Long-term trends in nitrogen oxides concentrations and on-road vehicle emission factors in Copenhagen, London and Stockholm

Krecl, P; Harrison, RM; Johansson, C; Targino, AC; Beddows, DC; Ellermann, T; Lara, C; Ketzel, M
2021 | Environ. Pollut. | 290
air quality , air quality in europe , atmospheric pollutants , black carbon , dieselization , model , no2 concentrations , nox , ospm model , particle number , policy , pollution , road transport , street , urban
Road transport is the main anthropogenic source of NOx in Europe, affecting human health and ecosystems. Thus, mitigation policies have been implemented to reduce on-road vehicle emissions, particularly through the Euro standard limits. To evaluate the effectiveness of these policies, we calculated NO2 and NOx concentration trends using air quality and meteorological measurements conducted in three European cities over 26 years. These data were also employed to estimate the trends in NOx emission factors (EFNox, based on inverse dispersion modeling) and NO2:NOx emission ratios for the vehicle fleets under real-world driving conditions. In the period 1998-2017, Copenhagen and Stockholm showed large reductions in both the urban background NOx concentrations (-2.1 and -2.6% yr(-1), respectively) and EFNox at curbside sites (68 and 43%, respectively), proving the success of the Euro standards in diminishing NOx emissions. London presented a modest decrease in urban background NOx concentrations (-1.3% yr(-1)), while EFNox remained rather constant at the curbside site (Marylebone Road) due to the increase in public bus traffic. NO2 primary emissions -that are not regulated- increased until 2008-2010, which also reflected in the ambient concentrations. This increase was associated with a strong dieselization process and the introduction of new after-treatment technologies that targeted the emission reduction of other species (e.g., greenhouse gases or particulate matter). Thus, while regulations on ambient concentrations of specific species have positive effects on human health, the overall outcomes should be considered before widely adopting them. Emission inventories for the on-road transportation sector should include EFNox derived from real-world measurements, particularly in urban settings.

The Importance of Benthic Nutrient Fluxes in Supporting Primary Production in the Laptev and East Siberian Shelf Seas

Sun, XL; Humborg, C; Morth, CM; Bruchert, V
2021 | Global Biogeochem Cycles | 35 (7)
arctic-ocean , benthic flux , carbon , chukchi sea , continental-shelf , denitrification rates , nitrogen , nitrogen-fixation , nutrient , organic-matter , phosphorus , sediments , siberian shelf , silica , trace metals , transport
This study presents an assessment of benthic nutrient regeneration and its role for the nutrient budget of the outer Laptev and East Siberian shelf sea. Porewater profiles of the major nutrients dissolved silica (DSi), dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphate (DIP) as well as total dissolved iron (DFe) were evaluated with a one-dimensional reaction transport model to derive net reaction rates and benthic nutrient fluxes from shelf and slope 16 stations. Integrated over the shelf area the benthic fluxes of DSi, DIN, and DIP were found to be 7.1, 1.2, and 0.5 Gmol/year in the Laptev Sea and 29.8, 9.5, and 2.8 Gmol/year in East Siberian Sea, respectively. A comparison of the ratios of the benthic nutrient fluxes with marine and riverine inputs and Arctic plankton stoichiometry indicate substantial benthic nitrogen loss likely due to denitrification relative to DIP and DSi. Our benthic flux estimation is likely a low estimate of benthic nutrient fluxes considering potentially higher regeneration rates of nutrients from more productive, bioturbated near-shore sediments. The estimate emphasizes the role of benthic nutrient fluxes by returning nutrients with a fundamentally different stoichiometry to bottom waters from that of Arctic marine phytoplankton, riverine sources, and open water inflow. With a simple box model, we provide a snapshot of today's nutrient budget in the two seas and estimate that about 10%-20% of nutrients required by primary production are derived from sediments. This proportion is expected to increase for a future warmer Arctic continental shelf in response to increasing primary production.

