ORCID Profile
0000-0002-8251-6603
Current Organisation
University of California, Irvine
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Publisher: Proceedings of the National Academy of Sciences
Date: 19-11-2018
Abstract: We report radiocarbon ( 14 C) measurements of carbonaceous aerosol originating from fires on the islands of Sumatra and Borneo. These data provide information about what types of ecosystems burned and are critical for linking the human health effects of fires to the anthropogenic build-up of atmospheric CO 2 . Our measurements confirm that peat emissions were the dominant source of aerosols in Singapore during the 2015 El Niño and provide a means for monitoring the success of policies designed to protect peatland areas during future drought events.
Publisher: American Geophysical Union (AGU)
Date: 09-2020
DOI: 10.1029/2020GB006672
Abstract: The magnitude of future emissions of greenhouse gases from the northern permafrost region depends crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon ( 14 C) to quantify the release of this “old” SOC as CO 2 or CH 4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14 C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14 C‐CO 2 emissions generally had a modern (post‐1950s) signature, but that well‐drained, oxic soils had increased CO 2 emissions derived from older sources following recent thaw. The age of CO 2 and CH 4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously frozen SOC as CO 2 , CH 4 , and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of “old” sources among studies h er the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14 C studies in the permafrost region.
Publisher: American Geophysical Union (AGU)
Date: 05-12-2020
DOI: 10.1029/2020JD033125
Abstract: 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 (∆ 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 ( °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.
No related grants have been discovered for Claudia I. Czimczik.