Defining the Scope of Exposome Studies and Research Needs from a Multidisciplinary Perspective

Zhang, P; Carlsten, C; Chaleckis, R; Hanhineva, K; Huang, MN; Isobe, T; Koistinen, VM; Meister, I; Papazian, S; Sdougkou, K; Xie, HY; Martin, JW; Rappaport, SM; Tsugawa, H; Walker, DI; Woodruff, TJ; Wright, RO; Wheelock, CE
2021 | Environ. Sci. Technol. Lett. | 8 (10) (839-852)
air pollution , cancer , dietary , disease , environment , exposure , high-resolution metabolomics , ion mobility spectrometry , mass spectrometry , mortality
The concept of the exposome was introduced over 15 years ago to reflect the important role that the environment exerts on health and disease. While originally viewed as a call-to-arms to develop more comprehensive exposure assessment methods applicable at the individual level and throughout the life course, the scope of the exposome has now expanded to include the associated biological response. In order to explore these concepts, a workshop was hosted by the Gunma University Initiative for Advanced Research (GIAR, Japan) to discuss the scope of exposomics from an international and multidisciplinary perspective. This Global Perspective is a summary of the discussions with emphasis on (1) top-down, bottom-up, and functional approaches to exposomics, (2) the need for integration and standardization of LC- and GC-based high-resolution mass spectrometry methods for untargeted exposome analyses, (3) the design of an exposomics study, (4) the requirement for open science workflows including mass spectral libraries and public databases, (5) the necessity for large investments in mass spectrometry infrastructure in order to sequence the exposome, and (6) the role of the exposome in precision medicine and nutrition to create personalized environmental exposure profiles. Recommendations are made on key issues to encourage continued advancement and cooperation in exposomics.

Ship- and island-based atmospheric soundings from the 2020 EUREC(4)A field campaign

Stephan, CC; Schnitt, S; Schulz, H; Bellenger, H; de Szoeke, SP; Acquistapace, C; Baier, K; Dauhut, T; Laxenaire, R; Morfa-Avalos, Y; Person, R; Melendez, EQ; Bagheri, G; Bock, T; Daley, A; Guttler, J; Helfer, KC; Los, SA; Neuberger, A; Rottenbacher, J; Raeke, A; Ringel, M; Ritschel, M; Sadoulet, P; Schirmacher, I; Stolla, MK; Wright, E; Charpentier, B; Doerenbecher, A; Wilson, R; Jansen, F; Kinne, S; Reverdin, G; Speich, S; Bony, S; Stevens, B
2021 | Earth Syst. Sci. Data | 13 (2) (491-514)
boundary layer , clouds , heat , mass , model , precipitation , sea-level , shallow cumulus , thermodynamic structure
To advance the understanding of the interplay among clouds, convection, and circulation, and its role in climate change, the Elucidating the role of clouds-circulation coupling in climate campaign (EUREC(4)A) and Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) collected measurements in the western tropical Atlantic during January and February 2020. Upper-air radiosondes were launched regularly (usually 4-hourly) from a network consisting of the Barbados Cloud Observatory (BCO) and four ships within 6-16 degrees N, 51-60 degrees W. From 8 January to 19 February, a total of 811 radiosondes measured wind, temperature, and relative humidity. In addition to the ascent, the descent was recorded for 82% of the soundings. The soundings sampled changes in atmospheric pressure, winds, lifting condensation level, boundary layer depth, and vertical distribution of moisture associated with different ocean surface conditions, synoptic variability, and mesoscale convective organization. Raw (Level 0), quality-controlled 1 s (Level 1), and vertically gridded (Level 2) data in NetCDF format (Stephan et al., 2020) are available to the public at AERIS (https://doi.org/10.25326/137). The methods of data collection and post-processing for the radiosonde data set are described here.

