Human and ecological risk assessment of heavy metals in different particle sizes of road dust in Muscat, Oman

Effects of massive desiccation of olive waste residues on air quality

New industries are proliferating in the recovery of agri-food wastes, such as those involved in the revaluation of alperujo, generated in the production of olive oil. Despite the potential environmental benefits, their activity is not exempt from new forms of emissions, aggravated by the massification of waste treatments. This work reports a six-month field campaign carried out in an alperujo desiccation plant which can serve as a proxy for these emerging industries in the Mediterranean countries. The study focused on air quality parameters, covering criteria pollutants, metals and microbiological load of particulate matter and the characterization of volatile organic compounds (VOCs). The results show a slight contribution of the factory to the NOx levels in the surroundings (3.0-12.5 μg/m3). Statistically significant effects were not observed for ozone, CO, SO2, or PM10. Concerning the levels of metals, concentrations were low and calculated health risk indexes indicated safe conditions in the area. The most abundant elements were Na (6.5 × 102 ng/m3), K (4.0 × 102 ng/m3), Al (2.7 × 102 ng/m3), Zn (2.1 × 102 ng/m3), Ca (2.16 × 102 ng/m3), Fe (3.6 × 101 ng/m3) and Mg (3.2 × 101 ng/m3). Bacterial counts, with a mean value of 15.9 CFU/m3, showed a seasonal shift, mainly explained by weather (air moisture and temperature) and PM2.5 concentration. The genomic analysis showed Cutibacterium as the dominant genus during the cold months while Bacillus predominated in the warm season. The VOCs with higher average concentrations were acetic acid (130 μg/m3), nonanoic acid (124 μg/m3), benzoic acid (29.7 μg/m3), octanoic acid (19.9 μg/m3) and nonanal (4.70 μg/m3), with the rest of compounds in concentrations below 4 μg/m3. Odorant pollutants with the greatest contribution to olfactory nuisance were aldehydes (from pentanaldehyde to decanaldehyde), acetic acid and phenol. Although the observable effects of the waste treatments were low, several parameters showed an influence on the environment which should be assessed to foresee and prevent long-term consequences.

Determination of contamination, source, and risk of potentially toxic metals in fine road dust in a karst region of Southwest China

Understanding the pollution situation of potentially toxic metals (PTMs) in fine road dust (FRD) in emerging industrialized cities and identifying priority control factors is crucial for urban environmental management, resident health protection, and pollution control. This study conducted a comprehensive investigation on PTMs pollution in FRD in Zunyi, a representative emerging industrialized city in the karst region of southwestern China. The average contents of Ni, Cr, Mn, Cu, Zn, Ba, Pb, V, and Co in the FRD were 43.2, 127.0, 1232.1, 134.4, 506.6, 597.8, 76.1, 86.8, and 16.2 mg kg-1, respectively, which were obviously higher than the corresponding background levels of the local soil except for V and Co. The comprehensive pollution level of the determined PTMs in the FRD was very high, primarily caused by Zn and Cu. The sources of PTMs in Zunyi FRD were traffic, industrial, construction, and natural sources, accounting for 38.0, 23.7, 21.9, and 16.4% of the total PTMs content, respectively. The PTMs in Zunyi FRD exhibited a low to moderate overall ecological risk level, mainly contributed by Cu and traffic source. The cancer risks of PTMs in Zunyi FRD were high for all populations. The non-carcinogenic risk of PTMs in Zunyi FRD was acceptable for adults, but cannot be ignored for children. According to the source-specific probabilistic health risk estimation results, the priority control source is industrial source and the priority control PTM is Cr. Local governments need to give more attention to the carcinogenic risks and health hazards posed by PTMs in the FRD.

