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PubMed2003

[Degradation of metsulfuron-methyl in soils. I. Effect of soil properties].

The ANOVA results showed that degradation of metsulfuron-methyl was different among various soils. Five principal factors were selected by principal factor analysis and they represented 90.4% of total information. The multivariate regression equations were established between soil properties and metsulfuron-methyl residues after stepwise regression analysis. The partial correlation and path analysis indicated that soil pH and microbial activity were the most significant factors controlling the degradation of metsulfuron-methyl in soils.

Analysis of Variance↗
PubMed1976

Sulfate reduction in poorly-drained soils as influenced by organic matter and soil texture.

Investigations of the influence of added organic matter content (rice straw or clover) on the reduction of added sulfate (8 meq/100 g soil) following submergence and incubation of 120 days gave these results: 1. In soils with native organic matter (humus) the rate of sulfate reduction was very low; it slightly increased with increased clay content of the soils. 2. The addition of undecomposed organic matter led to a complete reduction of the added sulfates within 120 days. 3. The varying C/N ratio of the added organic matter appeared to have no influence on the sulfate reduction. 4. As a qualitative indication of the reduction the soil darkened after three weeks of incubation, and an odour of H2S was detected.

Oxidation-Reduction↗
PubMed2002

In situ spatial patterns of soil bacterial populations, mapped at multiple scales, in an arable soil.

Very little is known about the spatial organization of soil microbes across scales that are relevant both to microbial function and to field-based processes. The spatial distributions of microbes and microbially mediated activity have a high intrinsic variability. This can present problems when trying to quantify the effects of disturbance, management practices, or climate change on soil microbial systems and attendant function. A spatial sampling regime was implemented in an arable field. Cores of undisturbed soil were sampled from a 3 x 3 x 0.9 m volume of soil (topsoil and subsoil) and a biological thin section, in which the in situ distribution of bacteria could be quantified, prepared from each core. Geostatistical analysis was used to quantify the nature of spatial structure from micrometers to meters and spatial point pattern analysis to test for deviations from complete spatial randomness of mapped bacteria. Spatial structure in the topsoil was only found at the microscale (micrometers), whereas evidence for nested scales of spatial structure was found in the subsoil (at the microscale, and at the centimeter to meter scale). Geostatistical ranges of spatial structure at the micro scale were greater in the topsoil and tended to decrease with depth in the subsoil. Evidence for spatial aggregation in bacteria was stronger in the topsoil and also decreased with depth in the subsoil, though extremely high degrees of aggregation were found at very short distances in the deep subsoil. The data suggest that factors that regulate the distribution of bacteria in the subsoil operate at two scales, in contrast to one scale in the topsoil, and that bacterial patches are larger and more prevalent in the topsoil.

Agriculture↗
PubMed1992

Distinguishing outdoor soil ingestion from indoor dust ingestion in a soil pica child.

This paper represents the first quantitative attempt to distinguish the amount of outdoor soil ingestion from indoor dust ingestion in a soil pica child. Based on a methodology using a comparison of differential element ratios it is estimated that the predominant proportion of the fecal tracers were from outdoor soil and not indoor dust origin. The methodology employed can be utilized on a broader scale to assess the relative amounts of soil and dust consumed by individuals.

Child↗
PubMed2006

Integrated treatment of PAH contaminated soil by soil washing, ozonation and biological treatment.

The aim of the study was to optimise three different treatment methods and to find out if the integration of soil washing, ozonation and biological treatment could be a feasible method for the remediation of aged oil contaminated with PAHs. Three different ozone doses and soil washing were studied in different pHs in order to assess their effect to the degradation and enhancement of biodegradability of PAH in the soil and water phase. Main target of the study was to find out a method with which the PAH concentrations could be decreased below the Finnish guideline level for total PAHs. In this case, the initial concentration of PAHs was 1200 mg kg(-1) and therefore almost 85% degradation of PAHs was required. Any of the methods studied was not able to reach this target level alone, but by several combinations of the methods studied achieved 90% reduction of PAHs. The consumption of ozone was 5-10 times lower in the integrated treatments of soil washing, ozonation and biological treatment than without prewashing.

Environmental Restoration and Remediation↗
PubMed2002

Estimation of soil organic partition coefficients: from retention factors measured by soil column chromatography with water as eluent.

