More Like this

1. Nitrate radical oxidation of <i>γ</i>-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields

   https://doi.org/10.5194/acp-17-8635-2017  

   Slade, Jonathan H. ; de Perre, Chloé ; Lee, Linda ; Shepson, Paul B. ( January 2017 , Atmospheric Chemistry and Physics)

   Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO₃), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO₃. Under dry conditions, the hydroxy nitrate yield  =  4(+1/−3) %, total ON yield  =  14(+3/−2) %, and SOA yield  ≤  10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO₃. Using a chemical box model, we show that the measured concentrations of NO₂ and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO₃ chemistry. This suggests that NO₃ addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applyingmore »high-resolution liquid chromatography–mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.« less
2. Nitrate Reductase Knockout Uncouples Nitrate Transport from Nitrate Assimilation and Drives Repartitioning of Carbon Flux in a Model Pennate Diatom

   https://doi.org/10.1105/tpc.16.00910  

   McCarthy, James K. ; Smith, Sarah R. ; McCrow, John P. ; Tan, Maxine ; Zheng, Hong ; Beeri, Karen ; Roth, Robyn ; Lichtle, Christian ; Goodenough, Ursula ; Bowler, Chris P. ; et al ( August 2017 , The Plant Cell)
3. Updated methods for global locally interpolated estimation of alkalinity, pH, and nitrate: LIR: Global alkalinity, pH, and nitrate estimates

   https://doi.org/10.1002/lom3.10232  

   Carter, B. R. ; Feely, R. A. ; Williams, N. L. ; Dickson, A. G. ; Fong, M. B. ; Takeshita, Y. ( February 2018 , Limnology and Oceanography: Methods)
4. Global inorganic nitrate production mechanisms: comparison of a global model with nitrate isotope observations

   https://doi.org/10.5194/acp-20-3859-2020  

   Alexander, Becky ; Sherwen, Tomás ; Holmes, Christopher D. ; Fisher, Jenny A. ; Chen, Qianjie ; Evans, Mat J. ; Kasibhatla, Prasad ( January 2020 , Atmospheric Chemistry and Physics)

   Abstract. The formation of inorganic nitrate is the main sink for nitrogenoxides (NOx = NO + NO2). Due to the importance of NOx forthe formation of tropospheric oxidants such as the hydroxyl radical (OH) andozone, understanding the mechanisms and rates of nitrate formation isparamount for our ability to predict the atmospheric lifetimes of mostreduced trace gases in the atmosphere. The oxygen isotopic composition ofnitrate (Δ17O(nitrate)) is determined by the relativeimportance of NOx sinks and thus can provide an observationalconstraint for NOx chemistry. Until recently, the ability to utilizeΔ17O(nitrate) observations for this purpose was hindered by ourlack of knowledge about the oxygen isotopic composition of ozone (Δ17O(O3)). Recent and spatially widespread observations of Δ17O(O3) motivate an updated comparison of modeled andobserved Δ17O(nitrate) and a reassessment of modeled nitrateformation pathways. Model updates based on recent laboratory studies ofheterogeneous reactions render dinitrogen pentoxide (N2O5)hydrolysis as important as NO2 + OH (both 41 %) for globalinorganic nitrate production near the surface (below 1 km altitude). Allother nitrate production mechanisms individually represent less than 6 %of global nitrate production near the surface but can be dominant locally.Updated reaction rates for aerosol uptake of NO2 result in significantreduction of nitrate and nitrous acid (HONO) formed through this pathway inthe model and render NO2 hydrolysis amore »negligible pathway for nitrateformation globally. Although photolysis of aerosol nitrate may haveimplications for NOx, HONO, and oxidant abundances, it does notsignificantly impact the relative importance of nitrate formation pathways.Modeled Δ17O(nitrate) (28.6±4.5 ‰)compares well with the average of a global compilation of observations (27.6±5.0 ‰) when assuming Δ17O(O3) = 26 ‰, giving confidence in the model'srepresentation of the relative importance of ozone versus HOx (= OH + HO2 + RO2) in NOx cycling and nitrate formation on theglobal scale.« less
5. Aquatic Nitrate Retention at River Network Scales Across Flow Conditions Determined Using Nested In Situ Sensors: NETWORK SCALE NITRATE RETENTION

   https://doi.org/10.1002/2017WR020644  

   Wollheim, W. M. ; Mulukutla, G. K. ; Cook, C. ; Carey, R. O. ( November 2017 , Water Resources Research)