Study of pesticides in waters from a chalk catchment,cambridgeshire

WRc are undertaking a long term study of pesticides in the aquatic environment. A study of the pesticides in the rain, river water and groundwater of the Granta catchment in Cambridgeshire is now in its fourth year. Preliminary results are presented and the concentrations of agricultural pesticides in environmental waters are related to the land-use within the catchment. The Granta study is incomplete but certain anomalies in pesticide occurrence can be identified. In particular, the triazines are much more prevalent in the groundwaters than their agricultural usage would lead one to expect. The limited data base gives problems with modelling the contaminant transport in groundwater. The present situation is reviewed and areas of future work necessary to fulfil the modelling needs identified. These areas of study. The historical land-use and pesticide usage; the groundwater quality data base; the pesticide transport in the unsaturated zone.     

Applying weather index insurance to agricultural pest and disease risks

In this paper, we explore the application of weather index insurance to plant pest and disease management strategies using two distinct models: (1) insuring crop loss due to disease incidence (“Crop Insurance”) and (2) insuring the use of pesticides (“Pesticide Insurance”). We find that despite the seeming ease of applying weather-based pest incidence models to an insurance product, insuring plant disease incidence models is presently unsuitable for the insurance market for both scientific and behavioral reasons. However, derivative-like applications of weather index insurance to insure pesticide use offer a means to introduce financial leverage into pesticide usage decisions. Risk management with weather index insurance would thus function as a complement to existing risk management strategies using pesticides, and offer a market-based mechanism for pesticide abatement. We conclude that more interdisciplinary collaboration is needed to develop weather index insurance for remuneration of losses due to plant pests and diseases, but weather index insurance offers a potential mechanism to reduce inefficiencies and negative externalities in agricultural markets if pesticide expenditures are insured instead of crop losses.     

Integrated modeling environment for statewide assessment of groundwater vulnerability from pesticide use in agriculture

Atrazine, a herbicide widely used for corn production in the Midwest, has been detected in groundwater of several states, and has been identified as a possible human carcinogen. With the widespread use of pesticides in crop production, and the frequent detection of these chemicals in groundwater, large-scale risk assessments would help water resource managers to identify areas that are more susceptible to contamination and implement practices to ameliorate the problem. This paper presents an integrated, visual and interactive system for predicting potential environmental risks associated with pesticide contamination at spatial scales ranging from fields to landscapes and regions. The interactive system extends the predictive ability of the Pesticide Root Zone Model Release 2.0 (PRZM-2) to a landscape and statewide scale through integration with a geographic information system (GIS), graphical user interface and environmental databases. Predictions of statewide (Iowa) vulnerability of groundwater from atrazine leaching below the unsaturated zone were made to demonstrate the utility of the system, and the results were used in risk assessment. In the example application, atrazine fate and transport were evaluated using long-term climatic data (1980--1989) in combination with several environmental databases (eg STATSGO soils database) and exposure risks were expressed in terms of the probability of the predicted pesticide concentrations exceeding the maximum contaminant level (MCL) for drinking water. The results indicate that the predicted pesticide concentrations were significantly lower than the EPA-established MCL. In addition to providing an interactive environment for landscape-level assessment of potential risks from pesticide leaching, the system significantly reduces the time and resources needed to organize and manipulate data for use with PRZM-2, and provides an analytical framework for evaluating groundwater-leaching impacts of pesticide management practices.     

Comparison of adherence tendencies of pesticide residues sprayed on small-, medium-, and large-sized tomatoes

Crop field trials were conducted to investigate the residues of sprayed pesticides on the different sizes of tomatoes. Pesticide residue data in tomatoes varied due to different locations of the three crop fields selected and/or physicochemical properties of the three pesticides tested. The pesticide residue levels in the medium- and small-sized tomatoes were 1.5 and 2.4 times higher than the level in large-sized tomatoes under similar spray conditions, whereas amount of pesticides adhered per unit surface area were approximately equal among all three sizes of tomatoes. The results of this study suggested that the differences in pesticide residue levels were due to differences in the degree of specific surface area of each tomato size. Resultant residue data of medium-sized tomatoes demonstrated a proportional relationship between pesticide residue levels and the specific surface area of tomatoes.     

