This study provides the feasibility of using a single-particle ICP-MS technique for convenient and routine monitoring of engineered nanomaterials in tap water.

Abstract. Carbonaceous aerosol is mainly composed of organic carbon (OC) and elemental carbon (EC). Both OC and EC originate from a variety of emission sources. Radiocarbon (14C) analysis can be used to apportion bulk aerosol, OC, and EC into their sources. However, such analyses require the physical separation of OC and EC. Here, we apply of ECT9 protocol to physically isolate OC and EC for 14C analysis and evaluate its effectiveness. Several reference materials are selected, including: two pure OC (fossil adipic acid, contemporary sucrose), two pure EC (fossil regal black and C1150), and three complex materials containing contemporary and/or fossil OC and EC (rice char and NIST urban dust standards SRM1649a, i.e., bulk dust and SRM8785, i.e., fine fraction of re-suspended SRM1649a on filter). The pure materials were measured for their OC, EC and total carbon (TC) mass fractions and corresponding carbon isotopes to evaluate the uncertainty of the procedure. The average accuracy of TC mass, determined via volumetric injection of a sucrose solution, was approximately 5 %. Ratios of EC/TC and OC/TC were highly reproducible, with analytical precisions better than 2 % for all reference materials, ranging in size from 20 to 100 µg C. Consensus values were reached for all pure reference materials for both δ13C and FM14C with an uncertainty of

Composition of individual atmospheric particles reveals the influence of marine sources, terrestrial sources, and anthropogenic sources on atmospheric chemistry in the changing Alaskan Arctic.

Elemental carbon (EC) is a major light-absorbing component of atmospheric aerosol particles. Here, we report the seasonal variation in EC concentrations and sources in airborne particulate matter (PM) and snow at Alert, Canada, from March 2014 to June 2015. We isolated the EC fraction with the EnCan-Total-900 (ECT9) protocol and quantified its stable carbon isotope composition (δ 13 C) and radiocarbon content (Δ 14 C) to apportion EC into contributions from fossil fuel combustion and biomass burning (wildfires and biofuel combustion). Ten-day backward trajectories show EC aerosols reaching Alert by traveling over the Arctic Ocean from the Russian Arctic during winter and from North America (>40°N) during summer. EC concentrations range from 1.8-135.3 ng C m −3 air (1.9-41.2% of total carbon [TC], n = 48), with lowest values in summer (1.8-44.5 ng C m −3 air, n = 9). EC in PM (Δ 14 C =-532 ± 114‰ [ave. ± SD, n = 20]) and snow (−257 ± 131‰, n = 7) was depleted in 14 C relative to current ambient CO 2 year-round. EC in PM mainly originated from liquid and solid fossil fuels from fall to spring (47-70% fossil), but had greater contributions from biomass burning in summer (48-80% modern carbon). EC in snow was mostly from biomass burning (53-88%). Our data show that biomass burning EC is preferentially incorporated into snow because of scavenging processes within the Arctic atmosphere or long-range transport in storm systems. This work provides a comprehensive view of EC particles captured in the High Arctic through wet and dry deposition and demonstrates that surface stations monitoring EC in PM might underestimate biomass burning and transport. Plain Language Summary Elemental carbon (EC) aerosols are produced during combustion processes and impact Arctic climate because they absorb light, warm the atmosphere, and accelerate snow and ice melt. Here, we measured the concentration and isotopic composition of EC suspended in the atmosphere and in snow at Alert, Canada, between March 2014 and May 2015. We found that concentrations were lowest during the summer and increased throughout the winter and early spring. This pattern is typical, because EC is removed from the atmosphere by precipitation, which happens more frequently during summer. Our isotope data and meteorological analyses revealed that fossil fuel burning in the Russian Arctic was an important source of EC to Alert from September to May, while forest fires in the North American boreal region were major sources of EC during the summer. We also found that snow contained a greater proportion of EC derived from biomass burning than the suspended aerosols. Snow might be preferentially capturing biomass burning EC from the local atmosphere or be transporting them to the Arctic from lower latitudes. Since EC surface observing networks routinely measure EC in PM but not snow, the impact of biomass burning EC sources on Arctic climate might be underestimated.