A previously unrecognized industrial source of atmospheric molecular bromine in eastern China

Abstract

Reactive bromine species play an important role in atmospheric oxidation, the ozone budget, and mercury transformation, yet their abundance and sources outside polar regions remain poorly characterized. Here we report measurements of episodic plumes of molecular bromine (Br2) in a high-tech industrial park in eastern China, with mixing ratios up to 23.4 ppt at night. The alignment of wind direction of high Br2 mixing ratios with the location of the pharmaceutical facilities, along with strong correlations with brominated organics and methylating agents, suggests pharmaceutical processes as the probable source. The elevated Br2 occasionally persisted after sunrise, contributing approximately 20% to the oxidation of isoprene in the morning. Based on national bromine consumption data and conservative emission factors, we estimate that Br2 emissions from the pharmaceutical industry could rival those from residential coal combustion by 2030. These findings highlight a previously unrecognized industrial source of reactive bromine with potentially significant implications for regional air quality.