Tuesday, March 11, 2014

A distinguished researcher examines Rhode Island's rivers

BAYKEEPER REPORT

Tom Kutcher
Narragansett Baykeeper
@NarraBaykeeper
Narragansett Bay was once the most industrialized estuary in the world. The Bay’s tributaries were used by mills as a perpetual source of energy and as a convenient conduit to carry away industrial waste. With industrialization came extensive build-out of the watershed to support the hordes of workers that flocked to the area in search of a life of security and prosperity on the beautiful shores of Narragansett Bay and her many tributaries. In recent decades, industry along Bay tributaries has subsided, but the cumulative impacts of industrialization and build-out continue to dramatically degrade the water quality of the important rivers that once nourished our Bay.

Dr. Bernhard Peucker-Ehrenbrink of the Woods Hole Oceanographic Institution (WHOI) is an expert in analyzing the historic implications of the biogeochemistry (or chemical makeup) of river water from around the world. Last week at Save The Bay, he presented the preliminary findings from a recent study conducted right here in the Narragansett Bay region to an audience comprised largely of scientists and decision-makers. 

WHOI researchers collect samples from the Pawtuxet River
In partnership with Save The Bay and a host of volunteers from the community, Dr. Peucker-Ehrenbrink analyzed water samples from Narragansett Bay’s major tributaries, the Blackstone, Pawtuxet, and Taunton Rivers, plus the Pawcatuck River, which drains into Little Narragansett Bay on the South Coast. His study aimed to reveal the legacy and ongoing impacts of the industrialization and build-out of Southern New England on the water quality of Rhode Island’s main rivers. Dr. Peucker-Ehrenbrink used a novel analytical method to compare our rivers to some of the most important and well-known rivers in the world, offering the audience a truly unique perspective on our already well-studied river systems.  

WHOI researchers along the Pawtuxet River
Dr. Peucker-Ehrenbrink highlighted that our urban rivers are highly prone to flash flood events due to the speed in which rain water pours off of our now highly-paved urban landscapes versus being absorbed by a historic naturally vegetated landscape. But just as important are the chemicals that flow with that runoff into the rivers. These include toxic heavy metals, petroleum hydrocarbons, nutrients, salts, and sediments. 

For example, the Pawtuxet River was found to have elevated concentrations of petroleum hydrocarbons (motor oil, grease, industrial solvents) compared with other river systems. This certainly reflects urban runoff, and may also reflect the intensive industrial history of this urban river. 

Mid-river water sampling
Another finding of interest is that our rivers are much more acidic than expected relative to our bedrock geology, indicating that they may act a source of carbon dioxide (a greenhouse gas) to our atmosphere, whereas our salt waters act as a carbon sink. Our rivers are also affected by the direct inputs of wastewater discharges from our wastewater treatment facilities. These inputs tend to increase salinity and nutrient concentrations to at or above levels found at the tail end of the Mighty (impacted) Mississippi.

In his concluding statements, Dr. Peucker-Ehrenbrink recommended that we continue to pursue long-term monitoring of water quality in the Narragansett Bay estuary and tributaries. Identifying trends, or predictable changes, in the quality of the water in our rivers is critical for developing effective management actions to solve some of the problems imposed on us by our industrial legacy. 

Save The Bay is honored to work with Dr. Peucker-Ehrenbrink and his many partners at WHOI on this informative project. This project would not have been possible without the generous support of the van Beuren Charitable Foundation.   

- Tom