Distribution Characteristics And Ingredient Source Of Water Chemistry In The Ganjiang River

The Ganjiang River is the main source of water quantity and hydro-chemical composition of the Poyang Lake.Identifying the temporal-spatial distribution characteristics and source of hydrochemistry in the Ganjiang River has great significance for water environment protection of the Poyang Lake.In this study,37river water samples?13 of them are in the main streams and the rest are in the tributaries?were collected in the dry season in 2015 and in the wet season in 2016.The hydro-chemical parameters in the water were measured,including the concentrations of anions and cations,dissolved trace metal elements and inorganic nitrogen.The Spatio-temporal distribution characteristics of concentrations of anions and cations,dissolved trace metal elements and inorganic nitrogen were analyzed by one way ANOVA,cluster analysis?Ward Method and Squared Euclidean Distance?,Piper diagram and Gibbs diagram.Furthermore,the controlling factors of ions in the Ganjiang River were estimated based on the principal component analysis?PCA?and the main pollution sources of dissolved trace metal elements were identified based on the absolute principal component analysis?APCA?.The conclusions were summarized in this following:?1?In the Ganjiang River,the orders of cations and anions were Ca²⁺>Na⁺>K⁺>Mg²⁺>NH₄⁺and HCO₃^->SO₄^2->Cl^-,respectively.The hydro-chemical type was HCO₃-Ca with weak water salinity,and the ionic concentrations in the dry season were significantly higher than those in the wet season.The average concentrations of NH₄⁺-N and NO₃^--N were 0.39 mg/L and 0.46 mg/L respectively,which reached category II of the water standard in water environmental quality of China respectively.The concentrations of NH₄⁺-N and NO₃^--N in the dry season were higher than those in the wet season.The concentrations of dissolved trace metal elements in most water samples met the national water quality standard,and Fe is the primary trace metal beyond the national standard,i.e.21.6%of water samples had higher Fe concentrations than the national drinking water quality standard,followed by As?8.10%?,Mn?4.05%?,Tl?4.05%?and Al?1.35%?.In addition,the concentrations of Be,Al,V,Fe,Co,Ni,Cu and U during the dry season were significantly higher than those during the wet season,while others had no significant difference.?2?Based on clustering analysis of the ionic concentrations,the Ganjiang River basin was divided into three zones:A1?Taojiang River basin,Yuan River basin and Jinjiang River basin?,A2?Qinjiang River basin,Meijiang River basin,Pingjiang River basin,Enjiang River basin and Lushui River basin?,and A3?other areas beyond the A1 and A2 in the Ganjiang River basin?.The order of Total Dissolved Solid?TDS?in three zones was A1>A3>A2.The main natural factor affecting,hydro-chemical composition of river water in the Ganjiang River basin was rock leaching,and hydro-chemical composition was obviously affected by evaporation in the A3 zone in the dry season.The concentrations of ions were the lowest in A2 where the hydrochemistry were mainly affected by the rock leaching.Seen from the factors of the human,the concentration of SO₄^2-in A1 zone was the highest because of the influence of the industrial and mining waste water.The concentration of Ca²⁺was also the highest in A1,because of the discharge of acidic water which promoted the rock leaching.The concentrations of Cl^-and Na⁺in A3 were higher than those in A1and A2 because of the stronger influence of urban sewage.?3?Based on the spatial distribution of the concentrations of inorganic nitrogen,the Ganjiang River basin was divided into three zones:B1?the downstream of the Huichang County,the upstream of the Yudou County,the northern tributaries of the Ganjiang River,Meijiang River basin,Pingjiang River basin,Shangyoujiang River basin,the upstream of the Zhangshui River basin,Suichuanjiang River basin,Yuanshui River basin,Jingjiang River basin?,B2?the middle reach of the Ganjiang River,the middle and southern tributaries flowing through the city of Nanchang?,B3?the Ganzhou city,the downstream of the Wan'an County,the downstream of the Taojiang River basin,the downstream of the Zhangshui River basin?.The order of the average concentrations of inorganic nitrogen in three zones was B3>B1>B2.B1 and B2 are mainly located in the middle and lower reaches of the Ganjiang River.The concentration of inorganic nitrogen was low and the water quality was better in B1and B2.However,the concentration of inorganic nitrogen was the highest because of the influence of agricultural and urban sewage in B3.?4?Based on the spatial distribution of the concentrations of dissolved trace metal elements,three spatial regions were identified:C1?Xiangshui River basin,Zhangshui River basin and Ganzhou section of the Ganjiang River?,C2?Taojiang River basin,Yuanshui River basin and Jinjiang River basin?,and C3?the other regions beyond C1 and C2?.The contamination order in the three regions was C1>C2>C3.The highest concentrations of Be,Al,Cu,Mo,Sb and As occurred in Xiangshui River basin,Zhangshui River basin and Ganzhou section of the Ganjiang River,while V,Mn,Fe,Ni and Cd in Taojiang River basin,Yuanshui River basin and Jinjiang River basin.The primary sources of dissolved trace metal elements in the Ganjiang River were mining waste water,leaching water of slag and agricultural soils,and steel industry waste water.We estimated based on the MLR-APCS that more than40%of Be,Al,Cu,Pb and U were from mining waste water,more than 35%of Cu,As,Mo and Cd from leaching water of slag and agricultural soils,and more than 41%of V,Mn,Co and Ni from the steel industry waste water.