40 a来珠江广州段水环境污染特征演变及驱动机制研究

Water pollution variation and mechanism analysis of Pearl River,Guangzhou in the past 40 years

基于1977—2020年珠江广州段水环境质量监测数据,以溶解氧(Dissolved Oxygen,DO)质量浓度、氨氮(NH_(4)^(+))质量浓度和5 d生化需氧量(Five-day Biochemical Oxygen Demand,BOD_(5))为主要研究指标,分析40 a来珠江广州段水环境质量演变趋势、关联特点及影响因素。采用ArcGIS空间渲染技术展现1980—2020年主要水质指标时空分布状况,再现珠江广州段水环境质量由恶化到改善过程;运用Mann-Kendall(M-K)非参数秩次检验,分析鸦岗、猎德和莲花山3个重点断面主要因子长时间尺度变化趋势。结果显示:40 a来珠江广州段主要水环境指标呈“先恶化后改善”趋势。DO质量浓度总体呈波动态势,趋势性不明显(Z=0.425,p> 0.5),NH_(4)^(+)质量浓度呈极显著下降趋势(Z=-3.179,p<0.01),BOD_(5)虽呈极显著上升趋势(Z=2.747,p<0.01),但总体质量浓度不高。采用Pearson相关性分析,探讨主要水质因子的内联特点和潜在同源性,揭示污水处理能力的提升与DO质量浓度改善及NH_(4)^(+)质量浓度削减呈显著线性正相关关系;采用主成分分析(Principle Component Analysis,PCA)和偏相关分析法,初步解析了重点断面影响DO质量浓度水平的主要影响因素和驱动机制。结果显示:上游DO质量浓度主要受硝化耗氧和有机耗氧过程影响,中游主要受有机耗氧和硝化耗氧过程影响,下游则主要受硝化耗氧和有机耗氧过程影响。研究为下阶段广州市深入打好水污染防治攻坚战,巩固现有治理成果,实现珠江广州段向优良水体提升转变提供了理论和数据支持。

Based on annual water quality monitoring data of Pearl river,Guangzhou section,from 1977 to 2020,a comprehensive analysis of primary water quality indices such as dissolved oxygen(DO),ammonia(NH_4~+),and 5 d biological oxygen demand(BOD_5),is conducted to investigate variation trend,interior co-relative characteristics and influential factors during the last four decades.Through ArcGIS spatial rendering technologies,primary water quality indices temporal and special distribution and variation are simulated from the 1980s to 2010s,which also vividly reveal the process from deterioration to upgradation.The long-term tendency of primary indices at three major segments of Yagang,Liede,and Lianhuashan are obtained by Mann-Kendall non-parametric rank test.Results reveal that in the past 40 years,the main water environment indicators in Guangzhou section of the Pearl River shows a trend of “deteriorating first and then improving”.DO shows a wave dynamic potential in general,with no obvious trend(Z = 0.425,p > 0.5),NH_4~+shows a very significant downward trend(Z =-3.179,p < 0.01),and BOD_(5) shows a very significant upward trend(Z = 2.747,p < 0.01),but the overall mass concentration is not high.Secondly,the co-relative relationship and homology among primary indices are investigated by the Pearson co-relative analysis method,which reveals that the improvement of sewage treatment capacity is positively correlated with the improvement of DO and the reduction of NH_4~+ mass concentration.Lastly,factors affecting DO balance in the water environment and driving mechanisms are also analyzed by Principal component analysis(PCA) and partial co-relative analysis methods.The results show that DO in the upstream is mainly affected by nitrification and organic processes;In the middle reaches,organic oxygen consumption and nitrification oxygen consumption are the main factors;The downstream is mainly affected by nitrification and organic oxygen consumption processes.Findings from this paper help to consolidate water quality remediation progress and to provide important theoretical and data support for future water quality upgradation to a better level.