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Agricultural Nutrients and Pesticide Pollution in Aquatic Ecosystems, with Policy Implications

Joel Onyango

Enhanced agricultural productivity has led to intensification of irrigation and increased application of agrochemicals. Further expansion of agriculture will increase environmental risks from application of nutrients and pesticides. Pressures from agrochemicals can act with or separately from habitat modifications of either, or both, terrestrial and aquatic ecosystems. Addressing the impact of pollution requires adaptable management, which necessitates development and implementation of adequate policies that are able to accommodate increasing agricultural production while mitigating associated risks of water pollution. This paper explores the global drivers of and pressures from agricultural expansion. The paper reviews the underlying factors in agriculture that result in combined nutrients and pesticides loads and impact. The paper further discusses the independent effects on nutrients and pesticides in aquatic ecosystems, followed by the potential combined effects of both nutrients and pesticides. The combined effects of nutrients and pesticides are explored based on the concentration addition, independent action and interaction approaches. While management measures incorporating combined nutrients and pesticides are still not well developed, the paper explores key steps towards monitoring measures for combined nutrients and pesticides contamination: detection and identification; and prioritization of measures.