Guide to Semi-Quantitative Non-Targeted Screening Using LC/ESI/HRMS

Malm, L; Palm, E; Souihi, A; Plassmann, M; Liigand, J; Kruve, A
2021 | Molecules | 26 (12)
contaminants , decision making , electrospray-ionization , ion suppression , ionization , ionization efficiency scale , metabolomics data , mobile-phase , nts strategies , quantification , resolution-mass-spectrometry , system , waste-water
Non-targeted screening (NTS) with reversed phase liquid chromatography electrospray ionization high resolution mass spectrometry (LC/ESI/HRMS) is increasingly employed as an alternative to targeted analysis; however, it is not possible to quantify all compounds found in a sample with analytical standards. As an alternative, semi-quantification strategies are, or at least should be, used to estimate the concentrations of the unknown compounds before final decision making. All steps in the analytical chain, from sample preparation to ionization conditions and data processing can influence the signals obtained, and thus the estimated concentrations. Therefore, each step needs to be considered carefully. Generally, less is more when it comes to choosing sample preparation as well as chromatographic and ionization conditions in NTS. By combining the positive and negative ionization mode, the performance of NTS can be improved, since different compounds ionize better in one or the other mode. Furthermore, NTS gives opportunities for retrospective analysis. In this tutorial, strategies for semi-quantification are described, sources potentially decreasing the signals are identified and possibilities to improve NTS are discussed. Additionally, examples of retrospective analysis are presented. Finally, we present a checklist for carrying out semi-quantitative NTS.

Quantification and implication of measurement bias of ambient atmospheric BC concentration

Li, CL; Zhang, C; Kang, SC; Gustafsson, O
2021 | Atmos Environ | 249
ambient particle , black carbon , emission inventories , pm2.5
Black carbon (BC) aerosols have severe impacts on climate and health. Most atmospheric BC loadings are now predominantly reported for the PM2.5 size cut-off. Based on 39 published set of ambient BC concentrations from around the world where PM2.5 and PM10 were collected in parallel, we demonstrate that BC in PM2.5 was only around 80% of that in PM10. The implication is that around 20% of BC in the global ambient atmosphere is ignored with the now-legacy PM2.5 sampling approach. Correspondingly, BC of freshly emitted particles from combustion activities is dominantly reported in terms of PM2.5, and thus inflicting a bias in the total BC emission inventories. A consequence is that ambient BC is underpredicted when derived from models based on (PM2.5) emission inventories. This consideration contributes to reconcile existing systematic offset between model predictions and observation-based estimates of climate-relevant effects of anthropogenic BC aerosols. We propose that total ambient BC concentration should be considered rather than the PM2.5 portion to reduce the uncertainties in estimates of BC effects on the climate.

Methodological Advances to Study Contaminant Biotransformation: New Prospects for Understanding and Reducing Environmental Persistence?

Fenner, K; Elsner, M; Lueders, T; McLachlan, MS; Wackett, LP; Zimmermann, M; Drewes, JE
2021 | ACS ES&T Wat. | 1 (7) (1541-1554)
2,6-dichlorobenzamide bam , biodegradation , degradation , enzymes , identification , organic micropollutants , pathway , reductive dehalogenases , stable-isotope fractionation , transformation
Complex microbial communities in environmental systems play a key role in the detoxification of chemical contaminants by transforming them into less active metabolites or by complete mineralization. Biotransformation, i.e., transformation by microbes, is well understood for a number of priority pollutants, but a similar level of understanding is lacking for many emerging contaminants encountered at low concentrations and in complex mixtures across natural and engineered systems. Any advanced approaches aiming to reduce environmental exposure to such contaminants (e.g., novel engineered biological water treatment systems, design of readily degradable chemicals, or improved regulatory assessment strategies to determine contaminant persistence a priori) will depend on understanding the causal links among contaminant removal, the key driving agents of biotransformation at low concentrations (i.e., relevant microbes and their metabolic activities), and how their presence and activity depend on environmental conditions. In this Perspective, we present the current understanding and recent methodological advances that can help to identify such links, even in complex environmental microbiomes and for contaminants present at low concentrations in complex chemical mixtures. We discuss the ensuing insights into contaminant biotransformation across varying environments and conditions and ask how much closer we have come to designing improved approaches to reducing environmental exposure to contaminants.

