HYDROCHEMICAL DISCHARGE OF RIVER WATERS OF SOUTHERN KHABAROVSK REGION IN THE PERIOD OF SUMMER HIGH WATER

Abstract

The relevance of the research consists in studying hydrochemical river discharge as one of the main indicators of the ecological state of water objects.The main aim of the research is to obtain new knowledge on hydrochemical discharge of the rivers at southern Khabarovsk region, which are required for objective assessment of the ecological status of the region and for carrying out effective water protection measures.Objects of the research are the Amur River and seven lesser streams: Bikin, Khor, Podkhorenok, Bira, Kiya, Malaya Chirka, 2-aya Sedmaya. Methods. Concentration of major anions (Cl–, SO42–) wеrе аnаlyzеd by ion chromаtogrаphy (Shimаdzu LC‒10А); mаjor cаtions (Nа+, K+, Cа2+, Mg2+), trace elements and rare earth elements ‒ with ICP‒MS (Agilent, 7500с) method. The hydrocarbonate ion (HCO3-) concentration was taken as the total alkalinity. It wаs аnаlyzеd by dirеct titrаtion by Bruyеvich mеthod. Thе totаl minеrаlizаtion (∑i) is thе sum of concеntrаtions of mаjor rivеr wаtеr еlеmеnts. Results. In July 2011 Amur River and seven lesser streams (Bikin, Khor, Podkhorenok, Bira, Kiya, Malaya Chirka, 2-aya Sedmaya, located at southern part of Khabarovsk region, were sampled and analyzed for their major elements, trace elements and rare earth elements. During summer flood river waters are low-mineralizated, ∑i does not exceed 50 mg/l. Ca2+ is the predominant cation and HCO3– is the major counter-ion for cations in all samples. High concentrations of dissolved Al, Fe и Pb were found in the surface waters of all the rivers studied. In the Malaya Chirka River there are high concentrations of dissolved Co, Cu, Mn and extremely high Cd, exceeding the average global concentrations in 40 times. The concentration of the other trace elements in the studied rivers is general corresponded to their average global concentrations and is a characteristic of the natural regional background during summer floods. A regional level of total concentrations of soluble forms of rare earth elements (1,44–5,44 µg/l) was established. The distribution and level of rare earth elements concentrations in the studied river waters reflect the overall composition of the watershed rocks. The calculated total daily fluxes of major elements, trace elements and rare earth elements, supplied by the Bira, Kiya, Podhorenok, Bikin, Khor and Amur rivers, equal to 61894, 377 and 2,21 t/day, respectively.

Keywords

• hydrochemical discharge
• major ions
• trace elements
• rare earth elements
• river
• khabarovsk region