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At least 253 records · Page 14Linked to original sources
PubMed2003

The effect of application time and soil factors on the occurrence of Beauveria brongniartii applied as a biological control agent in soil.

The effects of abiotic and biotic soil factors on occurrence of the entomopathogenic fungus Beauveria brongniartii after application at different times of the year were examined in Switzerland. Applications made from May to August generally resulted in an increase of 1-5 x 10(3) CFU g(-1) dry soil compared to untreated control plots. Conversely, soils treated in October and November yielded no increase. Soil temperatures between 20 and 25 degrees C, and high clay content of the soil had a positive effect on the occurrence and density of B. brongniartii whereas increased catalase activity and temperatures above 27 degrees C had a negative influence. Laboratory experiments revealed that a higher number of CFUs developed after one month of incubation at 22 degrees C than at 12 degrees C. Differences were not detected after three months of incubation, indicating that growth rate was simply slower at sub-optimal temperatures. The increase was different in three native soils, but was not correlated with different clay contents of the soil. In sterilized soil, though, the differences were not detected, suggesting that biotic factors have a greater influence rather than soil texture.

Animals↗
PubMed2006

Using soil biomass as an indicator for the biological removal of effluent-derived organic carbon during soil infiltration.

This study investigates the relationship between soil biomass and organic carbon removal during the infiltration of conventionally treated effluents used for groundwater recharge during soil-aquifer treatment (SAT). Investigations were conducted on samples collected from full-scale SAT sites, revealing a positive correlation between biodegradable organic carbon (BOC) concentrations in the recharged effluents and total viable soil biomass concentrations in the infiltration zone of soil samples collected from respective recharge basins. Findings of this study suggest that BOC limits soil biomass growth and was able to support a steady-state concentration of viable soil biomass that is characteristic to BOC concentrations introduced with the recharged effluents. All investigated sites indicate that BOC is primarily removed within 30 cm soil depth leading to a significant increase in soil biomass levels (measured as substrate induced respiration (SIR), total viable biomass, and dehydrogenase activity (DHA)). Controlled biological column studies revealed that the primary components of BOC in domestic effluents are organic colloids. Findings of this study support that hydrophobic acids, commonly believed to be recalcitrant, may also be attenuated by biological processes during soil infiltration.

Bacteria↗
PubMed2005

Influence of pH on soil charge characteristics and cadmium sorption in some noncontaminated soils of Indian subtropics.

Concentrations of total dissolved cadmium (Cd) and activity of its free ions in soil solution are suggested to be influenced by soil pH, organic matter (OM) content, cation exchange capacity (CEC), and clay mineralogy. We investigated the sorption of Cd by taking 25-, 50-, and 100-microM Cd solutions in five noncontaminated soils of West Bengal, India, having differing chemical properties with batch sorption experiments. The charge characteristics and point of zero salt effect (PZSE) of all experimental soils were calculated by the potentiometric titration method measuring the adsorption of H+ and OH- on amphoteric surfaces in solutions of varying ionic strength (I). Sorption of Cd was more pronounced at pH levels greater than PZSE for all experimental soils. The CEC, OM content, clay mineralogy, and specific surface area (SSA) also had a great influence on the sorption of Cd from soil solution to soils. The relationships of Cd with those parameters were found to be consistent and the results concluded that Cd sorption in soils is strongly affected by the soil characteristics.

Absorption↗
PubMed2004

Ascomycete diversity in soil-feeding termite nests and soils from a tropical rainforest.

Molecular microbial ecology has revealed remarkable biodiversity - prokaryotic and eukaryotic - in numerous soil environments. However, no culture-independent surveys of the termitosphere exists, although termites dominate tropical rainforests. Here, we focused on soil feeders, building nests with their soil-born faeces, enriched with clay-organic complexes, thus contributing to the improvement of soil fertility. In order to assess the fungal community composition of these termitaries compared with soils not foraged by termites, samples of the two types were collected in the Lopé rainforest, Gabon, and processed for generation of fungal internal transcribed spacer (ITS) clone libraries. Although primers were universal, most of the recovered sequences represented Ascomycete that were previously uncharacterized and the proportions of which reached 72.5% in soils and 80% in termitaries. Their affiliation with identified fungi was analysed in performing a phylogenetic tree based on 5.8S rDNA. Furthermore, the ascomycete communities of soil-feeding termitaries and soils shared only 6.3% of sequences. This discrepancy of composition between soil and nest may result from the building behaviour of termites, as the organic matter in the nest is chemically modified, and some vacant ecological microniches are available for more specialized fungi.

