Effects of land use/cover change on heavy metal distribution of soils in wetlands and ecological risk assessment.

This study aimed to determine the impact of land use/cover changes on the heavy metal content in the Sultan Marshland and surrounding area and assess the pollution status. 54 topsoil samples (0-20 cm) were collected from the Rangeland, Farmland, Scrubland, Southern Marshland, Northern Marshland, and Dry Lake areas. The heavy metal contents of the soil samples (Cr, Pb, Fe, Zn, Cu, Co, Mn, Cd, Mo, As, and Ni) were determined using ICP-MS and ICP-OES devices. The impact of land use/cover change on soil heavy metal content was evaluated using variance analysis, while differences between groups were identified using the Duncan test. Principal Component Analysis (PCA) was conducted to identify potential sources of heavy metals. The contamination status of the soils was evaluated based on land use/cover using the Contamination Factor (Cf), Pollution Load Index (PLI), Ecological Risk Factor (Er), and Potential Ecological Risk Index (PERI). Changes in land use/cover around the Sultan Marshlands affected heavy metal distribution of the soils except for Cd. Among all land use/cover types, Fe concentration was the highest in the soils, while Cd concentration was the lowest. Soils in Southern Marshland exhibited higher average concentrations of Cr, Fe, Zn, Co, Cu, and Ni compared to other land uses/covers. Farmlands and rangelands had higher concentrations of Cd, As and Pb. Land use/cover was ranked based on the total heavy metal load in the following order in terms of average values: Southern Marshland > Scrubland > Farmland > Rangeland > Northern Marshland > Dry Lake. According to Cf, the soils in the Dry Lake were exposed to considerable levels of As contamination. Based on PLI, half of the soil sampling points in the Southern Marshland soils showed a degradation in environmental quality. Er indicated that all land uses moderately polluted with Cd. According to the average PERI, all soils under different land use/cover types were categorized as having a low ecological risk. It was believed that heavy metals originated from both natural and human activities. To ensure the sustainability of the ecosystem and to mitigate the risk of heavy metal pollution entering the food chain, it is recommended to manage farming and mining activities and land use habits.

Turbid Waters and Clearer Standards: Refining Water Quality Criteria for Coastal Environments by Encompassing Metal Bioavailability from Suspended Particles.

Suspended particulate matter (SPM) carries a major fraction of metals in turbid coastal waters, markedly influencing metal bioaccumulation and posing risks to marine life. However, its effects are often overlooked in current water quality criteria for metals, primarily due to challenges in quantifying SPM's contribution. This contribution depends on the SPM concentration, metal distribution coefficients (Kd), and the bioavailability of SPM-bound metals (assimilation efficiency, AE), which can collectively be integrated as a modifying factor (MF). Accordingly, we developed a new stable isotope method to measure metal AE by individual organisms from SPM, employing the widely distributed filter-feeding clam Ruditapes philippinarum as a representative species. Assessing SPM from 23 coastal sites in China, we found average AEs of 42% for Zn, 26% for Cd, 20% for Cu, 8% for Ni, and 6% for Pb. Moreover, using stable isotope methods, we determined metal Kd of SPM from these sites, which can be well predicted by the total organic carbon and iron content (R2 = 0.977). We calculated MFs using a Monte Carlo method. The calculated MFs are in the range 9.9-43 for Pb, 8.5-37 for Zn, 2.9-9.7 for Cu, 1.4-2.7 for Ni, and 1.1-1.6 for Cd, suggesting that dissolved-metal-based criteria values should be divided by MFs to provide adequate protection to aquatic life. This study provides foundational guidelines to refine water quality criteria in turbid waters and protect coastal ecosystems.

Inhalation exposure to toxic heavy metals in nail salon technicians and health risk assessment using Monte Carlo simulation.

