Effect of the Resuspension of Contaminated Sediments on the
Availability of Heavy Metals
Mehdi Pourabadehei1, Catherine N. Mulligan2
1Ph.D
candidate at BCEE Department, Concordia University, Montreal, Quebec, Canada
at BCEE Department Concordia University, Montreal, Quebec, Canada
2Proffesor
Abstract
Mobility of heavy metals in aquatic ecosystems has been a serious issue due to their
toxicity and ecological risk on the biotic species. Binding of the contaminations to the
particles allows the sediments to play a main role in transporting and geochemical
partitioning of the heavy metals. In addition, sediments are a valuable source of
biological diversity in the rivers. Therefore, concern about the water quality and aquatic
ecosystem would be incomplete without the appropriate study of sediments.
Based on the strong scientific evidence, metals are associating with the finer sediments.
This is the primary concept of the resuspension method used as a new approach for
remediation of the contaminated sediments in this research. As the first step in
resuspension, the air jet for a specific period of time suspends the sediments in the
confined water column. Through time, the coarser sediments are settled while the finer
ones are still suspended. The suspended sediments will be removed at the next step by a
pump and eventually will be collected in a filter system. Consequently some of the fine
sediments, which contain the most contamination, are removed from the environment.
In this study, all the sediment samples were obtained from selected stations at a harbor,
located on the bank of the St. Lawrence River in the province of Quebec. The surface and
core sediment samples were taken approximately at 5 and 50-centimeter depths from the
river bottom, respectively. Samples were analyzed based on the sediment quality
guidelines (SQGs). A sequential extraction technique was used to provide the history and
contribution of each metal in five different fractions followed by using ICP-MS to
measure the concentration of them. The physical features of the sediments were
determined by laser scattering particle size distribution analysis.
The results indicated that the aeration influenced the transfer of the metals from
exchangeable and carbonate fractions to the other fractions, which reduced the potential
level of availability and mobility of heavy metals. Resuspension also, improved the water
and sediment quality by decreasing the redox-potential (abs Eh) and loss on ignition
(LOI%) by a maximum of 131% and 73% respectively. Overall, resuspension of
contaminated sediments is suggested as the best choice for remediation in harbors with a
high concentration and level of availability of the heavy metals.
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