Potomac River: 10-fold increase in native submerged vegetation reflects improved water quality

 

ScienceDaily (Sep. 7, 2010) — The Potomac River in Washington, D.C. is showing multiple benefits from restoration efforts, newly published research suggests.Reduced nutrients and improved water clarity have increased the abundance and diversity of submerged aquatic vegetation (SAV) in the Potomac, according to direct measurements taken during the 18-year field study.

Since 1990, the area covered by SAV in the lower Potomac has doubled, the area covered by native SAV has increased ten-fold, the diversity of plant species has increased, and the proportion of exotic species to native species has declined as nutrients have declined, according to the study by the U.S. Geological Survey and England's National Oceanography Centre (NOC) in Southhampton, UK.

"Improvements to plant communities living at the bottom of the river have occurred nearly in lock step with decreases in nutrients and sediment in the water and incremental reductions in nitrogen effluent entering the river from the wastewater treatment plant for the Washington DC area," said USGS scientist Dr. Nancy Rybicki.

More than a dozen species of SAV, including the exotic hydrilla, co-exist in this reach of the Potomac that was almost barren in a 1978-1981 USGS study.

"People want to know that money spent on ecosystem restoration is having tangible results, but many feel that efforts to clean up Chesapeake Bay have so far had limited success," said researcher Dr Henry Ruhl of the NOC.

"Upgrades to the wastewater treatment plant have benefited SAV habitats 50-miles downstream. These findings underscore the benefits of nutrient reduction efforts on a major tributary to the Chesapeake Bay," said Rybicki, who has been conducting research on the Potomac since 1979.

"Our results suggest that widespread recovery of submerged vegetation abundance and diversity can be achievable if restoration efforts are enhanced across the bay," said Henry Ruhl of the National Oceanography Centre. "There are many other estuaries globally where nutrients have been identified as contributing to SAV habitat decline, so restoration is an issue for many governments." …

Potomac River: 10-fold increase in native submerged vegetation reflects improved water quality

Technorati Tags: environmental restoration,sewage,nitrogen,eutrophication,dead zone

Phosphorus famine: the threat to our food supply

This underappreciated resource--a key component of fertilizers--is still decades from running out. But we must act now to conserve it, or future agriculture could collapse

By David A. Vaccari   

As complex as the chemistry of life may be, the conditions for the vigorous growth of plants often boil down to three numbers, say, 19-12-5. Those are the percentages of nitrogen, phosphorus and potassium, prominently displayed on every package of fertilizer. In the 20th century the three nutrients enabled agriculture to increase its productivity and the world’s population to grow more than sixfold. But what is their source? We obtain nitrogen from the air, but we must mine phosphorus and potassium. The world has enough potassium to last several centuries. But phosphorus is a different story. Readily available global supplies may start running out by the end of this century. By then our population may have reached a peak that some say is beyond what the planet can sustainably feed.

Moreover, trouble may surface much sooner. As last year’s oil price swings have shown, markets can tighten long before a given resource is anywhere near its end. And reserves of phosphorus are even less evenly distributed than oil’s, raising additional supply concerns. The U.S. is the world’s second-largest producer of phosphorus (after China), at 19 percent of the total, but 65 percent of that amount comes from a single source: pit mines near Tampa, Fla., which may not last more than a few decades. Meanwhile nearly 40 percent of global reserves are controlled by a single country, Morocco, sometimes referred to as the “Saudi Arabia of phosphorus.” Although Morocco is a stable, friendly nation, the imbalance makes phosphorus a geostrategic ticking time bomb.

In addition, fertilizers take an environmental toll. Modern agricultural practices have tripled the natural rate of phosphorus depletion from the land, and excessive runoff into waterways is feeding uncontrolled algal blooms and throwing aquatic ecosystems off-kilter. While little attention has been paid to it as compared with other elements such as carbon or nitrogen, phosphorus has become one of the most significant sustainability issues of our time. ...

Phosphorus Famine: The Threat to Our Food Supply

Technorati Tags: resource depletion,agriculture,algae bloom,dead zone

Worst culprits from nine states contributing to Gulf of Mexico dead zone mapped by USGS

 

TreeHugger has covered the issue of ocean dead zones, in particular the annual 8,000 square mile one in the Gulf of Mexico, a number of times.

Now, the US Geological Survey has released new maps which pinpoint the watersheds within the Mississippi River Basin which most contribute to the problem:

The short version is that commercial fertilizer and animal manure in nine states—Illinois, Iowa, Indiana, Missouri, Arkansas, Kentucky, Tennessee, Ohio and Mississippi—causes 70% of the problem. But when you look at the maps the USGS has put out you can see that it's a bit more complicated than that. Those bright red areas show areas with the greatest contribution; it's really specific places within these states. …

Worst Culprits From Nine States Contributing to Gulf of Mexico Dead Zone Mapped by USGS

Technorati Tags: dead zone