Congener-specific analysis of the accumulation of polychlorinated biphenyls (PCBs) by aquatic organisms in the maximum turbidity zone of the St. Lawrence estuary, Québec, Canada.

The polychlorinated biphenyl (PCB) contamination of the biota of the St. Lawrence estuary maximum turbidity zone (MTZ) was investigated. The species analyzed consist of zooplankton (mostly Neomysis americana), larval smelt (Osmerus mordax), juvenile smelt, juvenile tomcod (Microgadus tomcod) and adult smelt, tomcod and capelin (Mallotus villosus). A significant increase in total PCB contamination from zooplankton to all fish developmental stages indicates that the St. Lawrence MTZ is a site of significant PCB contamination. The total PCB contamination of adult smelt and tomcod sampled in the St. Lawrence MTZ was greater than the limit of 0.1 ppm set by the International Joint Commission for the protection of predators. For zooplankton, tomcod and capelin, significant correlations were found between lipid content and PCB contamination. The congener-specific analyses showed that the bioconcentration factor of the individual congeners varied with the species involved and with the molecular structure of the congener. It was found that the chlorine atoms in positions 2, 4 and 5 on at least one phenyl ring of the PCB molecule was a dominant factor causing accumulation of PCBs in aquatic organisms. The pattern of PCB congeners found in beluga (Delphinapterus leucas) whale tissues is similar to the PCB pattern found in the St. Lawrence estuary MTZ biota.

Export of mirex from Lake Ontario to the St. Lawrence Estuary.

The relative importance of migrating eels and suspended particulate material (biotic and abiotic) as transporters of mirex from Lake Ontario to the St. Lawrence River Estuary is evaluated in the context of a possible adverse impact on the St. Lawrence beluga population. Our estimates suggest that transport of mirex out of Lake Ontario by eels (2270 g annually) is almost twice that due to suspended particulate flux (1370 g annually). Mass balance calculations for mirex in Lake Ontario indicate that transport by migrating eels and particulate matter, combined with coverage of surficial sediments by continuing deposition of new material, could effectively "cleanse" Lake Ontario of mirex inputs in 100 years or less. Using mirex as a prototype to simulate the fate of hydrophobic organic chemicals in Lake Ontario led to a revised sediment budget for this final lake in the Great Lakes-St. Lawrence system. According to this budget, 94% of the suspended particulate material entering Lake Ontario is retained in the depositional basins and, by inference, most hydrophobic organic contaminants and metal forms having a dominant association with the particulate phase, would be expected to behave in a similar fashion.

Chemical ionization and high resolution electron impact mass spectra of 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide and three of its metabolites.

The electron impact and the hydrogen and methane chemical ionization mass spectra of 5,6-dihydro-2-methyl-1,4-oxathin-3-carboxanilide, the sulfoxide and sulfone derived therefrom, and 2-(2-hydroxyethylthio)-acetoacetanilide enol have been determined. All four compounds show abundant molecular ions in the electron impact spectra and abundant [MH]+ ions in the methane chemical ionization spectra (along with the expected [M + C2H5]+ and [M + C3H5]+ ions), but relatively low [MH]+ ion signals in the hydrogen chemical ionization spectra. From high resolution mass measurements and metastable transitions determined by metastable ion refocusing, electron impact fragmentation mechanisms have been established. For 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide, 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide-4-oxide and 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide-4,4-dioxide the major fragmentation mode involves loss of the anilino radical from [M]+, followed by loss of C2H4. Fragmentation to form the aniline molecular ion increases in importance with increasing oxidation state of the sulfur. In the chemical ionization of these three compounds fragmentation of [MH]+ proceeds in a similar fashion by loss of neutral aniline and by formation of protonated aniline. The electron impact mass spectrum of 2-(2-hydroxyethylthio)acetoacetanilide is dominated by the molecular ion and the aniline molecular ion. However, in the chemical ionization mass spectra characteristic fragment ions involving loss of water and loss of aniline from [MH]+, as well as protonated aniline, are observed and serve to characterize the compound.

Mass spectra of sodium N-alkyl and N,N-dialkyl dithiocarbamates and some related compounds.

Electron impact mass spectra of 8 sodium alkyl and dialkyl dithiocarbamate salts are reported with the spectra of 2 dithiocarbamate zinc salts and N',N'-dimethyl-N,N-dimethylthiocarbamylsulfenamide. The investigated compounds all gave molecular ions, and generalized descriptions of their fragmentation behavior are presented.

Gas chromatographic identification of some organochlorine pesticides and their photoalteration products by means of Kovats' retention indices.

Kovats' retention indices and temperature coefficients for some chlorinated methanonaphthalene and methanoindene pesticides and their photoproducts were determined on an OV-17 silicone liquid phase at three different temperatures. A detailed procedure for the off-line calculation of the retention indices, (see article) and I values are described. The program, written in BASIC, calculates the indices at three different temperatures and provides a computer-written report.

Isolation and characterization of the photoalteration products of cis- and trans-chlordane.

Ultraviolet irradiation of cis- and trans-chlordane yielded 3 photolysis products. The expected half-caged analog of cis-chlordane was formed in high yield, and 2 minor photoproducts of trans-chlordane were observed. One of these products was a half-caged isomer. The individual photoproducts were isolated by thin layer chromatography and characterized by infrared, nuclear magnetic resonance, and mass spectrometry.