Mobility of antimony in soil and its availability to plants

In a historical mining area residual material has been filled on land and these locations are used today as agricultural soils or house gardens. The antimony concentrations in these soils are up to 500 mg/kg. Antimony transfer into 19 vegetable and crop species was investigated. In grain and other storage organs up to 0.09 mg Sb/kg were found, whereas maximum antimony concentrations in shoots and leaves were determined to be 0.34 mg Sb/kg and 2.2 mg Sb/kg, respectively. Despite the high antimony contamination of the soils, concentrations in the investigated plants in general corresponded to concentrations only reported for uncontaminated soils. NH4NO3 extraction of some of the soils indicated that the mobile fraction of antimony present was only 0.06-0.59%. In contrast, in leaves of spinach grown under controlled conditions in soils with a high mobile antimony content an accumulation of the element could be observed: a maximum value of 399 mg Sb/kg was detected, and a correlation between the mobile fraction in the soils and antimony in leaves was found.     

Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil

Pyrolytic conversion of sewage sludge into biochar could be a sustainable management option for Mediterranean agricultural soils. The aim of this work is to evaluate the effects of biochar from sewage sludge pyrolysis on soil properties; heavy metals solubility and bioavailability in a Mediterranean agricultural soil and compared with those of raw sewage sludge. Biochar (B) was prepared by pyrolysis of selected sewage sludge (SL) at 500 °C. The pyrolysis process decreased the plant-available of Cu, Ni, Zn and Pb, the mobile forms of Cu, Ni, Zn, Cd and Pb and also the risk of leaching of Cu, Ni, Zn and Cd. A selected Mediterranean soil was amended with SL and B at two different rates in mass: 4% and 8%. The incubation experiment (200 d) was conducted in order to study carbon mineralization and trace metal solubility and bioavailability of these treatments. Both types of amendments increased soil respiration with respect to the control soil. The increase was lower in the case of B than when SL was directly added. Metals mobility was studied in soil after the incubation and it can be established that the risk of leaching of Cu, Ni and Zn were lower in the soil treated with biochar that in sewage sludge treatment. Biochar amended samples also reduced plant availability of Ni, Zn, Cd and Pb when compared to sewage sludge amended samples.     

Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil

Pyrolytic conversion of sewage sludge into biochar could be a sustainable management option for Mediterranean agricultural soils. The aim of this work is to evaluate the effects of biochar from sewage sludge pyrolysis on soil properties; heavy metals solubility and bioavailability in a Mediterranean agricultural soil and compared with those of raw sewage sludge. Biochar (B) was prepared by pyrolysis of selected sewage sludge (SL) at 500 °C. The pyrolysis process decreased the plant-available of Cu, Ni, Zn and Pb, the mobile forms of Cu, Ni, Zn, Cd and Pb and also the risk of leaching of Cu, Ni, Zn and Cd. A selected Mediterranean soil was amended with SL and B at two different rates in mass: 4% and 8%. The incubation experiment (200 d) was conducted in order to study carbon mineralization and trace metal solubility and bioavailability of these treatments. Both types of amendments increased soil respiration with respect to the control soil. The increase was lower in the case of B than when SL was directly added. Metals mobility was studied in soil after the incubation and it can be established that the risk of leaching of Cu, Ni and Zn were lower in the soil treated with biochar that in sewage sludge treatment. Biochar amended samples also reduced plant availability of Ni, Zn, Cd and Pb when compared to sewage sludge amended samples.     

毒死蜱在不同土壤腐殖酸上的吸附/解吸特征

通过平衡振荡法研究毒死蜱在不同来源土壤腐殖酸(Has)上的吸附/解吸行为.结果表明,毒死蜱在Has上的等温吸附行为用Freundlich模型描述相对更合理;它们的吸附等温线在实验范围内基本呈直线,且吸附能力很强,顺序为:紫色潮土Has＞黄壤Has＞中性紫色土Has＞酸性紫色土Has＞腐殖土Has;但毒死蜱的解吸率较小,其值均小于26.70%,有明显的滞后现象,尤其是腐殖土Has和紫色潮土Has,固定能力顺序为:紫色潮土Has＞腐殖土Has＞中性紫色土Has＞酸性紫色土Has＞黄壤Has.由于不同来源土壤中Has的组成结构差异明显,它们对毒死蜱的吸附/解吸规律表现出不同的特征.土壤Has对毒死蜱的吸附/解吸行为的影响是多种因素综合作用的结果,具体作用机理尚待进一步研究.     

