Weathering Plastics as a Planetary Boundary Threat: Exposure, Fate, and Hazards

Arp, HPH; Kuhnel, D; Rummel, C; MacLeod, M; Potthoff, A; Reichelt, S; Rojo-Nieto, E; Schmitt-Jansen, M; Sonnenberg, J; Toorman, E; Jahnke, A
2021 | Environ. Sci. Technol. | 55 (11) (7246-7255)
debris , degradation , density polyethylene , environmental plastics , environments , exposure , fate , fragmentation , hazards , marine , microplastic particles , planetary boundary threat , polystyrene , transport , water , weathering
We described in 2017 how weathering plastic litter in the marine environment fulfils two of three criteria to impose a planetary boundary threat related to "chemical pollution and the release of novel entities": (1) planetary-scale exposure, which (2) is not readily reversible. Whether marine plastics meet the third criterion, (3) eliciting a disruptive impact on vital earth system processes, was uncertain. Since then, several important discoveries have been made to motivate a re-evaluation. A key issue is if weathering macroplastics, microplastics, nanoplastics, and their leachates have an inherently higher potential to elicit adverse effects than natural particles of the same size. We summarize novel findings related to weathering plastic in the context of the planetary boundary threat criteria that demonstrate (1) increasing exposure, (2) fate processes leading to poorly reversible pollution, and (3) (eco)toxicological hazards and their thresholds. We provide evidence that the third criterion could be fulfilled for weathering plastics in sensitive environments and therefore conclude that weathering plastics pose a planetary boundary threat. We suggest future research priorities to better understand (eco)toxicological hazards modulated by increasing exposure and continuous weathering processes, to better parametrize the planetary boundary threshold for plastic pollution.

Perfluoroalkyl Substances in the Western Tropical Atlantic Ocean

Miranda, DD; Leonel, J; Benskin, JP; Johansson, J; Hatje, V
2021 | Environ. Sci. Technol. | 55 (20) (13749-13758)
cabo frio , deep-water , geotraces , labrador sea , perfluorinated acids , perfluorooctanoic acid (pfoa) , pfaas , polyfluoroalkyl substances , pops , south-atlantic , sulfluramid use , surface water , tropical atlantic ocean , upwelling , upwelling system
The dispersion of perfluoroalkyl substances (PFAS) in surface and deep-water profiles (down to 5845 m deep) was evaluated through the Western Tropical Atlantic Ocean (TAO) between 15 degrees N and 23 degrees S. The sum concentrations for eight quantifiable PFAS (Sigma(8)PFAS) in surface waters ranged from 11 to 69 pg/L, which is lower than previously reported in the same area as well as in higher latitudes. Perfluoroalkyl carboxylic acids (PFCAs) were the predominant PFASs present in the Western TAO. The 16 surface samples showed variable PFAS distributions, with the predominance of perfluorooctanoic acid (PFOA) along the transect (67%; 11 +/- 8 pg/L) and detection of perfluoroalkyl sulfonic acids (PFSAs) only in the Southern TAO. Perfluoroheptanoic acid (PFHpA) was often detected in the vertical profiles. PFAS distribution patterns (i.e., profiles and concentrations) varied with depth throughout the TAO latitudinal sectors (North, Equator, South Atlantic, and in the Brazilian coastal zone). Vertical profiles in coastal samples displayed decreasing PFAS concentrations with increasing depth, whereas offshore samples displayed higher PFAS detection frequencies in the intermediate water masses. Together with the surface currents and coastal upwelling, the origin of the water masses was an important factor in explaining PFAS concentrations and profiles in the TAO.

Understanding Biofilm Formation in Ecotoxicological Assays With Natural and Anthropogenic Particulates

