Study of the Heavy Metals, Nitrogen and Phosphorus Contaminants in the Sediments of the Yellow River Delta

Abstract

The sediments of the Yellow River Delta, mainly, are silty. Contents of Cd, Pb, Zn, Hg, Cu, Ni, Cr and Mn in sediments are in a range of 0.07～0.30 μg/g, 9.7～36.3 μg/g, 37.4～110 μg/g, 0.01～0.25 μg/g, 18.4 ～58.0 μg/g, 17.9～43.7 μg/g, 38.7～80.7 μg/g and 423～980 μg/g, respectively. Due to the low concentrations of Pb, Zn, Cd and Hg and the similar concentrations of Cu, Ni, Cr and Mn to the background values, the sediments of the Yellow River Delta would not be seriously suffered from contamination. The heavy metals are concentrated in the silty sediments rich in clay particles. If the sediments rich in clay particles are excluded in consideration, contents of Pb, Zn, Cd and Hg still show the increased trends upwards in the profile located in the river mouth, which implicates the impact of rapid economic growth of the Yellow River area since 1980' s on the delta environments. Generally, total N in sediments is low from 110 μg/g to 670 μg/g, and the ratios of N existing in the form of NH 3 to total N are only 0.01～0.06. The contents of total P in sediments range from 430 μg/g to 760 μg/g. It occurs mainly as calcium phosphates, and the ratios of P existing in the forms of FePO 4 and AlPO 4 to total P are only 0.00～0.08 and 0.00～0.03, respectively. Therefore, N and P in sediments can not produce serious impact on the environments.