Biodegradation of chlorpyrifos by either single or combined cultures of some soilborne plant pathogenic fungi

Abstract

Biodegradation of chlorpyrifos was studied in liquid culture media amended with either single or combined eight different plant pathogenic fungi isolated from the continuous cropping wheat fields. The average recovery of chlorpyrifos from the liquid media was found to be 86.1%. The detection limit of chlorpyrifos by the analytical method used was 19 ppb. Data showed that the growth of mixed fungi at concentrations up to 200 ppm of chlorpyrifos was higher than in the control treatment. Chlorpyrifos concentrations declined in the medium of combined fungi more than it did in the medium of any single fungus with increase in the incubation period. The amount of chlorpyrifos recovered was 79.8 ppm (39.9%) in the combined fungal cultures after 21 days. However, those recovered from the media of Fusarium graminearum, F. oxysporum, Rhizoctonia solani, Cladosporhim cladosporiodes, Cephalosporium sp., Trichoderma viridi, Alternaria alternata, and Cladorrhinum brunnescens, ranged from 48.0 to 74.8%. The half‐life value (T_1/2) for chlorpynfos was 15.8 day in the medium amended with mixed fungi. However, for the single cultures it ranged from 19.3 to 33.0 day.     

Effects of phosphorus fertilization on the availability and uptake of uranium and nutrients by plants grown on soil derived from uranium mining debris

Subterranean clover and barley were grown on a soil derived from uranium mining debris and fertilized with phosphate as a U immobilizing additive for in situ remediation. We investigated the beneficial effect of P fertilization in the range 0-500 mg P kg(-1) soil in terms of U extractability, plant biomass production and U uptake. Increasing P in the mining debris caused a significant decrease of the water-soluble U and NH(4)-Ac extractable U at pH 7 and 5. For both plant species, P fertilization considerably increased root and shoot dry matter up to a maximum observed for soil receiving 100 mg P kg(-1) while the soil-to-plant transfer of U was regularly decreased by increasing P content in soil. These observations show that P fertilization represents an in situ practical option to facilitate the revegetation of U-mining heaps and to reduce the risks of biota exposure to U contamination.     

Mobility and plant availability of risk elements in soil after long-term application of farmyard manure

Crop rotation long-term field experiments were established in 1955 and 1956 at three locations in the Czech Republic (?áslav, Ivanovice, and Lukavec) differing in their climatic and soil physicochemical properties. The effect of long-term application of farmyard manure and farmyard manure + NPK treatments on plant-available, easily mobilizable, potentially mobilizable, and pseudo-total contents of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) contents in soils (in 2013) as well as the uptake of these elements by winter wheat (Triticum aestivum L.) grain and straw were analyzed in the two following seasons: 2012 and 2013. The treatments resulted in increasing the soil pH level when compared to the control, but the cation exchange capacity remained unchanged. Although all fertilizers were applied for six decades, the pseudo-total concentration elements in both the soil and wheat plants stayed far below those of the Czech and European threshold limits for agricultural soils and cereals for human nutrition and feedstuff. Although the mobile pools of As, Cu, and Zn were slightly changed at the treated soils, these changes were not related to the element uptake by the wheat plants. Moreover, the effect of the location and growing season was more decisive for the differences in soil and plant element contents than for the individual treatments. Thus, the long-term application of farmyard manure did not result in any substantial change in risk element contents in both soils and winter wheat plants.     

