Aeration Effects on the Partitioning of a PCB to Anoxic Estuarine Sediment Pore Water Dissolved Organic Matter

Abstract

Pore water dissolved organic matter (DOM) plays an important role in the distribution, mobility, and bioavailability of hydrophobic organic chemicals (HOCs) in sediment environments. The effect of aeration on the partitioning of 2,2′,4,4′-tetrachlorobiphenyl (TeCB) to anoxic pore water DOM from three estuarine sites was investigated. Pore water DOM was fractionated into molecular size and polarity fractions by ultrafiltration and XAD-8 resin chromatography. Total organic carbon analysis was utilized to determine shifts in molecular size and polarity distributions. Changes in functional groups and aromaticity were evaluated for whole and fractionated pore waters by specific UV absorbance at 254 nm (SUVA 254 ). The solubility enhancement method was used to determine the partitioning of TeCB to whole and fractionated pore water DOM. At two sites, the overall TeCB-DOM distribution coefficient decreased by an order of magnitude after aeration. The higher molecular size and all polarity fractions exhibited a decrease in partitioning behavior upon aeration. The aromaticity and TeCB-DOM distribution coefficient of the lowest molecular size fraction (<1000 Da) decreased upon aeration. The highest (>10 000 Da) and lowest (<1000) molecular size fractions contributed the most to overall partitioning. The observed aeration effects in anoxic estuarine sediment pore waters differed significantly from those previously reported in freshwater systems.

Bioturbation-Driven Release of Organic Contaminants from Baltic Sea Sediments Mediated by the Invading Polychaete Marenzelleria neglecta

“…This was explained by coprecipitation of interstitial colloids and DOM and associated POPs when ferrous oxides precipitated following aeration. Pedersen et al (16) report a 24% decrease in pore water DOM when aerating estuarine sediments, attributable to DOM coagulation with precipitating Fe(OH)3. Baltic Sea sediments contain large amounts of organic matter and coprecipitation effects are plausible explanations to the stabilized or reduced contaminant fluxes observed in the reoxygenation treatment.…”

Interactive influence of Fe–Mn and organic matter on pentachlorophenol sorption under oxic and anoxic conditions

“…The anoxic treatments typically had greater amounts of DOC than oxic. Increased DOC in anoxic treatment may be attributed to several factors; (i) greater solubility of organic matter at the higher pH level of the anoxic treatment and (ii) formation of ferric hydroxides as a co-precipitant of DOC in oxic soil samples [44,45]. As SOM is often considered to be the chief sorbent for hydrophobic compounds, it was therefore anticipated to dominate the sorption of PCP; however, subsequent dissolved organic matter (DOM) formation offset its impact in this study in agreement with previous reports [46,47].…”

Resuspension of polychlorinated biphenyl‐contaminated field sediment: release to the water column and determination of site‐specific KDOC

“…Pedersen et al [6] found that by exposing anoxic sediment pore water from three different estuarine sites to DO, partitioning of a tetra-CB between pore-water DOM and the freely dissolved phase decreased at two sites and did not change at the third. Lin et al [8] found changes in the diffusive flux of a tetra-CB from the sediment bed to the water column depended on changes in partitioning Fig.…”

“…The lack of significant change in PCB partitioning in the present study is probably due to lack of change in water column ionic strength (e.g., pH) despite differences in water column DO. Both Pedersen et al [6] and Lin et al [8] demonstrated the effects of oxic state were both ionic strength-and site-dependent, and indicated site-specific sorption coefficients are necessary for evaluating the effect of remediation activities.…”

“…Further, resuspension can potentially alter chemical gradients between particle-associated and dissolved contaminants [3], and resuspended particles are subject to increased rates of organic matter oxidation/mineralization because of greater exposure to dissolved oxygen in the water column [4,5]. The aeration of sediment solids has been shown to increase HOC partitioning away from dissolved organic matter and particulate organic matter (DOM and POM) to the dissolved phase, presumably due to a decrease in DOM/POM aromaticity with oxidation [6][7][8].…”