High Pollutant Concentrations Research Articles

Adsorption properties of Pb(II) and Cd(II) in acid mine drainage by oyster shell loaded lignite composite in different morphologies

A new idea to alleviate environmental pollution is the development of low-cost adsorbents using natural minerals and fishery wastes to treat high concentrations of heavy metal pollutants in acid mine drainage (AMD). Adsorbent morphology, adsorptive and regenerative capacity, and application potential are limiting factors for their large-scale use. Oyster shells capable of releasing alkalinity were loaded on the surface of lignite to develop two composite adsorbents with different morphologies (powdery and globular) for the treatment of AMD containing Pb(II) and Cd(II). The results show that the ability of the adsorbent to treat AMD is closely related to its morphologies. The pseudo-second-order kinetic model and the Langmuir model are suitable to describe the adsorption process of OS-M(P), and the maximum adsorption saturation capacities of Pb(II) and Cd(II) are 332.6219 mg/g and 318.9854 mg/g, respectively. The pseudo-second-order kinetic model and the Freundlich model are suitable to describe the adsorption process of OS-M(G). A synergistic result of electrostatic adsorption, neutralization precipitation, ion exchange and complex reaction is achieved in the removal of Pb(II) and Cd(II) by two morphologies of adsorbents. The regeneration times (5 times) and recovery rate (75.75%) of OS-M(G) are higher than those of OS-M(P) (3 times) and recovery rate (20%). The ability of OS-M(G) to treat actual AMD wastewater is still better than that of OS-M(P). OS-M(G) can be used as a promising environmentally friendly adsorbent for the long-term remediation of AMD. This study provides a comprehensive picture of resource management and reuse opportunities for natural mineral and fishery wastes.

Culturable Bioaerosols Assessment in a Waste-Sorting Plant and UV-C Decontamination

Waste-Sorting Plant (WSP) workers are exposed to bioaerosols containing a large variety of bacterial and fungal species, posing a critical health risk that needs to be assessed and mitigated. The present study aimed to evaluate the indoor air quality in a Portuguese WSP and the air decontamination efficiency with UV-C. The concentrations of bacteria and fungi and particulate matter (PM2.5 and PM10), CO2, relative humidity, and temperature were determined at different hours in manual sorting areas (cabin and ramp) in autumn and winter in 2022 and in administrative offices and canteen in the autumn of 2023. The PM2.5 and PM10 concentrations in the air increased with the daily waste-sorting activities, especially inside the cabin, averaging 22 and 42 μg/m3, respectively, while the CO2 concentration was in the range of 343–578 ppm in both sampling sites. The bacterial species were mainly environmental (mesophilic bacteria) rather than human sources. In the waste-sorting areas, the concentration of bacteria was often found to exceed outdoor values by more than 1000 CFU/m3 on average. Additionally, the concentration of fungi indoors was consistently higher than outdoor values, in many cases exceeding 500 CFU/m3. These findings suggest that workers in these areas are frequently exposed to high levels of microbes. The indoor-to-outdoor (I/O) contamination ratios revealed that the air quality inside the administrative offices and the canteen had high pollutant concentrations during some time periods. The worst scenarios were observed in the canteen and offices with high occupancy in the afternoon. UV-C lamps at 253.7 nm and with 5.0 W irradiation power were used in the sorting cabin to test the indoor air and surface decontamination, and the results showed a high bacterial removal efficacy of over 87.6% after one hour of exposure to UV-C. The present study raises the question of whether 37 °C is the optimal incubation temperature for WSP samples since the microorganisms’ habitat before the sampling had a much lower temperature. As the waste-sorting industry expands, these findings show that the air quality of WSPs remains concerning and requires a holistic approach, integrating the working conditions of all personnel and the implementation and monitoring of mitigation measures.

Weak geostrophic wind driven ventilation in street canyons with trees and green walls: Cooperating or opposing dispersions of airborne pollutants?

