Characteristics and sources of halogenated hydrocarbons in the Yellow River Delta region, northern China

As important ozone-depleting substances and potential greenhouse gases, halocarbons have attracted much attention since 1970s. To better understand the characteristics and sources of halocarbons in the Yellow River Delta (YelRD) region, an important oil extraction and petrochemical industrial area in northern China, a two-phase (winter-spring and summer) intensive campaign was conducted in 2017. Compared with the Northern Hemispheric background, median enhancements of Montreal Protocol (MP) regulated species (CFCs, Halons and CH3CCl3) in this region were relatively small. Meanwhile, enhancements were relatively large for MP under control species (HCFCs and HFC-134a). Historical trends of halocarbons in China and the YelRD region both exhibited declining and increasing trends for MP regulated and under control species, respectively. Results above indicate effective implementation of MP in China. The enhancements of MP unregulated species were high as they are still used and uncontrolled. In addition, oil fields were found to have a negligible influence on ambient halocarbons in this region. The back-trajectory analysis shows that clusters from the North China Plain and East China were associated with the highest concentrations of most halocarbons during the winter-spring and summer periods, respectively. Source apportionment of halocarbons was carried out by positive matrix factorization (PMF). Model results indicate that biomass burning, marine, refrigerants and foam blowing, and solvent usage were the most important sources. This study provides the underlying insights into the characteristics and sources of halocarbons in the YelRD region.