生物扰动对沉积物中污染物环境行为的影响研究进展

生物扰动由于显著改变沉积物结构和性质,进而影响沉积物中污染物的环境行为。综述生物扰动对沉积物中氮、磷、重金属和疏水性有机污染物环境行为的影响。生物扰动促进这些污染物从沉积物向水体释放。生物扰动还对不同的污染物产生其它不同的影响。对于氮,生物扰动还影响其硝化与反硝化作用;对于磷,生物扰动不仅改变其化学形态,还提高有机磷降解。对于重金属,生物扰动还能改变其在沉积物中的分布及化学形态。对于疏水性有机污染物,生物扰动主要增强生物富集和代谢,以及提高生物降解。

Review of the impacts of bioturbation on the environmental behavior of contaminant in sediment

The feeding, burrowing, and reworking of benthic invertebrates, collectively termed bioturbation. Bioturbation is one of most important ecological processes, which can cause the redistribution of particles and interstitial water in sediments, and therefore have significant affects on the physical, chemical and biological properties of the sediment. In particular, bioturbation redistribute particles and porewater in sediment and thereby increase the surface area available for sediment-water interface exchange of nutrients and contaminants, resulting in significant changes on the sorption characteristics of the sediment. Hence, the environmental behavior of contaminant in sediment was significantly influenced by the bioturbation. For the nitrogen, bioturbation can impact it's biogeochemistry in two routes. One is that bioturbation can stimulate the solute exchanges (oxygen and metabolites) across the water-sediment interface and then enhance the microbial processes such as nitrification and denitrification. The other is that bioturbation can enhance the exposed area of sediment to water and air, thus accelerated the exchange of nitrogen at the sediment-water interface. For the phosphorus, the bioturbation have significantly effect on it's biogeochemical cycling, including the increase of the release of soluble reactive phosphorus (SRP) from sediment to water and alteration the chemical form of phosphorus. Furthermore, the degradation of organic phosphorus was enhanced by bioturbation. For heavy metals, bioturbation can alter the environmental behavior of metals in sediment in several ways. The first way is that the spatial heterogeneity of sedimentary metal levels was influenced by the bioturbation. The second way is that the bioturbation lead to a significant flux of metals to water. The third way is that the bioturbation can affect the chemical form of heavy metals. For the hydrophobic organic contaminants (HOCs), the release, bioaccumulation and biodegradation of them were significantly affected by the bioturbation. On one hand, bioturbation can lead to a significant increase flux of HOCs to water. On the other hands, bioturbation can enhance the benthos bioaccumulation the HOCs. Addition, due to bioturbation has been confirmed to increase the abundance of microorganisms and the oxygen in the sediment, thus the biodegradation of HOCs were enhanced.