Experts believe that this is closely related to Hunan's unique geographical conditions and historical industrial layout. In addition, the abuse of agricultural inputs, exogenous pollution, aquaculture pollution and other factors are also increasingly apparent.
Hunan is a famous "hometown of nonferrous metals" in China, and the background value of heavy metals in soil is high. In addition, the Xiangjiang River Basin has always been an important non-ferrous metal and heavy chemical industry intensive area in the central region, especially the non-ferrous metallurgy, chemical industry, mining and mineral processing industries with serious water pollution account for more than 80% of the province.
The economic layout dominated by heavy chemical industry makes the situation of heavy metal pollution in Hunan severe. In 2007 alone, Xiangjiang River Basin discharged 567 million tons of industrial wastewater and 90,000 tons of domestic sewage11. The content of heavy metals is particularly high, with mercury, cadmium, lead and arsenic accounting for 54.5%, 37%, 6.0% and 14. 1% respectively.
At the end of 20 12, the Hunan Provincial Department of Agriculture disclosed at the provincial conference on cultivated land quality that at present, the heavy metal pollution in the producing areas of agricultural products in Hunan Province has developed from mild pollution to severe compound pollution, from local pollution to regional pollution, and from urban suburbs to vast rural areas.
First, the polluted areas are widely distributed. The heavy metal pollution areas in Hunan province are distributed in "one line and two pieces", that is, the first line of Xiangjiang River Basin and two pieces of Xiangxi and Xiangnan.
Secondly, the pollution area of the producing area is large. According to preliminary estimation, in 2009, the cultivated land polluted by heavy metals accounted for 25% of the cultivated land area in the province.
The third is the serious pollution in the producing areas of agricultural products. 20 1 1, the application amount of agricultural chemical fertilizer reached 8,362,700 tons, the use amount of pesticides120,400 tons, and the use amount of agricultural plastic film was 75,900 tons. However, the seasonal utilization rates of main crops such as nitrogen, phosphorus and potassium are only 30%, 25.9% and 36.7% respectively, and the utilization rate of pesticides is only about 30%, so the recovery rate of plastic film is insufficient. This means that there will be1673,400 tons of chemical fertilizer (pure state), 84,300 tons of pesticides and1654,380 tons of plastic film residue in the soil every year, and the degradation time of agricultural plastic film in the soil will be as long as 20 years.
A person in charge of an agricultural science and technology company in Hunan Province said that the overuse of agricultural inputs in China has become a flood trend. Many chemical fertilizers and pesticides contain heavy metals, which will reduce the organic matter content in soil and destroy the self-regulation function of soil.
Some phosphate fertilizer, potash fertilizer and compound fertilizer can make soil and crops absorb heavy metals that are not easy to be removed, even organic fertilizer can not escape heavy metal pollution. In some small-scale farms, people often add arsenic preparation or copper sulfate to the feed of agricultural animals such as pigs and chickens, because this heavy metal can kill parasites in pigs, promote the growth of livestock, and may even "make pork more rosy".
How does cadmium rice flow to the dining table?
In the process of planting, land use is not divided; In the sampling inspection, the sampling inspection of Zhongmi small factory is like "the cowshed closes the cat". The content of heavy metals has not been included in the routine grain inspection items for a long time. Although some enterprises can conduct random inspections, they do not publish them and have no credibility.
"What do you mean by excessive heavy metals? We have never heard of it. " This is the media exposure at the end of February this year, Hunan rice cadmium exceeded the standard, when a reporter interviewed a farmer randomly in the field, his answer.
In fact, in the process of planting, due to the "pressure to increase production", many places in China simply did not divide land use. Until the cadmium exceeded the standard, the grain in the hands of farmers could not be sold, and innocent farmers still looked blank.
Li Xufang, a farmer from Shaling Village, Heshan District, Yiyang City, Hunan Province, told reporters that no one had ever told them whether their fields were still suitable for growing crops.
The existence of a large number of small and medium-sized millet factories makes it impossible to form a situation of "bullpen closed cats" even if strict sampling is carried out. Less than two kilometers away from Li Xufang's home, it is Lanxi Rice Market, the largest folk rice market in Hunan Province. More than 200 rice mills, large and small, produce more than 2 million tons of rice every year. Zhao, director of Shanling Rice Industry, said that although Yiyang conducts random inspections on various factories twice a year, the samples sampled each time are only about five or six kilograms.
"Hundreds of rice mills, you can do nothing. Excessive rice is not sealed, and if it is put aside, it will eventually be sold by the rice mill. As long as you get on the bus, there will be no more exams on the road. " Zhao said to him.
In addition, the content of heavy metals has not been included in the routine detection items of grain for a long time. Xue Fei Rice Industry Co., Ltd. is the largest rice processing enterprise in Zhuzhou City. A staff member of the company told the reporter that the company has no ability to detect heavy metals, and only detects common indicators such as fractions, impurities, yellow rice and broken rice. This year, after the media reported that the cadmium in Hunan rice exceeded the standard, they sent a batch of rice for heavy metal detection as required.
And some large enterprises with detection ability can not only detect whether the rice exceeds the standard, but also master the polluted areas in detail. But most of these data are "for internal reference only".
Xiangtan Junyi Ecological Agriculture Co., Ltd. conducted a thorough investigation on the area within 35km of the company's Fiona Fang some time ago, and the ratio of polluted area to unpolluted area was about 1: 6. "But we can't arbitrarily announce which areas are polluted." Chen Yimin, director of the company office, said.
"Mercury content is 0.008 mg/kg, cadmium has not been detected, and inorganic arsenic content is 0. 1 15 mg/kg, and the detection conclusions are all' qualified'" —— Peng Runchu, chairman of Hongde Agricultural Science and Technology Company, Junshanpu Town, Hanshou County, Hunan Province, dug out a copy issued by Hanshou County Quality Supervision, Inspection and Metrology Institute in May 20 12. However, despite holding the qualified report of heavy metal detection, the credibility of this report is greatly reduced due to the lack of comprehensive and accurate data from authoritative departments.
The data comes from: "How does cadmium rice flow to the dining table? 》
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