AMHERST, Mass. - With the assistance of a grant from the Massachusetts Department of Environmental Management (DEM), a multidisciplinary team of scientists from the University of Massachusetts is testing 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, R.I., 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 will study 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.
"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 remediation 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 DEM grant has provided funding for two graduate students – one from the plant and soil sciences department, and one from microbiology - to help develop methods to remove pollutants and detoxify the region. If successful, this model project could pave the way for a larger, more comprehensive exploration of phytoremediation applications to reduce environmental toxicity emanating from the Blackstone site into the interiors of Massachusetts, Rhode Island, and Connecticut, according to Lanza.
In addition to state grants, alumna Alice K. Shepard of Rhode Island has funded two additional graduate students to work on the project, in keeping with her life-long interest in the solution of complex environmental problems. The Class of 1943 grad, and her husband, Larry, have long supported projects promoting the protection of natural resources.
The project is expected to run through 2001, and involves the UMass departments of microbiology, and plant and soil sciences, as well as the environmental sciences program, all part of the College of Food and Natural Resources. Cleve Willis, dean of CFNR, notes, "This exciting project brings together several outstanding scientists from different departments who will gain evidence on the feasibility of using phytoremediation to remove contaminants from our waterways in an environmentally friendly and economic way. It is a bonus that the research will remove contaminants from a polluted historic American Heritage River."