Rising anthropogenic nitrate levels in the North Pacific Ocean

Kitack Lee

Pohang University of Science and Technology, South Korea

Wednesday, July 19, 2017
Pacific Forum—11:00 a.m.

Human activities, in particular industrial and agricultural processes, have had significant impacts on the upper ocean nitrogen cycle. The rate of deposition of reactive nitrogen (i.e., nitrogen oxides from fossil fuel burning and ammonia compounds from fertilizer in agriculture) from the atmosphere to the open ocean has more than doubled globally over the last 100 years, reaching a magnitude that is comparable to about half of global ocean nitrogen fixation. This analysis revealed that the oceanic nitrate concentration increased significantly over the last 30 years in the top few hundred meters of the North Pacific Ocean due largely to the enhanced deposition of nitrogen from the atmosphere. Enhanced nitrogen deposition has several potential ecological ramifications. Because the North Pacific Ocean is nitrate limited, the input of new nitrogen from the atmosphere may increase primary and export production.

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Next: August 2, Shimi Rii

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