Abstract
The study of mercury accumulation in peat cores provides an excellent opportunity to improve the knowledge on mercury cycling and depositional processes at remote locations far from pollution sources. We analyzed mercury concentrations in 150 peat samples from two cores from Rano Aroi (Easter Island, 27° S) and in selected vegetation samples of present-day flora of the island, in order to characterize the mercury cycling for the last ~71 ka BP. The mercury concentrations showed values ranging between 35 and 200 ng g−1, except for a large maxima (~1000 ng g−1) which occurred at the end of the Last Glacial Maximum (LGM, ~20 ka cal BP) in both peat cores. Low temperatures during the LGM would accelerate the atmospheric oxidation of Hg(0) to divalent mercury that, coupled with higher rainfall during this period, most likely resulted in a very efficient surface deposition of atmospheric mercury. Two exceptional short-lived Hg peaks occurred during the Holocene at 8.5 (350 ng g−1) and 4.7 (1000 ng g−1) ka cal BP. These values are higher than those recorded in most peat records belonging to the industrial period, highlighting that natural factors played a significant role in Hg accumulation—sometimes even more so than anthropogenic sources. Our results suggest that wet deposition, linked to atmospheric oxidation, was the main process controlling the short-lived Hg events, both in the mire and in the catchment soils.
Funder
Ministerio de Ciencia y Tecnología
Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia
Subject
General Earth and Planetary Sciences
Cited by
9 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献