Ecological pollution features and health risk exposure to heavy metals via street dust and topsoil from Nkpor and Onitsha in Anambra, Nigeria

The manuscript presents the investigation results on the pollution and risk of metal mines, and it is considered an important report on environmental pollution near mines in Nigeria, with archival value. The research involved soil sampling and heavy metal analysis for about 12 months in three metal mines. Based on these results, the paper provides information on pollution levels and hazards using well-known methods like pollution and ecological risk indexes. The increasing population in urban communities attracted by various industrial, economic and social activities causes contamination of atmospheric environment that can affect human health. We investigated heavy metal distributions, correlation coefficient among elements, ecological indices and probable health risk assessment in street dust and topsoil from Nkpor and Onitsha urban suburb, Nigeria. The mean concentration of heavy metals in car dust from Onitsha and Nkpor suburb follows thus: Fe > Mn > Cu > As > Pb > Ni > Cr. The decreasing trend of heavy metal in rooftop dust from both area: Fe > Mn > Cu > Pb > As > Ni > Cr whereas metal contents in topsoil were: Fe > Mn > Cu > Pb > Ni > Cr > As for both areas. The degree of pollution indices was characterized by contamination factor (CF), geo-accumulation factor (I-geo), pollution load index (PLI), Nemerow (PN), ecological and potential ecological risk index (ER and PERI) which indicated low pollution in the urban street environment. The results of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that the estimated heavy metals displayed sources from atmospheric deposition, natural origin and anthropogenic sources. Risk assessment revealed that ingestion of dust and soil was the significant route for heavy metals exposure to the populace followed by inhalation, then dermal contact. Considering all factors, non-cancer risk was more prominent in children than adults and no significant health hazard could be attributed to both aged groups as of the period of study except for As and Ni that needs constant monitoring to avoid exceeding organ damaging threshold limit of 1 × 10-4.

Trace elements and microbial community composition associated with airborne PM2.5 in wetlands: A case study in Tablas de Daimiel National Park

Tablas de Daimiel National Park (TDNP) is one of the most important wetlands in the Iberian Peninsula. Due to its location near various cities and new industries focused on agricultural waste revalorization, we investigated concurrently the concentrations of particulate matter 2.5 (PM2.5) mass, trace element composition, and associated microbial communities (bacteria and fungi) during a year-long study. The goal of this study was to explore the dependencies among these physicochemical and microbiological parameters on a seasonal time scale. Additionally, we assessed meteorological conditions and back trajectories to shed light on atmospheric mechanisms and sources related to these elements. We found the variability of PM2.5 to be influenced by local meteorological parameters. Through the analysis of crustal enrichment factors (EFs), bivariate correlations, and air mass patterns, we determined that soil resuspension was the primary contributor to elevated metal concentrations in PM2.5 within the park, followed by other minor sources, such as traffic emissions and Sahara dust intrusions. The measured metal levels were used to calculate the ecological risk in the area, resulting in a low ecological risk index (RI) of 52. Shifts in microbial community structure were observed to be mainly driven by changes in air temperature and Cu concentration. The results from this study contribute to a better understanding of the environmental dynamics in TDNP. Taken together, our findings will aid in the development of effective strategies for its conservation and management.

Human biomonitoring of environmental contaminants in Gulf Countries - current status and future directions

BACKGROUND

This systematic review aimed to evaluate the status of Human Biomonitoring (HBM) in the Gulf Cooperation Council (GCC) region and provide recommendations for future research, considering the increased environmental contaminants that pose a threat to human health in this rapidly industrializing area.

METHODS

A thorough search was performed in PubMed and Web of Science databases up to February 2023 to identify biomonitoring studies on human exposure and levels in the GCC region. Two independent reviewers assessed study eligibility, conducted data extraction and risk of bias assessment. The NIH Quality Assessment Tools and PRISMA guidelines were utilized for quality evaluation and reporting of results.

RESULTS

A total of 38 eligible articles were included in this systematic review out of 662 articles screened. The majority of the publications were from Saudi Arabia (n = 24) and Kuwait (n = 10), while limited representation was found from Qatar (n = 3) and the UAE (n = 1). No articles were identified from Oman and Bahrain. The studies focused on metals, organohalogen compounds, pesticides, polycyclic aromatic hydrocarbons, and phthalates. The findings revealed elevated levels of metals and established correlations between metal exposure and adverse health effects, including infant neurodevelopmental issues, vitamin D deficiency, and oxidative stress. The presence of organohalogen compounds and pesticides was prevalent in the GCC region, with significant associations between exposure to these compounds and negative health outcomes. Notably, high levels of perchlorate were observed in the Kuwaiti population, and a study from Saudi Arabia found an association between per- and polyfluorinated substances and increased odds of osteoporosis.

