Mercury Export to the Arctic Ocean from the Mackenzie River, Canada

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• 作者：Craig A. Emmerton ; Jennifer A. Graydon ; Jolie A. L. Gareis ; Vincent L. St. Louis ; Lance F. W. Lesack ; Janelle K. A. Banack ; Faye Hicks ; Jennifer Nafziger
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：July 16, 2013
• 年：2013
• 卷：47
• 期：14
• 页码：7644-7654
• 全文大小：622K
• 年卷期：v.47,no.14(July 16, 2013)
• ISSN：1520-5851

文摘

Circumpolar rivers, including the Mackenzie River in Canada, are sources of the contaminant mercury (Hg) to the Arctic Ocean, but few Hg export studies exist for these rivers. During the 2007鈥?010 freshet and open water seasons, we collected river water upstream and downstream of the Mackenzie River delta to quantify total mercury (THg) and methylmercury (MeHg) concentrations and export. Upstream of the delta, flow-weighted mean concentrations of bulk THg and MeHg were 14.6 卤 6.2 ng L^鈥? and 0.081 卤 0.045 ng L^鈥?, respectively. Only 11鈥?3% and 44鈥?1% of bulk THg and MeHg export was in the dissolved form. Using concentration鈥揹ischarge relationships, we calculated bulk THg and MeHg export into the delta of 2300鈥?200 kg yr^鈥? and 15鈥?3 kg yr^鈥? over the course of the study. Discharge is not presently known in channels exiting the delta, so we assessed differences in river Hg concentrations upstream and downstream of the delta to estimate its influence on Hg export to the ocean. Bulk THg and MeHg concentrations decreased 19% and 11% through the delta, likely because of particle settling and other processes in the floodplain. These results suggest that northern deltas may be important accumulators of river Hg in their floodplains before export to the Arctic Ocean.