Democritus University of Thrace, Faculty of Agricultural Development, Laboratory of Agricultural Pharmacology and Ecotoxicology, 193 Pantazidou, 68200 Orestias, Greece.
Sci Total Environ. 2012 Dec 15;441:41-8. doi: 10.1016/j.scitotenv.2012.09.074. Epub 2012 Nov 6.
A five-year groundwater monitoring program undertaken in Evros (north-east Greece), showed a diversification in the levels of pesticide residues detected in adjacent transboundary aquifers. During the first two years 37 wells, including irrigation, drinking water and artesian wells were monitored while the next three years the survey was focused on the 11 most contaminated wells. The presence of pesticide residues was also monitored in the phreatic horizon (shallow groundwater) of four experimental boreholes drilled in the respective margins of four fields. Among the compounds found alachlor, metolachlor, atrazine, desethylatrazine (DEA), desisopropylatrazine (DIA) and caffeine were constantly detected. Pesticide concentrations were much lower (up to 1.54 μg/L) in the water of the monitored drinking water wells (deep groundwater aquifers) compared to those found in the phreatic horizon (experimental boreholes) of the respective areas (up to 5.20 μg/L). DEA to atrazine concentration ratios (DAR) determined for the phreatic horizon of the three boreholes and respective wells were lower than 1, indicating that preferential flow was the cause of the fast downward movement of atrazine to the phreatic horizon. In contrast the DAR for the fourth borehole and the adjacent well were greater than 1 indicating the absence of preferential flow of atrazine. Catabolic processes of the soil converted atrazine to DEA which is more mobile than atrazine itself through chromatographic (darcian) flow. This differential behavior of pesticides in adjacent aquifers (3 km) was further investigated by determining the apparent age of water in the two wells. The apparent age of the water present in the first aquifer was 21.7 years whereas the apparent age of that in the second aquifer was approximately 1.2 years. The faster replenishing rate of the latter is an indication that this aquifer is very vulnerable to contamination with pollutants present in the infiltrated soil water.
在希腊东北部的埃夫罗斯进行的一项为期五年的地下水监测计划显示，相邻跨界含水层中检测到的农药残留水平呈现多样化。在前两年监测了 37 口井，包括灌溉井、饮用水井和自流井，接下来的三年调查重点是 11 口污染最严重的井。还在四个实验钻孔的潜水位（浅层地下水）中监测到农药残留，这些钻孔分别位于四个农田的边缘。在所发现的化合物中，持续检测到甲草胺、乙草胺、莠去津、去乙基莠去津 (DEA)、去异丙基莠去津 (DIA) 和咖啡因。与各自地区实验钻孔（潜水位）中发现的浓度相比，监测的饮用水井（深部地下水含水层）中的农药浓度要低得多（最高为 1.54μg/L）（高达 5.20μg/L）。三个钻孔及其各自水井的潜水位确定的 DEA 与莠去津浓度比 (DAR) 均低于 1，表明优先流是莠去津快速向下迁移到潜水位的原因。相比之下，第四个钻孔及其相邻水井的 DAR 大于 1，表明莠去津不存在优先流。土壤的代谢过程将莠去津转化为 DEA，通过色谱（达西）流使其比莠去津本身更具流动性。通过确定两个水井中水中的表观年龄，进一步研究了相邻含水层（3 公里）中农药的这种差异行为。第一含水层中存在的水的表观年龄为 21.7 年，而第二含水层中存在的水的表观年龄约为 1.2 年。后者的补充速度更快，表明该含水层非常容易受到渗透土壤水中存在的污染物的污染。
