漓江流域不同土地利用类型下水体污染类型与成因

Types and causes of water pollution under different land use types in Lijiang River Basin

土地利用类型、社会经济活动直接影响着区域水体污染特征。本文以漓江流域为研究对象,在其干流和11条支流设置14个监测断面,进行1个水文年的取样监测,用综合水质标识指数法进行水质评价,并对比分析不同土地利用方式下水体污染类型与成因,分析得出以下结论:(1)研究区主要污染物是TN。(2)污染最严重的是漓江中游,上游水质总体情况比中下游好;水质最差的是桃花江,为Ⅳ类水质;水质最好的是六洞河和小溶江,达到Ⅰ类水质。(3)在季节上,上游枯水期污染比丰水期稍严重;中游枯水期污染较丰水期严重;下游丰水期污染重于枯水期。(4)土地利用类型影响水体的污染类型:上游河流林地覆盖广,污染轻;中游城镇用地和耕地面积广,受工业和生活污水影响,污染较其他河流严重,以点源污染为主;下游河流园地面积比重大,在丰水期水土流失加重,以农业面源污染为主。

Water pollution characteristics of the region are affected by land use types as well as social and economic activities. This paper takes Lijiang River Basin as the research object, 14 monitoring sections are set up along the Lijiang River and 11 tributaries. Monitoring and sampling were done during a hydrological year to evaluate the water pollution according to different land uses, by the comprehensive water quality identification indexes. The results show that （1） TN is the main pollutant in Lijiang River Basin; （2） The most serious pollution is the middle reaches of Li River. The upstream water quality is the best. The most polluted tributary is Taohua River, as the Ⅳ water quality. The water quality of Liudong River and Xiaorong River is the best, class Ⅰ water quality; （3） In terms of season, the pollution in dry season is a little serions than wet season in upstream. The pollution in dry season is worse than wet season in the middle tributaries, and the downstream to the contrary; （4） The types of water pollution are influenced by the land use types. The upstream pollution is not so bad, because of large area of woodland. The midstream pollution is more serious because of the industrial and domestic sewage. The main type of pollution is point source. In the downstream river, garden area is at a major ratio. Soil erosion increases in wet season. The main type of pollution is agricultural non-point source pollution.