Potentially Toxic Substances and Associated Risks in Soils Affected by Wildfires: A Review

The presence of toxic substances is one of the major causes of degradation of soil quality. Wildfires, besides affecting various chemical, physical, and biological soil properties, produce a mixture of potentially toxic substances which can reach the soil and water bodies and cause harm to these media. This review intends to summarise the current knowledge on the generation by wildfires of potentially toxic substances, their effects on soil organisms, and other associated risks, addressing the effects of fire on metal mobilisation, the pyrolytic production of potentially toxic compounds, and the detoxifying effect of charcoal. Numerous studies ascertained inhibitory effects of ash on seed germination and seedling growth as well as its toxicity to soil and aquatic organisms. Abundant publications addressed the mobilisation of heavy metals and trace elements by fire, including analyses of total concentrations, speciation, availability, and risk of exportation to water bodies. Many publications studied the presence of polycyclic aromatic hydrocarbons (PAH) and other organic pollutants in soils after fire, their composition, decline over time, the risk of contamination of surface and ground waters, and their toxicity to plants, soil, and water organisms. Finally, the review addresses the possible detoxifying role of charcoal in soils affected by fire.

Tin and Antimony as Soil Pollutants along Railway Lines—A Case Study from North-Western Croatia

The aim of this study was to determine the extent and patterns of antimony and tin contamination in soils along railway lines, as there are very few data in the literature on this subject. The study was conducted in north-western Croatia. Total and bioavailable concentrations of Sn and Sb were detected using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The following results were obtained: total concentrations of Sb ranged from 0.98 to 52.0 mg/kg and of Sn from 3.04 mg/kg to 97.6 mg/kg. The soil samples showed pronounced Sb and Sn enrichment, up to 87 and 33 times the median value for European soils, respectively. In contrast to the total concentrations, the bioavailable concentrations showed relatively low values. For Sn, the percentage of total content ranged from 0.001 to 0.021%, while for Sb it ranged from 0.001 to 0.136%. Statistical data analysis suggests that the distribution of Sb and Sn in soils near railway lines is influenced by the functional use of the site, distance from the tracks, topography, age of the railway line, and also by soil properties such as soil texture, humus content, and soil pH. This study demonstrates that rail transport is a source of soil pollution with Sn and Sb. The origin of Sb and Sn enrichment is abrasion by brakes, rails, wheels, freight losses, exhaust gasses, etc. Both elements in soils along railway lines pose an environmental risk to humans, agricultural production, and wildlife, and therefore further detailed studies are required.

Total and bioavailable heavy metals in the soils of two adjacent forests

<p>The concentrations and comparisons of total and available metals Cd, Cr, Ni, Pb and the metalloid As were examined in two adjacent acid forest soils in Greece under oak and beech together with the dependency of their availability. It was found that the soil in the beech plot had higher concentrations of total elements with the exception of the litter layer (L) where most metals did not differ. It is probable that the parent material of the beech soil contained some metamorphic mafic material. The surface soils for both stands were moderately enriched with Pb, Cd and As, whereas for Cr and Ni the enrichment was minimal. The concentrations of available elements (extracted with DTPA) were higher in the beech soil. The availability of most metals was affected by the pH, the organic C, the ratio of C/N and the total concentration of the metals. Through a Principal Component Analysis (PCA) analysis, it was found that 63-75% of the concentrations variance of the available metals was explained. The percentages of available metals with regard to their total concentrations in soils were higher in the beech plot in the FH layer but in the mineral layers, they did not differ apart from Pb. The concentrations of the metals in the leaves of both species in three consecutive years did not differ with the exception of Cd, the concentration of which was higher in the beech leaves.</p>

Contamination Levels of Potentially Toxic Elements and Foraminiferal Distribution Patterns in Lagos Lagoon: A Correlation Analysis

The ecological response of benthic foraminifera to bioavailable Potentially Toxic Elements (PTEs) was evaluated in Lagos Lagoon (Nigeria). We sampled and analyzed PTEs across Lagos Lagoon with the aim to investigate the extent of contaminated sediments, to document their distribution, and to explore the relationship between PTE concentration and the spatial distribution, composition, abundance, and species richness of benthic foraminifera biotas. PTE’s recordings showed a wide range reflecting a diffuse contamination, where Contamination and Enrichment Factor suggest low to extremely polluted sediments. Findings of a previous survey of the benthic foraminifera inhabiting Lagos Lagoon revealed diverse assemblages of benthic taxa, species-specific distribution patterns, gradients of species richness and abundance, and a disjunct distribution of agglutinated and hyaline-perforate/porcelaneous taxa along a pronounced salinity gradient. Correlation matrix analysis shows that except for Selenium, all PTE total concentrations positively correlate with mud and Total Organic Carbon (TOC) and two of the most abundant agglutinated taxa, Ammotium salsum, and Trochammina sp. 1. Moreover, both species display significant positive correlations with CrF4-CoF2-F3-F4-total-CuF4-total-NiF3-F4-total-AlF4-total-FeF3-F4-total-ZnF3-F4-total. On the other hand, both foraminifers correlate negatively with PbF4-SeF3-Setotal. The overall significant positive correlation of these PTEs suggests that they behave as micronutrients when complexed with organic matter. No significant positive correlation with none of the PTEs in any fraction was found for neither species richness nor for the most abundant hyaline perforate species (Ammonia aoteana). Some PTE fractions were found to correlate either positively or negatively with individual species, suggesting that they function as either micronutrients and/or stressors. The resulting Contamination Factor of the PTE total concentrations shows that only a few sample sites can be classified as “moderately” polluted for chromium, zinc, and copper and that all sampled sites are classified as “highly polluted” for selenium. The highest concentrations for Cr, Cu, Ni, and Zn were found towards the industrialized western part, an area that is characterized by moderate to high diversity but low abundances.

