Study On The Distribution And Influencing Factors Of Soil Se Of Jiangjin District, Chongqing Municipality

At present, it is very hard to confirm that the Se is one of the necessary nutrient elements for human and animals. A lot of studies suggested quite unequivocally that the Se play a very important role in the growth of plants and animals. The animals are easy to develop the disease like white myopathy and the human are easy to have risk factor to Keshan disease and Kashin-Beck disease without Se. However, under the influence of high concentration of Se, the growth of crops and animals can also be influenced. Which may decrease the production of yields and result in the abnormity of embryonic development. Therefore, no matter lack in Se or rich in Se, it will ultimately affect growth and reproduction of organisms. Soil is the main source of Se. From the historical data, Chongqing is the key area of Se deficiency in our country. Expecially, the Purple soil that mainly distribute in the southwest of China is classified as " very low Se" soil type in the history. And from the existing research materials, there has a few studies about the distribution and content of Se and corresponding influencing factors in the Purple soils. Accordingly, the goal of this work is to conduct a research on the Se in Purple soil of Jiangjin district, Chongqin municipality. The content of Se in the soils, crops and water was measured. And the effects of soil conditions and trace elements on the forms of Se were analyzed. Major results obtained are summarized as follows:(1) According to the results of determination of 3880 soil samples, agricultural soil Se content in Jiangjin mainly at the middle level, where 90.2% above the level of Se (>0.2 mg/kg) of the total sample of soil, accounting for 9.74% of low Se soli. The spatial distribution of agriculture soil Se was "spoon-shaped", that is, low middle, to the surrounding showed increasing trends.(2) Among the agricultural products in Jiangjin,56% rice samples reached Chongqing Se local standards (0.05～0.30 mg/kg),and75.3% to the national Se standards (0.05～0.30 mg/kg).76.4% beans samples reached the level of Se standard, where in the average highest Se content of soybean, mung bean lowest average content of Se. On the Se content distribution, pepper Se level was significantly ribbon distribution,that is, with eastern and south to peripheral expansion showed a gradual increasing trend; beans and rice patchy distribution, low overall height of the north to the south.(3) 140 soil samples in Jiangjin were analyzed and in the Purples soil, the total Se content to an average of 0.29 mg/kg, the average content of water-soluble Se was 1.79 μg/kg, the average content of Olsen-Se was 17.8μg/kg. There were obvious correlation between total Se and water-soluble Se, Olsen-Se, the correlation coefficients were 0.415**、0.61**.(4) The Se content in water were analyzed, and the average content of Se in water was 0.3235 μg/L. The average content of Se was 0.4 μg/L, in groundwater and 0.247μg/L in surface water. There was a large change of the Se content between different villages.(5) The basic properties of soil was closely related to the total Se, water-soluble Se and Olsen-Se. Different soil parent material development levels of the soil is different, the change of total Se order:J1-2z>B2j>J2s>J3p>J2sn; change the order of the water-soluble Se:J2sn>J3p>J1-2z> B2j>J2s; Olsen-Se content change order for:J2s> B2j>J1-2z>J2sn>J3p.Industrial development has a certain effect on the accumulation of Se in soil, more than three times the total Se content of the soil parent material of the same industrial zone in the soil total Se content in non-industrial areas.(6) Analysis of this research:the basic soil physical and chemical properties of soil selenium enriched the stranded, at the same time also limits the selenium dissolved suck. Soil parent material, soil pH, organic matter, heavy metal, using factors such as the way is the selenium content in agricultural soil level, distribution, migration and enrichment of the important factors.(7) There is a definite relation between the total Se, a water-soluble Se, Olsen-Se and heavy metals, as compared to the total amount of metal, metal and selenium effective correlation between the more significant. Among effective metals, effectively lead and different forms of selenium are closely linked.