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PubMed2000

Biotic indices based on soil nematode communities for assessing soil quality in terrestrial ecosystems.

Nematode communities offer several advantages for assessing the quality of soils. Diversity and maturity indices as well as trophic structure defining parameters based on the composition of soil nematode communities have been used to detect various kinds of man-induced disturbances and monitor ecological recovery. In the present paper we examined the response of these indices in herbaceous Mediterranean ecosystems. Incipient soils, which were developed on the top of waste dumping sites were compared with agricultural soils under fallow. Grasslands and old-fields were considered as reference systems. Either diversity or maturity indices were shown to be very sensitive to changes in soil system caused by waste dumping. However, they were less useful for the categorisation of perturbation in agroecosystems. Trophic composition related parameters were more meaningful for this aim. Plant parasite index (PPI) may be a good generic indicator of recovery processes after perturbation in these annual herbaceous ecosystems.

Animals↗
PubMed2004

Biodiversity of Collembola in urban soils and the use of Folsomia candida to assess soil 'quality'.

The effects of metal contamination on natural populations of Collembola in soils from five sites in the Wolverhampton area (West Midlands, England) were examined. Analysis revealed that metal concentrations were elevated above background levels at all sites. One location in particular (Ladymoor, a former smelting site) was highly contaminated with Cd, Cu, Pb and Zn at more than 20 times background levels. Biodiversity indices (Shannon-Weiner, Simpson index, Margalef index, alpha index, species richness, Shaneven (evenness) and Berger-Parker dominance) were calculated. Of these indices, estimates of species richness and evenness were most effective at highlighting the differences between the Collembola communities. Indeed, the highest number of species were found at the most contaminated site, although the Collembola population also had a comparatively low evenness value, with just two species dominating. The number of individuals per species were allocated into geometric classes and plotted against the cumulative number of species as a percentage. At Ladymoor, there were more geometric classes, and the slope of the line was shallower than at the other four sites. This characteristic is a feature of polluted sites, where a few species are dominant and most species are rare. The Ladymoor soil also had a dominance of Isotomurus palustris, and was the only site in which Ceratophysella denticulata was found. Previous studies have shown that these two species are often found in sites subject to high metal contamination. Survival and reproduction of the "standard" test springtail, Folsomia candida (Willem), were determined in a 4 week exposure test to soils from all five sites. Mortality was significantly increased in adults and reproduction significantly lower in the Ladymoor soil in comparison to the other four sites. This study has shown that severe metal contamination can be related to the population structure of Collembola in the field, and performance of F. candida (in soils from such sites) in the laboratory.

Age Factors↗
PubMed2001

Nutrient stimulation of sulfolane biodegradation in a contaminated soil from a sour natural gas plant and in a pristine soil.

Natural gas in western Canada can contain up to 35% H2S. The Sulfinol process for sour gas treatment makes use of sulfolane and an amine to remove H2S and other sour components from natural gas. Sulfolane has leached into groundwaters at sour gas treatment plant sites, and poses a risk for off-site contamination. Sulfolane biodegradation was monitored in shake-flask cultures and air-sparged microcosms inoculated with uncontaminated topsoil or with sulfolane contaminated soil obtained near a Sulfinol process building at a sour gas treatment facility in western Canada. For both soils, supplementation with a source of fixed nitrogen stimulated sulfolane biodegradation. Topsoil cultures and microcosms were only slightly affected by the addition of phosphate. Contaminated soil microcosms and cultures were stimulated by phosphate addition, but not to the same degree as by the addition of nitrogen. For these cultures and microcosms, amendment with both fixed nitrogen and phosphate produced an additive effect. It was possible to predict the nutrient requirements of air-sparged microcosms inoculated with each soil type using shake-flask cultures. Shake-flask cultures require less time and effort and fewer materials than the more complex air-sparged soil microcosms, and will be useful for large-scale experiments to predict the nutrient supplements required for bioremediation of sulfolane-contaminated sites.