Urban high-rise buildings and dense street canyons significantly disrupt synchronised wind flows, potentially exacerbating urban heat island effect. Fortunately, urban heat island effect can be mitigated by the green infrastructure in cities, particularly through the presence of roadside trees and green walls. However, the combined mechanisms of tree resistance, shading effects, and cooling effect, along with sensible thermal buoyancy flows within canyon ventilation and pollution dispersion, remain undisclosed. This study employs refined computational fluid dynamics numerical simulations to analyse airflow and pollutant dispersion within urban street canyons. Air exchange rate and pollutant retention time are employed to evaluate ventilation and pollutant dispersion, respectively, inside the street canyons.In scenarios with leeward green wall layout, higher tree canopy spread and trunk height lead to a shift in high pollutant concentrations from the region near the windward side to that near the leeward side of the typical canyon (H/W = 1). Conversely, in deep canyons (H/W = 5), most pollutants are retained near the bottom leeward side. Moreover, differences in pollutant dispersion between typical and deep canyons increase with with rising tree canopy spread. Additionally, higher tree canopy spread and trunk height values result in longer pollutant retention time, which are unfavourable for pollutant removal, and particularly limiting pollutant dispersion as street canyon depth increases. Similarly, increasing tree canopy spread reduces the difference in air exchange rate between windward and leeward green wall layout patterns. Regarding Richardson number variations —indicating thermal buoyancy effects—lower Richardson number values lead to reduced differences in pollutant retention time between typical and deep canyons. Furthermore, ventilation performance of the windward green pattern surpasses that of the leeward pattern. This research provides valuable insights for implementing green infrastructure to locally mitigate urban air pollution.

Effects of extreme meteorological factors and high air pollutant concentrations on the incidence of hand, foot and mouth disease in Jining, China.

The evidence on the effects of extreme meteorological conditions and high air pollution levels on incidence of hand, foot and mouth disease (HFMD) is limited. Moreover, results of the available studies are inconsistent. Further investigations are imperative to elucidate the specific issue. Data on the daily cases of HFMD, meteorological factors and air pollution were obtained from 2017 to 2022 in Jining City. We employed distributed lag nonlinear model (DLNM) incorporated with Poisson regression to explore the impacts of extreme meteorological conditions and air pollution on HFMD incidence. We found that there were nonlinear relationships between temperature, wind speed, PM2.5, SO2, O3 and HFMD. The cumulative risk of extreme high temperature was higher at the 95th percentile (P95th) than at the 90th percentile(P90th), and the RR values for both reached their maximum at 10-day lag (P95th RR = 1.880 (1.261-2.804), P90th RR = 1.787 (1.244-2.569)), the hazardous effect of extreme low temperatures on HFMD is faster than that of extreme high temperatures. The cumulative effect of extreme low wind speeds reached its maximum at 14-day lag (P95th RR = 1.702 (1.389-2.085), P90th RR = 1.498(1.283-1.750)). The cumulative effect of PM2.5 concentration at the P90th was largest at 14-day lag (RR = 1.637 (1.069-2.506)), and the cumulative effect at the P95th was largest at 10-day lag (RR = 1.569 (1.021-2.411)). High SO2 concentration at the P95th at 14-day lag was associated with higher risk for HFMD (RR: 1.425 (1.001-2.030)). Our findings suggest that high temperature, low wind speed, and high concentrations of PM2.5 and SO2 are associated with an increased risk of HFMD. This study not only adds insights to the understanding of the impact of extreme meteorological conditions and high levels of air pollutants on HFMD incidence but also holds practical significance for the development and enhancement of an early warning system for HFMD.

