Concerns regarding the environmental impact of diesel exhaust particulate matter (DPM) have increased in recent years. Following emission to the atmosphere, these fine materials can sorb many contaminants at their surface, which can subsequently be released, for instance, due to physicochemical environmental changes. The desorption of contaminants from particulate matter will increase the environmental pollution and can promote ecotoxicological effects. In this context, the objective of this study was to assess the aquatic ecotoxicity profile of extracts of DPM obtained at two different pH values. Thus, after collecting particulate matter from the diesel exhaust of heavy engines, extracts were obtained with pure water (at pH 2.00 and 5.00) and with a mixture of three organic solvents (dichloromethane, n-hexane, and acetone). To assess the environmental impact of DPM, the exhaust extracts were used in a battery of aquatic bioassays including key organisms of the food chain: bacteria (Aliivibrio fischeri), algae (Scenedesmus subspicatus), daphnids (Daphnia magna), and fishes (Danio rerio). The aqueous leachate at natural pH (2.0) and solvent extracts were extremely ecotoxic, while the aqueous leachate at pH = 5.0 showed the lowest ecotoxicity. The global ranking of sensitivity for the biotests tested was daphnids > algae > bacteria > fishes. Thus, the use of this bioassay battery could improve our understanding of the impact of DPM on aquatic environments, which is dependent on the pH of the leaching process.

Passive samplers are of the most applied methods and tools for measuring concentration of hydrophobic organic compounds in water (c ₁ ᵂ) in which the polymer-water partition coefficients (D) are of fundamental importance for reliability of measurements. Due to the cost and time associated with the experimental researches, development of a predictive method for estimation and evaluation of performance of polymeric passive samplers for various hydrophobic organic compounds is highly needed and valuable. For this purpose, in this work, following the fundamental chemical thermodynamic equations governing the concerned local equilibrium, successful attempts were made to establish a theoretical model of polymer-water partition coefficients. Flory–Huggins model based on the Hansen solubility parameters was used for calculation of activity coefficients. The method was examined for reliability of calculations using collected data of three polymeric passive samplers and ten compounds. A regression model of form ln(D) = 0.707ln(c ₁ ᵖ) − 2.7391 with an R ² = 0.9744 was obtained to relate the polymer-water partition coefficients (D) and concentration of hydrophobic organic compounds in passive sampler (c ₁ ᵖ). It was also found that polymer-water partition coefficients are related to the concentration of hydrophobic organic compounds in water (c ₁ ᵂ) as ln(D) = 2.412ln(c ₁ ᵖ) − 9.348. Based on the results, the tie lines of concentration for hydrophobic organic compounds in passive sampler (c ₁ ᵖ) and concentration of hydrophobic organic compounds in water (c ₁ ᵂ) are in the form of ln(c ₁ ᵂ) = 0.293ln(c ₁ ᵖ) + 2.734. The composition of water sample and the interaction parameters of dissolved compound-water and dissolved compound-polymer, temperature, etc. actively influence the values of partition coefficient. The discrepancy observed over experimental data can be simply justified based on the local condition of sampling sites which alter these effective factors.

Biochar is produced by pyrolysis of biomass residues under limited oxygen conditions. In recent years, biochar as an amendment has received increasing attention on composting and soil remediation, due to its unique properties such as chemical recalcitrance, high porosity and sorption capacity, and large surface area. This paper provides an overview on the impact of biochar on the chemical characteristics (greenhouse gas emissions, nitrogen loss, decomposition and humification of organic matter) and microbial community structure during composting of organic wastes. This review also discusses the use of biochar for remediation of soils contaminated with organic pollutants and heavy metals as well as related mechanisms. Besides its aging, the effects of biochar on the environment fate and efficacy of pesticides deserve special attention. Moreover, the combined application of biochar and compost affects synergistically on soil remediation and plant growth. Future research needs are identified to ensure a wide application of biochar in composting and soil remediation. Graphical abstract ᅟ

This study aimed to investigate the possible mechanisms of environmental metal pollutant lead (Pb)-induced apoptosis in chicken. Forty 8-day-old healthy chickens were randomly assigned to two groups (n = 20/group) after raising standard commercial diet and drinking water for 1 week: including control group and Pb group ((CH₃COO)₂Pb 350 mg/L of drinking water); the chickens were given euthanasia and collected livers at 90 days. A significant increase of apoptosis rate were found in Pb group and Pb induced obvious ultrastructural changes of chicken liver. The mRNA levels of glycometabolism key enzymes were significantly lower in Pb group than those in controls. Higher levels of malondialdehyde (MDA) and nitric oxide (NO) were observed in Pb group; the activities of antioxidant enzymes and ATPases were significantly lower in Pb group than those in controls, while the inducible nitric oxide synthase (iNOS) activity was on the contrary. The mRNA and protein levels of pro-apoptotic genes were all lower in Pb group than those in controls. Altogether, Pb-induced mitochondrial swelling and nuclear chromatin condensation, oxidative stress, energy metabolism disorder, thereby lead to apoptosis via mitochondrial pathway in chicken liver, suggesting that Pb-induced mitochondrial pathway apoptosis plays an important role in the mechanisms of Pb cytotoxicity to chicken liver.

