Average Concentrations Of Cr Research Articles

Effects of scanning speed on the microstructure, hardness and corrosion properties of high-speed laser cladding Fe-based stainless coatings

Fe-based coatings have been prepared by utilizing laser cladding with the scanning speed ranging from 1.57 to 20.4 m/min. The microstructure and corrosion properties have been further investigated to evaluate the effects of scanning speed. The results show that, both coating's thickness and dilution rate gradually decrease with the increase of scanning speed. However, the deposition efficiency on the surface can be greatly improved by around 4 times. Under high scanning speed, the Fe-based coatings show the similar microstructure feature, comprising with dendrites and inter-dendritic structures. But the coating's microstructure can be significantly refined with the secondary dendritic arm spacing less than 1 μm. Furthermore, the gap of Cr concentration between the two structures can be effectively reduced, which shrinks the difference in corrosion resistance. On the other hand, the Fe-based coating's hardness gradually decreases resulting from the retained austenite and ferrite under high scanning speed. Compared to Q235 steel, the cladded Fe-based coatings show superior corrosion resistance with much higher corrosion potential and lower corrosion current density. Pitting dominates the corrosion forms of high-speed laser Fe-based coatings, which initially takes place on the boundaries of different structures. With the increase of scanning speed, the coating's corrosion resistance increases firstly and then decreases, and the coating cladded with the speed of 15.7 m/min shows the best corrosion resistance. Higher average Cr content and more uniform Cr distribution account for the better corrosion resistance. However, excessive microstructure refinement plays a negative role in the coating's corrosion resistance owing to more grain boundaries.

Pollution status, spatiotemporal variations, and source identification of potentially toxic elements (PTEs) in street dust, the case of Hamedan metropolis, west of Iran

ABSTRACT In the current study, a total of 162 street dust specimens were collected from 18 sites of Hamedan Megacity in 2023 and the contents of tested potentially toxic elements (PTEs) were determined by ICP-OES. The average contents of As, Cd, Cr, Cu, Ni, Pb, and Zn with 3.91, 0.609, 53.9, 70.1, 94.1, 82.4, and 308 mg kg-1, respectively, were found to be greater than those in the background samples reported for Iran, implying the anthropogenic sources of these elements. The greatest concentrations of the analyzed PTEs were observed in the commercial or industrial areas and their highest amount were related the samples obtained in fall, indicating the impact of human entries and seasonal variations of emission sources. The cumulative mean EF, I-geo, and PI values for the analyzed PTEs decreased in the order of Zn > Cd > Cr> Cu > Pb > Ni > As. Computed cumulative values of EF, I-geo, and PI ranged from 13.8 to 53.9, 0.382 to 2.35, and 1.95 to 7.66, respectively, indicating ‘severe to very severe’, ‘unpolluted to moderately polluted’ to ‘moderately to heavily polluted’, and ‘moderate to very high pollution’ contamination levels, respectively. The PLI with accumulative mean value of 2.77 reflected high pollution levels in the entire study area. Additionally, the cumulative mean values of RI with 146, demonstrated considerable ecological risks across the investigated area. The results of PCC, PCA and HCA showed that, traffic, fossil fuel combustion and industrial activities could be considered as the most important anthropogenic factors having a significant impact on the content of PTEs in the street dust. In conclusion, an accurate investigation of probability of the environmental risks due to the dust pollution by other PTEs and persistent organic pollutants (POPs) was recommended for future works.

Potential toxic heavy metals in village rainwater runoff of antimony mining area, China: Distribution, pollution sources, and risk assessment

The potential toxic heavy metal runoff from antimony mining areas poses a serious threat to the water environment and the health of residents in the village. The study found that the average concentrations of As, Sb, Cr, Pb, and Cd in the runoff were 0.1237, 0.1148, 0.0332, 0.0140, and 0.0013 mg/L, which were higher than the normal average concentrations in the water environment of 0.018, 0.0009, 0.05, 0.012, and 0.000013 mg/L, respectively.Sb and As are severely polluted, while Cd, Pb, and Cr have lower pollution levels. The coefficients of variation for As, Sb, Cr, Pb, and Cd range from 0.079 to 1.051, with Sb showing exceptionally high variability. Heavy metal elements Pb, Cd, and Sb accumulate in the southeastern area of the village, with Sb concentrations decreasing from the southeast to the northwest. As is mainly distributed in the northeastern part of the village, while Cr is primarily found in the central-western region. Source analysis indicates that As and Sb originate from mining and industrial activities, dust deposition, and domestic sewage. Cr comes from the natural geological background and metal product industry, Pb from lead-acid batteries, industrial activities, and gasoline additives, and Cd from fertilization in residential green areas and pesticide use. Health risk analysis reveals that the hazard index (HI) values for As and As in the water environment are 1.49 and 2.31, respectively, both exceeding 1, posing a serious threat to the health of village residents. The HI values for Pb, Cr, and Cd elements are all below 1, indicating lower risks. This study identified that Sb in the antimony ore area and its associated metal element As are the main elements leading to potential heavy metal pollution in the runoff of village residential areas, providing direction for subsequent water environment restoration work.

