Over an 8-day (Monday to Monday) period from 2 - 10 May 2016, we measured Hg0(g) outside our building in Longyearbyen at 10-minute intervals. The Hg0(g) measurements using a Lumex RA-915+ spectrometer were taken ~725 meters from the discharge of a coal-fired power plant. UV-A and UV-B radiation fluz, air temperature and wind speed and direction was also measured. Concentrations of Hg0(g) ranged from 1 ng m-3 to an extreme event reaching 42.8 ng m-3; the results have a high average of 2.9 ng m-3 (n = 1131). The Hg0(g) concentrations had a strong daily cycle, ranging from 2 to 5.5 ng m-3, the lowest near midnight and the peak in the early afternoon. The UV results, measured on horizontal sensors, also had a daily cycle and ranged from 0.5 to 16.1 W m-2 for UV-A and 0.05 to 0.745 W m-2 for UV-B with low readings at night and high near noon. There is a high correlation between Hg0(g) and both UV readings, but there is no chemical reason for high UV causing greater release of Hg0(g) or reduction of Hg<sup>2+</sup>. The Hg0(g) results are not related to air temperature, wind speed or direction: In fact, the sampler was upwind of the power plant during most of the sampling period. No apparent sources of Hg0(g) were upwind of the sampling site at the time. In Barentsburg, a Lumex RA-915+ was also put in service during May 2016. We have comparable data for 3 hours on 3 May. Those results show similar concentrations between 2 - 3 ng m-3 until early afternoon, then a decline at Barentsburg to ~1 ng m-3 while the concentrations in Longyearbyen remain unchanged but eventually began rising to a daily peak of ~5.5 ng m-3. The first Monday-Monday Barentsburg results were from 23 – 30 May and also show some daily cycles, with low values near 1.0 ng m-3 at night – on some nights – and higher values at other times generally between 2.0 – 2.5 ng m-3. The Barentsburg amounts never exceeded ~2.7 ng m-3 while Longyearbyen highest concentrations, without the extreme event, were twice as high. The Barentsburg average = 2.00 ng m-3 (n = 1960). Both Longyearbyen and Barentsburg average results are higher than background concentrations found elsewhere in the Arctic, which range from ~1.3 – 1.8 ng m-3. The results show that there are Hg0(g) sources even at these remote Arctic sites, and that observation of trends needs to continue to identify possible annual variations. Further information about combustion conditions at the two power plants is also needed.

Gas-phase mercury cycles during May at urban/industrial sites on Svalbard

253rd National Meeting (2017)

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