Inorganic pollutants are continuously introduced into the atmosphere. Bioindicators present an alternative method of monitoring air quality. This work proposes to evaluate the Mangifera indica L. leaves as a biomonitor for air quality. Quantification of aluminum (Al), barium (Ba), calcium (Ca), chromium (Cr), copper (Cu), iron (Fe), potassium (K), manganese (Mn), magnesium (Mg), sodium (Na), nickel (Ni), sulfur (S), strontium (Sr), titanium (Ti), and zinc (Zn) were determined in leaves of M. indica using optical emission spectrometer inductively coupled plasma (ICP-OES). The correlogram analyses demonstrated a strong positive correlation between Al and Fe. Contamination of the soil by vehicles and agricultural chemicals, in synergy with the influence of the winds, may be considered as a source of contamination. Enrichment factor (EF) index was used to distinguish between natural and anthropogenic sources. Detection of Mn and Cu could be associated with anthropogenic influence, demonstrating M. indica as a feasible tool to biomonitor air quality.

Activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in soil samples collected at Mount Rainier National Park and Satsop Nuclear Power Plant zone in State of Washington (USA) and Curonian Spit National Park and Ignalina Nuclear Power Plant zone in Lithuania have been measured by gamma spectrometry. The results have been compared with the worldwide measured average values reported by the UNSCEAR. Higher activity concentrations of ¹³⁷Cs were found in Curonian Spit National Park due to Chernobyl accident fallout. The radium equivalent activity (Raₑq), the external hazard index (Hₑₓ), the internal hazard index (Hᵢₙ), the absorbed dose rate (D), and the annual effective dose rate (AEDR) were also calculated and compared with the international recommended values. These calculated hazard indices used to estimate the potential radiological health risk in soil and the dose rate associated with it are below their permissible limit.

Respiratory quotient (RQ) is a parameter proposed as a tool for practical and online monitoring of petroleum hydrocarbon biodegradation. Various environmental factors and remediation conditions affect RQ values. Occasionally, actual RQ values deviate from theoretical RQ values of petroleum hydrocarbon biodegradation. In addition, different RQ calculation and interpretation approaches investigated in literature make it difficult to compare the results. In this study, different RQ calculation and interpretation methods given in the literature were compared and the effects of nitrogen biostimulation with ammonium and nitrate salts on RQ values of petroleum hydrocarbon biodegradation were investigated. Respirometric reactors were used in bioremediation of diesel fuel–contaminated soils. Ammonium sulfate and potassium nitrate were amended to enhance hydrocarbon biodegradation. Total n-alkane levels in the soils were analyzed after the incubation period. RQ values were calculated based on continuous CO₂ and O₂ measurements. Biostimulation with ammonium and nitrate led to significant contaminant biodegradation. The nitrogen source type affected RQ values significantly. It was concluded that in evaluating hydrocarbon biodegradability properties and interpreting biostimulation properties, the use of graphical RQ evaluation methods that include plotted statistical approaches allows access to more useful information than using individual theoretical RQ values.

In this paper, the removal of total organic carbon (TOC) from a primary treated municipal wastewater using a new electrode configuration in electrocoagulation was evaluated. The used electrode configuration induces a dielectrophoretic (DEP) force by using an asymmetrical aluminum electrode with an alternating current power supply. The impact of applied current, electrolysis time, and interelectrode distance on the removal efficiency of TOC were evaluated. The experimental results showed that the maximum removal efficiency of TOC was obtained at 30 min electrolysis time, 600 mA applied current, and 0.5 cm interelectrode distance. Under these operating conditions, the TOC removal was 87.7% compared to 80.5% using symmetrical aluminum electrodes with no DEP effect. The energy consumption at the selected operating conditions was 3.92 kWh/m³. The experimental results were comparable with the simulation results done by COMSOL Multiphysics software.