Sulfonamides are the second most widely used group of veterinary antibiotics which are often detected in the environment. They are eliminated from freshwaters mainly through photochemical degradation. The toxicity of sulfadimethoxine (SDM) was evaluated with the use of Lemna minor before and after 1- and 4-h irradiation in a SunTest CPS+ solar simulator. Eight endpoints consisting of: number and total area of fronds, fresh weight, chlorophylls a and b, carotenoids, activity of catalase and guaiacol peroxidase, and protein content were determined. The total frond area and chlorophyll b content were the most sensitive endpoints with EC50 of 478 and 554 μg L⁻¹, respectively. The activity of guaiacol peroxidase and catalase increased at SDM concentrations higher than 125 and 500 μg L⁻¹, respectively. The SDM photodegradation rate for first order kinetics and the half-life were 0.259 h⁻¹ and 2.67 h, respectively. The results show that the toxicity of irradiated solutions was caused by SDM only, and the photoproducts appeared to be either non-toxic or much less toxic to L. minor than the parent compound. To study the recovery potential of L. minor, after 7 days exposure in SDM solutions, the plants were transferred to fresh medium and incubated for the next 7 days. L. minor has the ability to regenerate, but a 7-day recovery phase is not sufficient for it to return to an optimal physiological state.

Ecological risk assessment, spatio-temporal variation, and source apportionment of polychlorinated biphenyls (PCBs) were studied in surface sediments and water from River Ravi and its three northern tributaries (Nullah Deg, Nullah Basantar, and Nullah Bein) in Pakistan. In total, 35 PCB congeners were analyzed along 27 sampling stations in pre-monsoon and post-monsoon seasons. The ∑₃₅PCB concentration ranged from 1.06 to 95.76 ng/g (dw) in sediments and 1.94 to 11.66 ng/L in water samples, with hexa-CBs and tetra-CBs as most dominant homologs in sediments and water matrixes, respectively. The ∑₈DL-PCB levels were 0.33–22.13 ng/g (dw) and 0.16–1.95 ng/L in sediments and water samples, respectively. The WHO-toxic equivalent values were ranged from 1.18 × 10⁻⁶ to 0.012 ng/L and 1.8 × 10⁻⁶ to 0.031 ng/g in water and sediments matrixes, respectively. The ecological risk assessment indicates considerable potential ecological risk during pre-monsoon season ([Formula: see text] = 95.17) and moderate potential ecological risk during post-monsoon season ([Formula: see text] = 49.11). The industrial and urban releases were recognized as key ongoing sources for high PCB levels in environment. Therefore, we recommend more freshwater ecological studies to be conducted in the study area and firm regulatory initiatives are required to be taken in debt to the Stockholm Convention, 2001 to cop up with PCB contamination on emergency basis.

Acid mine drainage (AMD) is extremely acidic, sulfate-rich effluent from abandoned or active mine sites that also contain elevated levels of heavy metals. Untreated AMD can contaminate surface and groundwater and pose severe ecological risk. Both active and passive methods have been developed for AMD treatment consisting of abiotic and biological techniques. Abiotic techniques are expensive and can create large amounts of secondary wastes. Passive biological treatment mainly consists of aerobic or anaerobic constructed wetlands. While aerobic wetlands are economical, they are not effective if the pH of the AMD is < 5. Anaerobic wetlands use organic-rich substrates to provide carbon source to iron- and sulfate-reducing bacteria. The efficiency of these systems declines overtime and requires continuous maintenance. Our objective is to develop an alternative, low-cost, and sustainable floating wetland treatment (FWT) system for AMD for the abandoned Tab-Simco coal mining site in Illinois using vetiver grass (Chrysopogon zizanioides). Tab-Simco AMD is highly acidic, with mean pH value of 2.64, and contains high levels of sulfate and metals. A greenhouse study was performed for a 30-day period in order to screen and optimize the necessary parameters to design a FWT system. Water quality and plant growth parameters were continuously monitored. Results show significant SO₄ ²⁻ removal, resulting in increased pH, particularly at higher planting densities. Vetiver also helped in metal removal; high amounts of Fe, Zn, and Cu were removed, with relatively lower amounts of Pb, Al, and Ni. Iron plaque formation on the root was observed, which increased metal stabilization in root and lowered root to shoot metal translocation. Vetiver was tolerant of AMD, showing minimal change in biomass and plant growth. Results obtained are encouraging, and a large scale mesocosm study is now in progress, as the next step to develop the vetiver-based system for AMD treatment.

