The Research Of The Distribution Characteristics Of Heavy Metals And The Environmental Capacity Of Fundamental Farmland In Shandong Province

The development of industry, urbanization and wide usage of agricultural chemicals lead to soil pollution of heavy metals. The serious soil pollution of heavy metals significantly reduces the quantity and quality of the agricultural output, which is quite harmful for human health. The study of the distribution of soil-environmental capacity of heavy metals and its dynamical behavior makes it possible for us to understand and effectively implement the limited soil-environmental capacity.Based on the existing materials and field survey, 60 sampling spots are selected in farmland Shandong Province, which covers the three main kinds of soils, brown soil, cinnamon soil and calcareous soil. The topsoil is collected from the 60 sampling spots and the availability and the whole volume of Cu, Zn, Pb and Cd in the samples are analyzed. With the materials on soil-background value and critical value, the characteristics of the soil-environmental capacity distribution of Shandong Province are studied and compared with the results in 1980's to capture the dynamic behavior. The objective of this research is to provide the basic data for the establishment of the soil-environmental quality standard, farmland watering standard, amount of sludge application and etc. This research works as a scientific basis for regional soil-environmental quality evaluation, soil pollution prediction, heavy metals total amount control, and etc.The main achievements of this research are summarized as follows:1.The 5 sampling spots in Fangshan of Qufu, Jiyang of Jinan, Wendeng, Haiyang, Zaozhuang, from the total 60 reach the National Secondary Standards; the others are lower than the standards. The Zn availability of one sampling spot in Yunshan Town, Pingdu City, Qingdao reaches the National Secondary Standards; the others are lower than the standards. The Pb availabilities of two sampling spots, Fangshan and Cangshan, reach the National Secondary Standards. The Cd availabilities of all the sampling spots are lower than the National Secondary Standards. The Cu availabilities of 10% of the sampling spots are lower than the Cu critical value, which means the farmland soils there are in a low fertility level. The Cu availabilities of 86% of the sampling spots are larger than or equal to medium fertility level. Thus, from the viewpoint of Cu availability, the farmland soil fertility is in a considerable level in totality.2.The soil heavy metal comprehensive pollution index of Shandong Province is 0.1051—1.4742. The research shows that 10% of the 60 sampling spots of interest are lightly polluted, and soil-environment qualities of 90% of the sampling spots are in good condition. Shanting of Zaozhuang, Ningyang of Taian, Fangshan of Qufu, Cangshan of Linyi, Jiyang of Jinan and Wendeng City take the largest value of the pollution indexes. The research result strongly motivates the control of soil pollution.3.In the past 20 years, Pb in farmland soil varied significantly, which especially in brown soil, has increased 5.81 times. Cd in cinnamon soil has changed the lest, and has increased only 1.33 time in the past 20 years. Brown soil is with the largest variation of the volume of the four heavy metals, followed by calcareous soil. In the past 20 years, the Cu availability in farmland soil in Shandong Province has increased a little. The Zn availability in the three kinds of soils has increased more than ten times. Human health is closely related to the availability, which should be highly respected.4.The sequence of the static environmental capacity is Pb>Zn>Cu>Cd in all three kinds of soils. The static environmental capacity of Pb in cinnamon soil is 528.21kg/hm2, which is the largest. The relative environmental capacity of Cu is not so large, and there are few high-capacity regions. The relative environmental capacity of Zn is comparatively large, and more than 2/3 of the sampling spots are larger than medium environmental capacity. The relative environmental capacity of Pb is also comparatively large, and more than 2/3 of the sampling spots are larger than medium environmental capacity. Comprehensive relative environmental capacity is not very large, more than half number of the sampling spots are with medium capacities. More than 1/3 number of the sampling spots are with low capacities, while there are only three sampling spots with high capacities, which are Shanting of Zaozhuang, Pingdu of Qingdao and Laixi of Qingdao. One sampling spot is overloaded, which is in Qufu.5.In the study of heavy metals environmental availability prediction, three kinds of inputs of pollution are assumed. If the input equals the controlled input, then the year of limitation is in several years time; if the input is larger than the controlled input, then the year of limitation is sooner. In the later case, whether sooner or later depends on the differences between the residual rate of different heavy metals in different soil types. The sustainable development of the ecology can be achieved only if the principle of input per year less than controlled capacity per year is obeyed. Total capacity control is a feasible and effective way to prevent soil pollution.