Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark,
Ambio. 2014 Feb;43(1):26-36. doi: 10.1007/s13280-013-0474-7.
Hypoxia has occurred intermittently over the Holocene in the Baltic Sea, but the recent expansion from less than 10 000 km(2) before 1950 to >60 000 km(2) since 2000 is mainly caused by enhanced nutrient inputs from land and atmosphere. With worsening hypoxia, the role of sediments changes from nitrogen removal to nitrogen release as ammonium. At present, denitrification in the water column and sediments is equally important. Phosphorus is currently buried in sediments mainly in organic form, with an additional contribution of reduced Fe-phosphate minerals in the deep anoxic basins. Upon the transition to oxic conditions, a significant proportion of the organic phosphorus will be remineralized, with the phosphorus then being bound to iron oxides. This iron-oxide bound phosphorus is readily released to the water column upon the onset of hypoxia again. Important ecosystems services carried out by the benthic fauna, including biogeochemical feedback-loops and biomass production, are also lost with hypoxia. The results provide quantitative knowledge of nutrient release and recycling processes under various environmental conditions in support of decision support tools underlying the Baltic Sea Action Plan.
全新世期间波罗的海间歇性出现缺氧现象，但最近的缺氧面积从 1950 年前的不足 10000 平方公里扩大到 2000 年后的 >60000 平方公里，主要是由于陆地和大气中营养物质输入的增加所致。随着缺氧情况的恶化，沉积物的作用从去除氮转变为释放铵态氮。目前，水柱和沉积物中的反硝化作用同样重要。磷目前主要以有机形式埋藏在沉积物中，在深缺氧盆地中还有一部分还原态的铁磷酸盐矿物。在向有氧条件转变时，相当一部分有机磷将被再矿化，然后与铁氧化物结合。一旦再次出现缺氧，这部分铁氧化物结合的磷就会很容易释放到水柱中。底栖动物进行的重要生态系统服务，包括生物地球化学反馈循环和生物量生产，也随着缺氧而丧失。这些结果提供了在各种环境条件下营养物质释放和循环过程的定量知识，为波罗的海行动计划的决策支持工具提供支持。
