Black carbon (BC) as the main component of pollutants in the Arctic plays an important role on regional climate change. In this study, we applied the regional climate-chemistry model, WRF-Chem, to investigate the spatial distribution, transportation, and impact factors of BC in the Arctic. Compared with reanalysis data and observations, the WRF-Chem performed well in terms of the seasonal variations of meteorological parameters and BC concentrations, indicating the applicability of this model on Arctic BC simulation works. Our results showed that the BC concentrations in the Arctic had an obviously seasonalvariation pattern. Surface BC concentrations peaked during winter and spring seasons, while the minimum occurred during summer and autumn seasons. For the vertical distribution, BC aerosols mainly concentrated in the Arctic lower troposphere, and most of BC distributed near the surface during winter and spring seasons and in the higher altitude during other seasons. The seasonality of BC was associated with the seasonal change of meteorological field. During winter, the significant northward airflow prevailing in northern Eurasia caused the transport of accumulated pollutants from this region into the Arctic. The similar but weakened northward airflow pattern and the anticyclone activity during spring can allow pollutants to be transported to the Arctic lower troposphere. Moreover, the more stable atmosphere during winter and spring seasons made BC accumulated mainly near the surface. During summer and autumn seasons, the less stable boundary layer and the cyclone activity in the Arctic facilitated the diffusion of pollutants into the higher altitude. Meanwhile, the higher relative humidity can promote the wet removal process and lead to the relatively lower BC concentrations near the surface. Compared with the seasonal change of emission, our analysis showed that the seasonal variation of meteorological field was the main contributor for the seasonality of BC in the Arctic.

The ongoing transition to renewable fuel sources has led to increased use of wood and other biomass fuels. The physiochemical characteristics of biomass combustion derived aerosols depends on appliances, fuel and operation procedures, and particles generated during incomplete combustion are linked to toxicity. Frequent indoor wood burning is related to severe health problems such as negative effects on airways and inflammation, as well as chronic hypoxia and pathological changes in placentas, adverse pregnancy outcome, preterm delivery and increased risk of preeclampsia. The presence of combustion-derived black carbon particles at both the maternal and fetal side of placentas suggests that particles can reach the fetus. Air pollution particles have also been shown to inhibit trophoblast migration and invasion, which are vital functions for the development of the placenta during the first trimester. In this study we exposed a placental first trimester trophoblast cell line to wood smoke particles emitted under Nominal Burn rate (NB) or High Burn rate (HB). The particles were visible inside exposed cells and localized to the mitochondria, causing ultrastructural changes in mitochondria and endoplasmic reticulum. Exposed cells showed decreased secretion of the pregnancy marker human chorionic gonadotropin, increased secretion of IL-6, disrupted membrane integrity, disrupted proliferation and contained specific polycyclic aromatic hydrocarbons (PAHs) from the particles. Taken together, these results suggest that wood smoke particles can enter trophoblasts and have detrimental effects early in pregnancy by disrupting critical trophoblast functions needed for normal placenta development and function. This could contribute to the underlying mechanisms leading to pregnancy complications such as miscarriage, premature birth, preeclampsia and/or fetal growth restriction. This study support the general recommendation that more efficient combustion technologies and burning practices should be adopted to reduce some of the toxicity generated during wood burning.