Green roof (GF) as an important role of urban ecosystem services is more and more focused on carbon sequestration for the mitigation of climate change, which there is still a gap of longer period of investigation on carbon sequestration on GF. This work aims to quantify the carbon sequestration on green roofs from 2012 to 2017 by measuring and calculating parameter on substrate organic carbon and plant organic carbon, when using waste building material substrate (WBMS) as GF substrate for the recycling of waste solid. Green roof group 2 (waste building material substrate (WBMS) as substrate) and green roof group 1 (local natural soil (LNS) as substrate), planting same three native plants (N. auriculata, L. spicata, and L. vicaryi), were both three substrate depth of 20 cm, 25 cm, and 30 cm, respectively. Results show that both innovative WBMS and LNS were a great capability of carbon sequestration and carbon storage on green roofs. Carbon storage of green roof group 1 and green roof group 2 was 65.6 kg C m⁻² and 72.6 kg C m⁻², respectively. Annual mean carbon sequestration of the WBMS was 1.8 times higher than LNS. The overall average carbon sequestration (12.8 kg C m⁻² year⁻¹) in green roof group 2 using WBMS was 1.1 times than corresponding in green roof group 1 (11.4 kg C m⁻² year⁻¹ using LNS). WBMS substrate and L. vicaryi could be considered as the most adaptable green roof configuration, which can be a recommendation to promote the carbon sequestration and the function of green roof for the better urban ecosystem services. Future work may focus on the GF carbon model, water interface, long-term monitoring, environmental impact, water quality and quantity, synthesized effect on GF ecosystem, low impact development (LID), management and simulation, and combination on intelligent urban system, based on LCA.

The relationship between tourism development, economic growth, renewable energy consumption, and carbon dioxide emissions has been examined in a variety of contexts; however, the extant studies report contradictory findings mainly due to utilizing arbitrary empirical techniques. We present a comprehensive literature review and the effects of tourism development, economic growth, and renewable energy consumption on the carbon dioxide (CO₂) emission. Specifically, the effects of gross domestic product, renewable energy consumption, and tourism receipts on carbon dioxide emissions in OECD countries are examined utilizing the bootstrap panel cointegration technique and the augmented mean group estimator. The results showed that tourism development has negative and significant effects on CO₂ emission in Canada, Czechia, and Turkey, while tourism development has positive and significant effects on CO₂ emission in Italy, Luxembourg, and the Slovak Republic. Also, Belgium, France, New Zealand, and the Slovak Republic have shifted towards sustainable tourism practices. Theoretical and practical implications are discussed.

Nitrate nitrogen in water, especially in groundwater, is a major problem in the current drinking water environment. In this study, copper- and nickel-modified phosphotungstate catalysts supported on TiO₂ were prepared by the sol-gel solvothermal method, and photocatalytic reduction by phosphotungstate was used to remove nitrate nitrogen in water under ultraviolet irradiation. The maximum removal rate was 59.60% with 0.8 g/L Cu-H₃PW₁₂O₄₀/TiO₂, 90 mg/L nitrate nitrogen, and 60 min reaction time. For Ni-H₃PW₁₂O₄₀/TiO₂, the maximum removal rate of nitrate nitrogen was 54.58%, achieved with a catalyst concentration of 0.8 g/L, nitrate nitrogen concentration of 120 mg/L, and reaction time of 30 min. Both catalysts could remove nitrate nitrogen from water under the condition of photocatalysis.

