A mesocosm experiment on methyl mercury formation after cappingof U-864 sediments enriched with powdered algae

GSTDTAP > 气候变化

	A mesocosm experiment on methyl mercury formation after cappingof U-864 sediments enriched with powdered algae
	Ndungu, Kuria; Schaanning, Morten
	2015
出版年	2015
语种	英语
国家	挪威
出版者	Norsk institutt for vannforskning
领域	气候变化
英文摘要	A mesocosm experiment was performed on methylation of mercury in marine sediments from the wreck site at Fedje. The mercury contaminated sediment was enriched with zero, low, medium or high dose of labile organic carbon from pulverized algae and either capped with a thin layer of clay or left uncapped exposed to the seawater flowing through the mesocosm. The small fraction of methyl mercury (MeHg) of 0,006% of the total concentration (TotHg) in the batch of sediment shipped form Fedje indicated that in situ methylation at the wreck site is low. In the boxcosms, no significant methylation was observed in sediments with no addition of algae. In the low dose treatment, initial methylation rates were found to be 0.2-0,3 ng MeHg m-2 day-1, but the process ceased after the first month, presumably due to depletion of the reservoir of available algae carbon added. In medium and high dose treatments the process proceeded throughout the experimental period at apparently constant rates proportional with the amount of algae added. Methylation was observed in both capped and uncapped Fedje sediments, but the highest rates of methylation were observed in the capped sediments, in which up to 0.6 ng m-2 day-1 of methyl mercury (MeHg) accumulated during the six months experimental period. Fluxes of TotHg and MeHg to the seawater were only measured in the uncapped sediments. High fluxes were observed in all treatments. The six months median fluxes showed a four-fold increase of TotHg from zero to high algae addition, whereas the corresponding fluxes of MeHg increased 100x from 0,97 to 94.1 ng MeHg m-2 day-1. The flux of MeHg could only account for a small fraction (in general less than 10% of the total flux) indicating the formation of soluble organic complexes other than MeHg. A more long-term experiment using petrogenic hydrocarbons is recommended to improve assessment of the risks of Hg methylation at Fedje and at Hg-contaminated wreck sites in general.
英文关键词	VDP::Matematikk og naturvitenskap: 400 VDP::Mathematics and natural scienses: 400 Effekt av tildekking / Effect of capping Mesocosmos / Mesocosm Metylkvikksølv / Methylmercury Sediment / Sediment
URL	查看原文
来源平台	Center for International Climate and Environmental Research-Oslo (CICERO)
文献类型	科技报告
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/2012
专题	气候变化
推荐引用方式 GB/T 7714	Ndungu, Kuria,Schaanning, Morten. A mesocosm experiment on methyl mercury formation after cappingof U-864 sediments enriched with powdered algae:Norsk institutt for vannforskning,2015.