Across the planet, winter de-icing practices have caused secondary salinization of freshwater habitats. Many amphibians are vulnerable because of permeable skin and reliance on small ponds, where salinity can be high. Early developmental stages of amphibians are especially sensitive to salt, and larvae developing in salt-polluted environments must osmoregulate through ion exchange in gills. Though ionoregulation in amphibian gills is generally understood, the role of gill morphology remains poorly described. Yet gill structure should affect ionoregulatory capacity, for instance in terms of available surface area. As larval amphibian gills also play critical roles in gas exchange and foraging, changes in gill morphology from salt pollution potentially affect not only osmoregulation, but also respiration and feeding. Here, we used an exposure experiment to quantify salinity effects on larval gill morphology in wood frogs (Rana sylvatica). We measured a suite of morphological traits on gill tufts—where ionoregulation and gas exchange occur—and on gill filters used in feeding. Larvae raised in elevated salinity developed larger gill tufts but with lower surface area to volume ratio. Epithelial cells on these tufts were less circular but occurred at higher densities. Gill filters showed increased spacing, likely reducing feeding efficiency. Many morphological gill traits responded quadratically, suggesting that salinity might induce plasticity in gills at intermediate concentrations until energetic demands exceed plasticity. Together, these changes likely diminish ionoregulatory and respiratory functionality of gill tufts, and compromise feeding functionality of gill filters. Thus, a singular change in aquatic environment from a widespread pollutant appears to generate a suite of consequences via changes in gill morphology. Critically, these changes in traits likely compound the severity of fitness impacts in populations dwelling in salinized environments, whereby ionoregulatory energetic demands should increase respiratory and foraging demands, but in individuals who possess structures poorly adapted for these functions.

Ants can influence ecological processes, such as the transfer of elements or radionuclides, in several ways. For example, they redistribute materials while foraging and maintaining their nests and have an important role in terrestrial food webs. Quantitative data of the transfer of elements into ants is needed, e.g., for developing improved radioecological models. In this study, samples of red wood ants (genus Formica), nest material, litter and soil were collected from a former uranium mining site in Eastern Finland. Concentrations of 33 elements were analyzed by Inductively Coupled Plasma-Mass Spectroscopy/Optical Emission Spectroscopy. Estimated element concentrations in spruce needles were used as a proxy for studying the transfer of elements into ants via aphids because spruces host the most important aphid farms in boreal forests. Empirically determined organism/medium concentration ratios (CRs) are commonly used in radioecological models. Ant/soil CRs were calculated and the validity of the fundamental assumption behind the of use of CRs (linear transfer) was evaluated. Elements that accumulated in ants in comparison to other compartments were cadmium, potassium, phosphorus, sulfur, and zinc. Ant uranium concentrations were low in comparison to soil, litter, or nest material but slightly elevated in comparison to spruce needles. Ant element concentrations were quite constant regardless of the soil concentrations. Non-linear transfer models could therefore describe the soil-to-ant transfer better than conventional CRs.

Soil Cd and Zn contamination has become a serious environmental problem. This work explored the performance of wood vinegar (WV) in enhancing the phytoextraction of Cd/Zn by hyperaccumulator Sedum alfredii Hance. Rhizosphere chemical properties, enzyme activities and bacterial community were analyzed to determine the mechanisms of metal accumulation in this process. Results demonstrated that, after 120 days growth, different times dilution of WV increased the shoot biomass of S. alfredii by 85.2%–148%. In addition, WV application significantly increased soil available Cd and Zn by lowing soil pH, which facilitated plant uptake. The optimal Cd and Zn phytoextraction occurred from the 100 times diluted WV (D100), which increased the Cd and Zn extraction by 188% and 164%, compared to CK. The 100 and 50 times diluted WV significantly increased soil total and available carbon, nitrogen and phosphorus, and enhancing enzyme activities of urease, acid phosphatase, invertase and protease by 10.1–21.4%, 29.1–42.7%,12.2–38.3% and 26.8–85.7%, respectively, compared to CK. High-throughput sequencing revealed that the D 100 significantly increased the bacterial diversity compared to CK. Soil bacterial compositions at phylum, family and genera level were changed by WV addition. Compared to CK, WV application increased the relative abundances of genus with plant growth promotion and metal mobilization function such as, Bacillus, Gemmatimonas, Streptomyces, Sphingomonas and Polycyclovorans, which was positively correlated to biomass, Cd/Zn concentrations and extractions by S. alfredii. Structural equation modeling analysis showed that, soil chemical properties, enzyme activities and bacterial abundance directly or indirectly contributed to the biomass promotion, Cd, and Zn extraction by S. alfredii. To sum up, WV improved phytoextraction efficiency by enhancing plant growth, Cd and Zn extraction and increasing soil nutrients, enzyme activities, and modifying bacterial community.

