Measured partitioning coefficients for parent and alkyl polycyclic aromatic hydrocarbons in 114 historically contaminated sediments: Part 1. K_OC values

Abstract

Polycyclic aromatic hydrocarbon (PAH) partitioning coefficients between sediment organic carbon and water (K(OC)) values were determined using 114 historically contaminated and background sediments collected from eight different rural and urban waterways in the northeastern United States. More than 2100 individual K(OC) values were measured in quadruplicate for PAHs ranging from two to six rings, along with the first reported K(OC) values for alkyl PAHs included in the U.S. Environmental Protection Agency's (U.S. EPA) sediment narcosis model for the prediction of PAH toxicity to benthic organisms. Sediment PAH concentrations ranged from 0.2 to 8600 microg/g (U.S. EPA 16 parent PAHs), but no observable trends in K(OC) values with concentration were observed for any of the individual PAHs. Literature K(OC) values that are commonly used for environmental modeling are similar to the lowest measured values for a particular PAH, with actual measured values typically ranging up to two orders of magnitude higher for both background and contaminated sediments. For example, the median log K(OC) values we determined for naphthalene, pyrene, and benzo[a]pyrene were 4.3, 5.8, and 6.7, respectively, compared to typical literature K(OC) values for the same PAHs of 2.9, 4.8, and 5.8, respectively. Our results clearly demonstrate that the common practice of using PAH K(OC) values derived from spiked sediments and modeled values based on n-octanol-water coefficients can greatly overestimate the actual partitioning of PAHs into water from field sediments.

Vertical records of sedimentary PAHs and their freely dissolved fractions in porewater profiles from the northern bays of Taihu Lake, Eastern China

“…† For the dissolved organic carbon, we assumed K DOC z K OC , where K OC is the organic carbon-normalized two phase distribution coefcient. 26 K OC data were adopted from the previous report 27 and shown in Table S4. †…”

Identifying the causes of sediment‐associated contamination in the Illinois River (USA) using a whole‐sediment toxicity identification evaluation

“…The exhaustive sediment extraction technique used in the present study may overestimate bioavailability. One approach that can reduce this source of variation for PAH toxicity would be to use freely dissolved pore-water concentrations measured by solid phase microextraction methods [33][34][35][36][37]. Second, knowing concentrations of alkyl PAHs can provide additional information for sediment TIEs.…”

Influence of historical industrial epochs on pore water and partitioning profiles of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in Oslo Harbor, Norway, sediment cores

“…Total organic carbon, AOC, and BC themselves comprise several unique carbonaceous phases with widely varying sorption properties [20][21][22][23]. Because of this heterogeneity, TOC, AOC, and BC sorption coefficients for PAHs, PCBs, and other contaminants have been found to scatter over several log units [17,19,24]. As a result of this uncertainty, it remains to be established whether partitioning models for TOC, AOC, and BC can be used to assess the C pw behavior in recent sediments.…”