Factors affecting soil residues of dieldrin, endosulfan, gamma-HCH, dimethoate, and pyrolan

The factors which determine the fate of pesticide residues in soils are discussed in relation to published research and to our own work with a range of temperate and tropical soils. Pesticide characteristics, soil type, climatic conditions, methods of application, and crop husbandry ought to be considered before pesticide application, since they determine the rate of pesticide disappearance from the soil. Degradation products of organophosphorus and carbamate compounds in the soil may be as toxic as the parent materials and can exhibit considerable persistence. A toxic metabolite of dimethoate was detected 2 years after a field had last been treated with the pesticide. Under laboratory conditions, metabolites of pyrolan were detected in soils and leachates more than 300 days after the parent compound was applied. Chlorinated hydrocarbons such as γ-HCH and endosulfan slowly degrade in soils to less or nontoxic products. The multiple use of pesticides in agriculture may cause long-term adverse effects on nontarget organisms. To minimize environmental hazards, pesticides should be used in the smallest quantities which would be effective against the target organisms, using seed treatment, soil treatment or controlled placement of pesticides. Spraying should be used only when alternative methods have proved unsuccessful. The review reveals a dearth of quantitative data on the relative importance of the different routes of pesticide loss from soils.     

Soil Dissipation and Leaching Behavior of a Neonicotinoid Insecticide Thiamethoxam

Persistence and leaching of thiamethoxam in soil were studied under laboratory conditions. The persistence studies carried out at two fortification levels and under three moisture regimes revealed that thiamethoxam persisted beyond 90 days in all the treatments with half-life varying from 46.3 to 301.0 days. Under dry conditions, the dissipation was faster at 10 mg kg(-1) level as compared to 1 mg kg(-1), whereas the reverse trend was observed under field capacity moisture and submerged conditions. The effect of moisture was prominent and longer persistence was observed under dry conditions (t1/2 200.7-301.0 days) followed by field capacity moisture (t1/2 91.2-94.1 days) and submerged condition (t1/2 46.3-75.3 days). The leaching experiment carried out under laboratory conditions showed that on leaching the soil column with water equivalent to 65 cm rainfall, 66-79% of the applied thiamethoxam was recovered from leachate and no residues were detected in soil. Results showed that thiamethoxam has a potential to leach down under heavy rainfall conditions.     

Multipesticide Residue Assessment of Agricultural Soil and Water in Major Farming Areas in Benguet, Philippines

This study investigated the concentration and presence of pesticide residues in water and soil in Benguet, which is a vegetable producing region in the Philippines. Seventy-eight samples and 49 water samples were taken from different farms covering three municipalities in the province of Benguet and were analyzed using gas chromatography. Meteorological conditions of temperature and humidity were also taken. Thirty-four of the soil samples were found to be positive for pesticide residues. The most significant pesticide type with the highest concentration was technical endosulfan, with a mean concentration of 0.025 mg/kg, followed by endosulfan sulfate (0.015 mg/kg), chlorpyrifos (0.01 mg/kg), profenofos (0.003 mg/kg), chlorothanil, cypermethrin, and cylohathrin (all at 0.002 mg/kg). One water sample was found to be positive for pesticide residue of chlorpyrifos in municipality 2 at a concentration of 0.07 mg/L. The data also showed that endosulfan, which is restricted in the Philippines and banned in other countries, was found to be the most prevalent pesticide used (17.7%) and the second highest in concentration (0.015 mg/kg) in soil samples. The study also showed a relationship between temperature and pesticide concentration in soil. In conclusion, pesticide residues were found in soil and water samples in the farming areas of Benguet.     

Interactions in the fate of chemicals in terrestrial systems

In outdoor lysimeters, [14C]atrazine (0.9 mg/kg dry soil), [14C]atrazine combined with the detergent n-dodecylbenzenesulfonate (0.9 and 10 mg/kg, respectively), [14C]n-dodecylbenzene-sulfonate (10 mg/kg), and [14C]n-dodecylbenzenesulfonate combined with atrazine (10 and 0.9 mg/kg, respectively) were applied to soils. Maize was grown in the first year and barley in the second year. n-Dodecylbenzenesulfonate increased the mobility of atrazine and its metabolites in soil as well as its leaching into water, its uptake by maize plants, and its volatilization from soil. Atrazine had a negative influence on mineralization, mobility in soil, leaching, plant uptake by both species, and binding rates of radiocarbon derived from the surfactant in soil and plants. The results were confirmed by short-term laboratory tests. Whereas the effects of the detergent on the fate of atrazine and its conversion products were apparent only in the first growing season, those of atrazine on the fate of detergent-derived residues could also be observed in the second year due to the persistence of atrazine in soil.     

