Risk mitigation measures for pesticide runoff: How effective are they?

BACKGROUND: One of the most important sources of pesticide pollution of surface waters is runoff and erosion from agricultural fields after rainfall. This study analyses the efficacy of different risk mitigation measures to reduce pesticide runoff and erosion inputs into surface waters from arable land excluding rice fields. RESULTS: Three groups of risk mitigation measures were quantitatively analyzed: vegetative filter strips, micro-dams in row crops and soil conservation measures. Their effectiveness was evaluated based on a meta-analysis of available experimental data using statistical methods such as classification and regression trees, and exploratory data analysis. Results confirmed the effectiveness of vegetative filter strips and micro-dams. Contrary to common assumption, the width of vegetative filter strips alone is not sufficient to predict their effectiveness. The effectiveness of soil conservation measures (especially mulch-tillage) varied widely. This was in part due to the heterogeneity of the available experimental data, probably resulting from the inconsistent implementation and the inadequate definitions of these measures. CONCLUSION: Both vegetative filter strips and micro-dams are effective and suitable, and can therefore be recommended for quantitative assessment of environmental pesticide exposure in surface waters.However, the processes of infiltration and sedimentation in vegetative filter strips should be simulated with amechanistic model like Vegetative Filter Strip Modeling System, VFSMOD. The reduction effect ofmicro-dams can be modelled by reducing the runoff curve number, e.g., in the pesticide root zone model, PRZM. Soil conservationmeasures are in principle promising, but further well-documented data are needed to determine under which conditions they are effective

Pesticide exposure assessment for surface waters in the EU. Pt.2: Determination of statistically based run-off and drainage scenarios for Germany

BACKGROUND In order to assess surface water exposure to active substances of plant protection products (PPP) in the EU, the FOCUS (FOrum for the Co-ordination of pesticide fate models and their USe) surface water workgroup introduced four runoff and six drainage scenarios for Step 3 of the tiered FOCUSsw approach. These scenarios may not necessarily represent realistic worst-case situations for the different Member States of the EU. Hence, the suitability of the scenarios for risk assessment in the national authorisation procedures is not known. RESULTS Using Germany as an example, the paper illustrates how national soil-climate scenarios can be developed to model entries of active substances into surface waters from runoff and erosion (using model PRZM) and from drainage (using model MACRO). In the authorisation procedure for PPPs on member state level, such soil-climate scenarios can be used to determine exposure endpoints with a defined overall percentile. CONCLUSION The approach allows the development of national specific soil-climate scenarios and to calculate percentile-based exposure endpoints. The scenarios have been integrated into a software tool analogous to FOCUS-SWASH which can be used in the future to assess surface water exposure in authorisation procedures of PPPs in Germany