Heavy metal toxicity found in Chinese port poses risk to seafood safety

Heavy metals naturally occur in the Earth’s crust, but human activities can increase their concentration in the environment, including domestic sewage and waste disposal, fumes from vehicle exhausts, fertilizer runoff, mining and fuel leaks from ships. These elements, such as arsenic, lead and mercury, can be highly toxic even in small amounts and bioaccumulate persistently, proving harmful to humans and wildlife.

New research, published in Frontiers in Marine Science, has assessed how heavy metal pollution in China’s Yangshan Port is impacting the aquatic environment and subsequent effects on the local population.

To do so, WenZhuo Zhu, of China’s Zhejiang Ocean University, and colleagues investigated the concentration of seven heavy metals (arsenic, cadmium, chromium, copper, lead, mercury and zinc) in seawater, sediment samples, and five species of fish and crustaceans living on or near the sea floor.

They found that heavy metals accumulate in the sediment at higher concentrations than in the water column. This correlated with a greater incidence of toxicity in benthic organisms living near the seafloor and interacting more with the bottom sediments, compared to fish at higher levels of the water column.

It may be further exacerbated by the differences in the metabolisms and detoxification mechanisms of fish and crustaceans, and between species of fish living at different depths of the water column with varying dissolved oxygen levels.

The researchers note that anthropogenic factors are the leading cause of this heavy metal pollution, particularly in the port area closest to the Yangtze River estuary. These pollutants are derived from household and industrial wastewater, plus discharges from the agriculture and fishing industries. Arsenic was also sourced from marine engineering structures, particularly for the shipping industry.

Overall, arsenic and mercury posed the greatest threat to the marine environment in the study area, with the former the most significant risk to human health through trace metal poisoning. This can affect multiple areas of the body, including the liver and skin, plus respiratory, cardiovascular and nervous systems, and may also increase the risk of developing cancer. The hazard is particularly heightened in children due to their developing metabolisms and immune systems, plus rapid cell growth.

Due to the accumulation of heavy metal toxicity in marine organisms throughout the food chain, the authors recommend that the local population here, and in other areas worldwide where this is an issue, avoid consuming too much seafood to reduce their exposure. While this is beneficial for health, it could have serious socioeconomic implications for locals who rely on the fishing industry of the port area for their livelihoods.

Consequently, this research is significant for understanding heavy metal toxicity in the ocean and how this impacts not only the marine ecosystem but the well-being of the local population, in order for communities and policy makers to implement protection measures to reduce pollution risks and associated impacts. In particular, as Yangshan Port and others worldwide undergo expansion projects, the need to reduce heavy metal toxicity is becoming ever-more pressing.

© 2025 Science X Network