The severe and pervasive effects of multispecies foodborne microbial biofilms highlight the importance of rapid detection and diagnosis of contamination risk in the field using epifluorescence-based techniques (EBT) combined with automatic image-counting software. This study screened the hygiene quality of the environment, the carcass and the slaughtering equipment in the El-Kharga abattoir, New Valley Province, Egypt, to assess possible contamination during slaughter process. In addition, biofilm was assessed, and bacteria was enumerated by epifluorescence microscopy. Using both conventional and EBT, the highest bacterial counts were observed for the slaughtering equipment (6.6 and 5.2 cfu/cm2, respectively), followed by different parts of the carcass (4.1 and 4.4 cfu/cm2, respectively) and environmental samples (3.9 and 4.1 cfu/cm2, respectively). A high prevalence of E. coli O157:H7 was observed on the slaughtering equipment (25%), which also led to carcass (1%) contamination. Moreover, Enterobacteriaceae members were detected during examination, such as Klebsiella pneumoniae, Enterobacter aerogenes, and Raoultella ornithinolytica. Despite the relatively good hygiene quality of the abattoir environment, there is also a high risk associated with biofilm formation by pathogenic microorganisms on the slaughtering equipment. Moreover, EBT showed different structures of the biofilm, including those formed at different maturation stages, such as voids, microbubbles, channels and mushroom shapes. (EBT) microscopy combined with image-counting software could be a candidate substitute to estimate efficiently, precisely and rapidly the microbial aggregation and exposure risk in field than the conventional counting techniques.

Continuous measurements of Black Carbon (BC) aerosol mass concentrations were carried at Dehradun (30.33°N, 78.04°E, 700 m amsl), a semi-urban site in the foothills of north-westHimalayas, India during January 2011–December 2017. We reported both the BC seasonal variations as well as mass concentrations from fossil fuel combustion (BCff) and biomass burning (BCbb) sources. Annual mean BC exhibited a strong seasonal variability with maxima during winter (4.86 ± 0.78 μg m⁻³) followed by autumn (4.18 ± 0.54 μg m⁻³), spring (3.93 ± 0.75 μg m⁻³) and minima during summer (2.41 ± 0.66 μg m⁻³). Annual averaged BC mass concentrations were 3.85 ± 1.16 μg m⁻³ varying from 3.29 to 4.37 μg m⁻³ whereas BCff and BCbb ranged from 0.11 to 7.12 μg m⁻³ and 0.13–3.6 μg m⁻³. The percentage contributions from BCff and BCbb to total BC are 66% and 34% respectively, indicating relatively higher contribution from biomass burning as compared to other locations in India. This is explained using potential source contribution function (PSCF) and concentration weighted trajectories (CWT) analysis which reveals the potential sources of BC originating from the north-west and eastern parts of IGP and the western part of the Himalayas that are mostly crop residue burning and forest fire regions in India. The annual mean ARF at top-of-atmosphere (TOA), at surface (SUR), and within the atmosphere (ATM) were found to be −14.84 Wm⁻², −43.41 Wm⁻², and +28.57 Wm⁻² respectively. To understand the impact of columnar aerosol burden on ARF, the radiative forcing efficiency (ARFE) was estimated and averaged values were −31.81, −91.63 and 59.82 Wm⁻² τ⁻¹ for TOA, SUR and ATM respectively. The high ARFE within the atmosphere indicates the dominance of absorbing aerosol (BC and dust) over Northwest Himalayas.

Polycyclic aromatic compounds (PACs) are ubiquitous in the environment. Wildlife (including fish) are chronically exposed to PACs through air, water, sediment, soil, and/or dietary routes. Exposures are highest near industrial or urban sites, such as aluminum smelters and oil sands mines, or near natural sources such as forest fires. This review assesses the exposure and toxicity of PACs to wildlife, with a focus on the Canadian environment. Most published field studies measured PAC concentrations in tissues of invertebrates, fish, and birds, with fewer studies of amphibians and mammals. In general, PAC concentrations measured in Canadian wildlife tissues were under the benzo[a]pyrene (BaP) guideline for human consumption. Health effects of PAC exposure include embryotoxicity, deformities, cardiotoxicity, DNA damage, changes to DNA methylation, oxidative stress, endocrine disruption, and impaired reproduction. Much of the toxicity of PACs can be attributed to their bioavailability, and the extent to which certain PACs are transformed into more toxic metabolites by cytochrome P450 enzymes. As most mechanistic studies are limited to individual polycyclic aromatic hydrocarbons (PAHs), particularly BaP, research on other PACs and PAC-containing complex mixtures is required to understand the environmental significance of PAC exposure and toxicity. Additional work on responses to PACs in amphibians, reptiles, and semi-aquatic mammals, and development of molecular markers for early detection of biological responses to PACs would provide a stronger biological and ecological justification for regulating PAC emissions to protect Canadian wildlife.

