Institute of Inorganic Chemistry, University of Vienna, Währingerstrasse 42, 1090 Vienna, Austria.
Sci Total Environ. 2010 May 1;408(11):2402-8. doi: 10.1016/j.scitotenv.2010.02.018. Epub 2010 Mar 5.
Peat bogs have the ability to produce strong chelate ligands (humic and fulvic acids) which enhance the weathering rates of iron-silicate minerals and greatly increase the solubility of the essential trace metal iron in river water. Fluvial networks link peat bogs with the ocean, and thus terrestrial-derived fulvic-iron complexes fuel the ocean's biological productivity and biological carbon pump, but understanding this role is constrained by inconsistent observations regarding the behaviour of riverine iron in the estuarine mixing zone, where precipitation reactions remove iron from the water column. We applied a characterization of the colloidal iron carriers in peatland-draining rivers in North Scotland, using field-flow fractionation (FFF), in combination with end-member mixing experiments of river water sampled near the river mouth and coastal seawater using a (59)Fe radiotracer method. According to our results, the investigated river contributed "truly dissolved" Fe concentrations of about 3300nmolL(-1) to the ocean which is nearly two orders of magnitude higher than the dissolved iron contribution of the "average world" river ( approximately 40nmolL(-1)). Thus we conclude that peatland-draining rivers are important sources of dissolved iron to the ocean margins. We propose highly electrostatic and sterical stabilized iron-organic matter complexes in the size range of <2kDa to be responsible for iron transport across the estuarine mixing zone.
泥炭沼泽具有产生强螯合配体（腐殖酸和富里酸）的能力，这些配体可增强铁硅酸盐矿物的风化速率，并极大地提高河水中必需痕量金属铁的溶解度。河流网络将泥炭沼泽与海洋连接起来，因此陆地衍生的富铁复合物为海洋的生物生产力和生物碳泵提供动力，但对河口混合区河流水体中铁的行为的不一致观测限制了对这一作用的理解，在河口混合区，沉淀反应会将铁从水柱中去除。我们使用野外流动分级（FFF）技术对苏格兰北部泥炭沼泽排水河流中的胶体铁载体进行了特征描述，并结合使用（59）Fe 放射性示踪剂方法对河口附近采集的河水和沿海海水进行端元混合实验。根据我们的研究结果，所研究的河流向海洋贡献了约 3300nmolL(-1)的“真正溶解”态铁，这几乎比“平均世界”河流（约 40nmolL(-1)）的溶解铁贡献高两个数量级。因此，我们得出结论，泥炭沼泽排水河流是海洋边缘溶解铁的重要来源。我们提出，在<2kDa 的范围内，具有高静电和空间稳定作用的铁-有机物质复合物负责在河口混合区进行铁运输。
