogical analyses were completed in May 2013. Maps of the conterminous United States showing predicted element and mineral concentrations were interpolated from actual soil data for each soil sample type by an inverse distance weighted (IDW) technique using ArcGIS software. Regional- and national-scale map patterns for selected elements and minerals apparent in interpolated maps are described here in the context of soil-forming factors and possible human inputs. These patterns can be related to (1) soil parent materials, for example, in the distribution of quartz, (2) climate impacts, for example, in the distribution of feldspar and kaolinite, (3) soil age, for example, in the distribution of carbonate in young glacial deposits, and (4) possible anthropogenic loading of phosphorus (P) and lead (Pb) to surface soil. This new geochemical and mineralogical data set for the conterminous United States represents a major step forward from prior national-scale soil geochemistry data and provides a robust soil data framework for the United States now and into the future.

Spatio-temporal soil moisture variability in Southwest Germany observed with a new monitoring network within the COPS domain

Energy Technology Data Exchange (ETDEWEB)

Krauss, Liane; Kottmeier, Christoph [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Meteorology and Climate Research; Hauck, Christian [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Meteorology and Climate Research; Fribourg Univ. (Switzerland). Dept. of Geosciences

2010-12-15

Within the 'Convective and Orographically-induced Precipitation Study' (COPS) 2007 in Southwest Germany and Northeast France a soil moisture monitoring network was installed. The aim of the network is to identify the interaction between the temporal and spatial variability of the soil moisture field and its influence on the energy balance and the moisture availability in the planetary boundary layer. The network is comprised of a large number of newly developed low-cost soil moisture sensors based on the frequency-domain reflectometry method (FDR). In total 47 soil moisture stations within the COPS domain were each equipped with two to four sensors simultaneously measuring vertical profiles of soil moisture and soil temperature down to 50 cm depth. This contribution describes the soil moisture network, its installation procedure and the calibration of the sensor output signal. Furthermore we discuss the soil texture distribution within the study area and present first analyses of the spatio-temporal soil moisture variability during a 13 month period from June 2007 till June 2008 based on regional differences and site specific properties (altitude and soil texture). Results show that the altitude plays a key role for the overall soil moisture pattern relative to the area mean due to the direct linkage to precipitation patterns. Soil texture controls the vertical soil moisture gradient relative to the near surface soil moisture, as their properties control water storage and drainage characteristics. Both factors significantly influence regional soil moisture patterns in Southwest Germany. (orig.)

Incorporating soil variability in continental soil water modelling: a trade-off between data availability and model complexity

Science.gov (United States)

Peeters, L.; Crosbie, R. S.; Doble, R.; van Dijk, A. I. J. M.

2012-04-01

Developing a continental land surface model implies finding a balance between the complexity in representing the system processes and the availability of reliable data to drive, parameterise and calibrate the model. While a high level of process understanding at plot or catchment scales may warrant a complex model, such data is not available at the continental scale. This data sparsity is especially an issue for the Australian Water Resources Assessment system, AWRA-L, a land-surface model designed to estimate the components of the water balance for the Australian continent. This study focuses on the conceptualization and parametrization of the soil drainage process in AWRA-L. Traditionally soil drainage is simulated with Richards' equation, which is highly non-linear. As general analytic solutions are not available, this equation is usually solved numerically. In AWRA-L however, we introduce a simpler function based on simulation experiments that solve Richards' equation. In the simplified function soil drainage rate, the ratio of drainage (D) over storage (S), decreases exponentially with relative water content. This function is controlled by three parameters, the soil water storage at field capacity (SFC), the drainage fraction at field capacity (KFC) and a drainage function exponent (β). [ ] D- -S- S = KF C exp - β (1 - SFC ) To obtain spatially variable estimates of these three parameters, the Atlas of Australian Soils is used, which lists soil hydraulic properties for each soil profile type. For each soil profile type in the Atlas, 10 days of draining an initially fully saturated, freely draining soil is simulated using HYDRUS-1D. With field capacity defined as the volume of water in the soil after 1 day, the remaining parameters can be obtained by fitting the AWRA-L soil drainage function to the HYDRUS-1D results. This model conceptualisation fully exploits the data available in the Atlas of Australian Soils, without the need to solve the non

Terrigenous sediment provenance from geochemical tracers, south Molokai reef flat, Hawaii

Science.gov (United States)

Takesue, R.K.

2010-01-01

Land-derived runoff is one of the greatest threats to coral-reef health. Identification of runoff sources is an important step in erosion mitigation efforts. A geochemical sediment provenance study was done in uplands and across the adjacent fringing reef on the southeast shore of Molokai, Hawaii, to determine whether sediment runoff originated from hillsides or gulches. Source-region identification was based on geochemical differences between alkalic basalt, which outcrops on hillsides, and tholeiitic basalt, which outcrops in gulches. In Kawela watershed, copper to iron ratios (Cu/Fe) were distinct in hillside soil versus gulch sediment and suggest that hillside erosion is the predominant mechanism of sediment delivery to the nearshore. This suggests that runoff-mitigation efforts should take steps to reduce hillside erosion. Cadmium to thorium ratios (Cd/Th) in nearshore sediment suggest that there is a high-Cd source of runoff east of Kamalo Gulch. This compositional difference is consistent with the predominance of tholeiitic basalt on the eastern end of Molokai.

Variability in soil CO2 production and surface CO2 efflux across riparian-hillslope transitions

Science.gov (United States)

Vincent Jerald. Pacific

2007-01-01

The spatial and temporal controls on soil CO2 production and surface CO2 efflux have been identified as an outstanding gap in our understanding of carbon cycling. I investigated both the spatial and temporal variability of soil CO2 concentrations and surface CO2 efflux across eight topographically distinct riparian-hillslope transitions in the ~300 ha subalpine upper-...

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.

Trace element distribution in geochemical environment of the island Krk and its influence on the local population

International Nuclear Information System (INIS)

Kutle, A.; Orescanin, V.; Obhodas, J.; Valkovic, V.

