In situ Treatment with Activated Carbon Reduces Bioaccumulation
in Aquatic Food Chains
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Abstract
In
situ activated carbon (AC) amendment is a new direction in contaminated
sediment management, yet its effectiveness and safety have never been
tested on the level of entire food chains including fish. Here we
tested the effects of three different AC treatments on hydrophobic
organic chemical (HOC) concentrations in pore water, benthic invertebrates,
zooplankton, and fish (<i>Leuciscus idus melanotus</i>).
AC treatments were mixing with powdered AC (PAC), mixing with granular
AC (GAC), and addition–removal of GAC (sediment stripping).
The AC treatments resulted in a significant decrease in HOC concentrations
in pore water, benthic invertebrates, zooplankton, macrophytes, and
fish. In 6 months, PAC treatment caused a reduction of accumulation
of polychlorobiphenyls (PCB) in fish by a factor of 20, bringing pollutant
levels below toxic thresholds. All AC treatments supported growth
of fish, but growth was inhibited in the PAC treatment, which was
likely explained by reduced nutrient concentrations, resulting in
lower zooplankton (i.e., food) densities for the fish. PAC treatment
may be advised for sites where immediate ecosystem protection is required.
GAC treatment may be equally effective in the longer term and may
be adequate for vulnerable ecosystems where longer-term protection
suffices