| Six districts(counties) of apple orchard production area in Tianshui City (Qinxhou, Maiji, Qinan, Gangu , Wushan, Qingshui) were taken as the research sites. Where the pH and Concentrations of Cr, Cu, Pb, Cd, Zn and organic matter were investigated and analyzed with the help stastistical method in apple orchard topsoils(0~20cm) in Tianshui area. Simultaneously soil environmental quality was evaluated according to the environmental quality standards of green food production base methods of both the Nemerow comprehensive pollution index and pollution load index. The results indicate that the soil was slightly alkaline. and the average value of organic matter content is 1.53%, the content of these 5 metals were cumulated in the studied apple orchards, especially the average value of the element of Cr, Pb, Zn exceed the soil background value of the Gansu Province . The were significantly correlation among Cr, Pb, Cu and organic matter in apple orchard soils. Single factor index of all metals are less than 1and their multi-factor index and pollution load index were less than 0.7, its shows that the studied apple orchards meets the needs of the green food production base for furhter development, on the other hand, the content of Pb may have a potential negative influence to the green food production, therefore, real-time monitoring and protection measures were required to prevent its further enrichment. |