The retention factors (k) of 104 hydrophobic organic chemicals (HOCs) were measured in soil column chromatography (SCC) over columns filled with three naturally occurring reference soils and eluted with Milli-Q water. A novel method for the estimation of soil organic partition coefficient (Koc) was developed based on correlations with k in soil/water systems. Strong log Koc versus log k correlations (r>0.96) were found. The estimated Koc values were in accordance with the literature values with a maximum deviation of less than 0.4 log units. All estimated Koc values from three soils were consistent with each other. The SCC approach is promising for fast screening of a large number of chemicals in their environmental applications.

Organic Chemicals↗
PubMed1999

Soil thin-layer chromatography and pesticide mobility through soil microstructures. New technical approach.

Soil thin-layer chromatography with water or water-methanol as solvents allows observation and measurement of the mobility of labelled pesticides through soil microstructures. Eleven different sieved matrices were studied: pure humine, pure clays, schists and soils. Ionized compounds (paraquat, glyphosate) were tightly bound to these matrices. The other compounds, lipophilic and generally non-ionized ones, migrated in the same order on most of the studied matrices, either mineral or organic: R(F) atrazine=isoproturon>diuron=fipronil>phenmedipham. This order was roughly correlated to log P but much more complex correlations were suggested. The rate of water movement, VWR, widely changed from one matrix to another. Therefore, the pesticide movement, M, in soil microstructures under the action of rain may be described by the equation M = WR R(F).

Atrazine↗
PubMed2001

Effectiveness of an anaerobic granular activated carbon fluidized-bed bioreactor to treat soil wash fluids: a proposed strategy for remediating PCP/PAH contaminated soils.

An integrated system has been developed to remediate soils contaminated with pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAHs). This system involves the coupling of two treatment technologies, soil-solvent washing and anaerobic biotreatment of the extract. Specifically, this study evaluated the effectiveness of a granular activated carbon (GAC) fluidized-bed reactor to treat a synthetic-waste stream of PCP and four PAHs (naphthalene, acenaphthene, pyrene, and benzo(b)fluoranthene) under anaerobic conditions. This waste stream was intended to simulate the wash fluids from a soil washing process treating soils from a wood-preserving site. The reactor achieved a removal efficiency of greater than 99.8% for PCP with conversion to its dechlorination intermediates averaging 46.5%. Effluent, carbon extraction, and isotherm data also indicate that naphthalene and acenaphthene were removed from the liquid phase with efficiencies of 86 and 93%, respectively. Effluent levels of pyrene and benzo(b)fluoranthene were extremely low due to the high-adsorptive capacity of GAC for these compounds. Experimental evidence does not suggest that the latter two compounds were biochemically transformed within the reactor.

Acenaphthenes↗
PubMed2000

Baltic soil survey: total concentrations of major and selected trace elements in arable soils from 10 countries around the Baltic Sea.

Agricultural soils were collected from 10 European countries over a 1,800,000 km2 area surrounding the Baltic Sea. The sampling density was 1 site/2500 km2. Two samples were taken at each site: topsoil 0-25 cm (ploughing layer, Ap-horizon) and subsoil (bottom samples, usually B- or C-horizon) at an approximate depth of 50-75 cm, well below the ploughed layer. The samples were analysed for total element concentrations of 41 elements by WD-XRF. Analytical results for both layers are quite comparable. Large differences between element concentrations and variations can be observed for most elements when the different countries are compared. The Nordic countries show considerably higher concentrations and variations for quite a number of elements [Al, Fe, (Mg, P), Ti, Ba, Sc, Sr, V] in their agricultural soils. This is an expression of geology, the relatively younger age of the soils here and of the climatic conditions (reduced weathering rates). Regional geochemical maps demonstrate that geology overwhelmingly dominates the total concentration of chemical elements as observed in the agricultural soils. The three (four) large tectonic units (Caledonian mountain chain, Fennoscandian Shield and the northern and southern eastern European Platform) composing this area are all reflected in the regional maps.

Agriculture↗
PubMed2001

A review of the contamination of soil with lead II. Spatial distribution and risk assessment of soil lead.