Factors influencing entry of pesticides into soil water

Leaching of pesticides and hence the risk of contamination of ground-water depends on the physicochemical properties of the pesticide, the properties of the soil and the weather. Lipophilicity is the most important physicochemical property influencing the movement of un-ionised pesticides through soil. Water solubility is usually only an important factor in leaching for a few moderately polar solids with high melting points. Organic matter content is the most important property of the soil for un-ionised pesticides whilst the mobility of weak acids depends on soil pH. Permanent anions and weak acids can be very weakly adsorbed and hence might easily reach groundwater. Applications in autumn are more likely to reach groundwater than those in spring because soil temperatures are low and rainfall exceeds evaporation in winter, enabling mobile pesticides to penetrate to subsoils where degradation rates can be very slow. Concentrations of pesticide in water entering subsoils cannot be reliably simulated to an accuracy of better than an order of magnitude because the complex patterns of water flow and the slow diffusion processes of the pesticide are insufficiently understood. The consequences of applying a mobile pesticide to soil where drainage is impeded or where the water table is near the surface need to be anticipated before it is registered for treatment of the soil.     

Pesticide‐laden dust emission and drift from treated seeds during seed drilling: a review

Dressing seeds with pesticides to control pests is a widespread practice with important advantages. Recent incidents of bee losses, however, have directed attention to the emission of abraded pesticide‐coated seed particles to the environment during sowing. This phenomenon of drift of pesticide dust can lead to pesticide contamination of air, water and other natural resources in crop‐growing areas. This review article presents the state of the art of the phenomenon of dust emission and drift from pesticide seed dressing during sowing and its consequences. Firstly, pesticide seed treatment is defined and its pros and cons are set out, with the focus on dust, dust emission and dust drift from pesticide‐coated seed. The factors affecting emission of pesticide dust (e.g. seed treatment quality, seed drilling technology and environmental conditions) are considered, along with its possible effects. The measuring techniques and protocols and models currently in use for calculating the behaviour of dust are reviewed, together with their features and limitations. Finally, possible mitigation measures are discussed, such as improving the seed quality and the use of modified seed drilling technology, and an overview of regulations and stewardship activities is given. © 2013 Society of Chemical Industry     

The potential environmental impact of pesticides removed from sprayers during cleaning

BACKGROUND: There is concern that pesticide residues on the external surfaces of sprayers could have an adverse impact on the environment if they are washed off, yet there is a need to remove these residues for health reasons. The aim of this study was to quantify pesticide residues contained in washings from cleaning discrete parts of a sprayer and to assess their likely environmental impact. RESULTS: The boom/rear of the sprayer and the spray tank accounted for 80% of the total pesticide load in the washings. Predicted environmental pesticide concentrations from sprayer washings were lower than predictions from the FOCUS surface water model for pesticides used under normal agricultural conditions, although for tebuconazole this difference was smaller than for the other compounds investigated. The field area over which the residues may need to be uniformly deposited to avoid overdosing during infield cleaning was typically less than 0.5 m(2), with a maximum value of 4 m(2). CONCLUSIONS: It is unlikely that infield cleaning will lead to overdosing. External residues are not insignificant, so any adverse impact on the environment must be mitigated. Appropriate measures include cleaning in the field away from surface waters and other sensitive areas, and cleaning machines over bunded areas or similar.     

农药有效利用率与喷雾技术优化

提高农药的有效利用率是植保工作者非常关心的问题。本文阐述了农药有效利用率的广义和狭义涵义,并分析了农药使用中存在的药剂浪费、有效利用率低的问题。根据喷雾技术中的“剂量传递”过程,分析了农药有效利用率的狭义涵义,在春季果园和作物苗期,常规喷雾法的农药有效利用率只有20%~30%;在夏秋季果园和作物中后期,随着作物叶面积系数（LAI）的增加,农药的有效利用率可达到50%~60%。论文分析了造成农药有效利用率低的原因,提出喷雾技术的优化措施：（1）大田喷雾时采用机动喷杆喷雾替代背负式手动常规喷雾,可以改善雾滴沉积分布的均匀性;（2）添加喷雾助剂可以提高药液在靶标表面的润湿性;（3）优化雾滴粒径,采用细雾滴替代粗雾滴可以提高雾滴的中靶率;（4）降低施药液量可以减少药液流失;（5）加装挡板可以减少雾滴飘失等。通过以上技术的优化,可以大幅度提高农药的有效利用率,达到减量增效的目的。     

Effects of soil redistribution by tillage on subsequent transport of pesticide to subsurface drains

BACKGROUND

Tillage operations will change the distribution in soil for any pesticide residues still present from earlier applications. This redistributive effect of tillage has been neglected in the study of pesticide leaching behavior. This study reviews the literature to characterize this redistributive effect for different tillage operations and uses a pesticide leaching model to investigate the impact of redistribution on pesticide transport to subsurface drains which is a significant input route to surface water bodies.

