城市黑臭河道富营养化次生灾害形成机制及其控制对策思考

对城市河道黑臭污染的形成及其治理、富营养化次生灾害表现形式、形成机制以及预防和控制对策等方面进行了总结和研究.结果表明,随着城市黑臭河道相应污染治理工程、措施的实施,河道水体污染负荷得到了大大消减、水质得到了一定的改善、黑臭也逐步好转,但营养盐仍处于相对较高的水平,且可被植物直接利用吸收的营养盐储备充足,同时,黑臭污染的治理使得受损的河道生态系统得到了一定的恢复和重建,当外界环境条件适宜时,极易引起水华暴发、浮萍泛滥、水葫芦"疯"长、水生植物生物量激增等富营养化次生灾害.对于城市黑臭河道治理后富营养化次生灾害的预防和控制必须以城市黑臭河道污染治理为基础,将其纳入到河道污染整治整体规划中.综合运用上/下行效应理论,应从外源控制、内源治理和修复、整体生态系统恢复等角度进行系统预防和控制.同时也应厘清思路,认识到城市黑臭河道富营养化及其次生灾害的形成是城市黑臭河道污染治理过程中的必经阶段,城市河道水环境治理应从当前的"黑臭等重污染治理"向"氮磷营养盐控制"转变.

Study on formation mechanism,and control and preventive measures of eutrophication secondary disasters in urban malodorous-back river

In this paper, the eutrophication secondary disasters in urban malodorous back river were reviewed from the forming and treatment of “malodorous back”, and the disaster forms and control and preventive measures. The results indicated that with the implementation of many treatment projects, technologies and measures in pollution control and remediation, pollution load of urban malodorous back river was greatly reduced, water quality had been much improved, and the “malodorous back” disappeared gradually. All these resulted to the nutrient that can be utilized by plant was at high level, and the damaged ecosystem of urban river was restored and constructed. Once those environmental factors were very suitable, the major outbreak of eutrophication secondary disasters (e.g. algal bloom, Lemna minor L, Eichhorniacrassipes.) could be unavoidable. For its part, the control and preventive measures of eutrophication secondary disasters must be based on the treatment and remediation of “malodorous back”. In addition, we realized that the outbreak of eutrophication secondary disasters would be an unavoidable stage of the treatment and remediation of “malodorous back”, and the current focus on pollution control and remediation of urban river should be changed from the severe pollution treatment (e.g. “malodorous back”) to the nutrient (Nitrogen, phosphorus, etc.) control.