Spatial-temporal Variation and Local Source Identification of Air Pollutants in a Semi-urban Settlement in Nigeria Using Low-cost Sensors

Owoade, OK; Abiodun, PO; Omokungbe, OR; Fawole, OG; Olise, FS; Popoola, OOM; Jones, RL; Hopke, PK
2021 | Aerosol Air Qual. Res. | 21 (10)
aerosol , area , cbpf , electrochemical sensors , low-cost sensors , opc-n2 , particulate matter , pm2.5 , pollution , quality , site , source identification , temporal variation
Low-cost sensors were deployed at five locations in a growing, semi-urban settlement in southwest Nigeria between June 8 and July 31, 2018 to measure particulate matter (PM2.5 and PM10), gaseous pollutants (CO, NO, NO2, O-3 and CO2), and meteorological variables (air temperature, relative humidity, wind speed and wind-direction). The spatial and temporal variations of measured pollutants were determined, and the probable sources of pollutants were inferred using conditional bivariate probability function (CBPF). Hourly PM2.5 and PM10 concentrations ranged from 20.7 +/- 0.7 to 36.3 +/- 1.6 mu g m(-3) and 47.5 +/- 1.5 to 102.9 +/- 5.6 mu g m(-3), respectively. Hourly gaseous pollutant concentrations ranged from 348 +/- 132 to 542 +/- 200 ppb CO, 21.5 +/- 7.2 ppb NO2 and 57.5 +/- 11.3 to 64.4 +/- 14.0 ppb O-3. Kruskal-Wallis ANOVA on ranks determined statistically significant spatial differences in the hourly-average pollutant concentrations. Diel variation analyses indicated that CO2, PM2.5, and PM10 peaked in the early hours of most days, O-3 at noon while NO, NO2, and CO peaked in the evening. Most pollutants were of anthropogenic origins and exhibited the highest contributions from the southwest at most sampling locations. There were strong similarities between pollutants source contribution at two of the monitoring sites that were in residential areas with a frequently used paved road. Mitigation strategies need to be established to avoid further deterioration of ambient air quality that negatively affect public health.

Chemical profiling of the Arctic sea lettuce Ulva lactuca (Chlorophyta) mass-cultivated on land under controlled conditions for food applications

Roleda, MY; Lage, S; Aluwini, DF; Rebours, C; Brurberg, MB; Nitschke, U; Gentili, FG
2021 | Food Chem | 341
acid-composition , amino-acid , amino-acids , bulk biomass , diversity , edible seaweeds , fatty acid , food quality , heavy metals , iodine , liquid chromatography , microalgae , minerals , nordic cuisine , prolifera , protein , sugar , toxic elements
The increasing use of seaweeds in European cuisine led to cultivation initiatives funded by the European Union. Ulva lactuca, commonly known as sea lettuce, is a fast growing seaweed in the North Atlantic that chefs are bringing into the local cuisine. Here, different strains of Arctic U. lactuca were mass-cultivated under controlled conditions for up to 10 months. We quantified various chemical constituents associated with both health benefits (carbohydrates, protein, fatty acids, minerals) and health risks (heavy metals). Chemical analyses showed that long-term cultivation provided biomass of consistently high food quality and nutritional value. Concentrations of macroelements (C, N, P, Ca, Na, K, Mg) and micronutrients (Fe, Zn, Co, Mn, I) were sufficient to contribute to daily dietary mineral intake. Heavy metals (As, Cd, Hg and Pb) were found at low levels to pose health risk. The nutritional value of Ulva in terms of carbohydrates, protein and fatty acids is comparable to some selected fruits, vegetables, nuts and grains.

Steady-State Mass Balance Model for Predicting Particle-Gas Concentration Ratios of PBDEs

2021 | Environ. Sci. Technol. | 55 (14) (9425-9433)
air partition-coefficients , aromatic-hydrocarbons pahs , brominated flame retardants , dibenzo-p-dioxins , diphenyl ethers pbdes , equilibration time scales , global air , long range transport , semivolatile organic-chemicals , vapor-pressure
Assuming equilibrium partitioning between the gas and particle phases has been shown to overestimate the fraction of low-volatility chemicals in the particle phase. Here, we present a new steady-state mass balance model that includes separate compartments for fine and coarse aerosols and the gas phase and study its sensitivity to the input parameters. We apply the new model to investigate deviations from equilibrium partitioning by exploring model scenarios for seven generic aerosol scenarios representing different environments and different distributions of emissions as the gas phase, fine aerosol, and coarse aerosol. With 100% of emissions as the particle phase, the particle-gas concentration ratio in our model is similar to the equilibrium model, while differences are up to a factor of 10(6) with 100% of emissions as the gas phase. The particle-gas concentration ratios also depend on the particle size distributions and aerosol loadings in the different environmental scenarios. The new mass balance model can predict the particle-gas concentration ratio with more fidelity to measurements than equilibrium models. However, further laboratory-based evaluations and calibrations of the standard sampling techniques, field investigations with preferably size-resolved measurements of aerosol particle composition, together with the appropriate process modeling for low-volatility chemicals are warranted.

