The most dangerous pollution sources are intensive agricultural activity and livestock farming, whose production waste has a negative impact on soil and water quality. Livestock farming is separated into two systems: indoor (pigs and poultry) and pasture-based (livestock and sheep). Numerous studies aimed at elucidating how different systems affect the environment have been performed. In Lithuania, the biggest environmental problems are caused by 24 farms with more than 5000 pigs, 21 poultry farm with more than 1000 chickens, 2179 cow-cattle farms larger than 50 places, and about 200,000 sheep. We aimed to assess the quality of surface water in the Kaunas region next to the pig and livestock farms. In 2008–2017, seven livestock agricultural companies and seven larger farmers were regarded as potential sources of pollution in the Kaunas region. Half of these sources were pig farms, and the rest were livestock farms. Locations next to potential agricultural pollution sources were chosen to monitor the surface water. The results indicated that although the agricultural areas, number of livestock units, and nitrogen rate per 1 ha were similar between the pig and livestock farms, the activity on the pig farms affected the surface water quality more than that on livestock farms. As the number of livestock units (LU) increased on the farms, the pH decreased and the suspended materials, nitrates, and phosphates increased in the surface water. With increasing nitrogen kg/ha, the pH values decreased, thereby yielding more acidic water. The intensity of agricultural activity did not affect the water quality near the livestock farms, except for livestock units (LU), which affected the pH.

Biodiesel appears to be a possible substitute for non-renewable fossil fuels; however, its production requires the presence of a catalyst to accelerate the reaction. Serving the purpose of finding effective, cheap and environmentally safe, heterogeneous catalysts, this research used the fig leaves in three different forms, calcined, activated by KOH, and activated by both K₂CO₃ and CaCO₃. Their efficiency in biodiesel synthesis, from spent cooking oil, was examined and compared with that of activated carbon which has been previously investigated. The properties of different catalyst forms were specified using X-ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy. Operating parameters studied for the three catalysts were reaction time (from 30 to 180 min), alcohol-to-oil molar ratio (from 4:1 to 10:1), catalyst loading (from 0.5 to 5% by wt.), and stirring speed (from 100 to 400 rpm). The increase in reaction time, molar ratio, and catalyst loading proved to have a favorable effect on % conversion to biodiesel but to a certain degree; increasing the stirring speed augmented the conversion. At optimum conditions (2 h of heating, 6:1 alcohol-to-oil molar ratio, 1% by wt. catalyst loading, and 400 rpm stirring), fig leaves activated by KOH provided the highest conversion to biodiesel (92.73%). The measured properties of the produced biodiesel (density, viscosity, flash point, cloud point, and pour point) yielded encouraging results. Graphical Abstract

The importance of sustainable tourism in environmental literature is well documented, while there is a need to explore its different socio-economic and environmental factors that are helpful to promote sustainable development across countries. The objective of the study is to investigate the relationship between international tourism (ITOUR), energy demand (ED), carbon dioxide emissions (CO₂), and economic growth (EG) by using a panel data of top 10 tourism-induced countries for the period of 1995–2016. The findings confirmed the Environmental Kuznets Curve (EKC) hypothesis in the panel of top 10 countries. Moreover, the results show that FDI inflows negatively influenced natural environment in the form of high mass carbon emissions, which supported “pollution haven hypothesis (PHH).” The energy demand escalates carbon emissions across countries. The study confirmed the feedback relationship between (i) tourism income (TI) and ED, and (ii) CO₂ emissions and international tourism departures (ITD), while study supported the growth-led tourism income across countries. The study concludes that government(s) should have to focus on ecotourism policies and energy resources in a way to mitigate carbon emissions that is imperative for sustainable development across countries.