OBJECTIVE: Nail salons offer a developing and diverse occupation for many women, especially the new generation. Due to the increasing apprehension surrounding heavy metals in dust caused by filing nails containing dried nail polish, the present study was designed aimed to health risk assessment of heavy metals in breathing zone of nail salon technicians (NSTs). METHODS: This is a cross-sectional study that was conducted in NSTs. The concentration of Cadmium (Cd), Lead (Pb), Nickel (Ni), Chromium (Cr) and Manganese (Mn)in breathing zone of 20 NSTs was determined using ICP-OES. RESULTS: The metal concentrations were in the following order: Mn > Pb > Ni > Cr > Cd with corresponding arithmetic mean values of0.008, 0.0023, 0.0021, 0.001 and 0.0006 mg m-3, respectively, which are exceeded the recommended levels stated in the indoor air guidelines. The average lifetime carcinogenic risk (LCR) for Cr, Cd, Ni and Pb was calculated 0.0084, 0.00054, 0.00026 and 1.44 E - 05, respectively. The LCR values of all metals (except Pb) exceeded the acceptable level set by the USEPA. The mean of Hazard quotients (HQ) for Mn, Cd, Cr, Ni and Pb were calculated to be23.7, 4.74, 2.19, 0.51 and 0.0.24, respectively. The sensitivity analysis showed that, the exposure frequency (EF) for Cr and Ni had the strong effects on generation of both LCR and HQ. Furthermore, the concentrations of Mn, Cd and Pb had strong impacts on the HQ generation and the concentration of Cd and Pb had main effects on LCR generation. CONCLUSION: To effectively reduce pollutant concentration, it is recommended to install a ventilation system near nail salon work tables and conduct continuous monitoring and quality control of nail products.

Higher heavy metal contamination indoors than outdoors during COVID-19 in Mexico City.

People spend most of their time indoors, especially during the coronavirus disease. Prolonged exposure to heavy metal-contaminated dust can be harmful to human health. The objectives of this study were to identify the contamination level in outdoor and indoor dust, compare contamination in both environments, and assess the human health risk. Two-hundred thirty-nine samples of dust were taken by Mexico City citizens in 38 homes on the weekends of May 2020. Heavy metal concentrations were measured through XRF. The contamination level was set using the contamination factor with a local and global background value, mixed linear models were used to identify indoor and outdoor differences, and USEPA human health risk methodology was used. Pb, Zn, and Cu had the highest contamination levels, followed by Sr and Mn, using both the local and global background values. The Pb, Zn, and Cu contamination was greater indoors, while higher Mn, Sr, and Fe were detected outdoors. According to the outdoor/indoor ratios, the main sources of Ca, Pb, Zn, and Cu must be indoors, while the main sources of Fe, Mn, Sr, Y, and Ti are outdoors. A human health risk was not detected, as the hazard index was lower than one. However, ailments can be developed due to exposure to Pb, Mn, and Fe in children (hazard index > 0.1). A higher risk due to Pb exposition was found indoors. Indoor environments in Mexico City were more contaminated by heavy metals and represented a higher risk to human health than outdoors during the pandemic isolation.

Difference in concentration of lead (Pb) in meat from pheasants killed using lead and iron (Fe) shotgun ammunition.

The use of lead shotgun ammunition for hunting has been banned in a few jurisdictions and habitats, principally to protect wild birds from poisoning by ingestion of spent lead shot. The EU and UK REACH processes have recently considered bans on lead ammunition throughout the European Union and United Kingdom, including assessments of possible health benefits from reduced human dietary exposure to lead from game meat. Comparisons of the mean lead concentrations in meat from gamebirds killed using lead and non­lead shotgun ammunition have not been published. We compared lead concentrations in meat from wild-shot pheasants from which lead shotgun pellets were recovered (n = 27) with those from which iron pellets were recovered (n = 20), having removed all pellets from the meat before analysis. The mean concentration of lead in meat from pheasants killed using lead shot was 2.10 mg/kg w.w., which is >20 times the European Union's maximum permitted level for the lead concentration in meat from domesticated animals. For pheasants killed using iron shot the mean was 0.07 mg/kg w.w., which is below the maximum permitted level.

Distribution of Minor and Major Metallic Elements in Residential Indoor Dust: A Case Study in Latvia.

