Distribution of heavy metals and radionuclides in the sediments and their environmental impacts in Nansha Sea area, South China Sea

Activity concentrations of radionuclides (238U, 226Ra, 232Th, and 40K) in the sediments of eight sampling stations and heavy metal concentrations (Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) in the sediments of two long cores from Nansha Sea area were obtained by high-purity germanium spectroscopy and inductively coupled plasma atomic emission spectrometry. In a correlation analysis between the radionuclides and heavy metals, 232Th was positively correlated with As and Pb. 238U demonstrated a significant positive correlation with Co, Ni, Cu, Zn, and Cd. 40K was positively correlated with Co, Ni, and Cu. The geo-accumulation index, pollution load index, potential ecological risk index, and multivariate statistical techniques were used to evaluate the pollution degree and possible sources of heavy metals in the sediments. An ecological risk assessment suggested that Cr, Co, Ni, Cu, Zn, Cd, and Pb were primarily derived from natural processes, while the source of As may be related to natural processes and human activities.

Automated summary

The study showed that there is a correlation between radionuclides and heavy metals in the sediments of Nansha Sea area. The heavy metals are primarily derived from natural processes, while As may be related to both natural processes and human activities.