Mitigation of agricultural nonpoint-source pesticide pollution in artificial wetland ecosystems

Abstract

International audienceContamination caused by pesticides in agriculture is a source of environmental poor water quality in some of the European Union countries. Without treatment or targeted mitigation, this pollution is diffused in the environment. Pesticides and some metabolites are of increasing concern because of their potential impacts on the environment, wildlife and human health. Within the context of the European Union (EU) water framework directive context to promote low pesticide-input farming and best management practices, the EU LIFE project ArtWET assessed the efficiency of ecological bioengineering methods using different artificial wetland (AW) prototypes throughout Europe. We optimized physical and biological processes to mitigate agricultural nonpoint-source pesticide pollution in artificial wetland ecosystems. Mitigation solutions were implemented at full-scale demonstration and experimental sites. We tested various bioremediation methods at seven experimental sites. These sites involved (1) experimental prototypes, such as vegetated ditches, a forest microcosm and 12 wetland mesocosms, and (2) demonstration prototypes: vegetated ditches, three detention ponds enhanced with technology of constructed wetlands, an outdoor bioreactor and a biomassbed. This set up provides a variety of hydrologic conditions, with some systems permanently flooded and others temporarily flooded. It also allowed to study the processes both in field and controlled conditions. In order to compare the efficiency of the wetlands, mass balances at the inlet and outlet of the artificial wetland will be used, taking into account the partition of the studied compound in water, sediments, plants, and suspended solids. The literature background necessary to harmonize the interdisciplinary work is reviewed here and the theoretical framework regarding pesticide removal mechanisms in artificial wetland is discussed. The development and the implementation of innovative approaches concerning various water quality sampling strategies for pesticide load estimates during flood, specific biological endpoints, innovative bioprocess applied to herbicide and copper mitigation to enhance the pesticide retention time within the artificial wetland, fate and transport using a 2D mixed hybrid finite element model are introduced. These future results will be useful to optimize hydraulic functioning, e.g., pesticide resident time, and biogeochemical conditions, e.g., dissipation, inside the artificial wetlands. Hydraulic retention times are generally too low to allow an optimized adsorption on sediment and organic materials accumulated in artificial wetlands. Absorption by plants is not either effective. The control of the hydraulic design and the use of adsorbing materials can be useful to increase the pesticides residence time and the contact between pesticides and biocatalyzers. Pesticide fluxes can be reduced by 50-80% when hydraulic pathways in artificial wetlands are optimized by increasing ten times the retention time, by recirculation of w...

Constructed wetlands with light expanded clay aggregates for agricultural wastewater treatment

“…Their use as buffer zones to provide effective protection of water bodies from agricultural runoff events, namely for the containment of associated pesticide contamination hazards, has also been studied and applied (Gregoire et al, 2009;Warsaw et al, 2012;Matamoros et al, 2012b).…”

Advances in Chile for the Treatment of Pesticide Residues: Biobeds Technology

“…The point source pollution by pesticides, a result of accidental spillages or inadequate residue management, has been rigorously investigated in the last decade in Europe, fi nding that it plays a key role in soil and water pollution (Gregoire et al 2009 ). In Chile, point source pollution by pesticides has not been evaluated; nevertheless, it is expected that the situation could be similar to Europe, particularly in basins with greater pressure from pesticide use, as in fruit production.…”

Land Use: Catchment Management

“…Slowing water in drainage ditches using vegetation and/or low grade weirs allows attenuation of nitrogen and phosphorus (Ensign et al, 2006;Kröger et al, 2011). Retention of runoff water in constructed wetlands can also enable denitrification of nitrate and uptake and sediment adsorption of phosphorus, sedimentation, degradation and decay of pathogenic bacteria (Scholz et al, 2010;Wilcock et al, 2012) and pesticides (Moore et al, 2007;Gregoire et al, 2009). Sediment traps and flow diversion terraces in fields facilitate deposition of sediments entrained in field runoff (Yang et al, 2009;Ockenden et al, 2012).…”