Assessing heavy metal toxicity in sediments of Chennai Coast of Tamil Nadu using Energy Dispersive X-Ray Fluorescence Spectroscopy (EDXRF) with statistical approach

Heavy metal concentrations and pollution indicators in the Ennore ecosystem, east coast of Tamilnadu, India using atomic absorption spectrometry study with statistical approach

The study of the heavy metals in the Ennore ecosystem plays a vital role in determining the extent of pollution in the area. Heavy metals such as Mg, Al, Si, K, Ca, Ti, Fe, V, Cr, Mn, Co Ni, Cu, Zn, As, Cd, Ba, La, and Pb were determined in twenty-six samples. The heavy metal concentration in the sediments was found to decrease in the sequence of Si > Al > Fe > Ca > Ti > K > Mg > Mn > Ba > V > Cr > Zn > La > Ni > Pb > Co > As > Cd > Cu in the study area, its varies as follows: 540-49,434, 3597-56,502, 22.37-691, 11.5-198.29, 69.10-1227.61, 1.40-19.95 and 11.48-38.63 for Ti, Fe, V, Cr, Mn, Co and Ni respectively. The average heavy metal concentrations were below the world's crustal average. The level of sediment pollution attributed to heavy metals was evaluated using several pollution indicators such as the enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), and pollution load index (PLI). The analysis, that revealed the average values of the enrichment factor indicates anthropogenic sources of Pb, Cr, As, Cd, Ni, V, Mn, and Zn. The average contamination factor (Cf) of metal Cd is slightly higher in some study areas (C2, B6, C10, B2, and S7). The results of the geoaccumulation index (Igeo) and pollution load index (PLI) indicate that the most of study area is not contaminated by heavy metals. The results of multivariate data analysis techniques, including Pearson correlation analysis, principal components, and clusters analysis, indicate that heavy metals in the sediments are of natural origin. This shows a general absence of serious pollution in the study area.

Artificial water regulation and natural flood processes control heavy metal concentrations and transport in the Yellow River, China

Based on heavy metals daily observation at the Lijin station during water-sediment regulation (WSR) event and three natural floods in 2020, we examined the effects of different flood events on heavy metal in lower Yellow River, China. The results revealed that due to different water and sediment sources and processes influencing heavy metals dynamics, the dissolved Cr, Zn As and particulate heavy metals during natural flood events were higher than those during WSR event. Dissolved heavy metals increased during water regulation and decreased during sediment regulation. Using positive matrix factorization (PMF) model, we found that sources of dissolved heavy metals during WSR event were mainly from agricultural practices, rock and soil weathering, and industrial pollution. During flood events, particulate heavy metals' concentrations varied due to dilution, human activities, and reservoir influences, with industrial and agricultural sources significantly impacting Cu, Zn, As, and Pb levels.

Assessing the impact of heavy metals on bacterial diversity in coastal regions of Southeastern India

Globally, there is growing concern over the environmental contamination of coastal ecosystems caused by anthropogenic activities. Here,we performed a study to evaluate the degree of heavy metal contamination in 5 different sediment samples collected from five sites along the Southeastern coast of India. Additionally, the research aims to explore the potential ecological implications of heavy metal contamination on the bacterial diversity, a crucial factor in upholding a sustainable ecosystem. A total of  seven heavy metals, i.e., chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As), were assessed and quantified using inductively coupled plasma mass spectrometry. Targeted amplicon sequencing revealed that phylum Proteobacteria (36.9%) was the most dominating followed by Halobacterota (25.5%), Actinobacteriota (15%), Firmicutes (6.7%), Bacteroidota (4.0%), Thermoplasmatota (2.3%), Acidobacteriota (2.0%), Chloroflexi (1.6%), Planctomycetota (1.2%) and Crenarchaeota (1.1%). According to the alpha diversity estimate, lesser bacterial diversity was observed in areas with high pollution levels. Moreover, the physicochemical parameters of the sediments were analyzed. The contamination levels of the sediments were evaluated using the geo-accumulation index (Igeo), contamination factor (CF) and pollution loading index (PLI) to ascertain the comprehensive toxicity status of the sediments. The Igeo values revealed sediment pollution with metals such as Hg and Cd. The sediments obtained from the sampling site PU-01 showed the highest concentration of Hg pollution. Considering the ecotoxicological aspect, the estimated risk index (RI) values indicated a range from low to significant ecological risk.