CONCLUSIONS

This review emphasizes the need to address environmental health challenges in the GCC region through improved HBM research methods and strategies. Implementing biomonitoring programs, conducting cohort studies, investing in tools and expertise, promoting collaboration, and engaging the community are crucial for reliable HBM data in the GCC.

Ascertaining priority control pollution sources and target pollutants in toxic metal risk management of a medium-sized industrial city

Re-suspended surface dust (RSD) often poses higher environmental risks due to its specific physical characteristics. To ascertain the priority pollution sources and pollutants for the risk control of toxic metals (TMs) in RSD of medium-sized industrial cities, this study took Baotou City, a representative medium-sized industrial city in North China, as an example to systematically study TMs pollution in RSD. The levels of Cr (242.6 mg kg-1), Pb (65.7 mg kg-1), Co (54.0 mg kg-1), Ba (1032.4 mg kg-1), Cu (31.8 mg kg-1), Zn (81.7 mg kg-1), and Mn (593.8 mg kg-1) in Baotou RSD exceeded their soil background values. Co and Cr exhibited significant enrichment in 94.0 % and 49.4 % of samples, respectively. The comprehensive pollution of TMs in Baotou RSD was very high, mainly caused by Co and Cr. The main sources of TMs in the study area were industrial emissions, construction, and traffic activities, accounting for 32.5, 25.9, and 41.6 % of the total TMs respectively. The overall ecological risk in the study area was low, but 21.5 % of samples exhibited moderate or higher risk. The carcinogenic risks of TMs in the RSD to local residents and their non-carcinogenic risks to children cannot be ignored. Industrial and construction sources were priority pollution sources for eco-health risks, with Cr and Co being the target TMs. The south, north and west of the study area were the priority control areas for TMs pollution. The probabilistic risk assessment method combining of Monte Carlo simulation and source analysis can effectively identify the priority pollution sources and pollutants. These findings provide scientific basis for TMs pollution control in Baotou and constitute a reference for environmental management and protection of residents' health in other similar medium-sized industrial cities.

A review on toxic metal pollution and source-oriented risk apportionment in road dust of a highly polluted megacity in Bangladesh

Heavy metal enrichment in road dust has resulted from intensive anthropogenic activity, particularly urbanization, industrial activities and traffic emission, posing a hazard to urban ecosystems and human health. To promote optimal road dust management in urban environments, it is necessary to assess the possible ecological and health impact of toxic elements in road dust. In a heavily populated megacity like Dhaka, Bangladesh, large-scale risk assessments of contamination in road dust with heavy metals are limited. The present study aims at presenting a concentration of twenty-five metals in road dust (Na, K, Cs, Rb, Mg, Ca, Sr, Ba, Al, Zn, Cd, Pb, As, Sb, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr and W) in Dhaka megacity. We used a critical source-based positive matrix factorization model, source-oriented potential ecological risks and health risks. Out of the studied metals, Na, Ca, Zn, Cd, Cu, Zr and W exceeded the shale value. About 73%, 48%, 29% and 32% of sampling sites showed a higher level of pollution based on PLI, NIPI, PER and NIRI, respectively. PMF model identified that Cd (85.3%), Cr (62.4%), Ni (58.2%), Zn (81.8%) and Mn (65.9%) in road dust were primarily attributed to traffic emission, fuel combustion, metal processing, transport sources and natural sources, respectively. Fuel combustion and metal processing posed considerable and high risks based on modified potential ecological risk and NIRI. Based on health hazards, traffic emission posed a high cancer risk in adult males (29%), whereas transport sources contributed to females (21%) and children (23%).

