New study reveals even more harmful materials found in plant runoff

A team of researchers from Chung-Ang University recently announced publication of a paper which sheds light on the seriousness of non-point pollution in the environment.

Non-point pollution refers to environmental deterioration of pollutants from urban residence, roads, farms and construction sites. It is created when rain falls or snow melts, with the runoff picking up and carrying topsoil, bacteria, fertilizers, pesticides, oil and many other toxic or harmful materials and depositing them into various water sources. It is so called because it is difficult to determine a single, polluting source. As land development accelerates and areas where water cannot permeate increases, such pollution is emerging as a new environmental challenge.

According to the Ministry of Environment, non-point pollution accounts for 30-35 percent of water pollution in South Korea; if environmental deterioration from decrepit sewage and untreated animal urine is included, the number could increase to 42-69 percent.

The team is led by Oh Jae-il, a professor majoring in Housing and Environmental Engineering, and conducted the research between 2004 and 2005, by analyzing the degree of pollution in runoff water collected from Yoenhyo Brigde, one of the bridges crossing the Han River.

The research showed that the chemical oxygen demand of the rainwater found on the Yoenhyo Bridge had been recorded at 2,232 ppm, more than 400 times higher than that found in the Han River, or 5 ppm, meaning that it was extremely polluted. When compared with industrial effluent cleared for disposal, the figure was more than 50 times higher.

Choi Yeong-hwa, a participating researcher, said, ‘‘It depends on how much rain falls, but in a typical 30-minute period, a significant amount of pollutants are washed away. We only saw clean water after two hours.’’

Among the pollutants, researchers found toxic materials such as lead, copper, cadmium and zinc, presumed to have leaked from the tires, breaks and gasoline of passing cars. The research team said that the runoff water collected by the research team was dangerous enough to kill 10 water fleas in just one to two hours.

Pathogenic microbes, potentially dangerous microorganisms, were also found in the water sample taken by the research team - the first time this kind of organism has been recorded in runoff water in South Korea. As many as 158 colon bacillus per milliliter were detected.

Professor Oh said, ‘‘So far, the focus has been on sewage and other basic environmental facilities without much tangible impact. This led us to turn our attention to non-point pollution. We have as many cars on the road as any other country, which surely pollute the run-off.’’

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