Evaluation of Pollution Level, Spatial Distribution, and Ecological Effects of Antimony in Soils of Mining Areas: A Review

The first global-scale assessment of Sb contamination in soil that was related to mining/smelting activities was conducted based on 91 articles that were published between 1989 and 2021. The geographical variation, the pollution level, the speciation, the influencing factors, and the environmental effects of Sb that were associated with mining/smelting-affected soils were analyzed. The high Sb values mainly occurred in developed (Poland, Italy, Spain, Portugal, New Zealand, Australia) and developing (China, Algeria, Slovakia) countries. Sb concentrations of polluted soil from mining areas that were reported in most countries significantly exceeded the maximum permissible limit that is recommended by WHO, except in Turkey and Macedonia. The soil Sb concentrations decreased in the order of Oceania (29,151 mg/kg) > North Africa (13,022 mg/kg) > Asia (1527 mg/kg) > Europe (858 mg/kg) > South America (37.4 mg/kg). The existing extraction methods for Sb speciation have been classified according to the extractant, however, further research is needed in the standardization of these extraction methods. Modern analytical and characterization technologies, e.g., X-ray absorption spectroscopy, are effective at characterizing chemical speciation. Conditional inference tree (CIT) analysis has shown that the clay content was the major factor that influenced the soil Sb concentration. Non-carcinogenic risks to the public from soil Sb pollution were within the acceptable levels in most regions. An Sb smelter site at the Endeavour Inlet in New Zealand, an abandoned open-pit Sb mine in Djebel Hamimat, Algeria, an old Sb-mining area in Tuscany, Italy, and Hillgrove mine in Australia were selected as the priority control areas. Cynodon dactylon, Boehmeria, Pteris vittata, and Amaranthus paniculatus were found to be potential Sb accumulators. All of the values of bioaccumulation factors for the crops were less than one. However, ingestion of Sb through crop consumption posed potential non-carcinogenic health risks, which should not be neglected. The soil variables (pH, Eh, total sulfur, carbon nitrogen ratio, total organic carbon, and sulfate), the total Sb and the bioavailable Sb, and heavy metal(loid)s (As, Pb, and Fe) were the major parameters affecting the microbial community compositions.

Evaluation of the Bioavailability and Translocation of Selected Heavy Metals by Brassica juncea and Spinacea oleracea L for a South African Power Utility Coal Fly Ash

This study evaluated the physicochemical and mineralogical properties, mobile chemical species bioavailability and translocation in Brassica juncea and Spinacea oleracea L. plants of a South African coal-fired power utility. Coal-fly-ash (CFA) disposal is associated with various environmental and health risks, including air, soil, surface, and groundwater pollution due to the leaching of toxic heavy metals; these ends up in food webs affecting human health, while repeated inhalation causes bronchitis, silicosis, hair loss, and lung cancer. The morphology and chemical and mineralogical composition of CFA were determined using Scanning Electron Microscopy (SEM), X-ray fluorescence (XRF), and X-ray diffraction, respectively. In pot-culture experiments, S. oleracea L. and B. juncea plants were grown in three sets of pots containing CFA (Set 1), soil (Set 2), and a mixture of CFA plus soil at a ratio of 1:1 (50% CFA: 50% soil, Set 3), while no plants were grown in Set 4 as a control for the leachate samples. SEM showed that the surface morphology of CFA has a lower degree of sphericity with the irregular agglomerations of many particles. XRF results revealed that CFA contains 43.65%, 22.68%, and 10.89% of SiO₂, Al₂O_3, and Fe₂O_3, respectively, which indicates that CFA is an aluminosilicate material. X-ray diffraction (XRD) showed that CFA contains mullite as a major phase, followed by quartz mineral phases. Chemical species such as B, Ba, Mo, and Cr were occurring at higher concentrations in the leachates for most weeks in the pot-culture experiments, especially for CFA and soil + CFA growth media. However, there was a common trend for all growth media of chemical-species concentrations declining with time, which might have been caused by plant uptake or wash-off with water during irrigation; even for the growth media as well, where no plants were grown. Chemical species, such as Fe, Mn, B, Ba, and Zn, accumulated highly in most parts of the plant species. However, B. juncea showed higher potential to accumulate chemical species as compared to S. oleracea L. Bioconcentration and translocation factors (BF and TF) showed that B. juncea was the most effective in terms of bioconcentration and translocation of most of the chemical species. This indicates that B. juncea has potential in application for the phytoremediation of CFA dumps, and could contribute to the remediation of CFA dumps and the reduction of potential health and environmental impact associated with CFA.

Entropy Analysis of 3D Non-Newtonian MHD Nanofluid Flow with Nonlinear Thermal Radiation Past over Exponential Stretched Surface

The present study characterizes the flow of three-dimensional viscoelastic magnetohydrodynamic (MHD) nanofluids flow with entropy generation analysis past an exponentially permeable stretched surface with simultaneous impacts of chemical reaction and heat generation/absorption. The analysis was conducted with additional effects nonlinear thermal radiation and convective heat and mass boundary conditions. Apposite transformations were considered to transform the presented mathematical model to a system of differential equations. Analytical solutions of the proposed model were developed via a well-known homotopy analysis scheme. The numerically calculated values of the dimensionless drag coefficient, local Nusselt number, and mass transfer Nusselt number are presented, with physical insights. The graphs depicting the consequences of numerous parameters on involved distributions with requisite deliberations were also a part of this model. It is seen that the Bejan number is an increasing function of the thermal radiation parameter.

Fine particulate matter constituents associated with cardiovascular hospitalizations and mortality in New York City

BACKGROUND

Recent time-series studies have indicated that both cardiovascular disease (CVD)mortality and hospitalizations are associated with particulate matter (PM). However, seasonal patterns of PM associations with these outcomes are not consistent, and PM components responsible for these associations have not been determined. We investigated this issue in New York City (NYC), where PM originates from regional and local combustion sources.

OBJECTIVE

In this study, we examined the role of particulate matter with aerodynamic diameter ≤ 2.5 µm (PM(2.5)) and its key chemical components on both CVD hospitalizations and on mortality in NYC.

METHODS

We analyzed daily deaths and emergency hospitalizations for CVDs among persons ≥ 40 years of age for associations with PM(2.5), its chemical components, nitrogen dioxide (NO(2)), carbon monoxide, and sulfur dioxide for the years 2000-2006 using a Poisson time-series model adjusting for temporal and seasonal trends, temperature effects, and day of the week. We estimated excess risks per interquartile-range increases at lags 0 through 3 days for warm (April through September) and cold (October through March) seasons.

RESULTS

The CVD mortality series exhibit strong seasonal trends, whereas the CVD hospitalization series show a strong day-of-week pattern. These outcome series were not correlated with each other but were individually associated with a number of PM(2.5) chemical components from regional and local sources, each with different seasonal patterns and lags. Coal-combustion-related components (e.g., selenium) were associated with CVD mortality in summer and CVD hospitalizations in winter, whereas elemental carbon and NO(2) showed associations with these outcomes in both seasons.

CONCLUSION

Local combustion sources, including traffic and residual oil burning, may play a year-round role in the associations between air pollution and CVD outcomes, but transported aerosols may explain the seasonal variation in associations shown by PM(2.5) mass.