The researchers studied sediments from the Dagu River and Jiaozhou Bay in China to see how much heavy metals were present. They found that the estuary sediments had higher metal levels than those from the river. The metals were mostly influenced by the size of the sediment particles and were enriched by minerals and organic matter. Some metals were at levels that could harm marine life and humans. Lead and mercury were especially concerning, likely coming from coal and car emissions. The metals were mainly brought into the area by river flow and air pollution, and then spread to other parts of the bay.