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Sample records for factors influencing soil

  1. Soil sealing degree as factor influencing urban soil contamination with polycyclic aromatic hydrocarbons (PAHs

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    Mendyk Łukasz

    2016-03-01

    Full Text Available The objective of the study was to determine role of soil sealing degree as the factor influencing soil contamination with polycyclic aromatic hydrocarbons (PAHs. The study area included four sampling sites located within the administrative boundaries of the Toruń city, Poland. Sampling procedure involved preparing soil pits representing three examples of soil sealing at each site: non-sealed soil as a control one (I and two degrees of soil sealing: semi-pervious surface (II and totally impervious surface (III. Together with basic properties defined with standard procedures (particle size distribution, pH, LOI, content of carbonates content of selected PAHs was determined by dichloromethane extraction using gas chromatography with mass spectrometric detection (GC-MS. Obtained results show that urban soils in the city of Toruń are contaminated with polycyclic aromatic hydrocarbons. Soil sealing degree has a strong influence on the soil contamination with polycyclic aromatic hydrocarbons. Totally sealed soils are better preserved from atmospheric pollution including PAHs. Combustion of grass/wood/coal was the main source of determined PAHs content in examined soils.

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

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

    2013-03-01

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

  3. Influencing factors of compressive strength of solidified inshore saline soil using SH lime-ash

    Institute of Scientific and Technical Information of China (English)

    覃银辉; 刘付华; 周琦

    2008-01-01

    Through unconfined compressive strength test,influencing factors on compressive strength of solidified inshore saline soil with SH lime-ash,ratio of lime-ash(1-K),quantity of lime-ash,age,degree of compression and salt content were studied.The results show that because inshore saline soil has special engineering characteristic,more influencing factors must be considered compared with ordinary soil for the perfect effect of solidifying.

  4. [Variation characteristic in soil respiration of apple orchard and its biotic and abiotic influencing factors].

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    Wang, Rui; Guo, Sheng-Li; Liu, Qing-Fang; Zhang, Yan-Jun; Jiang, Ji-Shao; Guo, Hui-Min; Li, Ru-Jian

    2014-05-01

    To evaluate the orchard variability of soil respiration and the response of soil respiration to its influencing factors is helpful for a deep understanding about the effects of converting cropland to apple orchard. A field experiment was conducted in the Changwu State Key Agro-Ecological Station. Soil respiration, soil temperature, soil moisture and roots biomasses were periodically measured in a mature apple orchard during 2011 and 2012. Soil respiration decreased as the distance from the trunk increased. The cumulative soil respiration in the 0.5 m-distance from the trunk was 20% and 31% higher than that in the 2 m-distance from the trunk, respectively in 2011 and 2012. The temperature sensitivity of soil respiration (Q10) was relatively lower in the 2 m-distance than that in the 0. 5 m-distance in both years. Soil temperature and soil moisture were slightly higher in the 2 m-distance, but there was no significant difference between the 2 m-distance and the 0. 5 m-distance. Soil respiration and soil temperature showed a significant exponential relationship, but there was no positive correlation between soil moisture and soil respiration. Soil temperature changes can explain seasonal variation of soil respiration well, but it could not explain its spatial variability. Root density was an important factor for the spatial variability of soil respiration and Q15. Variation of soil respiration coefficient was 23% -31%. Therefore, the distance from the trunk should be considered when estimating orchards soil respiration.

  5. Influence of Environmental Factors on Feammox Activity in Soil Environments

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    Huang, S.; Jaffe, P. R.

    2015-12-01

    The oxidation of ammonium (NH4+) under iron reducing conditions, referred to as Feammox, has been described in recent years by several investigators. The environmental characteristics in which the Feammox process occurs need to be understood in order to determine its contribution to the nitrogen cycle. In this study, a total of 66 locations were selected covering 4 different types of soils/sediments: wetland soils (W), river sediments (R), forest soils (F), and paddy soils (P) from several locations in central New Jersey, at Tims Branch at Savannah River in South Carolina, both in the Unities States, and at several locations in the Guangdong province in China. Though soil chemical analyses, serial culturing experiments, analysis of microbial communities, and using a canonical correspondence analysis, the occurrence of the Feammox reaction and the presence of Acidimicrobiaceae bacterium A6, which plays a key role in the Feammox process(1), were found in 17 samples. Analyses showed that the soil pH, as well as its Fe(III) and NH4+ content were the most important factors controlling the distribution of these Feammox microorganisms. Based on the results, soils in the subtropical forests and soils that are near agricultural areas could be Feammox hotspot. Under the conditions that favor the presence and activity of Feammox microorganisms and their oxidation of NH4+, denitrification bacteria were also active. However, the presence of nitrous oxide (N2O) reducers was limited under these conditions, implying that at locations where the Feammox process is active, conditions are favoring a higher ratio of N2O: N2 as the nitrogen (N) end products. Incubations of soils where the presence of Acidimicrobiaceae bacterium A6 was detected, were conducted for 120 days under two different DO levels (DO ammonia-oxidizing bacteria and anammox bacteria) decreased, while in the incubations with DO = 0.8~1.0 mg/L the opposite trend was observed. References Huang S., and Jaffé P.R., 2015

  6. Factors influencing adoption of soil and water conservation measures in southern Mali

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    Bodnar, F.; Graaff, de J.

    2003-01-01

    A soil and water conservation (SWC) extension programme, promoting erosion control measures and soil fertility measures, has been going on in southern Mali since 1986. Five factors that influence farmer adoption of SWC measures were analysed: land pressure, cotton-growing area, possession of ploughi

  7. The longitudinal translocation characters and the influencing factors of Hg, Cd in the soil

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    Zhang Yujuan

    2006-11-01

    Full Text Available Combining the methods of simulation test and field survey, the longitudinal distribution and the influencing factors of Hg and Cd in the profile in the typical sewage irrigation area were studied in this paper and the result shows: (1 the content distribution of Hg, Cd in the superficial soil profile was higher than that in the bottom and the content decreased with the increase of the depth, the translocation ability of the Hg, Cd in the garden mould and cinnamon soil were lower than that in the paddy soil and fluve-aquic soil, the longitudinal translocation ability of the Cd in the soil profile was stronger than that of Hg; (2 Hg was accumulated in the different soil and has the highest accumulation rate in the paddy soil and the lowest in the cinnamon soil; the translocation order of the Cd in the different was: garden mould > paddy soil > cinnamon soil > fluve-aquic soil; (3 the concentration of Hg, Cd in the soil leacheate increased with the concentration increase of Hg, Cd in the sewage, the migration rate increased with the roughness of the soil quality and decreased with the increase of pH and soil organic matter.

  8. The Influence of Soil Chemical Factors on In Situ Bioremediation of Soil Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Breedveld, Gijs D.

    1997-12-31

    Mineral oil is the major energy source in Western society. Production, transport and distribution of oil and oil products cause serious contamination problems of water, air and soil. The present thesis studies the natural biodegradation processes in the soil environment which can remove contamination by oil products and creosote. The main physical/chemical processes determining the distribution of organic contaminants between the soil solid, aqueous and vapour phase are discussed. Then a short introduction to soil microbiology and environmental factors important for biodegradation is given. There is a discussion of engineered and natural bioremediation methods and the problems related to scaling up laboratory experiments to field scale remediation. Bioremediation will seldom remove the contaminants completely; a residue remains. Factors affecting the level of residual contamination and the consequences for contaminant availability are discussed. Finally, the main findings of the work are summarized and recommendations for further research are given. 111 refs., 41 figs., 19 tabs.

  9. Decisive key-factors influencing farm households' soil and water conservation investments

    NARCIS (Netherlands)

    Kessler, A.

    2006-01-01

    In the inter-Andean valleys of Bolivia decisive key-factors influencing farm households' soil and water conservation investments were determined. The household's progressiveness most influences the decision how much to invest; dynamic and responsible families are among the first. Economic stratum is

  10. Chemical Forms of Mercury in Soils and Their Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    QINGCHANGLE; MOUSHUSEN; 等

    1998-01-01

    Experiments were carried out study the transformation of mercury in soils,Results showed that Hg2+ was immediatel converted into other forms once it entered into soils,Bentonite,humus or CaCO3 accelerated the transformaiton of Hg2+ by various mechanisms.Bentonite could convert Hg2+ into residual form eventually,and application of CaCO3 enhanced the formation of inorganic Hg,Humus competed strongly with clay minerals for binding Hg2+,thus increase of soil hums content led to increased formation of organically bound Hg.

  11. Soil factors exhibit greater influence than bacterial inoculation on alfalfa growth and nitrogen fixation.

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    Neumann, Ute; Kosier, Bob; Jahnke, Joachim; Priefer, Ursula B; Al-Halbouni, Djamila

    2011-09-01

    In order to study the effects of soil factors and bacterial inoculation on alfalfa (Medicago sativa), plants were inoculated with Ensifer meliloti L33 and Azospirillum brasilense Sp7 in pot experiments using two different soils separately as well as in a mixture. One soil was contaminated with chemical waste products; the other was an arable soil. Soil factors, including the availability of macro- and micronutrients as well as carbon and nitrogen contents, were found to exhibit a much greater influence on the growth of alfalfa than any of the inoculations. In contaminated soil, the shoot and root growth of alfalfa was decreased and nodules were diminished and ineffective. Bacterial inoculations did not significantly improve this hostile growth environment. However, in a mixture (44% arable, 22% contaminated soil, 34% vermiculite), growth conditions for alfalfa were improved so that shoot dry weight and nodule numbers increased up to 100- and 20-fold, respectively, compared with the contaminated soil. For the strain L33, its persistence in the rhizosphere was correlated to the presence of its host plant, but its dynamics were influenced by competition with indigenous rhizobia. The strain Sp7, once provided with a suitable soil, was not dependent on the plant's rhizosphere, but it enhanced the performance of L33 and native rhizobia.

  12. Influence of soil, land use and climatic factors on the hydraulic conductivity of soil

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    Jarvis, N.; Koestel, J.; Messing, I.; Moeys, J.; Lindahl, A.

    2013-12-01

    Due to inadequate data support, existing algorithms used to estimate soil hydraulic conductivity, K, in (eco)hydrological models ignore the effects of key site factors such as land use and climate and underplay the significant effects of soil structure on water flow at and near saturation. These limitations may introduce serious bias and error into predictions of terrestrial water balances and soil moisture status, and thus plant growth and rates of biogeochemical processes. To resolve these issues, we collated a new global database of hydraulic conductivity measured by tension infiltrometer under field conditions. The results of our analyses on this data set contrast markedly with those of existing algorithms used to estimate K. For example, saturated hydraulic conductivity, Ks, in the topsoil (< 0.3 m depth) was found to be only weakly related to texture. Instead, the data suggests that Ks depends more strongly on bulk density, organic carbon content and land use. In this respect, organic carbon was negatively correlated with Ks, presumably due to water repellency, while Ks at arable sites was, on average, ca. 2-3 times smaller than under natural vegetation, forests and perennial agriculture. The data also clearly demonstrates that clay soils have smaller K in the soil matrix and thus a larger contribution of soil macropores to K at and near saturation.

  13. Influence of the soil sealing on the geoaccumulation index of heavy metals and various pollution factors.

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    Charzyński, Przemysław; Plak, Andrzej; Hanaka, Agnieszka

    2017-02-01

    Soil sealing belongs to the most destructive and damaging processes to the soil environment. Soil sealing interrupts or greatly restricts the exchange of matter and energy between the biosphere, hydrosphere, and atmosphere and the soil environment. The aim of this study was to compare the content of heavy metals (Cd, Cr, Cu, Hg, Fe, Ni, Pb, Zn) of Ekranic Technosols by applying indicators such as geoaccumulation index (I geo), enrichment factor (EF), and pollution load index (PLI), which allowed to determine quantitatively the impact of the soil sealing degree on the content of heavy metals and to distinguish natural from anthropogenic sources of origin of heavy metals. In general, 42 soils from different parts of the city of Toruń (NW Poland) were sampled and divided into three groups according to the degree of soil sealing: completely sealed with asphalt or concrete (A), semi-permeable (partially sealed with cobblestones and concrete paving slabs (B)), and reference (non-sealed) (C). The results indicate that the artificial sealing in urban areas slightly affects the content of heavy metals in soils. However, based on PLI, I geo, and EF, it was found that the sealing has influence on soil properties and unsealed soil is the most exposed to the accumulation of pollutants.

  14. [Characteristics of Adsorption Leaching and Influencing Factors of Dimethyl Phthalate in Purple Soil].

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    Wang, Qiang; Song, Jiao-yan; Zeng, Wei; Wang, Fa

    2016-02-15

    The typical soil-purple soil in Three Gorges Reservoir was the tested soil, the characteristics of adsorption leaching of dimethyl phthalate (DMP) in contaminated water by the soil, and the influencing factors in the process were conducted using soil column leaching experiment. The results showed that the parabolic equation was the best equation describing adsorption kinetics of DMP by soils. The concentration of DMP in the leaching solution had significant effect on the adsorption amounts of DMP. With the increasing concentration of DMP in the leaching solution, the adsorption capacities of DMP by purple soil increased linearly. The ionic strength and pH in leaching solution had significant effects on adsorption of DMP. On the whole, increasing of the ionic strength restrained the adsorption. The adsorption amounts at pH 5.0-7.0 were more than those under other pH condition. The addition of exogenous organic matter (OM) in purple soil increased the adsorption amount of DMP by purple soil. However, the adsorption amount was less than those with other addition amounts of exogenous OM when the addition of exogenous OM was too high (> or = 30 g x kg(-1)). The addition of surfactant sodium dodecylbenzene sulfonic acid (SDBS) in purple soil increased the adsorption amount of DMP by purple soil. The adsorption amount was maximal when the addition amount of SDBS was 50 mg x kg(-1). However, the adsorption amounts decreased with increasing addition amounts of SDBS although the adsorption amounts were still more than that of the control group, and the adsorption amount was almost equal to that of the control group when the addition amount of SDBS was 800 mg x kg(-1). Continuous leaching time affected the vertical distribution of DMP in the soil column. When the leaching time was shorter, the upper soil column adsorbed more DMP, while the DMP concentrations in upper and lower soil columns became similar with the extension of leaching time.

  15. Intrinsic factors of Peltigera lichens influence the structure of the associated soil bacterial microbiota.

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    Leiva, Diego; Clavero-León, Claudia; Carú, Margarita; Orlando, Julieta

    2016-11-01

    Definition of lichens has evolved from bi(tri)partite associations to multi-species symbioses, where bacteria would play essential roles. Besides, although soil bacterial communities are known to be affected by edaphic factors, when lichens grow upon them these could become less preponderant. We hypothesized that the structure of both the lichen microbiota and the microbiota in the soil underneath lichens is shaped by lichen intrinsic and extrinsic factors. In this work, intrinsic factors corresponded to mycobiont and cyanobiont identities of Peltigera lichens, metabolite diversity and phenoloxidase activity and extrinsic factors involved the site of the forest where lichens grow. Likewise, the genetic and metabolic structure of the lichen and soil bacterial communities were analyzed by fingerprinting. Among the results, metabolite diversity was inversely related to the genetic structure of bacterial communities of lichens and soils, highlighting the far-reaching effect of these substances; while phenoloxidase activity was inversely related to the metabolic structure only of the lichen bacterial microbiota, presuming a more limited effect of the products of these enzymes. Soil bacterial microbiota was different depending on the site and, strikingly, according to the cyanobiont present in the lichen over them, which could indicate an influence of the photobiont metabolism on the availability of soil nutrients. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. THE INFLUENCES OF GEOMORPHOLOGICAL FACTORS ON SOIL CHARACTERISTICS IN AYVALIDERE BASIN (SULEYMANPASA/TEKIRDAG

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    Emre ÖZŞAHİN

    2016-01-01

    Full Text Available In this paper, the influences of geomorphological factors on the soil characteristics is studied on the basis of Ayvalıdere Basin. The fact that these relationships are examined within a sample basin constitutes the significance of the study. In this study, KIRKLARELI F19-d4 and BANDIRMA G19-a1 topographic maps on a scale of 1:25.000 are used. As to methodology, firstly the geomorphological characteristics of the basin area were identified. Afterwards, the detailed soil map of the area was formed by making use of the sample soil analyses by other researchers and the other study findings. Whether or not geomorpho- logical characteristics affect soil distribution in the basin was scrutinized by comparing and contrasting both geomorphological characteristics (landforms, slope, aspect, altitude and soil characteristics on GIS (Geographic Information Systems. It was found and emphasized as a result that the relationship between landforms and the soil characteristics significantly differs even in short distances. There is a need for more detailed research on this relationship. Thus, the obtained results may be used to take concrete steps for the conservation of soil resource and their proper use and planning. Finally, similar research on the rela- tionship between soil and the landforms dealing with pedological and geomorphological characteristics may help us to understand and analyze the natural environment better.

  17. Influence of soil, plant and meteorological factors on water relations and yield in Hevea brasiliensis

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    Rao, G. Gururaja; Rao, P. Sanjeeva; Rajagopal, R.; Devakumar, A. S.; Vijayakumar, K. R.; Sethuraj, M. R.

    1990-09-01

    Influence of factors governing the soil-plantatmosphere system on components of water relations and yield was studied in two clones of rubber tree, Hevea brasiliensis, viz. RRII 105 and RRII 118. Clonal variations were evident in yield and yield components and associated physiological parameters in response to soil moisture status and meteorological factors. Observations made during different seasons indicatedvariations in yield are attributed to differences in plugging index and initial flow rates, to the major yield components and also variations in components of water relations as influenced by meteorological factors. Among the two clones, RRII 105 was found to be fairly drought tolerant compared to RRII 118. RRII 105 was found to respond well to dry weather through higher stomatal resistances, higher leaf water potentials, lowered transpirational water loss and lower relative transpiration ratios, while RRII 118 was susceptible to stress situations.

  18. Soil moisture and biogeochemical factors influence the distribution of annual Bromus species

    Science.gov (United States)

    Belnap, Jayne; Stark, John Thomas; Rau, Benjamin; Allen, Edith B.; Phillips, Sue

    2016-01-01

    Abiotic factors have a strong influence on where annual Bromus species are found. At the large regional scale, temperature and precipitation extremes determine the boundaries of Bromusoccurrence. At the more local scale, soil characteristics and climate influence distribution, cover, and performance. In hot, dry, summer-rainfall-dominated deserts (Sonoran, Chihuahuan), little or noBromus is found, likely due to timing or amount of soil moisture relative to Bromus phenology. In hot, winter-rainfall-dominated deserts (parts of the Mojave Desert), Bromus rubens is widespread and correlated with high phosphorus availability. It also responds positively to additions of nitrogen alone or with phosphorus. On the Colorado Plateau, with higher soil moisture availability, factors limiting Bromus tectorum populations vary with life stage: phosphorus and water limit germination, potassium and the potassium/magnesium ratio affect winter performance, and water and potassium/magnesium affect spring performance. Controlling nutrients also change with elevation. In cooler deserts with winter precipitation (Great Basin, Columbia Plateau) and thus even greater soil moisture availability, B. tectorum populations are controlled by nitrogen, phosphorus, or potassium. Experimental nitrogen additions stimulate Bromus performance. The reason for different nutrients limiting in dissimilar climatic regions is not known, but it is likely that site conditions such as soil texture (as it affects water and nutrient availability), organic matter, and/or chemistry interact in a manner that regulates nutrient availability and limitations. Under future drier, hotter conditions,Bromus distribution is likely to change due to changes in the interaction between moisture and nutrient availability.

  19. Soil abiotic factors influence interactions between belowground herbivores and plant roots.

    Science.gov (United States)

    Erb, Matthias; Lu, Jing

    2013-03-01

    Root herbivores are important ecosystem drivers and agricultural pests, and, possibly as a consequence, plants protect their roots using a variety of defensive strategies. One aspect that distinguishes belowground from aboveground plant-insect interactions is that roots are constantly exposed to a set of soil-specific abiotic factors. These factors can profoundly influence root resistance, and, consequently, the outcome of the interaction with belowground feeders. In this review, we synthesize the current literature on the impact of soil moisture, nutrients, and texture on root-herbivore interactions. We show that soil abiotic factors influence the interaction by modulating herbivore abundance and behaviour, root growth and resistance, beneficial microorganisms, as well as natural enemies of the herbivores. We suggest that abiotic heterogeneity may explain the high variability that is often encountered in root-herbivore systems. We also propose that under abiotic stress, the relative fitness value of the roots and the potential negative impact of herbivory increases, which may lead to a higher defensive investment and an increased recruitment of beneficial microorganisms by the plant. At the same time, both root-feeding herbivores and natural enemies are likely to decrease in abundance under extreme environmental conditions, leading to a context- and species-specific impact on plant fitness. Only by using tightly controlled experiments that include soil abiotic heterogeneity will it be possible to understand the impact of root feeders on an ecosystem scale and to develop predictive models for pest occurrence and impact.

  20. Distribution characteristics and influencing factors of soil organic carbon in alpine ecosystems on the Tibetan Plateau transect, China

    Institute of Scientific and Technical Information of China (English)

    Yuqiang TIAN; Hua OUYANG; Minghua SONG; Haishan NIU; Qiwu HU

    2008-01-01

    The undisturbed regions along the Qinghai-Tibet Highway crossing the natural zones of montane desert, alpine meadow-steppe, and montane shrub-conifer-ous forest were chosen as the study areas. Soil samples were collected at 23 sites and the relations between the influ-encing factors and distribution of soil organic carbon (SOC) content were studied. The results indicated that the order of SOC content for the whole soil profile with differ-ent vegetations and in the horizontal direction was shown as below: forest > shrub > meadow > steppe > desert. All the SOC contents of the top 10 cm soil layers of forest, shrub and meadow vegetations, as well as that of the top 20 cm soil layers in steppe, in the vertical direction, were higher than those of corresponding lower soil layers. However, the SOC content in the desert soil was in accord-ance. The grey correlative analysis between the climatic factors and SOC content in the top soil show that precip-itation was the dominant climatic factor affecting the dis-tribution of SOC in the Tibetan Plateau transect. The influence of precipitation on the horizontal distribution of SOC decreased with the increase of precipitation in the horizontal direction. The vertical distribution of SOC along the soil profile was greatly affected by precipitation or the soil clay content in top soil layers, and was clearly influ-enced by soil silt content or sand content in lower soil layers, as well. The influences of both soil bulk density and soil pH on the vertical distribution of SOC along the soil profile gradually declined. The plant biomass was the most import-ant biotic factors affecting the distribution of the SOC.

  1. Identification of factors influencing the restoration of cyanobacteria-dominated biological soil crusts.

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    Chongfeng Bu

    Full Text Available Biological soil crusts (BSCs cover >35% of the Earth's land area and contribute to important ecological functions in arid and semiarid ecosystems, including erosion reduction, hydrological cycling, and nutrient cycling. Artificial rapid cultivation of BSCs can provide a novel alternative to traditional biological methods for controlling soil and water loss such as the planting of trees, shrubs, and grasses. At present, little is known regarding the cultivation of BSCs in the field due to lack of knowledge regarding the influencing factors that control BSCs growth. Thus, we determined the effects of various environmental factors (shade; watering; N, P, K, and Ca concentrations on the growth of cyanobacteria-dominated BSCs from the Sonoran Desert in the southwestern United States. The soil surface changes and chlorophyll a concentrations were used as proxies of BSC growth and development. After 4 months, five factors were found to impact BSC growth with the following order of importance: NH4NO3 ≈ watering frequency>shading>CaCO3 ≈ KH2PO4. The soil water content was the primary positive factor affecting BSC growth, and BSCs that were watered every 5 days harbored greater biomass than those watered every 10 days. Groups that received NH4NO3 consistently exhibited poor growth, suggesting that fixed N amendment may suppress BSC growth. The effect of shading on the BSC biomass was inconsistent and depended on many factors including the soil water content and availability of nutrients. KH2PO4 and CaCO3 had nonsignificant effects on BSC growth. Collectively, our results indicate that the rapid restoration of BSCs can be controlled and realized by artificial "broadcasting" cultivation through the optimization of environmental factors.

  2. Characterization on the rhizoremediation of petroleum contaminated soil as affected by different influencing factors

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    J. Tang

    2010-06-01

    Full Text Available In this paper, pilot experiments were conducted to analyze the effect of different environmental factors on the rhizoremediation of petroleum contaminated soil. Different plant species (cotton, ryegrass, tall fescue, and alfalfa, addition of fertilizer, different concentration of TPH in soil, bioaugmentation with effective microbial agent (EMA and PGPR, and remediation time were tested as influencing factors during bioremediation process of Total Petroleum Hydrocarbon (TPH. The result shows that the remediation process can be enhanced by different plants species with the following order: tall fescue > ryegrass > alfalfa > cotton. The degradation rate of TPH increased with increased fertilizer addition and moderate level of 20 g/m2 urea is best for both plant growth and TPH remediation. High TPH content is toxic to plant growth and inhibits the degradation of petroleum hydrocarbon with 5% TPH content showing the best degradation result in soil planted with ryegrass. Bioaugmentation with different bacteria and plant growth promoting rhizobacteria (PGPR showed the following results for TPH degradation: cotton + EMA + PGPR > cotton + EMA > cotton + PGPR > cotton > control. Rapid degradation of TPH was found at the initial period of remediation caused by the activity of microorganisms, continuous increase was found from 30–90 d period and slow increase was found from 90 to 150 d. The result suggests that rhizoremediation can be enhanced with the proper control of different influencing factors that affect both plant growth and microbial activity in the rhizosphere environment.

  3. Characterization on the rhizoremediation of petroleum contaminated soil as affected by different influencing factors

    Science.gov (United States)

    Tang, J.; Wang, R.; Niu, X.; Wang, M.; Zhou, Q.

    2010-06-01

    In this paper, pilot experiments were conducted to analyze the effect of different environmental factors on the rhizoremediation of petroleum contaminated soil. Different plant species (cotton, ryegrass, tall fescue, and alfalfa), addition of fertilizer, different concentration of TPH in soil, bioaugmentation with effective microbial agent (EMA) and PGPR, and remediation time were tested as influencing factors during bioremediation process of Total Petroleum Hydrocarbon (TPH). The result shows that the remediation process can be enhanced by different plants species with the following order: tall fescue > ryegrass > alfalfa > cotton. The degradation rate of TPH increased with increased fertilizer addition and moderate level of 20 g/m2 urea is best for both plant growth and TPH remediation. High TPH content is toxic to plant growth and inhibits the degradation of petroleum hydrocarbon with 5% TPH content showing the best degradation result in soil planted with ryegrass. Bioaugmentation with different bacteria and plant growth promoting rhizobacteria (PGPR) showed the following results for TPH degradation: cotton + EMA + PGPR > cotton + EMA > cotton + PGPR > cotton > control. Rapid degradation of TPH was found at the initial period of remediation caused by the activity of microorganisms, continuous increase was found from 30-90 d period and slow increase was found from 90 to 150 d. The result suggests that rhizoremediation can be enhanced with the proper control of different influencing factors that affect both plant growth and microbial activity in the rhizosphere environment.

  4. Survey analysis of soil physicochemical factors that influence the distribution of Cordyceps in the Xiahe Region of Gansu Province

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    He Shuling

    2017-04-01

    Full Text Available In this paper, we studied the influence of soil physicochemical factors on the distribution of Cordyceps. We found that in the soil layers at different depths, the differences in pH values, total N (TN, total P (TP, available P (AP and available K (AK were not significant, but the differences in soil water content (WC, soil organic matter (OM, hydrolysable nitrogen (HN and AK were significant. In the 5-10 cm layer, WC, pH and TP were significant factors that influence the distribution of Cordyceps - the number of Cordyceps was the largest and the characterization of the Cordyceps was also the best. TP was an important factor for the first principle component of the soil physicochemical properties that influenced the population distribution of Cordyceps. pH value was an important factor for the the second principal component of the soil physicochemical properties that influenced population distribution, and WC was an important factor for the third principal component, the soil physicochemical properties. This demonstrates that the requirement of Cordyceps for specific ranges of WC, soil acidity-alkalinity and AP in soil layers is very high.

  5. Distribution of Soil Organic Carbon and the Influencing Factors in An Oasis Farmland Area

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    WANG Ze

    2014-08-01

    Full Text Available The soil organic carbon(SOC of a typical oasis farmland in middle part of Manasi county of Xinjiang was used as the research ob原 ject. Using remote sensing and lab analysis techniques, influences of soil texture, terrain, land uses, and crop types on SOC content of farmland were studied. Results showed that the SOC distribution in farmland of Manasi was mainly determined by comprehensive natural environmental factors. The SOC content decreased along with the increasing soil depth. For soil textures, the SOC content from high to low was clay loam>powder loam>silty loam. Slope direction had significantly positive correlations with SOC contents at 0~30 cm and 30~60 cm, while altitude and SOC content at 60~100 cm were significantly positive correlation. The SOC content of orchard was the highest, and the uncultivated land was the lowest under different land-use patterns. For different crop planting systems, the order of SOC content was corn field >wine grapes field>cotton field, and the difference was significant.

  6. Characterisation of the rhizoremediation of petroleum-contaminated soil: effect of different influencing factors

    Science.gov (United States)

    Tang, J. C.; Wang, R. G.; Niu, X. W.; Wang, M.; Chu, H. R.; Zhou, Q. X.

    2010-12-01

    Pilot experiments were conducted to analyse the effect of different environmental factors on the rhizoremediation of petroleum-contaminated soil. Different plant species (cotton, ryegrass, tall fescue and alfalfa), the addition of fertilizer, different concentrations of total petroleum hydrocarbons (TPH) in the soil, bioaugmentation with effective microbial agents (EMA) and plant growth-promoting rhizobacteria (PGPR) and remediation time were tested as influencing factors during the bioremediation process of TPH. The results show that the remediation process can be enhanced by different plant species. The order of effectiveness of the plants was the following: tall fescue > ryegrass > alfalfa > cotton. The degradation rate of TPH increased with increased fertilizer addition, and a moderate urea level of 20 g N (Nitrogen)/m2 was best for both plant growth and TPH remediation. A high TPH content is toxic to plant growth and inhibits the degradation of petroleum hydrocarbons. The results showed that a 5% TPH content gave the best degradation in soil planted with ryegrass. Bioaugmentation with different bacteria and PGPR yielded the following results for TPH degradation: cotton+EMA+PGPR > cotton+EMA > cotton+PGPR > cotton > control. Rapid degradation of TPH was found at the initial period of remediation caused by the activity of microorganisms. A continuous increase of degradation rate was found during the 30-90 days period followed by a slow increase during the 90-150 days period. These results suggest that rhizoremediation can be enhanced with the proper control of different influencing factors that affect both plant growth and microbial activity in the rhizosphere environment.

  7. Characterisation of the rhizoremediation of petroleum-contaminated soil: effect of different influencing factors

    Directory of Open Access Journals (Sweden)

    J. C. Tang

    2010-12-01

    Full Text Available Pilot experiments were conducted to analyse the effect of different environmental factors on the rhizoremediation of petroleum-contaminated soil. Different plant species (cotton, ryegrass, tall fescue and alfalfa, the addition of fertilizer, different concentrations of total petroleum hydrocarbons (TPH in the soil, bioaugmentation with effective microbial agents (EMA and plant growth-promoting rhizobacteria (PGPR and remediation time were tested as influencing factors during the bioremediation process of TPH. The results show that the remediation process can be enhanced by different plant species. The order of effectiveness of the plants was the following: tall fescue > ryegrass > alfalfa > cotton. The degradation rate of TPH increased with increased fertilizer addition, and a moderate urea level of 20 g N (Nitrogen/m2 was best for both plant growth and TPH remediation. A high TPH content is toxic to plant growth and inhibits the degradation of petroleum hydrocarbons. The results showed that a 5% TPH content gave the best degradation in soil planted with ryegrass. Bioaugmentation with different bacteria and PGPR yielded the following results for TPH degradation: cotton+EMA+PGPR > cotton+EMA > cotton+PGPR > cotton > control. Rapid degradation of TPH was found at the initial period of remediation caused by the activity of microorganisms. A continuous increase of degradation rate was found during the 30–90 days period followed by a slow increase during the 90–150 days period. These results suggest that rhizoremediation can be enhanced with the proper control of different influencing factors that affect both plant growth and microbial activity in the rhizosphere environment.

  8. Major factors influencing cadmium uptake from the soil into wheat plants.

    Science.gov (United States)

    Liu, Ke; Lv, Jialong; He, Wenxiang; Zhang, Hong; Cao, Yingfei; Dai, Yunchao

    2015-03-01

    At present, soil quality standards for agriculture have not been improved for many years and are applied uniformly for a diverse variety of crops and different soil types, not fully considering the effects of soil properties on cadmium (Cd) uptake via soil-plant transfer. In this study, the characteristics of Cd transfer from soil to eight wheat varieties were investigated, and the results showed that Xiaoyan 22 was moderately sensitive to Cd. Upon growing Xiaoyan 22 in 18 different Chinese soils, we studied the major controlling factors of Cd transfer and constructed a bioaccumulation prediction model from the soil properties. The results showed that pH was the most important factor contributing to Cd uptake. After calibration for the eight wheat varieties, a continuous soil threshold model for wheat was derived for the species sensitive distribution based on food safety standards.

  9. Influence of geogenic factors on microbial communities in metallogenic Australian soils.

    Science.gov (United States)

    Reith, Frank; Brugger, Joel; Zammit, Carla M; Gregg, Adrienne L; Goldfarb, Katherine C; Andersen, Gary L; DeSantis, Todd Z; Piceno, Yvette M; Brodie, Eoin L; Lu, Zhenmei; He, Zhili; Zhou, Jizhong; Wakelin, Steven A

    2012-11-01

    Links between microbial community assemblages and geogenic factors were assessed in 187 soil samples collected from four metal-rich provinces across Australia. Field-fresh soils and soils incubated with soluble Au(III) complexes were analysed using three-domain multiplex-terminal restriction fragment length polymorphism, and phylogenetic (PhyloChip) and functional (GeoChip) microarrays. Geogenic factors of soils were determined using lithological-, geomorphological- and soil-mapping combined with analyses of 51 geochemical parameters. Microbial communities differed significantly between landforms, soil horizons, lithologies and also with the occurrence of underlying Au deposits. The strongest responses to these factors, and to amendment with soluble Au(III) complexes, was observed in bacterial communities. PhyloChip analyses revealed a greater abundance and diversity of Alphaproteobacteria (especially Sphingomonas spp.), and Firmicutes (Bacillus spp.) in Au-containing and Au(III)-amended soils. Analyses of potential function (GeoChip) revealed higher abundances of metal-resistance genes in metal-rich soils. For example, genes that hybridised with metal-resistance genes copA, chrA and czcA of a prevalent aurophillic bacterium, Cupriavidus metallidurans CH34, occurred only in auriferous soils. These data help establish key links between geogenic factors and the phylogeny and function within soil microbial communities. In particular, the landform, which is a crucial factor in determining soil geochemistry, strongly affected microbial community structures.

  10. Influence of environmental factors on the spatial distribution and diversity of forest soil in Latvia

    OpenAIRE

    Raimonds Kasparinskis; Olgerts Nikodemus

    2012-01-01

    This study was carried out to determine the spatial relationships between environmental factors (Quaternary deposits, topographical situation, land cover, forest site types, tree species, soil texture) and soil groups, and their prefix qualifiers (according to the international Food and Agricultural Organization soil classification system World Reference Base for Soil Resources [FAO WRB]). The results show that it is possible to establish relationships between the distribution of environmenta...

  11. Correlation Between the Content of Fluoride in Tea and Properties of Tea Garden Soil and Its Influencing Factors

    Directory of Open Access Journals (Sweden)

    ZHAO Ming

    2016-05-01

    Full Text Available The water-soluble fluorine, pH, exchangeable acid, exchangeable cation content of soil from typical tea gardens in Qingdao and its fluoride content in tea were determined. We studied the correlation between fluoride content in tea and the soil properties, and analyzed the main influencing factors of soil water-soluble fluorine and exchangeable acid. The results showed that the water-soluble fluorine of tea garden soil and exchangeable acid were positively correlated with tea fluoride content, which are the main factors affecting the fluorine content in tea. Soil exchangeable H+ and Na+ were positively correlated with soil water-soluble fluorine, which are the main factors affecting the soil water-soluble fluorine. Soil exchangeable acid was positively correlated with exchangeable Al3+, and negatively correlated with pH, exchangeable Ca2+, exchangeable base amount and base saturation, which are the main factors affecting the soil exchangeable acid. The results can provide the bases for tea garden soil improvement and reduce the quality and safety risk of tea fluorine.

  12. Influence of natural and anthropogenic factors on the dynamics of CO2 emissions from chernozems soil

    Science.gov (United States)

    Syabruk, Olesia

    2017-04-01

    Twentieth century marked a significant expansion of agricultural production. Soil erosion caused by human activity, conversion of forests and grasslands to cropland, desertification, burning nutrient residues, drainage, excessive cultivation led to intense oxidation of soil carbon to the atmosphere and allocation of additional amounts of CO2. According to the UN Intergovernmental Panel on Climate Change, agriculture is one of the main sources of greenhouse gases emissions to the atmosphere. The thesis reveals main patterns of the impact of natural and anthropogenic factors on CO2 emissions in the chernozems typical and podzolized in a Left-bank Forest-Steppe of Ukraine, seasonal and annual dynamics. New provisions for conducting monitoring CO2 emissions from soil were developed by combining observations in natural and controlled conditions, which allows isolating the impact of hydrological, thermal and trophic factors. During the research, the methods for operational monitoring of emission of carbon losses were improved, using a portable infrared gas analyzer, which allows receiving information directly in the field. It was determined that the volumes of emission losses of carbon chernozems typical and podzolized Left-bank Forest-Steppe of Ukraine during the growing season are 480-910 kg/ha and can vary depending on the soil treatment ±( 4,0 - 6,0) % and fertilizer systems ± (3,8 - 7,1) %. The significant impact of long application of various fertilizer systems and soil treatment on the intensity of carbon dioxide emissions was investigated. It was found that most emission occurs in organic- mineral fertilizers systems with direct seeding. The seasonal dynamics of the potential capacity of the soil to produce CO2 were researched. Under identical conditions of humidity and temperature it has maximum in June and July and the gradual extinction of the autumn. It was determined that the intensity of the CO2 emission from the surface of chernozem fluctuates daily from

  13. Influence of environmental factors on the spatial distribution and diversity of forest soil in Latvia

    Directory of Open Access Journals (Sweden)

    Raimonds Kasparinskis

    2012-02-01

    Full Text Available This study was carried out to determine the spatial relationships between environmental factors (Quaternary deposits, topographical situation, land cover, forest site types, tree species, soil texture and soil groups, and their prefix qualifiers (according to the international Food and Agricultural Organization soil classification system World Reference Base for Soil Resources [FAO WRB]. The results show that it is possible to establish relationships between the distribution of environmental factors and soil groups by applying the generalized linear models in data statistical analysis, using the R 2.11.1 software for processing data from 113 sampling plots throughout the forest territory of Latvia.A very high diversity of soil groups in a relatively similar geological structure was revealed. For various reasons there is not always close relationship between the soil group, their prefix qualifiers and Quaternary deposits, as well as between forest site types, the dominant tree species and specific soil group and its prefix qualifiers. Close correlation was established between Quaternary deposits, forest site types, dominant tree species and soil groups within nutrient-poor sediments and very rich deposits containing free carbonates. No significant relationship was detected between the CORINE Land Cover 2005 classes, topographical situation and soil group.

  14. Environmental factors influencing trace house gas production in permafrost-affected soils

    Science.gov (United States)

    Walz, Josefine; Knoblauch, Christian; Böhme, Luisa; Pfeiffer, Eva-Maria

    2016-04-01

    The permafrost-carbon feedback has been identified as a major feedback mechanism to climate change. Soil organic matter (SOM) decomposition in the active layer and thawing permafrost is an important source of atmospheric carbon dioxide (CO2) and methane (CH4). Decomposability and potential CO2 and CH4 production are connected to the quality of SOM. SOM quality varies with vegetation composition, soil type, and soil depth. The regulating factors affecting SOM decomposition in permafrost landscapes are not well understood. Here, we incubated permafrost-affected soils from a polygonal tundra landscape in the Lena Delta, Northeast Siberia, to examine the influence of soil depth, oxygen availability, incubation temperature, and fresh organic matter addition on trace gas production. CO2 production was always highest in topsoil (0 - 10 cm). Subsoil (10 - 50 cm) and permafrost (50 - 90 cm) carbon did not differ significantly in their decomposability. Under anaerobic conditions, less SOM was decomposed than under aerobic conditions. However, in the absence of oxygen, CH4 can also be formed, which has a substantially higher warming potential than CO2. But, within the four-month incubation period (approximate period of thaw), methanogenesis played only a minor role with CH4 contributing 1-30% to the total anaerobic carbon release. Temperature and fresh organic matter addition had a positive effect on SOM decomposition. Across a temperature gradient (1, 4, 8°C) aerobic decomposition in topsoil was less sensitive to temperature than in subsoil or permafrost. The addition of labile plant organic matter (13C-labelled Carex aquatilis, a dominant species in the region) significantly increased overall CO2 production across different depths and temperatures. Partitioning the total amount of CO2 in samples amended with Carex material into SOM-derived CO2 and Carex-derived CO2, however, revealed that most of the additional CO2 could be assigned to the organic carbon from the amendment

  15. The influence of Alpine soil properties on shallow movement hazards, investigated through factor analysis

    Directory of Open Access Journals (Sweden)

    S. Stanchi

    2012-06-01

    Full Text Available Mountain watersheds are particularly vulnerable to extreme meteorological events, such as high intensity rainfall, and mountain soils often show pronounced fragility and low resilience due to severe environmental conditions. Alpine soil vulnerability is partly intrinsic but in part related to climate change (mainly precipitation regimes, and is enhanced by the abandonment of rural mountain areas that reduced the land maintenance actions traditionally carried out by farmers and local populations in the past. Soil hazards are related to different processes such as water erosion, loss of consistency, surface runoff and sediment transport, often occurring simultaneously and interacting with each other. Therefore, the overall effects on soil are not easy to quantify as they can be evaluated from different soil chemical and physical properties, referring to specific soil loss phenomena such as soil erosion, soil liquefaction, loss of consistency etc. In this study, we focus our attention on a mountain region in the NW Italian Alps (Valle d'Aosta, which suffered from diffuse soil instability phenomena in recent years, as a consequence of extreme rainfall events and general abandonment of the agricultural activities in marginal areas. The main effects were a large number of shallow landislides involving limited soil depths (less than 1 m, affecting considerable surfaces in the lower and middle part of the slopes. These events caused loss of human lives in the year 2000 and therefore raised the attention on land maintenance issues. Surface (topsoil: 0–20 cm and subsurface (subsoil: 20–70 cm samples were characterised chemically and physically (pH, carbon and nitrogen contents, cation exchange capacity, texture, aggregate stability, Atterberg limits etc. and they showed very different soil properties. Topsoils were characterised by better stability, structure, and consistency. The differences between the two depths were potential trigger factors for

  16. [Spatial distribution of soil moisture and salinity and their influence factors in the farmland of Manas River catchment, Northwest China].

    Science.gov (United States)

    Shen, Hao; Abuduwaili, Jilili

    2015-03-01

    Applying methods of statistics and geo-statistics, Manas River catchment was selected as the research area to study the spatial distribution of soil moisture and salinity in the soil profile as. well as their influence factors. The coupling relationship between soil moisture and salinity presented in the spatial distribution was explored as well. The result showed that the soil moisture was overall at a low level (varying from 14.2% to 20.9%), while the salinity was relatively high (about 6.00-9.15 g . kg-1). The soil profile distribution of water and salt contents both showed a trend of bottom accumulation. The variation of soil water moisture was moderate, while that of salt content was strong. Soil salinity and moisture of all layers showed strong spatial autocorrelation, which were mainly affected by structural factors. The horizontal distribution patterns of water and salt contents were irregular, and were constrained by factors like terrain and landforms, etc. Disturbed by human activities, the coupling relation of soil moisture and salinity became much more complex, but their spatial distribution variation was synchronized to some extent.

  17. Factors Influencing Access to Integrated Soil Fertility Management Information and Knowledge and Its Uptake among Smallholder Farmers in Zimbabwe

    Science.gov (United States)

    Gwandu, T.; Mtambanengwe, F.; Mapfumo, P.; Mashavave, T. C.; Chikowo, R.; Nezomba, H.

    2014-01-01

    Purpose: The study evaluated how farmer acquisition, sharing and use patterns of information and knowledge interact with different socioeconomic factors to influence integrated soil fertility management (ISFM) technology uptake. Design/methodology/approach: The study was conducted as part of an evaluation of field-based farmer learning approaches…

  18. Copper and cobalt mobility in soil and accumulation in a metallophyte as influenced by experimental manipulation of soil chemical factors.

    Science.gov (United States)

    Lange, Bastien; Pourret, Olivier; Meerts, Pierre; Jitaru, Petru; Cancès, Benjamin; Grison, Claude; Faucon, Michel-Pierre

    2016-03-01

    The influence of Fe oxides, Mn oxides and organic matter (OM) on the Cu and Co mobility in soil and accumulation in the metallophyte Anisopappus chinensis (Ac), as compared with Helianthus annuus (Ha), was experimentally investigated. Growth and accumulation response when increasing the exchangeable Cu and Co concentrations in soil were also investigated. Plants were cultivated on soil where concentrations of Cu, Co, Fe oxides, Mn oxides and OM content were varied according to 36 treatments. The OM supply decreased the Cu mobility and increased the Co mobility, resulting in decreasing the foliar Cu of Ac and increasing the foliar Co of Ha. The Fe oxides supply could increase the Cu accumulation for Ac, but was not verified for Ha. Compared with Ha, Ac increasingly accumulated Cu and Co without negative effect on plant growth while increasing Cu and Co mobility to phytotoxic concentrations. The results revealed promising perspectives for the use of Ac in Cu-contaminated environment phytoremediation applications.

  19. Characteristics and influencing factors of tetrachloroethylene sorption-desorption on soil and its components.

    Science.gov (United States)

    Qiu, Zhaofu; Yang, Weiwei; He, Long; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian

    2016-02-01

    To investigate the effects of soil structure, soil organic carbon (SOC), minerals, initial tetrachloroethylene (PCE) concentration (C0), and ionic strength (Ci) on PCE sorption-desorption, six types of soil were adopted as adsorbents, including two types of natural soil and four types of soil with most of the "soft carbon" pre-treated by H2O2 or with all SOC removed from the original soil by 600 °C ignition. The results showed that all of the sorption-desorption isotherms of PCE were non-linear within the experimental range, and the H2O2-treated samples exhibited higher non-linear sorption isotherms than those of the original soils. The hysteresis index of PCE sorption to original soil is less pronounced than that of the H2O2-treated and 600 °C-heated samples due to the entrapment of sorbate molecules in the "hard carbon" domain, together with the meso- and microporous structures within the 600 °C-heated samples. Both SOC and minerals have impacts on the sorption-desorption of PCE, and the sorption-desorption contribution rate of minerals increased with decreasing SOC content. C0 has almost no influence on the sorption to minerals of the soils, but the contribution rate of minerals decreased with increasing C0 in the desorption stage. As a result of the salting-out effect, PCE sorption capacity was increased by increasing Ci, especially when Ci ≥ 0.1 M. Moreover, desorption increased and hysteresis weakened with increasing Ci, except for the 600 °C-heated samples. In addition, no significant effect of Ci on desorption of PCE and no hysteresis was observed in this experimental range for the 600 °C-heated samples.

  20. Influence of biotic and abiotic factors on dissipating metalaxyl in soil.

    Science.gov (United States)

    Sukul, P; Spiteller, M

    2001-11-01

    Under laboratory condition, dissipation of metalaxyl in sterile and non-sterile soils, its sorption behaviour and fate in presence of light have been studied. The half-life value of metalaxyl was found in the range of 36-73 d in non-sterile soil. 5.3-14.7% dissipation was observed due to abiotic factors other than light. Metalaxyl was found photostable in soil showing half-life of 188- 502 h under simulated sunlight. In adsorption study, a non-linear relationship between concentration of metalaxyl and its adsorption into soils was observed. Estimated koc value increased as organic carbon content decreased. Adsorption and desorption kD values ranged between 53.5 and 151.1.

  1. Factors influencing the extraction of pharmaceuticals from sewage sludge and soil: an experimental design approach.

    Science.gov (United States)

    Ferhi, Sabrina; Bourdat-Deschamps, Marjolaine; Daudin, Jean-Jacques; Houot, Sabine; Nélieu, Sylvie

    2016-09-01

    Pharmaceuticals can enter the environment when organic waste products are recycled on agricultural soils. The extraction of pharmaceuticals is a challenging step in their analysis. The very different extraction conditions proposed in the literature make the choice of the right method for multi-residue analysis difficult. This study aimed at evaluating, with experimental design methodology, the influence of the nature, pH and composition of the extraction medium on the extraction recovery of 14 pharmaceuticals, including 8 antibiotics, from soil and sewage sludge. Preliminary experimental designs showed that acetonitrile and citrate-phosphate buffer were the best extractants. Then, a response surface design demonstrated that many cross-product and squared terms had significant effects, explaining the shapes of the response surfaces. It also allowed optimising the pharmaceutical recoveries in soil and sludge. The optimal conditions were interpreted considering the ionisation states of the compounds, their solubility in the extraction medium and their interactions with the solid matrix. To perform the analysis, a compromise was made for each matrix. After a QuEChERS purification, the samples were analysed by online SPE-UHPLC-MS-MS. Both methods were simple and economical. They were validated with the accuracy profile methodology for soil and sludge and characterised for another type of soil, digested sludge and composted sludge. Trueness globally ranged between 80 and 120 % recovery, and inter- and intra-day precisions were globally below 20 % relative standard deviation. Various pharmaceuticals were present in environmental samples, with concentration levels ranging from a few micrograms per kilogramme up to thousands of micrograms per kilogramme. Graphical abstract Influence of the extraction medium on the extraction recovery of 14 pharmaceuticals. Influence of the ionisation state, the solubility and the interactions of pharmaceuticals with solid matrix. Analysis

  2. Wien Effect in Suspensions of Electrodialyzed Soil Particles and Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The electrical conductivity of suspensions and their supernatants from the electrodialyzed clay fractions of latosol, yellow-brown soil and black soil equilibrated with nitrate solutions were determined at different field strengths using a short high-voltage pulse apparatus to demonstrate the Wien effect in soil suspensions and to investigate factors affecting it. It was found that Wien effect was much stronger in suspensions with a clay content of 30 g kg-1 from the soils equilibrated with a 1 × 10-4 KNO3 solution than in their supernatants.The threshold field strength (TFS), at which the relative conductivity is equal to 1.05, i.e., the Wien effect begins to be obvious, of the yellow-brown soil suspensions (clay content of 30 g kg-1) equilibrated with different nitrate solutions of a concentration of 1 × 10-4/z mol L-1 , where z is the valence, varied with the type of nitrates, being lowest for NaNO3 (47 kV cm-1) and highest for Ca(NO3)2 (98 kV cm-1). At high field strengths (larger than 130 kV cm-1), the relative conductivities of yellow-brown soil suspensions containing different nitrates diminished in the order: NaNO3 > KNO3 > Mg(NO3)2 > Zn(NO3)2 > Ca(NO3)2. The rates and intensities of the Wien effect in the suspensions of the three soils equilibrated with 5 × 10-5 molL-1 Ca(NO3)2 solution were in the order of the yellow-brown soil > the latosol > the black soil. The results for the yellow-brown soil suspensions (clay concentration of 30 g kg-1) equilibrated with KNO3 solutions of various concentrations clearly demonstrated that the more dilute the solution, the lower the TFS, and the larger the relative conductivity of the suspensions at high field strengths. The results for yellow-brown soil suspensions with different clay concentrations indicated that as the clay concentration increased, the low field electrical conductivity, EC0, also increased, but the TFS decreased, and the Wien effect increased.

  3. INFLUENCE OF HEXAVALENT CHROMIUM INITIAL CONCENTRATION ON RETARDATION FACTOR AND CONTAMINANT VELOCITY IN A SOIL MEDIA

    Directory of Open Access Journals (Sweden)

    K. SHIVA PRASHANTH KUMAR

    2016-02-01

    Full Text Available Sources of soil and ground water contamination are many and include many folds of accidental spills and leaks of toxic and hazardous chemicals. Preparation of ground water contamination model needs good understanding of the behavior of contaminant transport through soil media for predicting the level of contamination of ground water in the near future at the intended site conditions. Sorption is a natural process; due to its presence, the contaminant can move slowly as compared to the ground water and hence the effects of sorption must be taken into consideration while predicting the travel time of the contaminant to reach the ground water sources. This paper discusses the results of column test studies carried out in the laboratory under controlled conditions about the spreading of contaminant (Hexavalent chromium, Cr (VI through the clay mixed red soil at two different initial concentrations (800 mg/L and 4200 mg/L. The variations of the contaminant flow velocity and retardation factor for two different initial concentrations of contaminant were brought out and discussed. The contaminant flow velocity drastically coming down for a relative concentration of 0 to 0.2 and beyond this range, the contaminant flow velocity value is decreasing in a slow rate for both the lower and higher initial contaminant concentrations tested. At the lower relative concentration, the higher retardation factor was observed and it may be due to slowly filling the available sorption sites in the soil column.

  4. Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

    Science.gov (United States)

    Fang, Xuening; Zhao, Wenwu; Wang, Lixin; Feng, Qiang; Ding, Jingyi; Liu, Yuanxin; Zhang, Xiao

    2016-08-01

    Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80-500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120-140 and 480-500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80-220 cm); (ii) a transition layer (220-400 cm); and (iii) a stable layer (400-500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially

  5. Traffic-related trace elements in soils along six highway segments on the Tibetan Plateau: Influence factors and spatial variation.

    Science.gov (United States)

    Wang, Guanxing; Zeng, Chen; Zhang, Fan; Zhang, Yili; Scott, Christopher A; Yan, Xuedong

    2017-03-01

    The accumulation of traffic-related trace elements in soil as the result of anthropogenic activities raises serious concerns about environmental pollution and public health. Traffic is the main source of trace elements in roadside soil on the Tibetan Plateau, an area otherwise devoid of industrial emissions. Indeed, the rapid development of tourism and transportation in this region means it is becoming increasingly important to identify the accumulation levels, influence distance, spatial distribution, and other relevant factors influencing trace elements. In this study, 229 soil samples along six segments of the major transportation routes on the Tibetan Plateau (highways G214, S308, and G109), were collected for analysis of eight trace elements (Cr, Co, Ni, As, Cu, Zn, Cd, and Pb). The results of statistical analyses showed that of the eight trace elements in soils, Cu, Zn, Cd, and Pb were primarily derived from traffic. The relationship between the trace element accumulation levels and the distance from the roadside followed an exponential decline, with the exception of Segment 3, the only unpaved gravel road studied. In addition, the distance of influence from the roadside varied by trace element and segment, ranging from 16m to 144m. Background values for each segment were different because of soil heterogeneity, while a number of other potential influencing factors (including traffic volume, road surface material, roadside distance, land cover, terrain, and altitude) all had significant effects on trace-element concentrations. Overall, however, concentrations along most of the road segments investigated were at, or below, levels defined as low on the Nemero Synthesis index.

  6. Daily changes of radon concentration in soil gas under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Lara, Evelise G.; Oliveira, Arno Heeren de, E-mail: evelise.lara@gmail.com, E-mail: heeren@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Rocha, Zildete; Rios, Francisco Javier, E-mail: rochaz@cdtn.br, E-mail: javier@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This work aims at relating the daily change in the radon concentration in soil gas in a Red Yellow Acrisol (SiBCS) under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity. The {sup 226}Ra, {sup 232}Th, U content and permeability were also performed. The measurements of radon soil gas were carried out by using an AlphaGUARD monitor. The {sup 226}Ra activity concentration was made by Gamma Spectrometry (HPGe); the permeability was carried out using the RADON-JOK permeameter and ICP-MS analysis to {sup 232}Th and U content. The soil permeability is 5.0 x 10{sup -12}, which is considered average. The {sup 226}Ra (22.2 ± 0.3 Bq.m{sup -3}); U content (73.4 ± 3.6 Bq.kg{sup -1}) and {sup 232}Th content (55.3 ± 4.0 Bq.kg{sup -1}) were considered above of average concentrations, according to mean values for soils typical (~ 35.0 Bq.kg{sup -1}) by UNSCEAR. The results showed a difference of 26.0% between the highest and the lowest concentration of radon in soil gas: at midnight (15.5 ± 1.0 kBq.m{sup -3}) and 3:00 pm, the highest mean radon concentration (21.0 ± 1.0 kBq.m{sup -3}). The room temperature and surface soil temperature showed equivalent behavior and the surface soil temperature slightly below room temperature during the entire monitoring time. Nevertheless, the relative humidity showed the highest cyclical behavior, showing a higher relationship with the radon concentration in soil gas. (author)

  7. [Diurnal and Seasonal Dynamic Variation of Soil Respiration and Its Influencing Factors of Different Fenced Enclosure Years in Desert Steppec].

    Science.gov (United States)

    Cui, Hai; Zhang, Ya-hong

    2016-04-15

    The fenced measures could improve the ecological environment of degraded grassland, it's a main measure for restoration of degraded grassland vegetation in China. Soil respiration (Rs) is an important component of an ecosystem's carbon cycle and the main pathway for carbon moving from the ecosystem to the atmosphere. In order to explore soil respiration characteristics and influencing factors of the different fenced years in arid desert grassland, we continuously observed Rs rate and environmental factors in the growing season of fenced enclosure 11a, 7a and no fenced (CK) desert steppe in Ningxia. The results showed that: (1) Both the diurnal andseasonal variations of Rs rate showed a single asymmetric peak changing in fenced enclosure of 11 years, 7 years, CK desert steppe. On the daily scale, the maximum and minimum values of Rs rate were found in the periods of 12:00-16:00 and 00:00-06:00,respectively. On the seasonal variation scale, the maximum value of Rs rate occurred in August with suitable precipitation and temperature conditions. And the Rs rate of the growing season of different fenced enclosure years was in the order of 11a [0.143 g · (m² · h)⁻¹] > 7a [0.138 g · (m² · h)⁻¹] > CK [0.106 g · (m2 - h)⁻¹]. (2) According to statistical analysis, it indicated that R² rate had a significant exponential positive relationship with air and soil temperature in fenced enclosure of 11 years, 7 years, CK desert steppe (P soil surface temperature (R²: 0.408-0.413) > air temperature (R2: 0.355-0.376) > 5-20 cm soil temperature (R2: 0.263-0.394). The temperature sensitivity coefficient Q, increased gradually with the soil depth, and Q1, of different fenced enclosure years was showed as 11 a (2.728) > 7a (2.436) > CK (2.086). (3) A significant quadratic function model (P soil moisture content of fenced enclosure 11a, 7a and CK desert steppe in the whole growing season. Rs rate had a significant linear negative correlation with air carbon dioxide

  8. Climate and soil factors influencing seedling recruitment of plant species used for dryland restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Erickson, Todd E.; Martini, Dylan C.; Dixon, Kingsley W.; Merritt, David J.

    2016-06-01

    Land degradation affects 10-20 % of drylands globally. Intensive land use and management, large-scale disturbances such as extractive operations, and global climate change, have contributed to degradation of these systems worldwide. Restoring these damaged environments is critical to improving ecosystem services and functions, conserve biodiversity, and contribute to climate resilience, food security, and landscape sustainability. Here, we present a case study on plant species of the mining intensive semi-arid Pilbara region in Western Australia that examines the effects of climate and soil factors on the restoration of drylands. We analysed the effects of a range of rainfall and temperature scenarios and the use of alternative soil materials on seedling recruitment of key native plant species from this area. Experimental studies were conducted in controlled environment facilities where conditions simulated those found in the Pilbara. Soil from topsoil (T) stockpiles and waste materials (W) from an active mine site were mixed at different proportions (100 % T, 100 % W, and two mixes of topsoil and waste at 50 : 50 and 25 : 75 ratios) and used as growth media. Our results showed that seedling recruitment was highly dependent on soil moisture and emergence was generally higher in the topsoil, which had the highest available water content. In general, responses to the climate scenarios differed significantly among the native species which suggest that future climate scenarios of increasing drought might affect not only seedling recruitment but also diversity and structure of native plant communities. The use of waste materials from mining operations as growth media could be an alternative to the limited topsoil. However, in the early stages of plant establishment successful seedling recruitment can be challenging in the absence of water. These limitations could be overcome by using soil amendments but the cost associated to these solutions at large landscape scales

  9. Spatial distribution of soil organic carbon and its influencing factors in desert grasslands of the Hexi Corridor, northwest China.

    Science.gov (United States)

    Wang, Min; Su, Yongzhong; Yang, Xiao

    2014-01-01

    Knowledge of the distribution patterns of soil organic carbon (SOC) and factors that influence these patterns is crucial for understanding the carbon cycle. The objectives of this study were to determine the spatial distribution pattern of soil organic carbon density (SOCD) and the controlling factors in arid desert grasslands of northwest China. The above- and belowground biomass and SOCD in 260 soil profiles from 52 sites over 2.7×10(4) km2 were investigated. Combined with a satellite-based dataset of an enhanced vegetation index during 2011-2012 and climatic factors at different sites, the relationships between SOCD and biotic and abiotic factors were identified. The results indicated that the mean SOCD was 1.20 (SD:+/- 0.85), 1.73 (SD:+/- 1.20), and 2.69 (SD:+/- 1.91) kg m(-2) at soil depths of 0-30 cm, 0-50 cm, and 0-100 cm, respectively, which was smaller than other estimates in temperate grassland, steppe, and desert-grassland ecosystems. The spatial distribution of SOCD gradually decreased from the southeast to the northwest, corresponding to the precipitation gradient. SOCD increased significantly with vegetation biomass, annual precipitation, soil moisture, clay and silt content, and decreased with mean annual temperature and sand content. The correlation between BGB and SOCD was closer than the correlation between AGB and SOCD. Variables could together explain about 69.8%, 74.4%, and 78.9% of total variation in SOCD at 0-30 cm, 0-50 cm, and 0-100 cm, respectively. In addition, we found that mean annual temperature is more important than other abiotic factors in determining SOCD in arid desert grasslands in our study area. The information obtained in this study provides a basis for accurately estimating SOC stocks and assessing carbon (C) sequestration potential in the desert grasslands of northwest China.

  10. The Influence of Meteorological Parameters and Other Factors on Soil Radon Dynamics

    Science.gov (United States)

    Yakovleva, V. S.; Nagorsky, P. M.; Kondratyeva, A. G.; Mishina, N. V.

    2016-08-01

    The paper presents the results of the research in the degree of the effect of space weather meteorological parameters and factors on the dynamics of soil radon levels and α- and β-radiation flux densities in a seismically passive region. The cross-correlation analysis showed a significant correlation of β-radiation flux density with temperature in summer, and no correlation in winter. A significant relation between α- and β-radiation flux densities and pressure within the intra-annual range was not observed. The investigation of the high-intensity precipitation effect on radon volumetric activity and α- and β-radiation flux densities showed their abnormal increase. The dependence of the anomaly duration on the depth was revealed. The abnormal jumps in α- and β-radiation flux densities data series occur in the snow-melting periods as well. Low-intensity precipitations significantly violate the standard "diurnal variations" of α- and β-radiation soil fluxes and radon volumetric activity. Fourier analysis showed the diurnal (24 hours) and semidiurnal (12 hours) harmonics for the observed radiation values at a depth of 0.5 m. The obtained results can be used for interpretation of the data on the soil radon monitoring in order to predict earthquakes, etc.

  11. Active microorganisms in forest soils differ from the total community yet are shaped by the same environmental factors: the influence of pH and soil moisture.

