Technische Universität Dresden, D-01062 Dresden, Germany; Institute of General Ecology and Environmental Protection, Tharandt, Germany.
Chemosphere. 2013 Mar;90(10):2534-8. doi: 10.1016/j.chemosphere.2012.10.091. Epub 2012 Dec 8.
Organic matter is known to accumulate high amounts of metals/metalloids, enhanced during the process of decomposition by heterotrophic biofilms (with high fixation capacity for metals/metalloids). The colonization by microbes and the decay rate of the organic matter depends on different litter properties. Main litter properties affecting the decomposition of organic matter such as the nutrient ratios and the content of cellulose, lignin and phenols are currently described to be changed by silicon availability. But less is known about the impact of silicon availability during plant growth on elemental fixation during decay. Hence, this research focuses on the impact of silicon availability during plant growth on fixation of 42 elements during litter decay, by controlling the litter properties. The results of this experiment are a significantly higher metal/metalloid accumulation during decomposition of plant litter grown under low silicon availability. This may be explained by the altered litter properties (mainly nutrient content) affecting the microbial decomposition of the litter, the microbial growth on the litter and possibly by the silicon double layer, which is evident in leaf litter with high silicon content and reduces the binding sites for metals/metalloids. Furthermore, this silicon double layer may also reduce the growing biofilm by reducing the availability of carbon compounds at the litter surface and has to be elucidated in further research. Hence, low silicon availability during plant growth enhances the metal/metalloid accumulation into plant litter during aquatic decomposition.
有机物已知会积累大量的金属/类金属，在异养生物膜的分解过程中（对金属/类金属具有高固定能力）会增强。微生物的定殖和有机物的降解速率取决于不同的凋落物特性。目前，主要的凋落物特性，如养分比、纤维素、木质素和酚类物质的含量，被描述为硅供应的变化而改变。但是，关于植物生长过程中硅供应对凋落物分解过程中元素固定的影响知之甚少。因此，本研究通过控制凋落物特性，重点研究了植物生长过程中硅供应对凋落物分解过程中 42 种元素固定的影响。该实验的结果表明，在硅供应较低的情况下生长的植物凋落物分解过程中，金属/类金属的积累明显更高。这可能是由于凋落物特性的改变（主要是养分含量）影响了凋落物的微生物分解、凋落物上微生物的生长，并且可能是由于硅双层，硅双层在高硅含量的叶凋落物中很明显，减少了金属/类金属的结合位点。此外，硅双层还可能通过减少凋落物表面碳化合物的可用性来减少生长中的生物膜，这需要在进一步的研究中阐明。因此，植物生长过程中硅供应不足会增强金属/类金属在水生分解过程中向植物凋落物中的积累。
