The present research investigates potential of microalgae isolated from sewage treatment plant to utilize sodium bicarbonate as carbon source for CO₂ sequestration and biodiesel production. Eight algal isolates were isolated from waste water of sewage treatment plant, Amity University Haryana, India. The most potent algal isolates were identified and characterized on the basis of growth and lipid content. The efficient isolates ASW1 and ASW2 were identified as Chlorella sp. and Arthronema sp. by 18srRNA and 16srRNA sequencing method. In both isolates, maximum growth was observed under 20-W fluorescent bulb (3500 flux light intensity) with continuous light cycle of 24 h at pH 9.0 and 25 °C on the 20th day of incubation period. CO₂ utilization efficiency of both algal isolates were observed in terms of total CO₂ consumption rate. Under optimized culture conditions, total lipid content and lipid yield was higher in Arthronema sp. (180 mg l⁻¹; 32.14%) as compared to Chlorella sp. (98 mg l⁻¹; 29.6%) in 50 mM NaHCO₃. Transesterified lipids were analysed by GC-MS. The fatty acid methyl ester profile of Arthronema sp. was 34.42% saturated and 65.58% unsaturated fatty acid. Chlorella sp. produces 29.80% saturated and 70.20% unsaturated fatty acid. In both isolates, C16 and C18 fatty acids dominated, which is a promising component for biodiesel. Graphical abstract

Accelerating greenhouse gas emission particularly carbon dioxide (CO₂) in the atmosphere has become a major concern. Adsorption process has been proposed as a promising technology for CO₂ adsorption from flue gas, and the carbonaceous adsorbent is a potential candidate for CO₂ adsorption at atmospheric pressure and ambient temperature. Biochar derived from palm kernel shell waste was applied as a potential precursor for activated carbon production. This research study employed the response surface methodology coupled with Box-Behnken design to optimize the parameters involved in producing exceptional activated carbon with high yield (Y₁) and CO₂ adsorptive characteristics (Y₂). Specifically, parameters studied include the activation temperature (750–950 °C), holding time (60–120 min), and CO₂ flow rate (150–450 mL/min). The activated carbon at the optimum conditions was characterized using various analytical instruments, including elemental analyzer, nitrogen (N₂) physisorption analyzer, and field emission scanning electron microscopy. Overall, utilization of biochar as the activated carbon precursor is practical compared with the traditional non-renewable materials, due to its cost efficiencies and it being more environment-friendly ensuring process sustainability. Besides, this research study that incorporates physical activation with CO₂ as the activating agent is attractive, because it directly promotes CO₂ utilization and capture, in addition to the absence of any chemicals that may result in the secondary pollution problems.

Previous studies have shown the effect of extremely low-frequency (ELF) magnetic fields on the hematopoietic system. However, molecular modification and biological toxicity are not known yet. The aim of this study was to investigate the effect of occupational exposure to ELF magnetic field on the hemoglobin and DNA alteration using Fourier transform infrared (FTIR) spectroscopy. Twenty nine individuals were selected among those working as the controller in a powerhouse in order to be studied as the population exposed to ELF magnetic field. Control group comprised of 29 administrative employees voluntarily participated who were matched with the exposed subjects in terms of sex, age, work experiences, smoking habit, and socioeconomic status. DNA and hemoglobin were extracted from blood samples and then were studied by FTIR spectroscopy. The results showed the level of magnetic field exposure was between 0.38 to 50 μT in the exposed subjects while the level of magnetic field exposure was between 0.19 and 20 μT for the unexposed people. Hemoglobin level was equal to 15.67 ± 1.42 g/dL for exposed subjects which is significantly lower than that of the unexposed people (p = 0.0001). There was a significant alteration in CH content and COO structure of the hemoglobin structure. Moreover, DNA showed significant changes by functional group of organic base. This change in the structure of DNA and hemoglobin can lead to the creation of risks in human health. In conclusion, FTIR method could reveal the quality of DNA and hemoglobin structure in subjects after exposure to ELF magnetic field.

