HEAVY METAL CONTAMINATION IN MARINE ENVIRONMENTS

Clay and organic matter have a net negative surface charge that makes them attract positively charged cations such as heavy metals. Clay moreover has a high surface to volume ratio and thus has plenty of surface area to which heavy metals can be bound through adsorption. In contrast, sand is inert and does not bind heavy metals as clay and organic matter does.

 

Organic and fine particles tend to settle out in low energy environments and also where fresh water meets salty water, encouraging flocculation. This type of environment is common in estuaries.

 

Heavy metals are thus prone to accumulate in low energy, clayey, estuarine environments common in many harbours. Contamination has been magnified in many such areas due to the antifouling paint on boats containing heavy metals.