Bacteria, Aerobic↗
PubMed2001

Methane oxidation in three Alberta soils: influence of soil parameters and methane flux rates.

Current concern over the potentially negative impacts of climate change has brought attention to anthropogenic sources of methane, a primary greenhouse gas. Two such emission sources are methane leakage at heavy oil wells and sanitary landfills. At both of these sources, substantial quantities of methane could potentially be oxidised by methanotrophic microbes living in soils. Optimisation of this phenomenon may serve as an inexpensive technique for reducing methane emissions. Soil column and batch incubation experiments were performed on a landfill loam, an agricultural loam and a sedge peat to gain a better quantitative understanding of the biological and physical processes limiting CH4 oxidation in soils that undergo the freeze-thaw cycles associated with northern climates. Moisture content emerged as a critical variable that can limit a soil's CH4 oxidation potential. For example, the oxidation rate of the agricultural soil was seen to increase by an order of magnitude after increasing its moisture content from 6% to 10% of its dry weight.

Alberta↗
PubMed1976

Influences of soil acidity on Streptomyces populations inhabiting forest soils.

The Streptomyces populations inhabiting five acidic forest soils were examined. It was found that lowering the pH of a medium selective for streptomycetes (starch-casein agar) to the pH of the particular soil horizon being plated influenced both the total numbers and types of streptomycetes that were isolated from the soils examined in this study. On the acidified medium both the numbers of streptomycetes and the percentage of total bacteria on the plates represented by streptomycetes increased (as compared with the same medium with a pH of 7.2). These differences were greatest on the isolations from the most acid soils. The largest concentrations of streptomycetes were found in the surface horizon (0 to 15 cm) and the litter layer immediately over the surface mineral horizon. Acidity tolerance tests demonstrated that random samplings of isolates contained acidophilic, neutrophilic, and acidoduric strains, with the largest numbers of acidophiles being found on the acidified media from the most acid soils. There were no differences between overall utilization of selected carbohydrates among the isolates taken from either the neutral or acidic media, although a larger proportion of the acid media isolates produced acid from the carbohydrates. Evidence is presented which indicates that different types of streptomycetes were isolated on the acid media, and possible reasons for the presence of these acid-tolerant populations are discussed.

Carbohydrate Metabolism↗
PubMed2004

Competition effects for copper between soil, soil solution, and yeast in a bioassay for Folsomia candida Willem.

We investigated the accumulation of copper (Cu) by the springtail Folsomia candida Willem, if exposed to Cu-contaminated sandy soil with yeast as a food source. Commonly, the dissolved and the easily desorbed Cu fractions are assumed to be available for uptake, and as both fractions depend on pH, a pH dependency of copper uptake and accumulation is expected. In recent studies with springtails this dependency was not observed. To explain this, we show that both the adsorption of copper by yeast and by soil is indeed pH dependent; however, these dependencies differ. Addition of yeast as a food source to copper-contaminated soil leads to competition for copper by yeast and soil that suppresses the pH dependency of copper adsorption by yeast. This may cause a pH dependency not to be observed in copper accumulation by springtails if they predominantly feed on yeast in bioassays. We conclude that the addition of artificial food sources in bioassays may affect the cause-effect relationships that are investigated. A combination of (soil) chemical experimentation and modeling and ecotoxicological studies may help in identifying such bias and, therefore, with interpreting bioassays.

Adsorption↗
PubMed2004

Effects of pesticides on soil biochemical characteristics of a paddy soil.

