Properties of black carbon and other insoluble light-absorbing particles in seasonal snow of northwestern China

Abstract

Abstract. A large field campaign was conducted and 284 snow samples were collected at 38 sites in Xinjiang Province and 6 sites in Qinghai Province across northwestern China from January to February 2012. A spectrophotometer combined with chemical analysis was used to measure the insoluble light-absorbing particles (ILAPs) and chemical components in seasonal snow. The results indicate that the cleanest snow was found in northeastern Xinjiang along the border of China, and it presented an estimated black carbon (CBCest) of approximately 5 ng g−1. The dirtiest snow presented a CBCest of approximately 450 ng g−1 near industrial cities in Xinjiang. Overall, the CBCest of most of the snow samples collected in this campaign was in the range of 10–150 ng g−1. Vertical variations in the snowpack ILAPs indicated a probable shift in emission sources with the progression of winter. An analysis of the fractional contributions to absorption implied that organic carbon (OC) dominated the 450 nm absorption in Qinghai, while the contributions from BC and OC were comparable in Xinjiang. Finally, a positive matrix factorization (PMF) model was run to explore the sources of particulate light absorption, and the results indicated an optimal three-factor/source solution that included industrial pollution, biomass burning, and soil dust.

Quantifying light absorption and its source attribution of insoluble light-absorbing particles in Tibet an Plateau glaciers from 2013–2015

“…Therefore, the second factor or source profile is easily interpretable as a natural soil dust source. But a notable feature is that the relative high mass loading of C BC max (76.4%) to that of the previously identified soil dust source as reported by Pu et al (2017). It is well known that K + and K Biosmoke are the 5 major indicators of biomass burning source (Zhang et al, 2013a).…”

“…In this study, two datasets including the mass concentrations of the chemical components and the ILAPs in snow/ice and the associated uncertainty datasets were used to run the PMF 5.0 model. The details of the techniques have already been illustrated by Hegg et al (2009Hegg et al ( , 2010 and Pu et al (2017). The factor loadings 20 (apportionment of species mass to individual factors) for the 3-factor solution of the source profiles based on the PMF 5.0 model are given in Fig.…”

Iron oxides in the cryoconite on the glaciers over Tibetan Plateau: abundance, speciation and implications

“…For the glaciers except BS, the absorption by goethite was larger than BC and approximately equal to organic matters. The increased contribution by goethite at the shorter wavelength was due to its large AAE 5 value (Zhou et al, 2017), which indicated stronger light absorption at short wavelength. While the relative contribution to absorption by hematite appeared to be constant between different wavelengths.…”

“…The light attenuation by samples on filter at specific wavelength will be converted to equivalent BC mass loading (L BC , µg C cm -2 ), which allows to calculate absorption optical depth τ(λ) by cryoconite: τ λ =L BC β λ . Where β λ is mass absorption coefficiency (MAC) of standard black carbon (i.e., fullerene, 6.3 m 2 g -1 at 550 nm) (Grenfell et al, 2011;Zhou et al, 2017). Then the light absorption capacity of cryoconite was calculated through 10 dividing the absorption optical depth by the mass loading on filter:…”

“…et al, 2017; Kaspari et al, 2015;Pu et al, 2017;Takeuchi, 2002). The complex of LAIs is particularly the case for the mountain glaciers in Himalayas and Tibetan Plateau (TP) (Fig.…”