When the use of derived wastes and effluents treatment is part of a responsible industrial production: A review

Effluents derived from industrial production can contain pollutants as oils, dyes, plaguicides, emerging organic pollutants, detergents, disinfectants, and toxic metals. The presence of high concentrations of pollutants in effluents makes them an important source of environmental pollution. To solve this problem, various technologies have been developed for the treatment of industrial effluents. Currently, sustainable industrial production and the wastes reuse is of great importance for the economic development and environmental countries protection. This review initially proposes an introduction to sustainable industrial production, its foundations and aspects related to the circular economy and the process intensification. Current trends in waste reuse in Latin America are presented. In addition, the latest advances on the technologies used for effluents treatment are commented and discussed, considering the different sustainability indicators. The contributions reported in this manuscript demonstrated the efficiency of eliminating pollutants present in industrial effluents, reaching removal percentages of pollutants from 20 to 100 %. Finally, it is important to mention that the applied technologies are useful not only for the decontamination of an industrial effluent and the environmental care but also for the possibility of give an additional use to these resources considering the water shortage present in many parts of Latin America.

Analyses of industrial air pollution and long-term health risk using different dispersion models and WRF physics parameters

AbstractThis study consists of three main sections. The first section delves into a performance analysis centered around modeling PM10, NOx, and CO emissions from a cement factory. It examines the effectiveness of various factors, including meteorological data, physics models, and air quality dispersion models, in producing accurate results for atmospheric simulations. The second section covers the dispersion direction and concentrations obtained by visualizing the dispersion maps. The third section covers an analysis of heavy metals emitted from the facility, taking into account potential risks in the region such as cancer, acute and chronic effects, and long-term respiratory risks. This study made use of meteorological models (WRF, AERMET, and CALMET), air quality dispersion models (AERMOD and CALPUFF), a health risk analysis model (HARP), and various sub-models (MMIF and CALWRF). Satellite meteorological data were obtained from NCEP and ERA, with the majority of meteorological data based on the Global Data Assimilation System (GDAS)/Final Operational Global Analysis (FNL) from Global Tropospheric Analyses and Forecast Grids used for the WRF model. In the daily results, AERMOD showed the highest concentration values, but CALPUFF had greater concentrations throughout the annual period. The winter season had the highest concentrations of pollutants. Although there are differences among the physics models used in this research, the conclusions produced are consistent. Analysis of the data from the HARP model suggested that cancer risk levels exceeded the threshold of one person per million. However, the proportion of exceedance instances is rather small in comparison to the receptor points.

Trend in indices of public health risk caused by air pollution in an industrial center

Introduction. In industrialized regions and cities, atmospheric air pollution greatly contributes to the hazard for public health. The study aim was to assess the state of the atmospheric air in the city of Novokuznetsk over 2017–2022 and determine the levels of risks to public health. Materials and methods. Data on gross atmospheric emissions and average annual concentrations of the substances was taken from the reports on the state of the environment of the Kemerovo region and Novokuznetsk. Maximum permissible concentrations of atmospheric pollutants were determined according to SanPiN 1.2.3685–21. Calculations of the risks to public health were carried out in accordance with Guideline P 2.1.10.1920–04. The classification of risk levels was carried out on the basis of MR 2.1.10.0156–19. 2.1.10. Results. Decrease in total atmospheric emissions from 2017 to 2022 amounted to 50.1 thousand tons (about 16%). At the same time, there was revealed an excess of the average annual maximum permissible concentrations of benzo(a)pyrene (3.5-11.2 times); formaldehyde (1.7 and 3.4 times over 2021 and 2022, respectively); suspended substances (1.6 and 2.0 times in 2021 and 2022, respectively); hydrogen fluoride (1.2 times in 2021); nitrogen dioxide (1.6 times in 2022). The hazard coefficients of benzo(a)pyrene were 3.5–11.2 (high level of non-carcinogenic risk); formaldehyde and suspended substances – 1.1–3.0 (alarming level). In 2022, the hazard coefficient for formaldehyde was 3.4 (high risk level), suspended substances – 2.0, nitrogen dioxide – 1.6 (alarming risk level). Hazard indices of pollutants were detected in the range from 7.0 to 20.1 (high level of risk). The main critical organs and systems were the immune system (hazard indices were 4.0–14.6), development during childhood (hazard indices – 3.5–11.2), respiratory organs (hazard indices – 3.0–8.6). These risk levels range from alarming to high. The highest total individual carcinogenic risk (1.6•10–4) was determined in 2021 (alarming level), the main contribution is made by formaldehyde. Limitations. In 2022, there were no data on carbon (soot) concentrations, so the level of total carcinogenic risk this year cannot be considered to be correct. Conclusion. Reducing the total volume of atmospheric emissions does not provide a significant effect on improving the environmental situation and public health, since high concentrations of pollutants remain in the city’s atmosphere. When implementing air protection measures, it is necessary to take into account risk criteria.