Evaluation of radioactive and heavy metal pollution in agricultural soil surrounding the lignite-fired thermal power plant using pollution indices

Soil pollution caused by heavy metals negatively affects the environment and human health. However, the assessment of the environmental and ecological risks caused by heavy metals in agricultural soils in developing countries is limited. This study was carried out to determine heavy metal pollution and its possible sources in the agricultural lands surrounding the lignite-fired Afşin-Elbistan thermal power plant (TPP). A total of 52 soil samples were collected from the agricultural soils surrounding the TPP, and seven different heavy metal (U, Th, Ni, Fe, Cu, Cr and Zn) analyzes were performed on these samples. Soil samples were taken according to the prevailing wind direction. Nickel had a higher geoaccumulation index (1.40) and enrichment factor (5.09) values than the other metals. In addition, U posed a "moderate potential ecological risk" in the study area. Pearson correlation and principal component analyses showed that U, Ni, and Cr were controlled by anthropogenic sources.

Ecological and contamination assessment of soil in the region of coal-fired thermal power plant

This study was carried out to determine the heavy metal pollution and possible sources of agricultural soils in Tavşanlı district, Which energy power plant is located. Total 83 soil samples were taken and 8 (Cu, Cr, Pb, Co, Fe, Mn, Ni, and Zn) heavy metals were analyzed in soil samples The mean concentration of heavy metals were determined as Cu (32.89 mg kg-1), Cr (285.69 mg kg-1), Co (36.37 mg kg-1), Mn (860.20 mg kg-1), Ni (457.59 mg kg-1), Pb (22.14 mg kg-1), Fe (30,250 mg kg-1) and Zn (65.05 mg kg-1), were determined. The mean concentrations of Cu, Cr Co, Mn and Ni found to be higher than both the upper continental crust values and the European soil mean values. Contamination factor Co (2.1), Cr (3.10) and Ni (9.73), enrichment factor Co (2.73), Cr (3.75) and Ni (11.42) and geoaccumulation index Co (0.18), Cr (0.50) and Ni (1.98) values showed that the soils were polluted by Co, Cr, and Ni. In addition, it was determined that Ni (48.65) poses a "moderate ecological risk" in the study area. Pearson correlation anaysis and principal component analysis determined that Cr, Co and Ni have both lithogenic and anthropogenic origin.

Otolith microchemistry of freshwater indigenous minor carp (Bangana dero) as a biomonitoring tool to trace heavy metals in River Sutlej, Ropar Wetland (Ramsar site), Punjab, India

The elemental composition of the fish otolith may represent a permanent record of the environmental condition the fish inhabited. Fish otolith grows incrementally from the core to a marginal region that acts as a repository of trace metal signatures. The present study explores the potential application of otolith microchemistry of the benthopelagic indigenous minor carp Bangana dero sampled from the Ropar wetland on River Sutlej, Punjab. The concentration of sixteen metals was evaluated in the otolith (n = 42) and water (n = 48) for the post-monsoon and pre-monsoon season from 2020 to 2022 using inductively coupled plasma mass spectrometry (ICP-MS) followed by element detection in the core and marginal region of whole otolith, using energy-dispersive mass spectroscopy (EDS). All the heavy metals exhibited an increase in metal concentrations in fish otolith than water during the post-monsoon season. By indices approach, the otolith was found to have a high bioaccumulation factor for Se in the post-monsoon and Hg in the pre-monsoon. Certain trace metals like As and Hg exhibited fluctuations in their core and marginal region. Thus, trace metal patterns in the otolith could act as a potential tool for monitoring the seasonal changes of metals in water bodies. The EFHg, EFSe and EFAs in the fish otolith predicted its anthropogenic source, while the remaining studied elements showed ambient water origin. Thus, using the otoliths of Bangana dero as a long-term monitoring tool in the future may be helpful for environmental assessments and the reconstruction of historical exposure for safeguarding of water bodies.

The importance of using soil series-based geochemical background values when calculating the enrichment factor in agricultural areas

The enrichment factor (EF) is one of the most commonly used indices for determining the source of air, water and soil pollution. However, concerns have been raised about the accuracy of the EF results because the formula leaves the choice of background value to the researcher's discretion. The EF was used in this study to assess the validity of such concerns and to determine heavy metal enrichment in five soil profiles with different parent materials (alluvial, colluvial, and quartzite). Moreover, the upper continental crust (UCC) and specific local background values (sub-horizons) were used as the geochemical backgrounds. When UCC values were applied, the soils were moderately enriched in Cr (2.59), Zn (3.54), Pb (4.50) and Ni (4.69), and significantly enriched in Cu (5.09), Cd (6.54) and As (6.64). Using the sub-horizons of the soil profiles as a background value, it was found that the soils had "moderate enrichment" by As (2.59) and "minimally enrichment" by Cu (0.86), Ni (1.01), Cd (1.11), Zn (1.23), Cr (1.30), and Pb (1.50). As a result, the UCC reported an inaccurate conclusion indicating that soils were 3.84 times more heavily polluted than they were. In addition, the statistical analyses performed in this study (Pearson correlation analysis and principal component analysis) revealed that the percentage of clay in the soil horizons and the cation exchange capacity had strong positive relationships (r ≥ 0.670, p < 0.05) with certain heavy metals (Al, Zn, Cr, Ni, Pb and Cd). These findings indicated that sampling from the "lowest horizons" or "parent materials" of the soil series would yield the most accurate results in determining the geochemical background values in agricultural areas.

