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The Belle II software was developed by a few hundred individual contributors over several years. Following the rising desire of making it publicly available, the collaboration established open source software policies and procedures. The political and technical challenges and their solutions at Belle II are discussed in this article. With the publication of the Belle II software, basf2, on GitHub and Zenodo in 2021 an important milestone towards open science was reached.

Anthropogenic activities emit ~2,000 Mg y -1 of the toxic pollutant mercury (Hg) into the atmosphere, leading to long-range transport and deposition to remote ecosystems. Global anthropogenic emission inventories report increases in Northern Hemispheric (NH) Hg emissions during the last three decades, in contradiction with the observed decline in atmospheric Hg concentrations at NH measurement stations. Many factors can obscure the link between anthropogenic emissions and atmospheric Hg concentrations, including trends in the reemissions of previously released anthropogenic ("legacy") Hg, atmospheric sink variability, and spatial heterogeneity of monitoring data. Here, we assess the observed trends in gaseous elemental mercury (Hg 0 ) in the NH and apply biogeochemical box modeling and chemical transport modeling to understand the trend drivers. Using linear mixed effects modeling of observational data from 51 stations, we find negative Hg 0 trends in most NH regions, with an overall trend for 2005 to 2020 of -0.011 ± 0.006 ng m -3 y -1 (±2 SD). In contrast to existing emission inventories, our modeling analysis suggests that annual NH anthropogenic emissions must have declined by at least 140 Mg between the years 2005 and 2020 to be consistent with observed trends. Faster declines in 95th percentile Hg 0 values than median values in Europe, North America, and East Asian measurement stations corroborate that the likely cause is a decline in nearby anthropogenic emissions rather than background legacy reemissions. Our results are relevant for evaluating the effectiveness of the Minamata Convention on Mercury, demonstrating that existing emission inventories are incompatible with the observed Hg 0 declines., Competing Interests: Competing interests statement:The authors declare no competing interest.

We examined PM 2.5 and Hazard Mapping System smoke plume satellite data at ∼600 United States (US) air monitoring stations to identify surface smoke on 14.0% of all May-September days for 2018-2023, with large influences in 2020 and 2021, due to California fires, and 2023, due to Canadian fires. Days with smoke have an average of 11 μg m -3 more PM 2.5 and 8 ppb higher maximum daily 8 h average (MDA8) O 3 concentrations than nonsmoke days, and they also account for 94% of all days that exceed the daily PM 2.5 health standard (35 μg m -3 ) and 36% of all days that exceed the O 3 health standard (70 ppb). To estimate the smoke contributions to the O 3 MDA8, Generalized Additive Models (GAMs) were built for each site using the nonsmoke day data and up to 8 predictors. The mean and standard deviation of the residuals from the GAMs were 0 ± 6.1 ppb for the nonsmoke day data and 4.3 ± 7.9 ppb for the smoke day data, indicating a significant enhancement in the MDA8 O 3 on smoke days. We found positive residuals on 72% of the smoke days and for these days, we calculate an average smoke contribution to the O 3 MDA8 of 7.8 ± 6.0 ppb. Over the 6 year period, the percentage of exceedance days due to smoke in the continental US was 25% of all exceedance days, and the highest was in 2023 (38%). In 2023, the Central US experienced an unusually high number of exceedance days, 1522, with 52% of these impacted by smoke, while the Eastern US had fewer exceedance days, 288, with 78% of these impacted by smoke. Our results demonstrate the importance of wildland fires as contributors to exceedances of the health-based national air quality standards for PM 2.5 and O 3 .

High spinal cord injury (SCI) leads to persistent and debilitating compromise in respiratory function. Cervical SCI not only causes the death of phrenic motor neurons (PhMNs) that innervate the diaphragm, but also damages descending respiratory pathways originating in the rostral ventral respiratory group (rVRG) located in the brainstem, resulting in denervation and consequent silencing of spared PhMNs located caudal to injury. It is imperative to determine whether interventions targeting rVRG axon growth and respiratory neural circuit reconnection are efficacious in chronic cervical contusion SCI, given that the vast majority of individuals are chronically-injured and most cases of SCI involve contusion-type damage to the cervical region. We therefore employed a rat model of chronic cervical hemicontusion to test therapeutic manipulations aimed at reconstructing damaged rVRG-PhMN-diaphragm circuitry to achieve recovery of respiratory function. At a chronic time point post-injury, we systemically administered: an antagonist peptide directed against phosphatase and tensin homolog (PTEN), a central inhibitor of neuron-intrinsic axon growth potential; an antagonist peptide directed against receptor-type protein tyrosine phosphatase sigma (PTPσ), another important negative regulator of axon growth capacity; or a combination of these two peptides. PTEN antagonist peptide (PAP4) promoted partial recovery of diaphragm motor activity out to nine months post-injury (though this effect depended on the anesthetic regimen used during recording), while PTPσ peptide did not impact diaphragm function after cervical SCI. Furthermore, PAP4 promoted robust growth of descending bulbospinal rVRG axons caudal to the injury within the denervated portion of the PhMN pool, while PTPσ peptide did not affect rVRG axon growth at this location that is critical to control of diaphragmatic respiratory function. In conclusion, we find that, when PTEN inhibition is targeted at a chronic time point following cervical contusion, our non-invasive PAP4 strategy can successfully promote significant regrowth of damaged respiratory neural circuitry and also partial recovery of diaphragm motor function., Competing Interests: Declaration of competing interest The authors report no declarations of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Peroxyacetyl nitrate (PAN) is produced in the atmosphere by photochemical oxidation of non-methane volatile organic compounds in the presence of nitrogen oxides (NO x ), and it can be transported over long distances at cold temperatures before decomposing thermally to release NO x in the remote troposphere. It is both a tracer and a precursor for transpacific ozone pollution transported from East Asia to North America. Here, we directly demonstrate this transport with PAN satellite observations from the infrared atmospheric sounding interferometer (IASI). We reprocess the IASI PAN retrievals by replacing the constant prior vertical profile with vertical shape factors from the GEOS-Chem model that capture the contrasting shapes observed from aircraft over South Korea (KORUS-AQ) and the North Pacific (ATom). The reprocessed IASI PAN observations show maximum transpacific transport of East Asian pollution in spring, with events over the Northeast Pacific offshore from the Western US associated in GEOS-Chem with elevated ozone in the lower free troposphere. However, these events increase surface ozone in the US by less than 1 ppbv because the East Asian pollution mainly remains offshore as it circulates the Pacific High.