2004-01-01

Samples of soil, plant material and water collected on the Croatian island Krk in northern Adriatic sea were analyzed for a number of elements (Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Pb) by using energy dispersive X-ray fluorescence (EDXRF) as an analytical tool. Some of these data have been previously used to produce geochemical map of the island. In addition, trace element contents of hair from children, attending elementary and secondary schools, has been investigated using the same analytical method for Mg, S, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Hg and Pb elements. Concentrations of the twelve elements and nine variables from the questionnaire, i.e., age, sex, living place, transportation, medication, hair colour, hair type, type of shampoo used and hair treatment, were considered in the statistical analysis. The observed differences for the seven island's communes have also been discussed. (author)

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

International Nuclear Information System (INIS)

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

2015-01-01

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. - Highlights: • The SOC stocks across 30 and 100 cm depth were 3.28 and 7.32 kg C m −2 , respectively. • SOC stocks were 34 and 16%, respectively

Generalization of some results of a vertical radionuclide migration study in soils of 30-km zone

International Nuclear Information System (INIS)

Ziborov, A.M.; Sadol'ko, I.V.; Sushchik, Yu.Ya.; Tikhanov, Eh.K.; Proskuryakov, A.G.; Kuz'michev, V.N.; Shcheglov, A.I.

1992-01-01

Results of radionuclide distribution study in a vertical profile of soils are presented under different landscape geochemical conditions in 1989-1991. It is ascertained that radionuclide migration process in geochemical profile of soils of 30-km zone is in early stage of development. More than 90% of radioactivity concentrates in the upper 5-10 cm layer whereas measurable radioactivity fixes at a depth up to 1 m. The process of deepening of radioactivity reserve center takes place in the surface soil layer. Now it equals 1,5-3 cm. Peculiarities of the vertical radionuclide distribution haven't brightly pronounced character depending on soil types and are at the formation stage. 12 figs.; 2 tabs

Soil bacterial and fungal community responses to nitrogen addition across soil depths and microhabitat in an arid shrubland

Directory of Open Access Journals (Sweden)

Rebecca C Mueller

2015-09-01

Full Text Available Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0-0.5 cm or 0-10 cm across the N-amendment gradient (0, 7 and 15 kg ha-1 yr-1. We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

The two-layer geochemical structure of modern biogeochemical provinces and its significance for spatially adequate ecological evaluations and decisions

Science.gov (United States)

Korobova, Elena; Romanov, Sergey

2014-05-01

Contamination of the environment has reached such a scale that ecogeochemical situation in any area can be interpreted now as a result of the combined effect of natural and anthropogenic factors. The areas that appear uncomfortable for a long stay can have natural and anthropogenic genesis, but the spatial structure of such biogeochemical provinces is in any case formed of a combination of natural and technogenic fields of chemical elements. Features of structural organization and the difference in factors and specific time of their formation allow their separation on one hand and help in identification of areas with different ecological risks due to overlay of the two structures on the other. Geochemistry of soil cover reflects the long-term result of the naturally balanced biogeochemical cycles, therefore the soil geochemical maps of the undisturbed areas may serve the basis for evaluation of the natural geochemical background with due regard to the main factors of geochemical differentiation in biosphere. Purposeful and incidental technogenic concentrations and dispersions of chemical elements of specific (mainly mono- or polycentric) structure are also fixed in soils that serve as secondary sources of contamination of the vegetation cover and local food chains. Overlay of the two structures forms specific heterogeneity of modern biogeochemical provinces with different risk for particular groups of people, animals and plants adapted to specific natural geochemical background within particular concentration interval. The developed approach is believed to be helpful for biogeochemical regionalizing of modern biosphere (noosphere) and for spatially adequate ecogeochemical evaluation of the environment and landuse decisions. It allows production of a set of applied geochemical maps such as: 1) health risk due to chemical elements deficiency and technogenic contamination accounting of possible additive effects; 2) adequate soil fertilization and melioration with due

Geochemical distribution of polycyclic aromatic hydrocarbons in soils and sediments of El-Tabbin, Egypt.

Science.gov (United States)

Havelcová, Martina; Melegy, Ahmed; Rapant, Stanislav

2014-01-01

Polycyclic aromatic hydrocarbons (PAHs) were extracted from 30 samples (24 soils and 6 stream sediments) collected in El-Tabbin area in the southern part of Greater Cairo, Egypt. Isopleth maps of PAHs clarified the regional variability and identified the most affected regions in the area suffering from high pollution. The total PAH concentrations were 53.4-5558.0 ng g(-1) in the sample extracts. The highest values were found in a soil sample near a coke factory, with the highest concentration of single PAHs, which were 1064.8 ng g(-1) of fluoranthene and 1286.4 ng g(-1) of phenanthrene. The calculated ratios and indexes allowed to elucidate origin of the organic compounds and to identify emission sources. The overall molecular patterns are signatures of pyrolysis of fossil fuels and biomass. Petrogenic contamination was recognised in the sediment samples due to petroleum products deliveries from ships. Also perylene was prominent especially in samples of the River Nile sediments as a diagenetic product of fungi. Other detailed information on petrogenic sources was provided by analysis of alkanes and calculation of alkane ratios. Copyright © 2013 Elsevier Ltd. All rights reserved.

Coupled geochemical and solute transport code development

International Nuclear Information System (INIS)

Morrey, J.R.; Hostetler, C.J.

1985-01-01

A number of coupled geochemical hydrologic codes have been reported in the literature. Some of these codes have directly coupled the source-sink term to the solute transport equation. The current consensus seems to be that directly coupling hydrologic transport and chemical models through a series of interdependent differential equations is not feasible for multicomponent problems with complex geochemical processes (e.g., precipitation/dissolution reactions). A two-step process appears to be the required method of coupling codes for problems where a large suite of chemical reactions must be monitored. Two-step structure requires that the source-sink term in the transport equation is supplied by a geochemical code rather than by an analytical expression. We have developed a one-dimensional two-step coupled model designed to calculate relatively complex geochemical equilibria (CTM1D). Our geochemical module implements a Newton-Raphson algorithm to solve heterogeneous geochemical equilibria, involving up to 40 chemical components and 400 aqueous species. The geochemical module was designed to be efficient and compact. A revised version of the MINTEQ Code is used as a parent geochemical code

Phosphorus sorption in relation to soil grain size and geochemical ...

African Journals Online (AJOL)

By using stepwise regression, the combination of Al, Fe, clay and Ca predicted more than 94% of the variation in the P sorption capacity of soils samples from Simiyu and Kagera basins. These four soil properties, which are strongly related to P sorption, could therefore be used as quick tests for predicting the P sorption ...