Recent advances in instrumental techniques for heavy metal quantification

Heavy metals (HMs) are ubiquitous; they are found in soil, water, air, and all biological matrices. The toxicity, bioaccumulation potential, and deleterious effects of most of these metals on humans and the environment have been widely documented. Consequently, the detection and quantification of HMs in various environmental samples have become a pressing issue. The analysis of the concentrations of HMs is a vital component of environmental monitoring; hence, the selection of the most suitable analytical technique for their determination has become a topic of great interest in food, environment, and human health safety. Analytical techniques for the quantification of these metals have evolved. Presently, a broad range of HM analytical techniques are available with each having its outstanding merits as well as limitations. Most analytical scientists, therefore, adopt complementation of more than one method, with the choice influenced by the specific metal of interest, desired limits of detection and quantification, nature of the interference, level of sensitivity, and precision among others. Sequel to the above, this work comprehensively reviews the most recent advances in instrumental techniques for the determination of HMs. It gives a general overview of the concept of HMs, their sources, and why their accurate quantification is pertinent. It highlights various conventional and more advanced techniques for HM determination, and as one of its kind, it also gives special attention to the specific merits and demerits of the analytical techniques. Finally, it presents the most recent studies in this regard.

Microplastic pollution and its implicated risks in the estuarine environment of Tamil Nadu, India

Estuaries are transition zones between freshwater and seawater. There are only few studies on microplastic (MPs) pollution in estuaries. In this study, investigating the spatiotemporal variations of MPs in water, sediment and biota samples of 19 estuaries in Tamil Nadu, India, we assessed the chemical and human exposure risks of MPs. MPs extracted by digestion and density separation and characterized them using microscope, Fourier transform infrared spectroscopy and scanning electron microscopy with energy dispersive analysis of X-rays. MP abundancesin summer and monsoon range from 31.7 ± 3.8 to 154.7 ± 4.2 items/L in water and 51.7 ± 3.6 to 171.4 ± 9.1 items/kg in sediment. Highest MPs abundance is found in water and sediment of the urbanized Adayar estuary. MP levels are higher in monsoon than in summer (P < 0.05) due to the discharge of wastewater via storm water outlets. More small-size MPs are found in summer (<0.5-1 mm) while monsoon has a greater diversity of MP polymers (MPDII: 0.81). MP abundance in fish varies from 0.01 ± 0.003 to 0.15 ± 0.03 items/g, and in shellfish from 0.75 ± 0.12 to 9.7 ± 0.28 items/g. In fish, more MPs are found in intestine than in gill or muscle. Shell fishes contain more MPs than fishes. In all the matrices, fibers of different sizes, and polymers of polyethylene and polypropylene are commonly found. An average local person is likely to ingest 781 items of MPs via fish and 2809 items via shellfish annually. Polymer hazard index shows hazard levels of IV to V indicating the serious MP pollution trend, which poses a risk to the biota. In conclusion, MPs observed in this study show that estuaries are a major pathway for land-derived plastics to reach the ocean. The results will help implement remedial/clean-up measures for the estuary for better ecosystem conservation.

Heavy metal contamination along different tidal zones of a tropical Bay of Bengal coastal environment influenced by various anthropogenic activities

The spatiotemporal variations of five heavy metals (Cd, Cu, Cr, Pb, and Zn) in the beach sediments along the Tamil Nadu coast sourced from various anthropogenic activities were assessed using atomic absorption spectrophotometry (AAS). Various pollution monitoring indices were computed to clearly understand the metal pollution status along the Tamil Nadu coastline. The metal concentrations in sediments were typically higher in the summer season than in the monsoon season. In the monsoon season, metal concentration followed a decreasing order of Zn > Cr > Cu > Pb > Cd, and in the summer season, the order was Cr > Zn > Cu > Pb > Cd. During the monsoon season, freshwater runoff from the rainfall dilutes the sediments and their trace element load. However, due to a lack of freshwater influx during the summer season, the heavy metals in the sediments get concentrated and showed elevated levels. Geo-accumulation index, ecological risk index, pollution load index, and contamination degree clearly depict that Cd and Pb have higher accumulation and pose greater hazard when compared with other metals. The rivers flowing in the region also transport the heavy metals from the mainland to the estuaries and coastal environments. Metal levels along the Tamil Nadu coast are influenced by various anthropogenic activities persistent along the coastline. Some of the activities that cause metal contamination are mining, milling, electroplating, furnishing, pharmaceutical industries, fishing, harbor activities, urban runoff, and agricultural runoff, which release a variety of toxic metals into the coastal environment.

