
Marine sediments with Leptocheirus and Neris show mixing
of the added fluorescent-tagged pellets into the top 2 inches of sediment.
Scale on the left shows sediment
depth in inches
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Pilot-scale Research of Novel Amendment Delivery for
In-situ Sediment Remediation
Investigators: Upal Ghosh (UMBC) and Charles A Menzie (Exponent)
Duration: 2008-2010
Funding agency: National Institue of Environmental Health Sciences (NIH)
Summary. Human health risks associated with the presence of
chemicals in sediments arise from either direct contact
with the sediments or by eating fish and shellfish that have accumulated
chemicals from the sediments.
Emerging laboratory-scale research by our group and others has shown
that contaminant transport
pathways and bioavailability can be interrupted by modifying and enhancing
the binding and contaminant
assimilation capacity of natural sediments. This is achieved by adding
sorbent amendments such as
activated carbon for binding persistent organic pollutants and natural
minerals such as apatite, zeolites, or
bauxite for the binding of toxic metals in sediments. Critical barriers
in the adoption of this in-situ
remediation approach is the availability of efficient delivery methods
for amendments to impacted sediments
and understanding of physical and biological processes in field sites
that control technology effectiveness.
The main aim of this research project is to develop the in-situ remediation
technology through a pilot-scale
investigation aimed at addressing the critical barriers in the advancement
of the technology. This field
research project will be carried out at two PCB/DDT-impacted sensitive
wetland sites. The research design
will involve application of the technology in a quarter acre plot in
each site and a monitoring plan to
understand how the fate and transport processes of PCB/DDT in the wetland
environment is impacted by the
application of the sorbent amendments. Biological monitoring will include
PCB/DDT bio-uptake
measurements in a freshwater oligochaete carried out in field exposure
chambers and also in laboratory
microcosms. The physicochemical monitoring will include aqueous partitioning
and desorption rate from
sediment, two measures that define the bioavailability processes of
sediment bound contaminants. The
PCB/DDT fate and transport process understanding will be used to assess
human health risk benefit from
the technology based on a dermal uptake model and a food-chain model.
Sediment-bound contaminants such as PCBs and DDT pose a public health
risk through contamination of
the food chain and through direct exposure. This field research will
evaluate the effectiveness of a novel
approach to alter the binding capacity of sediments to reduce human
exposure to such contaminants.
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