Uptake of perfluorinated alkyl acids by crops: results from a field study

Felizeter, S; Jurling, H; Kotthoff, M; De Voogt, P; McLachlan, MS
2021 | Environ. Sci.-Process Impacts | 23 (8) (1158-1170)
breast milk , carboxylic-acids , edible crops , health-risks , human exposure , perfluoroalkyl substances , perfluorooctane sulfonate (pfos) , plant compartments , root uptake , translocation
Four crops with different edible plant parts (radish, lettuce, pea and maize) were grown in outdoor lysimeters on soil spiked with 13 perfluorinated alkyl acids (PFAAs) at 4 different levels. PFAA concentrations were measured in soil, soil pore water, and different plant parts at harvest. Edible part/soil concentration factors ranged over seven orders of magnitude and decreased strongly with increasing PFAA chain length, by a factor of 10 for each additional fluorinated carbon (n(CF)) for pea. Three processes were responsible for most of the variability. The first was sorption to soil; calculating whole plant concentration factors on the basis of concentration in pore water instead of soil reduced the variability from five orders of magnitude to two. Second, the journey of the PFAAs with the transpiration stream to the leaves was hindered by retention in the roots driven by sorption; root retention factors increased by a factor 1.7 for each n(CF). Third, transfer of PFAAs from the leaves to the fruit via the phloem flow was also hindered - presumably by sorption; fruit/leaf concentration factors decreased by a factor 2.5 for each n(CF). A simple mathematical model based on the above principles described the measured concentrations in roots, leaves, fruits and radish bulbs within a factor 4 in most cases. This indicates that the great diversity in PFAA transfer from soil to crops can be largely described with simple concepts for four markedly different species.

The Role of Behavioral Ecotoxicology in Environmental Protection

Ford, AT; Agerstrand, M; Brooks, BW; Allen, J; Bertram, MG; Brodin, T; Dang, ZC; Duquesne, S; Sahm, R; Hoffmann, F; Hollert, H; Jacob, S; Kluver, N; Lazorchak, JM; Ledesma, M; Melvin, SD; Mohr, S; Padilla, S; Pyle, GG; Scholz, S; Saaristo, M; Smit, E; Steevens, JA; van den Berg, S; Kloas, W; Wong, BBM; Ziegler, M; Maack, G
2021 | Environ. Sci. Technol. | 55 (9) (5620-5628)
consequences , ecology , evolution , mate choice , pollution , support , survival , toxicology
For decades, we have known that chemicals affect human and wildlife behavior. Moreover, due to recent technological and computational advances, scientists are now increasingly aware that a wide variety of contaminants and other environmental stressors adversely affect organismal behavior and subsequent ecological outcomes in terrestrial and aquatic ecosystems. There is also a groundswell of concern that regulatory ecotoxicology does not adequately consider behavior, primarily due to a lack of standardized toxicity methods. This has, in turn, led to the exclusion of many behavioral ecotoxicology studies from chemical risk assessments. To improve understanding of the challenges and opportunities for behavioral ecotoxicology within regulatory toxicology/risk assessment, a unique workshop with international representatives from the fields of behavioral ecology, ecotoxicology, regulatory (eco)toxicology, neurotoxicology, test standardization, and risk assessment resulted in the formation of consensus perspectives and recommendations, which promise to serve as a roadmap to advance interfaces among the basic and translational sciences, and regulatory practices.

Identifying source regions of air masses sampled at the tropical high-altitude site of Chacaltaya using WRF-FLEXPART and cluster analysis

