Nitrogen pollutants in seawater threaten the atmosphere

An international team of scientists, led by professor of oceanography and atmospheric science Robert Duce of Texas A&M University, concluded that a large amount of nitrogen compounds - released into the atmosphere during the process Burning fossil fuels and using human nitrogen fertilizers - mixing with seawater can remove carbon dioxide from the atmosphere.

A group of 30 experts from institutions around the world presented the conclusions in the latest issue in Science.

Human-produced nitrogen compounds are carried away by the wind and deposited in seawater, which acts as a fertilizer, increasing the growth of marine plants. The growth of plants causes the phenomenon of more carbon dioxide from the atmosphere absorbed into the seawater. According to the team's paper, this process causes 10% of the carbon dioxide in the atmosphere to be released by human activities, thus potentially reducing climate warming.

However, some of the nitrogen deposited in seawater is re-processed to form another nitrogen compound called nitrous oxide, which is then released back into the atmosphere. Nitrous oxide is a powerful greenhouse gas - about 300 times more per molecule than carbon dioxide - and thus, losing about two-thirds of what comes from removing carbon dioxide, Duce explained. He said: 'But of course, the whole system is very complicated and we are still unsure about other impacts that may occur in the ocean.'

Kelp is growing up in the ocean.Human-produced nitrogen compounds are carried away by the wind and deposited in seawater, which acts as a fertilizer, increasing the growth of marine plants.(Photo: iStockphoto / Tammy Pelus)

According to Duce, most areas of nitrogen are nutrients that limit plant growth. So when all the nitrogen on the surface of a sea is used up, there will be no marine plants remaining in that area. Duce explained that his research team found that the nitrogen produced by humans deposited in seawater accounts for about one-third of the nitrogen from the outside, increasing the amount of nitrogen for the development of marine plants making the species real. things grow more .

Marine plants live on the type of carbon produced in seawater (bicarbonate), which is equal to the amount of carbon dioxide in the atmosphere. When bicarbonate sustains life for marine plants that are used up, it breaks the balance, and carbon dioxide is pulled down to the seawater from the atmosphere to restore that equilibrium.

Duce said, the enrichment of nitrogen compounds produced by humans in the ocean removes some of the most important greenhouse gases - carbon dioxide - in the atmosphere.However, this benefit is limited by another nitrogen compound, nitrous oxide, also formed from nitrogen enrichment and re-emitted into the atmosphere as a powerful greenhouse gas.

Duce said: 'If you don't consider the effects of man-made nitrogen when trying to regulate climate change, you're missing an important part of the carbon cycle and the nitrogen cycle. So nitrogen deposition is a very important factor in climate change '.

According to the team's calculations, about 54 million tons of nitrogen generated by human activities settled into the sea from the atmosphere in 2000. Duce said the team also found the amount of nitrogen currently emitted. This is about 10 times more than the 1860s. He added that the amount of nitrogen released into the atmosphere will continue to increase in the coming decades with increasing demand for energy and fertilizer. The team predicts that by 2030, the amount of nitrogen generated by humans emitted into the atmosphere will increase to 62 million tons a year.

Duce said: 'Clearly there are many things we do not know about the scale and timing of the impact of nitrogen deposition in seawater as well as the subsequent reactions affecting the climate system. These relationships are closely and very complex, interacting with each other. This is a very important thing that policy makers must pay attention to. Even scientists are trying to regulate coordination to understand, model climate in the future also need careful consideration. '