Animals↗
PubMed2006

Soil parent material is a key determinant of the bacterial community structure in arable soils.

The bacterial community composition in soil and rhizosphere taken from arable field sites, differing in soil parent material and soil texture, was analyzed using terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes. Nine sandy to silty soils from North-East Germany could clearly be distinguished from each other, with a relatively low heterogeneity in the community structure within the field replicates. There was a relationship between the soil parent material, i.e. different glacial and aeolian sediments, and the clustering of the profiles from different sites. A site-specific grouping of T-RFLP profiles was also found for the rhizosphere samples of the same field sites that were planted with potatoes. The branching of the rhizosphere profiles corresponded partly with the soil parent material, whereas the effect of the plant genotype was negligible. Selected terminal restriction fragments differing in their relative abundance within the nine soils were analyzed based on the cloning of the 16S rRNA genes of one soil sample. A high phylogenetic diversity observed to include Acidobacteria, Betaproteobacteria, Bacteroidetes, Verrucomicrobia, and Gemmatimonadetes. The assignment of three out of the seven selected terminal restriction fragments to members of Acidobacteria suggested that this group seems to participate frequently in the shifting of community structures that result from soil property changes.

Ecosystem↗
PubMed2006

Diversity of Planctomycetes in soil in relation to soil history and environmental heterogeneity.

Members of the Planctomycetes, which were once thought to occur primarily in aquatic environments, have been discovered in soils on five continents, revealing that these Bacteria are a widespread and numerically abundant component of microbial communities in soil. We examined the diversity of Planctomycetes in soil samples obtained from experimental plots at an agricultural site in order to assess the extent of Planctomycetes diversity in soil, to determine whether management effects such as past land cover and compost addition affected the composition of the Planctomycetes community, and to determine whether the observations made could provide insight into the ecological distribution of these organisms. Analysis of Planctomycetes 16S rRNA gene sequences revealed a total of 312 +/- 35 unique phylotypes in the soil at the site examined. The majority of these Planctomycetes sequences were unique, and the sequences had phylogenetic affiliations that included all major lineages in the Planctomycetaceae, as well as several novel groups of deeply divergent Planctomycetes. Both soil management history and compost amendment had significant effects on the Planctomycetes diversity, and variations in soil organic matter, Ca2+ content, and pH were associated with variations in the Planctomycetes community composition. In addition, Planctomycetes richness increased in proportion to the area sampled and was correlated with the spatial heterogeneity of nitrate, which was associated with the soil management history at the orchard site examined. This report provides the first systematic assessment of the diversity of Planctomycetes in soil and also provides evidence that the diversity of this group increases with area as defined by the general power law description of the taxon-area relationship.

Agriculture↗
PubMed2006

Estimation of soil sorption coefficients of veterinary pharmaceuticals from soil properties.

Environmental exposure assessment of veterinary pharmaceuticals requires estimating the sorption to soil. Soil sorption coefficients of three common, ionizable, antimicrobial agents (oxytetracycline [OTC], tylosin [TYL], and sulfachloropyridazine [SCP]) were studied in relation to the soil properties of 11 different soils. The soil sorption coefficient at natural pH varied from 950 to 7,200, 10 to 370, and 0.4 to 35 L/kg for OTC, TYL, and SCP, respectively. The variation increased by almost two orders of magnitude for OTC and TYL when pH was artificially adjusted. Separate soil properties (pH, organic carbon content, clay content, cation-exchange capacity, aluminum oxyhydroxide content, and iron oxyhydroxide content) were not able to explain more than half the variation observed in soil sorption coefficients. This reflects the complexity of the sorbent-sorbate interactions. Partial-least-squares (PLS) models, integrating all the soil properties listed above, were able to explain as much as 78% of the variation in sorption coefficients. The PLS model was able to predict the sorption coefficient with an accuracy of a factor of six. Considering the pH-dependent speciation, species-specific PLS models were developed. These models were able to predict species-specific sorption coefficients with an accuracy of a factor of three to four. However, the species-specific sorption models did not improve the estimation of sorption coefficients of species mixtures, because these models were developed with a reduced data set at standardized aqueous concentrations. In conclusion, pragmatic approaches like PLS modeling might be suitable to estimate soil sorption for risk assessment purposes.

Adsorption↗
PubMed2001

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 1. Short-term effects on soil microbiology.

