Remote Northern Hemisphere (NH) and Southern Hemisphere (SH) lake sediment and peat records of mercury (Hg) deposition have shown a ×3 to ×5 Hg enrichment since pre-industrial times (<1880 AD), leading to the perception that global atmospheric Hg enrichment is moderate and uniform across the hemispheres. Anthropogenic Hg emissions in the NH are, however, approximately 4 times higher than those in the SH. Here, we reconstruct atmospheric Hg deposition in four remote SH peatlands and review sediment and peat Hg records from both hemispheres. We observe a ×4 all-time enrichment in SH Hg deposition from pre-anthropogenic (<1450 AD) to the late 20th-century periods, which is lower than the large ×16 all-time enrichment in NH Hg deposition. We attribute this difference to lower anthropogenic Hg emissions in the SH, and higher natural atmospheric SH Hg concentrations, supported by ×2 higher natural background Hg accumulation in SH peat records. We suggest that the higher SH natural atmospheric Hg deposition reflects the SH land–ocean distribution, and is driven by important SH marine Hg emissions. Our findings indicate that atmospheric Hg background levels and anthropogenic enrichment in both hemispheres are different and should be taken into account in international Hg assessments and environmental policy.

中文翻译：

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地球北半球和南半球中不当的人为汞富集

自工业化之前（公元1880年）以来，偏远的北半球（NH）和南半球（SH）的湖泊沉积物和汞（Hg）沉积的泥炭记录显示，Hg的富集度为×3至×5。大气中Hg的富集在整个半球是中等且均匀的。但是，NH中人为的Hg排放量比SH中的人为排放量高约4倍。在这里，我们重建了四个偏远的SH泥炭地的大气汞沉积，并审查了两个半球的沉积物和泥炭汞记录。我们观察到从人为前（<1450 AD）到20世纪后期，SH Hg沉积物的历史富集率为×4，低于NH Hg沉积物的大型×16历时富集。我们将此差异归因于上海的人为汞排放降低，SH泥炭记录中的自然背景Hg积累增加了2倍，从而支持了更高的自然大气SH Hg浓度。我们建议，较高的天然SH自然大气汞沉积反映出SH陆地-海洋的分布，并且是由重要的SH海洋Hg排放驱动的。我们的发现表明，两个半球的大气汞背景水平和人为富集程度不同，在国际汞评估和环境政策中应予以考虑。