Contaminant analysis in tundra by pyrolysis-GC/FID

摘要

A portion of the natural organic matter (NOM) in soil interferes with tests for petroleum contamination, inflating the values obtained for diesel-range organics (DRO) and residual-range organics (RRO). Currently, no standard method exists to separately quantify the fraction of DRO and RRO due to biogenic interference. Pyrolysis-GC/FID is being developed to quantify biogenic interference in contaminated soils. Analyses of 36 samples from a study site on the North Slope of Alaska were used to evaluate the newly developed method. The study area had no known history of contamination, so the measured DRO and RRO were attributed entirely to biogenic interference. A series of compounds common to all soil pyrolysates were examined as potential indicators of the quantity of biogenic interference. Numerous regression models were examined in order to determine the best form for a model to predict biogenic interference in soils. Linear models gave much higher r~2 values than any other form of model examined. Most of the 24 pyrolysis products examined were better predictors of biogenic DRO and RRO than was total ogranic content of the soil, as measured by loss on ignition. The best single compound predicted biogenic DRO and RRO with r~2 = 0.79 and 0.78, respectively; multiple linear regression models using four compounds gave r~2 = 0.90 and 0.92. Loss on ignition predicted DRO and RRO with r~2 = 0.30 and 0.36, respectively.