Size distribution and chemical composition of marine aerosols: A compilation and review

Some 30 years of physical and chemical marine aerosol data are reviewed to derive global-size distribution parameters and inorganic particle composition on a coarse 15°×15° grid. There are large gaps in geographical and seasonal coverage and chemical and physical aerosol characterisation. About 28% of the grid cells contain physical data while there are compositional data in some 60% of the cells. The size distribution data were parametrized in terms of 2 submicrometer log-normal distributions. The sparseness of the data did not allow zonal differentiation of the distributions. By segregating the chemical data according to the major aerosol sources, sea salt, dimethylsulfide, crustal material, combustion processes and other anthropogenic sources, much information on mass concentrations and contribution of natural and anthropogenic sources to the marine aerosol can be gleaned from the data base. There are significant meridional differences in the contributions of the different sources to the marine aerosol. Very clearly, we see though that the global marine surface atmosphere is polluted by anthropogenic sulfur. Only in the case of sulfur components did the coverage allow the presentation of very coarse seasonal distributions which reflect the spring blooms in the appropriate parts of the oceans. As an example of the potential value in comparing the marine aerosol data base to chemical transport models, global seasonal meridional MSA distributions were compared to modelled MSA distributions. The general good agreement in mass concentrations is encouraging while some latitudinal discrepancies warrant further investigations covering other aerosol components such as black carbon and metals

Marginal Damage of Methane Emissions: Ozone Impacts on Agriculture

Methane directly contributes to air pollution, as an ozone precursor, and to climate change, generating physical and economic damages to different systems, namely agriculture, vegetation, energy, human health, or biodiversity. The methane-related damages to climate, measured as the Social Cost of Methane, and to human health have been analyzed by different studies and considered by government rulemaking in the last decades, but the ozone-related damages to crop revenues associated to methane emissions have not been incorporated to policy agenda. Using a combination of the Global Change Analysis Model and the TM5-FASST Scenario Screening Tool, we estimate that global marginal agricultural damages range from ~ 423 to 556 $2010/t-CH4, of which 98$2010/t-CH4 occur in the USA, which is the most affected region due to its role as a major crop producer, followed by China, EU-15, and India. These damages would represent 39–59% of the climate damages and 28–64% of the human health damages associated with methane emissions by previous studies. The marginal damages to crop revenues calculated in this study complement the damages from methane to climate and human health, and provides valuable information to be considered in future cost-benefits analyses. © 2023, The Author(s).JS and SW were supported by the U.S. Environmental Protection Agency, under Interagency Agreement DW-089-92459801. The views expressed in this article are purely those of the authors and do not, under any circumstances, represent the views or policies of the U.S. Environmental Protection Agency or the European Commission. JS and SW were supported by the U.S. Environmental Protection Agency, under Interagency Agreement DW-089-92459801. The views expressed in this article are purely those of the authors and do not, under any circumstances, represent the views or policies of the U.S. Environmental Protection Agency or the European Commission

Physical aerosol properties and their relation to air mass origin at Monte Cimone (Italy) during the first MINATROC campaign

