New research has shown that the Mississippi River is full of carbon dioxide as a result of farming practices around the river. The excess carbon dioxide in the river is a worry because it is acidifying the downstream of the Gulf of Mexico and this leads to harmful effects on marine wildlife and coral.

Researchers tracked various changes of the water in the river – from water levels through to various chemicals. They found that over the past century, the chemistry of the river has changed significantly. The researchers believe that farming practices around the river are the main culprits – they point to practices such as liming (adding calcium to the soil), drainage, and crop rotation, believing that these factors have increase the amount of bicarbonate and water run-off to the Mississippi.

Water in the farmland will start to dissolve the minerals in the soil – the most important of which is bicarbonate. This bicarbonate forms carbon dioxide when the water run off dissolves the soil minerals, and this makes its way into the nearby water systems.

Bicarbonate is a big player when it comes to absorbing atmospheric carbon dioxide – when the Mississippi hits the Gulf of Mexico, the ocean waters absorb more CO2 and therefore become more acidic. Carbonate ions are needed for shells and coral reefs to form. The extra acidity in the water decreases the amount of carbonate ions available and therefore the extra carbonate in the water has a massive negative effect on marine wildlife.

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