The impact of triazophos, bensulfuron-methyl, chlobenthiazone on soil biochemical characteristics in a paddy soil under controlled moisture (flooded soil) and temperature (25 degrees C) condition was studied. The electron transport system (ETS)/dehydrogenase activity displayed a negative correlation with triazophos, bensulfuron-methyl, chlobenthiazone concentrations, and the activity decreased as the concentration of the pesticides increased. The higher doses, 5 and 10 field rates, of triazophos, bensulfuron-methyl, chlobenthiazone significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect against the control. The relative toxicity of triazophos, bensulfuron-methyl, chlobenthiazone in decreasing the ETS activity was in the order: triazophos > chlobenthiazone > bensulfuron-methyl, irrespective of the rates of application. Triazophos, bensulfuron-methyl, chlobenthiazone caused an improvement in the soil phenol content and it increased with increasing concentration of triazophos, bensulfuron-methyl, chlobenthiazone. Triazophos, bensulfuron-methyl, chlobenthiazone incorporation did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of triazophos, bensulfuron-methyl, chlobenthiazone in the order of triazophos > chlobenthiazone > bensulfuron-methyl; and the toxicity of applied amount was in the order: 10 FR (field rate) > 5 FR > 1.0 FR > 0.5 FR > control.

Agriculture↗
PubMed2005

Effect of heavy metals on soil microbial activity and diversity in a reclaimed mining wasteland of red soil area.

The microbial biomass, basal respiration and substrate utilization pattern in copper mining wasteland of red soil area, southern China, were investigated. The results indicated that soil microflora were obviously different compared with that of the non-mine soil. Microbial biomass and basal respiration were negatively affected by the elevated heavy metal levels. Two important microbial ecophysiological parameters, namely, the ratio of microbial biomass C(Cmic)/organic C(Corg) and metabolic quotient(qCO2) were closely correlated to heavy metal stress. There was a significant decrease in the Cmic/Corg ratio and an increase in the metabolic quotient with increasing metal concentration. Multivariate analysis of Biolog data for sole carbon source utilization pattern demonstrated that heavy metal pollution had a significant impact on microbial community structure and functional diversity. All the results showed that soil microbiological parameters had great potential to become the early sensitive, effective and liable indicators of the stresses or perturbations in soils of mining ecosystems.

Analysis of Variance↗
PubMed2006

[Characteristics of soil organic carbon and microbial biomass carbon in hilly red soil region].

In this paper, 535 soil samples (0 to approximately 20 cm) were taken from the woodland, orchard, upland, and paddy field in the hilly red soil region of south China, and the quantitative characteristics of soil organic carbon (SOC) and soil microbial biomass carbon (SMB-C) were studied. The results showed that SOC content was the highest (16.0 g x kg(-1)) in paddy field and the lowest (8.4 g x kg(-1)) in woodland, while SMB-C content was the highest in paddy field (830 mg x kg(-1)) and the lowest in orchard (200 mg x kg(-1)). There was a highly significant positive correlation (P < 0.01) between the contents of SOC and SMB-C in the four land-use types. It was suggested that the changes of SMB-C content could sensitively indicate the dynamics of SOC. The transition from woodland to orchard or cultivated land in hilly red soil region would not decrease the SOC content.

Carbon↗
PubMed1997

[Microbiologic/hygienic evaluation of the risk potential of bacteria from soil and water sources in combination with biotechnologic risks of soil restoration].

Biological cleanup-processes removing contaminations from soil and ground-water can be carried out "ex-situ" or "in situ". The pollutants are mineralized (totally or partly) by microorganisms. The successful application of bioremediation techniques often leads to an increase of aerobic and facultatively anaerobic bacteria in soil and/or groundwater, a fact that triggered discussions about a potential biological risk originating from these microorganisms. In this study the identification results of 10,200 microorganisms isolated from 109 ground-water- and 152 soil-samples of different sites contaminated with mineral oil or chlorinated aromatics are evaluated with respect to a possible biological risks originating from these microorganisms. According to their biological risk potential, 19.2% (1958) of the isolated organisms can be grouped into risk-groups II, that means they they are able o cause human disease but it is unlikely that they are spread to the community and there is effective prophylaxis or treatment available. The majority of isolates (81.8%) are grouped into risk group I, meaning that it is very unlikely that they cause a human disease. All these microorganisms are either adsorbed to the soil-matrix or within a closed system of a water-treatment-plant, so that the risk of infection is very unlikely for healthy individuals (regarding possible pathways of infection). The risk potential in waste-water-treatment-plants is regarded to be significantly higher than in biological soil-cleanup processes, because of the specific origin of the bacteria and the possible formation of aerosols.