Aerosol physical properties were measured at the Monte Cimone Observatory (Italy) from 1 June till 6 July 2000. The measurement site is located in the transition zone between the continental boundary layer and the free troposphere (FT), at the border between the Mediterranean area and Central Europe, and is exposed to a variety of air masses. Sub-&mu;m number size distributions, aerosol hygroscopicity near 90% RH, refractory size distribution at 270&deg;C and equivalent black carbon mass were continuously measured. Number size distributions and hygroscopic properties indicate that the site is exposed to aged continental air masses, however during daytime it is also affected by upslope winds. The mixing of this transported polluted boundary layer air masses with relatively clean FT air leads to frequent nucleation events around local noon. <P style='line-height: 20px;'> Night-time size distributions, including fine and coarse fractions for each air mass episode, have been parameterized by a 3-modal lognormal distribution. Number and volume concentrations in the sub-&mu;m modes are strongly affected by the air mass origin, with highest levels in NW-European air masses, versus very clean, free tropospheric air coming from the N-European sector. During a brief but distinct dust episode, the coarse mode is clearly enhanced. <P style='line-height: 20px;'> The observed hygroscopic behavior of the aerosol is consistent with the chemical composition described by Putaud et al.&nbsp;(2004), but no closure between known chemical composition and measured hygroscopicity could be made because the hygroscopic properties of the water-soluble organic matter (WSOM) are not known. The data suggest that WSOM is slightly-to-moderately hygroscopic (hygroscopic growth factor GF at 90% relative humidity between 1.05 and 1.51), and that this property may well depend on the air mass origin and history. <P style='line-height: 20px;'> External mixing of aerosol particles is observed in all air masses through the occurrence of two hygroscopicity modes (average GF of 1.22 and 1.37, respectively). However, the presence of 'less' hygroscopic particles has mostly such a low occurrence rate that the average growth factor distribution for each air mass sector actually appears as a single mode. This is not the case for the dust episode, where the external mixing between less hygroscopic and more hygroscopic particles is very prominent, and indicating clearly the occurrence of a dust accumulation mode, extending down to 50 nm particles, along with an anthropogenic pollution mode. <P style='line-height: 20px;'> The presented physical measurements finally allow us to provide a partitioning of the sub-&mu;m aerosol in four non-overlapping fractions (soluble/volatile, non-soluble/volatile, refractory/non-black carbon, black carbon) which can be associated with separate groups of chemical compounds determined with chemical-analytical techniques (ions, non-water soluble organic matter, dust, elemental carbon). All air masses except the free-tropospheric N-European and Dust episodes show a similar composition within the uncertainty of the data (53%, 37%, 5% and 5% respectively for the four defined fractions). Compared to these sectors, the dust episode shows a clearly enhanced refractory-non-BC fraction (17%), attributed to dust in the accumulation mode, whereas for the very clean N-EUR sector, the total refractory fraction is 25%, of which 13% non-BC and 12% BC

LC-MS analysis of aerosol particles from the oxidation of ?-pinene by ozone and OH-radicals

International audienceThe time resolved chemical composition of aerosol particles, formed by the oxidation of alpha-pinene has been investigated by liquid chromatography/mass spectrometry (LC-MS) using negative and positive ionisation methods (ESI(-) and APCI(+)). The experiments were performed at the EUPHORE facility in Valencia (Spain) under various experimental conditions, including dark ozone reactions, photosmog experiments with low NOx mixing ratios and reaction with OH radicals in the absence of NOx (H2O2-photolysis). Particles were sampled on PTFE f ilters at different stages of the reaction and extracted with methanol. The predominant products from alpha-pinene in the particulate phase are cis-pinic acid, cis-pinonic acid and hydroxy-pinonic acid isomers. Another major compound with molecular weight 172 was detected, possibly a hydroxy-carboxylic acid. These major compounds account for 50% to 80% of the identified aerosol products, depending on the time of sampling and type of experiment. In addition, more than 20 different products have been detected and structures have been tentatively assigned based on their molecular weight and responses to the different ionisation modes. The different experiments performed showed that the aerosol formation is mainly caused by the ozonolysis reaction. The highest aerosol yields were observed in the dark ozone experiments, for which also the highest ratios of mass of identified products to the formed aerosol mass were found (30% to 50%, assuming a density of 1 g cm-3)

Can two-dimensional measured peak sagittal plane excursions during drop vertical jumps help identify three-dimensional measured joint moments?

Background: Less optimal sagittal plane movement patterns are believed to increase knee injury risk in female athletes. To facilitate clinical screening with a user-friendly method, the purpose of the present study was to examine the temporal relationships between two-dimensional measured sagittal plane kinematics and three-dimensional joint moments during the double-leg drop vertical jump (DVJ) and single-leg DVJ (SLDVJ). Methods: Fifty injury-free female athletes were tested. Maximal excursions of hip flexion, knee flexion and ankle dorsiflexion were measured through two-dimensional video analysis. Three-dimensional motion and ground reaction forces were recorded to calculate external hip flexion, knee flexion and knee abduction moments during the entire stance phase of DVJ and SLDVJ. One-dimensional statistical parametric mapping was used to examine relationships between peak two-dimensional kinematic variables and three-dimensional moment profiles. Results: Hip flexion was significantly related to the hip and knee flexion moment for both tests and knee abduction moment for DVJ during the time frames corresponding with highest three-dimensional moments, while knee flexion was significantly related to the hip flexion moment during these time frames. No significant relationships were found for ankle dorsiflexion with any of the joint moments. Conclusions: Two-dimensional measured sagittal plane hip flexion angles at the deepest landing position were associated with peak joint moments of the hip and knee during DVJ and SLDVJ, while the amount of knee flexion was only associated with the hip flexion moment. Assessment of knee injury risk with two-dimensional video analysis could benefit from measuring maximal hip flexion, more so than knee flexion

