Washington, Jan 10 : A team of researchers has found potentially dangerous levels of mercury and arsenic in Lake Baiyangdian, which is the largest lake in the North China Plain and a source of both food and drinking water for the people who live around it.
Led by biologists from Dartmouth College in New Hampshire, US, the research involved the study of three separate locations in Lake Baiyangdian, all at varying distances from major sources of pollution, such as coal emissions, agricultural runoff, and sewage discharge.
The team found concentrations of arsenic and mercury in the fish, which was well above the threshold considered by the U.S. Environmental Protection Agency (EPA) to pose a risk to humans and wildlife.
"For example, we saw arsenic levels in the water that represent more than fifty times the EPA-recommended limit for consumption of fish and shellfish," said Celia Chen, a research associate professor of biological sciences.
In their previous work, the researchers found that when there is a lot of algae present, mercury and arsenic are biodiluted, or more dispersed, so zooplankton that eat the algae are exposed to lower levels of the metals and transfer less to fish.
They also found that more nutrient-rich environments supported larger algal blooms, which resulted in lower concentrations of mercury and arsenic in the water due to uptake by the algae.
"Despite this potential interaction - a decrease in bioaccumulation due to high algal biomass - the mercury and arsenic in this system are high enough to be of concern to humans and wildlife that drink the water and consume fish," said Celia Chen, a research associate professor of biological sciences.
"It's important to study this system because it is typical of many throughout China where human activity and industrialization are having detrimental effects on the environment with major human health implications," he added.