Fate of veterinary antibiotics in a macroporous tile drained clay soil

The environment may be exposed to veterinary medicines administered to livestock through the application of organic fertilizers to land. For other groups of substances that are applied to agricultural land (e.g., pesticides), preferential flow in underdrained clay soils has been identified as an extremely important mechanism by which pollution of surface waters can occur. This study, therefore, was performed to investigate the fate of three antibiotics from the sulfonamide, tetracycline, and macrolide groups. Pig slurry was applied to a field in arable production in two consecutive years and the fate of the compounds was monitored in the soil and drainage water. Both sulfachloropyridazine and oxytetracycline were detected in soil at concentrations up to 365 and 1691 microg/kg, respectively. Subsequently, peak concentrations of the two substances in drainflow were 613.2 and 36.1 microg/L, although mass losses to the receiving water were less than 0.5%. In contrast, tylosin was not detected at all. These findings could be explained by the persistence and sorption characteristics of the antibiotics, while preferential flow via desiccation cracks and worm channels to the tile drains was found to be the most important route for translocation of the chemicals. Thus, when the soil was disced prior to slurry application, losses were reduced significantly. It is evident that processes governing pesticide fate also apply to veterinary antibiotics.     

Dissipation and Residue of Cyprodinil in Strawberry and Soil

The dissipation of cyprodinil under field and greenhouse condition in China was investigated. The pesticide cyprodinil dissipation differed under different cultivate conditions, the half lives were 14.5 and 12.5 days in strawberry and soil, respectively, under the field condition, 5.5 and 6.5 days, respectively, under greenhouse. The results showed that the dissipation rate under greenhouse condition was much faster than under field condition either in strawberry or soil. The terminal residues in strawberries were below the EU maximum residue level (5 mg/kg) after 7 days of application. This study will give a suggestion for the reasonable use of cyprodinil under different cultivate conditions and can also provide reference to set MRL value in strawberry in China.     

Degradation and persistence of cotton pesticides in sandy loam soils from Punjab, Pakistan

The present study evaluated the influence of temperature, moisture, and microbial activity on the degradation and persistence of commonly used cotton pesticides, i.e., carbosulfan, carbofuran, lambda-cyhalothrin, endosulfan, and monocrotophos, with the help of laboratory incubation and lysimeter studies on sandy loam soil (Typic Ustocurepts) in Pakistan. Drainage from the lysimeters was sampled on days 49, 52, 59, 73, 100, 113, and 119 against the pesticide application on days 37, 63, 82, 108, and 137 after the sowing of cotton. Carbofuran, monocrotophos, and nitrate were detected in the drainage samples, with an average value, respectively, of 2.34, 2.6 microg/L, and 15.6 mg/L for no-tillage and 2.16, 2.3 microg/L, and 13.4 mg/L for tillage. In the laboratory, pesticide disappearance kinetics were measured with sterile and nonsterile soils from 0 to 10 cm in depth at 15, 25, and 35 degrees C and 50% and 90% field water capacities. Monocrotophos and carbosulfan dissipation followed first-order kinetics while others followed second-order kinetics. The results of incubation studies showed that temperature and moisture contents significantly reduced the t(1/2) (half-life) values of pesticides in sterile and nonsterile soil, but the effect of microbial activity was nearly significant that might be due to less organic carbon (0.3%). The presence of carbofuran and monocrotophos in the soil profile (0-10, 10-30, 30-60, 60-90, 90-150 cm) and the higher concentrations of endosulfan and lambda-cyhalothrin in the top layer (0-10 cm) showed the persistence of the pesticides. The detection of endosulfan and lambda-cyhalothrin in the 10-30 cm soil layer might be due to preferential flow. The data generated from this study could be helpful for risk assessment studies of pesticides and for validating pesticide transport models for sandy loam soils in cotton-growing areas of Pakistan.     

