Lake Superior Nitrate Levels
Nitrate levels in Lake Superior, which have been rising steadily over the past century, are 2.7 percent closer toward making the lake's water unsafe to drink, according to University of Minnesota researchers. The new study was published in the journal Geophysical Research Letters.
The complexity of the causes underlying the increase makes it difficult to predict when the water could become unhealthy. The trend is a concern because Lake Superior contains 10 percent of the Earth's supply of surface fresh water.
Everyone is exposed to harmless amounts of nitrate from eating fruits and vegetables; nitrate contamination of drinking water can expose people to harmful levels. Too much nitrate can reduce blood levels of oxygen, which poses a risk to infants and children or adults with lung or cardiovascular disease. Consuming excess nitrate over long periods of time is also suspected of causing cancer.
A compound made from nitrogen and oxygen, nitrate is a component of agricultural fertilizers and is generated by fossil fuel combustion. Nitrate levels in Lake Superior have increased five times since the earliest measurements in 1906.
June 6, 2007 6:39 AM | Category: Lake Superior