Utilidad de los parásitos en el monitoreo ambiental

Air, water, and soil pollution represent a threat for the ecosystem and human health. To preserve a healthy environment, it is necessary to implement conservation strategies and carry out continuous ecosystem monitoring. Parasites, used as bioindi-cators, can help with this task. These organisms are key components of biodiversity, and their presence, absence, and diversity provide information about the health status of the ecosystems. Additionally, some of these organisms can be useful for detecting conta-minants in the environment, as they can accumulate high concentrations of chemical pollutants.

An integrated approach for sewage diversion: Case of the Huayuan mine, Hunan Province, China

Environment protection is a core priority for many governments in this century. Most environmental problems have diverse causes: emission of greenhouse gases from fossil fuels, resource depletion, or intense mining activities such as the Huayuan manganese mine. The positioning of mining factories and water treatment stations impacts the surrounding groundwater reservoir. As the mine expands, the environmental impact also increases, and the previous plan based on monitoring wastewater leakage has become inappropriate. Therefore, to solve this issue, a new study is required to understand the lateral resistivity distribution underground and to define a new station location for water treatment and divert the sewage to that station. In this study, the audio-frequency magnetotelluric method is used. Surveys of two long lines that cross the mining area to its boundaries are carried out. Data are robustly processed and inverted. Based on the inverted models, in addition to the geologic information, drilling inspections, and solid waste distributions map, the integrated interpretation develops two sites on the top of impermeable layers, which constitute a buffer point between the unsafe (high concentration of pollutants) and the safe zones in the northwestern part of the mine. From the resistivity distribution combined with the water quality analysis, a relationship between the fault structures reveals an interconnected conductive zone (CZ) in the southeastern part. As the main channels for water circulating underground, these CZs delineate the main groundwater reservoir with a clastic aquifer layer. However, close to factories, the water from faults contains solid wastes, thereby making the groundwater in that zone nonpotable, unlike the safety zone located in the northwestern part. This workflow can become a field guide to improve the environment of mines and the deployment of hydrogeologic drilling in a safe area.

Activation of stress reactions in the dinophyte microalga Prorocentrum cordatum as a consequence of the toxic effect of ZnO nanoparticles and zinc sulfate