The coronavirus disease 2019 (COVID-19) pandemic has not only brought considerable and permanent changes to economies and healthcare systems, but it has also greatly changed the habits of almost the entire society. During the lockdowns, people were forced to stay in their dwellings, which served as a catalyst for the initiation of a survey on the estimation of the metallic element content in residential indoor dust in different parts of Latvia. This article presents the study results obtained through the analysis of collected dust samples from 46 dwellings, both in the capital of Latvia, Riga, and in smaller cities. Two methods were employed for indoor dust collection: vacuum sampling and manual sampling with a brush and plastic spatula. After microwave-assisted acid extraction, the samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) in terms of the major (Na, K, Ca, Mg, Al and Fe) and minor (Mn, Ni, Co, Pb, Cr, As, Ba, Li, Be, B, V, Cu, Zn, Se, Rb, Sr, Cd, La, Ce and Bi) elements. For the data analysis, principal component analysis was performed. Among the measured metals, the highest values were determined for the macro and most abundant elements (Na > K > Ca > Fe > Mg > Al). The concentration ranges of the persistently detected elements were as follows: Pb, 0.27-1200 mg kg-1; Cd, 0.01-6.37 mg kg-1; Ni, 0.07-513 mg kg-1; As, 0.01-69.2 mg kg-1; Cu, 5.71-1900 mg kg-1; Zn, 53.6-21,100 mg kg-1; and Cr, 4.93-412 mg kg-1. The critical limit values of metallic elements in soil defined by the legislation of the Republic of Latvia (indicating the level at or above which the functional characteristics of soil are disrupted, or pollution poses a direct threat to human health or the environment) were exceeded in the following numbers of dwellings: Pb = 4, Ni = 2, As = 1, Cu = 16, Cr = 1 and Zn = 28.

Assessment of heavy metals mobilization in road-deposited sediments induced by COVID-19 disinfection.

Road-deposited sediments (RDS) on urban impervious surfaces are important carriers of heavy metals (HMs), and can contribute to urban runoff pollution. With the outbreak of COVID-19, chlorinated disinfectants (CDs) have been extensively sprayed on these surfaces. This practice may have a superposed or priming effect on HMs contaminants in RDS, yet this remains unknown. This study examined the effects of seven CDs concentration gradients (0, 250, 500, 1000, 2000, 5000, 60,000 mg/L) on the leaching and chemical forms of HMs (Cd, Cr, Ni, Pb, and Zn) in seven particle size fractions (<44, 44-63, 63-105, 105-149, 149-250, 250-450, 450-1000 µm). The results showed that CDs can promote the leaching of HMs in RDS, at the recommended CDs dose (2000 mg/L), except for Pb, the leaching amounts increased by 21.8%-237.2% compared with the untreated RDS. The alteration in the leaching were primarily attributed to the redistribution of chemical forms of HMs in RDS, specifically, the acid-extractable fractions percentage increased by 0.23%-24.39%, and the reducible fractions percentages decreased by 3.21%-38.35%. The lower oxidation-reduction potential (ORP) and alkalinity of CDs as strong oxidants were responsible for the redistribution of forms. The leaching and chemical forms of HMs vary among different particle sizes, but in any case, finer particle sizes (< 105 µm) still dominate their contribution. The current control measure of street sweeping is ineffective in removing these particles. These findings will facilitate the development of strategies for controlling urban diffuse pollution from RDS during the pandemic. Finally, this study suggests potential directions for future research.

Comparative analysis of temporal variation of heavy metal accumulation by two sea urchin species from a harbour region, including pre and post COVID 19 lock down period.

Sea urchins are marine invertebrates belonging to phylum Echinodermata, recognized as relevant biological tool for assessing environmental pollution. In the present study, we assessed the bioaccumulation potential of different heavy metals by two sea urchin species, Stomopneustes variolaris Lamarck, 1816 and Echinothrix diadema Linnaeus, 1758, collected from a harbour region, along the south west coast of India, during four different sampling periods for 2 years, from the same sea urchin bed. Heavy metals like Pb, Cr, As, Cd, Co, Se, Cu, Zn, Mn and Ni were analysed from water, sediment and different body parts of sea urchins, such as shell, spine, tooth, gut and gonad. The sampling periods also included the pre and post COVID 19 lockdown period during which the harbour activities were closed. The bio-water accumulation factor (BWAF), bio-sediment accumulation factor (BSAF) and the metal content/test weight index (MTWI) were calculated, in order to compare the bioaccumulation of metals by both the species. The results showed that S. variolaris had higher bioaccumulation potential than E. diadema, for metals like Pb, As, Cr, Co and Cd especially in the soft body parts like gut and gonad. The hard parts of S. variolaris like shell, spine, and tooth also accumulated more Pb, Cu, Ni and Mn than E. diadema. Following the lockdown period, there was a decline in the concentration of all heavy metals in water, whereas in sediment, Pb, Cr, and Cu levels were reduced. The gut and gonad tissues of both the urchins showed a decrease in the concentration of most of the heavy metals following the lockdown phase and no significant reduction was observed in the hard parts. This study reveals the use of S. variolaris as an excellent bioindicator of heavy metal contamination in the marine environment which can be employed for coastal monitoring programs.

