Heavy metal concentrations in roadside plants (Achillea wilhelmsii and Cardaria draba) and soils along some highways in Hamedan, west of Iran

Assessment of distribution, contamination, ecological risks, and sources of heavy metals in soil from metal recycling sites

Developing the metal recycling industry to meet the demand for green resource recycling and utilization has raised environmental concerns. However, long-term processing and stacking of waste heavy metals (HMs) may lead to negative impacts on the soil environment. This study investigated the distribution of HMs such as, Cd, Cu, Pb, Hg, Ni, Co, and V, in soil from metal-recycling sites. A total of 63 soil samples were collected to assess the degree of soil contamination by HMs and trace the sources of HMs. The single pollution index was calculated based on the background values of reference elements to determine the level of HMs pollution. Except for As, the average concentrations of seven HMs in the surface soil exceeded their background values. It is worth noting that according to the geo-accumulation index (Igeo) and pollution load index (PLI) revealed that Hg, Cu, and Pb exhibited relatively high pollution levels, while the potential ecological risk index (RI) and Nemerow risk index (NRI) indicated that Hg and Cd posed higher ecological risks. The source apportionment results indicate that As, Cd, Cu, Pb, and Hg have significant homology, mainly derived from the composite source of human activities and natural sources; V mainly comes from industrial process sources; Ni and Hg mainly come from atmospheric deposition sources; Co is mainly influenced by natural factors. This study provides reference for implementing pollution control measures and promoting precise remediation work in areas affected by metal recycling activities.

Preliminary Assessment of Essential and Potentially Toxic Elements in the Most Common Spices in a Developing Country: Health Hazard Implication

In the current study, total concentrations of essential and potentially toxic elements (Ba, Ca, K, P, Na, Mg, Cr, Ni, Cu, Fe, Mn, Zn, As, Cd, and Pb) in the most common nine spices (Nigella sativa, Capsicum annum, Piper guineense, Capsicum carvi, Elettaria cardamomum, Zingiber officinale, Piper nigrum, Cinnamomum verum, and Curcuma longa) of fields and markets of Bogra district (Bangladesh) were determined using inductively coupled plasma mass spectrometry following acid digestion. The findings of the study indicate a good source of essential elements like Ca, K, Na, P, Mg Fe, Zn, and Mn in spices. The average concentrations of K, P, Ca, Mg, Na, Fe, Ba, Cu, Mn, Zn, Ni, Cr, As, Pb, and Cd in spices were 697, 190, 168, 112, 97.2, 7.35, 6.29, 4.36, 4.21, 3.91, 2.99, 0.81, 0.17, 0.08, and 0.03 mg/kg, respectively. The concentrations of Cr, Cu, and Pb were higher than the recommended level (0.5, 4.5, and 0.1 for Cr, Cu and Pb), which indicates that people would experience potential risks from spices. The daily intake values of all the metals were lower than the maximum tolerable daily intake (MTDI). Considering child exposure group, total target hazard quotient (THQ) values for all studied elements from a single spice or all examined spices exceeded the threshold value (THQ > 1.0), indicating that the children posed a potential non-cancer risk to the potentially toxic elements. Consumption of Piper guineense, Nigella sativa, Cinnamomum verum, and Curcuma longa may pose carcinogenic health risk due to an incremental lifetime cancer risk (ƩTR) value higher than 10-4.

Fractionation, chemometric analysis, and sophisticated risk assessment indices to appraise sediment contamination of a tropical mangrove forests, the Red Sea

This paper adds a new perspective to Ras Mohamed Protectorate mangrove sediment quality studies in terms of bioavailability, mobility, human and eco-environmental risk of various potential toxic elements (PTEs). Fe > Mn > Pb > Cu > Cd was the order in which the PTE levels declined. Residual fraction controlled the geochemical speciation of all elements. The following was the order of the mean percentages of mobile elements in sediments: Mn > Fe > Pb > Cu > Cd. All sediment samples had low to moderate risk, according to synergistic indices (GCF, mRAC, PETI-A and PTEI-B). Mn was the primary ecological risk PTE contributor. According to the suggested individual indices, Mn is the most mobile and bioavailable element (0.4-1), whereas Cd, Cu, Fe, and Pb have moderate mobility and bioavailability (MI 0.1-0.4 and BI 0.1-0.4, respectively). The current PTE exposure in sediments did not constitute a significant health concern (THQ < 1 and LCR < 10-4).

Environmental risks of heavy metals in railway soils: Challenges to ecosystem management

Heavy metal contamination near high-traffic railways presents serious risks to food safety, particularly in agricultural regions adjacent to rail transport corridors. This study investigated heavy metal in soils and wheat plants along the Arak-Tehran railway in Iran, focusing on how distance from the railway and soil depth influence contamination levels. Soil and plant samples were collected at intervals from 0 to 300 m away from the railway to assess the concentrations of nickel (Ni), cadmium (Cd), lead (Pb), and zinc (Zn). The findings indicated that heavy metal concentrations decreased with increasing distance from the railway, with surface soils showing higher contamination than subsurface soils. Soil parameters like Organic matter, calcium carbonate, and cation exchange capacity were positively correlated with the absorption of heavy metals. The Geoaccumulation Index (Igeo) classified the area as highly polluted, particularly by cadmium (Igeo = 6.39), nickel (Igeo = 6.72), and lead (Igeo = 4.01). Contamination factor (Cf) values for nickel (158.47), cadmium (125.67), and lead (24.23) along with the average Pollution Load Index (PLI) of 31.5, confirm severe soil contamination. The translocation factor analysis revealed that cadmium had the highest translocation rate from roots to shoots, followed by zinc, nickel, and lead. Both the aerial and root parts of wheat contained heavy metal concentrations exceeding FAO/WHO safety limits, posing a potential health risk to populations consuming crops from this area. Despite high soil contamination, heavy metals were efficiently transferred to the aerial parts of the wheat, particularly cadmium and lead. These findings underscore the health risks posed populations consuming wheat and other crops grown in agricultural zones near the Arak-Tehran railway, where heavy metal contamination from the railway infrastructure can impact food safety.

Comprehensive analysis and risk assessment of fine road dust in Abbottabad city (Pakistan) with heavy traffic for potentially toxic elements

Human activities have far-reaching impact on natural ecosystems, causing increasing disturbances and disruptions to the delicate balance of the environment. Poor land use planning, urbanization, infrastructure development, and unplanned tourism exacerbate contamination and degradation in tourist destinations, yet the pollution of potentially toxic elements (PTEs) in these environments remains inadequately explored. To address this issue, we investigated the concentrations of acid-digested PTEs in road dust in Abbottabad city (Pakistan) with heavy traffic. The current study also evaluated PTE associated pollution, ecological and health risks, and potential sources of these elements. The average concentrations (in mg kg-1) of PTEs in road dust were highest for Fe (15540), followed by Mn (304), Zn (139), Cu (50.0), Pb (21.5), Cr (13.0), Ni (10.3), Co (6.66), and Cd (0.236). The levels of Co, Cr, Mn, Ni, and Fe were below the upper continental crust (UCC) averages, while Cd, Cu, Pb, and Zn exceeded them. Spatially, Cd, Cu, Pb, and Zn were found at higher levels near traffic hotspots, bus stands and automobile workshops. Road dust in Abbottabad exhibited unpolluted to moderate pollution levels (geo-accumulation index), with Cd, Cu, Zn, and Pb at 23 % of the sites. The enrichment factor results indicated a significant anthropogenic influence, with Cd being significantly enriched and Zn, Cu, and Pb moderately enriched. The contamination factor results revealed moderate contamination by (Cd: 2.62, Zn: 2.08, Cu: 1.79, Pb: 1.27). Single metal risk index showed that 61 % of the sites posed considerable to very high ecological risks due to Cd, which was highlighted as a significant concern. The absolute principal component scores-multiple linear regression model identified three factors contributing to PTE pollution: lithogenic (Co, Fe, Mn, Ni), traffic-related (Cd, Cu, Pb, Zn), and mixed sources (Cr), with contributions of 52.8 %, 35.8 %, and 11.4 %, respectively. The PTE hazard quotient and total hazard index values for children and adults were below the safe risk level of 1, indicating no non-carcinogenic health risks. The cumulative carcinogenic risk values to the residents were also within acceptable limits. However, children's susceptibility to non-carcinogenic risks is higher due to their behavior and lower body weight. This study highlights the accumulation of PTEs in Abbottabad's environment, which poses challenges to long-term sustainability, particularly amid unplanned tourism. Therefore, urgent measures are necessary to mitigate PTE pollution and preserve tourist spots and public health.