Phthalates, non-phthalates, polychlorinated biphenyls and phenyl phosphates in atmospheric suspended particulate matter of Dhahran City, Saudi Arabia: Levels and seasonal variation

This work describes the seasonal variations, levels, and possible health effects of groups of persistent organic pollutants (POPs) as phthalates (Ps), non-phthalates (NPs), polychlorinated biphenyls (PCBs), and phenyl phosphates (PhePhs) in ambient total suspended particles (TSP) from the city of Dhahran, Saudi Arabia. The mass concentrations of TSP ranged from 88±32 µg m−3 in winter to 350±320 µg m−3 in summer. The total concentrations of these compounds varied from 337±266 ng m−3 in summer to 469±403 ng m−3 in winter. The major compounds were Ps (235±199 ng m−3 in summer to 389±335 ng m−3 in winter), PCBs (30.7±19.3 ng m−3 in autumn to 65.6±61.2 ng m−3 in summer), NPs (4.9±2.3 ng m−3 in summer to 11.9±12.5 ng m−3 in winter), and PhePhs (4.1±4.0 ng m−3 in spring to 13.3±3.2 ng m−3 in summer). The proportional fractions of these POPs relative to natural biogenic sources and petroleum-related emissions were extremely high ranging from 17% in winter to 47% in autumn. Significant correlations were found among these different POP groups and total concentrations, suggesting that they were from local sources. Principal component analysis indicated that Ps and NPs were from the same initial sources, and the PhePhs as well as PCBs were from different regional sources, where the latter were dependent on the TSP levels. In the long term, the elevated levels of these POPs in the TSP of these urban areas will affect human health by eventually developing a range of illnesses.

Preliminary investigation of the presence of PFOS and PFOA in water and sediment in Cau river

Perfluoro-octane sulfonate (PFOS) and Perfluoro-octanoic acid (PFOA) are recognised as emerging environmental pollutants because of their high persistence in various environmental matrices and toxic effects on humans and animals. The objectives of this study were to preliminarily investigate the occurrence of PFOS and PFOA in the water and sediment of the Cau river in Thai Nguyen city. The concentration of PFOS and PFOA in water ranged from <LOQ-0.67 ng/l and 0.05-8.11 ng/l; 1.19-4.73 ng/g, and 0.17-1.78 ng/g in sediment, respectively. The highest total concentrations of PFOS and PFOAwere recorded in the areas that directly received wastewater from domestic and industrial activities. The water-sediment distribution coefficient (Kd) was relatively different for PFOS and PFOA, with Kd ranged from 20.51-72.83 l/g and 1.21-20.31 l/g for PFOS and PFOA, respectively. This result suggested the distribution of PFOS and PFOA between water and sediment, in which PFOS will preferentially deposit in the sediment, and PFOA will tend to distribute in the liquid phase of the aquatic environment.

Source and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Water from Mboppi River in Douala–Cameroon

Having a source attributed to anthropogenic activities such as incomplete combustion or pyrolysis of organic materials, polycyclic aromatic hydrocarbons are toxic organic pollutants that the ubiquity is no more to be proved. The purpose of this work is to identify and quantify the hydrocarbons pollution of the Mboppi River. Eight (8) samples of water were collected in the river during the dry and the rainy season (4samples for each season). Hydrocarbon fraction was extracted by magnetic agitation of the mixture water/hexane followed by clean-up, fractionation and subsequently, analysis using gas chromatography coupled to a Flame Ionization Detector (GC-FID). Total concentrations of polycyclic aromatic hydrocarbons in the samples were ranged between 196.3-1040.19 µg/L in the river. Polycyclic aromatic hydrocarbons with more than four rings showed the highest concentrations in the river independently from the seasonal variation while the polycyclic aromatic hydrocarbons with 2 or 3 rings were usually present in low concentrations or sometimes undetectable. From the data, it was also possible to conclude that there is predominance of petroleum sources, and essentially closed to the more industrialized areas. Mboppi River can then be considered as being among the most polycyclic aromatic hydrocarbons polluted environment in comparison with some rivers and estuaries.

On the nature of indoor airborne bioaerosols at a hospital in Iran

Introduction: Hospitals are sensitive places owing to the contagious nature of diseases transferred by patients to others such as health care workers and staff. Materials and methods: The aim of the present work is to evaluate the type and concentration of bacterial and fungal bio-aerosols in the indoor air of four operating rooms (ORs) and four wards in Khalkhal, Iran during 2019. A total of 192 bacterial and fungal samples were collected. Results: Mean total concentrations of airborne bacteria for ORs and wards were between 11±1.2 to 48±3.1 CFU/m3, respectively, while for airborne fungi values ranged from 95±5.6 to 51±1.2 CFU/m3, respectively. The predominant genera of airborne bacterial isolated (ORs vs. wards) were Staphylococcus epidermidis (72% vs. 58%), Group D Streptococcus (4% vs. 17%), Group A Streptococcus (13% vs. 3%), and Staphylococcus saprophyticus (6% vs. 4%). In addition, the main fungal species identified (ORs vs. wards) were Cladosporium sp. (37% vs. 38%), Penicillium sp. (28% vs. 22%), and Aspergillus Niger (21% vs. 12%). A statistically significant correlation was observed between the mean concentration of bio-aerosols and population density (p<0.05). Conclusion: Furthermore, a statistically significant difference was observed between the mean concentrations of bio-aerosols and the values recommended by WHO (p<0.05), linked presumably to inadequate disinfection, improper design and operation of standard central ventilation (SCV), and the high density of visitors and patients. Addressing such issues can help reduce airborne fungi and bacteria in hospital.