Persistence and movement of phorate at high concentrations in soil

The entrance of a large number of chemicals into the agricultural market has caused concern to both cultivators and scientists because of their effectiveness at the target site, possibility of underground water contamination, and other undesirable effects such as phytotoxicity and effects on nontarget species. The persistence and movement of phorate--a systemic granular insecticide--were studied at high concentrations (4 and 8 kg a.i./ha) in field soil in two seasons, i.e., winter and summer. Periodic sampling for total phorate residues (TPR) at various vertical depths showed that it leached more efficiently at the higher dose (i.e., 8 kg a.i./ha) in both seasons. The horizontal mobility was also higher at this dose. Irrespective of the treatments, TPR leaching was significantly greater in winter with the higher dose, whereas its movement in the horizontal plane was comparatively greater in summer with this dose. The TPR concentration peaks remained stationary at 7.5 cm depth at all the redistribution times until the pesticide was nearly dissipated under both treatments and in both seasons. TPR persistence was higher at the higher dose. Its persistence was comparatively greater in winter than in summer. The present findings show that there seems to be no threat of underground water contamination by this pesticide even at a rate as high as 8 kg a.i./ha.     

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 2. Effects on soil microbiology as influenced by sewage sludge and incubation time

The anionic surfactant linear alkylbenzene sulfonate (LAS) may inhibit soil microorganisms and may occur in agricultural soil through the application of sewage sludge. For five microbial parameters (microbial biomass C and the potentials of iron reduction, ammonium oxidation, dehydrogenase activity, and arylsulfatase activity), we compared the effects of aqueous LAS and LAS-spiked sewage sludge added to existing levels of 0, 3, 8, 22, 22, 62, 174, and 488 mg/kg soil (dry wt) in a Danish sandy agricultural soil that was incubated for 5 d to eight weeks. Arylsulfatase activity (measured after four weeks of incubation) was rather insensitive to LAS, with an EC 10 of 222 and more than 488 mg/kg in soil samples treated with aqueous LAS and LAS-spiked sewage sludge, respectively. For the other microbial parameters, the short-term effects (approximately one to two weeks) of aqueous LAS were characterized by an EC10 in the range of 3 to 39 mg/kg. Application of LAS via sewage sludge generally reduced the short-term effects for the microbial parameters, and the EC10 for LAS in sludge-amended soil after approximately one to two weeks of incubation ranged from less than 8 to 102 mg/kg. Recovery potential was seen for most microbial parameters as a result of prolonged incubation, both under conditions of LAS persistence (anaerobic conditions, the iron-reduction test) and LAS depletion (aerobic incubations, all other assays). In conclusion, the short-term inhibitory effects of LAS on soil microbiology were decreased in the presence of sewage sludge and by a prolonged (two to eight weeks) laboratory incubation period.     

Hygienic significance of surface-active substances in the conditions of soil contamination with chemical substances

Urgent problems of the interaction of surface-active substances (SAS) with other ingredients under the conditions of chemical soil pollution are discussed, in particular, under the conditions of irrigation of agricultural fields with treated municipal sewage containing detergents. Before the beginning of the irrigation season the content of anion SAS in the arable layer of the soil is 2.02-2.66 mg/kg. In the middle of the vegetation period the quantity of detergents is increased 3-4 times fold. The authors suppose, that SAS may influence translocation of heavy metals from soil into plants. However, this question should be studied more carefully in the conditions of field experience with various SAS concentrations in soil.     

Persistence and movement of fipronil termiticide with under-slab and trenching treatments

To have an effective barrier against invading termites around building structures and to assess the potential risks to the urban environment and human beings, we need to understand the fate of termiticides applied in urban soil. The movement and degradation of a new termiticide, fipronil, were investigated in Australian soils following standard termiticide treatment methods (surface application under slab and trenching treatments along walls). Surface application studies in three field sites showed slow dissipation and little movement for fipronil in all three soils under the simulated slab during a three-year period. The greatest mass of the chemical residues remained in the quartzite sand layer (thickness, 5 cm), and only small amounts of these were found to have migrated into the soil layers (depth, 0-15 cm) underneath the quartzite sand layer. Of the three metabolites (desulfinyl, sulfide, and sulfone) found in the soils, the sulfone derivative had the highest concentration. Persistence of fipronil was affected by application rate. The time for 50% loss of the total toxic components (fipronil plus its metabolites) in the quartzite sand layer (thickness, 5 cm) ranged from 200 to 326 d for the low rate (0.15 g active ingredient/m2) and from 633 to 674 d for the high application rate (3 g active ingredient/m2). One-year trenching studies at two sites in Adelaide (Roseworthy Farm [RF] and Terretfield [TF]; South Australia, Australia) showed that vertical movement and dissipation of fipronil occurred in the soils. The average concentration of fipronil in the trenches (depth, 0-30 cm) decreased from 33.7 to 14.9 mg/kg in the loam soil at the RF site and from 39.4 to 14.6 mg/kg in the clay soil at the TF site over the year. With time under the natural weather condition, fipronil and its derivatives were found in the deeper soil sections without treatment (depth, 20-30 cm). However, laboratory studies using repacked soil columns showed low mobility in the loam soil from the RF site and a variably charged clay soil from Malanda (Queensland, Australia) under intermittent wetting and drying conditions.     

