Acid rain has a disproportionate impact on coas...( The release of sulfur and nitrogen i...)

The release of sulfur and nitrogen into the atmosphere by power plants and agricultural activities plays a minor role in making the ocean more acidic on a global scale, but the impact is greatly amplified in the shallower waters of the coastal ocean, according to new research by atmospheric and marine chemists.

Ocean acidification occurs when chemical compounds such as carbon dioxide, sulfur, or nitrogen mix with seawater, a process which lowers the pH and reduces the storage of carbon. Ocean acidification hampers the ability of marine organismssuch as sea urchins, corals, and certain types of planktonto harness calcium carbonate for making hard outer shells or exoskeletons. These organisms provide essential food and habitat to other species, so their demise could affect entire ocean ecosystems.

The findings were published this week in the online early edition of the Proceedings of the National Academy of Sciences; a printed version will be issued later this month.

Acid rain isnt just a problem of the land; its also affecting the ocean, said Scott Doney, lead author of the study and a senior scientist in the Department of Marine Chemistry and Geochemistry at the Woods Hole Oceanographic Institution (WHOI). That effect is most pronounced near the coasts, which are already some of the most heavily affected and vulnerable parts of the ocean due to pollution, over-fishing, and climate change.

In addition to acidification, excess nitrogen inputs from the atmosphere promote increased growth of phytoplankton and other marine plants which, in turn, may cause more frequent harmful algal blooms and eutrophication (the creation of oxygen-depleted dead zones) in some parts of the ocean.

Doney collaborated on the project with Natalie Mahowald, Jean-Francois Lamarque, and Phil Rasch of the National Center for Atmospheric Research, Richard Feely of the Pacific Marine Environmental Laboratory, Fred Mackenzie of the University of
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