南水北调东线工程沿线湖沼湿地生态环境特征及退化分析

Features and Degradation of Eco-Environment of Lakes and Marshes along the East Route of the South-to-North Water Transfer Project

南水北调东线工程沿线湖沼湿地广泛发育,以浅积水的内陆淡水湿地为主。天然湖泊湿地向人工、半人工湿地演变明显,沼泽湿地均属于富营养型。湿地生物资源较为丰富,种群结构具有趋同性。由于自然与人为过程相互作用的结果,湖沼湿地的生态环境呈现了明显的退化趋势:湿地水量减少,面积逐渐萎缩;湿地水体普遍受到污染,污染程度从南向北加剧;湖泊湿地水体普遍处于中、富营养化状态;生物资源呈现衰减趋势;湿地调蓄功能逐渐下降。文中对湖沼湿地退化的形成原因、机制进行了分析,认为自然过程是退化的前提、基础,人为过程是退化的主要驱动力。本文为进一步研究东线工程对湖沼湿地生态环境的影响提供了基础。

The East Route of the South-to-North Water Transfer Project is a strategic area of optimal allocation of water resources in China. Along the East Route, lakes and marshes has developed extensively. They are distinctive ecosystems that have various important services and functions. Most of them belong to inland wetlands with freshwater and shallow water resources, which have abundant biological resources. The biology population structures have obvious comparability. Natural lakes markedly evolved to partially or completely artificial reservoirs. Marshes belong to eutrophication type. The aim of this article is to provide a foundation to study the effects of the East Route of the South-to-North Water Transfer Project on eco-environment of lakes and marshes in the future, and how to protect eco-environment effectively. At the present time, under the interactive impacts of natural and man-made processes, the eco-environment of lakes and marshes degrades obviously, The main characteristics are as follows: water quantity is decreasing, areas of lakes and marshes are diminishing. The pollution of water quality tends to be more serious from south to north, and it also has difference between flood season and non-flood season. Most lakes are in medium or high eutrophication condition. Biological resources of lakes and marshes such as species diversity of fishes diminish gradually, and storage function to flood also descends. Based on these analyses, the article points out the main reasons of degradation, which includes: quick wave of climate in the north part of our country, immobile channel of the Yellow River, drying-up of the Great Canal, blindly reclaim land from lakes and marshes, numerous flood control project and serious point sources and non-point sources pollution. Among which, man-made processes created cumulative impacts on the eco-environment of the lakes and marshes. Besides, over fishing, artificial breeding of fishes and petroleum exploitation also destroyed the eco-environment. At last, mechanisms of degradation are summarized as: natural process is the precondition and basis, and man-made processes are the main driving forces.