The Northern Wasatch Front area is one of ~ 50 metropolitan regions in the U.S. that do not meet the 2015 O 3 standard. To better understand the causes of high O 3 days in this region we conducted the Salt Lake regional Smoke, Ozone and Aerosol Study (SAMOZA) in the summer of 2022. The primary goals of SAMOZA were: Measure a suite of VOCs, by Proton Transfer Reaction Mass Spectrometry (PTR-MS) and the 2,4-dinitrophenylhydrazine (DNPH) cartridge method.Evaluate whether the standard UV O 3 measurements made in SLC show a positive bias during smoke events, as has been suggested in some recent studies.Use the observations to conduct photochemical modeling and statistical/machine learning analyses to understand photochemistry on both smoke-influenced and non-smoke days. Implications: The Northern Wasatch Front area is one of ~50 metropolitan regions in the U.S. that do not meet the 2015 O 3 standard. To better understand the causes of high O 3 days in this region we conducted the Salt Lake regional Smoke, Ozone and Aerosol Study (SAMOZA) in the summer of 2022. A number of policy relevant findings are identified in the manuscript including role of smoke and NOx vs VOC sensitivity.

We investigated the impact of wildfires on maximum daily 8-hr average ozone concentrations (MDA8 O 3 ) at four sites in Salt Lake City (SLC), Utah for May to September for 2006-2022. Smoke days, which were identified by a combination of overhead satellite smoke detection and surface PM 2.5 data and accounted for approximately 9% of the total number of days, exhibited O 3 levels 6.8 to 8.9 ppb higher than no-smoke days and were predominantly characterized by high daily maximum temperatures and low relative humidity. A Generalized Additive Model (GAM) was developed to quantify the impact of wildfire contributions to O 3 . The GAM, which provides smooth functions that make the interpretation of relationships more intuitive, employed 17 predictors and demonstrated reliable performance in various evaluation metrics. The mean of the residuals for all sites was approximately zero for the training and cross-validation data and 5.1 ppb for smoke days. We developed three approaches to estimate the contribution of smoke to O 3 from the model residuals. These generate a minimum and maximum contribution for each smoke day. The average of the minimum and maximum wildfire contributions to O 3 for the SLC sites was 5.1 and 8.5 ppb, respectively. Between 2006 and 2022, an increasing trend in the wildfire contributions to O 3 was observed in SLC. Moreover, trends of the fourth-highest MDA8 O 3 before and after removing the wildfire contributions to O 3 at the SLC Hawthorne site in 2006-2022 were quite different. Whereas the unadjusted data do not meet the current O 3 standard, after removing the contributions from wildfires the SLC region is close to achieving levels that are consistent with meeting the O 3 standard. We also found that the wildfire contribution during smoke days was particularly high under conditions of high temperature, high PM 2.5 concentration, and low cloud fraction. Implications : In this study, we quantified the impact of wildfires on maximum daily 8-hr average ozone concentrations (MDA8 O 3 ) in Salt Lake City, Utah, using a Generalized Additive Model (GAM). The GAM results demonstrate the importance of wildfires as contributors to O 3 air pollution. Our results suggest that states could use the GAM approach to assist in quantifying the wildfire contribution to MDA8 O 3 under the U.S. EPA exceptional events rule. These findings also highlight the need for strategies to manage wildfires and their subsequent impacts on air quality in an era of climate warming.

The inclusion of omega-3 fatty acids in our dietary intake is important for performance and recovery and may reduce the risk of various health issues. Studies have shown the omega-3 fatty acid status of US service members is low. The purpose of this study was to evaluate whether offering fish and omega-3-enhanced foods would increase the Omega-3 Index (O3I). We hypothesize cadets will increase O3I with enhanced omega-3 options more than fish alone. Food service venues at 3 US service academies offered fish and other omega-3 foods to cadets for 12 weeks. Questionnaires were used to collect information on the dietary habits and omega-3 food intake of participants. The O3I of each participant was measured at baseline, mid- (6 weeks), and after data collection (12 weeks) time points. Following the 12 weeks, we found a significant increase in O3I. More specifically, the intake of other omega-3 foods, smoothies (3 per week) and toppings (3 per week), increased O3I in cadets. This study identified a strategy encouraging omega-3 food intake and improving O3I among cadets. These results help us understand how we can more effectively impact military service member nutrition for optimal health and performance., (Published by Elsevier Inc.)

Rodents and bats are the most diverse mammal group that host Bartonella species. In the Americas, they were described as harboring Bartonella species; however, they were mostly characterized to the genotypic level. We describe here Bartonella isolates obtained from blood samples of one rodent ( Peromyscus yucatanicus from San José Pibtuch, Yucatan) and two bat species ( Desmodus rotundus from Progreso, and Pteronotus parnellii from Chamela-Cuitzmala) from Mexico. We sequenced and described the genomic features of three Bartonella strains and performed phylogenomic and pangenome analyses to decipher their phylogenetic relationships. The mouse-associated genome was closely related to Bartonella vinsonii . The two bat-associated genomes clustered into a single distinct clade in between lineages 3 and 4, suggesting to be an ancestor of the rodent-associated Bartonella clade (lineage 4). These three genomes showed <95% OrthoANI values compared to any other Bartonella genome, and therefore should be considered as novel species. In addition, our analyses suggest that the B. vinsonii complex should be revised, and all B. vinsonii subspecies need to be renamed and considered as full species. The phylogenomic clustering of the bat-associated Bartonella strains and their virulence factor profile (lack of the Vbh/TraG conjugation system remains of the T4SS) suggest that it should be considered as a new lineage clade (L5) within the Bartonella genus.

We analyzed NO 2 and O 3 data from 32 U.S. non-attainment areas (NAAs) for 1995-2020. Since 1995, all regions have shown steady reductions in NO 2 and the weekend-weekday pattern indicates that the O 3 production regime in most NAAs has transitioned to a NO x -limited regime, while a few NAAs remain NO x -saturated. In the eastern U.S., all NAAs have made steady progress toward meeting the current (70 ppb) O 3 standard, but this is less true in midwestern and western NAAs, with most showing little improvement in peak O 3 concentrations since about 2010. Due to COVID-19 restrictions, NO 2 concentrations were substantially reduced in 2020. In the eastern NAAs, we see significant reductions in both NO 2 and peak O 3 concentrations. In the midwestern U.S., results were more variable, with both higher and lower O 3 values in 2020. In the western U.S. (WUS), we see variable reductions in NO 2 but substantial increases in O 3 at most sites, due to the influence from huge wildland fires. The recent pattern over the past decade shows that the large amount of wildland fires has a strong influence on the policy-relevant O 3 metric in the WUS, and this is making it more difficult for these regions to meet the O 3 standard., (© 2022. American Geophysical Union. All Rights Reserved.)

