Modeling the fate of paddy field pesticide in surface water and environmental risk assessment

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水溶性农药流失的影响因素及污染防治

根据实际室和田间试验结果，分析了水溶性农药稻田流失的影响因素，提出了对水稻生长前期的农药渗滤量、降雨径流量和排水流失量的估算。结果表明，仅渗滤与排水两项流失，占农药用量的１７．２８％～５９．３１％，调查表明，环境水体已受杀虫单的污染，最后提出了防治水溶性农药稻田流失的节水灌溉，控制排水等措施。     

枯水期贵阳市饮用水源农药污染特征及健康风险

为确定贵阳市饮用水源地中农药污染特征及潜在风险,以贵阳市"两湖一库"(红枫湖、百花湖和阿哈水库)为研究对象,在枯水期设置15个取样断面,采用气相色谱/质普联用技术(GC/MS),同时检测9种有机农药残留物含量。结果表明,水体中均存在六六六类持久有机氯污染物,百花湖、阿哈水库检出率高于红枫湖,但红枫湖检出的农药种类较百花湖和阿哈水库多。利用US EPA健康风险评价模型对检出农药进行评价,结果显示贵阳市城市饮用水源地中农药污染对人体健康的风险处于较低水平,在4.96×10-11~1.22×10-5/a范围内,为可接受风险。     

DMPP对稻田田面水氮素转化及流失潜能的影响

采用杭嘉湖地区典型的小粉土和青紫泥土壤,进行水稻盆栽试验,研究新型硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)对稻田田面水氮素转化及径流流失潜能的影响.结果表明,小粉土和青紫泥土壤稻田应用添加DMPP抑制剂的尿素,与常规尿素处理相比,田面水中铵态氮的浓度增加24.8%和16.7%,硝态氮浓度降低47.7%和70.9%,亚硝态氮浓度降低90.6%和88.9%,总无机氮浓度下降13.5%与23.1%,能显著减轻农田氮素流失对水环境存在的污染;DMPP可使田面水的电导率下降,降低盐基离子随农田排水或暴雨径流所导致的流失风险,有助于保护河流水体等地表水环境.     

Predicting herbicides concentrations in paddy water and runoff to the river basin

This study was conducted to investigate the dissipation pattern and runoff of herbicides to the river basin from the paddy fields. Pesticide paddy field model(PADDY) was applied to predict herbicide concentration in paddy fields. A field study was conducted in a paddy farm of Higashi Hiroshima City, Hiroshima Prefecture, Japan in the year of 2003 paddy season. The herbicides were mefenacet, thiobencarb, and bensulfuron methyl. The sample water was analyzed by using gas chromatography and HPLC after solid phase extraction. Predicted dissipation rate of thiobencarb in paddy water was higher( DT50=4.36) than that measured, with a lower k value(-0.069). Two weeks after application no thiobencarb was detected in the drainage channel and down stream. In the down stream, thiobencarb was detected until 3d after application, with a range of 0.02% to 0.08% of applied herbicide. The predicted dissipation rate(k) and half-life (DT50) of mefenacet was not significantly different from that of measured. In the drainage channel, upstream and downstream mefenacet was found during the whole study period. In downstream, the maximum concentration of mefenacet was present 0.6l % of applied in the paddy field on 3DAH. The dissipation rate(k) of BSM varied from -0.0860 to -0.1059 to with half-life(DT50) 3.5 and 2.84 d. In upstream water, no BSM was detected except trace amounts(0.01μg/L) at 3d after application. However, in the drainag echannel 8%, 6% and 1.58% of applied BSM was present at 0, 1 and 3 d after application respectively. In the down stream, the highest concentration was 1.06%, shortly after application.     

北京官厅水库中农药类内分泌干扰物分布和来源

研究了北京官厅水库中农药类内分泌干扰物污染水平、分布特点和来源.结果表明,官厅水库及其支流水体受到农药类内分泌干扰物轻度污染.从农药在官厅水库中的分布推断,官厅水库以及各支流周边地区及农田排水渠是水库中农药的重要来源.底泥中农药通过底泥孔隙向表面水扩散,是表面水农药的1个污染源.由于水库周边较多的农业活动,可能导致水中农药浓度提高.为了减少污染和水生生物对内分泌干扰物的暴露,需要进行定期监测,减少农药的使用和农事操作.     