Gorokhova, E; Motiei, A; El-Shehawy, R
2021 | Front. Microbiol. | 12
actinobacteria , bacteria , bacterial assemblages on microplastic , balos , daphnia , daphnia-magna , diverse , ecotoxicological testing , microbiome , nov. , particle aggregation , plastic debris , predation , resistance , sediments , size distribution , suspended clay , zooplankton
Fossil-made polymers harbor unique bacterial assemblages, and concerns have been raised that ingested microplastic may affect the consumer gut microbiota and spread pathogens in animal populations. We hypothesized that in an ecotoxicity assay with a mixture of polystyrene (PS) and clay: (1) microbiome of the test animals inoculates the system with bacteria; (2) relative contribution of PS and the total amount of suspended solids (SS) select for specific bacterial communities; and (3) particle aggregation is affected by biofilm community composition, with concomitant effects on the animal survival. Mixtures of PS and clay at different concentrations of SS (10, 100, and 1000 mg/L) with a varying microplastics contribution (%PS; 0-80%) were incubated with Daphnia magna, whose microbiome served as an inoculum for the biofilms during the exposure. After 4-days of exposure, we examined the biofilm communities by 16S rRNA gene sequencing, particle size distribution, and animal survival. The biofilm communities were significantly different from the Daphnia microbiota used to inoculate the system, with an overrepresentation of predatory, rare, and potentially pathogenic taxa in the biofilms. The biofilm diversity was stimulated by %PS and decreased by predatory bacteria. Particle aggregate size and the biofilm composition were the primary drivers of animal survival, with small particles and predatory bacteria associated with a higher death rate. Thus, in effect studies with solid waste materials, ecological interactions in the biofilm can affect particle aggregation and support potentially harmful microorganisms with concomitant effects on the test animals.

Evaluating reliability and risk of bias of in vivo animal data for risk assessment of chemicals – Exploring the use of the SciRAP tool in a systematic review context

Waspe, J; Bui, T; Dishaw, L; Kraft, A; Luke, A; Beronius, A
2021 | Environ Int | 146
environmental-health science , guidance , iris , methodology , ohat , randomized controlled-trials , reliability , reporting quality , risk of bias , scales , scirap , systematic review , toxrtool , weight
Within the field of health risk assessment, it is essential that evaluations of reliability or validity of toxicity data are conducted with structure and transparency. To this end, different tools for evaluating toxicity studies have been developed by different groups and organizations, for different specific purposes. The Science in Risk Assessment and Policy (SciRAP) tool was developed for use in the regulatory health risk assessment of chemicals and to promote structured and transparent evaluation of study reliability within European regulatory frameworks. As such, the SciRAP tool is not specifically tailored for use in a systematic review context. However, in light of the current movement towards applying systematic review in the field of environmental health and chemical assessments and European chemicals regulation, we were interested in exploring how SciRAP could be applied in such a context. To achieve this, the scope of the SciRAP tool was first compared to two tools developed based on systematic review principles at the US Environmental Protection Agency's IRIS program and the National Toxicology Program's Office of Health Assessment and Translation (OHAT). Next, the SciRAP and IRIS tools were both applied in a case study to evaluate the same nine in vivo animal studies and the resulting evaluations were compared. The SciRAP tool was found to address the majority of the elements included for study evaluation in the OHAT and IRIS tools. In the case study, no major differences were found in the conclusions drawn when using SciRAP or IRIS tools. However, future developments to bring the SciRAP tool more in line with systematic review principles were identified and are discussed. Overall, this work illustrates the advantages of applying structured and pre-defined methods for study evaluation and provides a unique case study comparing the impact of using different tools for evaluating animal toxicity studies.

Transformation of organic micropollutants along hyporheic flow in bedforms of river-simulating flumes

Jaeger, A; Posselt, M; Schaper, JL; Betterle, A; Rutere, C; Coll, C; Mechelke, J; Raza, M; Meinikmann, K; Portmann, A; Blaen, PJ; Horn, MA; Krause, S; Lewandowski, J
2021 | Sci Rep | 11 (1)
attenuation , biotransformation , denitrification , ecology , exchange , fate , identification , pharmaceuticals , products , zone
Urban streams receive increasing loads of organic micropollutants from treated wastewaters. A comprehensive understanding of the in-stream fate of micropollutants is thus of high interest for water quality management. Bedforms induce pumping effects considerably contributing to whole stream hyporheic exchange and are hotspots of biogeochemical turnover processes. However, little is known about the transformation of micropollutants in such structures. In the present study, we set up recirculating flumes to examine the transformation of a set of micropollutants along single flowpaths in two triangular bedforms. We sampled porewater from four locations in the bedforms over 78 days and analysed the resulting concentration curves using the results of a hydrodynamic model in combination with a reactive transport model accounting for advection, dispersion, first-order removal and retardation. The four porewater sampling locations were positioned on individual flowpaths with median solute travel times ranging from 11.5 to 43.3 h as shown in a hydrodynamic model previously. Highest stability was estimated for hydrochlorothiazide on all flowpaths. Lowest detectable half-lives were estimated for sotalol (0.7 h) and sitagliptin (0.2 h) along the shortest flowpath. Also, venlafaxine, acesulfame, bezafibrate, irbesartan, valsartan, ibuprofen and naproxen displayed lower half-lives at shorter flowpaths in the first bedform. However, the behavior of many compounds in the second bedform deviated from expectations, where particularly transformation products, e.g. valsartan acid, showed high concentrations. Flowpath-specific behavior as observed for metformin or flume-specific behavior as observed for metoprolol acid, for instance, was attributed to potential small-scale or flume-scale heterogeneity of microbial community compositions, respectively. The results of the study indicate that the shallow hyporheic flow field and the small-scale heterogeneity of the microbial community are major controlling factors for the transformation of relevant micropollutants in river sediments.

