Acid rain may hit coastal waters hard

Nitrogen and sulphur compounds contribute to declining ocean pH.

Heidi Ledford

Carbon dioxide (CO₂) isn't the only atmospheric pollutant making the oceans more acidic and threatening the health of coral reefs and plankton. New research suggests that nitrogen and sulphur released into the air by human activities may be driving down the pH more than expected in some coastal waters.

Increasing CO₂ levels are expected to change the acidity of the Earth's waters from 8.2 to about 7.8 by the end of this century. But less attention has been paid to the effects on the acidity of ocean waters of the nitrogen and sulphur compounds emitted by fertilizers and fossil fuels.