News
River Restoration Requires Resilience, Other Ecological Criteria
An ambitious plan is under way in the ecological community to agree on a set of standards for ecologically successful river restoration. The plan is being led by the British Ecological Society's Journal of Applied Ecology, which published a special profile on river restoration that appeared online, April 18, 2005.
Opening the debate is a paper by 22 leading U.S. river ecologists proposing five criteria for ecologically successful river restoration. Their aim is to arrive at a shared set of standards that would eventually be endorsed by the United Nations Environment Programme.
Although billions of dollars are spent on river restoration projects worldwide, little agreement exists on how their success is measured. According to lead author Dr. Margaret Palmer of the University of Maryland: "Given the rapid rate of global degradation of fresh waters, and the fact that river and stream restoration has become a booming enterprise, it is time to agree on what constitutes successful river and stream restoration." Palmer and her colleagues say that the success of river restoration should be judged according to five criteria: a guiding image, improving ecosystems, increasing resilience, doing no lasting harm, and completing an ecological assessment.
The first step should be articulating a "guiding image" describing the ecologically healthy river that could exist at a given site. The second step should be to demonstrate that there have been measurable changes towards the guiding image, such as larger fish populations and clearer water.
The third criteria for successful river restoration is to create hydrological, geomorphological, and ecological conditions that allow the river to be a resilient, self-sustaining system. The fourth criteria is to do no lasting harm. "For example, a channel modification project should minimize loss of native vegetation during river reconstruction, and should avoid the fish spawning season for construction work," Palmer explained.
The final criteria is ecological assessment. According to Palmer: "It is critical that the broad restoration community, including funding agencies, practitioners, and citizen restoration groups, adopt criteria for defining and assessing ecological success in restoration."
For more information, visit www.blackwellpublishing.com/journal.asp?ref=0021-8901.
Human-Made Marsh Mellows Pollution Effectively as Natural Wetlands
Researchers who studied a human-made wetland in Ohio for two years recently concluded that the created wetland filtered and cleaned water as well as, or better than would a natural marsh.
The wetland, which was built in an agricultural area, reduced levels of phosphorus by nearly 60 percent and nitrates by 40 percent. Phosphorus and nitrates are prime ingredients in both fertilizers and in water pollution.
High levels of these nutrients can cause algae to flourish, often to the detriment of fish and other animals that depend on waterways for survival. Algae essentially rob oxygen from water in a pond, lake, and even the ocean.
"We saw a pretty significant reduction in phosphorus and nitrate concentrations -- close to the kind of decrease we typically see in a natural wetland," said William Mitsch, a study co-author and director of the Olentangy River Wetland Research Park at Ohio State University. "The water was cleaner when it left the wetland than when it came in."
The results appear in the March issue of the journal Ecological Engineering. Mitsch conducted the study with Daniel Fink, a student in the environmental science graduate program at Ohio State.
Often called the "kidneys" of the environment, wetlands act as buffer zones between land and waterways. They also act as sinks -- wetlands filter out chemicals in water that runs off from farm fields, roads, parking lots, and other surfaces and hold on to them for years to come.
But the jury is still out on how long a wetland can remain a sink for certain nutrients, Mitsch said. For example, phosphorus doesn't degrade, so after 30 or 40 years, the wetland in this study could possibly become a phosphorus source.
"Wetlands' capacity to store phosphorus declines with time," Mitsch said. "But a wetland that reaches that point has extremely rich soil, which could be harvested and spread over a farm field. Or the wetland itself could be turned into a field again, assuming there are other wetlands nearby to take its place."
The three-acre wetland in the study was roughly the size of three football fields and drained a watershed about 14 times that large. It is located in prime agricultural territory in west central Ohio -- on the shores of Great Miami River, a tributary that flows into a local lake and then on to the Ohio River, which drains to the Mississippi River.
The researchers studied the wetland for two years, collecting and analyzing water samples twice each month. They tested the samples for concentrations of phosphorus, nitrates, and several other chemicals.
The researchers also gathered data on water flowing into the wetland from rain and snowfall and from ground sources. They wanted to know if the design of this experimental wetland would work. Apparently, it did.