Influence of Water Concentrations of Perfluoroalkyl Acids (PFAAs) on Their Size-Resolved Enrichment in Nascent Sea Spray Aerosols

Sha, B; Johansson, JH; Benskin, JP; Cousins, IT; Salter, ME
2021 | Environ. Sci. Technol. | 55 (14) (9489-9497)
adsorption , anionic surfactants , atmosphere , fate , fractionation , inventories , polyfluoroalkyl substances pfass , sulfonate , to-air transfer , transport
Perfluoroalkyl acids (PFAAs) are persistent organic substances that have been widely detected in the global oceans. Previous laboratory experiments have demonstrated effective enrichment of PFAAs in nascent sea spray aerosols (SSA), suggesting that SSA are an important source of PFAAs to the atmosphere. In the present study, the effects of the water concentration of PFAAs on their size-resolved enrichment in SSA were examined using a sea spray simulation chamber. Aerosolization of the target compounds in almost all sizes of SSA revealed a strong linear relationship with their water concentrations (p 0.9). The enrichment factors (EF) of the target compounds showed no correlation with their concentrations in the chamber water, despite the concentrations varying by a factor of 500 (similar to 0.3 to similar to 150 ng L-1). The particle surface-area-to-volume ratio appeared to be a key predictor of the enrichment of perfluoroalkyl carboxylic acids (PFCAs) with >= 7 perfluorinated carbons and perfluoroalkanesulfonic acids (PFSAs) with >= 6 perfluorinated carbons in supermicron particles (p 0.8), but not in submicron particles. The different enrichment behaviors of PFAAs in submicron and supermicron particles might be a result of the different production mechanisms of film droplets and jet droplets. The results suggest that the variability in seawater concentrations of PFAAs has little influence on EFs and that modeling studies designed to quantify the source of PFAAs via SSA emissions do not need to consider this factor.

Microalgal growth, nitrogen uptake and storage, and dissolved oxygen production in a polyculture based-open pond fed with municipal wastewater in northern Sweden

Lage, S; Toffolo, A; Gentili, FG
2021 | Chemosphere | 276
algae , biofuels , biomass production , cultivation , culture , dynamics , flue gases , microalgae , nitrogen , nutrient removal , nutrients removal , phosphorous , phosphorus removal , strains , temperature , wastewater
Microalgal-based wastewater treatment and CO2 sequestration from flue gases with subsequent biomass production represent a low-cost, eco-friendly, and effective procedure of removing nutrients and other pollutants from wastewater and assists in the decrease of greenhouse gas emissions. Thus, it supports a circular economy model. This is based on the ability of microalgae to utilise inorganic nutrients, mainly nitrogen and phosphorous, as well as organic and inorganic carbon, for their growth, and simultaneously reduce these substances in the water. However, the production of microalgae biomass under outdoor cultivation is dependent on several abiotic and biotic factors, which impact its profitability and sustainability. Thus, this study's goal was to evaluate the factors affecting the production of microalgae biomass on pilot-scale open raceway ponds under Northern Sweden's summer conditions with the help of a mathematical model. For this purpose, a microalgae consortium and a monoculture of Chlorella vulgaris were used to inoculate outdoor open raceway ponds. In line with the literature, higher biomass concentrations and nutrient removals were observed in ponds inoculated with the microalgae consortium. Our model, based on Droop's concept of macronutrient quotas inside the cell, corresponded well to the experimental data and, thus, can successfully be applied to predict biomass production, nitrogen uptake and storage, and dissolved oxygen production in microalgae consortia. (C) 2021 The Author(s). Published by Elsevier Ltd.

Defining the Scope of Exposome Studies and Research Needs from a Multidisciplinary Perspective