Heavy Metal Pollution and Risk Assessment of Surface Dust in the Arid NW China

High concentrations of heavy metals (HMs) in urban surface dust (USD) can be extremely hazardous to urban ecology and human health. Oasis cities are located at the edge of deserts and are more exposed to salt/sandstorms, and they face a significantly higher accumulation of USD than wet or semi-humid areas. However, systematic studies on the pollution and risk assessment of HMs in USD in oasis cities have rarely been conducted. This study systematically analyzed the enrichment status, spatial distribution, pollution levels, health risks, and sources of HMs in USD in a typical oasis city (Changji city). The results showed that the average concentrations of Pb, Ni, As, Cd, Hg, and Cu in the USD of Changji city were 46.83, 26.35, 9.92, 0.21, 0.047, and 59.33 mg/kg, respectively, and the results of the pollution index evaluation showed moderate Pb, Hg, and Cu pollution, mild Cd pollution, and no Ni or As pollution. The spatial distribution of HM concentrations in the USD was substantially heterogeneous. High values of Pb, Hg, and Cu concentrations were mainly observed in areas with relatively intensive transportation and commercial activities, and high values of Cd and Ni were observed in industrial areas. The health risk assessment showed that HMs do not pose non-carcinogenic risks to humans at their current level, but they pose a carcinogenic risk to children, with As contributing the largest carcinogenic and non-carcinogenic risks. The source identification of HMs showed that the main pollution of HMs were traffic sources for Pb and Cu, industrial sources for Ni and Cd, natural sources for As, and coal-fired sources for Hg. According to the results of the quantitative analysis with the positive matrix factorization, the contribution of pollution sources followed this order: industrial sources (31.08%) > traffic sources (26.80%) > coal-fired sources (23.31%) > natural sources (18.81%).

Metal contamination in soils and windowsill dusts: implication of multiple sources on dust metal accumulation within a city affected by Pb smelting

The accumulation of total Pb, Cd, Cu, and Zn in soils (0-5 cm) and windowsill dust fractions (45-125, 10-45, and < 10 μm), and soil pollution indices (PI), were investigated in a long-term (~ 70 years) Pb smelter area and in the nearby urban city of Jiyuan, China. Principal component analysis (PCA) was utilized to identify metal contamination sources. Results showed that mean soil Pb, Cd, Cu, and Zn concentrations in the smelter area were 803, 13.8, 118, and 323 mg kg^-1, while those of the urban area were 270, 7.95, 51.6, and 244 mg kg^-1, respectively. Lead and Cd had greater soil PI than Cu and Zn. Lead concentrations in the 45-125, 10-45, and < 10-μm urban dust fractions ranged from 197.1 to 1953 (mean 1020), 202-3962 (2407), and 51.1-1258 (310.7) mg kg^-1, while Cd concentrations ranged from 11.1 to 111 (49.2), 10.4-159 (64.3) and 21.5-131 (60.0) mg kg^-1, respectively. Excessive Zn concentrations (5000-22,000 mg kg^-1) in some urban dust samples were found at two sampling sites, while Zn concentrations were < 2600 mg kg^-1 in all other samples. Based on PCA results, metal accumulation near the Pb smelter was dominated by smelting activities. The PCA results further suggested that mass vehicular transportation modes may be an important source of metals such as Cu and Zn in the urban area. Certain samples in both sub-areas had unsafe potential non-carcinogenic risks of Pb for children. These findings suggest that reducing environmentally relevant metal concentrations in this, and similar areas, will likely require a multi-faceted approach.

Pollution characteristics, risk assessment, and source apportionment of potentially toxic elements in road dust at two industrial parks in Trinidad and Tobago, West Indies

Potentially toxic elements can enter the environment through natural and anthropogenic processes, with the latter considered the primary contributor. Road dust samples from two industrial parks on the island of Trinidad were investigated for heavy metal content, and the pollution status, potential health risks, and source apportionment were evaluated. Samples were acid-digested and analysed by flame atomic absorption spectroscopy. The average levels of cadmium, chromium, copper, manganese, nickel, lead, and zinc in road dust at the Frederick Settlement Industrial Park were 1.14 μg/g, 15.13 μg/g, 66.42 μg/g, 768.49 μg/g, 37.95 μg/g, 55.90 μg/g, and 573.04 μg/g, respectively, while average concentrations at the O'Meara Industrial Park were 1.20 μg/g, 16.97 μg/g, 42.72 μg/g, 482.65 μg/g, 21.12 μg/g, 136.77 μg/g, and 358.70 μg/g, respectively. Contamination assessments evaluated both Fredrick Settlement and O'Meara as typically uncontaminated to moderately polluted, with the overall ecological risk deemed low at all locations. Hazard index values at all sampling areas were lower than 1, indicating no potential non-carcinogenic risks to children or adults, while the carcinogenic exposure risks for cadmium, chromium, and nickel were considered low. Principal component analysis and cluster analysis revealed two main sources of contamination for Fredrick Settlement, and three main sources for O'Meara. Based on the groupings obtained, the presence of potentially toxic elements was attributed primarily to specific anthropogenic activities within the industrial parks, with lesser contributions from vehicular-related sources.