"It was a relatively simple, inexpensive way to create a wetland, and it worked," said Mitsch, who is a professor of natural resources at Ohio State. The wetland was constructed by bulldozing a series of basins into the field. The five basins sloped downward toward the river -- the second basin was at a slightly lower elevation than the first, the third basin was slightly lower than the second, and so on. Surface water would come into the first basin and slowly seep toward the other basins. All of the basins were connected by water flowing beneath the surface.
No plants were planted in the wetland; rather, the builders let nature take its course, Mitsch said. Stands of trees surrounded part of the wetland.
"This area once was a wetland," Mitsch said. "So it reverted pretty quickly to that kind of ecosystem when it had the chance."
Over the two-year study, the wetland reduced concentrations of nitrates by 40 percent and phosphorus by 59 percent. It also retained these nutrients during periods of high precipitation, such as during storms and torrential downpours, which saturated the ground.
"It's encouraging that this wetland acted as an effective sink, even when runoff from fertilized fields was especially high," Mitsch said. "Of course, that could change as time goes on, however."
Most of the water entering the wetland came as runoff from farm fields, and nitrate and phosphorus levels all peaked after fertilizer application in the spring. Still, the wetland was able to retain a significant portion of these nutrients.
Algae thrive on phosphorus and nitrogen. While phosphorus is more of a concern in freshwater areas, as freshwater algae thrive on this nutrient, nitrogen is a considerable problem in the Gulf of Mexico.
Each spring, the rush of chemicals that runs into lakes and streams in the Mississippi watershed -- an area encompassing about 40 percent of the United States -- ultimately turn more than 7,000 square miles of the Gulf of Mexico into a "dead zone," a condition known as hypoxia.
Hypoxia happens when excess nutrients, such as nitrates and phosphorus, accumulate in a body of water and cause excessive growth of algae and algal blooms. These blooms thrive on the nutrients and deplete the water of nearly all of its oxygen.
Wetlands experts estimate that the American Midwest has lost about 80 percent of its wetlands in the last two centuries, compared to a 50 percent loss overall in the lower 48 states.
About 577,000 acres of wetlands have already been created or restored under current conservation programs, Mitsch said. But about 10 to 25 times that many are needed in the Mississippi watershed region in order to see a significant reduction of nitrogen levels in the Gulf of Mexico.
The Indian Lake Watershed Project and Natural Resources Conservation Service helped fund this study.
For more information e-mail Mitsch.1@osu.edu
Drinking Water Research Explores Acceptable Arsenic Levels
More stringent federal standards for acceptable levels of arsenic in public drinking water go into effect next year, a prospect that has resulted in four new research projects on arsenic.
The research, funded by the Midwest Technology Assistance Center for Small Public Water Systems, will address the new standards, which will change the acceptable level of arsenic in public groundwater supplies from 50 micrograms per liter to 10 micrograms per liter.
The center, housed at the Illinois State Water Survey, is a joint effort between that agency and the Water Resources Center at the University of Illinois at Urbana-Champaign.
"We feel the work we're funding, especially on arsenic, really is making a difference," said Kent Smothers, the managing director of the center. "Such projects are critical to small systems throughout the Midwest."
The center, one of nine throughout the United States, receives annual funding from the U.S. Environmental Protection Agency and provides grants or direct funding for work by state and university researchers on key areas for small water systems.
The projects include optimizing iron addition for arsenic removal at existing facilities, examining conditions that may control arsenic release into groundwater supplies, and tracking arsenic concentration variability in relation to time and pumping procedures. A new technique for more effective arsenic removal than existing methods also is being examined, Smothers said.
For more information, visit mtac.sws.uiuc.edu or www.sws.uiuc.edu/chem/psl.
Global Warming May Alter Road Salt Routine; Low Sodium Options Suggested
Salting and sanding roads in the Northeast is a routine part of winter, but changes in climate patterns caused by global warming may alter the established policies on snow removal, incurring higher costs and influencing road safety, according to a Penn State geographer.
"I am working with the Consortium for Atlantic Regional Assessment on a case study in New York State's Adirondack Park that investigates many aspects of climate change and land use change on local communities," said Tawan Banchuen, graduate student in geography. "My project focuses on climate change's effect on winter road maintenance including environmental and economic impacts."
Adirondack Park is six million acres in Upstate New York, about the size of Vermont, occupied by 130,000 people year round, but visited by several million each year. The area encompasses Lake Placid, home of two Olympics and many other small towns, and is the largest protected area in the United States.
