Hydroxyl radical (OH) is an important oxidant in atmospheric aqueous phases such as cloud and fog drops and water-containing aerosol particles. We find that numerical models nearly always overestimate aqueous hydroxyl radical concentrations because they overpredict its rate of formation and, more significantly, underpredict its sinks. To address this latter point, we examined OH sinks in atmospheric drops and aqueous particles using both new samples and an analysis of published data. Although the molecular composition of organic carbon, the dominant sink of OH, is extremely complex and poorly constrained, this sink behaves very similarly in different atmospheric waters and even in surface waters. Thus, the sink for aqueous OH can be estimated as the concentration of dissolved organic carbon multiplied by a general scavenging rate constant [kC,OH = (3.8 ± 1.9) × 10(8) L (mol C)(-1) s(-1)], a simple process that should significantly improve estimates of OH concentrations in atmospheric drops and aqueous particles.

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We investigated the simple and rapid preparation of standard materials of major and trace elements in aerosol particles for X‐ray fluorescence (XRF) analysis to study long‐range transport of air pollutants in East Asia. Standard materials for calibration curve were prepared using a small‐chamber sampling technique consisted of a 3‐L cylindrical acrylic chamber, aerosol filter holder, flow meter, and vacuum pump. Prepared aerosol standard materials had an excellent homogeneity in 0.5 mm × 0.5 mm analytical area. XRF analysis was performed by a bench top energy‐dispersive X‐ray fluorescent spectrometer. For only arsenic analysis, synchrotron radiation XRF was applied because As‐Kα line (10.53 keV) was overlapped by Pb‐Lα line (10.55 keV) in a typical XRF measurement. The calibration curves of 15 elements (K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba, and Pb) showed a good linearity. The prepared standard materials were applied to determine metal elements in total suspended particle (TSP) aerosols, which were collected at Kume Island in Okinawa, Japan, from June 2008 to June 2010, and analytical results in XRF were compared with those of inductively coupled plasma atomic mass spectrometry (ICP‐MS) or atomic absorption spectrometry (AAS). Analytical results of TSP aerosol between XRF and ICP‐MS or AAS had a strong correlation higher than 0.800 for all elements.