According to the results of the experimental study, the main regularities of changes in morphological, structural-functional and fluorescent indices of P. cordatum were established when zinc oxide nanoparticles ZnO NPs (0.3–6.4 mg L−1) and Zn in form of salt (0.09–0.4 mg L−1) were added to the medium. The studied pollutants have cytotoxic (growth inhibition, development of oxidative stress, destruction of cytoplasmic organelles, disorganization of mitochondria) and genotoxic (changes in the morphology of nuclei, chromatin condensation) effects on microalgae, affecting almost all aspects of cell functioning. Despite the similar mechanism of action of zinc sulfate and ZnO NPs on P. cordatum cells, the negative effect of ZnO NPs is also due to the inhibition of photosynthetic activity of cells (significant decrease in the maximum quantum yield of photosynthesis and electron transport rate), reduction of chlorophyll concentration from 3.5 to 1.8 pg cell−1, as well as mechanical effect on cells: deformation and damage of cell membranes, aggregation of NPs on the cell surface. Apoptosis-like signs of cell death upon exposure to zinc sulfate and ZnO NPs were identified by flow cytometry and laser scanning confocal microscopy methods: changes in cell morphology, cytoplasm retraction, development of oxidative stress, deformation of nuclei, and disorganization of mitochondria. It was shown that the first signs of cell apoptosis appear at 0.02 mg L−1 Zn and 0.6 mg L−1 ZnO NPs after 72 h of exposure. At higher concentrations of pollutants, a dose-dependent decrease in algal enzymatic activity (up to 5 times relative to control) and mitochondrial membrane potential (up to 4 times relative to control), and an increase in the production of reactive oxygen species (up to 4–5 times relative to control) were observed. The results of the presented study contribute to the disclosure of fundamental mechanisms of toxic effects of pollutants and prediction of ways of phototrophic microorganisms reaction to this impact.

Adsorption–photocatalysis synergy of reusable mesoporous TiO2–ZnO for photocatalytic degradation of doxycycline antibiotic

The potentials of mesoporous TiO2–ZnO (3TiZn) were explored on photocatalytic degradation of doxycycline (DOX) antibiotic, likewise the influence of adsorption on the photocatalytic process. The 3TiZn was characterized for physical and chemical properties. Stability, reusability, kinetic and the ability of 3TiZn to degrade high concentration of pollutant under different operating conditions were investigated. Photocatalytic degradation of DOX was conducted at varied operating conditions, and the best was obtained at 1 g/L catalyst dosage, solution inherent pH (4.4) and 50 ppm of DOX. Complete degradation of 50 ppm and 100 ppm of DOX were attained within 30 and 100 min of the reaction time, respectively. The stability and reusability study of the photocatalyst proved that at the tenth (10th) cycle, the 3TiZn is as effective in the degradation of DOX as in the first cycle. This may be attributed to the fusion of the mixed oxides during calcination. The 3TiZn is mesoporous with a pore diameter of 17 nm, and this boosts it potential to degrade high concentration of DOX. It was observed that the adsorption capacity of 3TiZn enhance the photocatalytic process. It can be emphasized that 3TiZn portrayed a remarkable catalyst stability and good potentials for industrial application.

Ozone Exposure Limits Cardiorespiratory Function During Maximal Cycling Exercise in Endurance Athletes.

Ground-level ozone (O3) is a potent air pollutant well recognized to acutely induce adverse respiratory symptoms and impairments in pulmonary function. However, it is unclear how the hyperpnea of exercise may modulate these effects, and the subsequent consequences on exercise performance. We tested the hypothesis that pulmonary function and exercise capability would be diminished, and symptom development would be increased during peak real-world levels of O3 exposure compared to room air. Twenty aerobically trained participants [13M, 7F; maximal O2 uptake (O2max), 64.1 ± 7.0 mL·kg-1·min-1)] completed a three-visit double-blinded, randomized crossover trial. Following a screening visit, participants were exposed to 170 ppb O3 or room air (<10 ppb O3) on separate visits during exercise trials, consisting of a 25-minute moderate intensity warmup, 30-minute heavy intensity bout, and a subsequent time-to-exhaustion (TTE) performance test. No differences in O2 uptake or ventilation were observed during submaximal exercise between conditions. During the TTE test, we observed significantly lower end-exercise O2 uptake (-3.2 ± 4.3%, p=0.004), minute ventilation (-3.2 ± 6.5%, p=0.043), tidal volume (-3.6 ± 5.1%, p=0.008), and a trend towards lower exercise duration in O3 compared to room air(-10.8 ± 26.5%, p=0.092). As decreases in O2 uptake and alterations in respiratory pattern were also present at matched time segments between conditions, a limitation of oxygen transport seems likely during maximal exercise. A more comprehensive understanding of the direct mechanisms that limit oxygen transport during exercise in high-pollutant concentrations is key for mitigating performance changes.