    Science.gov (United States)

    Romanowicz, Karl J; Freedman, Zachary B; Upchurch, Rima A; Argiroff, William A; Zak, Donald R

    2016-10-01

    Predicting the impact of environmental change on soil microbial functions requires an understanding of how environmental factors shape microbial composition. Here, we investigated the influence of environmental factors on bacterial and fungal communities across an expanse of northern hardwood forest in Michigan, USA, which spans a 500-km regional climate gradient. We quantified soil microbial community composition using high-throughput DNA sequencing on coextracted rDNA (i.e. total community) and rRNA (i.e. active community). Within both bacteria and fungi, total and active communities were compositionally distinct from one another across the regional gradient (bacteria P = 0.01; fungi P soil moisture, pH, SOM carboxyl content, as well as C and N concentration. Our study highlights the importance of distinguishing between metabolically active microorganisms and the total community, and emphasizes that the same environmental factors shape the total and active communities of bacteria and fungi in this ecosystem. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Influence of Soil Factors on the Stereoselective Fate of a Novel Chiral Insecticide, Paichongding, in Flooded Paddy Soils.

    Science.gov (United States)

    Li, Juying; Huang, Tuo; Li, Lizong; Ding, Tengda; Zhu, Hong; Yang, Bo; Ye, Qingfu; Gan, Jay

    2016-11-02

    In this study, the fate of paichongding was investigated in three soils with contrasting soil properties. In general, low soil pH has the potential to retard the mineralization and promote the dissipation of paichongding and the formation of its primary transformation product and to accelerate the formation of bound residue. The dissipation of paichongding stereoisomers was very fast and diastereoselective. This selectivity was found only between diastereomers and not between enantiomers and was observed to be soil dependent. In the acidic soil, the enantiomers (5R,7R)- and (5S,7S)-paichongding were degraded more quickly than (5R,7S)- and (5S,7R)-paichongding, whereas a contrary trend was observed in the neutral soil, and such selectivity did not occur in the alkaline soil. The OM and clay contents also played important roles in the fate of paichongding. This effect of soil properties should be considered in risk assessment of chiral pesticides and their application in the field.

  13. Influence of different biological factors on the character of biodegradation of oil pollution soils

    OpenAIRE

    Lifshits, S. H.; Chalaya, O. N.; Glaznetsova, Ju. S.; Zueva, I. N.; Лифшиц, С. Х.; Чалая, О. Н.; Глязнецова, Ю. С.; Зуева, И. Н.

    2012-01-01

    The results of laboratory and field experiments on remediation of oil pollution soils showed that for the effective restoration of soils it is possible to recommend performing works with the application of microorganism-plant complexes i.e. combining introduction into contaminated soil of hydrocarbon degradating bacteria with plant seeding.

  14. Toluene removal from sandy soils via in situ technologies with an emphasis on factors influencing soil vapor extraction.

    Science.gov (United States)

    Amin, Mohammad Mehdi; Hatamipour, Mohammad Sadegh; Momenbeik, Fariborz; Nourmoradi, Heshmatollah; Farhadkhani, Marzieh; Mohammadi-Moghadam, Fazel

    2014-01-01

    The integration of bioventing (BV) and soil vapor extraction (SVE) appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC) and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE) including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5%) of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing) after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater.

  15. Toluene Removal from Sandy Soils via In Situ Technologies with an Emphasis on Factors Influencing Soil Vapor Extraction

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Amin

    2014-01-01

    Full Text Available The integration of bioventing (BV and soil vapor extraction (SVE appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5% of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater.

  16. Toluene Removal from Sandy Soils via In Situ Technologies with an Emphasis on Factors Influencing Soil Vapor Extraction

    Science.gov (United States)

    Amin, Mohammad Mehdi; Hatamipour, Mohammad Sadegh; Nourmoradi, Heshmatollah; Farhadkhani, Marzieh; Mohammadi-Moghadam, Fazel

    2014-01-01

    The integration of bioventing (BV) and soil vapor extraction (SVE) appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC) and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE) including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5%) of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing) after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater. PMID:24587723

  17. A Cross-Site Comparison of Factors Influencing Soil Nitrification Rates in Northeastern USA Forested Watersheds

    Science.gov (United States)

    Donald S. Ross; Beverley C. Wemple; Austin E. Jamison; Guinevere Fredriksen; James B. Shanley; Gregory B. Lawrence; Scott W. Bailey; John L. Campbell

    2009-01-01

    Elevated N deposition is continuing on many forested landscapes around the world and our understanding of ecosystem response is incomplete. Soil processes, especially nitrification, are critical. Many studies of soil N transformations have focused on identifying relationships within a single watershed but these results are often not transferable. We studied 10 small...

  18. Factors influencing soil aggregation and particulate organic matter responses to bioenergy crops across a topographic gradient

    Science.gov (United States)

    Todd A. Ontl; Cynthia A. Cambardella; Lisa A. Schulte; Randall K. Kolka

    2015-01-01

    Bioenergy crops have the potential to enhance soil carbon (C) pools from increased aggregation and the physical protection of organic matter; however, our understanding of the variation in these processes over heterogeneous landscapes is limited. In particular, little is known about the relative importance of soil properties and root characteristics for the physical...

  19. The biological factors influence on the conversion of mineral components of Extremely Arid Desert Soils (Kazakhstan)

    Science.gov (United States)

    Kutovaya, Olga; Vasilenko, Elena; Lebedeva, Marina; Tkhakakhova, Azida

    2013-04-01

    Extremely arid soils of stony deserts (hamadas) along the southern periphery of the Ili Depression are considered to be analogous to extremely arid soils of Mongolia, also named as "ultra-arid primitive gray-brown soils." In general, the morphology of extremely arid soils of hamadas in the Ili Depression is similar to that of the soils of stony deserts in other parts of the world, including the Gobi, Atacama, and Tarim deserts. The diagnostics of the active communities of microorganisms were performed according to the method of Rybalkina-Kononenko. The exact identification of the living forms of microorganisms to the species level is not always possible with the use of this method. However, it allows us to study the physiological role of the microorganisms and their ecological functions, including the relationships with the soil matrix and other organisms. In particular, it is possible to estimate the contribution of the microorganisms to the transformation of mineral soil components. The obtained materials allow us to conclude that the extremely arid desert soils are characterized by the very high biological activity during short periods of the increased soil moistening after rare and strong rains. The diversity of living forms is very considerable; both prokaryotes (cyanobacteria, actinomycetes, and iron bacteria) and protists (green algae, diatoms, and dinoflagellates) are developed in the soil. Thus, during a short period after the rains, these microorganisms pass from the stage of anabiosis to the stage of active growth and reproduction. Then, upon drying of the soil, the biotic activity of the soil slows down and, finally, terminates. The organisms remain in the state of anabiosis until the next rain. During the period of active growth, the microorganisms compose a specific consortium of different species and exert a profound impact on the soil properties. They participate in the transformation of the soil minerals with the formation of amorphous substances

  20. Environmental factors influencing soil testate amoebae in herbaceous and shrubby vegetation along an altitudinal gradient in subarctic tundra (Abisko, Sweden).

    Science.gov (United States)

    Tsyganov, Andrey N; Milbau, Ann; Beyens, Louis

    2013-05-01

    Shifts in community composition of soil protozoa in response to climate change may substantially influence microbial activity and thereby decomposition processes. However, effects of climate and vegetation on soil protozoa remain poorly understood. We studied the distribution of soil testate amoebae in herbaceous and shrubby vegetation along an altitudinal gradient (from below the treeline at 500 m to the mid-alpine region at 900 m a.s.l.) in subarctic tundra. To explain patterns in abundance, species diversity and assemblage composition of testate amoebae, a data set of microclimate and soil chemical characteristics was collected. Both elevation and vegetation influenced the assemblage composition of testate amoebae. The variation was regulated by interactive effects of summer soil moisture, winter soil temperature, soil pH and nitrate ion concentrations. Besides, soil moisture regulated non-linear patterns in species richness across the gradient. This is the first study showing the effects of winter soil temperatures on species composition of soil protozoa. The effects could be explained by specific adaptations of testate amoebae such as frost-resistant cysts allowing them to survive low winter temperatures. We conclude that the microclimate and soil chemical characteristics are the main drivers of changes in protozoan assemblage composition in response to elevation and vegetation.

  1. INFLUENCES OF SLOPE GRADIENT ON SOIL EROSION

    Institute of Scientific and Technical Information of China (English)

    刘青泉; 陈力; 李家春

    2001-01-01

    The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows , and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory. Furthermore, the critical slope gradient of erosion was driven. The analysis shows that the critical slope gradient of soil erosion is dependent on grain size , soil bulk density , surface roughness, runoff length, net rain excess, and the friction coefficient of soil, etc. The critical slope gradient has been estimated theoretically with its range between 41. 5 °~ 50°.

  2. Regional accumulation characteristics of cadmium in vegetables: Influencing factors, transfer model and indication of soil threshold content.

    Science.gov (United States)

    Yang, Yang; Chen, Weiping; Wang, Meie; Peng, Chi

    2016-12-01

    A regional investigation in the Youxian prefecture, southern China, was conducted to analyze the impact of environmental factors including soil properties and irrigation in conjunction with the use of fertilizers on the accumulation of Cd in vegetables. The Cd transfer potential from soil to vegetable was provided by the plant uptake factor (PUF), which varied by three orders of magnitude and was described by a Gaussian distribution model. The soil pH, content of soil organic matter (SOM), concentrations of Zn in the soil, pH of irrigation water and nitrogenous fertilizers contributed significantly to the PUF variations. A path model analysis, however, revealed the principal control of the PUF values resulted from the soil pH, soil Zn concentrations and SOM. Transfer functions were developed using the total soil Cd concentrations, soil pH, and SOM. They explained 56% of the variance for all samples irrespective of the vegetable genotypes. The transfer functions predicted the probability of exceeding China food safety standard concentrations for Cd in four major consumable vegetables under different soil conditions. Poor production practices in the study area involved usage of soil with pH values ≤ 5.5, especially for the cultivation of Raphanus sativus L., even with soil Cd concentrations below the China soil quality standard. We found the soil standard Cd concentrations for cultivating vegetables was not strict enough for strongly acidic (pH ≤ 5.5) and SOM-poor (SOM ≤ 10 g kg(-1)) soils present in southern China. It is thus necessary to address the effect of environmental variables to generate a suitable Cd threshold for cultivated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Online Soil Science Lesson 3: Soil Forming Factors

    Science.gov (United States)

    This lesson explores the five major factors of soil formation, namely: 1) climate; 2) organisms; 3) time; 4) topography; and 5) parent material and their influence in forming soil. The distinction between active and passive factors, moisture and temperature regimes, organism and topographic influen...

  4. Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity.

  5. Lead (Pb) and other metals in New York City community garden soils: factors influencing contaminant distributions.

    Science.gov (United States)

    Mitchell, Rebecca G; Spliethoff, Henry M; Ribaudo, Lisa N; Lopp, Donna M; Shayler, Hannah A; Marquez-Bravo, Lydia G; Lambert, Veronique T; Ferenz, Gretchen S; Russell-Anelli, Jonathan M; Stone, Edie B; McBride, Murray B

    2014-04-01

    Urban gardens provide affordable fresh produce to communities with limited access to healthy food but may also increase exposure to lead (Pb) and other soil contaminants. Metals analysis of 564 soil samples from 54 New York City (NYC) community gardens found at least one sample exceeding health-based guidance values in 70% of gardens. However, most samples (78%) did not exceed guidance values, and medians were generally below those reported in NYC soil and other urban gardening studies. Barium (Ba) and Pb most frequently exceeded guidance values and along with cadmium (Cd) were strongly correlated with zinc (Zn), a commonly measured nutrient. Principal component analysis suggested that contaminants varied independently from organic matter and geogenic metals. Contaminants were associated with visible debris and a lack of raised beds; management practices (e.g., importing uncontaminated soil) have likely reduced metals concentrations. Continued exposure reduction efforts would benefit communities already burdened by environmental exposures.

  6. Discussion on wind factor influencing the distribution of biological soil crusts on surface of sand dunes

    Institute of Scientific and Technical Information of China (English)

    YongSheng Wu; Hasi Erdun; RuiPing Yin; Xin Zhang; Jie Ren; Jian Wang; XiuMin Tian; ZeKun Li; HengLu Miao

    2013-01-01

    Biological soil crusts are widely distributed in arid and semi-arid regions, whose formation and development have an important impact on the restoration process of the desert ecosystem. In order to explore the relationship between surface airflow and development characteristics of biological soil crusts, we studied surface airflow pattern and development characteristics of biological soil crusts on the fixed dune profile through field observation. Results indicate that the speed of near-surface airflow is the lowest at the foot of windward slope and the highest at the crest, showing an increasing trend from the foot to the crest. At the leeward side, although near-surface airflow increases slightly at the lower part of the slope after an initial sudden decrease at upper part of the slope, its overall trend decreases from the crest. Wind velocity variation coefficient varied at different heights over each observation site. The thickness, shear strength of biological soil crusts and percentage of fine particles at crusts layer decreased from the slope foot to the upper part, showing that biological soil crusts are less developed in high wind speed areas and well developed in low wind speed areas. It can be seen that there is a close relationship between the distribution of biological soil crusts in different parts of the dunes and changes in airflow due to geomorphologic variation.

  7. Study of processes influencing bioavailability of pesticides in wood-soil systems: Effect of different factors.

    Science.gov (United States)

    Marín-Benito, J M; Herrero-Hernández, E; Rodríguez-Cruz, M S; Arienzo, M; Sánchez-Martín, M J

    2017-05-01

    Lignocellulosic wastes and by-products containing lignin are now available in large amounts from forestry and industrial activities, and could be promising organic materials for the biosorption of pesticides by soils in order to reduce point-source pollution. Adding these materials to soil requires understanding the process of pesticide sorption-desorption by wood-soils, as sorption capacity could increase, with changes in pesticide bioavailability and final fate. The objective of this work was to study the effect that pine and oak wood added to soils had on the sorption/desorption of the pesticides linuron, alachlor, and metalaxyl. Experiments were conducted with two sandy loam and sandy clay soils each amended with two wood doses (5% and 50%) after different incubation times (0, 5 and 12 months). A low wood dose (5%) had no significant impact on the sorption (Kf) of alachlor, but Kf increased for linuron (up to 5.4-1.7 times) and metalaxyl (up to 4.4 and 8.6 times) in all wood-soil systems. The results were not significantly different after different incubation times. The desorption results indicated that wood decreases the sorption irreversibility of alachlor, and increases that of linuron and metalaxyl, with a varying effect of the wood-soil incubation time. The addition of a high wood dose to soil (50%) was more significant for increasing the sorption of all the pesticides, and the sorbed amounts remaining after desorption (>49% for linuron, >33% for alachlor and >6% for metalaxyl), although there was no apparent discrimination between the two types of woods. The role of the nature of the organic carbón (Koc values) for sorption was evidenced for alachlor and metalaxyl, but not for linuron. These outcomes are of interest for extending wood application to soil as a barrier for avoiding environmental risk by point-source pollution due to the use and management of pesticides in farming systems. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Factors Influencing Spatial Variability in Nitrogen Processing in Nitrogen-Saturated Soils

    Directory of Open Access Journals (Sweden)

    Frank S. Gilliam

    2001-01-01

    Full Text Available Nitrogen (N saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF, West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4 and WS4 (untreated control. Samples of forest floor material (O1 horizon and mineral soil (to a 5-cm depth were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C, lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3- to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C, followed by 1 NKCl extraction and analysis for NH4+ and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of

  9. Multi-factors influencing the spatial distribution of polycyclic aromatic hydrocarbons in soils surrounding drinking water protection zone.

    Science.gov (United States)

    Jiao, Wentao; Wang, Tieyu; Lu, Yonglong; Chang, Andrew; Chen, Weiping

    2013-08-01

    We selected the Guanting Reservoir in Beijing, China as a case where an industrial area locates on the upwind corner to study the influence of human activities and natural processes on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils. Soil PAH concentrations in the study area follow a log-normal probability distribution function, suggesting that distribution of PAH in soils was affected by human activities. Distribution of PAHs in soils was significantly affected by the point source that high PAH concentrations were observed in near industrial area with an obvious declining trend from the northwest to the southeast which was the prevailing wind direction in this area. Away from the influence of point source, distribution of PAHs in soils was found to significantly correlate with total organic carbon content, while the influences of agricultural land uses and type of soil texture on the total soil PAHs contents and ring compositions were quite limited. The results can provide some evidences and data on the pollutant accumulation in drink water protection area influenced by natural processes and human activities.

  10. [Analysis of soil respiration and influence factors in wheat farmland under conservation tillage in southwest hilly region].

    Science.gov (United States)

    Zhang, Sai; Zhang, Xiao-Yu; Wang, Long-Chang; Luo, Hai-Xiu; Zhou, Hang-Fei; Ma, Zhong-Lian; Zhang, Cui-Wei

    2013-07-01

    In order to investigate the effect of conservation tillage on soil respiration in dry cropping farmland in southwest purple hilly region, the LI6400-09 respiratory chamber was adopted in the experiment conducted in the experimental field in Southwest University in Beibei, Chongqing. The respiration and the hydrothermal and biotic factors of soil were measured and analyzed during the growth period of wheat in the triple intercropping system of wheat/maize/soybean. There were four treatments including T (traditional tillage), R (ridge tillage), TS (traditional tillage + straw mulching) and RS (ridge tillage + straw mulching), which were all in triplicates. The results indicated that the soil respiration rate changed in the range of 1.100-2.508 micromol x (m2 x s)(-1) during the reproductive growth stage of wheat. There were significant differences in soil respiration rate among different treatments, which could be ranked as RS > R > TS > T. The soil temperature in the 10cm layer was ranked as T > R > TS > RS. The relationship between soil respiration and soil temperature fitted well with an exponential function, in which the Q10 values were 1.25, 1.20, 1.31 and 1.26, respectively. The soil moisture in the 5cm layer was ranked as TS > RS > T > R. The best fitting model between soil moisture and soil respiration was a parabolic curve, indicating the presence of soil moisture with the strongest soil respiration. The response threshold of wheat to soil moisture was 14.80%-17.47% during the reproductive stage. The dominant groups of soil animals were Collembola and Acarina, which were correlated with soil respiration to some extent. The correlation was high in the treatments T and R, ranged from 0.669-0.921, whereas there was no remarkable correlation in the other treatments.

  11. The mechanical stability of clay soils as influenced by the moisture conditions and some other factors

    NARCIS (Netherlands)

    Koenigs, F.F.R.

    1961-01-01

    To test whether flocculation is a prerequisite for granulation and a waterstable structure or whether drying (close contact) is sufficient, homoionic suspensions were prepared from pure sodium, potassium, calcium or magnesium montmorillonite, illite or kaolinite and from the respective soil clays.

  12. Characterizing differences in the phosphorus activation coefficient of three typical cropland soils and the influencing factors under long-term fertilization.

    Science.gov (United States)

    Wu, Qihua; Zhang, Shuxiang; Zhu, Ping; Huang, Shaomin; Wang, Boren; Zhao, LinPing; Xu, Minggang

    2017-01-01

    The phosphorus activation coefficient (PAC, the ratio of available P to total P) is an important indicator of soil P availability and the transformation of P fractions. Understanding the details of the PAC is useful to estimate soil available P status and to provide P management guidance. In this research, soils from five long-term (23 years) fertilization treatments in three croplands were selected to examine the relationships between the PAC and P fractions and to analyse the influencing factors. PAC was affected by both soil types and fertilization treatments. Compared to the unfertilized control (CK) treatment, long-term P application significantly increased the PAC, all of the inorganic P (Pi) fractions and most of the organic P (Po) fractions in all the three soils, particularly in chemical fertilizer combined with manure treatment (NPKM). The PAC was significantly correlated to all of the Pi fractions proportions (Pvariance partitioning analysis showed that more variance of PAC is explained by soil factors (29.53%) than by P input (0.19%) and climate (0.25%) factors. Our findings demonstrate that P application increased the PAC by changing the Co content and the proportion of P fractions. Moreover, soil factors were the most important drivers of P transformations, and NPKM was optimal for improving soil fertility in Chinese croplands.

  13. The Heterogeneity and Its Influencing Factors of Soil Nutrients in Peak-Cluster Depression Areas of Karst Region

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; CHEN Hong-song; WANG Ke-lin; SU Yi-rong; ZHANG Ji-guang; YI Ai-jun

    2007-01-01

    By selecting a typical peak-cluster depression area of karst region in Southwest China, we evaluated the effect of land use types and topographic factors on soil nutrients. Grid and line sampling methods were used to sample soil in depression and slope lands respectively, and classical statistical tools were applied to analyze the spatial variability character of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK), pH, and C/N. It was found that land use type was the dominant factor that effected the spatial heterogeneity of SOC, TN, TP, TK, AN, and AP. The content of SOC, TN, and AN decreased with the increase of land use intensity. Due to high fertilizer input, TP and AP in tillage fields were higher than those in the other land use types. TK had no obvious change trend among various land use types. Topographic factors had a significant effect on SOC, TN, TP, AN, AP, AK, and pH. Habitat factor was the dominant factor that effected AK. Altitude factor was the dominant factor for pH. However, all of these factors had no significant effect on C/N. Tillage practice had important effect on soil nutrients loss and soil degradation in the fragile karst ecosystem, and the input of organic manure should be increased in this region.

  14. [Influence of soil factors on species diversity of arbuscular mycorrhizal (AM) fungi in Stipa steppe of Tibet Plateau].

    Science.gov (United States)

    Peng, Yue-lin; Yang, Min-na; Cai, Xiao-bu

    2010-05-01

    This study was based on the isolation and identification of arbuscular mycorrhizal (AM) fungi collected from the alpine Stipa steppe of north Tibet, and focused on the influence of soil texture, pH, organic matter, and available P on the spore density, isolation frequency, relative abundance, importance value, species diversity, and species evenness of the AM fungi. In the rhizosphere soil of the steppe, a total of 15 species AM fungi were isolated and identified, including 9 species of Glomus, 6 species of Acaulospora, and 1 species of Scutellospora. Among them, Glomus and Acaulospora were the dominant genera, and Glomus claroideum and Acaulospora laevis were the dominant species. In the soils with different texture, the spore density, isolation frequency, relative abundance, and importance value of the AM fungi all showed a trend of Glomus > Acaulospora > Scutellospora. Soil pH value had no significant effects on the species composition of AM fungi. However, the isolation frequency, relative abundance, and importance value of Glomus and Acaulospora showed an increasing trend with increasing soil pH, while Scutellospora showed the contrary trend. In the soils with different organic matter content, the spore density of AM fungi all showed a trend of Glomus > Acaulospora > Scutellospora, while the distribution of AM fungi had no definite pattern. The species richness and spore density of AM fungi were less affected by the soil available P content, but the species diversity and evenness showed an increasing trend with the increasing content of soil available P.

  15. The role of soil biogeochemistry in wine taste: Soil factors influencing grape elemental composition, photosynthetic biomarkers and Cu/Zn isotopic signature of Vitis vinifera

    Science.gov (United States)

    Blotevogel, Simon; Oliva, Priscia; Darrozes, José; Viers, Jérôme; Audry, Stéphane; Courjault-Radé, Pierre; Orgogozo, Laurent; Le Guedard, Marina; Schreck, Eva

    2015-04-01

    Understanding the influence of soil composition in wine taste is of great economic and environmental interest in France and around the world. Nevertheless the impact of soil composition on wine taste is still controversially discussed. Since inorganic soil components do not have a proper taste and do not enter the plant anyway, their influence needs to be induced by nutrient absorption and its impact on plant functioning and grape composition. Indeed recent development of geological tracers of origin proof the existence of soil chemical and isotopic signatures in wine. However, type and scale of the impact of soil composition on wine taste are not well understood yet, and little experimental evidence exists due to the complexity of mechanisms involved. Thus, to provide evidence for the impact of soil composition on grape composition and potentially wine taste, we studied soil and plant material from two relevant vineyards (Soave, Italia). On those two directly adjacent vineyards, two different wines are produced with the same plant material and cultivation techniques. The vineyards only differ by their underlying bedrock - limestone versus basaltic rock - and thus present suitable conditions for investigating the impact of soil composition on grapes and wine. Pedological and mineralogical parameters were analyzed for the two vineyards whereas chemical extractions (citrate, CaCl2) were performed to determine nutrient bioavailability in both soils. Elemental compositions were determined by ICP-MS analyses in different compartments (soils, vine leaves and grapes). Isotopic fractionation of Cu and Zn was investigated in various samples as source tracers and in order to better understand fractionation mechanisms involved. Finally, plant health was studied using the Omega-3 biomarker which determines the fatty acid composition in vine leaves, directly involved in photosynthetic processes. Results show that the vineyards are characterized by two different soil types due

  16. Spatial distribution of soil cadmium and its influencing factors in peri-urban farmland: a case study in the Jingyang District, Sichuan, China.

    Science.gov (United States)

    Li, Bing; Xiao, Rui; Wang, Changquan; Cao, Linhai; Zhang, Yi; Zheng, Shunqiang; Yang, Lan; Guo, Yong

    2017-01-01

    Semi-agricultural ecosystems in peri-urban areas are susceptible to contamination. The spatial distribution and influencing factors of such pollution are unclear and poorly constrained in many areas worldwide. Therefore, studying the problems of soil pollution in peri-urban areas is critical for environmental management and agricultural production. In this paper, with cadmium (Cd) as the target pollutant, the spatiotemporal variations of soil cadmium pollution and the relative importance of the affecting factors were analyzed at a peri-urban area from the Jingyang District, Sichuan, China. Statistical results showed that the farmland in the study area could be considered moderately soil Cd-polluted, under the dual influence of natural factors and human activity. In particular, the soil Cd concentration in Tianyuan and Bajiaojing exceeded 0.5 mg kg(-1), for intensive industrial enterprises are distributed in these areas. Correspondingly, the geoaccumulation index also showed that the contamination of Cd in this area was moderately polluted. Moreover, the ecological risk index was 80% in the study area, indicating that the soil Cd pollution potential risk was moderate to high. High geological background values (soil Cd = 0.29 mg kg(-1)), river migration, industrial enterprises, and traffic significantly influenced soil Cd pollution, with natural geological factors playing greater roles. The significant horizontal-spatial effective distances away from Shiting River, Deyang-Aba Highway, and chemical plants were 200, 400, and 100 m, respectively. These results will be useful in guiding farmland cultivation and pollution remediation effectively in the peri-urban areas.

  17. Regional, household and individual factors that influence soil transmitted helminth reinfection dynamics in preschool children from rural indigenous Panama.

    Directory of Open Access Journals (Sweden)

    Carli M Halpenny

    Full Text Available BACKGROUND: Few studies have investigated the relative influence of individual susceptibility versus household exposure factors versus regional clustering of infection on soil transmitted helminth (STH transmission. The present study examined reinfection dynamics and spatial clustering of Ascaris lumbricoides, Trichuris trichiura and hookworm in an extremely impoverished indigenous setting in rural Panamá over a 16 month period that included two treatment and reinfection cycles in preschool children. METHODOLOGY/PRINCIPLE FINDINGS: Spatial cluster analyses were used to identify high prevalence clusters for each nematode. Multivariate models were then used (1 to identify factors that differentiated households within and outside the cluster, and (2 to examine the relative contribution of regional (presence in a high prevalence cluster, household (household density, asset-based household wealth, household crowding, maternal education and individual (age, sex, pre-treatment eggs per gram (epg feces, height-for-age, latrine use factors on preschool child reinfection epgs for each STH. High prevalence spatial clusters were detected for Trichuris and hookworm but not for Ascaris. These clusters were characterized by low household density and low household wealth indices (HWI. Reinfection epg of both hookworm and Ascaris was positively associated with pre-treatment epg and was higher in stunted children. Additional individual (latrine use as well as household variables (HWI, maternal education entered the reinfection models for Ascaris but not for hookworm. CONCLUSIONS/SIGNIFICANCE: Even within the context of extreme poverty in this remote rural setting, the distinct transmission patterns for hookworm, Trichuris and Ascaris highlight the need for multi-pronged intervention strategies. In addition to poverty reduction, improved sanitation and attention to chronic malnutrition will be key to reducing Ascaris and hookworm transmission.

  18. Spatial Heterogeneity of Soil Moisture and the Scale Variability of Its Influencing Factors: A Case Study in the Loess Plateau of China

    Directory of Open Access Journals (Sweden)

    Mingyue Zhao

    2013-08-01

    mosaic patterns. For example, low-density woodland or wild grassland would be appropriate for sites with low soil moisture content, such as upper slope, high elevation and steep slope sites. A stepwise regression analysis indicated that the dominant factor controlling the spatial variability of soil moisture values varied at different scales. At the small watershed scale, the order of significance for the influence of environmental factors on soil moisture values was as follows: land use type, slope, relative elevation and vegetation cover. The order of significance at the watershed scale was also determined: location on the hill slope, vegetation cover, slope, relative elevation and sine of the aspect. This result indicated that the influence of different environmental factors on soil moisture variability was dependent on the scale. The forecasting capability of regression models for soil moisture decreases from the small watershed scale to the watershed scale. This study could provide a reference for relevant scale transformation studies and offer guidance for water resource management and vegetation restoration approaches on the Loess Plateau.

  19. General assessment of the influence of a municipal landfill site and environmental factors on the occurrence of keratinolytic fungi in soil.

    Science.gov (United States)

    Ulfig, K; Płaza, G; Sztyler, A; Bronder, J; Terakowski, M; Guarro, J

    2000-01-01

    The study was to generally determine the influence of a municipal landfill site and environmental factors on the distribution of keratinolytic fungi in soil. The landfill site in Sosnowiec was selected for examination. Keratinolytic fungi occurred abundantly in soils of the landfill site examined and its surrounding area. Of 495 soil samples (Petri dishes) examined, 379 (76.56%) were found to be positive for keratinolytic fungi. Altogether, 1131 strains from 26 species were isolated from the samples. Among the fungi, some species with pathogenic properties (Microsporum racemosum, M. cookei, M. gypseum, Aphanoascus fulvescens and Scopulariopsis brevicaulis) were recorded. The influence of environmental factors on the qualitative and quantitative composition of keratinolytic fungi in the soils was complex. Among these factors, exchangeable acidity (pH in 1 M KCl, in particular), faecal bacterial contamination and the level of water deficit in soil were the most important. The conclusion has been drawn that municipal landfill sites are the sources of potentially pathogenic fungi with keratinolytic properties.

  20. Vertical Profiles of Soil Water Content as Influenced by Environmental Factors in a Small Catchment on the Hilly-Gully Loess Plateau

    Science.gov (United States)

    Wang, Bing; Wen, Fenxiang; Wu, Jiangtao; Wang, Xiaojun; Hu, Yani

    2014-01-01

    Characterization of soil water content (SWC) profiles at catchment scale has profound implications for understanding hydrological processes of the terrestrial water cycle, thereby contributing to sustainable water management and ecological restoration in arid and semi-arid regions. This study described the vertical profiles of SWC at the small catchment scale on the hilly and gully Loess Plateau in Northeast China, and evaluated the influences of selected environmental factors (land-use type, topography and landform) on average SWC within 300 cm depth. Soils were sampled from 101 points across a small catchment before and after the rainy season. Cluster analysis showed that soil profiles with high-level SWC in a stable trend (from top to bottom) were most commonly present in the catchment, especially in the gully related to terrace. Woodland soil profiles had low-level SWC with vertical variations in a descending or stable trend. Most abandoned farmland and grassland soil profiles had medium-level SWC with vertical variations in varying trends. No soil profiles had low-level SWC with vertical variations in an ascending trend. Multi-regression analysis showed that average SWC was significantly affected by land-use type in different soil layers (0–20, 20–160, and 160–300 cm), generally in descending order of terrace, abandoned farmland, grassland, and woodland. There was a significant negative correlation between average SWC and gradient along the whole profile (Pcatchments on the Loess Plateau as well as in other complex terrains with similar settings. PMID:25313829

  1. Remediation of polybrominated diphenyl ethers in soil using Ni/Fe bimetallic nanoparticles: Influencing factors, kinetics and mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yingying [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Fang, Zhanqiang, E-mail: zhqfang@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Cheng, Wen [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Tsang, Pokeung Eric [Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong 00852 (China); Zhao, Dongye [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States)

    2014-07-01

    Polybrominated diphenyl ethers (PBDEs) are commonly used as additive flame retardants in all kinds of electronic products. PBDEs are now ubiquitous in the environment, with soil as a major sink, especially in e-waste recycling sites. This study investigated the degradation of decabromodiphenyl ether (BDE209) in a spiked soil using Ni/Fe bimetallic nanoparticles. The results indicated that Ni/Fe bimetallic nanoparticles are able to degrade BDE209 in soil at ambient temperature and the removal efficiency can reach 72% when an initial pH of 5.6 and at a Ni/Fe dosage of 0.03 g/g. A declining trend in degradation was noticed with decreasing Ni loading and increasing of initial BDE209 concentration. The degradation products of BDE209 were analyzed by GC-MS, which showed that the degradation of BDE209 was a process of stepwise debromination from nBr to (n − 1)Br. And a possible debromination pathway was proposed. At last, the degradation process was analyzed as two-step mechanism, mass transfer and reaction. This current study shows the potential ability of Ni/Fe nanoparticles to be used for removal of PBDEs in contaminated soil. - Highlights: • Ni/Fe bimetallic nanoparticles could effectively degradate BDE209 in soil. • The effects of various factors on remediation of BDE209 in soil using Ni/Fe were considered. • The degradation of BDE209 was a process of stepwise debromination from nBr to (n − 1)Br. • A possible debromination pathway and mechanism about removal of BDE209 in soil were proposed.

  2. Geometric factor and influence of sensors in the establishment of a resistivity-moisture relation in soil samples

    Science.gov (United States)

    López-Sánchez, M.; Mansilla-Plaza, L.; Sánchez-de-laOrden, M.

    2017-10-01

    Prior to field scale research, soil samples are analysed on a laboratory scale for electrical resistivity calibrations. Currently, there are a variety of field instruments to estimate the water content in soils using different physical phenomena. These instruments can be used to develop moisture-resistivity relationships on the same soil samples. This assures that measurements are performed on the same material and under the same conditions (e.g., humidity and temperature). A geometric factor is applied to the location of electrodes, in order to calculate the apparent electrical resistivity of the laboratory test cells. This geometric factor can be determined in three different ways: by means of the use of an analytical approximation, laboratory trials (experimental approximation), or by the analysis of a numerical model. The first case, the analytical approximation, is not appropriate for complex cells or arrays. And both, the experimental and numerical approximation can lead to inaccurate results. Therefore, we propose a novel approach to obtain a compromise solution between both techniques, providing a more precise determination of the geometrical factor.

  3. The Influence of Soil Environmental Factors on the Fruit Quality%土壤环境因素对水果果实品质的影响

    Institute of Scientific and Technical Information of China (English)

    高洪娜

    2015-01-01

    简要阐述了土壤环境因素(土壤pH值和土壤营养元素)对水果果实品质的影响。大多数果树都喜欢微酸性土壤,但pH值较低的土壤不利于果实品质的形成,土壤中有机质的含量对果实品质的形成起到明显的促进作用,而矿质营养与果实品质间的关系较为错综复杂。为此对今后的研究提出了几点建议。%This paper briefly stated the influence of soil environment factors(soil pH value and soil nutrient element) on the fruit quality .Most fruit trees liked little acid soil ,but soil with the lower pH value had an adverse effect on the formation of fruit quality ,The content of soil organic matters had an marked promoting effect on the formation of fruit quality ,however the relationship between mineral nutrition and fruit quality was complex .Therefore ,this paper put forward some suggestions about future research .

  4. Factors affecting soil cohesion

    Science.gov (United States)

    Soil erodibility is a measure of a soil’s resistance against erosive forces and is affected by both intrinsic (or inherent) soil property and the extrinsic condition at the time erodibility measurement is made. Since soil erodibility is usually calculated from results obtained from erosion experimen...

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

    Science.gov (United States)

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

    2013-10-15

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

  6. 岩土力学参数影响因素的分析%Analysis of Factors Influencing the Mechanical Parameters of Rock and Soil

    Institute of Scientific and Technical Information of China (English)

    赵玉

    2015-01-01

    With the development of civil engineering, the mechanical parameters of rock and soil are becoming more and more important. Due to the influence of multiple factors, accurate determination of the mechanical parameters of rock and soil is not an easy job. Therefore, it is very important to analyze the main factors and the influence of the parameters, which is very important for the accurate determination and selection of mechanical parameters of rock and soil.%随着土木工程的发展,岩土力学参数显得越来越重要。由于多重因素的影响,准确测定岩土力学参数并不是一项轻松的工作。因此,分析主要因素及其产生的影响,对于准确测定和正确选取岩土力学参数至关重要。

  7. Environmental factors regulating soil organic matter chlorination

    Science.gov (United States)

    Svensson, Teresia; Montelius, Malin; Reyier, Henrik; Rietz, Karolina; Karlsson, Susanne; Lindberg, Cecilia; Andersson, Malin; Danielsson, Åsa; Bastviken, David

    2016-04-01

    Natural chlorination of organic matter is common in soils. Despite the widespread abundance of soil chlorinated soil organic matter (SOM), frequently exceeding soil chloride abundance in surface soils, and a common ability of microorganisms to produce chlorinated SOM, we lack fundamental knowledge about dominating processes and organisms responsible for the chlorination. To take one step towards resolving the terrestrial chlorine (Cl) puzzle, this study aims to analyse how environmental factors influence chlorination of SOM. Four factors were chosen for this study: soil moisture (W), nitrogen (N), chloride (Cl) and organic matter quality (C). These factors are all known to be important for soil processes. Laboratory incubations with 36Cl as a Cl tracer were performed in a two soil incubation experiments. It was found that addition of chloride and nitrogen seem to hamper the chlorination. For the C treatment, on the other hand, the results show that chlorination is enhanced by increased availability of labile organic matter (glucose and maltose). Even higher chlorination was observed when nitrogen and water were added in combination with labile organic matter. The effect that more labile organic matter strongly stimulated the chlorination rates was confirmed by the second separate experiment. These results indicate that chlorination was not primarily a way to cut refractory organic matter into digestible molecules, representing one previous hypothesis, but is related with microbial metabolism in other ways that will be further discussed in our presentation.

  8. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale.

    Science.gov (United States)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing; Jiang, Lanlan; Yang, Fen; Zheng, Shixue; Wang, Gejiao; Lin, Xiangui

    2016-05-12

    Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples were collected across a region from south to north China (about 1,000 km) to address the questions if microbial activity displays biogeographic patterns and what are driving forces. These samples represented different soil types, land use and climate. Redundancy analysis and nonmetric multidimensional scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced by rainfall, location, temperature, soil pH and soil type and was correlated with microbial activity to some extent. Our results suggest that microbial activities display a clear geographic pattern that is greatly altered by geographic distance and reflected by climate, soil pH and total P over large spatial scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity.

  9. The Soil Microbiome Influences Grapevine-Associated Microbiota

    Science.gov (United States)

    Zarraonaindia, Iratxe; Owens, Sarah M.; Weisenhorn, Pamela; West, Kristin; Hampton-Marcell, Jarrad; Lax, Simon; Bokulich, Nicholas A.; Mills, David A.; Martin, Gilles; Taghavi, Safiyh; van der Lelie, Daniel

    2015-01-01

    ABSTRACT Grapevine is a well-studied, economically relevant crop, whose associated bacteria could influence its organoleptic properties. In this study, the spatial and temporal dynamics of the bacterial communities associated with grapevine organs (leaves, flowers, grapes, and roots) and soils were characterized over two growing seasons to determine the influence of vine cultivar, edaphic parameters, vine developmental stage (dormancy, flowering, preharvest), and vineyard. Belowground bacterial communities differed significantly from those aboveground, and yet the communities associated with leaves, flowers, and grapes shared a greater proportion of taxa with soil communities than with each other, suggesting that soil may serve as a bacterial reservoir. A subset of soil microorganisms, including root colonizers significantly enriched in plant growth-promoting bacteria and related functional genes, were selected by the grapevine. In addition to plant selective pressure, the structure of soil and root microbiota was significantly influenced by soil pH and C:N ratio, and changes in leaf- and grape-associated microbiota were correlated with soil carbon and showed interannual variation even at small spatial scales. Diazotrophic bacteria, e.g., Rhizobiaceae and Bradyrhizobium spp., were significantly more abundant in soil samples and root samples of specific vineyards. Vine-associated microbial assemblages were influenced by myriad factors that shape their composition and structure, but the majority of organ-associated taxa originated in the soil, and their distribution reflected the influence of highly localized biogeographic factors and vineyard management. PMID:25805735

  10. [Soil organic carbon sequestration rate and its influencing factors in farmland of Guanzhong Plain: a case study in Wugong County, Shannxi Province].

    Science.gov (United States)

    Zhang, Xiao-Wei; Xu, Ming-Xiang

    2013-07-01

    Take Wugong County as an example, soil carbon storage and soil carbon sequestration rate were calculated, the change law of farmland soil organic carbon was explored, and the relationship of farmland soil organic carbon and natural factors, human factors was further revealed. The results of the study showed that: (1) The soil organic carbon contents in 80% of the sampling sites were in the range of 8.0-12.0 g x kg(-1), and the organic carbon contents in 0-20 cm soils showed a normal distribution. (2) In 2011, the organic carbon density of the 0-20 cm farmland soil was 26.3 t x hm(-2), below the national average soil organic carbon density (33.45 t x hm(-2)) of the arable layer. In the last 30 years, the soil carbon sequestration rate in the 0-20 cm layer was 71.3 kg x (hm2 x a)(-1), and in the past five years, the carbon sequestration rate was 480 kg x (hm x a)(-1). The recent carbon sequestration rate was higher than the national average soil carbon sequestration rate of the arable layer [380.78 kg x (hm2 x a)(-1)]. (3) In the semi-humid plain region, soil organic carbon was mainly affected by soil types, landform types, organic fertilizer. Soil types accounted for 30.2% of the organic carbon variability; the landform types and the organic fertilizer could explain 37.7% and 32.1%, respectively. The results of the comprehensive analysis showed that the farmland soil organic carbon density of Wugong County in the past 30 years is increasing, and this probably relies on the utilization of chemical fertilizer and the returning straw. Further study should be conducted on the impact of the chemical fertilizer and returning straw.

  11. Remediation of polybrominated diphenyl ethers in soil using Ni/Fe bimetallic nanoparticles: influencing factors, kinetics and mechanism.

    Science.gov (United States)

    Xie, Yingying; Fang, Zhanqiang; Cheng, Wen; Tsang, Pokeung Eric; Zhao, Dongye

    2014-07-01

    Polybrominated diphenyl ethers (PBDEs) are commonly used as additive flame retardants in all kinds of electronic products. PBDEs are now ubiquitous in the environment, with soil as a major sink, especially in e-waste recycling sites. This study investigated the degradation of decabromodiphenyl ether (BDE209) in a spiked soil using Ni/Fe bimetallic nanoparticles. The results indicated that Ni/Fe bimetallic nanoparticles are able to degrade BDE209 in soil at ambient temperature and the removal efficiency can reach 72% when an initial pH of 5.6 and at a Ni/Fe dosage of 0.03 g/g. A declining trend in degradation was noticed with decreasing Ni loading and increasing of initial BDE209 concentration. The degradation products of BDE209 were analyzed by GC-MS, which showed that the degradation of BDE209 was a process of stepwise debromination from nBr to (n-1)Br. And a possible debromination pathway was proposed. At last, the degradation process was analyzed as two-step mechanism, mass transfer and reaction. This current study shows the potential ability of Ni/Fe nanoparticles to be used for removal of PBDEs in contaminated soil. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Spatial assessment of soil nitrogen availability and varying effects of related main soil factors on soil available nitrogen.

    Science.gov (United States)

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2016-11-09

    To effectively understand the availability of soil nitrogen and assist in soil nitrogen control at the regional scale, it is essential to understand the accurate spatial distribution patterns of the three soil nitrogen parameters [i.e., total nitrogen (TN), available nitrogen (AN) and nitrogen availability ratio (NAR)] and explore the spatially varying influences of major impact factors on soil AN. Land use affects the spatial distributions of soil TN, AN and NAR (i.e., AN/TN). To explore the effects of different land use types and improve mapping accuracy, residual kriging with land use information and ordinary kriging (without land use information) were compared based on the sample data of soil TN and AN in Hanchuan county, China. A local regression technique, geographically weighted regression (GWR), was adopted to explore the varying relationships between soil AN and its major impact factors in soil (i.e., soil TN and soil pH), due to the advantages of GWR over the traditional ordinary least squares regression (OLS) model. The results showed that (1) land use types as auxiliary information obviously improved the prediction accuracies of the three soil nitrogen parameters; (2) GWR performed much better than OLS in terms of fitting accuracy; and (3) GWR effectively revealed the spatially varying influences of the impact factors on soil AN, which were ignored by OLS. Based on the results, suggestions for soil nitrogen control measures in different subareas were proposed.

  13. Why is the influence of soil macrofauna on soil structure only considered by soil ecologists ?

    OpenAIRE

    Bottinelli, N.; Jouquet, Pascal; CAPOWIEZ, Y.; Podwojewski, Pascal; Grimaldi,Michel; Peng, X.

    2015-01-01

    These last twenty years have seen the development of an abundant literature on the influence of soil macrofauna on soil structure. Amongst these organisms, earthworms, termites and ants are considered to play a key role in regulating the physical, chemical and microbiological properties of soils. Due to these influential impacts, soil ecologists consider these soil macro-invertebrates as ‘soil engineers’ and their diversity and abundance are nowadays considered as relevant bioindi...

  14. Using 137 Cs measurements to investigate the influence of erosion and soil redistribution on soil properties.

    Science.gov (United States)

    Du, P; Walling, D E

    2011-05-01

    Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to investigate using traditional approaches to documenting soil redistribution rates involving erosion plots and predictive models. However, the use of the fallout radionuclide (137)Cs to document medium-term soil redistribution rates offers a means of overcoming many of the limitations associated with traditional approaches. The study reported sought to demonstrate the potential for using (137)Cs measurements to assess the influence of soil erosion and redistribution on soil properties (particle size composition, total C, macronutrients N, P, K and Mg, micronutrients Mn, Mo, Fe, Cu and Zn and other elements, including Ti and As). (137)Cs measurements undertaken on 52 soil cores collected within a 7 ha cultivated field located near Colebrooke in Devon, UK were used to establish the magnitude and spatial pattern of medium-term soil redistribution rates within the field. The soil redistribution rates documented for the individual sampling points within the field ranged from an erosion rate of -12.9 t ha(-1) yr(-1) to a deposition rate of 19.2 t ha(-1) yr(-1). Composite samples of surface soil (0-5 cm) were collected immediately adjacent to each coring point and these samples were analysed for a range of soil properties. Individual soil properties associated with these samples showed significant variability, with CV values generally lying in the range 10-30%. The relationships between the surface soil properties and the soil redistribution rate were analysed. This analysis demonstrated statistically significant relationships between some soil properties (total phosphorus, % clay, Ti and As) and the soil redistribution rate, but for

  15. Analysis on Soil Available Zinc Content and Its Influencing Factors in Tibet%西藏土壤有锌含量及其影响因子分析

    Institute of Scientific and Technical Information of China (English)

    蒲玉琳; 龙高飞; 刘世全; 陈红君

    2009-01-01

    The change of soil available zinc content and its influencing factors were studied according to analysis data on available zinc in 164 soil profiles from 18 tested soil types in Tibet. TheResults showed that the average contents of available zinc in surface and subsurface layer soil were about 3.0 and 1.0 mg/kg resp.. The content of available zinc in surface soil of different soil types in order was mountain humid forest soils (4.88 mg/kg) > alpine meadows soils (3.72 mg/kg) > valley semi-hydromorphic soils (2.25 mg/kg) > mountain drought forest-coppice soils (2.20 mg/kg) > frigid frozen soils (1.61 mg/kg) > alpine steep soils (0.82 mg/kg). The first principal influencing factor on effectiveness of zinc in Tibeta soils was organic matter content and the second principal influencing factor was pH value.%根据西藏18个供试土类164个剖面有效锌分析资料,探讨了土壤有效锌含量变化及其影响因子.结果表明,西藏土壤表层和表下层有效锌平均含量分别约为3.0、1.0 mg/kg.不同类型土壤表层有效锌含依次为:山地湿润森林土(4.88 mg/kg)>高山草甸土(3.72mg/kg)>河谷半水成土(2.25 mg/kg)>山地旱生林灌土(2.20 mg/kg)>寒冻土(1.61 mg/kg)>高山草原土(0.82 mg/kg).影响西藏土壤锌有效性的第1主因子为有机质含量,第2主因子为土壤pH值.

  16. Time as An Important Soil-Forming Factor Influencing Modern and Ancient Magnetic Susceptibility Enhancement Along the Delaware River Valley, USA

    Science.gov (United States)

    Stinchcomb, G. E.; Peppe, D. J.; Driese, S. G.

    2011-12-01

    Magnetic susceptibility is an increasingly popular low-cost method for rapidly assessing paleoclimate and paleoenvironmental impact on buried soils. The goal of this study is to determine the primary influence(s) on soil magnetic susceptibility along floodplain, terrace and upland soils in the middle Delaware River Valley, USA, using environmental magnetic, pedologic, and stratigraphic techniques. Two-hundred thirty samples were collected from age-constrained sandy, quartz-rich, floodplain, terrace, and upland soils (Entisols, Inceptisols). A Kruskal-Wallis (K-W) and post-hoc Tukey-Kramer (T-K) (α=0.05) multiple comparisons analysis on 176 mass-specific low-field susceptibility (Xlf) assays show that A and B horizons are magnetically enhanced compared to C and E horizons (p<0.0001). Results of descriptive soil micromorphology show that A and B horizons contain anywhere from 10-50% more amorphous organic matter and clay films along pores than do C and E horizons. Enhanced Xlf values also correlate positively (R^2=0.63) with the soil molecular weathering ratio of Alumina/Bases, suggesting that increased weathering likely results in the formation of pedogenic magnetic minerals and enhanced magnetic susceptibility signal. Additional K-W and T-K testing show that Xlf results, when grouped by floodplain-terrace designation (i.e., chronofunction) are significantly different (p<0.0001). The older T3 terrace and upland Xlf values (0.34±0.14 10^-6 m^3 kg^-1) are greater than the younger T2 terrace (0.18±0.06 10^-6 m^3 kg^-1) values, which are greater than modern floodplain (0.09±0.01 10^-6 m^3 kg^-1) Xlf values. These data suggest that longer intervals of soil formation enhance the Χlf value. This hypothesis is further supported when 159 Xlf values are plotted vs. age for the entire Holocene. A locally-weighted regression smoothing curve (LOESS) shows two distinct intervals of magnetic enhancement during previously established dry intervals, the early and late

  17. Biotic and abiotic soil properties influence survival of Listeria monocytogenes in soil.

    Directory of Open Access Journals (Sweden)

    Aude Locatelli

    Full Text Available Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monitoring Network. This soil collection is meant to be representative of the pedology and land use of the whole French territory. The population of L. monocytogenes in inoculated microcosms was enumerated by plate count after 7, 14 and 84 days of incubation. Analysis of survival profiles showed that L. monocytogenes was able to survive up to 84 days in 71% of the soils tested, in the other soils (29% only a short-term survival (up to 7 to 14 days was observed. Using variance partitioning techniques, we showed that about 65% of the short-term survival ratio of L. monocytogenes in soils was explained by the soil chemical properties, amongst which the basic cation saturation ratio seems to be the main driver. On the other hand, while explaining a lower amount of survival ratio variance (11%, soil texture and especially clay content was the main driver of long-term survival of L. monocytogenes in soils. In order to assess the effect of the endogenous soils microbiota on L. monocytogenes survival, sterilized versus non-sterilized soils microcosms were compared in a subset of 9 soils. We found that the endogenous soil microbiota could limit L. monocytogenes survival especially when soil pH was greater than 7, whereas in acidic soils, survival ratios in sterilized and unsterilized microcosms were not statistically different. These results point out the critical role played by both the endogenous microbiota and the soil physic-chemical properties in determining the survival of L. monocytogenes in soils.

  18. Plant species influence on soil C after afforestation of Mediterranean degraded soils

    Science.gov (United States)

    Dominguez, Maria T.; García-Vargas, Carlos; Madejón, Engracia; Marañón, Teodoro

    2015-04-01

    Increasing C sequestration in terrestrial ecosystems is one of the main current environmental challenges to mitigate climate change. Afforestation of degraded and contaminated lands is one of the key strategies to achieve an increase in C sequestration in ecosystems. Plant species differ in their mechanisms of C-fixation, C allocation into different plant organs, and interaction with soil microorganisms, all these factors influencing the dynamics of soil C following the afforestation of degraded soils. In this work we examine the influence of different woody plant species on soil C dynamics in degraded and afforested Mediterranean soils. The soils were former agricultural lands that were polluted by a mining accident and later afforested with different native plant species. We analysed the effect of four of these species (Olea europaea var. sylvestris Brot., Populus alba L., Pistacia lentiscus L. and Retama sphaerocarpa (L.) Boiss.) on different soil C fractions, soil nutrient availability, microbial activity (soil enzyme activities) and soil CO2 fluxes 15 years after the establishment of the plantations. Results suggest that the influence of the planted trees and shrubs is still limited, being more pronounced in the more acidic and nutrient-poor soils. Litter accumulation varied among species, with the highest C accumulated in the litter under the deciduous species (Populus alba L.). No differences were observed in the amount of total soil organic C among the studied species, or in the concentrations of phenols and sugars in the dissolved organic C (DOC), which might have indicated differences in the biodegradability of the DOC. Microbial biomass and activity was highly influenced by soil pH, and plant species had a significant influence on soil pH in the more acidic site. Soil CO2 fluxes were more influenced by the plant species than total soil C content. Our results suggest that changes in total soil C stocks after the afforestation of degraded Mediterranean

  19. Modelling agricultural suitability along soil transects under current conditions and improved scenario of soil factors

    Science.gov (United States)

    Abd-Elmabod, Sameh K.; Jordán, Antonio; Fleskens, Luuk; van der Ploeg, Martine; Muñoz-Rojas, Miriam; Anaya-Romero, María; van der Salm, Renée J.; De la Rosa, Diego

    2015-04-01

    Agricultural land suitability analysis and improvement of soils by addressing major limitations may be a strategy for climate change adaptation. This study aims to investigate the influence of topography and variability of soil factors on the suitability of 12 annual, semiannual and perennial Mediterranean crops in the province of Seville (southern Spain). In order to represent the variability in elevation, lithology and soil, two latitudinal and longitudinal (S-N and W-E) soil transects (TA and TB) were considered including 63 representative points at regular 4 km intervals. These points were represented by 41 soil profiles from the SDBm soil database -Seville. Almagra model, a component of the agro-ecological decision support system MicroLEIS, was used to assess soil suitability. Results were grouped into five soil suitability classes: S1-optimum, S2-high, S3-moderate, S4-marginal and S5-not suitable. Each class was divided in subclasses according to the main soil limiting factors: depth (p), texture (t), drainage (d), carbonate content (c), salinity (s), sodium saturation (a), and the degree of development of the soil profile (g). This research also aimed to maximize soil potential by improving limiting factors d, c, s and a after soil restoration. Therefore, management techniques were also considered as possible scenarios in this study. The results of the evaluation showed that soil suitability ranged between S1 and S5p - S5s along of the transects. In the northern extreme of transect TA, high content of gravels and coarse texture are limiting factors (soils are classified as S4t) In contrast, the limiting factor in the eastern extreme of transect TB is the shallow useful depth (S5p subclass). The absence of calcium carbonate becomes a limiting factor in some parts of TA. In contrast, the excessive content of calcium carbonate appeared to be a limiting factor for crops in some intermediate points of TB transect. For both transects, soil salinity is the main

  20. 陆地生态系统土壤呼吸时空变异的影响因素研究进展%Review of the Factors Influencing the Temporal and Spatial Variability of Soil Respiration in Terrestrial Ecosystem

    Institute of Scientific and Technical Information of China (English)

    陈书涛; 胡正华; 张勇; 沈小帅; 史艳姝

    2011-01-01

    土壤呼吸是碳循环中的1个重要过程,土壤呼吸作用的过程及其影响因子对理解陆地碳循环极为关键.本文对迄今为止国内外关于土壤呼吸时空变异性影响因素的一些研究进行综述,分析了气候、植被、土壤因素对土壤呼吸变异性的影响规律.以往的研究表明,气候因素中对土壤呼吸具有重要影响的因子为气温和降水,植被因素中对土壤呼吸具有重要影响的因子为叶面积指数、凋落物质量、细根生物量,而土壤因素中的有机碳含量、质地对土壤呼吸具有影响.气候、植被、土壤因素对土壤呼吸的影响往往表现为综合作用.温度、降水一方面直接影响土壤中根系和微生物的呼%Soil respiration is an important process in carbon cycling.Understanding the processes and controlling factors of soil respiration are crucial in investigating the terrestrial carbon cycling.This article reviews the investigations about the factors controlling the temporal and spatial variability of soil respiration.The temporal and spatial variability in soil respiration is linked with climate,vegetation and soil factors.Air temperature and precipitation generally contribute great to the variability of soil respiration.Leaf area index(LAI),litter fall and fine root biomass are three plant-related factors that can be employed to explained the variability of soil respiration,while soil carbon content and texture are two soil factors responsible for the variability of soil respiration.Generally,climate,vegetation and soil factors contribute collectively to the temporal and spatial variability of terrestrial soil respiration.Temperature and precipitation,on the one hand,directly affect the root and microbial respiration rates.On the other hand,temperature and precipitation indirectly affect soil respiration by influencing the plant and microbial growth and soil conditions.In order to understand the controlling factors of the

  1. 农田土壤固碳及其影响因子研究进展%Carbon Sequestration and its Influencing Factors in Agricultural Soils

    Institute of Scientific and Technical Information of China (English)

    宁皎莹; 和苗苗; 周根娣

    2014-01-01

    固碳过程对于改善土壤质量、维持农田生态系统、保障全球粮食安全、缓解气候变化趋势等至关重要。本文介绍了农田土壤的生物与非生物固碳过程,阐述了土壤质地、水热变化、全球变暖和人为因素对农田土壤固碳过程的影响。总结了目前较受重视的一些农田固碳措施(施肥、灌溉、秸秆还田、生物炭质施入等)及其对农田土壤固碳能力的改善和应用中存在的问题,并对今后的相关研究作出展望。%Carbon sequestration in agricultural soils plays an important role in improving soil quality ,restoring degraded soil and ecosystems ,ensuring global food security and mitigating global climate changes .This review elaborates the biotic and abiotic carbon sequestration processes in agricultural soil , and discusses the impacts of soil texture , hydrothermal changes ,global warming and anthropogenic factors on soil carbon sequestration .Some measures on agricultural soil carbon sequestration ,such as ,fertilization ,irrigation ,straw returning ,and biochar inputs ,as well as the improvement impacts of these measures on carbon sequestration ability and the problems in the applications are also summarized . Finally , the prospects of the future research work are put forward .

  2. Environmental factors influencing the structural dynamics of soil microbial communities during assisted phytostabilization of acid-generating mine tailings: a mesocosm experiment.

    Science.gov (United States)

    Valentín-Vargas, Alexis; Root, Robert A; Neilson, Julia W; Chorover, Jon; Maier, Raina M

    2014-12-01

    Compost-assisted phytostabilization has recently emerged as a robust alternative for reclamation of metalliferous mine tailings. Previous studies suggest that root-associated microbes may be important for facilitating plant establishment on the tailings, yet little is known about the long-term dynamics of microbial communities during reclamation. A mechanistic understanding of microbial community dynamics in tailings ecosystems undergoing remediation is critical because these dynamics profoundly influence both the biogeochemical weathering of tailings and the sustainability of a plant cover. Here we monitor the dynamics of soil microbial communities (i.e. bacteria, fungi, archaea) during a 12-month mesocosm study that included 4 treatments: 2 unplanted controls (unamended and compost-amended tailings) and 2 compost-amended seeded tailings treatments. Bacterial, fungal and archaeal communities responded distinctively to the revegetation process and concurrent changes in environmental conditions and pore water chemistry. Compost addition significantly increased microbial diversity and had an immediate and relatively long-lasting buffering-effect on pH, allowing plants to germinate and thrive during the early stages of the experiment. However, the compost buffering capacity diminished after six months and acidification took over as the major factor affecting plant survival and microbial community structure. Immediate changes in bacterial communities were observed following plant establishment, whereas fungal communities showed a delayed response that apparently correlated with the pH decline. Fluctuations in cobalt pore water concentrations, in particular, had a significant effect on the structure of all three microbial groups, which may be linked to the role of cobalt in metal detoxification pathways. The present study represents, to our knowledge, the first documentation of the dynamics of the three major microbial groups during revegetation of compost

  3. Environmental Factors Influencing the Structural Dynamics of Soil Microbial Communities During Assisted Phytostabilization of Acid-Generating Mine Tailings: a Mesocosm Experiment

    Science.gov (United States)

    Valentín-Vargas, Alexis; Root, Robert A.; Neilson, Julia W; Chorover, Jon; Maier, Raina M.

