Pollution of sediments

Name(s): 
Contamination of sediments by toxic substances
Nature 
Many metals and organic substances have an affinity for organic matter or mineral particles. Sediments thus provide a suitable medium for the accumulation of contaminants from aqueous sources and atmospheric deposition. The contaminant level is often higher than in the overlying body of water.
Counter-claim 
Certain elements, often associated with pollution, tend to occur naturally in sediments and their concentrations reflect the geology of the areas (as in the case of lake basin).
Type 
(E) Emanations of other problems