Iron: Studies on the speciation and bioavailavility in the Baltic Sea

铁：波罗的海的形态和生物利用度研究

• 批准号: 47755900
• 负责人: Dr. Christa Pohl (†)
• 金额: --
• 依托单位: Leibniz-Institut für Ostseeforschung Warnemünde (IOW)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/47755900?language=en
• 关键词: Iron; Studies; speciation; bioavailavility; Baltic

The Baltic Sea is affected by anthropogenic and natural trace metals via atmospheric- and riverine input. The marine biogeochemical cycles and food webs respond to the addition of micronutrients to the marine environment. Entering the surface waters, the transport of trace metals is closely linked to the seasonal variation of the biological production and modification processes. In seawater Fe (Iron) belongs to the most important micronutrients. It mainly exists as organically complexed species, as insoluble Fe (III) species (oxy / hydroxyl) and to a lesser extent as dissolved Fe (II) species in ocean surface waters These Fe complexes are mostly removed from the euphotic zone by adsorption on or incorporation into particles and the transport through the water column. They are known to accumulated at horizontal interfaces / boundaries such as the pycnocline, the OMZ (oxygen minimum zone) or the redox boundary because of slow sinking rates. Redox interfaces with stagnant deep water bodies are typical for the central Baltic. Fe belongs to the redox-sensitive elements, which means that under anoxic conditions insoluble Fe(III) species are reduced to dissolved Fe(II) species. Together with phosphorus the Fe (II) species built up a soluble compound which is kinetically convenient. This is the reason for the increasing dissolved Fe(II) concentrations in the Baltic below the redoxcline. In the deeper anoxic layers dissolved Fe concentrations are decreasing because of the formation of the thermodynamically more stable compound Fe (II) sulphide, which equilibrates the soluble species. Parallel to the enrichment of insoluble FeS in the bottom sediments, there is a diffusive transport flux of dissolved Fe(II) spezies across the redoxcline in 150m depth. Fe catalyses the uptake of nitrogen in nitrogen fixing cyanobacteria. In this context it has been assumed, that dissolved Fe(II) is the more bioavailable species for the uptake during cyanobacteria growth. This leads to the main question: “Is Iron a limiting or a promoting factor of cyanobacteria blooms in the Baltic Sea?” Therefore this project should combine how far the formation of stagnant deepwater up to anoxic conditions, the resulting change of Fe Speciation (reduction to Fe(II)) and the diffusive Fe(II) transport to the euphotic zone are responsible for the fertilisation and the increase of cyanobacteria blooms?

波罗的海通过大气和河流输入受到人为和自然微量金属的影响。海洋生物地球化学循环和食物网对海洋环境中微量营养素的增加作出反应。进入表层沃茨的痕量金属的迁移与生物生产和改造过程的季节变化密切相关。Fe（铁）是海水中最重要的微量营养元素。在海洋表面沃茨中，Fe（III）主要以有机络合物、不溶性Fe（III）（氧/羟基）和少量溶解Fe（II）的形式存在。这些Fe络合物主要通过吸附在颗粒上或掺入颗粒中以及通过水柱的运输而从真光层中去除。由于下沉速率缓慢，已知它们在水平界面/边界处积累，例如密度跃层、OMZ（氧气最小区）或氧化还原边界。与停滞的深水体的氧化还原界面是典型的波罗的海中部。Fe属于氧化还原敏感元素，这意味着在缺氧条件下，不溶性Fe（III）物质被还原为溶解的Fe（II）物质。与磷一起，Fe（II）物种形成了动力学上方便的可溶性化合物。这就是在波罗的海氧化还原跃层以下溶解的Fe（II）浓度增加的原因。在更深的缺氧层溶解铁浓度下降，因为形成的结晶更稳定的化合物Fe（II）硫化物，平衡的可溶性物种。在150 m深度，溶解态Fe（II）物种在氧化还原跃层中的扩散输运通量与底层沉积物中不溶性FeS的富集平行。铁催化固氮蓝藻对氮的吸收。在这种情况下，它已被假定，溶解的Fe（II）是更多的生物可利用的物种在蓝藻生长过程中的摄取。这就引出了一个主要问题：“铁是波罗的海蓝藻水华的限制因素还是促进因素？”因此，本项目应结合联合收割机，确定停滞深水的形成到缺氧条件的程度、由此产生的Fe形态变化（还原为Fe（II））以及Fe（II）向真光层的扩散运输对施肥和蓝藻水华的增加有多大影响？

项目成果

An estimate of the efficiency of the iron‐ and manganese‐driven dissolved inorganic phosphorus trap at an oxic/euxinic water column redoxcline

含氧/低氧水柱氧化还原酶中铁和锰驱动的溶解无机磷捕集器的效率估计

• DOI: 10.1029/2010gb003820
• 发表时间: 2010
• 期刊: Global Biogeochemical Cycles
• 影响因子: 5.2
• 作者: Turnewitsch