Poly Meta-Aminophenol (PmAP) as a Solid-State Electron Mediator in the Z-Scheme, Ag3PO4/CoFe2O4 Heterojunction: Mineralization of Highly Concentrated Bisphenol-A and Reactive Dyes Water Pollutants.

This study demonstrated the effectiveness of poly meta-aminophenol (PmAP) as a solid electron mediator in the Z-scheme photocatalytic system for organic pollutants (viz. bisphenol-A and reactive dyes) mineralization and also illustrated how PmAP transported the photogenerated electrons from an O2-emitting photocatalyst (Ag3PO4) to a H2-emitting photocatalyst (CoFe2O4) enabling enhanced photocatalytic activity under visible light irradiation. The PmAP/Ag3PO4-CoFe2O4 (PAC-10), was prepared by a two-step process and characterized by various analytical methods to assess the impact of PmAP on optical, photocatalytic, and electrochemical characteristics of the CoFe2O4 (CFO)/Ag3PO4 composite. The morphological investigation revealed that the PmAP sheet was nicely decorated with evenly distributed Ag3PO4 and CoFe2O4 particles. The M-S plot and impedance analyses were used to assess the electrochemical capabilities of the catalyst. Z-scheme charge transfer pathways were well supported by the radical trapping experiment and HRTEM analysis of Pt photodeposited PAC-10 photocatalysts during the photoreaction. Because of its magnetic nature and ease of synthesis, the PAC-10 offers an easily recyclable Z-scheme photocatalytic system that has the potential for purifying wastewater with high concentrations (up to 100 mg/L) of organic pollutants within 30 min of visible light exposition.

Assessing the impact of air pollution on short-term hospital visits for respiratory diseases in Lampang, a city heavily affected by biomass burning in Mainland Southeast Asia: Sex and age considerations

Mainland Southeast Asia has long been confronted with severe air pollution issues caused by open biomass burning. The analysis is conducted from January 2014 to December 2017 in Lampang located in central of Mainland Southeast Asia. The analysis of air pollution revealed significant exceedances of the PM10 (32%) and O3 (29%) air quality guidelines set by the World Health Organization. The major source of PM10 in Lampang is biomass burning, accounting for 97%, and it also experiences a high respiratory disease incidence of 7,276.61 per 100,000 population. A time-series analysis was conducted using generalized linear models based on Poisson regression, considering various lag times, to assess the relative risk (RR) among all age groups (0–14 years, 15–64 years, ≥65 years) and genders. A 10 μg/m3 increase in PM10 and O3 was associated with statistically significant percentage increases at lag 0. Specifically, there was a 0.65% (95% CI: 0.38–0.92) increase in respiratory diseases for PM10 and a 0.72% (95% CI: 0.43–1.01) increase for O3. The impact of PM10 and O3 significantly affects respiratory diseases in children, adults, and the elderly. Elderly males and females both experience the highest impact of PM10, whereas the greatest impact of O3 is observed in elderly males and adult females. Biomass burning is a major source that should be controlled to reduce the health risk of people. Protecting vulnerable groups like adult females, elderly males, and elderly females from high air pollution concentrations is crucial, especially with many countries experiencing an aging demographic shift.

Application of Doppler sodar in short-term forecasting of PM10 concentration in the air in Krakow (Poland)

