Importance of DOC in sediments for contaminant transport modelling

Abstract

Contaminants in the interstitial waters are not only dissolved but also associated with a filterable colloidal phase such as DOC. The DOC plays an important role regulating the distribution of chemicals between particulate and dissolved phases since it binds chemicals and makes them unavailable for vertical diffusive exchange. A three-phase partitioning model that consists of free-dissolved, DOC-bound, particulate-bound components of the chemicals involved is used for the contaminant transport model in order to include the effect of DOC on the partition coefficient. The contaminant model is linked to WASP modeling framework to predict remobilization of PCBs in sediments and the fate and transport of the contaminant in overlying waters of the New Bedford Harbor where the harbor has been contaminated with PCBs and heavy metals released from electronic capacitor manufacturers. Simulation of remedial controls indicates that if no action is taken, PCB concentrations will continue to be at elevated levels. Several scenarios for the removal of contaminated sediments have been performed to reduce the elevated PCB concentrations to background levels.

Impact of imposed anaerobic conditions and microbial activity on aqueous‐phase solubility of polycyclic aromatic hydrocarbons from soil

“…Burgess and others [17] have found that polychlorinated biphenyl–colloid interactions are more significant with increased core depth and presumably more reduced conditions. These workers and others [17–20] have observed higher than expected PAH concentrations in an aqueous phase containing soluble natural organic matter, which suggests the existence of PAH–organic soluble complexes. Some authors have shown a decrease in bioavailability to aquatic bluegills, guppies, and amphipods due to PAH binding with dissolved organic matter (DOM) [21–23].…”

“…Most certainly, the drastic solution chemistry changes resulting from anaerobic conditions, especially with Ti‐citrate microcosms, affected not only PAH‐DOM solution associations, but also interactions of soluble DOM and any DOM–PAH complexes with the mineral surfaces in the soil during incubation. Other workers [17–20] have implied that increased PAH solution concentrations are the result of solution PAH‐DOM associations. It is interesting to note that whatever soil‐DOM‐PAH mechanisms are operative in the Ti‐citrate microcosm data, the degree of solubility increase was strongly influenced by PAH molecular weight (Fig.…”

“…Pravecek et al incubation. Other workers [17][18][19][20] have implied that increased PAH solution concentrations are the result of solution PAH-DOM associations. It is interesting to note that whatever soil-DOM-PAH mechanisms are operative in the Ti-citrate microcosm data, the degree of solubility increase was strongly influenced by PAH molecular weight (Fig.…”

Dimensionless volatilization rate for two pesticides in a lake

“…where K d is a partition coefficient that could be related to some specific properties of the chemical, such as octanol‐water partition coefficient (K ow ) that, in turn, could be measured directly or computed as a function of contaminant solubility (S w ) and molecular weight (M); moreover, K d depends also on the organic‐carbon content of the solids (Karickhoff et al 1979; Thomann & Mueller 1987; Chapra 1997; Hwang et al 1998).…”

“…TCDD-cumulative distribution function for log (vol). (Karickhoff et al 1979;Thomann & Mueller 1987;Chapra 1997;Hwang et al 1998).…”