    2014-01-01

    Compost-assisted phytostabilization has recently emerged as a robust alternative for reclamation of metalliferous mine tailings. Previous studies suggest that root-associated microbes may be important for facilitating plant establishment on the tailings, yet little is known about the long-term dynamics of microbial communities during reclamation. A mechanistic understanding of microbial community dynamics in tailings ecosystems undergoing remediation is critical because these dynamics profoundly influence both the biogeochemical weathering of tailings and the sustainability of a plant cover. Here we monitor the dynamics of soil microbial communities (i.e. bacteria, fungi, archaea) during a 12-month mesocosm study that included 4 treatments: 2 unplanted controls (unamended and compost-amended tailings) and 2 compost-amended seeded tailings treatments. Bacterial, fungal and archaeal communities responded distinctively to the revegetation process and concurrent changes in environmental conditions and pore water chemistry. Compost addition significantly increased microbial diversity and had an immediate and relatively long-lasting buffering-effect on pH, allowing plants to germinate and thrive during the early stages of the experiment. However, the compost buffering capacity diminished after six months and acidification took over as the major factor affecting plant survival and microbial community structure. Immediate changes in bacterial communities were observed following plant establishment, whereas fungal communities showed a delayed response that apparently correlated with the pH decline. Fluctuations in cobalt pore water concentrations, in particular, had a significant effect on the structure of all three microbial groups, which may be linked to the role of cobalt in metal detoxification pathways. The present study represents, to our knowledge, the first documentation of the dynamics of the three major microbial groups during revegetation of compost

  4. FACTORS THAT INFLUENCE ADOPTION OF INTEGRATED SOIL FERTILITY AND WATER MANAGEMENT PRACTICES BY SMALLHOLDER FARMERS IN THE SEMI-ARID AREAS OF EASTERN KENYA

    Directory of Open Access Journals (Sweden)

    Miriam Mutua Mutuku

    2017-05-01

    Full Text Available In arid and semi-arid lands (ASALs, low adoption of integrated soil fertility and water management (ISFWM technologies has contributed to food and nutrition insecurity. A study was conducted to assess factors influencing smallholder farmers’ adoption decision of ISFWM technologies in Mwala and Yatta Sub-Counties. A questionnaire was administered to 248 respondents in the study region. Selection of household heads was done in ‘Farmer-led adoption approach’ sites otherwise known as Primary and Secondary Participatory Technology Evaluations (PPATEs and SPPATEs and Non-PPATEs/SPATEs sites in both Sub-Counties. Relationships between different variables were determined by the Tobit model. The results revealed that group membership (P<0.016, inaccessible credit services (P<0.017, gender (P<0.025, age and access to agricultural extension services (P<0.027 influenced adoption of ISFWM technology significantly. Cost of inputs and access to radio information (P<0.01, access to appropriate farm machines (p<0.001, cost of labor and farmers’ perception on seasons’ reliability (P<0.004 and out-put markets (P<0.006 were reported to affect adoption of ISFWM practices highly significantly. Descriptive statistic results indicated that majority of the respondents (93.9% in the project areas were adopting a combination of tied ridges, organic fertilizer and improved seed compared to only 6.1% in the non-project area. There was also significantly (P<0.01 higher adoption (76.5% of a combination of tied ridges, both fertilizer and improved seed in the project area in contrast to merely 23.5% in non-project area, as well as those adopting (80% a combination of zai pit, both fertilizer and improved seed compared to only 20% in non-project area. Policy makers should focus on availability of affordable credit facilities and farm machines, ease access to information, labor and input-output markets for enhanced farm productivity and livelihoods of the smallholder

  5. 茶园土壤细菌丰度及其影响因子研究%Bacterial Abundance of Tea Garden Soils and Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    韩文炎; 王皖蒙; 郭赟; 杨明臻; 贾仲君

    2013-01-01

      采用 Griffiths 法直接提取土壤微生物基因组 DNA,并通过实时荧光定量 PCR 技术分析土壤微生物16 S rRNA 基因数量,对茶园及其附近森林和菜园土壤的细菌丰度及其影响因素进行了研究。结果表明,茶园土壤细菌丰度在0.01×108~20.32×10816 S rRNA 基因拷贝数/g 之间,平均为3.70×10816 S rRNA 基因拷贝数/g,与酸性森林土壤大致相当,但明显低于中性菜园土壤。土壤细菌丰度与 pH 和微生物量 C 呈极显著正相关(P<0.001),但与施 N 量和茶树种植年限呈极显著负相关(P<0.01),与土壤有机 C 和全 N 含量的相关性不明显。多元回归分析表明,影响土壤细菌丰度最重要的因子是土壤 pH,其他依次为树龄和施氮量。可见,提高茶园土壤细菌数量和微生物多样性的有效办法是适当提高土壤 pH 值,同时避免过量施用氮肥;对于改植换种的老茶园,改良土壤也是必不可少的。%Bacterial abundances in tea garden and their adjacent forest and vegetable soils were investigated by real-time quantitative PCR (qPCR) as well as the factors that may affect the population size of bacterial communities. Soil DNA was extracted by using Griffiths’ method and bacterial abundance was determined by quantifying the copy number of 16S rRNA genes. The results showed that the bacterial abundance of tea garden soils ranged from 0.01×108 to 20.32×108 16 S rRNA gene copies/g (gram dry weight soil) with an average of 3.70×108 16 S rRNA gene copies/g, being similar with that in the forest soil, but far below that in the vegetable soil. The bacterial abundance in the tea garden soils was significantly and positively correlated with the soil pH and microbial biomass C (P<0.001) respectively, but significantly and negatively correlated with N application rate and age of tea plantation (P<0.01) respectively. There was no significant correlation between bacterial abundance and

  6. Factors determining soil nutrient distribution in a small-scaled watershed in the purple soil region of Sichuan Province, China

    NARCIS (Netherlands)

    Wang, H.J.; Shi, X.Z.; Yu, D.S.; Weindorf, D.C.; Huang, B.; Sun, W.X.; Ritsema, C.J.; Milne, E.

    2009-01-01

    Determining soil nutrient distribution is critical to identify sites which are at risk of N and P loading. Equally important are determining factors that influence such distribution (e.g. land use, land management, topography, etc.). In this research, soil nutrient distribution and its influencing

  7. Modeling the influence of organic acids on soil weathering

    Science.gov (United States)

    Lawrence, Corey; Harden, Jennifer; Maher, Kate

    2014-08-01

    Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

  8. Modeling the influence of organic acids on soil weathering

    Science.gov (United States)

    Lawrence, Corey R.; Harden, Jennifer W.; Maher, Kate

    2014-01-01

    Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

  9. Reduction of Influence Factors

    NARCIS (Netherlands)

    Regtien, Paulus P.L.; Sydenham, Peter H.; Thorn, Richard

    Any measurement system has imperfections and any act of measurement is liable to errors. Measurement errors either originate from system deficiencies (for instance system noise, quantization, and drift), or are due to environmental influences such as thermal, electromagnetic, and mechanical

  10. PRINCIPAL COMPONENT ANALYSIS OF FACTORS DETERMINING PHOSPHATE ROCK DISSOLUTION ON ACID SOILS

    Directory of Open Access Journals (Sweden)

    Yusdar Hilman

    2016-10-01

    Full Text Available Many of the agricultural soils in Indonesia are acidic and low in both total and available phosphorus which severely limits their potential for crops production. These problems can be corrected by application of chemical fertilizers. However, these fertilizers are expensive, and cheaper alternatives such as phosphate rock (PR have been considered. Several soil factors may influence the dissolution of PR in soils, including both chemical and physical properties. The study aimed to identify PR dissolution factors and evaluate their relative magnitude. The experiment was conducted in Soil Chemical Laboratory, Universiti Putra Malaysia and Indonesian Center for Agricultural Land Resources Research and Development from January to April 2002. The principal component analysis (PCA was used to characterize acid soils in an incubation system into a number of factors that may affect PR dissolution. Three major factors selected were soil texture, soil acidity, and fertilization. Using the scores of individual factors as independent variables, stepwise regression analysis was performed to derive a PR dissolution function. The factors influencing PR dissolution in order of importance were soil texture, soil acidity, then fertilization. Soil texture factors including clay content and organic C, and soil acidity factor such as P retention capacity interacted positively with P dissolution and promoted PR dissolution effectively. Soil texture factors, such as sand and silt content, soil acidity factors such as pH, and exchangeable Ca decreased PR dissolution.

  11. Influence of spatially-dependent, modeled soil carbon emission factors on life-cycle greenhouse gas emissions of corn and cellulosic ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhangcai; Dunn, Jennifer B.; Kwon, Ho-young; Mueller, Steffen; Wander, Michelle M.

    2016-01-01

    Converting land to biofuel feedstock production incurs changes in soil organic carbon (SOC) that can influence biofuel life-cycle greenhouse gas (GHG) emissions. Estimates of these land use change (LUC) and life-cycle GHG emissions affect biofuels’ attractiveness and eligibility under a number of renewable fuel policies in the U.S. and abroad. Modeling was used to refine the spatial resolution and depth-extent of domestic estimates of SOC change for land (cropland, cropland pasture, grasslands, and forests) conversion scenarios to biofuel crops (corn, corn stover, switchgrass, Miscanthus, poplar, and willow). In most regions, conversions from cropland and cropland pasture to biofuel crops led to neutral or small levels of SOC sequestration, while conversion of grassland and forest generally caused net SOC loss. Results of SOC change were incorporated into the Greenhouse Gases, Regulated Emissions, and Energy use in Transportation (GREET) model to assess their influence on life-cycle GHG emissions for the biofuels considered. Total LUC GHG emissions (g CO2eq MJ-1) were 2.1–9.3 for corn, -0.7 for corn stover, -3.4–12.9 for switchgrass, and -20.1–-6.2 for Miscanthus; these varied with SOC modeling assumptions applied. Extending soil depth from 30 to 100cm affected spatially-explicit SOC change and overall LUC GHG emissions; however the influence on LUC GHG emissions estimates were less significant in corn and corn stover than cellulosic feedstocks. Total life-cycle GHG emissions (g CO2eq MJ-1, 100cm) were estimated to be 59–66 for corn ethanol, 14 for stover ethanol, 18-26 for switchgrass ethanol, and -0.6–-7 for Miscanthus ethanol.

  12. SOIL TRANSMITTED HELMINTHS AND ASSOCIATED FACTORS ...

    African Journals Online (AJOL)

    GB

    2013-11-03

    Nov 3, 2013 ... government and private primary school children. Stool samples were collected ... 2Addis Continental Institute of Public Health, Addis Ababa, Ethiopia. Corresponding ... possible risk factors and status of soil contamination are ...

  13. Remote Sensing Assessment of Soil Moisture, Soil Mineralogy and other Environmental Factors Influencing Mosquito-borne Infection Risks in the Lower Rio Grande Valley, U.S. - Mexico Border (Invited)

    Science.gov (United States)

    Hubbard, B. E.; Folger, H. W.; Page, W. R.

    2010-12-01

    A dengue fever outbreak occurred near Matamoros, Mexico along the Lower Rio Grande Valley during the summer of 2005 following heavy rainfall from Tropical Storm Gert and Hurricane Emily. This outbreak exemplifies the need for monitoring soil moisture and mapping soil permeability factors affecting the breeding and distribution of mosquito species capable of spreading disease. For example, the Rio Grande delta of South Texas and North Tamaulipas Mexico is inhabited by over 50 native and invasive species of mosquitoes capable of hosting Malaria, West Nile Virus and other types of human and livestock infecting Encephalitis. They range in ecological habitats from coastal salt marshes to freshwater riparian wetlands, tree holes and/or urban containers, flooded agricultural fields, and the many irrigation canals and ditches present throughout our study area. For this study, water-saturated and flooded soils were mapped using a “soil moisture availability” index (Mo) based on normalized difference vegetation index (NDVI) images and surface radiant and/or kinetic temperature images derived from multi-temporal Landsat-7 ETM+ and ASTER imagery. In particular, the Landsat-7 imagery covers ten cloud-free or minimal cloud cover acquisition dates during drought and wet periods of 2002, prior to the scan-line corrector failure in 2003. This includes one date (August 18, 2002) of co-orbital swath coverage between Landsat and ASTER, acquired after the land fall and dissipation of Tropical Storm Bertha (August 09, 2002). ASTER image dates used include those before and after the land fall of Hurricane Emily on July 20, 2005. The resulting maps show the distribution of relatively permeable (i.e. sandier) and impermeable soil types, the latter of which are dominated by clay-rich soils deposited in remnant interdistributary channels as channel-fill, and overbank flood deposits along the modern Rio Grande delta and portions of the (remapped) Pleistocene Beaumont coastal deltaic plain

  14. Soil Respiration Variations in Winter Wheat Field in Different Previous Crops and Its Influencing Factors%不同前茬冬小麦土壤呼吸特征及影响因子分析

    Institute of Scientific and Technical Information of China (English)

    郝旺林; 梁银丽; 吴兴; 林兴军; 朱艳丽; 罗安荣

    2011-01-01

    This study was to define the Variations of soil respiration,the response of influence factors to soil respiration and carbon sink in the total growing season,in winter wheat field of different previous crops.The results showed that: ①as soil depth increases,the response of temperature to soil respiration rate also increased with a lag;②the soil respiration rate was quadric to soil moisture,phosphorus,potassium,soil urease activity,soil temperature,soil moisture as the main factors had an effect on soil respiration rate;soil temperature had the stronger effect on soil respiration rate when potassium had the weaker effect on soil respiration rate;③the average carbon emission rate in wheat filed of different previous crops showed as follow: Pepper of previous crops celery of previous crops corn of previous crops eggplant of previous crops.The intensity of carbon "sink" displayed as follow: eggplant of previous crops celery of previous crops corn of previous crops pepper of previous crops.As for the trials of this study,although the soil respiration rate is highest in the winter wheat filed of previous pepper,the amount of carbon fixed is the most.Its ratio of net primary productivity(NPP) and soil carbon release quantity was highest,so carbon sink was the strongest.If rotation planting was arranged according to the purpose of increasing carbon sink and reducing carbon emissions,pepper was relatively appropriate stubbles crop,followed by corn crop,celery and eggplant.%以不同蔬菜前茬处理的冬小麦田为对象,研究土壤呼吸变化特征、各影响因子对土壤呼吸的响应的通径分析以及计算全生长季农田碳汇强度.结果表明:①温度对土壤呼吸速率的响应随深度增加具有滞后性;土壤呼吸与土壤水分呈显著二次相关.②有效磷、速效钾、土壤脲酶、土壤温度、土壤水分对土壤呼吸变化的贡献较大,为主要影响因子.5种主要因子中土壤温

  15. Phonological Awareness: Factors of Influence

    Science.gov (United States)

    Frohlich, Linda Paulina; Petermann, Franz; Metz, Dorothee

    2013-01-01

    Early child development is influenced by various genetic and environmental factors. This study aims to identify factors that affect the phonological awareness of preschool and first grade children. Based on a sample of 330 German-speaking children (mean age = 6.2 years) the following domains were evaluated: Parent factors, birth and pregnancy,…

  16. Effect of thermokarst lake on soil saturated hydraulic conductivity and analysis of its influenced factors%热融湖塘对青藏高原土壤饱和导水率的影响及因素分析

    Institute of Scientific and Technical Information of China (English)

    高泽永; 王一博; 刘国华

    2014-01-01

    Thermkarst lakes as a typical landform unit are widely distributed in permafrost areas of the source region of the Yangtze River. The thermokarst lakes can have huge impact on soil properties, permafrost distribution, eco-hydrological processes, etc. on the lakeshore area with its development process. In this study, we analyzed the influence factors on physical and chemical properties of soil and made comparative analysis of the spatial difference of soil saturated hydraulic conductivity in the undisturbed lakeshore area, the dead root area of lakeshore, saline soil area of lakeshore and different slope areas around a typical thermokarst lake in permafrost areas of the source region of Yangtze River. Our results showed that soil saturated hydraulic conductivity differed among soils from different areas. The soil saturated hydraulic conductivity was in an order of dead root area of lakeshore > undisturbed lakeshore area > saline soil area of lakeshore. Compared with the soil of undisturbed lakeshore area, the soil saturated hydraulic conductivity of the dead root area of lakeshore increased by 70.1%, while the saline soil area decreased by 33.8%. The results showed soil environment had a great change with the formation of thermkarst lakes. The results suggested that the formation of the dead root area of lakeshore led to an increase in soil saturated hydraulic conductivity and a decrease of runoff capacity. Opposite results were found with the saline soil. At different slope areas of lakeshore, the greater the slope was, the greater the soil saturated hydraulic conductivity. Furthermore the maximum difference appeared at the middle position of the slope while soil saturated hydraulic conductivity of slope bottom did not obviously changed. The results also showed that with the different effects of thermkarst lakes, the cause of the variation of soil saturated hydraulic conductivity at the different areas was coupled with the influences of vegetation coverage, soil

  17. Influence of 15N enrichment on the net isotopic fractionation factor during the reduction of nitrate to nitrous oxide in soil

    DEFF Research Database (Denmark)

    Mathieu, O.; Levegue, J.; Henault, C.

    2007-01-01

    Nitrous oxide, a greenhouse gas, is mainly emitted from soils during the denitrification process. Nitrogen stable-isotope investigations can help to characterise the N(2)O source and N(2)O production mechanisms. The stable-isotope approach is increasingly used with (15)N natural abundance...... or relatively low (15)N enrichment levels and requires a good knowledge of the isotopic fractionation effect inherent to this biological mechanism. This paper reports the measurement of the net and instantaneous isotopic fractionation factor (alpha(i)(s/p)) during the denitrification of NO(3)(-) to N(2)O over...... a range of (15)N substrate enrichments (0.37 to 1.00 atom% (15)N). At natural abundance level, the isotopic fractionation effect reported falls well within the range of data previously observed. For (15)N-enriched substrate, the value of alpha(i)(s/p) was not constant and decreased from 1.024 to 1...

  18. Spatial characterization of soil properties and influence in soil formation in oak-grassland of Sierra Morena, S Spain

    Science.gov (United States)

    Román-Sánchez, Andrea; Cáceres, Francisco; Pédèches, Remi; Giráldez Cervera, Juan Vicente; Vanwalleghem, Tom

    2016-04-01

    The Mediterranean oak-grassland ecosystem is very important for the rural economy and for the biodiversity of south-western European countries like Spain and Portugal. Nevertheless these ecosystems are not well characterized especially their soils. In this report soil carbon has been evaluated and related to other properties. The principal factors controlling the structure, productivity and evolution of forest ecosystems are bedrock, climate, relief, vegetation and time. Soil carbon has an important influence in the soil and ecosystem structures. The purpose of this study is to determine the relationship between relief, soil properties, spatial distribution of soil carbon and their influence in soil formation and geomorphology. This work is part of another study which aims to elucidate the processes involved in the soil formation and to examine their behaviour on long-term with a modelling. In our study area, located in oak-grassland of Sierra Morena, in Cordoba, S Spain, have been studied 67 points at 6 depths in 262 hectares in order to determine carbon content varying between 0-6%, soil properties such as soil depth between 0-4 m, horizon depth and the rocks amount in surface. The relationship between the soil carbon, soil properties and the relief characteristic like slope, aspect, curvature can shed light the processes that affect the mechanisms of bedrock weathering and their interrelationship with geomorphological processes.

  19. Influence of temperature and organic matter content on soil respiration in a deciduous oak forest

    Directory of Open Access Journals (Sweden)

    Zsolt Kotroczó

    2014-12-01

    Full Text Available The increasing temperature enhances soil respiration differently depend on different conditions (soil moisture, soil organic matter, the activity of soil microbes. It is an essential factor to predicting the effect of climate change on soil respiration. In a temperate deciduous forest (North-Hungary we added or removal aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture and soil temperature. Soil CO2 efflux was measured at each plot using chamber based soil respiration measurements. We determined the temperature sensitivity of soil respiration. The effect of doubled litter was less than the effect of removal. We found that temperature was more influential in the control of soil respiration than soil moisture in litter removal treatments, particularly in the wetter root exclusion treatments (NR and NI (R2: 0.49-0.61. Soil moisture (R2: 0.18-0.24 and temperature (R2: 0.18-0.20 influenced soil respiration similarly in treatments, where soil was drier (Control, Double Litter, Double Wood. A significantly greater increase in temperature induced higher soil respiration were significantly higher (2-2.5-fold in root exclusion treatments, where soil was wetter throughout the year, than in control and litter addition treatments. The highest bacterial and fungal count was at the DL treatment but the differences is not significant compared to the Control. The bacterial number at the No Litter, No Root, No Input treatment was significantly lower at the Control. Similar phenomenon can be observed at the fungal too, but the differences are not significant. The results of soil respiration suggest that the soil aridity can reduce soil respiration increases with the temperature increase. Soil bacterial and fungal count results show the higher organic matter content and soil surface cover litter favors the activity.

  20. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale

    DEFF Research Database (Denmark)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing

    2016-01-01

    were collected across a region from south to north China (about 1,000 km) to address the questions if microbial activity displays biogeographic patterns and what are driving forces. These samples represented different soil types, land use and climate. Redundancy analysis and nonmetric multidimensional...... by rainfall, location, temperature, soil pH and soil type and was correlated with microbial activity to some extent. Our results suggest that microbial activities display a clear geographic pattern that is greatly altered by geographic distance and reflected by climate, soil pH and total P over large spatial...... scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity....

  1. Distribution characteristics of soil carbon and nitrogen and its influencing factors in different farming regions of Jiangsu province%江苏省不同农区土壤碳氮分布特征及其影响因素

    Institute of Scientific and Technical Information of China (English)

    张辉; 王绪奎; 许建平; 张永春; 艾玉春

    2014-01-01

    为给江苏省耕地地力的保持和培育提供基础数据,以分布于江苏全省的297个土壤监测点为研究对象,研究了江苏省域不同农区土壤碳氮分布,并对其影响因素进行了分析。结果表明土壤类型、农区分布、施肥类型及施肥量、种植制度和还田秸秆量对土壤碳氮分布具有重要影响:(1)水稻土、黄棕壤、砂姜黑土、潮土、棕壤、潮盐土的土壤有机质和氮含量依次减少。(2)在水稻土中,徐淮、里下河、沿江等农区土壤有机质和氮含量较高,而太湖和丘陵农区次之,沿海农区最低;潮土中徐淮、里下河和丘陵农区土壤有机质和氮含量较高,而太湖农区、沿江农区次之,沿海农区最低;黄棕壤中太湖农区土壤有机质和氮含量较高,而丘陵农区较低;潮盐土中徐淮农区土壤有机质和氮含量最高,里下河农区次之,沿江农区最低。(3)同一种土壤中,有机肥施用量高的土壤碳氮含量较高。(4)在同一种土壤中,种植蔬菜、大量粮食作物(小麦、水稻、玉米等)、块根旱作作物(马铃薯等)、茶叶等的土壤碳氮含量依次降低。%In order to provide basic data for arable land conservation and cultivation in Jiangsu province, the distri-bution of soil carbon and nitrogen in different farming region were studied in 297 soil monitoring sites located around Jiangsu province, and the influencing factors were analyzed as well. The results showed that the soil type, the distribution of farm-ing regions, fertilizer type and amount of fertilizer, cropping systems and the amount of returned straw played major roles in the distribution of soil carbon and nitrogen. Soil organic matter and nitrogen content decreased in the orders of paddy soil, yellow brown soil, lime concretion black soil, alluvial soil, brown soil and alluvial-salty soil. In paddy soils, the farming regions of Xuhuai, Lixiahe and Yangtze River bank

  2. Evaluation of soil microbial communities as influenced by crude oil ...

    African Journals Online (AJOL)

    Evaluation of soil microbial communities as influenced by crude oil pollution. ... Community-level approach for assessing patterns of sole carbon-source utilization ... impact of crude oil pollution, soil – biota interactions, ecosystem monitoring, ...

  3. Influence of Parent Material and Topography on some Soil ...

    African Journals Online (AJOL)

    Influence of Parent Material and Topography on some Soil Properties in Southwestern Nigeria. ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... on soils formed on banded gneiss and quartzite schist parent materials.

  4. Influence of Soil Fertility on Angelica Quality and Yield

    Institute of Scientific and Technical Information of China (English)

    RAO Bi-yu; WU Zhan-jing; LUO Shao-qin; LI Xiao-bo

    2012-01-01

    We studied the relationship between soil fertility indicator and angelica yield and quality by the methods of correlation analysis and path analysis. The results showed that, in Yunnan Province, the content of ferulic acid (major indicator of angelica quality) is 1.5-2.5 mg/g and single plant fresh weight (major indicator of yield) is 60-250 g. The content of angelica ferulic acid and angelica single plant fresh weight are positively correlated with the content of total N, quick-acting K, organic matter, whereas negatively correlated with the content of quick-acting P. It is shown that the most direct factor that influence the content of the angelica ferulic acid is the quick-acting K, and the least direct factor is organic matter; the most direct factor that influences the single plant fresh weight of angelica is the total N, while the least direct factor is the quick-acting P. In conclusion, the soil fertility indicators that have great influence on quality and yield of angelica are the quick-acting K, total N, quick-acting P and organic matter.

  5. Characteristics and Influencing Factors of Soil Organic Carbon in Upstream Watershed of Miyun Reservoir in North China%密云水库上游流域土壤有机碳特征及其影响因素

    Institute of Scientific and Technical Information of China (English)

    王淑芳; 王效科; 欧阳志云

    2011-01-01

    Soil organic carbon (SOC) pool constitutes an important portion of the global carbon pool and has significant impacts on land productivity and global climate change. The study on soil organic carbon has been one of the hot issues of the world. However, related research of the filed in the Upstream Watershed of Miyun Reservoir, the largest reservoir in North China, is relatively rare. The distribution characteristics and influencing factors (such as climate, topography and soil characteristics) of soil organic carbon in seven kinds of typical land use types of the Upstream Watershed of Miyun Reservoir were analyzed in the study, and the results showed as follows. 1) In the target domain, soil organic carbon contents in natural secondary forests and grasslands were much higher than those in shrubs and artificial forests, while that in croplands was the lowest. In the whole soil profile (0 - 40 cm), the average soil organic carbon content was in order of natural secondary Populus davidiana Dode-Belula platyphylla Suk. Mixed forest > grassland > natural secondary Quercus wutaishanica Blume forest > shrub > artificial Larix principis-rupprechlii Mayr. Forest>artificial Pinus labulaeformis Carr. Forest>cropland. 2) Soil organic carbon contents in the top soil layer (0 - 10 cm) were the highest and decreased rapidly with the increase depth in the six kinds of land use types except grassland, which showed a slight increase from 0 to 20 cm and a small drop from 20 to 40 cm in depth. 3) Soil organic carbon content in each layer was significantly positively correlated with altitude, soil water content and nitrogen content (p0.05). Further partial correlation analysis indicated that the most principal factors influencing soil organic carbon content varied with soil depth, and they were soil nitrogen content, bulk density and pH in the 0 - 10 cm layer, soil nitrogen content, bulk density and slop in the 10-20 cm layer, soil nitrogen content and annual precipitation in the 20

  6. Factors Influencing Healthcare Service Quality

    OpenAIRE

    Ali Mohammad Mosadeghrad

    2014-01-01

    Background The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results Quality in healthcare is a production o...

  7. Soil Respiration Characteristics and Its Influencing Factors in Datong Phragmites australis Ecological Wetland%大通芦苇生态湿地土壤呼吸特征及其影响因子

    Institute of Scientific and Technical Information of China (English)

    赵魁; 姚多喜; 张治国; 杨清; 安士凯; 张文影

    2013-01-01

    In order to seek soil carbon emission characteristics and its influencing factors in Datong Phragmites australis ecological wetland, soil respiration and related environmental factors in Huainan Datong Phragmites australis ecological wetland were measured by LI-8100, the automated soil CO2 flux system, from July 2011 to April 2012. At the same time, the corresponding point topsoil was brought back to determine 7 kinds of enzyme activity. The results indicated that: the diurnal variation of Phragmites australis wetland soil respiration showed an asymmetric single peak curve pattern, and seasonal change was significant (P0.05). The stepwise regression showed that, Phragmites australis wetland soil respiration was significant correlation with phosphatase, cellulose and catalase (P0.05). In conclude, the significant environment driving factor of Phragmites australis wetland soil respiration was the soil temperature, the effect of soil enzyme related to soil respiration was also extremely important.%为了探寻芦苇湿地土壤碳排放特征及其影响因素,利用Li-8100自动土壤碳通量系统,分别于2011年7月、10月,2012年1月、3月测定淮南大通芦苇湿地的土壤呼吸强度及相关环境因子,同时取相应点表土测定7种土壤酶活性.结果表明:芦苇湿地土壤呼吸强度昼夜变化呈非对称的单峰曲线,季节差异显著(P<0.05),最大值为(4.41±0.36) μmol/(m2·s),出现在2011年7月的12:00-16:00,最小值为(0.57士0.24)μmol/(m2·s),出现在2012年1月的凌晨4:00左右;通过偏相关分析排除其他环境因子的影响,芦苇湿地土壤呼吸强度仅与土壤10 cm温度呈极显著相关(p<0.01),其指数回归模型可以解释土壤呼吸的91.50%,与其他环境因子相关性不显著(p<0.05);逐步线性回归方程表明,芦苇湿地土壤呼吸强度与土壤碱性磷酸酶、纤维素酶、过氧化氢酶极显著相关(p<0.01),这3种酶可解释土壤呼吸强度的95.6%,而与

  8. Spatial Analysis of PAHs in Soils along an Urban–Suburban–Rural Gradient: scale effect, distribution patterns, diffusion and influencing factors

    Science.gov (United States)

    Peng, Chi; Wang, Meie; Chen, Weiping

    2016-11-01

    Spatial statistical methods including Cokriging interpolation, Morans I analysis, and geographically weighted regression (GWR) were used for studying the spatial characteristics of polycyclic aromatic hydrocarbon (PAH) accumulation in urban, suburban, and rural soils of Beijing. The concentrations of PAHs decreased spatially as the level of urbanization decreased. Generally, PAHs in soil showed two spatial patterns on the regional scale: (1) regional baseline depositions with a radius of 16.5 km related to the level of urbanization and (2) isolated pockets of soil contaminated with PAHs were found up to around 3.5 km from industrial point sources. In the urban areas, soil PAHs showed high spatial heterogeneity on the block scale, which was probably related to vegetation cover, land use, and physical soil disturbance. The distribution of total PAHs in urban blocks was unrelated to the indicators of the intensity of anthropogenic activity, namely population density, light intensity at night, and road density, but was significantly related to the same indicators in the suburban and rural areas. The moving averages of molecular ratios suggested that PAHs in the suburban and rural soils were a mix of local emissions and diffusion from urban areas.

  9. Influence of Soil Moisture on Soil Gas Vapor Concentration for Vapor Intrusion

    OpenAIRE

    Shen, Rui; Pennell, Kelly G.; Suuberg, Eric M.

    2013-01-01

    Mathematical models have been widely used in analyzing the effects of various environmental factors in the vapor intrusion process. Soil moisture content is one of the key factors determining the subsurface vapor concentration profile. This manuscript considers the effects of soil moisture profiles on the soil gas vapor concentration away from any surface capping by buildings or pavement. The “open field” soil gas vapor concentration profile is observed to be sensitive to the soil moisture di...

  10. Cd Distribution of Soil in Dongdagou Baiyin District and Its Influencing Factors%白银区东大沟流域农田土壤Cd分布及其影响因素

    Institute of Scientific and Technical Information of China (English)

    王婷; 南海

    2015-01-01

    This study is aimed to explore Cd distribution characteristics and its influence factors in cultivated soil from Dongdagou in Baiyin district of Baiyin city,Gansu province. The content of Cd,soil organic matter,total N,total P,CEC,pH, soil urease,invertase,catalase and polyphenol oxidase in soil are measured,and the spatial distribution data of Cd are obtained with ArcGIS method. The result shows that the arable layer soil is polluted seriously,the range of Cd contents is 0.170~82.400 mg/kg. The high value area of Cd contents with island-like spacial distribution located mainly in Shapogang and Minqin village,in which Cd contents decreased around. Cd distribution has obvious enrichment regularity in the surface layer of soil profile,and the significant model of negative exponential function is found for Cd. Cd contents are significantly positively correlated with organic matter,and it are very significantly negatively correlated with pH.%为揭示白银区东大沟流域耕地土壤Cd的分布特征及其影响因素,对采集土样的Cd、土壤有机质、全氮、全磷、CEC、pH、土壤脲酶、蔗糖酶、过氧化氢酶和多酚氧化酶含量进行了测定,运用GIS手段分析了耕层土壤Cd空间分布特征。结果表明,耕层土壤Cd浓度范围0.170~82.400 mg/kg,属重度污染。土壤Cd含量高值区出现在沙坡岗和民勤村,呈岛状分布,并以此为中心Cd浓度向周边方向递减。Cd土壤剖面分布具有明显的表层富集规律,符合负指数方程递减规律。表层土壤Cd含量与有机质呈显著正相关,与pH呈极显著负相关。

  11. Development of Soil Crusts Under Simulated Rainfall and Crust Formation on a Loess Soil as Influenced by Polyacrylamide

    Institute of Scientific and Technical Information of China (English)

    HU Xia; LIU Lian-You; LI Shun-Jiang; CAI Qiang-Guo; L(U) Yan-Li; GUO Jin-Rui

    2012-01-01

    This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and identified the relationships between soil crust and splash erosion under simulated rainfall.The effect of polyacrylamide (PAM) on soil aggregate stabilization and crust formation was also investigated.A laboratory rainfall simulation experiment was carried out using soil sample slices.The slices were examined under a polarized light microscopy and a scanning electron microscope (SEM).The results revealed that the soil crusts were thin and were characterized by a greater density,higher shear strength,finer porosity,and lower saturated hydraulic conductivity than the underlying soil.Two types of crusts,i.e.,structural and depositional crusts,were observed.Soil texture was determined to be the most important soil variable influencing surface crust formation; depositional crust formation was primarily related to the skeleton characteristics of the soil and happened when the soil contained a high level of medium and large aggregates.The crust formation processes observed were as follows:1) The fine particles on the soil surface became spattered,leached,and then rough in response to raindrop impact and 2) the fine particles were washed into the subsoil pores while a compact dense layer concurrently formed at soil surface due to the continual compaction by the raindrops.Therefore,the factors that influenced structural crust formation were a large amount of fine particles in the soil surface,continual impact of raindrops,dispersion of aggregates into fine particles,and the formation of a compact dense layer concurrently at the soil surface.It was concluded that the most important factor in the formation of soil crusts was raindrop impact.When polyacrylamide (PAM) was applied,it restored the soil structure and greatly increased soil aggregate stabilization.This effectively prevented crust formation.However,this function of PAM was not continuously effective and

  12. [Influences of biochar and nitrogen fertilizer on soil nematode assemblage of upland red soil].

    Science.gov (United States)

    Lu, Yan-yan; Wang, Ming-wei; Chen, Xiao-vun; Liu, Man-qiang; Chen, Xiao-min; Cheng, Yan-hong; Huang, Qian-ru; Hu, Feng

    2016-01-01

    The use of biochar as soil remediation amendment has received more and more concerns, but little attention has been paid to its effect on soil fauna. Based on the field experiment in an upland red soil, we studied the influences of different application rates of biochar (0, 10, 20, 30, 40 t · hm⁻²) and nitrogen fertilizer (60, 90, 120 kg N · hm⁻²) on soil basic properties and nematode assemblages during drought and wet periods. Our results showed that the biochar amendment significantly affect soil moisture and pH regardless of drought or wet period. With the increasing of biochar application, soil pH significantly increased, while soil moisture increased first and then decreased. Soil microbial properties (microbial biomass C, microbial biomass N, microbial biomass C/N, basal respiration) were also significantly affected by the application of biochar and N fertilizer. Low doses of biochar could stimulate the microbial activity, while high doses depressed microbial activity. For example, averaged across different N application rates, biochar amendment at less than 30 t · hm⁻² could increase microbial activity in the drought and wet periods. Besides, the effects of biochar also depended on wet or drought period. When the biochar application rate higher than 30 t · hm⁻², the microbial biomass C was significantly higher in the drought period than the control, but no differences were observed in the wet period. On the contrary, microbial biomass N showed a reverse pattern. Dissolved organic matter and mineral N were affected by biochar and N fertilizer significantly in the drought period, however, in the wet period they were only affected by N fertilizer rather than biochar. There was significant interaction between biochar and N fertilizer on soil nematode abundance and nematode trophic composition independent of sampling period. Combined high doses of both biochar and N fertilization promoted soil nematode abundance. Moreover, the biochar amendment

  13. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    Science.gov (United States)

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-11-10

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  14. Factors influencing pacing in triathlon.

    Science.gov (United States)

    Wu, Sam Sx; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon.

  15. Bioremediation treatment of hydrocarbon-contaminated Arctic soils: influencing parameters.

    Science.gov (United States)

    Naseri, Masoud; Barabadi, Abbas; Barabady, Javad

    2014-10-01

    The Arctic environment is very vulnerable and sensitive to hydrocarbon pollutants. Soil bioremediation is attracting interest as a promising and cost-effective clean-up and soil decontamination technology in the Arctic regions. However, remoteness, lack of appropriate infrastructure, the harsh climatic conditions in the Arctic and some physical and chemical properties of Arctic soils may reduce the performance and limit the application of this technology. Therefore, understanding the weaknesses and bottlenecks in the treatment plans, identifying their associated hazards, and providing precautionary measures are essential to improve the overall efficiency and performance of a bioremediation strategy. The aim of this paper is to review the bioremediation techniques and strategies using microorganisms for treatment of hydrocarbon-contaminated Arctic soils. It takes account of Arctic operational conditions and discusses the factors influencing the performance of a bioremediation treatment plan. Preliminary hazard analysis is used as a technique to identify and assess the hazards that threaten the reliability and maintainability of a bioremediation treatment technology. Some key parameters with regard to the feasibility of the suggested preventive/corrective measures are described as well.

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

    Science.gov (United States)

    Liu, H.; Yu, Z.

    2008-12-01

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

  17. Surface soil factors and soil characteristics in geo-physical milieu of Kebbi State Nigeria

    Directory of Open Access Journals (Sweden)

    Suleiman Usman

    2016-07-01

    Full Text Available Soil erodibility (K factor is the most important tool for estimation the erosion. The aim of this study Soil factors and surface soil characteristics are important components of agricultural environment. They support surface and subsurface soils to perform many functions to agriculture and economic human developments. Understanding these factors would aid to the recognition of the values that our soil and land offered to humanity. It is therefore, aim of this study to visualise and examine the soil factors and surface soil characteristics in Kebbi State Nigeria. An Integrated Surface Soil Approach (ISSA was used in the classification and description of soil environment in the study region. The factors constituted in the ISSA are important components of soil science that theories and practice(s noted to provide ideas on how soil environment functioned. The results indicate that the surface soil environments around Arewa, Argungu, Augie, Birnin Kebbi and Dandi are physically familiar with the following surface soil characteristics: bad-lands, blown-out-lands, cirque-lands, fertile-lands, gullied-lands, miscellaneous and rock-outcrops.The major soil factors observed hat played an important role in surface soil manipulations and soil formation are alluvial, colluvial, fluvial and lacustrine; ant, earthworms and termite; and various forms of surface relief supported by temperature, rainfall, relative humidity and wind. Overall, the surface soil environment of the region was describe according to their physical appearance into fadama clay soils, fadama clay-loam soils, dryland sandy soils, dryland sandy-loam soils, dryland stony soils and organic-mineral soils.

  18. 福建省蔬菜产地土壤汞污染状况及其影响因素%Mercury Pollution and its Influencing Factors of Vegetable Soils in Fujian Province, China

    Institute of Scientific and Technical Information of China (English)

    洪曾纯; 郭永玲; 王果

    2015-01-01

    An investigation on mercury pollution of the soils was carried out over the vegetable fields at the suburbs of 12 countries of Fujian Province. The main soil properties which influenced the accumulation and the availability of soil mercury were discussed. Results showed that soil total mercury of the vegetable fields was 0.038~1.81 mg·kg-1, and 33.04%of the total soil mercury of the soil samples exceeded the Na-tional Secondary Standard for acidic agricultural soils. Total soil mercury had significant and positive correlations with the contents of clay, silt, organic matter, as well as CEC of the soils, indicating that these soil properties were in favour of the accumulation of mercury in the soils. The available soil mercury was between 0.003 mg·kg-1 and 0.095 mg·kg-1, showing a significant and positive correlation with total soil mer-cury. The availability factions of soil mercury decreased with increasing soil organic matter, suggesting that organic matter was the major soil property which influenced the availability of mercury in the soils.%研究了福建省12个县(市、区)郊区部分菜地土壤的汞污染状况,讨论了影响土壤汞累积及汞有效性的主要土壤学性质。结果表明:调查的菜地土壤全汞含量范围为0.038耀1.81 mg·kg-1,其中有33.04%的土壤全汞含量超出国家土壤环境质量二级标准。土壤全汞含量与土壤粘粒、粉粒、有机质含量及CEC之间均呈极显著的正相关,说明这些土壤性质有利于汞在土壤中的累积。土壤有效汞含量范围为0.003耀0.095 mg·kg-1,与土壤全汞含量之间呈极显著的线性正相关。土壤汞有效度随土壤有机质的增加而降低,表明有机质是影响土壤汞有效性的主要土壤学性质。

  19. Soil Biological Parameters Influenced By Cocoa Management Systems

    Science.gov (United States)

    Cropping systems have a profound influence on the soil micro-fauna and they are responsible for nutrient cycling, and add stability to the soil. At Tarapoto, Peru, two field experiments were established on acidic medium fertility Alfisol to assess the influence of management systems on cacao rhizosp...

  20. Spatial variability of soil moisture content and its influencing factors in small Karst catchment during dry period%喀斯特小流域土壤含水率空间异质性及其影响因素

    Institute of Scientific and Technical Information of China (English)

    付同刚; 陈洪松; 张伟; 高鹏; 王克林

    2014-01-01

    and other soil properties, including bulk density (BD), capillary capacity (CP), non-capillary capacity (NCP), soil organic carbon (SOC), and rock fragment content (RC). Environmental factors including topographical position (upper-slope, middle-slope, lower-slope and depression), land use type (forestland, shrubland, shrub-grassland and farmland), slope gradient (SG), slope aspect (SA) and bare rock (BR) were investigated around the sampling points. Spatial variability of SMC and its influencing factors were analyzed by both geostatistical and classical analysis methods. The results showed that the mean value of SMC was 34.43%. The SMC had a moderate variation with the coefficient of variation of 0.33. The geostatistical results showed that the semivariance of SMC was best fitted by exponential model with a higher determination coefficient of 0.910. The range was 381.00 m and the nugget/sill value was 0.382, indicating a moderate spatial correlation of SMC. When the lag distance was smaller than 200 m, the variation in 120° direction was higher than that of 30° direction. However, when the lag distance was exceeded 200 m, no anisotropy was found in 120° and 30° directions with the anisotropy ratio fluctuated around 1. The Kriging map showed that SMC generally decreased with the increasing altitude. Most of the slope had a lower SMC value less than 35%. The highest SMC value always appeared in the east of the depression which was higher than 50%. The Pearson correlation analysis showed that CP had a significant (p<0.01) positive correlation with SMC but RC and BD had a significant negative correlation with SMC. NCP had a significantly negatives effect on SMC with the significant value of 0.022. However, SOC only significantly affected SMC at 0.10 level. This suggested that all the soil properties had important influence on SMC. However, for the topographical factors, only SG had a significant influence on SMC with the correlation coefficient of-0.435 (p<0

  1. Denitrification in upland of China: Magnitude and influencing factors

    Science.gov (United States)

    Wang, Jinyang; Yan, Xiaoyuan

    2016-12-01

    A better understanding of influencing factors and accurate estimate of soil denitrification is a global concern. Here we present a synthesis of 300 observations of denitrification in Chinese upland soils from 39 field and laboratory studies using the acetylene inhibition technique. The results of a linear mixed model analysis showed that the rates of soil denitrification were significantly affected by crop type, soil organic carbon, soil pH, the measurement period, and the rate of N application. The emission factor (EF) and N2O/(N2O + N2) ratio for soil denitrification were on average 2.11 ± 0.17% and 0.508 ± 0.020, respectively. Our meta-analysis indicated that N fertilization increased soil denitrification by 311% (95% CI: 279-346%) and 112% (95% CI: 66-171%) in the field and laboratory studies, respectively. Substantial interactive effects between soil properties and N fertilization on soil denitrification were found. Although the highest values of both the rate of denitrification and the EF were found in vegetable fields, the size of the stimulating effect of N fertilization on soil denitrification was lower in vegetable fields than in maize and wheat fields. These results suggest that the crop-specific effect is important and that vegetable fields are potential hot spots of denitrification in Chinese uplands. Based on either the EF or the N2O/(N2O + N2) ratio obtained, the estimated amount of total denitrification from the upland soils was an order of magnitude lower than that from budget calculations, suggesting that the acetylene inhibition technique may significantly underestimate denitrification in Chinese upland soils.

  2. Factors Influencing Healthcare Service Quality

    Directory of Open Access Journals (Sweden)

    Ali Mohammad Mosadeghrad

    2014-07-01

    Full Text Available Background The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results Quality in healthcare is a production of cooperation between the patient and the healthcare provider in a supportive environment. Personal factors of the provider and the patient, and factors pertaining to the healthcare organisation, healthcare system, and the broader environment affect healthcare service quality. Healthcare quality can be improved by supportive visionary leadership, proper planning, education and training, availability of resources, effective management of resources, employees and processes, and collaboration and cooperation among providers. Conclusion This article contributes to healthcare theory and practice by developing a conceptual framework that provides policy-makers and managers a practical understanding of factors that affect healthcare service quality.

  3. 水热因子对克氏针茅草原土壤呼吸及其土壤温度敏感性的影响%The influence of hydrothermal factors on soil respiration and soil temperature sensi-tivity of Stipa krylovii steppe,Inner Mongolia,China

    Institute of Scientific and Technical Information of China (English)

    谷蕊; 潮洛濛; 张立欣; 苏力德; 万志强; 闫玉龙; 陈雅丽; 高清竹

    2015-01-01

    respiration is an important component of the carbon cycle on the steppe and the main source of soil carbon losses.In this study,typical grassland dominated by S .krylovii,located in Mao-deng Ranch,Xilinhaote,Inner Mongolia was selected as the study area.An open top type growth chamber was used to simulate the response of soil respiration to temperature and precipitation from 2011 to 2013.The Auto-mated Soil CO2 Flux System (LI-8100,LI-COR,NE)was used to observe the soil respiration in the study area during the growing season (May to September).Air temperature,soil temperature and soil moisture were measured using the EM50 Data Collection System (Decagon Devices,Inc.,NE,USA).Soil samples were col-lected,soil nutrients and microbial numbers were determined and correlation analysis used to explore associa-tions between soil respiration rate and environmental factors.Soil respiration was significantly affected by air temperature and soil water content (P <0.01).Under warm and warm-moist conditions respectively soil respi-ration rates were 2.60 μmol/(m2 ·s)and 1.96 μmol/(m2 ·s)(2012)and 3.38 μmol/(m2 ·s)and 2.09 μmol/(m2 ·s)(2013 );differences between years were significant (P <0.05 ).Increased air temperature and de-creased soil water content both inhibited soil respiration.During the 2013 growing season additional environ-mental factors including soil organic carbon,total nitrogen and soil microbial mass may also have affected soil respiration.The Q10 temperature coefficient was significantly increased by warm-moist conditions.It was con-cluded that soil respiration is mainly influenced by hydrothermal conditions;increased air temperature and re-duced soil moisture content inhibit soil respiration.The relationship between environment factors and soil res-piration on the Inner Mongolian steppe is complex and requires further research.

  4. 固定化微生物修复石油污染土壤影响因素研究%Study on influencing factors of immobilized microorganisms for remedying oil-contaminated soil

    Institute of Scientific and Technical Information of China (English)

    张秀霞; 白雪晶; 徐娜娜; 刘永博; 孔甜甜

    2013-01-01

    针对石油污染土壤修复,利用实验室已筛选的高效石油降解单菌SM-3,以天然有机材料为载体,吸附法制备固定化微生物.将游离与固定化微生物应用于室内花盆模拟修复石油污染土壤,对C/N/P、微生物投加量、石油含量、氧化剂和表面活性剂设计5因素4水平正交实验,探讨不同修复时期各影响因素的重要性顺序,最佳条件下各菌株的修复效果.结果表明,不同微生物在不同降解时期,各影响因素的重要性会发生变化;经过21 d的修复,固定化单菌SM-3石油降解率为22.77%,修复过程中,接种量是最重要的影响因素,营养元素N、P投加影响较大,表面活性剂和氧化剂影响次之.%Aiming to remedy the oil-contaminated soil, high-efficiency oil-degrading single strain SM-3 which had been screened in the laboratory was elected as experimental strain. Use natural organic materials as carriers to obtain immobilized microorganism by adsorption method. Free and immobilized microorganisms were applied to simulate and remedy the oil-contaminated soil in the indoor pot. The orthogonal experiment of five factors (C/N/P, inoculated quantity, oil content, oxidant and surfactant) and four levels was designed to investigate the sequence of the importance of each influencing factor in different remedial periods and the remedial effect of each strain under their respective optimum conditions. The experiment showed that for different microorganisms, the importance of each factor changed in different periods. After the remediation of 21 days, the oil degradation rate of immobilized single strain SM-3 was 22. 77% . During the biodegradation, inoculated quantity was the most important factor. Nutrients nitrogen and phosphorus had a relative greater effect on degradation rate compared with the influence of oxidant and surfactant.

  5. Influences of Oyster Shell Soil Conditioner on Soil and Plant Rhizospheric Microorganisms

    Institute of Scientific and Technical Information of China (English)

    JIANG Guoliang; LIU Yun; DING Mingyu; KONG Xiuqin

    2003-01-01

    Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric microorganisms, especially nitrogen-fixers, and intensify soil respiration in proportion to the dose and fertilizing time of the conditioner, leading to the increase in the number of nitrogen fixing bacteria and the decrease in the number of bacteria with special nutrition demands.

  6. 山东省土壤酸化特征及其影响因素分析%Characteristics of soil acidification and its influencing factors in Shandong province

    Institute of Scientific and Technical Information of China (English)

    杨歆歆; 赵庚星; 李涛; 万广华; 李萍

    2016-01-01

    -alkaline, accounting for 67.87% of this soil group points. The cinnamon soil, lime concretion black soil, paddy soil were mainly neutral, accounting for 50.66%, 36.54% and 54.07% of these three soil group points, respectively. The skeletal soil and brown earth were mainly weak-acidic, accounting for 38.90% and 41.22% of these two soil group points, respectively. The soil pH averages of fluvio-aquatic soil, cinnamon soil, lime concretion black soil, paddy soil, skeletal soil and brown earth decreased in turn. The soil acidification of brown earth was the most serious, while fluvio-aquatic soil was the least acid. The soil acidification in Shandong province showed an increasingly serious trend may due to the natural geographic and climatic conditions of local environment. Additionally, other possible factors such as different land use types, unreasonable fertilizations and managements were also accountable. By adjusting soil pH value, the contents of soil nutrients could be controlled and the growth of crops could be promoted.%为弄清山东省土壤酸化状况,采用统计分析和空间分析方法,对山东省测土配方施肥项目数据进行分析,并与第2次全国土壤普查的部分数据作比较,分析山东省不同区域、不同土地利用类型、不同土类的土壤酸化状况。结果表明:1)山东省的酸化土壤面积为126.4万hm2,占全省土壤面积的8.13%,与第2次全国土壤普查相比,酸化面积增加了8.07%;2)山东省土壤pH值呈现自西向东、由北向南逐渐减小的趋势,酸化土壤集中分布在鲁东和鲁南地区的威海市、烟台市、日照市、青岛市和临沂市;3)不同土地利用类型中,园地中的茶园酸化程度较重,耕地酸化程度最轻;4)不同土类中,棕壤酸化程度最重,潮土酸化程度最轻。山东省土壤酸化呈现严重的趋势,其自然地理气候条件、不同土地利用方式以及施肥管理等是可能导致土壤酸化的主要原因。

  7. Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

    Directory of Open Access Journals (Sweden)

    Lia C R S Teixeira

    Full Text Available Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies, Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

  8. Plant and Bird Presence Strongly Influences the Microbial Communities in Soils of Admiralty Bay, Maritime Antarctica

    Science.gov (United States)

    Teixeira, Lia C. R. S.; Yeargeau, Etienne; Balieiro, Fabiano C.; Piccolo, Marisa C.; Peixoto, Raquel S.; Greer, Charles W.; Rosado, Alexandre S.

    2013-01-01

    Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific. PMID:23840411

  9. Influence of soil on groundwater geochemistry in a carbonate aquifer, southern Italy

    Directory of Open Access Journals (Sweden)

    Tiziano Boschetti

    2014-01-01

    Full Text Available The role of soil compositions in influencing groundwater geochemistry in carbonate aquifers is still little known. Nothing is known regarding the influence of pyroclastic soils (andisol within the carbonate Apennines in central-southern Italy, despite their wide distribution. In this study we analyze some physical and chemical properties of pyroclastic soil at the Acqua dei Faggi experimental site (southern Italy, to assess its influence on groundwater geochemistry. Chemical analyses were carried out on saturated paste extracts and a physical analogue model was developed through two column experiments. Physico-chemical properties of rainwater and spring water, and some microbiological features of the soil medium were also taken into consideration. The studied soil has a great influence in modifying rainwater chemistry during percolation. About the 50% of HCO3- and Ca2+ in spring water is due to interaction between percolation water and soil medium, and equilibrium with calcite is reached at this stage. The Na+/K+ ratio is buffered by clay minerals in the soil by primary silicates in the pyroclastic cover and then buffered. Cl- and SO42- concentrations in spring water are very close to that of soil infiltration water during short-term interaction with soil, but a decline is showed during long-term cause to the anions adsorption effect in the andisol. Chemical and microbiological investigations show the existence of a soil microbial community that allows denitrification and nitrate reduction. Infiltration processes cause anoxic conditions within the soil medium, therefore the absence of NH4+ in spring water throughout the observation period should be due to anammox processes. These findings suggest that hydrochemistry and spring chemographs may be significantly influenced by several factors, such as relationships between soil and rainwater, vegetation, and microbial communities, which are not necessarily correlated with lithological and structural

  10. Factors influencing pacing in triathlon

    Directory of Open Access Journals (Sweden)

    Wu SSX

    2014-09-01

    Full Text Available Sam SX Wu,1 Jeremiah J Peiffer,2 Jeanick Brisswalter,3 Kazunori Nosaka,1 Chris R Abbiss1 1Centre for Exercise and Sports Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, WA, Australia; 2School of Psychology and Exercise Science, Murdoch University, Perth, WA, Australia; 3Laboratory of Human Motricity, Education Sport and Health, University of Nice Sophia Antipolis, Nice, France Abstract: Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. Keywords: cycle, endurance, multisport, pacing strategy, run, swim

  11. The influence of heavy metals on soil microflora

    Directory of Open Access Journals (Sweden)

    Štyriaková Iveta

    2002-12-01

    Full Text Available The aim of our contribution was to ascertain an influence of heavy metals on quantitative and qualitative composition of soil microflora. Our experiment was directed to quantitative isolation of culturable bacteria from individual soil samples and to the comparison of the amounts and colony morphology of the isolates from various soil samples. These soil samples were characteristic by a difference in pH, heavy metals and humus contents. Despite the differences between individual soil samples, the most of bacterial isolates were represented by Bacillus genus (especially Bacillus cereus and Bacillus mycoides which belongs to the heavy metal resistant bacterial kinds.

  12. Factors influencing the tolerance of flufenacet applications in winter rye

    OpenAIRE

    2016-01-01

    In winter rye which is grown mostly on locations with a lighter soil texture loose silky-bent grass (Apera spica-venti) is a dominate weed grass. Because of increasing herbicide resistance the control of A. spica-venti becomes more difficult. To manage resistant weed grass populations in winter rye flufenacet is a very important active substance. However, the application of flufenacet can lead to substantially culture damage. The influence of different factors influencing the tolerance of ...

  13. Factors influencing women's decisions to purchase specific ...

    African Journals Online (AJOL)

    Keywords: multi-nutrient supplements; survey; children; women's decisions. Factors influencing .... associations between level of education and various factors influencing women's ..... Social marketing improved the use of multivitamin and ...

  14. Factors Influencing Learner Permit Duration

    Directory of Open Access Journals (Sweden)

    Johnathon P. Ehsani

    2016-12-01

    Full Text Available An increasing number of countries are requiring an extended learner permit prior to independent driving. The question of when drivers begin the learner permit period, and how long they hold the permit before advancing to independent licensure has received little research attention. Licensure timing is likely to be related to “push” and “pull” factors which may encourage or inhibit the process. To examine this question, we recruited a sample of 90 novice drivers (49 females and 41 males, average age of 15.6 years soon after they obtained a learner permit and instrumented their vehicles to collect a range of driving data. Participants completed a series of surveys at recruitment related to factors that may influence licensure timing. Two distinct findings emerged from the time-to-event analysis that tested these push and pull factors in relation to licensure timing. The first can be conceptualized as teens’ motivation to drive (push, reflected in a younger age when obtaining a learner permit and extensive pre-permit driving experience. The second finding was teens’ perceptions of their parents’ knowledge of their activities (pull; a proxy for a parents’ attentiveness to their teens’ lives. Teens who reported higher levels of their parents’ knowledge of their activities took longer to advance to independent driving. These findings suggest time-to-licensure may be related to teens’ internal motivation to drive, and the ability of parents to facilitate or impede early licensure.

  15. Mathematical Analyses for the Influence of Soil Conditions and Nutrient Interactions on Cotton Yields

    Institute of Scientific and Technical Information of China (English)

    ZHANGJIANHUI; HUCHANGQING; 等

    1996-01-01

    The influence of soil chemical properties and soil nutrition on cotton yields was studied by means of establishing mathematical models.The nultivarate quadratic regression equations developed by a stepwise regression method not only presented the single effect of soil factors but also displayed the interaction(synergistic or antagonistic) of soil nutrients.The effect of individual factor and the way of nutrient interaction were further analysed by the path analysis method.The results showed that among major factors affecting cotton yields,there existed the interactions between macronutrients(available P× available K),and between macronutrients and microelements(N×Zn,P×Mo,P×Cu,P×Zn,K×Mo)besides the single effect of soil pH,total P ,available Cu and available Zn.

  16. Influence of Panax ginseng Continuous Cropping on Metabolic Function of Soil Microbial Communities

    Institute of Scientific and Technical Information of China (English)

    YING Yi-xin; DING Wan-long; ZHOU Ying-qun; LI Yong

    2012-01-01

    Objective To investigate the influence of Panax ginseng continuous cropping on the carbon substrate metabolic activity of microbes in soils sampled from Dafang,Huangni,and Wulidi in Jilin Province,China.Methods Soil metabolisms of soil communities were characterized by community level physiological profiles using BIOLOGTM EcoPlate.Results Soils sampled from the three sites were analyzed and their metabolic activities were compared.Principal component analysis explored the significant variance in metabolic function of microbial communities in soils,though the Shannon index and the evenness index of them were similar.Futhermore,two principal components(PC1 and PC2),which contributed 67.83% and 10.78% of total variance,were extracted respectively.And also,substrates significantly correlated with PC1 and PC2 at the three sampling sites were identified.Conclusion Characteristic of soil is the primary factor influencing microbial communities,and P.ginseng continuous cropping has significant influence on microbial community.Though soil samples show similar microbial metabolic profiles,microbial communities in rhizosphere soil are changed obviously during the cultivation of P.ginseng,which would finally result in the unbalance of microbial community.Phytopathogens would gradually be the predominants in rhizosphere soil and make P.ginseng sick.

  17. The influence of surface reflectance anisotropy on estimation of soil properties

    Science.gov (United States)

    Bartholomeus, Harm; Roosjen, Peter; Clevers, Jan

    2014-05-01

    The spatial variation in soil properties is an important factor for agricultural management. Unmanned airborne vehicles (UAV's) equipped with a hyperspectral mapping system may provide these data, but anisotropic reflectance effects may have an influence on the derived soil properties. Besides influencing the reflectance, angular observations may deliver added information about soil properties. We investigated the anisotropic behavior of 59 soil samples with a large variation in soil composition, by measuring their reflectance (350-2500 nm) over 92 different angles using a robot-based laboratory goniometer system. The results show that the anisotropic behavior of the soils influences the measured reflectance significantly, which limits the accurate prediction of soil properties (OM and clay especially). However, prediction accuracies of OM increase when spectra are measured under specific angles. Prediction accuracies further increase when a combination of observation angles is being used. Apart from that, using UAV's the wavelength range is limited to about 1000 nm. In general, this will decrease the model performance, but our results show that this effect can largely be compensated by combining multiple observation angles. Altogether, we demonstrate that surface anisotropy influences the prediction of soil properties negatively. This effect can be reduced by combining spectra acquired under different angles. Moreover, predictions can be improved if combinations of different observation angles are used.

  18. Influence factors and prediction model for soil nickel ecological threshold%土壤中镍生态阈值的影响因素及预测模型

    Institute of Scientific and Technical Information of China (English)

    王小庆; 马义兵; 黄占斌

    2012-01-01

    Correction with leaching-aging factor should be applied in deriving soil ecological threshold with toxicity data from laboratory toxicity test in order to eliminate the difference of toxicity in field-contaminated soils and that in laboratory amended soils. In the paper the soil ecological threshold for soil nickel was derived with 17 species toxicity data and corrected with leaching-aging factor. The results showed that leaching effect was more significant in the soils with pH>8.5, and the values of leaching factors were all more than 2 except for exceptional soil. Aging effect was more significant in the soil with pH>7.0 and the value of aging factor increased with pH value. Main soil factors controlling soil ecological threshold for nickel were found as soil pH value and soil organic carbon content (OC). The pH value, OC and CEC could explain the nickel ecological threshold variation by 86.2%, 9.0% and 4.1% proportion respectively. The two-factor predictive model based on soil pH and OC were developed and validated for predicting ecological threshold of soil nickel. The results showed that the model could predict ecological threshold for nickel based on soil pH and OC well and the determination coefficient (R2) reached up to 0.972. The model can be applied in predicting nickel ecological threshold for different kinds of soils according to the soil properties.%利用实验室获得的毒理学数据建立土壤生态阈值需通过老化-淋洗因子校正以消除外源添加的人工污染与野外实际污染的差异.该文利用基于中国土壤的17个物种的镍毒理学数据建立镍土壤生态阈值并利用老化-淋洗因子对数据进行校正.结果表明淋洗效应在pH值大于8.5的土壤中尤为显著,除个别土壤外,淋洗因子(LF)值均大于2;老化效应在碱性土壤(pH值>7.0)中更为显著,且老化因子(AF)值随着土壤pH值的升高而增大.pH值、有机碳含量(OC)、阳离子交换量(CEC)可分别

  19. Influence of soil structure on the "Fv approach" applied to (238)U and (226)Ra.

    Science.gov (United States)

    Blanco Rodríguez, P; Vera Tomé, F; Lozano, J C

    2017-02-01

    The soil-to-plant transfer factors were determined in a granitic area for the two long-lived uranium series radionuclides (238)U and (226)Ra. With the aim to identify a physical fraction of soil whose concentration correlates linearly with the plant concentration, the soil compartment was analyzed in various stages. An initial study identified the soil compartments as being either bulk soil or its labile fraction. The bulk soil was subsequently divided into three granulometric fractions consisting of: coarse sand, fine sand, and silt and clay. The soil-to-plant transfer of radionuclides for each of these three texture fractions was analyzed. Lastly, the labile fraction was extracted from each textural part, and the activity concentration of the radionuclides (238)U and (226)Ra was measured. In order to assess the influence of soil texture on the soil-to-plant transfer process, we sought to identify possible correlations between the activity concentration in the plant compartment and those found in the different fractions within each soil compartment. The results showed that the soil-to-plant transfer process for uranium and radium depends on soil grain size, where the results for uranium showed a linear relationship between the activity concentration of uranium in the plant and the fine soil fraction. In contrast, a linear relation between the activity concentration of radium in the plant and the soil coarse-sand fraction was observed. Additionally, the presence of phosphate and calcium in the soil of all of the compartments studied affected the soil-to-plant transfer of uranium and radium, respectively.

  20. Soil microbial communities: Influence of geographic location and hydrocarbon pollutants

    CSIR Research Space (South Africa)

    Maila, MP

    2006-02-01

    Full Text Available (CLPP) and Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR-DGGE). Hydrocarbon contaminated and uncontaminated soils from different geographical locations were used in the study. In addition, the influence or relevance...

  1. Soil pH and electrical conductivity are key edaphic factors shaping bacterial communities of greenhouse soils in Korea.

    Science.gov (United States)

    Kim, Jeong Myeong; Roh, An-Sung; Choi, Seung-Chul; Kim, Eun-Jeong; Choi, Moon-Tae; Ahn, Byung-Koo; Kim, Sun-Kuk; Lee, Young-Han; Joa, Jae-Ho; Kang, Seong-Soo; Lee, Shin Ae; Ahn, Jae-Hyung; Song, Jaekyeong; Weon, Hang-Yeon

    2016-12-01

    Soil microorganisms play an essential role in soil ecosystem processes such as organic matter decomposition, nutrient cycling, and plant nutrient availability. The land use for greenhouse cultivation has been increasing continuously, which involves an intensive input of agricultural materials to enhance productivity; however, relatively little is known about bacterial communities in greenhouse soils. To assess the effects of environmental factors on the soil bacterial diversity and community composition, a total of 187 greenhouse soil samples collected across Korea were subjected to bacterial 16S rRNA gene pyrosequencing analysis. A total of 11,865 operational taxonomic units at a 97% similarity cutoff level were detected from 847,560 sequences. Among nine soil factors evaluated; pH, electrical conductivity (EC), exchangeable cations (Ca(2+), Mg(2+), Na(+), and K(+)), available P2O5, organic matter, and NO3-N, soil pH was most strongly correlated with bacterial richness (polynomial regression, pH: R(2) = 0.1683, P pH: R(2) = 0.1765, P pH and EC (Mantel test, pH: r = 0.2672, P 1%), the relative abundances of Proteobacteria, Gemmatimonadetes, Acidobacteria, Bacteroidetes, Chloroflexi, and Planctomycetes were also more strongly correlated with pH and EC values, compared with other soil cation contents, such as Ca(2+), Mg(2+), Na(+), and K(+). Our results suggest that, despite the heterogeneity of various environmental variables, the bacterial communities of the intensively cultivated greenhouse soils were particularly influenced by soil pH and EC. These findings therefore shed light on the soil microbial ecology of greenhouse cultivation, which should be helpful for devising effective management strategies to enhance soil microbial diversity and improving crop productivity.

