Ambio ( IF 5.8 ) Pub Date : 2022-06-23 , DOI: 10.1007/s13280-022-01738-8 Carl Rolff 1 , Jakob Walve 2 , Ulf Larsson 2 , Ragnar Elmgren 2
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Abstract
Even large inflows of oxygen-rich seawater to the Baltic Proper have in recent decades given only short-lived relief from oxygen deficiency below the halocline. We analyse long-term changes in oxygen deficiency, and calculate the “total oxygen debt” \(\Sigma\) OD, the oxygen required to oxidize the hydrogen sulphide (H2S) and ammonium (NH4) that builds up during stagnation periods. Since the early 1990s, oxygen below 65m has gradually decreased during successive stagnation periods, and the \(\Sigma\) OD has increased, with NH4 more important than previously recognised. After the major inflow in 2014, the Baltic Proper \(\Sigma\) OD has reached its highest level so far. The gradual shift of the \(\Sigma\) OD to shallower sub-halocline waters in the western and northern basins has increased the risk of periodic coastal hypoxia and export of hypoxic water to the Bothnian Sea. The potential for inflows large enough to more than eliminate the \(\Sigma\) OD seems limited in the near term.
中文翻译：
波罗的海缺氧如何蔓延和恶化：铵和硫化氢的作用
摘要
近几十年来，即使是大量富氧海水流入波罗的海，也只是短暂缓解了盐弧线以下的缺氧问题。我们分析缺氧的长期变化，并计算“总氧债” \(\Sigma\) OD，即氧化停滞期间积累的硫化氢 (H 2 S) 和铵 (NH 4 ) 所需的氧气期间。自 1990 年代初以来，65m 以下的氧气在连续停滞期间逐渐减少，\(\Sigma\) OD 增加，其中 NH 4比以前认识到的更为重要。在 2014 年的主要流入之后，波罗的海专有\(\Sigma\) OD 达到了迄今为止的最高水平。在西部和北部盆地， \(\Sigma\) OD 逐渐向较浅的亚盐卤水转移，增加了沿海周期性缺氧和缺氧水向波的尼亚海输出的风险。流入量大到足以消除\(\Sigma\) OD 的潜力在短期内似乎有限。
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