RESULTS

Inversion ploughing moves the majority of any residues of pesticide present at or near the soil surface into the bottom two-thirds of the plough layer, whereas non-inversion ploughing has only a limited redistributive effect. Incorporating this redistributive effect into model simulations resulted in large changes (typically 5–10-fold difference) in both the maximum concentration and total mass of pesticide transported to drains over the winter following cultivation. More intense cultivation decreased subsequent leaching for relatively mobile compounds (Koc ≤1000 mL g⁻¹), but increased it for strongly sorbed pesticides (Koc ≥2000 mL g⁻¹).

CONCLUSION

The redistributive effect of soil tillage on pesticide residues can have a large effect on subsequent transport to subsurface drains. This effect has been neglected in the literature. Field research is required to validate the model simulations presented here, and consideration should be given as to whether the effect needs to be included within risk assessment procedures. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

农药兑水茎叶喷施对靶沉积剂量传递与调控研究进展

农药兑水茎叶喷施对靶沉积是一个复杂的剂量传递与分布过程，涉及制剂形成、药液配制、雾化分散、空间运行、叶面沉积和稳态持留等动态过程，受到药剂特性、环境因素、为害规律、植株形态和叶面结构等多因素影响，在水稻、小麦和玉米三大粮食作物上对靶沉积率为40.6%。其中，对不同区域、不同靶标作物种植体系中农药损失规律和高效利用机理研究与认识不足，是农药对靶沉积剂量传递效率低的主要原因之一。本文以农药向靶标作物及有害生物传递的过程行为为主线，将农药兑水茎叶喷施对靶沉积的剂量传递过程分解为雾滴空间运行、叶面动态沉积和稳态持留3个过程，从空间维度综述了各过程中的表观现象与行为、损失规律及其调控机制途径与技术等；从技术发展与进步角度，分析了农药对靶沉积剂量传递与调控研究和认知的发展思路，概述了典型代表性成果，提出了未来研究与发展建议。期望客观认知农药高效对靶沉积的损失规律与调控机制，探析主控过程与影响因子，提出农药减量施用调控方法、控制技术指标及功能助剂施用限量标准等，为农药减施增效关键技术与产品研发提供理论与技术支持。     

A review of pesticide policies and regulations for urban amenity areas in seven European countries

An analysis of the regulations of herbicide use for weed control in non-agricultural/urban amenity areas, including actual pesticide use, was carried out as a joint survey of seven European countries: Denmark, Finland, Germany, Latvia, the Netherlands, Sweden and United Kingdom. Herbicides constitute the major part of the pesticides used in urban amenity areas. Herbicide use on hard surfaces is the largest in terms of volume and potential contamination of surface and groundwater. The aim of the study was to investigate the differences in political interest and public debate on the 'use of pesticides in public urban amenity areas', regulations within each country at national, regional and local levels, possible use of alternative weed control methods and the amounts of pesticides used on urban amenity areas. A comparative analysis revealed major differences in political interest, regulations and availability of statistics on pesticide use. Denmark, Sweden, the Netherlands and Germany have, or have had, a strong public and political interest for reducing the use of herbicides to control weeds in urban amenity areas and also have very strict regulations. The UK is currently undergoing a period of increasing awareness and strengthening regulation, while Latvia and Finland do not have specific regulations for weed control in urban amenity areas or on hard surfaces. Statistics on pesticide/herbicide use on urban amenity areas were only available in Denmark and the Netherlands. Developing this kind of information base reveals the differences in herbicide use, regulations and policies in European countries and may enhance the transfer of knowledge on sustainable weed control across countries.     