Linear alkylbenzene sulfonates (LAS) may occur in sewage sludge that is applied to agricultural soil, in which LAS can be inhibitory to biological activity. As a part of a broader risk assessment of LAS in the terrestrial environment, we tested the short-term effects of aqueous LAS on microbial parameters in a sandy agricultural soil that was incubated for up to 11 d. The assays included 10 microbial soil parameters; ethylene degradation; potential ammonium oxidation; potential dehydrogenase activity; beta-glucosidase activity; iron reduction; the populations of cellulolytic bacteria, fungi and actinomycetes; the basal soil respiration; and the phospholipid fatty acid (PLFA) content. Except for beta-glucosidase activity, basal respiration, and total PLFA content, all soil parameters were sensitive to LAS, with EC10 values in the range of less than 8 to 22 mg/kg dry weight. This probably reflected a similar mode of LAS toxicity, ascribed to cell membrane interactions, and showed that sensitivity to LAS was common for various soil microorganisms. The extracellular beta-glucosidase activity was rather insensitive to LAS (ECI10, 47 mg/kg dry wt), whereas the basal soil respiration was not inhibited even at 793 mg/kg dry weight. This was interpreted as a combined response of inhibited and stimulated compartments of the microbial community. The PLFA content, surprisingly, showed no decrease even at 488 mg/kg. In conclusion, LAS inhibited specific microbial activities, although this could not be deduced from the basal respiration or the total PLFA content. The lowest EC10 values for microbial soil parameters were slightly higher than the predicted no-effect concentrations recently derived for plants and soil fauna (approximately 5 mg/kg dry wt).

Agriculture↗
PubMed2001

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 4. The influence of salt speciation, soil type, and sewage sludge on toxicity using the collembolan Folsomia fimetaria and the earthworm Aporrectodea caliginosa as test organisms.

Sewage sludge applied to agricultural soils often contains linear alkylbenzene sulfonates (LAS) in the range of 1 to 10 g/kg dry weight, and their toxicity to relevant soil organisms should, therefore, be assessed to ensure safe use of sewage sludge as a fertilizer. Studies of LAS toxicity to soil organisms are few, and to our knowledge, factors that may influence the toxicity in the field have not been studied in detail. In this paper, we report on the influence of speciation of LAS in the test solution added to soil (soluble Na-LAS vs poorly soluble Ca-LAS or Mg-LAS), the influence of soil type, and the modifying effects of sludge amendment on the toxicity of LAS. These issues were investigated using reproduction of Collembola and growth of juvenile earthworms as test parameters. Speciation of the LAS added to test soil did not have any influence on toxicity for any of the test species. Likewise, in three different agricultural soils (sand, loam, and clay), we found almost equal toxicities. The LAS added to test soil in a sludge-water suspension was equally toxic as when it was added in an aqueous solution. However, anaerobic incubation for 7 and 14 d of the LAS-sludge suspension (with no decay of LAS) caused the toxicity to increase almost threefold in both collembolan and earthworm. The relationships between soil constituents, bioavailability, and toxicity are also discussed.

Agriculture↗
PubMed2004

[Microbial eco-characterization and its restoration in copper reclaimed wasteland in red soil area of China. II. Effects on soil microbial characteristics and community structure].

Soil microbial features in Lipu copper mining and non-mine soil were studied comparatively. The results indicated that mine soil possessed obviously different microbial features such as lower microbial biomass carbon and soil basal respiration strength, Cmic/Corg decreasing, and higher microbial ecophysiological parameters qCO2, indicating that heavy metal had a depressive impact on soil microbial eco-characteristics. Biolog data showed that mine soil microbial community structure was changed obviously, the speed and quantity of carbon consuming were increased significantly, and the kinds of carbon sources which soil microorganism used were changed, led to consume much more energies for maintaining the normal needs of its life. But the utilization efficiency was lower compared with the control. All the results showed that soil microbial eco-characteristics could be used as a sensitive, effective and liable index of mine soil environment qualities.

Bacteria↗
PubMed1994

The impact of soil lead abatement on urban children's blood lead levels: phase II results from the Boston Lead-In-Soil Demonstration Project.

