清水江河道深潭—急流—河滩系统水质差异

Evaluations on the Difference of Water Quality of the Riffle-deep Pool-benchland Systems in Watercourses of Qingshuijiang River

指出了天然河流是由深潭-急流-河滩不断重复出现构成的系统,深潭-急流-河滩是河流的基本结构单元。在清水江上、中、下游选取9个基本结构单元为对象,测定水质指标、模拟底质氮磷释放,分析了山区典型河道基本结构单元与水质变化之间的关系。研究表明:深潭和急流水体中各指标浓度TN(0.90>0.84)、NO3--N(0.50>0.45)、NH4+-N(0.225>0.195)、TP(0.0172>0.0148)、DO(8.50<10.54)、BOD5(1.36<2.67)和COD(11.30<11.35),F检验除TN、NO-3-N、NH+4-N差异性不显著外,其余均显著。用蒸馏水模拟河水,底质氮磷释放量小于原河水模拟河水氮磷释放量,并且见光模拟释放要小于避光条件模拟释放。河流形态结构变化影响着水环境质量,深潭-急流-河滩不断重复出现使河流水质得到改善,在河道生态修复中需要遵循河流形态结构规律以提高河流的自净能力。

A river is a continual system composed of the repetitively occurring basic structural units, i.e. the ＂riffle-- deep pool--benchland＂systems in a river. In the study, we selected nine of the ＂riffle--deep pool--benchland＂ sys- tems respectively in the upstream,midstream and downstream of Qingshuijiang River to test water quality indicators and simulate nitrogen and phosphorus release from a substratum collected from the riverbeds of these systems. The results indicated that the concentrations of water quality indicators in deep pool and riffle were respectively as fol- lows： TN（0.90〉0.84）, NO3- --N（0.50〉0.45）, NH＋ --N（0.225〉0. 195） ,TP（0.0172〉0.0148） ,DO（8.50〈10. 54） ,BOD5（1.36〈2.67）and COD（11. 30〈11. 35）. Using distilled water to simulate the river water, the phosphorus and nitrogen releases from the substratum was relatively less than the original water used, and the releases of nitro- gen and phosphorus with sunlight was also less than without the sunlight. F--tests present the differences of these results between deep. pools and riffles except for TN, NO3- --N, NH4＋ --N. River morphology significantly affected water quality of river and the repetitive emergence of the riffle--deeppool--benchland systems was helpful for river water environments improved. The changes of the river structures into primitive forms, i. e. , ＂riffle--deep pool-- benchland＂ systems, were not only beautiful in rive landscape but also significant in ecosystem functioning in river system restoration.