Pollutants, Volume 5, Issue 1 (March 2025) – 8 articles

The prevalence of hyperthyroidism in cats has been steadily increasing worldwide since the late 1970s. The main cause of feline hyperthyroidism remains unknown. The underlying cause was studied from the viewpoint of the “One Health” concept, which is an approach integrating environmental, animal and human health. Looking at the dietary difference between cats which are carnivores and dogs which appear to be omnivores like humans, there is a possibility that cats take in a comparatively greater amount of endocrine-disrupting chemicals such as polybrominated diphenyl ethers (PBDEs) than dogs and humans via the fish-based food web. PBDEs have been used worldwide as flame retardants since the 1970s. It is considered that PBDEs mimic thyroid-stimulating hormones to cause a thyroid adenoma, which is often active and produces excessive thyroid hormones, resulting in symptomatic hyperthyroidism. The increasing prevalence of feline hyperthyroidism may be associated with Minamata disease that was caused by methyl-mercury contamination in the 1950s. This environmental contamination firstly wreaked havoc as neurological disorders in local cats, and this occurrence was a sign that severe neurological disorders would next develop in large numbers of local people. The prevalence of feline hyperthyroidism may be a sign of what will next emerge in human beings. Full article

This study evaluated heavy metal (HM) contamination in sediments from the Malbasag River in the Ormoc City port, Leyte, Philippines. A total of thirty sediment samples were collected randomly from ten locations along the river using an Ekman grab sampler. Atomic absorption spectrophotometry revealed HM concentrations in the order of Mn > Zn > Cu > Ni > Pb > Cd. All HMs exceeded their sediment quality guideline (SQG) thresholds except for Mn. Contamination was assessed using indices such as the contamination factor (CF), pollution load index (PLI), geo-accumulation index (I_geo), and enrichment factor (EF). The CF values indicated “moderate to considerable” contamination for Zn, Ni, and Cd, while Cu and Pb showed “very high” contamination levels. The PLI results indicated severe sediment degradation in 20% of samples. The I_geo analysis classified 60% of the samples as “heavily to extremely polluted” for Cd, Cu, and Pb. EF analysis suggested that anthropogenic sources contributed to elevated HM levels, including port activities and agricultural runoff. Ecological risk index (RI) analysis revealed moderate risk in 40% and considerable risk in 20% of sampling locations. Multivariate analyses suggested significant anthropogenic contributions to HM contamination, highlighting the need for further studies to assess the ecological impacts. Full article

The recent increase in industrial activities has raised concerns regarding environmental quality in urban areas in Malawi. In this study, the contents of heavy metals [copper (Cu), zinc (Zn) and cadmium (Cd)] were analysed in 15 sites selected from Makata, Limbe, Maselema, Chirimba, and Maone industrial zones of Blantyre City in Malawi. Soil sampling was conducted during dry and rainy seasons, followed by laboratory analysis. The results revealed a few cases of elevated content of heavy metals exceeding permissible England and Canadian standards with higher content detected during the dry season than in the rainy season. Chirimba soil had the highest mean Zn content of 822 mg/kg in the rainy season and 579 mg/kg in the dry season. Maone soils had the highest Cd content, measuring 2.09 mg/kg in the rainy season and 3.06 mg/kg in the dry season. Chirimba soils also had the highest Cu content with levels of 105 mg/kg in the dry season and 79 mg/kg in the rainy season. The geo-accumulation index indicated that Zn posed the most severe pollution. The results of the Positive Matrix Factorisation model suggest that heavy metal pollution primarily originates from metal processing and manufacturing industries, followed by plastic manufacturing industries. This finding is supported by the nature of emissions from these sectors, where metal processing activities release heavy metals through particulates and waste to the environment, suggesting collective actions to prevent soil contamination. Full article

This paper focuses on the environmental impact of urban surface transportation and the influence that driving mode and drivers’ attitudes have on it. This article emphasizes the importance of a respectful attitude toward the environment and adopting moderate or conservative driving modes. This study covers driving GHG emissions in urban and peripheral areas for variable driving conditions, evaluating reductions or increases in CO₂ emissions depending on the way of driving. The analysis of the different cases shows that pollutant emissions are significantly lower if a car driver reduces the acceleration rate and slows down by 10 to 20 km/h, or 6 to 12 mph, depending on the urban zone, downtown or peripheral, and traffic conditions. The reduction in GHG emissions can be as high as 0.083 kg of CO₂ per day, on average, representing a global yearly reduction of 30 kg of GHG emissions per vehicle. This paper analyzes how inadequate driving speed and the above traffic regulation limits have caused a surplus in GHG emissions and a severe impact on urban areas, which are sensitive to pollution, increasing the GHG emission rate by between 28% and 40% depending on driving mode and driver attitude. This study shows that vehicle speed reduction did not significantly increase traveling time, with an average time extension of 0.2 min per km, representing a global extended daily traveled time of 6.4 min for the average daily journey distance in many countries. GHG increases due to inadequate driving increase the early human mortality rate by 0.4%, representing nearly 35 million early deaths per year. Full article

Two sets of sediment samples were collected from the Sarigiol basin, Greece, aiming to evaluate the environmental consequences of the industrial activity in the area by assessing their magnetic properties with the magnetic susceptibility method. Chemical composition and morphological characteristics of magnetic particles were defined by EDX analysis and scanning electron microscopy, respectively. Based on the results, most of the study area shows positive values of the difference between X_LF values of the samples, indicating the influence of fly ash dispersion from Agios Dimitrios and Kardia power plants and the conveyor belt, down to a depth of 50 cm. Negative values in the NE, W and S parts of the study area are attributed to ophiolite complexes. Anthropogenic and lithogenic magnetic particles were identified at a 50 cm depth, in the form of spheres and octahedrons, respectively. Fe is the dominant element while Al, Si, Mg and Ca were found in minor amounts. Cr increases with depth, pointing mainly to a lithogenic source, while Ti decreases, suggesting a relationship with the dispersed fly ash particles. Mn and Zn were found in limited magnetic spheres. These findings highlight the need for effective environmental management strategies and are valuable keys for soil pollution control. Full article