Recent advances in computational fluid dynamics relevant to the modelling of pesticide flow on leaf surfaces

Increasing societal and governmental concern about the worldwide use of chemical pesticides is now providing strong drivers towards maximising the efficiency of pesticide utilisation and the development of alternative control techniques. There is growing recognition that the ultimate goal of achieving efficient and sustainable pesticide usage will require greater understanding of the fluid mechanical mechanisms governing the delivery to, and spreading of, pesticide droplets on target surfaces such as leaves. This has led to increasing use of computational fluid dynamics (CFD) as an important component of efficient process design with regard to pesticide delivery to the leaf surface. This perspective highlights recent advances in CFD methods for droplet spreading and film flows, which have the potential to provide accurate, predictive models for pesticide flow on leaf surfaces, and which can take account of each of the key influences of surface topography and chemistry, initial spray deposition conditions, evaporation and multiple droplet spreading interactions. The mathematical framework of these CFD methods is described briefly, and a series of new flow simulation results relevant to pesticide flows over foliage is provided. The potential benefits of employing CFD for practical process design are also discussed briefly. © Crown copyright 2009. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

人工智能在农药精准施药应用中的研究进展

传统农药施药方式大多依靠人工经验识别单位种植面积内作物的主要病虫草害并针对该症状均匀连续喷洒农药。该方法难以根据作物的不同病虫草害种类和严重程度及时调整农药种类及用量,可能会导致不足或过量用药,喷洒在非症状区域的农药还会对生态环境造成污染。精准施药技术在平衡使用农药与保护生态安全之间给出了一种有效的解决方案,值得大力推广。近年来,人工智能技术的发展推动了精准施药相关研究。为进一步总结人工智能在农药精准施药关键技术中的应用进展,探索人工智能在农药精准施药未来发展方向,本文分析了人工智能在农药精准施药关键技术领域的应用现状,并展望了人工智能在农药精准施药应用中的发展趋势。     

农药的化学信息学分析

从大英农作物生产研究会e-农药手册(The e-Pesticide Manual V5.0)中提取了1 478个各类农药,利用化学信息学方法对比了农药与临床药物在物理化学性质、分子骨架等方面的差异,分析了二者在化学空间中的分布特点。结果表明:农药具有相对较低的相对分子质量和较高的脂溶性,其F、Cl、P等元素含量明显高于临床药物;在分子骨架和化学空间分布上二者也有着显著差异。因此,在将医药研发的技术应用到农药研发时,应根据农药的特点适当调整设计或计算参数。     

Assessing the risk of pesticide environmental impact in several Argentinian cropping systems with a fuzzy expert indicator

BACKGROUND: The introduction of transgenic soybean (Glycine max, L.) varieties resistant to glyphosate (GR soybeans) has rapidly expanded in Argentina, increasing pesticide use where only grasslands were previously cultivated. The authors compared an estimate of environmental risk for different crops and active ingredients using the IPEST index, which is based on a fuzzy‐logic expert system. For IPEST calculations, four modules are defined, one reflecting the rate of application, the other three reflecting the risk for groundwater, surface water and air. The input variables are pesticide properties, site‐specific conditions and characteristics of the pesticide application. The expert system calculates the value of modules according to the degree of membership of the input variables to the fuzzy subsets F (favourable) and U (unfavourable), and they can be aggregated following sets of decision rules. IPEST integrated values of ≥ 7 reflect low environmental risk, and values of < 7 reflect high risk. RESULTS: Alfalfa, soybean and wheat showed IPEST values over 7 (low risk), while maize had the lowest IPEST values (high risk). Comparing active ingredients applied in annual and perennial crops, atrazine and acetochlor gave the highest risks of environmental contamination, and they are mainly used in maize. Groundwater was the most affected compartment. CONCLUSIONS: Fuzzy logic provided an easy tool combining different environmental components with pesticide properties to give a simple and accessible risk assessment. These findings provide information about active ingredients that should be replaced in order to protect water and air from pesticide contamination. Copyright © 2010 Society of Chemical Industry     