Evaluation of metal mobility, plant availability and immobilization by chemical agents in a limed-silty soil

Metal-contaminated soils in the vicinity of industrial sites become of ever-increasing concern. Diagnostic criteria and ecological technologies for soil remediation should be calibrated for various soil conditions; actually, our knowledge of calcareous soil is poor. Silty soils near smelters at Evin (Pas de Calais, France) have been contaminated by non-ferrous metal fallout and regularly limed using foams. Therefore, the mobility, bioavailability, and potential phytotoxicity of Cd, Pb and Zn, were investigated using single soil extractions (i.e. water, 0.1 n Ca(NO(3))(2), and EDTA pH 7), and vegetation experiments, in parallel with a biological test based on (iso)-enzymes in leaves and roots, before and following soil treatment with chemical agents, i.e. Thomas basic slags (TBS), hydrous manganese oxide (HMO), steel shots (ST) and beringite. No visible toxicity symptoms developed on the above-ground parts of ryegrass, tobacco and bean plants grown in potted soil under controlled environmental conditions. Cd, Zn and Pb uptake resulted in high concentrations in the above-ground plant parts, but the enzyme capacities in leaves and roots, and the peroxidase pattern indicated that these metal concentrations were not phytotoxic for beans as test plants. The addition of chemical agents to the soil did not increase biomass production, but treatment with either HMO, ST or beringite markedly decreased the mobility of Cd, Zn and Pb. These agents were proven to be effective in mitigating the Cd uptake by plants. HMO and ST decreased either Pb or Zn uptake by ryegrass. TBS was effective in lowering Pb uptake by the same species. Beringite decreased Cd uptake by beans. If fallout could be restricted, the metal content of food crops in this area should be lowered by soil treatment. However, the differences in Cd uptake between plant species were not suppressed, regardless of the type of agents applied to the soil.     

Persistence of chlorpyrifos in a mineral and an organic soil

Chlorpyrifos (Lorsban emulsifiable concentrate) was applied at 3.4 kg AI/ha and incorporated into sand and muck soil contained in small field plots. Soil samples were taken at intervals over 2 yr. Radishes and carrots, seeded yearly, served as indicator crops for absorption of insecticide residues. Samples were extracted and analyzed, by gas-liquid chromatography, for chlorpyrifos, oxychlorpyrifos, and 3,5,6-trichloro-2-pyridinol. Chlorpyrifos residues declined rapidly, with 50% of the initial application remaining after 2 and 8 wk in sand and muck, respectively, and 4 and 9% after 1 yr. Pyridinol residues increased to 13 and 39% of the initial chlorpyrifos application in sand and muck after 1 and 8 wk, respectively, and declined thereafter. Oxychlorpyrifos was detected in the 2 soils at very low levels only in immediate posttreatment samples. In the first year of the study low levels (less than 0.1 ppm) of chlorpyrifos and the pyridinol were detected in radishes and carrots.     

Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.     

Dissipation of chlorpyrifos in two soil environments of semi-arid India

The dissipation of chlorpyrifos (20 EC) at environment-friendly doses in the sandy loam and loamy sand soils of two semi-arid fields and the presence of pesticide residues in the harvested groundnut seeds, were monitored. The movement of chlorpyrifos through soil and its binding in the loamy sand soil was studied using 14C chlorpyrifos. Chlorpyrifos was moderately stable in both loamy sand and sandy loam soils, with half-life of 12.3 and 16.4 days, respectively. With 20 EC treatments the dissipation was slower for standing crop than seed treatment, indicative of the high degradation rates in the bioactive rhizosphere. In soil, 3,5,6-trichloro-2-pyridinol (TCP) was the principal breakdown product. Presence of 3,5,6-trichloro-2-methoxypyridine (TMP), the secondary metabolite, detected in the rhizospheric samples during this study, has not been reported earlier in field soils. The rapid dissipation of the insecticide from the soil post-application might have resulted from low sorption due to the alkalinity of the soil and its low organic matter content, fast topsoil dissipation possibly by volatilization and photochemical degradation, aided by the low water solubility, limited vertical mobility due to confinement of residues to the upper 15 cm soil layers and microbial mineralization and nucleophilic hydrolysis. Contrary to the reports of relatively greater mobility of its metabolites in temperate soils, TMP and TCP remained confined to the top 15 cm soil. The formation of bound residues (half-life 13.4 days) in the loamy sand soil was little and not "irreversible." A decline in bound residues could be correlated to decreasing TCP concentration. Higher pod yields were obtained from pesticide treated soils in comparison to controls. Post-harvest no pesticide residues were detected in the soils and groundnut seeds.     