Direct and Indirect Exogenous Contamination by Pesticides of Rice-Farming Soils in a Mediterranean Wetland

It is known that the sources of soil contamination can be endogenous or exogenous and that exogenous contamination may be direct or indirect. In this work, an environmental pesticide fate study was conducted in soil profiles collected from 23 rice field sites in an important Mediterranean wetland (Albufera Natural Park, Valencia, Spain) from April 1996 to November 1997. Temporal and spatial distribution of 44 pesticide residues in an alluvial Mediterranean soil (gleyic-calcaric Fluvisol, Fluvaquent) were monitored. During this period, the levels of pesticide residues in different soil horizons (Ap1 0–12 cm, Ap2 12–30 cm, ApCg 30–50 cm, C1gr 50–76 cm, and C2r 76–100 cm) were investigated. In addition, information was collected on agricultural pesticide application practices and soil characteristics. Distribution throughout the soil profile showed that pesticide concentrations were always higher in the topsoil (Ap1 horizon), in the autumn season, and in the border with citrus-vegetable orchard soils (calcaric Fluvisol, Xerofluvent). Chlorpyrifos (organophosphorus), endosulfan (organochlorine), and pyridaphenthion (organophosphorus) insecticides were, respectively, the most detected of all the pesticides investigated. These results were associated with processes, such as nonleaching, transport by movement into surface waters, retention, volatilization, and chemical and biological degradation in the topsoil, as well as with direct and indirect exogenous contamination sources. Received: 29 January 2002/Accepted: 24 July 2002     

Assessment of a 2,4,6-trinitrotoluene-contaminated site using Aporrectodea rosea and Eisenia andrei in mesocosms

Polynitro-organic compounds such as 2,4,6-trinitrotoluene (TNT) can be released into the environment from production and processing facilities and military firing ranges as well as through field use and disposal practices. Based on laboratory toxicity data, TNT has lethal (at >/=260 mg TNT/kg dry soil) and sublethal effects (at >/=59 mg TNT/kg dry soil) to the earthworm. However, field studies are needed to relate exposure of organisms to explosives in mixed-contaminated soil under field conditions and to define effects-based ecotoxicologic benchmarks for TNT-contaminated soil. In the present study, the lethal and sublethal effects of a 10-day in situ exposure at a TNT-contaminated field site using mesh-bag mesocosms were assessed. In addition to the survival end point, the biomarkers of earthworm exposure and effect-including tissue residues, lysosomal neutral red retention time (NRRT), and total immune activity (TIA)-were measured. Concentrations of TNT in soil mesocosms ranged from 25 to 17,063 mg/kg. Experiments indicated a trend toward decreasing survival of caged Aporrectodea rosea and Eisenia andrei as the concentration of TNT and total nitroaromatic compounds increased. E. andrei tolerated higher concentrations of TNT (up to 4050 mg/kg dry soil) in mesocosms than did indigenous earthworms, who survived only at 相似文献   

Aging reduces the bioavailability of even a weakly sorbed pesticide (carbaryl) in soil

We investigated bioavailability and biodegradation of carbaryl (1-naphthyl methylcarbamate) in a soil with a long history of pesticide contamination from a storage facility located at Mamoon Kanjan, Pakistan. Carbaryl is weakly sorbed and generally considered to be easily degradable in soil. Extraction studies revealed that 49% of the total carbaryl in soil (88.0 mg kg(-1)) was not water-extractable and also not bioavailable, as demonstrated by inoculation of the contaminated soil with a carbaryl-degrading, mixed bacterial culture. Inoculation of the contaminated soil with the carbaryl-degrading culture showed that the bacteria were capable of degrading only the available (i.e., water-extractable) fraction of the pesticide. When the soil was pulverized in a ball mill to enhance the release of residue, an additional 19% of the carbaryl became bioavailable. A significant proportion of residue (approximately 33%) remained unavailable. The long (>12 years) contact time between the pesticide and soil (i.e., aging), allowing possible sequestration into soil nanopores and the organic matter matrices, is suggested to have rendered the pesticide unavailable for microbial degradation. High concentration (88.0 mg kg(-1)) in soil facilitated its persistence and sequestration. Results from the present study demonstrate that even a weakly sorbed and easily degradable pesticide, carbaryl, is effectively sequestrated in soil with time, rendering it partly inaccessible to microorganisms and affecting the bioavailability of the compound.     