Wildfire-influenced air masses under regional background conditions were characterized at the Mt. Bachelor Observatory (∼2800 m a.s.l.) in summer 2019 to provide a better understanding of the aging of biomass burning organic aerosols (BBOAs) and their impacts on the remote troposphere in the western United States. Submicron aerosol (PM 1 ) concentrations were low (average ± 1σ = 2.2 ± 1.9 μg sm -3 ), but oxidized BBOAs (average O/C = 0.84) were constantly detected throughout the study. The BBOA correlated well with black carbon, furfural, and acetonitrile and comprised above 50% of PM 1 during plume events when the peak PM 1 concentration reached 18.0 μg sm -3 . Wildfire plumes with estimated transport times varying from ∼10 h to >10 days were identified. The plumes showed ΔOA/ΔCO values ranging from 0.038 to 0.122 ppb ppb -1 with a significant negative relation to plume age, indicating BBOA loss relative to CO during long-range transport. Additionally, increases of average O/C and aerosol sizes were seen in more aged plumes. The mass-based size mode was approximately 700 nm ( D va ) in the most oxidized plume that likely originated in Siberia, suggesting aqueous-phase processing during transport. This work highlights the widespread impacts that wildfire emissions have on aerosol concentration and properties, and thus climate, in the western United States.

There is growing appreciation for astrocyte heterogeneity both across and within central nervous system (CNS) regions, as well as between intact and diseased states. Recent work identified multiple astrocyte subpopulations in mature brain. Interestingly, one subpopulation (Population C) was shown to possess significantly enhanced synaptogenic properties in vitro, as compared with other astrocyte subpopulations of adult cortex and spinal cord. Following spinal cord injury (SCI), damaged neurons lose synaptic connections with neuronal partners, resulting in persistent functional loss. We determined whether SCI induces an enhanced synaptomodulatory astrocyte phenotype by shifting toward a greater proportion of Population C cells and/or increasing expression of relevant synapse formation-associated genes within one or more astrocyte subpopulations. Using flow cytometry and RNAscope in situ hybridization, we found that astrocyte subpopulation distribution in the spinal cord did not change to a selectively synaptogenic phenotype following mouse cervical hemisection-type SCI. We also found that spinal cord astrocytes expressed synapse formation-associated genes to a similar degree across subpopulations, as well as in an unchanged manner between uninjured and SCI conditions. Finally, we confirmed these astrocyte subpopulations are also present in the human spinal cord in a similar distribution as mouse, suggesting possible conservation of spinal cord astrocyte heterogeneity across species.

Serotonin plays a central role in cognition and is the target of most pharmaceuticals for psychiatric disorders. Existing drugs have limited efficacy; creation of improved versions will require better understanding of serotonergic circuitry, which has been hampered by our inability to monitor serotonin release and transport with high spatial and temporal resolution. We developed and applied a binding-pocket redesign strategy, guided by machine learning, to create a high-performance, soluble, fluorescent serotonin sensor (iSeroSnFR), enabling optical detection of millisecond-scale serotonin transients. We demonstrate that iSeroSnFR can be used to detect serotonin release in freely behaving mice during fear conditioning, social interaction, and sleep/wake transitions. We also developed a robust assay of serotonin transporter function and modulation by drugs. We expect that both machine-learning-guided binding-pocket redesign and iSeroSnFR will have broad utility for the development of other sensors and in vitro and in vivo serotonin detection, respectively., Competing Interests: Declaration of Interests L.T. and G.O.M. are co-founders of Seven Biosciences. D.E.O. is a founder of Delix., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A major portion of individuals affected by traumatic spinal cord injury (SCI) experience one or more types of chronic neuropathic pain (NP), which is often intractable to currently available treatments. The availability of reliable behavioral assays in pre-clinical models of SCI-induced NP is therefore critical to assess the efficacy of new potential therapies. Commonly used assays to evaluate NP-related behavior in rodents, such as Hargreaves thermal and von Frey mechanical testing, rely on the withdrawal response to an evoked stimulus. However, other assays that test spontaneous/non-evoked NP-related behavior or supraspinal aspects of NP would be highly useful for a more comprehensive assessment of NP following SCI. The Mouse Grimace Scale (MGS) is a tool to assess spontaneous, supraspinal pain-like behaviors in mice; however, the assay has not been characterized in a mouse model of SCI-induced chronic NP, despite the critical importance of mouse genetics as an experimental tool. We found that beginning 2 weeks after cervical contusion, SCI mice exhibited increased facial grimace features compared to laminectomy-only control mice, and this grimace phenotype persisted to the chronic time point of 5 weeks post-injury. We also found a significant relationship between facial grimace score and the evoked forepaw withdrawal response in both the Hargreaves and von Frey tests at 5 weeks post-injury when both laminectomy-only and SCI mice were included in the analysis. However, within only the SCI group, there was no correlation between grimace score and Hargreaves or von Frey responses. These results indicate both that facial grimace analysis can be used as an assay of spontaneous NP-related behavior in the mouse model of SCI and that the information provided by the MGS may be different than that provided by evoked tests of sensory function., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Bartonella sp. infection is quite common in free-roaming dogs in many tropical countries. However, limited information is available of the presence of these pathogens in Mexico. The present study looked at prevalence of Bartonella exposure and/or infection in dogs and their fleas in Central Mexico. Blood samples were collected from 31 stray dogs in August 2014 at the municipal pound, Tulancingo, Mexico, as well as fleas on 26 of them. Bartonella seropositivity was 46.9%, including 35.5% for Bartonella henselae, 45% for Bartonella clarridgeiae and 32.2% for Bartonella vinsonii subsp. berkhoffii. Three (9.7%) dogs were polymerase chain reaction (PCR) positive for the Bartonella gltA gene. Partial sequencing of that gene revealed that these three dogs were infected with B. henselae. In total, 86 fleas were collected from 26 dogs (range 1-9 fleas per dog), including 52 Ctenocephalides felis and 34 Ctenocephalides canis. Of 40 pools of fleas (20 pools of C. canis and 20 pools of C. felis), five (12.5%) were PCR positive for the Bartonella sp. gltA gene, including three C. canis pools (five fleas) and two C. felis pools (three fleas). All sequences showed 99.25% to 100% homology with B. henselae Houston I., (© 2020 The Royal Entomological Society.)