Spatial variability and response of soil organic carbon stocks to land abandonment and erosion in mountainous drylands (Invited)

Science.gov (United States)

De Baets, S. L.; Meersmans, J.; Vanacker, V.; Quine, T. A.; van oost, K.

2013-12-01

This research focuses on understanding the impact of human activities on C dynamics in a mountainous and semi-arid environment. Despite the low C status of drylands, soil organic carbon (SOC) is the largest C pool in these systems and hence possess a large restoration capacity. Still, regional estimates of SOC stocks and insights in their determining factors are lacking. This study therefore aims 1) to interpret the variability of soil organic carbon in relation to key soil, topographical and land use variables and 2) to quantify the effects of land regeneration following abandonment on SOC stocks. Soil profiles were taken in the Sierra de los Filabres (SE Spain) in different land units along geomorphic and degradation gradients. SOC contents were modelled using recovery period, soil and topographical variables. Sample depth, topographical position, altitude, recovery period and stone content are identified as the main factors for predicting SOC concentrations. SOC stocks in 1 m depth of soil vary between 3.16 and 76.44 t ha-1. Recovery period (years since abandonment), topographical position and altitude were used to predict and map SOC stocks in the top 0.2 m. The results show that C accumulates fast during the first 10-50 years following abandonment, whereafter the stocks evolve towards a steady state level. The erosion zones in the study area demonstrate a higher potential to increase their SOC stocks when abandoned. Deposition zones have higher SOC stocks, although their C accumulation rate is lower compared to erosion dominated landscapes in the first 10-50 years following abandonment. Therefore, full understanding of the C sequestration potential of land use change in areas of complex topography requires knowledge of spatial variability in soil properties and in particular SOC.

Geochemical and petrographic studies and the relationships to durability and leach resistance of vitrified products from the in situ vitrification process

International Nuclear Information System (INIS)

Timmons, D.M.; Thompson, L.E.

1996-01-01

Soil and sludge contaminated with hazardous and radioactive materials from sites in the United States and Australia were vitrified using in situ vitrification. Some of the resulting products were subjected to detailed geochemical, leach and durability testing using a variety of analytical techniques. The leach resistance and durability performance was compared to that of vitrified high level waste with borosilicate composition. Particular attention was given to crystallization behavior, the effects of crystallization on residual melt chemistry and how crystallization influences the behavior of contaminant ions. The results of this work show that the vitrified material studied has superior chemical durability and leach resistance relative to typical borosilicate waste glasses. Crystallization behavior was variable depending upon melt chemistry and cooling history. Crystallization was not observed to adversely affect chemical durability or leach resistance

Geochemical features of the elemental composition of meadowsweet (Filipendula ulmaria (L).Maxim) in Kemerovo Oblast

Science.gov (United States)

Zhdanov, V. A.; Sobolev, I. S.; Baranovskaya, N. V.; Kolesnikova, E. A.; Chernenkaya, E. V.; Yalaltdinova, A. R.

2016-09-01

Biogeochemical sampling of the aboveground part of meadowsweet (Fillipendula Ulmaria (L). Maxim) allowed us to study ecological and geochemical features of 10 regions in Kemerovo Oblast, including both natural and man-made landscapes. The content of 55 elements in the plant is determined by ICP-MS. Statistical analysis of the results allowed us to establish the effect of the soil mineral composition and the mining region specificity on the elemental composition of meadowsweet, to reveal significant positive correlations of the elements and to establish a statistically significant difference in the studied areas on the basis of the content of some elements. Sample reference to one of the clusters, followed by an assessment of their geochemical features is determined by the K-average method.

Geochemical Investigations of Groundwater Stability

International Nuclear Information System (INIS)

Bath, Adrian

2006-05-01

The report describes geochemical parameters and methods that provide information about the hydrodynamic stability of groundwaters in low permeability fractured rocks that are potential hosts for radioactive waste repositories. Hydrodynamic stability describes the propensity for changes in groundwater flows over long timescales, in terms of flow rates and flow directions. Hydrodynamic changes may also cause changes in water compositions, but the related issue of geochemical stability of a potential repository host rock system is outside the scope of this report. The main approaches to assessing groundwater stability are numerical modelling, measurement and interpretation of geochemical indicators in groundwater compositions, and analyses and interpretations of secondary minerals and fluid inclusions in these minerals. This report covers the latter two topics, with emphasis on geochemical indicators. The extent to which palaeohydrogeology and geochemical stability indicators have been used in past safety cases is reviewed. It has been very variable, both in terms of the scenarios considered, the stability indicators considered and the extent to which the information was explicitly or implicitly used in assessing FEPs and scenarios in the safety cases. Geochemical indicators of hydrodynamic stability provide various categories of information that are of hydrogeological relevance. Information about groundwater mixing, flows and water sources is potentially provided by the total salinity of groundwaters, their contents of specific non-reactive solutes (principally chloride) and possibly of other solutes, the stable isotopic ratio of water, and certain characteristics of secondary minerals and fluid inclusions. Information pertaining directly to groundwater ages and the timing of water and solute movements is provided by isotopic systems including tritium, carbon-14, chlorine-36, stable oxygen and hydrogen isotopes, uranium isotopes and dissolved mobile gases in

Mercury in urban soils: A comparison of local spatial variability in six European cities

International Nuclear Information System (INIS)

Rodrigues, S.; Pereira, M.E.; Duarte, A.C.; Ajmone-Marsan, F.; Davidson, C.M.; Grcman, H.; Hossack, I.; Hursthouse, A.S.; Ljung, K.; Martini, C.; Otabbong, E.; Reinoso, R.; Ruiz-Cortes, E.; Urquhart, G.J.; Vrscaj, B.