Banchuen is currently looking at an area in the Park near Whiteface Mountain. He is investigating the use of salt and sand on both federal highways and local roads and tracking where the sand and salt end up. Banchuen would eventually like to model the climate change and consequent precipitation changes to see how it affects the amounts of salt and sand needed and how that affects the environment and economy.
"After the 1980 Lake Placid Olympics, the communities in the park promised to follow a bare pavement policy in winter," Banchuen told attendees at the American Association of Geographers meeting on April 6 in Denver.
"Typically, state roads use mostly salt, and local and town roads use sand," said Banchuen. "Salt is more expensive."
A previous study of four small streams in the park that feed into Rich Lake, found a significant elevation in chlorine downstream from the road. These elevated levels remained for four to six months after the last application.
Unfortunately, salt has many potential impacts on lakes. Increased salt concentrations can cause the lake to stratify into lighter and denser layers. While this often happens in the summer with temperature gradients, the salt could prevent the water from remixing in the fall. Circulation would stop or slow, and oxygen would not mix into the lower layers of the lake. With oxygen depletion come fish kills and releases of heavy metals in the sediment. Saltier water would also favor salt tolerant plants and animals and decrease the diversity in the lake.
Outside the lake, increased road salt can kill vegetation at roadsides. Road salt damages automobile undercarriages and bodies. Salt can also seep into the groundwater drinking supply. Sand increases the load of suspended particles in streams and lakes. It also creates a clean-up problem on the sides of the road.
"Currently, in one county in the Adirondacks, half the road maintenance budget is spent on clearing the roads and making them safe," said Banchuen. "The rest can only repair half the damaged roads in the area."
A warmer climate does not necessarily mean less road salt use. Most researchers who look at warming agree that a warmer global climate will bring more precipitation to the area of the Adirondacks. The question is, will that precipitation fall as snow, mixed snow and sleet, sleet, freezing rain, or rain?
"If the precipitation tends toward more sleet and freezing rain, then more salt and sand will be needed to make the roads safe," says Banchuen. "But, fewer days of snow might mean less ski traffic in the park and a depressed winter economy. Policy makers will need to adapt to the changes and make decisions that minimize the impacts of the changes."
For more information, e-mail txb213@psu.edu.
Good Water Promotes Clean Bill of Health
The introduction of water filtration and chlorination in major U.S. cities between 1900 and 1940 accounts for one-half the steep decline in death rates during those years, according to an article published in the recent issue of the journal Demography.
The analysis found that clean water was responsible for cutting three-quarters of infant mortality and nearly two-thirds of child mortality during that time, according to Harvard economists and article co-authors David Cutler and Grant Miller.
"Inexpensive water disinfection technologies can have enormous health returns in poor countries, even in the absence of sanitation services," said Cutler.
In 2000, the World Health Organization and UNICEF found that more than one-fifth of the drinking water samples from existing water systems were contaminated with bacteria and pollutants. Worldwide, 1.1 billion people lack access to clean water.
Although not a substitute for appropriate investment in sanitation, low-cost water disinfection could prevent a significant share of the 1.7 million annual deaths from diarrhea-related diseases worldwide, according to Cutler and Miller.
"While the (South Asian) tsunami was an enormous, immediate catastrophe," Cutler noted, "the deaths from unclean water are likely every bit as large, but more spread out in time and space."
Cutler and Miller also write that, between 1900 and 1940, U.S. death rates fell 40 percent, more rapidly than in any other time in the nation's history. About one-half of that decline is the result of clean water, according to the study.
For their analysis, the authors used U.S. Census Bureau mortality statistics for specific urban areas; they also gathered information on the timing of the introduction of clean water technologies from reports published in municipal engineering and urban planning journals during the period. Water filtration and chlorination were introduced in the U.S. cities before sewage treatment and sewage chlorination, allowing the researchers to calculate the impact separately.
Cutler and Miller estimate that the social rate of return on clean water technologies in the United States was about $23 gain for every $1 spent. They calculate that the cost per person-year saved was about $500 in present day dollars. The authors add that, had they factored in the impact of less disease and greater productivity, their estimates of the social benefits of investment in clean water would have been much greater.
For more information, visit www.prb.org/cpipr/demography/cutler.pdf.
This news column originally appeared in the May/June 2005 issue Water and Wastewater Products, Vol. 5, No. 3.
This article originally appeared in the 06/01/2005 issue of Environmental Protection.