The atmosphere is a significant global reservoir for mercury (Hg) and its isotopic characterization is important to understand sources, distribution, and deposition of Hg to the Earth's surface. To better understand Hg isotope variability in the remote background atmosphere, we collected continuous 12-h Hg 0 samples for 1 week from two high elevation sites, Camp Davis, Wyoming (valley), and Mount Bachelor, Oregon (mountaintop). The samples collected at Camp Davis displayed strong diel variation in δ 202 Hg values of Hg 0 , but not in Δ 199 Hg or Δ 200 Hg values. We attribute this pattern to nightly atmospheric inversions trapping Hg in the valley and the subsequent nighttime uptake of Hg by vegetation, which depletes Hg from the atmosphere. At Mount Bachelor, the samples displayed diel variation in both δ 202 Hg and Δ 199 Hg, but not Δ 200 Hg. We attribute this pattern to differences in the vertical distribution of Hg in the atmosphere as Mount Bachelor received free tropospheric air masses on certain nights during the sampling period. Near the end of the sampling period at Mount Bachelor, the observed diel pattern dissipated due to the influence of a nearby forest fire. The processes governing the Hg isotopic fractionation differ across sites depending on mixing, topography, and vegetation cover.

Air quality impacts from wildfires have been dramatic in recent years, with millions of people exposed to elevated and sometimes hazardous fine particulate matter (PM 2.5 ) concentrations for extended periods. Fires emit particulate matter (PM) and gaseous compounds that can negatively impact human health and reduce visibility. While the overall trend in U.S. air quality has been improving for decades, largely due to implementation of the Clean Air Act, seasonal wildfires threaten to undo this in some regions of the United States. Our understanding of the health effects of smoke is growing with regard to respiratory and cardiovascular consequences and mortality. The costs of these health outcomes can exceed the billions already spent on wildfire suppression. In this critical review, we examine each of the processes that influence wildland fires and the effects of fires, including the natural role of wildland fire, forest management, ignitions, emissions, transport, chemistry, and human health impacts. We highlight key data gaps and examine the complexity and scope and scale of fire occurrence, estimated emissions, and resulting effects on regional air quality across the United States. The goal is to clarify which areas are well understood and which need more study. We conclude with a set of recommendations for future research., Implications: In the recent decade the area of wildfires in the United States has increased dramatically and the resulting smoke has exposed millions of people to unhealthy air quality. In this critical review we examine the key factors and impacts from fires including natural role of wildland fire, forest management, ignitions, emissions, transport, chemistry and human health.

Dogs can be infected by a wide range of Bartonella spp., but studies regarding the prevalence of Bartonella infection in dogs in the Philippines have not been conducted. This study aimed at determining the prevalence of Bartonella infection in pets dogs from two veterinary clinics in Metro Manila, The Philippines, using both serology and polymerase chain reaction (PCR). Blood samples from 116 dogs from two different groups, one of 60 mainly "healthy dogs" and the other one of 56 dogs enrolled in a tick-borne disease suspect group, were tested for presence of B. henselae antibodies and to detect Bartonella DNA using primers specific for the citrate synthase gene. Seroprevalence for B. henselae was very low (2.6%), as the only three (5%) seropositive dogs (titer 1:64) where among the healthy pet dog group. Following subsequent sequencing, 13 samples, all from the tick-borne disease group, were determined positive for B. henselae (11.2%). This is the first study to report dog infection with B. henselae in the Philippines., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Bartonellae are emerging zoonotic vector-borne pathogens causing a broad spectrum of clinical symptoms in humans and animals, including life-threatening endocarditis. Dogs are infected with a wide range of Bartonella species and infection has been reported in free-roaming dogs from various South American countries. We report a high Bartonella seroprevalence in 82 Chilean stray dogs. More than half of the dogs from Linares (72.7%, n  = 66) and Puerto Montt (56.2%, n  = 16) were seropositive for Bartonella henselae , Bartonella vinsonii ssp. berkhoffii , or Bartonella clarridgeiae with antibody titers ranging from 1:64 to 1:512. Three dogs (3.6%) were PCR positive for Bartonella sp. Partial sequencing of the glt A gene indicated that two dogs were infected with B. henselae , and one with a strain close to Bartonella vinsonii ssp. vinsonii . Exposure to Bartonella species was common in stray Chilean dogs, as for other South American countries, likely associated with heavy ectoparasite infestation.

Objectives: Bartonella infection has been associated with endocarditis in humans, dogs, cats and cattle. In order to evaluate the importance of this pathogen as a possible source of endocarditis in United States military working dogs (MWDs), we performed a retrospective case-control study on 26 dogs with histological diagnosis of culture negative endocarditis (n = 18), endomyocarditis (n = 5) or endocardiosis (n = 3) and 28 control dogs without any histological cardiac lesions., Methods: DNA was extracted from paraffin embedded cardiac valves and tissues from case and control dogs and submitted to PCR testing with primers targeting the Bartonella gltA gene. PCR-RFLP using four restriction endonucleases and partial sequencing was then performed to determine the Bartonella species involved., Results: Nineteen (73%) cases were PCR positive for Bartonella, including B. henselae (8 dogs), B. vinsonii subsp. berkhoffii (6 dogs), B. washoensis (2 dogs) and B. elizabethae (1 dog). Only one control dog was weakly PCR positive for Bartonella. Based on the type of histological diagnosis, 13 (72.2%) dogs with endocarditis, 3 (60%) dogs with endomyocarditis and all 3 dogs with endocardiosis were Bartonella PCR positive., Conclusions: Bartonella sp. Infections were correlated with cardiopathies in US military working dogs. Systemic use of insecticides against ectoparasites and regular testing of MWDs for Bartonella infection seem highly appropriate to prevent such life-threatening exposures., Competing Interests: Conflict of Interest Statement The authors do not have any conflicts of interest to disclose., (Crown Copyright © 2019. Published by Elsevier B.V. All rights reserved.)

Urban ozone (O 3 ) pollution is influenced by the transport of wildfire smoke but observed impacts are highly variable. We investigate O 3 impacts from smoke in 18 western US cities during July-September, 2013-2017, with ground-based monitoring data from air quality system sites, using satellite-based hazard mapping system (HMS) fire and smoke product to identify overhead smoke. We present four key findings. First, O 3 and PM 2.5 (particulate matter <2.5 μm in diameter) are elevated at nearly all sites on days influenced by smoke, with the greatest mean enhancement occurring during multiday smoke events; nitrogen oxides (NO x ) are not consistently elevated across all sites. Second, PM 2.5 and O 3 exhibit a nonlinear relationship such that O 3 increases with PM 2.5 at low to moderate 24 h PM 2.5 , peaks around 30-50 μg m -3 , and declines at higher PM 2.5 . Third, the rate of increase of morning O 3 is higher and NO/NO 2 ratios are lower on smoke-influenced days, which could result from additional atmospheric oxidants in smoke. Fourth, while the HMS product is a useful tool for identifying smoke, O 3 and PM 2.5 are elevated on days before and after HMS-identified smoke events implying that a significant fraction of smoke events is not detected.

