Geochemical Signatures of Water Bodies and Sources in the Qinghai Lake Area, China

Abstract

The chemical composition of dissolved constituents in aquatic ecosystems is of fundamental importance in regulating chemical and biological dynamics and processes. There are many factors that can determine and affect chemical composition of lakes and rivers. This paper presents fundamental geochemical information for the waters in Qinghai Lake area in China and assesses geochemical patterns, relationships between the elements, and potential mechanisms for these patterns. The concentrations of 30 elements from 16 water samples were measured. The results showed that Ca (8.1-88.9 mg/L), K (5.1-372.7 mg/L), Mg (6.3-1127.0 mg/L), Na (10.0-6459.0 mg/L), and S (4.8-2002.0 mg/L) were the dominant elements in all water samples but exhibited considerable variation among systems. The tributaries had high Ca, relatively low Na+K, and low salinity, indicating rock weathering as the dominant factor determining their geochemistry. The satellite lakes (except the two largest ones) showed low Ca, moderate Na+K and Mg, and low salinity, indicating the combined effects of many factors. Correlation analyses suggested that B, K, Li, Mg, and Na concentrations are determined by evaporation and crystallization and dissolution of sulfate minerals while Al and Fe concentrations are affected mostly by rock weathering.