School of Public Health, University of Illinois at Chicago , Chicago, Illinois 60612, United States.
Department of Civil and Materials Engineering, University of Illinois at Chicago , Chicago, Illinois 60607, United States.
Environ Sci Technol. 2016 Jul 19;50(14):7335-43. doi: 10.1021/acs.est.6b00706. Epub 2016 Jul 1.
Surface grab and core sediment samples were collected from Lakes Michigan, Superior, and Huron from 2010 to 2012, and concentrations of herbicides atrazine, simazine, and alachlor, as well as desethylatrazine (DEA), were determined. Concentrations of atrazine in surface grabs ranged from 0.01 to 1.7 ng/g dry weight and are significantly higher in the southern basin of Lake Michigan (latitude <44°) than other parts of the three lakes. The highest concentration of alachlor was found in sediments of Saginaw Bay in Lake Huron. The inventory and net fluxes of these herbicides were found to decline exponentially from the south to the north. The concentration ratio of DEA to atrazine (DEA/ATZ) increased with latitude, suggesting degradation of atrazine to DEA during atmospheric transport. DEA/ATZ also increased with sediment depth in the sediment cores. Diffusion of deposited herbicides from the upper sediment into deeper sediments has occurred, on the basis of the observed patterns of concentrations in dated sediment cores. Concentrations of atrazine in pore water were estimated and were higher than those reported for the bulk waters, suggesting the occurrence of solid-phase deposition of atrazine through the water column and that contaminated sediments act as a source releasing atrazine to the overlying water.
从 2010 年到 2012 年，从密歇根湖、苏必利尔湖和休伦湖采集了表层抓样和岩芯沉积物样本，并测定了莠去津、西玛津和甲草胺以及去乙基莠去津（DEA）的浓度。表层抓样中莠去津的浓度范围为 0.01 至 1.7ng/g 干重，且在密歇根湖南部（纬度<44°）显著高于其他三个湖的其他区域。在休伦湖的萨吉诺湾沉积物中发现了最高浓度的甲草胺。这些除草剂的存量和净通量从南向北呈指数下降。DEA 与莠去津的浓度比（DEA/ATZ）随纬度增加而增加，表明莠去津在大气传输过程中降解为 DEA。DEA/ATZ 也随着沉积物芯的深度增加而增加。基于对定年沉积物芯中浓度的观测模式，推断出沉积的除草剂从上层沉积物向深层沉积物的扩散已经发生。根据估算的孔隙水中莠去津的浓度，高于报告的水体总浓度，这表明莠去津通过水柱发生固相沉积，受污染的沉积物作为释放莠去津到上覆水体的源。
