Heavy metal contamination in beach sediments as a result of sewage outlet and waste residue dumping in Qingdao, China

Heavy metal pollution on beaches due to enhanced human activities has received attention. This study takes four beaches in China as examples to study the characteristics of heavy metal pollution. The results show that most beach sediments have a certain degree of heavy metal accumulation as a result of human activities, except for the sediments of No. 1 beach. The beaches in order of the degree of pollution were No. 3 beach > Shilaoren beach > No. 2 beach > No. 1 beach. Three of the four studied beaches show contamination with As, Cr, Fe, Ni, Pb and Zn. Sewage outlets are the main sources of these pollutants, but the high levels of Zn and Fe are caused by coal cinder dumping at one beach, and the high levels of Ni are due to the coating of fishing boats at another beach. Heavy metal pollution occurs in areas near pollutant sources or at the high or low tide lines due to waves and tides. Heavy metals also diffuse vertically, resulting in contamination at certain depths. The distribution of heavy metals over ten years showed that most of the pollutants on cape-bay beaches are difficult to diffuse outward, which indicates that a special pollutant management plan needs to be developed for such beaches.