Internal and external spatial analysis of trace elements in local crayfish

Pollution in urban environments is a major health concern for humans as well as the local wildlife and aquatic species. Anthropogenic waste and discharge from storm drainage accumulate nutrients and environmental contaminants in local water systems. Locating contaminated sites using water samples over the vast landscape is a daunting task. Crayfish thrive in urban environments and have been used for biomonitoring pollutants. This study aimed to use crayfish as sentinels to monitor for elements in local environments. In this study, crayfish were used to measure metals and metalloids in lotic environments using ICP-OES analysis of abdominal and exoskeletal tissue. Using cluster analysis, geographical zones of trace element accumulation were determined. Eighteen total elements were analysed providing baseline data on local genera, biometric data, and element concentrations averaging 267.3 mg/kg Mn in the exoskeleton and with Zn averaging 6.88 mg/kg being significantly higher in the abdomen. Correlations of elements with biometric data allowed for internal analyses of elements. The elements As, Cr, Hg, Ni, and Tl demonstrated equivalent concentrations in both tissues. The crayfish locations with high abundance of elements allowed for the determination of contaminated areas with higher accumulations being areas of active urban development. These analyses gave measurable results of metal and metalloid to pinpoint potential sources of pollutants. Since crayfish are consumed globally as a food source, these methods can be used to determine the risk of toxic metals being passed through the food chain to the public.

Efficient Removal of Cadmium (Cd2+) from Aqueous Solutions by Chitosan@fig Branch Biochar: Adsorption Performance and Enhanced Complexation

In this study, fig branch biochar (FBB) was modified by chitosan to improve the Cd2+ adsorption performance from an aqueous solution. The surface area, pores, and functional groups of chitosan-modified fig branch biochar (CMFBB) were characterized by DTG-TGA, BET, SEM-EDS, FTIR, and XRD. In addition, the impact of various conditions on the Cd adsorption performance of the biochar was analyzed, including dosage, initial pH, concentration, temperature, reaction time, and coexisting cations. The adsorption kinetics, isotherms, and practical applications were also investigated. Under the optimized conditions including pH 6, adsorbent dose 2 g L-1, reaction time 90 min, Cd2+ concentration 100 mg L-1, and 25 °C, the Cd2+ adsorption capacity was 62.25 mg g-1, representing a 78.26% increase compared to FBB. The adsorption data for Cd2+ by CMFBB were found to be well-described by the pseudo-second-order kinetic and Langmuir isothermal models, indicating that a monolayer chemical adsorption process occurred. The Cd2+ adsorption was a spontaneous endothermic process, and the coexisting cations exerted negligible influence on the adsorption process. After five adsorption-desorption cycles, CMFBB maintained an adsorption efficiency of 92.3%, demonstrating excellent regeneration capability. The quantification of adsorption mechanisms suggested that physical adsorption, cation exchange, precipitation, complexation, and π-π interactions accounted for 3.70, 2.50, 33.04, 58.76, and 2.0% of the total adsorbed Cd2+ in CMFBB, respectively. Compared with FBB, the level of CMFBB increased 26.52% in complexation. This work implies that CMFBB has great potential as an effective absorbent for treating Cd2+ polluted water.

Pollutant accumulation characteristics of substrates and mechanism of microbial action in different ecological ditches

Ecological ditches serve as one of the important measures for the concentrated infiltration of stormwater in the construction process of sponge cities. Prolonged concentrated infiltration of stormwater can lead to the accumulation of pollutants and pollution risks in the substrate of ecological ditches. In this study, two different substrate ecological ditches were constructed, namely, a combined substrate ecological ditch with zeolite + ceramsite (EA), and a biological substrate ecological ditch (EB). The accumulation characteristics of pollutants and microbial mechanisms in the ecological ditches were evaluated by simulating the cumulative rainfall test for three years. Results showed that there was serious total nitrogen (TN) contamination in both EA and EB substrates, with mean values of 718.6 and 802.7 mg/kg, respectively. The average contents of potentially toxic elements (Cu, Pb, and Zn) in EA and EB substrates were higher than the background values of soil elements in China, and Cu posed considerable ecological risks to the environment. Proteobacteria was the dominant phylum and accounted for 32.85-41.33% in two ditches; the total number of denitrifying functional bacterial genera in the EB increased by 1.53% than EA, which proved that the biological substrate was more favourable for the growth of denitrifying microorganisms. The accumulation characteristics of pollutants and microbial mechanisms in the ecological ditches with different substrates above provide a reference for extending the service life of ecological ditch facilities.

Source apportionment, ecological and health risks of potentially toxic elements in street dusts across different land uses in city of Kermanshah, Iran

In this study, the contamination, ecological and human health risks as well as source apportionment of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and V in street dusts of different land-uses in Kermanshah, Iran were investigated. A total of 192 dust samples were taken from 16 sites and were analyzed for their elemental contents using ICP-OES. The computed mean values for the geo-accumulation index (I-geo) and the pollution index (PI) ranged from - 6.07 to 2.67 and from 0.023 to 9.58, respectively, indicating 'unpolluted' to 'moderately to heavily polluted', and 'slight to very high polluted' pollution levels, respectively. The pollution load index (PLI) with a cumulative mean value of 1.03 reflected moderate pollution levels across the entire study area. Moreover, the ecological risk (RI) of 135 indicated moderate ecological risks throughout the study region. The mean hazard index (HI) values for the analyzed potentially toxic elements (PTEs) for both adults and children were all within the safe limit (< 1). Furthermore, the total carcinogenic risk (TCR) values showed that the carcinogenic risks associated with As, Cd, Cr, and Ni for both target populations were at tolerable to unacceptable levels. The positive matrix factorization (PMF) model identified traffic emissions and sources, fossil fuel combustion and natural sources, and industrial emissions as the major sources of tested elements. Hence, a thorough investigation into the sources of ecological health risks associated with dust contamination from potentially toxic elements (PTEs) is recommended for future studies.

Novel Nanocomposite of Carbonized Chitosan-Zinc Oxide-Magnetite for Adsorption of Toxic Elements from Aqueous Solutions

Herein, a novel nanocomposite (carbonized chitosan-zinc oxide-magnetite, CCZF) was developed to effectively remove toxic elements in water remediation. Combining the high adsorption capacities of chitosan with the magnetic properties of magnetite and the chemical stability of zinc oxide, the combination of these unique properties makes it an efficient and versatile material that offers a sustainable solution for water purification. The (CCZF) nanocomposite was synthesized through the coprecipitation method and characterized using various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. The results showed impressive maximum adsorption capacities of 891.34 mg/g for Ni2+, 1269.35 mg/g for Co2+, and 1502.67 mg/g for Cu2+, fitting well with a modified Langmuir isotherm model. The adsorption process was spontaneous and endothermic, characterized by low positive enthalpy (ΔH) values ranging from 10.95 to 34.9 kJ/mol, indicative of the physical adsorption mechanism. Additionally, the nanocomposite demonstrated good reusability over multiple adsorption and desorption cycles. This research highlights the potential of the (CCZF) nanocomposite as a highly efficient, reusable adsorbent for the removal of toxic elements from aqueous solutions, contributing significantly to environmental remediation efforts and pollution control.

Characteristics and sources of potentially toxic elements in road-deposited sediments at the Port of Busan, South Korea: A key contributor to port sediments pollution

This study investigated the spatial distribution and chemical characteristics of potentially toxic elements (PTEs) in road-deposited sediments (RDS) at the Port of Busan by size fraction. Enrichment factor (EF) values for Zn, Cd, and Sb in fine RDS <250 μm were 52-69, 49-78, and 46-44, respectively, indicating 'extremely high enrichment'. Various statistical analyses, including PCA and PMF models, revealed a strong correlation between pollution levels in RDS <250 μm and vehicle type, identifying non-exhaust emissions (NEE) of vehicles as a primary source of PTEs in RDS from the port. The risk index (RI) value of fine RDS ranged from 649 to 2238, indicating that the entire study area could be classified as having a 'significant ecological risk,' with higher values observed in heavy-duty vehicles (HDV) areas. The study underscores the need for effective NEE management to mitigate the environmental impact of ports on marine ecosystems.

