Bioavailability assessment in activated carbon treated coastal sediment with in situ and ex situ porewater measurements

Songjing Yan; Magdalena Rakowska; Xiaolong Shen; Theresa Himmer; Cameron Irvine; Rachel Zajac-Fay; Jamie Eby; Danielle Janda; Sharon Ohannessian; Danny D Reible

doi:10.1016/j.watres.2020.116259

Bioavailability assessment in activated carbon treated coastal sediment with in situ and ex situ porewater measurements

Water Res. 2020 Oct 15:185:116259. doi: 10.1016/j.watres.2020.116259. Epub 2020 Aug 3.

Authors

Affiliations

¹ Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
² Department of Civil, Environmental and Construction Engineering, Texas Tech University, Lubbock, TX 79409, USA.
³ Jacobs Engineering, Boston, MA 02116, USA.
⁴ Robertson-Bryan, Elk Grove, CA 95624, USA.
⁵ Jacobs Engineering, Tampa, FL 33609, USA.
⁶ Port of Oakland, Oakland, CA 94607, USA.
⁷ Department of the Navy (DoN), Base Realignment and Closure Program Management Office (BRAC PMO) West, San Diego, CA 92014, USA.
⁸ Redhorse Corporation, San Diego, CA 92101, USA.
⁹ Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA; Department of Civil, Environmental and Construction Engineering, Texas Tech University, Lubbock, TX 79409, USA. Electronic address: Danny.Reible@ttu.edu.

PMID: 32798889
DOI: 10.1016/j.watres.2020.116259

Abstract

Passive sampling and bioaccumulation assessments were used to evaluate the performance of activated carbon (AC) remediation of polychlorinated biphenyl (PCB) contaminated sediment offshore in Parcel F of the former Hunters Point Naval Shipyard (HPNS) (San Francisco, California). Two different composite AC materials, AquaGate+PAC™ (86 tons) and SediMite™ (24 tons) were placed on the sediment surface covering an area of 3200 m². PCB tissue concentrations in the clam Macoma nasuta were reduced 75 to 80% in pilot amendment areas after 8 months and 84-87% in non-lipid normalized tissues after 14 months during in situ monitoring, confirming the effectiveness of the AC at reducing bioavailability of the PCBs. Polydimethylsiloxane (PDMS) passive samplers were applied to evaluate and monitor freely dissolved concentrations (C_free) of PCBs in sediment porewater before AC placement (i.e., during baseline) and at 8 months, 14 months and 26 months following placement. Although AC composite materials were placed only at the surface, 80% reductions were observed to a depth of 16 cm after 8 months and up to 26 cm after 26 months in AquaGate+PAC treatment area. Total PCB porewater concentrations in surface sediments (1-6 cm) were reduced 89 and 91% in the AquaGate+PAC and SediMite areas during final sampling. Ex situ passive sampling showed porewater concentrations 2-5 times larger than in situ measurements due to the absence of hyporheic exchange in laboratory measurements and near equilibration between sediment and porewater. Estimated post placement ex situ porewater concentrations were more consistent with a model of bioaccumulation using the octanol-water partition coefficient (K_OW) as a bioaccumulation factor leading to a hypothesis that the bioaccumulation factor in the deposit feeding clam is better estimated by equilibrium ex situ porewater measurements.

Keywords: Bioaccumulation; Composite activated carbon; PCBs; Passive samplers; Sediment remediation.

MeSH terms

Animals
Biological Availability
Charcoal
Environmental Monitoring
Geologic Sediments
Polychlorinated Biphenyls* / analysis
San Francisco
Water Pollutants, Chemical* / analysis

Substances

Water Pollutants, Chemical
Charcoal
Polychlorinated Biphenyls