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.

Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

Wagner, R; Ickes, L; Bertram, AK; Els, N; Gorokhova, E; Mohler, O; Murray, BJ; Umo, NS; Salter, ME
2021 | Atmos. Chem. Phys. | 21 (18) (13903-13930)
cloud , coastal , fjord , glassy aerosols , kongsfjorden , nuclei , ocean , phase , spray aerosol , water-uptake
Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea spray aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5 x 10(10) m(-2) at an ice saturation ratio of 1.3. Much smaller densities in the range of 10(8)-10(9) m(-2) were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are 2 orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the number of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how instrumental parameters like the aerosolisation method and the ice nucleation measurement technique might affect the comparability of the results amongst different studies.

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.

Revisiting old lessons from classic literature on persistent global pollutants This article belongs to Ambio’s 50th Anniversary Collection. Theme: Environmental contaminants

2021 | Ambio | 50 (3) (534-538)
chemical regulation , environmental contaminants , mercury , persistent , polychlorinated
Looking back 50 years at classic literature was a reminder of inspiring discoveries and clever theories that were formative to the field of environmental chemistry, but also of the irreparable costs that persistent global pollutants have had on ecosystems and human society. In my view, these three papers have greatly impacted contemporary science and influenced development of policies that have limited the spread of hazardous contaminants. At the same time, a sobering reality is that reversing decades of past pollution has proven impossible in our lifetime, and global trends are dire for both legacy and emerging contaminants. Lessons in these papers are clear to most environmental scientists, but I argue have not resulted in adequate investment in infrastructure or manpower to enable systematic unbiased searching for pollutants as proposed by Soren Jensen in 1972. Acknowledging that the costs of new global contaminants will be too high, we must incentivize safer chemicals and their sustainable use, increase international exchange of lists of chemicals in commerce, and coordinate international efforts in nontarget screening to identify new contaminants before they circulate the world.

The effect of reduction measures on concentrations of hazardous semivolatile organic compounds in indoor air and dust of Swedish preschools

Langer, S; de Wit, CA; Giovanoulis, G; Faldt, J; Karlson, L
2021 | Indoor Air | 31 (5) (1673-1682)
article substitution , exposure , indoor air , new construction , renovation , settled dust
Young children spend a substantial part of their waking time in preschools. It is therefore important to reduce the load of hazardous semivolatile organic compounds (SVOCs) in the preschools' indoor environment. The presence and levels of five SVOC groups were evaluated (1) in a newly built preschool, (2) before and after renovation of a preschool, and (3) in a preschool where SVOC-containing articles were removed. The new building and the renovation were performed using construction materials that were approved with respect to content of restricted chemicals. SVOC substance groups were measured in indoor air and settled dust and included phthalates and alternative plasticizers, organophosphate esters (OPEs), brominated flame retardants, and bisphenols. The most abundant substance groups in both indoor air and dust were phthalates and alternative plasticizers and OPEs. SVOC concentrations were lower or of the same order of magnitude as those reported in comparable studies. The relative Cumulative Hazard Quotient (HQ(cum)) was used to assess the effects of the different reduction measures on children's SVOC exposure from indoor air and dust in the preschools. HQ(cum) values were low (1.0-6.1%) in all three preschools and decreased further after renovation and article substitution. The SVOCs concentrations decreased significantly more in the preschool renovated with the approved building materials than in the preschool where the SVOC-containing articles were removed.

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.

How Copepods Can Eat Toxins Without Getting Sick: Gut Bacteria Help Zooplankton to Feed in Cyanobacteria Blooms

Gorokhova, E; El-Shehawy, R; Lehtiniemi, M; Garbaras, A
2021 | Front. Microbiol. | 11
baltic sea , biodegradation , community structure , copepods , daphnia , degradation , diversity , enzymatic pathway , grazing , growth , hepatotoxins , microcystin , microcystin-lr , mlra gene , nodularia-spumigena , nodularin , rna
Toxin-producing cyanobacteria can be harmful to aquatic biota, although some grazers utilize them with often beneficial effects on their growth and reproduction. It is commonly assumed that gut microbiota facilitates host adaptation to the diet; however, the evidence for adaptation mechanisms is scarce. Here, we investigated the abundance of mlrA genes in the gut of the Baltic copepods Acartia bifilosa and Eurytemora affinis during cyanobacteria bloom season (August) and outside it (February). The mlrA genes are unique to microcystin and nodularin degraders, thus indicating the capacity to break down these toxins by the microbiota. The mlrA genes were expressed in the copepod gut year-round, being >10-fold higher in the summer than in the winter populations. Moreover, they were significantly more abundant in Eurytemora than Acartia. To understand the ecological implications of this variability, we conducted feeding experiments using summer- and winter-collected copepods to examine if/how the mlrA abundance in the microbiota affect: (1) uptake of toxic Nodularia spumigena, (2) uptake of a non-toxic algal food offered in mixtures with N. spumigena, and (3) concomitant growth potential in the copepods. The findings provide empirical evidence that the occurrence of mlrA genes in the copepod microbiome facilitates nutrient uptake and growth when feeding on phytoplankton mixtures containing nodularin-producing cyanobacteria; thus, providing an adaptation mechanism to the cyanobacteria blooms.