Aliaga, D; Sinclair, VA; Andrade, M; Artaxo, P; Carbone, S; Kadantsev, E; Laj, P; Wiedensohler, A; Krejci, R; Bianchi, F
2021 | Atmos. Chem. Phys. | 21 (21) (16453-16477)
aerosol , atmospheric transport , background station , black carbon , carbon-monoxide , climatology , free troposphere , jungfraujoch , planetary boundary-layer , pm10
Observations of aerosol and trace gases in the remote troposphere are vital to quantify background concentrations and identify long-term trends in atmospheric composition on large spatial scales. Measurements made at high altitude are often used to study free-tropospheric air; however such high-altitude sites can be influenced by boundary layer air masses. Thus, accurate information on air mass origin and transport pathways to high-altitude sites is required. Here we present a new method, based on the source-receptor relationship (SRR) obtained from backwards WRF-FLEXPART simulations and a k-means clustering approach, to identify source regions of air masses arriving at measurement sites. Our method is tailored to areas of complex terrain and to stations influenced by both local and long-range sources. We have applied this method to the Chacaltaya (CHC) GAW station (5240 m a.s.l.; 16.35 degrees S, 68.13 degrees W) for the 6-month duration of the "Southern Hemisphere high-altitude experiment on particle nucleation and growth" (SALILNA) to identify where sampled air masses originate and to quantify the influence of the surface and the free troposphere. A key aspect of our method is that it is probabilistic, and for each observation time, more than one air mass (cluster) can influence the station, and the percentage influence of each air mass can be quantified. This is in contrast to binary methods, which label each observation time as influenced by either boundary layer or free-troposphere air masses. Air sampled at CHC is a mix of different provenance. We find that on average 9 % of the air, at any given observation time, has been in contact with the surface within 4 d prior to arriving at CHC. Furthermore, 24 % of the air has been located within the first 1.5 km above ground level (surface included). Consequently, 76 % of the air sampled at CHC originates from the free troposphere. However, pure free-tropospheric influences are rare, and often samples are concurrently influenced by both boundary layer and free-tropospheric air masses. A clear diurnal cycle is present, with very few air masses that have been in contact with the surface being detected at night. The 6-month analysis also shows that the most dominant air mass (cluster) originates in the Amazon and is responsible for 29 % of the sampled air. Furthermore, short-range clusters (origins within 100 km of CHC) have high temporal frequency modulated by local meteorology driven by the diurnal cycle, whereas the mid- and long-range clusters' (> 200 km) variability occurs on timescales governed by synoptic-scale dynamics. To verify the reliability of our method, in situ sulfate observations from CHC are combined with the SRR clusters to correctly identify the (pre-known) source of the sulfate: the Sabancaya volcano located 400 km north-west from the station.

Ecotoxicological assessment of suspended solids: The importance of biofilm and particle aggregation

Motiei, A; Ogonowski, M; Reichelt, S; Gorokhova, E
2021 | Environ. Pollut. | 280
aggregation , biofilm , clay , daphnia-magna , flocculation , fresh , microplastics , particle hazardous effects , pls-sem , polystyrene , size distribution , water quality , wettability
Assessment of microplastic impacts in biota is challenging due to the complex behavior of the test particles and their interactions with other particulates, including microorganisms, in the environment. To disentangle responses to microplastic exposure from those to other suspended solids, both micro plastic and natural particles must be present in the test system. We evaluated how microplastic, non plastic particles, and biofilms interacted in their effects on survivorship using acute toxicity assay with Daphnia magna. The animals were exposed to microplastic and kaolin at different concentrations of suspended solids (SS; 10, 100, and 1000 mg/L) with a varying microplastic contribution (%MP; 0e80%) and biofilm (presence/absence) associated with the solids. Also, we examined how these exposure parameters (SS, %MP, and Biofilm) affected aggregate formation that was analyzed using particle size distribution data. Under the exposure conditions, Daphnia mortality was primarily driven by SS concentration but ameliorated by both microplastic and biofilm. The ameliorating effects were related to increased particle aggregation in the presence of biofilm and high %MP. In addition, a weak yet significant positive effect of the biofilm on the survivorship was observed, presumably, due to microbial food supply to the daphniids in the exposure system; the bacteria were utilized at the absence of other food. Therefore, the effects of both natural and anthropogenic particulates depend on the particle behavior and aggregation in the water governed by microbial communities and physicochemical properties of the particles, which must be taken into account in the hazard assessment of plastic litter. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Long-term increasing trends in the wet deposition of secondary inorganic constituents in SW Indian precipitation

