农药与土壤腐殖物质的结合残留及其环境意义

农药或其代谢产物进入土壤环境后，可通过多种途径与土壤无机和有机组分形成结合残留物。越来越多的证据表明，在农药土壤环境行为的研究中，应重视其结合残留问题。文章阐述了农药在土壤中的主要结合残留机理，结合残留物在土壤腐殖物质各组分中的分布状况及其环境意义，并对该领域的深入研究提出建议。     

The influence of solid matrices on arsenic toxicity to Corophium orientale

In marine ecosystems, benthic organisms are really important because they are the first step in the transfer of contaminants from environment to biota. To this end, this study focused on biological assays with the amphipod Corophium orientale exposed to two different molecules of arsenic: arsenate (As^V), the most abundant form in sediments, and dimethyl-arsinate (DMA), expected to be moderately toxic as an intermediate in the process of detoxification. The toxicity of arsenic compounds was measured after exposure to three different matrices: water, spiked natural sediment and inert spiked quartz sand. LC₅₀ values were calculated for each exposure, and the results confirmed the highest toxicity of As^V, in addition to underlining the importance of matrix of exposure. Water exposure was the matrix which presented the highest toxicity for inorganic arsenic (As^V LC₅₀=3.51 mg L^?1 vs DMA LC₅₀=54.65 mg L^?1), spiked natural sediment demonstrated its capability to chelate arsenate toxicity (As^V LC₅₀=34.27 mg kg^?1 vs. DMA LC₅₀=52.19 mg kg^?1) and spiked quartz sand presented intermediate values for As^V (LC₅₀=25.26 mg kg^?1), whereas for DMA a lower toxicity was registered (LC₅₀=872.35 mg kg^?1). This study can provide some useful data linked with chemical speciation of arsenic and exposure matrix, for improving the correct management of contaminated sediment.     

Bewertungsmaßstäbe zur Beurteilung von Schadstoffbelastungen in Böden anhand der Bioverfügbarkeit

Until now, assessment of contaminated sites is based on variable protection goals, whereby total contents and in part mobile contents are considered. Due to interactions of pollutants in soil and bound residues, total contents do not reflect the actual risk. In contrast an investigation based on availability/bioavailability of contaminants would enable a harmonization of the protection-goal-based evaluation and a closer-to-reality risk assessment for the individual location.     

污染黑土中重金属的形态分布与生物活性研究

通过对污染和清洁黑土的耕层、非耕层分层采样分析,比较了Cd,Pb,Cu和Zn等在同一土壤耕层和非耕层以及不同采样点土壤中的形态分布和生物活性.结果表明,无污染黑土中这些重金属的形态分布一般为:残渣态>有机结合态>铁锰结合态>碳酸盐结合态>可交换态,外源污染则使可交换态重金属的含量增加.以生物有效性系数和迁移系数进行重金属生物活性评价,其在黑土中生物活性大小的顺序为:Cd>Cu>Zn>Pb.污染愈严重的土壤,重金属的生物活性和自身的淋溶能力相对较强,在非耕层中也表现出较高的生物活性.综合重金属在土壤中的含量和生物活性,发现2个污染点的黑土中Cd和Pb对当地农业生产和地下水安全已构成潜在的威胁.     

Medium ‐ pressure ‐ liquid ‐ extraction (MPLE) of selected polychlorinated biphenyls from soil (MPLE II) 1

The extraction of PCBs from spiked soils using the Medium‐Pressure Liquid‐Extraction method showed good recovery rates. Comparison of MPLE and Soxhlet extraction of naturally contaminated soil showed similar results. However, too large quantities of solvents have to be used in MPLE procedure and the elution profile makes it unlikely, that the aspired separation from PAHs would be sufficient.     

Principles and application of an in vivo swine assay for the determination of arsenic bioavailability in contaminated matrices

The assessment of arsenic (As) bioavailability from contaminated matrices is a crucial parameter for reducing the uncertainty when estimating exposure for human health risk assessment. In vivo assessment of As utilising swine is considered an appropriate model for human health risk assessment applications as swine are remarkably similar to humans in terms of physiology and As metabolism. While limited in vivo As bioavailability data is available in the literature, few details have been provided regarding technical considerations for performing in vivo assays. This paper describes, with examples, surgical, experimental design and analytical issues associated with performing chronic and acute in vivo swine assays to determine As bioavailability in contaminated soil and food.     

