人工沉床技术在水环境改善中的应用研究进展

人工沉床技术是利用沉床载体和人工基质栽植大型水生植物,对污染水体进行原位修复的一种生物-生态水体修复技术,大型水生植物是该技术的核心。人工沉床技术中大型水生植物对水体的净化作用是一个复杂的物理、化学和生物过程,其作用机理包括:①直接吸收营养物质和富集重金属;②通过物理吸附去除悬浮物和高分子有机物,提高水体透明度;③释放氧气,提高水体DO含量;④通过植物化感作用抑制藻类和细菌生长;⑤为微生物活动提供附着载体和氧源,形成植物-微生物的协同净化。然而,以往水生植物特别是沉水植物在水底直接栽植易受水体透明度、水深等条件的制约,成为高等水生植物在低透明度和水深较大的重污染水体修复应用的重要障碍。而人工沉床技术可以通过床体升降人为调控植物在水下的深度,克服水深、透明度等因素对植物生长的制约,易于实现植物种群优化配置和群落构建,而且有利于植物后期的维护和管理,将为利用高等水生植物修复透明度低、水深较大或水位变化较大的重污染水体提供一条新的思路。

Improvement of Water Quality by Constructed Submerged Plant Bed

The constructed submerged plant bed(CSPB),with aquatic macrophytes being vegetated on a constructed submerged bed and artificial filling,is a biologic-ecological technique of water body restoration at virgin position for polluted water body,and its core is still aquatic macrophytes.The purification of aquatic macrophytes of CSPB for polluted water is a complicated physical,chemical and biologic process,the mechanism contains: 1.absorption of nutrient elements and enrichment of heavy metal;2.removal of SS and macromolecule organic matter by physical adsorb adsorption;3.enhance of Do in water by releasing oxygen;4.controlling the growth of algal and bacteria by means of biochemical effect;5.providing carrier and O2 for microorganism and forming plant-microbiology cooperating purification.Nevertheless,because aquatic macrophytes be vegetated directly under water in previous studies,the utilization of aquatic macrophytes,especially of submerged aquatic vegetation,is restricted by diaphaneity and depth of water,it becomes a important limit for aquatic macrophytes to be applied for restoring grievously polluted water with low diaphaneity and large depth.Contrarily,the CSPB technology can artificially adjust the depth of aquatic macrophytes under water by means of rising or sinking down the vegetation bed,so,it can eliminate the limit of diaphaneity and depth to the growth of aquatic vegetation.moreover,the CSPB technology is convenient for the scheme of species and community construction of aquatic macrophytes,as well as for the management and maintenance of aquatic vegetation.It should provide a new idea for water quality improvement by utilizing aquatic macrophytes in grievously polluted water body with low diaphaneity and large depth.