Pollution of surface waters with pesticides in Germany: modeling non-point source inputs

Pesticide pollution of surface waters represents a considerable hazard for the aquatic environment. However, the mean amount of pesticides reaching the water resources varies considerably between regions and depends highly upon application rates, chemical characteristics of pesticides and natural conditions during application. In this study a model was developed which estimates loss of 42 active ingredients applied to 11 field crops, vineyards and orchards along each non-point source path of entry (subsurface drains, runoff and spray drift). A spatially and temporally differentiated data set of application rates and periods was compiled for each active ingredient and target culture to enable the modeling of pesticide transport. The model results are provided in digital raster format (100 m×100 m) within a geographic information system (GIS). The calculated pesticide loads in surface waters were compared with measured loads from different catchments in Germany. Both data sets agreed as to the order of magnitude, nevertheless due to the scale of the study the estimated loads cannot be interpreted as absolute values and only differences between active ingredients, regions and application periods should be assessed.     

我国东南地区饮用水源地多种农药的赋存特征及健康风险评估

为阐明我国东南地区典型饮用水源地农药类微污染物的污染特征及生态风险,检测评估了某省7个水库的苯并咪唑类、酰胺类、三唑类和有机磷类等19类共55种常用农药的检出频率、检出浓度以及每种农药对于绿藻、水蚤和鱼类这3种不同营养级生物的风险商.在分析的55种农药中,多菌灵和乙草胺的检出频率为100%,12种农药的检出频率在80%以上.多菌灵的检出浓度最高(77.7 ng·L^-1),其次是乙草胺(51.6 ng·L^-1).风险评估结果显示,大部分农药在目标区域都处于低风险状态.对于3种生物来说,乙草胺是绿藻的风险主导型农药,而多菌灵是鱼类和水蚤的风险主导型农药.     

六叉河小流域不同景观结构中径流磷形态差异分析

选取巢湖六叉河小流域,研究了流域内不同类型景观降雨产流过程中径流磷素的形态差异.结果表明,旱地径流中总磷、溶解性总磷、颗粒态总磷、总活性磷、颗粒态活性磷的浓度最高,水稻田次之,河道中最低.颗粒态磷是旱地和水稻田磷索输出的主要形态,颗粒态活性磷占总活性磷的80%以上;而河道径流中各种磷形态浓度值均较低,总磷浓度均值在0.4mg·L-1以下,磷素输出以溶解态磷为主.磷素由旱地经过水稻田向河道传输过程中,颗粒物浓度显著下降,河流中颗粒态磷浓度降低至50%左右,活性组分浓度显著降低.由水塘、沟渠等组成的多水塘系统不仅降低了磷素输出的总量,而且对活性磷有较强的削减作用,在非点源流域控制及水源地水质保护方面有重要意义.     

Entry and toxicity of organic pesticides and copper in vineyard streams: Erosion rills jeopardise the efficiency of riparian buffer strips

The present study was performed to characterise in-stream pesticide exposure within the Palatinate vineyard region in south-west Germany, evaluate the influence of buffer strip widths and identify mitigation measures for the relevant entry pathways. In-stream water and sediment samples that were taken at nine sampling sites of different buffer widths following intense rainfall, and edge-of-field runoff that were sampled in erosion rills were analysed regarding 28 active ingredients of pesticides including copper. In-stream samples contained a mix of 8 ± 4 pesticide compounds, resulting in total pesticide concentrations of 1.4-8.9 μg l⁻¹ for water and 16-670 μg kg⁻¹ dw for sediment. Following an exceptional rainfall event with a previous 34-day drought period, pesticide concentrations reached 7.0-83.4 μg l⁻¹. Fungicides were the most important pesticides found and were significantly correlated with the pesticide application frequency and rate. The calculated toxicity values per sample (TU_max) indicated that both organic pesticides and copper concentrations likely cause ecotoxicological effects in the field. The buffer strip width was of little importance for pesticide in-stream concentrations because pesticide entry occurred mainly via the field path network and erosion rills. Pesticide in-stream concentrations were significantly and positively correlated with the concentrations detected in erosion rills (R² = 0.56). As possible risk mitigation measures, we suggest the implementation of grassed field paths and vegetated ditches or wetlands.     