Spatial health risk assessment and hierarchical risk management for mercury in soils from a typical contaminated site,China

Due to rapid urbanization and the implementation of ecological civilization construction in China, many industrial factories have been closed or relocated. Therefore, numbers of contaminated sites were generated with contaminated soils which may pose a risk to receptors living nearby. This study presented a spatial health risk assessment and hierarchical risk management policy making for mercury (Hg) in soils from a typical contaminated site in the Hunan Province, central China. Compared with the second class value (0.3 mg/kg) of the Chinese Environmental Quality Standard for Soils, the mean concentrations of Hg in the three soil depths exceeded the second class value. The non-carcinogenic risk of Hg probably posed adverse health effects in 41, 30 and 36 % of the surface soil, the moderate soil and subsoil, respectively, under a sensitive land scenario. The non-carcinogenic risk temporarily posed no adverse health effects in most areas under an insensitive land scenario except for the area around sampling site S29. Spatially, the central, southwest and northeast parts of the contaminated land under a sensitive land scenario should be regarded as the priority regions. For non-carcinogenic effects, the exposure pathways that resulted in the higher levels of exposure risk were ingestion and inhalation of vapors, followed by dermal contact and inhalation of particles. A risk-based integrated risk management policy including the hierarchical risk control values for different soil depths and the calculated remediation earthwork was proposed with consideration of the cost-benefit effect for the related decision-makers.     

Toxizitätsdaten aus einer ökotoxikologischen Testbatterie

The influence of industrial chemicals in the environment is strongly determined by the condition of the soil. Considering the complex interrelationships of soil condition and the specific parameters of the material as influential to bioavailability and decompositional reactions, it is necessary to reproduce various situations via a selected battery of ecotoxicological tests. The use of such batteries has already proved to be suitable for the examination of sediments. In order to make statements about the dangerous potential of chemicals in the soil, samples of natural soil were exposed to industrial chemicals (surfactants, mineral oil hydrocarbons, an antibiotic and a pesticide), and examined regularly in test batteries over a period of four weeks. This microcosm works as a degradation test of environmental relevance, monitoring the effects and reactions of industrial chemicals in natural soil. All test results collected over this period of time come to a very complex and multi-dimensional compilation of data which needs to be considered in full before an assessment is possible. The main goal in analysing the data is to extract the maximum possible information from the matrix. Aside from the graphic presentation, mathematic graphs of the data will be introduced. This method aims to provide a structural and logical relationship to the data, in order to build up a classification system and an order of precedence, which should make it possible to estimate potential risk.     

Biodegradation of Hexachlorocyclohexane by two species of Bacillus isolated from contaminated soil

Biodegradation of α, β, γ and δ hexachlorocyclohexane (HCH) isomers was studied in broth medium and soil microcosm by Bacillus circulans and Bacillus brevis isolated from contaminated soil. Degradation of α and γ isomers by both the bacterial isolates was higher than thermodynamically stable β and δ isomers. However, B. circulans was found more effective than B. brevis for β and δ isomers. Maximum rate of degradation was recorded at 150 mg/L followed by 100 and 50 mg/L. Soil microcosm study revealed maximum degradation of HCH isomers in the treatment containing natural soil, pesticide and bacterial inocula than the treatment having sterilised soil, pesticide and bacterial isolates. Chloride release was positively co-related with HCH degradation in broth medium as well as in soil microcosm, suggesting that B. circulans and B. brevis hold promising potential by having efficient enzyme(s) required for dechlorination of HCH from contaminated sites.     

