8ALI M M, ISHIGA H, WAKATSUKI T. Distribution and changes in heavy metal contents of paddy soils in different physiographic units of Bangladesh [J]. Soil Science and Plant Nutrition, 2003,49(4):527 - 538.
9HAKANSON L. An ecological risk index for aquatic pollution control a sediment logical approach[J]. Water Research, 1980,14(8) : 975 - 1001.