Two reasons precipitation is more acidic today compared to 1900.
The correct answer and explanation is:
Two primary reasons for the increase in the acidity of precipitation today compared to 1900 are the rise in industrial emissions and the increased use of fossil fuels.
First, the burning of fossil fuels has significantly increased over the past century. This includes coal, oil, and natural gas, which release sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere. These compounds react with water vapor, oxygen, and other chemicals to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃), both of which lower the pH of precipitation, making it more acidic. The industrial revolution, starting in the late 1800s, greatly accelerated the use of coal in factories and power plants, followed by an increased dependence on gasoline and diesel for transportation. These activities released vast amounts of sulfur dioxide and nitrogen oxides, and the prevalence of these pollutants continued to grow throughout the 20th century.
Second, the growth in urbanization and population has led to a higher concentration of pollutants in the air. As cities grew, more vehicles were used, factories increased their output, and energy demands expanded, all of which contributed to higher emissions of sulfur dioxide and nitrogen oxides. These pollutants combined with other atmospheric conditions like humidity and temperature, resulting in the formation of acid rain. This trend has been especially prominent in industrialized nations, where emissions were less regulated in the early 1900s. Today, regulations have been put in place to curb emissions, but the effects of years of industrial pollution still linger, contributing to the overall acidity of rainwater.
These two factors—industrial emissions and urbanization—have contributed to the increasing acidity of precipitation, affecting ecosystems, infrastructure, and public health in numerous ways.