Passive Sampling to Measure Baseline Dissolved Persistent Organic Pollutant Concentrations in the Water Column of the Palos Verdes Shelf Superfund Site

Abstract

Passive sampling was used to deduce water concentrations of persistent organic pollutants (POPs) in the vicinity of a marine Superfund site on the Palos Verdes Shelf, California, USA. Precalibrated solid phase microextraction (SPME) fibers and polyethylene (PE) strips that were preloaded with performance reference compounds (PRCs) were codeployed for 32 d along an 11-station gradient at bottom, surface, and midwater depths. Retrieved samplers were analyzed for DDT congeners and their breakdown products (DDE, DDD, DDMU, and DDNU) and 43 PCB congeners using GC-EI- and NCI-MS. PRCs were used to calculate compound-specific fractional equilibration achieved in situ for the PE samplers, using both an exponential approach to equilibrium (EAE) and numerical integration of Fickian diffusion (NI) models. The highest observed concentrations were for p,p'-DDE, with 2200 and 990 pg/L deduced from PE and SPME, respectively. The difference in these estimates could be largely attributed to uncertainty in equilibrium partition coefficients, unaccounted for disequilibrium between samplers and water, or different time scales over which the samplers average. The concordance between PE and SPME estimated concentrations for DDE was high (R(2) = 0.95). PCBs were only detected in PE samplers, due to their much larger size. Near-bottom waters adjacent to and down current from sediments with the highest bulk concentrations exhibited aqueous concentrations of DDTs and PCBs that exceeded Ambient Water Quality Criteria (AWQC) for human and aquatic health, indicating the need for future monitoring to determine the effectiveness of remedial activities taken to reduce adverse effects of contaminated surface sediments.

Application of passive sampling for measuring dissolved concentrations of organic contaminants in the water column at three marine superfund sites

“…The NBH4 C free were not different for PE and total water, SPME and C 18 the PE and simple deployment system. In another study examining water column concentrations using PE and SPME passive samplers deployed at 11 stations at the PVS Superfund site, 431 Fernandez et al [18] lost several samplers in the middle and upper water column where the 432 current is the strongest.…”

“…In the same study, SPME deployed 644 approximately one meter above the sediments measured C free of 1,700 to 4,000 pg/L. Finally, in 645 both Fernandez et al [18,19], SPME were deployed to monitor for total PCB C free but unlike the Total PCB is equivalent to the sum of measured PCB congeners. …”

“…The losses were attributed to fatigue of the aluminum wire used to 433 secure the samplers to the deployment gear. In the same study, the SPME attached to the gear by 434 stainless steel hose clamps were successfully recovered [18] as were SPME samplers Zeng et al…”

“…This type of exposure information is very important 137 for understanding the direct exposure to water column organisms (e.g., fish) and serving as input 138 information for modelling bioaccumulation and assessing risk to human and ecological health 139 higher in the food chain (e.g., avians, wildlife). Therefore, to successfully predict exposures to 140 water column organisms and model higher level impacts it is critical to insure that measurements In recent years, the use of passive sampling for measuring C free at U.S. EPA Superfund 144 sites has been encouraged as a scientifically-robust tool for assessing exposure (e.g., [26][27][28]) 145 and, in a limited number of cases, remedial project managers (RPMs) at Superfund sites have 146 applied passive sampling (e.g., [18,19,29] placed on ice for transport to the laboratory. Once at the laboratory, water samples were filtered 268 through solvent-rinsed glass fiber filters (1 µm effective pore size) within 24 hours of collection.…”

“…In another study examining water column concentrations using PE and SPME passive samplers deployed at 11 stations at the PVS Superfund site, 431 Fernandez et al [18] lost several samplers in the middle and upper water column where the 432 current is the strongest. The losses were attributed to fatigue of the aluminum wire used to 433 secure the samplers to the deployment gear.…”