Heavy metals in riverine/estuarine sediments from an aquaculture wetland in metropolitan areas, China: Characterization, bioavailability and probabilistic ecological risk.

Aquaculture wetlands, particularly those located within urban areas, are fragile ecosystems due to urban and aquaculture impacts. However, to date, there are no reports on the combined toxicity of heavy metal mixtures in aquatic biota in sediments from aquaculture wetlands in metropolitan areas. Thus, the characterization, bioavailability, and ecological probability risk of heavy metals were studied in the riverine/estuarine sediments of the Rongjiang River in an aquaculture wetland in Chaoshan metropolis, South China. In the study area, the average total concentrations (mg/kg) were 2.38 (Cd), 113.40 (Pb), 88.27 (Cr), 148.25 (Ni), 62.08 (Cu), 125.18 (Zn), 45,636.44 (Fe), and 797.18 (Mn), with the Cd pollution being regarded as extremely serious based on the enrichment factor (EF). There are two main sources of heavy metals in the study area; Ni, Pb, Zn, Fe and Mn are mainly from domestic waste, while Cr, Cd and Cu are possibly associated with industrial production activities. The bioavailability of most heavy metals accounted for more than 20% of the total concentration. The combined toxicity of heavy metal mixtures based on probabilistic risk assessment suggests that the surface sediments of the Rongjiang River and its estuary had a 15.71% probability of toxic effects on aquatic biota.

Improving the efficiency of machine learning in simulating sedimentary heavy metal contamination by coupling preposing feature selection methods.

Sediment cores were collected from Taihu Lake in China. The chronology was determined by radionuclide. Heavy metals and magnetic properties of each core slice were assessed, respectively. The concentrations of most heavy metals in sediments surged at 20 cm from the surface, accompanying the increase in the concentrations of single-domain magnetic particles. This may be resulted from the influence of anthropic activities on the lake's environment after the 1970s. Two feature selection methods, random forest (RF) and maximal information coefficient (MIC), were combined with support vector machine (SVM) model to simulate heavy metals, with the inclusion of selected magnetic and physicochemical parameters. Compared with the modeling results obtained with the full set of parameters, a reasonable simulation performance was obtained with RF and MIC. RF performed better than MIC by increasing the R2 of simulation models for Cd, Cr, Cu, Pb, and Sb. For heavy metals with high ecological risks (As, Cd, Cr, Hg, Pb, Sb), the correlation coefficients for observed and predicted data ranged from 0.73 to 0.97 with only 14-27% of the parameters selected by RF as input variables. The RF-RBF-SVM enabled heavy metal predictions based on the magnetic properties of the lake sediments.

Combining spatial autocorrelation with artificial intelligence models to estimate spatial distribution and risks of heavy metal pollution in agricultural soils.

Information on spatial distribution and potential sources of heavy metals in agricultural lands is very important for human health and food safety. In this study, pollution degree of lead (Pb), cadmium (Cd), and nickel (Ni) in Yüksekova Plain, located on the border in the southeastern part of Turkey, was evaluated by geoaccumulation index (Igeo), modified contamination factor (mCdeg), and Nemerow pollution index (PINemerow) combined with spatial autocorrelation using deep learning algorithms. A total of 304 soil samples were collected from two different depths (0-20 and 20-40 cm) in the study area, which covered 17.5 thousand ha land. Covariates were determined for spatial distribution models of Pb, Cd, and Ni by factor analysis (FA). Spatial distribution models for surface soils were developed using pedovariables (silt, sand, clay lime, organic matter, electrical conductivity, pH, Ca, and Na) determined by the FA and Igeo and mCdeg values by artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models. The estimation success of models for different depths was assessed by root mean square error (RMSE), mean absolute percent error (MAPE), and Taylor diagrams. The RMSE and MAPE values showed a strong correlation between heavy metal contents and the covariates. The RMSE values of ANN-Ni0-20, ANN-Ni20-40, ANN-Pb0-20, ANN-Cd0-20, and ANN-Cd20-40 models (0.01240, 0.07257, 0.0039, 0.00045, 0.00044, and 0.04607, respectively) confirmed the success of the models. Likewise, the MAPE values between 0.2 and 8.5% indicated that all models were very good predictors. In addition, the Taylor diagrams showed that the estimation performance of ANFIS and ANN models are compatible. The IgeoNi and IgeoPb values in both models at both depths indicated that strongly to extremely polluted (4-5) areas are quite high in the study area, while the IgeoCd values revealed that unpolluted areas are widespread. The mCdeg index value showed a moderate to high contamination at the first depth, while very high contamination at the second depth in most of the study area. Spatial distribution of PINemerow revealed that moderate pollution (2-3) is common in both soil depths of the study area. The PINemerow of subsurface layer was between 0.91 and 1 (warning limit class) in a small part of the study area. The results showed that vertical mobility of heavy metals is closely related to pedovariables. In addition, the ANN and ANFIS models are capable of exhibiting the heterogeneity in the spatial distribution pattern of high variation in the data. Thus, the locations with extreme contamination have been accurately determined. The pollution indices calculated considering the commonly used international reference values revealed that heavy metal pollution in some part of the study area reached the detrimental levels for human health and food safety. The results suggested that the pollution indices were more successful than simple heavy metal concentrations in interpreting the pollution risk levels. High-resolution spatial information reported in this study can help policy makers and authorities to reduce heavy metal emissions of pollutants or, if possible, to eliminate the pollution.