This study aims to investigate the airborne elements’ deposition by using native Usnea barbata lichens as biomonitors in the forested areas of Tierra del Fuego (TdF, southern Patagonia), an apparently pristine environment. The present study is linked to the volcanic eruption of the Puyehue-Cordón Caulle which started in north Patagonia in June 2011, which gives rise to long-distance transport of pollutants through the atmosphere at 1700 km from our sampling sites. The monitoring breakdown structure (MBS) was applied to three sampling campaigns in 2006 (baseline) ➔ 2011–2012 (3 and 15 months after the volcanic event, respectively). We have on purpose enhanced the information variety endowment: (i) Seventy-one referenced sites were double sampled; (ii) up to 426 composite lichen samples were collected; (iii) twenty-six elements were measured by neutron activation analysis (As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, Yb, Zn) for samples of 2011 and 2012 campaigns; (iv) thirteen common elements (As, Ba, Ca, Co, Cr, Cs, Fe, K, Na, Sb, Se, U, Zn) were determined in 2006 for the baseline comparison. The natural contamination by tephras is reflected by lichens more clearly in the 2011 campaign, where Ba, Cr, Na, Ca, Cs, and U showed higher median levels compared with the baseline campaign (2006). Ca, K, and Na were the most accumulated elements after the volcano event and could be associated with the volcanic ashes’ deposition. Rare earth elements (REEs) showed no significant bioaccumulation levels between 2011 and 2012, indicating their association with higher lithogenic inputs than volcanic ashes. Using the Earth’s crust as reference, nine elements (As, Ba, Br, Ca, K, Na, Sb, Se, and Zn) presented moderate/significant mean enrichment factor (EF) values (> 5). The usefulness of Usnea barbata as test species for direct biomonitoring oriented kinetic studies in areas characterized by a low human impact is confirmed. Eventually, our results confirm that TdF is not an actual pristine environment as earlier supposed.

Mercury contamination and its rate of transformation and transport are increasing in the environment due to climatic variations. The mercury contamination is also rising in the polar ecosystems too. The present study assessed the content of mercury and other metals in the surface soils of tundra ecosystem of Ny-Ålesund, Svalbard. The samples were taken during summer months of 2015–2018 as part of Indian Arctic expedition. Mercury content in the surface soils were ranged from 0.01 to 0.14 μg/g and is comparable with the earlier studies carried out in the circumpolar regions. Total mercury content in plant samples was also comparable and the mean concentration was 83.45 ng/g. The mercury content is significantly varied from site to site; however, no significant variation was found between years. The interrelationship shown by mercury and other metals indicated a common contaminant pathway. The results indicated that the metals might have influenced by the local variations in the environment especially the increased thawing of permafrost as it led to more runoff of accumulated as well as atmospherically deposited metals. Hence, more detailed studies are required to understand the effect of thawing and atmospheric conditions on the cycling of metals in the polar environment.

It is globally acceptable that carbon dioxide (CO₂) emissions are one of the greenhouse gases are considered the main factor influencing global warming and environmental degradation. The present study focuses on China, the world’s largest carbon emitter. The study aims to capture the time-frequency dependency of economic growth and CO₂ emissions in China for the time period 1950–2016 using a wavelet coherence approach, which allows us to investigate both the long-run and short-run causal links of the estimated variables. In order to capture the long-run and causal linkage between economic growth and CO₂ emissions, the study employs Maki cointegration, wavelet coherence, Toda-Yamamoto causality, Fourier Toda-Yamamoto causality, and nonparametric Granger causality tests. The findings of this study reveal that (i) there is a significant vulnerability between economic growth and CO₂ emissions throughout the 2000s both the short-term and medium-term; (ii) there is long-run cointegration linkage between economic growth and CO₂ emissions in China; (iii) economic growth in China has an important power for predicting CO₂ emissions over the selected study period, especially in the short-term and medium-term; and (iv) it was observed that there is positive correlation between economic growth during the 1980s and 1990s in the short-term only. The outcome of the Toda-Yamamoto causality, Fourier Toda-Yamamoto causality, and nonparametric Granger causality tests underlines that economic growth is a robust policy variable for predicting CO₂ emissions in China.

This study investigates the effects of lead (Pb) on earthworm Eisenia fetida and its potential to recover from Pb exposure. Adult earthworms E. fetida were exposed for 4 weeks to lead (40–2500 mg Pb kg⁻¹) in soil, and after the period of exposure, earthworms were transferred to clean unpolluted soil for 4 weeks to recover. Pb had no effect on the earthworm’s survival but inhibited earthworm growth; growth rate decreased with Pb concentration in the soil. During the recovery period, Pb pre-exposed earthworms did not manage to recover completely their growth. Lead had a highly significant effect on the malondialdehyde (MDA) concentration during both exposure and recovery periods. Pb showed concentration dependent toxicity relationships (weight, lipid peroxidation) for total earthworm Pb concentration. However, earthworm Pb bioconcentrations after recovery period could not explain the higher MDA concentration and lower earthworm fresh weight. Earthworms pre-exposed to low Pb levels have the potential to recover their growth and decrease Pb bioconcentrations, though more prolonged recovery period is needed to full recovery.

