Aquatic secondary metal source

The sources of heavy metals to wetlands, while in some part from natural sources, are dominated by human activity. Natural weathering of rocks introduces some metals into wetlands. However, the majority of elevated heavy metal inputs are from industrial sources. Humans have allowed the surface water to be the prime repository of waste materials including industrial sources. These waste materials include heavy metals that are toxic to aquatic plant and animal life. As a result, there are now concerns with secondary impacts the bioaccumulation and bioconcentration of metals (e.g., Hg) through the food chain that result in toxicity to the nonaquatic species. The atmosphere can also contribute large amounts of heavy metals through emissions from industrial sources which are deposited by both dry aerosol fallout and wet scavenging as precipitation into watersheds. 

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