Evaluation of the potentially toxic elements and radionuclides in the soil sample of Novaya Zemlya in the Arctic Circle

The study presented here elucidate the concentrations of radionuclides and potentially toxic elements in the soil samples around the Novaya Zemlya in the Russian Arctic zone, determined using HPGe gamma spectrometry, inductively coupled plasma optical emission spectrometry and direct mercury analyzer. The average detected concentrations for 226Ra, 232Th, 40K, 235U and 137Cs were 36.40, 46.06, 768, 2.06 and 4.71 Bq/kg, respectively. At many sampling sites, the concentrations of potentially toxic elements (Zn, Cu, Pb, Cd, Ni, and Cr) were higher than the natural levels. Positive Matrix Factorization analysis revealed the contribution of oil dumps (32%), natural sources (16%), bird colonies (32%) and atmospheric deposition (20%) for elevated elements content. In the case of radionuclides, the natural occurring contamination (38%) was primary source followed by dumped material (32%) and bird colonies (30%). The radiological risk from radionuclides was relatively high, yet still under permissible levels. For potentially toxic elements, Fe was predominant non-carcinogenic pollutant and Ni emerged as major carcinogenic contaminant. Keeping in view the high content of some elements, future studies are required to keep the human and ecological risk low, and to establish scientific grounds for the contribution of settled bird species. The findings of the study advance the present knowledge about the contamination of the study area and lays the path for further effort.

Contamination Features and Quantitative Source Apportionment of Potentially Toxic Elements in the Urban Surface Soil, the Case of Hamedan, West of Iran

In this study, a total of 180 surface soil samples were collected from a control area and residential, commercial, and industrial regions of Hamedan, Iran during the fall season in 2023. Contents of analyzed elements were then determined using ICP-OES. The results illustrated that the average contents of As, Cd, Cu, Mn, Ni, and Pb were 1.17-2.26 times greater than those reported as local background values, while the mean contents of As, Cd, and Cu were respectively 3.41, 1.25, and 1.00 times greater than the background contents for Iran by implying the possible human sources of these PTEs. The cumulative average ecological risk value with 81.9, demonstrated moderate ecological risk across the study area. The results of source apportionment showed that the PTEs contamination in the soil of the study area mainly originates from the anthropogenic activities (65.6%) and traffic emissions as the primary pollution source (47.3%) had the highest contribution to the PTE pollution in the study area. In conclusion, by providing a useful approach to identifying the sources and contributions of toxic elements across different functional areas, this study has the potential to guide future efforts aimed at managing and mitigating the pollution caused by metal elements.

Physicochemical characterization and determination of trace metals in different edible fats and oils in Bangladesh: Nexus to human health

The study assessed the quality of four different edible fats and oils using standard analytical techniques. The presence of potentially toxic elements was determined using atomic absorption spectrometry. This study reveals that edible oils function admirably in terms of physical traits such as moisture content, boiling point, melting point, density, and specific gravity. Some edible fats and oils exceeded the standard limit of moisture, acid value, and peroxide value and these values were found in the range of 0.120-0.760 %, 0.220-2.45 mg KOH/g, and 1.23-21.7 meq/kg respectively. The iodine value for fats showed satisfactory results but for oils observed lower than the standard value varied from 68.2 to 104 g/100 g. The results of saponification value for most of the oils and fats were found satisfactory but others were lower than recommended limits and detected results were in the range of 167-224 mg KOH/g. Trace metals viz. Fe, Mn, Ni, Pb, Cd, Cu, and Co were measured in all samples and the concentration ranged from 0.070 to 47.0, 0.120-2.44, 0.540-27.1, 0.030-1.87, 0.010-4.63 and 0.060-8.39 ppm for iron, manganese, nickel, lead, copper, and cobalt respectively. The study found high levels of Fe, Mn, Ni, Cu, and Co in edible fats and oils in Bangladesh. No Cd was found, and Pb was not present in over half of the samples, which included the majority of mustard oils. The levels of Fe and Ni were higher than advised, but there was no discernible toxicological danger from Cd or Pb. The results of the health risk assessment indicated that there was no risk to children's health and possible hazards to adults' health.

Status of trace metals and arsenic in sediments and catfish muscles (Clarias gariepinus) from the Eastern Tanzanian basin

Trace metals and metalloids are groups of chemical elements that naturally occur in low concentrations and cycle in the environment driven by natural processes and human activities. They have a persistent and bio-accumulative tendency in the environment, and certain trace metals and metalloids have become a public health concern. This study assesses the concentration of eleven trace metals and a metalloid in sediments and catfish muscle from five study sites in the Eastern Tanzanian River basin. Forty catfish tissues and fifteen sediment samples were collected and analyzed using ICP-MS. Concentrations of As, Cd, Co, Pb, and Zn did not exceed the United States Environmental Protection Agency (USEPA) guideline for pollution of sediments, while Al Cr, Al, Mn, and V with values ranging from (118.54 to 70154.55) indicating moderately polluted. The stations Java-Sadaani and Matandu showed the highest Cr, Ni, and Cu concentrations, but the potential ecological risk index (RI) was low (RI < 95). In the catfish muscle tissue, the levels of Cd, Pb, Cu, and Zn did not surpass the EU and FAO/WHO limits and results ranged from 2.22 to 35.22mg/kg. Low levels of accumulation of Cd, Pb, and As were found in this study compared to catfish muscles from other studies, whereas the concentrations of other trace metals and metalloids analyzed had comparable results. Biota/sediment accumulation factors (BSAF) were all < 1. The weekly metal intake (MWI) results ranged from 6.89E-04 to 2.43E+01 μg/know-1week-1, indicating a low risk as the value did not exceed the FAO/WHO established Permissible Tolerable Weekly Intake (PTWI). The non-carcinogenic health risk result THQ was 4.43E-02 and the carcinogenic health risks result HI was 4.42E-05 which indicated tolerable levels of risks as both the values of the Target Hazard Quotient (THQ) and the Hazard Index (HI) was < 1, and the carcinogenic target risk (TR) is < 0.0001. The highest TR values were observed for Cr and Ni. We recommend a continued monitoring of the changes in trace metal levels in the environment and biota together with continuous public health education on the dangers of high levels of trace metals.

Pinus eldarica (L.) bark as urban atmospheric trace element pollution bioindicator: pollution status, spatial variations, and quantitative source apportionment based on positive matrix factorization receptor model

In this study, a total of 180 Pinus eldarica bark samples were collected from different regions of Hamedan megacity, Iran, in 2023, and contents of Cd, Cr, Cu, Mn, Ni, Pb, and Zn in the samples were determined using ICP-OES. The results illustrated that the average contents of all the analyzed elements were greater than those in the background contents, which presumably demonstrated anthropogenic sources of these potentially toxic elements (PTEs). The greatest concentrations of the analyzed PTEs for different functional areas were observed in specimens collected from commercial or industrial areas, indicating the impact of human entries. The I-geo values were in the range of "unpolluted to moderately polluted" to "moderately to heavily polluted", PI showed "moderate to very high pollution", and PLI reflected high to very high pollution levels for the whole study area. Additionally, the cumulative mean value of ecological risk (RI) was found to be 152, demonstrating moderate ecological risk across the study area. The results of positive matrix factorization (PMF) showed that the PTE contamination in the air of Hamedan could mainly have an anthropogenic origin (82.7%) and that the traffic emissions as the primary pollution source (33.6%) make the highest contribution to the PTE pollution and ecological risks in the study area. In residential areas, demolition and construction activities could be considered the main sources of PTEs, while in commercial and industrial areas traffic emissions and industrial emissions, could be regarded as the main sources of such pollution, respectively. In conclusion, this study provides a useful approach to identifying the sources and contributions of the toxic elements in different functional areas and can inform future endeavors that aim at managing and controlling metal element pollution.