Contamination of soil with lead has occurred on a global scale. Exposure to lead may cause adverse effects to human health and the environment. It is therefore desirable to obtain a quantitative estimate of the potential risk of lead contamination. Numerous studies have been conducted collecting lead concentration data from both natural and contaminated soil on a range of scales. Very few of these studies have made serious attempts to spatially describe the data. In order to identify contaminated land and to enable development of appropriate environmental guidelines, it is essential to have an understanding of the universal range of lead concentrations. Such data also assists in assessing any potential risk to the environment or human health. This paper reviews the multitude of data collected on soil Pb concentrations. Lead surveys are discussed on the basis of land use, with Australian data presented separately. Data from lead surveys of agricultural, urban and industrial areas, as well as nationwide surveys are summarised. A small but increasing number of studies have employed spatial prediction techniques such as kriging to map the distribution of lead concentrations in soil. These studies are also summarised and a brief description of the basis for their use presented. Finally, environmental and health risk assessment is discussed and some methodologies in use around the world reviewed.

Agriculture↗
PubMed1999

Method for purification of bacterial endospores from soils: UV resistance of natural Sonoran desert soil populations of Bacillus spp. with reference to B. subtilis strain 168.

Endospores of Bacillus spp. were purified from three Sonoran desert soil samples by Chelex extraction and NaBr density gradient centrifugation and their UV resistances compared with that of B. subtilis strain 168. Natural spore populations exhibited tight adherence to soil particles which was not readily overcome by the extraction and purification procedure. It was observed that spores purified from soil exhibited 2-3 fold higher resistance to UV (as measured by the 90% lethal dose, LD90) than did B. subtilis strain 168 grown on NSM, a standard laboratory sporulation medium, and purified by the same extraction procedure. Cultivation of spore-forming bacteria isolated from soil on NSM resulted in production of spores with essentially identical UV resistance as strain 168, suggesting that spore UV resistance is influenced by the environment in which spores are produced.

Bacillus↗
PubMed2002

Axi-symmetric simulation of soil vapor extraction influenced by soil fracturing.

Fracturing, either pneumatic or hydraulic, is a method to improve the performance of soil vapor extraction (SVE) in relatively low permeability soils (< 10(-5) cm/s). A two-dimensional model is presented to simulate trichloroethylene (TCE) soil vapor extraction modified by fracturing. Flow and transport is modeled using mobile macropore and micropore networks, which also have been identified in the literature as dual porosity, dual permeability, or heterogeneous flow models. In this model, fluids can flow in both the macropore and micropore networks. This represents a more general model compared to immobile micropore, mobile macropore models presented thus far in the literature for vapor flow and transport in two dimensions. The model considers pressure- and concentration-driven exchange between the macropore and micropore networks, concentration-driven exchange between the gas and sorbed phases within each network, and equilibrium exchange between the gas and water and a sorbed phase within each network. The parameters employed in an example simulation are based on field measurements made at a fractured site. Considered in the simulations were the influence of the volume percentage of fractures, the length of fractures, the relative location of the water table, and the influence of pulsed pumping. For these simulations, internetwork concentration-driven exchange most significantly affected mass removal. The volume percentage of fractures more significantly influence flow and mass removal than the length of fractures. The depth of the water table below the contamination plume only significantly influenced flow and mass removal when the water table was within 60 cm of the bottom of the contaminated soil in the vadose zone for the parameters considered in this study. Pulsed pumping was not found to increase the amount of mass removed in this study.

Adsorption↗
PubMed2001

A 10-year study of the 137Cs distribution in soil and a comparison of Cs soil inventory with precipitation-determined deposition.

During a 10-year period, 1988-1998, surface soil samples have been collected at Blentarp in southern Sweden and analysed for 137Cs from the Chernobyl accident and from the nuclear weapons tests. The distance between the sampling plots on the different sampling occasions has been no more than 3 m. The results show that the depth distribution of 137Cs is very similar for each of the sampling occasions, indicating that the caesium migration at this site is very small. The total activity measured in the soil cores is in agreement with the calculated activity of 137Cs deposited at the site after nuclear weapons tests and the Chernobyl accident, based on air activity concentration and the amount of precipitation. The calculated deposition of 137Cs originating from the bomb tests amounts to 1.41 kBq m-2 for the period 1962-1986, which is in agreement with the activity of nuclear weapons fallout measured in the soil samples (1.60 kBq m-2 as a mean value of the first four years of sampling). The calculated activity of 137Cs of Chernobyl origin was 0.79 kBq m-2, which agrees well with the value of 0.79 kBq m-2 measured in the soil samples in 1988.

Cesium Radioisotopes↗
PubMed1999

Simplified soil washing processes for a variety of soils.

