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南水北调中线总干渠污染物降解及自净能力研究

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自净过程是影响河湖水体水质变化的重要因素,污染物降解系数是决定水体自净能力的关键参数.定量分析长距离输水过程中渠道本身的自净作用,对于认识总干渠水质变化过程,区分其他外源因素对水质变化的影响都有着重要意义.以高锰酸盐指数和氨氮为研究对象,采用室内实验模拟的方法测定了南水北调中线输水总干渠典型断面的污染物降解系数,并将模拟的自净衰减过程与水质实际变化过程进行对比.结果显示:① 总干渠污染物降解系数k相对天然河流处于较低水平,陶岔断面kCODMn为0.055 d-1,kNH3-N为0.003 d-1,郑湾断面kCODMn为0.049 d-1,kNH3-N为0.003 d-1,大安舍断面kCODMn为0.032 d-1,kNH3-N为0.009 d-1;考虑到高锰酸盐指数实际组分复杂,渠道降解系数较模拟结果可能更低.② 模拟的自净衰减过程受温度、流速的影响较大,不同条件下总干渠高锰酸盐指数将从1.8 mg/L下降至0.228～1.042 mg/L,氨氮浓度将从0.034 mg/L下降至0.026～0.030 mg/L.由于存在藻源性、大气沉降和坡面径流等外源输入增量,总干渠沿程实测高锰酸盐指数介于1.8～2.4 mg/L之间(2019 年),基本维持稳定;氨氮浓度介于0.029～0.096 mg/L之间(2019 年),有升高趋势.理想条件下,自净作用最大能够消减高锰酸盐指数增量的81.81%,消减氨氮增量的30.37%.研究成果可为深入认识南水北调中线总干渠输水过程中水质沿程变化提供参考.
Study on water self-purification process in main channel of Middle Route of South-to-North Water Diversion Project
The self-purification process is an important factor influencing changes in the water quality of rivers and lakes,and the degradation coefficient of pollutants is the key parameter determining the self-purification ability of water bodies.The quanti-tative analysis of the self-purification function of the channel in long-distance water transport is of great significance for under-standing the water quality change process and distinguishing the influence of other external factors on the water quality change.U-sing permanganate index(CODMn)and ammonia nitrogen(NH3-N)as the research subjects,the pollution degradation coeffi-cients of typical sections of main canal of Middle Route of South-to-North Water Diversion Project were determined using in-door experimental simulation methods,and the simulated self-purification decay process was compared with the actual water quality changes.The results showed that:①The pollution degradation coefficients for the main canal were relatively low compared to natural rivers.The degradation coefficients of CODMn of Taocha,Zhengwan and Daanshe were 0.055 d-1,0.049 d-1 and 0.032 d-1 respectively,while the degradation coefficients of NH3-N were 0.003 d-1,0.003 d-1 and 0.009 d-1 respectively.Consider-ing that the actual components of the permanganate index were complex,the channel degradation coefficient may be lower than the simulation results.② The simulated self-purification decay process was significantly influenced by temperature and flow rate.Under different conditions,the permanganate index in the main channel decreased from 1.8 mg/L to a range of 0.228 to 1.042 mg/L,while ammonia nitrogen concentration decreased from 0.034 mg/L to a range of 0.026 to 0.030 mg/L.Due to the external inputs from algae,atmospheric deposition,and surface runoff,the permanganate index along the main channel ranged between 1.8 to 2.4 mg/L(in 2019),remaining relatively stable;while ammonia nitrogen concentrations ranged from 0.029 to 0.096 mg/L(in 2019),showing an increasing trend.Under ideal conditions,the self-purification process can reduce the average proportion of changes in permanganate index and ammonia nitrogen by81.81%and30.37%,respectively.The research results can provide a reference for further understanding the changes of water quality along the main canal of the Middle Route of South-to-North Water Diversion Project.

pollutant degradationself-purification processpermanganate indexammonia nitrogendegradation coeffi-cientsimulation experimentmain canal of Middle Route of South-to-North Water Diversion Project

肖新宗、郭芳、贾庆林、刘信勇、王超

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中国南水北调集团中线有限公司,北京 100038

长江水资源保护科学研究所,湖北 武汉 430051

宝武水务科技有限公司山西分公司,山西太原 030021

长江水利委员会湖库水源地面源污染生态调控重点实验室,湖北武汉 430051

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污染物降解 自净过程 高锰酸盐指数 氨氮 降解系数 模拟实验 南水北调中线总干渠

湖北省自然科学基金水利部重大科技项目国家自然科学基金

2022CFB342SKS-2022125U2040210

2024

10.16232/j.cnki.1001-4179.2024.05.007

人民长江
水利部长江水利委员会

人民长江

CSTPCD北大核心
影响因子：0.451
ISSN：1001-4179
年,卷(期)：2024.55(5)
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