Internal release of nutrients is an important contributor to the nutrient dynamics in shallow eutrophic lakes. Zoobenthic organisms may contribute to this release by excreting nutrients to the overlaying water. Based on experiments and using results from previous experimental studies as well as field monitoring density data from 2007 to 2017, we calculated the annual and seasonal nutrient excretions of the two most common macroinvertebrates (Corbicula fluminea and Limnodrilus hoffmeisteri) in Lake Taihu, China. We compared these rates with the concentrations of NH₄–N, total nitrogen (TN), PO₄–P and total phosphorus (TP) in the lake water as well as with previous results of release rates from undisturbed sediments collected in the lake. The spatial distribution of nutrient excretion by the two invertebrate species varied markedly among sites and years. Regression analyses revealed significant relationships between total nutrient excretions by these two species and the concentrations of NH₄–N, TN, PO₄–P and TP in the lake, but with seasonal differences. The relationship was overall strongest in winter, followed by spring, and weakest in summer and autumn. The flux of NH₄–N and PO₄–P released by the two macroinvertebrate species were equivalent to as much as 50% and 66%, respectively, of the sediment release recorded in lab experiments under undisturbed conditions; however, the percentages would be somewhat lower under field conditions where the sediment is subjected to frequent wind-induced resuspension and fish disturbance, enhancing the release rates. The release declined during the study period due to a reduction in the density of macroinvertebrates, perhaps indicating increasing stocking of fish since 2007. Our results indicate that benthic invertebrates are important contributor to the internal loading in shallow eutrophic lakes.

The biodegradation of polychlorinated biphenyls (PCBs) occurs slowly when the degrading bacteria enter a low activity state, such as a viable but nonculturable (VBNC) state, under unfavorable environmental conditions. The introduction of resuscitation-promoting factor (Rpf) can re-activate VBNC bacteria. This study tested the feasibility of enhancing PCB biodegradation via supplementing Rpf in liquid culture and soil microcosms inoculated with Rhodococcus biphenylivorans strain TG9ᵀ. Exogenous Rpf resuscitated TG9ᵀ cells that had previously entered the VBNC state after 90 d of nutrient starvation, resulting in the significantly enhanced degradation of PCB by 24.3% over 60 h in liquid medium that originally contained 50 mg L⁻¹ Aroclor 1242. In soil microcosms containing 50 mg kg⁻¹ Aroclor 1242 and inoculated with VBNC TG9ᵀ cells, after 49 d of supplementation with Rpf, degradation efficiency of PCB reached 34.2%, which was significantly higher than the control. Our results confirmed that exogenous Rpf resuscitated VBNC TG9ᵀ cells by stimulating endogenous expression of rpf gene orthologs. The enhanced PCB-degrading capability was likely due to the increased cell numbers and the strong expression of PCB catabolic genes. This study demonstrated the role of Rpf in enhancing PCB degradation via resuscitating PCB-degrading bacteria, indicating a promising approach for the remediation of PCB contamination.