Bacteria, Aerobic↗
PubMed2005

Vertical gradients of delta15N and delta18O in soil atmospheric N2O--temporal dynamics in a sandy soil.

The greenhouse gas nitrous oxide (N(2)O) can be both formed and consumed by microbial processes in the soil. As these processes fractionate strongly in favour of (14)N and (16)O, delta(15)N and delta(18)O gradients of N(2)O in the soil profile may elucidate patterns of N(2)O formation, consumption or emission to the atmosphere. We present the first in situ data of such gradients over time for a mesic typic Haplaquod seeded with potatoes (Solanum tuberosum L.). On two adjacent fields in 2002 and 2003, topsoil N(2)O fluxes were measured and the soil atmosphere was regularly sampled for N(2)O concentrations, delta(15)N and delta(18)O signatures of N(2)O at depths of 18, 48 and 90 cm during approximately 400 days. During the entire sampling period, the N(2)O concentrations were the highest and the delta(15)N signatures the lowest in the subsoil (48 or 90 cm depth) as compared with the topsoil, indicating production of N(2)O in the subsoil. For delta(15)N, differences greater than 30 per thousand between topsoil and subsoil on the same date were regularly observed. The highest N(2)O concentration of 100385 microL m(-3) at 90 cm depth on 1 July 2003, was preceded by the lowest delta(15)N value of -43.5 per thousand one week earlier. This was followed by a 150-day general decrease of N(2)O concentrations at 90 cm depth to 1723 microL m(-3) and a simultaneous enrichment of delta(15)N to +7.1 per thousand, mostly without a significant topsoil flux. There was a negative logarithmic relationship between N(2)O concentration at 90 cm depth and its delta(15)N signature. This relationship indicated a delta(15)N signature of -40 to -45 per thousand during the production of N(2)O in the subsoil, and a subsequent enrichment during the consumption of N(2)O. We conclude that the isotopic signature of the N(2)O topsoil flux is the result of various processes of consumption and production at different depths in the soil profile. It is therefore not a reliable estimator for the overall delta(15)N signature of N(2)O in the soil atmosphere, nor for indirect losses of N(2)O to the environment. Therefore, these findings will pose a further challenge to ongoing efforts to draw up a global isotopic budget for N(2)O.

Atmosphere↗
PubMed2005

Georelational analysis of soil type, soil salt content, landform, and land use in the Yellow River Delta, China.

The Yellow River Delta, one of China's three major river deltas, is becoming a major region for the development of agriculture and fisheries. Protecting the delicate ecology of newly formed aquatic systems as well as the evolution of soils, natural vegetation, and fauna on older upland environments in the delta is a priority in planning for the wise use of the delta's resources for future agricultural development. In this article, we use a Geographic Information System (GIS) to analyze relationships between land-use/ land-cover characteristics in the Dongying municipality, one of the most intensely developed areas of the delta, and spatial variations in soil salinity and landforms. This analysis reveals that soil salt content decreases from regionally high values in isolated depressions to relatively moderate values in embanked former back swamps, with the lowest values occurring in abandoned river courses. Comparing the present land use on this soil salinity-landform pattern shows that it is basically at odds with general concepts of land suitability for agricultural utilization of saline soils. Crop-based agriculture in the region is probably overdeveloped, whereas more appropriate agricultural development, like cattle and forest production, is underrepresented. Future development should focus on converting farmland in embanked former back swamps and abandoned river courses into grasslands and forests. Crop-based agriculture (up to 151,000 ha) could be planned at the low-salinity terrace uplands and flood plains. The article provides guidelines for decision-makers regarding agricultural land use and wetland protection in the Yellow River Delta.

Agriculture↗
PubMed2005

Selenium extractability from a contaminated fine soil fraction: implication on soil cleanup.