Bartonella spp. have been identified in many bat species worldwide, including the zoonotic species, Candidatus Bartonella mayotimonensis. The common vampire bat (Desmodus rotundus) preys preferentially on livestock in Latin America and is frequently infected with Bartonella spp. To determine the potential role of D. rotundus in transmitting Bartonella to livestock, common vampire bats and bat-bitten domestic ruminants from Mexico were tested for Bartonella infection by blood culture or conventional PCR. Furthermore, to explore the possibility of bite transmission during blood feeding, saliva swabs from 35 D. rotundus known to be either Bartonella bacteremic (N = 17) or blood culture negative (N = 18) were tested by PCR to detect the presence of Bartonella DNA. Twenty (17.1%) of 117 sheep and 16 (34.8%) of 46 cattle were Bartonella bacteremic by PCR testing. However, none of them were infected with Bartonella strains previously isolated from vampire bats and none of the 35 D. rotundus saliva swabs tested were PCR positive for Bartonella. All but two animals among those which were Bartonella culture and/or PCR positive, were infected with either B. bovis (cattle) or B. melophagi (sheep). Two sheep were infected by a possible new species, Candidatus Bartonella ovis, being phylogenetically closer to B. bovis than B. melophagi. This study does not support the role of D. rotundus as a reservoir of Bartonella species infecting livestock, which could be transmitted via bite and blood feeding and therefore suggest limited risk of zoonotic transmission of Bartonella from common vampire bats to humans., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Using data from rural monitoring sites across the contiguous United States, we evaluated fine particulate matter (PM 2.5 ) trends for 1988-2016. We calculate trends in the policy-relevant 98th quantile of PM 2.5 using Quantile Regression. We use Kriging and Gaussian Geostatistical Simulations to interpolate trends between observed data points. Overall, we found positive trends in 98th quantile PM 2.5 at sites within the Northwest United States (average 0.21 ± 0.12 µg·m -3 ·y -1 ; ±95% confidence interval). This was in contrast with sites throughout the rest of country, which showed a negative trend in 98th quantile PM 2.5 , likely due to reductions in anthropogenic emissions (average -0.66 ± 0.10 µg·m -3 ·y -1 ). The positive trend in 98th quantile PM 2.5 is due to wildfire activity and was supported by positive trends in total carbon and no trend in sulfate across the Northwest. We also evaluated daily moderate resolution imaging spectroradiometer (MODIS) aerosol optical depth (AOD) for 2002-2017 throughout the United States to compare with ground-based trends. For both Interagency Monitoring of Protected Visual Environments (IMPROVE) PM 2.5 and MODIS AOD datasets, we found positive 98th quantile trends in the Northwest (1.77 ± 0.68% and 2.12 ± 0.81% per year, respectively) through 2016. The trend in Northwest AOD is even greater if data for the high-fire year of 2017 are included. These results indicate a decrease in PM 2.5 over most of the country but a positive trend in the 98th quantile PM 2.5 across the Northwest due to wildfires., Competing Interests: The authors declare no conflict of interest.

Bartonellae are emerging blood-borne bacteria that have been recovered from a wide range of mammalian species and arthropod vectors around the world. Bats are now recognized as a potential wildlife reservoir for a diverse number of Bartonella species, including the zoonotic Candidatus B. mayotimonensis. These bat-borne Bartonella species have also been detected in the obligate ectoparasites of bats, such as blood-feeding flies, which could transmit these bacteria within bat populations. To better understand this potential for transmission, we investigated the relatedness between Bartonella detected or isolated from bat hosts sampled in Mexico and their ectoparasites. Bartonella spp. were identified in bat flies collected on two bat species, with the highest prevalence in Trichobius parasiticus and Strebla wiedemanni collected from common vampire bats (Desmodus rotundus). When comparing Bartonella sequences from a fragment of the citrate synthase gene (gltA), vector-associated strains were diverse and generally close to, but distinct from, those recovered from their bacteremic bat hosts in Mexico. Complete Bartonella sequence concordance was observed in only one bat-vector pair. The diversity of Bartonella strains in bat flies reflects the frequent host switch by bat flies, as they usually do not live permanently on their bat host. It may also suggest a possible endosymbiotic relationship with these vectors for some of the Bartonella species carried by bat flies, whereas others could have a mammalian host.

Many mammals are established hosts for the vector borne bacterial genus, Bartonella. Small Indian mongooses (Herpestes auropunctatus) have only been reported as a possible host for Bartonella henselae in southern Japan. Confirming Bartonella presence in mongooses from other regions in the world may support their role as potential reservoirs of this human pathogen. Specifically, documenting Bartonella in Caribbean mongooses would identify a potential source of zoonotic risk with mongoose-human contact in the New World. Using serological and molecular techniques, we investigated B. henselae DNA and specific antibody prevalence in 171 mongooses from all six parishes in Grenada, West Indies. Almost a third (32.3%, 54/167) of the tested mongooses were B. henselae seropositive and extracted DNA from 18/51 (35.3%) blood pellets  were PCR positive for the citrate synthase (gltA) and/or the β subunit of RNA polymerase (rpoB) genes. All sequences were identical to B. henselae genotype I, as previously reported from Japan. This study confirms the role of small Indian mongooses as a natural reservoir of B. henselae in the New World., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Wildfires emit O 3 precursors but there are large variations in emissions, plume heights, and photochemical processing. These factors make it challenging to model O 3 production from wildfires using Eulerian models. Here we describe a statistical approach to characterize the maximum daily 8-h average O 3 (MDA8) for 8 cities in the U.S. for typical, nonfire, conditions. The statistical model represents between 35% and 81% of the variance in MDA8 for each city. We then examine the residual from the model under conditions with elevated particulate matter (PM) and satellite observed smoke ("smoke days"). For these days, the residuals are elevated by an average of 3-8 ppb (MDA8) compared to nonsmoke days. We found that while smoke days are only 4.1% of all days (May-Sept) they are 19% of days with an MDA8 greater than 75 ppb. We also show that a published method that does not account for transport patterns gives rise to large overestimates in the amount of O 3 from fires, particularly for coastal cities. Finally, we apply this method to a case study from August 2015, and show that the method gives results that are directly applicable to the EPA guidance on excluding data due to an uncontrollable source.

Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (∼2700 m a.s.l.) as well as near their sources using an aircraft. The regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), an index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (∼1 h old) and emissions sampled after atmospheric transport (6-45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.

Bacterial metabolisms are responsible for critical chemical transformations in nearly all environments, including oceans, freshwater, and soil. Despite the ubiquity of bacteria in the atmosphere, little is known about the metabolic functioning of atmospheric bacterial communities. To gain a better understanding of the metabolism of bacterial communities in the atmosphere, we used a combined empirical and model-based approach to investigate the structure and composition of potentially active bacterial communities in air sampled at a high elevation research station. We found that the composition of the putatively active bacterial community (assayed via rRNA) differed significantly from the total bacterial community (assayed via rDNA). Rare taxa in the total (rDNA) community were disproportionately active relative to abundant taxa, and members of the order Rhodospirillales had the highest potential for activity. We developed theory to explore the effects of random sampling from the rRNA and rDNA communities on observed differences between the communities. We found that random sampling, particularly in cases where active taxa are rare in the rDNA community, will give rise to observed differences in community composition including the occurrence of "phantom taxa", taxa which are detected in the rRNA community but not the rDNA community. We show that the use of comparative rRNA/rDNA techniques can reveal the structure and composition of the metabolically active portion of bacterial communities. Our observations suggest that metabolically active bacteria exist in the atmosphere and that these communities may be involved in the cycling of organic compounds in the atmosphere.

Arsenic and many of its compounds are toxic pollutants in the global environment. They can be transported long distances in the atmosphere before depositing to the surface, but the global source-receptor relationships between various regions have not yet been assessed. We develop the first global model for atmospheric arsenic to better understand and quantify its intercontinental transport. Our model reproduces the observed arsenic concentrations in surface air over various sites around the world. Arsenic emissions from Asia and South America are found to be the dominant sources for atmospheric arsenic in the Northern and Southern Hemispheres, respectively. Asian emissions are found to contribute 39% and 38% of the total arsenic deposition over the Arctic and Northern America, respectively. Another 14% of the arsenic deposition to the Arctic region is attributed to European emissions. Our results indicate that the reduction of anthropogenic arsenic emissions in Asia and South America can significantly reduce arsenic pollution not only locally but also globally.

Baseline ozone refers to observed concentrations of tropospheric ozone at sites that have a negligible influence from local emissions. The Mount Bachelor Observatory (MBO) was established in 2004 to examine baseline air masses as they arrive to North America from the west. In May 2012, we observed an O3 increase of 2.0-8.5 ppbv in monthly average maximum daily 8-hour average O3 mixing ratio (MDA8 O3) at MBO and numerous other sites in the western U.S. compared to previous years. This shift in the O3 distribution had an impact on the number of exceedance days. We also observed a good correlation between daily MDA8 variations at MBO and at downwind sites. This suggests that under specific meteorological conditions, synoptic variation in O3 at MBO can be observed at other surface sites in the western U.S. At MBO, the elevated O3 concentrations in May 2012 are associated with low CO values and low water vapor values, consistent with transport from the upper troposphere/lower stratosphere (UT/LS). Furthermore, the Real-time Air Quality Modeling System (RAQMS) analyses indicate that a large flux of O3 from the UT/LS in May 2012 contributed to the observed enhanced O3 across the western U.S. Our results suggest that a network of mountaintop observations, LiDAR and satellite observations of O3 could provide key data on daily and interannual variations in baseline O3.

Ozone (O3) has been measured at Great Basin National Park (GBNP) since September 1993. GBNP is located in a remote, rural area of eastern Nevada. Data indicate that GBNP will not comply with a more stringent National Ambient Air Quality Standard (NAAQS) for O3, which is based upon the 3-year average of the annual 4th highest Maximum Daily 8-h Average (MDA8) concentration. Trend analyses for GBNP data collected from 1993 to 2013 indicate that MDA8 O3 increased significantly for November to February, and May. The greatest increase was for May at 0.38, 0.35, and 0.46 ppb yr(-1) for the 95th, 50th, and 5th percentiles of MDA8 O3 values, respectively. With the exception of GBNP, continuous O3 monitoring in Nevada has been limited to the greater metropolitan areas. Due to the limited spatial detail of O3 measurements in rural Nevada, a network of rural monitoring sites was established beginning in July 2011. For a period ranging from July 2011 to June 2013, maximum MDA8 O3 at 6 sites occurred in the spring and summer, and ranged from 68 to 80ppb. Our analyses indicate that GBNP, in particular, is ideally positioned to intercept air containing elevated O3 derived from regional and global sources. For the 2 year period considered here, MDA8 O3 at GBNP was an average of 3.1 to 12.6 ppb higher than at other rural Nevada sites. Measured MDA8 O3 at GBNP exceeded the current regulatory threshold of 75 ppb on 7 occasions. Analyses of synoptic conditions, model tracers, and air mass back-trajectories on these days indicate that stratospheric intrusions, interstate pollution transport, wildfires, and Asian pollution contributed to elevated O3 observed at GBNP. We suggest that regional and global sources of ozone may pose challenges to achieving a more stringent O3 NAAQS in rural Nevada., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We use measurements made onboard the National Science Foundation's C-130 research aircraft during the 2013 Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) experiment to examine total Hg (THg) emission ratios (EmRs) for six coal-fired power plants (CFPPs) in the southeastern U.S. We compare observed enhancement ratios (ERs) with EmRs calculated using Hg emissions data from two inventories: the National Emissions Inventory (NEI) and the Toxics Release Inventory (TRI). For four CFPPs, our measured ERs are strongly correlated with EmRs based on the 2011 NEI (r(2) = 0.97), although the inventory data exhibit a -39% low bias. Our measurements agree best (to within ±32%) with the NEI Hg data when the latter were derived from on-site emissions measurements. Conversely, the NEI underestimates by approximately 1 order of magnitude the ERs we measured for one previously untested CFPP. Measured ERs are uncorrelated with values based on the 2013 TRI, which also tends to be biased low. Our results suggest that the Hg inventories can be improved by targeting CFPPs for which the NEI- and TRI-based EmRs have significant disagreements. We recommend that future versions of the Hg inventories should provide greater traceability and uncertainty estimates.