Relative bioaccessibility of Pb-based paint in soil

The threat posed by lead (Pb) in soil for pediatric populations continues to be a public health issue. In long-established residential areas, a principal source of Pb in soil is likely to be old Pb-based paint originating from building surfaces. The health hazard posed by Pb from paint in soil will likely depend on quantity of paint incorporated, its Pb-mineral composition, whether the Pb is locked in some other material and the paint residence time in the soil (degree of aging). Here the relative bioavailability (RBA) of Pb in different types of Pb-bearing paint has been assessed. Tests were performed with individual paints, with paints mixed with a low-Pb soil, and with paints mixed with soil and the biogenic phosphate apatite II. Thirteen Pb-bearing paint samples were ground and passed through 250- and 100-µm screens. Samples nominally <100 µm from all the paints were analyzed, and six of the paints for which there was sufficient material in the 100- to 250-µm-size range were also tested. RBA extraction of Pb employed a simulated gastric fluid (SGF) of HCl and glycine adjusted to a pH of 1.5 in which samples were agitated (in an end-over-end rotator) for 2 h. Original paints were examined by SEM/EDX, and by XRD, residues collected after RBA extraction were examined by SEM/EDX. The concentration of Pb in the extraction fluid was measured by AAS. The quantity of Pb mobilized in each test batch was approximately an order of magnitude less in the paint–soil mix compared to the corresponding paint-only sample. The difference in the amount of Pb extracted from the paint–soil mix compared to the paint–soil–phosphate mix was minimal. However, in the post-RBA residues of the paint–soil mix, a PbCl precipitate was observed, and in the extraction residues of the paint–soil–apatite II mixes PbClP phases were recorded. Precipitation of these secondary phases obviously modified the amount of Pb in the extraction fluid, and this may need to be considered, i.e., under-reporting of extractable Pb, when this form of in vitro extraction is used to determine the RBA of Pb in environmental media.     

应用脂肪酸甲酯淋洗去除土壤中多环芳烃

针对煤气厂土壤等高浓度多环芳烃污染土壤修复困难的现实,采用易生物降解的新型淋洗剂脂肪酸甲酯淋洗修复高浓度多环芳烃污染的土壤,同时进行了以甲醇、植物油(大豆油)作为淋洗剂的淋洗实验,比较不同淋洗剂的淋洗效果.结果证明脂肪酸甲酯对人工模拟污染土壤中蒽、荧蒽、芘、苯并(a)芘的去除率可以达到80%—95%,对煤气厂土壤中多环芳烃的去除效果也非常明显,总多环芳烃的去除率达到41%.脂肪酸甲酯的淋洗效果要优于其它两种淋洗剂.     

Tissue distribution of antimony (Sb) in piglets orally given graded levels of Sb (V)

The potential risks from oral intake of soil antimony (Sb) depends mainly on the amount of metal ingested and its bioavailability. Relative bioavailability may be determined by comparing Sb present in soil to a reference compound, taking into account accumulation in different target tissues or excretion. However, due to the lack of scientific knowledge concerning the fate of Sb in the organism, there is a need to study the absorption and distribution of Sb in order to select target tissues for assessment of bioavailability of Sb in soils. Thus, 45 piglets were exposed to a soluble pentavalent antimony salt (KSb(OH)₆), for 15 days at concentrations ranging from 0–1600 µg Sb/kg body weight (BW) per day. Following the exposure period, blood, plasma, liver, spleen, kidneys, hair, bone, bile and urine were obtained to measure Sb concentrations by ICP-MS. Results showed that tissue Sb levels were dose-related. Higher Sb concentrations were found in urine, kidneys, hair, bone and liver. Sb(V) was not detectable in blood and plasma. In the case of highly contaminated soil with soluble forms of Sb in concentrations ranging from 200–1600 µg Sb/kg BW, kidneys, liver and spleen are the most reliable compartments to determine Sb bioavailability from soil. However, for the soils with lower levels of contamination and a low Sb bioaccessibility, urine may serve as a relevant compartment.     

