Expert: Underground sewage is the culprit of groundwater pollution in my country

Recently, the underground sewage has been exposed from the Internet to the government of many places to launch relevant investigations, regardless of whether the evidence of underground sewage discharge by enterprises is solid, China's groundwater pollution is serious is an indisputable fact. On this issue, the reporter of "Environment and Life" magazine interviewed Hao, an expert in hydrology and water resources in China and academician of the Chinese Academy of Engineering.

Academician Hao

Sixty percent of China's groundwater is seriously polluted

Environment and Life: You are an authoritative expert in groundwater, can you introduce the current situation of groundwater in China?

Hiroshi: More than 1.5 billion people around the world rely on groundwater for drinking water. China's groundwater resources account for 1/3 of the country's total water resources, maintaining 70% of the country's population to drink, 40% of farmland irrigation and 38% of industrial production.

Groundwater is suffering from more and more serious pollution due to the discharge of industrial wastewater and domestic sewage, the use of over-quantified fertilizers and pesticides, the leaching of garbage dumps and the leakage of underground oil tanks. Experts from the China Geological Survey once pointed out that 90% of China's groundwater is polluted to varying degrees, and 64% is seriously polluted.

Among the shallow groundwater in the 1.97 million square kilometers of plain area evaluated by the national water resources survey, groundwater pollution is serious in the basins of Taihu Lake, Liaohe River, Haihe River and Huaihe River.

Fertilizers and pesticides cause excessive "three nitrogen" (i.e. ammonia nitrogen, nitrate, nitrite) in groundwater. All provinces and cities in the Yangtze River Delta region found that nitrate nitrogen in groundwater exceeded the standard.

There is also organic pollution in groundwater pollution, and the relevant domestic departments have investigated and evaluated groundwater pollution, and generally detected trace organic matter, and different degrees of carcinogenic, teratogenic and mutagenic "three-cause" substances have been detected, which are not easy to be degraded by microorganisms in water, but are easily absorbed by organisms and returned to the human table through the food chain. More than 100 pollutants have been detected in groundwater in Beijing, Tianjin, Hebei and other places, many of which are "three-caused" substances.

In recent years, due to the large amount of groundwater overextraction, a large area of groundwater funnel has formed in the ground, which has further aggravated the backflow of surface sewage to groundwater. According to the official report, the groundwater overextraction in North China reached 120 billion cubic meters, equivalent to the amount of water in 200 Baiyangdian, and the continuous decline of the groundwater table has formed a huge groundwater landing funnel area in the North China Plain. Discharge in these areas not only contaminates shallow groundwater, but also becomes vulnerable as shallow sewage continues to flow deeper into the groundwater.

In short, China's groundwater pollution has shown a trend of evolution from point to area, from east to west, from urban to rural, and from local to regional.

Agriculture, industry, human bodies are victims

Environment and Life: What harm will such groundwater pollution cause?

Hiroshi: First of all, it directly affects the quality of drinking water sources. After the groundwater is polluted, the hardness is too high, as a source of drinking water, it is not only bitter and difficult to drink, but also causes gastrointestinal disorders, vomiting, diarrhea, flatulence and other symptoms; When groundwater is polluted, it often causes changes in the content of trinitrogen in water, and if the content of trinitrogen in water is too high, it will cause harm to the human body (especially infants) and cause acute nitrate poisoning. Trinitrogen is also converted into causes under specific conditions in the human body