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1. Measurement report: Molecular composition and volatility of gaseous organic compounds in a boreal forest – from volatile organic compounds to highly oxygenated organic molecules

   https://doi.org/10.5194/acp-21-8961-2021  

   Huang, Wei ; Li, Haiyan ; Sarnela, Nina ; Heikkinen, Liine ; Tham, Yee Jun ; Mikkilä, Jyri ; Thomas, Steven J. ; Donahue, Neil M. ; Kulmala, Markku ; Bianchi, Federico ( January 2021 , Atmospheric Chemistry and Physics)

   null (Ed.)

   Abstract. The molecular composition and volatility of gaseous organiccompounds were investigated during April–July 2019 at the Station forMeasuring Ecosystem – Atmosphere Relations (SMEAR) II situated in a borealforest in Hyytiälä, southern Finland. In order to obtain a morecomplete picture and full understanding of the molecular composition andvolatility of ambient gaseous organic compounds (from volatile organiccompounds, VOCs, to highly oxygenated organic molecules, HOMs), twodifferent instruments were used. A Vocus proton-transfer-reactiontime-of-flight mass spectrometer (Vocus PTR-ToF; hereafter Vocus) wasdeployed to measure VOCs and less oxygenated VOCs (i.e., OVOCs). Inaddition, a multi-scheme chemical ionization inlet coupled to an atmosphericpressure interface time-of-flight mass spectrometer (MION API-ToF) was usedto detect less oxygenated VOCs (using Br− as the reagent ion; hereafterMION-Br) and more oxygenated VOCs (including HOMs; using NO3- asthe reagent ion; hereafter MION-NO3). The comparison among differentmeasurement techniques revealed that the highest elemental oxygen-to-carbonratios (O : C) of organic compounds were observed by the MION-NO3 (0.9 ± 0.1, average ± 1 standard deviation), followed by the MION-Br(0.8 ± 0.1); lowest O : C ratios were observed by Vocus (0.2 ± 0.1). Diurnal patternsof the measured organic compounds were found to vary among differentmeasurement techniques, even for compounds with the same molecular formula,suggesting contributions of different isomers detected by the differenttechniques and/or fragmentation from different parent compounds inside theinstruments. Based on the complementary molecular information obtained fromVocus, MION-Br, and MION-NO3, a more complete picture of the bulkvolatility of all measured organic compounds in this boreal forest wasobtained. As expected, the VOC class was the most abundant (about 53.2 %), followed by intermediate-volatility organic compounds (IVOCs, about45.9 %). Although condensable organic compounds (low-volatility organiccompounds, LVOCs; extremely low volatility organic compounds, ELVOCs; andultralow-volatility organic compounds, ULVOCs) only comprised about 0.2 %of the total gaseous organic compounds, they play an important role in newparticle formation as shown in previous studies in this boreal forest. Ourstudy shows the full characterization of the gaseous organic compounds inthe boreal forest and the advantages of combining Vocus and MION API-ToF formeasuring ambient organic compounds with different oxidation extents (fromVOCs to HOMs). The results therefore provide a more comprehensiveunderstanding of the molecular composition and volatility of atmosphericorganic compounds as well as new insights into interpreting ambientmeasurements or testing/improving parameterizations in transport and climatemodels. 

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2. Organic amendments change soil organic C structure and microbial community but not total organic matter on sub-decadal scales

   https://doi.org/10.1016/j.soilbio.2020.107986  

   Xu, Jiangbing ; Roley, Sarah S. ; Tfaily, Malak M. ; Chu, Rosalie K. ; Tiedje, James M. ( November 2020 , Soil Biology and Biochemistry)

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3. Effects of organic sulfur and arsenite/dissolved organic matter ratios on arsenite complexation with dissolved organic matter

   https://doi.org/10.1016/j.chemosphere.2022.134770  

   Abu-Ali, Lena ; Yoon, Hyun ; Reid, Matthew C. ( September 2022 , Chemosphere)
4. Particulate Organic Carbon Deconstructed: Molecular and Chemical Composition of Particulate Organic Carbon in the Ocean

   https://doi.org/10.3389/fmars.2020.00518  

   Kharbush, Jenan J. ; Close, Hilary G. ; Van Mooy, Benjamin A. ; Arnosti, Carol ; Smittenberg, Rienk H. ; Le Moigne, Frédéric A. ; Mollenhauer, Gesine ; Scholz-Böttcher, Barbara ; Obreht, Igor ; Koch, Boris P. ; et al ( June 2020 , Frontiers in Marine Science)
5. Copper oxide nanoparticle dissolution at alkaline pH is controlled by dissolved organic matter: influence of soil-derived organic matter, wheat, bacteria, and nanoparticle coating

   https://doi.org/10.1039/d0en00574f  

   Hortin, J. M. ; Anderson, A. J. ; Britt, D. W. ; Jacobson, A. R. ; McLean, J. E. ( January 2020 , Environmental Science: Nano)

   Dissolution of CuO nanoparticles, releasing Cu ions, is a primary mechanism of Cu interaction in the rooting zone of plants. CuO dissolution is sometimes incorrectly considered negligible at high pH, since complexation of Cu with dissolved organic matter may enhance nanoparticle dissolution. Therefore data on the effects of plant-microbial-soil interactions on nanoparticle dissolution, particularly in alkaline soils, are needed. Dissolution of CuO nanoparticles (100 mg kg −1 Cu) was studied in sand supplemented with factorial combinations of wheat growth, a root-colonizing bacterium, and saturated paste extracts (SPEs) from three alkaline, calcareous soils. In control sand systems with 3.34 mM Ca(NO 3 ) 2 solution, dissolved Cu was low (266 μg L −1 Cu). Addition of dissolved organic matter via wheat root metabolites and/or soil SPEs increased dissolved Cu to 795–6250 μg L −1 Cu. Dissolution was correlated with dissolved organic carbon ( R = 0.916, p < 0.0001). Ligands >3 kDa, presumably fulvic acid from the SPEs, complexed Cu driving solubility; the addition of plant exudates further increased solubility 1.5–3.5×. The root-colonizing bacterium decreased dissolved Cu in sand pore waters from planted systems due to metabolism of root exudates. Batch solubility studies (10 mg L −1 Cu) with the soil SPEs and defined solutions containing bicarbonate or fulvic acid confirmed elevated CuO nanoparticle solubility at >7.5 pH. Nanoparticle dissolution was suppressed in batch experiments compared to sand, via nanoparticle organic matter coating or homoconjugation of dissolved organic matter. Alterations of CuO nanoparticles by soil organic matter, plant exudates, and bacteria will affect dissolution and bioavailability of the CuO nanoparticles in alkaline soils. 

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