Two batches of fine soil fraction of an acidic soil were deliberately contaminated with selenite (Se(IV)) and selenate (Se(VI)), respectively, and aged for more than 220 days. Speciation analysis using continuous flow-through hydride generation atomic absorption spectrometry (HGAAS) indicated that the species were predominant in their respective aged soils. A selective sequential extraction scheme was employed to fractionate the Se retained in the soils into six fractions of varying retentions. Abilities of various chemical reagents in extracting the Se in the two soil batches were then evaluated. The reagents investigated were sodium salts such as sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), and sodium phosphate (Na3PO4), and two oxidants, namely, hydrogen peroxide (H2O2) and potassium permanganate (KMnO4). It was found that NaCl, Na2SO4, and Na2CO3 could only extract the exchangeable fraction of Se, while Na3PO4 could extract the exchangeable and strongly-bound fractions. Selenate was extracted more than Se(IV) by the salts. The kinetics of Se(IV) extraction by Na3PO4 could be best described by the Elovich model, while the Ritchie second-order model was the most appropriate to describe Se(VI) extraction. Efficiencies of the oxidants in Se(IV) extraction highly depended on their applied dosages. Both H2O2 and KMnO4 were able to extract greater than 93% of total Se, and therefore were significantly more effective than the salts in Se(IV) extraction.

Chemical Fractionation↗
PubMed2005

Adsorption behavior of herbicide butachlor on typical soils in China and humic acids from the soil samples.

Three kinds of soils in China, krasnozem, fluvo-aquic soil, and phaeozem, as well as the humic acids (HAs) isolated from them, were used to adsorb the herbicide butachlor from water. Under the experimental conditions, the adsorption amount of butachlor on soils was positively correlated with the content of soil organic matter. HAs extracted from different kinds of soils had different adsorption capacity for the tested herbicide, which was positively correlated with their content of carbonyls. The adsorption mechanism was studied using Fourier transform infrared spectroscopy and cross-polarization with magic angle spinning 13C nuclear magnetic resonance (CP-MAS 13C NMR) techniques. It was showed that the adsorption mainly took place on the C=O, phenolic and alcoholic O-H groups of HAs. It was also confirmed that the adsorption mechanism was hydrogen bonds formation between the above groups of HAs and butachlor molecules.

Acetanilides↗
PubMed2005

Seasonal variation of the radiocaesium transfer soil-to-Swiss chard (Beta vulgaris var. cicla L.) in allophanic soils from the Lake Region, Chile.

The transfer factor (TF) of radiocaesium from soil-to-Swiss chard (Beta vulgaris var. cicla L.) was studied in two different characteristic allophanic soils (umbric andosol and dystric fluvisol) of the Lake Region, an important agricultural region situated in central-south Chile. To investigate especially the time dependence and the effect of K-fertilisation on the TF, field experiments were conducted. Plots of 7.6 m2 were labelled with 100 kBq 134Cs m(-2) at Santa Rosa Experiment Station close to the city of Valdivia characterised by a temperate climate and high precipitation rates. The variation in time of the radiocaesium TF soil-to-Swiss chard was observed during two consecutive years after soil contamination by sequential harvests and radiocaesium analyses of the plants. The TFs showed no significant ageing effect, but a pronounced seasonal decrease with effective half-lives of about 140 and 160 days for the umbric andosol without and with K-fertilisation, respectively, and of 50 and 60 days for the dystric fluvisol without and with K-fertilisation, respectively. The effect of K-fertilisation on the absolute values of the TF was determined by the ratio between the median TF values obtained for corresponding dates without and with use of K-fertiliser. A ratio of TF(without K)/TF(with K) = 1.8 for the umbric andosol and TF(without K)/TF(with K) = 2.9 for the dystric fluvisol was obtained, indicating a reduction of the TF by applying 90 kg K ha(-1). The maximal values of the TF to chard predicted by the equation characterising the seasonal decrease of the TF at the beginning of the harvest periods are 0.19 for the umbric andosol and 0.11 for the dystric fluvisol, both values for soil treated with common K-fertilisation.

