Study On Soil-Environmental Capacity In Main Soil-types Of Shandong Province

With the development of industrial and agricultural , soil pollution of heavy metals is growing seriously and mankind is faced with the problem of soil-environmental capacity. How to correctly recognize and rationally take use of the limited soil-environmental capacity, has become widespread concern. In order to know the bearing capacity of the soil environment, it is essential to do some relevant research for the output process of heavy metals in the soil and soil-environmental capacity.In this paper, the cinnamon soil, fluvo-aquic soil and brown soil of the main soil-types in Shandong Province were studied. Environmental capacity of heavy metals in soil of different vegetative types were studied through field investigation. And the output coefficient, thresholds and environmental capacity of heavy metals contamination in the main soil-types of Shandong Province were also studied through the simulation experiments. It can provide technical support and scientific basis for environmental quality assessment and the total amount control of pollutants, strengthening management of environmental science, protecting the balance of ecological environment, improving the productivity of agricultural soils and the protection of human health.1. Pot experiment results showed that: the dry weight and fresh weight of leaf and root of the Chinese cabbage in cinnamon soil, fluvo-aquic soil and brown soil reduced along with the increasing of Cu, Zn, Pb, Cd. The production of Chinese cabbage significantly reduced when Cu was 100 mg·kg-1, Zn 100 mg·kg-1, Pb 50 mg·kg-1 and Cd 10 mg·kg-1. The critical value of Cu,Zn,Pb,Cd in cinnamon soil respectively were 117.30,151.35,126.39 and 0.58mg.kg-1;In fluvo-aquic soil respectively were 121.32,190.32,135.26 and 0.81mg·kg-1;In brown soil respectively were 55.13,134.05,93.11 and0.36mg·kg-1. Among the three soils, the threshold of Cu, Zn, Pb, Cd were: fluvo-aquic soil > cinnamon soil> brown soil. The absorption coefficient of Chinese cabbage for Cu, Zn, Pb, Cd were less than 1, no enrichment. 2. Leaching experiment results showed that: the amount of leaching of Cu, Zn, Pb, Cd increased with the addition of heavy metals in the three type soils, reducing with the increase of leaching Views. The total leaching out trend of the four heavy metals were: brown soil > cinnamon soil> fluvo-aquic soil. The leaching coefficients of fluvo-aquic soil were the smallest and brown soil largest. The validity index of Cu, Zn, Pb, Cd in the three type soils were much higher than CK, and increased with the added heavy metals . The validity index of Cd was the highest in the same soil.3. The runoff migration coefficient of heavy meatals were closely related to soil erosion of the study area, the heavy metal content of runoff away compared to the amount taken away by soil erosion, were almost negligible. Take the background value of heavy metals in soils for example, the migration coefficient of cinnamon soil was 2.72%, fluvo-aquic soil 1.18% and brown soil 2.29%.4. The average dynamic capacity of Cu, Zn, Pb, Cd was bigger than the average static capacity in main type-soils of Shandong Province, showed that the soils not only has certain capacity in the scope of environmental thresholds, but also has certain capacity by plants absorption, leaching, runoff migration and self-purification of the soils. Soils static capacity and dynamic capacity are related with soil environmental quality standard and background value of heavy metals. Dynamic capacity is also related with control period, the age is longer, the average dynamic capacity is smaller, but the total capacity of dynamic is bigger.5. According to the characteristics of vegetation in Shandong Province, Vegetation are divided into five main types :crops, forest trees, shrubs, grassland, meadow and marsh plants ,and environmental capacity of heavy metals in soil of different vegetative types were studied. The results shows that both of the static and dynamic capacity of Cu, Zn, Pb, Cd in soil of crops are the smallest ; the average dynamic capacity in soils of different vegetative types is 7-20 times of the static capacity.