双功能吸附剂的制备及其对水中毒死蜱的降解特性

对具有催化功能的负载Fe（Ⅲ）的活性炭进行了表征,与母体活性炭相比,其比表面积以及微孔体积均有所下降,酸性官能团的量有所增加;考察了普通浸渍法和超声浸渍法制备的双功能活性炭对毒死蜱的吸附和降解性能,结果表明,双功能活性炭对毒死蜱的吸附量有所降低,但对毒死蜱的降解能力增强,超声浸渍法所制备的活性炭对毒死蜱的降解能力要优于普通浸渍法所制备的活性炭。     

The effect of thallium on the growth of Lemna minor and plant tissue concentrations in relation to both exposure and toxicity

The effect of thallium on frond production and the rates of increase in surface area and fresh weight in Lemna minor were examined in terms of concentrations of the element in the growth medium and in the plant. The toxicity indices, EC(50) and threshold concentration, indicate that curtailment of frond expansion occurs at a lower thallium exposure than inhibition of frond multiplication. Production of smaller fronds, rather than chlorosis, was the most notable initial response to thallium stress and, below the threshold of toxicity, enhanced multiplication rates were recorded. Subsequent recovery in thallium-free medium was significant in the region of EC(50) exposures and below, but very little recovery occurred at higher exposures. Lemna minor has a remarkable capacity to accumulate thallium, and accumulation factors of 88 x 10(3) at low exposures, and 6 x 10(3) at high exposures, were recorded, which would suggest some form of active uptake.     

Chemical assays of availability to earthworms of polycyclic aromatic hydrocarbons in soil

The bioavailable concentration of an organic pollutant is less than the concentration determined by vigorous extraction of soil. Because bioavailability varies with the particular compound, soil, and aging time, an assay for bioavailability is needed. Three methods were tested: extraction with a 25% aqueous solution of tetrahydrofuran (THF), 95% ethanol, and C18 membranes. Evaluations were conducted with a mixture of four polycyclic aromatic hydrocarbons (PAHs) added to five dissimilar soils and with pyrene as sole PAH added to six soils, and the availability of aged and freshly added compounds was determined. Assimilation by earthworms (Eisenia fetida) was used to assess bioavailability. For extraction with THF and earthworm uptake, the correlation coefficients of determination (R2) for anthracene, chrysene, pyrene, and benzo(a)pyrene added as a mixture exceeded 0.85. The R2 values for assays with the C18 membrane were 0.77 or higher. The values for pyrene added alone were 0.710 and 0.823, respectively. R2 values for assays with ethanol often exceeded 0.87, but lower values were sometimes obtained. We suggest that such solvent or solid-phase extractions may be useful in assessing PAH bioavailability.     

耐盐性毒死蜱降解混合菌的构建及其降解特性

为明确蜡状芽孢杆菌(Bacillus cereus)混合菌株对毒死蜱的降解效果,采用正交实验的方法构建混合菌。以混合菌对毒死蜱的降解率和菌株的生长量为依据,利用单一因素实验考察了不同因素对混合菌降解毒死蜱的影响。结果表明:构建的混合菌中三菌株的体积比为1∶1∶3。在含80 mg/L毒死蜱的反应体系中,最适接菌量为8%(V/V),最适pH为7。在实验浓度下,混合菌对毒死蜱的降解符合一级动力学方程。混合菌对盐分有较高的耐受度,当反应液中氯化钠浓度在20～100 g/L之间时,混合菌对80 mg/L毒死蜱的降解率最高达61%。     

Degradation of chlorpyrifos and its hydrolysis product, 3,5,6‐trichloro‐2‐pyridinol,in soil

