Study On Distribution And Collective Characte Of The Main Heavy Metal In Paddy Soil, Rice And Sweat Grain

Based on the statistical data of 147 samples obtained from Sichuan province (52 paddy soil, 50 wheat and 45 rice grain), the amount, as well as the central tendency and macro attribute of the heavy metal which distributed in the grain of both rice and wheat were studied. The results indicated:The accumulation of the heavy metal in the wheat grain showed the same tendency at the mining area of the west of Panzhihua city, and at the Chendu plain and the mountain country around. The accumulation amount of heavy metal in the grain of both rice and wheat increased with the increasing of that in paddy soil planted, among which the most accumulation were Cd, Cu, Hg, Zn, Ni, the absorbing indices was 7.12, 16.17, 7.48, 5.17, 1.14; 5.02, 19.10, 6.30, 7.41, 1.20 respectively. And these accumulation effects in the mining area of the west of Panzhihua city were much higher than that in Chendu plain and the mountain area around as for the Cd, Cr, Cu, Hg, Pb and Zn.Zn accumulation showed the highest amount in both of rice and wheat, varying between 12.43-98.55mg/kg.While it was lowest as for the Hg, which the accumulation level changed from 0.034-0.160mg/kg; And the total accumulation followed the order of Zn > Cu >> Pb, Ni > Cr, Cd > As > Hg. Generally, to As, Cu, Zn, Ni the amount in wheat was higher than that in rice, while it displayed the reverse effect when it came to Cd, Cr, Hg, Pb.The pH did a significant influence on the transport of heavy metal in soil and the absorption of heavy metal by soil. The lower pH caused the more accumulation of heavy metal in soil, impeding the transport of heavy metal from soil to plant. As well, the Absorption coefficence increased with the increase of the soil pH, resulting in the leaching, precipitating, and the transport of heavy metal out from the soil. And these indices were the highest in alkali paddy soil.The positive significant correlation was found between the amount of Cd, Cu, Pb, Zn and Ni in the rice grain and that in soil, and there exist some low positive correlation between As and Cr, indicating that the accumulation of heavy metal in the rice was mainly ascribed to the environmental behavior such as transport of heavy metal in paddy soil. As for the wheat,the good correlation was also found, and the accumulation of the heavy metal studied could also be ascribed to the heavy metal environmental behaviors in soil.But there exist some imposstive correlation as for Hg.