In-Vitro Determination of Arsenic Bioavailability in Contaminated Soil and Mineral Beneficiation Waste from Ron Phibun, Southern Thailand: A Basis for Improved Human Risk Assessment

The post-ingestion bioavailability of arsenic (As) in alluvial soil and mineral beneficiation waste from Ron Phibun, Nakhon Si Thammarat Province, Thailand has been investigated using a physiologically-based extraction test (PBET). The method utilises synthetic leaching fluids closely analogous to those of the human stomach and small intestine, upon which the leaching duration and ambient temperature of the experimental procedure are also directly based. Replicate analyses of Ron Phibun alluvium samples holding 1406 and 2123 g As g-1 respectively indicated an average stomach absorption of 11.2% (of total soil As). Gross absorption increased to 18.9% following translocation through a simulated small-intenstine regime. Higher gross absorption (35.7%) was recorded during PBET analysis of a flotation waste sample holding c. 2% total As. Within- and between-site variations of As bioavailability can principally be ascribed to mineralogical factors, notably the relative abundances of sulphide, arsenide, arsenate and oxide hosts within the soil/flotation waste matrix. The PBET provides a potentially valuable mechanism for refining risk assessments of sites subject to natural or anthropogenic As contamination. Through the substitution of total soil As values with input data which relate specifically to bioavailable As, risk calculations derived using established models such as the US-EPA package Risk Assistant may prove more realistic, thus facilitating improved cost-benefit analysis of site remediation options. Assessment of the relative human risks associated with potable water consumption and contaminated soil ingestion at Ron Phibun has signified that the latter could constitute a more significant As exposure pathway than recognised previously. Further evaluation of the precise soil ingestion levels of inhabitants residing on the As-rich alluvium which covers much of the district is, therefore, warranted.     

污染场地中有机氯农药对土壤原生动物群的影响

有机氯农药污染土壤对生态环境具有潜在的风险。采集某废弃农药厂污染场地的土壤样品,测定了土壤的理化性质,以及典型有机氯农药滴滴涕(DDTs)和六六六(HCHs)的残留浓度,并对土壤中原生动物的组成和数量进行了分析。结果显示,农药厂区域的土壤中原生动物的组成结构为:鞭毛虫和肉足虫为优势类群,纤毛虫为稀有类群。土壤理化性质与原生动物数量的相关性分析表明,总氮含量与鞭毛虫、纤毛虫数量和原生动物总数量呈显著正相关,总磷含量与肉足虫数量呈显著正相关。同时,农药厂区域土壤中的原生动物数量较对照区显著减少,污染场地中长期残留的有机氯农药对原生动物有明显抑制作用。     

Effect of red mud addition on the fractionation and bio-accessibility of Pb,Zn and As in combined contaminated soil

Using soil incubation experiments, the effect of red mud addition on the fractionation and bioaccessibility of Pb, Zn and As in combined contaminated soil was studied. The results showed that red mud addition could significantly decrease the concentration of HOAc-extractable Pb and Zn in soil. Compared with the control, 5% red mud addition could significantly reduce the concentrations of HOAc-extractable Pb and Zn in soil after 1, 2 and 3 months of incubation [62.5, 65.3 and 73.5% decrease (Pb), 56.7, 65.8 and 67.4% decrease (Zn)]. Whereas adding red mud could remarkably increase the concentrations of specific absorbed As and residual As in soil. The result of a simple bioavailability extraction test (SBET) indicated that all treatments with red mud addition markedly reduced the concentration of bioaccessible Zn but increased the concentration of bioaccessible As in soil, while having little effect on the concentration of bioaccessible Pb in soil. After 3 months incubation, all treatments including 1, 2 and 5% red mud addition reduced the concentration of bioaccessible Zn by 53.1–56.7% compared with the control, but increased the concentration of bioaccessible As by 1.81–6.25 times. The results suggested that red mud is an additive with potential for the remediation soil contaminated soil by combinations of heavy metals, although it should be added based on the different heavy metals in the soil. Combined use of red mud and hyperaccumulators to remediate heavy metal contaminated soil needs further study.     

Degradation characteristics of metribuzin in soils within the Nzoia River Drainage Basin,Kenya

Metribuzin, a triazinone herbicide, is heavily used within the expansive Nzoia River Drainage Basin in Kenya for the optimization of sugarcane yields. For field experiments, soils were spiked with metribuzin and amended with filter mud compost and Tithonia diversifolia leaves. Soils with history of metribuzin application (48 months) were also spiked with metribuzin but not amended with the organic materials. Degradation of metribuzin for the three variants was followed for a period of 102 days. Repeated exposure of metribuzin to soil and addition of filter mud compost to soil enhances the degradation of metribuzin with half dissipation times of 31 and 25 days. In soil amended with Tithonia diversfolia leaves, the half dissipation time was 32 days while in the control (unamended non history soil), it was 36 days. Laboratory studies showed that soil sterilization slowed the degradation of metribuzin, with a half dissipation time of 154 days. This confirmed that metribuzin was biochemically degraded in soil by an adapted community of microbes.     

