Since the Industrial Revolution, humans have been releasing nitrogen into the atmosphere and, from there, into the ocean, where it acts as a nutrient but also poses dangers to aquatic ecosystems in high quantities. Now, new research finds that far less human-generated nitrogen is reaching the open ocean than previously thought.
Thousands of years ago, the Earth was going through an ice age and conditions were harsh: it was much colder and windier compared to today, and large amounts of dust were being scattered in the air and much of it contained iron. The iron eventually found its way into the oceans and many scientists believe that the extra iron increased the growth of tiny forms of marine life. One part of the puzzle of iron fertilization of the oceans has been evaluated by an international team of researchers.
A new study finds that human activities are likely contributing far less nitrogen to the open ocean than many atmospheric models suggest. That's generally good news, but it also nullifies a potential side benefit to additional nitrogen, says Meredith Hastings, associate professor of Earth, environmental and planetary sciences at Brown University and one of the study's co-authors. (Co-author Prof. Daniel Sigman et al)