Nanoscale zero-valent iron–supported zeolite Na-P1 (Z-NZVI) was synthesized and technologically promoted for selenate (Se⁶⁺) removal from water. NZVI, Z, and Z-NZVI were characterized using XRD, FTIR, high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy (HR-TEM-EDS), and XANES techniques. Morphology and visualizing analysis using HR-TEM-EDS demonstrated that NZVI was uniformly distributed on the surfaces of Z in the Z-NZVI sample, which apparently reduced the aggregation of NZVI and would thereby increase the reduction activity. The Z-NZVI demonstrated higher efficiency for Se⁶⁺ removal since the high synergistic effect of Se⁶⁺ reduction and sorption by Z-NZVI. XANES analysis indicated that Z-NZVI could enhance Se⁶⁺ reduction into and selenium (Se⁰), while the adsorption phenomenon emerged on the Z-NZVI surface. Z performed as a supporter of the insoluble products, improving the reduction activity of NZVI. The high capacity of Z-NZVI provides promising technology for the removal of selenium from aqueous solutions.

Both polychlorinated biphenyls (PCBs) and cadmium (Cd) can be frequently found in marine ecosystems and have detrimental effects on marine organisms, especially on filter-feeding marine mussels. Although biological responses to single metal or PCB exposure in mussels have been well-studied, information about oxidative stress is still limited, especially in different tissues in mussels. Considering the variety of contaminants existing in the actual marine environment, the exposures of the marine mussel Mytilus coruscus to Cd²⁺ alone (0.194, 0.388, and 0.775 mg/L) and Aroclor 1254 alone (0.005, 0.010, and 0.050 mg/L) and the co-exposures of the marine mussel Mytilus coruscus to Cd²⁺ (0.194 and 0.388 mg/L) and Aroclor 1254 (0.005 and 0.010 mg/L) were tested in an 8-day exposure experiment followed by a 7-day acclimation experiment. The alterations in superoxide dismutase, catalase, glutathione peroxidase, and malondialdehyde levels in the gills of the mussels were assessed. The effects of the depressed antioxidant were induced by the exposures of Cd²⁺ and Aroclor 1254 and their co-exposures. All exposures resulted in an initial increase and then a reduction in antioxidant enzyme activities. The range and rate of the antioxidant enzyme activities were positively correlated with stress duration and the concentration of the stress material. The effect of combined stress was stronger than that of each individual stressor. The valuable information for future investigations of stress response mechanisms, especially in relation to tissue functions in marine organisms, has been provided by the results and experimental model. The study of combined pollution effects has more scientific significance for marine pollution monitoring.

Cementitious materials are commonly used to reinforce the bearing capacity of silty soils. However, there is very little data about how changes in arsenic (As) leaching from silty soils caused by the addition of cementitious materials. Therefore, batch leaching tests were conducted using As-bearing silty soil under different pH conditions. The pH was adjusted by changing the amount of slag cement added or the concentration of sodium hydroxide. This allows us to evaluate the effects of cement on As leaching. In addition, two different additives were applied to reduce As migration. The results show that high concentration of calcium ion (Ca²⁺) in leachates of soil-cement mixture has a significant effect in reducing the mobility of As even under hyperalkaline pH conditions. Arsenic immobilized by Ca²⁺ was observed in two patterns. The first mechanism was the help of Ca²⁺ to reduce the negative electrical potential on the surface of (hydr)oxide minerals under high pH conditions, thereby reducing the mobility of As by adsorption and coagulation of fresh precipitates of Fe and Al hydroxides. The second was the precipitation of calcium carbonate. This precipitate either directly adsorb/co-precipitate As or lower the concentration of strong competing ion, silica, both of which reduced the As mobility. When Ca- or Mg-based additive was added to the silty soil-cement mixture, As concentration in the leachate decreased. These findings are useful in developing sustainable soil-cement reinforcement techniques to avoid contamination.