Marine nitrogen loss is strongly tied to the sinking of organic matter in low-oxygen coastal waters, reports a study published online this week in Nature Geoscience. The findings suggest that surface productivity regulates the loss of biologically usable nitrogen from the global ocean.
Marcel Kuypers and colleagues assessed rates of nitrogen turnover and loss in the low-oxygen waters off the coast of South America. They found that rates of nitrogen loss peaked in the highly productive coastal waters, where large quantities of organic matter sink from the surface ocean. The researchers suggest that this sinking organic matter fuels the microbes responsible formarine nitrogen loss.
In an accompanying News and Views article, Bo Thamdrup states that they “show that organic matter export is a significant driver of nitrogen loss in the eastern South Pacific oxygen minimum zone.”