Heavy metal impacts on antioxidants in cow blood from wastewater-irrigated areas

The aim of the present research was to investigate the presence of heavy metals such as lead (Pb), copper (Cu), chromium (Cr), and cadmium (Cd) in blood samples from cows raised with irrigated wastewater, as well as in the wastewater itself, in the North-western region of Pakistan. A total of 60 blood samples were collected from five different locations in Kohat, namely Tappi Road (TR), Pindi Road (PR), Gul Malik Road (GMR), Markaz Road (MR), and a control group. The samples of both i.e. cow blood and wastewater were analyzed for the concentrations of heavy metals. The highest concentration of Cd was detected in the MR site with a mean value of 0.03 mg/L, and the highest concentration of Cu (0.04 mg/L) was recorded in the TR site, while the lowest level was found in the control group with a mean of 0.002 mg/L in blood samples. The highest Cr and Pb concentrations were found at the PR site, with mean values of 0.03 and 0.07 mg/L, respectively, whereas the control group had the lowest concentrations, with mean values of 0.002 and 0.01 mg/L. Similarly, heavy metal concentrations were analyzed in wastewater used for irrigation in the study area. Results indicated elevated concentrations of Cu and Cr in wastewater, although they remained below the World Health Organization (WHO) recommended values except for Cr (0.13 mg/L) in the GMR site, which exceeded permissible limits. Cd and Pb concentrations in wastewater were relatively low, but Cd concentration surpassed WHO limits, particularly with a mean concentration of 0.08 mg/L in the TR site. Comparison between heavy metal concentrations in blood and wastewater revealed higher values of Cd and Pb in blood samples than in wastewater, while Cu and Cr concentrations were higher in water compared to blood. Additionally, elevated levels of Super Oxide Dismutase (SOD), antioxidant enzyme Catalase (CAT), and oxidative stress marker malondialdehyde (MDA) were detected in blood samples. Cluster and principal component analyses were employed to assess heavy metal toxicity among the groups, indicating potential long-term adverse health effects on animals, transfer to humans, and toxicity in living organisms.

Assessment of potentially toxic elements (PTEs) in atmospheric dry deposition of Hamedan Metropolis, west of Iran: pollution status, spatiotemporal variation, health risk implications, and source identification

The present study was designed to assess concentrations, contamination levels, spatiotemporal variations, health hazards and source apportionment of potentially toxic elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and V) of atmospheric dry deposition (ADD) in Hamedan Metropolis. In so doing, a total of 144 atmospheric dry deposition samples were collected from 12 sites during four seasons in 2023. The concentrations of the analyzed PTEs in dry deposition samples were determined using ICP-OES after samples were digested with acid. The results illustrated that the average contents of As, Cd, Cr, Cu, Ni, Pb, and Zn with 4.52, 0.591, 4.01, 36.5, 42.5, 10.9, 84.6, 69.6, 178, and 3.91 mg/kg, respectively, were higher than those in the background samples reported for Iran, which could indicate the anthropogenic origin of these PTEs. The highest quantities of the tested PTEs in various seasons were observed in summer and/or fall samples and their highest amount in various functional regions pertained to the samples collected from the commercial or industrial regions, showing the effect of seasonal changes on emission sources and human inputs. Values of average contamination factor (CF), geo-accumulation index (I-geo), and enrichment factor (EF) ranged from 0.013 to 4.45, - 7.07 to 1.56, and 0.120 to 41.3, respectively, showing 'slight to high' pollution, 'unpolluted to moderately polluted', and 'no enrichment to very severe enrichment' levels, respectively. The pollution load index (PLI) with an average value of 0.680 reflected slight pollution levels in the entire study area. The average hazard index (HI) values of the tested PTEs for the residents were all within the safe limit (< 1). Additionally, the total carcinogenic risk (TCR) values showed that the carcinogenic risk of As, Cr and Ni for both target groups were at an acceptable level. Based on the positive matrix factorization (PMF) model, non-exhaust emissions and natural sources, fossil fuel combustion and industrial emissions, and traffic sources were identified as the primary contributors to ADD pollution, accounting for 26%, 38%, and 36%, of the total pollution respectively. In conclusion, further research is recommended to investigate the source-oriented ecological and health risks associated with atmospheric dry deposition pollution.

Appraisal of metallic accumulation in the surface sediment of a fish breeding dam in Türkiye: A stochastical approach to ecotoxicological risk assessment

This study examines the levels and patterns of potentially toxic elements (PTEs) in surface sediment of Almus Dam Lake (ADL), a key fish breeding site in Türkiye. PTE concentrations in sediment were ranked: Hg (0.05 ± 0.01) < Cd (0.16 ± 0.01) < Pb (9.34 ± 1.42) < As (18.75 ± 15.65) < Cu (63.30 ± 15.17) < Ni (72.64 ± 20.54) < Zn (86.66 ± 11.95) < Cr (108.35 ± 36.40) < Mn (1008 ± 151) < Fe (53,998 ± 6468), with no significant seasonal or spatial differences. Ecological risk indices (mHQ, EF, Igeo, CF, PLI, Eri, mCd, NPI, PERI, MPI, and TRI) showed low contamination levels. Health risk assessments, including LCR, HQ, and THI, indicated minimal risks to humans from sediment PTEs. Statistical analyses (PCA, HCA, SCC) identified natural, transportation, and anthropogenic PTE sources, with slight impacts from agriculture and fish farming. This research underlines contamination status of ADL and emphasizes the need for targeted management strategies, offering critical insights for environmental safeguarding.

Potentially toxic elements (PTEs) and ecological risk at waste disposal sites: An analysis of sanitary landfills

This study presents an analysis of soil contamination caused by Ni, Zn, Cd, Cu, and Pb at municipal solid waste (MSW) landfills, with a focus on ecological risk assessment. The approach aims to assess how different landfill practices and environmental conditions affect soil contamination with potentially toxic elements (PTEs) and associated environmental risks. Soil samples were collected from MSW landfills in Poland and the Czech Republic. The research included a comprehensive assessment of PTEs in soils in the context of global environmental regulations. The degree of soil contamination by PTEs was assessed using indices: Geoaccumulation Index (Igeo), Single Pollution Index (Pi), Nemerow Pollution Index (PN), and Load Capacity of a Pollutant (PLI). The ecological risk was determined using the Risk of PTEs (ERi) and Sum of Individual Potential Risk Factors (ERI). The maximum values of the indicators observed for the Radiowo landfill were as follows: Igeo = 4.04 for Cd, Pi = 24.80 for Cd, PN = 18.22 for Cd, PLI = 2.66, ERi = 744 for Cd, ERI = 771.80. The maximum values of the indicators observed for the Zdounky landfill were as follows: Igeo = 1.04 for Cu, Pi = 3.10 for Cu, PN = 2.52 for Cu, PLI = 0.27, ERi = 25 for Cd, ERI = 41.86. The soils of the tested landfills were considered to be non-saline, with electrical conductivity (EC) values less than 2,000 μS/cm. Varying levels of PTEs were observed, and geostatistical analysis highlighted hotspots indicating pollution sources. Elevated concentrations of Cd in the soil indicated potential ecological risks. Concentrations of Cu and lead Pb were well below the thresholds set by the environmental legislation in several countries. In addition, Ni concentrations in the soils of both landfills indicated that the average levels were within acceptable limits. Principal Component Analysis (PCA) revealed common sources of PTEs. The identification of specific risk points at the Radiowo and Zdounky sites contributes to a better understanding of potential hazards in landfill environments. By establishing buffer zones and implementing regular maintenance programs, emerging environmental problems can be addressed in a timely manner.

Distribution, ecological, and health risk assessment of trace elements in the surface seawater along the littoral of Tangier Bay (Southwestern Mediterranean Sea)

In the current study, an environmental assessment of surface seawater in Tangier Bay was conducted by analyzing physicochemical parameters and trace elements, such as As, Cr, Zn, Cd, Pb, and Cu. The results showed mean concentrations (μg/l) of 22.50 for As, 0.46 for Cr, 8.57 for Zn, 15.41 for Cd, 0.23 for Pb, and 1.83 for Cu. While most trace elements met the guidelines, elevated levels of Cd raised concerns about long-term exposure. Pollution indices, including the contamination factor, degree of contamination, and water quality index, indicate the impact of human activities, dividing sites into arsenic-cadmium contamination, wastewater influence, and low pollution levels. Statistical methods, such as ANOVA, revealed no significant differences in trace element levels across the bay. PCA and HCA revealed that Cr, Cu, and Zn originated from common anthropogenic sources, whereas Pb and Cd originated from distinct sources. As indicates that natural geological processes influence its origin.

