Historical Reconstruction of Environmental Change

Demands on our aquatic resources will increase in coming decades as it is projected that 75% of the world s population (6.3 billion) people will reside in coastal areas by 2025. 

The introduction of invasive species worldwide has changed the community composition and physical structure of many ecosystems. 

The effects of human encroachment on coastal systems has resulted in dramatic increases in the loadings of contaminants such as trace metals, HOCs (e.g., hydrocarbons and chlorinated hydrocarbons), and nutrients. 

Polycyclic aromatic hydrocarbons are generated from anthropogenic or natural combustion processes, in addition to rapid transformation processes of biogenic precursors that occur in situ. 

Past studies have shown a decrease in the toxicity of metals in the presence of organic matter, due to the binding of natural ligands that are believed to bind metals and reduce the concentration of free ionic species. The free ion activity model proposes that the free metal ion (as opposed to total metal ion concentration) is the dominant species available for organisms, and assumes that the colloidally complexed species should be less available. 

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