During the summer of 2013, we examined the performance of KCl-coated denuders for measuring gaseous oxidized mercury (GOM) by calibrating with a known source of GOM (i.e., HgBr2) at the North Birmingham SouthEastern Aerosol Research and Characterization (SEARCH) site. We found that KCl-coated denuders have near 95% collection efficiency for HgBr2 in zero air (i.e., air scrubbed of mercury and ozone). However, in ambient air, the efficiency of KCl-coated denuders in capturing HgBr2 dropped to 20-54%. We also found that absolute humidity and ozone each demonstrate a significant inverse correlation with HgBr2 recovery in ambient air. Subsequent laboratory tests with HgBr2 and the KCl-coated denuder show that ozone and absolute humidity cause the release of gaseous elemental Hg from the denuder and thus appear to explain the low recovery in ambient air. Based on these findings, we infer that the KCl denuder method underestimates atmospheric GOM concentrations and a calibration system is needed to accurately measure GOM. The system described in this paper for HgBr2 could be implemented with existing mercury speciation instrumentation and this would improve our knowledge of the response to one potentially important GOM compound.

Wildfires generate substantial emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs). As such, wildfires contribute to elevated ozone (O3) in the atmosphere. However, there is a large amount of variability in the emissions of O3 precursors and the amount of O3 produced between fires. There is also significant interannual variability as seen in median O3, organic carbon and satellite derived carbon monoxide mixing ratios in the western U.S. To better understand O3 produced from wildfires, we developed a statistical model that estimates the maximum daily 8 h average (MDA8) O3 as a function of several meteorological and temporal variables for three urban areas in the western U.S.: Salt Lake City, UT; Boise, ID; and Reno, NV. The model is developed using data from June-September 2000-2012. For these three locations, the statistical model can explain 60, 52, and 27% of the variability in daily MDA8. The Statistical Model Residual (SMR) can give information on additional sources of O3 that are not explained by the usual meteorological pattern. Several possible O3 sources can explain high SMR values on any given day. We examine several cases with high SMR that are due to wildfire influence. The first case considered is for Reno in June 2008 when the MDA8 reached 82 ppbv. The wildfire influence for this episode is supported by PM concentrations, the known location of wildfires at the time and simulations with the Weather and Research Forecasting Model with Chemistry (WRF-Chem) which indicates transport to Reno from large fires burning in California. The contribution to the MDA8 in Reno from the California wildfires is estimated to be 26 ppbv, based on the SMR, and 60 ppbv, based on WRF-Chem. The WRF-Chem model also indicates an important role for peroxyacetyl nitrate (PAN) in producing O3 during transport from the California wildfires. We hypothesize that enhancements in PAN due to wildfire emissions may lead to regional enhancements in O3 during high fire years. The second case is for the Salt Lake City (SLC) region for August 2012. During this period the MDA8 reached 83 ppbv and the SMR suggests a wildfire contribution of 19 ppbv to the MDA8. The wildfire influence is supported by PM2.5 data, the known location of wildfires at the time, HYSPLIT dispersion modeling that indicates transport from fires in Idaho, and results from the CMAQ model that confirm the fire impacts. Concentrations of PM2.5 and O3 are enhanced during this period, but overall there is a poor relationship between them, which is consistent with the complexities in the secondary production of O3. A third case looks at high MDA8 in Boise, ID, during July 2012 and reaches similar conclusions. These results support the use of statistical modeling as a tool to quantify the influence from wildfires on urban O3 concentrations.

From August 22 to September 16, 2012, atmospheric mercury (Hg) was measured from a common manifold in the field during the Reno Atmospheric Mercury Intercomparison eXperiment. Data were collected using Tekran systems, laser induced fluorescence, and evolving new methods. The latter included the University of Washington-Detector for Oxidized Mercury, the University of Houston Mercury instrument, and a filter-based system under development by the University of Nevada-Reno. Good transmission of total Hg was found for the manifold. However, despite application of standard protocols and rigorous quality control, systematic differences in operationally defined forms of Hg were measured by the sampling systems. Concentrations of reactive Hg (RM) measured with new methods were at times 2-to-3-fold higher than that measured by Tekran system. The low RM recovery by the latter can be attributed to lack of collection as the system is currently configured. Concentrations measured by all instruments were influenced by their sampling location in-the-manifold and the instrument analytical configuration. On the basis of collective assessment of the data, we hypothesize that reactions forming RM were occurring in the manifold. Results provide a new framework for improved understanding of the atmospheric chemistry of Hg.

The Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) was in Reno, NV from August 22, 2011 to September 16, 2011. The goals of the experiment were to compare existing and new methods for measurements of ambient elemental and oxidized Hg, and to test these with quantitative spikes of Hg(0), HgBr2, O3 and water vapor. In this paper we describe the design, testing, and deployment of a high flow manifold system designed to deliver ambient air and spiked compounds to multiple instruments simultaneously. The manifold was constructed of 1" OD PFA tubing and heated to 115 °C for the entire active zone. Manifold flow was controlled at ∼200 LPM using a blower and a velocity sensor in a feedback control system. Permeation tubes in controlled ovens were used to deliver Hg(0) and HgBr2. Ozone was generated from a small UV lamp in a flow of high purity O2. Water vapor was generated by pumping a flow of purified N2 through heated, high purity water. The spiking delivery for Hg(0), HgBr2, O3, and water vapor after dilution in the manifold ranged up to 20 ng m(-3), 0.64 ng m(-3), 100 ppbv, and 20 g kg(-1), respectively. During laboratory tests the average transmission efficiencies for Hg(0), HgBr2, and O3 were found to be 92%, 76%, and 93%, respectively.

The Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) was carried out from 22 August to 16 September, 2011 in Reno, NV to evaluate the performance of new and existing methods to measure atmospheric mercury (Hg). Measurements were made using a common sampling manifold to which controlled concentrations of Hg species, including gaseous elemental mercury (GEM) and HgBr2 (a surrogate gaseous oxidized mercury (GOM) compound), and potential interferents were added. We present an analysis of Hg measurements made using the University of Washington's Detector for Oxidized Hg Species (DOHGS), focusing on tests of GEM and HgBr2 spike recovery, the potential for interference from ozone (O3) and water vapor (WV), and temporal variability of ambient reactive mercury (RM). The mean GEM and HgBr2 spike recoveries measured with the DOHGS were 95% and 66%, respectively. The DOHGS responded linearly to HgBr2. We found no evidence that elevated O3 interfered in the DOHGS RM measurements. A reduction in RM collection and retention efficiencies at very high ambient WV mixing ratios is possible. Comparisons between the DOHGS and participating Hg instruments demonstrate good agreement for GEM and large discrepancies for RM. The results suggest that existing GOM measurements are biased low.

