Hydrogeochemical characterization and groundwater quality assessment in intruded coastal brine aquifers (Laizhou Bay, China)

Abstract

The aquifer in the coastal area of the Laizhou Bay is affected by salinization processes related to intense groundwater exploitation for brine resource and for agriculture irrigation during the last three decades. As a result, the dynamic balances among freshwater, brine, and seawater have been disturbed and the quality of groundwater has deteriorated. To fully understand the groundwater chemical distribution and evolution in the regional aquifers, hydrogeochemical and isotopic studies have been conducted based on the water samples from 102 observation wells. Groundwater levels and salinities in four monitoring wells are as well measured to inspect the general groundwater flow and chemical patterns and seasonal variations. Chemical components such as Na, K, Ca, Mg, Sr, Cl, SO, HCO, NO, F, and TDS during the same period are analyzed to explore geochemical evolution, water-rock interactions, sources of salt, nitrate, and fluoride pollution in fresh, brackish, saline, and brine waters. The decreased water levels without typical seasonal variation in the southeast of the study area confirm an over-exploitation of groundwater. The hydrogeochemical characteristics indicate fresh-saline-brine-saline transition pattern from inland to coast where evaporation is a vital factor to control the chemical evolution. The cation exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. Meanwhile, isotopic data indicate that the brine in aquifers was either originated from older meteoric water with mineral dissolution and evaporation or repeatedly evaporation of retained seawater with fresher water recharge and mixing in geological time. Groundwater suitability for drinking is further evaluated according to water quality standard of China. Results reveal high risks of nitrate and fluoride contamination. The elevated nitrate concentration of 560 mg/L, which as high as 28 times of the standard content in drinking water is identified in the south region. In addition, the nitrate and ammonia data of the Wei River suggests decreasing nitrification rate in the study area from inland to estuary. High fluoride concentration, larger than 1 mg/L, is also detected in an area of about 50% of the study region. The saltwater intrusion is analyzed to be responsible for part of dissolution of minerals containing fluoride. Therefore, water treatment before drinking is needed in urgent to reduce the health expose risk.

Multi-Scale and Multi-Dimensional Time Series InSAR Characterizing of Surface Deformation over Shandong Peninsula, China

“…However, due to the rapid urbanization, industrialization and economy growth, serious long-term subsidence of different magnitudes has occurred in this area. Firstly, overexploitation of natural groundwater resources, including fresh water and brine, has led to severe land subsidence for decades [9][10][11][12]. Abundant natural brine deposits occur in the coastal zones where many salt factories were built along the coastline of Laizhou Bay and Jiaozhou Bay.…”

Hydrogeochemistry of Ground Water in Mbeere South Sub-County, Kenya

“…Hydrogeochemistry uses the water's chemistry as a forensic tool to find out where groundwater has been and what has happened to it along its journey (Bundschuh and Zilberbrand, 2012). This information gives a wide, more regionally understanding of ground water systems (Zhang et al, 2017). Furthermore, this improved knowledge can be used to create more inclusive management, conservation plans and more equitable groundwater/surface water regulations.…”

“…Water is an important natural resource that is essential for all forms of life (Zhang et al, 2017). Water as a resource is important for economic development due to its support for agricultural development, energy generation, municipal and commercial uses livestock development, industrial growth, wildlife and recreational activities among others (Kinuthia et al, 2009).…”

“…In arid and semi arid areas, groundwater is the main source of water for agricultural, industrial and domestic uses (Kinuthia et al, 2009). In order to manage this limited resource effectively, hydrogeochemistry of groundwater is essential to establish the hydrogeochemical processes affecting it (Zhang et al, 2017). Groundwater contains a wide range of dissolved inorganic constituents due to the hydrogeochemical processes .Some of these processes are mineral dissolution, rock weathering, precipitation and ion-exchange.…”

“…The hydrogeochemistry of groundwater would therefore be an informative basis that can be used in its management and conservation for effective domestic, industrial and agricultural purposes. Hydro-geochemical information is useful in predicting changes associated with groundwater quality (Zhang et al, 2017). The information can be used further in developing step-gap measures to address the changes in water quality and therefore management of this scarce commodity especially in arid and semi-arid areas.…”