Determination of Organic Material to Organic Carbon (OM/OC) Ratios by FT-IR Spectroscopy at Select Sites in the IMPROVE Network

摘要

A non-destructive technique for measuring organic functional groups, organic material and organic carbon was developed and applied to seven IMPROVE sites. Laboratory generated standards are used to create a calibration with partial least squares regression. In the IMPROVE network protocol, OC is measured using a thermal optical reflectance method and OM is estimated using an OM/OC ratio of 1.8. Using the FT-IR technique developed here, the median OM/OC ratio for the seven sites was 1.67 and the 10th and 90th percentiles were 1.43 and 2.00. Phoenix, AZ had the lowest annual-median value of 1.55 and Mesa Verde, CO had the highest of 1.83. The FT-IR measured sample, site and seasonal OM/OC ratios indicate that a single estimate of OM/OC does not represent the observed variability in OM/OC.