  2. Soil Property Influences on Xiphinema americanum Populations as Related to Maturity of Loess-Derived Soils.

    Science.gov (United States)

    Schmitt, D P

    1973-10-01

    Field populations of Xiphinerna americanum around roots of Syringa vulgaris 'President Lincoln' were larger in Marshall silty clay loam, a medially developed loess soil, than in Monona silt loam, a minimally developed loess soil. Most X. amerieanum occurred in the top 15 cm of soil, with few below 30 cm. Maximum numbers occurred in August of both years in the Marshall soil, and in August 1969 and June 1970 in the Monona soil. Population fluctuations during the growing season were coincident with changes in soil moisture content. Although the population fluctuation pattern was the same at each depth tested, the adult-to-juvenile ratio increased in one soil while it decreased in the other. Numbers of X. americanum decreased as root weights decreased within a soil profile, but they were not correlated with root weights over all soils and depths. More X. americanum were recovered from the Marshall than from the Monona soil, but fibrous root weights were greater in the Monona soil. Survival of X. americanum in soil columns in growth chamber experiments was better in the Marshall than in the Monona soil. Movement and survival were different in identically textured Monona A and B horizon soils. Factors related to the ion exchange sites may affect X. americanum.

  3. Distribution and Content of Selenium in Soil and Its Influence Factors in Zhangqiu Area%章丘地区土壤硒的含量分布及影响因素

    Institute of Scientific and Technical Information of China (English)

    赵西强; 张贵丽

    2015-01-01

    以章丘地区土壤为对象,系统分析了表层、深层土壤及8条剖面土壤中Se元素的含量水平,研究了土壤中Se的分布特征及其与土壤类型、成土母质、地形地貌和土壤理化性质及组分的关系。结果表明:章丘地区表层土壤中Se含量在0.1~0.8 mg/kg之间,以中硒土壤为主,富硒土壤面积173 km2。土壤类型中,水稻土Se平均含量水平最高,为0.55 mg/kg;成土母质中以石炭—二叠纪泥页岩发育的土壤Se含量最高;剖面土壤中的Se主要在表层富集。影响章丘地区土壤Se含量分布的主要因素是成土母质、地形地貌、土壤pH、有机质及土壤中硫、铁铝氧化物等组分。%Setting soil in Zhangqiu area as an example, the contents of Se in surface soil, deep soil and section 8 porfiles have been analyzed comprehensively, distribution characteristics, and the relation between distribution and soil types, soil parent materials, topography, geophysical and geochemical property and components have been studied as well. It is showed that the content of Se in surface soil is 0. 1~0. 8mg/kg. It is mainly composed of se-lenium medium soil, while the square of selenium rich is 173km2 . Among soil types, the average content of Se in paddy soil is the highest as 0. 55mg/kg;while among soil parent materials, the content of Se in Carboniferous Permian soil is the highest. Se is concentrated in the surface in profile soil. The main factors affected the distribu-tion of Se content in Zhangqiu area are soil parent material, topography, soil pH, organic matter, sulfur, iron and aluminum oxides and other components.

  4. A New European Slope Length and Steepness Factor (LS-Factor for Modeling Soil Erosion by Water

    Directory of Open Access Journals (Sweden)

    Panos Panagos

    2015-04-01

    Full Text Available The Universal Soil Loss Equation (USLE model is the most frequently used model for soil erosion risk estimation. Among the six input layers, the combined slope length and slope angle (LS-factor has the greatest influence on soil loss at the European scale. The S-factor measures the effect of slope steepness, and the L-factor defines the impact of slope length. The combined LS-factor describes the effect of topography on soil erosion. The European Soil Data Centre (ESDAC developed a new pan-European high-resolution soil erosion assessment to achieve a better understanding of the spatial and temporal patterns of soil erosion in Europe. The LS-calculation was performed using the original equation proposed by Desmet and Govers (1996 and implemented using the System for Automated Geoscientific Analyses (SAGA, which incorporates a multiple flow algorithm and contributes to a precise estimation of flow accumulation. The LS-factor dataset was calculated using a high-resolution (25 m Digital Elevation Model (DEM for the whole European Union, resulting in an improved delineation of areas at risk of soil erosion as compared to lower-resolution datasets. This combined approach of using GIS software tools with high-resolution DEMs has been successfully applied in regional assessments in the past, and is now being applied for first time at the European scale.

  5. Influence of grazing exclosure on vegetation biomass and soil quality

    Directory of Open Access Journals (Sweden)

    Shagufta Qasim

    2017-03-01

    Full Text Available This study investigated the influence of sixteen years exclosure from unmanaged grazing on aboveground vegetation biomass, soil organic matter (SOM, soil aggregation and nitrogen (N mineralization in arid shrubland of Baluchistan, Pakistan. Sampling was carried out from three sites along the chronosequence of secondary succession. One site was located at open-for-grazing area (grazed site and the other two sites were located in the area that is protected since 1998. One of the protected site is more remote from grazing (protected site 1 where the land is less disturbed and has thick vegetation than the other protected site (protected site 2. Results showed a significant difference for aboveground vegetation biomass across sites and was in the order of protected site 1> protected site 2> grazed site. Soil organic matter was 53% and 46% higher in protected sites than grazed site. Aggregates larger than 2 mm size were not detected in soil from grazed site but represented 4.5% and 3% of the sample soil profile at the protected site 1 and protected site 2, respectively. Rate of N mineralization was lower in soils at the grazed site as compared to soils at the protected sites. Soil moisture contents were significantly lower at grazed site and showed a strong positive correlation with aboveground vegetation biomass. This study demonstrates that unmanaged grazing severely affected aboveground vegetation biomass, soil organic matter, large-sized soil aggregates, nitrogen mineralization and soil moisture contents. Short term exclosure from grazing (~16 years can enhance aboveground vegetation biomass and soil quality in terms of soil organic matter accumulation, soil aggregation, retention of soil moisture and nitrogen mineralization in this arid rangeland.

  6. Modification of the USLE K factor for soil erodibility assessment on calcareous soils in Iran

    Science.gov (United States)

    Ostovari, Yaser; Ghorbani-Dashtaki, Shoja; Bahrami, Hossein-Ali; Naderi, Mehdi; Dematte, Jose Alexandre M.; Kerry, Ruth

    2016-11-01

    The measurement of soil erodibility (K) in the field is tedious, time-consuming and expensive; therefore, its prediction through pedotransfer functions (PTFs) could be far less costly and time-consuming. The aim of this study was to develop new PTFs to estimate the K factor using multiple linear regression, Mamdani fuzzy inference systems, and artificial neural networks. For this purpose, K was measured in 40 erosion plots with natural rainfall. Various soil properties including the soil particle size distribution, calcium carbonate equivalent, organic matter, permeability, and wet-aggregate stability were measured. The results showed that the mean measured K was 0.014 t h MJ- 1 mm- 1 and 2.08 times less than the estimated mean K (0.030 t h MJ- 1 mm- 1) using the USLE model. Permeability, wet-aggregate stability, very fine sand, and calcium carbonate were selected as independent variables by forward stepwise regression in order to assess the ability of multiple linear regression, Mamdani fuzzy inference systems and artificial neural networks to predict K. The calcium carbonate equivalent, which is not accounted for in the USLE model, had a significant impact on K in multiple linear regression due to its strong influence on the stability of aggregates and soil permeability. Statistical indices in validation and calibration datasets determined that the artificial neural networks method with the highest R2, lowest RMSE, and lowest ME was the best model for estimating the K factor. A strong correlation (R2 = 0.81, n = 40, p < 0.05) between the estimated K from multiple linear regression and measured K indicates that the use of calcium carbonate equivalent as a predictor variable gives a better estimation of K in areas with calcareous soils.

  7. Analysis on influence factors of soil Pb and Cd in agricultural soil of Changsha suburb based on geographically weighted regression model%农田土壤铅、镉含量影响因素地理加权回归模型分析

    Institute of Scientific and Technical Information of China (English)

    刘琼峰; 李明德; 段建南; 吴海勇; 洪曦

    2013-01-01

    Contamination of suburban, agricultural soils with heavy metals draws great attention because of its potential threat to food safety and its detrimental effects on the ecosystem. The origins of soil heavy metals in the suburban interface are usually controlled by many factors, such as parent material, industrial activities, and agriculture. To decrease heavy metals pollution risks effectively in suburban areas and further to establish reliable protection measures, it is quite necessary to understand their sources and spatial patterns. The ordinary linear regression model (OLS) has been frequently used to analyze the relationship between soil heavy metals and their influential factors. However, OLS is only in a global or an average sense to estimate parameters, and it is unable to reflect spatial local variation or test spatial non-stationarity.Geographically weighted regression models (GWR) are a powerful tool for exploring spatial heterogeneity. The underlying idea of GWR is that parameters may be estimated anywhere in the study area given a dependent variable and a set of one or more independent variables which have been measured at known locations. Not only can it test spatial non-stationarity, but it can also provide the corresponding solutions. As a local model, GWR modeling has been applied in research on urban housing land prices and the spatial factors of economic development, but it has seldom been applied to the origins and spatial structure of soil heavy metals. A survey was conducted in this study to determine the possible sources of heavy metals in agricultural soils of the suburban area of Changsha. A total of 513 surface soil samples were collected, and the concentrations of Pb and Cd were analyzed. Typical influences on soil Pb and Cd concentration were identified from soil properties and geographic locations, such as soil pH, organic matter, alkali-hydro nitrogen, rapidly available phosphorus, rapidly available potassium, slowly available potassium

  8. FACTORS INFLUENCING THE EVOLUTION OF YOUTH TRAVEL

    Directory of Open Access Journals (Sweden)

    Student Claudia MOISĂ

    2010-01-01

    Full Text Available Youth travel is an important part of global tourism, consequently, getting to know the evolution of this form of tourism requires an approach of the aspects regarding the permissive and restrictive factors that influence the youth travel dynamic worldwide. In terms of the factors that influence youth travel, we highlighted these two categories of factors (permissive and restrictive and, within each category, we tried to singularize the influence of every factor over youth travel.

  9. Influence of Soil Moisture on Soil Gas Vapor Concentration for Vapor Intrusion.

    Science.gov (United States)

    Shen, Rui; Pennell, Kelly G; Suuberg, Eric M

    2013-10-01

    Mathematical models have been widely used in analyzing the effects of various environmental factors in the vapor intrusion process. Soil moisture content is one of the key factors determining the subsurface vapor concentration profile. This manuscript considers the effects of soil moisture profiles on the soil gas vapor concentration away from any surface capping by buildings or pavement. The "open field" soil gas vapor concentration profile is observed to be sensitive to the soil moisture distribution. The van Genuchten relations can be used for describing the soil moisture retention curve, and give results consistent with the results from a previous experimental study. Other modeling methods that account for soil moisture are evaluated. These modeling results are also compared with the measured subsurface concentration profiles in the U.S. EPA vapor intrusion database.

  10. Influences of space, soil, nematodes and plants on microbial community composition of chalk grassland soils

    NARCIS (Netherlands)

    Yergeau, E.; Bezemer, T.M.; Hedlund, K.; Mortimer, S.R.; Kowalchuk, G.A.; Putten, van der W.H.

    2010-01-01

    Microbial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial community composit

  11. Physiological factors influencing capillary growth.

    Science.gov (United States)

    Egginton, S

    2011-07-01

    (1) Angiogenesis (growth of new capillaries from an existing capillary bed) may result from a mismatch in microvascular supply and metabolic demand (metabolic error signal). Krogh examined the distribution and number of capillaries to explore the correlation between O(2) delivery and O(2) consumption. Subsequently, the heterogeneity in angiogenic response within a muscle has been shown to reflect either differences in fibre type composition or mechanical load. However, local control leads to targetted angiogenesis in the vicinity of glycolytic fibre types following muscle stimulation, or oxidative fibres following endurance training, while heterogeneity of capillary spacing is maintained during ontogenetic growth. (2) Despite limited microscopy resolution and lack of specific markers, Krogh's interest in the structure of the capillary wall paved the way for understanding the mechanisms of capillary growth. Angiogenesis may be influenced by the response of perivascular or stromal cells (fibroblasts, macrophages and pericytes) to altered activity, likely acting as a source for chemical signals modulating capillary growth such as vascular endothelial growth factor. In addition, haemodynamic factors such as shear stress and muscle stretch play a significant role in adaptive remodelling of the microcirculation. (3) Most indices of capillarity are highly dependent on fibre size, resulting in possible bias because of scaling. To examine the consequences of capillary distribution, it is therefore helpful to quantify the area of tissue supplied by individual capillaries. This allows the spatial limitations inherent in most models of tissue oxygenation to be overcome generating an alternative approach to Krogh's tissue cylinder, the capillary domain, to improve descriptions of intracellular oxygen diffusion. © 2010 The Author. Acta Physiologica © 2010 Scandinavian Physiological Society.

  12. THE INFLUENCE OF FERTILIZERS, NaHCO3,SOIL TYPE ON CHEMISTRY OF FLOODED SOILS AND RICE PLANT GROWTH

    Institute of Scientific and Technical Information of China (English)

    Ir.Lahuddin M S; Zulkifli Nasution

    2006-01-01

    This research was conducted to study the influence of NaHCO3 and fertilizer treatments on flooded soils to the chemistry of soil and rice plant growth.The experiment was done in a greenhouse using a split-split plot design of three factors: two types of soil, three doses of fertilizers and three levels of NaHCO3 with three replications.The first factor was two kind of soils Fluvaquent and Calciquert, the factor was without nutrient (blank), macro nutrients, and completely nutrients (second macro and micro nutrients), and the third factor was 0 mg/kg, 200 mg/kg and 400 mg/kg of NaHCO3 or equivalent with 0 mg, 1 200 mg and 2 400 mg NaHCO3 per pot.Each experimental unit used a pot of 10 L capacity and filled with soil mud equivalent with 6 kg of dried soil.After each of treatment combination mixed into the mud soil, two plants of IR-32 variety were grown, and flooded at 5 cm high accordingly with growth period.Parameters observed were the growth of tillers, electrical conductivity (E.C.) and pH.The experiment results showed that the treatment of NaHCO3 increased the soluble salt content (E.C.) and soil acidity (pH) during flooding on Calciquerts and Fluvaquents.The content of soluble salt decreased to 2.0 mmhos/cm, while pH on Calciquert decreased towards the neutral pH.Anyhow the pH on Fluvaquents increased approach to neutral.The treatments of NaHCO3 inhibited the tiller growth, either macro fertilizer and completely fertilizer increased the tillers, but did not improve the negative effect of alkalinity due to of NaHCO3 treatment.

  13. Influence of Exogenous Lanthanum on Fertility Parameters of Red Soil and Paddy Soil

    Institute of Scientific and Technical Information of China (English)

    谢祖彬; 朱建国; 褚海燕; 曾青; 张雅丽; 曹志洪

    2001-01-01

    The effects of exogenous La on the fertility parameters such as cation exchange capacity (CEC), exchangeable basic cations, and exchangeable acidity in red soil and paddy soil were studied with soil column simulation. The results show that with increasing amount of the added La, the proportion of exchangeable La in soils increases and there is more exchangeable La in red soil than in paddy soil. When the concentration of La is more than 600 mg*kg-1, the proportion of exchangeable La almost remains constant. When the concentration of La is less than 1200 mg*kg-1, there is no significant effect on CEC in red soil. But when the concentration of La is more than 1200 mg*kg-1, it has significant effect on CEC in paddy soil. The application of La resulted in increasing exchangeable aluminum, Ca and Mg in soil solution, and decreasing exchangeable Ca and Mg retained in soils. But when the concentration of La is less than 150 mg*kg-1, it has no significant influence on CEC, exchangeable Ca and Mg, and exchangeable acidity in red soil and paddy soil.

  14. Effect of the edaphic factors and metal content in soil on the diversity of Trichoderma spp.

    Science.gov (United States)

    Racić, Gordana; Körmöczi, Péter; Kredics, László; Raičević, Vera; Mutavdžić, Beba; Vrvić, Miroslav M; Panković, Dejana

    2017-02-01

    Influence of edaphic factors and metal content on diversity of Trichoderma species at 14 different soil sampling locations, on two depths, was examined. Forty-one Trichoderma isolates from 14 sampling sites were determined as nine species based on their internal transcribed spacer (ITS) sequences. Our results indicate that weakly alkaline soils are rich sources of Trichoderma strains. Also, higher contents of available K and P are connected with higher Trichoderma diversity. Increased metal content in soil was not inhibiting factor for Trichoderma species occurrence. Relationship between these factors was confirmed by locally weighted sequential smoothing (LOESS) nonparametric smoothing analysis. Trichoderma strain (Szeged Microbiology Collection (SZMC) 22669) from soil with concentrations of Cr and Ni above remediation values should be tested for its potential for bioremediation of these metals in polluted soils.

  15. Influence of biochar on the enantioselective behavior of the chiral fungicide metalaxyl in soil

    Science.gov (United States)

    Gámiz, Beatriz; Pignatello, Joseph J.; Hermosín, María Carmen; Cox, Lucía; Celis, Rafael

    2015-04-01

    Chiral pesticides comprise an emerging and important class of organic pollutants currently, accounting for more than a quarter of used pesticides. Consequently, the contamination problems caused by chiral pesticides are concern matter and factors affecting enantioselective processes of chiral pesticides in soil need to be understood. For example, certain soil management practices, such as the use of organic amendments, can affect the enantioselective behavior of chiral pesticides in soils. Recently, biochar (BC), i.e. organic matter subjected to pyrolysis, has been proposed as organic amendment due to beneficial properties such as its high stability against decay in soil environments and its apparent ability to influence the availability of nutrients. BC is considered to be more biologically inert as compared to otherforms of organic carbon. However, its side-effects on the enantioselectivity of processes affecting the fate of chiral pesticides is unknown. The aim of this study was to assess the effect of biochar (BC) on the enantioselectivity of sorption, degradation, and leaching of the chiral fungicide metalaxyl in an agricultural soil. Amending the soil with BC (2% w/w) resulted in 3 times higher sorption of metalaxyl enantiomers compared to unamended soil, but no enantioselectivity in the process was observed. Moreover, both enantiomers showed some resistance to be desorbed in BC-amended soil compared to unamended soil. Dissipation studies revealed that the degradation of metalaxylwas more enantioselective in the unamended soil than in BC-amended soil. In unamended soil, R-metalaxyl(biologically active) and S- metalaxyl had half-lives (t1/2) of 3 and 34 days, respectively. BC enhanced the persistence of both enantiomers in the soil, with R-metalaxyl being degraded faster (t1/2=43 days) than S-metalaxyl (t1/2= 100 days). The leaching of both S-and R-metalaxyl was almost suppressed after amending the soil with BC; less than 10% of the fungicide applied to soil

  16. Influence of disturbance on soil respiration in biologically crusted soil during the dry season.

    Science.gov (United States)

    Feng, Wei; Zhang, Yu-qing; Wu, Bin; Zha, Tian-shan; Jia, Xin; Qin, Shu-gao; Shao, Chen-xi; Liu, Jia-bin; Lai, Zong-rui; Fa, Ke-yu

    2013-01-01

    Soil respiration (Rs) is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs) are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss), as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60-70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q 10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  17. Influence of Disturbance on Soil Respiration in Biologically Crusted Soil during the Dry Season

    Directory of Open Access Journals (Sweden)

    Wei Feng

    2013-01-01

    Full Text Available Soil respiration (Rs is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss, as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  18. Dissolved organic carbon (DOC) concentrations in UK soils and the influence of soil, vegetation type and seasonality.

    Science.gov (United States)

    van den Berg, Leon J L; Shotbolt, Laura; Ashmore, Mike R

    2012-06-15

    Given the lack of studies which measured dissolved organic carbon (DOC) over long periods, especially in non-forest habitat, the aim of this study was to expand the existing datasets with data of mainly non-forest sites that were representative of the major soil and habitat types in the UK. A further aim was to predict DOC concentrations from a number of biotic and abiotic explanatory variables such as rainfall, temperature, vegetation type and soil type in a multivariate way. Pore water was sampled using Rhizon or Prenart samplers at two to three week intervals for 1 year. DOC, pH, organic carbon, carbon/nitrogen (C:N) ratios of soils and slope were measured and data on vegetation, soil type, temperature and precipitation were obtained. The majority of the variation in DOC concentrations between the UK sites could be explained by simple empirical models that included annual precipitation, and soil C:N ratio with precipitation being negatively related to DOC concentrations and C:N ratio being positively related to DOC concentrations. Our study adds significantly to the data reporting DOC concentrations in soils, especially in grasslands, heathlands and moorlands. Broad climatic and site factors have been identified as key factors influencing DOC concentrations.

  19. 区域绿洲农田土壤有机碳分布及其影响因子研究%Distribution of Soil Organic Carbon and the Influencing Factors in An Oasis Farmland Area

    Institute of Scientific and Technical Information of China (English)

    王泽; 颜安; 张文太

    2014-01-01

    以干旱区典型绿洲农田区---玛纳斯县中部农田为研究区,以土壤有机碳为研究对象,结合野外土壤调查及实验室分析数据研究了土壤有机碳的垂直分布特征,并分析土壤质地、地形、土地利用、作物类型等不同因子对农田土壤有机碳的影响。结果表明:玛纳斯县中部农田土壤有机碳是自然环境综合因素的结果,土壤有机碳含量随着土壤深度的增加不断减小;不同土壤质地土壤有机碳含量的特征为:粘壤土跃粉壤土跃沙壤土;不同地形因子中坡向与农田0~30、30~60 cm层的土壤有机碳含量呈显著正相关,海拔与农田60~100 cm层的土壤有机碳含量呈显著正相关;不同土地利用方式下土壤有机碳含量有较大差异,果园的土壤有机碳含量最高,荒地的土壤有机碳含量最低;不同作物类型土壤有机碳含量特征为:玉米地跃酒葡萄地跃棉花地,且差异显著。%The soil organic carbon(SOC)of a typical oasis farmland in middle part of Manasi county of Xinjiang was used as the research ob-ject. Using remote sensing and lab analysis techniques, influences of soil texture, terrain, land uses, and crop types on SOC content of farm-land were studied. Results showed that the SOC distribution in farmland of Manasi was mainly determined by comprehensive natural environ-mental factors. The SOC content decreased along with the increasing soil depth. For soil textures, the SOC content from high to low was clay loam>powder loam>silty loam. Slope direction had significantly positive correlations with SOC contents at 0~30 cm and 30~60 cm, while alti-tude and SOC content at 60~100 cm were significantly positive correlation. The SOC content of orchard was the highest, and the uncultivated land was the lowest under different land-use patterns. For different crop planting systems, the order of SOC content was corn field>wine grapes field>cotton field, and the difference

  20. Investigating the Influence of Environmental Factors on Pesticide Exposure in Amphibians

    Science.gov (United States)

    Environmental factors such as temporal weather patterns and soil characterization coupled with pesticide application rates are known to influence exposure and subsequent absorption of these compounds in amphibians. Amphibians are a unique class of vertebrates due to their varied ...

  1. INFLUENCE OF XENOBIOTICS ON THE BIOLOGICAL SOIL ACTIVITY

    Directory of Open Access Journals (Sweden)

    S JAVOREKOVÁ

    2002-05-01

    Full Text Available The both basic and potential biological soil activity along with a biological degradation capacity of soil microorganisms through their respiratory activity were investigated after the application of polymers with the different degree of degradation in the soil. The CO2 production was measured by the absorption method at standard moisture and temperature under laboratory conditions. Numerous representing changes of major soil microbial groups were determined after the application of the polyethylene. Polyethylene (PE, polyvinylalcohol (PVA, polyvinylalcohol modified by hydrolysed collagen (PVAHC were applied as synthetic polymers into luvisol. The addition of all tested polymers significantly influenced the CO2 production. During 43 days of incubation period, the total amount of produced CO2 was 1271.6 mg.kg-1. The total amount of mineralised carbon in the soil reached 4.55 %. When compared with the soil, the respiratory activity of soil microorganisms increased 3-times, 1.2-times and 1.3-times after addition of starch, PVA and PVAHC, respectively. The addition of granular PE reduced the soil pores size, which resulted in a significant decrease of CO2 production and non-significant rearrangement of the major microbial groups in the soil after three month of incubation.

  2. Hydrolysis kinetics of atrazine and influence factors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The hydrolysis kinetics of atrazine in distilled water and leaching water from soil, and their influence factors were studied by incubation at 35℃ and HPLC analysis method in this paper. The kinetic process of atrazine hydrolysis can be described by the first-order reaction law. The results showed that the hydrolysis rate constants k in leaching water and distilled water were 1.606x10-3/d and 1.055x10-3/d, respectively; the half-life of atrazine hydrolysis in distilled water at pH 3, pH 4.5 and pH 8 were 373 days, 522 days and 657 days respectively. The results also showed that the proton in reaction solution can catalyze the atrazine hydrolysis; humic acid and NH4+ etc. substances in aqueous solution can facilitate atrazine hydrolysis; rate constants of atrazine hydrolysis with humic acid and NH4NO3 were 2.431x10-3/d and 1.498x10-3/d respectively which were 2.3 and 1.42 times of control(1.055x10-3/d); anion NO3- can inhibit catalysis of humic acid to atrazine hydrolysis.

  3. Influence of low- and high-frequency electrical heating on biodegrading microorganisms in soil: soil respiration.

    Science.gov (United States)

    Roland, Ulf; Holzer, Frank; Kopinke, Frank-Dieter

    2013-01-01

    The influence of electrical heating on microbiological processes in soil has been studied to evaluate the potential for enhancing biodegradation of pollutants by controlling the temperature. A frequency of 50 Hz (power line frequency) was applied for resistive heating. Dielectric heating was realized using a frequency of 13.56 MHz (radio frequency). Both techniques were compared with conventional heating in a water bath. For experiments in laboratory and full scale, a model soil and a contaminated original soil were used. It was shown that under conditions capable for heating soil to 35 degrees C or even 60 degrees C, soil respiration as a measure for microbial activity was not hindered by electrical heating when temperature and moisture content were comparable with conventional heating. The variations of soil respiration were reversible upon temperature changes. Under certain conditions, periodical fluctuations of microbiological activity were observed. Several possible explanations including chronobiology are discussed without being able to provide an unambiguous interpretation for this effect.

  4. Demotivating factors influencing rubber production workers

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Iravani

    2012-01-01

    Full Text Available Motivation is one of the most important factors influencing workers' productivity. An increase in workers' motivation could add more value to organizations' structure and influence the profitability, significantly. In this paper, we study different factors on demotivating workers using questionnaire consist of various questions. The questionnaire is distributed among some employees who work for rubber production units located in Esfahan, Iran. The results of this survey indicate that discrimination on annual job compensation, entrusting responsibilities and unpleasant relationship with family partner are some of the most important factors influencing employees' motivation. While financial factors play important role on increasing employees' motivation, non-financial factors are considered more important.

  5. Soil Chemistry Factors Confounding Crop Salinity Tolerance—A Review

    Directory of Open Access Journals (Sweden)

    Pichu Rengasamy

    2016-10-01

    Full Text Available The yield response of various crops to salinity under field conditions is affected by soil processes and environmental conditions. The composition of dissolved ions depend on soil chemical processes such as cation or anion exchange, oxidation-reduction reactions, ion adsorption, chemical speciation, complex formation, mineral weathering, solubility, and precipitation. The nature of cations and anions determine soil pH, which in turn affects crop growth. While the ionic composition of soil solution determine the osmotic and ion specific effects on crops, the exchangeable ions indirectly affect the crop growth by influencing soil strength, water and air movement, waterlogging, and soil crusting. This review mainly focuses on the soil chemistry processes that frustrate crop salinity tolerance which partly explain the poor results under field conditions of salt tolerant genotypes selected in the laboratory.

  6. Influence of soil and climate on root zone storage capacity

    Science.gov (United States)

    de Boer-Euser, Tanja; McMillan, Hilary; Hrachowitz, Markus; Winsemius, Hessel; Savenije, Hubert

    2016-04-01

    The catchment representative root zone storage capacity (Sr), i.e. the plant available soil water, is an important parameter of hydrological systems. It does not only influence the runoff from catchments, by controlling the partitioning of water fluxes but it also influences the local climate, by providing the source for transpiration. Sr is difficult to observe at catchment scale, due to heterogeneities in vegetation and soils. Sr estimates are traditionally derived from soil characteristics and estimates of root depths. In contrast, a recently suggested method allows the determination of Sr based on climate data, i.e. precipitation and evaporation, alone (Gao et al., 2014). By doing so, the time-variable size of Sr, is explicitly accounted for, which is not the case for traditional soil based methods. The time-variable size of Sr reflects root growth and thus the vegetation's adaption to medium-term fluctuations in the climate. Thus, we tested and compared Sr estimates from this 'climate based method' with estimates from soil data for 32 catchments in New Zealand. The results show a larger range in climate derived Sr than in soil derived Sr. Using a model experiment, we show that a model using the climate derived Sr is more accurately able to reproduce a set of hydrological regime signatures, in particular for humid catchments. For more arid catchments, the two methods provide similar model results. This implies that, although soil database information has some predictive power for model soil storage capacity, climate has a similar or greater control on Sr, as climate affects the evolving hydrological functioning of the root zone at the time scale of hydrological interest. In addition, Sr represents the plant available water and thus root surface, volume and density, and is therefore a more complete descriptor of vegetation influence on water fluxes than mere root depth. On balance, the results indicate that climate has a higher explanatory power than soils for

  7. Spatial Variation of Deep Soil Water in the Loess Hilly and Gully Regions and Its Influencing Factors%黄土丘陵沟壑区深层土壤水分空间变异及其影响因子

    Institute of Scientific and Technical Information of China (English)

    杨磊; 卫伟; 陈利顶; 贾福岩; 王子婷

    2012-01-01

    以甘肃省定西市龙滩流域为例,对比分析了不同坡位、坡度和坡向典型植被(柠条林地、油松林地、侧柏林地、苜蓿草地、荒草地和农地)O~8m深度土壤水分的空间变异状况.结果表明,不同植被和地形条件下,深层土壤水分的剖面分布特征均表现为随土层深度增加而增加.地形是浅层土壤水分空间变异的重要影响因子,而植被生长状况是深层土壤水分空间变异的决定因素,植被生长越好则深层土壤含水量越低.坡度对深层土壤水分有显著影响,缓坡地土壤含水量显著高于陡坡地.水土保持工程和耕作管理措施能有效提高深层土壤含水量,可作为提高土壤储水的有效途径.%Spatial variation of soil water content in soil profiles 0-8 m deep as affected by landform and vegetation was studied in the Longtan catchment of Dingxi in Gansu Province. Results show that topographic factors, such as position, inclination and exposure of a slope have significant influences on content of shallow soil water. However, spatial variation of deep soil water is more affected by growth conditions of the vegetation thereupon. The vegetations different in growth condition differ in consumption of soil water, thus the better the vegetation grows, the lower the content of deep soil water is. Slope gradient has significant influences on both shallow and deep soil waters. Soil water content is obviously higher in gentle slopes than in steep slopes in the entire 0 - 8 m soil profile. Management measures such as soil and water conservation and tillage activities can effectively enhance infiltration of rain water, thus increasing soil water storage in deep soil layers, and therefore be extrapolated as effective approaches to improvement of soil water regime in this region.

  8. Influence of grazing exclosure on vegetation biomass and soil quality

    OpenAIRE

    Shagufta Qasim; Shamim Gul; Maria Hussain Shah; Fayyaz Hussain; Sarfraz Ahmad; Muhammad Islam; Gulbano Rehman; Muhammad Yaqoob; Syed Qasim Shah

    2017-01-01

    This study investigated the influence of sixteen years exclosure from unmanaged grazing on aboveground vegetation biomass, soil organic matter (SOM), soil aggregation and nitrogen (N) mineralization in arid shrubland of Baluchistan, Pakistan. Sampling was carried out from three sites along the chronosequence of secondary succession. One site was located at open-for-grazing area (grazed site) and the other two sites were located in the area that is protected since 1998. One of the protected si...

  9. Influence of land use on soil organic matter

    Science.gov (United States)

    Rogeon, H.; Lemée, L.; Chabbi, A.; Ambles, A.

    2009-04-01

    Soil organic matter (SOM) is actually of great environmental interest as the amount of organic matter stored in soils represents one of the largest reservoirs of organic carbon on the global scale [1]. Indeed, soil carbon storage capacity represents 1500 to 2000 Gt for the first meter depth, which is twice the concentration of atmospheric CO2 [2]. Furthermore, human activities, such as deforestation (which represents a flux of 1.3 Gt C/year), contribute to the increase in atmospheric CO2 concentration for about one percent a year [3]. Therefore, carbon dioxide sequestration in plant and carbon storage in soil and biomass could be considered as a complementary solution against climate change. The stock of carbon in soils is greatly influenced by land use (ca 70 Gt for a forest soil or a grassland against 40 Gt for an arable land). Furthermore the molecular composition of SOM should be also influenced by vegetation. In this context, four horizons taken between 0-120 cm from the same profile of a soil under grassland and forest located in the vicinity of Poitiers (INRA Lusignan, ORE Prairie) were compared. For the surface horizon, the study is improved with the results from the cultivated soil from INRA Versailles. Soil organic matter was characterized using IR spectroscopy, elemental analysis and thermal analysis. Granulometric fractionation into sand (50-2000 μm), silt (2-50 μm) and clay (Change, pp 9-26 [2] Lal, R., et al., (2004), Soil carbon sequestration to mitigate climate change, Geoderma 123, 1-22. [3] IPCC, 2001. Summary for policymakers. In: Watson, R., (Ed.), Climate Change 2001: The Scientific Basis. Cambridge University Press, Cambridge, 1-20.

  10. 微波热修复石油污染土壤的影响因素研究%Influence Factors of Microwave Thermal Remediation on Soil Contaminated with Crude Oil

    Institute of Scientific and Technical Information of China (English)

    韩妮; 朱新萍; 杨春; 贾宏涛; 姚红宇

    2014-01-01

    Taking gray desert soil as the tested soil,firstly the simulation experiment was conducted in the laboratory,microwave thermal remediation technology was used to rapidly remedy soil containated with crude oil,then biochar and microwave technology were connected in order to remedy soil contaminated with crude oil.Based on the single-factor test,the Box-Behnken experiment design and response surface method were used to resarch the effects of microwave irradiation time,soil moisture contednt on microwave ther-mal remediation of soil contaminated with crude oil.The result revealed that when microwave power was 800 W,microwave irradiation time was 10 min,soil moisture content was 10.3%,biochar content was 6.9%,then petrolwum hydrocarbon degradation in soil reached 95.76%.Moreover,the results showed that the soil moisture content and biochar content had significant interactions in soil contaminated with crude oil.%利用微波热修复技术快速修复原油污染的土壤.通过室内模拟试验,以灰漠土为供试土壤,将添加生物黑炭介质与微波技术相结合,达到修复土壤中石油污染的目的.在单因素试验基础上,采用 Box-Behnken 实验设计和响应曲面法,以生物黑炭作为外源吸波介质,对微波辐射时间、土壤含水率等因素对石油污染土壤微波热修复效果的影响进行研究.研究结果表明,微波功率为800 W,微波辐射时间10 min,土壤含水率10.3%,生物黑炭添加量6.9%,为石油浓度20 g/kg 时土壤最佳修复条件,此时土壤中石油烃降解率达到95.76%.此外研究结果显示,土壤含水率与土壤中生物黑炭的含量在微波热修复石油污染土壤中存在显著的交互作用.

  11. Fatores relacionados à suscetibilidade da erosão em entressulcos sob condições de uso e manejo do solo Factors influencing susceptibility to interrill soil erosion under different land use and management conditions

    Directory of Open Access Journals (Sweden)

    Flávio P. de Oliveira

    2012-04-01

    Full Text Available Neste trabalho foram avaliados fatores relacionados com a suscetibilidade a erosão em entressulcos de um Neossolo Litólico submetido a diferentes intensidades de uso e manejo do solo. O experimento foi realizado em condições de laboratório, utilizando-se amostras deformadas de solo colocadas em parcelas experimentais (0,23 m2 e declividade de 0,09 m m-1. O delineamento experimental utilizado foi em blocos casualizados, em que foram aplicadas chuvas simuladas com intensidade de 100 mm h-1 para os seguintes tratamentos: (I solo cultivado com fumo sob preparo convencional (PC; (II solo cultivado com fumo sob plantio direto (PD e (III solo sob mata nativa (MN. Para avaliar a suscetibilidade a erosão em entressulcos utilizaram-se índices referentes à relação energia cinética total (chuva e escoamento sobre perda de solo, taxa média de desagregação e índice de estabilidade de agregados, cujos resultados mostraram que os fatores relacionados com a suscetibilidade a erosão em entressulcos estão associados não apenas com características e propriedades que conferem coesividade ao solo, mas, também, com condicionantes que afetam a hidráulica do escoamento e, consequentemente, a fase de transporte dos sedimentos.This study evaluated factors related to the suscetibility to the interrill soil erosion in an Entisol subjected to different degrees of soil use and management. The experiment was carried out under laboratory conditions using samples collected from tobacco fields and disturbed soil placed in erosion pans measuring (0.23 m2 with a slope of 0.09 m m-1. The experimental design was in randomized blocks. Simulated rainfall intensity of 100 mm h-1 was applied to the following treatments: (I conventionally tilled soil; (II no-till soil; and (III native forest soil. Total kinetic energy (rainfall and runoff to soil loss, average rate of detachment, and aggregate stability indexes were used to assess susceptibility to interrill erosion

  12. Socio-Economic Factors Assessment Affecting the Adoption of Soil Conservation Technologies on Rwenzori Mountain

    Directory of Open Access Journals (Sweden)

    Nabalegwa Wambede Muhamud

    2015-06-01

    Full Text Available This study analysed the role of socio-economic factors in influencing farmers’ adoption to soil conservation technologies in Bugoye Sub-county, Rwenzori Mountain. A cross sectional household survey design was used in this study, using systematic sampling to obtain 150 household samples. Qualitative analysis and chi-square tests were used to analyze these data. Results indicated that only 54% of the sampled households have adopted soil conservation, and revealed that eight of the nine factors significantly influenced farmers’ adoption, which are slope, farm size, farm distance from home, education level, family income, training, membership to NGOs, and credit accessibility. Only family size was insignificant. Other constraints are labour demands, cost of conservation work, land fragmentation, crop pests, and the limited agricultural extension services. It is recommended to perform training for farmers on designing soil conservation structures. Policies for empowering farmers with extra income are crucial to increase the adoption of soil conservation efforts.

  13. Influences of Soil Parameters on Bifurcation Analysis of Normally Consolidated Cohesive Soil under Plane Strain Undrained Compression Loading

    OpenAIRE

    2000-01-01

    This paper describes the influences of soil parameters on bifurcation analysis,using a non-coaxial Camclay model of normally consolidated cohesive soils during undrained shear under plane strain condition. The soil parameters are estmated from plasticity index. The soils exhibited a wide range in plasticity index,from lO−50. The results indicate that bifurcation behavior using a soil with lower plasticity index occurs at a larger stress ratio and a smaller strain compared to soils with ...

  14. The predictable influence of soil temperature and barometric pressure changes on vapor intrusion

    Science.gov (United States)

    Barnes, David L.; McRae, Mary F.

    2017-02-01

    Intrusion of volatile organic compounds in the gas phase has impacted many buildings in many different locations. Various building and environmental factors such as buoyancy of heated air and changes in barometric pressure can influence indoor air concentrations due to vapor intrusion in these buildings resulting in seasonal and daily variability. One environmental factor that previous research has not adequately addressed is soil temperature. In this study we present two northern region study sites where the seasonal trends in indoor air VOC concentrations positively correlate with soil temperature, and short-term (days) variations are associated with barometric pressure changes. We present simple and multivariate linear relationships of indoor air concentrations as a function of soil temperature and barometric pressure. Results from this study show that small changes in soil temperature can result in relatively large changes in indoor air VOC concentrations where the gas phase VOCs are sourced from non-aqueous phase liquids contained in the soil. We use the results from this study to show that a five degree Celsius increase in soil temperature, a variation in soil temperature that is possible in many climatic regions, results in a two-fold increase in indoor air VOC concentrations. Additionally, analysis provides insight into how building ventilation, diffusion, and the relative rate of soil-gas flow across the slab both from the subsurface into the building and from the building into the subsurface impact short term variations in concentrations. With these results we are able to provide monitoring recommendations for practitioners.

  15. 固定化MM-7修复石油污染土壤影响因素重要性%Importance of the influence factors on the bioremediation of oil-contaminated soil by immobilized MM-7

    Institute of Scientific and Technical Information of China (English)

    张秀霞; 刘永博; 徐娜娜; 白雪晶; 孔甜甜; 李进辉; 张腾

    2012-01-01

    针对石油污染土壤修复,利用实验室已筛选的高效石油降解混合菌MM-7,以天然有机材料YJ-05为载体,吸附法制备固定化微生物。并将游离与固定化微生物应用于室内花盆模拟修复石油污染土壤,对C/N/P、微生物投加量、石油含量、氧化剂和表面活性剂设计五因素四水平正交实验,探讨不同修复时期各影响因素的重要性顺序。实验结果表明,不同微生物在不同降解时期,各影响因素的重要性会发生变化;经过21 d的修复,固定化MM-7对石油烃类的降解率为27.12%,修复过程中,接种量一直是最重要的影响因素,在降解初期表面活性剂影响较大,降解中后期土壤石油含量变为重要影响因子。%MM-7,a group of mixed bacteria selected from effective bacterium strains under the laboratory condition was employed to produce immobilized microorganism with YJ-05,a natural organic carrier in adsorption.Then the immobilized microorganism and free bacteria were used to simulate the remediation of oil contaminated soil to investigate the order of importance of 5 factors in different restoring stages with the method of orthogonality,in which the ratio of C,N,P,the amount of bacteria added,the amount of oil,oxidant and surfactant were considered.The results indicated that the order of importance of factors changed in different degradation stages and different kinds of microorganisms.21-day experiment showed that the rate of petroleum hydrocarbon degradation retains 27.12%,the amount of bacteria was the most important factor,the amount of surfactant followed in the early stage,and the amount of oil also influenced a lot in the middle and last stage.

  16. Impact of topography and soil factors on crop suitability in two Mediterranean areas (Egypt and Spain)

    Science.gov (United States)

    Abd-Elmabod, S. K.; Jordán, A.; Anaya-Romero, M.; Ali, R. R.; Muñoz-Rojas, M.; Zavala, L. M.; de la Rosa, D.

    2012-04-01

    The aim of this research is to study the influence of topography and soil factors on crop suitability two Mediterranean areas: Sevilla (southern Spain) and El-Fayoum (northern Egypt). The Shuttle Radar Topography Mission (SRTM) images were processed using ENVI 4.7 software to extract elevation data, slope gradient and slope direction. North-south toposequences from both areas were extracted and studied using Arc-GIS 9.3 software. Soil characteristics along these toposequences were extracted from regional soil maps, as well as land surveying and laboratory analyses. The Almagra model (included in the agro-ecological system MicroLEIS DSS) was used to evaluate agricultural soil suitability using soil factors of useful depth, texture, drainage, carbonate content, salinity, sodium saturation, and degree of development of the profile. Changes of soil characteristics through the toposequences are discussed. The results of Almagra model indicate that the crop suitability main limiting factors are soil texture, drainage, soil salinity and sodium saturation percent and topography factors elevation, slope gradient, slope direction.

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

    Science.gov (United States)

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

    2016-03-01

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

  18. Influence of soil properties on the bioaccumulation and effects of arsenic in the earthworm Eisenia andrei.

    Science.gov (United States)

    Romero-Freire, A; Peinado, F J Martín; Ortiz, M Díez; van Gestel, C A M

    2015-10-01

    This study aimed at assessing the influence of soil properties on the uptake and toxicity effects of arsenic in the earthworm Eisenia andrei exposed for 4 weeks to seven natural soils spiked with different arsenic concentrations. Water-soluble soil concentrations (AsW) and internal As concentrations in the earthworms (AsE) were greatly different between soils. These two variables were highly correlated and were key factors in earthworm toxicity response. AsW was explained by some soil properties, such as the pH, calcium carbonate content, ionic strength, texture or oxide forms. Toxicity showed a clear variation between soils, in some cases without achieving 50 % adverse effect at the highest As concentration added (600 mg kg(-1)). Nevertheless, soil properties did not show, in general, a high relation with studied toxicity endpoints, although the high correlation with AsW could greatly reduce indirectly As bioavailability and toxicity risk for earthworms. Obtained results suggest that soil properties should be part of the criteria to establishing thresholds for contaminated soils because they will be key in controlling As availability and thus result in different degrees of toxicity.

  19. Influence of Land Cover and Climate on CO2 and CH4 fluxes from Urban Soils

    Science.gov (United States)

    Smith, R. M.; Groffman, P. M.; Kaushal, S.; Gold, A.; Cole, J. N.

    2015-12-01

    Soils are important sinks for greenhouse gases globally. Urbanization influences biogeochemical processes and gas fluxes through increased nitrogen deposition, heat island effects, and vegetation management. Previous work at the Baltimore Ecosystem Study LTER site has reported elevated CO2 fluxes and reduced CH4 consumption in urban soils. Differences among soils (urban forest, rural forest, lawns) have been linked to nitrogen cycling and may also be driven by temperature differences between land cover types. A combination of site-specific changes (land cover, nitrogen availability) and climatological (temperature, soil moisture) factors are likely to influence long-term patterns in gas fluxes and therefore carbon storage in growing urban regions. We utilized 15 years of measured gas fluxes and continuous temperature and soil moisture data to model CO2 emissions and CH4 consumption under different vegetation classes. We scaled these fluxes to the metropolitan region using high-resolution spatial, and found that regional CH4 consumption and CO2 fluxes are sensitive to changes in temperature and land cover. For instance, in 2007 land cover in Baltimore City had 21% lawn and 22% forest cover. If all of the lawn area in the city were converted to urban forest, CH4 consumption by urban soils would increase by 70% and CO2 emissions would decrease by 20%. In suburban Baltimore County, lawns and urban forests comprised 35 and 50% of land cover respectively. If all lawns in the county were converted to urban forest, soil CH4 consumption would increase by 55% and soil CO2 flux would decrease by 20%. Soil CO2 fluxes also increase by approximately 0.1g C m-2 d-1 for every 1° C increase across all land cover classes. CH4 consumption increases with temperature in urban and rural forest soils. Our results highlight the interacting effects of land cover change and climate on carbon fluxes from urban soils.

  20. Introducing soil forming factors with mini campus field trips

    Science.gov (United States)

    Quinton, John; Haygarth, Phil

    2013-04-01

    Students like field work, yet the proportion of time spent in the field during many soil science courses is small. Here we describe an introductory lecture on the soil forming factors based around a mini field trip in which we spend 45 minutes exploring these factors on the Lancaster University campus. In the 'trip' we visit some woodland to consider the effects of organic matter , vegetation and time on soil development and then take in a football pitch to examine the effects of landscape position, parent material and climate. Student responses are overwhelmingly positive and we suggest that more use can be made of our often mundane surroundings to explore soil formation. Soil functions and soil processes.

  1. Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station

    Science.gov (United States)

    Sugathan, Neena; Biju, V.; Renuka, G.

    2014-06-01

    Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76°59'E longitude and 8°29'N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed.

  2. Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station

    Indian Academy of Sciences (India)

    Neena Sugathan; V Biju; G Renuka

    2014-07-01

    Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76° 59’E longitude and 8°29’N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed.

  3. Estimate Soil Erodibility Factors Distribution for Maioli Block

    Science.gov (United States)

    Lee, Wen-Ying

    2014-05-01

    The natural conditions in Taiwan are poor. Because of the steep slopes, rushing river and fragile geology, soil erosion turn into a serious problem. Not only undermine the sloping landscape, but also created sediment disaster like that reservoir sedimentation, river obstruction…etc. Therefore, predict and control the amount of soil erosion has become an important research topic. Soil erodibility factor (K) is a quantitative index of distinguish the ability of soil to resist the erosion separation and handling. Taiwan soil erodibility factors have been calculated 280 soil samples' erodibility factors by Wann and Huang (1989) use the Wischmeier and Smith nomorgraph. 221 samples were collected at the Maioli block in Miaoli. The coordinates of every sample point and the land use situations were recorded. The physical properties were analyzed for each sample. Three estimation methods, consist of Kriging, Inverse Distance Weighted (IDW) and Spline, were applied to estimate soil erodibility factors distribution for Maioli block by using 181 points data, and the remaining 40 points for the validation. Then, the SPSS regression analysis was used to comparison of the accuracy of the training data and validation data by three different methods. Then, the best method can be determined. In the future, we can used this method to predict the soil erodibility factors in other areas.

  4. Influence of soil structure on nutrient cycling using microfluidic techniques

    Science.gov (United States)

    Arellano Caicedo, Carlos; Aleklett, Kristin; Ohlsson, Pelle; Hammer, Edith

    2017-04-01

    The rising of atmospheric CO2 levels and its effects on global warming make it necessary to understand the elements that regulate such levels and furthermore try to slow down the CO2 accumulation in the atmosphere. The exchange of carbon between soil and atmosphere plays a significant role in the atmospheric carbon budget. Soil organisms deposit organic compounds on and in soil aggregates, either as exudates or dead remains. Much of this dead organic material is quickly recycled, but a portion, however, will stay in the soil for long term. Evidence suggests that micro-scale biogeochemical interactions could play a highly significant role in degradation or persistence of organic matter in soils, thus, soil physical structure might play a decisive role in preventing accessibility of nutrients to microorganisms. For studying effects of spatial microstructure on soil nutrient cycles, we have constructed artificial habitats for microbes that simulate soil structures. Microfluidic, so called Lab-on-a-chip technologies, are one of the tools used to achieve our purpose. Such micro-habitats consist of pillar structures of difference density and surface area, tunnels with increasing depth, and mazes of increasing complexity to simulate different stages of soil aggregation. Using microscopy and analytical chemistry, we can follow the growth of microorganisms inoculated into the "soil chip" as well as the chemical degradation of organic matter compounds provided as nutrient source. In this way, we want to be able to predict how soil structure influences soil microbial activity leading to different effects on the carbon cycle. Our first results of a chip inoculated with natural soil showed a succession of organisms colonizing channels leading to dead-end arenas, starting with a high presence of bacteria inside the chip during the first days. Fungal hyphae growth gradually inside the channels until it finally occupied the big majority of the spaces isolating bacteria which

  5. Influence of the soil genesis on physical and mechanical properties.

    Science.gov (United States)

    Marschalko, Marian; Yilmaz, Işık; Fojtová, Lucie; Kubečka, Karel; Bouchal, Tomáš; Bednárik, Martin

    2013-01-01

    The paper deals with the influence of soil genesis on the physical-mechanical properties. The presented case study was conducted in the region of the Ostrava Basin where there is a varied genetic composition of the Quaternary geological structure on the underlying Neogeneous sediments which are sediments of analogous granulometry but different genesis. In this study, 7827 soil samples of an eolian, fluvial, glacial, and deluvial origin and their laboratory analyses results were used. The study identified different values in certain cases, mostly in coarser-grained foundation soils, such as sandy loam S4 (MS) and clayey sand F4 (CS). The soils of the fluvial origin manifest different values than other genetic types. Next, based on regression analyses, dependence was proved neither on the deposition depth (depth of samples) nor from the point of view of the individual foundation soil classes or the genetic types. The contribution of the paper is to point at the influence of genesis on the foundation soil properties so that engineering geologists and geotechnicians pay more attention to the genesis during engineering-geological and geotechnical investigations.

  6. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    KAUST Repository

    Serrano, Oscar

    2016-08-15

    Biotic and abiotic factors influence the accumulation of organic carbon (C-org) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher C-org stocks (averaging 6.3 kg C-org m(-2) at 3- to 4-fold higher rates (12.8 gC(org) m(-2) yr(-1) ) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg C-org m(-2) and 3.6 g C-org m(-2) yr(-1) . In shallower meadows, C-org stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr(-1) and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr(-1) and 5 %, respectively). The C-org stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg C-org m(-2) and 1.2 g C-org m(-2) yr(-1)were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  7. Stone Columns - Determination of the soil improvement factor

    Science.gov (United States)

    Pivarč, J.

    2011-09-01

    A stone column is one of the soil stabilizing methods that is used to increase strength, decrease the compressibility of soft and loose fine graded soils, accelerate a consolidation effect and reduce the liquefaction potential of soils. The columns consist of compacted gravel or crushed stone arranged by a vibrator. This paper deals with Priebe's theory (1976) on the design of an improvement factor, which belongs among the most used analytical methods and also describes the numerical and laboratory models of stone columns. The improvement factors calculated from numerical and laboratory models are compared with the improvement factors resulting from Priebe's theory.

  8. 几种土壤属性制图方法的稳定性与影响因素分析%Analysis and Comparison in Stabilities and Related Influence Factors for Several Common Methods Used in Soil Property Mapping

    Institute of Scientific and Technical Information of China (English)

    齐力; 赵彦锋; 巫振富; 张路伟

    2012-01-01

    Total 870 soil samples were collected from the north of Henan Province over a 27 955 km2area. Two subgroups with 435 samples were respectively used in soil property map-making, i. e. the content of exchangeable cations (CEC) and the total nitrogen (TN). The difference of map-making results between two subgroups was calculated. The stability among Kriging method, inverse distance weight method (IDW) and polygon value represented by point value method (PRP) were compared and its' influencing factors were discussed. The results showed that; (i) RMSECRoot Mean Square Error)and R (correlation coefficient) between measured data and predicted data could not represent the stability of map-making, namely, the returning probability of the spatial pattern of soil properties. And the result was differential in precision validation when using different ways, (ii) The stability of Kriging and IDW were significantly superior to the PRP. The area with relative difference lower than 0. 3 didn't achieved 20% of the total area in Kriging and IDW mapping methods, but it achieved 51. 57% in PRP mapping method. The area with a high difference level was scattered in the difference map when using the former two methods, but it was centralized and showed by big polygons when using PRP. (iii) The stability of soil property map-making results was disturbed by both sample distribution and high variability of soils in local area. Sample distribution was much important in keeping stability in Kriging method than that in IDW and PRP methods. In the two latter ways high variability among data values showed much impressive effects.%本文以土壤CEC和土壤全氮为研究对象,在河南省黄河以北6个地市选取870个样点,并随机均分为两个数据集,进行了制图对比分析;同时研究了Kriging法、IDW法和以点代面法制图结果的稳定性及其与精度的关系,以及影响因素.结果表明:采用实测数据与预测数据的交叉验证并不能用来衡量制

  9. Influence of soil type on half-highbush blueberry productivity

    Directory of Open Access Journals (Sweden)

    Tea Tasa

    2012-12-01

    Vaccinium spp. cultivars (five- and six-year-old plants were used in the experiment: ‘Aino’, ‘Alvar’, ‘Arne’, and ‘Northblue’. Environmental conditions exercised a considerable influence on biological processes of half-highbush blueberry, at the same time, a genotype-based variation was observed. Cultivar ‘Northblue’ had a higher yield in mineral soil and ‘Aino’ had the highest yield in peat soil considering the average of two years. The peat soil condition in the harvested peat field provided a better supply of nutrients for blueberry bushes compared to mineral soil and this, in its turn, secured better growth and a higher yield of blueberry bushes.

  10. The influence of soil moisture deficits on Australian heatwaves

    Science.gov (United States)

    Herold, N.; Kala, J.; Alexander, L. V.

    2016-06-01

    Several regions of Australia are projected to experience an increase in the frequency, intensity and duration of heatwaves (HWs) under future climate change. The large-scale dynamics of HWs are well understood, however, the influence of soil moisture deficits—due for example to drought—remains largely unexplored in the region. Using the standardised precipitation evapotranspiration index, we show that the statistical responses of HW intensity and frequency to soil moisture deficits at the peak of the summer season are asymmetric and occur mostly in the lower and upper tails of the probability distribution, respectively. For aspects of HWs related to intensity, substantially greater increases are experienced at the 10th percentile when antecedent soil moisture is low (mild HWs get hotter). Conversely, HW aspects related to longevity increase much more strongly at the 90th percentile in response to low antecedent soil moisture (long HWs get longer). A corollary to this is that in the eastern and northern parts of the country where HW-soil moisture coupling is evident, high antecedent soil moisture effectively ensures few HW days and low HW temperatures, while low antecedent soil moisture ensures high HW temperatures but not necessarily more HW days.

  11. The Soil Microbiome Influences Grapevine-Associated Microbiota

    OpenAIRE

    Zarraonaindia, Iratxe; Owens, Sarah M.; Weisenhorn, Pamela; West, Kristin; Hampton-Marcell, Jarrad; Lax, Simon; Bokulich, Nicholas A; Mills, David A.; Martin, Gilles; Taghavi, Safiyh; van der Lelie, Daniel; Gilbert, Jack A

    2015-01-01

    ABSTRACT Grapevine is a well-studied, economically relevant crop, whose associated bacteria could influence its organoleptic properties. In this study, the spatial and temporal dynamics of the bacterial communities associated with grapevine organs (leaves, flowers, grapes, and roots) and soils were characterized over two growing seasons to determine the influence of vine cultivar, edaphic parameters, vine developmental stage (dormancy, flowering, preharvest), and vineyard. Belowground bacteri...

  12. Psychological Factors Influencing Consumer Behaviour

    OpenAIRE

    Vainikka, Bianca

    2015-01-01

    This paper’s aim is to provide an in-depth elucidation of the many aspects that influence consumer behaviour. The study of consumer behaviour emphasizes the “why” and “how” questions involved in decision making and buying behaviour. This exciting field visits a dynamic blend of themes of consumer marketing strategies, psychology and behavioural discipline. Consumer behaviour in this day and age is highly applicable to modern society as it is an integral part of our everyday lives. This paper ...

  13. Influence of fines content on the anti-frost properties of coarse-grained soil

    Institute of Scientific and Technical Information of China (English)

    TianLiang Wang; ZuRun Yue; TieCheng Sun; JinChuang Hua

    2015-01-01

    This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows: (1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles, the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engi-neering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions.

  14. Selenate redistribution during aging in different Chinese soils and the dominant influential factors.

    Science.gov (United States)

    Wang, Dan; Zhou, Fei; Yang, Wenxiao; Peng, Qin; Man, Nan; Liang, Dongli

    2017-09-01

    To date, few works have attempted to determine the effect of soil types on Selenium aging process and the possible influential factors. In this study, the differences in Se speciation distribution and availability in 15 Chinese typical agricultural soils were investigated using spiked selenate for the entire year. Results evidenced that after one year of incubation, Se transformed from soluble fraction to Fe/Mn oxides and organic matter bound fractions in neutral or alkaline soils (pH 7.09-8.51) and from exchangeable fraction to residual fraction in acidic soils (pH 4.89-6.82). The available Se content in all soils declined rapidly at the initial stage of aging, with most of the neutral or alkaline soils reaching equilibrium after 109 d, whereas the acidic soils reached equilibrium after only 33-56 d. The available Se content in soil decreased constantly during the entire aging process in S4 (Xinjiang Gray desert soil), S12 (Anhui Yellow brown earths), and S15 (Hunan Krasnozems). Elovich model was the best model (R(2) > 0.80) in describing the Se aging process. Estimated time for exogenous Se reaching the distribution of available Se in corresponding native soils extended from 9.7 y to 50.2 y, indicating a much longer time was required for spiked soil to reach equilibrium. Soil pH was the most significant factor directly and negatively influencing the aging process (p speciation. Results could provide reference for the selection of unified equilibrium time on Se-spiked experiment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Study on the numerical simulation of gravel soil slope stability and influencing factors%碎石土边坡稳定性及影响因素的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    吴周明; 傅军健

    2012-01-01

    Combined with practiced engineering, adopting the analytic way of elasto-plastic FDM shear strength reduction, the safety coefficient of the gravel soil slope was calculate by the numerical simulation and compared with the traditional analysis method. The influencing on the slope stability of the soil properties and calculation model parameters was analyzed and researched. The results indicated,FLAC3D analysis software has a good advantage on analysising slope stability feasible, cohesion, internal friction angle and density of soil are significant impact on slope stability.%结合工程实例,采用有限差分强度折减法对碎石土边坡进行稳定性数值模拟求得安全系数,并与传统分析方法进行计算比较.同时,分析边坡土性及计算模型参数对稳定性的影响.结果表明,FLAC3D分析边坡的稳定性可行且具有较好的优越性,内聚力、内摩擦角及土体密度对边坡稳定性的影响更加显著.

  16. Thymic Output: Influence Factors and Molecular Mechanism

    Institute of Scientific and Technical Information of China (English)

    Rong Jin; Jun Zhang; Weifeng Chen

    2006-01-01

    Thymus is a primary lymphoid organ, able to generate mature T cells that eventually colonize secondary lymphoid organs, and is therefore essential for peripheral T cell renewal. Recent data showed that normal thymocyte export can be altered by several influence factors including several chemokines,sphingosinel-phosphate (S1P),transcription factors such as Foxjl, Kruppel-like transcription factor 2 (KLF2) and antigen stimulation, etc. In this review, we summarized the recent reports about study strategies, influence factors and possible molecular mechanisms in thymic output.

  17. Landscape changes influence the occurrence of the melioidosis bacterium Burkholderia pseudomallei in soil in northern Australia.

    Directory of Open Access Journals (Sweden)

    Mirjam Kaestli

    Full Text Available BACKGROUND: The soil-dwelling saprophyte bacterium Burkholderia pseudomallei is the cause of melioidosis, a severe disease of humans and animals in southeast Asia and northern Australia. Despite the detection of B. pseudomallei in various soil and water samples from endemic areas, the environmental habitat of B. pseudomallei remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: We performed a large survey in the Darwin area in tropical Australia and screened 809 soil samples for the presence of these bacteria. B. pseudomallei were detected by using a recently developed and validated protocol involving soil DNA extraction and real-time PCR targeting the B. pseudomallei-specific Type III Secretion System TTS1 gene cluster. Statistical analyses such as multivariable cluster logistic regression and principal component analysis were performed to assess the association of B. pseudomallei with environmental factors. The combination of factors describing the habitat of B. pseudomallei differed between undisturbed sites and environmentally manipulated areas. At undisturbed sites, the occurrence of B. pseudomallei was found to be significantly associated with areas rich in grasses, whereas at environmentally disturbed sites, B. pseudomallei was associated with the presence of livestock animals, lower soil pH and different combinations of soil texture and colour. CONCLUSIONS/SIGNIFICANCE: This study contributes to the elucidation of environmental factors influencing the occurrence of B. pseudomallei and raises concerns that B. pseudomallei may spread due to changes in land use.

  18. 31. FACTORS INFLUENCING UTILIZATION OF INTERMITTENT ...

    African Journals Online (AJOL)

    Esem

    treatment of malaria during pregnancy(IPTp), effective IPTp service utilization ... effective case management of malaria. Despite the ... Factors influencing IPTp utilization identified in the study included; educational status of a woman,. Medical ...

  19. Home Environmental Factors Influencing Performance and Progress ...

    African Journals Online (AJOL)

    ... Factors Influencing Performance and Progress of Primary School Pupils in ... found that parents' educational level and income level have a bearing on school ... on school progress and performance, however; home language did play a role.

  20. Factors Influencing Self Employment Media Service Providers ...

    African Journals Online (AJOL)

    Factors Influencing Self Employment Media Service Providers among Tertiary ... role stereotype and common business practices on media self employment in ... Sex, Psycho-social Characteristics, self Employment, Providing Media Services.

  1. Age-Related Factors That Influence Fertility

    Science.gov (United States)

    ... can be found at the NICHD Pregnancy Loss topic page . Committee on Gynecologic Practice of American College of ... 2012, from http://www.nichd.nih.gov/health/topics/pregnancyloss/researchinfo/Pages/default.aspx [top] « Lifestyle Factors That Influence Fertility ...

