High levels of tire wear particles in soils along low traffic roads

Traffic pollution has been linked to high levels of metals and organic contaminants in road-side soils, largely due to abrasion of tires, brake pads and the road surface. Although several studies have demonstrated correlations between different pollutants and various traffic variables, they mainly focused on roads with medium to high traffic density (>30,000 vehicles per day). In this study we have focused on investigating tire wear particles and road-related metals (zinc, copper, lead, chromium, nickel, and the metalloid arsenic) in the soils of low traffic roads in rural areas (650–14,250 vehicles per day). Different explanatory factors were investigated, such as traffic density, speed, % heavy vehicles, organic matter content, annual precipitation, soil types and roadside slope profiles. The results show high levels of tire wear particles, from 2000 to 26,400 mg/kg (0.2–2.6 % tire wear in d.w. soil), which is up to five times higher compared to previously reported values in roadside soils of high traffic density areas. A weak but significant correlation was found between tire wear particles, traffic speed and the annual precipitation. No significant relationship was found between tire wear particles metals. The concentrations of metals were comparable to previous studies of high traffic areas of Norway, as well as both urban and rural soils in other countries. For the metals, all factors together explained 45 % of the variation observed, with traffic density (11 %) and organic matter content (10 %) as the most important single variables. The analysis of tire wear particles in soils using Pyrolysis Gas chromatography Mass Spectrometry is challenging, and the results presented demonstrate the need for pretreatment to remove organic matter from the samples before analysis.High levels of tire wear particles in soils along low traffic roadspublishedVersio

High resolution modeling of aluminium transport in a fjord estuary with focus on mean circulation and irregular flow events

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Modeling key processes affecting Al speciation and transport in estuaries

Assessments of the impacts of aluminium (Al) to aquatic organisms in estuarine waters have suffered from the lack of available models that can accurately predict the presence of toxic physico-chemical forms (species) of Al at adequate spatial and temporal resolution. In the present work, transport and distribution of river-discharged Al species through changing environmental conditions in the Sandnesfjorden estuary, South-Eastern Norway, was predicted using a numerical model system at relatively high spatial (32 m × 32 m in horizontal) and temporal (1 h) resolution. New model code was implemented, including dynamic, salinity-dependent speciation and transformation processes, based on in situ measurements from several Norwegian estuaries as well as experimental data. This is the first time such elemental speciation code including LMM, colloidal, particle and sediment species is utilized in an estuary case in combination with high resolution hydrodynamics and compared to an extensive observational dataset. Good agreement was obtained between modeled and observed total and fractionated Al concentration at several stations along the fjord transect. Without including background contribution of Al from the coastal water, the model predicted too low Al concentrations (by up to approximately a factor 4) near the fjord mouth. The surface Al concentrations were also underestimated due to overestimated near-surface vertical mixing in the hydrodynamic model. The observed correlation between salinity and total Al concentration was well reproduced by the model in situations with low upper layer volume flux, typical under low river flow conditions. In contrast, the predicted surface salinity and total Al concentration were less correlated under high-flux conditions. As the general trends of Al concentrations and speciation were well reproduced, this study demonstrated that by including carefully chosen transfer rates, the model can be used to predict spatio-temporal distribution of total contamination as well as concentration levels of the elemental species.publishedVersio

Geochemical and morphological characterization of particles originating from tunnel construction

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Sensitivity of the green algae Chlamydomonas reinhardtii to gamma radiation: Photosynthetic performance and ROS formation

Embargo until December 06 2018.The aquatic environment is continuously exposed to ionizing radiation from both natural and anthropogenic sources, making the characterization of ecological and health risks associated with radiation of large importance. Microalgae represent the main source of biomass production in the aquatic ecosystem, thus becoming a highly relevant biological model to assess the impacts of gamma radiation. However, little information is available on the effects of gamma radiation on microalgal species, making environmental radioprotection of this group of species challenging. In this context, the present study aimed to improve the understanding of the effects and toxic mechanisms of gamma radiation in the unicellular green algae Chlamydomonas reinhardtii focusing on the activity of the photosynthetic apparatus and ROS formation. Algal cells were exposed to gamma radiation (0.49–1677 mGy/h) for 6 h and chlorophyll fluorescence parameters obtained by PAM fluorometry, while two fluorescent probes carboxy-H2DFFDA and DHR 123 were used for the quantification of ROS. The alterations seen in functional parameters of C. reinhardtii PSII after 6 h of exposure to gamma radiation showed modifications of PSII energy transfer associated with electron transport and energy dissipation pathways, especially at the higher dose rates used. Results also showed that gamma radiation induced ROS in a dose-dependent manner under both light and dark conditions. The observed decrease in photosynthetic efficiency seems to be connected to the formation of ROS and can potentially lead to oxidative stress and cellular damage in chloroplasts. To our knowledge, this is the first report on changes in several chlorophyll fluorescence parameters associated with photosynthetic performance and ROS formation in microalgae after exposure to gamma radiation.acceptedVersio

