Most of Rhode Island's rivers offer natural beauty and numerous opportunities for recreation, but Rhode Island's urban rivers were once seen as lost causes, destined to be covered over and used as a convenient way to flush away toxic waste. But thanks to the dedication and work of Rhode Island citizens and a blossoming commitment to a cleaner environment, Rhode Island's rivers are staging a comeback. Fish and wildlife abound in the Blackstone River, the Woonasquatucket and Mussasack Rivers in Providence have been uncovered and turned into a pleasant downtown park, and chemical levels in the Providence and Seekonk rivers have dropped.

On September 3, over 150 incoming freshmen from Providence College joined the staff of the Narragansett Bay Commission (NBC) for a large river and community clean up along the Woonasquatucket River in Providence.

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Over the past three years, the NBC has organized numerous clean-ups of the Woonasquatucket, an American Heritage River, from Waterplace Park to Olneyville Square. The NBC-organized clean-ups have attempted to clear floatable pollution such as trash, tires, shopping carts and other debris from the river. The clean-ups have been very successful clearing thousands of pounds of debris from the river and riverbanks.

“We are so pleased to see these students taking an active interest in the health of our urban rivers,” said NBC Chairman Vincent Mesolella. “We hope that other corporate and community partners will follow the example of these students, and join the NBC in our efforts to recapture the beauty that urban rivers provide.”

Of course, trash in the urban rivers is just the easily visible part of the problem. Centuries of industrialization along Rhode Island's major waterways has resulted in chemical pollution that is just now being addressed.

The Blackstone River has been part of U.S. history since the American Industrial Revolution, when in 1793 Samuel Slater constructed Slater Mill in Pawtucket. The Blackstone River has continually been an important natural, recreational and cultural resource for both Rhode Island and Massachusetts.

A multidisciplinary team of scientists from the University of Massachusetts tested ways to use common pond plants to stabilize and decontaminate seriously polluted areas of the historic Blackstone River Watershed. Extending from south central Massachusetts to Pawtucket, the Blackstone has been designated an American Heritage River by Congress, and its surrounding area, the Blackstone River Valley, is a National Heritage Corridor.

It was along the Blackstone that the first water-powered cotton-spinning mill in the U.S. was built in 1790, laying the foundation for the American Industrial Revolution and New England's successful textile industry. The by-product of that success was a legacy of millions of tons of heavy metals - mercury, zinc, cadmium, arsenic, tin, copper, and others – left behind, embedded in the sediment at the bottom of the river. These pollutants continue to impact on the health of the region's human and wildlife populations all the way to the Narragansett Bay, according to environmental microbiologist Guy R. Lanza, head of the environmental sciences program at UMass, and leader of the Blackstone research project.

Over the course of the project, the UMass team studied ways to clean up pollution from heavy metals and organic chemicals in the Blackstone sediment, through research conducted by Baoshan Xing, of the department of plant and soil sciences, and by environmental microbiologist Klaus Nuesslein, of the microbiology department. Xing's basic research into the remediation of organic chemicals and metals in soils and sediments will set standards for risk assessment related to this and similarly contaminated sediments. Nuesslein will study native plants and beneficial microbial communities that can be used to stabilize, remove, or degrade contaminants from this and similar sites.

Phytoremediation, or the use of plants to remove, degrade or stabilize complex environmental contaminants, is an alternative technology for remediating sites contaminated with heavy metals, some radioactive materials, and hazardous organic materials at a fraction of the cost of many conventional treatment technologies. Although not a new technology, phytoremediation has gained recognition in recent decades as science has searched for technologies that are both practical and safe, says Lanza.

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"We know phytoremediation works in many instances, and the beauty of it is, it doesn't leave behind its own pollution, it doesn't require an unsightly treatment facility, and the tools you need - usually quite ordinary plants – are readily available and inexpensive," said Lanza.

"It's such an elegant system: The sun is the engine, the pollutants themselves can supply some of the fuel, and green plants work like well-oiled machinery in this safe and sound clean-up technology."

Lanza points out that dredging, incineration, precipitation technology, soil-venting, or filtration generally is used to accomplish soil remediation. In some cases, remediation by bacteria alone will convert the agents of pollution into something more manageable to handle. Phytoremediation, on the other hand, works by letting plants, and the microbes that live on their root systems, absorb, oxidize, and store pollutants within their cells, or by breaking down the chemicals to less toxic forms. Plants often can stabilize pollutants, keeping them from expanding their reach into the environment.

Lanza says phytoremediation has many advantages over other methods, but its downside is that living creatures, including humans, fish, and birds, must be prevented from eating the plants that take up the pollutants. "Even so, it's still easier to isolate, cut down and remove plants growing on the surface of the water or in sediments, than it is to dig under a river and take up sediments without letting pollutants loose in the environment," explains Lanza. After the plants are harvested, they can be burned to concentrate heavy metals in ash, and buried in contained landfills.

The Blackstone River flows 48 miles before becoming the Seekonk River, combining with Providence River and discharging to Narragansett Bay. A recent study completed by the Narragansett Bay Commission (NBC) conclusively demonstrates that Water Quality Criteria are being met in the Providence and Seekonk Rivers for a number of trace metals, as well as for ammonia toxicity. The NBC study, the most extensive monitoring study ever done on the Providence and Seekonk Rivers, used a variety of state-of-the-science methodologies and the data generated tells a positive story about the effects of two decades of clean-up efforts in these two important urban tributaries.

The NBC conducted extensive monitoring of the Providence and Seekonk Rivers to evaluate the condition of the receiving waters of our wastewater treatment facilities. Study components included circulation current profiling with acoustic Doppler profilers conducted by Dr. Chris Kincaid of URI Graduate School of Oceanography (GSO), physical water quality characterization with state-of-the-art YSI sondes and sensors, background nutrient analyses conducted by the expert marine laboratory of Dr. Candace Oviatt of URI/GSO and ultra-low level dissolved and total trace metal sample collections. The trace metal samples were analyzed by Microinorganics, Inc., one of the few laboratories nationwide with the capability to analyze samples to the ultra low detection levels necessary for this study. The cost of this project, the first of its kind ever conducted in Narragansett Bay, was approximately $200,000, excluding NBC staff time associated with project planning and field work.

“We brought together the best scientific resources available to ensure the integrity of this study,” said NBC Executive Director Paul Pinault, P.E., noting that over the past fifteen years the NBC has aggressively decreased industrial pollution discharges to the rivers through its award-winning Pretreatment Program.

The study concluded that the levels of toxic inorganic substances, such as cadmium, copper, lead, nickel, and silver, once a tremendous threat to the health of Providence and Seekonk Rivers, have dropped from dangerous to very acceptable levels and that levels of ammonia, also a toxic substance, are well within the guidelines set by the USEPA. The results of this study should provide the data necessary for the DEM to remove the Seekonk and Providence Rivers from the EPA 303 (d) List of Impaired Waterways for these toxic pollutants.

“The NBC will strive to further reduce toxic discharges to Narragansett Bay through strong Industrial Pretreatment, Environmental Monitoring, Pollution Prevention, and Sewer Permitting programs, and through maintenance and improvements to the collection system and efficient wastewater treatment plant operations,” Pinault added.

The revival of Rhode Iland's urban rivers is a major accomplishment. Congressman Patrick J. Kennedy says “The Blackstone River is not only the largest river in Rhode Island, making it a key natural resource, but it is also the central to the prosperity of the Blackstone Valley Heritage Corridor.” It's just a matter of time until the state's urban rivers are as beautiful and clean as ther rest of Rhode Island's rivers.

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