  2. Factors that negatively influence consumption of traditionally ...

    African Journals Online (AJOL)

    Factors that negatively influence consumption of traditionally fermented milk ... of sub-Saharan Africa and a number of health benefits to human beings are ... Key words: Mursik, Lactic acid bacteria (LAB), probiotic, Preschoolers, Focus group

  3. FACTORS INFLUENCING THE SELECTION OF DENTAL NURSING ...

    African Journals Online (AJOL)

    drclement

    FACTORS INFLUENCING THE SELECTION OF DENTAL NURSING AS A. PROFESSION ... Colleges of Health Technology undergoing external ... questionnaire requested information on age ... individual with good communication skills and ...

  4. Factors that Influence Adolescents to Smoke.

    Science.gov (United States)

    Smith, Karen H.; Stutts, Mary Ann

    1999-01-01

    A survey of the factors that influence adolescents (n=246) to smoke found that family smoking behavior, peer pressure, and prior beliefs were more important in predicting smoking level than were advertising and antismoking information. (Author/JOW)

  5. FACTORS INFLUENCING SUSTAINED MANAGERIAL EFFICIENCY

    Directory of Open Access Journals (Sweden)

    Alexandru Marius RIZESCU

    2017-04-01

    Full Text Available The concept of effectiveness is learnable in economic theory and practice with various forms of manifestation of the results obtained by the managers, such as profitability, the productivity of factors of production, capital efficiency, cost savings, etc. Regarded as the organizing principle and driving activity in the market economy, it has a much richer content and also favorable results of generalizing all derived by managers. Choosing effective in meeting needs with limited resources or powerlessness to maximize resource needs under restrains, are expressions through which efficiency is situated at the heart of economic theory and practice.

  6. Soil bioindicators : how soil properties influence their responses and how to select them in function of the site issues ?

    OpenAIRE

    Pauget, Benjamin; Rougé, Laurence; Vaufleury, Annette De; Dequiedt, Samuel; Gattin, Isabelle; Grand, Cécile; Le Guédard, Marina; Hedde, Mickaël; Villenave, Cécile; Peres, Guenola

    2014-01-01

    Context - Despite no directive exists for soil protection, this key component of ecosystem needs to be protected. To fill the lack of tools to monitor the soil threats and to assess the impact of soil management, biological indicators have been developed in the French program Bioindicators 2 (ADEME). On the 47 plots of 13 sites (agricultural, industrial and forest), the influence of soil characteristics and soil use on the response of 80 biological parameters (fauna, flora and microorganisms)...

  7. How do peat type, sand addition and soil moisture influence the soil organic matter mineralization in anthropogenically disturbed organic soils?

    Science.gov (United States)

    Säurich, Annelie; Tiemeyer, Bärbel; Don, Axel; Burkart, Stefan

    2017-04-01

    Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. As a consequence of both drainage induced mineralization and anthropogenic sand mixing, large areas of former peatlands under agricultural use contain soil organic carbon (SOC) at the boundary between mineral and organic soils. Studies on SOC dynamics of such "low carbon organic soils" are rare as the focus of previous studies was mainly either on mineral soils or "true" peat soil. However, the variability of CO2 emissions increases with disturbance and therefore, we have yet to understand the reasons behind the relatively high CO2 emissions of these soils. Peat properties, soil organic matter (SOM) quality and water content are obviously influencing the rate of CO2 emissions, but a systematic evaluation of the hydrological and biogeochemical drivers for mineralization of disturbed peatlands is missing. With this incubation experiment, we aim at assessing the drivers of the high variability of CO2 emissions from strongly anthropogenically disturbed organic soil by systematically comparing strongly degraded peat with and without addition of sand under different moisture conditions and for different peat types. The selection of samples was based on results of a previous incubation study, using disturbed samples from the German Agricultural Soil Inventory. We sampled undisturbed soil columns from topsoil and subsoil (three replicates of each) of ten peatland sites all used as grassland. Peat types comprise six fens (sedge, Phragmites and wood peat) and four bogs (Sphagnum peat). All sites have an intact peat horizon that is permanently below groundwater level and a strongly disturbed topsoil horizon. Three of the fen and two of the bog sites have a topsoil horizon altered by sand-mixing. In addition the soil profile was mapped and samples for the determination of soil hydraulic properties were collected. All 64 soil columns (including four additional reference samples) will be installed

  8. Ecology of cultivable yeasts in pristine forests in northern Patagonia (Argentina) influenced by different environmental factors.

    Science.gov (United States)

    Mestre, María Cecilia; Fontenla, Sonia; Rosa, Carlos A

    2014-06-01

    Environmental factors influencing the occurrence and community structure of soil yeasts in forests are not well studied. There are few studies dedicated to Southern Hemisphere soil yeasts populations and even fewer focused on temperate forests influenced by volcanic activity. The present work aimed to study the ecology of soil yeast communities from pristine forests influenced by different environmental factors (precipitation, physicochemical properties of soil, tree species, soil region, and season). The survey was performed in 4 northern Patagonian forests: 2 dominated by Nothofagus pumilio and 2 by Nothofagus antarctica. Yeast communities were described with ecological indices and species accumulation curves, and their association with environmental characteristics was assessed using multivariate analysis. Each forest site showed a particular arrangement of species as a result of environmental characteristics, such as dominant plant species, nutrient availability, and climatic characteristics. Cryptococcus podzolicus was most frequently isolated in nutrient-rich soils, Trichosporon porosum dominated cold mountain forests with low nutrient and water availability in soil, and capsulated yeasts such as Cryptococcus phenolicus dominated forest sites with low precipitation. The present work suggests that environmental factors affecting yeast communities may not be the current soil characteristics but the result of complex interactions of factors including natural disturbances like volcanic activity.

  9. ENERGY EFFICIENCY. TRENDS AND INFLUENCE FACTORS

    Directory of Open Access Journals (Sweden)

    Zizi GOSCHIN

    2006-12-01

    Full Text Available Energy efficiency is correlated with many factors of influence: Gross National Income per capita, energy imports (% of energy use, renewable combustible and waste (% of total, energy use per capita, services as % of GDP and others. In this paper we are testing a model of piecewise linear regression with breakpoint in order to measure the influence of these factors on the variation of GDP per unit of energy use in Europe in the year 2003.

  10. Poro-mechanical coupling influences on potential for rainfall-induced shallow landslides in unsaturated soils

    Science.gov (United States)

    Wu, L. Z.; Selvadurai, A. P. S.; Zhang, L. M.; Huang, R. Q.; Huang, Jinsong

    2016-12-01

    Rainfall-induced landslides are a common occurrence in terrain with steep topography and soils that have degradable strength. Rainfall infiltration into a partially saturated slope of infinite extent can lead to either a decrease or complete elimination of soil suction, compromising the slopes' stability. In this research the rainfall infiltration coupled with deformation of a partially saturated soil slope during rainfall infiltration is analyzed. The limit equilibrium conditions and the shear strength relationship of a partially saturated soil are employed to develop an analytical solution for calculating the stability of an infinite partially saturated slope due to rainfall infiltration. The analytical solutions are able to consider the influence of the coupled effects on the stability of the slope. The factors that affect the safety of a partially saturated slope of infinite extent are discussed. The results indicate that the poro-mechanical coupling of water infiltration and deformation has an important effect on the stability of the infinite unsaturated slope.

  11. 石油污染对冻土热传导的影响%The Oil Contamination Influence on Heat Transfer in Frozen Soils

    Institute of Scientific and Technical Information of China (English)

    Zhuravlev Igor Igorevich; Motenko Rimma Grigoryevna

    2004-01-01

    Complex experimental research of thermal properties of oil-contaminated frozen soils was carried out. On the basis of the obtained results the influence of the various factors connected with oil pollution on heat transfer in frozen soils was analyzed. And the model of heat transfer in frozen soils was offered.

  12. Soil moisture influenced the interannual variation in temperature sensitivity of soil organic carbon mineralization in the Loess Plateau

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2015-01-01

    Full Text Available Temperature sensitivity of SOC mineralization (Q10 determines how strong the feedback from global warming may be on the atmospheric CO2 concentration, thus understanding the factors influencing the interannual variation in Q10 is important to accurately estimate the local soil carbon cycle. In situ SOC mineralization was measured using an automated CO2 flux system (Li-8100 in long-term bare fallow soil in the Loess Plateau (35° 12' N, 107° 40' E in Changwu, Shaanxi, China form 2008 to 2013. The results showed that the annual cumulative SOC mineralization ranged from 226 to 298 g C m−2 y−1 (mean =253 g C m−2 y−1; CV =13%, annual Q10 ranged from 1.48 to 1.94 (mean =1.70; CV =10%, and annual soil moisture content ranged from 38.6 to 50.7% WFPS (mean =43.8% WFPS; CV =11%, which were mainly affected by the frequency and distribution of precipitation. Annual Q10 showed a negative quadratic correlation with soil moisture. In conclusion, understanding of the relationships between interannual variation in Q10 of SOC mineralization, soil moisture and precipitation is important to accurately estimate the local carbon cycle, especially under the changing climate.

  13. Persistence of benthiocarb in soil: influence of ultraviolet and sunlight

    Directory of Open Access Journals (Sweden)

    Md. Wasim Aktar

    2008-12-01

    Full Text Available Persistence of benthiocarb in soil as affected by UV and sunlight exposure was studied. Treated soil was placed in petri plate, brought to field capacity moisture and then exposed to UV and sunlight. Residues of benthiocarb in soil dissipated with half lives of 2.10, 11.85 and 43.63 days under UV, sunlight and dark condition, respectively. Soil samples kept under dark showed the slowest dissipation. Further, benthiocarb residues dissipated quickly under UV light as compared to sunlight. Exposure of thin film of benthiocarb confirmed that it is photo labile and dissipated very fast with half life of 1.16 and 1.77 days following exposure to UV and sunlight, respectively. The study revealed that UV component of sunlight is an important factor for benthiocarb dissipation.

  14. Variation properties of ionospheric eclipse factor and ionospheric influence factor

    Institute of Scientific and Technical Information of China (English)

    ZHAO Chunmei; YUAN Yunbin; OU Jikun; CHEN Jinping

    2005-01-01

    The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GPS data to determine ionospheric delay based on the above variation properties is also analysed.

  15. The influence of vegetation on soil water repellency-markers and soil hydrophobicity.

    Science.gov (United States)

    Mao, Jiefei; Nierop, Klaas G J; Rietkerk, Max; Sinninghe Damsté, Jaap S; Dekker, Stefan C

    2016-10-01

    Soil water repellency (SWR) markers are defined as hydrophobic compounds in soil causing SWR and are mainly derived from plants. Previous studies have shown the types and abundance of SWR-markers in soils. However, how these SWR-markers are exactly related to SWR and their origin is poorly understood. This study aims to understand the relationship between SWR-markers, vegetation type and cover and SWR for a simple sandy soil ecosystem, consisting of oaks with sedge and six grass species. All the soil (at different depth) and vegetation samples were collected in the field along a 6m transect, starting from an oak tree. Further along the transect grasses and sedges became more abundant. Free and ester-bound lipids from soils and plant leaves/roots were obtained using a sequential extraction method and identified by gas chromatography-mass spectrometry. Significant linear correlations were found between the main soil characteristics, such as total organic carbon content, and SWR. Single long-chain (>C20) SWR-markers derived from both plant leaf waxes and roots positively related to SWR. Both ester-bound ω-hydroxy fatty acids and C22 and C24 α,ω-dicarboxylic acids were predominantly present in the grass roots, but to a lesser extent in the roots of oak and sedge. These suberin-derived ω-hydroxy fatty acids and α,ω-dicarboxylic acids characteristic of roots could well predict the SWR. Additionally, the SWR predictors abundantly present in the soils matched well with high concentrations of the corresponding biomarkers in the dominant vegetation species that covered the soils. Our analyses demonstrated that grass roots influenced SWR more due to their more substantial contribution of organic matter to the topsoils than oak roots. This led to a stronger SWR of the soils covered with grass than those covered with oak vegetation. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Influence of soil amendments made from digestate on soil physics and the growth of spring wheat

    Science.gov (United States)

    Dietrich, Nils; Knoop, Christine; Raab, Thomas; Krümmelbein, Julia

    2016-04-01

    Every year 13 million tons of organic wastes accumulate in Germany. These wastes are a potential alternative for the production of energy in biogas plants, especially because the financial subventions for the cultivation of renewable resources for energy production were omitted in 2014. The production of energy from biomass and organic wastes in biogas plants results in the accumulation of digestate and therefore causes the need for a sustainable strategy of the utilization of these residues. Within the scope of the BMBF-funded project 'VeNGA - Investigations for recovery and nutrient use as well as soil and plant-related effects of digestate from waste fermentation' the application of processed digestate as soil amendments is examined. Therefore we tested four different mechanical treatment processes (rolled pellets, pressed pellets, shredded compost and sieved compost) to produce soil amendments from digestate with regard to their impact on soil physics, soil chemistry and the interactions between plants and soil. Pot experiments with soil amendments were performed in the greenhouse experiment with spring wheat and in field trials with millet, mustard and forage rye. After the first year of the experiment, preliminary results indicate a positive effect of the sieved compost and the rolled pellets on biomass yield of spring wheat as compared to the other variations. First results from the Investigation on soil physics show that rolled pellets have a positive effect on the soil properties by influencing size and distribution of pores resulting in an increased water holding capacity. Further ongoing enhancements of the physical and chemical properties of the soil amendments indicate promising results regarding the ecological effects by increased root growth of spring wheat.

  17. Assessment of tillage systems in organic farming: influence of soil structure on microbial biomass. First results

    OpenAIRE

    Vian, Jean François; Peigné, Joséphine; Chaussod, Rémi; Roger-Estrade, Jean

    2007-01-01

    Soil tillage modifies environmental conditions of soil microorganisms and their ability to release nitrogen. We compare the influence of reduced tillage (RT) and mouldboard ploughing (MP) on the soil microbial functioning in organic farming. In order to connect soil structure generated by these tillage systems on the soil microbial biomass we adopt a particular sampling scheme based on the morphological characterisation of the soil structure by the description of the soil profile. This method...

  18. FACTORS INFLUENCING COMPOSTING POULTRY WASTE

    Directory of Open Access Journals (Sweden)

    Michał Kopeć

    2015-11-01

    Full Text Available Organic recycling of waste, taking into account sanitary safety, should be a fundamental method for recovering the nutrients present in the waste for plants and organic matter. It also refers to by-products of animal origin, which are not intended for consumption by humans. In the present research , composting of hydrated poultry slaughterhouse waste with maize straw was carried out. A combination with fodder yeast and post-cellulose lime was also introduced, which modified chemical and physico-chemical properties of the mixtures. The experiment was carried out by recording the biomass temperature for 110 days in 1.2×1.0×0.8 m reactors with perforated bottoms enabling active aeration. The following parameters were taken into consideration in the composted material: carbon, nitrogen, sulfur, respiratory activity, microorganisms, fractions of compost obtained after washing on sieves. Small amounts of fodder yeast favoured the development of microorganisms and caused a sanitary risk in the final product. At the initial stage, the temperature of raw compost in that object was several degrees lower than in the case of the composted mass without yeast addition. The addition of post-cellulose lime at ratios 6.5:1:6.5 (maize straw: poultry slaughterhouse waste: post-cellulose lime caused a change in the time of microbiological activity, and led to its inhibition in the final process. In comparison to objects with poultry waste, the highest degree of hygienization was found in the compost with post-cellulose lime (with pH close to neutral. By adjusting the ratios of substrates we can influence the microbiological activity, but the amounts of individual substrates should be determined taking into account the quality of the obtained compost.

  19. Retention and Mobility of Copper and Lead in Soils as Influenced by Soil Horizon Properties

    Institute of Scientific and Technical Information of China (English)

    B. CERQUEIRA; E. F. COVELO; M. L. ANDRADE; F. A. VEGA

    2011-01-01

    The mobility and bioavailability of heavy metals in soils is largely governed by sorption and desorption phenomena.Cu2+ and Pb2+ are among the most potentially toxic heavy metals and they are present,often concomitantly,in many polluting spills and in agrochemicals.The objective was to assess and compare the competitive sorption and desorption capacities and sorption hysteresis of Cu2+ and Pb2+,as well as their migration through the profiles of four natural soils:a Humic Umbrisol,an Umbric Cambisol,an Endoleptic Luvisol and a Humic Cambisol.In all horizons Pb2+ was invariably sorbed and retained to a greater extent than Cu2+.The sorption and retention of Cu2+ were most influenced by pH,effective cation exchange capacity (CECe) and Mn oxide content.On the other hand,the fixation capacity of Pb2+ was most influenced by pH,CECe,and Mn oxide and organic matter contents.pH and CECe were the individual soil properties most markedly influencing Cu2+ and Pb2+ sorption and retention.In all the horizons Pb2+ exhibited greater hysteresis than Cu2+.In each soil the hysteresis in the A horizon was greater than that in the B horizon,except in the Bt horizon of the Endoleptic Luvisol,due to its high pH and vermiculite content.Based on migration indices,Pb2+ was less mobile than Cu2+ in the studied soils.

  20. Factors Influencing the Quality of Mobile Applications

    Directory of Open Access Journals (Sweden)

    Alin ZAMFIROIU

    2014-01-01

    Full Text Available Mobile applications are becoming increasingly used. Mobile devices are becoming indispensable for the user. In the material are claiming the sales of mobile devices internationally and the use of mobile applications compared to traditional internet use on desktop systems for the United States. Are presented influences the quality of mobile applications and based on these influencing factors built a model of choice for optimal application of mobile applications and traditional desktop application. At the end of the material presented methods to increase quality by tracking the influence factors during the development of mobile applications.

  1. Factors influencing alginate gel biocompatibility.

    Science.gov (United States)

    Tam, Susan K; Dusseault, Julie; Bilodeau, Stéphanie; Langlois, Geneviève; Hallé, Jean-Pierre; Yahia, L'Hocine

    2011-07-01

    Alginate remains the most popular polymer used for cell encapsulation, yet its biocompatibility is inconsistent. Two commercially available alginates were compared, one with 71% guluronate (HiG), and the other with 44% (IntG). Both alginates were purified, and their purities were verified. After 2 days in the peritoneal cavity of C57BL/6J mice, barium (Ba)-gel and calcium (Ca)-gel beads of IntG alginate were clean, while host cells were adhered to beads of HiG alginate. IntG gel beads, however, showed fragmentation in vivo while HiG gel beads stayed firm. The physicochemical properties of the sodium alginates and their gels were thoroughly characterized. The intrinsic viscosity of IntG alginate was 2.5-fold higher than that of HiG alginate, suggesting a greater molecular mass. X-ray photoelectron spectroscopy indicated that both alginates were similar in elemental composition, including low levels of counterions in all gels. The wettabilities of the alginates and gels were also identical, as measured by contact angles of water on dry films. Ba-gel beads of HiG alginate resisted swelling and degradation when immersed in water, much more than the other gel beads. These results suggest that the main factors contributing to the biocompatibility of gels of purified alginate are the mannuronate/guluronate content and/or intrinsic viscosity.

  2. Ecological factors governing the distribution of soil microfungi in some forest soils of Pachmarhi Hills, India

    Directory of Open Access Journals (Sweden)

    Shashi Chauhan

    2014-02-01

    Full Text Available An ecological study of the microfungi occurring in the various forest soils of Pachmarhi Hills, India has been carried-out by the soil plate technique. Soil samples from 5 different forest communities viz., moist deciduous forest dominated by tree ferns, Diospyros forest, Terminalia forest, Shorea forest and scrub forest dominated by Acacia and Dalbergia sp. were collected during October, 1983. Some physico-chemical characteristics of the soil were analysed and their role in distribution of fungi in 5 soil types was studied and discussed. 43 fungal species were isolated, of which Asperigillus niger I and Penicillium janthinellum occurred in all the 5 soil types. Statistically, none of the edaphic factors showed positive significant correlation with the number of fungi.

  3. Soil Surface Structure: A key factor for the degree of soil water repellency

    Science.gov (United States)

    Ahn, S.; Doerr, S. H.; Douglas, P.; Bryant, R.; Hamlett, C.; McHale, G.; Newton, M.; Shirtcliffe, N.

    2012-04-01

    Despite of considerable efforts, the degree of water repellency has not always been fully explained by chemical property of soil (termed hydrophobicity). That might be because the structure of a soil surface was not considered properly, which is another main factor determining the severity of soil water repellency. Surface structure has only recently been considered in soil science, whilst it has been paid attention for several decades in materials science due to its relevance to industrial applications. In this contribution, comparison of critical contact angles measured on different surface structures (made with glass beads, glass shards and beach sands) is presented and the effect of surface structure on manifestation of soil water repellency is discussed in terms of several different variables such as the individual particles shape, and areal and structural factors of the actual surface.

  4. What Factors Influence Wind Perceptions

    Science.gov (United States)

    Stein, Tatiana

    Over the last decade, wind power has emerged as a possible source of energy and has attracted the attention of homeowners and policy makers worldwide. Many technological hurdles have been overcome in the last few years that make this technology feasible and economical. The United States has added more wind power than any other type of electric generation in 2012. Depending on the location, wind resources have shown to have the potential to offer 20% of the nation's electricity; a single, large wind turbine has the capacity to produce enough electricity to power 350 homes. Throughout the development of wind turbines, however, energy companies have seen significant public opposition towards the tall white structures. The purpose of this research was to measure peoples' perceptions on wind turbine development throughout their growth, from proposal to existing phase. Three hypotheses were developed based on the participant's political affiliation, proximity and knowledge of wind turbines. To validate these hypotheses, participants were asked an array of questions regarding their perception on economic, environmental, and social impacts of wind turbines with an online service called Amazon Mechanical Turk. The responses were from residents living in the United States and required them to provide their zip code for subsequent analysis. The analysis from the data obtained suggests that participants are favorable towards wind turbine development and would be supportive of using the technology in their community. Political affiliation and proximity to the nearest wind turbine in any phase of development (proposal, construction, existing) were also analyzed to determine if they had an effect on a person's overall perception on wind turbines and their technology. From the analysis, political affiliation was seen to be an indirect factor to understanding favorability towards wind turbines; the more liberal you are, the more supportive you will be towards renewable energy use

  5. Research on tests of the influence factors on creep property of sandy slate coarse-grained soil%砂质板岩粗粒土蠕变特性影响因素试验研究

    Institute of Scientific and Technical Information of China (English)

    韩铠屹; 刘群; 宋晓东

    2014-01-01

    Uniaxial compression creep test was utilized to analyze the effect of moisture conditions and different particle grading components on creep property of sandy slate coarse-grained soil,and investigate the relations between moisture contents or fine particle contents and creep parameters on the basis of H -K Creep Model which is in agreement with the experimental results.The research results show that moisture content and fine par-ticle content are the important factors that affect creep property of sandy slate coarse-grained soil and it is pro-posed to use dry or saturated coarse-grained soil and fine particle content accounting for 30% coarse-grained soil filler to decrease long-term settlement of embankment.%通过单轴压缩蠕变试验研究含水率以及颗粒组成对粗粒土蠕变的影响规律,分析砂质板岩粗粒土在不同影响因素(含水状态、颗粒组成)下的蠕变特性,并基于与试验结果相符的H-K蠕变模型,探讨含水率、细颗粒含量、应力与蠕变参数之间的关系。研究结果表明:含水率、细颗粒含量均为影响粗粒土蠕变特性的重要因素,提出通过使用干燥或饱和含水态的粗粒土填料以及使用细颗粒含量为30%的粗粒土填料的途径来控制路堤的长期沉降。

  6. Patient factors that influence warfarin dose response.

    Science.gov (United States)

    White, Pamela J

    2010-06-01

    Warfarin has long been the mainstay of oral anticoagulation therapy for the treatment and prevention of venous and arterial thrombosis. The narrow therapeutic index of warfarin, and the complex number of factors that influence international normalized ratio (INR) response, makes optimization of warfarin therapy challenging. Determination of the appropriate warfarin dose during initiation and maintenance therapy requires an understanding of patient factors that influence dose response: age, body weight, nutritional status, acute and chronic disease states, and changes in concomitant drug therapy and diet. This review will examine specific clinical factors that can affect the pharmacokinetics and pharmacodynamics of warfarin, as well as the role of pharmacogenetics in optimizing warfarin therapy.

  7. Interspecific Relationships Among Soil Invertebrates Influence Pollutant Effects of Phenanthrene

    DEFF Research Database (Denmark)

    Cortet, J.; Joffre, R.; Elmholt, S.

    2006-01-01

    Five mesofauna communities varying in both structure and composition were exposed to phenanthrene in mesocosms for up to four months. Effects of phenanthrene were assessed on mesofauna population dynamics, fungal biomass (ergosterol concentrations), and litter decomposition (litter mass loss, nit...... toxic effects of organic pollutants on mesofauna species and soil biological functioning......., nitrogen concentration). The effects of each community on the fate of phenanthrene were also assessed. We hypothesize that phenanthrene affects the population dynamics of mesofauna and soil biological functioning depending on exposure duration, type of community, or both. Results show that phenanthrene...... exerted an effect on mesofauna and that the effects on some species, like Folsomia fimetaria, were influenced by the species composition in the mesocosms, the soil layer, and the sampling date. However, the effects of phenanthrene on ergosterol content and organic matter decomposition were...

  8. Factors Affecting Diffusion of Ions in Soils

    Institute of Scientific and Technical Information of China (English)

    LICHENG-BAO; YANGDING-QING

    1993-01-01

    In this work the diffusion coefficients of Na+,K+,Ca2+,NO3- and Cl- ions were estimated in terms of measuring apparent direct current (DC) conductivities of latosol,red soil and yellow-brown earth containing,respectively,NaNO3,NCl,and CaCl2 of different concentrations (0.005,0.05,0.10,and 0.15 mol/L) in the case of moisture contents ranging from wet to water saturation.The results showed that when bulk density,moisture content,and electrolyte concentration were constant,the diffusion coefficients of cations were in the order Na+>K+>Ca2+ except for Na+ and K+ in latosol,while the order for anions was NO3->Cl-.The diffusion coefficients (Di) of cations and anions were linearly proportional to volumetric moisture content (θ) as electrolyte concentration and bulk density were unchanged.When moisture content and bulk density were constant,the diffusion coefficients of cations decreased,to varying extents,with the increase of electrolyte concentration,and the decrement in different soils followed the order yellow-brown earth> red soil> latosol,but the decrement order of different cations was Na+>K+>Ca2+.

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

    Science.gov (United States)

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

    2014-08-01

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

  10. Influences affecting the soil-water characteristic curve

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jian; YU Jian-lin

    2005-01-01

    The soil-water characteristic curve (SWCC) is the primary partially saturated soil information as its behavior and properties can be derived from it. Although there have been many studies of unsaturated soils and the SWCC, there is still no combined constitutive model that can simulate soil characteristics accurately. In cases when hydraulic hysteresis is dominant (e.g.under cyclic loading) it is particularly important to use the SWCC. In the past decades, several mathematical expressions have been proposed to model the curve. There are various influences on the SWCC as a source of information, so the curves obtained from conventional tests often cannot be directly applied;and the mathematical expressions from one scenario cannot be used to simulate another situation. The effects of void ratio, initial water content, stress state and high suction were studied in this work revealing that water content and stress state are more important than the other effects;but that the influences tend to decrease when suction increases. The van Genuchten model was modified to simulate better the changes in the degree of saturation at low values of suction. Predictions were compared with experimental results to determine the simulation capability of the model.

  11. Influence factors of morphological development of soil cracks in degraded slopes in Yuanmou dry-hot valley region%元谋干热河谷区退化坡地土壤裂缝形态发育的影响因子

    Institute of Scientific and Technical Information of China (English)

    熊东红; 杨丹; 李佳佳; 苏正安; 董一帆; 翟娟

    2013-01-01

      土壤开裂影响土体内水分散失、溶质运移及土体结构,是元谋干热河谷坡地退化的一个重要过程及特征。该文通过对元谋干热河谷退化坡地典型土壤裂缝样方的实地调查及数据的室内分析,系统分析了土壤理化属性对裂缝发育程度的影响。研究结果表明:1)土壤裂缝发育程度与土壤黏粒含量、土壤胀缩度、土壤容重呈正相关,与土壤有机质含量、土壤总孔隙度呈较弱的负相关;2)土壤裂缝发育程度的首要影响因子是土壤结构性因子(土壤容重、总孔隙度和黏粒含量),其次为土壤胀缩度,然后是土壤有机质。该研究可为进一步研究土壤开裂导致的土地退化过程奠定基础,为制定开裂土体的改良措施提供参考。%Soil cracking is an important process and feature of the slope degradation in Yuanmou Dry-hot Valley Region, which influences water evaporation, solutes transport and soil structure. In this paper, 25 soil crack quads were investigated by using the photography method to describe the morphology of soil cracks, and meanwhile, soil samples were also obtained at soil depth 0-30 cm and >30-60 cm in the same quad. The crack area density (Dc) was obtained by ArcGIS 9.0. The values for soil physico-chemical properties were also obtained by laboratory analysis. And then, the influences of soil physico-chemical properties on the development degrees of soil cracks were analyzed by application of statistical analysis methods. The Results indicate that: (1) The development degrees of soil cracks have a positive correlation with clay content, swell-shrink property and bulk density, and are negatively correlated to organic content and soil porosity. Dc, which is the quantitative indicator for the development degrees of soil cracks has been found to have a significant strong correlation with clay content, their coefficients were 0.97 and 0.95 for 0-30 cm layer and for >30-60 cm

  12. Greenhouse gas emission factors associated with rewetting of organic soils

    Directory of Open Access Journals (Sweden)

    D. Wilson

    2016-04-01

    Full Text Available Drained organic soils are a significant source of greenhouse gas (GHG emissions to the atmosphere. Rewetting these soils may reduce GHG emissions and could also create suitable conditions for return of the carbon (C sink function characteristic of undrained organic soils. In this article we expand on the work relating to rewetted organic soils that was carried out for the 2014 Intergovernmental Panel on Climate Change (IPCC Wetlands Supplement. We describe the methods and scientific approach used to derive the Tier 1 emission factors (the rate of emission per unit of activity for the full suite of GHG and waterborne C fluxes associated with rewetting of organic soils. We recorded a total of 352 GHG and waterborne annual flux data points from an extensive literature search and these were disaggregated by flux type (i.e. CO2, CH4, N2O and DOC, climate zone and nutrient status. Our results showed fundamental differences between the GHG dynamics of drained and rewetted organic soils and, based on the 100 year global warming potential of each gas, indicated that rewetting of drained organic soils leads to: net annual removals of CO2 in the majority of organic soil classes; an increase in annual CH4 emissions; a decrease in N2O and DOC losses; and a lowering of net GHG emissions. Data published since the Wetlands Supplement (n = 58 generally support our derivations. Significant data gaps exist, particularly with regard to tropical organic soils, DOC and N2O. We propose that the uncertainty associated with our derivations could be significantly reduced by the development of country specific emission factors that could in turn be disaggregated by factors such as vegetation composition, water table level, time since rewetting and previous land use history.

  13. The Influence of Age, Location and Soil Conditions on the Allometry of Young Norway Spruce (Picea abies L. Karst. Trees

    Directory of Open Access Journals (Sweden)

    Ioan DUTCA

    2014-12-01

    Full Text Available In this study the influence of tree’s age, location (i.e. latitude and altitude and soil conditions (i.e. pH, humus content, carbon to nitrogen ratio, cation exchange capacity and percent base saturation on tree allometry was investigated. The data was collected from 22 Norway spruce (Picea abies L. Karst plantations located in Eastern Carpathians of Romania, aged between 4 and 15. From each plantation a soil sample and 10 trees were collected for soil chemical properties and biomass measurements, respectively. Root collar diameter (RCD and height (H based allometric equations were developed for total tree and vegetative organs of the tree (i.e. stem, branches, needles and roots. Furthermore, the interaction between the standardised residuals of these models and the tested factors was analysed. In order to account for the random effect of the clustered data, the mixed-effect modelling procedure was used. The results have shown no influence of these factors (age, location and soil conditions on RCD based models, except for branches biomass model which was linked to soil carbon/nitrogen ratio. The H based models, however, were significantly influenced by latitude and soil cation exchange capacity as a consequence of H/RCD ratio change with these factors. The trees were more likely to allocate more to height growth when growing in higher latitudes or on soils with higher values of cation exchange capacity.

  14. The influence of wildfire severity on soil char composition and nitrogen dynamics

    Science.gov (United States)

    Rhoades, Charles; Fegel, Timothy; Chow, Alex; Tsai, Kuo-Pei; Norman, John, III; Kelly, Eugene

    2017-04-01

    Forest fires cause lasting ecological changes and alter the biogeochemical processes that control stream water quality. Decreased plant nutrient uptake is the mechanism often held responsible for lasting post-fire shifts in nutrient supply and demand, though other upland and in-stream factors also likely contribute to elevated stream nutrient losses. Soil heating, for example, creates pyrogenic carbon (C) and char layers that influence C and nitrogen (N) cycling. Char layer composition and persistence vary across burned landscapes and are influenced first by fire behavior through the temperature and duration of combustion and then by post-fire erosion. To evaluate the link between soil char and stream C and N export we studied areas burned by the 2002 Hayman Fire, the largest wildfire in Colorado, USA history. We compared soil C and N pools and processes across ecotones that included 1) unburned forests, 2) areas with moderate and 3) high wildfire severity. We analyzed 1-2 cm thick charred organic layers that remain visible 15 years after the fire, underlying mineral soils, and soluble leachate from both layers. Unburned soils released more dissolved organic C and N (DOC and DON) from organic and mineral soil layers than burned soils. The composition of DOC leachate characterized by UV-fluorescence, emission-excitation matrices (EEMs) and Fluorescence Regional Integration (FRI) found similarity between burned and unburned soils, underscoring a common organic matter source. Humic and fulvic acid-like fractions, contained in regions V and III of the FRI model, comprised the majority of the fluorescing DOM in both unburned and char layers. Similarity between two EEMs indices (Fluorescence and Freshness), further denote that unburned soils and char layers originate from the same source and are consistent with visual evidence char layers contain significant amounts of unaltered OM. However, the EEMs humification index (HIX) and compositional analysis with pyrolysis GCMS

  15. Soil Microbial Biomass Dynamics and Influence Factors in Larix gmelinii Forest in Daxing' an Mountains%兴安落叶松林土壤微生物生物量季节动态及影响因素

    Institute of Scientific and Technical Information of China (English)

    邸雪颖; 耿莹莹; 孙龙; 胡海清

    2012-01-01

    The seasonal dynamics of soil microbial biomass carbon and nitrogen in a Larix gmelinii forest in Tahe Forestry Bureau of Daxing' an Mountains were studied by using the chloroform fumigation extraction method. The relationships between soil microbial biomass dynamics and environmental factors were also analyzed. Results showed that the microbial biomass carbon ranged from 70.02 to 1 065.38 mg · kg-1, and the microbial biomass nitrogen from 15.63 to 75.18 mg · kg-1 in larch forest. The microbial biomass carbon and nitrogen basically showed an upward trend from May to June and a downward trend from June to August, and reached the maximum value in September, then began to decline, which exhibited a seasonal variation pattern with 1 -2 peaks. Pearson correlation analysis indicated that the microbial biomass carbon was significantly correlated with microbial biomass nitrogen( P<0. 05). The microbial biomass carbon was negatively correlated with soil temperature(P<0.05), and positively correlated with soil organic content and soil total nitrogen(P<0.01). The microbial biomass nitrogen was positively correlated with soil organic content and soil total nitrogen ( P<0.01).%应用氯仿熏蒸浸提法测定了大兴安岭塔河地区兴安落叶松林(Larix gmelinii Rupr.)土壤微生物生物量碳(Cm)和微生物量氮(Nm)的季节动态变化,并研究了其与土壤养分因子和土壤环境因子的关系.结果表明:兴安落叶松林的Cm的变化范围为70.02 ~1 065.38 mg·kg-1,其Nm的变化范围依次为:15.63 ~75.18 mg· kg-1.Cm和Nm基本于5-6月呈上升趋势、6-8月呈下降趋势,9月又达到一个最大值,之后开始下降,其中出现1~2个峰值的季节变化格局.Pearson相关分析表明,Cm与Nm呈显著相关(P<0.05),Cm与土壤温度(Ts)呈显著负相关(P<0.05),Cm与土壤有机碳(Cs.o)和土壤全氮(NT)呈极显著正相关(P<0.O1).Nm与土壤有机碳(Cs.o)和土壤全氮(NT)呈极显著正相关(P<0.01).

  16. Influencing factors in MMR immunisation decision making.

    Science.gov (United States)

    Hill, Marie C; Cox, Carol L

    Immunisation decision making is not a straightforward process for parents. Many factors influence parental decision making on whether they immunise their child with the measles, mumps and rubella (MMR) vaccine. The feasibility study described in this article provides insight into influencing factors associated with decisions regarding the immunisation of children by parents. The study findings suggest that the practice nurse is a credible source of information for parents seeking informed decision making. At a time when the incidence of measles and mumps is rising in the UK, the provision of appropriate information by the practice nurse has the potential to increase uptake of the MMR vaccine.

  17. 气象因子对麦田土壤呼吸速率影响的通径分析%Path Analysis on the Meteorological Factors Impacting Soil Respiration Rate of Wheat Field

    Institute of Scientific and Technical Information of China (English)

    江晓东; 李永秀

    2009-01-01

    [Objective] The experiment aimed to study the effects of meteorological factors under different weather conditions on soil respiration. [Method] The path analysis was used to analyze meteorological factors which influenced soil respiration of wheat field under different weather condition and at jointing stage. [Result] In sunny day, the correlations between ground temperature at 5 cm, solar radiation, air relative humidity, air temperature and soil respiration were all at significant level while solar radiation and ground temperature at 5 cm were the major factors which influenced soil respiration. In cloudy day, solar radiation was a major factor which influenced soil respiration. [Conclusion] The soil respiration and surplus path coefficient in sunny day were all higher than these in cloudy day, which demonstrated that except influenced by ground temperature, air temperature, solar radiation and air relative humidity, the soil respiration was also influenced by other factors especially biological factor.

  18. 吡嘧磺隆抑制矮慈菇效果的影响因素研究%Influence Factors in the Inhibition Effect of Pyrazosulfuron-ethyl against Sagittaria pygmaea in Paddy Soils

    Institute of Scientific and Technical Information of China (English)

    金晨钟; 柏连阳; 刘桂英; 邬腊梅

    2011-01-01

    [目的]探索吡嘧磺隆对矮慈菇抑制效果的影响因素。[方法]在温室内水稻土中进行生物测定。[结果]在1叶1心期施用有效成分45g/hm2,矮慈菇受药7天以上才可达到80%以上的鲜重抑制率;在萌芽期施用高剂量(60g/hm2),不论矮慈菇块茎大小均被完全抑制,当施用低剂量(6g/hm2)时,随着矮慈菇块茎的增大其抑制率逐步降低;灌水深度和施药后的温度对抑制效果影响不显著。在无渗漏有水层状态时,萌芽期与芽后施药矮慈菇的抑制率差异不显著,而在渗漏无水层状态下,芽后用药的抑制率要显著大于前者;芽前用药,较浅土层下(2cm)的矮慈菇抑制率明显较高。[结论]为进一步研究吡嘧磺隆的抑制效果提供依据。%[Objective] The aim was to explore the factors affecting the herbicidal activity of pyrazosulfuron-ethyl against Sagittaria pygmaea in paddy soil.[Method] The bioassay method was carried out under greenhouse conditions.[Result] The reduction of more than 80% in fresh weight was observed in S.pygmaea treated with 45 g/hm2 of pyrazosulfuron-ethyl for 7 d or more.Application of 60 g/hm2 at the sprouting stage of S.pygmaea suppressed completely the growth in fresh weight irrespective of tuber size.However,at 6 g/hm2 growth of the weed sustained less reduction with increasing tuber size.Differences in flooding water depth and temperature had no appreciable influence on the herbicidal activity.Growth inhibition of S.pygmaea by pre-emergence or 1.5-leaf stage applications under non-leaching conditions was significantly higher than that under water leaching conditions.Under non-leaching condition,there was no remarkable difference in this inhibition between preemergence and 1.5-leaf stage applications,while under water leaching conditions the growth reduction with the latter application was significantly larger.Growth inhibition of S.pygmaea planted at a depth of 2 cm was significantly higher than

  19. Spatial Variability of Soil Organic Carbon and Related Factors in Jiangsu Province, China

    Institute of Scientific and Technical Information of China (English)

    CHUAI Xiao-Wei; HUANG Xian-Jin; WANG Wan-Jing; ZHANG Mei; LAI Li; LIAO Qi-Lin

    2012-01-01

    Soil organic carbon (SOC) plays a key role in the global carbon cycle.In this study,we used statistical and geostatistical methods to characterize and compare the spatial heterogeneity of SOC in soils of Jiangsu Province,China,and investigate the factors that influence it,such as topography,soil type,and land use.Our study was based on 24 186 soil samples obtained from the surface soil layer (0-0.2 m) and covering the entire area of the province.Interpolated values of SOC density in the surface layer,obtained by kriging based on a spherical model,ranged between 3.25 and 32.43 kg m-3.The highest SOC densities tended to occur in the Taihu Plain,Lixia River Plain,along the Yangtze River,and in high-elevation hilly areas such as those in northern and southwest Jiangsu,while the lowest values were found in the coastal plain.Elevation,slope,soil type,and land use type significantly affected SOC densities.Steeper slope tended to result in SOC decline.Correlation between elevation and SOC densities was positive in the hill areas but negative in the low plain areas,probably due to the effect of different land cover types,temperature,and soil fertility.High SOC densities were usually found in limestone and paddy soils and low densities in coastal saline soils and alluvial soils,indicating that high clay and silt contents in the soils could lead to an increase,and high sand content to a decrease in the accumulation of SOC.SOC densities were sensitive to land use and usually increased in towns,woodland,paddy land,and shallow water areas,which were strongly affected by industrial and human activities,covered with highly productive vegetation,or subject to long-term use of organic fertilizers or flooding conditions.

  20. INFLUENCE FACTORS FOR LEASING MARKET CONTRACTS

    Directory of Open Access Journals (Sweden)

    Oana BĂRBULESCU

    2016-11-01

    Full Text Available This paper aims to investigate the relationship between leasing contracts and some factors that influence the value of these contracts. In order to do this, we have decided on some quantitative marketing research by appealing to statistics for accomplishing the objectives that we have set: to find a correlation between the turnover percentage assigned to leasing expenses and several influence factors. This study indicated that the more contracts are signed by a firm, the more likely is to assign a bigger fraction of the income to each new leasing contract. The study confirmed that bigger companies are relying more on leasing as a way of financing than small companies. This study also discovered that companies with more employees are using larger contracts in order to sustain their activity. The findings are expected to contribute to adjusting the offers by the leasing companies, taking into consideration these factors and to using these factors in order to better predict the market evolution.

  1. Influence of Organic Manure on Organic Phosphorus Fraction in Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGYONG-SONG; NIWU-ZHONG; 等

    1993-01-01

    The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.

  2. Soil porosity correlation and its influence in percolation dynamics

    Science.gov (United States)

    Rodriguez, Alfredo; Capa-Morocho, Mirian; Ruis-Ramos, Margarita; Tarquis, Ana M.

    2016-04-01

    The prediction of percolation in natural soils is relevant for modeling root growth and optimizing infiltration of water and nutrients. Also, it would improve our understanding on how pollutants as pesticides, and virus and bacteria (Darnault et al., 2003) reach significant depths without being filtered out by the soil matrix (Beven and Germann, 2013). Random walk algorithms have been used successfully to date to characterize the dynamical characteristics of disordered media. This approach has been used here to describe how soil at different bulk densities and with different threshold values applied to the 3D gray images influences the structure of the pore network and their implications on particle flow and distribution (Ruiz-Ramos et al., 2009). In order to do so first we applied several threshold values to each image analyzed and characterized them through Hurst exponents, then we computed random walks algorithms to calculate distances reached by the particles and speed of those particles. At the same time, 3D structures with a Hurst exponent of ca 0.5 and with different porosities were constructed and the same random walks simulations were replicated over these generated structures. We have found a relationship between Hurst exponents and the speed distribution of the particles reaching percolation of the total soil depth. REFERENCES Darnault, C.J. G., P. Garnier, Y.J. Kim, K.L. Oveson, T.S. Steenhuis, J.Y. Parlange, M. Jenkins, W.C. Ghiorse, and P. Baveye (2003), Preferential transport of Cryptosporidium parvum oocysts in variably saturated subsurface environments, Water Environ. Res., 75, 113-120. Beven, Keith and Germann, Peter. 2013. Macropores and water flow in soils revisited. Water Resources Research, 49(6), 3071-3092. DOI: 10.1002/wrcr.20156. Ruiz-Ramos, M., D. del Valle, D. Grinev, and A.M. Tarquis. 2009. Soil hydraulic behaviour at different bulk densities. Geophysical Research Abstracts, 11, EGU2009-6234.

  3. Influence of the soil-atmosphere exchange on the hydric profile induced in soil-structure system

    Directory of Open Access Journals (Sweden)

    A. Al Qadad

    2012-06-01

    Full Text Available Soil-atmosphere exchange leads to a moisture change in the soil. This can cause major damage to engineering structures due to the soil expansion and shrinkage. The soil-atmosphere exchange is related to several parameters, in particular the soil characteristics and climate conditions. The presence of an engineering structure causes a variation of the hydraulic profile in the soil, which can lead to heterogeneous soil movement and consequently to structural damage. This paper presents a coupled numerical model based on the consideration of both water flow in unsaturated soils and soil-atmosphere exchange. After the validation of the model, the paper presents its use for the analysis of the influence of the presence of structures on moisture change induced under climatic conditions recorded in a semi-arid region. Analysis shows that the presence of the structure leads to important change in the moisture distribution, in particular in the vicinity of the structure.

  4. A factor analysis to detect factors influencing building national brand

    Directory of Open Access Journals (Sweden)

    Naser Azad

    Full Text Available Developing a national brand is one of the most important issues for development of a brand. In this study, we present factor analysis to detect the most important factors in building a national brand. The proposed study uses factor analysis to extract the most influencing factors and the sample size has been chosen from two major auto makers in Iran called Iran Khodro and Saipa. The questionnaire was designed in Likert scale and distributed among 235 experts. Cronbach alpha is calculated as 84%, which is well above the minimum desirable limit of 0.70. The implementation of factor analysis provides six factors including “cultural image of customers”, “exciting characteristics”, “competitive pricing strategies”, “perception image” and “previous perceptions”.

  5. Influence of indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils: a rhizobox study.

    Science.gov (United States)

    Kim, Kwon-Rae; Owens, Gary; Kwon, Soon-lk

    2010-01-01

    This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils (two alkaline soils and two acidic soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic soils and only a slight increase (alkaline soils. Furthermore, the DOC concentration increased by 17-156 mg/L in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion chromatographic determination showed a marked increase in the total dissolved organic acids (OAs) in rhizosphere. While root exudates were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.

  6. Influence of soil properties and soil leaching on the toxicity of ionic silver to plants.

    Science.gov (United States)

    Langdon, Kate A; McLaughlin, Mike J; Kirby, Jason K; Merrington, Graham

    2015-11-01

    Silver (Ag) has been shown to exhibit antimicrobial properties; as a result, it is being used increasingly in a wide range of consumer products. With these uses, the likelihood that Ag may enter the environment has increased, predominately via land application of biosolids or irrigation with treated wastewater effluent. The aim of the present study was to investigate the toxicity of Ag to 2 plant species: barley (Hordeum vulgare L. CV Triumph) and tomato (Lycopersicum esculentum) in a range of soils under both leached and unleached conditions. The concentrations that resulted in a 50% reduction of plant growth (EC50) were found to vary up to 20-fold across the soils, indicating a large influence of soil type on Ag toxicity. Overall, barley root elongation was found to be the least sensitive to added Ag, with EC50 values ranging from 51 mg/kg to 1030 mg/kg, whereas the tomato plant height showed higher sensitivity with EC50 values ranging from 46 mg/kg to 486 mg/kg. The effect of leaching was more evident in the barley toxicity results, where higher concentrations of Ag were required to induce toxicity. Variations in soil organic carbon and pH were found to be primarily responsible for mitigating Ag toxicity; therefore, these properties may be used in future risk assessments for Ag to predict toxicity in a wide range of soil types.

  7. On factors influencing students’ listening abilities

    Institute of Scientific and Technical Information of China (English)

    胡天秀

    2012-01-01

    As we all know,listening,speaking,reading,and writing are four basic skills in language teaching and learning.Listening plays an important role in improving other skills.There are some factors influencing students’ listening abilities.So it’s important for teachers to improve students’ listening abilities.

  8. Factors Influencing High School Students' Career Aspirations

    Science.gov (United States)

    Tang, Mei; Pan, Wei; Newmeyer, Mark D.

    2008-01-01

    This article explores the factors influencing high school students' career aspirations with a study analyzing 141 high school students. The Social Cognitive Career Development Model was utilized to examine the interactive relationships among learning experiences, career self-efficacy, outcome expectations, career interests, and career choices. The…

  9. Factors influencing laser cutting of wood

    Science.gov (United States)

    V.G. Barnekov; C.W. McMillin; H.A. Huber

    1986-01-01

    Factors influencing the ability of lasers to cut wood may be generally classified into these three areas: 1) characteristics of the laser beam; 2) equipment and processing variables; and 3) properties of the workpiece. Effects of beam power, mode, polarization, and stability are discussed as are aspects of optics, location of focal point, feed speed, gas-jet assist...

  10. Factors influencing the process of farm liquidation

    Directory of Open Access Journals (Sweden)

    Michał Dudek

    2010-01-01

    Full Text Available In the paper the logit analysis was used in order to define the factors influencing farm liquidation. The prevalence of this phenomenon and its regional differences were analysed. Significant and negative impact of the number of people in a family farm and the number of machinery and technical equipment, as well as the positive impact of the farmer’ age are reported.

  11. Influences of Quinclorac on Culturable Microorganisms and Soil Respiration in Flooded Paddy Soil

    Institute of Scientific and Technical Information of China (English)

    ZHEN-MEI LU; HANG MIN; YANG-FANG YE

    2003-01-01

    Objective To investigate the potential effects of herbicide quinclorac (3,7-dichloro-8-quinoline-carboxylic) on the culturable microorganisms in flooded paddy soil. Methods Total soil aerobic bacteria, actinomycetes and fungi were counted by a 10-fold serial dilution plate technique. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN)methods with anaerobic liquid enrichment media. The number of methanogenic bacteria (MB) and nitrogen-fixing bacteria (NFB) was determined by the rolling tube method in triplicate. Soil respiration was monitored by a 102G-type gas chromatography with a stainless steel column filled with GDX-104 and a thermal conductivity detector. Results Quinclorac concentration was an important factor affecting the populations of various culturable microorganisms. There were some significant differences in the aerobic heterotrophic bacteria. AFB and DNB between soils were supplemented with quinclorac and non-quinclorac at the early stage of incubation, but none of them was persistent. The number of fungi and DNB was increased in soil samples treated by lower than1.33 μg·g-1 dried soil, while the CFU of fungi and HPAB was inhibited in soil samples treated by higher than 1.33 μg·g-1 dried soil. The population of actinomycete declined in negative proportion to the concentrations of quinclorac applied after 4 days. However, application of quinclorac greatly stimulated the growth of AFB and NFB. MB was more sensitive to quinclorac than the others, and the three soil samples with concentrations higher than 1 μg·g-1 dried soil declined significantly to less than 40% of that in the control, but the number of samples with lower concentrations of quinclorac was nearly equal to that in the control at the end of experiments. Conclusion Quinclorac is safe to the soil microorganisms when applied at normal

  12. Social Factors Influencing Child Health in Ghana.

    Directory of Open Access Journals (Sweden)

    Emmanuel Quansah

    Full Text Available Social factors have profound effects on health. Children are especially vulnerable to social influences, particularly in their early years. Adverse social exposures in childhood can lead to chronic disorders later in life. Here, we sought to identify and evaluate the impact of social factors on child health in Ghana. As Ghana is unlikely to achieve the Millennium Development Goals' target of reducing child mortality by two-thirds between 1990 and 2015, we deemed it necessary to identify social determinants that might have contributed to the non-realisation of this goal.ScienceDirect, PubMed, MEDLINE via EBSCO and Google Scholar were searched for published articles reporting on the influence of social factors on child health in Ghana. After screening the 98 articles identified, 34 of them that met our inclusion criteria were selected for qualitative review.Major social factors influencing child health in the country include maternal education, rural-urban disparities (place of residence, family income (wealth/poverty and high dependency (multiparousity. These factors are associated with child mortality, nutritional status of children, completion of immunisation programmes, health-seeking behaviour and hygiene practices.Several social factors influence child health outcomes in Ghana. Developing more effective responses to these social determinants would require sustainable efforts from all stakeholders including the Government, healthcare providers and families. We recommend the development of interventions that would support families through direct social support initiatives aimed at alleviating poverty and inequality, and indirect approaches targeted at eliminating the dependence of poor health outcomes on social factors. Importantly, the expansion of quality free education interventions to improve would-be-mother's health knowledge is emphasised.

  13. Does pH influence soil hydro-mechanical properties?

    Science.gov (United States)

    Chaplain, V.; Défossez, P.; Delarue, G.; Dexter, A. R.; Richard, G.; Tessier, D.

    2009-04-01

    Does pH influence soil hydro-mechanical properties ? V. Chaplain1, P. Défossez2, G. Delarue1, A.R. Dexter3, G. Richard3 and D. Tessier1. 1 UR INRA PESSAC RD 10, F-78026 Versailles cedex 2 UMR INRA/URCA FARE, 2 Esplanade Roland Garros, BP 224 F-51686 Reims cedex 2 3 UR INRA Sols 2163 Avenue de la Pomme de Pin - CS 40001 ARDON F-45075 Orléans Cedex 2 Corresponding author : chaplain@versailles.inra.fr Structure of soils and its dynamic, physico-chemistry of the interface are of a great importance in the fate of organic pollutants because it governs the accessibility of pollutants to micro-organisms. The soil structure of soils is related to physical parameters (texture, density, water content) but the physico-chemical properties of the interface is not considered. In this study we performed hydro-mechanical measurements on soil samples taken from the 42-plot long-term experiment in Versailles. Indeed six plots were selected to cover a large range of pH values from acid (3.5) to alkaline (8.2) due to the repeated application of fertilizers. Soils were taken in the 0-20 cm and in the 30-35 cm layer out of the ploughed zone. All soils had similar texture and composition with low organic carbon. Therefore pH changes the surface charges and hydrophobicity that are implied in aggregation process. The two layers had the same pH values. The precompression stress Pc and the compression index Cc were derived from confined compression tests performed on remoulded soil samples (density 1.45 g/cm3) at saturation. Results shows that the precompression stress increased at pH lower than 4. In acid case, precompression stress was higher in subsoil. This increase of Pc was attributed to the hydrophobicity due in part to the condensation of charges probably sensitive to the humectation/dessication processes.

  14. Influence of nonlinear sorption kinetics on the slow-desorbing organic contaminant fraction in soil

    NARCIS (Netherlands)

    Schlebaum, W.; Schraa, G.; Riemsdijk, van W.H.

    1999-01-01

    Release rates of hydrophobic organic compounds (HOCs) from the soil matrix influence the availability of HOCs in soils or sediments for microbial degradation or removal by physical means (e.g., soil washing or soil venting). In this study it was shown that the initial contaminant concentration influ

  15. Problem solving III: factors influencing classroom problem

    Directory of Open Access Journals (Sweden)

    Sayonara Salvador Cabral da Costa

    1997-05-01

    Full Text Available This paper presents a review of the literature in the area of problem solving, particularly in physics, focusing only on factors that influence classroom problem solving. Fifty-seven papers have been analyzed in terms of theoretical basis, investigated factors/methodology and findings/relevant factors, which were organized in a table that served as support for a synthesis made by the authors. It is the third of a four-paper series reviewing different aspects of the problem solving subject.

  16. Factors that influence women's dispositions toward science

    Science.gov (United States)

    Atria, Catherine Graczyk

    Females have been underrepresented in the study of science and science careers for decades although advancements have been made in closing this gender gap, the gap persists particularly in the physical sciences. Variables which influence a woman's desire to pursue and maintain a science course of study and career must be discovered. The United States lags behind other industrialized countries in the fields of science, math, and engineering. Females comprise an estimated half of the population; their potential contributions cannot be ignored or overlooked. This retrospective research study explores the personal experiences of ten women enrolled in science majors, with science related career plans. The goal of this study is to describe the factors that influence the participants' interest in science. The findings, the effect of science coursework, science teachers' personality and manner, other influential educational personnel, role models and mentors, external influences exclusive of school, parental influence, locus of control and positive attitudes toward science confirm what other researchers have found.

  17. Uncovering Factors Influencing Interpersonal Health Communication.

    Science.gov (United States)

    Donné, Lennie; Jansen, Carel; Hoeks, John

    2017-01-01

    Talking to friends, family, or peers about health issues might, among other things, increase knowledge of social norms and feelings of self-efficacy in adopting a healthier lifestyle. We often see interpersonal health communication as an important mediating factor in the effects of health campaigns on health behavior. No research has been done so far, however, on factors that influence whether and how people talk about health issues without being exposed to a health campaign first. In this exploratory study, we interviewed 12 participants about their communication behavior concerning six different health themes, like smoking and exercising. The results suggest that at least four types of interpersonal health communication can be distinguished, each influenced by different factors, like conversational partner and objective of the conversation. Future research should take this diversity of interpersonal health communication into account, and focus on designing health campaigns that aim to trigger dialogue within target populations.

  18. Theoretical difference between impact factor and influence factor

    Directory of Open Access Journals (Sweden)

    Đilda Pečarić

    2010-06-01

    Full Text Available Bibliometric constructions of "knowledge maps" and "cognitive structures of science" do not differentiate between impact and influence factors. The difference can be constructedaccording to different meaning and interpretation of the terms reference and citation. Reference is "acknowledgment which one author gives to another", whereas citation is "acknowledgment which one document receives from another". Development of Information Science according to period and subject area is analyzed on the corpus of citation literature retrieved from doctoral dissertations in Information Science from 1978 to 2007 at Croatian universities. The research aim is to indicate the difference between document impact factor and author's influence factor (i.e. reference ability to produce effects on actions, behavior, and opinions of authors of doctoral theses. The influence factor serves to distinguish the key role of cited authors in time and according to the duration of the influence (the average age for cited papers of dominant authors in different periods is between eight and ten years. The difference between linear and interactive communication seems vital for the interpretation of cited half-life, i.e. the attitude of one science community towards used information resources and cognitive heritage. The analyzed corpus of 22,210 citations can be divided into three communication phases according to influence factor criteria: in the phase of dialogue and interactive communication 25% of bibliographic units are cited in the first four years; in the second phase another 25% of units are cited from the fifth to the ninth year; after ten years, in the dominant linear communication phase, approximately 30% of units are cited.

  19. Susceptibility of volcanic ash-influenced soil in northern Idaho to mechanical compaction

    Science.gov (United States)

    Deborah S. Page-Dumroese

    1993-01-01

    Timber harvesting and mechanical site preparation can reduce site productivity if they excessively disturb or compact the soil. Volcanic ash-influenced soils with low undisturbed bulk densities and rock content are particularly susceptible. This study evaluates the effects of harvesting and site preparation on changes in the bulk density of ash-influenced forest soils...

  20. Influence of soil texture on the distribution and availability of {sup 238}U, {sup 230}Th, and {sup 226}Ra in soils

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Rodriguez, P. [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, Avd. Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Extremadura, Avd. Elvas s/n, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Lozano, J.C. [Laboratorio de Radiactividad Ambiental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Perez-Fernandez, M.A. [Area de Ecologia, Universidad Pablo Olavide, Carretera de Utrera km. 1, 41013 Sevilla (Spain)

    2008-08-15

    The influence of soil texture on the distribution and availability of {sup 238}U, {sup 230}Th, and {sup 226}Ra in soils was studied in soil samples collected at a rehabilitated uranium mine located in the Extremadura region in south-west Spain. The activity concentration (Bq kg{sup -1}) in the soils ranged from 60 to 750 for {sup 238}U, from 60 to 260 for {sup 230}Th, and from 70 to 330 for {sup 226}Ra. The radionuclide distribution was determined in three soil fractions: coarse sand (0.5-2 mm), medium-fine sand (0.067-0.5 mm), and silt and clay (<0.067 mm). The relative mobility of the natural radionuclides in the different fractions was studied by comparison of the activity ratios between radionuclides belonging to the same radioactive series. The lability of these radionuclides in each fraction was also studied through selective extraction from the soils using a one-step sequential extraction scheme. Significant correlations were found for {sup 238}U, {sup 230}Th, and {sup 226}Ra between the activity concentration per fraction and the total activity concentration in the bulk soil. Thus, from the determination of the activity concentration in the bulk soil, one could estimate the activity concentration in each fraction. Correlations were also found for {sup 238}U and {sup 226}Ra between the labile activity concentration in each fraction and the total activity concentration in bulk soil. Assuming that there is some particle-size fraction that predominates in the process of soil-to-plant transfer, the parameters obtained in this study should be used as correction factors for the transfer factors determined from the bulk soil in previous studies.

  1. An approach for modeling the influence of wheel tractor loads and vibration frequencies on soil compaction

    Science.gov (United States)

    Verotti, M.; Servadio, P.; Belfiore, N. P.; Bergonzoli, S.

    2012-04-01

    Both soil compaction and ground vibration are forms of environmental degradation that may be understood in the context of the vehicle-soil interaction process considered (Hildebrand et al., 2008). The transit of tractors on agricultural soil is often the main cause of soil compaction increasing. As known, this can be a serious problems for tillage and sowing and therefore the influence of all the affecting factors have been extensively studied in the last decades in order to understand their impact on the biosystem. There are factors related to the climate, namely to the rainfalls and temperature, and many others. Hence, it is not simple to figure out a complete model for predicting an index of compaction, for a given situation. Soil compaction models are important tools for controlling soil compaction due to agricultural field traffic and they are potentially useful technique to provide information concerning correct soil management. By means of such models, strategies and recommendations for prevention of soil compaction may be developed and specific advice may be given to farmers and advisers. In order to predict field wheeled and tracked vehicle performance, some empirical methods, used for off-road vehicle, were applied by Servadio (2010) on agricultural soil. The empirical indexes included, besides the soil strength, the load carried by the tire or track, some technical characteristics of the tire or track of the vehicle (tire or track width, tire or track wheel diameter, unloaded tire section height, number of wheel station in one track, tire deflection, total length of the belt track, the track pitch) as well as the vehicle passes. They have been validated with the tests results of agricultural vehicles over a range of soil in central Italy. Among the parameters which affect soil compaction, the water content of the soil, the axle load and number of vehicle passes proved to be the most important ones. The present paper concerns mainly vehicle-soil

  2. What Factors Influence Knowledge Sharing in Organizations?

    DEFF Research Database (Denmark)

    Razmerita, Liana; Kirchner, Kathrin; Nielsen, Pia

    2016-01-01

    Purpose: Enterprise social media platforms provide new ways of sharing knowledge and communicating within organizations to benefit from the social capital and valuable knowledge that employees have. Drawing on social dilemma and self-determination theory, the aim of the study is to understand what...... factors drive employees’ participation and what factors hamper their participation in enterprise social media. Design/methodology/approach: Based on a literature review, a unified research model is derived integrating demographic, individual, organizational and technological factors that influence...... knowledge sharing framework helps to understand what factors impact engagement on social media. Furthermore the article suggests different types of interventions to overcome the social dilemma of knowledge sharing. Originality/value: The study contributes to an understanding of factors leading...

