Water, Environment Process Development and Analysis Division, Bureau de Recherches Géologiques et Minières (BRGM), 3 Avenue Claude Guillemin, 45060, Orléans cedex 2, France.
SUEZ, CIRSEE, 38 rue du président Wilson, 78230, le Pecq, France.
Environ Sci Pollut Res Int. 2020 May;27(15):18565-18576. doi: 10.1007/s11356-020-08385-0. Epub 2020 Mar 21.
Pesticides occur in groundwater as a result of agricultural activity. Their monitoring under the Water Framework Directive is based on only a few spot-sampling measurements per year despite their temporal variability. Passive sampling, which was successfully tested in surface water to provide a more representative assessment of contamination, could be applied to groundwater for a better definition of its contamination. However, few reliable calibration data under low water flow are available. The objective of our study thus consisted in determining sampling rates by two types of passive samplers, a POCIS (polar organic chemical integrative sampler) for polar pesticides, and a POCIS-MIP sampler based on a receiving phase of molecular imprinted polymers, specific for AMPA and glyphosate under low flow conditions as exist in groundwater. To our knowledge, this is the first time that sampling rates (sampling rate represents the volume of water from which the analyte is quantitatively extracted by the sampler per unit time) are estimated for groundwater applications. Our calibrations took place in an experimental pilot filled with groundwater and with low water flow (a few metres per day). Pesticide uptake in POCIS showed good linearity, with up to 28 days before reaching equilibrium. Two types of accumulation in POCIS were noted (a linear pattern up to 28 days, and after a time lag of 7 to 14 days). Sampling rates for 38 compounds were calculated and compared with those available in the literature or obtained previously under laboratory conditions. The values obtained were lower by a factor 1 to 14 than those estimated under stirring conditions in the literature, whereas water flow velocity (m s) differed by a factor of 2000 to 10,000.
农药会因农业活动而进入地下水。尽管其具有时间变异性，但根据《水框架指令》，对地下水的监测每年仅进行几次现场抽样测量。尽管在地表水监测中成功测试了被动采样法，以更准确地评估污染情况，但该方法尚未应用于地下水，以更好地定义其污染程度。然而，在低水流条件下，可靠的校准数据非常有限。因此，我们的研究目的是通过两种类型的被动采样器（用于极性农药的 POCIS 和基于分子印迹聚合物接收相的 POCIS-MIP 采样器）来确定采样率，这两种采样器都可用于在低水流条件下（类似于地下水中的情况）对 AMPA 和草甘膦进行更准确的检测。据我们所知，这是首次针对地下水应用情况来估算采样率（采样率代表单位时间内从采样器定量提取分析物的水量）。我们的校准在一个充满地下水且水流缓慢的实验模型中进行（每天只有几米）。在 POCIS 中，农药的吸收表现出良好的线性关系，直到达到平衡前有长达 28 天的时间。在 POCIS 中注意到两种积累模式（线性模式长达 28 天，然后是 7 至 14 天的滞后时间）。我们计算了 38 种化合物的采样率，并与文献中的值或以前在实验室条件下获得的值进行了比较。与文献中搅拌条件下的估计值相比，所得值低了 1 到 14 倍，而水流速度（m/s）相差了 2000 到 10000 倍。
