Influence of ortho-Substitution on Patterns of PCB Accumulation in Sediment, Plankton, and Fish in a Freshwater Estuary

Abstract

The accumulation of a group of non-and mono-ortho (coplanar) PCB congeners in aquatic food webs is of special interest due to their dioxin-like toxicities. Furthermore, higher octanol-water partition coefficients than homologs with greater ortho-substitution suggest the potential for selective accumulation of the coplanar congeners. We quantified 47 PCB congeners containing 0-3 ortho-chlorines from six homolog groups in sediments, plankton, and fish from Green Bay, WI, using conventional and multidimensional gas chromatography with electron capture detection. Of the congeners exhibiting dioxin-like toxicity, the only nonortho-substituted congener quantifiable in any of the matrices was IUPAC 77, but all of the toxic mono-ortho-substituted congeners were detected and quantified. Penta-, hexa-, and heptachloro congeners were enriched relative to other congeners in sediments and fish located more distant from the main source of the bay, whereas trichloro congeners were depleted. The same homolog groups also became more enriched as PCBs moved to higher levels in the ecosystem from sediment to plankton to fish, while trichloro congeners were depleted. Enrichment patterns of the most toxic (dioxin-like) congeners were also influenced mainly by total chlorine substitution; the degree of orthosubstitution did not systematically affect accumulation in plankton and fish.

Effects of sedimentary sootlike materials on bioaccumulation and sorption of polychlorinated biphenyls

“…An exception is the trichlorobiphenyl group, for which a fully planar congener is missing. The observed patterns are consistent with those reported in the literature [16,18]. In Figure 2, BSAF values from Figure 1b are rearranged and presented per type of sediment in separate subgraphs (a, b, and c).…”

“…For PCBs, bioaccumulation might also depend on the molecular configuration (molecular planarity) of the congener of interest. In fact, this may explain the reduced accumulation or the absence of preferential accumulation of coplanar PCBs in aquatic organisms from the field, which has been observed by some researchers [18,19]. On the other hand, soot is able to preferentially sorb coplanar PCBs [13], which theoretically could lead to reduced bioaccumulation of these congeners from sediments containing soot.…”

A preliminary investigation of the environmental impact of a thermal power plant in relation to PCB contamination

“…The congener profile of Se5, the sediment sample located farthest from the STTP, differs from the other profiles as it contains considerably higher proportions of tri-and tetra-chlorobiphenyls. This suggests downstream transport of relatively more soluble, lower chlorinated congeners (Willman et al 1997). The average congener profile of the sediments is very similar to that of the late production Aroclor 1254 (also plotted in Fig.…”

Contaminant exposure of birds nesting in Green Bay, Wisconsin, USA

“…Fish have been shown to deplete lower number PCB congeners more rapidly than higher numbered congeners [10,11], and as a result, fish-eating birds may be less exposed to those congeners. As expected, total PCBs were higher in eggs of 3 piscivorous birds compared with the insectivorous tree swallow.…”

“…Fish have been shown to deplete lower number PCB congeners, including PCB 77, more rapidly than higher numbered congeners [10,11], and as a result, fish-eating birds may be less exposed to those congeners. Fish have been shown to deplete lower number PCB congeners, including PCB 77, more rapidly than higher numbered congeners [10,11], and as a result, fish-eating birds may be less exposed to those congeners.…”