Major Elements in the Upstream of Three Gorges Reservoir: An Investigation of Chemical Weathering and Water Quality during Flood Events

Abstract

Rivers transport terrestrial matter into the ocean, constituting a fundamental channel between inland and oceanic ecosystem and affect global climate change. To reveal chemical weathering processes and environmental health risks during flood periods, water samples were collected in the upper reaches of Three Gorges Reservoir (TGR) in 2020. HCO3− and Ca2+ were the most abundant anions and cations of the river water, respectively. The range of HCO3− concentration was between 1.81 and 3.02 mmol/L, while the mean content of Ca2+ was 1.03 mmol/L. The results of the Piper diagram and element ratios revealed that the river solutes were mainly contributed by carbonate weathering and gypsum-rich evaporite dissolution. A mass balance model indicated that the contribution order of sources to cations in the main channel (Yibin-Luzhou) was evaporites > carbonates > atmospheric input > silicates. The order in the Chongqing—Three Gorges Dam was carbonates > atmospheric input > evaporites > silicates. These results showed a lithologic control on hydrochemical characteristics. Most sampling sites were suitable for agricultural irrigation according to the water quality assessment. However, indexes sodium adsorption ratio (SAR) and soluble sodium percentage (Na%) were higher than 1.0 in Yibin-Luzhou and 30% in Yibin–Chongqing, respectively, suggesting a potential sodium hazard. In addition, except Tuojiang River and Shennong River, the risk of sodium hazard in tributaries was relatively low. High Na+ concentration in irrigation water can damage soil structure and function and ultimately affect agricultural production. Water quality in the upstream of a Piper diagram should attract enough attention.

Evaporation Processes in the Upper River Water of the Three Gorges Reservoir: Evidence from Triple Oxygen Isotopes

“…The study area is located in the Three Gorges Reservoir (TGR), which is a typical basin of evolution from river to lake. , The influence of reservoir construction on the river carbon cycle, biological diversity, and allocation of water sources continues to attract the attention of scholars. − Isotope techniques have become major tracers for the studies of various geochemical processes, − such as the effects of climate change and human activities on the water cycle, , the mixing processes between tributaries and main streams, , and the hydrological effect of reservoirs. , However, the data of isotopes in the TGR and even in the Yangtze River are still limited, which is insufficient to reveal the signatures of the water cycle and the regulatory effect of the Three Gorges Dam (TGD) on the TGR Basin . In the Yangtze River Basin, triple oxygen isotopes are only involved in the study of atmospheric precipitation at the headwaters and upper reaches of the Yangtze River , but are scarce in studies on river water.…”

CO2 Release Driven by the Combination of Sulfide Oxidation and Carbonate Dissolution in the Upper Changjiang River: Effect of Erosion and Lithology on Chemical Weathering

“…The data on major ions has been reported by Wang et al. (2021). The DOC concentrations were measured by Elementar Vario TOC analyzer with a precision of 10%.…”

“…The study area is under a monsoonal climate regime, which leads to seasonal fluctuations in rainfall and temperature (Wang et al., 2021). The annual precipitation in the studied area varies from 1,000 to 1,300 mm, and more than 60% of the total rainfall is received during the wet season from May to September (Wu et al., 2018).…”

“…) were determined by using ionic chromatography (IC, Dionex Corporation, USA). The data on major ions has been reported by Wang et al (2021). The DOC concentrations were measured by Elementar Vario TOC analyzer with a precision of 10%.…”

O ataque a fontes de água como crime de guerra: análise no âmbito do Tribunal Penal Internacional

“…A água é uma preocupação mundial, notadamente em relação ao seu acesso, quantidade e qualidade. Ainda convive-se com a transmissão de doenças através da água e com as externalidades causadas pela contaminação desse precioso líquido (GEVORGYAN et al, 2021;JIMÉNEZ-OYOLA et al, 2021;COIMBRA;ESCAPA;OTERO et al, 2021;WANG et al, 2021;CARLES et al, 2021).…”