Soil contamination and healthy risk assessment of peach orchards soil of Bilecik Province Turkey

The soil is the part of the biosphere where heavy metal pollution is most common. Heavy metals pose a threat to animal and human health through plants. This study aimed to evaluate heavy metal concentrations in the soil of orchards of Bilecik Province and possible human health risks. In 2016, 42 soil samples were taken from peach orchards of Bilecik Province, and Cr, Fe, Ni, Cu, Zn, Cd, and Pb analyzed. Pollution indices (Enrichment Factor, Geoaccumalation Index, Contamination Factor, Ecological Risk Factor) were used to determine heavy metal pollution, and the effects on human health were determined by the hazard quotient (HQ) and hazard index (HI). The study area is moderate contaminated by Cd (3.64), Ni (2.38) and Cu (2.24) in terms of enrichment factor. Similarly, the study area soils were moderately contaminated by Cd (1.72), Ni (1.40) and Cu (1.38) in terms of the contamination factor. Besides, soils had moderate potential ecological risk by Cd (51.54). The principal component and correlation analysis showed Cd and Cu are anthropogenic and Ni is the lithogenic origin. Although soil pollution indexes show moderate pollution, there is no non-carcinogenic health risk for children (0.56) and adults (0.061).

Seasonal variation, polymer hazard risk and controlling factors of microplastics in beach sediments along the southeast coast of India

Microplastics (MPs) and its associated organic and inorganic contaminants are one among the significant health hazards to almost all biota, including human. We investigated the polymer hazard risk and its adsorbed contaminants in MPs at six prominent beaches of Chennai on the southeast coast of India. The spatial variation of MPs during the northeast (NE) monsoon (range: 76-720 items/kg, mean: 247.4 items/kg) was higher than that during southwest (SW) monsoon (range: 84-498 items/kg, mean: 302.7 items/kg). In both the seasons, polyethylene (PE) and polypropylene (PP) were the dominant polymers and fibre was the predominant shape of MPs, likely to be derived from fishing, textile and urban activities in this region. Scanning electron microscope (SEM) images exhibited various surface weathering features including grooves, cracks, fractures, adhering particles, pits, vermiculate textures and fibre reinforcements. Energy dispersive X-ray spectrometer (EDS) results showed that MPs have adsorbed major (Si, Al, Na, Mg, Ca, Fe and Ti) and trace (Cu, Cr, Ni, Pb and Zn) metals. Though pollution load index (PLI) presented low degree of MP contamination in the beach sediments, hazardous polymers such as polyvinyl chloride (PVC), polyamide (PA) and polystyrene (PS) contributed to high polymer hazard index (PHI) and potential ecological risk index (PERI), posing very high risk to the biota. The trajectories obtained from particle-tracking coupled with hydrodynamic simulation clearly showed that 20% of MPs settled along the coast and the remaining moved towards north, alongshore and offshore (∼50 km) within 30 days, and in NE monsoon due to current reversal, the floating debris and MPs have drifted towards south, ∼40 km in 30 days, indicating the role of circulation in the fate and transport pathways of plastic debris.

Potentially toxic elements in weathered waste-rocks of Fushun western opencast mine: distribution, source identification, and contamination assessment

To understand the current status of the contamination of potentially toxic elements (PTEs) after closing the Fushun Western Opencast Mine, this study has focused on the concentration, contamination assessment, and source identification of eight PTEs in weathered waste-rocks in four distinct areas of the mine. The mean concentrations of Ni, Cr, Zn, Cu, Pb, Hg, Cd, and As were 79.4, 86.3, 126, 64.8, 16.9, 1.04, 1.94, and 6.27 mg kg^-1, respectively. The results demonstrated that Ni, Cr, Zn, Cu, Pb, Hg, Cd, and As were contaminated to different extents in different weathered waste-rocks and waste-rocks, among which there was considerable Cd contamination. Coal gangue area (CGA) exhibited the most polluted weathered waste-rocks, which can be attributed to severe pollution and moderate ecological hazards. Self-combustion gangue (SCG) contamination of waste-rocks was considerably serious and caused severe pollution and considerable ecological harm. Health risk assessments demonstrated that Hg had the highest non-carcinogenic risk. Ingestion of PTEs was found to be a primary route of exposure, while dermal and inhalation exposure was negligible. Principal component analysis (PCA) demonstrated that there were roughly three sources of PTEs in the weathered waste-rocks of the mine, natural sources related to the weathering of parent rocks, and human sources, including industrial emissions, mining activities, and atmospheric dust deposition and resuspension. This study advances our knowledge of PTEs in mines and provides policymakers with a reference for designing strategies to protect mine-based ecosystems.