In the developing world, rapid urbanization and industrialization produces an enormous volume of wastes daily. This study was aimed to explore the potential and risks associated with sewage sludge through the characterization and fractionation technique. Sewage sludge samples were collected from various wastewater treatment in five different cities of Pakistan. Considerable amounts of macro-elements were detected in all types of sewage sludge samples. The pHw of all sewage sludge were neutral to slightly alkaline in reaction. Total organic carbon (TOC) was maximum (18.73%) with Coca-Cola sewage sludge (CSS) while the minimum (14.69%) was with Water and Sanitation Agency (WASA) sewage sludge (WSS). Percent relative distribution of cadmium (Cd) was higher in residual fraction (F4) up to 52% in the Nestle wastewater treatment plant, Sheikhupura (NSS). The chromium (Cr) concentration in Kasur sewage sludge (KSS) was extremely in mobile fraction (exchangeable) as compared with all other sludge samples, therefore showing a higher level of risk assessment code. While in the case of Iron (Fe), mobility was less and its maximum portion was noted in residual fraction (F4) of all sewage sludge samples. Percent distribution of manganese (Mn) showed variable trends for different sewage sludge samples. Zinc (Zn) concentration showed high mobility (exchangeable fraction) in case of NUST wastewater treatment plant, Islamabad (NTS) (31.16%) and WSS (37.83%) as compared with other sewage sludges. The risk assessment code indicated that Zn and Ni had a medium level of risk with I-9 Sector wastewater treatment plant, Islamabad (ISS), CSS, KSS, and NSS whereas these pose a high risk with NTS and WSS. Based on physicochemical properties, nutrients, trace elements, mobility, and risk assessment code, it was concluded that KSS should not be recommended at any application rate while NTS and WSS may be used at low application rates whereas ISS, CSS, and NSS may be used for agricultural crop production.

Roxarsone (ROX) and copper (Cu) are growth promoters in livestock to promote growth and prevent disease. These chemicals and their metabolites are released to the soil through manure application and have a potential adverse effect on soil-dwelling organisms. The objective of this study was to investigate the combined subacute effect of ROX exposure (0, 80, 240, 720 mg kg⁻¹) and Cu exposure (0, 80, 160 mg kg⁻¹) in earthworms (Eisenia fetida). Growth, reproduction, spermatogenesis under light microscope, and heavy metal residue were investigated during 56-day exposure period. Results showed that Cu exposure of 80 or 160 mg kg⁻¹ alleviated the effect of ROX on cocoon production or hatching. The cocoon number exhibited an increase (P < 0.05) at 80 mg kg⁻¹ ROX on day 28, compared with the 0 mg kg⁻¹ ROX, in the presence of 80 mg kg⁻¹ Cu, whereas there was no effect (P > 0.05) in the presence of 160 mg kg⁻¹ Cu. The hatching success at 80 or 240 mg kg⁻¹ ROX exhibited a decrease (P < 0.05) on day 28, in the absence of Cu, whereas no effect (P > 0.05) was observed in the presence of 80 or 160 mg kg⁻¹ Cu. The other reproductive parameters (cocoon weight, juvenile number, and biomass) demonstrated a decrease (P < 0.05) only at 720 mg kg⁻¹ ROX in the presence or absence of Cu. However, with increasing exposure time, the above reproductive parameters were not affected (P > 0.05) in all groups on day 56. On the other hand, sperm deformity (%) increased (P < 0.05) at 240 or 720 mg kg⁻¹ ROX on day 28, in the presence or absence of Cu; however, the microstructural alteration in seminal vesicles occurred only at 720 mg kg⁻¹ ROX, exhibiting disordered distribution and decreased mature sperm bundles. In addition, ROX or Cu residues in earthworms demonstrated an increase with increasing ROX or Cu exposure concentration. Our present results may provide important insight on combined toxicity of chemicals in soils.

Due to the increase of cadmium (Cd)-contaminated land area worldwide, effective measures should be taken to minimize the Cd bioavailability in crops. A study was performed to explore the effectiveness of biochar pyrolyzed from rice straw at 400 °C alone or combined with AM fungi (Funneliformis mosseae) on the corn growth and Cd uptake in corn in Cd-contaminated soil with different levels of phosphorus supplies. The results showed that biochar significantly reduced 66% and 38% of Cd uptake in shoot and root respectively (P < 0.001) attributed to the increase of soil pH and dissolved organic matter. In contrast, AM fungi inoculation of corn plants had little effect on Cd bioavailability due to the AM was suppressed by the highly contaminated acid soil (31.76 mg/kg), and had neither synergistic effect with biochar on decreasing the Cd bioavailability with high or low phosphorus supplies. This study demonstrated that biochar application could be a promising method to immobilize Cd in the contaminated soil to ensure the safety of agro-product while high Cd-contaminated soil would suppress the growth of mycorrhizae, so this remains an open question to be further studied.