22 August 2011
The University of Manitoba and Ducks Unlimited enlist the ecological services of one of North America’s largest freshwater wetlands. A fly-over Google Earth tour of the area prepared by the International Institute for Sustainable Development shows a huge delta marsh where the silt-laden Red River of the North flows into Lake Winnepeg.
The Netley-Libau Nutrient Bioenergy Project turns wetland plants to into bioenergy and recovers agricultural phosphorus while protecting water quality in Lake Winnepeg, the tenth largest freshwater lake in the world.
Using Cattail (Typa spp..) for Biomass Feedstock
The Red River delivers loads of runoff agricultural fertilizer to the marsh, which grows thick, fast-growing stands of cattail. The Bioenergy Project harvests the cattail using implements adapted to soggy marsh soils. The cattail is dried and pelletized and burned as fuel. The ash contains residual phosphorus and other minerals that can be recycled as fertilizer to be used back on the farm.
The Net Primary Production per unit area of earth surface in freshwater marshes ranks right up with estuaries and tropical rain forests.
Besides harvesting plants to burn for energy, the project removes phosphorus from the Lake Winnepeg system. Eutrophication, or nutrient enrichment, especially by phosphorus, stimulates aquatic plant growth and sets a lake up for for high biochemical oxygen demand. When short-lived algae proliferate and die and decay, dissolved oxygen levels plummet, resulting in fish kills and other problems. Low oxygen levels at the water-sediment interface can cause the release of more phosphorus by chemical reduction of iron-phosphate compounds.
Here is an August 19, 2011 MODIS satellite image Lake Erie with a showing a massive algal plume (bright green) in the western basin. Western Lake Erie has had problems with anoxic “dead zones.”
I’m glad see a wetland harvesting program take off. Harvesting is always somewhat controversial in that it has the potential to damage nests and disturb other wildlife. Timing is important. It will be interesting to see if the economics of the project are deemed favorable enough to keep the project going and inspire others elsewhere.
More information is available on the global status of freshwater lakes from the World Lake Database and International Lake Environment Committee Foundation