River carbon impacts Arctic Ocean much more than previously believed

Washington, Feb 13 : A new study has indicated that arctic rivers, which transport huge quantities of dissolved organic carbon (DOC) to the Arctic Ocean, has much more impact on its chemistry and biology than previously believed.

The study, conducted by R.M. Holmes of the Woods Hole Research Center and colleagues at collaborating institutions, has challenged the prevailing paradigm regarding DOC in arctic rivers that it is of little significance for the biogeochemistry of the Arctic Ocean.

In fact, the new study has shown that DOC in Alaskan arctic rivers is remarkably adaptable during the spring flood period when the majority of annual DOC flux occurs.

According to Dr. Holmes, "Though only about 1% of global ocean volume, the Arctic Ocean receives almost 10% of global river discharge. As a consequence, organic carbon transported by arctic rivers has the potential to strongly impact the chemistry and biology of the Arctic Ocean".

Because of logistical challenges, past studies have focused almost exclusively on the summer low-flow period, when numerous studies have shown arctic river DOC to be refractory.

However, by timing their sampling to include the high-flow period just after the spring ice break, the researchers found that much of the DOC discharged by Alaskan rivers to the Arctic Ocean is adaptable.

Consequently, riverine inputs of DOC to the Arctic Ocean may have a much larger influence on coastal ocean biogeochemistry than previously realized, and reconsideration of the role of terrigenous DOC on carbon, microbial, and food-web dynamics on the arctic shelf is warranted.

According to Holmes, "Though tantalizing evidence has been emerging in recent years, this study was the first to directly show that dissolved organic carbon in rivers during the spring flood period is highly labile."

Rivers sampled for this project were the Kuparuk, Sagavanirktok, and Colville rivers on the North Slope of Alaska. The next step will be to conduct similar experiments on larger arctic rivers, including the massive rivers entering the Arctic Ocean from Siberia.

ANI