No abstract

No abstract

: A pressure-chamber technique was used to study the root uptake and xylem translocation of some fungicides, herbicides and an insecticide from di †er-ent chemical classes in detopped soybean roots. Physiological parameters such as K`leakage from roots, K`concentrations in the xylem sap, and protein and ATP levels in the root cells were measured so as to evaluate any potential damage of this technique to the root system. HPLC was used to quantify the compounds in the xylem sap. The pressure-chamber technique has proved useful to study the root uptake and translocation of pesticides, does not damage the root system, and allows one to obtain appreciable volumes of xylem sap that can be analysed directly by HPLC, thus avoiding dependence on the availability of radio-labelled compounds. The concentration of each pesticide in the xylem sap showed a steady-state kinetic proÐle. Non-linear regression analysis was used to calculate the steady-state concentration and the time required to achieve 50% of the steady-state concentration was well correlated with log (TSSC 50 ). TSSC 50 the more lipophilic the compound the more time was required to reach the K ow ; steady-state concentration. The efficiency of translocation was assessed by the transpiration stream concentration factor (TSCF) and a non-linear relationship between TSCF and log was observed. The highest TSCF values were mea-K ow sured for those compounds with log values around 3, a lipophilicity value K ow similar to that reported earlier in an analogous experiment with detopped soybean plants but slightly higher than that reported in earlier experiments with intact barley plants. Lower TSCF values were obtained with chemicals with log values below as well as above 3. K ow

No 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...