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The biogenic emissions of isoprene and monoterpenes are one of the main drivers of atmospheric photochemistry, including oxidant and secondary organic aerosol production. In this paper, the emission rates of isoprene and monoterpenes from Australian vegetation are investigated for the first time using the Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGANv2.1); the CSIRO chemical transport model; and atmospheric observations of isoprene, monoterpenes and isoprene oxidation products (methacrolein and methyl vinyl ketone). Observations from four field campaigns during three different seasons are used, covering urban, coastal suburban and inland forest areas. The observed concentrations of isoprene and monoterpenes were of a broadly similar magnitude, which may indicate that southeast Australia holds an unusual position where neither chemical species dominates. The model results overestimate the observed atmospheric concentrations of isoprene (up to a factor of 6) and underestimate the monoterpene concentrations (up to a factor of 4). This may occur because the emission rates currently used in MEGANv2.1 for Australia are drawn mainly from young eucalypt trees (< 7 years), which may emit more isoprene than adult trees. There is no single increase/decrease factor for the emissions which suits all seasons and conditions studied. There is a need for further field measurements of in situ isoprene and monoterpene emission fluxes in Australia.

Benzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions.

Dimethyl sulfide (DMS) and methanethiol (MeSH) are biologically co‐produced marine volatile sulfur compounds, which play a critical role in climate‐cooling aerosol formation. The spatio‐temporal distributions of MeSH are poorly constrained, especially over the Southern Ocean. DMS and MeSH atmospheric concentrations and relative contributions to volatile methylated sulfur (VMS) were measured across the Southern Ocean, spanning all seasons and latitudes from 37°S to 67°S. Highest absolute mixing ratios of MeSH occurred in summer (up to 250 ppt), over biologically productive waters at 45°S to 52°S and close to the Antarctic coast (>${ >} $ 62°S). Highest MeSH/VMS occurred in spring and winter (up to 35%), and at the Subtropical Front and Antarctic coast. These results constrain MeSH contributions to VMS over the Southern Ocean, explore mechanisms driving these dynamics, and support recently modeled MeSH importance to the atmospheric sulfur burden, with significant implications for modeling climate‐cooling aerosols.

Coral reefs have been found to produce the sulfur compound dimethyl sulfide (DMS), a climatically relevant aerosol precursor predominantly associated with phytoplankton. Until recently, the role of coral-reef-derived DMS within the climate system had not been quantified. A study preceding the present work found that DMS produced by corals had negligible long-term climatic forcing at the global–regional scale. However, at sub-daily timescales more typically associated with aerosol and cloud formation, the influence of coral-reef-derived DMS on local aerosol radiative effects remains unquantified. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) has been used in this work to study the role of coral-reef-derived DMS at sub-daily timescales for the first time. WRF-Chem was run to coincide with an October 2016 field campaign over the Great Barrier Reef, Queensland, Australia, against which the model was evaluated. After updating and scaling the DMS surface water climatology, the model reproduced DMS and sulfur concentrations well. The inclusion of coral-reef-derived DMS resulted in no significant change in sulfate aerosol mass or total aerosol number. Subsequently, no direct or indirect aerosol effects were detected. The results suggest that the co-location of the Great Barrier Reef with significant anthropogenic aerosol sources along the Queensland coast prevents coral-reef-derived aerosol from having a modulating influence on local aerosol burdens in the current climate.

Understanding uncertainty is essential for utilizing atmospheric volatile organic compound (VOC) measurements in robust ways to develop atmospheric science. This study describes an inter-comparison of the VOC data, and the derived uncertainty estimates, measured with three independent techniques (PTR-MS, proton-transfer-reaction mass spectrometry; GC-FID-MS, gas chromatography with flame-ionization and mass spectrometric detection; and DNPH–HPLC, 2,4-dinitrophenylhydrazine derivatization followed by analysis by high-performance liquid chromatography) during routine monitoring as part of the Sydney Particle Study (SPS) campaign in 2012. Benzene, toluene, C8 aromatics, isoprene, formaldehyde and acetaldehyde were selected for the comparison, based on objective selection criteria from the available data. Bottom-up uncertainty analyses were undertaken for each compound and each measurement system. Top-down uncertainties were quantified via the inter-comparisons. In all seven comparisons, the correlations between independent measurement techniques were high with R2 values with a median of 0.92 (range 0.75–0.98) and small root mean square of the deviations (RMSD) of the observations from the regression line with a median of 0.11 (range 0.04–0.23 ppbv). These results give a high degree of confidence that for each comparison the response of the two independent techniques is dominated by the same constituents. The slope and intercept as determined by reduced major axis (RMA) regression gives a different story. The slopes varied considerably with a median of 1.25 and a range of 1.16–2.01. The intercepts varied with a median of 0.04 and a range of −0.03 to 0.31 ppbv. An ideal comparison would give a slope of 1.00 and an intercept of 0. Some sources of uncertainty that are poorly quantified by the bottom-up uncertainty analysis method were identified, including: contributions of non-target compounds to the measurement of the target compound for benzene, toluene and isoprene by PTR-MS as well as the under-reporting of formaldehyde, acetaldehyde and acetone by the DNPH technique. As well as these, this study has identified a specific interference of liquid water with acetone measurements by the DNPH technique. These relationships reported for Sydney 2012 were incorporated into a larger analysis with 61 similar published inter-comparison studies for the same compounds. Overall, for the light aromatics, isoprene and the C1–C3 carbonyls, the uncertainty in a set of measurements varies by a factor of between 1.5 and 2. These uncertainties (∼50 %) are significantly higher than uncertainties estimated using standard propagation of error methods, which in this case were ∼22 % or less, and are the result of the presence of poorly understood or neglected processes that affect the measurement and its uncertainty. The uncertainties in VOC measurements identified here should be considered when assessing the reliability of VOC measurements from routine monitoring with individual, stand-alone instruments; when utilizing VOC data to constrain and inform air quality and climate models; when using VOC observations for human exposure studies; and for comparison with satellite retrievals.