Risk assessment of four toxic heavy metals in terrestrial and aquatic ecosystems around BSCIC tannery industrial estate of Savar, Dhaka, Bangladesh

The shifting of tannery industries from Hazaribagh to Savar adjacent to Dhaleshwari River might have inevitable adverse impacts, especially the heavy metal contamination of both terrestrial and aquatic ecosystems. The study was carried out to investigate the concentrations of four heavy metals in the soil, water, and plant samples collected from around Dhaleshwari River adjacent to the Bangladesh Small & Cottage Industries Corporation Tannery Industrial Estate, Dhaka. This study revealed that average concentrations of cadmium and chromium in soil exceeded the maximum permissible limit of World Health Organization (1996) and average concentrations of lead, cadmium, and chromium in water exceeded the maximum permissible limit of World Health Organization (2011) and Environmental Conservation Rules (1997). The average concentrations of lead, cadmium, and chromium in the roots and shoots of both Eichhornia crassipes and Cynodon dactylon exceeded the maximum permissible limit of Food and Agriculture Organization/ World Health Organization (2016). Ecological risk assessment using indices model for soil pollution indicated that soil is mostly contaminated with cadmium and chromium which can pose strong ecological risk Health risk assessment using indices model for water pollution revealed the high degree of contamination and unacceptable non-carcinogenic risk and carcinogenic risk for adults as well as children through ingestion of water. Average bioconcentration factor and bioaccumulation factor were higher in Eichhornia crassipes than Cynodon dactylon for lead, cadmium, and chromium. Average translocation factor was also higher in Eichhornia crassipes for all the metals except cadmium. It is suggested remedial and mitigation measures be instituted to control environmental degradation of the newly established Tannery Industrial Estate.

Evaluation of potentially toxic elements and microplastics in the water treatment facility

The potentially harmful effects of consuming potentially toxic elements (PTEs) and microplastics (MPs) regularly via drinking water are a significant cause for worry. This study investigated PTEs (Cd, Cu, Cr, Ni, Pd, Zn, Co), MPs, turbidity, pH, conductivity, and health risk assessment in the water treatment plant in Kielce, Poland. Zn had the highest concentrations throughout the water treatment facility, whereas Cd, Pb, and Co had lower concentrations (< 0.1 µg/L). The order of the concentrations among the specified PTEs was like Zn˃Cu˃Ni˃Cr˃Cd˃Pb and Co. The minimum turbidity was 0.34, and the maximum was 1.9 NTU. The range of pH in water samples was 6.51-7.47. The conductivity was 1,203-1,445 ms in water samples. These identified MPs were categorized into fiber and fragments. The color of these identified MPs was blue, red, black, green, and transparent. The minimum and maximum size of the MPs was 196 and 4,018 µm, while the average size was 2,751 ± 1,905 µm. The average concentration of MPs per liter of the water treatment plant was 108.88 ± 55.61. The elements listed are C, O, Na, Mg, Al, Si, K, Ca, and Ti. Fe and Zn were the predominant elements seen using EDX. HQ values of the PTEs were less than one for adults and children. The human health risk associated with all detected PTEs revealed that the HQ values exhibit a satisfactory degree of non-carcinogenic adverse health risk. HI values for adults and children age groups were less than one. In most water treatment samples, the carcinogenic value exceeds the threshold value of 10-6. The PTEs and MP concentrations in drinking water should be periodically monitored to minimize consumers' environmental pollution and health risks.

Assessment of bioremediation potential of Calotropis procera and Nerium oleander for sustainable management of vehicular released metals in roadside soils

Land transportation is a major source of heavy metal contamination along the roadside, posing significant risks to human health through inhalation, oral ingestion, and dermal contact. Therefore, this study has been designed to determine the concentrations of vehicular released heavy metals (Cd, Pb, Ni, and Cu) in roadside soil and leaves of two commonly growing native plant species (Calotropis procera and Nerium oleander).Two busy roads i.e., Lahore-Okara road (N-5) and Okara-Faisalabad roads (OFR) in Punjab, Pakistan, were selected for the study. The data were collected from five sites along each road during four seasons. Control samples were collected ~ 50 m away from road. The metal content i.e. lead (Pb), cadmium (Cd) nickel (Ni) and copper (Cu) were determined in the plant leaves and soil by using Atomic Absorption Spectrophotometer (AAS). Significantly high amount of all studied heavy metals were observed in soil and plant leaves along both roads in contrast to control ones. The mean concentration of metals in soil ranged as Cd (2.20-6.83 mg/kg), Pb (4.53-15.29 mg/kg), Ni (29.78-101.26 mg/kg), and Cu (61.68-138.46 mg/kg) and in plant leaves Cd (0.093-0.53 mg/kg), Pb (4.31-16.34 mg/kg), Ni (4.13-16.34 mg/kg) and Cu (2.98-32.74 mg/kg). Among roads, higher metal contamination was noted along N-5 road. Significant temporal variations were also noted in metal contamination along both roads. The order of metal contamination in soil and plant leaves in different seasons was summer > autumn > spring > winter. Furthermore, the metal accumulation potential of Calotropis procera was higher than that of Nerium oleander. Therefore, for sustainable management of metal contamination, the plantation of Calotropis procera is recommended along roadsides.

Potential Toxic Metal Concentration and Risk Assessment in Agricultural Soil and Lentil Crop (Lens culinaris Medik) in Dawunt Woreda, Northwest Wollo, Ethiopia

Health implications for the population due to consuming contaminated crops have been a great concern worldwide. This study aimed to measure the levels of potential toxic elements in lentils and their growing soil in Dawunt Woreda, Ethiopia. Accordingly, 15 soil samples along with the lentil samples were collected to measure the level of potential toxic elements, including chromium (Cr), manganese (Mn), iron (Fe), lead (Pb), cadmium (Cd), copper (Cu), and cobalt (Co), by using an inductively coupled plasma optical emission spectrometer and for assessing the potential ecological and human health risk. The wet digestion method using aqua regia (HCl/HNO3 3 : 1) was employed for soil and lentil sample preparation. The mean concentrations of Fe, Mn, Co, Cu, Cd, Pb, and Cr in the lentil sample were 60.4, 9.68, 0.75, 5.7, 0.25, 0.9, and 1.15 mg/kg, respectively. In soil, the mean concentrations of Fe, Mn, Co, Cu, Cd, Pb, and Cr were 649, 19.9, 3.32, 40.0, 15.2, 1.83, and 69.1 mg/kg, respectively. All of the potential toxic metals in agricultural soil and lentil samples were found to be below the reference level set by the World Health Organization, except Cd, in the soil samples. Five single metal and three cumulative pollution index parameters were employed for the data and results showed that Fe, Cu, and Cr moderately pollute the soil and are highly contaminated by Cd. The cumulative pollution indices also confirmed that the extent of soil pollution varied from highly contaminated to moderate contamination. The possible health risks at various exposure routes have also been estimated. The single-metal and cumulative-metals health risks (cancer and noncancer) of adults and children due to chronic exposure to soil and consumption of lentils were estimated using the health quotient and health index values as per the United States Environmental Protection Agency guidelines. Thus, the results revealed no significant adverse health risks (cancer and noncancer) for adults and children. Therefore, the inhabitants in the study area have no significant health impacts due to either the consumption of lentil crops or exposure to agricultural soil particles.

Pollution indices of selected metals in tea (Camellia sinensis L.) growing soils of the Upper Assam region divulge a non-trifling menace of National Highway

The study investigated the influence of a National Highway (NH) traversing tea estates (TEs) on heavy metal (HM) contamination in the top soils of Upper Assam, India. The dispersion and accumulation of six HMs, viz. cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn), within tea-growing soils were assessed using diverse indices: contamination factor (CF), degree of contamination (DC), enrichment factor (EF), geo-accumulation index (Igeo), modified degree of contamination (MDC), Nemerow pollution index (PINemerow), pollution load index (PLI), potential ecological risk factor (Eri), and potential ecological risk index (RI). The order of HM prevalence was Fe > Mn > Zn > Ni > Cu > Cd. Elevated Cd levels near the NH prompted immediate attention, while Cd and Zn showed moderate pollution in CF, EF, and RI. The remaining metals posed minimal individual risk (Eri< 40), resulting in an overall contamination range of "nil to shallow," signifying slight contamination from the studied metals. From MDC values for investigated metals, it was found to be "zero to very low degree of contamination" at all locations except the vicinity of NH. Soil pollution, as determined by PLI, indicated unpolluted soils in both districts, yet PINemerow values indicated slight pollution. The statistical analysis revealed that there is a significant decrease in most of the indices of HM as the distance from NH increases. The application of multivariate statistical techniques namely Principal Component Analysis and Cluster Analysis showed the presence of three distinct homogenous groups of distances based on different indices. This investigation underscores NH-associated anthropogenic effects on TE soil quality due to HM deposition, warranting proactive mitigation measures.

