The strongest evidence for anthropogenic alterations to the global mercury (Hg) cycle comes from historical records of mercury deposition preserved in lake sediments. Hg isotopes have added a new dimension to these sedimentary archives, promising additional insights into Hg source apportionment and biogeochemical processing. Presently, most interpretations of historical changes are constrained to a small number of locally contaminated ecosystems. Here, we describe changes in natural Hg isotope records from a suite of dated sediment cores collected from various remote lakes of North America. In nearly all cases, the rise in industrial-use Hg is accompanied by an increase in δ²⁰²Hg and Δ¹⁹⁹Hg values. These trends can be attributed to large-scale industrial emission of Hg into the atmosphere and are consistent with positive Δ¹⁹⁹Hg values measured in modern-day precipitation and modeled increases in δ²⁰²Hg values from global emission inventories. Despite similar temporal trends among cores, the baseline isotopic values vary considerably among the different study regions, likely attributable to differences in the fractionation produced in situ as well as differing amounts of atmospherically delivered Hg. Differences among the study lakes in precipitation and watershed size provide an empirical framework for evaluating Hg isotopic signatures and global Hg cycling.

中文翻译：

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从遥远的北美湖泊沉积物的同位素记录解析大气汞负荷和源趋势。

人为改变全球汞 (Hg) 循环的最有力证据来自湖泊沉积物中保存的汞沉积的历史记录。汞同位素为这些沉积档案增加了一个新的维度，有望进一步了解汞的来源分配和生物地球化学处理。目前，对历史变化的大多数解释仅限于少数当地受污染的生态系统。在这里，我们描述了从北美各个偏远湖泊收集的一套年代久远的沉积岩芯中天然汞同位素记录的变化。在几乎所有情况下，工业用汞的增加都伴随着 δ ²⁰² Hg 和 Δ ^{199 的增加}汞值。这些趋势可归因于汞向大气中的大规模工业排放，并且与现代降水中测量的正 Δ ¹⁹⁹ Hg 值和全球排放清单中模拟的 δ ²⁰² Hg 值增加一致。尽管岩心之间的时间趋势相似，但不同研究区域的基线同位素值差异很大，这可能归因于原位产生的分馏差异以及大气输送的汞含量不同。研究湖泊在降水和流域大小方面的差异为评估汞同位素特征和全球汞循环提供了经验框架。