Currently, the world average annual emissions of about 15,000 tons H g , C u about 3.4 million tons , P b of about 5 million tons , M n of about 15 million tons , N i of about 100 million tons. According to the Chinese Ministry of Agriculture sewage irrigation nationwide survey showed that about 1.4 million hectares of irrigated water , and subjected to heavy metal contaminated land area accounts for 64.8% of sewage irrigated area, of which 46.7% slightly polluted land , accounting for moderate pollution 9.7% , 8.4% severe pollution , which contaminated area H g and C d is the maximum .
According to statistics, the country suffered varying degrees of contamination of arable land is close to 20 million hectares , accounting for arable land area of 1/ 5. China’s annual grain production due to heavy metal pollution caused more than 10 million tons , heavy metal contamination of food up to 12 million tons , the total economic loss of at least 20 billion yuan . After being adsorbed heavy metals in soil and plants accumulate through the food chain to humans and animals enriched body , thereby endanger human and animal health , cause cancer and other diseases, such as water Minamata disease , bone disease, etc. are typical examples.
Destruction of mineral resources , excessive use of agricultural materials , chemical industry emissions and other pollution caused by heavy metals in soil . The use of humic acid fertilizer, pesticides, mulch , insurance agent and other agricultural products to improve soil physical and chemical properties , and enhance the toxicity of metal tolerance, while increasing the absorption of heavy metals in the soil conditions gradually improved ; utilization of humic acid acidic, surface activity and network ( chelate ) together , reducing the soluble heavy metal content of the soil , reducing its liquidity ; humic acid but also because of the natural , environmental , pollution and other characteristics , can reduce or avoid the introduction of other chemical reagents , avoid secondary pollution.