Regulation of diffuse pesticide pollution: Combining point source reduction and mitigation in stormwater wetland (Rouffach, France)

摘要

The economic crisis and increasingly stringent water quality requirements demand integrative approaches to reduce pesticide pollution in aquatic ecosystems and limit water treatment. In this study, environmental economists and wetland scientists joined forces to analyze the combination of different abatement measures to reduce pollution with more efficiency. Pesticide reduction directly at source (i.e., reduction of pesticide use), and combining pesticide source reduction with mitigation using a stormwater wetland to treat pesticide runoff are compared. The capacity of the buffer zone to reduce additional diffuse pollution with a given total abatement cost is evaluated, by placing emphasis on how the contribution of a buffer zone evolves according to the total cost. Fungicides were used as a representative class of synthetic pesticides widely used in vine growing, and more largely in conventional agriculture. Our results show that coupling reduction of pesticide source with the use of buffer zones collecting pesticide runoff can be economically advantageous. For a given total cost, the reduction of fungicide runoff is 90% greater when pesticide reduction at source is combined with pesticide mitigation by a stormwater wetland compared to the case of pesticide reduction at source only. However, the higher the total cost is, the more it is necessary to reduce pesticides at source and thus reduce pesticide mass transfer into aquatic systems. The results of this study is anticipated to be a starting point for considering cost and efficiency when combining different measures targeting pesticide mitigation in surface water, and in particular when using stormwater wetlands as a management practice.