Emerging per- and polyfluoroalkyl substances (PFAS) in human milk from Sweden and China (vol 22, pg 2023, 2020)

Awad, R; Zhou, YH; Nyberg, E; Namazkar, S; Wu, YN; Xiao, QF; Sun, YJ; Zhu, ZL; Bergman, A; Benskin, JP
2021 | Environ. Sci.-Process Impacts | 23 (1) (188-188)

Chemical profiling of the Arctic sea lettuce Ulva lactuca (Chlorophyta) mass-cultivated on land under controlled conditions for food applications (vol 341, 127999, 2021)

Roleda, MY; Lage, S; Aluwini, DF; Rebours, C; Brurberg, MB; Nitschke, U; Gentili, FG
2021 | Food Chem | 347

The presence of selected UV filters in a freshwater recreational reservoir and fate in controlled experiments

O'Malley, E; McLachlan, MS; O'Brien, JW; Verhagen, R; Mueller, JF
2021 | Sci. Total Environ. | 754
benzophenone-3 , degradation , environmental half-life , personal care products , sunscreen agents
UV filters present in sunscreen and other cosmetics are directly released into the environment during aquatic recreational activities. The extent to which the wide range of UV filters pose a risk to the environment remains unclear. This study investigated the occurrence and dissipation of selected organic UV filters at a recreational site (Enoggera Reservoir, Queensland, Australia) over 12 h. Furthermore, different possible degradation processes were investigated in a controlled off-site experiment with surface water exposed to natural light. Half-lives were estimated for ten UV filters. In Enoggera Reservoir, seven UV filters were detected, of which the most prevalent were octocrylene, avobenzone (BMDBM) and enzacamene (4-MBC). Summed concentrations of the seven UV filters ranged from 7330 ng L-1 at 13:00 h to 2550 ng L-1 at 21:00 h. In the degradation experiment, four UV filters showed no significant change over time. The fate of these compounds in the environment is likely to be mainly influenced by dispersion. Half-lives of the remaining UV filters were 6.6 h for amiloxate (IMC), 20 h for benzophenone 1, 23 h for octinoxate (EHMC), 30 h for 3-benzylidene camphor, 34 h for 4-MBC and 140 h for dioxybenzone (BP8). The degree of susceptibility to photodegradation and biodegradation was generally consistent within a structural class. The fate and half-lives of UV filters are variable and should be considered on a per site basis when assessing environmental risk. (C) 2020 Elsevier B.V. All rights reserved.

A Review of Dietary Intake of Acrylamide in Humans

Timmermann, CAG; Molck, SS; Kadawathagedara, M; Bjerregaard, AA; Tornqvist, M; Brantsaeter, AL; Pedersen, M
2021 | Toxics | 9 (7)
acrylamide , baby food , breast-cancer , child cohort , children , colorectal-cancer , diet , epidemiological studies , food frequency questionnaire , hemoglobin adduct levels , humans , model system , norwegian mother , pancreatic-cancer risk , renal-cell , surveys and questionnaires
The dietary intake of acrylamide (AA) is a health concern, and food is being monitored worldwide, but the extent of AA exposure from the diet is uncertain. The aim of this review was to provide an overview of estimated dietary intake. We performed a PubMed search identifying studies that used dietary questionnaires and recalls to estimate total dietary AA intake. A total of 101 studies were included, corresponding to 68 original study populations from 26 countries. Questionnaires were used in 57 studies, dietary recalls were used in 33 studies, and 11 studies used both methods. The estimated median AA intake ranged from 0.02 to 1.53 mu g/kg body weight/day between studies. Children were represented in 25 studies, and the body-weight-adjusted estimated AA intake was up to three times higher for children than adults. The majority of studies were from Europe (n = 65), Asia (n = 17), and the USA (n = 12). Studies from Asia generally estimated lower intakes than studies from Europe and the USA. Differences in methods undermine direct comparison across studies. The assessment of AA intake through dietary questionnaires and recalls has limitations. The integration of these methods with the analysis of validated biomarkers of exposure/internal dose would improve the accuracy of dietary AA intake exposure estimation. This overview shows that AA exposure is widespread and the large variation across and within populations shows a potential for reduced intake among those with the highest exposure.

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