Air pollution in urban centers comes from anthropogenic activities. Tropospheric ozone (O₃) depends on chemical precursors that promote an increase in its production, mainly in wind-dominated and large green areas. It is a gas produced by a series of complex chemical reactions catalyzed by sunlight in the atmosphere. It can be concentrated to a greater or lesser extent depending on factors such as the amount of volatile organic compounds (VOCs), the amount of nitrogen dioxide (NO₂), the intensity of solar radiation, or by climatic conditions such as temperature and other factors. The objective of this study was to predict tropospheric ozone levels from Land Surface Temperature (LST) data of Landsat 8 in the city of Durango, Dgo. Tropospheric O₃ and LST values were obtained from 14 sampling points in the urban area of the city of Durango, of which 11 were obtained by collecting from temperature-monitoring station data and the rest from three fixed monitoring stations established in the city, specifically located in Ministry of Natural Resources and Environment (SRNyMA), Durango Institute of Technology (ITD) and Interdisciplinary Research Center for Regional Integral Development Durango Unit (CIIDIR). A correlation analysis was performed for the 12 months of the year 2023. Subsequently, a linear regression analysis was executed for each month. The results showed a greater positive correlation between O₃ concentration and temperature for January (r = 0.91); additionally, this period showed a greater goodness of fit in the prediction of O₃ (R² = 0.91; RMSE = 0.65 ppm). The LST allows for the spatial prediction of ozone concentrations in terms of covering complete urban areas without measuring air stations. Full article

Differences in exposures and resources to manage personal health contribute to persistent inequities in air pollution burden despite vast air quality improvements over the past 2–3 decades in the United States. These factors are, partly, linked to historic racist practices, such as redlining, a discriminatory housing policy that was practiced legally between 1935 and 1968. Using 100 m × 100 m resolution land-use regression predicted surfaces of PM_2.5 constituents (black carbon, nickel, vanadium, and copper) as pollution source indicators, we fit Bayesian generalized linear mixed-effects models to examine differences in source exposures over two study periods, 2008–2015 and 2016–2019, comparing (1) redlined to not redlined and (2) high-asthma to low-asthma neighborhoods. We examine redlining as an indicator of historical, and structural racism and asthma rates as an indicator of present-day community burden. Redlined areas saw near elimination of disparities in exposure to residual oil boilers and marine residual oil but persistent disparities in traffic. High-asthma neighborhoods continue to have disproportionately high exposures to both residual oil boilers and traffic, with no discernable disparities related to marine residual oil emissions. Overall exposure disparities are small, with PM_2.5 disparities by both asthma morbidity and redlining amounting to less than 1 µg/m³ and NO₂ disparities by asthma and redlining amounting to less than 2 ppb in the post-2016 period. For context, 2019 NYC average PM_2.5 and NO₂ were 8.5 µg/m³ and 20 ppb, respectively. Our findings suggest that local pollution policy should focus on reducing traffic and building boiler emissions in high-asthma neighborhoods to reduce exacerbations. Full article

Acid mine drainage (AMD), which is primarily caused by the exposure of sulfidic minerals to oxygen and water during mining operations, remains a significant contributor to environmental pollution. Numerous technologies have been developed to prevent/control and treat AMD, including the isolation of waste from the atmosphere and treatment systems for AMD-impacted water. Many field studies on mine site reclamation have involved an individual AMD source and/or technology, with a limited number of studies looking at reclamation programs integrating multiple approaches to manage AMD stemming from both surface and underground sources. The former Franklin mine site in Nova Scotia, Canada, was impacted by the deposition of waste rock across the site and the discharge of mine water from underground workings, with the adjacent Sullivan’s Pond serving as the main environmental receptor. Site reclamation was completed in 2010 and involved the following: (1) excavation of the dispersed waste rock (117,000 m²) and backfilling with clean soil; (2) consolidation of the excavated waste rock into a covered, compact waste rock pile (WRP) (25,000 m²); and (3) construction of a passive treatment system for the discharging underground mine water. An extensive field sampling program was conducted between 2011 and 2018 to monitor a range of meteorological, cover material, waste rock, groundwater, and surface water quality parameters. The results confirm that the multi-layer, geomembrane-lined WRP cover system is an extremely effective barrier to air and water influx, thereby minimizing the rate of AMD generation and seepage into groundwater and eliminating all contaminated surface water runoff. A small AMD groundwater plume emanates from the base of the WRP, with 50% captured by the underground mine workings over the long term and 50% slowly migrating towards Sullivan’s Pond. Excavation of the former waste disposal area eliminated the AMD source from the previously dispersed waste, with only clean surface water runoff and a diminishing legacy groundwater plume remaining. Finally, the passive treatment system, which contains a series of treatment technologies such as a limestone leach bed and settling pond, successfully treats all mine water loading (~50 kg/day) discharging from the underground workings and surface runoff. Its additional treatment capacity (up to ~150 kg/day) ensures it will be able to manage any potential drop in treatment efficiency and/or increased AMD loading from long-term WRP seepage. This comprehensive study of mine site reclamation and AMD management at an abandoned mining site can be of great reference value for environmental management and policymakers in the mining sector. Full article