The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical and physical properties, fluxes to the atmosphere, and ultimately their impact on cloud formation under minimal direct anthropogenic influence. Here we present an interdisciplinary approach, combining atmospheric physics and chemistry with marine biogeochemistry, during a voyage between 41° and 47°S in March 2020. In parallel to ambient measurements of atmospheric composition and seawater biogeochemical properties, we describe semicontrolled experiments to characterize nascent sea spray properties and nucleation from gas-phase biogenic emissions. The experimental framework for studying the impact of the predicted evolution of ozone concentration in the Southern Hemisphere is also detailed. After describing the experimental strategy, we present the oceanic and meteorological context including provisional results on atmospheric thermodynamics, composition, and flux measurements. In situ measurements and flux studies were carried out on different biological communities by sampling surface seawater from subantarctic, subtropical, and frontal water masses. Air–Sea-Interface Tanks (ASIT) were used to quantify biogenic emissions of trace gases under realistic environmental conditions, with nucleation observed in association with biogenic seawater emissions. Sea spray continuously generated produced sea spray fluxes of 34% of organic matter by mass, of which 4% particles had fluorescent properties, and which size distribution resembled the one found in clean sectors of the Southern Ocean. The goal of Sea2Cloud is to generate realistic parameterizations of emission flux dependences of trace gases and nucleation precursors, sea spray, cloud condensation nuclei, and ice nuclei using seawater biogeochemistry, for implementation in regional atmospheric models.

Polar oceans and sea-ice regions are global hot spots for the production of biogenic volatile methylated sulfur (VMS) compounds: dimethyl sulfide (DMS) and methanethiol (MeSH). VMS compounds make important contributions to atmospheric particle formation and cloud property modulation, especially when polar atmospheres are pristine. As a result, the polar biogenic sulfur cycle may induce significant climate feedback in response to ongoing sea ice decline. However, polar VMS production, emission, and atmospheric oxidation processes remain poorly represented in current numerical models, hampering assessments of their radiative impacts and, in turn, implementation of targeted observations necessary for providing predictive understanding of changes in the ocean–sea ice–atmosphere (OIA) system. We synthesize current knowledge of the polar biogenic sulfur cycle and its representation in models. To untangle the existing gaps and provide a roadmap toward predictive understanding, we identify key features of sea ice habitats for biological VMS production, sea ice physical features that enhance or suppress VMS emissions, and atmospheric VMS oxidation at low temperatures that controls the contribution of oxidation products to particle formation or growth. These features are tightly coupled, emphasizing the need for coordinated efforts across disciplines that span the OIA interface, and among observational, experimental, and modeling communities. We recommend 4 priority research areas: (1) model representation of biological VMS production at the sea ice bottom and surface; (2) improved quantification of cloud condensation nuclei (CCN) sensitivity to VMS emissions with updated gas phase and multiphase oxidation chemistry at low temperatures; (3) better spatial and seasonal quantification of MeSH abundance and its biological and chemical controls in sea-ice environments; and (4) assessment of the contribution of episodic extreme VMS emissions during sea ice breakup for the polar CCN budget.

The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February–March 2011 and April–May 2012. The aim of this study was to increase scientific understanding of particle formation and transformations in the Sydney airshed. In this paper we describe the methods used to collect and analyse particle and gaseous samples, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties, and gaseous concentrations. This paper also provides a description of the data collected and is a metadata record for the data sets published in Keywood et al. (2016a, https://doi.org/10.4225/08/57903B83D6A5D) and Keywood et al. (2016b, https://doi.org/10.4225/08/5791B5528BD63).

This article addresses the role played by adaptive self-regulation in protecting older adults' psychological and physical health. A theoretical model is outlined illustrating how common age-related challenges (i.e., physical challenges and life regrets) can influence older adults' health. In addition, the proposed model suggests that older adults can avoid the adverse health effects of encountering these problems if they engage in adaptive self-regulation. Finally, this article reviews recent studies that examined the adaptive value of self-regulation processes for managing physical challenges and life regrets in the elderly. The findings from cross-sectional, longitudinal, and experimental studies document the importance of adaptive self-regulation for maintaining older adults' health.

Derek Draplin, a reporter with the Mackinac Center’s Michigan Capitol Confidential news service, thought his Freedom of Information Act request for emails sent by University of Michigan President Mark Schlissel referencing Donald Trump would be simple. When the documents had still not been received as of March 1, the Mackinac Center decided that the request had taken an unreasonable amount of time under FOIA rules and filed a lawsuit seeking the records, costs, and full...