Long term effects of ionising radiation in the Chernobyl Exclusion zone on DNA integrity and chemical defence systems of Scots pine (Pinus sylvestris)

The Chernobyl Nuclear Power Plant (ChNPP) accident in 1986 resulted in extremely high levels of acute ionising radiation, that killed or damaged Scots pine (Pinus sylvestris) trees in the surrounding areas. Dead trees were cleared and buried, and new plantations established a few years later. Today, more than three decades later, gamma and beta-radiation near the ChNPP is still elevated compared with ambient levels but have decreased by a factor of 300 and 100, respectively. In the present work, Scots pine-trees growing at High (220 μGy h−1), Medium (11 μGy h−1), and Low (0.2 μGy h−1) total (internal + external) dose rates of chronically elevated ionising radiation in the Chernobyl Exclusion zone were investigated with respect to possible damage to DNA, cells and organelles, as well as potentially increased levels of phenolic and terpenoid antioxidants. Scots pine from the High and Medium radiation sites had elevated levels of DNA damage in shoot tips and needles as shown by the COMET assay, as well as increased numbers of resin ducts and subcellular abnormalities in needles. Needles from the High radiation site showed elevated levels of monoterpenes and condensed tannins compared with those from the other sites. In conclusion, more than three decades after the ChNPP accident substantial DNA damage and (sub)cellular effects, but also mobilisation of stress-protective substances possessing antioxidant activity were observed in Scots pine trees growing at elevated levels of ionising radiation. This demonstrates that the radiation levels in the Red Forest still significantly impact the plant community.publishedVersio

Ultraviolet B modulates gamma radiation-induced stress responses in Lemna minor at multiple levels of biological organisation

Elevated levels of ionizing and non-ionizing radiation may co-occur and pose cumulative hazards to biota. However, the combined effects and underlying toxicity mechanisms of different types of radiation in aquatic plants remain poorly understood. The present study aims to demonstrate how different combined toxicity prediction approaches can collectively characterise how chronic (7 days) exposure to ultraviolet B (UVB) radiation (0.5 W m−2) modulates gamma (γ) radiation (14.9, 19.5, 43.6 mGy h−1) induced stress responses in the macrophyte Lemna minor. A suite of bioassays was applied to quantify stress responses at multiple levels of biological organisation. The combined effects (no-enhancement, additivity, synergism, antagonism) were determined by two-way analysis of variance (2 W-ANOVA) and a modified Independent Action (IA) model. The toxicological responses and the potential causality between stressors were further visualised by a network of toxicity pathways. The results showed that γ-radiation or UVB alone induced oxidative stress and programmed cell death (PCD) as well as impaired oxidative phosphorylation (OXPHOS) and photosystem II (PSII) activity in L. minor. γ-radiation also activated antioxidant responses, DNA damage repair and chlorophyll metabolism, and inhibited growth at higher dose rates (≥20 mGy h−1). When co-exposed, UVB predominantly caused non-interaction (no-enhancement or additive) effects on γ-radiation-induced antioxidant gene expression, energy quenching in PSII and growth for all dose rates, whereas antagonistic effects were observed for lipid peroxidation, OXPHOS, PCD, oxidative stress, chlorophyll metabolism and genes involved in DNA damage responses. Synergistic effects were observed for changes in photochemical quenching and non-photochemical quenching, and up-regulation of antioxidant enzyme genes (GST) at one or more dose rates, while synergistic reproductive inhibition occurred at all three γ-radiation dose rates. The present study provides mechanistic knowledge, quantitative understanding and novel analytical strategies to decipher combined effects across levels of biological organisation, which should facilitate future cumulative hazard assessments of multiple stressors.publishedVersio