POCIS for pesticide monitoring in groundwaters: from "low flow" lab calibration to in situ monitoring

Since few decades, polar organic chemical integrative sampler (POCIS) has been successfully applied to the measurement of a wide range of polar organic contaminants including pesticides. Passive sampling offering time integrated sampling that compensates for fluctuations in concentrations and lower detection limits compared to standard water sampling [1]. Applications have been deployed in surface waters [2, 3] or wastewaters [4] after obtaining sampling rate (Rs) by laboratory calibrations. POCIS sampling rates are affected by environmental factors such as water flow rates, that is particularly significant for groundwaters, characterized by low water flow conditions [5, 6]. To develop a better understanding of the relationship between water flow and POCIS accumulation, an experimental system has been implemented to obtain sampling rates for POCIS on representative groundwater hydraulic conditions. In parallel, monitoring campaigns have been undertaken during one year to obtain in situ sampling rate values. Both approaches are evaluated and compared to improve quantitative performances of POCIS for groundwater monitoring.