Assessment of potentially hazardous elements in soils of the Boyacá industrial corridor (Colombia) using GIS, multivariate statistical analysis, and geochemical indexes

In the industrial corridor of Boyacá, Colombia, population growth is accompanied by anthropogenic activities such as industrial operations, vehicle exhaust fumes, mining, smelting, atmospheric deposition, and excessive use of chemical products to promote crop growth. These activities are known to have a significant impact on urban and rural soils, contributing significantly to elevated concentrations of potentially hazardous elements in the environment. This industrial corridor is an area of economic and social development that needs to provide reference information that will allow us to know the state of soil quality to preserve and manage the public and geoenvironmental health of this region. Anthropogenic activities have contributed to the accumulation of potentially hazardous elements in the environment, affecting various levels of life and creating risks with economic and social implications. However, igneous activity or detrital deposition also enriches soils and creates geochemical anomalies in specific locations. In these cases, the identification of potentially hazardous elements involves the determination of likely sources of contamination and their relationship to the geological setting. In this study, the concentrations of As, Cd, Pb, Mn, Fe, Zn, Hg, Cu and Ni were determined in eighty-one soil samples from the Boyacá industrial corridor (Colombia). The sequential trend of the concentrations of potentially hazardous elements was as follows: Fe > Mn > Zn > Ni > Cu> Pb > As > Cd > Hg. Furthermore, the application of spatial analysis criteria in GIS software with multivariate statistical tools and geochemical indices allowed the identification of anthropogenic and geogenic sources. Most of the potentially hazardous elements were found in soils exposed to industrial and agricultural activities, except for iron. This element showed low variability in all samples, regardless of the geological formations. Due to the lack of reference values for potentially hazardous elements in Colombia, the concentrations were compared with the environmental standards of the Environmental Protection Agency (EPA) and the Ecuadorian Ministry of Environment, Water and Ecological Transition (MAE). The results demonstrate the complexity of the soil and represent the first exploratory study of potentially hazardous elements in this industrial corridor. These results are the starting point for the establishment of geochemical background lines in Colombia and for inspection policies for areas where productive activities converge.

Neuropathological profile of the African Giant Rat brain (Cricetomys gambianus) after natural exposure to heavy metal environmental pollution in the Nigerian Niger Delta

Pollution by heavy metals is a threat to public health because of the adverse effects on multiple organ systems including the brain. Here, we used the African giant rat (AGR) as a novel sentinel host to assess the effect of heavy metal accumulation and consequential neuropathology upon the brain. For this study, AGR were collected from distinct geographical regions of Nigeria: the rain forest region of south-west Nigeria (Ibadan), the central north of Nigeria (Abuja), and in oil-polluted areas of south Nigeria (Port-Harcourt). We found that zinc, copper, and iron were the major heavy metals that accumulated in the brain and serum of sentinel AGR, with the level of iron highest in animals from Port-Harcourt and least in animals from Abuja. Brain pathology, determined by immunohistochemistry markers of inflammation and oxidative stress, was most severe in animals from Port Harcourt followed by those from Abuja and those from Ibadan were the least affected. The brain pathologies were characterized by elevated brain advanced oxidation protein product (AOPP) levels, neuronal depletion in the prefrontal cortex, severe reactive astrogliosis in the hippocampus and cerebellar white matter, demyelination in the subcortical white matter and cerebellar white matter, and tauopathies. Selective vulnerabilities of different brain regions to heavy metal pollution in the AGR collected from the different regions of the country were evident. In conclusion, we propose that neuropathologies associated with redox dyshomeostasis because of environmental pollution may be localized and contextual, even in a heavily polluted environment. This novel study also highlights African giant rats as suitable epidemiological sentinels for use in ecotoxicological studies.

Metals stress on soil enzyme activities and herbs defense in the vicinity of high traffic roadways

This study has investigated the impact of vehicle sourced heavy metals (HMs) on soil enzyme activities and plants in and around high traffic roadways near the metropolitan area. In detail, the defense response against HM pollution was studied by considering the commonly available herbs around the roadside area namely Alternanthera paronychioides, Ageratum conyzoides, Spilanthes acmella, and Parthenium hysterophorus. The study reported that the HM concentrations such as Cu, Ni, Zn, Mn, and Cr were observed in the range of 6.05 ± 0.1 to 309 ± 0.5 mg/kg in roadside soil and 5.2 ± 0.1to 451 ± 4.2 mg/kg in the herbs collected from roadside area. The soil enzyme (urease, dehydrogenase, amylase, catalase, peroxidase, and polyphenol oxidase) activities decreased by 22.56 to 77.84% in roadside soil and lower IC50 values were observed for DPPH (2.32-4.67) and H2O2 (1.59-2.15) free radical scavenging activities in plants collected from roadside area. The flavonoid and phenolic content in plants collected from the roadside area ranges from 12.65 ± 0.2 to 15.75 ± 0.3 mg quercitin/g and 0.61 ± 0.04 to 1.16 ± 0.1 mg gallic acid/g respectively while in plant collected from the control areas ranges from 7.96 ± 0.1 to 11.24 ± 0.05 and 0.47 ± 0.01 to 0.61 ± 0.1. In addition, the contamination factor (CF) (1.53-11.92) and geo-accumulation index (Igeo) (0.031-2.99) in soil and bioaccumulation factor (BAF) (0.72-2.73) of Cu, Ni, Zn, Mn, and Crin plants indicated that the soil and plants growing along the highway were heavily contaminated with HM. Finally, Pearson correlation matrix confirmed the inhibition effect of HM on soil enzymatic activities and enzymatic defense of plants in response to the HM stress.

Sediment-connected Potentially Toxic Element Contamination and Phytoremediation Potential of Native Aquatic Macrophytes along the Jajrood River, Tehran Province, Iran

This study was conducted to analyze Cu, Fe, and Pb contamination in sediments and also phytoremediation ability of bulrush (Typha Latifolia) and one-rowed water-cress (Nasturtium microphyllum) along the Jajrood River, Iran in 2022. In so doing, a total of 60 sediment and macrophyte samples were collected from four sites. The contents of the analyzed elements were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Also, the values of pollution index (PI), pollution load index (PLI), bioconcentration factor (BCF), bioaccumulation factor (BAF), transfer factor (TF) and metal accumulation index (MAI) were calculated. The results demonstrated that the average contents of Cu, Fe, and Pb were lower than those in the background, which presumably demonstrated natural sources of these metals. The greatest concentrations of analyzed elements for all the sediment and macrophyte samples were observed in specimens collected from S4 located at the end of the river, indicating the impact of anthropogenic entries from upstream areas on elemental accumulation in downstream section of the river. The values of PI reflected slight contamination. The higher BCF and lower translocation TF values of Fe and Pb in T. Latifolia and also Cu in N. microphyllum imply that these species could be suitable for their phytostabilization of above-mentioned elements from the sediment. This study provides evidenceas to the efficiency of T. Latifolia and N. microphyllum in bioremediation of Cu, Fe, and Pb in contaminated aquatic environments.

Ecological risk assessment of metal pollutants in two agriculturally impacted estuaries

A focused diagnosis of ecosystem health in two South African estuaries (Kromme and Gamtoos) was conducted. Four pollution indices were used, i.e., geoaccumulation (Igeo), ecological risk (RI), contamination factor (CF) and pollution load index (PLI), to assess toxicity levels of metal contaminants in relation to background values. The Igeo results (11.1 %) can be classified as contaminated, with Cd, the only element with high values in both estuaries. Likely sources (herbicides, pesticides) of Cd are used in the agricultural dominated catchments. There was a high concentration of Mn (13.4 ± 2.51 and 12.3 ± 1.13 μg·g-1) and Fe (1289 ± 243 and 1291 ± 130 μg·g-1) at site 4 for Gamtoos and Kromme estuary respectively compared to the other metal elements. Although results indicate low metal contamination, with increasing global anthropogenic pressure, continuous monitoring should be prioritised to assist in managing estuarine systems that support a wide range of socio-economic and ecosystem services.

