Department of Integrated Science and Technology, James Madison University, Harrisonburg, VA, 22807, USA,
Arch Environ Contam Toxicol. 2014 Feb;66(2):201-12. doi: 10.1007/s00244-013-9964-7. Epub 2013 Nov 20.
Mercury is a globally distributed pollutant that biomagnifies in aquatic food webs. In the United States, 4,769 water bodies fail to meet criteria for safe fish consumption due to mercury bioaccumulation. Although the majority of these water bodies are affected primarily by atmospheric deposition of mercury, legacy contamination from mining or industrial activities also contribute to fish consumption advisories for mercury. The largest mercury impairment in Virginia, a 130-mile stretch of the South and South Fork Shenandoah rivers, is posted with a fish-consumption advisory for mercury contamination that originated from mercuric sulfate discharges from a textile facility in Waynesboro, Virginia, between 1929 and 1950. Although discharges of mercury to the river ceased >60 years ago, mercury levels in fish remain greater than levels safe for human consumption. This is due to the continued cycling of historic mercury in the river and its eventual uptake and biomagnification through aquatic food webs. This study investigated the relative importance of waterborne versus sediment-borne mercury in controlling biological uptake of mercury into the aquatic food web. Twelve artificial stream channels were constructed along the contaminated South River in Crimora, Virginia, and the uncontaminated North River in nearby Port Republic, Virginia, to provide four experimental treatments: a control with no Hg exposure, a Hg in sediment exposure, a Hg in water exposure, and a Hg in sediment and water exposure. After 6 weeks of colonization and growth, algae in each treatment was collected and measured for mercury accumulation. Mercury accumulation in water-only exposures was four times greater than in sediment-only exposures and was equivalent to accumulation in treatments with combined water and sediment exposure. This indicates that mercury in the water column is much more important in controlling biological uptake than mercury in near-field sediments. As a result, future remediation efforts need to focus on strategies that either remove mercury from the water column or decrease flux to the water column.
汞是一种在全球范围内分布的污染物，在水生食物链中具有生物放大作用。在美国，由于汞的生物累积，有 4769 个水体未能达到安全鱼类消费标准。尽管这些水体中的大多数主要受到大气汞沉积的影响，但来自采矿或工业活动的遗留污染也导致了鱼类消费中对汞的警告。弗吉尼亚州最大的汞污染是南叉和南叉谢南多厄河的 130 英里河段，该地区由于弗吉尼亚州韦恩斯伯勒的一家纺织厂从 1929 年到 1950 年期间排放硫酸汞，鱼类消费受到汞污染的警告。尽管向河流排放汞的行为已经停止了 60 多年，但鱼类中的汞含量仍然超过了人类食用的安全水平。这是由于河流中历史汞的持续循环以及它最终通过水生食物链被吸收和生物放大。本研究调查了控制汞进入水生食物链的生物吸收过程中，水载汞和底泥载汞的相对重要性。在弗吉尼亚州克里莫拉受污染的南叉河和附近的波因特共和国的未受污染的北叉河沿线建造了 12 个人工溪流通道，提供了四种实验处理：无 Hg 暴露的对照、底泥 Hg 暴露、水 Hg 暴露和底泥和水 Hg 暴露。经过 6 周的殖民和生长，收集并测量了每个处理组的藻类中的汞积累量。仅在水中暴露的汞积累量是仅在底泥中暴露的四倍，与水和底泥联合暴露的处理中的积累量相当。这表明，与近场底泥中的汞相比，水柱中的汞在控制生物吸收方面更为重要。因此，未来的修复工作需要集中精力制定策略，要么从水柱中去除汞，要么减少向水柱中的通量。
