Linn G. Speidel, Roger Carvalho da Silva, Melanie Beck, Olaf Dellwig, Jochen Wollschläger, Thorsten Dittmar, Michael Seidel
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引用次数: 0
Abstract
The German Bight in the southern North Sea receives nutrients, dissolved organic matter (DOM), and trace metals from rivers, porewater reflux, and porewater outwelling. We studied the marine, riverine, and porewater sources analyzing molecular transformations of solid-phase extracted (SPE) DOM in the German Bight. We applied a combination of ultrahigh-resolution mass spectrometry (FT-ICR-MS) with quantitative data of dissolved organic sulfur (DOS), dissolved black carbon (DBC), dissolved trace metals (Ba, Co, Gd, Mo, Mn, W), and nutrients (nitrite, nitrate, phosphate, silicate). While aromatic DOM and DBC mainly originated from the rivers, nitrogen-containing, more saturated DOM was enriched offshore suggesting greater contributions of marine (algal) sources. Except for dissolved Mo, rivers were the primary source of trace metals and nutrients. However, tidal flats contributed to dissolved nutrient (e.g., dissolved phosphate), trace metal and DOS inventories of the southern North Sea. The input of DOS from intertidal flats was identified by the molecular index derived from sulfidic porewaters (ISuP), non-conservative behavior of elemental sulfur-to-carbon ratio and sulfur content of molecular formulae (from FT-ICR-MS). Dissolved Mn and Si were removed in the German Bight, likely due to precipitation as Mn(hydr)oxides and biological uptake, respectively. Preliminary estimates suggest that DOS from porewater outwelling is approximately four times higher than DOS discharged by the three main rivers in the region. Our study therefore highlights the need to consider porewater discharge in addition to riverine sources to comprehensively assess elemental budgets within the complex interplay and transformations of DOM, nutrients, and trace metals in coastal ecosystems.
北海南部的德国港湾从河流、孔隙水回流和孔隙水外流中获取营养物质、溶解有机物(DOM)和痕量金属。我们研究了海洋、河流和孔隙水的来源,分析了德国港湾固相萃取(SPE)DOM 的分子转化。我们将超高分辨率质谱法(FT-ICR-MS)与溶解有机硫(DOS)、溶解黑碳(DBC)、溶解痕量金属(钡、钴、钆、钼、锰、钨)和营养物质(亚硝酸盐、硝酸盐、磷酸盐、硅酸盐)的定量数据相结合。芳香族 DOM 和 DBC 主要来源于河流,而含氮、饱和度更高的 DOM 则富集于近海,这表明海洋(藻类)来源的贡献更大。除溶解态 Mo 外,河流是痕量金属和营养物质的主要来源。不过,北海南部的溶解营养物(如溶解磷酸盐)、痕量金属和 DOS 库存也有潮汐滩涂的贡献。潮间带滩涂的 DOS 输入量是通过硫化孔隙水(ISuP)得出的分子指数、元素硫碳比的非保守行为和分子式中的硫含量(来自 FT-ICR-MS)确定的。在德国湾,溶解的锰和硅被去除,可能分别是由于锰(氢)氧化物沉淀和生物吸收。初步估计表明,孔隙水外流的 DOS 约为该地区三条主要河流排放的 DOS 的四倍。因此,我们的研究强调,在全面评估沿岸生态系统中 DOM、营养盐和痕量金属复杂的相互作用和转化过程中的元素预算时,除了考虑河 流来源外,还需要考虑孔隙水排放。
期刊介绍:
Biogeochemistry publishes original and synthetic papers dealing with biotic controls on the chemistry of the environment, or with the geochemical control of the structure and function of ecosystems. Cycles are considered, either of individual elements or of specific classes of natural or anthropogenic compounds in ecosystems. Particular emphasis is given to coupled interactions of element cycles. The journal spans from the molecular to global scales to elucidate the mechanisms driving patterns in biogeochemical cycles through space and time. Studies on both natural and artificial ecosystems are published when they contribute to a general understanding of biogeochemistry.