Feasibility Study on Phytoremediation of Potentially Toxic Elements (Cd, Ni and Pb) in Aquatic Environments Using Suaeda maritima Plant Species, a Case Study: Khorkhoran International Wetland, Persian Gulf

The current study was designed to assess the phytoremediation potential of Suaeda maritima has been assessed for cleanup of contaminated sediments with Cd, Ni and Pb. In so doing, totally, 20 sampling sites were selected in the Khorkhoran International Wetland. The contents of elements in sediments, plant organs and water samples were determined using ICP-OES. The mean contents of Cd, Ni and Pb (mg/kg) in the sediment samples were found to be 0.096, 38.1 and 1.78, respectively. Moreover, the mean levels of Cd, Ni and Pb (mg/kg) in root samples of S. maritime were 0.160, 2.72 and 1.22 respectively; whereas, in leaf samples they were found to be 0.157, 3.34 and 2.23 mg/kg, respectively. Furthermore, the mean contents of Cd, Ni and Pb (µg/L) in water samples were 243, 1440 and 3010, respectively. The values of BCF for Cd, BAF for Cd and Pb, and TF for Ni and Pb were higher than 1, which would indicate that S. maritima could possibly be a suitable candidate for the phytostabilization of Cd and the phytoextraction of Ni and Pb.

Monitoring the spatial distribution pattern according to urban land use and health risk assessment on potential toxic metal contamination via street dust in Ankara, Türkiye

The urbanization processes with growing vehicle numbers cause heavy metal pollution in street dust, and high populations in metropolitan cities are exposed to pollutants. This paper aims to monitor the spatial distribution of heavy metals and evaluate the concentrations via health risk assessment of HMs (Cu, Ni, Cd, Co, Pb, and Zn) that expose the inhabitants to health hazards. According to the results of the current study, sixty street dust samples were applied to the acid digestion technique and quantification by inductively coupled plasma-mass spectrometry (ICP-MS). The spatial distribution of the selected heavy metals in the street dust was investigated using the spatial analysis tool in ArcGIS 10.0 according to population density and land use. In the present study, we used hazard index and cancer risk methods to estimate the public health risk of the pollutants exposed to street dust in Ankara. The concentrations range of the elements in street dust over the study area ranged from 3.34-4.50, 31.69-42.87, 16.09-21.54, 42.85-57.55, 0.00-3.51, and 23.03-30.79, respectively. The overall decreasing order of mean concentration of metals was observed as follows: Pb > Cu > Ni > Co > Cd > Zn. Vehicle traffic and industrial activities seem to be the most critical anthropogenic sources responsible for dust pollution in the study area. The risk assessment of Pb and Ni exposure was the highest, and the hazard index values were 2.42E + 00 and 2.28E + 00 mg/kg/day for children. However, the effect on adults was 2.62E-01 and 2.37E-02 mg/kg/day, followed by inhalation and dermal contact with street dust was almost negligible. The decreasing concentration is modeled spatially along the western development corridor of the city. The risk to public health is high in areas with high densities close to the city center and the main artery.

Environmental impacts of air pollution and its abatement by plant species: A comprehensive review

Air pollution is one of the major global environmental issues urgently needed attention for its control through sustainable approaches. The release of air pollutants from various anthropogenic and natural processes imposes serious threats to the environment and human health. The green belt development using air pollution-tolerant plant species has become popular approach for air pollution remediation. Plants' biochemical and physiological attributes, especially relative water content, pH, ascorbic acid, and total chlorophyll content, are taken into account for assessing air pollution tolerance index (APTI). In contrast, anticipated performance index (API) is assessed based on socio-economic characteristics including "canopy structure, type, habit, laminar structure, economic value and APTI score" of plant species. Based on previous work, plants with high dust-capturing capacity are identified in Ficus benghalensis L. (0.95 to 7.58 mg/cm2), and highest overall PM accumulation capacity was observed in Ulmus pumila L. (PM10 = 72 µg/cm2 and PM2.5 = 70 µg/cm2) in the study from different regions. According to APTI, the plant species such as M. indica (11 to 29), Alstonia scholaris (L.) R. Br. (6 to 24), and F. benghalensis (17 to 26) have been widely reported as high air pollution-tolerant species and good to best performer in terms of API at different study sites. Statistically, previous studies show that ascorbic acid (R2 = 0.90) has good correlation with APTI among all the parameters. The plant species with high pollution tolerance capacity can be recommended for future plantation and green belt development.

Enrichment, sources, and distributions of toxic elements in the farming land's topsoil near a heavily industrialized area of central Bangladesh, and associated risks assessment

Toxic element accumulation in the surrounding soils of the advanced industry- and agriculture-oriented areas may lead to severe environmental degradation and harmful impact on inhabitants. This work examined the concentration of some concerned toxic elements (Cr, Pb, Cd, Cu, As, and Ni) in the representative topsoil from 10 industrially contaminated sites in central Bangladesh (Narayanganj district) using an Inductively Coupled Plasma Mass Spectrometer concerning the probable ecological and human health risks. The mean concentrations (mg/kg) of the elements were found in the order of Ni (58.1 ± 11.8) > Pb (34.1 ± 14.3) > Cr (32.1 ± 6.77) > Cu (14.5 ± 3.30) > Cd (2.74 ± 1.08) > As (1.49 ± 0.43). The findings pointed out that diversified manmade events enhanced the intensities of elemental contamination through the studied sites. Source analysis showed that Cr, Pb, As, and Cd may originate from industrial wastewater and agricultural activities, whereas Cu and Ni came from natural sources. The geo-accumulation index level for Cd (1.70-3.39) was determined as grade 3 (moderately to strongly polluted), the enrichment factor score for Cd (13.9) fell in the very severe enhanced category (cluster 5), and the highest contamination factor value was found for Cd (15.7). The contamination degree values for all the tested elements signify a moderate to severe contamination grade; conversely, pollution load index levels depicted the nonexistence of elemental pollution. The assessment revealed serious Cd pollution in agricultural soils and moderate to significant potential ecological risk for the rest of the examined toxic elements. Furthermore, hazard index values exceeded the safe exposure levels, indicating that there was potential non-carcinogenic risk in the soils for children and adults. Ingestion exposure had much higher carcinogenic risk values than inhalation and cutaneous exposure, and children are exposed to considerable carcinogenic hazards. Therefore, it is suggested that the harmful practices that expose this farming soil to contaminants should be stopped immediately and effective environment-friendly techniques of waste management and effluent treatment should be employed in the study area.

Effect of salinity on the potential cadmium phytoremediation from the polluted soil by carpobrotus rossii

Nowadays, toxic metals accumulation in soil texture due to anthropogenic activities is a major form of pollution, which can lead to worldwide concerns; however, there are many treatment methods to remove them from soil such as phytoremediation. The carpobrotus rossii, has shown great potential to tolerate high salinity and accumulate Cd from contaminated soils. The experiments, in this study, are analyzed and optimized by Central Composite Design (CCD) as method and using Response Surface Methodology (RSM) package in R software. The Cd removal by root and the whole plant followed the quadratic model and the R² values were 94.95 and 94.81, respectively. The results showed that a decrease in NaCl concentration in Cd-containing solution can increase the phytoremediation process of Cd by carpobrotus rossii, significantly. The optimum conditions for 58% Cd removal by the whole plant, predicted through a CCD response surface methodology model were as follows: initial Cd concentration of 49 mgKg^-1,NaCl concentration of 16 dSm^-1, time of 17 days, and pH of 6.5. C. rossii's potential in removing 58% of Cd under the obtained optimum condition from the modelling was evaluated in real condition in the laboratory. The results revealed that around 56% of the initial added Cd concentration was removed by carpobrotus rossii. As a take home message, carpobrotus rossii can be recommended as an efficient plant to remove heavy metals especially cadmium from soil and sediments in arid area which have a salty soil.