Abstract. This paper describes an attempt to use data obtained from sodar (sound detection and ranging) for short-term forecasting of PM10 concentration levels in Krakow. Krakow is one of the most polluted cities in central Europe (CE) in terms of PM10 concentration. This is due to the high municipal emissions. Thanks to intensive corrective actions taken by the city authorities, these are being effectively eliminated, but the unfavourable topographic location of the city limits natural ventilation. The article describes all these conditions, focusing on presenting the method of short-term correction of air quality for the time needed to take quick corrective actions by the city authorities in the event of anticipated exceedances of the permissible values. Based on several years of measurements of the physical properties of the atmosphere with sodar, the authors of the paper suggest that sodar data could be considered for operational use to generate short-term predictions. The proposed method is based on the use of the spectrum, i.e. the set of amplitudes of signals returning to the sodar receiver from the reflection of a single-frequency sound transmission and its characteristic properties depending on the physical state of the atmosphere. Similar spectra were parameterised with a single numerical value using statistical methods. It was found that, in some cases preceding high concentrations of PM10, the spectral parameters had similar values. This made it possible to develop a forecasting method for such concentrations by using data mining to search for conditions in historical data closest to the state of the atmosphere at the time of forecasting. In this part of the study, data from 2017–2018 were used. In the next step, three methods of using the sodar data developed for PM10 prediction were proposed, comparing them with the method without sodar use. The study results were tested on independent material using data concerning the episodes of high concentrations of pollutants from October 2021 to March 2022 in Krakow. The findings were considered to be encouraging, also taking into account the speed and low cost of preparing the forecast.

Effects of building envelope features on airflow and pollutant dispersion within a symmetric street canyon.

Building envelope features (BEFs) have attracted more and more attention as they have a significant impact on flow structure and pollutant dispersion within street canyons. This paper conducted CFD numerical models validated by wind-tunnel experiments, to explore the effects of the BEFs on characteristics of the airflow and pollutant distribution inside a symmetric street canyon under perpendicular incoming flow. Three different BEFs (balconies, overhangs, and wing walls) and their locations and continuity/discontinuity structures were considered. For each canyon with various BEFs, the air exchange rate (ACH), airflow patterns, and pollutant distributions were evaluated and compared in detail. The results show that compared to the regular canyon, the BEFs will reduce the ACH of the canyon, but increase the disturbances (the proportion of ACH') inside the canyon. The BEFs on the leeward wall have the least influence on the in-canyon airflow and pollutant distributions, followed by that on the windward wall. Then when the BEFs are on both walls, the ventilation capacity of the canyon is weakened greatly, and the pollutant concentration in the ground center is increased significantly, especially near the windward side. Moreover, the discontinuity BEFs will weaken the effect of the continuity BEFs on the in-canyon flow and dispersion, specifically, the discontinuity BEFs reduced the region of high pollutant concentration distributions. These findings can help optimize the BEFs design to enhance ventilation and mitigate traffic pollution.

Indoor Air Remediation Using Biochar from Bark: Impact of Particle Size and Pollutant Concentration

The growing emphasis on indoor air quality and public health is fuelling the need for efficient yet affordable air purification techniques. In this study, the influence of biochar particle size on its adsorption efficiency toward airborne pollutants was examined. Bark-derived biochar particles were treated by grinding or ball milling, and then, seven samples with different particle size groups were separated. Biochar particles were characterized by particle size, proximate, SEM, XRD, and physisorption analyses. For adsorption efficiency, two different pollutants were tested at variable initial concentrations. The physical composition and XRD patterns of the biochar with different particle sizes were comparable. The ball-milled sample was an exception in that it had higher ash content and additional XRD peaks signifying contamination of the sample. The porosity of biochar was greater in smaller particles. Ball milling increased the specific surface area and total pore volume by 102% and 48%, respectively. Biochar with finer particle size exhibited the highest adsorption potential towards formaldehyde and methanol among other samples. It should be emphasized that simple mechanical grinding is preferred for reducing biochar size to avoid the risk of eventual contamination, greater energy consumption, and slower processing related to ball milling. When a low concentration of pollutant was tested (1 ppm formaldehyde), the effect of particle size on the adsorption efficiency was more noticeable. However, the effect of particle size was less dominant when higher concentrations of pollutants were tested. Smaller biochar particles (&lt;100 μm) are more favourable for indoor air remediation given their superior adsorption efficiency of volatile organic compounds occurring at low concentrations in the buildings.