Spatial distribution, sources apportionment and risk assessment of heavy metals in the Changchun black soil area, China

The contamination of cropland with heavy metals poses a significant threat to human health and food security. Black soil, characterized by high organic matter content and associated with high grain yields, is particularly susceptible to heavy metal accumulation. Total of 99 surface soil samples were gathered from the Changchun black soil area in Jilin Province, in order to determine the spatial distribution, the sources, the pollution and risk assessment of seven toxic elements. The average concentrations of Cu, Ni, Cr and Cd are 1.15, 1.08, 1.22 and 1.19 times higher than the respective background values. The spatial variation of seven heavy metals demonstrated that Cu, Cd, and As exhibited significant spatial heterogeneity in the study area. Through spatial distribution and multivariate statistical analysis, the toxic elements Pb, Zn and Ni were mainly derived from a nature source, while Cd, Cr and As mainly comes from anthropogenic sources, with agriculture production and industrial transportation being the primary factors. By geo-accumulation index and the single factor index toxic metals showed that the accumulation of Cu, Cr and Cd in the soil were relatively high. Potential ecological risk and human health risk are at a low level overall, but there are still several points in Gongzhuling City with moderate ecological risk levels.

Spatial Variation, Ecological Risk, and Point Sources of Environmental Trace Metals in Lacustrine Ecosystems: An Assessment of Natural and Urban Inputs

ABSTRACT To gain insights into the spatial distribution, ecological risk and origins of heavy metals in surface sediments of lacustrine ecosystems in Cameroon, the content of 7 trace metals (Fe, Cr, Zn, Cu, Ni, Pb and Cd) in sediments from 60 sampling stations in 5 lacustrine environments of different formation contexts. The selected metals were investigated based on inductively coupled plasma mass spectrometry. The results revealed that the average concentrations of Cr, Cu and Cd were higher than the geochemical Threshold values. On the basis of the spatial variation, the studied metals vary quantitatively in the following order: Fe > Cr > Zn > Cu > Ni > Pb > Cd. The calculated enrichment factor (EF) and geo-accumulation index (Igeo) showed that, sediments from large cities and industrial sites had moderate enrichment (3 < EF ≤ 5) and were moderately to severely contaminated (2 < Igeo < 3) while those from low population and rural areas had minor enrichment (1 < EF ≤ 3) and were moderately contaminated (1 < Igeo < 2). With regards to cumulative pollution, the pollution load index (PLI) and the sediment pollution index (SPI) coupled with the potential ecological risk factor (Er) and the potential ecological risk index (RI), the sediments of the lakes are polluted (SPI and PLI > 1) to some extent but with a low ecological risk (Er < 40 and RI < 150). The results of Pearson correlation, principal component analysis (PCA), and cluster analysis (CA) identified three main sources: Ni would have a natural source; Pb from anthropogenic sources, and the other metals (Fe, Cr, Zn, Cu, and Cd) could have a mixed source (anthropogenic and natural). These findings serve as a scientific foundation for the advancement and use of these lake environments, which are the most attractive sites.

Characterization of Microplastics and Associated Heavy Metals in Urban Soils Affected by Anthropogenic Littering: Distribution, Spatial Variation, and Influence of Soil Properties