Spatial distribution characteristics, influencing factors, and source distribution of soil cadmium in Shantou City, Guangdong Province

A total of 511 topsoils and 139 deep soil samples were collected to analyze the distribution characteristics, regional differentiation factors, and contamination sources of Cd in Shantou City, and to assess its environmental, ecological, and human health risks. We used a combination of multivariate statistics and geostatistics to quantify the distribution and level of Cd contamination in the study area, and an absolute principal component scores-multiple linear regression model to resolve the sources of contamination and their contribution values, combined with the health risk model to assess the human health risk from each source. The result exhibited that the average value of soil Cd content was 0.100 mg/kg, which was lower than the threshold value of soil environmental quality standard, but higher than the 0.070 mg/kg background value of soil. The high-value areas of surface Cd content in the study area were distributed in the western, northern, and northeastern parts of Shantou, and the source of Cd in the soil was a mix of anthropogenic and natural contamination. The non-carcinogenic and carcinogenic risks of heavy metal Cd exposure pathways are: oral ingestion > dermal contact > inhalation. The human health risk posed by Cd is below the reference threshold, indicating that the Cd contents in the soil have no unacceptable health risk to the residents. Among industrial sources, natural sources, and unknown sources with potential carcinogenic and non-carcinogenic risks, natural sources were the main source of contamination for adults and children. Among the different soil types, paddy, and red soils had relatively high Cd content, and among the different soil-forming parent materials, the Cd content in soils developed on Quaternary sediments was significantly higher than that other parent materials. Among the different land use types, the Cd content of soil for construction land was the highest. This study provides a scientific foundation and reference for the prevention of soil Cd contamination in Shantou City and the analysis of soil contamination sources in areas with similar contamination patterns.

The Design of Experiment as a Tool to Model Plant Trace-Metal Bioindication Abilities

Bioindicator plants are species that have the capacity to linearly uptake some elements (metal and metalloids) from the growing substrate, thus reflecting their concentration in the soil. Many factors can influence the uptake of these elements by plants, among which is the simultaneous presence of several metals, a common situation in contaminated or natural soils. A novel approach that can be used to validate the bioindication ability of a species growing on a polymetallic substrate is the design of experiment (DoE) approach. The aim of the present study was to apply the DoE in full factorial mode to model the Cu, Cd, Pb, Zn, and Cr bioindication capacity of Polygonum aviculare, used as the model plant. The results showed that P. aviculare has the ability to bioindicate Cd and Cr with a linear uptake (from 0.35 to 6.66, and 0.1 to 3.4 mg kg-1, respectively) unaffected by the presence of other metals. Conversely, the uptake of Pb, Cu, and Zn is strongly influenced by the presence of all the studied metals, making their concentration in the plant shoot not proportional to that of the soil. In conclusion, these preliminary results confirmed that the DoE can be used to predict the bioindicator abilities of a plant for several elements at the same time and to evaluate the interactions that can be established between variables in the growing medium and in the plant itself. However, more studies including other plant species are needed to confirm the effectiveness of this method.

Heavy metal phytoremediation potential of the roadside forage Chloris barbata Sw. (swollen windmill grass) and the risk assessment of the forage-cattle-human food system

This study presents the assessment of the risks incidental to the growth of the common tropical grass species Chloris barbata Sw. (swollen windmill grass) on road margins contaminated with Pb and Cd. Pot experiments were first carried out to quantify the Pb and Cd accumulation potential of the plant species in various plant parts as a function of the metal concentration in soil. C. barbata was found to be a hyperaccumulator for Cd (BCF>1, for aerial parts) and an excluder of Pb (BCF<1, for aerial parts). As the plant was found to accumulate Pb in its roots with TF<1, it can be considered a phytostabilizer of Pb. The mathematical relationship developed between soil concentrations of Pb and Cd and their corresponding concentrations in aerial parts were used in combination with the concentrations of these heavy metals reported in roadside soils to obtain estimates of their accumulation in the forage and consequently in the animal organs. Risk to the consumers of offal was estimated. It was found that the consumption of kidney meat was riskier than the consumption of liver meat. Furthermore, it was seen that despite the nearly two order less concentrations of Cd in roadside soils compared to Pb, it was posing a higher risk. For the median concentrations of Pb reported in roadside soils and cattle feeding exclusively on C. barbata growing on roadside soils, the HQ exceeded 1 for weekly consumption of kidney meat above 650 g. For median Cd concentrations, consumption of kidney meat above 230 g/week resulted in HQ>1. The scenario considered for risk assessment is significant for India, where stray grazing of cattle on road margins is common and offal offers a cheap source of animal protein for the economically poor.

Spatial distribution of heavy metal contamination and uncertainty-based human health risk in the aquatic environment using multivariate statistical method

Heavy metal contamination in the aquatic environment is one of the most serious health issues worldwide. In this study, an evaluation framework is developed to identify the sources and health risk of heavy metals (i.e., As, Hg, Cr, Cu, Zn, Pb, and Cd) contamination in the North Canal of Fengtai District, China, which is based on multiple approaches, including multivariate statistical method, health risk assessment, and uncertainty analysis. Spatial distribution of these heavy metals could exhibit their impact on the aquatic environment. Pearson's correlation analysis shows that a majority of the correlations between different heavy metals are not significant due to the differences in sources of heavy metals. Principal component analysis indicates that there are four principal components to explain 91.381% of the total variance. Moreover, health risk reveals that hazard quotient values are in low levels, ranging from 0.48 to 0.74, relative higher quotient levels could be observed in the northern section. The carcinogenic risk of Cd has exceeded the acceptable level in S1, S3, and S7. Sensitivity analysis ensures the reliability of health risk assessments. Furthermore, some specific recommendations are given to help decision-makers develop more comprehensive strategies for improving water environment quality.

Quantifying the influencing factors and multi-factor interactions affecting cadmium accumulation in limestone-derived agricultural soil using random forest (RF) approach

Cadmium (Cd) is a highly toxic heavy metal that occurs widely in the environment and poses extensive threats to human health, animals, and plants. This study aims to identify and apportion multi-source and multi-phase Cd pollution from natural and anthropogenic inputs using ensemble models that include random forest (RF) in agricultural soils on Karst areas. The contributions of natural and anthropogenic factors to Cd accumulation were quantitatively assessed using the RF machine learning method. The results revealed that the main influencing factors were pH, organic carbon (C_org), and elevation. Moreover, the interaction effects of pH and C_org on distance and elevation were also quantified and visualised. It is observed that pH and C_org had stronger effects on soil Cd concentration than that of distance when pH > 7.02 and C_org > 1.53. In other words, higher Cd content in the soil along roadways may be caused by the interaction of distance, pH and C_org, with pH and C_org playing the dominant role in our case. Moreover, the maximum contribution of a single factor, elevation, to Cd concentration was about 0.13 mg/kg, and its interactions reached 1.082 mg/kg and 0.83 mg/kg, respectively, when combined with pH and C_org at 194.0 m. However, with increasing elevation, pH and C_org gradually took over the leading roles. This result not only gives us a quantitative understanding of the relationship between the factors that affect soil cadmium accumulation, but also provides an accurate method for source apportionment of heavy metals in soil.

Concentrations of selected trace elements in surface soils near crossroads in the city of Bratislava (the Slovak Republic)

It is well known that road transport emits various trace elements into the environment, which are deposited in soils in the vicinity of roads, so-called roadside soils, and thus contributes to the deterioration of their chemical state. The aim of this work was to determine concentrations of some metals and metalloids (arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V), and zinc (Zn)) in soils from crossroads with traffic signals, which are characterized by deceleration of vehicles and increased emissions of elements related mainly to brake and tyre wear. The results confirmed a moderate enrichment of soils with Cu, Pb, and Zn (enrichment factor (EF) values > 2) and significant enrichment for Sb (EF > 5), while the other elements showed no or minimal enrichment. The age of crossroads proved to have a positive influence on the accumulation of some elements in soils with the largest differences for Cu, Fe, Pb, Sb, and Zn (p < 0.001). Traffic volumes expressed as the average daily traffic intensity (ADTI) also positively influenced soil concentrations of Cr, Cu, Pb, Sb, and Zn, while distance to the crossroad had a significant negative effect on the soil concentration of Cu, Sb, and Zn (p < 0.001). The stable isotopic ratios of Pb, ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb, ranging from 1.1414 to 1.2046 and from 2.0375 to 2.1246, respectively, pointed to the mixed natural-anthropic origin of Pb in the soils of crossroads with a visible contribution of traffic-related sources. Based on the above findings combined with covariance among the studied elements using statistical methods applied to compositionally transformed data, it was possible to show that Cu, Pb, Sb, and Zn clearly originated from road traffic.