In the karst landscape, widespread in the world including southern China, soil nutrient supply is strongly constrained. In such environments, arbuscular mycorrhizal (AM) fungi may facilitate plant nutrient uptake. However, the possible role of different AM fungal species, and their interactions, especially in transferring nitrogen (N) from litter to plant, is poorly understood. We conducted two microcosm experiments to investigate the role that two karst soil AM fungi, Glomus etunicatum and Glomus mosseae, play in the transfer of N from decomposing litter to the host plant and to determine how N availability influences these processes. In experiment 1, Cinnamomum camphora tree seedlings were grown in compartments inoculated with G. etunicatum. Lolium perenne leaf litter labeled with δ¹⁵N was added to the soil in unplanted compartments. Compartments containing the δ¹⁵N labeled litter were either accessible to hyphae but not to seedling roots or were not accessible to hyphae or roots. The addition of mineral N to one of the host compartments at the start of the experiment significantly increased the biomass of the C. camphora seedlings, N content and N:P ratio, AM mycelium length, and soil microbial biomass carbon and N. However, significantly, more δ¹⁵N was acquired, from the leaf litter by the AM hyphae and transferred to the host when mineral N was not added to the soil. In experiment 2, in which C. camphora seedlings were inoculated with both G. etunicatum and G. mosseae rather than with G. mosseae alone, there was a significant increase in mycelial growth (50.21%), in soil microbial biomass carbon (417.73%) in the rhizosphere, and in the amount of δ¹⁵N that was transferred to the host. These findings suggest that maintaining AM fungal diversity in karst soils could be important for mediating N transfer from organic material to host plants in N-poor soils.

The present study investigated the response to ozone (O₃) of two cultivars (cv.‘Romana’ and cv. ‘Canasta’) of irrigated lettuce grown in an open-top chamber (OTC) experiment in Mediterranean conditions. Two different levels of O₃ were applied, ambient O₃ in non-filtered OTCs (NF-OTCs) and −40% of ambient O₃ in charcoal-filtered OTCs (CF-OTCs), during four consecutive growing cycles. At the end of each growing cycle, the marketable yield (fresh biomass) was assessed while during the growing periods, measurements of the stomatal conductance at leaf level were performed and used to define a stomatal conductance model for calculation of the phytotoxic ozone dose (POD) absorbed by the plants.Results showed that O₃ caused statistically significant yield reductions in the first and in the last growing cycle. In general, the marketable yield of the NF-OTC plants was always lower than the CF-OTC plants for both cultivars, with mean reductions of −18.5 and −14.5% for ‘Romana’ and ‘Canasta’, respectively. On the contrary, there was no statistically significant difference in marketable yield due to the cultivar factor or to the interaction between O₃ and cultivar in any of the growing cycle performed.Dose-response relationships for the marketable relative yield based on the POD values were calculated according to different flux threshold values (Y). The best regression fit was obtained using an instantaneous flux threshold of 6 nmol O₃ m⁻² s⁻¹ (POD₆); the same value was obtained also for other crops. According to the generic lettuce dose-response relationship, an O₃ critical level of 1 mmol O₃ m⁻² of POD₆ for a 15% of marketable yield loss was found.

Environmental pollution caused by inert anthropogenic stressors such as microplastics in aquatic media is constantly increasing. Through the proliferating use of plastic products in daily life, more and more plastic particles enter waters as primary microplastics. Even though large scale plastic items such as plastic bottles and bags represent the highest percentage of plastic waste, their degeneration also generates microparticles and nanoparticles (secondary microplastics). Modern sewage treatment plants require innovative ideas in order to deal with this man-made problem. State-of-the-art technology offers approaches to minimise the amount of microplastics in aquatic systems. These technologies, however, are either insufficient or very costly, as well as time-consuming in both cases. The conceptual idea presented here is to apply innovative inorganic-organic hybrid silica gels which provide a cost-effective and straightforward approach. Currently, the synthesis of preorganised bioinspired compounds is advancing in order to produce functionalised hybrid silica gels in a further step. These gels have the ability to remove stressors such as microplastics from waste water. By means of the sol-gel process, bioinspired silane compounds are currently being permuted to macromolecules and examined with respect to their properties as fixation and filter material in order to remove the hydrophobic anthropogenic stressors sustainably. Here, the reproduction of biological systems plays a significant role. In particular in material sciences, this approach is becoming increasingly important. Among other concepts, new biomimetic molecules form the basis for the investigation of innovative host-guest relationships for anthropogenic stressors in the environment and their implementation in technical processes.