A mass budget for mercury and methylmercury in the Arctic Ocean
A mass budget for mercury and methylmercury in the Arctic Ocean
复制标题
DOI：
10.1002/2015gb005280
复制
发表时间：
2016-04-01
影响因子：
5.2
通讯作者：
Sunderland, Elsie M.
中科院分区：
文献类型：
--
作者：
Soerensen, Anne L.;Jacob, Daniel J.;Sunderland, Elsie M.
在整个北冰洋都观察到甲基汞（一种生物累积性神经毒素）的生物浓度升高，但对海水中的主要来源和降解途径还没有很好的了解。我们制定了大量的预算汞物种在北冰洋自2004年以来的现有数据的基础上，并讨论的影响和不确定性。我们的计算表明，北极海水中总汞（Hg）相对于其他流域的高反映了大量的淡水输入和海冰覆盖，抑制了通过逃避损失。我们发现大部分甲基汞的净产量（20 Mga（-1））发生在次表层海洋（20- 200米）。在那里，它被转化为二甲基汞（Me 2 Hg：17 Mga（-1）），扩散到极性混合层并逃逸到大气中（14 Mga（-1））。Me 2 Hg在大气中的寿命很短，很快就会降解回MeHg。我们假设，大多数逃避Me 2 Hg再沉积为甲基汞和大气沉积是最大的净甲基汞源（8 Mga（-1））的生物生产的表面海洋。与低纬度地区相比，北冰洋海水中的甲基汞浓度较高。河流输入的甲基汞约占海洋表面输入量的15%（2.5Mga（-1）），但由于淡水排放量和永久冻土融化量的增加，未来可能会更加重要。这可能会抵消因逃避无冰表面沃茨而导致的潜在下降。地球化学模型模拟表明，对于海洋中与生物最相关的区域，减少汞输入的监管行动有能力迅速影响水生汞浓度。
Elevated biological concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, are observed throughout the Arctic Ocean, but major sources and degradation pathways in seawater are not well understood. We develop a mass budget for mercury species in the Arctic Ocean based on available data since 2004 and discuss implications and uncertainties. Our calculations show that high total mercury (Hg) in Arctic seawater relative to other basins reflect large freshwater inputs and sea ice cover that inhibits losses through evasion. We find that most net MeHg production (20Mga(-1)) occurs in the subsurface ocean (20-200m). There it is converted to dimethylmercury (Me2Hg: 17Mga(-1)), which diffuses to the polar mixed layer and evades to the atmosphere (14Mga(-1)). Me2Hg has a short atmospheric lifetime and rapidly degrades back to MeHg. We postulate that most evaded Me2Hg is redeposited as MeHg and that atmospheric deposition is the largest net MeHg source (8Mga(-1)) to the biologically productive surface ocean. MeHg concentrations in Arctic Ocean seawater are elevated compared to lower latitudes. Riverine MeHg inputs account for approximately 15% of inputs to the surface ocean (2.5Mga(-1)) but greater importance in the future is likely given increasing freshwater discharges and permafrost melt. This may offset potential declines driven by increasing evasion from ice-free surface waters. Geochemical model simulations illustrate that for the most biologically relevant regions of the ocean, regulatory actions that decrease Hg inputs have the capacity to rapidly affect aquatic Hg concentrations.