Soil contamination assessment and potential sources of heavy metals of alpu plain Eskişehir Turkey

Soil is the basic component of the biosphere and is exposed to many contaminants, including heavy metals, which are mainly affected by natural and human activities. Heavy metals in the soil are included in the food chain and pose a risk to human health. Determination of concentration and potential sources of heavy metals and evaluation of environmental and ecological risks were aimed at this study. In this study, 79 soil samples were collected from Alpu plain, located in Middle Anatolian to determine concentrations of Cadmium (Cd), Chromium (Cr), Copper (Cu), Cobalt (Co), Manganese (Mn), Nickel (Ni), Lead (Pb), and Zinc (Zn). As a result, Enrichment Factor (EF) and Geoaccumalation Index (I_geo), average values of Ni and Cd showed moderate enrichment and pollution. Similarly, Cd was found as the considerably potential ecological risk. Principal component and Pearson correlation analysis proved that while Pb, Cr, Cu, Zn, Ni, Co, and Mn are primarily from natural sources, Cd is mainly from anthropogenic activities.

Distribution and ecological risk assessment of heavy metals using geochemical normalization factors in the aquatic sediments

Thamirabharani river acquires a noticeable quantity of sewage and agriculture waste from local inhabitants. The distribution of heavy metals in the surface sediments of the Thamirabharani river was analyzed using Inductively Coupled Plasma- Mass Spectrometry (ICP-MS) to study the ecological risks. The heavy metal concentrations in the sediments ranged from 0.098 ± 0.03(Cd) to 159.181 ± 13.36 mg kg-1 (Fe). The Cd, Zn, Ni, Fe, and Mn concentrations in the sediments were above the US Environmental Protection Agency-Sediment Quality Guidelines. The fact that Cd, Co, and Cu concentrations at sites 4 and 5 exceeded the background values (BGVs) of 0.2, 13, and 32 mg kg-1 suggests anthropogenic activity, notably in the downstream of the river. The sediment contaminated with Cd is more evident, particularly in the estuarine region. The potential ecological risk index (150 Collapse

Key Words

• Degree of contamination
• Ecological risk co-efficient
• Enrichment factor
• Heavy metal pollution
• Pollution load index
• Sediment quality

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MESH Headings

• Ecosystem
• Environmental Monitoring
• Geologic Sediments
• Metals, Heavy/analysis
• Risk Assessment
• Water Pollutants, Chemical/analysis

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Affiliation(s)

Ulaganathan Arisekar Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India.
Robinson Jeya Shakila Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India.
Rajendren Shalini Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India
Geevartnam Jeyasekaran Tamil Nadu Fisheries University Nagapattinam, 611 002, Tamil Nadu, India
Muruganantham Keerthana Department of Fisheries and Fishermen Welfare, Thoothukudi, 628 008, Tamil Nadu, India
Natarajan Arumugam Department of Chemistry, College of Science, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia
Abdulrahman I Almansour Department of Chemistry, College of Science, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia
Karthikeyan Perumal Department of Chemistry and Biochemistry, The Ohio State University, 151 W. Woodruff Ave, Columbus, OH, 43210, USA

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Distribution of heavy metals in surface soil near a coal power production unit: potential risk to ecology and human health

Coal thermal power plants are the dominant factor in producing various hazardous elements in surrounding surface soil, resulting in a significant human health hazard. In the current study, the seasonal (pre- and post-monsoon) concentration of As, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, and Zn in surface soil around coal power production unit was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The possible health risks throughout multiple exposure routes, i.e., ingestion, dermal, and inhalation were estimated for adult and children. Furthermore, geo-accumulation index (Igeo), enrichment factor (EF), pollution factor (CF), ecological risk index, and pollution load index (PLI) were applied to interpret the environmental pollution in the study area. The geospatial distribution pattern was computed to understand the trace and hazardous element distribution in the surface soil. As a result, the concentration of Fe (mg/kg) in pre-monsoon (15,620) and post-monsoon (27,180), Ni (mg/kg) in pre-monsoon (19.8), and post-monsoon (81.7) was found above the standard limits of soil prescribed by the WHO and FAO. Enrichment factor was observed between 0.95-6948 (pre-monsoon) and 0.53-116.09 (post-monsoon). The ecological risk index was found moderate to considerable for As and Cd metals during both seasons. In addition, the average PLI value was observed high for both seasons indicating the contamination of the study area with heavy metals. Moreover, Igeo values for Fe, Mg, and As were found relatively high. Conversely, health risks to the human population were found within the USEPA acceptable limits.

