Variation characteristics, source analysis, and health risk assessment of carbonyl compounds in Zhangjiajie National Forest Park, China

Abstract

This study presents a comprehensive analysis of carbonyls in the atmosphere of Zhangjiajie Forest from May 2016 to January 2017 following the Environmental Protection Agency (EPA) TO-11 A guidelines, including pollution characteristics, human health risks, and sources. The dominant carbonyl compounds were formaldehyde, acetaldehyde, and acetone, with average concentrations of 5.94, 1.48, and 4.24 μg/m3, respectively. A seasonal variation was observed in the total carbonyl compound concentrations in the order summer > autumn > spring > winter. The diurnal patterns showed that the concentration of the main carbonyl compounds peaked in the afternoon. The ratios of formaldehyde/acetaldehyde (C1/C2) and acetaldehyde/propionaldehyde (C2/C3) ranged from 2.82 to 5.66 and 0.76–3.14; this indicates that compared with anthropogenic sources, volatile organic compounds emitted from natural sources contributed more significantly to atmospheric carbonyl compounds in the Zhangjiajie Forest. Correlation analysis of the three main carbonyl compounds with common air pollutants revealed that formaldehyde and acetaldehyde have similar secondary sources for photochemical reactions. In autumn and winter, acetaldehyde and acetone were affected by fuel combustion and vehicle exhaust emissions. Reverse trajectory, potential source contribution function, and concentration-weighted trajectory analyses revealed that carbonyl compounds in the atmosphere of Zhangjiajie Forest were mainly polluted locally in spring and autumn and influenced by the urban air mass from the northeast in summer and winter. The health risk assessment showed that the lifetime carcinogenic risk of formaldehyde and acetaldehyde exceeded the acceptable level and that long-term exposure to this concentration poses serious carcinogenic risks. The findings of this study shed light on the characteristics of atmospheric carbonyl compound pollution in subtropical forest areas, and provide scientific basis for formulating pollution control measures.