The Boston Lead-In-Soil Demonstration Project was a randomized environmental intervention study of the impact of urban soil lead abatement on children's blood lead levels. Lead-contaminated soil abatement was associated with a modest reduction in children's blood lead levels in both phases of the project; however, the reduction in Phase II was somewhat greater than that in Phase I. The combined results from both phases suggest that a soil lead reduction of 2060 ppm is associated with a 2.25 to 2.70 micrograms/dl decline in blood lead levels. Low levels of soil recontamination 1 to 2 years following abatement indicate that the intervention is persistent, at least over the short-term. Furthermore, the intervention appears to benefit most children since no measurable differences in efficacy were observed for starting blood and soil lead level, race, neighborhood, gender, and many other characteristics. However, soil abatement did appear to be more beneficial to children in the higher socioeconomic classes, with low baseline ferritin levels, and who spent time away from home on a regular basis and lived in nonowner occupied housing, and with adults who had lead-related hobbies and almost always washed their hands before meals. Children who lived in apartments with consistently elevated floor dust lead loading levels derived almost no benefit from the soil abatement. It was not possible to separate the effects of the variables that had a beneficial impact on efficacy because they were closely correlated and the number of subjects was small. We recommend that further research be conducted to identify subgroups of children to whom soil lead abatement might be targeted.

Boston↗
PubMed2006

Remediation of cadmium-contaminated paddy soils by washing with chemicals: effect of soil washing on cadmium uptake by soybean.

We conducted a pot experiment to evaluate the effect of soil washing with CaCl(2) on Cd absorption by two soybean cultivars. The results were as follows: (1) Soybean growth was not significantly different in washed and unwashed soils, but the seed Cd concentration for both cultivars decreased significantly, up to 25%, in the washed soils compared with the unwashed soils. (2) In the washed soils, the Cd concentration in the soil solution indicated an obviously lower value from sowing to the flowering stage; however, the change in Cd speciation was not evident in the CaCl(2)-washed soil solution. Consequently, the effect of soil washing using CaCl(2) on Cd-contaminated paddy soils can be expected to continue after a CaCl(2)-washed paddy field is converted to an upland field.

Cadmium↗
PubMed2004

Prediction of soil organic carbon partition coefficients by soil column liquid chromatography.

To avoid the limitation of the widely used prediction methods of soil organic carbon partition coefficients (KOC) from hydrophobic parameters, e.g., the n-octanol/water partition coefficients (KOW) and the reversed phase high performance liquid chromatographic (RP-HPLC) retention factors, the soil column liquid chromatographic (SCLC) method was developed for KOC prediction. The real soils were used as the packing materials of RP-HPLC columns, and the correlations between the retention factors of organic compounds on soil columns (ksoil) and KOC measured by batch equilibrium method were studied. Good correlations were achieved between ksoil and KOC for three types of soils with different properties. All the square of the correlation coefficients (R2) of the linear regression between log ksoil and log KOC were higher than 0.89 with standard deviations of less than 0.21. In addition, the prediction of KOC from KOW and the RP-HPLC retention factors on cyanopropyl (CN) stationary phase (kCN) was comparatively evaluated for the three types of soils. The results show that the prediction of KOC from kCN and KOW is only applicable to some specific types of soils. The results obtained in the present study proved that the SCLC method is appropriate for the KOC prediction for different types of soils, however the applicability of using hydrophobic parameters to predict KOC largely depends on the properties of soil concerned.

Chromatography, High Pressure Liquid↗
PubMed2005

Biodegradation and speciation of residual SS-ethylenediaminedisuccinic acid (EDDS) in soil solution left after soil washing.

This paper aims to investigate the degradation and speciation of EDDS-complexes (SS-ethylenediaminedisuccinic acid) in soil following soil washing. The changes in soil solution metal and EDDS concentrations were investigated for three polluted soils. EDDS was degraded after a lag phase of 7-11 days with a half-life of 4.18-5.60 days. No influence of EDDS-speciation on the reaction was observed. The decrease in EDDS resulted in a corresponding decrease in solubilized metals. Changes in EDDS speciation can be related to (1) initial composition of the soil, (2) temporarily anoxic conditions in the soil slurry after soil washing, (3) exchange of EDDS complexes with Cu even in soils without elevated Cu and (4) formation of NiEDDS. Dissolved organic matter is important for metal speciation at low EDDS concentrations. Our results show that even in polluted soils EDDS is degraded from a level of several hundred micromoles to below 1 microM within 50 days.

Chelating Agents↗
PubMed2005

Toxicity of the antimicrobial oxytetracycline to soil organisms in a multi-species-soil system (MS.3) and influence of manure co-addition.

