In situ measurements of the mass, mixing state, and optical size of individual black‐carbon (BC) particles in the fine mode (90–600 nm) have been made in fresh emissions from urban and biomass ...burning sources with an airborne single‐particle soot photometer. Contrasts between the two sources are significant and consistent. Urban BC tends to smaller sizes, fewer coated particles, thinner coatings, and less absorption per unit mass than biomass‐burning BC. This suggests that urban BC may have a longer lifetime in the atmosphere and a different impact on BC radiative forcing in the first indirect effect than biomass‐burning BC. These measurements bound the likely variability in the microphysical state of BC emissions from typical continental processes, and provide direct measurements of the size distribution and coating state of fine‐mode BC for use in constraining climate and aerosol models. These results highlight the need for the integration of source‐specific information into such models.
Recent decreases in nitrogen oxide (NOx = NO + NO2) emissions from eastern U.S. power plants and their effects on regional ozone are studied. Using the EPA 1999 National Emission Inventory as a ...reference emission data set, NOx and sulfur dioxide (SO2) emission rates at selected power plants are updated to their summer 2003 levels using Continuous Emission Monitoring System (CEMS) measurements. The validity of the CEMS data is established by comparison to observations made on the NOAA WP‐3 aircraft as part of the 2004 New England Air Quality Study. The impacts of power plant NOx emission decreases on O3 are investigated using the WRF‐Chem regional chemical forecast model. Summertime NOx emission rates decreased by approximately 50% between 1999 and 2003 at the subset of power plants studied. The impact of NOx emission reductions on ozone was moderate during summer 2004 because of relatively cool temperatures and frequent synoptic disturbances. Effects in individual plant plumes vary depending on the plant's NOx emission strength, the proximity of other NOx sources, and the availability of volatile organic compounds (VOCs) and sunlight. This study provides insight into the ozone changes that can be anticipated as power plant NOx emission reductions continue to be implemented throughout the United States.
•Finland had a different drug profile compared to the other countries.•Opioids were the main cause of death among fatal poisoned drug addicts in all countries.•Cocaine and MDMA deaths increased in ...all countries.•Sweden saw a high number of deaths from fentanyl analogues.•New psychoactive substances have emerged in all countries except Iceland.
This study is the seventh report on fatal poisonings among drug addicts in the Nordic countries. In this report, we analyse data from the five Nordic countries: Denmark, Finland, Iceland, Norway and Sweden. Data on gender, number of deaths, places of deaths, age, main intoxicants and substances detected in blood were recorded to obtain national and comparable Nordic data, and to allow comparison with earlier studies conducted in 1984, 1991, 1997, 2002, 2007 and 2012.
The death rate (number of deaths per 100,000 inhabitants) was highest in Iceland (6.58) followed closely by Sweden (6.46) and then lowest in Denmark (4.29). The death rate increased in Finland (5.84), Iceland and Sweden and decreased in Denmark compared to earlier studies. The death rate in Norway, which has decreased since 2002, has stabilised around 5.7 as of 2017. Women accounted for 7–23% of the fatal poisonings. The percentage was lowest in Iceland and highest in Finland and Norway. The age range was 14–70 years. The median age (41 years) was highest in Denmark and Norway. The other countries had a median age between 33 and 35 years.
Opioids were the main cause of death. Methadone remained the main intoxicant in Denmark, while heroin/morphine was still the main intoxicant in Norway, as was buprenorphine in Finland. However, the picture has changed in Sweden compared to 2012, where heroin/morphine caused most deaths in 2017. Sweden also experienced the highest number of deaths from fentanyl analogues (67 deaths) and buprenorphine (61 deaths). Deaths from fentanyl analogues also occurred in Denmark, Finland and Norway, but to a smaller extent. Over the years, the proportion of opioid deaths has decreased in all countries except Sweden, which has experienced an increase. This decline has been replaced by deaths from CNS stimulants like cocaine, amphetamine and methylenedioxymethamphetamine (MDMA). Cocaine deaths have occurred in all countries but most frequently in Denmark. MDMA deaths have increased in all countries but mostly in Finland.
Poly-drug use was widespread, as seen in the earlier studies. The median number of detected drugs per case varied from 4–6. Heroin/morphine, methadone, buprenorphine, cocaine, amphetamine, methamphetamine, MDMA, tetrahydrocannabinol (THC) and benzodiazepines were frequently detected. Pregabalin and gabapentin were detected in all countries, especially pregabalin, which was detected in 42% of the Finnish cases. New psychoactive substances (NPS) occurred in all countries except Iceland.
Data taken in aircraft transects of emissions plumes from rural U.S. coal-fired power plants were used to confirm and quantify the nonlinear dependence of tropospheric ozone formation on plume NOx(NO ...plus NO2) concentration, which is determined by plant NOxemission rate and atmospheric dispersion. The ambient availability of reactive volatile organic compounds, principally biogenic isoprene, was also found to modulate ozone production rate and yield in these rural plumes. Differences of a factor of 2 or greater in plume ozone formation rates and yields as a function of NOxand volatile organic compound concentrations were consistently observed. These large differences suggest that consideration of power plant NOxemission rates and geographic locations in current and future U.S. ozone control strategies could substantially enhance the efficacy of NOxreductions from these sources.
