Global warming and pollution are the twin crises experienced globally. Biological offset of these crises are gaining importance because of its zero waste production and the ability of the organisms to thrive under extreme or polluted condition. In this context, this review highlights the recent developments in carbon dioxide (CO₂) capture from flue gas using microalgae and finding the best microalgal remediation strategy through contrast and comparison of different strategies. Different flue gas microalgal remediation strategies discussed are as follows: (i) Flue gas to CO₂ gas segregation using adsorbents for microalgal mitigation, (ii) CO₂ separation from flue gas using absorbents and later regeneration for microalgal mitigation, (iii) Flue gas to liquid conversion for direct microalgal mitigation, and (iv) direct flue gas mitigation using microalgae. This work also studies the economic feasibility of microalgal production. The study discloses that the direct convening of flue gas with high carbon dioxide content, into microalgal system is cost-effective.

ANT is a commonly occurring polycyclic aromatic hydrocarbon (PAH) in natural eutrophic waters where Microcystis blooms break out usually. In this study, effects of ANT at different concentrations (0.02, 0.06, 0.18, 0.54, and 1.62 μg/mL) on the growth, microcystin-LR (MC-LR) production, and expression of three key mcy genes in Microcystis aeruginosa were investigated. The results showed that all the tested concentrations of ANT inhibited M. aeruginosa growth significantly except 0.02 μg/mL ANT in the early stage of the experiment. In the culture media, initially applied ANT concentrations decreased significantly after 3 days of incubation. ANT stimulated MC-LR production in a concentration-dependent manner. After exposure to ANT for 1 day, the expression of mcyB gene was inhibited and the inhibitory effects increased with ANT concentrations. ANT at higher concentrations (above 0.02 μg/mL) stimulated gene expression of mcyD (P < 0.05) and mcyH (P < 0.01) significantly, and 0.02 μg/mL of ANT inhibited their expression significantly (P < 0.01). With increasing culture time, 0.18 μg/mL of ANT inhibited mcyB gene expression first and then stimulated it while gene expressions of mcyD and mcyH were stimulated throughout the experiment. Our results suggested that ANT in natural waters could affect not only Microcystis growth but also MC production via modifying mcy gene expressions.

Three macrophyte species, Typha augustifolia (T. augustifolia), Phragmites australis (P. australis), and Acorus calamus L. (A. calamus L.), have been grown in hydroponic cultivation systems fed with synthetic wastewater. The experiment was designed as 3 × 2 factorial, with three species and two ratios of NH₄ ⁺/NO₃ ⁻ so as to investigate the nitrogen transformation and nitrogen removal capacity of each species. The nitrogen removal mechanism was further disclosed by comparing biomass production, nitrogen mass balance, and root exudates of the three plant species under different NH₄ ⁺/NO₃ ⁻ ratios. The results indicated there exists a linear relationship, with positive significance (r = 0.946, p < 0.05), between plant biomass and total nitrogen (TN) removal efficiency; in other words, biomass could best reflect plant ability to remove nitrogen. It is also found that NH₄ ⁺/NO₃ ⁻ ratio could influence plant biomass and root exudates significantly. Additionally, the hydrogen donor and source of energy in denitrification happened in this research were mainly organic acids and soluble sugars, accounting for approximately 50 % of the composition in root exudates.

Bosten Lake, a typical rump lake in an oasis in northwest China, was chosen to evaluate the distribution, sources, pollution status, and potential ecological risk of heavy metals. Sediment samples were collected from the lake, and results showed that the values of the eight heavy metals all fell within the Second Soil National Standard, while the average and maximum values of the metals were higher than the background values of the study. Multivariate statistical analysis showed that sediment concentrations of Cd, Pb, Hg, and Zn were mainly influenced by man sources. In comparison, Cu, Ni, Cr, and As were primarily natural in origin. Enrichment factor analysis (EF) and the geo-accumulation index evaluation method (I gₑₒ) showed that Cd, Hg, and Pb fell under low and partial serious pollution levels, while Zn, As, Cr, Ni, and Cu mainly were characterized under no pollution and low pollution levels. The potential ecological hazards index (RI) showed that among the eight heavy metals, Pb, Hg, and Cd posed the highest potential ecological risk, with potential ecological hazards indices (RI) of 29.06, 27.71, and 21.54 %, respectively. These findings demonstrated that recent economic development in the area of the basin has led to heavy metal accumulation in the surface sediments of the lake.

Sediment samples from a salt marsh habitat in the vicinity of Linden Chemical Plant (LCP) Superfund site in Brunswick Georgia, USA, were analyzed for the composition of total solvent extracts and sources of lipid compounds. Stable isotope analysis of carbon and nitrogen and gas chromatography-mass spectrometry analysis infer past multiple sources of organic matter (OM) from aquatic and terrestrial origin, e.g., phytoplankton, bacteria, and land plants, as well as anthropogenic contamination. The n-alkane and n-alkanol distributions in the sediment samples were dominated by long-chain homologues maximizing at C₂₅–C₂₇ for alkanes (carbon preference index (CPI) ∼1) and C₃₂ for n-alkanols indicating inputs from higher plants, but also microbial and petroleum-related sources. Fatty acid distribution was characterized by short-chain (< C₁₈) and branched homologues indicative of bacterial origin. The high abundance of dehydroabietic acid and anthropogenic contaminants, including alkylphenols, are indicative of the effects of past industrial activities in the LCP marsh area in Brunswick, Georgia.