Microorganisms are abundant in the upper atmosphere, particularly downwind of arid regions, where winds can mobilize large amounts of topsoil and dust. However, the challenge of collecting samples from the upper atmosphere and reliance upon culture-based characterization methods have prevented a comprehensive understanding of globally dispersed airborne microbes. In spring 2011 at the Mt. Bachelor Observatory in North America (2.8 km above sea level), we captured enough microbial biomass in two transpacific air plumes to permit a microarray analysis using 16S rRNA genes. Thousands of distinct bacterial taxa spanning a wide range of phyla and surface environments were detected before, during, and after each Asian long-range transport event. Interestingly, the transpacific plumes delivered higher concentrations of taxa already in the background air (particularly Proteobacteria, Actinobacteria, and Firmicutes). While some bacterial families and a few marine archaea appeared for the first and only time during the plumes, the microbial community compositions were similar, despite the unique transport histories of the air masses. It seems plausible, when coupled with atmospheric modeling and chemical analysis, that microbial biogeography can be used to pinpoint the source of intercontinental dust plumes. Given the degree of richness measured in our study, the overall contribution of Asian aerosols to microbial species in North American air warrants additional investigation.

Microorganisms are abundant in the troposphere and can be transported vast distances on prevailing winds. This study measures the abundance and diversity of airborne bacteria and fungi sampled at the Mt. Bachelor Observatory (located 2.7 km above sea level in North America) where incoming free tropospheric air routinely arrives from distant sources across the Pacific Ocean, including Asia. Overall deoxyribonucleic acid (DNA) concentrations for microorganisms in the free troposphere, derived from quantitative polymerase chain reaction assays, averaged 4.94 × 10(-5) ng DNA m(-3) for bacteria and 4.77 × 10(-3) ng DNA m(-3) for fungi. Aerosols occasionally corresponded with microbial abundance, most often in the springtime. Viable cells were recovered from 27.4 % of bacterial and 47.6 % of fungal samples (N = 124), with 49 different species identified by ribosomal DNA gene sequencing. The number of microbial isolates rose significantly above baseline values on 22-23 April 2011 and 13-15 May 2011. Both events were analyzed in detail, revealing distinct free tropospheric chemistries (e.g., low water vapor, high aerosols, carbon monoxide, and ozone) useful for ruling out boundary layer contamination. Kinematic back trajectory modeling suggested air from these events probably originated near China or Japan. Even after traveling for 10 days across the Pacific Ocean in the free troposphere, diverse and viable microbial populations, including presumptive plant pathogens Alternaria infectoria and Chaetomium globosum, were detected in Asian air samples. Establishing a connection between the intercontinental transport of microorganisms and specific diseases in North America will require follow-up investigations on both sides of the Pacific Ocean.

We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products (131)I, (132)I, (132)Te, (134)Cs, and (137)Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity from radionuclides attached to particulate matter amounted to 4.4 ± 1.3 mBq m(-3) of (131)I on 19-20 March., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Fifty-six seasonal snowpack samples were collected at remote alpine, subarctic, and arctic sites in eight Western U.S. national parks during three consecutive years (2003-2005). Four current-use pesticides (CUPs) (dacthal (DCPA), chlorpyrifos, endosulfans, and gamma-hexachlorocyclohexane (HCH)) and four historic-use pesticides (HUPs) (dieldrin, alpha-HCH, chlordanes, and hexachlorobenzene (HCB)) were commonly measured at all sites, during all years. The mean coefficient of variation for pesticide concentrations was 15% for site replicate samples, 41% for intrapark replicate samples, and 59% for interannual replicate samples. The relative pesticide concentration profiles were consistent from year to year but unique for individual parks, indicating a regional source effect. HUP concentrations were well-correlated with regional cropland intensity when the effect of temperature on snow-air partitioning was considered. The mass of individual CUPs used in regions located one-day upwind of the parks was calculated using air mass back trajectories, and this was used to explain the distribution of CUPs among the parks. The percent of the snowpack pesticide concentration due to regional transport was high (>75%) for the majority of pesticides in all parks. These results suggest that the majority of pesticide contamination in U.S. national parks is due to regional pesticide use in North America.

We developed a high time resolution (2.5 min) aircraft instrument for gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM). The system measures RGM with complementary denuder and difference techniques, which can be compared to check for consistency. In laboratory tests, the agreement of the two techniques was 15% (+/- 13%). In five test flights, RGM was generally below the detection limit of the difference technique (0.08-0.16 ng/m3) except for values of 200-500 pg/m3 in airmasses between 600-700 mb (Flight 1) and 850-550 mb (Right 4), which is consistent with previous observations of RGM at Mt Bachelor. There was a linear correlation between the denuder and difference techniques in each flight (range of slopes, 0.27-1.24) and across all flights (slope = 0.37, p < 1e-6). The correlation is evidence that the difference technique is able to measure RGM in real time, although RGM appears to not be fully captured or recovered by the denuder. The only factor common to all RGM enhancements was the low aerosol scattering coefficient (< 2 M/m). Particulate mercury was below the detection limit (27 pg/m3) for all samples. The mean GEM and total mercury (THg) profiles are in the middle of the range of other published profiles. The THg profile showed no gradient to 5.5 km (p = 0.12, r2 = 0.009).

Ozone exposure is associated with negative health impacts, including premature mortality. Observations and modeling studies demonstrate that emissions from one continent influence ozone air quality over other continents. We estimate the premature mortalities avoided from surface ozone decreases obtained via combined 20% reductions of anthropogenic nitrogen oxide, nonmethane volatile organic compound, and carbon monoxide emissions in North America (NA), EastAsia (EA), South Asia (SA), and Europe (EU). We use estimates of ozone responses to these emission changes from several atmospheric chemical transportmodels combined with a health impactfunction. Foreign emission reductions contribute approximately 30%, 30%, 20%, and >50% of the mortalities avoided by reducing precursor emissions in all regions together in NA, EA, SA and EU, respectively. Reducing emissions in NA and EU avoids more mortalities outside the source region than within, owing in part to larger populations in foreign regions. Lowering the global methane abundance by 20% reduces mortality mostin SA,followed by EU, EA, and NA. For some source-receptor pairs, there is greater uncertainty in our estimated avoided mortalities associated with the modeled ozone responses to emission changes than with the health impact function parameters.