Spatial-temporal characteristics of inorganic anions in the Middle Route of South-North Water Diversion project in Henan province (China)

Atmospheric deposition is a vital source of nutrient input into lakes and reservoirs. Therefore, it is of great significance to study the spatial-temporal variation of inorganic anions during the dry and wet atmospheric deposition to ensure the water ecological security of the South-North Water Diversion Middle Route Project (MRP). This study investigated the spatial-temporal variation of inorganic anions (F, Cl, NO3, and SO42) concentration and its sedimentation fluxes in dry and wet deposition, and their influence on water quality through 10 automatic dust rainfall collection devices installed in the Henan section of the MRP from October 2018 to October 2020. Results indicated that the anion concentration and deposition flux in dry and wet deposition varied in space and time, and SO42 was the highest anion in dry deposition (178.88 +/- 175.60 mg/L) and NO3 was the highest anion in wet deposition (52.02 +/- 24.63 mg/L). Furthermore, correlation analysis showed that there was a correlation between the wet deposition of anions (F, Cl, NO3, and SO42) and water quality in winter in the Henan section of the MRP (p < 0.05), and anions dry deposition fluxes have an effect on spring and winter water quality, while the wet deposition fluxes only have an impact on summer and autumn water quality due to the abundant precipitation in summer and autumn. This study could provide new data support for management measures such as strengthening the ecological environment and water quality protec-tion in the MRP.