Determination of eight synthetic pyrethroids in bovine fat by gas chromatography with electron capture detection.

Synthetic pyrethroids are among the most widely used classes of insecticides, and their uses are varied, including plant protection, animal dips, and as a treatment for human clothing and bedding in very hot climates. Veterinary applications include ear tags, pour-on formulations, sprays, and dips. Persistent residues have been reported in livestock, and routine monitoring programs in other countries have found detectable residues of various pyrethroids in fat. A method has been developed using solid-phase extraction that reduces the quantities of solvents used, the time required, and the amount of glassware used compared to an earlier method on which it was based. The scope of analytes tested included the 5 compounds cited in the earlier method (flucythrinate, permethrin, cypermethrin, fenvalerate, and deltamethrin) and, in addition, cyfluthrin, lambda-cyhalothrin, and fluvalinate. Sample extracts were analyzed by gas chromatography with electron capture detection using selected chromatographic peaks characteristic of each compound. Limits of quantification for the compounds were from 25-50 microg/kg, with a linear response for all compounds to 200 microg/kg. Recoveries ranged from 80 to 123%.

Spatial patterns of natural polycyclic aromatic hydrocarbons in sediment in the lower Athabasca River.

The Athabasca Oil Sands is one of the four natural oil sands deposits in Northern Alberta, Canada, and are by far the largest oil sand deposit in North America, covering an area of 46,000 km2. Sediment samples were collected from the bed and bank of several tributaries that have naturally occurring exposures of oil sand material. Oil sand deposited along the lower Athabasca River, more than 100 km downstream of naturally occurring oil sand exposures, were also sampled. The levels of alkylated polycyclic aromatic hydrocarbons (PAHs) in samples collected from these various locations ranged from not detected to almost 50 ppm. Using dibenzothiophene/chrysene (C2/D2 vs. C3/D3) double ratio plots, it is possible to approximate the relative degree of degradation or weathering of the PAHs from these various sediment deposits along the lower Athabasca River and its tributaries. Similarly a plot of dibenzothiophene/phenanthrene (D2/P2 vs. D3/P3) indicate the possible origins of the oil. A combination of these plots, D3/P3 vs. D3/C3, was particularly useful in identifying weathering characteristics of different sources of the oil. Comparison of alkylated PAH distributions between the lower Athabasca River and the tributaries show slight differences consistent with different petrogenic sources and/or different weathering patterns.

Origin of polycyclic aromatic hydrocarbons in lake sediments of the Mackenzie Delta.

The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) were assessed in sediment cores from among 14 lakes from three regions comprising a transect across the central Mackenzie Delta. PAHs were consistently found in the lake sediments, with parent concentrations in the 20-200 ng/g range. Concentrations were generally independent of depth in the sediment cores and this pattern was similar among the 3 regions of the delta. Concentrations increased in a westerly direction among the regions. For some lakes, the concentration of PAHs decreased with decreasing flooding frequency, and decreasing sedimentation rates. For the latter, maximum concentrations occurred at shallower depths within the sediment cores as flooding frequency among the lakes decreased. The distributions of C0-C4 alkylated 2- and 3- ring PAHs were consistent with a petrogenic origin, while the corresponding distribution of 4-ring PAHs appears to be more consistent with a biogenic or pyrogenic origin. Based on relative contributions to the overall PAH budget, a petrogenic source appears to be dominant. However, the pyrene/fluoranthene ratio is more consistent with a source derived from peat. The alkylated PAH profiles are inconsistent with those in the Athabasca River system, and supports a previously published hypothesis that the contribution of PAHs from the Athabasca oil sands to the lower Mackenzie River is minimal. A double ratio plot of chrysene vs dibenzothiophene, diagnostic of weathering, suggests most weathering occurred before the sediments were deposited in the lakes, while a double ratio plot of dibenzothiophene vs phenanthrene suggests a common source of PAHs across the delta, despite differing water sources from east to west across the delta. PAH inputs to the delta appear to mirror sediment inputs documented in previous work, where high sediment input from the Mackenzie mainstem during high floods dominates the delta sediment influx and masks any influence of the Peel River.