Ecole Nationale Polytechnique, Laboratory of Environmental Sciences and Technology, 10 Avenue Hassen Badi, BP 182, 16200 Algiers, Algeria.
Environ Monit Assess. 2013 May;185(5):4107-15. doi: 10.1007/s10661-012-2853-0. Epub 2012 Aug 29.
Metribuzin is a widely used herbicide around the world but it could lead to soil and water contamination. Metribuzin retention on a silty-clay agricultural soil of Algeria was studied in laboratory batch experiments to assess the contamination risk of the groundwater. Factors conditioning the fate of metribuzin were investigated: soil nature, metribuzin formulation, NPK fertilizer, and soil pH. Freundlich sorption isotherms gave the coefficients K F between 1.2 and 4.9 and 1/n a between 0.52 and 0.93. The adsorption is directly dependent on organic and clay soil contents. Formulated metribuzin (Metriphar) reduces the adsorption (K F = 1.25) compared to pure metribuzin (K F = 2.81). The addition of an NPK fertilizer decreases the soil pH (6.67 for the soil without fertilizer and 5.86 for 2 % of fertilizer) and increases metribuzin adsorption (K F is 4.83 for 2 % of fertilizer). The pH effect on the adsorption is corroborated in experiments changing the soil pH between 5 (K F is 4.17) and 8 (K F is 1.57) under controlled conditions. Desorption isotherms show a hysteresis and only 30 to 40 % of the initially adsorbed metribuzin is released. The estimated GUS index is ≥ 2.8 for a DT50 ≥ 30 days. K F values and the hysteresis show that metribuzin is little but strongly retained on the soil. Formulated metribuzin and addition of fertilizer affect the retention. However, the GUS index indicates a high mobility and a significant risk of leaching. The most appropriate risk management measure would be an important increase in organic matter content of the soil by addition of organic amendments.
灭草松是一种在世界各地广泛使用的除草剂，但它可能导致土壤和水污染。本研究采用实验室批量实验，研究了灭草松在阿尔及利亚粉质粘壤土中的残留情况，以评估地下水的污染风险。考察了影响灭草松命运的因素：土壤性质、灭草松制剂、NPK 肥料和土壤 pH 值。Freundlich 吸附等温线给出了 1.2 到 4.9 之间的 K F 系数和 0.52 到 0.93 之间的 1/n a 值。吸附直接取决于有机和粘土壤土含量。制剂灭草松（Metriphar）比纯灭草松（K F = 2.81）减少了吸附（K F = 1.25）。NPK 肥料的添加降低了土壤 pH 值（无肥料的土壤为 6.67，2%的肥料为 5.86），增加了灭草松的吸附（K F 为 2%的肥料时为 4.83）。在控制条件下，通过改变土壤 pH 值（5 时 K F 为 4.17，8 时 K F 为 1.57）的实验，证实了 pH 值对吸附的影响。解吸等温线显示出滞后性，只有 30%到 40%的初始吸附的灭草松被释放。GUS 指数估计值≥2.8，DT50≥30 天。K F 值和滞后性表明，灭草松在土壤中的保留量虽少但很强。制剂灭草松和肥料的添加影响了保留。然而，GUS 指数表明，其具有高迁移性和显著的淋溶风险。最适当的风险管理措施是通过添加有机改良剂，显著增加土壤中的有机质含量。