The effects of oxytetracycline (OTC) on soil organisms have been studied using a multi-species-soil system (MS.3). Oxytetracycline concentrations of 0.01 mg/kg, 1 mg/kg and 100 mg/kg soil were added to the 20 cm top arable soil layer, with and without horse/cow manure (0.15 g organic N/kg soil) co-addition. No mortality was observed for Eisenia foetida S. but significant effects on soil microbial enzymatic activities (phosphatase, dehydrogenase) were observed. The effects on soil microorganism were observed earlier but then recovered in systems with manure co-addition. More important, OTC related plant inhibition was observed in the manured but not in the non-manured systems. Oxytetracycline reached 0.19 and 1.85 mg/l in the leachate of the soil spiked with 1 and 100 mg OTC/kg, respectively and 0.05 and 1.14 mg/l for the same OTC concentrations in the manured systems. The results confirm that manure can modify both the fate and the effects of OTC and that the multi-species-soil systems can reproduce the conditions for a realistic effect estimation of veterinary medicines.

Animals↗
PubMed2003

Study of the desorption of linuron from soils to water enhanced by the addition of an anionic surfactant to soil-water system.

The influence of the addition of the anionic surfactant sodium dodecyl sulphate (SDS) to the soil-water-linuron system in the herbicide desorption from soils with different organic matter (OM) content to water have been studied. SDS was used at critical micelle concentrations (cmc) of 0.75, 1.50, 5 and 10. The adsorption-desorption isotherms of linuron in aqueous medium and in SDS solutions at concentration of 0.75 cmc fitted the Freundlich adsorption equation for all the soils studied. When the SDS concentration was 1.50 cmc only the desorption isotherms for the soils with OM content < or = 5.40% fit this equation and was not fulfilled by any of the soils when the SDS concentration was 5 or 10 cmc. All the desorption isotherms displayed hysteresis, the hysteresis coefficients of the desorption isotherms in SDS solutions always being lower than those of the desorption isotherms in water. The efficiency coefficients, defined as the relationship between the percentages of linuron desorbed in SDS solution and the percentages of linuron desorbed in water, range from 1.02 to 2.41 in the soil with the lowest OM content, and from 1.91 to 17.1 in the soil with the highest OM content. The results obtained indicate the enhancement of linuron desorption by the addition of SDS surfactant to soil-water system. The efficiency of SDS is seen as from surfactant concentrations below the cmc and varies with the surfactant concentration and with the soil OM content.

Adsorption↗
PubMed2001

Influence of soil moisture on the sequestration of organic compounds in soil.

A study was conducted as a part of continuing investigation of the effect of soil moisture on the sequestration of organic compounds aged in the soil. Here, experiments focused on the effects of moisture changes within the soil before, during, and after contaminant addition. The extractability of aged (68 d) phenanthrene was greater from soil that had been subjected to wetting and drying cycles prior to solute addition as compared to soil initially maintained at constant moisture. The recovery of phenanthrene added to moist soil was increased relative to extractability from soil that was air-dried at the time of the contaminant addition. Repeated wetting and drying of soil after the addition of atrazine or phenanthrene resulted in decreased extractability of the compounds as compared to samples maintained at constant moisture. A method for rapidly sequestering contaminants is proposed and may be useful in limiting the time required for laboratory studies involving "aged" contaminants. These data build upon the findings of earlier work from our laboratory and indicate that changes in the moisture conditions of soil can affect the availability of sequestered contaminants possibly through alterations in the structure of the natural solid.

Atrazine↗
PubMed2003

Sorption and mobility of 14C-labeled imazaquin and metolachlor in four soils as influenced by soil properties.

Aqueous batch-type sorption-desorption studies and soil column leaching studies were conducted to determine the influence of soil properties, soil and suspension pH, and ionic concentration on the retention, release, and mobility of [14C]imazaquin in Cape Fear sandy clay loam, Norfolk loamy sand, Rion sandy loam, and Webster clay loam. Sorption of [14C]metolachlor was also included as a reference standard. L-type sorption isotherms, which were well described by the Freundlich equation, were observed for both compounds on all soils. Metolachlor was sorbed to soils in amounts 2-8 times that of imazaquin, and retention of both herbicides was related to soil organic matter (OM) and humic matter (HM) contents and to herbicide concentration. Metolachlor retention was also related to soil clay content. Imazaquin sorption to one soil (Cape Fear) increased as concentration increased and as suspension pH decreased, with maximum sorption occurring in the vicinity of pK(a1) = (1.8). At pH levels below pK(a1) imazaquin sorption decreased as hydronium ions (H3O+) increased and competed for sites. NaCl was more effective than water in desorption of imazaquin at pH levels near the pK(a1). Mechanisms of bonding are postulated and discussed. The mobility of imazaquin through soil columns was in the order Rion > or = Norfolk > Cape Fear > or = Webster, whereas for metolachlor it was Rion > or = Norfolk >> Webster > or = Cape Fear. Imazaquin was from 2 to 10 times as mobile as metolachlor.

Acetamides↗