Beta vulgaris↗
PubMed2001

Controlling mechanisms of aluminium in soil solution--an evaluation of 180 podzolic forest soils.

To monitor the level of soil acidification in the county of Värmland in the middle west of Sweden 180 podzolic forest soils were investigated. Soil solutions from four horizons were obtained by centrifugation and the soil was sampled for a determination of the exchangeable pool by extraction. The concentrations of inorganic Al and its fraction of the total Al in solution were greater in the south of the county (up to 50%). The factors influencing the total Al and free inorganic Al3+ in the soil solutions were evaluated. Saturation indices (SI) for five different mineral phases were calculated but none implied equilibrium conditions. The relationships between pAl3+ and pH (in the pH range 4-6.2) gave slopes of about 1, which indicated that ion exchange/complexation reactions may be important for determining the Al3+ concentration in the B and C horizons. In the E horizon solutions complexation with soluble organic acids seemed to be the major factor which influenced the Al3+ activity. The influence of organic matter on Al solubility was supported by partial least square (PLS) regressions.

Aluminum↗
PubMed2003

Comparison of biodegradation of surfactants in soils and sludge-soil mixtures by use of 14C-labelled compounds and automated respirometry.

The biodegradability of dodecyl benzene sulphonate (LAS), nonylphenol-di-ethoxylate (NP2EO) and tridecyl-tetra-ethoxylate (LAE) in soil was examined by use of 14C experiments at two concentrations (10 and 400 mg/kg). Increasing the concentration of test chemical from 10 to 400 mg/kg resulted in a decrease in the relative maximum mineralization rate and an increase in the estimated lag times of a factor of approximately 3.5. In sludge-amended soil, the highest expected environmental concentration (just after sludge application) will be around 10 mg/kg for linear alkylbenzene sulphonate (LAS), while the concentration of NP2EO and linear alcohol ethoxylates (LAE) will be much lower. However, when using a respirometric method it is necessary to use a higher concentration of test substance in order to detect biodegradation. In our experiment, amendment with anaerobically digested sludge resulted in a decrease in the mineralization of LAS, NP2EO and LAE for all soils. Respirometric experiments were carried out at 400 mg/kg and could be used for estimation of biodegradation potential of LAS, NP2EO and LAE in soil and sludge-amended soil. For LAS, the results obtained from the respirometric experiments were similar to the results obtained in the 14C experiments, whereas NP2EO and LAE showed a faster degradation in the respirometric experiments.

Biodegradation, Environmental↗
PubMed2003

Investigation of organic xenobiotic transfers, partitioning and processing in air-soil-plant systems using a microcosm apparatus. Part II: comparing the fate of chlorobenzenes in grass planted soil.

A microcosm system was used to investigate and compare transfers of 14C labeled-1,2-dichlorobenzene (DCB), 1,2,4-trichlorobenzene (TCB) and hexachlorobenzene (HCB) in an air-soil-plant system using single grass tillers planted into spiked soil. This study was the second phase of a development investigation for eventual study of a range of xenobiotic pollutants. Recoveries from the system were excellent at >90%. The predominant loss pathway for 14C labeled-1,2-DCB and 1,2,4-TCB was volatilisation with 85% and 76% volatilisation of parent compound and volatile metabolites over 5 weeks respectively. Most of the added label in the hexachlorobenzene spiked system remained in soil. Mineralisation was <1% for all compounds. 14C plant burdens expressed as microg parent compound/g plant fresh weight were significant and suggest that plant uptake of chlorobenzenes from soil may be an important exposure pathway for grazing herbivores. Both shoot and root uptake of 14C was detected, with foliar uptake of volatilised compounds dominating shoot uptake, and being greatest in TCB spiked systems. The microcosm is shown as potentially an ideal system with which to investigate organic xenobiotic partitioning in air-soil-plant systems to improve understanding of the equilibria and kinetics of exchanges. However, limitations imposed by the lab based conditions must be recognized and data should be compared with field based data sets as a consequence.

Carbon Radioisotopes↗