Arsenic (As) pollution remains a major threat to the quality of global soils and drinking water. The health effects of As pollution are often severe and have been largely reported across Asia and South America. This study investigated the possibility of using unmodified biochar derived from rice husk (RB) and aspen wood (WB) at 400 °C and 700 °C to enhance the precipitation of calcium/arsenic compounds for the removal of As(III) from solution. The approach was based on utilizing calcium to precipitate arsenic in solution and adding unmodified biochar to enhance the process. Using this approach, As(III) concentration in aqueous solution decreased by 58.1% when biochar was added, compared to 25.4% in the absence of biochar. Varying the pH from acidic to alkaline enabled an investigation into the pH dependent dynamics of the approach. Results indicated that significant precipitation was only possible at near neutral pH (i.e. pH = 6.5) where calcium arsenites (i.e. Ca(AsO₂)₂, and CaAsO₂OH•½H₂O) and arsenates (i.e. Ca₅(AsO₄)₃OH) were precipitated and deposited as aggregates in the pores of biochars. Arsenite was only slightly precipitated under acidic conditions (pH = 4.5) while no arsenite was precipitated under alkaline conditions (pH = 9.5). Arsenite desorption from wood biochar was lowest at pH 6.5 indicating that wood biochar was able to retain a large quantity of the precipitates formed at pH 6.5 compared to pH 4.5 and pH 9.5. Given that the removal of As(III) from solution is often challenging and that biochar modification invites additional cost, the study demonstrated that low cost unmodified biochar can be effective in enhancing the removal of As(III) from the environment through Ca–As precipitation.

The Amazon coastal zone has become contaminated with organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs). However, information about their distribution and sources in this area is scarce, despite increasing deforestation and oil exploitation. Therefore, individual PAHs were analysed in the sediments of the Oyapock estuary, which is located in the Amazon coastal zone. This study provides information about the spatial and short-term temporal distributions of PAHs and discusses the major sources of PAHs to better understand the anthropogenic processes occurring in adjacent areas. The concentrations of all sixteen priority PAHs defined by the US EPA (United States Environmental Protection Agency, ∑₁₆PAHs) ranged from 10.9 to 138.8 ng g⁻¹ with a mean and standard deviation = 37.9 ± 20.5 and indicated that this estuary is not contaminated, while the mean levels were similar to those found in other Amazon regions and pristine areas along the coast of Brazil. No significant differences were found in the sedimentary PAHs levels between the wet and dry sampling campaigns, despite the different climatic conditions. Diagnostic ratios, positive matrix factorization (PMF) and cluster analysis have shown that the majority of the investigated PAHs were derived from combustion processes (at least 55.1%, as estimated by the PMF model). Localized source inputs from oil and its by-products concomitantly with natural/biogenic sources appear to be secondary sources. The PAH contribution from biomass and wood combustion was approximately 13.6% and was relatively lower than other regions of the Amazon that are undergoing massive biomass burning. As the first study of PAHs in this region, this study provides vital information on the healthy state of the estuary and can serve as a baseline for assessing the impacts of acute oil disasters or the chronic input of PAHs as a result of human settlements.

Polycyclic aromatic compounds (PACs) in Canadian air and deposition were examined at the national scale for the first time in over twenty-five years. Air concentrations spanned four orders of magnitude, and were highest near industrial emitters and lowest in the Arctic. Declines in unsubstituted PAHs were observed at locations close to industrial facilities that had reduced emissions, but trends elsewhere were modest or negligible. Retene concentrations are increasing at several locations. Ambient concentrations of benzo[a]pyrene exceeded Ontario’s health-based guideline in many urban/industrial areas. The estimated toxicity of the ambient PAC mixture increased by up to a factor of six when including compounds beyond the US EPA PAHs. Knowledge of PAC deposition is limited to the Laurentian Great Lakes and Athabasca Oil Sands regions. The atmosphere remained a net source of PAHs to the Great Lakes, though atmospheric inputs were decreasing with halving times of 26–30 years. Chemical transport modelling substantially overestimated wet deposition, but model performance is unknown for dry deposition. Sources from Asia, Europe and North America contributed to Arctic and Sub-Arctic concentrations, whereas transboundary or long-range transport have not been assessed outside Canada’s north. Climate-related impacts from re-emission and forest fires were implicated in maintaining air concentrations in the high Arctic that were not consistent with global emissions reductions. Industrial emission decreases were substantial at the national scale, but their influence on the environment was limited to areas near relevant facilities. When examined through the lens of ambient levels at the local scale, evidence suggested that contributions from residential wood combustion and motor vehicles were smaller and larger, respectively, than those reported in national inventories. Future work aimed at characterizing PACs beyond the EPA PAHs, improving measurement coverage, elucidating deposition phenomena, and refining estimates of source contributions would assist in reducing remaining knowledge gaps about PACs in Canada.