Dynamics of heavy metals during the development and decomposition of leaves of Avicennia marina and Kandelia obovata in a subtropical mangrove swamp.

In mangrove wetlands, leaves make up a high proportion of the plant biomass and can accumulate heavy metals from contaminated sediment. Despite this, it is still unclear how heavy metal concentrations in leaves change as they develop and how metals in senescence leaves are recycled back into the mangrove ecosystems during decomposition. The present study aims to investigate the dynamics of six heavy metals (Cu, Zn, Cr, Ni, Cd, and Pb) in leaves of two common mangrove plants, Avicennia marina and Kandelia obovata, at different stages of development (young, mature, and senescent) and leaf litter decomposition (from 0 to 20 weeks). Based on litterbag experiments in a subtropical mangrove swamp, both plant species showed similar trends in alternations of the six heavy metals during leaf development, that was, decreased in Cu and Zn but increased in Pb, while Cr, Ni, and Cd remained steady. All heavy metals in litter gradually increased in concentration during decomposition. By the end of the 20-weeks decomposition, the concentrations of Cu, Zn, and Cd in decayed leaves were comparable to those in sediment, with Cu, Zn, and Cd at approximately 18, 75, and 0.2 mg·kg-1, respectively, while Cr (66 mg·kg-1), Ni (65 mg·kg-1), and Pb (55 mg·kg-1) were lower than those in sediment, indicating that metals were not retained in litter but recycled back to the sediment. Tannins in mangrove leaf litter might chelate heavy metals, affecting their migration and transformation of heavy metals in estuarine mangrove wetlands. The findings of our study provide insight into the interactions between toxic heavy metals and mangrove plant species during leaf development, representing the first example of how most metals would be retained in leaf litter during decomposition, thereby reducing their release to estuarine and marine ecosystems.

Plant growth promoting rhizobacteria modulates the antioxidant defense and the expression of stress-responsive genes providing Pb accumulation and tolerance of grass pea.

To ensure the success of phytoremediation, it is important to consider the appropriate combination of plants and microorganisms. This study was conducted to get a better insight into the underlying molecular and biochemical mechanism of grass pea (Lathyrus sativus L.) induced by plant growth promoting rhizobacteria (PGPR), when exposed for 3, 6, 9, and 14 days to 1 mM Pb in a hydroponic system. The significant positive effect of bacterial inoculation was reproduced in various parameters. Results indicated that inoculation of PGPR significantly increased the accumulation of Pb by 20%, 66%, 43%, and 36% in roots and by 46%, 55%, 37%, and 46% in shoots, respectively after 3, 6, 9, and 14 days of metal exposure compared to the uninoculated plants. The metal accumulation in grass pea plants triggered a significant elevation in the synthesis of non-protein thiols (NPT), particularly in inoculated plant leaves where it was about 3 and 2-fold higher than the uninoculated set on the 6th and the 9th day. Nevertheless, Pb treatment significantly increased oxidative stress and membrane damage in leaves with the highest hydrogen peroxide (H2O2) production and tissue malondialdehyde (MDA) concentration recorded in uninoculated plants. Furthermore, the PGPR inoculation alleviated the oxidative stress, improved significantly plant tolerance, and modulated the activities of antioxidant enzymes (SOD, CAT, APX, GR, DHAR, and MDHAR). Similarly, the expression patterns of LsPCS, LsGCN, LsCNGC, LsGR, and LsGST through qRT-PCR demonstrated that bacterial inoculation significantly induced gene expression levels in leaves 6 days after Pb treatment, indicating that PGPR act as regulators of stress-responsive genes. The findings suggest the key role of PGPR (R. leguminosarum (M5) + Pseudomonas fluorescens (K23) + Luteibacter sp. + Variovorax sp.) in enhancing Pb accumulation, reducing metal toxicity, strengthening of the antioxidant system, and conferring higher Pb tolerance to grass pea plants. Hence, the association Lathyrus sativus-PGPR is an effective tool to achieve the goal of remediation of Pb contaminated sites.

