Search Results (3)

Lakes are vital freshwater ecosystems that sustain biodiversity, support livelihoods, and drive socio-economic growth globally. However, they face escalating threats from anthropogenic activities, including urbanization, agricultural runoff, and pollution, which are exacerbated by climate change. Phewa Lake in Nepal was selected for this study due to its increasing rates of nutrient enrichment, sedimentation, and pollution. This study evaluated seasonal and spatial water quality variations within the lake by analyzing water samples from 30 sites during the pre-monsoon and post-monsoon seasons. Twenty physicochemical parameters, including the potential of hydrogen (pH), dissolved oxygen (DO), electrical conductivity (EC), and major ions, e.g., calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), potassium (K⁺), bicarbonate (HCO₃⁻), chloride (Cl⁻), sulfate (SO₄²⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and ammonium (NH₄⁺), were measured. The average pH ranged from 8.06 (pre-monsoon) to 8.24 (post-monsoon), reflecting dilution from monsoon rains and increased carbonate runoff. Furthermore, the DO levels in Phewa Lake averaged 7.46 mg/L (pre-monsoon) and 8.62 mg/L (post-monsoon), with higher values observed post-monsoon due to rainfall-driven oxygenation. Nutrient concentrations were shown to be elevated, with the nitrate concentration reaching 2.31 mg/L during the pre-monsoon period, and the phosphate concentration peaking at 0.15 mg/L in the post-monsoon period, particularly near agricultural runoff zones. The dominant cations in the lake’s hydrochemistry were Ca²⁺ and Mg²⁺, while HCO₃⁻ was the primary anion, reflecting the influence of carbonate weathering. Cluster analysis identified the lake outlet as a high-pollution zone, with the total dissolved solids (TDS) reaching 108–135 mg/L. Additionally, Principal component analysis revealed agricultural runoff and sewage effluents as the main pollution sources. Seasonal dynamics highlighted monsoon-induced dilution and pre-monsoon pollution peaks. These findings underscore the need for targeted pollution control and eutrophication management. By aligning with the sustainable development goals (SDGs) relevant to clean water and climate action, this research provides a replicable framework for sustainable lake management that is applicable to freshwater ecosystems worldwide. Full article

The research was aimed at studying pitting corrosion, which precedes the appearance of fistulas in steel and cast-iron pipelines in water supply systems and leads to significant expenditures. The process of fistula formation is accompanied by the formation of tubercles and craters on the surface of a corroding metal. The study focused on examining the qualitative and quantitative composition of the solution, which is generated inside the tubercles during their growth. It was found that, during the operation of water pipelines, the concentration of aggressive chloride ions inside the tubercles increases significantly compared to the chloride content of the source water. The increase in chloride concentration leads to an accelerated corrosion rate, potentially causing the formation of fistulas over time. As a result of the study, a mechanism for changing the mineral composition of the solution inside the tubercles has been proposed. This is due to the manifestation of selective properties by a dense layer of tubercles. The study also examined the appearance of crystalline forms of corrosion products that form after removing pipes from the water supply system. The study also reveals the conditions of corrosion products emerging. Further studies on the structure and properties of a dense layer of corrosive sediment could be used to evaluate the effectiveness of various corrosion inhibitors. Full article

Chlorine ions in the air are a key factor in the corrosion of offshore buildings. Mastering the distribution law of the chloride ion settlement rate (${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$) in three-dimensional (3D) spatiality is helpful in protecting offshore buildings. The self-designed “kite-hanging wet candle method” was used to collect chloride ions in the air, using ion chromatography to analyze the chloride ion concentration of the sample solution, and obtained the annual ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ in the offshore atmosphere at different vertical heights, using the Pearson correlation coefficient method to analyze the influence of environmental factors on the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$. The results show that the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ has a significant linear relationship with temperature, relative humidity and wind speed. Among them, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ is positively correlated with temperature and negatively correlated with wind speed and relative humidity. In the vertical height range of 10–100 m, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ presents a “$\subset$”-shaped distribution. In the range of 10–30 m, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ is mainly controlled by the impact of ocean spray; in the range of 30–80 m, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ is mainly controlled by marine aerosols; and in the range of 80 m–100 m, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ is mainly controlled by marine aerosols and wind speed. Under the influence of wind direction and wind speed, the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ of the windward side is higher than that of the leeward side at different monitoring points, which are close to the coastline and at a low vertical height. Studying the distribution of the ${\mathrm{R}}_{{\mathrm{C}\mathrm{l}}^{-}}$ in 3D spatiality can effectively prevent and reduce its impact on offshore buildings. Full article