Zhang, P; Carlsten, C; Chaleckis, R; Hanhineva, K; Huang, MN; Isobe, T; Koistinen, VM; Meister, I; Papazian, S; Sdougkou, K; Xie, HY; Martin, JW; Rappaport, SM; Tsugawa, H; Walker, DI; Woodruff, TJ; Wright, RO; Wheelock, CE
2021 | Environ. Sci. Technol. Lett. | 8 (10) (839-852)
air pollution , cancer , dietary , disease , environment , exposure , high-resolution metabolomics , ion mobility spectrometry , mass spectrometry , mortality
The concept of the exposome was introduced over 15 years ago to reflect the important role that the environment exerts on health and disease. While originally viewed as a call-to-arms to develop more comprehensive exposure assessment methods applicable at the individual level and throughout the life course, the scope of the exposome has now expanded to include the associated biological response. In order to explore these concepts, a workshop was hosted by the Gunma University Initiative for Advanced Research (GIAR, Japan) to discuss the scope of exposomics from an international and multidisciplinary perspective. This Global Perspective is a summary of the discussions with emphasis on (1) top-down, bottom-up, and functional approaches to exposomics, (2) the need for integration and standardization of LC- and GC-based high-resolution mass spectrometry methods for untargeted exposome analyses, (3) the design of an exposomics study, (4) the requirement for open science workflows including mass spectral libraries and public databases, (5) the necessity for large investments in mass spectrometry infrastructure in order to sequence the exposome, and (6) the role of the exposome in precision medicine and nutrition to create personalized environmental exposure profiles. Recommendations are made on key issues to encourage continued advancement and cooperation in exposomics.

Can determination of extractable organofluorine (EOF) be standardized? First interlaboratory comparisons of EOF and fluorine mass balance in sludge and water matrices

Karrman, A; Yeung, LWY; Spaan, KM; Lange, FT; Nguyen, MA; Plassmann, M; De Wit, CA; Scheurer, M; Awad, R; Benskin, JP
2021 | Environ. Sci.-Process Impacts | 23 (10) (1458-1465)
combustion ion chromatography , organic fluorine , perfluoroalkyl substances , polyfluoroalkyl substances , precursors , samples
The high proportion of unidentified extractable organofluorine (EOF) observed globally in humans and the environment indicates widespread occurrence of unknown per- and polyfluoroalkyl substances (PFAS). However, efforts to standardize or assess the reproducibility of EOF methods are currently lacking. Here we present the first EOF interlaboratory comparison in water and sludge. Three participants (four organizations) analyzed unfortified and PFAS-fortified ultrapure water, two unfortified groundwater samples, unfortified wastewater treatment plant effluent and sludge, and an unfortified groundwater extract. Participants adopted common sample handling strategies and target lists for EOF mass balance but used in-house combustion ion-chromatography (CIC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. EOF accuracy ranged from 85-101% and 76-109% for the 60 and 334 ng L-1 fluorine (F) - fortified water samples, respectively, with between-laboratory variation of 9-19%, and within-laboratory variation of 3-27%. In unfortified sludge and aqueous samples, between-laboratory variation ranged from 21-37%. The contribution from sum concentrations of 16 individual PFAS ( n-ary sumation PFAS-16) to EOF ranged from 2.2-60% but extended analysis showed that other targets were prevalent, in particular ultra-short-chain perfluoroalkyl acids (e.g. trifluoroacetic acid) in aqueous samples and perfluoroalkyl acid-precursors (e.g. polyfluoroalkyl phosphate diesters) in sludge. The EOF-CIC method demonstrated promising accuracy, robustness and reporting limits but poor extraction efficiency was observed for some targets (e.g. trifluoroacetic acid).

The importance of Aitken mode aerosol particles for cloud sustenance in the summertime high Arctic – a simulation study supported by observational data

Bulatovic, I; Igel, AL; Leck, C; Heintzenberg, J; Riipinen, I; Ekman, AML
2021 | Atmos. Chem. Phys. | 21 (5) (3871-3897)
The potential importance of Aitken mode particles (diameters similar to 25-80 nm) for stratiform mixed-phase clouds in the summertime high Arctic (> 80 degrees N) has been investigated using two large-eddy simulation models. We find that, in both models, Aitken mode particles significantly affect the simulated microphysical and radiative properties of the cloud and can help sustain the cloud when accumulation mode concentrations are low (< 10-20 cm(-3)), even when the particles have low hygroscopicity (hygroscopicity parameter - kappa = 0.1). However, the influence of the Aitken mode decreases if the overall liquid water content of the cloud is low, either due to a higher ice fraction or due to low radiative cooling rates. An analysis of the simulated supersaturation (ss) statistics shows that the ss frequently reaches 0.5 % and sometimes even exceeds 1 %, which confirms that Aitken mode particles can be activated. The modelling results are in qualitative agreement with observations of the Hoppel minimum obtained from four different expeditions in the high Arctic. Our findings highlight the importance of better understanding Aitken mode particle formation, chemical properties and emissions, particularly in clean environments such as the high Arctic.

Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange

Osterwalder, S; Nerentorp, M; Zhu, W; Jiskra, M; Nilsson, E; Nilsson, MB; Rutgersson, A; Soerensen, AL; Sommar, J; Wallin, MB; Wangberg, I; Bishop, K
2021 | Global Biogeochem Cycles | 35 (8)
atmospheric mercury , baltic sea , coastal , eddy covariance , evasion , flux , fluxes , gas-exchange , rea , system , transfer velocities , transfer velocity , uptake , water , wind-speed
Air-sea exchange of gaseous elemental mercury (Hg-0) is not well constrained, even though it is a major component of the global Hg cycle. Lack of Hg-0 flux measurements to validate parameterizations of the Hg-0 transfer velocity contributes to this uncertainty. We measured the Hg-0 flux on the Baltic Sea coast using micrometeorological methods (gradient-based and relaxed eddy accumulation [REA]) and also simulated the flux with a gas exchange model. The coastal waters were typically supersaturated with Hg-0 (mean +/- 1 sigma = 13.5 +/- 3.5 ng m(-3); ca. 10% of total Hg) compared to the atmosphere (1.3 +/- 0.2 ng m(-3)). The Hg-0 flux calculated using the gas exchange model ranged from 0.1-1.3 ng m(-2) h(-1) (10th and 90th percentile) over the course of the campaign (May 10-June 20, 2017) and showed a distinct diel fluctuation. The mean coastal Hg-0 fluxes determined with the two gradient-based approaches and REA were 0.3, 0.5, and 0.6 ng m(-2) h(-1), respectively. In contrast, the mean open sea Hg-0 flux measured with REA was larger (6.3 ng m(-2) h(-1)). The open sea Hg-0 flux indicated a stronger wind speed dependence for the Hg-0 transfer velocity compared to commonly used parameterizations. Although based on a limited data set, we suggest that the wind speed dependence of the Hg-0 transfer velocity is more consistent with gases that have less water solubility than CO2 (e.g., O-2). These pioneering flux measurements using micrometeorological techniques show that more such measurements would improve our understanding of air-sea Hg exchange.

Biological Effects of Activated Carbon on Benthic Macroinvertebrates are Determined by Particle Size and Ingestibility of Activated Carbon

Ramo, RA; Honkanen, J; Nybom, I; Gunnarsson, JS
2021 | Environ. Toxicol. Chem. | 40 (12) (3465-3477)
activated carbon , adsorption , amendments , benthic macroinvertebrates , bioaccumulation , ecotoxicology , organic-matter , pcdd/f-contaminated sediments , polychlorinated biphenyls , polycyclic aromatic hydrocarbons , reduce pcb , sediment quality , sediment remediation , small-intestine , thin-layer capping , water
The application of activated carbon (AC) to the surface of contaminated sediments is a promising technology for sediment remediation in situ. Amendment with AC has proved to be effective in reducing bioavailability and sediment-to-water release of hydrophobic organic contaminants. However, AC may cause positive or negative biological responses in benthic organisms. The causes of these effects, which include changes in growth, reproduction, and mortality, are unclear but are thought to be related to the size of AC particles. The present study investigated biological response to AC ranging from ingestible powdered AC to noningestible granular AC in two benthic deposit feeders: the polychaete Marenzelleria spp. and the clam Limecola balthica (syn. Macoma balthica). In the polychaete, exposure to powdered AC (ingestible) reduced both dry weight and carbon assimilation, whereas exposure to granular AC (noningestible) increased both dry weight and carbon assimilation. Responses in the clam were similar but less pronounced, indicating that response levels are species-specific and may vary within a benthic community. In addition, worms exposed to the finest ingestible AC particles had reduced gut microvilli length and reduced gut lumen, indicating starvation. These results strongly suggest that biological responses to AC depend on particle ingestibility, whereby exposure to ingestible particles may cause starvation through reduced bioavailability of food coingested with AC or due to rejection of AC-treated sediment as a food source. Environ Toxicol Chem 2021;00:1-13. (c) 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

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Stockholm University
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