2006-01-01

The objective of this study was to quantify and assess for the first time the variability of total mercury in urban soils at a European level, using a systematic sampling strategy and a common methodology. We report results from a comparison between soil samples from Aveiro (Portugal), Glasgow (Scotland), Ljubljana (Slovenia), Sevilla (Spain), Torino (Italy) and Uppsala (Sweden). At least 25 sampling points (in about 4-5 ha) from a park in each city were sampled at two depths (0-10 and 10-20 cm). Total mercury was determined by pyrolysis atomic absorption spectrometry with gold amalgamation. The quality of results was monitored using certified reference materials (BCR 142R and BCR 141R). Measured total mercury contents varied from 0.015 to 6.3 mg kg -1 . The lowest median values were found in Aveiro, for both surface (0-10 cm) and sub-surface (10-20 cm) samples (0.055 and 0.054 mg kg -1 , respectively). The highest median mercury contents in soil samples were found in samples from Glasgow (1.2 and 1.3 mg kg -1 , for surface and sub-surface samples, respectively). High variability of mercury concentrations was observed, both within each park and between cities. This variability reflecting contributions from natural background, previous anthropogenic activities and differences in the ages of cities and land use, local environmental conditions as well as the influence of their location within the urban area. Short-range variability of mercury concentrations was found to be up to an order of magnitude over the distance of only a few 10 m

phosphorus sorption in relation to soil grain size and geochemical

African Journals Online (AJOL)

Mgina

use and landscape in the Simiyu and Kagera River basins were determined using the Langmuir ... determination of key soil properties that .... deviation) of selected soil properties in the Simiyu (S) and Kagera (K) basins. Particle size. % dry weight. Sample. %. Sand. % Silt. % Clay. pH. Al2O3. Fe2O3. CaO. Na2O. K2O. S1.

Establishing nursery estuary otolith geochemical tags for Sea Bass (Dicentrarchus labrax): Is temporal stability estuary dependent?

Science.gov (United States)

Ryan, Diarmuid; Wögerbauer, Ciara; Roche, William

2016-12-01

The ability to determine connectivity between juveniles in nursery estuaries and adult populations is an important tool for fisheries management. Otoliths of juvenile fish contain geochemical tags, which reflect the variation in estuarine elemental chemistry, and allow discrimination of their natal and/or nursery estuaries. These tags can be used to investigate connectivity patterns between juveniles and adults. However, inter-annual variability of geochemical tags may limit the accuracy of nursery origin determinations. Otolith elemental composition was used to assign a single cohort of 0-group sea bass Dicentrarchus labrax to their nursery estuary thus establishing an initial baseline for stocks in waters around Ireland. Using a standard LDFA model, high classification accuracies to nursery sites (80-88%) were obtained. Temporal stability of otolith geochemical tags was also investigated to assess if annual sampling is required for connectivity studies. Geochemical tag stability was found to be strongly estuary dependent.

Electrodialytic Remediation of Different Heavy Metal-Polluted Soils in Suspension

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Jensen, Pernille Erland; Kirkelund, Gunvor Marie

2013-01-01

Electrokinetic remediation of heavy metal-polluted soil faces different challenges in relation to implementation. One challenge is to cope with the nonlinear and transient geochemical changes in the soil and another is to increase the remediation rate. Both these challenges are met when treating...... the soil in a suspension in an electrodialytic cell. The soil suspension is stirred and uniform during treatment. Previously, it has been shown that a faster remediation can be obtained when remediating a stirred soil suspension compared to a stationary water saturated soil (all other parameters the same...

CO and H2 uptake and emissions by soil: variability of fluxes and their isotopic signatures

Science.gov (United States)

Popa, Maria Elena; Chen, Qianjie; Ferrero Lopez, Noelia; Röckmann, Thomas

2017-04-01

In order to study the uptake and release of H2 and CO by soil, we performed long term, high frequency measurements with an automatic soil chamber at two sites in the Netherlands (Cabauw - grassland, and Speuld - forest). The measurements were performed over different seasons and cover in total a cumulated interval of about one year. These measurements allow determining separately, for each species, the two distinct fluxes i.e. uptake and release, and investigating their temporal variability and dependencies on environmental variables. Additional experiments were performed for determining the isotopic signatures of the H2 and CO uptake and release by soil. Flask samples were filled from the soil chamber, and then analyzed in the laboratory for the stable isotopic composition of H2 (δD) and CO (δ13C and δ18O). We find that both uptake and release are present at all times, regardless of the direction of the net flux. The emissions are significant for both species and at Cabauw, there are times and places where emissions outweigh the soil uptake. For each species, the two fluxes have different behavior and dependence on external variables, which indicates that they have different origins. The isotope results also support that, for both H2 and CO, uptake and emission occur simultaneously. We were able to determine separately the isotopic effects of the two fluxes. For both H2 and CO, soil uptake is associated with a small positive fractionation (the lighter molecule is taken up faster). The soil uptake fractionation (α = kheavy/klight) was 0.945 ± 0.004 for H2; for CO, the fractionation was 0.992 for 13C and 0.985 for 18O. The isotopic composition of the H2 emitted from the grassland was -530 ± 40 ‰, less depleted that what is expected from the isotopic equilibrium of H2 with water. For CO, the isotopic composition of the soil emission is depleted in 13C compared to atmospheric CO, and lower than the average isotopic composition of plant or soil organic matter.

Impact of Hydrologic and Micro-topographic Variabilities on Spatial Distribution of Mean Soil-Nitrogen Age

Science.gov (United States)

Woo, D.; Kumar, P.

2015-12-01

Excess reactive nitrogen in soils of intensively managed agricultural fields causes adverse environmental impact, and continues to remain a global concern. Many novel strategies have been developed to provide better management practices and, yet, the problem remains unresolved. The objective of this study is to develop a 3-dimensional model to characterize the spatially distributed ``age" of soil-nitrogen (nitrate and ammonia-ammonium) across a watershed. We use the general theory of age, which provides an assessment of the elapsed time since nitrogen is introduced into the soil system. Micro-topographic variability incorporates heterogeneity of nutrient transformations and transport associated with topographic depressions that form temporary ponds and produce prolonged periods of anoxic conditions, and roadside agricultural ditches that support rapid surface movement. This modeling effort utilizes 1-m Light Detection and Ranging (LiDAR) data. We find a significant correlation between hydrologic variability and mean nitrate age that enables assessment of preferential flow paths of nitrate leaching. The estimation of the mean nitrogen age can thus serve as a tool to disentangle complex nitrogen dynamics by providing the analysis of the time scales of soil-nitrogen transformation and transport processes without introducing additional parameters.

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.

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. ...

