A Comparative Study of Different Methods on Quality Assessment of Soil Environment Polluted by Zinc in Agricultural Production Areas——A Case Study in Shulan City of Jilin Province

[Objective] The aim was to explore evaluated precision on quality of soil environment polluted with zinc in agricultural production areas and to provide references for verification of production area.[Method] In Shulan City in Jilin Province,soils were sampled and analyzed in a laboratory using single-factor pollution index and GIS based spatial interpolation.The quality of environment polluted with zinc was assessed and related methods were compared according to Environment Quality Standard of Green Food Production Area.[Result] Spatial interpolation of zinc in soils based on GIS proved more precise than traditional methods;cokriging method with co-factors was higher in precision than common cokriging;cokriging method with zinc and organic matter was higher in precision than cokriging with zinc alone.[Conclusion] Quality assessment on environment polluted with zinc based on GIS interpolation is more scientific and reasonable than traditional methods.

Evaluation on Soil Heavy Metal Pollution of Agricultural Habitat Environment in Xi'an City

[Objective] This study aimed to understand and grasp the soil heavy metal pollution status of agricultural habitat environment in Xi＇an City. [Method] The soil heavy metal pollution status of pollution-free agricultural products-producing areas in 9 counties （districts） of Xi＇an City was investigated. A total of 609 soil samples were collected, and their Cd, Hg, As, Pb and Cr contents were determined. In addition, the heavy metal pollution status of the collected soil samples was evaluated by Nemerow index method. [Result] The pollution in Baqiao, Chang＇an; Gaoling, Lan- tian, Lintong and Yanliang was of grade I, belonging to clean level; the pollution in Hu County, Weiyang and Zhouzhi was of grade II, near the warning line, belong to relatively clean level. There was no large-area soil heavy metal pollution overall. The investigated areas could be used as production bases of pollution-free agricultural products and even high-quality agricultural products. However, the heavy met- als contents in some individual areas exceeded relevant soil environmental quality standards, and they should be avoided or forbidden during regional planning and selection of production area. [Conclusion] Soil heavy metal pollution of agricultural habitat environment in Xi＇an City is generally at good status. Targeting at the future development plan of Xi＇an City, feasible and scientific suggestions are put forward.

Phosphorus Loss from Dry Sloping Lands of Three Gorges Reservoir Area, China

Eutrophication in the Three Gorges Reservoir has become a serious issue, and phosphorus (P) is the nutrient thought to be primarily responsible although there are few studies about P loss from the mostly sloping farmlands of the area. This work investigated the amounts and forms of P loss from 9 farmlands with the slopes of 4°, 9°, and 17° in a small watershed, Wangjiagou in Fuling District, Chongqing of China. The slope of the relationship between runoff and rainfall increased with field slope; i.e., there was a significant interaction between the effects of rainfall and field slope on water export. For sediment export by surface runoff, there was no interaction between field slope and rainfall, and the intercept of the relationship between rainfall and sediment loss was significantly different for the 3 slopes. The main P loss was from sediments, regardless of slope. In the runoff water, particulate P was the largest P fraction, and its loss was greatest from the steepest land and least from the flattest. The release of total P and available P from sediments followed the same trend. The P loss during May to July in Wangjiagou was more than 60% of the annual total.