Evaluation of ecological risk, source, and spatial distribution of some heavy metals in marine sediments in the Middle and Eastern Black Sea region, Turkey

In the present study, the concentration levels of heavy metals such as Mn, Fe, Ni, Cu, Zn, Cr, and Pb in sediment samples collected from 16 sampling locations in the Middle and Eastern Black Sea regions, Turkey, were measured using energy dispersive X-ray fluorescence spectroscopy (EDXRF). Various pollution parameters and methods, such as the enrichment factor (EF), geo-accumulation index (I_geo), contamination factor (CF), pollution load index (PLI), ecological risk index (RI), and geo-spatial distribution patterns, were used to assess the pollution status, ecological risks, and sources of metals in sediment in detail. The mean concentrations of Mn, Fe, Ni, Cu, Zn, Cr, and Pb were found to be 565.38, 46,000, 34.38, 104.06, 109.88, 87.31, and 32.31 mg/kg, respectively. Results showed that the mean concentrations of Cu, Zn, and Pb exceeded the crustal shale value, with the exception of Mn, Fe, Ni, and Cr. According to the calculated pollution parameters, although minimal or moderate pollution was detected in the area investigated, it was determined that there was a very low ecological risk. Multivariate statistical analysis results showed that Cu, Zn, and Pb levels in the investigated region were slightly influenced by anthropogenic inputs such as mining and agricultural practices. In addition, the geo-spatial distributions of Cu, Zn, Fe, and Pb were found to be higher in this region due to the mining activities carried out in the Eastern Black Sea region.

Microplastics as contaminants in Indian environment: a review

The increased production and consumption scale of plastic items has led to the generation of microplastics (MPs), an emerging class of contaminants, in our environment. MPs are plastic particles less than 5 mm in size and could originate due to primary and secondary sources. The primary ones are generated as such in the MP size range while the secondary MPs are a result of fragmentation of larger plastic particles which eventually enters the aquatic, terrestrial and atmospheric environments. The increasing concern of MP pollution in every compartment of our environment is being globally explored, with relatively fewer studies in India. Among the total studies published on MP prevalence in the Indian environments, marine systems have received significantly higher attention compared to the other compartments like freshwater, atmosphere, terrestrial and human consumables. This review article is an effort to present current understanding of MP pollution in aquatic systems, terrestrial systems, atmosphere and human consumables of India by reviewing available scientific literature. Along with this, the review also focuses on identification of the gap areas in current knowledge and highlights way forward for future research. This would further help in meeting the goals of this emergent pollutant management.

Pollution, human health risk assessment and spatial distribution of toxic metals in urban soil of Yazd City, Iran

Heavy metal pollution significantly reduces the quality of the environment and threatens human health, especially in industrial cities. This study investigated toxic metals concentrations, pollution levels and human health risks assessment of urban soils in Yazd City, as an industrial city in center of Iran. Soil surface samples (0-10 cm) were collected from 30 points in the area for geochemical analysis. The concentrations of heavy metals were determined using an inductively coupled plasma mass spectrometry (ICP-MS). The values of the mean concentrations of toxic metals (mg kg^-1) in the urban soils decrease in the order of Zn (83.9) > Pb (34.5) > Cr (32.6) > Cu (23.5) > Ni (23.4) > As (5.86) > Co (4.86) > Cd (0.27). The mean concentration of Zn, Pb, As and Cd elements was higher than the background and the crust values. A pollution assessment by Geo-accumulation Index (I_geo), Pollution Index (PI), Contamination Degree (C_D), the Integrated Pollution Index (IPI), the Pollution Load Index (PLI) and Integrated Nemerow Pollution Index (INPI) showed that As, Cd and Pb were moderately enriched and the study area polluted considerably by these toxic metals. Based on PI results, 88.9% of the urban soil samples highly polluted by As. Overall, the quality of the urban soil in Yazd City is clearly affected by toxic metals. Due to the prevailing wind direction, the route of the north-south highway of Iran and the population density and traffic of the northwestern and southern areas of the study area were found the highest level of pollution indicators (IPI > 1.8; LPI > 1.3; C_D > 15 and INPI > 4.3). The results of Pearson correlation analysis indicated that all pollution evaluation indicators were influenced by As and Cu, and showed high significant correlation with these two elements, while neither of them had a significant relationship with Pb and was found also a weak link statistically with Cd. Health risk assessment of toxic metals has been performed in both carcinogenic and non-carcinogenic sectors. The results indicate that oral intake is the main pathway that toxic metals can harm human health for both the child and adults. The carcinogenic risks (RI) of adults and child by toxic metals were as follows: Ni > Pb > Cr > As > Cd. Hazard quotients (HQ) and hazard index (HI) values for child also were higher than these for adults. Generally, the results demonstrated that the potential carcinogenic health risks for adults of toxic metals were in an acceptable range in study area, whereas for Cr, Ni and Pb with RI > 10^-4, the risk of cancer in child probably increases.