Use of geophysical survey as a predictor of the edaphic properties variability in soils used for livestock production

Directory of Open Access Journals (Sweden)

Nahuel R. Peralta

2015-12-01

Full Text Available The spatial variability in soils used for livestock production (i.e. Natraquoll and Natraqualf at farm and paddock scale is usually very high. Understanding this spatial variation within a field is the first step for site-specific crop management. For this reason, we evaluated whether apparent electrical conductivity (ECa, a widely used proximal soil sensing technology, is a potential estimator of the edaphic variability in these types of soils. ECa and elevation data were collected in a paddock of 16 ha. Elevation was negatively associated with ECa. Geo-referenced soil samples were collected and analyzed for soil organic matter (OM content, pH, the saturation extract electrical conductivity (ECext, available phosphorous (P, and anaerobically incubated Nitrogen (Nan. Relationships between soil properties and ECa were analyzed using regression analysis, principal components analysis (PCA, and stepwise regression. Principal components (PC and the PC-stepwise were used to determine which soil properties have an important influence on ECa. In this experiment elevation was negatively associated with ECa. The data showed that pH, OM, and ECext exhibited a high correlation with ECa (R2=0.76; 0.70 and 0.65, respectively. Whereas P and Nan showed a lower correlation (R2=0.54 and 0.11 respectively. The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1. Therefore, ECext, pH and OM were considered key latent variables because they substantially influence the relationship between the PC1 and the ECa (loading factors>0.4. Results showed that ECa is associated with the spatial distribution of some important soil properties. Thus, ECa can be used as a support tool to implement site-specific management in soils for livestock use.

Use of geophysical survey as a predictor of the edaphic properties variability in soils used for livestock production

Energy Technology Data Exchange (ETDEWEB)

Peralta, N.R.; Cicore, P.L.; Marino, M.A.; Marques da Silva, J. R.; Costa, J.L.

2015-07-01

The spatial variability in soils used for livestock production (i.e. Natraquoll and Natraqualf) at farm and paddock scale is usually very high. Understanding this spatial variation within a field is the first step for site-specific crop management. For this reason, we evaluated whether apparent electrical conductivity (ECa), a widely used proximal soil sensing technology, is a potential estimator of the edaphic variability in these types of soils. ECa and elevation data were collected in a paddock of 16 ha. Elevation was negatively associated with ECa. Geo-referenced soil samples were collected and analyzed for soil organic matter (OM) content, pH, the saturation extract electrical conductivity (ECext), available phosphorous (P), and anaerobically incubated Nitrogen (Nan). Relationships between soil properties and ECa were analyzed using regression analysis, principal components analysis (PCA), and stepwise regression. Principal components (PC) and the PC-stepwise were used to determine which soil properties have an important influence on ECa. In this experiment elevation was negatively associated with ECa. The data showed that pH, OM, and ECext exhibited a high correlation with ECa (R2=0.76; 0.70 and 0.65, respectively). Whereas P and Nan showed a lower correlation (R2=0.54 and 0.11 respectively). The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1. Therefore, ECext, pH and OM were considered key latent variables because they substantially influence the relationship between the PC1 and the ECa (loading factors>0.4). Results showed that ECa is associated with the spatial distribution of some important soil properties. Thus, ECa can be used as a support tool to implement site-specific management in soils for livestock use. (Author)

Relationship Between Physical Properties and Magnetism of Soils From Various Pedoenvironments

Science.gov (United States)

Jordanova, N.; Jordanova, D.; Todorova, D.; Hirt, A.; Petrov, P.

2009-05-01

Characterization of soils with respect to their fertility, sustainable use and conservation require extensive, time- consuming and costly analyses. Establishment of well defined relationships between certain physical, geochemical and magnetic parameters would be useful tool in pedometrics, giving opportunity to carry out large scale studies on soil properties in more economically effective and fast way. Interdisciplinary analysis of 15 type soils from different pedoenvironments (oxidative, water-logged, salty, etc.) includes extensive magnetic measurements (magnetic susceptibility, anhysteretic (ARM) and isothermal (IRM) remanences, hysteresis parameters); determination of a set of physical characteristics (grain size fractions, pH) and geochemical analyses (total Fe content, oxalate- and dithionite-soluble Fe). Empirical linear relationship is found between soil reaction (pH) and magnetic susceptibility for aerobic soils, and negative relationship between pH and ARM for water-logged soils. Different type soils, showing magnetic enhancement along the solum, show higher ARM intensity with increasing percent of the clay fraction. This feature most probably is related to the fact that pedogenic ferrimagnetic minerals are strongly linked to clay fraction. The absence of such correlation for soils, affected by water-logging conditions suggests prevailing role of amorphous phases and antiferromagnetic Fe oxides in magnetic mineralogy. The role of pedogenic factors for particular behavior of other magnetic parameters will be discussed.

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.

Geochemical and radiometric surveys of Sabkhet Al-Jaboul area by investigating trace elements, radon measurements and gamma spectrometry

International Nuclear Information System (INIS)

Jubeli, Y.; Aissa, M.; Al-Hilal, M.

1999-08-01

Radiometric and geochemical surveys were carried out over various geological formations in Sabkhet Al-Jaboul and its surrounding environment for evaluating the levels of radioactivity in the area. Therefore, a number of exploration techniques were used in this study such as gamma ray spectrometry, geochemical exploration and soil radon measurements. Although the results of this survey indicate some slight variations of which might be useful to distinguish between various lithological units, most of the obtained data do not reveal any significant radiometric values that could be considered important from the exploration point of view. However, these data were successfully handled to estimate the natural background of radioactivity throughout the geological units of the region. The results also showed the importance of the sedimentary transition contact zone where the continental fresh and salt favourable geochemical environment for uranium precipitation when other fundamental geological requirements for developing such concentrations are available. (author)

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

OpenAIRE

Kizilkaya, Ridvan; Aşkin, Tayfun

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...

Spatial variability of isoproturon mineralizing activity within an agricultural field: Geostatistical analysis of simple physicochemical and microbiological soil parameters

Energy Technology Data Exchange (ETDEWEB)

El Sebai, T. [UMR Microbiologie et Geochimie des Sols, INRA/CMSE, 17 Rue Sully, BP 86510, 21065 Dijon Cedex (France); Lagacherie, B. [UMR Microbiologie et Geochimie des Sols, INRA/CMSE, 17 Rue Sully, BP 86510, 21065 Dijon Cedex (France); Soulas, G. [UMR Microbiologie et Geochimie des Sols, INRA/CMSE, 17 Rue Sully, BP 86510, 21065 Dijon Cedex (France); Martin-Laurent, F. [UMR Microbiologie et Geochimie des Sols, INRA/CMSE, 17 Rue Sully, BP 86510, 21065 Dijon Cedex (France)]. E-mail: fmartin@dijon.inra.fr

2007-02-15

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. - In field spatial variation of isoproturon mineralization mainly results from the spatial heterogeneity of soil pH and microbial C biomass.