Degradation and leaching potential of pesticides in biobed systems

Biobeds provide a potential solution to pesticide contamination of surface waters arising from the farmyard. Previous work has shown that biobeds can effectively treat spills and splashes of pesticide. This study investigated the potential for biobeds to treat much larger volumes and amounts of pesticide waste not only arising from spills but also from washing processes. Two systems were assessed using a range of pesticides at the semi-field scale, ie a lined biobed system and an unlined system. Studies using the lined biobeds demonstrated that water management was crucial, with biobeds needing to be covered to exclude rain-water. Once covered, the top of the biobed became hydrophobic, restricting moisture loss and resulting in saturated conditions at depth. The drying out of the top layer coincided with a measured decrease in microbial biomass in the treated biobeds. Applied pesticides were effectively retained within the 0-5 cm layer. Whilst all pesticides tested degraded, low moisture content and microbial activity meant degradation rates were low. Studies using unlined biobeds showed that only the most mobile pesticides leached, and for these > 99% was removed by the system, with a significant proportion degraded within 9 months. Peak concentrations of the two most mobile pesticides did however exceeded the limits that are likely to be required by regulatory bodies. However, it is thought that these limits could be reached by optimisation of the system.     

Pesticide exposure assessment in rice paddies in Europe: a comparative study of existing mathematical models

A comparative test was undertaken in order to identify the potential of existing mathematical models, including the rice water quality (RICEWQ) 1.6.4v model, the pesticide concentration in paddy field (PCPF-1) model and the surface water and groundwater (SWAGW) model, for calculating pesticide dissipation and exposure in rice paddies in Europe. Previous versions of RICEWQ and PCPF-1 models had been validated under European and Japanese conditions respectively, unlike the SWAGW model which was only recently developed as a tier-2 modelling tool. Two datasets, derived from field dissipation studies undertaken in northern Italy with the herbicides cinosulfuron and pretilachlor, were used for the modelling exercise. All models were parameterized according to field experimentations, as far as possible, considering their individual deficiencies. Models were not calibrated against field data in order to remove bias in the comparison of the results. RICEWQ 1.6.4v provided the highest agreement between measured and predicted pesticide concentrations in both paddy water and paddy soil, with modelling efficiency (EF) values ranging from 0.78 to 0.93. PCPF-1 simulated well the dissipation of herbicides in paddy water, but significantly underestimated the concentrations of pretilachlor, a chemical with high affinity for soil sorption, in paddy soil. SWAGW simulated relatively well the dissipation of both herbicides in paddy water, and especially pretilachlor, but failed to predict closely the pesticide dissipation in paddy soil. Both RICEWQ and SWAGW provided low groundwater (GW) predicted environmental concentrations (PECs), suggesting a low risk of GW contamination for the two herbicides. Overall, this modelling exercise suggested that RICEWQ 1.6.4v is currently the most reliable model for higher-tier exposure assessment in rice paddies in Europe. PCPF-1 and SWAGW showed promising results, but further adjustments are required before these models can be considered as strong candidates for inclusion in the higher-tier pesticide regulatory scheme.     

Analysis of various Iowa waters for selected pesticides: atrazine, DDE, and dieldrin-1974.

Atrazine, DDE, and dieldrin were extracted and concentrated from various surface, subsurface, and finished waters using the macroreticular resin method. Organic components in the concentrates from these waters were separated by gas chromatography; the amounts of the three pesticides in the waters ranged from 0.5 to 42,000 parts per trillion by weight. Every major watershed in the State of Iowa revealed some degree of pesticide contamination and seasonal variations were consistent with agricultural runoff models. Atrazine concentrations were highest of the three pesticides, a symptom of its widespread use in the corn belt. DDE also appeared in substantial quantities, providing further evidence of the persistence of DDT and its metabolites. Water from several shallow wells and finished water from many water treatment plants were also contaminated. Current treatment processes do not effectively remove these pesticides.     

SWAT—A Semi-empirical Model to Predict Concentrations of Pesticides Entering Surface Waters from Agricultural Land

A semi-empirical model called SWAT has been developed to predict concentrations of agriculturally applied pesticides moving to surface waters, an aspect which is not well described by current models for pesticide fate. The model is based upon a direct hydrological link established between soil type and the amount of water moving rapidly to streams in response to rainfall. Attenuation factors describe the decrease in concentrations of pesticide between field application and loss in water moving from the site into surface waters. Evaluation of model predictions against available field data from three sites and four soil types in England shows that SWAT is capable of predicting the transient peak concentrations of a wide range of pesticides during rapid water movement to streams in response to rainfall. Predicted concentrations were too great when rainfall initiated water movement to streams very soon after pesticide application, particularly for the more mobile pesticides, and some predictions for pesticides sorbed very strongly to soil were relatively poor. Almost all of the predicted concentrations were within one order of magnitude of measured values.