The number of restaurants is increasing rapidly in recent years, especially in urban cities with dense populations. Particulate matter emitted from commercial and residential cooking is a significant contributor to both indoor and outdoor aerosols. The PM₂.₅ emission rates and source profiles are impacted by many factors (cooking method, food type, oil type, fuel type, additives, cooking styles, cooking temperature, source surface area, pan, and ventilation) discussed in previous studies. To determine which cooking activities are most influential on PM₂.₅ emissions and work towards cleaner cooking, an experiment design based on multi-factor and level orthogonal tests was conducted in a laboratory that is specifically designed to resemble a professional restaurant kitchen. In this cooking test, four main parameters (the proportion of meat in ingredients, flavor, cooking technique, oil type) were chosen and five levels for each parameter were selected to build up 25 experimental dishes. Concentrations of PM₂.₅ emission rates, organic carbon/elemental carbon (OC/EC), water-soluble ions, elements, and main organic species (PAHs, n-alkanes, alkanoic acids, fatty acids, dicarboxylic acids, polysaccharides, and sterols) were investigated across 25 cooking tests. The statistical significance of the data was analyzed by analysis of variance (ANOVA) with ranges calculated to determine the influence orders of the 4 parameters. The PM₂.₅ emission rates of 25 experimental dishes ranged from 0.1 to 9.2 g/kg of ingredients. OC, EC, water-soluble ions (WSI), and elements accounted for 10.49–94.85%, 0–1.74%, 10.09–40.03%, and 0.04–3.93% of the total PM₂.₅, respectively. Fatty acids, dicarboxylic acids, n-alkanes, alkanoic acids, and sterols were the most abundant organic species and accounted for 2.32–93.04%, 0.84–60.36%, 0–45.05%, and 0–25.42% of total PM₂.₅, respectively. There was no significant difference between the 4 parameters on PM₂.₅ emission rates, while a significant difference was found in WSI, elements, n-alkanes, and dicarboxylic acids according to ANOVA. Cooking technique was found to be the most influential factor for PM₂.₅ source profiles, followed by the proportion of meat in ingredients and oil type which resulted in significant difference of 183.19, 185.14, and 115.08 g/kg of total PM₂.₅ for dicarboxylic acids, n-alkanes, and WSI, respectively. Strong correlations were found among PM₂.₅ and OC (r = 0.854), OC and sterols (r = 0.919), PAHs and n-alkanes (r = 0.850), alkanoic acids and fatty acids (r = 0.877), and many other species of PM₂.₅.

Air pollutants and allergens are the main stimuli that have considerable effects on asthmatic patients’ health. Seamless monitoring of patients’ conditions and the surrounding environment, limiting their exposure to allergens and irritants, and reducing the exacerbation of symptoms can aid patients to deal with asthma better. In this context, ubiquitous healthcare monitoring systems can provide any service to any user everywhere and every time through any device and network. In this regard, this research established a GIS-based outdoor asthma monitoring framework in light of ubiquitous systems. The proposed multifaceted model was designed in three layers: (1) pre-processing, for cleaning and interpolating data, (2) reasoning, for deducing knowledge and extract contextual information from data, and (3) prediction, for estimating the asthmatic conditions of patients ubiquitously. The effectiveness of the proposed model is assessed by applying it on a real dataset that comprised of internal context information including patients’ personal information (age, gender, height, medical history), patients’ locations, and their peak expiratory flow (PEF) values, as well as external context information including air pollutant data (O₃, SO₂, NO₂, CO, PM₁₀), meteorological data (temperature, pressure, humidity), and geographic information related to the city of Tehran, Iran. With more than 92% and 93% accuracies in reasoning and estimation mechanism, respectively, the proposed method showed remarkably effective in asthma monitoring and management.

The ecotoxicological characterization of waste according to the European Waste List (HP14) is part of its hazard classification, which is based on 15 different hazardous properties and should include toxicity tests representing the aquatic and terrestrial compartment. Besides established soil toxicity tests with bacteria, plants, and earthworms, the standardized test with the nematode Caenorhabditis elegans (ISO 10872:2010) is suitable for testing soils and wastes, however, has never been validated for the purpose of waste toxicity assessment. Therefore, 23 different waste samples were tested for their toxicity on growth and reproduction of C. elegans to validate the suitability of ISO 10872 (ISO 2010) for assessing the ecotoxicological hazard of waste and to compare the results with those of other ecotoxicological test systems. C. elegans showed a comparable response to the waste samples as the earthworm avoidance test, however, with single samples where the nematodes indicated a higher toxicity than the E. fetida, thus, providing non-redundant information to the ecotoxicological hazard assessment of wastes. Also due to the short duration (4 days) and small-scale test set-up, the soil toxicity test with C. elegans turned out to be a valuable addition to already existing test batteries, for assessing the ecotoxicity of wastes in the soil compartment.