  3. Investigating important factors influencing purchasing from chains

    Directory of Open Access Journals (Sweden)

    Naser Azad

    2012-04-01

    Full Text Available In this paper, we survey important factors, influencing customers to buy more from one of well known food market operating in capital city of Iran named Shahrvand. The survey studies the effects of six factors including customer's perception, persuasive factors, brand, customers' expectations, product's characteristics and special features of store on attracting more customers. We have distributed questionnaire among 196 customers who regularly visit stores and analyzed details of the data. The results indicate that customers' perception is the most important item, which includes eight components. Years of experience is the most important item in our survey followed by impact of color and working hours. Diversity of services is another factor, which plays the most important role followed by quality of services. Next, fidelity and brand are other most important factors and the name of store and risk are in lower degree of importance.

  4. Limiting Factors for Agricultural Production and Differentiation of Soil Management in Romania

    Science.gov (United States)

    Ioana Moraru, Paula; Rusu, Teodor; Bogdan, Ileana; Ioan Pop, Adrian; Pop, Horia

    2017-04-01

    Romania's land area is 23,839,100 ha; 0.16% of the world's surface. Worldwide, Romania is ranked #83 for areal extent, and it consitutes 4.81% of the Europe's surface (ranked #12). Romania has 14,856,800 ha of agricultural land which represents 62.3% of the total surface; 0.65 ha per capita. At the national level, 72.5% and 27.5% of soils in Romania can be broadly classed as very poor and good/very good, respectively, based on intrinsic soil characteristics, climate, topography, and ground water. Romania has a specific geographical situation, namely: i) Romanian territory is located in the southeast portion of Central Europe at the cross roads of several high and low pressure centers that form regularly at the borders. The influence of these air masses is altered by the presence in the central regions of the Carpathian mountain chain resulting in a diverse climate with average annual rain fall amounts between 350 to 1,400 mm and average annual temperatures between 2 and 11.5°C. ii) At the national level, almost all soils in the international classification system are present in Romania; each soil type having specific properties and characteristics. iii) On approximately 12.5 million ha (7.5 million ha arable), soil fertility is adversely affected by erosion, acidity, low humus content, extreme texture (clay, sand), excessive moisture, chemical pollution etc. These natural and anthropogenic factors dramatically influence agricultural production. Furthermore, soil, climate, topography, etc. vary widely not only across the country, but also on smaller scales, even across fields within the same farm. In Steppe zone limitative climatic factors, which require differentiation towards soil management use, include: long periods of drought, high temperatures, high frequency winds (wind erosion in area of sands), low relative air humidity, and harsh frosts during winter. Negative phenomena most commonly encountered in this area are salinization, excess water, temporary

  5. Influence of soil moisture-carbon cycle interactions on the terrestrial carbon cycle over Europe

    Science.gov (United States)

    Mystakidis, Stefanos; Davin, Edouard L.; Gruber, Nicolas; Seneviratne, Sonia I.

    2016-04-01

    Water availability is a crucial limiting factor for terrestrial ecosystems, but relatively few studies have quantitatively assessed the influence of soil moisture variability on the terrestrial carbon cycle. Here, we investigate the role of soil moisture variability and state in the contemporary terrestrial carbon cycle over Europe. For this we use a Regional Earth System Model (RESM) based on the COSMO-CLM Regional Climate Model, coupled to the Community Land Model version 4.0 (CLM4.0) and its carbon-nitrogen module. The simulation setup consists of a control simulation over the period 1979-2010 in which soil moisture is interactive and three sensitivity simulations in which soil moisture is prescribed to a mean, a very dry or a very wet seasonal cycle without inter-annual variability. The cumulative net biome productivity varies markedly between the different experiments ranging from a strong sink of up to 6PgC in the wet experiment to a source of up to 1.2PgC in the dry experiment. Changes in the land carbon uptake are driven by a combination of two factors: the direct impact of soil moisture on plant's carbon uptake (essentially in southern Europe) and an indirect effect through changes in temperature affecting ecosystem respiration (mainly in central and northern Europe). We find that removing temporal variations in soil moisture dampens interannual variations in terrestrial carbon fluxes (Gross Primary Productivity, respiration, Net Biome Productivity) by more than 50% over most of Europe. Moreover, the analysis reveals that on annual scale about two-thirds of central Europe and about 70% of southern Europe display statistically significant effect of drying and/or wetting on the terrestrial carbon budget and its components. Our findings confirm the crucial role of soil moisture in determining the magnitude and the inter-annual variability in land CO2 uptake which is a key contributor to the year-to-year variations in atmospheric CO2 concentration.

  6. Influence of soil parameters on the linearity of the soil-to-plant transfer process of {sup 238}U and {sup 226}Ra

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Rodriguez, P.; Vera Tome, F. [Natural Radioactivity Group. Universidad de Extremadura, 06071 Badajoz (Spain); Lozano, J.C. [Laboratorio de Radiactividad Ambiental. Universidad de Salamanca, 37008 Salamanca (Spain)

    2014-07-01

    Transfer from soil to plant is an important input of radionuclides into the food chain. Also, the mobility of radionuclides in soils is enhanced through their passage into the plant compartment. Thus, the soil-to-plant transfer of radionuclides raises the potential human dose. In radiological risk assessment models, this process is usually considered to be an equilibrium process such that the activity concentration in plants is linearly related to the soil concentration through a constant transfer factor (TF). However, the large variability present by measured TF values leads to major uncertainties in the assessment of risks. One possible way to reduce this variability in TF values is to parametrize their determination. This paper presents correlations of TF with the major element concentrations in soils. The findings confirm the major influence of the chemical environment of a soil on the assimilation process. The variability of TF might be greatly reduced if only the labile fraction were considered. Experiments performed with plants (Helianthus annuus L.) growing in a hydroponic medium appear to confirm this suggestion, showing a linear correlation between the plant and the soil solution activity concentrations. Extracting the labile fraction of a real soil is no trivial task, however. A possible operationally definable method is to consider the water-soluble together with the exchangeable fractions of the soil. Studies performed in granitic soils showed that the labile concentration of uranium and radium strongly depended on the soil's textural characteristics. In this sense, a parametrization is proposed of the labile uranium and radium concentration as a function of the soil's granulometric parameters. (authors)

  7. Biological soil crusts in subtropical China and their influence on initial soil erosion

    Science.gov (United States)

    Seitz, Steffen; Goebes, Philipp; Kühn, Peter; Scholten, Thomas

    2014-05-01

    Soil is one of the most valuable resources we have on our planet. The erosion of this resource is a major environmental problem, in particular in subtropical China where high rainfall intensity causes severe and continuous soil losses. One of the main mechanisms controlling soil erosion is surface coverage, typically by vegetation, litter, stones and biological soil crusts (BSCs). BSCs play significant functional roles in soil systems, such as accelerating soil formation, changing water and nutrient cycling rates, enhancing soil stability and thus preventing erosion by wind or water. In initial ecosystems, cyanobacteria, algae, fungi, mosses and lichens are the first organisms to colonize the substrate; they form a biological crust within the first millimetres of the surface. BSCs and their effect on erosion are rarely mentioned in literature and most of the work done focussed on arid and semi-arid environments. This study aims to investigate the role of BSCs controlling the amount of runoff generated and sediment detached during soil erosion events in an initial ecosystem in subtropical China. The study took place on a deforested experimental site (BEF China) near Xingangshan, Jiangxi Province, PR China. We used a total number of 350 runoff plots (ROP, 40cmx40cm) to measure sediment discharge and surface runoff. BSC cover in each ROP was determined photogrammetrically in 4 time steps (autumn 2011, spring 2012, summer 2012 and summer 2013). Perpendicular images were taken and then processed to measure the coverage of BSCs using a 1 cm² digital grid overlay. Additionally BSCs were sampled in the field and identified by their taxonomy. In our ROPs we found 65 different moos, algae and lichen species, as well as cyanobacteria's. Mean BSC cover per ROP in 2013 was 17 % with a maximum of 62 % and a minimum of 0 %. Compared to stone cover with 3 %, our findings highlight the role of BSC in soil erosion processes. The total BSC covered area is slightly decreasing since

  8. Influence of organizational factors on safety

    Energy Technology Data Exchange (ETDEWEB)

    Haber, S.B.; Metlay, D.S.; Crouch, D.A.

    1990-01-01

    There is a need for a better understanding of exactly how organizational management factors at a nuclear power plant (NPP) affect plant safety performance, either directly or indirectly, and how these factors might be observed, measured, and evaluated. The purpose of this research project is to respond to that need by developing a general methodology for characterizing these organizational and management factors, systematically collecting information on their status and integrating that information into various types of evaluative activities. Research to date has included the development of the Nuclear Organization and Management Analysis Concept (NOMAC) of a NPP, the identification of key organizational and management factors, and the identification of the methods for systematically measuring and analyzing the influence of these factors on performance. Most recently, two field studies, one at a fossil fuel plant and the other at a NPP, were conducted using the developed methodology. Results are presented from both studies highlighting the acceptability, practicality, and usefulness of the methods used to assess the influence of various organizational and management factors including culture, communication, decision-making, standardization, and oversight. 6 refs., 3 figs., 1 tab.

  9. Factors Influencing Colorectal Cancer Screening Participation

    Directory of Open Access Journals (Sweden)

    Antonio Z. Gimeno García

    2012-01-01

    Full Text Available Colorectal cancer (CRC is a major health problem worldwide. Although population-based CRC screening is strongly recommended in average-risk population, compliance rates are still far from the desirable rates. High levels of screening uptake are necessary for the success of any screening program. Therefore, the investigation of factors influencing participation is crucial prior to design and launches a population-based organized screening campaign. Several studies have identified screening behaviour factors related to potential participants, providers, or health care system. These influencing factors can also be classified in non-modifiable (i.e., demographic factors, education, health insurance, or income and modifiable factors (i.e., knowledge about CRC and screening, patient and provider attitudes or structural barriers for screening. Modifiable determinants are of great interest as they are plausible targets for interventions. Interventions at different levels (patient, providers or health care system have been tested across the studies with different results. This paper analyzes factors related to CRC screening behaviour and potential interventions designed to improve screening uptake.

  10. Transfer factors of polonium from soil to parsley and mint.

    Science.gov (United States)

    Al-Masri, M S; Al-Hamwi, A; Eadan, Z; Amin, Y

    2010-12-01

    Transfer factors of (210)Po from soil to parsley and mint have been determined. Artificial polonium isotope ((208)Po) was used as a tracer to determine transfer factor of Po from soil to plant in pot experiments. Two plant growing systems were used for this study namely, an outdoor system and a sheltered system by a polyethylene tent. (208)Po and (210)Po were determined in soil and different parts of the studied plants (stem and leaf), using alpha spectroscopy. The results have shown that there was a clear uptake of (208)Po by roots to leaves and stems of both plants. Higher values of transfer factors using the (210)Po activity concentrations than the (208)Po activity concentration were observed. Transfer factors of (210)Po from soil to parsley varied between 20 × 10⁻² and 50 × 10⁻² and 22 × 10⁻³ and 67 × 10⁻³ in mint, while (208)Po transfer factors varied between 4 × 10⁻² and 12 × 10⁻² for parsley and 10 × 10⁻² and 22 × 10⁻² in mint. Transfer factors of Po were higher in those plants grown in the sheltered system than in the open system; about 75% of Po was transferred from atmosphere to parsley parts using the two systems. Ratios of transferred Po from soil to mint stem and leaf in the sheltered system were higher by 2 times from those in the open system. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Seasonal abundance of soil arthropods in relation to meteorological and edaphic factors in the agroecosystems of Faisalabad, Punjab, Pakistan.

    Science.gov (United States)

    Shakir, Muhammad Mussadiq; Ahmed, Sohail

    2015-05-01

    Soil arthropods are an important component of agroecosystems, contributing significantly to their biodiversity and functioning. However, seasonal patterns, population dynamics, and significant roles of these soil arthropods in improvement of soil structures and functions are influenced by many factors. The objective of the current study was to investigate soil arthropod abundance in relation to a blend of meteorological and edaphic factors and to find out the difference in abundance among various crops (sugarcane, cotton, wheat, alfalfa fodder, and citrus orchards). The arthropod sampling was done by pitfall traps and Tullgren extractions on fortnightly intervals. Soil temperature and relative humidity were noted on the field sites while analysis for soil pH, organic matter, and soil moisture contents were done in the laboratory. The rainfall data was obtained from an observatory. Results showed that significant differences were found in soil arthropod abundance across different sampling months and crops. Out of total 13,673 soil arthropods sampled, 38 % belonged to Collembola, followed by 15 % Hymenoptera, 15 % Acarina, 11 % Myriapods, 6 % Coleoptera, 5 % Orthoptera, and 5 % Araneae. Mean abundance per sample was highest in summer months as compared to winter. Overall abundance per sample was significantly different between all crops (p soil arthropods according to abundance, i.e., highly abundant (Collembola, Acarina, Myripoda, Hymenoptera), moderately abundant (Orthoptera, Aranae, Coleoptera), least abundant (Dermaptera, Hemiptera, Diptera), and rare (Blattaria, Isoptera, Diplura, Lepidoptera). Soil temperature and soil organic matter showed significant positive correlation with abundance, while relative humidity was significantly negatively correlated. Soil moisture and soil pH showed no significant correlations while no correlation was found with total rainfall. PCA analysis revealed that soil surface arthropods were the major contributors of variation in

  12. Interspecific Relationships Among Soil Invertebrates Influence Pollutant Effects of Phenanthrene

    DEFF Research Database (Denmark)

    Cortet, J.; Joffre, R.; Elmholt, S.

    2006-01-01

    exerted an effect on mesofauna and that the effects on some species, like Folsomia fimetaria, were influenced by the species composition in the mesocosms, the soil layer, and the sampling date. However, the effects of phenanthrene on ergosterol content and organic matter decomposition were......Five mesofauna communities varying in both structure and composition were exposed to phenanthrene in mesocosms for up to four months. Effects of phenanthrene were assessed on mesofauna population dynamics, fungal biomass (ergosterol concentrations), and litter decomposition (litter mass loss...

  13. Influence of plant roots on electrical resistivity measurements of cultivated soil columns

    Science.gov (United States)

    Maloteau, Sophie; Blanchy, Guillaume; Javaux, Mathieu; Garré, Sarah

    2016-04-01

    Electrical resistivity methods have been widely used for the last 40 years in many fields: groundwater investigation, soil and water pollution, engineering application for subsurface surveys, etc. Many factors can influence the electrical resistivity of a media, and thus influence the ERT measurements. Among those factors, it is known that plant roots affect bulk electrical resistivity. However, this impact is not yet well understood. The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil column. For this research, it is assumed that roots system affect the electrical properties of the rhizosphere. Indeed the root activity (by transporting ions, releasing exudates, changing the soil structure,…) will modify the rhizosphere electrical conductivity (Lobet G. et al, 2013). This experiment is included in a bigger research project about the influence of roots system on geophysics measurements. Measurements are made on cylinders of 45 cm high and a diameter of 20 cm, filled with saturated loam on which seeds of Brachypodium distachyon (L.) Beauv. are sowed. Columns are equipped with electrodes, TDR probes and temperature sensors. Experiments are conducted at Gembloux Agro-Bio Tech, in a growing chamber with controlled conditions: temperature of the air is fixed to 20° C, photoperiod is equal to 14 hours, photosynthetically active radiation is equal to 200 μmol m-2s-1, and air relative humidity is fixed to 80 %. Columns are fully saturated the first day of the measurements duration then no more irrigation is done till the end of the experiment. The poster will report the first results analysis of the electrical resistivity distribution in the soil columns through space and time. These results will be discussed according to the plant development and other controlled factors. Water content of the soil will also be detailed

  14. Influence of pH on wetting kinetics of a pine forest soil

    Science.gov (United States)

    Amer, Ahmad; Schaumann, Gabriele; Diehl, Dörte

    2014-05-01

    Water repellent properties of organic matter significantly alter soil water dynamics. Various environmental factors control appearance and breakup of repellency in soil. Beside water content and temperature also pH exerts an influence on soil water repellency although investigations achieved partly ambiguous results; some found increasing repellency with increasing pH (Terashima et al. 2004; Duval et al. 2005), other with decreasing pH (Karnok et al. 1993; Roper 2005) and some found repellency maxima at intermediate pH and an increase with decreasing and with increasing pH (Bayer and Schaumann 2007; Diehl et al. 2010). The breakup of repellency may be observed via the time dependent sessile drop contact angle (TISED). With water contact time, soil-water contact angle decreases until complete wetting is reached. Diehl and Schaumann (2007) calculated the activation energy of the wetting process from the rate of sessile drop wetting obtained at different temperatures and draw conclusions on chemical or physical nature of repellency. The present study aims at the influence of pH on the wetting kinetics of soil. Therefore, TISED of soil was determined as a function of pH and temperature. We used upper soil samples (0 - 10 cm) from a pine forest in the southwest of Germany (Rheinland-Pfalz). Samples were air-dried, sieved Contact Angle Meter (Dataphysics, Germany) on three replications for each soil sample. Apparent work of adhesion was calculated, plotted vs. time and mathematically fitted using double exponential function. Rate constants of wetting were used to determine the activation energy by Arrhenius equation. First results indicated that despite comparable initial contact angles, pH alteration strongly changed the wetting rate suggesting maximum wetting resistance at the natural pH of 4.3 and decreasing wetting resistance at lower and at higher pH. The poster will present further current results of the ongoing study and discuss the activation energy of the

  15. Factors influencing the feasibility of laparoscopy colectomy

    Institute of Scientific and Technical Information of China (English)

    He Zhiyun; Zhang Zhongtao

    2014-01-01

    Objective The objective was to review the factors affecting the feasibility of performing successful laparoscopic colectomy.Data sources The literatures about the risk factors closely related to the ability to perform laparoscopic colectomy on different surgical diseases of the colon cited in this review were obtained from PubMed published in English from 2006 to 2012.Study selection Original articles regarding the risk factors that affect the ability to perform laparoscopic colectomy were selected.Results Obesity,diabetes,inflammatory bowel diseases,advanced age,emergency operation,and pelvic anatomy are all important risk factors that increase the risk of developing serious complications such as hemorrhage,anastomotic leak,and skin and soft tissue infections following laparoscopic colectomy.These factors also increase the likelihood of conversion to an open operation.In this study,we reviewed the recent original articles about the relationship of laparoscopic colectomy with these risk factors.We also describe some strategies that limit the likelihood of these complications and the likelihood of conversion to an open operation.Conclusions Obesity,diabetes,inflammatory bowel diseases,age,emergency operation,and pelvic anatomy are all important risk factors that increase the risk of either serious complications or conversion to open operation with laparoscopic colectomy.Evaluation of these risk factors preoperatively should influence the decision to perform colectomy using laparoscopic techniques.

  16. INFLUENCE OF NPK AND LIME APLICATION ON ERVA-MATE GROWTH, ROOT-ROT SEVERITY AND SOIL FUNGI POPULATION1

    Directory of Open Access Journals (Sweden)

    Igor Poletto

    2011-09-01

    Full Text Available The present work evaluated the influence of the application of NPK and liming doses in the soil, on the growth of Erva-mate, the severity of rot-root and the fungi population of the soil. To do so, an experiment was installed at the green house, in the Forest Nursery of UFSM, using an experimental design completely randomized factorial 4x3x4 (Factor F: Fusarium spp. inoculation; Factor C: soil limestone; Factor A: NPK doses , totaling 48 treatments. The seedlings were cultivated in vases containing 2 kg of soil, classified as ‘Red-Yellow Argisoil’ (clay soil. At the end of the experiment was measured the stem diameter, height of the aerial part, leaves number, aerial dry biomass, root dry biomass and total dry biomass of the seedlings. Also, the soil was collected, from each treatment, for the chemical analysis and the counting of the fungi population. It was observed that the association among application of NPK and liming in the soil hampered the development of Erva-mate seedlings. The analysis of some variables suggests that the limestone absence provided greater resistance of seedlings to the attack of Fusarium spp. or the severity of Fusarium spp. was reduced in lower pH. The fungi population of the soil presented varied behavior depending on the applied treatments.

  17. Factors Influencing Tacit Knowledge in Construction

    Directory of Open Access Journals (Sweden)

    Jawahar Nesan

    2012-11-01

    Full Text Available Increased complexity of the construction business and consequentuse of new management concepts and technologies ledconstruction organisations to focus more on the transfer of explicitknowledge. However, it is the tacit knowledge that determinesthe construction companies’ competitiveness in a business thatis driven by turbulent market conditions and customers’ everincreasingdemands. This paper highlights the importance of tacitknowledge sharing in construction, explores the challenges andopportunities to efficiently share tacit knowledge, and based on theliterature review identifies some critical factors that influence tacitknowledge in construction. It is argued that employees’ knowledgesharing (learning behaviours are influenced by work practices thatare borne by respective organisational behaviours. Organisational,cultural, and project characteristics that facilitate knowledgesharing among construction employees are explored and thepractices that influence the construction employee behaviour insharing tacit knowledge are highlighted.

  18. Factors Influencing Tacit Knowledge in Construction

    Directory of Open Access Journals (Sweden)

    Jawahar Nesan

    2012-11-01

    Full Text Available Increased complexity of the construction business and consequentuse of new management concepts and technologies ledconstruction organisations to focus more on the transfer of explicitknowledge. However, it is the tacit knowledge that determinesthe construction companies’ competitiveness in a business thatis driven by turbulent market conditions and customers’ everincreasingdemands. This paper highlights the importance of tacitknowledge sharing in construction, explores the challenges andopportunities to efficiently share tacit knowledge, and based on theliterature review identifies some critical factors that influence tacitknowledge in construction. It is argued that employees’ knowledgesharing (learning behaviours are influenced by work practices thatare borne by respective organisational behaviours. Organisational,cultural, and project characteristics that facilitate knowledgesharing among construction employees are explored and thepractices that influence the construction employee behaviour insharing tacit knowledge are highlighted.

  19. Influence of relief and vegetation on soil properties in a disturbed chernozem soil landscape

    Science.gov (United States)

    Raab, Thomas; Hirsch, Florian; Vasserman, Oleksandr; Raab, Alexandra; Naeth, Anne

    2017-04-01

    In central and southeastern Alberta, chernozems dominate the soil landscape and are divided into several groups that follow the climate gradient from Northwest to Southeast: Dark Grey Chernozems, Black Chernozems, Dark Brown Chernozems; Brown Chernozems. Principles controlling development and distribution of these chernozem subtypes along the ecotone transect are quite well known. However, intensive land use over the last century has affected soils that originally have formed under natural conditions during the Holocene in more than 10,000 years. There is a lack of knowledge regarding soil development in these landscapes on the decadal to centennial time scale. Within this time frame the most important factor of soil formation may be relief, although this has not been properly studied. This study aims to compare soil properties in a typical chernozem landscape where soils have been highly disturbed and parent materials have been re-arranged by surface coal mining. We hypothesize that within 50 years, soils develop with significant differences based on vegetation type and slope aspect. Our study site is the former Diplomat Mine near Forestburg, Alberta where spoils form a small scale ridge and graben topography. The south facing slopes of the piles are covered by grassland, whereas on the north exposition has trees and shrubs. Samples were taken from six sites with differences in topography and vegetation type. Diplomate T1 is at the top of the ridge with grassland, Diplomate S1 is on the southern slope with grassland, Diplomate N1 is on the northern slope with trees, and Diplomate N2 is on the northern slope with shrubs. For comparison we took samples from two sites without slope aspect. One site was an undisturbed grassland (Diplomate Z1) and the other sites were reclaimed piles (Diplomate R1). At each site, five soil profiles were examined and volumetrically sampled (250 cm3 steel ring) in steps of five centimeters to a depth of 30 centimeters. We present first

  20. Microencapsulation techniques, factors influencing encapsulation efficiency.

    Science.gov (United States)

    Jyothi, N Venkata Naga; Prasanna, P Muthu; Sakarkar, Suhas Narayan; Prabha, K Surya; Ramaiah, P Seetha; Srawan, G Y

    2010-05-01

    Microencapsulation is one of the quality preservation techniques of sensitive substances and a method for production of materials with new valuable properties. Microencapsulation is a process of enclosing micron-sized particles in a polymeric shell. There are different techniques available for the encapsulation of drug entities. The encapsulation efficiency of the microparticle or microsphere or microcapsule depends upon different factors like concentration of the polymer, solubility of polymer in solvent, rate of solvent removal, solubility of organic solvent in water, etc. The present article provides a literature review of different microencapsulation techniques and different factors influencing the encapsulation efficiency of the microencapsulation technique.

  1. Factors Influencing Consumer Behavior of Smartphone Users

    OpenAIRE

    Nagarkoti, Bishal

    2014-01-01

    The aim of the study is to know about the factors influencing consumer behavior of Smartphone users. Under this study, the main focus is to identify whether Smartphone users buy Smartphone because of their need or wish, reasons to buy expensive smart phones, how social and personal factors affect them to make purchasing decision, for what purposes they use Smartphone, where and how long a day, change in usage of com-puters due to Smartphone and how high is the phone bill after using Smartphon...

  2. FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION

    Institute of Scientific and Technical Information of China (English)

    WU Long-hua; YANG Xiao-li

    2011-01-01

    The bending rigidity of submerged vegetation is closely related with vegetative drag force.This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation.Based on the dimensional analysis method,the factors influencing the bending rigidity of individual submerged vegetation were analyzed.The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation,and a relative bending rigidity expression for submerged vegetation was obtained by means of multiple linear regression method.The results show that the submerged vegetation has three states under different inflow conditions,and the each critical relative bending rigidity of individual submerged vegetation was determined for the different states of submerged vegetation.

  3. Investigating different factors influencing on brand equity

    Directory of Open Access Journals (Sweden)

    Afsane Zamanimoghadam

    2014-07-01

    Full Text Available The purpose of this paper is to determine and prioritize factors influencing on brand equity in consumer’s point of view for a case study of Samsung appliance consumers in city of Tehran, Iran. The study investigates the effects of four factors in terms of the customer's perspective, price, advertisement, family and brand image, by dimensions of brand equity, perceived quality, brand awareness, brand association, brand loyalty, on brand equity. The research method is based on a descriptive-survey research. The questionnaire includes Samsung consumers in city of Tehran, Iran. To test the hypotheses, SPSS and LISREL software packages are used. For data analysis, descriptive statistics and inferential statistical tests including structural equation modeling and path analysis are used. The results of the survey have indicated that family and brand image influence positively on brand equity but the effects of advertisement and price on brand equity were not confirmed.

  4. [Effects and influence factors of dicyandiamide (DCD) application in agricultural ecosystem].

    Science.gov (United States)

    Dai, Yu; He, Ji-Zheng; Shen, Ju-Pei

    2014-01-01

    The low utilization efficiency of nitrogen fertilizer in agricultural ecosystem has caused serious economic and environmental issues. Dicyandiamide (DCD) is a widely used nitrification inhibitor, which can inhibit nitrification via affecting ammonia oxidizing microorganisms with minimal influence on other soil microorganisms, thereby reducing the leaching of nitrate and emission of greenhouse gases. The factors influencing the efficiency of DCD in soil include soil temperature, pH, texture, organic matter, moisture, etc. Recently, the application of molecular methods in agricultural systems has shed new light on the microbial mechanism underlying nitrification inhibition by DCD. In this review, the enzymatic inhibition mechanism, the application effects and their influence factors of DCD were summarized, and the prospects of its application were discussed as well.

  5. Factors Influencing Impulse Buying in Retail Stores

    OpenAIRE

    Giorgadze, Nino

    2014-01-01

    Impulse buying is a widely pervasive phenomenon. Statistics shows that more and more shoppers are experiencing irresistible urge to purchase unplanned and in most cases unnecessary product. Existing researches fall short in identifying most suitable tools that marketers can adopt in order to promote impulsive sales. Therefore, this thesis provides deep analysis of those, controllable factors that influence impulse buying. Particularly four external cues are examined: product display, promotio...

  6. Major Factors influences the 2008 Stock Market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ 2007 was an unusual year for China's stock market, as the index climbed from 2675 points up to 6124 by the end of the year, setting new records again and again throughout 2007. What will happen to the stock market in the coming 2008? Let's havea look at some of the main factors that will influence the stock market this year, perhaps we can find out if 2008 will be another memorable year full of surprises.

  7. Soil parameters are key factors to predict metal bioavailability to snails based on chemical extractant data

    Energy Technology Data Exchange (ETDEWEB)

    Pauget, B.; Gimbert, F., E-mail: frederic.gimbert@univ-fcomte.fr; Scheifler, R.; Coeurdassier, M.; Vaufleury, A. de

    2012-08-01

    Although soil characteristics modulate metal mobility and bioavailability to organisms, they are often ignored in the risk assessment of metal transfer. This paper aims to determine the ability of chemical methods to assess and predict cadmium (Cd), lead (Pb) and zinc (Zn) environmental bioavailability to the land snail Cantareus aspersus. Snails were exposed in the laboratory for 28 days to 17 soils from around a former smelter. The soils were selected for their range of pH, organic matter, clay content, and Cd, Pb and Zn concentrations. The influence of soil properties on environmental availability (estimated using HF-HClO{sub 4}, EDTA, CaCl{sub 2}, NH{sub 4}NO{sub 3}, NaNO{sub 3}, free ion activity and total dissolved metal concentration in soil solution) and on environmental bioavailability (modelled using accumulation kinetics) was identified. Among the seven chemical methods, only the EDTA and the total soil concentration can be used to assess Cd and Pb environmental bioavailability to snails (r Superscript-Two {sub adj} = 0.67 and 0.77, respectively). For Zn, none of the chemical methods were suitable. Taking into account the influence of the soil characteristics (pH and CEC) allows a better prediction of Cd and Pb environmental bioavailability (r Superscript-Two {sub adj} = 0.82 and 0.83, respectively). Even though alone none of the chemical methods tested could assess Zn environmental bioavailability to snails, the addition of pH, iron and aluminium oxides allowed the variation of assimilation fluxes to be predicted. A conceptual and practical method to use soil characteristics for risk assessment is proposed based on these results. We conclude that as yet there is no universal chemical method to predict metal environmental bioavailability to snails, and that the soil factors having the greatest impact depend on the metal considered. - Highlights: Black-Right-Pointing-Pointer New approach to identify chemical methods able to predict metal bioavailability

  8. CONSIDERATIONS REGARDING THE INFLUENCE OF METALIC IONS OF THE STABILITY OF CARBONATES FROM SOILS

    Directory of Open Access Journals (Sweden)

    D. Bulgariu

    2005-10-01

    Full Text Available The distribution of minor elements in heterogeneous mineral / aqueous solutions systems represent one of important problem, with many applications in environmental geochemistry field. Ours studies was focus on the metal ions distribution in carbonate (CaCO3 / solution systems, from applicability point of view to the estimation of formation conditions and of carbonates stability from soils. On the base of our results obtained by sequential solid / liquid extraction for 17 soil samples and theoretical modeling of CaCO3 / solution systems, and the results from literature we try to develop the McIntire prognosis models and the free Gibbs enthalpy linear correlation model, by the inclusion in calculus relations of distribution coefficients a higher number of factors which effective influenced the thermodynamics and kinetics of interphase distribution processes of metal ions. The established correlations has been used to the estimation of time evolution of carbonate / solution equilibrium under the influence of some metal ions (Cd, Zn, Cu, Pb, Bi, which appear usual as pollutants in soils. The prognosis realized on the base of the established correlations are in agreement with the theoretical modelling results and studies of case for different types of polluted soils with heavy metals.

  9. Factors influencing the eicosanoids synthesis in vivo.

    Science.gov (United States)

    Szefel, Jarosław; Kruszewski, Wiesław Janusz; Sobczak, Ewa

    2015-01-01

    External factors activate a sequence of reactions involving the reception, transduction, and transmission of signals to effector cells. There are two main phases of the body's reaction to harmful factors: the first aims to neutralize the harmful factor, while in the second the inflammatory process is reduced in size and resolved. Secondary messengers such as eicosanoids are active in both phases. The discovery of lipoxins and epi-lipoxins demonstrated that not all arachidonic acid (AA) derivatives have proinflammatory activity. It was also revealed that metabolites of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) such as resolvins, protectins, and maresins also take part in the resolution of inflammation. Knowledge of the above properties has stimulated several clinical trials on the influence of EPA and DHA supplementation on various diseases. However, the equivocal results of those trials prevent the formulation of guidelines on EPA and DHA supplementation. Prescription drugs are among the substances with the strongest influence on the profile and quantity of the synthesized eicosanoids. The lack of knowledge about their influence on the conversion of EPA and DHA into eicosanoids may lead to erroneous conclusions from clinical trials.

  10. Factors affecting potassium fixation in seven soils under 15-year long-term fertilization

    Institute of Scientific and Technical Information of China (English)

    ZHANG HuiMin; XU MingGang; ZHANG WenJu; HE XinHua

    2009-01-01

    Potassium (K) fixation by seven soils, including black soil, fluvo-aquic soil, grey desert soil, loess soil, paddy soil, red soil and purple soil, was determined by laboratory simulation under a fifteen-year-pe-riod of long-term fertilization. Factors affecting soil K fixation were then discussed by factor analysis and stepwise regression. Magnitude of soil K fixation rate was as follows: the black soil > the purple soil > the loess soil > the fluvo-aquic soil > the paddy soil > the grey desert soil > the red soil. Our re-sulta showed that soil K fixation capacity was significantly affected by the clay mineral types in the soils. Potassium fixation capacity of soils, whose 2:1 layer silicates were dominant minerals, was af-fected by two components extracted by the method of principal component analysis: the first including soil available K, slow available K and K+ saturation, and the second including cation exchange capacity (CEC), soil organic matter (SOM) and <0.002 mm clay contents. Potassium fixation rate was mainly af-fected by K+ saturation and CEC with lower added K concentration (from 0.4 to 1.6 g/L), and by K+ saturation and <0.002 mm clay content with higher added K concentration (from 2.4 to 4.0 g/L).

  11. A Review of Factors Influencing Health Inequalities

    Directory of Open Access Journals (Sweden)

    Hassan Almaspoor Khanghah

    2016-01-01

    Full Text Available ​Background and Objectives : Inequity in health is a universal term which is used for showing current differences, variations and inequalities of people in accessing to health services. The current study aimed to assess the factors influencing health inequalities to present the results to the researchers and health care professionals. Material and Methods : In this review, several databases including PubMed, Proquest, Scopus, Google Scholar search engine, SID and IranDoc were searched within 2000-2014 period. We found 746 articles and refined them step by step according to the aim of the study by reviewing the titles, abstracts and full texts. Finally, 16 articles were selected for further study Results: In the present study, identified determinants in health inequalities were as follows: 1- Economic and income factors 2- Political factors, social and public policy 3- Cultural and social values 4- social and demographic factors 5- Behavioral, psychological and biological factors. Although, other factors like governmental, international, social cohesion, incidents and even the health system itself were involved in health inequalities, but the listed determinants were among the most important determinants in health inequalities in the conducted studies. Conclusion : Given the importance of people's health and inequalities in health, the approach should focus on reducing the inequalities in all policies and development programs and the role of these factors should be taken into consideration by managers and policy-makers

  12. 非生物因子对松嫩平原西部石油污染湿草甸土壤微生物的影响%The Influence of Abiotic Factors on Soil Microorganism in Wet Meadows Contaminated by Petroleum in the West Songnen Plain

    Institute of Scientific and Technical Information of China (English)

    初金美; 李秀军; 刘兴土; 赵鹏飞; 王铭

    2012-01-01

    (5 603 mg/kg) occurred in surface soil of the third producing well of petroleum chosen in Li-angjiazi town of Da'an city, and the highests of both microbial population and carbon metabolism activity occurred also in the same place. Those results in the study suggested that the petroleum hydrocarbons promoted soil microorganisms growth in the wet meadows, increased the microbial community metabolic activity and improved the ability of using carbon source. In addition, the influence of other abiotic factors on microorganisms were different, and microbial population, community activity and metabolic diversity showed positive correlation with organic matter content, whereas they showed negative correlation with total phosphorus content in the surface soils in the wet meadows.

  13. Using bioavailable soil fraction to assess the bioconcentration factor of plants in phytoremediation of mine soils

    Science.gov (United States)

    Roca, Núria; Rodríguez-Bocanegra, Javier; Bech, Jaume

    2017-04-01

    Polluted soils by heavy metals are characterized to present great concentrations of these pollutants. Ure wrote the following in 1996: "For understanding the chemistry of the heavy metals in their interaction with other soil components such as the clay minerals, organic matter and the soil solution, or to assess their mobility and retention as well as their availability to plants, the usual approach is to use selective chemical extraction". However, nowadays to assess the bioconcentration factor of plants in phytoremediation, the pseudototal or total concentration has been used. Strong mineral acids attack part of the silicate soil matrix and as consequence part of the heavy metals obtained are included in the structures of the mineral fraction. A different approach may, therefore, be more productive in the study of phytoremediation and the use of extractants, as EDTA or DTPA, can perhaps best be exploited by considering them in their role of bioconcentration factor. Moreover, EDTA and DTPA, which form strong complexes with many metals, can extract also organically complex metals. Properties of the soils collected in mining areas presented great variability, as they depend on materials where soils were developed, the complex mixture of heterogeneous wastes and the mining age. In the case of Caroline Mine in Hualgayoc (Perú), the mining is relatively modern and the available fraction of heavy metals of mine soils is low. The small available fraction concentration is due partly to both a few developed soil structure and low organic matter content. The only exception was the copper, with ranging from 1.2 to 36.2 % of total soil fraction. All plant species that were investigated in previous studies have a good ability to transport potential hazardous elements from the roots to the shoots and they have the ability to accumulate more than 1000 mg•kg-1 of heavy metals in the shoots. However, the bioconcentration factor was smaller than one for all the studied plants in

  14. Discriminating impacts of geomorphological and human factors on vineyard soil erosion (Burgundy, France)

    Science.gov (United States)

    Chevigny, Emmanuel; Quiquerez, Amélie; Petit, Christophe; Curmi, Pierre

    2014-05-01

    The Burgundy vineyards have been recognized for the high diversity of Terroirs, controlled by complex interactions between natural features, historical parameters and soil management practices. Vineyards are known to undergo substantial soil loss in comparison with other types of agricultural land. Hydric erosion on vineyards is controlled by complex interactions of natural and anthropogenic factors leading to intra-plot spatial heterogeneities of topsoil at a scale of a metre. Studying the relationship between soils and their degradation is crucial in this situation where soil sustainability is threatened. This study explores the relative influences of historical and present-day anthropogenic factors and geomorphological processes controlling soil erosion on vineyard hillslopes. The selected area was located in the Monthelie vineyard (Côte de Beaune, France) where intensive erosion occurred during high-intensity rainfall events. Soil erosion quantification was performed at a square-metre scale using dendrogeomorphology. This method is based on the measurement of the unearthing of the stock located on the vine plants, considered as a passive marker of soil-surface vertical displacement since the year of plantation. The obtained maps, together with various complementary datasets, such as geological and geomorphological data, but also historical documents (cadastral plans, cadastral matrices and old aerial photographs) allow landscape evolution to be assessed. The combination of all these data shows that spatial distribution and intensity of erosion are controlled mainly by lithology and slope value. However, our study highlights that the sediment dynamics in this vineyard plot is highly related to historical former plot limits and present-day management practices. Nonetheless, quantification of sediment dynamic for the last decade reveals that the impacts of historical structures are disappearing gradually, in response to present-day management practices and

  15. Influence of liquid water and soil temperature on petroleum hydrocarbon toxicity in Antarctic soil.

    Science.gov (United States)

    Schafer, Alexis N; Snape, Ian; Siciliano, Steven D

    2009-07-01

    Fuel spills in Antarctica typically occur in rare ice-free oases along the coast, which are areas of extreme seasonal freezing. Spills often occur at subzero temperatures, but little is known of ecosystem sensitivity to pollutants, in particular the influence that soil liquid water and low temperature have on toxicity of petroleum hydrocarbons (PHC) in Antarctic soil. To evaluate PHC toxicity, 32 locations at an aged diesel spill site in Antarctica were sampled nine times to encompass frozen, thaw, and refreeze periods. Toxicity was assessed using potential activities of substrate-induced respiration, basal respiration, nitrification, denitrification, and metabolic quotient as well as microbial community composition and bacterial biomass. The most sensitive indicator was community composition with a PHC concentration effecting 25% of the population (EC25) of 800 mg/kg, followed by nitrification (2,000 mg/kg), microbial biomass (2,400 mg/kg), and soil respiration (3,500 mg/kg). Despite changes in potential microbial activities and composition over the frozen, thaw, and refreeze period, the sensitivity of these endpoints to PHC did not change with liquid water or temperature. However, the variability associated with ecotoxicity data increased at low liquid water contents. As a consequence of this variability, highly replicated (n = 50) experiments are needed to quantify a 25% ecological impairment by PHCs in Antarctic soils at a 95% level of significance. Increases in biomass and respiration associated with changes in community composition suggest that PHC contamination in Antarctic soils may have irrevocable effects on the ecosystem.

  16. INFLUENCE OF SEWAGE SLUDGE ON THE CHOSEN SOIL PROPERTIES AND MICROBIOLOGICAL PARAMETERS OF URBAN GRASS MIXTURES RHIZOSPHERE

    Directory of Open Access Journals (Sweden)

    Urszula Wydro

    2014-12-01

    Full Text Available The aim of this study was to analyse the influence of municipal sewage sludge on selected microbiological parameters in the rhizosphere of lawn grass mixtures. Four experiments on the lawns along the main roads of Bialystok were founded. The factors in the experiment were three doses of sewage sludge (0 – control; 7.5 and 15 kg·m-2 and two grass mixtures (Eko and Roadside. The studied parameters were monitored twice during 2011 vegetation season by determining the total number of soil microorganisms, the total number of Gram-negative bacteria, the number of bacteria of Pseudomonas fluorescens species, the number of amylolytic and proteolytic bacteria. Sewage sludge amended to soil resulted in a change of physical-chemical properties of soil. The sewage sludge application to soil influenced significantly the number of proteolytic and Gram-negative bacteria.

  17. Soil Influences Colonization of Root-Associated Fungal Endophyte Communities of Maize, Wheat, and Their Progenitors

    Directory of Open Access Journals (Sweden)

    Deepak Bokati

    2016-01-01

    Full Text Available Root-associated fungal endophytes are vital component of root microbiome as some mitigate their host’s abiotic and biotic stress. We characterized root-associated fungal endophytes in cereal grains and their progenitors grown on two different soil-types. We aimed at determining how clay and desert soil affects the colonization of root fungal community. Both culture-dependent and culture-independent methods were employed to identify endophytes that successfully colonized greenhouse-grown host plants. The Internal Transcriber Spacer region of fungal ribosomal DNA was utilized for identification purposes. This study revealed soil as a prominent factor influencing the composition of microfungal communities inhabiting the roots of maize (Zea mays subsp. mays and its conspecific progenitor, teosinte (Zea mays subsp. parviglumis. Similar results were found in wheat (Triticum aestivum subsp. aestivum and its progenitor (Triticum monococcum subsp. monococcum. The multidimensional comparisons of Morisita-Horn similarity values of fungal colonists of various host plant taxa indicated that soil plays a primary role in shaping the root fungal community; a secondary effect was plant host identity, even when the plant host is a conspecific. Future studies focused on characterizing root endophytes in other cereal grains, and studying the effect of edaphic factors on fungal colonization, can ultimately contribute to crop productivity.

  18. Chloride and organic chlorine in forest soils: storage, residence times, and influence of ecological conditions.

    Science.gov (United States)

    Redon, Paul-Olivier; Abdelouas, Abdesselam; Bastviken, David; Cecchini, Sébastien; Nicolas, Manuel; Thiry, Yves

    2011-09-01

    Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cl(tot)) and organic chlorine (Cl(org)) were determined in litterfall, forest floor and mineral soil samples. Cl(org) constituted 11-100% of Cl(tot), with the highest concentrations being found in the humus layer (34-689 mg Cl(org) kg(-1)). In terms of areal storage (53 - 400 kg Cl(org) ha(-1)) the mineral soil dominated due to its greater thickness (40 cm). Cl(org) concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Cl(org) concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Cl(in)) and organic) was 5-fold higher than that estimated for Cl(in) alone. Consideration of the Cl(org) pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems.

  19. CREDIT LEVEL INFLUENCING FACTORS AT HUNGARIAN FARMS

    Directory of Open Access Journals (Sweden)

    Toth Jozsef

    2012-12-01

    Full Text Available In this paper we estimate the impact of different factors on creditability of agricultural farms. According to the literature the collateral (tangible assets, the farm size, productivity, and subsidies should have significant effects on farm loans. We use data from the Hungarian Farm Accountancy Data Network to test our two hypotheses and theoretical assumptions for the period 2001-2010. Because of using panel data, we do our estimations using fixed effects econometrics model to test our assumptions. The results indicate that the chosen factors have significant influence on total liabilities and short- and long-term loans as well. With specially interest of subsidies the growing level of supports decrease the need of other financial tools. At output factors (inclusive farm size have significant and positive effect, same as collateral (tangible assets.

  20. Internal factors influencing the knowledge continuity ensuring

    Directory of Open Access Journals (Sweden)

    Hana Urbancová

    2012-01-01

    Full Text Available The aim of the systematic ensuring of knowledge continuity is the continuity of an organisation’s development, the quality of managerial positions and the continuity of decision-making. By ensuring knowledge continuity, organisations may gain a performance-enhancing factor. The objective of the article is to identify the level of impact of decisive internal factors determining knowledge continuity ensuring and contributing to the efficiency of the organisations. Knowledge continuity ensuring as an internal force, however, can together with the right employees, help adapt more quickly to external conditions that organisations can hardly control. Monitoring and ensuring knowledge continuity can contribute to a higher quality of processes in general, in particular processes exploiting knowledge, and thus help improve the level of management. The first part of the article presents theoretical views on the aspects of knowledge continuity ensuring in organisations while the second part analyses the findings of the surveys carried out among managers in organisations in the Czech Republic. Based on the summary of the outcomes obtained it is possible to say that internal factors influence knowledge continuity ensuring in organisations, however, the level of impact of individual factors is determined by their size. The findings regarding the impact of each of the factors show that the most significant barriers to knowledge continuity ensuring are those associated with the human factor.

  1. Analysis of Communication and Dissemination Channels Influencing the Adoption of Integrated Soil Fertility Management in Western Kenya

    Science.gov (United States)

    Adolwa, Ivan S.; Okoth, Peter F.; Mulwa, Richard M.; Esilaba, Anthony O.; Mairura, Franklin S.; Nambiro, Elizabeth

    2012-01-01

    Purpose: The following study was carried out to evaluate the socio-economic factors influencing access to Integrated Soil Fertility Management (ISFM) information and knowledge among farmers in western Kenya, and subsequent ISFM uptake with a view to assessing communication gaps. Design/Methodology/Approach: Structured questionnaires were…

  2. Growth, yield and yield components of dry bean as influenced by phosphorus in a tropical acid soil

    Science.gov (United States)

    Phosphorus deficiency is one of the most yield limiting factors for dry bean (Phaseolus vulgaris) production in tropical acid soils. Dry beans are invariably grown as mono crops or as inter crops under the perennial tropical crops. Information is limited regarding the influence of phosphorus fertili...

  3. Microbial PAH-Degradation in Soil: Degradation Pathways and Contributing Factors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-Xiang; CHENG Shu-Pei; ZHU Cheng-Jun; SUN Shi-Lei

    2006-01-01

    Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

  4. Sound absorption coefficient in situ: an alternative for estimating soil loss factors.

    Science.gov (United States)

    Freire, Rosane; Meletti de Abreu, Marco Henrique; Okada, Rafael Yuri; Soares, Paulo Fernando; GranhenTavares, Célia Regina

    2015-01-01

    The relationship between the sound absorption coefficient and factors of the Universal Soil Loss Equation (USLE) was determined in a section of the Maringá Stream basin, Paraná State, by using erosion plots. In the field, four erosion plots were built on a reduced scale, with dimensions of 2.0×12.5m. With respect to plot coverage, one was kept with bare soil and the others contained forage grass (Brachiaria), corn and wheat crops, respectively. Planting was performed without any type of conservation practice in an area with a 9% slope. A sedimentation tank was placed at the end of each plot to collect the material transported. For the acoustic system, pink noise was used in the measurement of the proposed monitoring, for collecting information on incident and reflected sound pressure levels. In general, obtained values of soil loss confirmed that 94.3% of material exported to the basin water came from the bare soil plot, 2.8% from the corn plot, 1.8% from the wheat plot, and 1.1% from the forage grass plot. With respect to the acoustic monitoring, results indicated that at 16kHz erosion plot coverage type had a significant influence on the sound absorption coefficient. High correlation coefficients were found in estimations of the A and C factors of the USLE, confirming that the acoustic technique is feasible for the determination of soil loss directly in the field.

  5. Parent material, vegetation or slope position - which soil-forming factor controls the intensity of podzolization process in the soils of the Sudety Mountains montane zone?

    Science.gov (United States)

    Musielok, Łukasz

    2016-04-01

    Climatic conditions, parent material and vegetation type are considered to be the main soil-forming factors controlling podzolization process advancement. Moreover, in hilly and mountainous areas properties of soils that are undergoing podzolization process are influenced significantly by its location on a slope, due to lateral translocation of soil solutions. The Sudety Mts. are a medium-high mountain range characterized by geological mosaic with many different sedimentary, igneous and metamorphic rocks, mostly poor in alkali elements. Most of the Sudety Mts. area lies in a lower montane zone, where the dominant natural vegetation were temperate mixed and deciduous forests. However, since 18th century natural vegetation was significantly transformed by widespread introduction of spruce monocultures. These distinguishing features of the Sudety Mts. natural environment are considered to be responsible for prevalence of podzolized soil in this area, however the intensity of podzolization process is very differentiated. The aim of presented research was to determine the influence of varying parent material, different vegetation types and different slope positions the on the soil properties variability, and thus, to answer the question which of the analyzed soil-forming factors is controlling the podzolization process advancement in the Sudety Mountains montane zone? Data from A, E, Bs and C horizons of 16 soil profiles developed from different parent materials (granite, sandstone, andesites and mica schists), located under various types of vegetation (spruce and beech forests) and in different slope positions (upper, middle and lower parts of the slopes) were taken into the analysis. All analyzed soil profiles were located in lower montane zone between 550 and 950 m a. s. l. to avoid the influence of varying climatic conditions. One-way ANOVA and Principal Components Analysis (PCA) were used to analyze differentiation of soil texture, pH, organic carbon and nitrogen

  6. INFLUENCES OF SOIL AND GENOTYPES ON MICRONUTRIENTS STATUS IN MAIZE PLANTS

    Directory of Open Access Journals (Sweden)

    Manda Antunović

    2003-06-01

    Full Text Available Ten corn hybrids were grown on two soil types of Drava Valley in Slatina area (alluvial soil and pseudogley during two growing seasons (1998 and 1999. The ear-leaf at the beginning of silking stage was taken for chemical analysis. Micronutrient concentrations in corn leave samples were measured by ICP-AES after their microwave digestion using concentrated HNO3+H2O2. Mobile fraction of these elements in soils was also determined by ICP-AES after their extraction by ammonium acetate-EDTA. In both year of the testing, corn yields on acid soil were about 25% lower in comparison with alluvial soil. Mean concentrations of tested elements in corn leaves found in our investigations (mg kg-1 were 30.4 (Zn, 129.4 (Mn and 190.0 (Fe, respectively. In general, significant influences of growing season, soil type and genotype on Zn, Mn and Fe status in corn were found. For example, in the first year of testing higher Zn and Mn were found, as well as lower Fe concentrations in comparison with the second year. Corn growing on alluvial soil occurred due to lower Zn and Mn as well as higher Fe concentrations in plants compared to growing on pseudogley. However, these findings are not in coincidence with status of mobile fractions of Zn and Mn in the experimental plots. We presume that pH value near to neutral on alluvial soil could be responsible factor because low availability of Zn and Mn for plants occured under these conditions. An important role of heredity factors on Zn, Mn and Fe status in corn was found in our study because differences among the hybrids (mean values for two growing seasons and two soil types under identical environmental conditions were in ranges (mg kg-1 from 26.8 to 36.0 (Zn, from 98.6 to 150.4 (Mn and from 168.2 to 222.4 (Fe, respectively. It is very indicative that the first-ranged hybrid concerning grain yield (OsSK458exp: 12.34 t ha-1 is in the group characterizing low concentrations of Zn, Mn and Fe in leaves.

  7. Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture

    Directory of Open Access Journals (Sweden)

    Timothy J. Albaugh

    2015-08-01

    Full Text Available We examined three hypotheses in a nutrient dose and application frequency study installed in juvenile (aged 2–6 years old Pinus stands at 22 sites in the southeastern United States. At each site, eight or nine treatments were installed where nitrogen was applied at different rates (0, 67, 134, 268 kg ha−1 and frequencies (0, 1, 2, 4 and 6 years in two or four replications. Phosphorus was applied at 0.1 times the nitrogen rate and other elements were added as needed based on foliar nutrient analysis to insure that nutrient imbalances were not induced with treatment. Eight years after treatment initiation, the site responses were grouped based on texture and drainage characteristics: soil group 1 consisted of poorly drained soils with a clayey subsoil, group 2 consisted of poorly to excessively drained spodic soils or soils without a clay subsoil, and group 3 consisted of well-drained soils with a clayey subsoil. We accepted the first hypothesis that site would be a significant factor explaining growth responses. Soil group was also a significant factor explaining growth response. We accepted our second hypothesis that the volume growth-cumulative dose response function was not linear. Volume growth reached an asymptote in soil groups 1 and 3 between cumulative nitrogen doses of 300–400 kg ha−1. Volume growth responses continued to increase up to 800 kg ha−1 of cumulatively applied nitrogen for soil group 2. We accepted our third hypothesis that application rate and frequency did not influence the growth response when the cumulative nitrogen dose was equivalent. There was no difference in the growth response for comparisons where a cumulative nitrogen dose of 568 kg ha−1 was applied as 134 kg ha−1 every two years or as 269 kg ha−1 every four years, or where 269 kg ha−1 of nitrogen was applied as four applications of 67 kg ha−1 every two years or as two applications of 134 kg ha−1 every four years. Clearly, the sites examined

  8. Influence of traffic activity on heavy metal concentrations of roadside farmland soil in mountainous areas.

    Science.gov (United States)

    Zhang, Fan; Yan, Xuedong; Zeng, Chen; Zhang, Man; Shrestha, Suraj; Devkota, Lochan Prasad; Yao, Tandong

    2012-05-01

    Emission of heavy metals from traffic activities is an important pollution source to roadside farmland ecosystems. However, little previous research has been conducted to investigate heavy metal concentrations of roadside farmland soil in mountainous areas. Owing to more complex roadside environments and more intense driving conditions on mountainous highways, heavy metal accumulation and distribution patterns in farmland soil due to traffic activity could be different from those on plain highways. In this study, design factors including altitude, roadside distance, terrain, and tree protection were considered to analyze their influences on Cu, Zn, Cd, and Pb concentrations in farmland soils along a mountain highway around Kathmandu, Nepal. On average, the concentrations of Cu, Zn, Cd, and Pb at the sampling sites are lower than the tolerable levels. Correspondingly, pollution index analysis does not show serious roadside pollution owing to traffic emissions either. However, some maximum Zn, Cd, and Pb concentrations are close to or higher than the tolerable level, indicating that although average accumulations of heavy metals pose no hazard in the region, some spots with peak concentrations may be severely polluted. The correlation analysis indicates that either Cu or Cd content is found to be significantly correlated with Zn and Pb content while there is no significant correlation between Cu and Cd. The pattern can be reasonably explained by the vehicular heavy metal emission mechanisms, which proves the heavy metals' homology of the traffic pollution source. Furthermore, the independent factors show complex interaction effects on heavy metal concentrations in the mountainous roadside soil, which indicate quite a different distribution pattern from previous studies focusing on urban roadside environments. It is found that the Pb concentration in the downgrade roadside soil is significantly lower than that in the upgrade soil while the Zn concentration in the

  9. Influence of Traffic Activity on Heavy Metal Concentrations of Roadside Farmland Soil in Mountainous Areas

    Directory of Open Access Journals (Sweden)

    Tandong Yao

    2012-05-01

    Full Text Available Emission of heavy metals from traffic activities is an important pollution source to roadside farmland ecosystems. However, little previous research has been conducted to investigate heavy metal concentrations of roadside farmland soil in mountainous areas. Owing to more complex roadside environments and more intense driving conditions on mountainous highways, heavy metal accumulation and distribution patterns in farmland soil due to traffic activity could be different from those on plain highways. In this study, design factors including altitude, roadside distance, terrain, and tree protection were considered to analyze their influences on Cu, Zn, Cd, and Pb concentrations in farmland soils along a mountain highway around Kathmandu, Nepal. On average, the concentrations of Cu, Zn, Cd, and Pb at the sampling sites are lower than the tolerable levels. Correspondingly, pollution index analysis does not show serious roadside pollution owing to traffic emissions either. However, some maximum Zn, Cd, and Pb concentrations are close to or higher than the tolerable level, indicating that although average accumulations of heavy metals pose no hazard in the region, some spots with peak concentrations may be severely polluted. The correlation analysis indicates that either Cu or Cd content is found to be significantly correlated with Zn and Pb content while there is no significant correlation between Cu and Cd. The pattern can be reasonably explained by the vehicular heavy metal emission mechanisms, which proves the heavy metals’ homology of the traffic pollution source. Furthermore, the independent factors show complex interaction effects on heavy metal concentrations in the mountainous roadside soil, which indicate quite a different distribution pattern from previous studies focusing on urban roadside environments. It is found that the Pb concentration in the downgrade roadside soil is significantly lower than that in the upgrade soil while the Zn

  10. Environmental factors influencing the development of atherosclerosis

    Directory of Open Access Journals (Sweden)

    Andrzej Brodziak

    2013-12-01

    Full Text Available The aim of the paper is to present an overview of recent findings on the environmental and behavioral factors influencing the development of atherosclerosis. The authors primarily concentrated on deliberations of possibile main causes of the damage of the endothelium. At the same time the following pathogenic mechanisms as cellular dysfunction, inflammation and coagulation disorders have been enumerated. The links between the state of the vascular endothelium and life style have been emphasized. It is also important to note that the primary causes of the endothelial damage should be traced as originally suggested many years ago viewing such factors as anger, hostility, aggression, impulsiveness and depression but with a new approach. The authors supplement the comments, on the environmental factors influencing the development of atherosclerosis, with basic data on family predisposition to the development of this disease. They highlight that current genetic research have not determined genes responsible for atheroscelosis. According to the authors the considerations and conclusions presented in this overview are important for the educational purposes related to the most frequent disease process resulting in many diseases in medical disciplines.

  11. The influence of rainfall and soil hydrology on pipeflow in steep pasture-covered hill country

    Science.gov (United States)

    Crozier, M.; Hardenbicker, U.; Pott, A.

    2003-04-01

    This study presents some real time measurements of stormflow occurring in soil pipes. The aim of the study is to measure pipeflow runoff characteristics, determine which factors control flow behaviour, and estimate the role of pipeflow in hillslope drainage. Storms of different magnitudes are compared to assess the changing role of hydrological processes feeding pipeflow. In the study area of Hawke's Bay, North Island, New Zealand permeable soils overly low permeability marine sediments to a depth of about 1.2 m. The study area is ser-viced by an automatic climate station and five nearby sites are equipped to measure soil tension and soil moisture (at depths of 25, 50, and 100cm) as well as porewater pressure throughout the profile. The pipeflow network investigated has a catchment area of 1219 m2 and exits the base of study slope just upslope of a landslide scar. A thin-walled, 20 degree 'v'-notch weir has been installed at the pipe exit with water depth recorded by a pressure transducer / data logger system. Pipeflow is ephemeral with twenty-nine discrete pipeflow events being recorded between July 2000 and November 2001 associated with rainfall events ranging in total between 5.4mm and 296 mm. The flow events are generally very small with volumes ranging from less than one litre to 70,000 litres. The five largest events have total volumes ranging from 168 - 70,356 litres with maximum discharges recorded at one minute intervals ranging from 965 - 83,264 ml/min. In all cases pipeflow commenced several hours before soil moisture began to rise at the position in the soil where pipes were located (50cm depth). This suggests that pipeflow is not the result of the wetting front from matrix flow intersecting the pipe. However in high magnitude prolonged events results indicate that matrix flow and groundwater may contribute to pipeflow. Time lags between onset of rain and pipeflow and delays in soil moisture response indicate that bypass flow rather than matrix flow

  12. Key-socio economic factors influencing sustainable land management investments in the West Usambara Highlands, Tanzania

    NARCIS (Netherlands)

    Nyanga, A.W.; Kessler, C.A.; Tenge, A.J.M.

    2016-01-01

    Low investments in sustainable land management (SLM) limit agricultural production in the East African Highlands, leading to increased soil erosion, low productivity of land and food insecurity. Recent studies in the region show that different socio-economic factors influence SLM investments by farm

  13. Evolution Characteristics and Influence Factors of Acidification in Paddy Soil of Southern China%中国南方水稻土酸化演变特征及影响因素

    Institute of Scientific and Technical Information of China (English)

    周晓阳; 周世伟; 徐明岗; Colinet Gilles

    2015-01-01

    【目的】明确中国南方水稻土酸化特征及主要影响因素,为防控水稻土酸化提供理论依据。【方法】选择中国南方江苏、湖南、广东、广西、四川和云南6个省份(自治区)的20个水稻土长期定位监测点,统计分析水稻土pH演变特征及阶段性变化规律,并探讨施肥量及土壤氮素含量对水稻土酸化的影响。【结果】1988—2013年25年间中国南方水稻土显著酸化,土壤pH下降0.59个单位,平均每年下降0.023个单位。水稻土酸化具有明显的阶段性特征,起始的14年中水稻土pH急速下降,平均每年可下降0.051个单位;近10年间,土壤pH趋于平稳。增施化肥特别是化学氮肥可导致水稻土酸化,二者与土壤pH均呈显著负相关关系(P<0.01),由此推算出化学氮肥每增施100 kg·hm-2,水稻土pH可下降0.65个单位。减少有机肥的施用也可引起水稻土酸化,有机肥施用量与土壤pH之间呈显著正相关关系,有机肥每减少100 kg·hm-2,水稻土pH下降0.51个单位。土壤全氮及碱解氮含量与pH间均呈极显著负相关关系,土壤全氮和碱解氮含量每增加100 mg·kg-1,水稻土pH约下降0.1个单位。【结论】在过去25年间,中国南方水稻土显著酸化,酸化具有明显的阶段性特征,施肥初期土壤pH显著降低。减少化学氮肥的施用和增施有机肥是控制水稻土酸化的重要措施。%[Objective]The objective of this research was to illustrate evolution characteristics of acidification in paddy soil of southern China and to understand the main reasons of soil acidification, which will help farmers to reduce and control soil acidification rate in these areas by rational fertilization.[Method]We collected monitoring data from 20 sites located in Jiangsu, Hunan, Guangdong, Guangxi, Sichuan and Yunnan Province in southern China to evaluate soil acidification characteristics of paddy soils and to

  14. Contextual factors influencing research use in nursing.

    Science.gov (United States)

    French, Beverley

    2005-01-01

    Contextual factors are perceived to be significant barriers to research-utilisation-related activity, but little is known about how context impacts on specific research-based decisions, or how the individual interacts with the organisation in the requirement for research-based change. This study describes the impact of contextual factors on the practical reasoning of nurse specialists in the construction of policy for practice. Three groups of clinical nurse specialists were observed during a series of meetings convened to construct evidence-based guidelines for nursing practice. Transcripts of the meetings were analysed to identify and categorise the physical, social, political, and economic influences on 31 nursing issues. Multiple contextual factors influenced each decision made, with decisions about nursing practice bounded by setting and system considerations, relationships with others in the care team, and resource constraints. Practitioners were involved in weighing up alternative scenarios, contexts, and contingencies for each decision, requiring strategies to adapt and reconstruct the nature of care, to influence others, and to affect organisational decision-making processes. The practical accomplishment of evidence-based practice required diverse skills: translating between evidence and practice; mediating the values, preferences, and working practices of multiple stakeholders; negotiating organisational complexity and the management of boundaries; and coordinating inter-organisational and inter-agency working. Nurse specialists in this study had a significant role in instigating, fuelling, and coordinating policy review, predominantly by communication across professional and organisational boundaries. Clinical specialists acting as organisational boundary spanners require skills in the informal cultural work of organising, facilitating, and maintaining links across professional, team, and organisational boundaries. If their role in the negotiation of

  15. Influence of selected factors on induced syneresis

    Directory of Open Access Journals (Sweden)

    Jovanović Snežana T.

