Distribution and Contamination Assessment of Heavy Metals in Surface Soil and Offshore Sediments of Rizhao Coast, Shandong

摘要

Soil and surface sediment samples were collected from both land and offshore area of the coastal zone of Rizhao, Shandong Province. Eight heavy metal elements were analyzed to examine the element distribution pattern and to define the abnormal areas with high potential pollutant risks. The concentration distribution patterns are land-sea linked to understand the pollutant sources and the land-sea interaction. Arsenic(As) and mercury (Hg) show a widespread distribution pattern, while Cd, Cr, Cu, Ni, Pb and Zn show point pattern with high concentration close to the city and villages with high urbanization level. The level of heavy metal pollution were evaluated with both single factor and Nemerow multiple factors indices, the results show that most of the studied area fall into the range of quality standard of Grade-I, the polluted soil with quality of Grade-III and IV are mainly distributed in the urban area. the offshore surface sediments have slight high As and Cr concentration, due to the natural high As background from lithogenic sources and Cr anthropogenic sources near the harbor and river mouth areas. The offshore high concentration has a positive correlation with the fine sediment distribution, which suggests the clay sediments are important carriers of heavy metals.