Spatial variability of isoproturon mineralizing activity within an agricultural field: Geostatistical analysis of simple physicochemical and microbiological soil parameters

International Nuclear Information System (INIS)

El Sebai, T.; Lagacherie, B.; Soulas, G.; Martin-Laurent, F.

2007-01-01

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. - In field spatial variation of isoproturon mineralization mainly results from the spatial heterogeneity of soil pH and microbial C biomass

Water table fluctuations and soil biogeochemistry: An experimental approach using an automated soil column system

Science.gov (United States)

Rezanezhad, F.; Couture, R.-M.; Kovac, R.; O'Connell, D.; Van Cappellen, P.

2014-02-01

Water table fluctuations significantly affect the biological and geochemical functioning of soils. Here, we introduce an automated soil column system in which the water table regime is imposed using a computer-controlled, multi-channel pump connected to a hydrostatic equilibrium reservoir and a water storage reservoir. The potential of this new system is illustrated by comparing results from two columns filled with 45 cm of the same homogenized riparian soil. In one soil column the water table remained constant at -20 cm below the soil surface, while in the other the water table oscillated between the soil surface and the bottom of the column, at a rate of 4.8 cm d-1. The experiment ran for 75 days at room temperature (25 ± 2 °C). Micro-sensors installed at -10 and -30 cm below the soil surface in the stable water table column recorded constant redox potentials on the order of 600 and -200 mV, respectively. In the fluctuating water table column, redox potentials at the same depths oscillated between oxidizing (∼700 mV) and reducing (∼-100 mV) conditions. Pore waters collected periodically and solid-phase analyses on core material obtained at the end of the experiment highlighted striking geochemical differences between the two columns, especially in the time series and depth distributions of Fe, Mn, K, P and S. Soil CO2 emissions derived from headspace gas analysis exhibited periodic variations in the fluctuating water table column, with peak values during water table drawdown. Transient redox conditions caused by the water table fluctuations enhanced microbial oxidation of soil organic matter, resulting in a pronounced depletion of particulate organic carbon in the midsection of the fluctuating water table column. Denaturing Gradient Gel Electrophoresis (DGGE) revealed the onset of differentiation of the bacterial communities in the upper (oxidizing) and lower (reducing) soil sections, although no systematic differences in microbial community structure

Geochemical and microbiological study in soils of southern Uruguay

International Nuclear Information System (INIS)

Pianzzola, M.; De Souza, S.; Soubes, M.; Goso Aguilar, C.

2009-01-01

The sulphate reducing bacteria (S RB) constitute a diverse group of anaerobic prokaryotes that carry out the dissimilarity sulphate reduction of sulphur compounds like sulphate, sulphite, tio sulphate, and sulphide to hydrogen sulphide. Although B SR are anaerobic, some genre tolerate oxygen and some others, at low concentrations, can res pirate Fe+ 3 or oxygen, using hydrogen as electron donor. Several industries, including oil and natural gas processing and transporting plants, have been affected by their metabolic activity and the fundamental cause is the production of H S, corrosive and toxic. It damages the pumping equipment, tanks, and 2 pipes. On the other hand, the generated sulphide affects human health and causes security and environmental problems producing severe economic losses. Given the ecological and economic importance of the S RB this study attempts of its presence in soils of different characteristics from southern Uruguay. Although in the last years its knowledge at molecular level has been increased, there is still lack of information so as to be able to control all the effects produced by its metabolic activity. The objective of our work is to determine the degree of diversity of these bacteria in our soils and to know the bio corrosion potential of them. As a first step we have collected soil samples with different characteristics, having determined its p H, humidity, content of chloride and sulphates as well as the presence of S RB. Although the main obstacle to understand its ecology and diversity is the incapacity to cultivate many of the microorganisms that come from environmental samples, this difficulty can directly be avoided by means of the use of molecular techniques that allow the study of the microorganisms present or their genes. In this work we correlate the detection of sulphate reducing bacteria by classic and molecular methods in the different soils studied

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

Soil structure interaction model and variability of parameters in seismic analysis of nuclear island connected building

International Nuclear Information System (INIS)

Subramanian, K.V.; Palekar, S.M.; Bavare, M.S.; Mapari, H.A.; Patel, S.C.; Pillai, C.S.

2005-01-01

This paper provides salient features of the Soil Structure Interaction analysis of Nuclear Island Connected Building (NICB). The dynamic analysis of NICB is performed on a full 3D model accounting for the probable variation in the stiffness of the founding medium. A range analyses was performed to establish the effect of variability of subgrade parameters on the results of seismic analyses of NICB. This paper presents details of various analyses with respect to the subgrade model, uncertainties in subgrade properties, results of seismic analyses and a study of effect of the variability of parameters on the results of these analyses. The results of this study indicate that the variability of soil parameters beyond a certain value of shear wave velocity does not influence the response and in fact the response marginally diminishes. (authors)

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.

A generalized model for transport of contaminants in soil by electric fields.

Science.gov (United States)

Paz-Garcia, Juan Manuel; Baek, Kitae; Alshawabkeh, Iyad D; Alshawabkeh, Akram N

2012-01-01

A generalized model applicable to soils contaminated with multiple species under enhanced boundary conditions during treatment by electric fields is presented. The partial differential equations describing species transport are developed by applying the law of mass conservation to their fluxes. Transport, due to migration, advection and diffusion, of each aqueous component and complex species are combined to produce one partial differential equation that describes transport of the total analytical concentrations of component species which are the primary dependent variables. This transport couples with geochemical reactions such as aqueous equilibrium, sorption, precipitation and dissolution. The enhanced model is used to simulate electrokinetic cleanup of lead and copper contaminants at an Army Firing Range. Acid enhancement is achieved by the use of adipic acid to neutralize the basic front produced for the cathode electrochemical reaction. The model is able to simulate enhanced application of the process by modifying the boundary conditions. The model showed that kinetics of geochemical reactions, such as metals dissolution/leaching and redox reactions, may be significant for realistic prediction of enhanced electrokinetic extraction of metals in real-world applications.

