Performance of an in situ activated carbon treatment to reduce PCB availability in an active harbor

Abstract

In situ amendment of surface sediment with activated carbon is a promising technique for reducing the availability of hydrophobic organic compounds in surface sediment. The present study evaluated the performance of a logistically challenging activated carbon placement in a high-energy hydrodynamic environment adjacent to and beneath a pier in an active military harbor. Measurements conducted preamendment and 10, 21, and 33 months (mo) postamendment using in situ exposures of benthic invertebrates and passive samplers indicated that the targeted 4% (by weight) addition of activated carbon (particle diameter ≤74 µm) in the uppermost 10 cm of surface sediment reduced polychlorinated biphenyl availability by an average (± standard deviation) of 81 ± 11% in the first 10 mo after amendment. The final monitoring event (33 mo after amendment) indicated an approximate 90 ± 6% reduction in availability, reflecting a slight increase in performance and showing the stability of the amendment. Benthic invertebrate census and sediment profile imagery did not indicate significant differences in benthic community ecological metrics among the preamendment and 3 postamendment monitoring events, supporting existing scientific literature that this approximate activated carbon dosage level does not significantly impair native benthic invertebrate communities. Recommendations for optimizing typical site-specific assessments of activated carbon performance are also discussed and include quantifying reductions in availability and confirming placement of activated carbon. Environ Toxicol Chem 2018;37:1767-1777. Published 2018 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Bioaccumulation in Functionally Different Species: Ongoing Input of PCBs with Sediment Deposition to Activated Carbon Remediated Bed Sediments

“…Data from Figure are provided on a linear scale in Supplemental Data, Figure S3 (tabulated data provided in Supplemental Data, Table S3). Our results are consistent with those of others on the lower effectiveness of activated carbon in reducing bioaccumulation of higher chlorinated PCBs at least in the short term (Millward et al ; Cho et al ; Beckingham and Ghosh ; Cornelissen et al , ; Choi et al ; Kirtay et al ). The native congeners for which no reduction in bioaccumulation was detected made up less than 1% of the total native PCB bioaccumulation in the control and less than 10 to 20% of the total native PCB bioaccumulation in the activated carbon mix.…”

“…For this last reason, the difference between the inputs and native congeners was greater for the clams than the worms (Figure ). Similarly, Samuelsson et al () attributed newly deposited particles to reduced bioaccumulation in worms relative to clams, and Kirtay et al () also noted this.…”

“…Differences in the bioaccumulation levels between the worms and clams were caused by the variations in feeding strategies of the 2 species; that is, worms feed directly from sediments, whereas clams are suspension feeders from the overlying water Figure S3 and also provided in tabulated format in the Supplemental Data, Table S3. (Bridges et al 2017;Kirtay et al 2018). Significantly higher (p < 0.001) lipid content of the worms was also a factor (Table 2).…”

Assessing Biota Accumulation Due to Contamination of Sediments by Storm Water Heavy Metals

“…The clam species Macoma nasuta has been used for bioaccumulation exposure testing of marine and estuarine sediments (Werner et al 2004;Kirtay et al 2018). These bivalve species can take up metals through the ingestion of sediments but also through porewater, burrow, and overlying water (Winsor et al 1990).…”

“…Bioaccumulation tests that are performed in the laboratory ex situ can generate comparable results to the exposure tests conducted in situ if the exposed organisms and conditions are similar to the biota inhabiting the field sediments. The clam species Macoma nasuta has been used for bioaccumulation exposure testing of marine and estuarine sediments (Werner et al 2004; Kirtay et al 2018). These bivalve species can take up metals through the ingestion of sediments but also through porewater, burrow, and overlying water (Winsor et al 1990).…”