Assessment of a 2,4,6-Trinitrotoluene–Contaminated Site Using <Emphasis Type="Italic">Aporrectodea rosea</Emphasis> and <Emphasis Type="Italic">Eisenia andrei</Emphasis> in Mesocosms

Polynitro-organic compounds such as 2,4,6-trinitrotoluene (TNT) can be released into the environment from production and processing facilities and military firing ranges as well as through field use and disposal practices. Based on laboratory toxicity data, TNT has lethal (at 260 mg TNT/kg dry soil) and sublethal effects (at 59 mg TNT/kg dry soil) to the earthworm. However, field studies are needed to relate exposure of organisms to explosives in mixed-contaminated soil under field conditions and to define effects-based ecotoxicologic benchmarks for TNT-contaminated soil. In the present study, the lethal and sublethal effects of a 10-day in situ exposure at a TNT-contaminated field site using mesh-bag mesocosms were assessed. In addition to the survival end point, the biomarkers of earthworm exposure and effect—including tissue residues, lysosomal neutral red retention time (NRRT), and total immune activity (TIA)–were measured. Concentrations of TNT in soil mesocosms ranged from 25 to 17,063 mg/kg. Experiments indicated a trend toward decreasing survival of caged Aporrectodea rosea and Eisenia andrei as the concentration of TNT and total nitroaromatic compounds increased. E. andrei tolerated higher concentrations of TNT (up to 4050 mg/kg dry soil) in mesocosms than did indigenous earthworms, who survived only at 1146 mg TNT/kg. Earthworms E. andrei and A. rose survived in 67% and 75% of TNT-contaminated mesocosms, respectively, compared with references groups. NRRT was significantly decreased in surviving earthworms from the contaminated areas compared with those from the reference site. TIA was not affected by field exposure to TNT. Earthworm tissue concentrations of TNT metabolites 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene were not correlated with TNT soil concentrations. In addition, higher tissue concentrations of TNT metabolites were observed at concentrations ranging from 116 to 130 mg TNT/kg soil. The results showed that earthworm exposure in TNT-contaminated soil produced both lethal and sublethal effects in the field. The results of study indicated that mesocosm experiments would be useful to assess the toxicity of a site and to characterize the overall effects of contaminants. However, mesocosm experiments present special considerations (e.g., abiotic factors, exposure period) when used at heterogenous sites, and data must be interpreted with caution.     

A new tool for laboratory studies on volatilization: extension of applicability of the photovolatility chamber

Volatilization from soil and plant surfaces after application is an important source of pesticide residues to the atmosphere. The laboratory photovolatility chamber allows the simultaneous measurement of volatilization and photodegradation of 14C-labeled pesticides under controlled climatic conditions. Both continuous air sampling, which quantifies volatile organic compounds and 14CO2 separately, and the detection of surface-located residues allow for a mass balance of radioactivity. The setup of the photovolatility chamber was optimized, and additional sensors were installed to characterize the influence of soil moisture, soil temperature, and evaporation on volatilization. The modified flow profile in the glass dome of the chamber arising from the use of a high-performance metal bellows pump was measured. Diminished air velocity near the soil surface and a wind velocity of 0.2 m/s in 3 cm height allowed the requirements of the German guideline on assessing pesticide volatilization for registration purposes to be fulfilled. Determination of soil moisture profiles of the upper soil layer illustrated that defined water content in the soil up to a depth of 4 cm could be achieved by water saturation of air. Cumulative volatilization of [phenyl-UL-14C]parathion-methyl ranged from 2.4% under dry conditions to 32.9% under moist conditions and revealed the clear dependence of volatilization on the water content in the top layer.     

