Institute of General Ecology and Environmental Protection, Technische Universität Dresden, PF 1117, 01737, Tharandt, Germany.
Environ Sci Pollut Res Int. 2012 Nov;19(9):3942-9. doi: 10.1007/s11356-012-0975-0. Epub 2012 May 29.
Plant litter and organic sediments are a main sink for metals and metalloids in aquatic ecosystems. The effect of invertebrate shredder (a key species in litter decay) on metal/metalloid fixation by organic matter is described only under alkaline water conditions whereas for slightly acidic waters nothing can be found. Furthermore, less is known about the effect of invertebrate shredders on the quality of dissolved organic carbon (DOC) and nitrogen (DON) released during litter decay. We conducted an experiment to investigate the impact of invertebrate shredder (Gammarus pulex) on metal/metalloid fixation/remobilization and on the quality of DOC/DON released under slightly acidic water conditions. During decomposition of leaf litter, invertebrate shredder facilitated significantly the emergence of smaller particle sizes of organic matter. The capacity of metal fixation was significantly higher in smaller particles (POM 2,000-63 μm) compared to original leaf litter and litter residues. Thus, G. pulex enhanced metal fixation by organic partition of sediments by increasing the amount of smaller particle of organic matter in aquatic ecosystems. In contrast, the capacity of metal/metalloid fixation in the smallest fraction of POM (<63 μm) was lower compared with leaf residues in treatment without invertebrates. Remobilization of metals and metalloids was very low for all measured elements. A significant effect of invertebrates on quantitative formation of DOC/DON was confirmed. The quality of released DOC/DON, which may affect metal/metalloid remobilization, was also significantly affected by invertebrate shredders (e.g., more carboxylates). Hence, invertebrate shredder enhanced significantly the fixation of metals/metalloids into POM in slightly acidic environments.
植物凋落物和有机沉积物是水生生态系统中金属和类金属的主要汇。只有在碱性水条件下，才描述了无脊椎动物碎屑分解者（凋落物分解的关键物种）对有机物固定金属/类金属的影响，而对于略酸性的水则没有任何相关信息。此外，对于无脊椎动物碎屑分解者对凋落物分解过程中释放的溶解有机碳（DOC）和氮（DON）质量的影响知之甚少。我们进行了一项实验，以研究无脊椎动物碎屑分解者（食蚊鱼）在略酸性水环境下对金属/类金属固定/再移动以及释放的 DOC/DON 质量的影响。在叶片凋落物分解过程中，无脊椎动物碎屑分解者显著促进了较小粒径有机物的出现。与原始叶片凋落物和凋落物残余物相比，较小颗粒（POM 2,000-63 μm）中金属固定的能力显著更高。因此，食蚊鱼通过增加生态系统中小颗粒有机物的数量，增强了金属通过有机分配在沉积物中的固定。相比之下，在没有无脊椎动物的处理中，最小 POM （<63 μm）分数中的金属/类金属固定能力低于叶片残渣。所有测量元素的金属和类金属再移动都非常低。证实了无脊椎动物对 DOC/DON 定量形成有显著影响。释放的 DOC/DON 的质量（可能会影响金属/类金属的再移动）也受到无脊椎动物碎屑分解者的显著影响（例如，更多的羧酸根）。因此，在略酸性环境中，无脊椎动物碎屑分解者显著增强了金属/类金属在 POM 中的固定。