我国区域性水体农药污染现状研究分析

以4大流域为基础,较为全面地概述了我国区域性农药污染情况,并对其污染原因进行了分析。结果表明:长江流域有机磷农药、氨基甲酸酯类农药以及部分拟除虫菊酯类农药的的残留量很高;珠江流域农药污染情况较轻,检出量均低于我国地表水环境质量标准;黄淮海流域和松辽流域主要检出农药为酰胺类和三嗪类农药,但具体检出物质存在差异。研究分析表明各流域农药污染与该区域的农作物种类有重要关系。     

Temporal trends in organophosphorus pesticides use and concentrations in river water in Japan, and risk assessment

We reviewed organophosphorus pesticide use in Japan between 1982 and 2016 using data from the National Institute of Environmental Studies. Organophosphorus pesticide concentrations in river water throughout Japan were taken from the literature, and risk assessments were performed for some organophosphorus pesticides based on risk quotients and hazard quotients. Assessments were performed for 20 common pesticides, including insecticides, fungicides, and herbicides. The amounts used decreased in the order: insecticides?>?herbicides?>?fungicides. Organophosphorus insecticide and fungicide use have decreased over the last four decades, but organophosphorus herbicide use has increased. During this period, annual organophosphorus pesticide use was the highest for chlorpyrifos (105,263?tons/year) and the lowest for glyphosate-sodium (8?tons/year). The ecotoxicological risk assessment indicated that diazinon and fenitrothion posed strong risks to the Japanese aquatic environment, and chlorpyrifos and malathion have moderate risks. None of the pesticides that were assessed posed significant risks to humans. Continued use of organophosphorus pesticides in Japan may cause strong risks to aquatic environments. These risks should be reassessed periodically.     

多径流出口水稻田非点源污染试验研究及验证

为验证一种水稻田非点源污染原位观测方法的准确性和适应性,以北京市上庄镇某试验水稻田为例,应用原位观测方法分别在水稻田进水口附近（4#观测点）和出水口附近（2#观测点）安装水位计观测稻田水深,利用同步观测的降雨数据以及田内5个采样点定期采集的水质数据,进行非点源污染试验研究,探究基于同一块水稻田不同位置的水深观测数据是否对该方法的应用产生影响.结果表明:①晒田期间,由于4#观测点处于相对低洼的位置,其水深数据显示4 d的无水期,与实际晒田时间相符,而2#观测点水深数据显示10 d无水.②基于2#、4#观测点水深数据得到总蒸散发和渗漏损失、总径流量以及灌溉量的相对偏差分别为1.3%、1.0%、1.8%;应用原位观测方法估算出该水稻田的灌溉量在2 620~2 710 m3之间.③基于2#、4#观测点水深得到的TN、NH₄+-N、NO₃--N、TP、COD_Cr输出系数的相对偏差在0.8%~8.0%之间.研究显示:水位计安装位置对原位观测方法应用的影响不大,且主要体现在晒田期的水深观测,建议将水位计安装在稻田相对低洼处,以确保能够完整地监测水稻生长季的水深变化;应用该方法能准确识别水稻田的径流量和灌溉量,对具有多个径流出口的水稻田非点源污染试验具有较好的准确性和适应性.      

Predicting the aquatic risk of realistic pesticide mixtures to species assemblages in Portuguese river basins

Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This study estimated the impact of measured pesticide mixtures in surface waters from 2002 and 2008 within three important Portuguese river basins (‘Mondego’, ‘Sado’ and ‘Tejo’) on primary producers, arthropods and fish by toxic pressure calculation. Species sensitivity distributions (SSDs), in combination with mixture toxicity models, were applied. Considering the differences in the responses of the taxonomic groups as well as in the pesticide exposures that these organisms experience, variable acute multi-substance potentially affected fractions (msPAFs) were obtained. The median msPAF for primary producers and arthropods in surface waters of all river basins exceeded 5%, the cut-off value used in the prospective SSD approach for deriving individual environmental quality standards. A ranking procedure identified various photosystem II inhibiting herbicides, with oxadiazon having the relatively largest toxic effects on primary producers, while the organophosphorus insecticides, chlorfenvinphos and chlorpyrifos, and the organochloride endosulfan had the largest effects on arthropods and fish, respectively. These results ensure compliance with European legislation with regard to ecological risk assessment and management of pesticides in surface waters.     