Nitrogen dioxide (NO2) columns observed from space have been useful in detecting the increase of nitrogen oxides (NOx) emissions in East Asia, particularly China, coinciding with rapid economic ...growth during the past several decades. NO2 columns retrieved above a particular location reflect a combination of local NOx emissions and transported NOx from upwind sources. In this study, we demonstrate the transport of NOx emitted in East Asia using satellite and surface in situ measurements and Lagrangian particle dispersion model simulations. Enhanced satellite NO2 columns in the Yellow Sea (between China and South Korea) and the East Sea (between South Korea and Japan), and different seasonal variations of NO2 in China, North and South Korea, and Japan, suggest the importance of NOx transport in understanding the local NOx budget. Lagrangian transport model simulations with tracers of different chemical lifetimes identify source‐receptor relationships that explain high NO2 over the oceans and springtime peaks in Korea and Japan, with China being the most likely source region. Our results have important implications for studies using satellite NO2 retrievals to derive NOx emissions at local scales in regions adjacent to large sources, such as in East Asia, Europe, and the Eastern U.S.
Key Points
Satellite demonstrates springtime transport of NOx over Korea and Japan
Transport from China explains large NO2 columns over the Yellow Sea
Transport of NOx is important in understanding local budget of NOx
Highlights • We analysed data on fatal poisoning in drug addicts in 2012 from five Nordic countries. • Differences in death rate among fatal poisoned drug addicts diminished between the countries ...compared to earlier studies. • Opioids were the main cause of death among fatal poisoned drug addicts in all countries. • Medicinal opioids had mainly replaced heroin/morphine. • New psychoactive substances emerged.
There are many isolated sources of NOx emissions across the western United States, including electrical power generation plants and urban areas. In this manuscript, two satellite instruments ...measuring NO2 vertical columns over these sources and an atmospheric chemical‐transport model are used to evaluate bottom‐up NOx emission inventories, model assumptions, and satellite retrieval algorithms. We carried out simulations with the Weather Research and Forecasting‐Chemistry (WRF‐Chem) model for the western U.S. domain during the summer of 2005 using measured power plant NOx emissions. Model NO2 vertical columns are compared with a retrieval of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite instrument data by the University of Bremen and retrievals of the Ozone Monitoring Instrument (OMI) data by the U.S. National Aeronautics and Space Administration (NASA) and a modified version of the NASA OMI retrieval produced by the University of Bremen. For areas dominated by power plant NOx emissions, the model NO2 columns serve as a comparison standard for satellite retrievals because emissions are continuously monitored at all large U.S. power plants. An extensive series of sensitivity tests of the assumptions in both the satellite retrievals and the model are carried out over the Four Corners and San Juan power plants, two adjacent facilities in the northwest corner of New Mexico that together represent the largest NOx point source in the United States. Overall, the SCIAMACHY and OMI NO2 columns over western U.S. power plants agree well with model NO2 columns, with differences between the two being within the variability of the model and satellite. In contrast to regions dominated by power plant emissions, model NO2 columns over large urban areas along the U.S. west coast are approximately twice as large as satellite NO2 columns from SCIAMACHY and OMI retrievals. The discrepancies in urban areas are beyond the sensitivity ranges in the model simulations and satellite observations, implying overestimates of these cities' bottom‐up NOx emissions, which are dominated by motor vehicles. Taking the uncertainties in the satellite retrievals into account, our study demonstrates that the tropospheric columns of NO2 retrieved from space‐based observations of backscattered solar electromagnetic radiation can be used to evaluate and improve bottom‐up emission inventories.
A new method to determine fluid flux at high pressures and temperatures has been developed and used to study serpentinites at subduction zone conditions. Drill cores of a natural ...antigorite‐serpentinite with a strong foliation were used in multi‐anvil experiments in the range of 2–5 GPa and 450–800°C. Fluids released upon dehydration are fixed by the formation of brucite in an adjacent fluid sink. The amount and distribution of brucite serves as a proxy for fluid flow. In our specific setup the sample reacted with the surrounding fluid sink to form an additional layer of olivine, which has the potential to limit fluid flux within our experiments. For conditions prior to serpentine dehydration we used Al(OH)3 as fluid source. Fluid in this experiment did not migrate through the serpentinite, indicating that serpentine has a low diffusivity. The experiments also show that small deviatoric stresses have an influence on the fluid flux and can cause an anisotropic fluid flux. Comparison between the time scales of the determined fluid flux with fluid production rates indicates fluid pressure buildup during dehydration reactions. Adjacent less permeable layers can inhibit fluid flux and cause fluid pressure buildup even at conditions when an interconnected pore space formed.
Plain Language Summary
Subduction zones are regions where tectonic plates are recycled into the Earth's interior. Prior to subduction, the plates experienced extensive chemical interaction with the ocean water, forming hydrous minerals. Serpentine is an important hydrous mineral that can transport significant amounts of water into the Earth's interior. During subduction both pressure and temperature increase whereby hydrous minerals break down and release their water. The fluid migrates into the overlying mantle wedge, where it accounts for hydration as well as melting processes. The global flux balances would require this process to be very effective. However, it was so far not possible to measure the fluid flux at the subduction zone conditions in laboratories. In this study, we present a new method to determine the fluid flux prior and during dehydration. We found that prior to dehydration, the fluid flux in serpentinites is small. During dehydration the rocks ability to let fluids pass through increases. However, adjacent rocks with a low ability for fluid transport can further inhibit a fluid flux at these conditions. Generally, our experimental setup can be used for any system that immobilizes migrating fluids by hydration reactions.
Key Points
A new method to determine fluid flux at high pressure and temperature conditions is developed
Slow fluid migration in serpentinites promotes brittle fracturing in subduction zones
Fast fluid migration upon dehydration of serpentinites promotes large‐scale fluid flux, if not inhibited by adjacent less permeable layers
PDF
