YUAN Guoming，HE Guifang

（South China Sea Environmental Monitoring Center，SOA，Guangzhou 510300, China)

Abstract: By collecting 35 surficial sediment samples from Zhelin Bay to Dacheng bay, Guangdong Province, China, heavy metals and the grain-size were analyzed. Results show that the mean contents of Hg, As, Cu, Pb, Cd, Zn and Cr are respectively 0.053 mg/kg, 9.7 mg/kg, 19.2 mg/kg, 40.0 mg/kg, 0.11 mg/kg, 89.0 mg/kg and 31.4 mg/kg, and their distribution pattern shows a decrease from zhelin Bay to Dacheng Bay and from the west to the east (except Cd). The fine grain-size such as silt and clay dominate the vast area, and sand only exists in the local area, indicating the sedimentary environment of coastal and shallow sea. Based on the distribution of heavy metals, some environmental geochemistry characteristics of heavy metals were quantitatively assessed. The enrichment facto of heavy metals varies from 0.73 to 1.37, with the minor artificial enrichment in the Hg, Cu, Pb and Zn, while As, Cr and Cd is close to their background. The potential ecological risk index of sediment display generally good environment: single-factor index of the Hg has reached the grade of moderate- risk and the others only belong to the grade of low-risk, forthermore, mulit- factor integrated index is mostly in the low-risk, with moderate-risk existing sporadically. The heavy metals show outstanding positive correlation with each other (except Cd) and might have similar sources. There are positive certain correlation between heavy metals and grain-size, broadly in accordance with granularity control of heavy metals in sediment. 

Key words: sediment; heavy metal; content and distribution; enrichment; potential ecological risk

EARTH AND ENVIRONMENT Vol. 43, No.2, Tot No.304, 2015, Page 190-197