Human induced industrial waste also causing Ocean acidification

Washington: A new study has shown that human induced industrial and agricultural processes have significantly impacted the rising anthropogenic nitrate levels in the North Pacific Ocean.

The rate of deposition of reactive nitrogen from the atmosphere to the open ocean has more than doubled globally over the last 100 years. This anthropogenic addition of nitrogen has reached a magnitude comparable to about half of global ocean nitrogen.

David Karl, at the University of Hawaii, along with researchers from Korea, Switzerland and the U.S. National Oceanic and Atmospheric Administration, assessed the changes in nitrate concentration between the 1960s and 2000s across the open North Pacific Ocean.

Their analysis revealed that the oceanic nitrate concentration increased significantly over the last 30 years in surface waters of the North Pacific due largely to the enhanced deposition of nitrogen from the atmosphere.

The researchers used ocean data in conjunction with the state-of-the-art Earth System Model to reconstruct the history of the oceanic nitrate concentration and make predictions about the future state of the North Pacific Ocean. Their assessment revealed a consistent picture of increasing nitrate concentrations, the magnitude and pattern of which can only be explained by the observed increase in atmospheric nitrogen deposition.

Karl said that the growing human population needs energy and food - unfortunately, nitrogen pollution is an unintended consequence and not even the open ocean was immune from the daily industrial activities.

Given the likelihood that the magnitude of atmospheric nitrogen deposition will continue to increase in the future, the North Pacific Ocean could rapidly switch to having surplus nitrate. Thus, past and future increases in atmospheric nitrogen deposition have the potential to alter the base of the marine food web; and, in the long term, the structure of the ecosystem.

The study is published in Science.