Competitive interactions as a mechanism for chemical diversity maintenance in Nodularia spumigena

Lage, S; Mazur-Marzec, H; Gorokhova, E
2021 | Sci Rep | 11 (1)
allelopathy , baltic sea cyanobacteria , biological role , bloom , cylindrospermopsis-raciborskii , evolution , growth , limited microcystis-aeruginosa , nonribosomal peptides , phytoplankton
Nodularia spumigena is a bloom-forming diazotrophic cyanobacterium inhabiting brackish waters worldwide. This species produces non-ribosomal peptides (NRPs), including the hepatotoxin nodularin, often referred to as cyanotoxin. Several known classes of NRPs have various biological activities, although their modes of action are poorly understood. In the Baltic N. spumigena, there is a high NRP chemodiversity among strains, allowing their grouping in specific chemotypes and subgroups. Therefore, it is relevant to ask whether the NRP production is affected by intraspecific interactions between the co-existing strains. Using a novel approach that combines culture technique and liquid chromatography-tandem mass spectrometry for the NRP analysis, we examined N. spumigena strains under mono- and co-culture conditions. The test strains were selected to represent N. spumigena belonging to the same or different chemotype subgroups. In this setup, we observed physiological and metabolic responses in the test strains grown without cell contact. The changes in NRP levels to co-culture conditions were conserved within a chemotype subgroup but different between the subgroups. Our results suggest that intraspecific interactions may promote a chemical diversity in N. spumigena population, with higher NRP production compared to a single-strain population. Studying allelochemical signalling in this cyanobacterium is crucial for understanding toxicity mechanisms and plankton community interactions in the Baltic Sea and other aquatic systems experiencing regular blooms.

Lidar observation of aerosol transformation in the atmospheric boundary layer above the Baltic Sea

Makuch, P; Sitarek, S; Markuszewski, P; Petelski, T; Stacewicz, T
2021 | Oceanologia | 63 (2) (238-246)
aerosol , atmospheric boundary layer , lidars measurements
Investigation results of a coarse and accumulation mode of aerosol properties above the Baltic Sea are reported. A most important role in the direct aerosol effect on climate have aerosols from the group of coarse and accumulation mode particles. Overseas in the atmosphere, there is a lot of aerosols from the fine fraction but their impact is not so important as coarse and accumulation mode particles. Sea spray emission from the sea surface takes place over a wide range of aerosol particle size distribution, it is also large in size range which are studying in this work (Lewis and Schwartz, 2004). The discussed range is most important in view of atmospheric optical properties, smaller particles do not have such an influence on scattering as particles from range 0.5-2 mu m. The research was performed with a multiwavelength lidar. Due to the application of special software, the aerosol particle size distributions were retrieved from the lidar returns. That provided an opportunity to determine the profiles of the aerosol effective radius. We showed that the aerosol properties depend mainly on the direction of the air mass advection and the wind speed. The impact of the Baltic Sea on the aerosol size distribution is huge in the case of the advection from the open sea. Moreover, the aerosol effective radiuses in the whole boundary layer are much larger in the case of strong than for light wind. Our results suggest that the aerosol flux and the aerosol particle size distribution should be related to the wind speed in the emission function. (C) 2021 Institute of Oceanology of the Polish Academy of Sciences. Production and hosting by Elsevier B.V.

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

Zhao, FY; Riipinen, I; MacLeod, M
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.

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

Press enquiries should be directed to:

Stella Papadopoulou
Science Communicator
Phone +46 (0)8 674 70 11
stella.papadopoulou@aces.su.se