By using the activated carbon obtained from Citrullus lanatus rind by zinc chloride activation, methylene blue (MB) removal from aqueous solutions was studied, and the adsorption mechanism was solved through Weber-Morris intraparticle diffusion model, Bangham model, Boyd model, Fourier transform infrared spectra, and scanning electron microscopy. The effects of adsorption parameters (adsorbent concentration, temperature, initial dye concentration, and pH) were investigated. The equilibrium data of MB adsorption were described by applying the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models. The obtained results from adsorption isotherms indicated that Langmuir model is the best-fitted model with the maximum adsorption capacities of 231.48, 243.90, 244.50, and 259.74 mg/g at 25, 35, 45, and 55 °C, respectively. The analysis of the kinetic data by pseudo-first-order, pseudo-second-order, and Elovich models displayed that MB adsorption followed pseudo-second-order model. Also, the date obtained from intraparticle diffusion model, Bangham model, and Boyd model presented that intraparticle diffusion, pore diffusion, and film diffusion played significant role in MB adsorption. The thermodynamic studies demonstrated that MB adsorption onto the activated carbon obtained from C. lanatus rind was physical, spontaneous, feasible, and endothermic. Thus, the activated carbon prepared from C. lanatus rind has been an efficient adsorbent for MB removal from an aqueous solution. Graphical Abstract ᅟ

The study was aimed to evaluate the selected improvements of nature restoration in a depleted gravel pit. The study site consisted of four water reservoirs of different shapes and sizes, flooded after the gravel extraction ended. Ecological succession monitoring, conducted by the Warsaw University of Life Sciences students associated in the Student Scientific Association of Animal Sciences Faculty since the completion of mining, have focused on amphibians. A twofold approach upheld amphibian species population dynamics, as well as selected habitat elements. The restoration practices dedicated to habitat conditions enhancing have been proved to be definitely effective and useful for similar sites.

We evaluated the biogeochemical processes occurring in the rhizosphere of different native plants growing spontaneously in a copper-contaminated soil in an abandoned mine site in NE Brazil. We also assessed the effects that these processes have on copper mobility and toxicity and discuss the potential use of the plants as pioneer species in restoration programs. For these purposes, we determined chemical (pH, macronutrients, % TOC, and % TIC) and mineralogical (XRD) properties in both rhizosphere and nonrhizosphere soils (bulk soil), and we used the sequential extraction method (SEM) to extract copper from both soils. The study findings show that the plants have greatly altered the physicochemical characteristics of the soil that is directly influenced by their roots. Different plant species appear to act through different processes, thus altering various soil components and affecting the biogeodynamic cycling of essential nutrients and copper. The changes in the physical-chemical characteristics of the rhizosphere affected copper dynamics, mainly manifested as significantly lower concentrations of potentially bioavailable copper, i.e., exchangeable and carbonate-associated copper, in this soil fraction. The concentration of copper associated with noncrystalline Fe oxides was also higher in the rhizosphere, thus enhancing the immobilization and probably minimizing the risks of copper toxicity and mobility. The biogeochemical processes observed in the rhizosphere of the species under study seem to indicate that the plants promote phytostabilization of copper in their rhizosphere zone, and they thus show desirable characteristics for use in phytoremediation programs.

The bioconcentration potential of fluoxetine (FLX) and its biological effects were investigated in juvenile Pacific oyster exposed for 28 days to environmentally relevant concentrations of FLX (1 ng L⁻¹, 100 ng L⁻¹ and up to 10 μg L⁻¹). FLX bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. Nevertheless, FLX did not induce oyster mortality, delayed gametogenesis, or lead to adverse histopathological alterations. At the two highest concentrations, despite non-optimal trophic conditions, FLX stimulated shell growth but only in a transient manner, suggesting a role of serotonin in the regulation of feeding and metabolism in bivalves. Those high concentrations seemed to drive bell-shaped responses of catalase and glutathione S-transferase activities throughout the exposure period, which may indicate the activation of antioxidant enzyme synthesis and then an enhanced catabolic rate or direct inhibition of those enzymes. However, no clear oxidative stress was detected because no strong differences in thiobarbituric acid-reactive substance (TBARS) content (i.e. lipid peroxidation) were observed between oyster groups, suggesting that cellular defence mechanisms were effective. These results demonstrate the importance of considering additional biomarkers of oxidative stress to obtain a comprehensive overview of the FLX-induced changes in marine bivalves exposed under realistic conditions. Considering the battery of biomarkers used, FLX appears to induce little or no effects on oyster physiology even at a concentration of 10 μg L⁻¹. These results do not confirm the lowest observed effect concentration (LOEC) values reported by some authors in other mollusc species.

This research work evaluates the use of hydrogen peroxide for the removal of cyanide from coking wastewater deriving from the washing of gases in coal combustion furnace. The effect of the presence or absence of suspended solids and organic micropollutants on the efficiency of the treatment is analyzed. Various dosages of hydrogen peroxide (6.5–200 mg/L) were added to both aqueous solution (at pH 10.5) and industrial wastewater (at pH 10.3) samples. The influence of suspended solids in coking wastewater was analyzed by applying a coagulation–flocculation–decantation process before the hydrogen peroxide treatment. The preliminary cyanide removal treatment in aqueous solution showed that the maximum cyanide removal did not exceed 14 % using a mass ratio of hydrogen peroxide to cyanide of 11.6. The maximum cyanide removal obtained in coking wastewater was 47 % with a mass ratio of hydrogen peroxide to cyanide of 12.2 provided that a coagulation–flocculation–decantation pretreatment was applied to remove the suspended solids composed mainly of coal, calcium carbonate, and magnesium carbonate. On the other hand, the cyanide removal treatment in coking wastewater with hydrogen peroxide showed promising results in the removing of different organic micropollutants formed mainly by polycyclic aromatic hydrocarbons and quinolines.