Mercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
Mercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
复制标题
DOI：
10.1016/j.scitotenv.2013.10.096
复制
发表时间：
2014-06-15
影响因子：
9.8
通讯作者：
Taylor, Howard E.
中科院分区：
文献类型：
--
作者：
Alpers, Charles N.;Fleck, Jacob A.;Taylor, Howard E.
评估了Yolo Bypass野生生物区农业湿地和管理的非农业湿地水质的季节和空间变异性，包括汞物种，该区域被管理用于多种有益用途，包括鸟类栖息地和水稻种植。这项研究是在11个月的时间内(2007年6月至2008年4月)进行的，其中包括夏季生长季节和冬季洪水条件。地表水中甲基汞的浓度变化范围很大(未经过滤的0.1至37 ng L-1；过滤后的0.04至7.3 ng L-1)。最大甲基汞数值是湿地中有记录以来最高的数值之一。在收获期间(2007年9月)野生稻田的排水中观察到未经过滤的地表水中的甲基汞浓度最高，在区域洪水期间(2008年2月)在含有腐烂稻草的白稻田中观察到最高的甲基汞浓度。在白稻田和野生稻田的生长季(2007年6-8月)，未过滤和过滤过的水中总汞的比值(MeHg/mg)增加了约20倍，休耕田(2007年7-8月)增加了约5倍，而永久湿地中的MeHg/THG几乎没有变化。在这些农业湿地中，由于硫酸盐还原菌不受硫酸盐的限制，硫酸盐还原菌对汞(II)的甲基化没有影响。过滤水和未过滤水中甲基汞的浓度与过滤后的铁、过滤后的锰、溶解有机碳以及硫酸盐还原的两个指标：硫酸根/氯离子比和硫酸盐溶液中的S-34有关。这些关系表明，在这种情况下，微生物对SO42-、Fe(III)和可能的Mn(IV)的还原可能有助于汞(II)的净甲基化。爱思唯尔出版公司(Elsevier B.V.)
The seasonal and spatial variability of water quality, including mercury species, was evaluated in agricultural and managed, non-agricultural wetlands in the Yolo Bypass Wildlife Area, an area managed for multiple beneficial uses including bird habitat and rice farming. The study was conducted during an 11-month period (June 2007 to April 2008) that included a summer growing season and flooded conditions during winter. Methylmercury (MeHg) concentrations in surface water varied over a wide range (0.1 to 37 ng L-1 unfiltered; 0.04 to 7.3 ng L-1 filtered). Maximum MeHg values are among the highest ever recorded in wetlands. Highest MeHg concentrations in unfiltered surface water were observed in drainage from wild rice fields during harvest (September 2007), and in white rice fields with decomposing rice straw during regional flooding (February 2008). The ratio of MeNg to total mercury (MeHg/Mg) increased about 20-fold in both unfiltered and filtered water during the growing season (June to August 2007) in the white and wild rice fields, and about 5-fold in fallow fields (July to August 2007), while there was little to no change in MeHg/THg in the permanent wetland. Sulfate-bearing fertilizer had no effect on Hg(II) methylation, as sulfate-reducing bacteria were not sulfate-limited in these agricultural wetlands. Concentrations of MeHg in filtered and unfiltered water correlated with filtered Fe, filtered Mn, DOC, and two indicators of sulfate reduction: the SO42-/Cl- ratio, and delta S-34 in aqueous sulfate. These relationships suggest that microbial reduction of SO42-, Fe(III), and possibly Mn(IV) may contribute to net Hg(II)-methylation in this setting. Published by Elsevier B.V.