Recently, the underground sewage to start the investigation from multiple local governments from the network broke the news, the evidence is that the underground sewage enterprises regardless, groundwater pollution is a serious Chinese the indisputable fact. In this connection, "environment and life" magazine reporter interviewed our country hydrology water resources expert, Chinese Academy of Engineering academician Wang Hao.

Academician Wang Hao

60% of groundwater pollution is serious in our country

Environment and life: you are an expert in the study of groundwater. Can you tell me something about the present situation of groundwater in China?

Wang Hao: more than 1 billion 500 million people around the world rely mainly on underground water for drinking water. Groundwater resources in China account for 1/3 of the total water resources in China, maintaining 70% of the population's drinking, 40% of farmland irrigation and 38% of the industrial production.

Groundwater is suffering more and more serious pollution because of the discharge of industrial wastewater and domestic sewage, the use of excessive chemical fertilizers and pesticides, the leaching of landfills and the leakage of underground oil tanks. Experts at the geological survey of China pointed out that 90% of China's groundwater has been polluted in varying degrees, and 64% of them are seriously polluted.

In the 1 million 970 thousand square kilometers of the national water resources survey, shallow groundwater in plain area, groundwater pollution is most serious in Taihu, Liaohe River, Haihe River and Huaihe river.

Chemical fertilizers and pesticides lead to "three nitrogen" (ammonia nitrogen, nitrate and nitrite) in groundwater. Nitrate nitrogen in groundwater has been exceeded in all provinces and cities of the Yangtze River delta.

Organic pollution still exist in groundwater pollution, the relevant departments of the domestic investigation and assessment of groundwater pollution, the general detection of trace organic compounds in different degrees, the detection of carcinogenic, teratogenic and mutagenic "three letter" substances, these substances are not easy to be water microbial degradation, but easy to be absorbed by organism, through the food chain to the human table on. Groundwater in Beijing, Tianjin, Hebei and other places has detected more than 100 kinds of pollutants, many of which are "three chemicals".

In recent years, a large area of groundwater funnel has been formed in groundwater due to the large amount of underground water overdraft. Therefore, the ground water intrusion to ground water is even more serious. The official report shows that North China, groundwater reached 120 billion cubic meters, equivalent to 200 Baiyangdian water, declining groundwater levels, so that in the North China Plain, forming a huge funnel of groundwater zone. In these areas, sewage will not only pollute shallow ground water, but also make deep groundwater easy to be polluted with the shallow sewage flowing continuously.

In a word, the groundwater pollution in China has evolved from point to surface, from east to west, from urban to rural areas, and from local to regional.

The agricultural industry, the human body, is the victim

Environment and life: what harm does this kind of groundwater pollution cause?

Wang Hao: first of all, directly affect the quality of drinking water sources. Groundwater contamination after the high hardness, as a source of drinking water is not only a bitter drink, but also cause gastrointestinal disorders, vomiting, diarrhea, bloating and other symptoms; when the groundwater is polluted, often caused by the change of nitrogen content of three water, three if the nitrogen content in the water is too high, will be on the human body (especially infants) harm, acute poisoning caused by nitrate. The three nitrogen in the human body under certain conditions will be converted into carcinogenic nitrosamines, leading to cancer and even death. In addition, if the groundwater is subjected to serious organic pollution or even heavy metal pollution, the "three chemicals" produced in the water body will cause greater harm to human health. In recent years, the emergence of cancer villages in Taihu, Chaohu and other places has aroused widespread concern about the relationship between water pollution, environmental factors and cancer incidence.

Secondly, in the field of food safety research, the influence of irrigation water pollution on the quality of agricultural products is also one of the hot topics.

Moreover, in our country, especially in the northern areas, groundwater accounts for a great proportion of industrial production water, and the pollution of groundwater will seriously affect industrial production. Groundwater hardness increased, will make the boiler and pipe wall scaling, not only a waste of fuel, but also directly affect the service life of the boiler and even cause explosion; on the textile printing and dyeing industry, washing products with high hardness water, not only will consume a lot of lotion, and produces inferior or waste; in addition, the high hardness of groundwater will cause harm to many chemical industry, pharmaceutical, brewing, power, papermaking etc.. This has forced some industries to soften and purify hard water, thereby increasing production costs.

Finally, the pollutants discharged into rivers, lakes, in addition to water in natural fish and water biological hazards, excessive nitrate will make river lake acidification and corrosive, affecting the normal growth of biological water, some water can even cause extinction.

The treatment mode of sewage and waste water is improper in our country

Environment and life: what role does underground sewage play in the present situation of groundwater pollution in China?

Wang Hao: the government departments have adopted corresponding policies for the standards of enterprise sewage and wastewater treatment to minimize the negative impact on the environment by industrial development.

However, some unscrupulous companies are those containing toxic carcinogens to degradation (e.g. to degradation of arsenic and mercury and other heavy metals and polycyclic aromatic hydrocarbons) industrial sewage waste discharged into the ground, brazenly. In addition to dig pits, infiltration wells steal exclusive, in order to avoid the investigation, some polluting enterprises will be a large number of sewage directly into the underground high pressure pump, some companies even south of the sewage will be discharged into the underground cave.

For example, the cadmium pollution incident in Guangxi, which caused great uproar in February 2012, was caused by the emission of cadmium pollutants from the caves through two caves.

Through the seepage pits, wells sewage is sewage this method provides It is often seen., low cost, surface water infiltration and easy operation conditions. The sewage often seeps through underground aquifers, such as sand, gravel and rock, where the upper layer of groundwater is well permeable, resulting in groundwater contamination.