ABSTRACT Microplastics (MPs) are ubiquitous in terrestrial and marine environments. This research work studied the occurrence, distribution of MPs and heavy metals associated with these MPs in soils of different land- use types viz. residential, commercial, and industrial areas. We identified 15 types of MP polymers, of which polypropylene (15.51%), polyethylene (12.28%), polyamide (9.57%) were dominant. MPs abundance ranged from 8.54 × 104 to 8.51 × 105 particles/kg of soil. Average abundance of MPs in the three fractions viz. < 1 mm, 1–2 mm, and 2–5 mm were 1.85 × 105, 1.31 × 105, and 697.5 particles/kg of soil, respectively. Among the three land use types, MPs abundance in < 1 mm and 1–2 mm soil fractions were significantly higher in residential areas than that in commercial and industrial areas, i.e. <1 mm: 3.4 × 105, 1.26 × 104 and 9.0 × 104, and 1–2 mm: 2.35 × 105, 8.36 × 104, and 7.50 × 104 particles/kg, respectively, for residential, commercial and industrial areas respectively. The average concentration of Cr, Fe, Mn, Cd, Co, Ni, Cu and Pb in soils were 31.79, 11047.29, 423.92, 0.05, 11.86, 17.53, 125.95 and 28.29 mg/kg, respectively, whereas that in MPs were 6.27, 2181.64, 277.36, 0.24, 6.43, 8.29, 47.05 and 9.24 mg/kg, respectively. Concentration of Cd sorbed on MPs was higher than those found in soils. Also, Pb and Cd in MPs were positively correlated to MPs abundance, indicating MPs can be vectors of heavy metals in soils. The synergistic effect of MPs and heavy metals might put soil organisms at risk.

Türkiye'deki Ocaklardan Alınan Doğal Kil Mineral Örneklerinde Ağır Metal Konsantrasyonlarının Belirlenmesi

Environmental pollution of heavy metals is increasingly becoming a problem and has become of great concern due to the adverse effects it is causing around the world. Today, various chemical, biological, and physical pollutants arising as a result of rapidpopulation growth, industrialization, and excessive mining activities have become a major problem that adversely affects people, animals, plants, organisms, and ecosystems all over the world. Sepiolite is a clay mineral containing hydrated magnesium silicate and widely used in construction, agriculture, food, fertilizer, pharmaceutical, detergent, cosmetics, paint, paper, etc. The average concentrations of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Zr, Cd, Sn, Ba and Pb analyzed in sepiolite samples collected from three quarries (Polatlı, Beylikova, and Sivrihisar) located in the Central Anatolian Region of Turkey using EDXRF spectroscopy were found as 5456.5, 361.0, 42.0, 15.5, 65.2, 3831.5, 8.6, 23.7, 7.8, 11.8, 5.3, 13.7, 1183.2, 25.3, 3.7, 7.2, 131.9 and 5.3 mg/kg, respectively. The average enrichment factor values of V, Cr, Co, Ni, Cu, Zn, As, Sr, Cd, Sn, Ba, and Pb indicated minimal to extremely high enrichment in sepiolite. The values of non-carcinogenic risk index and cancer risk estimated to evaluate potentially health risks caused by PTEs in sepiolite samples were within the acceptable limit and the safe range except for the Beylikova quarry.

The Spatial Distribution and Influencing Factors of Heavy Metals in Soil in Xinjiang, China

Heavy metal pollution has been a problem of concern in soil ecology in recent decades. This study investigated the spatial distribution of heavy metals and their pollution levels in the soil of Xinjiang, based on the data of heavy metals published in the literature in the past five years, by using a geostatistical method, pollution index method, and geographic information system (GIS)-based spatial analysis. Additionally, the effects of five economic development indicators, such as population and industrial activities on the accumulation of heavy metals in soil, were explored by correlation analysis. The results showed that the average contents of Cd, Cr, Cu, Ni, Pb, and Zn in the soils were 2.858, 1.062, 1.194, 1.159, 1.192, and 1.086 times higher than the background values in Xinjiang, respectively. The semi-variance functions indicated that the Cd and Pb block gold coefficients of soils were greater than 25% and less than 50%, with an obvious spatial correlation. The spatial patterns showed that the high values of Cd, Cr, Cu, Ni, Pb, and Zn were mainly distributed in Karamay, Changji, Tacheng, and Kashi areas, with an overall decreasing trend from north to south, and the pollution index showed that the pollution of heavy metal Cd in soil was the most serious. Furthermore, Karamay, Changji, and Kashi areas were at heavy pollution levels. Correlation analysis showed that heavy metal Pb in the soil was significantly positively correlated with the agricultural GDP in Xinjiang, while Cd was correlated significantly and positively with comprehensive energy consumption and more significantly with industrial GDP. Thus, this study could provide a scientific basis for local evaluation of soil environmental quality and prevention and control of soil heavy metal pollution, which is of great significance for understanding the impact of human activities.

