Organic and elemental carbon in atmospheric fine particulate matter in an animal agriculture intensive area in North Carolina

Abstract

Carbonaceous components contribute significant fraction of fine particulate matter (PM2.5). Study of organic carbon
(OC) and elemental carbon (EC) in PM2.5 may lead to better understanding of secondary organic carbon (SOC) formation. This year-long (December 2008 to December 2009) field study was conducted in an animal agriculture intensive
area in North Carolina of United States. Samples of PM2.5 were collected from five stations located in an egg production
facility and its vicinities. Concentrations of OC/EC and thermograms were obtained using a thermal-optical carbon
analyzer. Average levels of OC in the egg production house and at ambient stations were 42.7 µg/m3
and 3.26 - 3.47
µg/m3
, respectively. Average levels of EC in the house and at ambient stations were 1.14 µg/m3
and 0.36 - 0.42 µg/m3
,
respectively. The OC to total carbon (TC) ratios at ambient stations exceeded 0.67, indicating a significant fraction of
SOC presented in PM2.5. Principal factor analysis results suggested that possible major source of in-house PM2.5 was
from poultry feed and possible major sources of ambient PM2.5 was from contributions of secondary inorganic and organic PM. Using the OC/EC primary ratio analysis method, ambient stations SOC fractions ranged from 68% to 87%.
These findings suggested that SOC could appreciably contribute to total PM2.5 mass concentrations in this agriculture
intensive area.