Abstract

The degradation of ¹⁴C‐chlorpyrifos and its hydrolysis product, 3,5,6‐trichloro‐2‐pyridinol (TCP), was investigated in soil in laboratory experiments. Between 12 and 57% of the applied chlorpyrifos persisted in a variety of agricultural soils after a 4‐week incubation. Concentrations of TCP present in these soils ranged from 1 to 34% of the applied dose. Two patterns of persistence were observed. In some soils, significant quantities of TCP and soil‐bound residues were produced, but little ¹⁴CO₂. In other soils, neither TCP nor soil‐bound residues accumulated, but large quantities of ¹⁴CO₂ were evolved. Direct treatment of fresh samples of each of these soils with ¹⁴C‐TCP resulted in rapid mineralization of TCP to ¹⁴CO₂ only in those soils in which TCP had not accumulated after chlorpyrifos treatment. The rapid mineralization of TCP in these soils was microbially mediated, but populations of soil microorganisms capable of using TCP as a sole carbon‐energy source were not detected.     

Metal accumulation in soil arthropods in relation to micro-nutrients

Nine species of soil arthropod collected at two sites of different pollution levels were compared for concentrations of seven different elements (Ca, Cd, Cu, Fe, Mn, Pb, Zn) and correlations between the different elements were calculated. Significant effects of site on element concentrations of the animals were found for cadmium, iron, manganese and zinc, whereas calcium, copper and lead concentrations showed no significant difference between the sites. Significant differences between the species were found for all metal. The pattern of accumulation was comparable for some of the metals. Correlations were found between calcium, iron, manganese and lead concentrations and between zinc and cadmium concentrations of the species. No significant correlations were found for copper. The study showed that species can not be easily categorised as accumulators or non-accumulators; the pattern depends on the metal.     

Effects of thiobencarb in combinations with molinate and chlorpyrifos on selected soil microbial processes

The impact of pesticides, namely thiobencarb (TBC), molinate (MOL) and chlorpyrifos (CPF), on soil microbial processes was studied in two Australian soils. Substrate induced respiration (SIR), substrate induced nitrification (SIN) and phosphatases and chitinase enzymatic activities were assessed during a 30-day microcosm study. The pesticides were applied to soils at recommended rates either alone, or as binary mixtures with TBC. Soil samples were sampled at 5, 15 and 30 days after pesticide treatments. Substrate induced respiration was only transiently affected by pesticides in both soils. In contrast, the process of indigenous nitrification was affected by the presence of pesticides in both soils, especially when the pesticides were applied as binary mixtures. Substrate induced nitrification increased with pesticides in the Griffith soil (except with MOL+TBC after 5 days) whereas SIN values were non-significantly different to the control on the Coleambally soil. The binary mixtures of pesticides with TBC resulted in a decrease in SIN in both soils, but the effects disappeared within 30 days. The enzymatic activities were not consistently affected by pesticides, and varied with the soil and pesticides studied. This study showed that, when applied at recommended application rates, TBC, MOL, and CPF (individually or as binary mixtures), had little or only transitory effects on the functional endpoints studied. However, further investigations are needed to assess the effect on microbial densities and community structure despite the low disturbance to the functions noted in this work.     

Effect of some preparates on soil microflora on the basis of soil bioassay

Abstract

Trials for control of soil‐borne plant pathogen fungi with biological and chemical fungicide preparates have been carried out in our Biological Control Laboratory for more than 10 years. During all these experiments soil bioassay was always carried out in order to observe the soil microflora. Here we mention one trial which confirms the general opinion that chemical treatments significantly change the soil microflora. The tested biological fungicide did not cause such changes.     

农药毒死蜱的生态风险及其微生物修复技术研究进展

毒死蜱是替代甲胺磷和对硫磷等高毒农药的高效有机磷杀虫剂,在世界范围得到广泛使用.但是,环境毒理学研究发现,毒死蜱对生态环境具有潜在的危险性,甚至被认为具有干扰内分泌的功能,许多国家对毒死蜱在农产品中的残留量有严格的规定.因此,深入研究毒死蜱的生态风险问题是当务之急.对国内外关于毒死蜱的残留活性、生态毒理、降解机制以及生物修复等方面的研究进行了综述,以期对毒死蜱的合理管理和使用提供科学依据.