Human health risk assessment of PM10-bound heavy metals and PAHs around the Latin America’s Largest opencast coal mine

Air pollution in opencast coal mine areas is a critical issue, resulting in harmful severe effects on human health. Therefore, it is essential to understand the air pollution factors and to assess the risks to humans. This study evaluated the potential risks (carcinogen and non-carcinogen) of inhalation exposure to PM10-bound heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) in an open pit mine in northern Colombia. During February-May 2022, PM10 samples were collected at eight sites. Heavy metals (i.e., Al, Cr(VI), Mn, Cu, Zn, As, Pb) and PAHs (thirteen priority PAHs, and one non-priority PAH) levels linked to PM10 were analyzed by X-ray fluorescence and gas chromatography–mass spectrometry, respectively. PM10 concentrations were found to range between 4.70 and 59.90 µg m−3. Out of the three different zones of the study area (i.e., North Zone, South Zone, and Populated Zone), the North Zone recorded the highest daily average concentrations of Cr(VI) (104.16 ng m−3), Mn (28.39 ng m−3), Cu (33.75 ng m−3), Zn (57.99 ng m−3), As (44.92 ng m−3), and Pb (27.13 ng m−3). The fraction of the analyzed heavy metals at all monitoring sites was 82%–89% for Al, followed by Cr(VI) with 3%–6%. Cr(VI) was the major contributor to the carcinogenic risk values, while Cu, Cr(VI), and As were the main drivers for the non-carcinogenic risk. The average cancer risk range for heavy metals was 3.30 × 10–04 –5.47 × 10–04. On the other hand, the cancer risk for PAHs exposure was acceptable. The average incremental lifetime cancer risk (ILCR) values varied between 2.87 × 10–07 and 4.21 × 10–07. Benzo[a]pyrene contributed to 54%–56% of the total risk from inhalation of PM10-bound PAHs, while Indeno[1,2,3-cd]pyrene contributed to 16%–19%. Based on the Monte Carlo sensitivity analysis, exposure to Cr(VI) was the main factor affecting cancer risk in the North, South, and Populated Zones. A suitable risk assessment and management plan requires understanding PM10-bound heavy metals and PAHs concentration levels as well as their potential health risks, mainly in open-cast coal mine zones. Our study found that people living near open-pit mines face potential health risks, so it is crucial to establish policies and regulations to control emission sources.

An Assessment of the Heavy Metal Contamination, Risk, and Source Identification in the Sediments from the Liangtan River, China

The contents of six heavy metals (HMs: Cr, Cu, As, Pb, Cd, and Zn) in sediments from the upper reaches of Liangtan River (LTR) were determined. The geo-accumulation index (Igeo), pollution load index (PLI), and potential ecological risk index (RI) were employed to assess the HM contamination in the sediments. Pearson’s correlation coefficient analysis (PCC), principal component analysis (PCA), and cluster analysis (CA) were used to infer the sources of HMs. The average concentrations of Cr, Cu, As, Pb, Cd, and Zn were 44.63 ± 25.36, 31.40 ± 22.56, 4.66 ± 2.07, 29.20 ± 27.73, 0.25 ± 0.06, and 68.87 ± 104.62 μg/g, respectively. The Igeo indicated that the Cd contamination level was unpolluted to moderately polluted. The mean PLI was 0.97 ± 0.53, suggesting that the sediments were unpolluted, but close to moderately contaminated. The RI values indicated that the potential environmental risk of HMs in the sediments of the LTR was low. The results of PCC, PCA, and CA suggested that the Cr, Cu, As, and Zn in the sediment may mainly originate from natural processes; Pb mainly comes from human industrial and agricultural production activities as well as natural processes; and the main source of Cd may be the production activities of the surrounding chemical enterprises and chemical fertilizer application in farmland.

Evaluation and Prediction of Environmental Capacities of Heavy Metals in the Surface Sediments of Lakes in Huoqiu County

To clarify the environmental capacity of heavy metals in sediments of Chengxi Lake and Chengdong Lake in Huoqiu County, 30 sediment samples were collected from Chengxi Lake and Chengdong Lake, respectively. The environmental capacity characteristics and spatial distribution of heavy metals in sediments of Chengxi Lake and Chengdong Lake were studied using the comprehensive environmental capacity index, the static and dynamic environmental capacity was estimated, and the change trend of nearly one hundred years was predicted. The results showed that the average contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the sediments of Chengxi Lake and Chengdong Lake did not exceed the national soil risk screening values. The average values of the single environmental capacity index of heavy metals in the sediments of Chengxi Lake and Chengdong Lake were in the following orders:Ni(0.81)<Zn(0.83)<Cu(0.88)<Cr(0.91)<As(0.95)<Cd(0.98)=Pb(0.98)<Hg(1.00) and Ni(0.89)<Zn(0.91)<Cu(0.96)<Cr(0.98)=As(0.98)<Hg(1.01)=Pb(1.01)<Cd(1.17), respectively. Except for Hg, Pb, and Cd in the sediments of Chengdong Lake, the other elements were basically in the medium capacity. The mean of PI of Chengdong Lake was significantly higher than that of Chengxi Lake, and Chengxi Lake and Chengdong Lake were in the middle capacity level as a whole. The static total capacity of heavy metal elements in the sediments of Chengxi Lake was smaller than that of Chengdong Lake sediments, and the static total capacity was in the same order as the existing capacity, with the order of Zn>Cr>Pb>Cu>Ni>As>Hg>Cd. Within 5 to 20 years, the static and dynamic annual capacity changed faster than that of other years, and the dynamic annual capacity of each year was greater than the static annual capacity.