A four-way model (FEST) for source apportionment: Development, verification, and application

In studying the spatial, temporal, and particle size variations heavy metal sources, a source apportionment model for a four-way array of data is required. In this study, referencing two-way and three-way models, a four-way (particle fractions, elements, sites, and time) source apportionment model (FEST) was developed. Errors in the three-way models solving four-way problems verified the necessity of developing the FEST model. The results showed that the FEST model had a higher accuracy than the existing models, which was probably because of more constraints and input data in the FEST model. Based on the sampled data in Beijing, sources were apportioned for the four-way array of data using the FEST model, and the spatial, temporal, and particle size variations of sources were evaluated. The main sources of heavy metals were similar to those in our prior studies, whereas the contributions of sources to specific heavy metals differed. Traffic exhaust and fuel combustion contributed more to fine particles than coarse particles, indicating that the two should be controlled preferentially among all sources. The management of traffic exhaust should be focused on the central and northern areas in each season, and the control of fuel combustion should be strengthened in the southern area in winter.

Potentially toxic elements in street dust from an urban city of a developing country: ecological and probabilistic health risks assessment

Anthropogenic activities in and around the urban highways followed by aerodynamic processing generate street dusts, which can cause adverse health effects through different exposure pathways. Hence, considering the high degree of industrialization, concomitant unplanned urbanization, and rapid demographic augmentation, street dust samples from an urban city (Gazipur, Bangladesh) were investigated in terms of potentially toxic elements (using ICP-MS) to evaluate their ecological and health risks. Mean concentrations (± SD) of lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), zinc (Zn), nickel (Ni), and arsenic (As) in the analyzed air-dried samples were 40.9 ± 13.6, 44.9 ± 15.4, 83.3 ± 19.0, 9.1 ± 5.4, 239.1 ± 34.7, 33.5 ± 10.4, and 2.1 ± 0.8 mg/kg, respectively with heterogeneous distribution which were 0.2 (As) to 82.7 (Cd) times higher than the available internationally recommended limits. Element-specific environmental indices revealed that contamination levels followed the descending order as Cd > Zn > Cu > Pb > Cr > Ni > As, whereas individual ecological risks followed the descending order as Cd > Cu > Pb > Ni > Zn > Cr > As. Sampling site-specific composite indices indicated that sampling sites with high loadings of traffic, population, industrialization, and urbanization were mostly polluted. Multivariate statistical approaches also deduced the similar origins of the studied elements. In terms of the investigated elements, the study site possessed high potential ecological risks, although non-carcinogenic and carcinogenic risks through different pathway's exposures seem insignificant, where children are more vulnerable than adults.

Characteristics of Potentially Toxic Elements, Risk Assessments, and Isotopic Compositions (Cu-Zn-Pb) in the PM10 Fraction of Road Dust in Busan, South Korea

The pollution status of ten potentially toxic elements (PTEs), isotopic compositions (Cu, Zn, Pb), and the potential ecological risk posed by them were investigated in the PM10 fraction of road dust in Busan Metropolitan city, South Korea. Enrichment factors revealed extremely to strongly polluted levels of Sb, Cd, Zn, Pb, and Cu in the PM10 fraction of road dust, with Sb levels being the highest. Statistical analyses showed that the major cause for contamination with PTEs was non-exhaust traffic emissions such as tire and brake wear. Cu and Zn isotopic compositions of road dust were related to traffic-related emission sources such as brake and tires. Pb isotopic compositions were close to that of road paint, indicating that Pb was a different source from Cu and Zn in this study. No significant health risk was posed by the PTEs. Taking into account the total length of road in Busan, a high quantity of PTEs in road dust (PM10) can have serious deleterious effects on the atmospheric environment and ecosystems. The results of metal concentrations and isotopic compositions in road dust will help identify and manage atmospheric fine particle and coastal metal contamination derived from fine road dust.