The effect of construction dust and agricultural fertilization on the precipitation chemical composition during summer in the Yangtze River Delta area, China

Abstract

To study the effect of construction dust and agricultural fertilization on the chemical composition characteristics of precipitation during the summer in the Yangtze River Delta region (China), the chemical composition of 144 precipitation samples collected at Wuxi from June 6th to July 15th in 2016 was analyzed. The results demonstrated that the pH values varied from 4.72 to 7.08 for all the precipitation events sampled, with the average pH value as high as 5.88. More than 68% of precipitation events showed pH values higher than 5.6, indicating lower acidic characteristics. The concentrations of anionic ions followed the order of SO42− > Cl− > NO3− > F− > NO2−, indicating SO42−, Cl− and NO3− were the main anions. The concentration of cationic ions followed the order of Ca2+ > NH4+ > Na+ > Mg2+ > K+, indicating Ca2+ and NH4+ were the main cations. The construction dust and agricultural fertilization were responsible for the increase of Ca2+and NH4+ concentration. Significant correlations between NH4+ and SO42− were found, indicating the neutralization ions and combination of all acidic had a great influence on acidity. The higher pH value could be attributed to the neutralization by the high concentration Ca2+, which is proven by the neutralization potential and acidic potential. The average value of fractional acidity is 0.28, indicating approximately 72% acidity is neutralized by alkaline composition. The influence of anthropogenic sources was dominant in chemical composition, higher than the marine and crustal source.