Heavy metal contamination is an elevating threat to the aquatic environment of estuarine bays. In the present study, surface sediments from Shantou Bay in South China were collected and detected for the concentrations of heavy metals including copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), cadmium (Cd), and lead (Pb) using ICP-MS. Spatial distribution, temporal trend, and potential ecological risks for the metal pollution were discussed. The results showed that levels of metals generally decreased by the order of Zn > Pb > Cr > Cu > Ni > Cd. Spatial variation of metal contents was observed with an order of Rongjiang River > Niutian Bay > Shanthou Harbor for Zn and Cd. Sediments of the Niutian Bay were observed with higher levels of Cu, Cr, Ni, and Pb. Compared with reported data from the same region at different sampling periods, a low–high–low trend was observed for the concentrations of the six elements, suggesting a great improvement of sediment quality in Shantou Bay. The average I_geo values suggested moderate pollution of Cu, Zn, Pb, and Cd. The potential ecological risks of Cu, Pb, Zn, Ni, and Cr were in low levels. More attention should be paid to the Cd pollution, considering its great values of potential ecological risk index. Our findings provided better understanding of heavy metal pollution in estuarine environments.

Surface soils form a major planting base of winter jujube in China were collected and detected for six heavy metals including Co, Ni, Cu, Zn, Cd, and Pb. The concentrations of Co, Ni, Cu, Zn, Cd, and Pb were 27.6 ± 6.0, 57.9 ± 12.8, 67.1 ± 10.3, 102.6 ± 23.4, 0.24 ± 0.07, and 25.1 ±5.9 mg/kg, respectively, showing an order of Zn > Cu > Ni > Co > Pb > Cd. The contents of the investigated metals were frequently observed higher than their related background values, suggesting that extra metal inputs occurred. Levels of all elements were below the associated risk screening values of agricultural soil in China, indicating healthy planting conditions for the winter jujube cultivation. Nemerow comprehensive pollution indexes of the metals in all the sampling stations were lower than 0.7, revealing a non-pollution status of the soils. Geo-accumulation indexes suggested that Zn and Pb caused no pollution, and Co, Ni, Cu, and Cd seemed to result in slight pollution. Co, Ni, Zn, Cd, and Pb had similar sources, which might be related to some natural processes and the use of fertilizers. Extra Cu might be mainly from the use of copper-containing pesticides. Based on our observations, the soils from the planting base of winter jujube in the Yellow River Delta were safe for the cultivation of winter jujube, and the rational utilization of pesticide and fertilizer were proposed to control the new inputs of heavy metals.