A set of high-quality, age-specific biota-sediment accumulation factors (BSAFs) for polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) have been determined from concentrations measured with high-resolution gas chromatography/high-resolution mass spectrometry, by use of the 13C isotopic dilution technique, in lake trout and surficial (0-2 cm) sediment samples from southern Lake Michigan. BSAFs ranged from <0.1 to 18 for PCBs and from <0.001 to 0.32 for PCDDs and PCDFs detected in the fish. PCBs with zero or one chlorine in an ortho position had smaller BSAFs than other PCBs. PCDDs and PCDFs with chlorines at the 2,3,7,8-positions had larger BSAFs than most other PCDDs and PCDFs. The fidelity of the relative bioaccumulation potential data between independent lake trout samples, within and among age classes, suggests that differences in slight rates of net metabolism in the food chain are important and contribute to the apparent differences in BSAFs, not only for PCDDs and PCDFs but also possibly for some PCBs. A complicating factor for non-ortho- and mono-ortho-PCBs is the uncertain contribution of enhanced affinity for black carbon (and possibly volatility) acting in concert with metabolism to reduce measured BSAFs for lake trout. On the basis of the association between chemicals with apparent slight rates of metabolism and measured dioxin-like toxicity, several PCDFs with similar measured BSAFs but unknown toxicity may be candidates for toxicity testing.
Kinetic expressions for the aqueous reactions of chlorine with phenanthrene (pH 3-10), fluorene (pH 3-5), and fluoranthene (pH 3-5) have been developed. At pH 3-5 the rate of reaction of each PAH studied could be related to the chlorine concentration (-d[PAH]). Phenanthrene, also studied at high pH values (pH >8.8), followed a rate expression consistent with pseudo-first-order kinetics (-d[phen]). The overall rate expression that was developed for phenanthrene is suggested as a model for correlating the rates of reaction of chlorine with polynuclear aromatic compounds in water over the entire pH range (pH 3-10) that might reasonably be encountered during disinfection. This overall expression is Cl•, and O" (24).The arene oxide (phenanthrene 9,10-oxide) was the predominant phenanthrene product at pH 54 while phenanthrene-9,10-dione and 9-chlorophenanthrene were the major products at pH S4.
A toxicity identification evaluation (TIE) conducted on a municipal wastewater discharge from the southeast United States was part of a research project aimed at developing U.S. Environmental Protection Agency (EPA) TIE methods for acutely toxic effluents. The effluent consistently exhibited acute toxicity to Ceriodaphnia dubia but not to fathead minnows (Pimephales promelas). Toxicity characterization procedures revealed that the primary toxicant was a nonpolar organic. Toxicity was recovered through C18 solid‐phase extraction and concentration steps. Gas chromatography–mass spectroscopy of these concentrates revealed the presence of diazinon (O, O‐diethyl O‐[6‐methyl‐2‐(1‐methylethyl)‐4‐pyrimidinyl] phosphorothioate). Diazinon concentrations in whole effluent, determined by GC analyses, correlated well with the toxicity measurements of each sample. Relative species sensitivity also implicated diazinon as the primary toxicant. This study illustrates the successful application of EPA TIE methodologies for identifying a nonpolar organic toxicant in a complex effluent. The significance of detecting diazinon at acutely toxic concentrations in municipal wastewater may indicate a more widespread problem in this region of the United States. This toxicity problem may be attributed to the chemical characteristics of diazinon and its applications.
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