Coastal Aquifer Contamination and Geochemical Processes Evaluation in Tugela Catchment, South Africa—Geochemical and Statistical Approaches

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Badana Ntanganedzeni

2018-05-01

Full Text Available Assessment of groundwater quality, contamination sources and geochemical processes in the coastal aquifer of Tugela Catchment, South Africa were carried out by the geochemical and statistical approach using major ion chemistry of 36 groundwater samples. Results suggest that the spatial distribution pattern of EC, TDS, Na, Mg, Cl and SO4 are homogenous and elevated concentrations are observed in the wells in the coastal region and few wells near the Tugela River. Wells located far from the coast are enriched by Ca, HCO3 and CO3. Durov diagrams, Gibbs plots, ionic ratios, chloro alkaline indices (CAI1 and CAI2 and correlation analysis imply that groundwater chemistry in the coastal aquifer of Tugela Catchment is regulated by the ion exchange, mineral dissolution, saline sources, and wastewater infiltration from domestic sewage; septic tank leakage and irrigation return flow. Principle component analysis also ensured the role of saline and anthropogenic sources and carbonates dissolution on water chemistry. Spatial distributions of factor score also justify the above predictions. Groundwater suitability assessment indicates that around 80% and 90% of wells exceeded the drinking water standards recommended by the WHO and South African drinking water standards (SAWQG, respectively. Based on SAR, RSC, PI, and MH classifications, most of the wells are suitable for irrigation in the study region. USSL classification suggests that groundwater is suitable for coarse-textured soils and salt-tolerant crops. The study recommends that a proper management plan is required to protect this coastal aquifer efficiently.

Geochemical background of zinc, cadmium and mercury in anthropically influenced soils in a semi-arid zone (SE, Spain)

Science.gov (United States)

García-Lorenzo, M. L.; Pérez-Sirvent, C.; Martínez-Sánchez, M. J.; Molina, J.; Tudela, M. L.; Hernández-Córdoba, M.

2009-04-01

This work seeks to establish the geochemical background for three potentially toxic trace elements (Zn, Cd and Hg) in a pilot zone included in the DesertNet project in the province of Murcia. The studied area, known as Campo de Cartagena, Murcia (SE Spain) is an area of intensive agriculture and has been much affected over the years by anthropic activity. The zone can be considered an experimental pilot zone for establishing background levels in agricultural soils. Sixty four samples were collected and corresponded to areas subjected to high and similar agricultural activity or soils with natural vegetation, which correspond to abandoned agricultural areas. The Zn content was determined by flame atomic absorption spectrometry. The Cd content was determined by electrothermal atomization atomic absorption spectrometry and mercury content was determined by atomic fluorescence spectrometry. Geostatistical analysis consisting of kriging and mapping was performed using the geostatistical analyst extension of ArcGIS 8.3. Zinc values ranged from 10 mg kg-1 to 151 mg kg-1, with an average value of 45 mg kg-1. Cadmium values ranged between 0.1 mg kg-1 and 0.9mg kg-1, with a mean value of 0.3 mg kg-1 and mercury values ranged from 0.1 mg kg-1 to 2.3 mg kg-1, with a mean value of 0.5 mg kg-1. At a national level, the Spanish Royal Decree 9/2005 proposes toxicological and statistical approaches to establish background values. According to the statistical approach, background values consist of the median value for the selected element. The background values for Zn, Cd and Hg in the studied area were 40 mg kg-1 for Zn, 0.3 mg kg-1 for Cd and 0.4 mg kg-1 for Hg.

Instrumenting an upland research catchment in Canterbury, New Zealand to study controls on variability of soil moisture, shallow groundwater and streamflow

Science.gov (United States)

McMillan, Hilary; Srinivasan, Ms

2015-04-01

Hydrologists recognise the importance of vertical drainage and deep flow paths in runoff generation, even in headwater catchments. Both soil and groundwater stores are highly variable over multiple scales, and the distribution of water has a strong control on flow rates and timing. In this study, we instrumented an upland headwater catchment in New Zealand to measure the temporal and spatial variation in unsaturated and saturated-zone responses. In NZ, upland catchments are the source of much of the water used in lowland agriculture, but the hydrology of such catchments and their role in water partitioning, storage and transport is poorly understood. The study area is the Langs Gully catchment in the North Branch of the Waipara River, Canterbury: this catchment was chosen to be representative of the foothills environment, with lightly managed dryland pasture and native Matagouri shrub vegetation cover. Over a period of 16 months we measured continuous soil moisture at 32 locations and near-surface water table (versus hillslope locations, and convergent versus divergent hillslopes. We found that temporal variability is strongly controlled by the climatic seasonal cycle, for both soil moisture and water table, and for both the mean and extremes of their distributions. Groundwater is a larger water storage component than soil moisture, and the difference increases with 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 are aspect and distance from stream. South-facing and near-stream locations have higher water tables and more, larger soil moisture wetting events. Typical hydrological models do not explicitly account for aspect, but our results suggest that it is an important factor in hillslope

Origin and Distribution of Methane Entrapped in Calcareous Alpine Proglacial Soil

Science.gov (United States)

Zhu, Biqing; Schroth, Martin H.; Henneberger, Ruth; Kübler, Manuel; Zeyer, Josef

2017-04-01

Methane (CH4) is an important greenhouse gas. The atmospheric methane concentration has been increasing in recent years, which is caused by imbalance between sources and sinks. Methane has been recently discovered to be entrapped in calcareous Swiss Alpine proglacial soil. This CH4 can be released upon mechanical impact and acidification. However, the amount, distribution and environmental fate of this entrapped CH4 in proglacial environment remain unknown. The entrapped CH4 in proglacial soil may be of modern or ancient origin. Modern origin includes ongoing or recent microbial CH4 production (methanogenesis) in subglacial or proglacial environments. An ancient origin mainly refers to CH4 produced thermogenically. This soil entrapped CH4 might be a common phenomenon along the entire glacial forefield, or it might only be present at few locations and depth. We present results of studies from two Swiss Alpine Glacier catchments, Wildstrubel Glacier (Canton Valais) and the Griessfirn Glacier (Canton Uri). Our main goals were 1) to assess the origin of CH4 entrapped in various glacial environments (subglacial, proglacial and supraglacial, soil and bedrocks) using geochemical and microbiological evidence; 2) to assess the spatial distribution of entrapped CH4. We performed geochemical analysis (CH4 content, gas wetness ([C1]/[C2-C3] alkane ratio), CH4 stable 13C- and 2H-isotopes, TOC) on subglacial, proglacial, and supraglacial soil samples collected from well-aerated and water-logged locations. Geochemical analysis was also selectively conducted on pore-water samples and on rock samples collected from different geological formations along the catchments. We also performed batch incubations on soil samples collected from subglacial, proglacial water-logged and supraglacial zones. In addition, for the aforementioned three types of samples, we also performed molecular analyses targeting the mcrA gene, which encodes the α-subunit of the enzyme methyl-coenzyme M reductase

