NGI and NOAA's AOML Study Reveals River Runoff Creates a Buffer Zone for Ocean Acidification in the Gulf of Mexico
February 28, 2022
The research, published in Geophysical Research Letters, used models to identify the main drivers of ocean acidification for different regions of the gulf. They provide evidence that river alkalinity has counteracted the progression of ocean acidification for coastal areas along the gulf.
Ocean acidification refers to a reduction in seawater pH over time, mainly caused by increased levels of carbon dioxide in the atmosphere being absorbed into the ocean. Seawater chemically reacts with carbon dioxide to form carbonic acid, causing the ocean to become more acidic.
Corals and shellfish need a higher aragonite saturation state and less acidic waters, i.e., higher on the pH scale, to thrive. If waters become too acidic, less coral reef habitat will be available for fish and other reef-dwelling animals, diminishing biodiversity and marine ecosystem health.
The Mississippi River has a relatively high level of alkalinity for a freshwater body. Over recent decades, agricultural practices such as liming (adding neutralizing materials to lower soil acidity) and water quality improvements have contributed to the increased water alkalinity in the Mississippi River system. Alkalinity acts as a neutralizing factor to make a solution less acidic and more basic or alkaline.
"Our study showed that river alkalinity inputs from the Mississippi River can offset the progression of ocean acidification in northern coastal areas of the Gulf of Mexico. We can expect river alkalinity to have a similar counteracting effect on ocean acidification in other US coastal regions since the dominant pattern for US rivers is alkalinization," said Fabian Gomez, a research scientist at AOML and NGI.
A recent report by NOAA's Office of Coastal Management highlighted the economic value of the Gulf of Mexico's coastal and marine ecosystems: they support approximately 598,000 workers and are the largest contributor to America's blue economy, with an estimated $104 billion dollars coming from oil and gas production, marine shipping, and the fishing industry.
NOAA's research to better understand ocean acidification will help preserve and manage coral reefs and other marine species that gulf coastal communities depend on for fishing, tourism, and other economic drivers in the region.
By AOML Communications