Investigating the quality of Isfahan city rainwater under the influence of air pollution in 2018-2019

Air pollution is one of the most important problems facing people all over the world today, especially in big cities. The ever-increasing population growth, as well as the increase in vehicles and the number of industrial factories in the city of Isfahan, have led to this city being considered one of the largest industrial cities in Iran. Therefore, this city is considered the second most polluted city in Iran after Tehran. The city of Isfahan faces the crisis of air pollution on many days of the year, which directly and indirectly affects all aspects of people's lives in this city. Among these impacts is the quality of rainwater in the area, which joins the surface and groundwater in the region and affects its quality. This cycle will continue and air pollution will affect the quality of drinking water, agriculture, respiratory diseases and, in a word, the health of the people in this region.

In this study, the effects of air pollution in Isfahan on the quality of rainwater in the 10th district of Isfahan city were investigated. The quality of rainwater was studied based on the World Health Organization standard for drinking water, APHA standard for running water, Chinese standard for agricultural use, and Iranian standard for drinking water and agricultural use. To evaluate the air quality of the region, the statistics of the Isfahan Meteorological Organization station were used and the meteorological parameters were analyzed based on the American Environmental Protection Agency standards.

The results showed that the EC value of rainwater is more sensitive than pH to determine the suitability of rainwater quality for drinking uses, so when considering pH, many samples have favorable quality, but when considering EC value of the same sample, the quality of rainwater is unfavorable. The results of air quality monitoring based on the amount of PM2.5 on rainy days showed that 5 days were clean, 13 days were acceptable, and 6 days were unsanitary for sensitive groups.

Isfahan urban runoff needs to be treated for drinking but it is suitable for agriculture. The results showed that the EC of rainwater is more dependent than pH to the rainfall depth. The results show that rainfall with a relatively small depth caused a significant increase in EC of stormwater. This decrease in the amount of precipitation has led to an increase in the amount of CO and PM2.5 in the atmosphere. The amount of rainfall did not affect the pH of rainwater, while with the increase of rainfall depth, the EC of rainwater has decreased significantly. In general, rainfall depth has a significant effect on EC concentration of rainwater. The results showed that in all the rainy days, the amount of CO, SO2 and O3 pollutants are in a clean state.