Impact of recent urbanization on formic and acetic acid concentrations in coastal North Carolina rainwater

Concentrations of formic and acetic acids in Wilmington, North Carolina, US A, rainwater collected between 1996 and 1998 have increased dramatically si nce an earlier study conducted at the same site between 1987 and 1989. The current volume-weighted concentrations of acetic acid are within the range of values reported for urban locations whereas values from the earlier stud y at this site were similar to those obtained for rural locations. The rati os of formic to acetic acids (F:A) in the current study (approximately 1:1) are considerably lower than those previously reported (approximately 2.7:1 ). Current F:A's are similar to F:A's from direct automobile emissions. Inc reases in formic and acetic acid concentrations and the shift in formic to acetic acid ratios likely reflect the impact of extensive population growth in the surrounding region. Assuming increases in formic and acetic acid co ncentrations result from increased anthropogenic sources, we estimate at le ast 1/2 of the formic and at least 2/3 of the acetic acid in Wilmington, NC growing season rainwater results from anthropogenic sources. (C) 2001 Else vier Science Ltd. All rights reserved.