Ambient levels of particulate organic matter in New York City in winter and summer

Abstract

Samples of suspended particulate matter were collected during two summer and two winter sampling campaigns. Non-polar, moderately polar and polar fractions of particulate organic matter (POM) were separated by 8h sequential Soxhlet extractions with cyclobexane, dichloromethane and acetone, respectively. Atmospheric concentrations of total POM averaged 13.0 μgm −3 for the two summer periods and 16.0 μgm −3 for the two winter periods. Extractable organic matter in respirable (D 50≤3.5 μm aerodynamic diameter) suspended particulate matter was 81% of the TSP organics during January–February 1978, but only 54% of TSP organics in August 1978. Evaluation of dispersion normalized aerosol concentrations of POM indicated that space heating contributed approximately 75% of the total POM in New York City in February 1977 and 51% in January–February 1978. The strong association of POM with the “oil-burning” factor obtained by factor analysis performed on the data was also indicative of a substantial contribution from this source. Use of high-sulfur (1.5–15 %) fuel oil in New York City during the 1976–1977 fuel crisis appears to have had a striking and significant impact on both total emissions and ambient concentrations of POM during February 1977. The cumulative evidence indicates oil-burning for space heating is currently the most significant source of POM although it contributes only 10–20% of the TSP. The atmospheric concentrations of POM and TSP determined in this study were compared to those measured at the same site in 1968 and 1969. Although wintertime TSP levels have declined to almost one-half of the levels of 1968 and 1969, wintertime concentrations of airborne POM do not appear to have declined. The summertime concentrations of POM in 1977 and 1978 were about 40% higher than those determined for similar periods in 1968 and 1969.