    2004-01-01

    Full Text Available Syneresis is the process of whey separation induced by gel contraction resulting in rearranging or restructuring of casein matrix formed during enzymatic coagulation. Numerous factors can influence the process of syneresis. The influences of pH, calcium concentration, temperature of coagulation of milk and applied heat treatment on the syneresis induced by different intensity of centrifugal force have been investigated. Coagulated samples were centrifuged at 1000, 2000 and 3000 rpm for 5 min, respectively. Reconstituted skim milk powder (control sample and reconstituted non-fat milk heat treated at 87ºC/10 min (experimental sample are coagulated at temperatures of 30ºC and 35ºC, at pH value of 5.8 and 6.2, and with the addition of 100, 200 and 400 mg/l of CaCl2, respectively. Centrifugation at 1000 rpm of both control and experimental samples didn’t recover any sera, regardless of the applied coagulation conditions. This indicates that the intensity of centrifugal force wasn’t strong enough to disrupt gel structure and cause syneresis. When the intensity of centrifugal force was increased up to 2000 rpm, the syneresis was induced, but the degree of syneresis depended on the applied factors of coagulation, primary on the applied heat treatments and temperature of coagulation. The amount of added CaCl2 didn’t have a significant influence on the induced syneresis at 2000 rpm. The induced syneresis was very significant for both control and experimental samples when the intensity of centrifugal force of 3000 rpm was applied. It was also noted that curd produced from heat treated milk in which milk protein coaggregates were formed, released less sera regardless of the applied coagulation factors.

  16. Factors influencing aircraft ground handling performance

    Science.gov (United States)

    Yager, T. J.

    1983-01-01

    Problems associated with aircraft ground handling operations on wet runways are discussed and major factors which influence tire/runway braking and cornering traction capability are identified including runway characteristics, tire hydroplaning, brake system anomalies, and pilot inputs. Research results from tests with instrumented ground vehicles and aircraft, and aircraft wet runway accident investigation are summarized to indicate the effects of different aircraft, tire, and runway parameters. Several promising means are described for improving tire/runway water drainage capability, brake system efficiency, and pilot training to help optimize aircraft traction performance on wet runways.

  17. Influence of soil frost on the character and degradability of dissolved organic carbon in boreal forest soils

    Science.gov (United States)

    Panneer Selvam, B.; Laudon, H.; Guillemette, F.; Berggren, M.

    2016-03-01

    Recent studies suggest that increases in extent and duration of winter soil frost increases dissolved organic carbon (DOC) concentrations in boreal riparian soils and connected aquatic systems during the subsequent spring and summer. However, little is known about the impact of frost on DOC character and its degradability. We applied three experimental treatments to riparian soils in northern Sweden—shallow soil frost (insulated), deep soil frost (snow removed) and control plots—to test the effect of different soil frost regimes on the chemical characteristics and degradability of soil DOC. Soil pore water samples were analyzed using excitation-emission fluorescence (parallel factor analysis) combined with biological and photochemical degradation experiments. We found that the absolute bacterial metabolic rates were significantly lower in samples from the shallow soil frost treatments, compared with the other treatments. Explorative multivariate analyses indicate that increasing soil frost is contributing to increased protein-like fluorescence and to increased biological degradability of the DOC. Our study shows that decreases in riparian soil frost due to climate warming may not only contribute to decreased riparian DOC concentrations but also lead to shifts in the DOC composition, resulting in decreased biodegradability (yet similar photodegradability) of the DOC that is exported from riparian soils to streams.

  18. Factors influencing groundwater quality: towards an integrated management approach.

    Science.gov (United States)

    De Giglio, O; Quaranta, A; Barbuti, G; Napoli, C; Caggiano, G; Montagna, M T

    2015-01-01

    The safety of groundwater resources is a serious issue, particularly when these resources are the main source of water for drinking, irrigation and industrial use in coastal areas. In Italy, 85% of the water used by the public is of underground origin. The aim of this report is to analyze the main factors that make groundwater vulnerable. Soil characteristics and filtration capacity can promote or hinder the diffusion of environmental contaminants. Global climate change influences the prevalence and degree of groundwater contamination. Anthropic pressure causes considerable exploitation of water resources, leading to reduced water availability and the progressive deterioration of water quality. Management of water quality will require a multidisciplinary, dynamic and practical approach focused on identifying the measures necessary to reduce contamination and mitigate the risks associated with the use of contaminated water resources.

  19. The influence of organic matter on sorption and fate of glyphosate in soil - Comparing different soils and humic substances

    Energy Technology Data Exchange (ETDEWEB)

    Albers, Christian N., E-mail: calbers@ruc.d [Dept. of Geochemistry, Geological Survey of Denmark and Greenland, DK-1350 Copenhagen (Denmark); Dept. of Science, Systems and Models, Roskilde University, DK-4000 Roskilde (Denmark); Banta, Gary T. [Dept. of Environmental, Social and Spatial Change, Roskilde University, DK-4000 Roskilde (Denmark); Hansen, Poul Erik [Dept. of Science, Systems and Models, Roskilde University, DK-4000 Roskilde (Denmark); Jacobsen, Ole S. [Dept. of Geochemistry, Geological Survey of Denmark and Greenland, DK-1350 Copenhagen (Denmark)

    2009-10-15

    Soil organic matter (SOM) is generally believed not to influence the sorption of glyphosate in soil. To get a closer look on the dynamics between glyphosate and SOM, we used three approaches: I. Sorption studies with seven purified soil humic fractions showed that these could sorb glyphosate and that the aromatic content, possibly phenolic groups, seems to aid the sorption. II. Sorption studies with six whole soils and with SOM removed showed that several soil parameters including SOM are responsible for the strong sorption of glyphosate in soils. III. After an 80 day fate experiment, approx40% of the added glyphosate was associated with the humic and fulvic acid fractions in the sandy soils, while this was the case for only approx10% of the added glyphosate in the clayey soils. Glyphosate sorbed to humic substances in the natural soils seemed to be easier desorbed than glyphosate sorbed to amorphous Fe/Al-oxides. - Glyphosate was sorbed by purified humic substances and a significant amount of glyphosate was found to be associated with soil organic matter in whole soils.

  20. Factors influencing the cardiac MIBG accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Takatsu, Hisato; Fujiwara, Hisayoshi [Gifu Univ. (Japan). School of Medicine

    1997-02-01

    Following factors possibly influencing the cardiac MIBG accumulation were examined mainly in mice. 1. The specific activity of the MIBG (meta-iodo-benzyl guanidine) on the neuronal and non-neuronal fractions. 2. Motor restriction stress on MIBG accumulation and washout. 3. Loading and restriction of sodium chloride on the accumulation and effect of suppression of renin-angiotensin system. 4. Examinations in Dahl rats. 125I- or 131I-MIBG was intravenously administered to mice at 74 kBq. At 30 min or 4 hr after administration, mice were sacrificed and their left ventricles were dissected out for measurement of radioactivity in a liquid scintillation counter. Salt-sensitive and -resistant Dahl rats were given with 37 MBq of 123I-MIBG and cardiac radioactivity was measured externally for calculation of washout. Factors examined were found highly correlated with the accumulation of MIBG and measurement of its washout was considered useful for evaluating sympathetic activity. (K.H.)

  1. A survey on factors influencing city branding

    Directory of Open Access Journals (Sweden)

    Seyed Mohsen Mahmoudzadeh

    2014-10-01

    Full Text Available Nowadays, the issue of “globalization” is entering to all areas in the world. In addition to products and companies, cities and countries also have the opportunity to see themselves as important actors in international arena. Places define their positions in different fields like business, leisure and recreation, educational opportunities, living, etc. This paper presents an empirical study to introduce city branding as one of the solutions to join globalization process. The method of this research is based on the “descriptive-analytic” and utilize the available literature and experts’ opinions to prioritize the influencing factors of city branding. We use Delphi consensus methods and technique of analytical hierarchy process to evaluate the factors. Finally, the results of the study indicate that security, transportation and mental creativity are the weakest fields and business and shopping facilities are strong fields of city branding in metropolitan of Tehran.

  2. [Responses of Manglietia glauca growth to soil nutrients and climatic factors].

    Science.gov (United States)

    Lu, Li-Hua; He, Ri-Ming; Nong, Rui-Hong; Li, Zhong-Guo

    2014-04-01

    Tree height and diameter of breast height (DBH) as growth characteristics of Manglietia glauca introduced from Vietnam were measured at many sites in south China and responses of M. glauca growth to soil nutrients and climatic factors were analyzed in this study. Annual average increments of tree height and DBH among different planted sites had significant differences. Annual average increments of tree height and DBH had significant positive correlation with soil total N and P, available N and P, but no significant correlation with soil organic matter, total K, available K, indicating that soil N and P contents could be the main affecting factors for the growth of M. glauca. Annual average increment of tree height had significant difference, but annual average increment of DBH had no significant difference at different altitudes. Annual average increment of tree height increased with the altitude from 150 to 550 m, the maximum was at the altitude of 550 m, and then it decreased. It indicated that the most appropriate altitude for M. glauca introduction is 550 m. Annual average increments of tree height and DBH had significant negative correlation with annual average temperature and > or = 10 degrees C accumulated temperature, and significant positive correlation with annual average precipitation, suggesting that annual mean temperature, > or = 10 degrees C accumulated temperature and annual average precipitation could be the main climatic factors influencing the growth of M. glauca.

  3. Tree species is the major factor explaining C:N ratios in European forest soils

    DEFF Research Database (Denmark)

    Cools, Nathalie; Vesterdal, Lars; De Vos, Bruno

    2014-01-01

    The C:N ratio is considered as an indicator of nitrate leaching in response to high atmospheric nitrogen (N) deposition. However, the C:N ratio is influenced by a multitude of other site-related factors. This study aimed to unravel the factors determining C:N ratios of forest floor, mineral soil...... and peat top soils in more than 4000 plots of the ICP Forests large-scale monitoring network. The first objective was to quantify forest floor, mineral and peat soil C:N ratios across European forests. Secondly we determined the main factors explaining this C:N ratio using a boosted regression tree...... analysis (BRT), including fifteen site and environmental variables. Ninety-five percent of the C:N ratios were between 16 and 44 in the forest floor, between 13 and 44 in the peat topsoil and between 10 and 32 in the mineral topsoil. Within the aerated forest floor and the mineral soil, the C:N ratios...

  4. Mineralization of organic matter with warming in boreal forest soils is influenced by nitrogen dynamics

    Science.gov (United States)

    Li, J.; Ziegler, S. E.; Lane, C. S.; Billings, S. A.

    2011-12-01

    Temperature is an important factor in regulating soil organic matter (SOM) decomposition, but the drivers of microbial substrate choice with changing temperature regimes remain poorly elucidated. For example, nitrogen (N) dynamics play a key role in dictating activity levels of different microbial groupings, which in turn may influence who in a microbial community is better able to take advantage of more favorable energetics in a warmer soil profile. These issues are particularly important for large SOM reservoirs, such as those in the boreal biome. To address these issues, we collected soils in organic horizons from two forested sites along the Newfoundland-Labrador Boreal Ecosystem Latitude Transect (NL-BELT) in eastern Canada. Sites differ in latitude and mean annual temperature, but are similar in forest cover and soil type. We incubated humified Oe+Oa materials and replaced Oi with low or high C:N coniferous litter possessing a distinct δ13C signature for 120 days at 15°C and 20°C. During the incubation, we assessed respiratory CO2 losses and its origin via δ13C of CO2, microbial biomass, and the activity of multiple exo-enzymes associated with the mineralization of slow-turnover and more labile substrates. As predicted by enzyme kinetics, warming positively influenced respiratory loss and the proportion of CO2 derived from more humified SOM, particularly in late stages of the incubation. We observed no interaction effect of warming and Oi C:N on respired CO2 or microbial biomass C or N in soil from either site. Oi C:N influenced respiratory loss from higher latitude soils, with lower C:N Oi input dampening respiration rates early in the incubation, and promoting it at later stages. Late in the incubation, when the positive effect of warming on CO2 release from more humified SOM was most pronounced, the warming-induced increase in phenol oxidase activity was further enhanced when Oi material had a relatively low C:N by factors of 1.87 and 17 for lower vs

  5. Growth and nutrition of cacao seedlings influenced by zinc application in soil

    Science.gov (United States)

    Levels of Zn in tropical soils profoundly influences growth and nutrition of tree crops . Research was undertaken to assess the effect of soil Zn on growth and nutrition of clonal cacao tree seedlings of PH 16. Three acidic Oxisol soils differing in texture were used with nine doses of Zn (0, 1, 2, ...

  6. Influence of olive oil mill waste amendment on fate of oxyfluorfen in Southern Spain soils

    Science.gov (United States)

    The influence of olive oil mill waste (OOMW) amendment on soil processes affecting the herbicide oxyfluorfen (2-chloro-4-trifluoromethylphenyl-3-ethoxy-4-nitrophenyl ether) in two soils (P2 and SJ) was assessed under laboratory conditions. The soils used were from two diverse locations in Guadalqui...

  7. A study of factors influencing advanced puberty

    Directory of Open Access Journals (Sweden)

    Yong Jun Park

    2010-02-01

    Full Text Available Purpose : The purpose of this study was to evaluate the timing of puberty and the factors inducing advanced puberty in elemental school students of low grades. Methods : The 1st, 2nd, and 3rd grade elemental students from the Goyang province were randomly selected, and their sexual maturation rate was assessed by physical examination. After obtaining an informed consent, a questionnaire was administered to the parents; eating habits, lifestyle, use of growth-inducing medication, and present illness of the students were evaluated to determine the factors that induced advanced puberty. The data were statistically analyzed. Results : We selected 170 children and the girls:boys sex ratio was 1.2:1. Two 9-year-old boys were in genital stage 2. Two (14.3% 6-year-old girls, 6 (19.4% 7-year-old girls, 15 (39.6% 8-year-old girls, and 4 (57.1% 9-year-old girls were in breast stage 2. The average pubertal timing predicted for girls was 9.11¡?#?.86; years. The main factors influencing pubertal timing were obesity scale, frequency of eating fast food, and the use of growth-inducing medication. A high rating on the obesity scale and high frequency of eating fast food indicated advanced stage of puberty. Growth-inducing medication induced puberty through obesity. Conclusion : We proposed that predictive average pubertal timing in girls was 9.11¡?#?.86; years, which was consistent with the previously reported findings from abroad. The significant influencing factors in advanced puberty were obesity scale and frequency of fast food.

  8. The Influence of Time Scale on the Quantitative Study of Soil and Water Conservation Effect of Grassland

    Institute of Scientific and Technical Information of China (English)

    Xiaoxia; WU; Zhujun; GU

    2015-01-01

    Quantitative analysis of time scale effects is conducive to further understanding of vegetation water and soil conservation mechanism.Based on the observation data of the grass covered and bare soil( control) experimental plots located in Hetian Town,Changting County of Fujian Province from 2007 to 2010,the characteristics of 4 parameters( precipitation,vegetation,RE and SE) were analyzed at precipitation event,month,season,and annual scales,and then the linear regression models were established to describe the relationships between RE( SE)and its influencing factors of precipitation and vegetation. RE( SE) means the ratio of runoff depth( soil loss) of grass covered plot to that of the control plot. Results show that these 4 parameters presented different magnitude and variation on different time scales. RE and SE were relatively stable either within or among different time scales due to their ratios reducing the influence of other factors. The coupling of precipitation and vegetation led to better water conservation effect at lower RE( 0. 7) REs at precipitation event scale as well as at annual scale( R2> 0. 78). For the soil conservation effect,precipitation or / and vegetation was / were the dominated influence factor( s) at precipitation event and annual scales,and the grass LAI could basically describe the positive conservation effect( SE 0. 55),while the maximum 30 min intensity( I30) could describe the negative conservation effect more accurately( SE >1,R2> 0. 79). More uncertainties( R2≈0. 4) exist in the models of both RE and SE at two moderate time scales( month and season). Consequently,factors influencing water and soil conservation effect of grass present different variation and coupling characteristics on different time scales,indicating the importance of time scale at the study on water and soil conservation.

  9. Soil influence on Carignane wine quality in the AOC Priorat, Northeast Spain

    Science.gov (United States)

    Nadal, Montserrat; Sanchez Ortiz, Antoni; Biel, Carme

    2014-05-01

    The impact of global warming obviously varies according to the type of wine produced and the geographical location. The importance of understanding climate variability and soil water holding capacity is especially important in vineyards growing in steep slopes. Texture and soil depth are factors that influence the accumulation of water and, therefore, its influence on grapes ripening. The study was carried out during 2009 and 2010 vintages in two regions El Molar (EM) and Porrera (PO). 5 different parcels located in the AOC Priorat, selected by having different soil texture, facing slope orientation and altitude: EMDA, EMBA, POMO, POME and PODA. Weather stations located in each vineyard recorded climate data (temperature, humidity, rainfall, radiation, wind speed and direction). Tukey test was applied for post-hocanalysis (SPSS statistical package, version 17.0) between plots. Climatic data revealed 2009 as a warmer vintage comparing with the temperate 2010. Porrera region resulted in lower Temperature, VPD and GDD. Soil analysis revealed EMDA as a parcel having the finest texture. In Porrera the highest and steepest vineyard (PODA) show the higher amount of gravels and stones; whilst POMO has a balance between fine elements and stones. Topsoil and subsoil layers are notably different in the POME parcel. The two plots PODA and EMDA are those with major differences between berry weights within the two years of study, indicating a greater variability. EMDA has the largest grape production, regardless of the vintage probably due to the fine soil texture. At the end of the maturation period, the ratio SFT / kg was higher in EMDA and PODA, corresponding with a greater leaf area in EMDA. In general the two plots are more irregular, with greater differences over the years with higher rainfall (2010) compared to dry years (2009), where the ratios do not show much difference. Concerning Ravaz-Index, the most unbalanced vigour corresponds to EMDA (this explains major

  10. Spatially explicit analysis of metal transfer to biota: influence of soil contamination and landscape.

    Directory of Open Access Journals (Sweden)

    Clémentine Fritsch

    Full Text Available Concepts and developments for a new field in ecotoxicology, referred to as "landscape ecotoxicology," were proposed in the 1990s; however, to date, few studies have been developed in this emergent field. In fact, there is a strong interest in developing this area, both for renewing the concepts and tools used in ecotoxicology as well as for responding to practical issues, such as risk assessment. The aim of this study was to investigate the spatial heterogeneity of metal bioaccumulation in animals in order to identify the role of spatially explicit factors, such as landscape as well as total and extractable metal concentrations in soils. Over a smelter-impacted area, we studied the accumulation of trace metals (TMs: Cd, Pb and Zn in invertebrates (the grove snail Cepaea sp and the glass snail Oxychilus draparnaudi and vertebrates (the bank vole Myodes glareolus and the greater white-toothed shrew Crocidura russula. Total and CaCl(2-extractable concentrations of TMs were measured in soils from woody patches where the animals were captured. TM concentrations in animals exhibited a high spatial heterogeneity. They increased with soil pollution and were better explained by total rather than CaCl(2-extractable TM concentrations, except in Cepaea sp. TM levels in animals and their variations along the pollution gradient were modulated by the landscape, and this influence was species and metal specific. Median soil metal concentrations (predicted by universal kriging were calculated in buffers of increasing size and were related to bioaccumulation. The spatial scale at which TM concentrations in animals and soils showed the strongest correlations varied between metals, species and landscapes. The potential underlying mechanisms of landscape influence (community functioning, behaviour, etc. are discussed. Present results highlight the need for the further development of landscape ecotoxicology and multi-scale approaches, which would enhance our

  11. Factors influencing seed germination in Cerrado grasses

    Directory of Open Access Journals (Sweden)

    Rosana Marta Kolb

    2016-03-01

    Full Text Available Few studies address the ecology of herbs of Cerrado grasslands, which are ecosystems where the long dry season, high temperatures, insolation, fire and invasive grasses greatly influencing germination and the establishment of plants. We assessed germination of 13 species of Poaceae from Cerrado grasslands under nursery conditions or in germination chambers, the latter with i recently collected seeds and seeds after six months storage, ii under constant and alternating temperatures, and iii in the presence and absence of light. Germinability, mean germination time (MGT and required light were quantified to elucidate factors involved in successful germination. Germinability was low for most grasses, probably because of low seed viability. For most species, germinability and MGT were not altered by seed storage. Germination percentages were higher at alternating temperatures and in the presence of light, factors that are more similar to natural environmental situations compared with constant temperature or the absence of light. Our findings indicate that alternating temperatures and light incidence are key factors for germination of species of Poaceae. The maintenance of these environmental factors, which are crucial for the conservation of Cerrado grasslands, depends on appropriate management interventions, such as fire management and the control of biological invasion.

  12. Factors Influencing Acceptance Of Contraceptive Methods

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    Anita Gupta

    1997-04-01

    Full Text Available Research Problem: What are the factors influencing acceptance of contraceptive methods.Objective: To study the determinants influencing contra­ceptive acceptance.Study design: Population based cross - sectional study.Setting: Rural area of East DelhiParticipants: Married women in the reproductive age group.Sample:Stratified sampling technique was used to draw the sample.Sample Size: 328 married women of reproductive age group.Study Variables: Socio-economic status, Type of contraceptive, Family size, Male child.Outcome Variables: Acceptance of contraceptivesStatistical Analysis: By proportions.Result: Prevalence of use of contraception at the time of data collection was 40.5%. Tubectomy and vasectomy were most commonly used methods. (59.4%, n - 133. Educational status of the women positively influenced the contraceptive acceptance but income did not. Desire for more children was single most important deterrent for accepting contraception.Recommendations:(i             Traditional method of contraception should be given more attention.(ii            Couplesshould be brought in the contraceptive use net at the early stage of marriage.

  13. Landslide forecasting and factors influencing predictability

    Science.gov (United States)

    Intrieri, Emanuele; Gigli, Giovanni

    2016-11-01

    Forecasting a catastrophic collapse is a key element in landslide risk reduction, but it is also a very difficult task owing to the scientific difficulties in predicting a complex natural event and also to the severe social repercussions caused by a false or missed alarm. A prediction is always affected by a certain error; however, when this error can imply evacuations or other severe consequences a high reliability in the forecast is, at least, desirable. In order to increase the confidence of predictions, a new methodology is presented here. In contrast to traditional approaches, this methodology iteratively applies several forecasting methods based on displacement data and, thanks to an innovative data representation, gives a valuation of the reliability of the prediction. This approach has been employed to back-analyse 15 landslide collapses. By introducing a predictability index, this study also contributes to the understanding of how geology and other factors influence the possibility of forecasting a slope failure. The results showed how kinematics, and all the factors influencing it, such as geomechanics, rainfall and other external agents, are key concerning landslide predictability.

  14. Variations on Soil Salinity and Sodicity and Its Driving Factors Analysis under Microtopography in Different Hydrological Conditions

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-05-01

    Full Text Available Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravates the soil salinization under microtopography in dry condition. In this study, the differences in surface soil salinity–sodicity (0–10 cm between dry year and wet year were compared, and the relationship between soil salinity–sodicity and environment factors such as ground elevation, surface ponding time, surface ponding depth, and soil moisture at four soil layers (0–10, 10–30, 30–60, and 60–100 cm were analyzed using redundancy analysis (RDA and simple correlation analysis (Pearson analysis for two different hydrological years. Analyzed soil salinity–sodicity parameters include soluble ions (Na+, K+, Ca2+, Mg2+, CO32−, HCO3−, Cl− and SO42−, salt content (SC, electrical conductivity (EC, sodium adsorption ratio (SAR, and pH. Results showed that values of SAR, Cl−, and SO42− were significantly higher in dry year than in wet year, while Ca2+, Mg2+, K+, and HCO3− showed the opposite results. Values of Na+, CO32−, and EC were significantly higher at higher ground elevation gradient (20–40 cm in dry year than wet year. Redundancy analysis indicated that spatial distributions and variations of salinity and sodicity in surface soil layer were related with environmental factors of ponding depth, ponding time and ground elevation in wet year, and they were related with ground elevation, ponding depth, ponding time, and soil moisture at 30–60 and 60–100 cm soil layer in dry year. Ponding depth and ground elevation rank first and second as the influential factors of the spatial distribution and variation of soil salinity

  15. Correlation Between Soil Water Retention Capability and Soil Salt Content

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capability were studied by the methods of correlation and path analyses. The results indicated that < 0.02mm physical clay and soil salt content were the main factors influencing soil moisture retention capability. At soil suction of 30~50 kPa, the soil salt content would be the dominant factor.

  16. 土壤水蚀的环境效应:影响因素、研究热点与评价指标的评述%Environmental Impacts of Soil Water Erosion: A Review of Influencing Factors, Hot Research Topics and Evaluation Indices.

    Institute of Scientific and Technical Information of China (English)

    吕一河; 刘国华; 冯晓明

    2011-01-01

    Soil erosion being an important earth surface process, its environmental impact has aroused wide attention globally world over. From the angle of its influencing factors and basic principles of the generation of its environmental effects,the processes of soil water erosion were analyzed, leading to the assumption that soil water erosion is a "passive" or "secondary" process, which is affected and restrained by natural factors and human activities. The initiation and development of soil water erosion process will also act on local and allopatric environmental systems, demonstrating a series of environmental effects. The researches oriented towards environmental effects of soil water erosion are focused mainly on effects of soil water erosion on soil quality, plant productivity and vegetation restoration, non-point source pollution risk, carbon cycling and global change. An index system for evaluation of environmental effects of soil water erosion can be established and formed of four major aspects, i.e. water, soil, atmosphere and biology. It is, however, very difficult to formulate a standardized index system adoptable to all geographic environmental conditions and scenarios due to variability of research objectives and intrinsic spatial differentiation of the earth surface. In contrast, the modular formulation approach, which integrates basic indices with optional ones, is more operable. Specific indices and approaches to acquisition and analysis of their data are all scale dependent.%针对土壤水蚀过程,从其影响因素和环境效应产生的基本原理角度进行了分析,认为土壤水蚀是一个"受动"或"次生"过程,受到自然和人类活动因素的影响和制约;土壤水蚀的发生、发展也会影响本地和异地环境系统,表现出一系列环境效应.针对土壤水蚀环境效应的研究主要集中在水蚀过程对土壤质量、植物生产力与植被恢复、非点源污染风险、碳循环及全球变

  17. Removal of a mixture of pesticides by a Streptomyces consortium: Influence of different soil systems.

    Science.gov (United States)

    Fuentes, María S; Raimondo, Enzo E; Amoroso, María J; Benimeli, Claudia S

    2017-04-01

    Although the use of organochlorine pesticides (OPs) is restricted or banned in most countries, they continue posing environmental and health concerns, so it is imperative to develop methods for removing them from the environment. This work is aimed to investigate the simultaneous removal of three OPs (lindane, chlordane and methoxychlor) from diverse types of systems by employing a native Streptomyces consortium. In liquid systems, a satisfactory microbial growth was observed accompanied by removal of lindane (40.4%), methoxychlor (99.5%) and chlordane (99.8%). In sterile soil microcosms, the consortium was able to grow without significant differences in the different textured soils (clay silty loam, sandy and loam), both contaminated or not contaminated with the OPs-mixture. The Streptomyces consortium was able to remove all the OPs in sterile soil microcosm (removal order: clay silty loam > loam > sandy). So, clay silty loam soil (CSLS) was selected for next assays. In non-sterile CSLS microcosms, chlordane removal was only about 5%, nonetheless, higher rates was observed for lindane (11%) and methoxychlor (20%). In CSLS slurries, the consortium exhibited similar growth levels, in the presence of or in the absence of the OPs-mixture. Not all pesticides were removed in the same way; the order of pesticide dissipation was: methoxychlor (26%)>lindane (12.5%)>chlordane (10%). The outlines of microbial growth and pesticides removal provide information about using actinobacteria consortium as strategies for bioremediation of OPs-mixture in diverse soil systems. Texture of soils and assay conditions (sterility, slurry formulation) were determining factors influencing the removal of each pesticide of the mixture.

  18. Characterization and nutrient release from silicate rocks and influence on chemical changes in soil

    Directory of Open Access Journals (Sweden)

    Douglas Ramos Guelfi Silva

    2012-06-01

    Full Text Available The expansion of Brazilian agriculture has led to a heavy dependence on imported fertilizers to ensure the supply of the growing food demand. This fact has contributed to a growing interest in alternative nutrient sources, such as ground silicate rocks. It is necessary, however, to know the potential of nutrient release and changes these materials can cause in soils. The purpose of this study was to characterize six silicate rocks and evaluate their effects on the chemical properties of treated soil, assessed by chemical extractants after greenhouse incubation. The experimental design consisted of completely randomized plots, in a 3 x 6 factorial scheme, with four replications. The factors were potassium levels (0-control: without silicate rock application; 200; 400; 600 kg ha-1 of K2O, supplied as six silicate rock types (breccia, biotite schist, ultramafic rock, phlogopite schist and two types of mining waste. The chemical, physical and mineralogical properties of the alternative rock fertilizers were characterized. Treatments were applied to a dystrophic Red-Yellow Oxisol (Ferralsol, which was incubated for 100 days, at 70 % (w/w moisture in 3.7 kg/pots. The soil was evaluated for pH; calcium and magnesium were extracted with KCl 1 mol L-1; potassium, phosphorus and sodium by Mehlich 1; nickel, copper and zinc with DTPA; and the saturation of the cation exchange capacity was calculated for aluminum, calcium, magnesium, potassium, and sodium, and overall base saturation. The alternative fertilizers affected soil chemical properties. Ultramafic rock and Chapada mining byproduct (CMB were the silicate rocks that most influenced soil pH, while the mining byproduct (MB led to high K levels. Zinc availability was highest in the treatments with mining byproduct and Cu in soil fertilized with Chapada and mining byproduct.

  19. Plant host and soil origin influence fungal and bacterial assemblages in the roots of woody plants.

    Science.gov (United States)

    Bonito, Gregory; Reynolds, Hannah; Robeson, Michael S; Nelson, Jessica; Hodkinson, Brendan P; Tuskan, Gerald; Schadt, Christopher W; Vilgalys, Rytas

    2014-07-01

    Microbial communities in plant roots provide critical links between above- and belowground processes in terrestrial ecosystems. Variation in root communities has been attributed to plant host effects and microbial host preferences, as well as to factors pertaining to soil conditions, microbial biogeography and the presence of viable microbial propagules. To address hypotheses regarding the influence of plant host and soil biogeography on root fungal and bacterial communities, we designed a trap-plant bioassay experiment. Replicate Populus, Quercus and Pinus plants were grown in three soils originating from alternate field sites. Fungal and bacterial community profiles in the root of each replicate were assessed through multiplex 454 amplicon sequencing of four loci (i.e., 16S, SSU, ITS, LSU rDNA). Soil origin had a larger effect on fungal community composition than did host species, but the opposite was true for bacterial communities. Populus hosted the highest diversity of rhizospheric fungi and bacteria. Root communities on Quercus and Pinus were more similar to each other than to Populus. Overall, fungal root symbionts appear to be more constrained by dispersal and biogeography than by host availability.

  20. Influence of climate warming and nitrogen deposition on soil phosphorus composition and phosphorus availability in a temperate grassland, China

    Institute of Scientific and Technical Information of China (English)

    GuangNa ZHANG; ZhenHua CHEN; AiMing ZHANG; LiJun CHEN; ZhiJie WU

    2014-01-01

    Climate warming and nitrogen (N) deposition change ecosystem processes, structure, and functioning whereas the phosphorus (P) composition and availability directly influence the ecosystem structure under condi-tions of N deposition. In our study, four treatments were designed, including a control, diurnal warming (DW), N deposition (ND), and combined warming and N deposition (WN). The effects of DW, ND, and WN on P composition were studied by 31P nuclear magnetic resonance (31P NMR) spectroscopy in a temperate grassland region of China. The results showed that the N deposition decreased the soil pH and total N (TN) concentration but increased the soil Olsen-P concentration. The solution-state 31P NMR analysis showed that the DW, ND and WN treatments slightly decreased the proportion of orthophosphate and increased that of the monoesters. An absence of myo-inositol phosphate in the DW, ND and WN treatments was observed compared with the control. Furthermore, the DW, ND and WN treatments significantly decreased the recovery of soil P in the NaOH-EDTA solution by 17%-20%. The principal component analysis found that the soil pH was positively correlated with the P recovery in the NaOH-EDTA solution. Therefore, the decreased soil P recovery in the DW and ND treatments might be caused by an indirect influence on the soil pH. Additionally, the soil moisture content was the key factor limiting the available P. The positive correlation of total carbon (TC) and TN with the soil P composition indicated the influence of climate warming and N deposition on the biological processes in the soil P cycling.

  1. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    Science.gov (United States)

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P carbon contents and other environmental factors (P > 0.05).

  2. Intrinsic and extrinsic factors influencing large African herbivore movements

    NARCIS (Netherlands)

    Venter, J.A.; Prins, H.H.T.; Mashanova, A.; Boer, de W.F.; Slotow, R.

    2015-01-01

    Understanding environmental as well as anthropogenic factors that influence large herbivore ecological patterns and processes should underpin their conservation and management. We assessed the influence of intrinsic, extrinsic environmental and extrinsic anthropogenic factors on movement behaviour o

  3. [Effects of soil factors on arbuscular mycorrhizae (AM) fungi around roots of wild plants].

    Science.gov (United States)

    Gai, Jingping; Liu, Runjin

    2003-03-01

    150 rhizospheric soil samples were collected from 45 wild plants distributed in Shandong Province during 1995-1997. More than forty species of AM fungi were isolated, and the effects of some soil factors on AM fungi were also investigated. It was proved that soil conditions were important factors to the colonization, growth, and distribution of AM fungi. Spore numbers were highest in brown earth, and lowest in alkali-saline soil. Glomus occurred in all types of soil. The occurrence frequency of Gigaspora and Scutellospora was much higher in brown earth. The distribution of AM fungi was also affected by soil pH. Glomus occurred in soil with a wide pH range. The greater of soil alkalinity, the more Glomus were found, while the greater of soil acidity, the more Acaulospora were isolated. Scutellospora occurred mostly in soil with pH of 6.0-7.0, and Gigaspora distributed mainly in acid soil.

  4. Hydrothermal carbonization of biomass from landscape management - Influence of process parameters on soil properties of hydrochars.

    Science.gov (United States)

    Röhrdanz, Michael; Rebling, Tammo; Ohlert, Jan; Jasper, Jan; Greve, Thomas; Buchwald, Rainer; von Frieling, Petra; Wark, Michael

    2016-05-15

    Besides pyrolysis the technology of hydrothermal carbonization (HTC) is tested to produce hydrochars for soil improvement. The chemical and physical properties of the hydrochars mainly depend on the feedstock and the process parameters reaction time and process temperature. Systematic investigations on the influences of these process parameters on soil properties of hydrochars like water holding capacity (WHC) and cation exchange capacity (CEC) are missing. In this study, a rush-rich biomass was carbonized within defined HTC process conditions under variation of reaction time and process temperature to produce hydrochars. Analysis of WHC, CEC, the elemental composition and Fourier-transform infrared spectroscopy (FT-IR) were performed to evaluate the influence of HTC process conditions on the pedological hydrochar properties. The results indicated that at increasing reaction severity (reaction time and process temperature) WHC and CEC decreased as well as the elemental O/C ratio. The decrease of WHC and CEC is based on the decrease of the hydrochar surface polarity. However, even the lowest WHC and CEC of investigated hydrochars still exceeded those of pure quartz sand by factors of 5-10. An application of hydrochars produced at severe HTC conditions could improve WHC and CEC of sandy soils. This has to be investigated in further studies.

  5. The influence of tree species composition on the storage and mobility of semivolatile organic compounds in forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Komprdová, Klára, E-mail: komprdova@recetox.muni.cz [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Komprda, Jiří [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Menšík, Ladislav [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Vaňková, Lenka [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Kulhavý, Jiří [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Nizzetto, Luca [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Norwegian Institute for Water Research, Gaustadalleen 21, NO-0349 Oslo (Norway)

    2016-05-15

    Soil contamination with PCBs and PAHs in adjacent forest plots, characterized by a distinct composition in tree species (spruce only, mixed and beech only), was analyzed to investigate the influence of ecosystem type on contaminant mobility in soil under very similar climate and exposure conditions. Physical-chemical properties and contaminant concentrations in litter (L), organic (F, H) and mineral (A, B) soil horizons were analyzed. Contaminant distribution in the soil core varied both in relation to forest type and contaminant group/properties. Contaminant mobility in soil was assessed by examining the ratios of total organic carbon (TOC)-standardized concentrations across soil horizons (Enrichment factors, EF{sub TOC}) and the relationship between EF{sub TOC} and the octanol-water equilibrium partitioning coefficient (K{sub OW}). Contaminant distribution appeared to be highly unsteady, with pedogenic/biogeochemical drivers controlling contaminant mobility in organic layers and leaching controlling accumulation in mineral layers. Lighter PCBs displayed higher mobility in all forest types primarily controlled by leaching and, to a minor extent, diffusion. Pedogenic processes controlling the formation of soil horizons were found to be crucial drivers of PAHs and heavier PCBs distribution. All contaminants appeared to be more mobile in the soil of the broadleaved plot, followed by mixed canopy and spruce forest. Increasing proportion of deciduous broadleaf species in the forest can thus lead to faster degradation or the faster leaching of PAHs and PCBs. The composition of humic substances was found to be a better descriptor of contaminant concentration than TOC. - Highlights: • Tree species composition influences vertical distribution of PCBs and PAHs in soils. • PCBs and PAHs were more mobile in the soil of the broadleaved plot. • Low molecular weight PCBs displayed higher mobility in all forest types. • Humic substances were important descriptors of

  6. Influence of vegetation, soil and antecedent soil moisture on the variability of surface runoff coefficients at the plot scale in the eastern alps

    Science.gov (United States)

    Chifflard, P.; Kohl, B.; Markart, G.; Kirnbauer, R.

    2009-04-01

    Modelling the runoff of a catchment in a high spatial resolution, you need to know the potential of a single plot to generate surface runoff. The portion of surface runoff is highly significant for storm runoff events, accordingly, it mainly forms the hydrograph. In this study, the influence of vegetation, soil features and antecedent soil moisture on generating surface runoff at the plot scale have been analysed. To achieve an appropriate fit of the plots, a plot sizes between 50 and 400 m² were chosen. The rainfall intensities ranged between 10 mm/h and 100 mm/h. Based on 260 rain simulations with a transportable sprinkling instrumentation on representative plots in the eastern Alps (Austria, Italy, Germany), including investigations on land-use, vegetation cover and soil physical characteristics, various soil-vegetation complexes and their surface runoff processes have been be analysed. Additionally, we investigated flow paths, travel distance, infiltration hindrance, flow resistance and overland flow velocity. The soil water status was monitored by using TDR-probes, which had been installed in two profiles within the plot in different depths ranging from 5 cm to 40 cm. For every sprinkling experiment, a surface runoff coefficient was calculated as the ratio between total rainfall amount and surface runoff. With this substantial dataset, the regression analysis was used to examine the influence of the hydrological key factors as soil, vegetation and initial soil moisture condition on the distribution functions of the surface runoff coefficient. The first results show that the vegetation cover is very important for the surface runoff. If initial soils are covered by alpine or sub-alpine pioneering vegetation surface runoff can be found very scarce. If these initial soils are covered i.e. by subalpine nardus grasslands the surface runoff coefficients range from 0.1 up to 0.8. On the other hand it can be shown that soils with a high bulk density mainly generate

  7. Patterns of relative magnitudes of soil energy channels and their relationships with environmental factors in different ecosystems in Romania.

    Science.gov (United States)

    Ciobanu, Marcel; Popovici, Iuliana; Zhao, Jie; Stoica, Ilie-Adrian

    2015-12-01

    The percentage compositions of soil herbivorous, bacterivorous and fungivorous nematodes in forests, grasslands and scrubs in Romania was analysed. Percentages of nematode abundance, biomass and metabolic footprint methods were used to evaluate the patterns and relative size of herbivory, bacterial- and fungal-mediated channels in organic and mineral soil horizons. Patterns and magnitudes of herbivore, bacterivore and fungivore energy pathways differed for a given ecosystem type and soil depth according to the method used. The relevance of herbivore energy channel increased with soil depth due to higher contribution of root-feeders. Ectoparasites, sedentary parasites and epidermal cell and root hair feeders were the most important contributors to the total biomass and metabolic footprints of herbivores. Metabolic footprint method revealed the general dominance of bacterial-based energy channel in all five types of ecosystems. The influence of altitude and climatic factors on percentages of abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores decreased with soil depth, whereas the influence of humus content, cation-exchange capacity and base saturation increased. Vegetation, altitude, climate and soil physico-chemical characteristics are important factors that influenced the abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores.

  8. Patterns of relative magnitudes of soil energy channels and their relationships with environmental factors in different ecosystems in Romania

    Science.gov (United States)

    Ciobanu, Marcel; Popovici, Iuliana; Zhao, Jie; Stoica, Ilie-Adrian

    2015-12-01

    The percentage compositions of soil herbivorous, bacterivorous and fungivorous nematodes in forests, grasslands and scrubs in Romania was analysed. Percentages of nematode abundance, biomass and metabolic footprint methods were used to evaluate the patterns and relative size of herbivory, bacterial- and fungal-mediated channels in organic and mineral soil horizons. Patterns and magnitudes of herbivore, bacterivore and fungivore energy pathways differed for a given ecosystem type and soil depth according to the method used. The relevance of herbivore energy channel increased with soil depth due to higher contribution of root-feeders. Ectoparasites, sedentary parasites and epidermal cell and root hair feeders were the most important contributors to the total biomass and metabolic footprints of herbivores. Metabolic footprint method revealed the general dominance of bacterial-based energy channel in all five types of ecosystems. The influence of altitude and climatic factors on percentages of abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores decreased with soil depth, whereas the influence of humus content, cation-exchange capacity and base saturation increased. Vegetation, altitude, climate and soil physico-chemical characteristics are important factors that influenced the abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores.

  9. Laboratory assessment of the influence of the proportion of waste foundry sand on the geotechnical engineering properties of clayey soils

    CSIR Research Space (South Africa)

    Mgangira, Martin B

    2006-01-01

    Full Text Available Soil improvement can be achieved through mechanical stabilisation using industrial byproducts. Clayey soils were blended with waste foundry sand to examine its influence on the geotechnical engineering properties of the soils. The waste foundry sand...

  10. Influence of soil structure on contaminant leaching from injected slurry

    DEFF Research Database (Denmark)

    Amin, M. G. Mostofa; Pedersen, Christina Østerballe; Forslund, Anita;

    2016-01-01

    macropore flow paths. The slurry constituents that ended up in or near the macropore flow paths of the intact soil were presumably washed out relatively quickly in the first event. For the last three events the intact soil leached fewer microorganisms than the disturbed soil due to the bypassing effect...... and persistence of nitrogen, microorganisms (bacteriophage, E. coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after injection of swine slurry into either intact (structured) or disturbed (homogeneous repacked) soil. The slurry was injected into hexaplicate soil columns...... of water through the macropore flow path in the intact soil. Estrogen leached from the intact soil in the first event only, but for the disturbed soil it was detected in the leachates of last two events also. Leaching from the later events was attributed to higher colloid transport from the disturbed soils...

  11. Examinations of factors influencing toe grip strength.

    Science.gov (United States)

    Soma, Masayuki; Murata, Shin; Kai, Yoshihiro; Nakae, Hideyuki; Satou, Yousuke; Murata, Jun; Miyazaki, Junya

    2016-11-01

    [Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole.

  12. [Dynamic changes of soil ecological factors in Ziwuling secondary forest area under human disturbance].

    Science.gov (United States)

    Zhou, Zhengchao; Shangguan, Zhouping

    2005-09-01

    As a widespread natural phenomenon, disturbance is considered as a discrete event occurred in natural ecosystems at various spatial and temporal scales. The occurrence of disturbance directly affects the structure, function and dynamics of ecosystems. Forest logging and forestland assart, the common human disturbances in forest area, have caused the dynamic changes of forest soil ecological factors in a relatively consistent environment. A study on the dynamics of soil bulk density, soil organic matter, soil microbes and other soil ecological factors under different human disturbance (logging and assart, logging but without assart, control) were conducted in the Ziwuling secondary forest area. The results indicated that human disturbance had a deep impact on the soil ecological factors, with soil physical and chemical properties become bad, soil organic matter decreased from 2.2% to 0.8%, and soil stable aggregates dropped more than 30%. The quantity of soil microbes decreased sharply with enhanced human disturbance. Soil organic matter and soil microbes decreased more than 50% and 90%, respectively, and soil bulk density increased from 0.9 to 1.21 g x cm(-3) with increasing soil depth. Ditch edge level also affected the dynamics of soil factors under the same disturbance, with a better soil ecological condition at low-than at high ditch edge level.

  13. Factors responsible for the patchy distribution of natural soil water repellency in Mediterranean semiarid forest

    Science.gov (United States)

    Lozano, E.; Jiménez-Pinilla, P.; Mataix-Solera, J.; González-Pérez, J. A.; García-Orenes, F.; Torres, M. P.; Arcenegui, V.; Mataix-Beneyto, J.

    2012-04-01

    H and between SOM and pH for all except for Q. rotundifolia. However, the negative correlation found between pH and persistence of WR seems to be related to soil organic matter (SOM) content for all vegetal species. Glomalin exudates from arbuscular mycorrhizal fungi in soil revealed significant differences between species. However, the first results do not point to a direct relationship between EEG content and WR but to soil mineralogy or certain components within SOM pool i.e. litter debris degradation products or specific components within the glomalin extract, as main factors affecting soil WR. Nonetheless, since some samples with the same SOM content (including some under the same vegetation cover) showed different WR persistence, complementary research including a more detailed characterization of most soil functional fractions (SOM and clays) is planned in order to elucidat the main factors influencing the presence and persistence of WR in soils under Mediterranean semiarid forest. Keywords: Water repellency, hydrophobicity, easily extractable glomalin, mycelium, arbuscular mycorrhizal fungi.

  14. The influence of different soil management practices on auxin herbicide interactions with organic carbon in soil aggregate fractions

    Science.gov (United States)

    Schnitzler, Frauke; Haupt, Nadine; Burauel, Peter; Berns, Anne E.

    2010-05-01

    The influence of changing organic carbon contents in soils on the sorption and/or sequestration mechanisms of xenobiotics and their bioavailability are still not understood precisely. The present work discusses the turnover of a crop residue interacting with processes like mobilisation, binding and metabolism of an auxin herbicide in soil. The soil type was a haplic chernozem, available in three crop production regimes (low, normal and high) due to three types of fertilisation (none, mineral and mineral & organic) [1]. Two sets of experiments were conducted with undisturbed soil columns under field-like conditions. In the first set 14C-labelled maize straw was incorporated into the top soil and after three months incubation the herbicide benazolin was applied. In the second set the unlabelled maize straw was incorporated first, then 14C-labelled benazolin was added. Soil layers of 0-5 cm and 5-10 cm were fractionated in according to a soil aggregate fractionation procedure [2]. The content of organic carbon and the distribution of benazolin and its metabolites were detected in the gained soil fractions. In general, the specific organic carbon content and the specific 14C-activity of benazolin and its metabolites increased in the order from sand-sized though silt-sized to clay fraction due to increasing specific surface areas and sorption sites of the mineral particles. The highest sorption capacity of benazolin and its metabolites was detected in the soil layers of 0-5 cm with mineral fertilisation. In the 5-10 cm soil layers the binding capacity increased with increasing crop production. It was shown that more than half of the residual 14C-activity was not extractable. LC-MS/MS analysis of the extracts showed that the major components were benazolin and the relatively non-mobile thiazolin. The amount of benazolin in the extracts increased with increasing crop production, but decreased with increasing soil depth. These results indicate that maize straw amendment

  15. Patterns of Fusarium community structure and abundance in relation to spatial, abiotic and biotic factors in soil

    NARCIS (Netherlands)

    Yergeau, E.; Labour, K.; Hamel, C.; Vujanovic, V.; Nakano-Hylander, A.; Jeannotte, R.; St-Arnaud, M.

    2010-01-01

    Members of the Fusarium genus are important components of many plant-soil systems worldwide and are responsible for many crop diseases. Knowledge of the relative influence of biotic and abiotic factors on this genus is therefore of broad economic and ecological importance. In order to address this i

  16. Test speed and other factors affecting the measurements of tree root properties used in soil reinforcement models

    NARCIS (Netherlands)

    Cofie, P.; Koolen, A.J.

    2001-01-01

    Measured values of the mechanical properties of tree roots are found to be affected by a number of factors. Shear properties of tree roots are found to be partly influenced by size of the testing equipment, level of soil compaction, deformation of the root material and estimated width of the shear z

  17. Atmospheric dust additions as a soil formation factor

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Hernandez, J. L.; Ruoss, J.

    2009-07-01

    The Mediterranean area is distinguished by a least four features that determine the nature of its soils. These are its climate, its mountains, the addition of exogenous dust and ongoing anthropogenic effects. We here present three cases in which the influence of atmospheric dust additions can be detected in the soils of representative circum-Saharan contexts the Canary Islands, Betic intramontane depressions, and the Sierra Bermeja peridotite massif (Malaga). The unique position of the Canary Islands determines important rates of dust deposit, largely depending on position on the relief. the nature of the dust contrasts with the rocky substratum of the islands, and the marine and volcanic context can also affect the nature of the deposits. The numerous, extensive intramontane basins of the Betic Cordilleras act as large captors of atmospheric dust, with rates similar to those found in the Canary archipelago. The carbonate content of these exogenous additions represents a significant components that should be taken into account when establishing the carbonate accumulation regime in these soils. (Author) 13 refs.

  18. Soil Type, Soil Moisture, and Field Slope Influence the Horizontal Movement of Salmonella enterica and Citrobacter freundii from Floodwater through Soil.

    Science.gov (United States)

    Callahan, Mary Theresa; Micallef, Shirley A; Buchanan, Robert L

    2017-01-01

    Pathogens in soil are readily mobilized by infiltrating water to travel downward through the soil. However, limited data are available on the horizontal movement of pathogens across a field. This study used a model system to evaluate the influence of soil type, initial soil moisture content, and field slope on the movement of Salmonella enterica serovar Newport across a horizontal plane of soil under flooding conditions. Three soil types of varying clay content were moistened to 40, 60, or 80% of their maximum water-holding capacities and flooded with water containing 6 log CFU/ml Salmonella Newport and Citrobacter freundii , the latter being evaluated as a potential surrogate for S. enterica in future field trials. A two-phase linear regression was used to analyze the microbial populations recovered from soil with increasing distance from the flood. This model reflected the presence of lag distances followed by a quantifiable linear decrease in the population of bacteria as a function of the distance from the site of flooding. The magnitude of the lag distance was significantly affected by the soil type, but this was not attributable to the soil clay content. The rate of the linear decline with distance from the flood zone was affected by soil type, initial soil moisture content, and soil incline. As the initial soil moisture content increased, the rate of decline in recovery decreased, indicating greater bacterial transport through soils. When flooding was simulated at the bottom of the soil incline, the rate of decline in recovery was much greater than when flooding was simulated at the top of the incline. There was no significant difference in recovery between Salmonella Newport and C. freundii , indicating that C. freundii may be a suitable surrogate for Salmonella Newport in future field studies.

  19. Factors influencing career choice in anaesthesiology

    Directory of Open Access Journals (Sweden)

    Asha Tyagi

    2012-01-01

    Full Text Available Background: There is a shortage of anaesthesiologists in India. The factors that prompt medical students to opt for anaesthesiology as their career are not known; neither do we have any mechanism to know a student′s stress-bearing ability before he/she opts for a stressful career like anaesthesiology. We conducted an anonymous, questionnaire-based, cross-sectional survey among 200 post-graduate anaesthesiology students to know various factors that they considered while opting for this speciality, and also evaluated their stress-bearing ability using Antonovsky′s 13-point sense of coherence scale. Methods: Two-hundred anaesthesiology students were asked to complete a questionnaire regarding the factors they considered important while opting for anaesthesiology, also enumerated in order of importance the three most important factors that led to opting this career. Students also answered the questions in Antonovsky′s sense of coherence (SOC scale. Results: Economic security was considered by maximum number of students (67.7%, while intellectual stimulation/challenge offered by anaesthesiology was rated first in order of importance. Influence of doctor−patient relationship was not considered by large number of students. The weak SOC score (55 (25 th percentile was not greatly different than the mean SOC score (60 in the survey. Conclusion: Increasing the exposure of students to anaesthesiology at undergraduate level and building public awareness about the speciality will prompt more students to opt for the speciality, while career counselling with regard to specific needs of a speciality and ability of a student will help in opting the speciality that best suits the student′s personality.

  20. Factors influencing nurses' perceptions of occupational safety.

    Science.gov (United States)

    Samur, Menevse; Intepeler, Seyda Seren

    2017-01-02

    To determine nurses' perceptions of occupational safety and their work environment and examine the sociodemographic traits and job characteristics that influence their occupational safety, we studied a sample of 278 nurses. According to the nurses, the quality of their work environment is average, and occupational safety is insufficient. In the subdimensions of the work environment scale, it was determined that the nurses think "labor force and other resources" are insufficient. In the occupational safety subdimensions "occupational illnesses and complaints" and "administrative support and approaches," they considered occupational safety to be insufficient. "Doctor-nurse-colleague relationships," "exposure to violence," and "work unit" (eg, internal medicine, surgical, intensive care) are the main factors that affect occupational safety. This study determined that hospital administrations should develop and immediately implement plans to ameliorate communication and clinical precautions and to reduce exposure to violence.

  1. Factors Influencing Sulfinatodehalogenation Reactions of Perhalocarbons

    Institute of Scientific and Technical Information of China (English)

    WU,Kai(吴恺); CHEN,Qing-Yun(陈庆云)

    2004-01-01

    The study on the factors influencing sulfinatodehalogenation of perfluorohexyl chloride plus octene-1 by using Na2S2O4/NaHCO3 discovered that among the various solvents tested(e.g.Me2SO,NMP,DMAc,CH3CN,CH3CN/H2O)at different temperatures,Me2SO was found to be the most suitable solvent and the conversion of the chloride was very dependent on the reaction temperature.When Me2SO was used in the reaction of perfluoroalkyl iodides,the reaction temperature could be decreased by 20℃ as compared with that carried out in CH3CN/H2O to reach the comparable yields.

  2. Factors influencing presence in virtual worlds.

    Science.gov (United States)

    Chow, Meyrick C M

    2012-01-01

    Virtual worlds are showing potential as an effective platform for a variety of activities, including learning. The concept of presence (the sensation of "being there" in a mediated environment) has received substantial attention from the virtual reality community, and the effectiveness of virtual worlds has often been linked to the feelings of presence reported by their users. The present study examined the effects of attitude and perceived ease of use on sense of presence in Second Life, which is one of the most known and used virtual worlds. Based on data from a survey of 206 nursing students, hypotheses are empirically tested. Findings suggest that users' attitude toward using Second Life and their perceived ease of use of it have a positive effect on their sense of presence in the virtual environment. This study advances our understanding of factors influencing presence in virtual worlds.

  3. Factors influencing consumer dietary health preventative behaviours

    Directory of Open Access Journals (Sweden)

    Ritson Christopher

    2006-09-01

    Full Text Available Abstract Background The deterioration of the health status of the Romanian population during the economic transition from a centrally planned to a free market economy has been linked to lifestyles factors (e.g. diet regarded as a main determinants of the disparity in life expectancy between Eastern and Western Europe. Reforms in the health care system in this transition economy aim to focus on preventive action. The purpose of this study was to identify the factors that impact on the individual decision to engage in Dietary Health Preventive Behaviour (DHPB and investigate their influence in the context of an adapted health cognition model. Methods A population-based study recruited 485 adult respondents using random route sampling and face-to-face administered questionnaires. Results and discussion Respondents' health motivation, beliefs that diet can prevent disease, knowledge about nutrition, level of education attainment and age have a positive influence on DHPB. Perceived barriers to healthy eating have a negative impact on alcohol moderation. The information acquisition behaviour (frequency of reading food labels is negatively predicted by age and positively predicted by health motivation, education, self-reported knowledge about nutrition and household financial status. A significant segment of respondents believe they are not susceptible to the elicited diseases. Health promotion strategies should aim to change the judgments of health risk. Conclusion The adaptation of the Health Belief Model and the Theory of Health Preventive Behaviour represents a valid framework of predicting DHPB. The negative sign of perceived threat of disease on DHPB may suggest that, under an income constraint, consumers tend to trade off long-term health benefits for short-term benefits. This cautions against the use of negative messages in public health campaigns. Raising the awareness of diet-disease relationships, knowledge about nutrition (particularly

  4. Local and regional factors influencing bacterial community assembly.

    Science.gov (United States)

    Lindström, Eva S; Langenheder, Silke

    2012-02-01

    The classical view states that microbial biogeography is not affected by dispersal barriers or historical events, but only influenced by the local contemporary habitat conditions (species sorting). This has been challenged during recent years by studies suggesting that also regional factors such as mass effect, dispersal limitation and neutral assembly are important for the composition of local bacterial communities. Here we summarize results from biogeography studies in different environments, i.e. in marine, freshwater and soil as well in human hosts. Species sorting appears to be the most important mechanism. However, this result might be biased since this is the mechanism that is easiest to measure, detect and interpret. Hence, the importance of regional factors may have been underestimated. Moreover, our survey indicates that different assembly mechanisms might be important for different parts of the total community, differing, for example, between generalists and specialists, and between taxa of different dispersal ability and motility. We conclude that there is a clear need for experimental studies, first, to clearly separate regional and local factors in order to study their relative importance, and second, to test whether there are differences in assembly mechanisms depending on different taxonomic or functional groups.

  5. Factors influencing women's decision making in hysterectomy.

    Science.gov (United States)

    Janda, Monika; Armfield, Nigel R; Page, Katie; Kerr, Gayle; Kurz, Suzanne; Jackson, Graeme; Currie, Jason; Weaver, Edward; Yazdani, Anusch; Obermair, Andreas

    2017-09-12

    To explore factors influencing how well-informed women felt about hysterectomy, influences on their decision making, and on them receiving a less-invasive alternative to open surgery. Online questionnaire, conducted in 2015-2016, of women who had received a hysterectomy in Australia, in the preceding two years. Questionnaires were completed by 2319/6000 women (39% response). Most women (n=2225; 96%) felt well-informed about hysterectomy. Women were more aware of the open abdominal approach (n=1798; 77%), than of less-invasive vaginal (n=1552; 67%), laparoscopic (n=1540; 66%), laparoscopic-assisted (n=1303; 56%), and robotic approaches (n=289; 12%). Most women (n=1435; 62%) reported their gynaecologist was the most influential information source. Women who received information about hysterectomy from a GP (OR=1.47; 95% CI 1.15-1.90), or from a gynaecologist (OR=1.3; 95% CI 1.06-1.58), were more likely to feel better informed (p<0.01). This study is important because it helps clinicians, researchers and health policy makers to understand why many women still receive an open abdominal approach despite many learned societies recommending to avoid it if possible. Additional information, or education about avoiding open abdominal approach where possible may lead to a greater number of women receiving less-invasive types of hysterectomy in the future. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  6. Influence of Vegetation Type and Land Management on Soil Organic Carbon Fractions in Gonbad Watershed, Hamadan

    Directory of Open Access Journals (Sweden)

    Khadije Salarinik

    2017-03-01

    Full Text Available Introduction: Soil organic matter is influenced strongly by vegetation cover and management, therefore it is proposed as the main indicator of soil quality and health. The changes in soil organic matter status occur much more rapidly in the labile pools than in organic C. Thus, labile pools can be used as early indicators of changes in total organic matter that will become more obvious in the longer term here. In addition, the labile fraction has a disproportionately large effect on nutrient-supplying capacity and structural stability of soils. Land management as well as soil and environmental conditions lead to the deployment of different plant communities in rangeland ecosystems, which in turn may have different effects on soil quality indicators. The main objective of this research was to investigate the influence of different vegetation covers on the quantity and quality of soil organic carbon fractions in Gonbad experimental watershed, Hamadan. Moreover, the seasonal changes of selected soil carbon fractions were investigated. Materials and Methods: Paired Gonbad watershed in Hamedan consists of two sub-basins: in control sub-basin no grazing management is applied, while in protected sub-basin, grazing has been restricted to a very short period in late autumn since 2002. Average annual precipitation and average annual temperature in the area are 304.4 mm and 9.5 °C, respectively (5. The soil cover of the watershed consists of TypicCalcixerepts, TypicHaploxerepts and Lithic Xerorthents (9. Five different vegetation typesof which, grasses (G, Astragalus-Bromus (A-B, Astragalus-Artemisia (A-A, Astragalus-Lactuca (A-L in protected sub-basin, and Astragalus-Euphorbia (A-E in control sub-basin, were selected. In addition, a formerly cultivated hilly land outside the watershed, now under rainfed wheat farming (RW was selected as a non-pasture vegetation type. All of the six vegetation types were similar in terms of soil parent materials and slope

  7. Biological factors influencing nitrogen transformation in wheat fields of lime concreted black soils and their response to different nitrogen supplications%影响砂姜黑土麦田土壤氮素转化的生物学因素及其对供氮量的响应

    Institute of Scientific and Technical Information of China (English)

    熊淑萍; 丁世杰; 王小纯; 马新明; 吴懿鑫; 杜盼; 于旭昊

    2016-01-01

    Lime concretion black soil is a typical low-yield field soil in China. It has heavy clay structure and poor permeability, which cause imbalances in effective nutrient supply, low capacity soil nutrient supply and poor production performance. In order to improve crop yields, chemical fertilizer (especially nitrogen fertilizer) has been excessively applied during production seasons. This has led to wastage of agricultural resources and environmental pollution. Soil microbes have always played a predominant role in the processes of soil nitrogen transformation. To provide scientific basis for directional adjustments to control the processes of soil nitrogen transformation, improve nitrogen use efficiency and reduce related negative effects, the processes and mechanisms of nitrogen transformation driven by soil microorganisms were studied. A filed experiment was carried out from 2012 to 2015 in Xiangcheng, Henan Province, China. The experimental setup was a single factorial design with four nitrogen rates (0 kg·hm-2, 120 kg·hm-2, 225 kg·hm-2 and 330 kg·hm-2). The biochemical action intensity of soil nitrogen transformation microorganisms (ammonification, nitrification and denitrification), urease activity, protease activity, net nitrogen mineralization rate, and content of nitrate and ammonium nitrogen of rhizosphere soil were determined at different wheat growth stages to explore the biological factors influencing nitrogen transformation and their response to different nitrogen application in wheat fields of lime concretion black soils. The results showed that the active period of soil nitrogen transformation microorganisms and enzymes was from jointing stage to grain-filling stage. After that, the ammonification intensity, nitrification intensity, urease activity and protease activity decreased. Similarly, the soil net nitrogen mineralization rate reached the highest level at flowering stage. Except for urease activity which increased with increasing nitrogen

  8. Evaluation of soil microbial communities as influenced by crude oil ...

    African Journals Online (AJOL)

    sunny t

    2015-05-13

    May 13, 2015 ... Key words: Species diversity, impact of crude oil pollution, soil – biota ... and inundated soil environment has proven to be a .... These were stored at -80°. ... For PCR AOA (Polymerase Chain Reaction – Ammonia Oxidizing.

