Heavy metal pollution remain a major challenge
Thứ năm, ngày 18 tháng 04 năm 2013 cập nhật lúc 04:19
Currently, in addition to focal pollution causes (radioactive materials, biological pollution, plant protection chemicals, etc.) heavy metals contamination by such chemicals as As, Pb, Cd, Hg, Cr emissions from increasing, industrial and mining activities are posing a major challenge for developing countries like Vietnam. Hazards stemming from heavy metals are increasingly threatening to the soil, water and air environment, while solutions are only restricted top temporary measures.
The risk of probable pollution
Vietnam is a country with agricultural economy, but the development of infrastructure has been outweighed the growth in industrial activities. At present, all industries pour directly untreated waste into the environment, which results in the fact that heavy metals and toxins are the typical components of industrial waste. According to scientists, heavy metals are metals with molecular weight larger than 52 (g), including copper, iron, lead ... These type of metal derived from waste water in agriculture, industries as well as in nature, creating a risk of potential pollution, threatening ecosystems, agriculture, industry and reducing the quality of the natural environment and human habitat.
Heavy metal pollution in the country has reached alarming levels. According to the results of environmental monitoring and analysis, the volumes of copper, lead, cadmium and cobalt in the coastal waters near residential areas and and major industrial zone are greater than their natural levels in seawater. In particular, copper and zinc concentrations exceeded the average level, and mercury, though not yet reached "pollution", have reached allowed level. Water pollution is a pressing problem in such big cities as Hanoi, Ho Chi Minh City. Hai Phong, Da Nang, Hue, Nam Dinh, Hai Duong; of which the main reason is due to the "free" discharge industrial zones and plants areas.
As reported by the Ministry of Natural Resources and Environment, Water in Dong Nai, Cau, Nhue and Day rivers was contaminated. The survey results showed that nearly 70% of more than one million m3 of wastewater before treatment from industrial parks (IPs) were discharged directly into the receiving water per day causing environmental polluting. Meanwhile, the percentage of Industrial Parks with centralized wastewater treatment station accounts for only about 43%.
Contaminated soil environment containing heavy metals comprises hidden harm to organisms and human health.
In HCM City, the results of the analysis of heavy metal pollution in the soil for rice cultivation area to south of the city reveals that the content of copper, zinc, lead, mercury, chromium in paddy land was directly influenced by the water from industrial parks, which was similar to or higher than the threshold for the use of land for agricultural purposes. Particularly, the cadmium content is 2.3 times as much as the standard level while cream exceeds 1.76 times. Hanoi and many other localities are facing soil pollution due to waste caused by manufacturing and agriculture activities.
Application of complex biological systems – the positive signal
One of the challenges in Vietnam at present there is the lack of a completed treatment model of heavy metal pollution which can achieved technical, economic, social and environmental criteria. Treatment process of heavy metal has been so far limited within the chemical methods, in which chemicals are used to increase the redox reaction. The oxidizing catalysts that are often used include ozone, hydrogen peroxide, and chlorine dioxide hypochlorine. Reducing catalysts involve iron sulfate, sodium bisulfite and sodium hydrosufite, which transform pollutants into less polluting substances. Biological measures engage in the using of microorganisms to decompose pollutants by providing sufficient nutrients and air to them. However, these measures are only temporary and sporadic.
Early last March, the General Department of Environment (Ministry of Natural Resources and Environment) in collaboration with Loyola University Chicago and the Association of Chemical and Environmental Toxicology Asia Pacific Training Workshop organized the International Training Workshop on application of biological complexes (BLM) in environmental management. The application of this model is considered as a positive sign of the effort of our country in the process of handling heavy metals pollution.
T.Minh
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