Fungi-associated phytoremediation is an environmentally friendly and cost-efficient approach to remove potential toxic elements (PTEs) from contaminated soils. Many fungal strains have been reported to possess PTE-biosorption behaviour which benefits phytoremediation performance. Nevertheless, most studies are limited in rich or defined medium, far away from the real-world scenarios where nutrients are deficient. Understanding fungal PTE-biosorption performance and influential factors in soil environment can expand their application potential and is urgently needed. This study applied attenuated total reflection Fourier-transform infrared (ATR-FTIR) coupled with phenotypic microarrays to study the biospectral alterations of a fungal strain Simplicillium chinense QD10 and explore the mechanisms of Cd and Pb biosorption. Both Cd and Pb were efficiently adsorbed by S. chinense QD10 cultivated with 48 different carbon sources and the biosorption efficiency achieved >90%. As the first study using spectroscopic tools to analyse PTE-biosorption by fungal cells in a high-throughput manner, our results indicated that spectral biomarkers associated with phosphor-lipids and proteins (1745 cm⁻¹, 1456 cm⁻¹ and 1396 cm⁻¹) were significantly correlated with Cd biosorption, suggesting the cell wall components of S. chinense QD10 as the primary interactive targets. In contrast, there was no any spectral biomarker associated with Pb biosorption. Addtionally, adsorption isotherms evidenced a Langmuir model for Cd biosorption but a Freundlich model for Pb biosorption. Accordingly, Pb and Cd biosorption by S. chinense QD10 followed discriminating mechanisms, specific adsorption on cell membrane for Cd and unspecific extracellular precipitation for Pb. This work lends new insights into the mechanisms of PTE-biosorption via IR spectrochemical tools, which provide more comprehensive clues for biosorption behaviour with a nondestructive and high-throughput manner solving the traditional technical barrier regarding the real-world scenarios.

The pollution of farm soils by the plasticizer dibutyl phthalate (DBP) should be researched owing to the extensive use of plastic film. We investigated the influence of DBP on microbial communities and enzyme activities in rhizosphere and non-rhizosphere soil during the different growth stages of wheat and determined the response through simulations. The results indicated that protease, polyphenol oxidase, and β-glucosidase activity in soil decreased with increasing DBP dosage, while dehydrogenase, urease, and acid phosphatase activities increased. Moreover, the effects of DBP on soil enzyme activity gradually weakened with DBP degradation. Dibutyl phthalate has a certain inhibitory effect on the activity, diversity, and heterogeneity of microorganisms in soil. In addition, DBP can increase the utilization of amines and carboxylic acids and decrease the utilization of carbohydrates and amino acids by soil microorganisms. According to the Gaussian and molecular docking analysis, we considered that monobutyl phthalate and DBP could affect the utilization of amino acids by Proteobacteria. The enzyme activity, microbial activity, and heterogeneity of rhizosphere soil were higher than those of non-rhizosphere soil. Microbial carbon source utilization in rhizosphere and non-rhizosphere soils depends on wheat growth, soil type, and DBP dosage. Owing to the widespread presence of DBP in agriculture, negative effects of phthalic acid esters should be considered in relation to soil quality and food safety in future.

Soil acidification has been expanding in many areas of Asia due to increasing reactive nitrogen (N) inputs and industrial activities. While the detrimental effects of acidification on forests have been extensively studied, less attention has been paid to grasslands, particularly alpine grasslands. In a soil pH manipulation experiment in the Qinghai-Tibet Plateau, we examined the effects of soil acidification on plant roots, which account for the major part of alpine plants.After three years of manipulation, soil pH decreased from 6.0 to 4.7 with the acid-addition gradient, accompanied by significant changes in the availability of soil nitrogen, phosphorus and cations. Plant composition shifted with the soil acidity, with graminoids replacing forbs. Differing from findings in forests, soil acidification in the alpine grassland increased root biomass by increasing the fraction of coarse roots and the production of fine roots, corresponding to enhanced sedge and grass biomass, respectively. In addition, litter decomposability decreased with altered root morphological and chemical traits, and soil acidification slowed root decomposition by reducing soil microbial activity and litter quality.Our results showed that acidification effect on root dynamics in our alpine grassland was significantly different from that in forests, and supported similar results obtained in limited studies in other grassland ecosystems. These results suggest an important role of root morphology in mediating root dynamics, and imply that soil acidification may lead to transient increase in soil carbon stock as root standing biomass and undecomposed root litter. These changes may reduce nutrient cycling and further constrain ecosystem productivity in nutrient-limiting alpine systems.