Budhavant, KB; Gawhane, RD; Rao, PSP; Nair, HRCR; Safai, PD
2021 | Air Qual. Atmos. Health | 14 (5) (667-677)
acidity , aerosols , air quality , black carbon , chemical composition , chemistry , cloud-water , high-altitude station , monsoon , rain water , rainwater , south asia , wet deposition
Precipitation chemistry measurements are essential to estimate the deposition of ionic components that are beneficial or harmful to the ecosystems and quantify the wet scavenging of the atmospheric constituents. A long-term (2006 to 2016) database of the water-soluble inorganic components in the rainwater (RW) at Pune (an urban location) and Sinhagad (a high-altitude rural location) in southwest India was examined to understand the trends in measured anthropogenic components and the factors controlling the chemistry of RW in this region. We observed the long-term increasing trends in NH4+ at Pune and SO42-, NO3 over bar , and NH4+ at Sinhagad. About 10% of rain samples were acidic (below 5.6). Low pH values were generally measured at Pune (8%) and Sinhagad (9%) stations when the air mass back trajectories (AMBTs) originated from land. This study suggests that NO3 over bar plays a vital role in acidifying the rain in both the sampling stations, though SO42- remains the dominant factor. The high concentrations of Ca2+ and NH4+ have played a significant role in neutralizing the acidity of RW. The cluster analysis of AMBTs showed that at Pune 74% and Sinahagd 65% of rain events were associated with oceanic air masses from the Arabian Sea.

Observed and Modeled Black Carbon Deposition and Sources in the Western Russian Arctic 1800-2014

Ruppel, MM; Eckhardt, S; Pesonen, A; Mizohata, K; Oinonen, MJ; Stohl, A; Andersson, A; Jones, V; Manninen, S; Gustafsson, O
2021 | Environ. Sci. Technol. | 55 (8) (4368-4377)
aerosols , biomass burning emissions , elemental carbon , ice-core record , reactive gases , snow
Black carbon (BC) particles contribute to climate warming by heating the atmosphere and reducing the albedo of snow/ice surfaces. The available Arctic BC deposition records are restricted to the Atlantic and North American sectors, for which previous studies suggest considerable spatial differences in trends. Here, we present first long-term BC deposition and radiocarbon-based source apportionment data from Russia using four lake sediment records from western Arctic Russia, a region influenced by BC emissions from oil and gas production. The records consistently indicate increasing BC fluxes between 1800 and 2014. The radiocarbon analyses suggest mainly (similar to 70%) biomass sources for BC with fossil fuel contributions peaking around 1960-1990. Backward calculations with the atmospheric transport model FLEXPART show emission source areas and indicate that modeled BC deposition between 1900 and 1999 is largely driven by emission trends. Comparison of observed and modeled data suggests the need to update anthropogenic BC emission inventories for Russia, as these seem to underestimate Russian BC emissions and since 1980s potentially inaccurately portray their trend. Additionally, the observations may indicate underestimation of wildfire emissions in inventories. Reliable information on BC deposition trends and sources is essential for design of efficient and effective policies to limit climate warming.

Aerosol dynamics and dispersion of radioactive particles

von Schoenberg, P; Tunved, P; Grahn, H; Wiedensohler, A; Krejci, R; Brannstrom, N
2021 | Atmos. Chem. Phys. | 21 (6) (5173-5193)
In the event of a failure of a nuclear power plant with release of radioactive material into the atmosphere, dispersion modelling is used to understand how the released radioactivity is spread. For the dispersion of particles, Lagrangian particle dispersion models (LPDMs) are commonly used, in which model particles, representing the released material, are transported through the atmosphere. These model particles are usually inert and undergo only first-order processes such as dry deposition and simplified wet deposition along the path through the atmosphere. Aerosol dynamic processes including coagulation, condensational growth, chemical interactions, formation of new particles and interaction with new aerosol sources are usually neglected in such models. The objective of this study is to analyse the impact of these advanced aerosol dynamic processes if they were to be included in LPDM simulations for use in radioactive preparedness. In this investigation, a fictitious failure of a nuclear power plant is studied for three geographically and atmospherically different sites. The incident was simulated with a Lagrangian single-trajectory box model with a new simulation for each hour throughout a year to capture seasonal variability of meteorology and variation in the ambient aerosol. (a) We conclude that modelling of wet deposition by incorporating an advanced cloud parameterization is advisable, since it significantly influence simulated levels of airborne and deposited activity including radioactive hotspots, and (b) we show that inclusion of detailed ambient-aerosol dynamics can play a large role in the model result in simulations that adopt a more detailed representation of aerosol-cloud interactions. The results highlight a potential necessity for implementation of more detailed representation of general aerosol dynamic processes into LPDMs in order to cover the full range of possible environmental characteristics that can apply during a release of radionuclides into the atmosphere.

Contact information

Visiting addresses:

Geovetenskapens Hus,
Svante Arrhenius väg 8, Stockholm

Arrheniuslaboratoriet, Svante Arrhenius väg 16, Stockholm (Unit for Toxicological Chemistry)

Mailing address:
Department of Environmental Science
Stockholm University
106 91 Stockholm

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