| Arable land per capita in China is small,in contrast,the overall situation of soil pollution is quite serious.On the basis of the bulletin of the national soil pollution investigation announced by the Ministry of environmental protection and the Ministry of land and resources on April 17,2014,16.1% of soils are polluted,that for the soils of cultivated land was 19.4%.Abandoned industrial and mining area’s soil environmental problems are prominent.The soil contaminated by 8 kinds of inorganic pollutants including cadmium,mercury,arsenic,copper,lead,chromium,zinc,nickel,are 7.0%,1.6%,2.7%,2.1%,1.5%,1.1%,0.9%,4.8% respectively.The soil pollution caused by mining activities in northern Guangdong province is serious.Because of lead and zinc mining pollution in Wengyuan county,Lechang county and other places,many farmlands for several kilometers alongside rivers has been contaminated seriously.Guangdong is one of the six pilot provinces for heavy metal pollution control nationwide.The heavy metal pollution assessed recently in Guangdong province is similar to what was previously expected,according to the results of a soil pollution survey completed by the environmental protection department of the province.In other words,heavy metals contamination in agricultural products poses a serious threat to our food safety.China is a country short of agricultural land resources,the heavy metal contaminated soil urgently needs to be remediated,with the economical and efficient remediation techniques and models,especially suitable to the polluted farmlands in Guangdong province.In this paper,different crop varieties were planted in the field.The yield of crops,the concentration of heavy metals and the concentration factors of heavy metals in edible parts were taken as important reference indexes.The low accumulating varieties were selected from several vegetables,such as Chinese flowering cabbage(Brassicaparachinensis),eggplant(Solanum melongena)and rice(Oryza sativa).Then combined with selenium fertilizer,soil conditioner to further reduce the ability of crops to absorb heavy metals.This provides scientific basis for soil remediation and safe agricultural production in polluted areas.The main results of this paper are as follows:(1)The field experiment of selecting low accumulating eggplant varieties showed that there were significant differences in the fruit contents of Cd and Pb among different varieties.In Zengcheng experimental area(unpolluted)and Shaoguan experimental area(medianly polluted),there were 4 varieties which fruits could meet the food standards.Among these varieties,DTSH was the typical low accumulating variety of eggplant.(2)The field experiment of selecting low accumulating cultivars of Chinese flowering cabbage showed that,in Zengcheng experimental area(unpolluted),Shaoguan experimental area(medianly polluted)and Baiyun experimental area(slightly polluted),there are 2 varieties that can meet the food standards of Cd and Pb in the aboveground parts.Among these varieties,LGL is a variety with high yield and lower accumulation of Cd and Pb.It was also found that the contents of heavy metals in edible parts were related to the growth duration of the plant.The longer the plant grew,the higher the contents of heavy metals were in the vegetable.(3)The field experiments studying the effect of selenium fertilizer on the heavy metal contents in Chinese flowering cabbage showed that the application of selenium fertilizer could inhibit the absorption,transport and accumulation of Cd in its aboveground parts,significantly reduce Cd in its stems and leaves.(4)The field experiment of selecting low accumulating rice varieties showed that the ability of rice to accumulate Cd and Pb was different among different varieties.ZZX is a variety with low Cd accumulation as shown in Baiyun experimental area(slightly polluted).(5)The field experiment applying soil conditioner showed that the accumulation of Cd in rice significantly reduced by the application of zeolite conditioner. |
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