Predicting the aquatic risk of realistic pesticide mixtures to species assemblages in Portuguese river basins

Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This study estimated the impact of measured pesticide mixtures in surface waters from 2002 and 2008 within three important Portuguese river basins(‘Mondego', ‘Sado' and ‘Tejo') on primary producers, arthropods and fish by toxic pressure calculation. Species sensitivity distributions(SSDs), in combination with mixture toxicity models, were applied. Considering the differences in the responses of the taxonomic groups as well as in the pesticide exposures that these organisms experience, variable acute multi-substance potentially affected fractions(ms PAFs) were obtained. The median msP AF for primary producers and arthropods in surface waters of all river basins exceeded 5%, the cut-off value used in the prospective SSD approach for deriving individual environmental quality standards. A ranking procedure identified various photosystem II inhibiting herbicides, with oxadiazon having the relatively largest toxic effects on primary producers, while the organophosphorus insecticides, chlorfenvinphos and chlorpyrifos, and the organochloride endosulfan had the largest effects on arthropods and fish, respectively. These results ensure compliance with European legislation with regard to ecological risk assessment and management of pesticides in surface waters.     

基于机器学习的长江流域农田氮径流流失负荷估算

定量解析长江流域农田氮径流流失特征是实现长江及其河口氮污染有效控制的关键科学基础.基于收集的长江流域570个旱地和434个水田田间氮径流流失数据组,采用相关性分析、结构方程模型、方差分解和机器学习方法,探究了影响旱地和水田总氮径流流失强度的主要因素,建立了基于机器学习的长江流域旱地和水田总氮径流流失强度预测模型,量化了长江流域农田总氮径流流失负荷.结果表明,径流深、施氮量和土壤氮含量是影响旱地总氮径流流失强度的主要因素;径流深和施氮量是水田总氮径流流失强度的主要影响因素.与分类与回归树、多元线性回归和增强回归树方法相比,采用随机森林算法构建的长江流域旱地和水田总氮径流流失强度预测模型具有更高的精度（R²为0.65~0.94）.基于随机森林算法的预测模型估算的2013年长江流域农田总氮径流流失负荷（以N计）为0.47 Tg ·a^-1（旱地：0.25 Tg ·a^-1;水田：0.22 Tg ·a^-1）,中下游地区贡献了58%的流失负荷.模型预测5种防治情景下的长江流域农田氮流失负荷可削减2.4%~9.3%,其中减少径流量的削减效果最为显著.长江流域农田氮面源污染防治必须协同加强氮肥精准管理、减少农田径流量和提高土壤氮利用,且应将重点放在中下游地区.所发展的基于机器学习建模方法克服了氮径流流失强度与影响因素之间函数关系难以确定的问题,为估算区域或流域农田氮流失负荷提供了简便且可靠的方法.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

有机磷农药废水的产生及处理

农药工业是中国化学工业主要行业之一,有机磷农药在中国的农药结构中占有较高的份额,农药的"三废"问题以废水最为严峻和突出.有机磷农药是由有毒的化学原料合成的一种化学农药,合成过程中要排放出大量废水,每合成1吨农药约消耗3-4t化工原料,排放废水3-2t,且废水污染物浓度高.在分析了不同的有机磷农药其废水的产生来源,实际工作中接触到的淄博农药生产厂家几种主要有机磷农药废水的水量、水质.如何用有机磷农药废水常用的处理方法及回收利用.     

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter

In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60 days using a real farmer''s pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability.     

The profiles of chiral pesticides in peri-urban areas near Yangtze River: Enantioselective distribution characteristics and correlations with surface sediments

Chiral pesticides account for 30% of pesticides. Pesticides are inevitably leached into the groundwater by runoff. At the watershed level, the distribution characteristics of enantiomers in sediments collected from the river network of an agricultural area near the middle and lower reaches of the Yangtze River were tested, and their potential correlations with the physicochemical properties and microbial communities of the sediments were analyzed. The sediment pollution was serious at sites 8 and 9, with their pollution source possibly being agricultural or industrial sewage. Moreover, there were higher cumulative contents of pesticide residues at sites 4, 8, and 9. Specifically, Cycloxaprid was the most detected chiral pesticide in the study area, followed by Dinotefuran and Diclofop-methyl. Additionally, Ethiprole and Difenoconazole had strong enantioselectivity in the study area. Interestingly, the enantiomers of some chiral pesticides, such as Tebuconazole, had completely different distributions at different sites. Pearson correlation analysis showed that sediment catalase and microbial biomass carbon were important factors for enantioselectivity of chiral pesticides. The effect of sediment physicochemical properties on enantioselective distribution was achieved by influencing the microorganisms in the sediment. Furthermore, the enantioselective distribution of Tebuconazole was closely related to the genus Arenimonas. Overall, the enantioselective distribution of most of the chiral pesticides was positively correlated with the prokaryotic microbial community. This study provides empirical support for agricultural non-point source pollution caused by chiral pesticides, and also lays a research foundation for exploring the factors that affect the fate of chiral pesticides in the environment.