The Spatiotemporal Distribution Characteristics and Influencing Factors of Surface Water in Dalian
(Objective)To analyze the spatial and temporal distribution characteristics as well as the influencing factors of surface water in Dalian City,in order to provide a basis for water ecological control planning in the basin.(Methods)The Spearman's rank correlation method was em-ployed to examine the time variation trend of the quality concentration of the characteristic index.(Results)The water quality of the main rivers in Dalian remained generally stable from 2013 to 2022,with most rivers having excellent water quality over the years.The ammonia nitrogen and chemical oxygen demand at monitoring sections remained stable at level Ⅱ or above,with occasional increases in some years.Ammonia nitrogen increased before 2016(p＜0.01),and then decreased significantly(p＜0.01).The overall chemical oxygen demand remained stable(p＞0.05),and total nitrogen showed a significant upward trend(p＜0.01).(Conclusion)The ammonia nitrogen concentration is higher in the upper reaches of Fuzhou River,and higher in the lower reaches of Dasha River,Zhuanghe River,and Dengsha River.The chemical oxygen demand con-centration in all five rivers is relatively high downstream.The total nitrogen concentration is higher in the lower reaches of Zhuanghe,Dengsha,and Fuzhou rivers,and higher in the upper reaches of Biliu River.
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