The effect of air staging strategies on NOₓ control was investigated on a 210-kW small-scale biomass boiler (SBB) and a 1.4-MW medium-scale biomass boiler (MBB). Considering the de-NOₓ effect, as well as the convenience and economy for future wide use, the structures of the secondary air duct and the fuel feed tube were innovatively designed to solve the problems of the traditional prototype. The preliminary experiment showed that the lowest NOₓ emission was achieved when the air excess (ε) was equal to 2.04. Then, additional operating modes were conducted on the MBB to further optimize the air staging strategies. The optimal air staging strategy of the MBB (the secondary to primary air flow ratio (λ) and the ε were equal to 0.13 and 0.76, respectively) could decrease the NOₓ emission from 338.12 to 148.14 mg/m³. Furthermore, the SO₂ emissions and the lowest NOₓ emission of the SBB and the MBB could meet most emission standards of China and some developed countries. The thermogravimetric analysis (TG) and combustion characteristics of the wood fuel showed that the air staging was a suitable de-NOₓ technology for wood combustion, and the slagging was less likely to occur under the selected condition. Hence, the air staging technology was an effective and low-cost method for the emission reduction of biomass boilers. This study provided a practical basis for future research on the gas emission control of biomass boilers.

Fermentation slurry from food waste (FSFW) produced at different temperatures (20, 37, and 55 °C) was utilized as external carbon source for promoting nitrogen removal in this study. It was found that high temperatures improved the hydrolysis rate by promoting the hydrolytic enzyme activity. Mesophilic temperature (37 °C) was favorable for organic acid (especially lactic acid) production by selectively enriching the Lactobacillus (with a relative abundance of 90.6%), while thermophilic temperature (55 °C) would restrict the acidogenesis rate (18.9%) and result in the accumulation of carbohydrate in the fermented slurry. Organic acids in the FSFW act as easily biodegradable carbon sources, but the macromolecular and particulate organic components can be utilized as slowly biodegradable carbon sources in the denitrification processes. Using the FSFW as carbon sources to enhance nitrogen removal from wastewater in sequencing batch reactors (SBRs) for more than 150 days, the FSFW produced at thermophilic temperature could significantly promote the microbial metabolic capacity of the activated sludge and improve the nitrogen and phosphate removal efficiencies.

Soil contamination with heavy metals is a global issue confronting the environmental pollution and human/animal health. Much work has been done on physiological and antioxidant responses of wheat in hydroponic experiments and health risks from individual heavy metal contamination to human, but limited information is available on their combined application in soil. Therefore, this pot study delineates the uptake of lead and cadmium, as well as physiological responses of wheat and associated health risks under different levels of alone and combined Cd and Pb treatments. Metal uptake increased with their increasing applied levels. The highest Cd (4.24, 1.38, and 0.92 mg kg⁻¹) and Pb (763.33, 39.63, and 16.35 mg kg⁻¹) concentrations in root, shoot, and grain, respectively, were observed at highest applied levels (0.4 mM Cd and 10 mM Pb). Furthermore, all the treatments increased lipid peroxidation and activities of superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, while decreased total chlorophyll contents and membrane stability index. Under combined application of Cd and Pb, the toxicity and detoxification responses of wheat increased compared to alone treatments. Multivariate analysis further confirmed the toxicity and accumulation pattern of metals under alone and combined treatments. Target hazard quotient values of Cd and Pb were < 1 under alone and combined treatments. The health hazard index values of Pb (97.07 and 87.89%) were higher than those of Cd (2.93 and 12.10%) in combined application for human and buffalo, respectively. This study highlights that the multi-metal contamination (Cd and Pb) is detrimental for wheat growth and human/animal health.

In recent years, concerns over the issue of air pollution have increased as one of the significant environmental and health problems. Air pollutants can be toxic or harmful to the life of plants, animals, and humans. Contrast to primary pollutants, ozone is a secondary pollutant that is produced by the reaction between primary precursors in the atmosphere. The average of air pollutant data was compiled for the purpose of analyzing their correlation with the pulmonary function of students and the FENO biomarker from the air pollutants of the Environmental Protection Agency. According to the average of 3 days, the concentration of ozone in the (S₃) region was higher than the other regions, and this level was significantly different from the ANOVA test (p < 0.05). The results of artificial neural network modeling for three particular combinations in the cold season, two hidden layers with 9 and 12 neurons, with R² = 0.859 and in the warm season, layer with 13 neurons, with R² = 0.74, showed the best performance.