Gaseous elemental mercury (Hg⁰) concentrations in the atmosphere have been increasing due to anthropogenic activities since the onset of colonial mining in the 17th century. However, accurate measurements of atmospheric Hg, including temporal trends, are mostly limited to recent decades. Natural environmental archives including tree rings show promise for reconstructing atmospheric concentrations of Hg⁰. In this paper, we present a new white spruce (Picea glauca) tree-ring Hg record (1696–2005) from the Old Crow Flats in northern Yukon. The record we present shows an increase in tree-ring Hg concentration (a proxy for gaseous Hg⁰ concentration) between 1748 and 1990 at a rate of +3.3% per year. A decrease in measured Hg is observed at the end of the record between 1990 and 2005, which may reflect the success of international regulations to reduce emissions including Hg. When compared with two other sites (a continental and marine location) in northwest Canada, there is not only some coherence in Hg trends at the regional scale but also some unique differences, suggesting that the location may influence atmospheric Hg⁰ available for assimilation. Further local factors within a site, such as soil moisture, may also affect the efficiency of this uptake. Results from this study highlight the need to better understand intra-site and inter-site differences in measured tree-ring Hg, and we recommend the continued development of a spatially resolved tree-ring Hg network in the northern boreal forest. Such records will be useful for developing better atmospheric Hg and global Hg models.

中文翻译：

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加拿大育空地区旧乌鸦屋中受大陆和海洋影响的树环汞记录

自17世纪开始殖民开采以来，由于人为活动，大气中的气态汞（Hg ⁰）浓度一直在增加。但是，大气汞的精确测量（包括时间趋势）主要限于最近几十年。包括树木年轮在内的自然环境档案显示，有望重建Hg ^0的大气浓度。在本文中，我们提出了育空北部旧乌鸦屋的新白云杉（Picea glauca）树年轮汞记录（1696–2005）。我们目前的记录显示树木年轮中的汞浓度增加（气态汞⁰的替代物1748年至1990年之间，每年的增长率为+ 3.3％。1990年至2005年的记录结束时，测得的Hg减少了，这可能反映了国际法规在减少包括Hg在内的排放方面的成功。与加拿大西北部的其他两个地点（大陆和海洋位置）相比，区域范围内的汞趋势不仅具有连贯性，而且还存在一些独特的差异，表明该位置可能会影响大气中的汞⁰可同化。场地内的其他局部因素（例如土壤湿度）也可能影响这种吸收的效率。这项研究的结果表明，需要更好地了解测得的树木年轮汞的站点内和站点间差异，我们建议在北方北方森林中继续发展空间分解的树木年轮汞网络。这样的记录将有助于开发更好的大气汞和全球汞模型。