Carbon dots-magnetic nanocomposites for the detection and removal of Hg2

The dual functional detection and removal of heavy ion metals by carbon dots has become an urgent matter of concern. Here, a unique fluorescent carbon dot-magnetic nanocomposite (Fe₃O₄/CDs) was prepared by hydrothermal methods for sensitive detection of Hg²⁺. The Fe₃O₄/CDs serve as fluorescent probes with higher selectivity and sensitivity for Hg²⁺, with the lowest detectable limit of 0.3 nM. Hg²⁺ statically quenched the blue emission of Fe₃O₄/CDs, which can be restored in the presence of saturated EDTA solution. The utilization of Fe₃O₄/CDs was fulfilled by recovering their emission conveniently. The recovery of Hg²⁺ in Chagan Lake water, tap water and drinks was calculated at 96.5 ~ 108.8%, which demonstrates the feasibility of the Fe₃O₄/CDs sensing system in natural samples. Notably, the Fe₃O₄/CDs can drive the effective removal of Hg²⁺ from samples, which is of outstanding significance as a promising probe in environmental monitoring.

Environmentally benign synthesis of fluorescent carbon nanodots using waste PET bottles: highly selective and sensitive detection of Pb2+ ions in aqueous medium

Green fluorescent carbon nanodots (size ∼6 nm) as a turn-off fluorescent optical nano-sensor for selective and sensitive detection of Pb²⁺ ions from aqueous medium.

Distribution and ecological- and health-risk assessment of heavy metals in the seawater of the southeast coast of India

The objective of the present study was to conduct an ecological and health risk assessment of heavy metals in the seawater of the southeast coast of India. The distribution profile of heavy metals in the surface seawater was Fe (79.60 ± 21.57 μg/L) > Zn (9.31 ± 1.33 μg/L) > Cu (5.19 ± 2.00 μg/L) > Ni (2.45 ± 0.76 μg/L) > Mn (1.20 ± 1.00 μg/L) > U (0.44 ± 0.23 μg/L) > Pb (0.36 ± 0.06 μg/L) > Cr (0.31 ± 0.57 μg/L) > Cd (0.11 ± 0.05 μg/L) > Co (0.07 ± 0.20 μg/L). Cu level for most of the samples exceeded the USEPA criteria for acute CMC (criterion maximum concentration) and chronic CCC (criterion continuous concentration). Other studied metals, Cd, Cr, Pb, and Ni, remained below the acute CMC and chronic CCC guidelines. The seawater pollution index (I_wp) of Cr, Ni, Zn, Cd, and Pb complied with the category-I seawater (<1, unpolluted). The ERI values (0.46-3.99) of the seawater of the studied coast mostly fell under the ecologically low risk category with respect to heavy metals. Dermal Hazard index values were orders of magnitude lower than one, indicating no potential health concern due to dermal exposure.

Heavy-Metal Pollution Characteristics and Influencing Factors in Agricultural Soils: Evidence from Shuozhou City, Shanxi Province, China

Although soil quality can be highly altered by mining activities, there are few reports on soil pollution in mining cities. We systematically characterized the heavy metals (HMs) pollution, risks, sources, and influencing factors in the surrounding soils of Shuozhou. Specifically, 146 samples were collected, and the potential ecological risk index (RI) and the single-factor index were jointly used to understand the environmental risk of HMs. Meanwhile, correlation analysis was applied to find the influencing factors of HMs. The results of the soil pollution risk assessment in the entire area of Shuozhou were compared with those in the open-pit mine area. (1) The mean concentrations of Cr, As, Cd, Pb, and Hg in our study were found to be higher than the background value. The RI results indicated that most soil samples (82.88%) in Shuozhou had a low potential ecological risk. Compared with the Pingshuo open-pit mine (average RI value: 200.07), the potential ecological RI was lower. (2) The HM correlation indicated that Cr and As were associated with the parent rock, whereas Cd, together with Hg and Pb, were associated with anthropic activities. (3) There was no significant correlation between HM concentrations and farmland slope. Located in the Datong Basin, the terrain of Shuozhou is relatively flat and open and has little impact on the distribution of HMs. (4) Only Hg and Pb have a negative correlation with pH. This suggests that soil with a lower pH value may be beneficial to the accumulation of Hg and Pb in soil. (5) Among the eight industry types examined, the pollution capacity level of the leather, fur, feather, and footwear industries is the strongest, indicating that HMs around LI industry sites represent the maximum level among the eight types.