Chemical fractionation of particulate-bound metal(loid)s to evaluate their bioavailability, sources and associated cancer risk in India.

Eleven potentially toxic metal(loid)s (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), proven source markers of mineral based coal-fired industrial emissions and vehicular exhausts, were analysed using the four steps sequential extraction method to evaluate metal(loid)s concentration, in total and fractions of bioavailable and non-bioavailable for fine (PM2.5) and coarse (PM10-2.5) particulate modes. A total of 26-day-wise samples with three replications (total number of samples = 78) were collected in January-December 2019 for each PM10 and PM2.5 at an urban-residential site in India. In both the coarse and fine particulate modes, Pb and Cr have respectively shown the highest and lowest total concentrations of the measured metal(loid)s, indicating the presence of coal-fired power plants and heavy vehicular activities near to study area. In addition, Mn has shown highest bioavailable fraction for both coarse and fine particulate modes. More than 50 % of metal(loid)s concentration, in total to a bioavailable fraction (BAF) were observed in case of As, Cd, Cr, Co, Mn, Ni, and Pb of PM2.5. Mn and Zn have shown similar behaviour in the case of coarse particulate mode. Source apportionment of metal(loid)s bioavailable fractions using positive matrix factorization (PMF 5.0) has found three significant sources: crustal and natural dust (30.04 and 39 %), road traffic (49.57 and 20 %), and industrial emission (20.39 and 41 %) for coarse and fine particulate mode, respectively. Cancer risk through the inhalation pathway was high in total concentration but lower in BAF concentration in both age groups (children and adults).

Pollution characteristics and risk assessment of potentially toxic elements of fine street dust during COVID-19 lockdown in Bangladesh.

Due to the COVID-19 pandemic, Bangladesh government took the measure like partial lockdown (PL) and complete lockdown (CL) to curb the spread. These measures gave a chance for environmental restoration. In this study, street dust samples were collected during PL and CL from four main urban land use categories in Dhaka city, such as industrial area (IA), commercial area (CA), public facilities area (PFA), and residential area (RA). Ten potentially toxic elements (Cr, Mn, Zn, Fe, Pb, Cu, Co, Ni, As, and Cd) in fine street dust particles (diameter < 20 µm) were determined following aqua-regia digestion and measured by inductively coupled plasma mass spectrometry (ICP-MS) to evaluate distribution, pollution sources, and potential risks to ecological systems and human health. Results showed that during PL, the concentrations of toxic elements in the dust were higher than that of CL. Cd and Fe were lowest and highest in concentration with 1.56 to 41,970 µg/g and 0.82 to 39,330 µg/g in partial and complete lockdown period respectively. All toxic elements were detected at high levels above background values where Fe with the highest and Cd with lowest concentrations, respectively. By land use, the levels of toxic elements pollution followed IA > PFA > RA > CA. Correlation analysis (CA), principal component analysis (PCA), and hierarchal cluster analysis (HCA) revealed that the sources of these analyzed toxic elements were mainly from anthropogenic which are related to industrial and vehicular or traffic emissions. Enrichment factor (EF), geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI) also suggested that the dust was more polluted during PL. Exposure of toxic elements to human was mainly via skin contact followed by ingestion and inhalation. Hazard quotient (HQ) values were < 1 except for Mn through dermal contact at all sites during partial and complete lockdown, similar to hazard index (HI), while Cr further showed high non-carcinogenic risks to children. Generally, children HI values were about 5-6 times higher than those of adults, suggesting a greater vulnerability of children to the health concerns caused by toxic elements in street dust. Carcinogenic risk (CR) values via ingestion pathway indicated all elements (except Pb) had significant health effect, while CR value by inhalation results showed no significant health effect. Cumulative carcinogenic risk (CCR) value had significant health effect except Pb in all land use categories. CCR values decreased during CL and reached at acceptable limit for most of the cases. This research provides a message to the local governments and environmental authorities to have a complete assessment of toxic elements in the street dust of Dhaka megacity in order to assuring public health safety and ecological sustainability.

