土壤原位覆盖对底泥的修复作用研究

Effect of in-situ capping on contaminated sediment remediation using local soil

在高度厌氧底泥和富营养化水体构成的模拟生态系统中,采用土壤和硅藻土进行原位覆盖,研究了覆盖技术对水-沉积物界面微环境的改善作用和不同覆盖材料对苦草生长的影响。这2种底质覆盖后,表层底泥氧化还原电位(Eh)分别提高了48.37%和46.77%,底层水体的溶解氧消耗降低,水体中的总氮(TN)和总磷(TP)含量降低;与对照箱体的苦草死亡相比,经过土壤和硅藻土覆盖的箱体中苦草正常萌发、定植和生长;硅藻土箱体苦草的生物量、叶绿素和根茎比均高于土壤覆盖箱体。因此,原位覆盖能有效改善底层水体和表层底泥的氧化还原环境,隔绝污染底泥和延缓营养盐释放,为沉水植物种子萌发和幼苗生长提供有利的生境条件。

In an ecological simulation system with highly anaerobic sediment and eutrophicated water, soil and diatomite were used as capping materials to study the effects of sediment manipulation on water-sediment surface and restoration of Vallisneria natans. After soil and diatomite capping treatment, the redox potential （Eh） of surface sediment was elevated by 48.37% and 46.77%, respectively, the oxygen consumption in bottom water decreased, and the TN and TP in overlying water reduced. Plants in both soil and diatomite capping tanks germinated, leafed out and settled down normally, while those in untreated tank died and decayed without leafing out. The biomass, content of chlorophyll and root/shoot ratio of V. natans in diatomite capped tank were all higher than those in soil capping tank, which suggests that diatomite may be more favorable for biomass accumulation and colonization. It is concluded that, in-situ capping could help to improve the redox condition near water-sediment interface, isolate contaminated sediment, delay the release of excessive nutrients, and most importantly, provide a suitable condition for seedling of submerged aquatic plants.