Hydrochemical Characteristics and the Relationship between Surface and Groundwater in a Typical ‘Mountain–Oasis’ Ecosystem in Central Asia

Abstract

Water environment monitoring is an important way to optimize the allocation and sustainable utilization of regional water resources and is beneficial for ensuring the security of regional water resources. In order to explore hydrochemical distributions in a mountain–oasis ecosystem in Central Asia, surface water and groundwater samples from the Kaidu River basin were collected over four seasons. pH values, major ions, total dissolved solids (TDS) and stable isotopes were determined during the period from 2016 to 2017. The results showed: (1) that most water bodies in the study areas were mildly alkaline and that hydrochemical distributions showed significant seasonal and spatial variation; (2) that δD and δ18O in surface water and groundwater showed enrichment in summer and autumn and poverty in spring and winter, with higher δ18O values appearing in the oasis area and lower δ18O values appearing in the mountain area; (3) that most of the water bodies in the study areas were of HCO3—Ca2+ type, with the hydrochemical types of groundwater presenting obvious spatial inconsistency relative to surface water; (4) that rock weathering was the main factor controlling hydrochemical composition in the study areas and that human activities had an influence on the groundwater environment in the oasis area; (5) and that surface water–groundwater interactions also displayed spatial inconsistency, especially in summer. The interaction between river water and groundwater was more obvious in the traditional oasis area, especially in spring and summer. The results will be important for regional water resource management and sustainable water utilization.

Multidisciplinary Research of Thermal Springs Area in Topusko (Croatia)

“…Instead, the samples showed an equivalent ratio of 2.1, suggesting that the excess of Ca 2+ comes from carbonate dissolution, and the origin of the sulphate anion remains undetermined. The dissolution resulting from silicate weathering may have contributed to the groundwater chemistry, providing the additional source of Ca 2+ and Mg 2+ balanced by sulphate anions [80,86,87]. Figures 3 and 4 point to (i) carbonate dissolution as the primary process driving the solute content in the thermal waters of Topusko, (ii) the interaction of the waters with Mesozoic carbonates that represent the main aquifer of THS, and (iii) the presence of limestone and dolomite rock in the system.…”

Applying Factor Analysis and the CCME Water Quality Index for Assessing Groundwater Quality of an Aegean Island (Rhodes, Greece)

“…The topic of water quality is broad and comprehensive [1,[12][13][14][15]. Gradual deterioration of water quality is one of the primary impacts of agricultural, industrial, and household expansion and other land use changes [2,4,13,16].…”