Identifying the origin of lead poisoning in white-backed vulture (Gyps africanus) chicks at an important South African breeding colony: a stable lead isotope approach.

Elevated lead levels in scavenging raptors can originate from a variety of environmental and anthropogenic sources, including soil, water, mining activities and legacy lead from leaded fuel, but has mostly been attributed to fragments of lead-based ammunition embedded in the tissues of carcasses. To identify the origins of lead in the tissues of white-backed vulture (Gyps africanus) chicks at Dronfield Nature Reserve, South Africa, we used MC-ICP-MS to compare the isotopic composition of lead in blood samples to those of soil in the chicks' immediate environment, different mining activities in South Africa and lead ammunition commonly used in hunting and game management practices. The isotopic ratios in vulture blood samples ranged widely (207Pb/206Pb: 0.827-0.911), but fell within those measured for ammunition (0.761-0.938). Dronfield water can be excluded as a significant source, as the lead concentration for water was below detection limits. Uranium, coal, atmospheric Pb, legacy Pb from fuel and Pb mining can also be excluded as significant sources, based on the limited overlap with Pb isotopic ratios measured in vulture blood. Whereas 55% of chicks we sampled displayed isotopic ratios consistent with Dronfield soil, the low local Pb concentration and the low extractable Pb levels in South African soil in general, imply that soil Pb is unlikely the major source of Pb in WBV chicks, especially in birds with elevated blood Pb levels, i.e. > 20 µg/dL. Our results, when considered in the context of vulture feeding ecology and low Pb levels in non-scavenging birds in South Africa, imply the major source of elevated Pb levels in WBV chicks to be fragments of lead-based ammunition embedded in the carrion fed to them by their parents.

In-vitro inhalation bioavailability estimation of Metal(oid)s in atmospheric particulate matter (PM2.5) using simulated alveolar lysosomal fluid: A dialyzability approach.

A novel in-vitro method, by using synthetic body fluids, human physiological conditions and a simulated air-blood barrier (by using a dialysis membrane) has been developed and applied to assess in-vitro inhalation bioavailability of metal(oid)s associated to particulate matter (PM2,5) samples collected from an industrial site of the Northwest of Spain. A validated analytical methodology based on inductively coupled plasma mass spectrometry (ICP-MS) was used to analyse metal(oid)s concentrations in bioavailable fractions. This approach would be a more realistic human health risk assessment since considering processes that occur in human body in contrast the overestimation derived from current models (which consider environmental concentrations). Metal(oid)s such as Cu and Mo seemed to be the most bioavailable (mean in-vitro bioavailability ratios higher than 70%); Ba, Cd, Mn, Pb, Rb, Sb, Sn, V and Zn shown mean ratios between 20 and 60%, while low in-vitro bioavailability ratios (less than 20%) were observed for metal(oid)s such as Al, Co, Cr, Fe, Ni, Ti, and Tl. Health risk assessment via inhalation based on hazard carcinogenic and non-carcinogenic indexes (HIc and HInc, respectively) were performed considering three exposure scenarios using both inhalation bioavailable and total metal(oid)s concentrations in PM2.5 samples, suggesting no risk to human health. The influence of chemical composition on in-vitro bioavailability ratios was obtained, pointing out that inhalation ratios of Al, Ba, Cr, Cu, Fe, Ni, Pb and V seem to be affected by sea salt and/or crustal and/or biogenic and/or anthropogenic content of PM2.5.

Comparison of concentrations of chemical species and emission sources PM2.5 before pandemic and during pandemic in Krakow, Poland.

