Acid rain is not always harmful

As acid rain decreases, microorganisms in streams, rivers and soil have a favorable opportunity to grow. However, the absence of acid rain can also cause many environmental problems, scientists warn.

"Those are the results we didn't expect," said David DeWalle, an environmental expert at the University of Pennsylvania (USA). "The increasing amount of carbon dioxide in rivers, streams and soil has a great impact on forest ecosystems and carbon balance in general". Dissolved carbon dioxide is the product of respiratory activity in the organism and the decomposition process of organic substances. It is a gas that causes acidification in pure water sources.

The scene in a forest after acid rain.(Photo: terradaily.com)

DeWalle and colleagues tracked five streams in the Appalachian Mountains (USA) from 1990 up to now. They explored the effects of sulfur reduction - one of the major causes of acid rain . The cause of reduced sulfur gas concentration is the Clean Air Act to reduce the air pollution of the US government.

Thanks to this law, over the years, water quality has improved and the amount of nitrogen in the streams has also decreased. However, the team found that the amount of carbon dioxide is increasing in all five streams. They argue that the decline in pollutants is creating favorable conditions for the bacteria in the soil to multiply.

During development, bacteria decompose organic compounds, releasing carbon dioxide, water and other dissolved organic matter, DeWalle explains. Due to the absorption of bacteria, organic compounds cannot dissolve into water. The respiratory process of bacteria increases the concentration of carbon dioxide in the soil.

The disturbance of the ecosystems of forests in the Appalachia Mountains - home to many species of microorganisms and also a place to create jobs for many people - can cause disastrous environmental and economic consequences .

"Although the decline in nitrogen and sulfur levels is a positive sign, it has affected the forest ecosystem. The increasing amount of CO2 in the soil means that someday, the house-effect gas this glass will escape the soil and return to the atmosphere, " DeWalle said.

Viet Linh