Natural CO2 Cycle in the Brazos Disrupted

According to a new series of investigations, it would appear that humans managed a difficult-to-aAchieve feat, and namely obscure the natural carbon dioxide (CO2) cycle taking place in the Brazos.

This is Texas' longest river, and the 11th longest in the United States, spanning a length of more than 2,060 km (1280 miles), and boasting a drainage basin of 116,000 square kilometers (44,800 square miles).

Damming and other human activities are the main source of the ecological disaster, say researchers at the Rice University, who conducted the new studies.

“The natural factors that influence carbon dioxide cycling in the Brazos are fairly obvious, and we expected the radiocarbon signature of the river to reflect those influences,” says Caroline Masiello.

She is an assistant professor of Earth science at the university, and also the co-author of the study, which appears in the latest online issue of the esteemed scientific journal Biogeochemistry.

“But it looks like whatever the natural process was in the Brazos, in terms of sources and sinks of carbon dioxide, it has been completely overprinted by human activities,” the expert adds.

The way the atmosphere and biosphere exchange carbon dioxide has become one of the hottest topics of research in the world right now.

The work is extremely important considering that no less than 8.5 gigatons of CO2 are being emitted into the air each year, mostly from humans burning fossil fuels (oil, natural gas and coal).

Plants play a huge part in soaking up excess CO2 on land, engulfing the substances through the process of photosynthesis, which feeds them.

On the open sea, phytoplankton is in charge of removing and storing CO2. These tiny organisms carry the chemical with them to the depths when they die, contributing to keeping the oceans free of pollution.

“We wanted to know if Texas is more like New York or more like Brazil. Because it is hot and humid in Texas, we expected the geochemistry of Texas' rivers to more closely resemble the geochemistry of tropical rivers,” says Fan-Wei Zeng.

The expert, a graduate student in Masiello's lab, and the first author of the new paper, says that their findings show that the carbon stored right where the river flows into the Gulf of Mexico is millennia old.

“Downstream, the carbon dioxide we found was old due to the dissolution of shells. In the upper part of the river, damming has changed the dynamics so much that if there ever was any carbon dioxide coming into the river from the limestone it's been cut off,” says study co-author Bill Hockaday.

The expert is now an assistant professor of geology at the Baylor University in Waco, Texas.

“With the damming, the carbon in the upper reaches appears to be rapidly cycling between the air and the water due largely to algal photosynthesis,” he concludes.