Observations of air pollution in Krakow have shown that air quality has been improved during the last decade. In the presented study two factors affecting the physicochemical characteristic of PM2.5 fraction at AGH station in Krakow were observed. One is the ban of using solid fuels for heating purposes and the second is COVID-19 pandemic in Krakow. The PM2.5 fraction was collected during the whole year every 3rd day between 2nd March 2020 and 28th February 2021 at AGH station in Krakow. In total 110 PM2.5 fraction samples were collected. The chemical composition was determined for these samples. The elemental analysis was performed by energy dispersive X-ray fluorescence (EDXRF) technique, ions analysis was performed by ion chromatography (IC) and black carbon by optical method. In order to identify the emission sources the positive matrix factorization (PMF) was used. The results of such study were compared to similar analysis performed for PM2.5 for the period from June 2018 to May 2019 at AGH station in Krakow. The PM2.5 concentration dropped by 25% in 2020/2021 in comparison to 2018/2019 at this station. The concentrations of Si, K, Fe, Zn and Pb were lowering by 43-64% in the year 2020/2021 in comparison to 2018/2019. Cu, Mn, Zn and Pb come from mechanical abrasion of brakes and tires while Ti, Fe, Mn and Si are crustal species. They are the indicators of road dust (non-exhaust traffic source). Moreover, the annual average contribution of traffic/industrial/soil/construction work source was reduced in 2020/2021 in comparison to 2018/2019. As well the annual average contribution of fuels combustion was declining by 22% in 2020/2021 in comparison to 2018/2019. This study shows that the ban and lockdown, during COVID-19 pandemic, had significant impact on the characteristic of air pollution in Krakow.

Potentially toxic elements (PTEs) in Gomti-Ganga Alluvial Plain, associated human health risks assessment and potential remediation using novel-nanomaterials.

The health risks associated with consumption of water from river Gomti polluted with potentially toxic elements (PTEs), including As, Fe, Pb, Cd, Mn, Cr, Ni, and Hg were investigated at the initiation of unlocking of COVID-19 lockdown and compared with pre-COVID-19 lockdown status. In the current investigation, the total hazard index (THI) values exceeded the acceptable limit of "unity" at all sampling stations. The use of river water for drinking and domestic purposes by millions of people with high THI values has emerged as a matter of huge concern. The individual hazard quotients associated with Cd and Pb were found to be most severe (> 1). A vivid difference between the THI values during the two study phases indicated the positive impact of COVID-19 lockdown signifying the prominent impact of anthropogenic activities on the PTE concentrations. The closure of local manufacturing units (textile, battery, etc.) emerged as a potential reason for decreased health risks associated with PTE levels. The higher susceptibility of children to health risks in comparison with adults through the values of THI and HQs was interpreted across the study area. Potential remedial measures for PTE contamination have also been suggested in the study.

Identifying contamination of heavy metals in soils of Peruvian Amazon plain: use of multivariate statistical techniques.

The Peruvian Amazon plain has abundant natural resources and is home to great biodiversity, which makes it an area with high economic potential. However, the use of its resources through various activities has contributed to the release of heavy metals (HMs) into its soils, generating severe pollution problems which have mainly affected the health of local populations and their ecosystems. Currently, there are no comprehensive studies that have identified the specific sources of contamination by HMs in the soils of this part of the Peruvian territory. In this sense, this research aims to identify the possible sources of contamination by HMs in the soils of the Peruvian Amazon plain to focus efforts on the establishment of adequate measures for the protection of the health of people and the ecosystem. In the present study, samples of topsoils (0-20 cm depth) and subsoils (100-150 cm depth) were collected for the analysis of 11 HMs (Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn, Be, and Hg) in 48 sites located in four regions of the Peruvian Amazon plain (Loreto, Amazonas, San Martín, and Ucayali), over the year 2019. The enrichment factor and geoaccumulation index were applied to assess contamination levels of HMs. The results indicated that topsoils and subsoils presented a greater enrichment by the elements Be and Pb, and were classified as moderately contaminated. Likewise, the integral analysis of these indexes together with principal component analysis, hierarchical cluster analysis, correlation analysis, and coefficient of variation allowed the identification of potential sources of contamination by HMs. As a result, Fe, Co, Zn, Ni, V, and Cr were associated with natural or lithogenic sources (parent material, crude oil deposits, and organic matter decomposition). Hg was attributed to anthropogenic sources (illegal gold mining, atmospheric deposition, and vehicle emissions). Be, Pb, Cu, and Mn originated from natural sources (parent material, crude oil deposits, decomposition of organic matter, and forest fires) and anthropogenic (areas degraded by solid waste, illegal gold mining, agriculture, and hydrocarbons). These findings provide essential information to establish regulations and prevent and control HM contamination in soils of the Peruvian Amazon plain.