Advances in aeration and wastewater treatment in shrimp farming: emerging trends, current challenges, and future perspectives

Abstract The shrimp aquaculture industry has recently witnessed dramatic growth. Shrimp farming has gradually shifted from extensive to intensive or super-intensive models. However, the intensification of shrimp aquaculture is associated with energy security and environmental issues. The aeration system requires high energy demand to run mechanical aerators to maintain dissolved oxygen concentration in cultured ponds. Besides, intensive shrimp farms usually produce wastewater with high pollutant concentrations that may jeopardize the ecosystem when discharged. In an attempt to minimize the impacts of these problems, rigorous technological approaches have been carried out. This review provides recent advanced technologies employed to improve aeration and wastewater management. Moreover, this paper also introduces a sustainable energy model being studied and developed for aeration and wastewater treatment at shrimp farms.

The red listed eagle owl (Bubo bubo) population in Norway is exposed to POP levels exceeding threshold values for adverse health effects

The eagle owl (Bubo bubo) population in Norway is today classified as critically endangered on the red list of endangered species. Because previous studies have detected high concentrations of Persistent Organic Pollutants (POPs) in birds of prey, concerns have been raised whether POPs exposure are a significant factor to the substantial decline of the eagle owl population.The aims of this study were to measure the levels of POPs in eagle owls and to assess whether POPs may represent a potential health risk. POPs were analysed in liver samples from 100 eagle owls collected between 1994 and 2014.The concentrations of POPs were generally very high and individual birds had levels among the highest measured worldwide. The contaminant groups analysed were highly correlated (p < 0.0001). The concentrations of sum of Polychlorinated Biphenyls (∑PCB) exceeded the threshold value from moderate to severe health risk in 90% of the birds. The birds with cachectic or lean body condition had significantly higher levels of contaminants than those with higher body condition scores. No significant temporal or spatial trends were noted.The lack of temporal trends, suggest that the downward trend of POPs, appear to be levelling off. The lack of differences between inland and coastal regions suggest that the risk of exposure may be comparable between predatory birds feeding in marine or terrestrial food webs. The significantly higher POPs levels detected in individuals with poor body condition may be due to reduced fat stores and thereby higher concentration in the remaining fat and/or the weight loss could be induced by toxic effects. The high proportion of birds exceeding the threshold values for severe and high risk of adverse effects, suggest that the high contamination load may reduce the eagle owl’s fitness and survival and, thus, contribute to decline of the eagle owl population.

Experimental Study on the Forced Ventilation Safety during the Construction of a Large-Slope V-Shaped Tunnel

The special large-slope V-shaped structure of underwater tunnels changes the ventilation characteristics during tunnel construction, making the traditional experience limited. Therefore, it is urgent to study the influence of the special structure on the safety of the air environment during construction. In this paper, a series of small-scale experiments were conducted to investigate the ventilation characteristics of V-shaped tunnels. The coupled effects of ventilation parameters (distance of duct outlet from working face Lo, air velocity at the duct outlet uo) and structural characteristics (digging length Ld, slope of the uphill section q) were considered. The extreme slope of the V-shaped tunnel of 8% was considered. The flow field and pollutant transport law were determined by using CO as a tracer in the experiments. The results show that uo has a positive impact on the air return velocity, while Ld has a negative impact, and neither of the other two factors has a significant effect. The transport characteristics of CO in V-shaped tunnels differ from those in flat tunnels, with the former tending to cause unconventional areas of high pollutant concentrations in the horizontal sections. Furthermore, the correlations between CO concentration and distance, ventilation time, and the influence factors discussed in this paper are derived from the experimental results. The conclusions provide guidance for the construction of V-shaped tunnels to prevent air pollution in the construction environment and to improve the working conditions of laborers. Additionally, it can also enrich the ventilation experience in tunnel construction.