Bestimmung von Mineralölkohlenwasserstoffen im Boden

The infra-red (IR) and the gas Chromatographic (GC) methods for the determination of mineral oil hydrocarbons in soils were examined in collaborative trials with regard to their accuracy and reproducibility. Natural, homogenized soils and soils spiked with mineral oil were used as standards. The soil matrix was composed relatively simply. The repeatability and reproducibility values obtained were about 5 % und 23 %, respectively. In contrast, the GC method revealed a considerably higher error range, especially by using the split/splitless technique. The degradation of mineral oil hydrocarbons in soils under different temperatures was investigated by IR throughout one year. The degradation rate at room temperature was about 25 %; at lower temperatures no degradation was detected. Thus, the spiked soils may be used as calibration standards for the mineral oil analysis.     

不同来源重金属污染的土壤对水稻的影响

采用人工污染土壤、尾矿砂、污泥等不同载体的污染源来模拟土壤污染 ,研究其对水稻生长、吸收养分和吸收重金属的影响。结果表明 ,不同污染载体对水稻生长的影响不同 ,其影响的大小顺序为人工污染土壤 >尾矿砂 >污泥 >尾矿砂 +污泥。不同污染载体对水稻吸收重金属的影响亦不同 ,以纯化学试剂的形式添加到土壤中的重金属最易被提取出来 ,植物从中吸收的Cu、Zn、Pb、Cd最多 ,而从以污泥为污染载体的土壤中吸收的Zn、Pb、Cd最少。研究表明 ,用添加纯化学试剂的方法来模拟污染土壤对生态与环境的影响是可行的 ,确定土壤负载容量是安全的 ,因为在实验条件下它对供试植物的影响最明显     

Soil particle-size composition and coastal erosion and accretion study in Soc Trang mangrove forests

Coastal erosion results in loss of land, which impacts the economy, coastal residents and settlement plans, especially in the context of rising sea levels caused by climate change. Studying soil particle-size fractions in mangrove forests will help provide a better understanding of the relationship between soil proportions and coastal processes as well as the role of mangrove forests to support coastal planning and management. Soil samples were collected at 26 sampling plots at depths of 10 cm and 40 cm in the Cu Lao Dung (CLD), Long Phu (LP) and Vinh Chau (VC) mangrove forests in Viet Nam’s Soc Trang Province. The soil proportions based on six different particle-sizes (<0.074 mm, 0.074–0.1 mm, 0.1–0.25 mm, 0.25–0.5 mm, 0.5–1.0 mm, and >1.0 mm) were measured using a dry sieving method. Analysis showed that soil particle-sizes ranging between 0.074 and 0.5 mm made up 75–95 % of the soil sample weight at both depths. The high standard deviation values of soil proportions of each given particle-size among sampling plots indicated the soil proportions by particle-size varied widely across the sampling plots. Cluster analysis found similar pattern of soil particle-size proportions for samples collected in CLD and VC, and different pattern of soil particle-size proportions in samples collected at LP, which is more impacted by the Mekong River flow and has a thin mangrove forest belt.?Non-metric dimension scaling (NMDS) analysis showed that sampling plots across the landward sites of the three mangrove forest areas were distributed in the nearby locations (Stress?=?0.11). This indicated that soil proportions of particle-sizes of samples collected from areas of the natural forest composed of different species were more similar. Such similarities were not found, however, in samples collected from middle and seaward plots dominated by single-species plantations.     

Heavy metals and soil microbes

Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g^?1 Cd and As; 1000 mg g^?1 Co, Cu, Cr, Ni and 10,000 mg g^?1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED₅₀) and lethal concentration (LC₅₀) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.