| Most of the the heavy industry enterprises in Lanzhou are locatde in the upper ar ea of the Yellow River with provides direct irrigation to the vegetable cultivation regi on. This paper, bared on the vegetable cultivation bare with Yellow River direct irrigat ion,focuses on the principles of migration of heavy metal pollution in soil and vegetab les.In this paper, author passes has talcen tfield sampling analysis for two years, usin g the Nemero Comprehensive Pollution Index and the Geoaccumulation Index to asses s the status of soil heavy metal pollution. According to cole and lettuce as the researc h object, through the indoor cultivation experiment, study of Cu and Pb element in th e rule of migration water-soil-vegetables is carries out. Through the research, it is fou nd:1. According to Cu and Pb element background values in soil element in Gansu province of the arithmetic average value, the contents of Cu element in the three sam ples are higher than the standard, the contents of Pb element in the three samples me et the standard besides GaoTan village. According to Soil Environmental Quality Index of the Green Vegetables Planting Base of China, the contents of Cu and Pb elements meet the requirement. Through count Nemero index and grading standards, soil envir onmental quality belongs to the light pollution in direct irrigation area of the Yellow River in Lanzhou; the pollution level is value of soil pollution more than the backgro und; crops have been contaminated. Through the classification standard of Geoaccumul ation Index, the soil is not polluted with Cu element and grading standard is zero. Th e Pb element has been accumulated in GaoTan village, which belongs to one class.2. According to the analysis and research on vegetables and the food pollution li mits, the elements of Cu and Pb never exceed the standard.3. In the indoor cultivation experiment, with the single condition, Cu element in t he soil reaches the maximum value when the Cu element of irrigation of water is25Omg/L; the enrichment ability of soil is Cu①>Cu②>Cu③only concentration of the Pb element is50mg/L in water, and Pb elements in soil are higher than the backgro und value of soil element. When Cu and Pb elements are combined action, the Cu an d Pb elements in the soil are lower than condition of single element.4. When the single condition, Cu or Pb element content in the concentration of c ole and leaves of vegetable increases with Cu or Pb element increasing in the water. When the Cu and Pb element is combined action, Cu element content in rape leaf inc reases with increasing Pb element in water; Pb element content in rape leaf increases with increasing Cu element too. Cu element content of lettuce leaves decreases with i ncreasing concentration of Pb element in the water; Pb element content of lettuce leav es decreases with increasing concentration of Cu element too.5. According to calculate the ability of accumulation and migration, capability of accumulation is:single condition> composite conditions>field sampling. With law of conservation of mass, in order to cole cases were calculated, this found that the Cu el ements from the outside\accumulate in the soil about76%, and accumulated mainly i n the upper soil (0-3cm). Cu element enrichment in vegetables only holds Cu element s in total quality about0.0076%. According to the results of calculation leaching loss ratio of the soil profile, degree of migration of Cu elements in soil decreases with the deepening of the soil. |
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