Chemical erosion of reinforced concrete by Cl⁻, SO₄²⁻ and Mg²⁺ in saline soil is the main factor of steel corrosion and concrete damage. In this study, the effects of different molar ratios of aqueous NaCl-MgSO₄ on concrete macroscopic properties (appearance, weight change, compressive strength, and dynamic elastic modulus), ion content, microstructure, and porosity of concrete were investigated. The effects of different molar ratios on the macroscopic characteristics and erosion depth of concrete were revealed through concrete appearance, weight, mechanical properties, and SO₄²⁻ and Cl⁻ content. Analysis of the microstructural evolution process and complex mineral composition of concrete using various microscopic testing methods. The results showed that with increased salt concentration and erosion time, the weight change rate, compressive strength change rate, and relative dynamic elastic modulus of concrete samples had a trend of first increasing and then decreasing. The evolutionary process of transition from large pores to medium and small pores and then to large pores. In the early erosion stage, with increased MgSO₄, corrosion products were deposited in pores and cracks, which refined the concrete pore structure and reduced ion diffusion speeds of Cl⁻, SO₄²⁻, and Mg²⁺. In the later erosion stage, corrosion products caused matrix damage and produced intersecting cracks, which promoted ion diffusion rates and induced deterioration of concrete macroscopic properties. During experiments, the binding ability of SO₄²⁻ and Mg²⁺ ions to hydration products was found to be higher than that of Cl⁻.

Northern Shaanxi Province of China has been affected by severe water shortages, especially in coal mining areas. A systematic method of identifying the influencing factors and their significance on river runoff is essential for paving the way towards environmental protection. Based on stepwise regression analysis, this paper analyzed the runoff influence factors of the Kuye River for 1961-1979, 1980-1998, 1999-2016 and 1961-2016, and calculated the runoff reduction caused by various factors in different periods. We found that the main influence factors on Kuye runoff are disparate in different periods. In 1961-2016, the main factors were rainfall, temperature, soil and water conservation measures, and coal mining. Compared with the base period (1961-1979), the reduction in Kuye runoff stood at 21,569×104 m3 per year in 1980-1998. In 1999-2016, runoff reduction of 52,992×104 m3 was attributable to water conservation measures (57%), temperature (21%), and coal mining (25%) – but was also partially offset by the rainfall increase. These findings could serve as important references for the ecological restoration of river ecosystems in other coal-mining areas.

There has been a marked decrease in river runoff in northern China recently, particularly from coal mining areas, but few studies have been able to quantify the factors influencing this phenomenon. It is urgently need some methods to calculate the river runoff decrease reasons and degree to guide the river ecology restoration. Taking the Kuye River as an example, this study established a reference period (1960–1979) for a Soil and Water Assessment Tool (SWAT) model, and simulated the runoff changes and distribution. Then, the degree of influence of weather, water and soil conservation, industrial and domestic water consumption, and coal mining on river runoff during a recent period (1999–2010) was quantified. Finally, recent changes in runoff and its distribution were simulated with a modified SWAT model. The results show that in comparison to the reference period, recent period 21,987 × 10⁴ m³ per year of runoff from the Kuye River was attributable to weather, while 8,840 × 10⁴ m³, 5,346 × 10⁴ m³ and 13,788 × 10⁴ m³ was attributable to soil and water conservation measures, industrial and domestic water consumption, and coal mining respectively. The distribution of the runoff in the recent period was similar to that in the reference period, although its value was only half of the latter. These results can serve as an important reference for the ecological restoration of the Kuye River basin.

Und erstanding the sources and mechanisms of aquifer recharge is critical for water resource management. So far, this is the first comprehensive study to explore the sources and mechanisms of groundwater recharge applying stable environmental isotopes and hydrogeochemical properties in Southwestern Bangladesh. Water samples from the different sources (groundwater, surface (pond), river and rain water) of high arsenic (As) Holocene aquifers were used to investigate the chemical tracers and environmental stable isotopes (δ18O and δ2H) to explore the hydrogeological features, groundwater recharge sources, mechanisms and processes. The analytical results showed high As concentration in water samples observed 590.7 μg/L. High As groundwater was identified by a low pH value, medium HCO3- and TDS with low concentration of NO3- and SO42-. However, depleted δ2H and δ18O signatures indicated that local vertical rainfall is the key source to recharge groundwater in study area. The recharge process from pond seepage and irrigation return flow also contribute in groundwater recharge. Isotopic signatures suggested the vertical connectivity amongst the aquifers and significant vertical recharge. The reduced heavier isotope reveals extra recharging from floods of mountains and high altitude. Due to the heterogeneous and anisotropic structure of the aquifer system the spatial variability of δ2H and δ18O shows limited lateral connectivity. The combined analyses of δ2H isotope and Cl- ion showed that evaporation is the primary cause for groundwater discharge. Based on the spatial and vertical recharge processes of groundwater, present study provides a crucial baseline knowledge for establishing a sustainable groundwater management strategy. The findings from this study can guide the development of targeted groundwater management strategies and improvement of understanding the groundwater recharge sources and processes.