A soil washing process is described in which high shear mixing, sprays, hydrosizing, flotation, and screening are integrated to countercurrently clean sand, silt and clay. Chemical techniques are summarized that can be used to remove selected contaminants from the soil and then clean the wash water for reuse. Descriptions of simple and complex processes, and a recent project are used to illustrate the points: (1) Soil washing is not a single process, but a collection of unit operations assembled for each project; (2) all process must be coordinated for the project to be successful; and (3) combining techniques in a few pieces of equipment debottlenecks soil washing.

Decontamination↗
PubMed2004

Geostatistical approach for assessing soil volumes requiring remediation: validation using lead-polluted soils underlying a former smelting works.

Assessing the volume of soil requiring remediation and the accuracy of this assessment constitutes an essential step in polluted site management. If this remediation volume is not properly assessed, misclassification may lead both to environmental risks (polluted soils may not be remediated) and financial risks (unexpected discovery of polluted soils may generate additional remediation costs). To minimize such risks, this paper proposes a geostatistical methodology based on stochastic simulations that allows the remediation volume and the uncertainty to be assessed using investigation data. The methodology thoroughly reproduces the conditions in which the soils are classified and extracted at the remediation stage. The validity of the approach is tested by applying it on the data collected during the investigation phase of a former lead smelting works and by comparing the results with the volume that has actually been remediated. This real remediated volume was composed of all the remediation units that were classified as polluted after systematic sampling and analysis during clean-up stage. The volume estimated from the 75 samples collected during site investigation slightly overestimates (5.3% relative error) the remediated volume deduced from 212 remediation units. Furthermore, the real volume falls within the range of uncertainty predicted using the proposed methodology.

Environmental Pollution↗
PubMed2006

Comparison of soil Pb in vitro bioaccessibility and in vivo bioavailability with Pb pools from a sequential soil extraction.

In this study, 15 soils ranging in Pb content from 32 to 6330 mg kg(-1) were subjected to in vitro gastrointestinal extractions with and without added powdered milk. Before and after treatment, Pb in the soils was fractionated according to a 7-step sequential extraction procedure. A subset of five soils and Pb acetate was used for a minipig dosing study. The amount of bioaccessible Pb determined with the in vitro system ranged from 3 to 20% without powdered milk and from 11 to 56% with powdered milk. The higher bioaccessibility of Pb in the in vitro model with addition of powdered milk was related to a depletion of Pb in the organic Pb pool and indicates that soluble milk constituents compete with soil organic ligands for Pb. The absolute and relative bioavailabilities of Pb in the minipig dosing experiment were not related to bioaccessible Pb determined in any of the two in vitro systems. However, relative bioavailabilities in liver, kidney, and total uptake were highly correlated to Pb in the third fraction of the sequential extraction that is attributed to easily reducible Mn oxides. These results indicate that reductive processes in the intestine may be more relevant for Pb absorption than the initial solubilization in the acidic stomach.

Animals↗
PubMed2005

Influence of soil properties on the adsorption-desorption of sulcotrione and its hydrolysis metabolites on various soils.

The retention process of sulcotrione and its two hydrolysis products, 1,3-cyclohexanedione (CHD) and 2-chloro-4-methylsulfonylbenzoic acid (CMBA), were studied in four different soils (Belgium, Landes, Perpignan, and Martinique) under laboratory conditions. Adsorption isotherms were well fitted by a Freundlich relationship. The values of K(fa) ranged from 0.4 to 27.0, and the most adsorbed compound was CHD regardless the soil type. Sulcotrione and CMBA exhibited similar retention behaviors. According to adsorption and desorption results, sulcotrione presents a moderate affinity with soil components; however, its leaching capacity needs to be carefully assessed. Clay content seemed to be the most important factor influencing the adsorption capacity of each compound, whereas organic matter and pH had little influence. The soils were classified according to their adsorption capacity in the following decreasing order: Martinique, Belgium, Landes, Perpignan.

Adsorption↗
PubMed2006

Influence of the soil composition on the effects of benzoxazinoid allelochemicals on two soil nontarget organisms.

Seven selected benzoxazinoid allelochemicals and synthetic reference compounds were tested for their lethal and sublethal effects in different field soils and standard soil on Folsomia candida and Poecilus cupreus by applying standard laboratory test procedures. The higher microbial activity in the field soils was most probably responsible for the reduced effects of test compounds on F. candida in the majority of all tests, whereas the higher organic carbon content in field soils was likely the reason for the reduced effects of test substances on P. cupreus.

Animals↗