The Peace-Athabasca Delta (PAD) receives a mixture of hydrocarbons from biogenic, pyrogenic, and petrogenic processes. Source apportionment in the PAD has focussed on polycyclic aromatic compounds (PACs), which are ubiquitous in the environment and susceptible to weathering. In contrast, petroleum biomarkers of terpanes, hopanes, and steranes are degradation-resistant organic compounds found uniquely in petroleum products that can identify the input and origin of petrogenic hydrocarbons (PHCs). We provide an analysis of environmentally-relevant PHCs (including n-alkanes, PACs, and petroleum biomarkers) in surficial sediments of strategically selected lakes in the Athabasca and Peace deltas and adjacent boreal uplands. Alkanes were found to be predominately biogenic in all lakes. PAC sources were identified as wood combustion in the upland boreal lakes, a mixture of petrogenic and pyrogenic combustion in two closed-drainage lakes in the Peace Delta, and predominately petrogenic in two flood-prone Athabasca Delta lakes. Using multivariate analyses, raw Alberta oil sands were identified as a potential source of PHCs to the two flood-prone lakes in the Athabasca Delta. Biomarkers of terpanes and hopanes were identified in the Peace Delta and boreal uplands, likely from bitumen and transported atmospherically. These findings validate the use of petroleum biomarkers as tracers for bituminous sands in surficial lake sediments and their potential use in paleolimnological investigations at the PAD to improve understanding of relative roles of natural and industrial processes on far-field deposition of PHCs.

The Wood mouse (Apodemus sylvaticus) is a widespread mammalian species that acts as a reservoir host for multiple infections, including zoonotic diseases. Exposure to immunotoxins, like for instance trace metals, may reduce the ability of the host to mount proper responses to pathogens, potentially increasing the transmission and prevalence of infections. Antibody-mediated responses are crucial in preventing and limiting infections, and the quantification of the primary antibody response is considered a sensitive predictor of immunosuppression. The current study aims to investigate effects of cadmium exposure on the antibody-mediated responses of wood mice inhabiting polluted and non-polluted areas in the Netherlands. Wood mice were captured alive at different locations and immunized to sheep red blood cells (SRBC) to induce a primary antibody response. SRBC-specific antibody-producing cells, or plaque forming cells (PFC), were quantified and related to kidney cadmium levels. Differential circulating main leukocyte populations were also characterised. Cadmium concentrations in mice kidneys differed between mice captured at different locations, and increased with individual body mass, likely associated with age-related time of exposure. Effect of cadmium was apparent on the percentages of B cell counts in blood. Because of potential natural immune heterogeneity between wild rodent populations, mice immune responses were analysed and compared grouped by captured locations. Capture location had significant effect on the total counts of white blood cells. Increasing cadmium exposure in wood mice captured from polluted sites was associated with a decrease of splenic PFC counts. This field research shows that wood mice antibody responses can be impaired by cadmium exposure, even at low environmental levels, by affecting B cell functioning mainly. Impaired B cell function can make exposed mice more susceptible to infections, potentially increasing the reservoir function of their populations. It also shows that immunomodulatory effects in the field should be assessed site specifically.

Understanding the migration and conversion of nitrogen in wood-based panels (WBPs) during pyrolysis is fundamentally important for potentially transforming the N-containing species into valuable material-based products. This review firstly summarizes the commonly used methods for examining N evolution during the WBPs pyrolysis before probing into the association between the wood and adhesives.The potential effects of wood-adhesive interaction on the pyrolysis process are subsequently analyzed. Furthermore, the controversial statements from literature on the influence of adhesives on wood pyrolysis behavior are discussed, which is followed by the detailed investigation into the distribution and evolution of N-containing species in gas, liquid and char, respectively, during WBPs pyrolysis in recent studies. The differences in N species due to the heating sources (i.e. electrical heating vs microwave heating) are particularly compared. Finally, based on the characteristics of staged pyrolysis, co-pyrolysis and catalytic pyrolysis, the converting pathways for WBPs are proposed with an emphasis on the production of value-added chemicals and carbon materials, simultaneously mitigating NOₓ emission.

In this review, global change processes have been linked to polycyclic aromatic compounds (PACs) in Canada and a first national budget of sources and sinks has been derived. Sources are dominated by wildfire emissions that affect western and northern regions of Canada disproportionately due to the location of Pacific and boreal forests and the direction of prevailing winds. Wildfire emissions are projected to increase under climate warming along with releases from the thawing of glaciers and permafrost. Residential wood combustion, domestic transportation and industry contribute the bulk of anthropogenic emissions, though they are substantially smaller than wildfire emissions and are not expected to change considerably in coming years. Other sources such as accidental spills, deforestation, and re-emission of previous industrial deposition are expected to contribute anthropogenic and biogenic PACs to nearby ecosystems. PAC sinks are less well-understood. Atmospheric deposition is similar in magnitude to anthropogenic sources. Considerable knowledge gaps preclude the estimation of environmental transformations and transboundary flows, and assessing the importance of climate change relative to shifts in population distribution and energy production is not yet possible. The outlook for PACs in the Arctic is uncertain due to conflicting assessments of competing factors and limited measurements, some of which provide a baseline but have not been followed up in recent years. Climate change has led to an increase in primary productivity in the Arctic Ocean, but PAC-related impacts on marine biota appear to be modest. The net effect of changes in ecological exposure from changing emissions and environmental conditions throughout Canada remains to be seen. Evidence suggests that the PAC budget at the national scale does not represent impacts at the local or regional level. The ability to assess future trends depends on improvements to Canada’s environmental measurement strategy and biogeochemical modelling capability.