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Fri October 25, 2013
NC Scientist Visits China To Study Toxic Green Slime
The common blue green algae found on local waterways has bloomed into an unprecedented event in the Taihu basin. We speak with North Carolina scientist Dr. Hans Paerl about his research trip to China and what we can do to prevent cyanobacteria from proliferating in eastern North Carolina.
Green algae slime. It’s common to inland waters and estuaries of eastern North Carolina. But in China, the concentration of cyanobacteria, also known as blue green algae, has become toxic and is compromising drinking water and harming the ecosystem. A North Carolina scientist at the University of North Carolina’s Institute of Marine Sciences in Morehead City recently returned from the Taihu basin in China where he studied the cause of a massive algae bloom and how to eliminate it.
“Lakes like Lake Taihu basically serve as sort of a looking glass as for what might be ahead in many instances here, as well as in Europe and other developing countries.”
Professor of Marine and Environmental Sciences Dr. Hans Paerl led an international team of researchers on the two week trip earlier this month. Dr. Paerl was awarded two National Science Foundation grants, totaling $2.5 million, for the research project which focused on controlling the amount of nutrients entering a body of water. The excess nutrients cause widespread algal blooms like the one in Lake Taihu, the third largest lake in China.
“It will allow us to use nutrient management strategies here as well as in Europe and more intensely populated regions.”
While China is booming both economically and agriculturally, there are negative impacts to the fast pace growth. The rapid development of cities, increased use of fertilizers in agriculture, and a favorable climate contribute to the epidemic of algae blooms in large lakes and reservoirs across China.
“They form these paint-like scums that cover the water, they’re often bright green, it looks like someone just spread paint on top of the water and they cause lots of water quality problems including toxicity they produce chemical compounds that are toxic to a variety of animals including man.”
The algae can cause liver cancer and damage to the nervous system. Blue green algae is common to rivers, lakes and coastal bodies of water. But when phosphorus and nitrogen are introduced at high concentrations, the algae rapidly multiply and cause a pea soup green cover.
“They more or less act like cockroaches they take advantage of even tiny trickles of nutrients that come in and when nutrient loads become very heavy, they just basically take over. And you and I know how difficult it is to get rid of cockroaches once they develop in your house and the same situation exists in blue green algal blooms in lakes, once they’re there they are very difficult to get rid of.”
Nutrients are introduced to the environment in a number of ways such as discharged waste water, agriculture, runoff from municipalities, and soil erosion. Dr. Paerl says the only long term solution is to reduce the amount of nitrogen and phosphorus that is being introduced into the body of water. Part of the research in China involves identifying which nutrients are a problem, and how much they need to reduce the nutrient load to begin restoring present blue green algae to normal levels.
“This lake supplies drinking water for about 20 million people living in that basin. So the stakes are very high obviously if these lakes get contaminated by these toxic blooms it basically means that the drinking water supply is cut off.”
In 2007, an algae bloom polluted Lake Taihu forcing the Chinese Government to deliver water to millions of people in the region. When the blue green algae is consumed either by drinking or eating fish from infected waters, Dr. Paerl says it can cause damage to the nervous system, liver, and intestines.
“The other group of toxins that they produce are called neurotoxins and they can affect your nervous system and lead to things like Alzheimer’s-like responses in people that are intoxicated with water that is contaminated with these blooms. The liver toxins are a particularly bad problem because they can accumulate over many years of drinking this contaminated water and lead to liver cancer. In China, it turns out, has very high rates of liver cancer which we think is related to the drinking water supplies that are contaminated by these toxins.”
In addition to health problems, blue green algal blooms also have impacts to wildlife and the ecosystem.
“They also cause problems with regard to food chain in the waters that they bloom in because they’re not eaten very easily by organisms that depend on algae as a food source, so they kind of put a wrench into the food web as well. And lastly, when they form very large blooms, like some of the blooms we’ve actually seen in North Carolina, when they die they sink to the bottom and that leads to a lot of oxygen being consumed in a very short period of time leading to these low oxygen events that can lead to fish kills.”
North Carolina is all too familiar with the “green slime.” During the early 1980’s, a warmer-than-normal summer and high nutrient loads of nitrogen and phosphorus caused a blue green algae bloom in the Neuse and Chowan Rivers.
“The entire river was coated with these blooms. And I remember actually seeing them all the way from Streets Ferry to New Bern. I’m sure that some of the old-timers remember some of these paint-like scums and blooms that we had on the Neuse.”
Dr. Paerl’s recalls his first project when he arrived at the Institute of Marine Sciences in Morehead City was to help the state develop nutrient management strategies to eliminate the algae. By reducing the amount of phosphorus and nitrogen being introduced into the Chowan and Neuse Rivers, Dr. Paerl says they were able to get the blue green algae under control. He hopes that some of the same techniques can be used to solve China’s current “green slime” problem.
“I’m somewhat optimistic that we can do something about the nutrient situation in China because half the nutrient load is coming into these lakes coming in from major cities that are being developed on the lake. So if we can remove half of the nutrient input, we can probably see some improvements fairly quickly in terms of being able to stem these blooms and to try to reverse them.”
According to Dr. Paerl, global warming is causing blue green algae blooms to become more of a problem. Now more than ever, he says it’s important to what we can to reduce the amount of nutrients that enter a body of water, whether it’s China or here in eastern North Carolina. Dr. Paerl recommends some simple steps, like applying fertilizers sparingly.
“Many instances, you don’t have to apply fertilizers. There’s enough nitrogen coming in from rainfall and enough phosphorus in the soil to grow crops and grass. So reducing fertilizer input and applying fertilizers sparingly and wisely is a very good strategy.”
Some other tips to keep in mind: never dump yard waste in body of water, maintain your septic system, and if you live along a pond, river or lake, consider leaving an un-mowed area at the water’s edge to trap and filter out unwanted nutrients.
Dr. Paerl’s research has gained national attention by the Associated Press, the Washington Post, and the Huffington Post. And he’ll be interviewed today around 2:30 on Public Radio East’s New and Ideas during Science Friday about his research trip to China. Dr. Paerl frequents the Taihu region for research. His next trip is planned for Spring 2014. You can see photos of his last visit at our website, publicradioeast.org. I’m Jared Brumbaugh.
To see more photos of Dr. Paerl's research, click: http://www.flickr.com/photos/98039329@N05/sets/72157636655315194