  9. 不同盐碱度土壤中AM菌根真菌群落结构组成及影响因子%Structure of Arbuscular mycorrhiza fungi community in soils with different salinity and influence factors

    Institute of Scientific and Technical Information of China (English)

    李丹; 高永超; 王加宁; 邱维忠; 迟建国

    2013-01-01

    In order to explore the Arbuscular mycorrhiza (AM) fungi diversity of the plant rhizosphere in the saline soil of the Yellow River Delta,four rhizosphere soil samples of Suaeda glauca Bge and Tamarix chinensis were collected from Gudong and Gudao oil fields in Dongying City for identification of the AM fungi communities.The results showed that Glomus was the dominant species in the saline soil accompanying with many unidentified fungi.The investigation of the mycorrhizal fungi community in different soil salinity showed that the AM fungal diversity in the rhizosphere soil of Suaeda glauca Bge was higher than that of Tamarix chinensis,and Gudong higher than Gudao.The correlation analysis showed that the ammonium nitrogen content had a significant negative relationship with AM fungal diversity.%为研究黄河三角洲盐渍土壤中植物根围AM菌根真菌多样性及影响多样性的因素,从东营孤东和孤岛油区采集碱蓬和柽柳植物的根围土壤,鉴定了4种土壤试样中丛枝菌根(Arbuscular mycorrhiza,AM)的群落组成.结果表明:球囊霉属(Glomus)是盐碱地中的优势种,同时还有许多未知真菌;考察不同盐碱度情况下菌根真菌群落结构差异,结果表明:碱蓬根围土壤中AM真菌的多样性高于柽柳,孤东根围土壤AM真菌多样性比孤岛高.相关分析表明,铵态氮含量与AM真菌多样性呈现显著负相关.

  10. Influence of agricultural micro-environment factors on greenhouse gases emission from the soil%农业微环境对土壤温室气体排放的影响*

    Institute of Scientific and Technical Information of China (English)

    齐玉春; 董云社; 章申

    2000-01-01

    二氧化碳(CO2)、氧化亚氮(N2O)、甲烷(CH4)等气体排放量的增加所引起的温室效应 是全球变暖的主要促动因素。同时各种温室气体的产生和排放量也同样受其所处环境状况的 影响与反馈作用。研究各环境要素对土壤温室气体排放的主要影响机制是调节气候变化与温 室气体排放循环反馈过程的关键环节,对减少温室气体排放、减缓全球变暖趋势具有较强的 现实意义。阐述了土壤排放N2O、CH4对环境因素的影响,并提出温室气体减排措施。%The global warming is one of the environmental problem s. The global climate change is the result of the natural process and human acti vity. The increasing of carbon dioxide, nitrous oxide and methane' emission flux is the main impelling force. At the same time, the emission of the greenhouse g ases (GHG) are also affected by the environment, so the study on the environment influence mechanism is the key link of keeping abreast of the interaction betwe en the climate change and the GHG emission. It is of important realistic signifi cance for decreasing the emis sion of the GHG and slowing down the global warming pace. In this paper, we will generally discuss about the influence of the environment factors and put forwar d some measures that could control and retard the GHG emission.

  11. Influence of temperature and predation on survival of Salmonella enterica serovar Typhimurium and expression of invA in soil and manure-amended soil.

    Science.gov (United States)

    García, R; Baelum, J; Fredslund, L; Santorum, P; Jacobsen, C S

    2010-08-01

    The effects of three temperatures (5, 15, and 25 degrees C) on the survival of Salmonella enterica serovar Typhimurium in topsoil were investigated in small microcosms by three different techniques: plate counting, invA gene quantification, and invA mRNA quantification. Differences in survival were related to the effect of protozoan predation. Tetracycline-resistant Salmonella serovar Typhimurium was inoculated into soil and manure-amended soil at 1.5 x 10(8) cells g soil(-1). Population densities were determined by plate counting and by molecular methods and monitored for 42 days. Simultaneous extraction of RNA and DNA, followed by quantitative PCR, was used to investigate invA gene levels and expression. Analysis by these three techniques showed that Salmonella serovar Typhimurium survived better at 5 degrees C. Comparing DNA and CFU levels, significantly higher values were determined by DNA-based techniques. invA mRNA levels showed a fast decrease in activity, with no detectable mRNA after an incubation period of less than 4 days in any of the soil scenarios. A negative correlation was found between Salmonella serovar Typhimurium CFU levels and protozoan most probable numbers, and we propose the role of the predator-prey interaction as a factor to explain the die-off of the introduced strain by both culture- and DNA quantification-based methods. The results indicate that temperature, manure, and protozoan predation are important factors influencing the survival of Salmonella serovar Typhimurium in soil.

  12. Influence of salinity and water content on soil microorganisms

    Directory of Open Access Journals (Sweden)

    Nan Yan

    2015-12-01

    Full Text Available Salinization is one of the most serious land degradation problems facing world. Salinity results in poor plant growth and low soil microbial activity due to osmotic stress and toxic ions. Soil microorganisms play a pivotal role in soils through mineralization of organic matter into plant available nutrients. Therefore it is important to maintain high microbial activity in soils. Salinity tolerant soil microbes counteract osmotic stress by synthesizing osmolytes which allows them to maintain their cell turgor and metabolism. Osmotic potential is a function of the salt concentration in the soil solution and therefore affected by both salinity (measured as electrical conductivity at a certain water content and soil water content. Soil salinity and water content vary in time and space. Understanding the effect of changes in salinity and water content on soil microorganisms is important for crop production, sustainable land use and rehabilitation of saline soils. In this review, the effects of soil salinity and water content on microbes are discussed to guide future research into management of saline soils.

  13. Hardwood biochar influences calcareous soil physicochemical and microbiological status

    Science.gov (United States)

    The effects of biochar application to calcareous soils are not well documented. In a laboratory incubation study, a hardwood-based, fast pyrolysis biochar was applied (0, 1, 2, and 10% by weight) to a calcareous soil. Changes in soil chemistry, water content, microbial respiration, and microbial com...

  14. Factors Influencing Students’ Perceptions of Online Teamwork

    Directory of Open Access Journals (Sweden)

    Irina Falls

    2014-02-01

    Full Text Available The evolution of online teaching in higher education demands a change in the types of pedagogies used in those courses. An example of one of these important pedagogies includes online teamwork. Teamwork in this context is one in which the majority of the individual’s grade is dependent on the positive or negative group experiences. This study utilized the theoretical framework of social motivation and cohesion to identify the factors shaping students’ perceptions of teamwork in online college courses. In these courses, the pedagogical approach known as the Five Pillars of effective collaborative work was applied. An Online Teamwork Learning Survey was developed based on these principles and completed by 62 undergraduate students enrolled in semester-long online courses required in their early childhood education program of study. Using a comparison between pre–postsurveys and regression analysis, the results showed that although the students’ perceptions of teamwork did not significantly change, the factors influencing their responses during the posttest doubled in number. The results showed that through carefully designed virtual teamwork activities, students learned that essential team characteristics such as promotive interaction, individual accountability, and positive interdependence are an integral part of effective collaboration and strong predictors of teamwork perception.

  15. Soil Line Influences on Two-Band Vegetation Indices and Vegetation Isolines: A Numerical Study

    Directory of Open Access Journals (Sweden)

    Alfredo R. Huete

    2010-02-01

    Full Text Available Influences of soil line variations on two-band vegetation indices (VIs and their vegetation isolines in red and near-infrared (NIR reflectance space are investigated based on recently derived relationships between the relative variations of VIs with variations of the soil line parameters in the accompanying paper by Yoshioka et al. [1]. The soil line influences are first demonstrated numerically in terms of variations of vegetation isolines and VI values along with the isolines. A hypothetical case is then analyzed by assuming the discrepancies between the general and regional soil lines for a Southern Brazil area reported elsewhere. The results indicate the validity of our analytical approach for the evaluation of soil line influences and the applicability for adjustment of VI errors using external data sources of soil reflectance spectra.

  16. The Influence of Processing Soil With a Coffee Grinder on Soil Classification

    Science.gov (United States)

    2015-01-20

    result of rapidly driving out moisture from wet clumps of soil. Left alone, these clods would skew the grain size curve to the coarse side and create a...soil splitter. For the control, a mortar and pestle were used to break up clumps of soil into individual particles and the ’treated’ soil was...the question that it may produce fines by cutting/breaking larger particles -potentially leading to the mis-classification of soil. In order to

  17. Influence of different plant species on methane emissions from soil in a restored Swiss wetland.

    Directory of Open Access Journals (Sweden)

    Gurbir S Bhullar

    Full Text Available Plants are a major factor influencing methane emissions from wetlands, along with environmental parameters such as water table, temperature, pH, nutrients and soil carbon substrate. We conducted a field experiment to study how different plant species influence methane emissions from a wetland in Switzerland. The top 0.5 m of soil at this site had been removed five years earlier, leaving a substrate with very low methanogenic activity. We found a sixfold difference among plant species in their effect on methane emission rates: Molinia caerulea and Lysimachia vulgaris caused low emission rates, whereas Senecio paludosus, Carex flava, Juncus effusus and Typha latifolia caused relatively high rates. Centaurea jacea, Iris sibirica, and Carex davalliana caused intermediate rates. However, we found no effect of either plant biomass or plant functional groups--based on life form or productivity of the habitat--upon methane emission. Emissions were much lower than those usually reported in temperate wetlands, which we attribute to reduced concentrations of labile carbon following topsoil removal. Thus, unlike most wetland sites, methane production in this site was probably fuelled chiefly by root exudation from living plants and from root decay. We conclude that in most wetlands, where concentrations of labile carbon are much higher, these sources account for only a small proportion of the methane emitted. Our study confirms that plant species composition does influence methane emission from wetlands, and should be considered when developing measures to mitigate the greenhouse gas emissions.

  18. Assessing the influence of sustainable trail design and maintenance on soil loss.

    Science.gov (United States)

    Marion, Jeffrey L; Wimpey, Jeremy

    2017-03-15

    Natural-surfaced trail systems are an important infrastructure component providing a means for accessing remote protected natural area destinations. The condition and usability of trails is a critical concern of land managers charged with providing recreational access while preserving natural conditions, and to visitors seeking high quality recreational opportunities and experiences. While an adequate number of trail management publications provide prescriptive guidance for designing, constructing, and maintaining natural-surfaced trails, surprisingly little research has been directed at providing a scientific basis for this guidance. Results from a review of the literature and three scientific studies are presented to model and clarify the influence of factors that substantially influence trail soil loss and that can be manipulated by trail professionals to sustain high traffic while minimizing soil loss over time. Key factors include trail grade, slope alignment angle, tread drainage features, and the amount of rock in tread substrates. A new Trail Sustainability Rating is developed and offered as a tool for evaluating or improving the sustainability of existing or new trails. Published by Elsevier Ltd.

  19. Assessing the influence of sustainable trail design and maintenance on soil loss

    Science.gov (United States)

    Marion, Jeff; Wimpey, Jeremy

    2017-01-01

    Natural-surfaced trail systems are an important infrastructure component providing a means for accessing remote protected natural area destinations. The condition and usability of trails is a critical concern of land managers charged with providing recreational access while preserving natural conditions, and to visitors seeking high quality recreational opportunities and experiences. While an adequate number of trail management publications provide prescriptive guidance for designing, constructing, and maintaining natural-surfaced trails, surprisingly little research has been directed at providing a scientific basis for this guidance. Results from a review of the literature and three scientific studies are presented to model and clarify the influence of factors that substantially influence trail soil loss and that can be manipulated by trail professionals to sustain high traffic while minimizing soil loss over time. Key factors include trail grade, slope alignment angle, tread drainage features, and the amount of rock in tread substrates. A new Trail Sustainability Rating is developed and offered as a tool for evaluating or improving the sustainability of existing or new trails.

  20. Spatial variability and influencing factors of soil catalase activity in grapevine fields in Huailai-Zhuolu Basin%怀涿葡萄产区土壤过氧化氢酶活性空间分布规律及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    马堃; 李橙; 肖凡; 冯圣东; 杨志新

    2013-01-01

    This study assessed the physicochemical factors influencing the spatial variability of soil catalase activity in grapevine fields.83 samples of 0~20 cm soil layer was collected from grapevine fields in the Huailai-Zhuolu basin (HZB) of Hebei,China.Geostatistics and GIS environments were used to analyze the spatial variability of soil catalase activity for different combinations of grape variety and soil property.Also the contributing factors to enzyme activity were analyzed.The results showed strongly spatial correlation of catalase activity in 0~20 cm soil layer of grapevine field in HZB.The variations of catalase activity in the study area tracked a zonal distribution,gradually decreasing from west to east along river courses.Based on semi-variance analysis,the best-fitted model for soil catalase activity distribution in the study area was an exponential model.With the exception of potassium,all macro-elements,micro-elements,quantitative elements,heavy metals and other beneficial elements had a significant positive activation effect on soil catalase activity in grapevine fields.In traditional soil-grape cropping systems,catalase activity was closely correlated with the distribution characteristics of most elements at different locations in grapevine fields.Also a significant positive correlation was noted between catalase activity and fine sand content.A highly significant positive correlation was noted between catalase activity and clay.The physical properties,especially clay and fine sand content,were other critical factors that influenced the spatial variability of soil catalase activity.Ggrape varieties and soil pH were not correlated with spatial variability of soil catalase activity.%为了探明影响土壤过氧化氢酶活性空间变异规律的葡萄品种、土壤物理、化学因素及其内在关系,本文利用GIS和地统计学分析方法研究了怀涿葡萄产区(河北省怀来、涿鹿两县)的83个表层土壤样品.结果表明:怀

  1. Preoperative factors influencing success in pterygium surgery

    Directory of Open Access Journals (Sweden)

    Torres-Gimeno Ana

    2012-08-01

    Full Text Available Abstract Background To identify preoperative, perioperative and postoperative risk factors that influence the success of pterygium surgery. Methods This is a prospective study of thirty-six patients with primary or recurrent pterygia. A detailed anamnesis and an ophthalmological examination were performed looking for the following factors: age, race, latitude and altitude of the main place of residence, hours of exposure to the sun, use of protective measures against UV-radiation, classification of pterygium, width of the pterygium at limbus, surgical technique (conjunctival autograft plus suturing versus tissue glue, graft alterations (misapposition, granuloma, haemorrhage, oedema, retraction or necrosis, and postoperative symptoms (foreign-body sensation, pain. The examinations were performed 2 and 7 days and 2, 6 and 12 months after surgery. In addition, recurrence was defined as any growth of conjunctiva into the cornea. Results A logistic regression and a survival analysis have been used to perform data analysis. A total number of 36 patients completed a one year follow-up. A total of 13 patients were born and lived in Spain, and 26 came from other countries, mostly Latin America. A total number of 8 males (no women presented a recurrence, mainly between 2 and 6 months. The hours of sun exposure through their life was independently related to surgical success. Pterygia of less than 5 mm of base width showed a weak positive correlation with recurrence. None of the other factors considered were significantly related to recurrence. Conclusions Male gender and high sun exposure are strongly and independently related to surgical success after the removal of pterygia.

  2. Soil development as limiting factor for shrub expansion in southwestern Greenland

    Science.gov (United States)

    Caviezel, Chatrina; Hunziker, Matthias; Zoller, Oliver; Wüthrich, Christoph; Kuhn, Nikolaus J.

    2014-05-01

    Southern Greenland currently experiences an increase in summer temperatures and a prolonged growing season (Masson-Delmotte et al. 2012), resulting in an increased shrub cover at the boreal - tundra border ecotone (Normand et al. 2013). These findings suggest the beginning of a greener Greenland in which tundra vegetation is transformed to a boreal woody flora. However, vegetation at borderline ecotones is influenced by further ecologic factors than just temperature. In this study, the ecologic conditions at a selection of sites along an elevation gradient near Igaliku in southern Greenland were examined to identify potential factors limiting the expansion of woody vegetation apart from temperature. The sites differ in elevation, topography, shrub density and soil parent material. The three study sites comprise i) well established birch shrubs growing between 50 and 180 m a.s.l., where the parent material origins from the Julianehab granite (Brooks 2012); ii) extended shrub patches at about 250 m a.s.l., where the parent material consists of Gardar Sandstones and Lavas (Brooks 2012) and iii) restricted shrub patches at an elevation of 250 m a.s.l., where the soil parent material originates from the Gardar intrusions (Brooks 2012). The extent of the shrub areas, topography and soil moisture were mapped, additionally soil samples were analyzed for C-and N-content, texture including coarse fraction and pH and used as soil development indicators. Our results show that the topographic setting regulates the existence or absence of soil while the soil parent material is an important limiting factor for soil moisture. According to these findings, we suggest that a high proportion of areas where temperature increase would allow the increase of shrub cover is not suitable for a woody flora. Brooks, Kent. 2012. "A Tale of Two Intrusions—where Familiar Rock Names No Longer Suffice." Geology Today 28 (1): 13-19. doi:10.1111/j.1365-2451.2012.00815.x. Masson-Delmotte, V., D

  3. The evolution of sandy soils under the influence of vegetation succession and anthropogenic activities - case study from Błędów Desert

    Science.gov (United States)

    Gus, Magdalena; Drewnik, Marek

    2016-04-01

    Sandy areas are an important source of research about early stages of the soils formation process and their further development. The rate of succession is reflecting the influence of vegetation on chemical and physical properties of soils which as the time goes undergo the evolution process caused by other environmental factors. The Błędów Desert (Poland, Central Europe) is an example of this kind of area, where sandy soils evolved into Podzols, but as a result of human activities conducted since Middle Ages soil cover has been destroyed to bedrock. Currently progressing vegetation succession occurred in two ways: primary, which took place in areas covered by loose sand and secondary, in the areas with fossil soils. Presently the Błędów Desert is a suitable example to study soil changes in both cases mentioned above. The main aim of the study was to present diversity and characteristics of soils in The Błędów Desert in relation to their development stages and vegetation succession. During field studies soil profiles were described and selected for the detailed studies and soils samples were taken for laboratory analysis, including a determination of basic physical and chemical analysis as well as for micromorphological analysis (selected profiles). Podzols located near the boundary of the study area was selected as a reference soils. The results proved the complexity of the soil process formation, which strongly depends on the vegetation succession and human activities including human-induced aeolian processes. Results confirmed the presence of buried soils, which together with the contemporary soils formed a soil sequence. Moreover, research shows that the dominant soil-forming processes at the Błędów Desert are humus accumulation and podzolization. To summarize, The Błędów Desert is a dynamic environment undergoing rapid changes of soil cover under the influence of the interaction of vegetation, anthropopression and aeolian processes.

  4. Influence of effective stress on swelling pressure of expansive soils

    Directory of Open Access Journals (Sweden)

    Baille Wiebke

    2016-01-01

    Full Text Available The volume change and shear strength behaviour of soils are controlled by the effective stress. Recent advances in unsaturated soil mechanics have shown that the effective stress as applicable to unsaturated soils is equal to the difference between the externally applied stress and the suction stress. The latter can be established based on the soil-water characteristic curve (SWCC of the soil. In the present study, the evolution of swelling pressure in compacted bentonite-sand mixtures was investigated. Comparisons were made between magnitudes of applied suction, suction stress, and swelling pressure.

  5. Environmental factors shaping the community structure of ammonia-oxidizing bacteria and archaea in sugarcane field soil.

    Science.gov (United States)

    Tago, Kanako; Okubo, Takashi; Shimomura, Yumi; Kikuchi, Yoshitomo; Hori, Tomoyuki; Nagayama, Atsushi; Hayatsu, Masahito

    2015-01-01

    The effects of environmental factors such as pH and nutrient content on the ecology of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in soil has been extensively studied using experimental fields. However, how these environmental factors intricately influence the community structure of AOB and AOA in soil from farmers' fields is unclear. In the present study, the abundance and diversity of AOB and AOA in soils collected from farmers' sugarcane fields were investigated using quantitative PCR and barcoded pyrosequencing targeting the ammonia monooxygenase alpha subunit (amoA) gene. The abundances of AOB and AOA amoA genes were estimated to be in the range of 1.8 × 10(5)-9.2 × 10(6) and 1.7 × 10(6)-5.3 × 10(7) gene copies g dry soil(-1), respectively. The abundance of both AOB and AOA positively correlated with the potential nitrification rate. The dominant sequence reads of AOB and AOA were placed in Nitrosospira-related and Nitrososphaera-related clusters in all soils, respectively, which varied at the level of their sub-clusters in each soil. The relationship between these ammonia-oxidizing community structures and soil pH was shown to be significant by the Mantel test. The relative abundances of the OTU1 of Nitrosospira cluster 3 and Nitrososphaera subcluster 7.1 negatively correlated with soil pH. These results indicated that soil pH was the most important factor shaping the AOB and AOA community structures, and that certain subclusters of AOB and AOA adapted to and dominated the acidic soil of agricultural sugarcane fields.

  6. Influence of space of double row piles on soil arching effect

    Directory of Open Access Journals (Sweden)

    Zhao bo

    2015-02-01

    Full Text Available FLAC3d software, based on continuous theory, is used to analysis influence of space of double row piles on soil arching effect. The result shows that different from single row pile, double row piles will produce soil arching effect at front pile and rear pile severally, this phenomenon is called multiple soil arching effect; the residual load of front of front row pile will increase,the soil arch zone and the soil arching effect will decrease with the continuous increase of double row pile spacing.At the same time the soil arching effect of rear pile decreases, while the soil arching effect of front pile increases and finally the soil arching effect between front pile and rear pile will be equal.

  7. Derivation of Soil Line Influence on Two-Band Vegetation Indices and Vegetation Isolines

    Directory of Open Access Journals (Sweden)

    Hiroki Yoshioka

    2009-11-01

    Full Text Available This paper introduces derivations of soil line influences on two-band vegetation indices (VIs and vegetation isolines in the red and near infra-red reflectance space. Soil line variations are described as changes in the soil line parameters (slope and offset and the red reflectance of the soil surface. A general form of a VI model equation written as a ratio of two linear functions (e.g., NDVI and SAVI was assumed. It was found that relative VI variations can be approximated by a linear combination of the three soil parameters. The derived expressions imply the possibility of estimating and correcting for soil-induced bias errors in VIs and their derived biophysical parameters, caused by the assumption of a general soil line, through the use of external data sources such as regional soil maps.

  8. Quantifying influences of physiographic factors on temperate dryland vegetation, Northwest China

    Science.gov (United States)

    Du, Ziqiang; Zhang, Xiaoyu; Xu, Xiaoming; Zhang, Hong; Wu, Zhitao; Pang, Jing

    2017-01-01

    Variability in satellite measurements of terrestrial greenness in drylands is widely observed in land surface processes and global change studies. Yet the underlying causes differ and are not fully understood. Here, we used the GeogDetector model, a new spatial statistical approach, to examine the individual and combined influences of physiographic factors on dryland vegetation greenness changes, and to identify the most suitable characteristics of each principal factor for stimulating vegetation growth. Our results indicated that dryland greenness was predominantly affected by precipitation, soil type, vegetation type, and temperature, either separately or in concert. The interaction between pairs of physiographic factors enhanced the influence of any single factor and displayed significantly non-linear influences on vegetation greenness. Our results also implied that vegetation greenness could be promoted by adopting favorable ranges or types of major physiographical factors, thus beneficial for ecological conservation and restoration that aimed at mitigating environmental degradation. PMID:28067259

  9. Rapid method of determining factors limiting bacterial growth in soil

    OpenAIRE

    Aldén Demoling, Louise; Demoling, Fredrik; Bååth, Erland

    2001-01-01

    A technique to determine which nutrients limit bacterial growth in soil was developed. The method was based on measuring the thymidine incorporation rate of bacteria after the addition of C, N, and P in different combinations to soil samples. First, the thymidine incorporation method was tested in two different soils: an agricultural soil and a forest humus soil. Carbon (as glucose) was found to be the limiting substance for bacterial growth in both of these soils. The effect of adding differ...

  10. Remarks on the physical factor influencing the individual language learners

    Institute of Scientific and Technical Information of China (English)

    刘晨君

    2015-01-01

    individual language learner as a subject of learning can be influenced by many factors such as physical factor,cognitive factor,and affective factor.All of which play an important role in language learning.These three factors are worthy of our research and physical factor will be discussed in this essay.

  11. The influence of vegetation covers on soil moisture dynamics at high temporal resolution in scattered tree woodlands of Mediterranean climate

    Science.gov (United States)

    Lozano-Parra, Javier; Schnabel, Susanne; Ceballos-Barbancho, Antonio

    2015-04-01

    Soil water is a key factor that controls the organization and functioning of dryland ecosystems. However, in spite of its great importance in ecohydrological processes, most of the studies focus on daily or longer timescales, while its dynamics at shorter timescales are very little known. The main objective of this work was to determine the role of vegetation covers (grassland and tree canopy) in the soil hydrological response using measurements with high temporal resolution in evergreen oak woodland with Mediterranean climate. For this, soil water content was monitored continuously with a temporal resolution of 30 minutes and by means of capacitance sensors, mainly for the hydrological years 2010-2011 and 2011-2012. They were installed at 5, 10 and 15 cm, and 5 cm above the bedrock and depending on soil profile. This distribution along the soil profile is justified because soils are generally very shallow and most of the roots are concentrated in the upper layer. The sensors were gathered in 8 soil moisture stations in two contrasting situations characterized by different vegetation covers: under tree canopy and in open spaces or grasslands. Soil moisture variations were calculated at rainfall event scale at top soil layer and deepest depth by the difference between the final and initial soil moisture registered by a sensor at the finish and the beginning of the rainfall event, respectively. Besides, as soil moisture changes are strongly influenced by antecedent conditions, different antecedent soil moisture conditions or states, from driest to wettest, were also defined. The works were carried out in 3 experimental farms of the Spanish region of Extremadura. Results obtained revealed that rainwater amount bypassing vegetation covers and reaching the soil may temporarily be modified by covers according to precipitation properties and antecedent environmental conditions (from dry to wet) before the rain episode. Rainfall amounts triggering a positive soil

  12. Influence of trace metals on some soil nitrogen transformations

    Energy Technology Data Exchange (ETDEWEB)

    Chang, F.H.; Broadbent, F.E.

    An investigation to evaluate the influence of trace metals on N immobilization, N mineralization, and nitrification was conducted. Samples of Yolo silt loam amended with 100 ppm NH/sub 4/-N, 1% sewage sludge, and 1% ground alfalfa (Medicago sativa L.) were treated with solutions to provide 100, 200, and 400 ppm of Cd(II), Cr(III), Cu(II), Mn(II), Pb(II) and Zn(II), and incubated for 2, 4, 8, and 12-week periods. Metals were determined by extracting with water, KNO/sub 3/, DPTA (diethylenetriaminepentaacetic acid), and HNO/sub 3/ at the end of each incubation period. All metals reverted quickly to more insoluble forms. Quantities of metals extractable with water + KNO, + DPTA decreased with time, while corresponding increases in HNO/sub 3/-soluble forms occurred. Nitrogen immobilization was measured during 2- to 4-week period, and N mineralization and nitrification during the 4- to 12-week period. At low levels of metal addition Mn and Pb stimulated N transformations. Among the six metals studied the sequence in order of decreasing inhibition was Cr > Cd > Cu > Zn > Mn > Pb. It was concluded that N transformation rates may be affected by trace metals in soils receiving heavy sludge applications.

  13. Effects of environmental factors and soil properties on topographic variations of soil respiration

    Directory of Open Access Journals (Sweden)

    K. Tamai

    2010-03-01

    Full Text Available Soil respiration rates were measured along different parts of a slope in (a an evergreen forest with common brown forest soil and (b a deciduous forest with immature soil. The effects of soil temperature, soil moisture and soil properties were estimated individually, and the magnitudes of these effects in the deciduous and evergreen forests were compared. In the evergreen forest with common brown forest soil, soil properties had the greatest effect on soil respiration rates, followed by soil moisture and soil temperature. These results may be explained by the fact that different soil properties matured within different environments. It can be argued that the low soil respiration rates in the low parts of the slope in the evergreen forest resulted from soil properties and not from wet soil conditions. In the deciduous forest, soil respiration rates were more strongly affected by soil moisture and soil temperature than by soil properties. These effects were likely due to the immaturity of the forest soil.

  14. Study on Soil Infiltration Capability and Its Impact Factors of Different Land-use Types in Purple Soil Region

    Institute of Scientific and Technical Information of China (English)

    Bin MO; Xiaoyan CHEN; Tao LIU; Yicui YANG; Zhixing LIN; Xiufeng HUANG; Qiliang HUANG; Hui JIAN; Tujin ZHOU; Yunkang SHEN

    2016-01-01

    Soil infiltration capability is the hot spot topic of soil erosion studies and soil physical and chemical properties have great influence on it. A new infiltration method point- source infiltration method was used to precisely evaluate the infiltration capability in different purple soil land- use types. And correlation analysis on soil physical and chemical properties and soil infiltration capability of different land- use types was performed. Results showed that:( i) there is a large difference among soil physical and chemical properties in different land- use types,soil water content,non- capillary porosity,capillary porosity,content of > 0. 25 mm aggregates and organic matter content in the top soil are greater than those in the subsoil;( ii) soil infiltration capability showed differences among different land- use types. Land use showed great effects,in general,the order of decrease on initial infiltration rate and average infiltration rate was: woodland slope > slope farmland >grassland,the order of decrease on steady infiltration rate was: slope farmland > woodland > grassland and the time reaching stable state was:slope farmland > woodland > grassland;( iii) correlation analysis showed that there was a significantly positive correlation between initial infiltration rate and wet sieve MWD value and structural damage rate,and it had a significantly negative correlation with capillary porosity;( iv)steady infiltration rate and non- capillary porosity showed the significantly positive correlation,and it had a significantly negative correlation with the soil bulk density;( v) the average infiltration rate and non- capillary porosity and structural damage rate showed a positive correlation and the correlation coefficient was large and there was a negative correlation between average infiltration rate and soil bulk density and capillary porosity,and the absolute value of correlation coefficient was relatively large. The results of this study can provide the

  15. Influence of sustainable management on aggregate stability and soil organic matter on agricultural soil of southern Spain

    Science.gov (United States)

    Morugan-Coronado, Alicia; Arcenegui, Victoria; Mataix-Solera, Jorge; Gomez-Lucas, Ignacio; Garcia-Orenes, Fuensanta

    2016-04-01

    Intensive agriculture has increased crop yields but also posed severe environmental problems. Unsustainable land management such as excessive tillage can lead to a loss of soil fertility and a drastic reduction in the aggregate stability and soil organic matter content. However sustainable agriculture can keep good crop yields with minimal impact on ecological factors conserving the soil quality and its ecosystem services. Sustainable agriculture management promotes the maintenance of soil organic matter levels providing plant nutrients through the microbial decomposition of organic materials. Also this management has a positive effect on soil structure with the improvement of stability of aggregates. The resistance of soil aggregates to the slaking and dispersive effects of water (aggregate stability) is important for maintaining the structure in arable soils. Our purpose was to investigate and compare the effects of sustainable agricultural practices versus intensive agriculture on aggregate stability and soil organic matter. Three agricultural areas are being monitored in the southern of Spain, two of them with citrus orchards (AL) and (FE) and one with grapevine(PA). In all of them two agricultural treatments are being developed, organic with no-tillage management(O) and inorganic fertilization with herbicide application and intensive tillage (I). The sustainable agricultural management (manure, no tillage and vegetation cover) contributed to the improve of soil conditions, increasing organic matter and aggregate stability. Meanwhile, herbicide treatment and intensive tillage with inorganic fertilization managements resulted in the decreasing of aggregate stability and low levels of soil organic carbon. Soil organic matter content is generally low in all unsustainable treatments plots and tends to decline in aggregate stability and soil physical condition. In both treatments the crop yield are comparable.

  16. Short-term Influence of Herbicide Quinclorac on Enzyme Activities in Flooded Paddy Soils

    Institute of Scientific and Technical Information of China (English)

    L(U) Zhen-Mei; MIN Hang; YE Yang-Fang

    2004-01-01

    The influence of quinclorac (3,7-dichloroquinoline-8-carboxylic acid) on enzyme activities in flooded paddy soils was assessed under laboratory conditions. The enzymes differed markedly in their response to quinclorac. Quinclorac inhibited proteinase, hydrogen peroxidase, phosphorylase, and urease activities.The higher the concentration of quinclorac applied, the more significant the inhibition to these observed activities with a longer time required to recover to the level of the control. However, soils supplemented with quinclorac were nonpersistent for proteinase, phosphorylase and urease as opposed to soils without quinclorac. Dehydrogenase activity was also sensitive to quinclorac. Three soil samples with concentrations of quinclorac higher than 1 μg g-1 soil declined to less than 20% of that in the control. However, the highest dehydrogenase activity (up to 3.28-fold) was detected in soils with 2 μg g-1 soil quinclorac on the 25th day after treatment. Quinclorac had a relatively mild effect on saccharase activity at the concentrations used in this experiment and a stimulatory one on soil respiration when added to soil at normal field concentrations.Nonetheless it was inhibited at higher concentrations in paddy soils. Quinclorac is still relatively safe to the soil ecosystem when applied at a normal concentration (0.67 μg g-1 dried soil) but may have some effects on soil enzymes at higher concentrations.

  17. Adsorption of chloroacetanilide herbicides on soil I. Structural influence of chloroacetanilide herbicide for their adsorption on soils and its components

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Adsorption of chloroacetanilide herbicide acetochlor,alachlor, metolachlor and propachlor on soils and soil components was determined, and the structural differences of these herbicides were used to explain the order of sorptivity. Adsorption isotherms for all herbicide-soil combinations conformed to the Freundlich equation, and Kf increased with increasing soil organic carbon content. Kd on soil humic acid was greater than that on clay, but association of humic acid with clay reduced the overall adsorption. On all soils and soil humic acids, herbicide adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca2+-montmorrilonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR spectra of herbicide-clay or herbicide-humic acid-clay mixtures showed that H-bonding and charge transfer were the primary interaction pathways between these compounds and the surface of clay or humic acids. The different moieties attached to 2-chloro-acetanilide and their unique arrangement may have influenced the binding mechanisms and thus the sorptivity of these herbicides. This study indicates that the structural difference of pesticides in the same classes may be used as a molecular probe to obtain a better understanding of sorption mechanisms of pesticides on soil.

  18. Degradation kinetics of forchlorfenuron in typical grapevine soils of India and its influence on specific soil enzyme activities.

    Science.gov (United States)

    Banerjee, Kaushik; Dasgupta, Soma; Oulkar, Dasharath P; Patil, Sangram H; Adsule, Pandurang G

    2008-05-01

    The rate of degradation of forchlorfenuron, a cytokinin-based plant growth regulator (PGR) was explored in typical grapevine soils of India with simultaneous evaluation of its effect on biochemical attributes of the test soils in terms of the activities of specific soil microbial enzymes. In all the test soils, namely clay, sandy-loam and silty-clay, the dissipation rate was faster at the beginning, which slowed down with time, indicating a non-linear pattern of degradation. Degradation in soils could best be explained by two-compartment 1st+1st order kinetics with half-life ranging between 4-10 days. The results suggest that organic matter might be playing a major role in influencing the rate of degradation of forchlorfenuron in soil. The rate of degradation in sandy-loam soil was fastest followed by clay and silty-clay soils, respectively. Comparison of the rate of degradation in natural against sterilized soils suggests that microbial degradation might be the major pathway of residue dissipation. Changes in soil enzyme activities as a consequence of forchlorfenuron treatment were studied for extra-cellular enzymes namely acid phosphatase, alkaline phosphatase and beta -glucosidase and intracellular enzyme-dehydrogenase. Although small changes in enzyme activities were observed, forchlorfenuron did not have any significant deleterious effect on the enzymatic activity of the test soils. Simple correlation studies between degradation percentage and individual enzyme activities did not establish any significant relationships. The pattern and change of enzyme activity was primarily the effect of the incubation period rather than the effect of forchlorfenuron itself.

  19. Dynamical soil-structure interactions: influence of soil behaviour nonlinearities; Interaction Dynamique Sol-Structure: Influence des Nonlinearites de Comportement du Sol

    Energy Technology Data Exchange (ETDEWEB)

    Gandomzadeh, Ali

    2011-02-08

    the soil and the response of the soil-structure system. Through these parametric studies we show that depending on the soil properties, frequency content of the soil response could change significantly due to the soil nonlinearity. The peaks of the transfer function between free field and outcropping responses shift to lower frequencies and amplification happens at this frequency range. Amplification reduction for the high frequencies and even de-amplification may happen for high level input motions. These changes influence the structural response. We show that depending on the combination of the fundamental frequency of the structure and the the natural frequency of the soil, the effect of soil-structure interaction could be significant or negligible. However, the effect of structure weight and rocking of the superstructure could change the results. Finally, the basin of Nice is used as an example of wave propagation on a heterogeneous nonlinear media and dynamic soil-structure interaction. The basin response is strongly dependent on the combination of soil nonlinearity, topographic effects and impedance contrast between soil layers. For the selected structures and soil profiles of this work, the performed numerical simulations show that the shift of the fundamental frequency is not a good index to discriminate linear from nonlinear soil behavior. (author)

  20. Factors mediating the restoration of structurally degraded soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Schjønning, Per;

    with the ability of soils to perform these functions. The present study examines the roles of clay mineralogy, native organic matter, and exogenous organic material on the restoration of structurally degraded soils. Totally seven soils from Denmark and Ghana - five soils dominated by illites, one kaolinitic soil......Soil structure is essential for sustained provision of ecosystem services such as water filtering and storage, waste disposal, carbon sequestration and many more. Structural degradation/disaggregation of soils emanating from human activities such as mining, grading and filling interferes...... and lowest for the smectitic soil. Among the illitic soils, aggregate workability increased with native organic matter content. Addition of exogenous organic material showed little effect on soil physical properties. Results points to the possibility of regenerating the structure of physically degraded soils...

  1. Growth and extracellular phosphatase activity of arbuscular mycorrhizal hyphae as influenced by soil organic matter

    DEFF Research Database (Denmark)

    Joner, E.J.; Jakobsen, I.

    1995-01-01

    Two experiments were set up to investigate the influence of soil organic matter on growth of arbuscular mycorrhizal (AM) hyphae and concurrent changes in soil inorganic P, organic P and phosphatase activity. A sandy loam soil was kept for 14 months under two regimes (outdoor where surplus precipi...... have influenced alkaline phosphatase excreted by other microorganisms, probably through competition for nutrients. Phosphatase activity was not correlated with the concentration of labile organic P in soil extracts.......Two experiments were set up to investigate the influence of soil organic matter on growth of arbuscular mycorrhizal (AM) hyphae and concurrent changes in soil inorganic P, organic P and phosphatase activity. A sandy loam soil was kept for 14 months under two regimes (outdoor where surplus...... precipitation leached through the soil, or indoor at constant moisture) with or without 9% (w/w) chopped wheat straw plus mineral N. Then the soils were partially sterilized and placed in two-compartment pots where mycorrhizal or non-mycorrhizal cucumber plants were grown in one root compartment (RC), and soils...

  2. Influence of strength parameters of soil on the slope stability

    Directory of Open Access Journals (Sweden)

    Xu Bin Bin

    2016-01-01

    Full Text Available The stability analysis of uniform clay and sand slope is carried out using traditional limit equilibrium method and strength reduction method. In order to evaluate the influence of strength parameters including friction angle and cohesive strength, the errors among Fellenius’s method, Bishop’s method and strength reduction method are calculated in detail. The results are: 1 the safety factor obtained from Fellenius’s method is smaller than that obtained from Bishop’s method; 2 the error between Bishop’s method and strength reduction method usually firstly increases and then decrease as the friction angle/cohesive strength becomes larger.

  3. Threshold friction velocity influenced by wetness of soils within the Columbia Plateau

    Science.gov (United States)

    Sharratt, B. S.; Vaddella, V. K.; Feng, G.

    2013-06-01

    Windblown dust impacts air quality in the Columbia Plateau of the US Pacific Northwest. Wind erosion of agricultural lands, which is the predominate source of windblown dust in the region, occurs when the friction velocity exceeds the threshold friction velocity (u∗t) of the surface. Soil moisture influences the u∗t, but the u∗t of variably wet soils is virtually unknown in the region. The relationship between u∗t and water content was ascertained for five silt loams collected from field sites in eastern Washington. After moistening the soils to predetermined water contents, u∗t was assessed from wind velocity and PM10 (particles with an aerodynamic diameter ⩽10 μm) and TSP (total suspended particulate matter) concentration profiles above the soil surface inside a wind tunnel. Soil water content appeared to have little influence on u∗t until gravimetric water content rose to 6-14% (depending on the soil). Trends in the relationship between u∗t and soil matric potential (Ψ) suggested moistening soils had little influence on u∗t until the Ψ was in the range of -25 to -1 MPa. The u∗t rose sharply with an increase in Ψ above -1 MPa. The results of this study suggest that u∗t is significantly influenced by adsorption and capillary forces that comprise the matric potential of soils.

  4. Influence of long-term sewage irrigation on the distribution of organochlorine pesticides in soil-groundwater systems.

    Science.gov (United States)

    Zhang, Caixiang; Liao, Xiaoping; Li, Jiale; Xu, Liang; Liu, Ming; Du, Bin; Wang, Yanxin

    2013-07-01

    Serious shortage of water resources is one of the major factors restricting the sustainable development of cropland and pasture land in northern and northwestern China. Although the reuse of wastewater for agricultural irrigation becomes a well established practice in these regions, many contaminants have been also introduced into the soil-groundwater systems such as persistent organochlorine pesticides (OCPs). To study the influence of long-term sewage irrigation on the distribution of OCPs in soil-groundwater systems, the groundwater flow field was investigated and 31 topsoil samples, 9 boreholes, 11 sewage effluents and 34 groundwater samples were collected in Xiaodian, Taiyuan city, one of the largest sewage irrigation districts, China. During sampling, three representative types of regions were considered including effluent-irrigated area, groundwater-irrigated area served as the control field and no-irrigated area as reference "background". The results showed over-exploitation of groundwater had changed the flow field of groundwater and wherever in soil or in groundwater, the concentration of OCPs in effluent-irrigation area presented the highest value, which indicated that the sewage irrigation had a strong influence on the distribution of OCPs in soil-groundwater systems. Principal component analysis for OCPs content in groundwater showed that the major influence factors on the occurrence and distribution of OCPs in groundwater systems attribute to the flow field of groundwater and to the current pesticide use.

  5. Influence of soil structure on contaminant leaching from injected slurry.

    Science.gov (United States)

    Amin, M G Mostofa; Pedersen, Christina Østerballe; Forslund, Anita; Veith, Tamie L; Laegdsmand, Mette

    2016-12-15

    Animal manure application to agricultural land provides beneficial organic matter and nutrients but can spread harmful contaminants to the environment. Contamination of fresh produce, surface water and shallow groundwater with the manure-borne pollutants can be a critical concern. Leaching and persistence of nitrogen, microorganisms (bacteriophage, E. coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after injection of swine slurry into either intact (structured) or disturbed (homogeneous repacked) soil. The slurry was injected into hexaplicate soil columns at a rate of 50 t ha(-1) and followed with four irrigation events: 3.5-h period at 10 mm h(-1) after 1, 2, 3, and 4 weeks. The disturbed columns delayed the leaching of a conservative tracer and microorganisms in the first irrigation event compared to the intact columns due to the effect of disturbed macropore flow paths. The slurry constituents that ended up in or near the macropore flow paths of the intact soil were presumably washed out relatively quickly in the first event. For the last three events the intact soil leached fewer microorganisms than the disturbed soil due to the bypassing effect of water through the macropore flow path in the intact soil. Estrogen leached from the intact soil in the first event only, but for the disturbed soil it was detected in the leachates of last two events also. Leaching from the later events was attributed to higher colloid transport from the disturbed soils. In contrast, NO3-N leaching from the intact soil was higher for all events except the first event, probably due to a lower nitrification rate in the disturbed soil. A week after the last irrigation event, the redistribution of all slurry constituents except NO3-N in most of the sections of the soil column was higher for the disturbed soil. Total recovery of E. coli was significantly higher from the disturbed soil and total leaching of mineral nitrogen was significantly lower

  6. Factors influencing competitive anxiety in Brazilian athletes

    Directory of Open Access Journals (Sweden)

    Marcos Gimenes Fernandes

    2013-09-01

    Full Text Available The study of factors influencing competitive anxiety, according to a multidimensional perspective and supported by valid instruments, is scarce among Brazilian athletes of different sports. The present study aims to: i investigate the theoretical relationship between the different dimensions of the multidimensional theory of anxiety (i.e., cognitive anxiety, somatic anxiety and self-confidence; and ii investigate the effects of gender, type of sport (individual or collective and competitive experience levels on cognitive anxiety, somatic anxiety and self-confidence. A total of 303 athletes (233 males and 70 females, from different sports, aged between 18 and 40 years (M =24.22, SD = 5.07 completed a shortened version of CSAI-2 (i.e., CSAI-2R, about one hour before the start of competitions. Results revealed significant correlations between cognitive anxiety, somatic anxiety and self-confidence dimensions, in accordance with the assumptions of the multidimensional theory. Additionally, comparative analyses indicated that female athletes and athletes from collective sports showed higher levels of cognitive anxiety, while male athletes and athletes with high competitive experience reported higher levels of self-confidence. These results were discussed taking into account the theoretical and practical implications of these findings for planning interventions of sport psychology in Brazil with athletes of different contexts.

  7. Factors That Influence Primary Cilium Length

    Directory of Open Access Journals (Sweden)

    Miyoshi,Ko

    2011-10-01

    Full Text Available Almost all mammalian cells carry one primary cilium that functions as a biosensor for chemical and mechanical stimuli. Genetic damages that compromise cilia formation or function cause a spectrum of disorders referred to as ciliapathies. Recent studies have demonstrated that some pharmacological agents and extracellular environmental changes can alter primary cilium length. Renal injury is a well-known example of an environmental insult that triggers cilia length modification. Lithium treatment causes primary cilia to extend in several cell types including neuronal cells;this phenomenon is likely independent of glycogen synthase kinase-3β inhibition. In renal epithelial cell lines, deflection of the primary cilia by fluid shear shortens them by reducing the intracellular cyclic AMP level, leading to a subsequent decrease in mechanosensitivity to fluid shear. Primary cilium length is also influenced by the dynamics of actin filaments and microtubules through the levels of soluble tubulin in the cytosol available for primary cilia extension. Thus, mammalian cells can adapt to the extracellular environment by modulating the primary cilium length, and this feedback system utilizing primary cilia might exist throughout the mammalian body. Further investigation is required concerning the precise molecular mechanisms underlying the control of primary cilium length in response to environmental factors.

  8. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    Energy Technology Data Exchange (ETDEWEB)

    Stitt, Caroline R. [Mills College, Oakland, CA (United States)

    2013-09-16

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

  9. Soil types and limiting factors in agricultural production in the San Fernando district, Tamaulipas, Mexico; Tipos de suelo y factores limitantes en la produccion agropecuaria en el distrito San Fernando, Tamaulipas, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa Ramirez, M.; Garza Cedillo, R.; Andrade limas, E.; Belmonte Serrato, F.

    2009-07-01

    The limiting factors in agricultural production, defined as those properties and characteristics of the geographical environment that influence the development of crops, can be diverse and are grouped with the physical environment of soil. They are the result of soil characteristics and soil degradation processes by anthropogenic influence. Due to the above, the objective of this study was to identify and surveying the limitative factors to agricultural production, as well as to define its ability land use capacity in San Fernando district, Tamaulipas. (Author) 7 refs.

  10. Forest management type influences diversity and community composition of soil fungi across temperate forest ecosystems

    Directory of Open Access Journals (Sweden)

    Kezia eGoldmann

    2015-11-01

    Full Text Available Fungal communities have been shown to be highly sensitive towards shifts in plant diversity and species composition in forest ecosystems. However, little is known about the impact of forest management on fungal diversity and community composition of geographically separated sites. This study examined the effects of four different forest management types on soil fungal communities. These forest management types include age class forests of young managed beech (Fagus sylvatica L., with beech stands age of approximately 30 years, age class beech stands with an age of approximately 70 years, unmanaged beech stands, and coniferous stands dominated by either pine (Pinus sylvestris L. or spruce (Picea abies Karst. which are located in three study sites across Germany. Soil were sampled from 48 study plots and we employed fungal ITS rDNA pyrotag sequencing to assess the soil fungal diversity and community structure.We found that forest management type significantly affects the Shannon diversity of soil fungi and a significant interaction effect of study site and forest management on the fungal OTU richness. Consequently distinct fungal communities were detected in the three study sites and within the four forest management types, which were mainly related to the main tree species. Further analysis of the contribution of soil properties revealed that C/N ratio being the most important factor in all the three study sites whereas soil pH was significantly related to the fungal community in two study sites. Functional assignment of the fungal communities indicated that 38% of the observed communities were Ectomycorrhizal fungi (ECM and their distribution is significantly influenced by the forest management. Soil pH and C/N ratio were found to be the main drivers of the ECM fungal community composition. Additional fungal community similarity analysis revealed the presence of study site and management type specific ECM genera.This study extends our knowledge

  11. [Advance in researches on vegetation cover and management factor in the soil erosion prediction model].

    Science.gov (United States)

    Zhang, Yan; Yuan, Jianping; Liu, Baoyuan

    2002-08-01

    Vegetation cover and land management are the main limiting factors of soil erosion, and quantitative evaluation on the effect of different vegetation on soil erosion is essential to land use and soil conservation planning. The vegetation cover and management factor (C) in the universal soil loss equation (USLE) is an index to evaluate this effect, which has been studied deeply and used widely. However, the C factor study is insufficient in China. In order to strengthen the research of C factor, this paper reviewed the developing progress of C factor, and compared the methods of estimating C value in different USLE versions. The relative studies in China were also summarized from the aspects of vegetation canopy coverage, soil surface cover, and root density. Three problems in C factor study were pointed out. The authors suggested that cropland C factor research should be furthered, and its methodology should be unified in China to represent reliable C values for soil loss prediction and conservation planning.

  12. Transfer factors of radionuclides from paddy soils to polished rice

    Energy Technology Data Exchange (ETDEWEB)

    Komamura, Misako; Tsumura, Akito; Yuita, Kouichi; Yamasaki, Shin-ichi [National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan); Kodaira, Kiyoshi

    1996-12-31

    The present studies were conducted in order to estimate the transfer factors of radionuclides from paddy soils to polished rice using the {sup 90}Sr and {sup 137}Cs survey data and analytical data obtained by conventional radiometric and ICP-MS methods. Soils and rices samples were collected nationwide from 15 paddy fields of National and Prefectural Experiment Stations in 1990 when the amount of radioactive fallout was extremely low (the direct contaminations to rice by {sup 90}Sr and {sup 137}Cs are neglected). The highest transfer factors were observed among the alkali metals (K {>=} Rb >> {sup 137}Cs > Cs), followed by alkaline-earth metals (Ca {>=} {sup 90}Sr > Sr {>=} Ba), last came the lanthanoids (La, Ce, Nd, Sm, Gd, Lu) and Th, U which all showed extremely low values. The transfer factors (average) of typical elements were as follows, {sup 40}K: 1.0 x 10{sup -1}, Rb: 3.3 x 10{sup -2}, {sup 137}Cs: 2.6 x 10{sup -3}, Cs: 7.8 x 10{sup -4}, Ca: 5.8 x 10{sup -3}, {sup 90}Sr: 4.8 x 10{sup -3}, Sr: 7.4 x 10{sup -4}, Ba: 5.0 x 10{sup -4}, La: 1.5 x 10{sup -4}, Ce: 4.5 x 10{sup -5}, Sm: 6.6 x 10{sup -5}, Lu: 8.8 x 10{sup -5}, Bi: 2.2 x 10{sup -4}, Th: 1.5 x 10{sup -4}, and U: 1.9 x 10{sup -4}. It was found that the transfer factors of fallout {sup 90}Sr and {sup 137}Cs were 4-6 times higher than those of natural Sr and Cs. (author)

  13. Influence of Xenobiotic Substances on Actinomycete Comunities in Soil

    OpenAIRE

    2012-01-01

    Sulfonylurea herbicides are frequently used in agricultural crops even if they determine quantitative and qualitativechanges in soil microbial communities. In this study it was used increasing doses of two sulfonylurea herbicides,tribenuron-methyl and nicosulfuron, in order to establish their effect on actinomyces communities from soil underlaboratory conditions. Using nutritive gelose with soil extract and Gause medium the main species of actinomyceswere identified: Streptomyces albus, Strep...

  14. Investigation on prevalence of soil-transmitted nematode infections and influencing factors for children in southwest areas of China%中国西南地区儿童土源性线虫感染及影响因素调查

    Institute of Scientific and Technical Information of China (English)

    王晓兵; Scott Rozelle; 王国飞; 张林秀; 罗仁福; 田洪春; 唐丽娜; 王聚君; Alexis Medina; Paul Wise

    2012-01-01

    Objective To understand the infection status and main risk factors of soil-transmitted nematodes in southwest China so as to provide the evidence for making the control programs for soil-transmitted nematodiasis. Methods The prevalence of soil-transmitted nematode infections was determined by Kato-Katz technique and influencing factors were surveyed by using a standardized questionnaire, and in part of the children, the examination of Enterobius vermicularis eggs was performed by using ihe cellophane swab method. The relationship between soil-transmitted nematode infections and influencing factors was analyzed by the multiple probit estimated method. Results A total of 1 707 children were examined, with a soil-transmitted nematode infection rate of 22.2%, the crowd infection rates oiAscaris lumhricoides, hookworm, and Trichuris trichiura were 16.0%, 3.8% and 6.6% respectively and 495 children were examined on Enterobius vermicularis eggs, with the infection rate of 5.1%. The results of probit estimated analysis suggested that the effects of 4 factors on soil-transmitted nematode infections were significant (all P values were less than 0.05) .namely the number of sib, educational level of mother, drinking unboiled water and raising livestock and poultry. Among the factors above, the educational level of mother could reduce the probability of infection (ME= -0.074) ,while the number of sib, drinking unboiled water and raising livestock and poultry could increase the probability of the infections (with ME of 0.028,-0.112 and 0.080, respectively). Conclusions Soil-transmitted nematode infection rates are still in a high level for children in southwest poor areas of China, with Ascaris lumbricoides as a priority. The changes of children' s bad health habits, raising livestock and poultry habits, and implementing the health education about parasitic diseases in mothers would be of great significance for the prevention and control of soil-transmitted nematodiasis

  15. Influence of hydraulic hysteresis on the mechanical behavior of unsaturated soils and interfaces

    Science.gov (United States)

    Khoury, Charbel N.

    Unsaturated soils are commonly widespread around the world, especially at shallow depths from the surface. The mechanical behavior of this near surface soil is influenced by the seasonal variations such as rainfall or drought, which in turn may have a detrimental effect on many structures (e.g. retaining walls, shallow foundations, mechanically stabilized earth walls, soil slopes, and pavements) in contact with it. Thus, in order to better understand this behavior, it is crucial to study the complex relationship between soil moisture content and matric suction (a stress state variable defined as pore air pressure minus pore water pressure) known as the Soil Water Characteristic Curve (SWCC). In addition, the influence of hydraulic hysteresis on the behavior of unsaturated soils, soil-structure interaction (i.e. rough and smooth steel interfaces, soil-geotextile interfaces) and pavement subgrade (depicted herein mainly by resilient modulus, Mr) was also studied. To this end, suction-controlled direct shear tests were performed on soils, rough and smooth steel interfaces and geotextile interface under drying (D) and wetting after drying (DW). The shearing behavior is examined in terms of the two stress state variables, matric suction and net normal stress. Results along the D and DW paths indicated that peak shear strength increased with suction and net normal stress; while in general, the post peak shear strength was not influenced by suction for rough interfaces and no consistent trend was observed for soils and soil-geotextiles interfaces. Contrary to saturated soils, results during shearing at higher suction values (i.e. 25 kPa and above) showed a decrease in water content eventhough the sample exhibited dilation. A behavior postulated to be related to disruption of menisci and/or non-uniformity of pore size which results in an increase in localized pore water pressures. Interestingly, wetting after drying (DW) test results showed higher peak and post peak shear

  16. Studies on Characteristics of Organic Matter Contents Distribution and Influence Factors in Longhui Soil of Tobacco Growing Areas%隆回植烟土壤有机质含量分布特征及其影响因素研究

    Institute of Scientific and Technical Information of China (English)

    孙书斌; 于庆涛; 姚雪梅; 杨虹琦; 刘光辉; 张保全

    2015-01-01

    为揭示隆回植烟土壤有机质含量分布特征及其影响因素,提高烤烟生产施肥的科学性,采用传统统计学、相关分析、回归分析以及灰色关联方法分析了隆回植烟土壤有机质含量分布特点及其影响因素。结果表明:①隆回烟区植烟土壤有机质含量平均值为32.22 g/kg,处于“适宜”水平,处于“适宜”范围内的样本占51.0%;②4种不同土类之间有机质含量达到极显著差异,有机质含量在“适宜”水平的土壤样本数比例为红壤>石灰岩土>黄壤>水稻土;③6种不同土壤质地间有机质含量存在极显著差异,其中轻壤土、砂壤土和中壤土有机质含量处于“适宜”水平的比例较高;④植烟土壤全氮、有效磷和全钾含量偏高,碱解氮含量适宜,全磷和速效钾含量偏低;⑤影响植烟土壤有机质含量分布的土壤养分因素有土壤氮素、磷素以及钾素,对有机质含量分布影响大小顺序为碱解氮>速效钾>全钾>全磷>有效磷>全氮;⑥有机质含量随碱解氮、有效磷和速效钾含量的升高而提高,而全氮、全钾和全磷与有机质含量之间呈二次曲线关系。%In order to reveal the distribution characteristics of organic matter contents and the influence factors in tobacco planting soil at Longhui area, and improve the fertilization of flue-cured tobacco production, this paper analyzed the distribution characteristics of organic matter contents and the influence factors by traditional statistics, correlation analysis, regression analysis and grey correlation method. The results indicated that ① the organic matter contents in soil of Longhui tobacco growing areas was in the "appropriate" level with 32. 22 g/kg mean value, and 51.0% samples were in the "appropriate" level;② the contents of organic matter of 4 different agro-type soils were significantly different, and the percent of samples in the "appropriate" level was red soil

  17. Soil type influence on Ag Nanoparticles by earthworms, Eisenia fetida

    DEFF Research Database (Denmark)

    Mariyadas, Jennifer; Mónica, Amorim; Scott-Fordsmand, Janeck James

    2014-01-01

    Earthworms are key sentinel organisms playing an important role in improving the soil structure. Here we tested the importance of soil type on the toxicity to silver nanoparticles (Ag NPs) to earthworms, Eisenia fetida. Silver nanoparticles are widely used in a range of consumer products mainly...... as antibacterial agents and thus causes potential risk to the environment once these particles are released into the environment [1]. In our tests, we were able to show that the earthworm toxicity was strongly dependent on the soil type, with strongest effect in low organic matter soil. Studies on the organic...

  18. Meadow soil microbiocoenosis under influence of railway transport

    Directory of Open Access Journals (Sweden)

    N. J. Bobryk

    2012-07-01

    Full Text Available A case study of the microbial coenosis status of the soil of meadow ecosystem at different distances from the railway track was carried out in the urbansettlement Velykyi Bereznyi in the Transcarpathian Region. The increasing technogenic pollution causes changes in the complex of microbiological indices, brings about qualitative and quantitative changes in the functioning of microbial cenosis of the soil. That has a negative impact on its potential fertility, and raises phytotoxic levels in soils. The results show that soils phytotoxic hyperactivity of ecosystems along the mainline correlates with the quantity of actinomycetes, coliforms, oligonitrophilc and cryptogamous microorgamisms.

  19. Soil moisture, temperature, and carbon substrate influences on soil respiration in a piñon-juniper woodland

    Science.gov (United States)

    Berryman, E.; Marshall, J. D.; Rahn, T.; Litvak, M. E.

    2010-12-01

    Arid and semi-arid ecosystems may be more vulnerable to climate change than mesic systems, having potentially large consequences for ecosystem carbon balance of the US southwest. Specifically, piñon-juniper woodlands cover much of the land area in the SW US, and they have experienced widespread piñon mortality in the past ten years. The impact of this mortality on carbon cycling in these ecosystems has yet to be fully examined. Of particular current interest is how soil temperature, soil moisture, and substrate availability interact to influence short-term variability of soil respiration rates. In this study, we examined the dependence of soil respiration on recent piñon photosynthate, temperature, and moisture in a piñon-juniper woodland in central New Mexico. We utilized phloem-girdling to study the importance of recently-fixed photosynthate as substrate for respiration, and we treated the stable carbon isotope ratio of soil respiration as indicative of different substrate sources contributing to soil respiration. Due to the presence of C3, C4, and CAM photosynthetic pathways in the ecosystem, we were able to infer changing contribution of different sources to soil respiration. We found that soil-respired δ13C depended on both soil moisture and lagged precipitation, although in dissimilar manners, suggesting different mechanisms are triggered by rainfall events compared to elevated soil moisture. C3-source respiration responded quickly to precipitation events. Over a ten-day period following girdling of piñon trees, soil-respired δ13C did not significantly change compared to a reference plot. There were also distinct differences in carbon isotope signatures and temporal patterns of such signatures of soil respiration collected in open spaces compared to underneath piñon canopies, emphasizing the importance of considering spatial variability when sampling soil-respired CO2 in patchy ecosystems. Overall, we found little evidence that soil respiration in

  20. Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

    Directory of Open Access Journals (Sweden)

    Jie Tang

    2016-02-01

    Full Text Available The study of greenhouse gas emissions has become a global focus, but few studies have considered saline-alkali paddy fields. Gas samples and saline-alkali soil samples were collected during the green, tillering, booting, heading and grain filling stages. The emission fluxes of CO2, CH4, and N2O as well as the pH, soil soluble salt, available nitrogen, and soil organic carbon contents were detected to reveal the greenhouse gas (GHG emission laws and influence factors in saline-alkali paddy fields. Overall, GHG emissions of paddy soil during the growing season increased, then decreased, and then increased again and peaked at booting stage. The emission fluxes of CO2 and CH4 were observed as having two peaks and a single peak, respectively. Both the total amount of GHG emission and its different components of CO2, CH4, and N2O increased with the increasing reclamation period of paddy fields. A positive correlation was found between the respective emission fluxes of CO2, CH4, and N2O and the available nitrogen and SOC, whereas a negative correlation was revealed between the fluxes of CO2, CH4, and N2O and soil pH and soil conductivity. The study is beneficial to assessing the impact of paddy reclamation on regional greenhouse gas emissions and is relevant to illustrating the mechanisms concerning the carbon cycle in paddy soils.

  1. Influence of perennial plants on chemical properties of arid calcareous soils in Iran

    Energy Technology Data Exchange (ETDEWEB)

    Karimian, N.; Razmi, K. (Shiraz Univ. (Iran))

    1990-10-01

    The authors conducted a study in Bajgah to determine the influence of perennial plants on some selected properties of soils formed on the highly calcareous parent material. The major plant genera were determined to be Agropyron, Artemisia, Astragalus, Dianthus, Eryngium, Peganum, Polygonum, Stipa, and Thymus. Tops of plants genera were found to be significantly different in ash, N, P, K, Ca, Mg, Na, Mn, Zn, and Cu; the concentration of Fe was not significantly different. The authors found the plants to differ significantly in their influence on soil properties. Peganum caused an accumulation of organic matter (OM) as high as 7% in the soil, in an environment where the soils typically contain less than 1% OM. Soil concentrations of P, K, Mn, Zn, and Cu were also found to vary significantly beneath different plant genera. They suggest these differences in OM accumulation were caused by plant litter. Concentration of Fe in the soils formed beneath different plant genera was statistically unchanged.

  2. Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

    Science.gov (United States)

    Croft, H.; Anderson, K.

    2012-04-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variabl