TY  - JOUR
AB  - Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region.
AU  - Moschos, V.*
AU  - Dzepina, K.*
AU  - Bhattu, D.*
AU  - Lamkaddam, H.*
AU  - Casotto, R.*
AU  - Daellenbach, K.R.*
AU  - Canonaco, F.*
AU  - Rai, P.*
AU  - Aas, W.*
AU  - Becagli, S.*
AU  - Calzolai, G.*
AU  - Eleftheriadis, K.*
AU  - Moffett, C.E.*
AU  - Schnelle-Kreis, J.
AU  - Severi, M.*
AU  - Sharma, S.*
AU  - Skov, H.*
AU  - Vestenius, M.*
AU  - Zhang, W.*
AU  - Hakola, H.*
AU  - Hellen, H.*
AU  - Huang, L.*
AU  - Jaffrezo, J.L.*
AU  - Massling, A.*
AU  - Nøjgaard, J.K.*
AU  - Petäjä, T.*
AU  - Popovicheva, O.*
AU  - Sheesley, R.J.*
AU  - Traversi, R.*
AU  - Yttri, K.E.*
AU  - Schmale, J.*
AU  - Prévôt, A.S.H.*
AU  - Baltensperger, U.*
AU  - El Haddad, I.*
C1  - 64471
C2  - 51937
CY  - Heidelberger Platz 3, Berlin, 14197, Germany
SP  - 196-202
TI  - Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols.
JO  - Nat. Geosc.
VL  - 15
IS  - 3
PB  - Nature Portfolio
PY  - 2022
SN  - 1752-0894
ER  - 

TY  - JOUR
AB  - Dissolved organic matter affects fundamental biogeochemical processes in the soil such as nutrient cycling and organic matter storage. The current paradigm is that processing of dissolved organic matter converges to recalcitrant molecules (those that resist degradation) of low molecular mass and high molecular diversity through biotic and abiotic processes. Here we demonstrate that the molecular composition and properties of dissolved organic matter continuously change during soil passage and propose that this reflects a continual shifting of its sources. Using ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, we studied the molecular changes of dissolved organic matter from the soil surface to 60 cm depth in 20 temperate grassland communities in soil type Eutric Fluvisol. Applying a semi-quantitative approach, we observed that plant-derived molecules were first broken down into molecules containing a large proportion of low-molecular-mass compounds. These low-molecular-mass compounds became less abundant during soil passage, whereas larger molecules, depleted in plant-related ligno-cellulosic structures, became more abundant. These findings indicate that the small plant-derived molecules were preferentially consumed by microorganisms and transformed into larger microbial-derived molecules. This suggests that dissolved organic matter is not intrinsically recalcitrant but instead persists in soil as a result of simultaneous consumption, transformation and formation.
AU  - Roth, V.N.*
AU  - Lange, M.*
AU  - Simon, C.*
AU  - Hertkorn, N.
AU  - Bucher, S.*
AU  - Goodall, T.*
AU  - Griffiths, R.I.*
AU  - Mellado-Vázquez, P.G.*
AU  - Mommer, L.*
AU  - Oram, N.J.*
AU  - Weigelt, A.*
AU  - Dittmar, T.*
AU  - Gleixner, G.*
C1  - 56737
C2  - 47253
CY  - 75 Varick St, 9th Flr, New York, Ny 10013-1917 Usa
SP  - 755–761
TI  - Persistence of dissolved organic matter explained by molecular changes during its passage through soil.
JO  - Nat. Geosc.
VL  - 12
IS  - 9
PB  - Nature Publishing Group
PY  - 2019
SN  - 1752-0894
ER  -