One hydrochlorofluorocarbon and two hydrofluorocarbons (HCFC-22, HFC-125 and HFC-152a) were measured in air samples at the Cape Point observatory (CPT), South Africa during 2017. These data represent the first such atmospheric measurements of these compounds from south western South Africa (SWSA). Baseline atmospheric growth rates were estimated to be 8.36 ppt yr-1 , 4.10 ppt yr-1 and 0.71 ppt yr-1 for HCFC-22, HFC-125 and HFC-152a, respectively. The CPT measurements were combined with an inverse model to investigate emissions from SWSA. For all three halocarbons, Cape Town was found to be the dominant source within SWSA. These estimates were extrapolated, based on population statistics, to estimate emissions for the whole of South Africa. We estimate South Africa's 2017 emissions to be 3.0 (1.6-4.4) Gg yr-1 , 0.8 (0.5-1.2) Gg yr-1 and 1.1 (0.6-1.6) Gg yr-1 for HCFC-22, HFC-125 and HFC-152a, respectively. For all three halocarbons, South Africa's contribution to global emissions is small (<2.5%), but future monitoring is needed to ensure South Africa's compliance with regulation set out by the Montreal Protocol and its Amendments.

Unregulated chlorocarbons, here defined as dichloromethane (CH 2 Cl 2 ), perchloroethene (C 2 Cl 4 ), chloroform (CHCl 3 ), and methyl chloride (CH 3 Cl), are gases not regulated by the Montreal Protocol. While CH 3 Cl is the largest contributor of atmospheric chlorine, recent studies have shown that growth in emissions of the less abundant chlorocarbons could pose a significant threat to the recovery of the ozone layer. Despite this, there remain many regions for which no atmospheric monitoring exists, leaving gaps in our understanding of global emissions. Here, we report on a new time series of chlorocarbon measurements from Cape Point, South Africa for 2017, which represent the first published high-frequency measurements of these gases from Africa. For CH 2 Cl 2 and C 2 Cl 4 , the majority of mole fraction enhancements were observed from the north, consistent with anthropogenically modified air from Cape Town, while for CHCl 3 and CH 3 Cl, we found evidence for both oceanic and terrestrial sources. Using an inverse method, we estimated emissions for south-western South Africa (SWSA). For each chlorocarbon, SWSA accounted for less than 1% of global emissions. For CH 2 Cl 2 and C 2 Cl 4 , we extrapolated using population statistics and found South African emissions of 8.9 (7.4−10.4) Gg yr −1 and 0.80 (0.64−1.04) Gg yr −1 , respectively.

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Benzene and toluene, emitted into the atmosphere from a number of common anthropogenic activities, pose a significant human health risk. The mole fractions of toluene and benzene were measured at two urban locations (Foreshore and Potsdam) in Cape Town and one background site at Cape Point, South Africa over the period of July-November 2017. The analysis of the mole fractions of benzene and toluene at two sampling sites in the city of Cape Town gave an indication of the probable anthropogenic sources of the air masses sampled at these sites. We propose that a traffic source dominated at the Foreshore site, while industrial processes dominated at the Potsdam site. The analysis of wind rose plots of benzene and toluene and the elevated mole fractions observed at the remote "clean air" sampling site, Cape Point, suggest that polluted air from Cape Town is the major source of the benzene and toluene mole fractions observed at Cape Point. Hydroxyl (OH) radical concentrations were estimated for Cape Town from the difference in T/B ([toluene]/[benzene]) ratios between Cape Town and Cape Point. The Cape Town OH estimations displayed a mean of (7.2 ± 3.5)  10 6 molecules cm -3 at the Foreshore site and (9.1 ± 4.4)  10 6 molecules cm -3 at the Potsdam site, without consideration of dilution reducing to (5.4 ± 3.4)  10 6 molecules cm -3 for the Foreshore site and (7.4 ± 4.6)  10 6 molecules cm -3 for Potsdam site for the period of July-November 2017 when dilution was considered. The estimated Cape Town OH concentrations are on the high side, but consistent with the results from other urban studies and may suggest a role for OH recycling following biogenic emissions between Cape Town and Cape Point.

Volatile organic halocarbons play a significant role in the biogeochemical cycling of halogens in the atmosphere. High frequency, in situ measurements of methyl iodide (CH3I), bromoform (CHBr3), dibromomethane (CH2Br2) and methyl bromide (CH3Br) were measured in the marine boundary layer at Cape Point, South Africa by an automated Absorption Desorption System-Gas Chromatography-Mass Spectrometer (ADS-GC-MS) between January and November 2017. These are the first multi-halocarbon measurements recorded at Cape Point and represent the longest time series to date. Baseline wind conditions were established using both wind direction and radon ( 222 Rn) concentration as markers of clean air. The baseline mixing ratios observed were 0.61 ± 0.29, 2.02 ± 0.89, 1.08 ± 0.17 and 6.09 ± 0.50 ppt, for CH3I, CHBr3, CH2Br2, and CH3Br, respectively. A statistically significant difference in short-lived halocarbon occurrence was established between anthropogenically affected and clean marine air masses for CH3Br at the Cape Point site. The CHBr3 and CH2Br2 mixing ratios were not statistically different (p > 0.05) when comparing the anthropogenically affected and clean marine air masses.The mixing ratios of CH3I suggested a strong seasonal variation with higher production in austral Summer-Autumn months than in the austral Winter-Spring months. A general chemical decay line was calculated for baseline CH2Br2 and CHBr3 measurements at Cape Point. An analysis of the ln([CH2Br2]/[CHBr3]):ln([CHBr3]) ratio for the Cape Point dataset exhibited a slight deflection to the right of the general chemical decay line, suggesting the influence of greater [CHBr3]:[CH2Br2] source ratios rather than their dilution.