Yale Environment School, 195 Prospect Street, New Haven, CT 06511.
Mar Pollut Bull. 2018 Jan;126:535-539. doi: 10.1016/j.marpolbul.2017.09.056. Epub 2017 Sep 29.
We collected seven cores from five coastal ponds in St Thomas, USVI, dated them via Pb, and measured their Hg profiles. Levels ranged from 20 to 100ngg and always increased upward to the surface or a shallow mixed zone. Taking into account differences in sediment accumulation rates and the presence or absence of a mixed zone, all sites revealed similar deposition histories. Mercury levels were at low, possibly pristine, values until the early to mid-20 century. Then they then doubled or quadrupled steadily until about 1990, after which Hg became relatively constant. We conclude that Hg in the sediments of these ponds came from long range deposition directly to the ponds and to their watersheds. Constant levels in recent years may be caused by transfer from watersheds, a pathway that is delayed compared to direct deposition from the atmosphere.
我们从美属维尔京群岛圣托马斯的五个沿海池塘中采集了七个岩芯，通过 Pb 进行了定年，并测量了它们的 Hg 分布。Hg 浓度范围为 20 到 100ngg，且总是向上增加至表层或浅层混合区。考虑到沉积速率的差异以及混合区的存在与否，所有地点都揭示了相似的沉积历史。Hg 水平在 20 世纪初之前一直处于低水平，可能处于原始状态。然后，它们稳定地增加了一倍或四倍，直到 1990 年左右，之后 Hg 变得相对稳定。我们得出结论，这些池塘沉积物中的 Hg 来自长距离直接沉积到池塘及其流域。近年来 Hg 浓度的稳定可能是由于从流域转移所致，与大气直接沉积相比，这种途径存在延迟。