A case study on pollution and a human health risk assessment of heavy metals in agricultural soils around Sinop province, Turkey

In the present study, the concentration levels of heavy metals such as Cr, Fe, Ni, Cu, Zn, As and Pb in soil samples collected from 88 sampling locations around Sinop Province, Turkey were measured using energy dispersive X-ray fluorescence spectroscopy (EDXRF). To interpret and to evaluate the pollution status and distribution of heavy metals in soil, metal pollution parameters such as enrichment factor (EF), geo-accumulation index (I_geo), pollution factor (CF) and pollution load index (PLI) and geo-spatial distribution patterns were used. The mean concentrations of Cr, Fe, Ni, Cu, Zn, As, and Pb were found to be 194.73, 39,848.57, 85.02, 43.19, 65.10, 5.66, and 17.01 mg/kg, respectively. Results indicated that the mean concentrations of Cr, Ni, As, and Pb exceeded the world crustal average, with the exception of Fe, Cu, and As. Multivariate analysis results showed that Cr, Ni, Zn, As, and Pb levels in the investigated region were highly influenced by anthropogenic inputs such as agricultural practices. According to the health risk assessment model introduced by USEPA to evaluate the human health risks, the non-carcinogenic risk for children was above the threshold level, but low for adults. Total potential carcinogenic health risks for both children and adults in the study area were in acceptable range. Overall, when health risks are evaluated, it shows that children are more susceptible to non-carcinogenic and carcinogenic health effects of trace metals compared to adults.

Trace metals in core sediments from a deep lake in eastern Turkey: Vertical concentration profiles, eco-environmental risks and possible sources

The contents of 12 trace metals (Hg, As, Pb, Cd, Ni, Cr, Zn, Cu, Co, Mn, Al and Fe) in two sediment cores (Hz11-P02 and Hz11-P09) from the Lake Hazar, one of the deepest natural lakes in Turkey, were examined to evaluate vertical concentration profiles, possible sources, pollution status and eco-environmental risks of these metals. The highest concentrations of Cd and As were detected in the upper part (0-10 cm depths) of core Hz11-P02, while Hg concentration was at a maximum in the upper part of core Hz11-P09. The concentrations of other metals except Cr were the highest in the bottom layer (depths below 100 cm) of both cores. Among trace metals (TMs), Cr, Ni, Al and Mn in core Hz11-P02 and Mn in core Hz11-P09 showed statistically significant correlations with core depth (p < 0.01). The mean concentrations of Hg, Pb, Cd, Cu, Zn, Co, Mn, Al and Fe in core Hz11-P02 were significantly higher than those in core Hz11-P09 (p < 0.01). Also, the mean enrichment factor, geoaccumulation index and contamination factor values of As, Cu, Cd, Zn, Pb and Hg were higher in core Hz11-P02. The ecological risk index (RI) values for core Hz11-P02 were between 150 and 300 in 40.3% of the samples, indicating "moderate ecological risk", whereas the RI values for core Hz11-P09 were <150 in 100% of the samples, indicating "low ecological risk". Factor, cluster and correlation analyses, and contamination indices indicated that As and Hg in core Hz11-P02 predominantly originated from anthropogenic sources, while 12 trace metals in core Hz11-P09 derived from natural sources.

Silver and copper as pollution tracers in Neogene to Holocene estuarine sediments from southwestern Spain

Estuaries are very sensitive ecosystems to human activities and the natural evolution of their drainage basins located upstream. Pollution derived from human activities, such as historical mining or recent industrial wastes, can significantly affect their environmental quality. This paper analyzes the silver and copper contents of four cores extracted in two estuaries of SW Spain. Its chronology and vertical evolution allow to differentiate the effects of several pollution episodes (natural, Roman, 19th-20th centuries) on its different sedimentary environments in the last 6 million years. Possible future applications are included in the fields of environmental management or even education.

Elemental concentration based potential ecological risk (PER) status of the surface sediments, Pulicat lagoon, Southeast coast of India

Eighty-three surface sediments were collected to investigate the element concentration based sediment pollution and potential ecological risk status of the Pulicat lagoon, southeast coast of India. The textural characteristics, Fe and Mn concentration in the surface sediments are chiefly controlled by the confluence of riverine inputs and vicinity of the marine environment. The varied distribution of CaCO₃ concentration is due to the depth of the lagoon followed by the sand and silty sand characteristics of the substratum. The surface sediments are derived from riverine sources. Sediment Pollution Index (SPI), Potential Ecological Risk Index of the sediments suggests that they are falling under less polluted and low potential ecological risk category.