Ecol Appl. 2014 Jun;24(4):812-22. doi: 10.1890/13-0212.1.
Terrestrial soil is a large reservoir of atmospherically deposited mercury (Hg). However, few studies have evaluated the accumulation of Hg in terrestrial ecosystems in the northeastern United States, a region which is sensitive to atmospheric Hg deposition. We characterized Hg and organic matter in soil profiles from 139 sampling sites for five subregions across the northeastern United States and estimated atmospheric Hg deposition to these sites by combining numerical modeling with experimental data from the literature. We did not observe any significant relationships between current net atmospheric Hg deposition and soil Hg concentrations or pools, even though soils are a net sink for Hg inputs. Soil Hg appears to be preserved relative to organic carbon (OC) and/or nitrogen (N) in the soil matrix, as a significant negative relationship was observed between the ratios of Hg/OC and OC/N (r = 0.54, P < 0.0001) that shapes the horizonal distribution patterns. We estimated that atmospheric Hg deposition since 1850 (3.97 mg/m2) accounts for 102% of the Hg pool in the organic horizons (3.88 mg/m2) and 19% of the total soil Hg pool (21.32 mg/m2), except for the southern New England (SNE) subregion. The mean residence time for soil Hg was estimated to be 1800 years, except SNE which was 800 years. These patterns suggest that in addition to atmospheric deposition, the accumulation of soil Hg is linked to the mineral diagenetic and soil development processes in the region.
陆地土壤是大气中沉积汞 (Hg) 的巨大储库。然而，很少有研究评估过美国东北部陆地生态系统中汞的积累，该地区对大气汞沉积敏感。我们对美国东北部五个地区的 139 个采样点的土壤剖面中的汞和有机质进行了特征描述，并通过数值模拟与文献中的实验数据相结合，估算了这些地点的大气汞沉积量。尽管土壤是汞输入的净汇，但我们没有观察到当前净大气汞沉积与土壤汞浓度或汞库之间存在任何显著关系。土壤汞相对于土壤基质中的有机碳 (OC) 和/或氮 (N) 似乎被保存下来，因为观察到 Hg/OC 和 OC/N 比值之间存在显著的负相关关系 (r = 0.54, P < 0.0001)，这塑造了水平分布模式。我们估计，自 1850 年以来的大气汞沉积 (3.97 mg/m2) 占有机层 (3.88 mg/m2) 中汞库的 102%和总土壤汞库 (21.32 mg/m2) 的 19%，除了新英格兰南部 (SNE) 地区。土壤汞的平均停留时间估计为 1800 年，除了 SNE 地区为 800 年。这些模式表明，除了大气沉积外，土壤汞的积累还与该地区的矿物成岩和土壤发育过程有关。