Assessing the Biophysical Impact and Financial Viability of Soil Management Technologies Under Variable Climate in Cabo Verde Drylands

NARCIS (Netherlands)

Baptista, Isaurinda; Irvine, Brian; Fleskens, Luuk; Geissen, Violette; Ritsema, Coen

2016-01-01

Field trials have demonstrated the potential of soil conservation technologies but have also shown significant spatial-temporal yield variability. This study considers the Pan-European Soil Erosion Risk Assessment - Desertification Mitigation Cost-Effectiveness modelling approach to capture a

The estimation of soil parameters using observations on crop biophysical variables and the crop model STICS improve the predictions of agro environmental variables.

Science.gov (United States)

Varella, H.-V.

2009-04-01

Dynamic crop models are very useful to predict the behavior of crops in their environment and are widely used in a lot of agro-environmental work. These models have many parameters and their spatial application require a good knowledge of these parameters, especially of the soil parameters. These parameters can be estimated from soil analysis at different points but this is very costly and requires a lot of experimental work. Nevertheless, observations on crops provided by new techniques like remote sensing or yield monitoring, is a possibility for estimating soil parameters through the inversion of crop models. In this work, the STICS crop model is studied for the wheat and the sugar beet and it includes more than 200 parameters. After a previous work based on a large experimental database for calibrate parameters related to the characteristics of the crop, a global sensitivity analysis of the observed variables (leaf area index LAI and absorbed nitrogen QN provided by remote sensing data, and yield at harvest provided by yield monitoring) to the soil parameters is made, in order to determine which of them have to be estimated. This study was made in different climatic and agronomic conditions and it reveals that 7 soil parameters (4 related to the water and 3 related to the nitrogen) have a clearly influence on the variance of the observed variables and have to be therefore estimated. For estimating these 7 soil parameters, a Bayesian data assimilation method is chosen (because of available prior information on these parameters) named Importance Sampling by using observations, on wheat and sugar beet crop, of LAI and QN at various dates and yield at harvest acquired on different climatic and agronomic conditions. The quality of parameter estimation is then determined by comparing the result of parameter estimation with only prior information and the result with the posterior information provided by the Bayesian data assimilation method. The result of the

Variations in Carabidae assemblages across the farmland habitats in relation to selected environmental variables including soil properties

Directory of Open Access Journals (Sweden)

Beáta Baranová

2018-03-01

Full Text Available The variations in ground beetles (Coleoptera: Carabidae assemblages across the three types of farmland habitats, arable land, meadows and woody vegetation were studied in relation to vegetation cover structure, intensity of agrotechnical interventions and selected soil properties. Material was pitfall trapped in 2010 and 2011 on twelve sites of the agricultural landscape in the Prešov town and its near vicinity, Eastern Slovakia. A total of 14,763 ground beetle individuals were entrapped. Material collection resulted into 92 Carabidae species, with the following six species dominating: Poecilus cupreus, Pterostichus melanarius, Pseudoophonus rufipes, Brachinus crepitans, Anchomenus dorsalis and Poecilus versicolor. Studied habitats differed significantly in the number of entrapped individuals, activity abundance as well as representation of the carabids according to their habitat preferences and ability to fly. However, no significant distinction was observed in the diversity, evenness neither dominance. The most significant environmental variables affecting Carabidae assemblages species variability were soil moisture and herb layer 0-20 cm. Another best variables selected by the forward selection were intensity of agrotechnical interventions, humus content and shrub vegetation. The other from selected soil properties seem to have just secondary meaning for the adult carabids. Environmental variables have the strongest effect on the habitat specialists, whereas ground beetles without special requirements to the habitat quality seem to be affected by the studied environmental variables just little.

Spatial patterns and controls of soil chemical weathering rates along a transient hillslope

Science.gov (United States)

Yoo, K.; Mudd, S.M.; Sanderman, J.; Amundson, Ronald; Blum, A.

2009-01-01

Hillslopes have been intensively studied by both geomorphologists and soil scientists. Whereas geomorphologists have focused on the physical soil production and transport on hillslopes, soil scientists have been concerned with the topographic variation of soil geochemical properties. We combined these differing approaches and quantified soil chemical weathering rates along a grass covered hillslope in Coastal California. The hillslope is comprised of both erosional and depositional sections. In the upper eroding section, soil production is balanced by physical erosion and chemical weathering. The hillslope then transitions to a depositional slope where soil accumulates due to a historical reduction of channel incision at the hillslope's base. Measurements of hillslope morphology and soil thickness were combined with the elemental composition of the soil and saprolite, and interpreted through a process-based model that accounts for both chemical weathering and sediment transport. Chemical weathering of the minerals as they moved downslope via sediment transport imparted spatial variation in the geochemical properties of the soil. Inverse modeling of the field and laboratory data revealed that the long-term soil chemical weathering rates peak at 5 g m- 2 yr- 1 at the downslope end of the eroding section and decrease to 1.5 g m- 2 yr- 1 within the depositional section. In the eroding section, soil chemical weathering rates appear to be primarily controlled by the rate of mineral supply via colluvial input from upslope. In the depositional slope, geochemical equilibrium between soil water and minerals appeared to limit the chemical weathering rate. Soil chemical weathering was responsible for removing 6% of the soil production in the eroding section and 5% of colluvial influx in the depositional slope. These were among the lowest weathering rates reported for actively eroding watersheds, which was attributed to the parent material with low amount of weatherable

Soil biogeochemistry properties vary between two boreal forest ecosystems in Quebec: significant differences in soil carbon, available nutrients and iron and aluminium crystallinity

Science.gov (United States)