Lidar and in situ observations of continental and Saharan aerosol: closure analysis of particles optical and physical properties

Single wavelength polarization lidar observations collected at Mt. Cimone (44.2º N, 10.7º E, 1870 m a.s.l.) during the June 2000 MINATROC campaign are analyzed to derive tropospheric profiles of aerosol extinction, depolarization, surface area and volume. Lidar retrievals for the 2170-2245 m level are compared to the same variables as computed from in situ measurements of particles size distributions, performed at the mountain top Station (2165 m a.s.l.) by a differential mobility analyzer (DMA) and an optical particle counter (OPC). A sensitivity analysis of this closure experiment shows that mean relative differences between the backscatter coefficients obtained by the two techniques undergo a sharp decrease when hygroscopic growth to ambient humidity is considered for the DMA dataset, otherwise representative of dry aerosols. Minimization of differences between lidar and size distribution-derived backscatter coefficients allowed to find values of the &quot;best&quot; refractive index, specific to each measurement. These results show the refractive index to increase for air masses proceeding from Africa and Western Europe. Lidar depolarization was observed to minimize mainly in airmasses proceeding from Western Europe, thus indicating a spherical, i.e. liquid nature for such aerosols. Conversely, African, Mediterranean and East Europe aerosol showed a larger depolarizing fraction, mainly due to coexisting refractory and soluble fractions. The analysis shows average relative differences between lidar and in-situ observations of 5% for backscatter, 36% for extinction 41% for surface area and 37% for volume. These values are well within the expected combined uncertainties of the lidar and in situ retrievals. Average differences further decrease during the Saharan dust transport event, when a lidar signal inversion model considering non-spherical scatterers is employed. The quality of the closure obtained between particle counter and lidar-derived aerosol surface area and volume observations constitutes a validation of the technique adopted to retrieve such aerosol properties on the basis of single-wavelength lidar observations

Organic aerosol and global climate modelling: a review

The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies

Quantifying the reductions in mortality from air-pollution by cancelling new coal power plants

Deep decarbonization paths to the 1.5 °C or 2 °C temperature stabilization futures require a rapid reduction in coal-fired power plants, but many countries are continuing to build new ones. Coal-fired plants are also a major contributor to air pollution related health impacts. Here, we couple an integrated human-earth system model (GCAM) with an air quality model (TM5-FASST) to examine regional health co-benefits from cancelling new coal-fired plants worldwide. Our analysis considers the evolution of pollutants control based on coal plants vintage and regional policies. We find that cancelling all new proposed projects would decrease air pollution related premature mortality between 101,388–213,205 deaths (2–5%) in 2030, and 213,414–373,054 (5–8%) in 2050, globally, but heavily concentrated in developing Asia. These health co-benefits are comparable in magnitude to the values obtained by implementing the Nationally Determined Contributions (NDCs). Furthermore, we estimate that strengthening the climate target from 2 °C to 1.5 °C would avoid 326,351 additional mortalities in 2030, of which 251,011 (75%) are attributable to the incremental coal plant shutdown.The authors acknowledge funding support from Bloomberg Philanthropies. This research is also supported by Basque Government through the BERC 2018-2021 and the Spanish Government through María de Maeztu excellence accreditation MDM-2017-0714. Jon Sampedro and Ignacio Cazcarro acknowledge financial support from the Ministry of the Economy and Competitiveness of Spain (RTI2018-099858-A-100 and RTI2018-093352-B-I00). Jon Sampedro acknowledge financial support from the Basque Government (PRE_2017_2_0139). The authors thank Patrick O’Rourke and Brinda Yarlagadda for their support with data processing. The authors declare no competing interests

Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings.

PURPOSE: The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). METHODS: Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. RESULTS: The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05). Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001). The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05). Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001). Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001). CONCLUSION: This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an increased medial and posterior neuromuscular activation (dominant hamstrings medialis activity) during the preparatory and initial contact phase and an increased lateral neuromuscular activation (dominant vastus lateralis activity) during the peak loading phase