Response of biomarkers in amphibian larvae to in situ exposures in a fruit-producing region in North Patagonia, Argentina

The authors evaluated biomarker responses in caged larvae of the amphibian Rhinella arenarum in water channels during fruit production season and compared them with those elicited by a transient exposure to azinphos methyl (AzM) (0.02-2?mg/L; 4?h), the main pesticide applied in the Alto Valle region, Patagonia, Argentina, taking into account the maximum environmental concentration detected in superficial water (22.5?μg/L). The traditional biomarkers of organophosphate exposure, acetylcholinesterase (AChE) and carboxylesterase, were inhibited in tadpoles after one week of exposure in channels potentially receiving pesticide drift, whereas the antioxidant glutathione (GSH) and the detoxifying activity of GSH S-transferase (GST) were induced. In a two-week monitoring study, AChE activity was induced in larvae exposed at the agricultural site, and carboxylesterase showed an inhibition followed by return to control values, suggesting an exposure-recovery episode. Antioxidant glutathione levels were first depleted and then surpassed control levels, whereas GST activity was continuously induced. These responses were mimicked in the laboratory by 2?mg/L AzM-pulse exposure, which notably exceeds the expected environmental concentrations. The results draw attention to the complexity of responses after pesticide exposure, strongly depending on exposure time-concentration and recovery periods, among other possible factors, and support the necessity of the integrated use of biomarkers to assess exposure episodes in agricultural areas. Environ. Toxicol. Chem. 2012; 31: 2311-2317. ? 2012 SETAC.     

Comparative assessment of soil contamination by lead and heavy metals in riparian and agricultural areas (southern Québec, Canada)

Soils contaminated with hydrocarbons (C(10)-C(50)), PAHS, lead and other heavy metals were recently found in the banks of two major rivers in southern Québec. Alluvial soils are contaminated over a distance of 100 kilometers. Eight sampling sites, including some located in agriculture areas (farm woodlots) have been selected to compare air pollution (aerosol fallout and rainout) and river pollution values. The concentrations detected in soil profiles for As, Cd and Pb vary between 3.01 to 37.88 mg kg(-1) (As), 0.11 to 0.81 mg kg(-1) (Cd) 12.32 to 149.13 mg kg(-1) (Pb). These metallic elements are considered highly toxic and can harm wildlife and human health at high levels. The maximum concentration of Pb (149.13 mg kg(-1)) in soils of the riparian zone is twelve times higher than the average Pb concentration found in a natural state evaluated at 15.3 mg kg(-1) (SD 17.5). Pb concentrations in soils of agricultural areas (woodland control sites) range between 12 and 22 mg kg(-1), and given that these values are recorded in surrounding cultivated land, the issue of the quality of agricultural products (crops and forage) to feed livestock or destined for human consumption must be further addressed in detail.     

Integrated ecological risk assessment of pesticides in tropical ecosystems: a case study with carbofuran in Brazil

The aim of the present study is to contribute an ecologically relevant assessment of the ecotoxicological effects of pesticide applications in agricultural areas in the tropics, using an integrated approach with information gathered from soil and aquatic compartments. Carbofuran, an insecticide/nematicide used widely on sugarcane crops, was selected as a model substance. To evaluate the toxic effects of pesticide spraying for soil biota, as well as the potential indirect effects on aquatic biota resulting from surface runoff and/or leaching, field and laboratory (using a cost-effective simulator of pesticide applications) trials were performed. Standard ecotoxicological tests were performed with soil (Eisenia andrei, Folsomia candida, and Enchytraeus crypticus) and aquatic (Ceriodaphnia silvestrii) organisms, using serial dilutions of soil, eluate, leachate, and runoff samples. Among soil organisms, sensitivity was found to be E. crypticus < E. andrei < F. candida. Among the aqueous extracts, mortality of C. silvestrii was extreme in runoff samples, whereas eluates were by far the least toxic samples. A generally higher toxicity was found in the bioassays performed with samples from the field trial, indicating the need for improvements in the laboratory simulator. However, the tool developed proved to be valuable in evaluating the toxic effects of pesticide spraying in soils and the potential risks for aquatic compartments.     

国内水环境中有机农药残留的文献分析

目的 综述国内水环境中农药残留研究现状,为深入研究农药残留提供参考和借鉴。方法 基于中国知网和PubMed,检索在2008年8月1日至2018年8月1日发表的篇名含农药和水或湖、河的文献,共检索英文文献581篇,中文文献121篇,剔除国外水体、检测方法、生态风险研究、底泥中农药研究得英文文献35篇、中文文献25篇,对所选文献中农药残留污染状况、时空分布及人体健康危害风险进行归纳。结果 水环境中农药残留以有机氯类和有机磷类为主,有机氯类对人体健康危害风险最大,污染主要来自历史使用;有机磷类残留浓度最高,污染来自新近使用;农药使用种类、喷药方式、河流分布、气温、降雨、工农业情况、光照、土壤性质等是水中农药含量的主要影响因素;水中农药研究主要集中在大江、大河及大城市周边河流,对农业区饮用水研究不足。结论 应加强农村饮用水中农药残留调查及影响因素研究。