Spatial and Temporal Distribution and Source Analysis of Heavy Metals in Agricultural Soils of Ningxia, Northwest of China

The spatial and temporal dynamic monitoring of the heavy metal concentration in agricultural soils can help us to understand the extent and changes of regional soil heavy metal pollution, allowing us safeguard food safety and human health and provide basic data for the prevention and control of heavy metal pollution in agricultural soils. The heavy metals’ concentrations, including Cd, Cr, Cu, Hg, Ni, Pb, Zn, and As, were measured in surface (0–20 cm) soil samples collected in 2017 and 2021 from agriculture land to evaluate their pollution levels in the Ningxia Hui Autonomous Region (Hereinafter referred to as Ningxia), northwest of China. A correlation analysis, principal component analysis, and positive matrix factorization were used jointly to identify possible sources. The results showed that, for most soils, the concentrations of As, Cr, Cu, Ni, Pb, and Zn were lower than the contamination thresholds stipulated by the national guideline. The average concentrations of As, Cd, Zn, and Ni in 2021 were significantly lower than the levels in 2017 (p &lt; 0.05), but the average concentration of Cu was significantly higher in 2021 than in 2017 (p &lt; 0.05), and the average concentrations of Cr, Pb, and Hg did not change significantly during the last five years. According to the pollution assessment index (mean Igeo values), Cd and Hg were found to accumulate in the farmland environment and were the major pollutants in the region, and the hotspots with high concentrations of heavy metals were mainly located in the Yellow River irrigation area in Northern Ningxia. Four main sources of heavy metals in the soils were identified: As mainly originated from natural sources; Pb, Cd, and Ni from atmospheric deposition and industrial activities; Cr, Zn, and Cu from agricultural activities; and Hg from the coal-related industrial activities. The concentration of heavy metals from anthropogenic sources accounted for 77.10% in agricultural soils, indicating the strong influence of this source on soil heavy metal accumulation. These findings provide scientific evidence and valuable information to prevent heavy metal contamination and control of farmland.

Health Risk Assessment of Heavy Metals in Agricultural Soils Around the Gangue Heap of Coal Mine Based on Monte Carlo Simulation

To analyze the pollution characteristics of heavy metals in the soil of farmland surrounding the gangue heap of a coal mine in Chongqing, the Nemerow, Muller, and Hakanson indices were used. Meanwhile, to investigate the health risks of heavy metals in soil, a health risk assessment model was employed using Monte Carlo simulation. The results revealed that the average contents of Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn were higher than their soil background values, and the Muller index (Igeo) from high to low was as follows:Cd>Hg>Cu>As>Ni>Zn>Cr>Pb. The Nemerow index (PN) demonstrated that the results of the assessment indicated mainly light pollution (1<PN ≤ 2). The single factor index (Pi) from high to low was as follows:Cd>Cu>Ni>Cr>Zn>As>Pb>Hg. The Hakanson index (RI) demonstrated that the results of the assessment indicated mainly moderate ecological risk (150 ≤ RI<300). The single ecological risk index (Eri) from high to low was as follows:Cd>Hg>As>Cu>Ni>Pb>Cr>Zn. The health risk assessment of heavy metals revealed that the non-carcinogenic health risks of children and adults could be ignored, but carcinogenic health risks existed, with an average total carcinogenic risk index (TCR) of 1.04E-5 and 3.94E-6, respectively. The major carcinogenic factors were As and Cd. Sensitivity analysis of non-carcinogenic health risks revealed that the ingestion rate of soil (Ringest) was the most sensitive, followed by the contents of As. Meanwhile, sensitivity analysis of carcinogenic health risks indicated that the content of As was the most sensitive, followed by the ingestion rate of soil (Ringest). In general, the health risks of children, including non-carcinogenic and carcinogenic risks, were higher than those of adults.

The multi-media environmental behavior of heavy metals around tailings under the influence of precipitation

Precipitation can lead to significant leaching of heavy metals from abandoned tailings，resulting in a decline in the quality of the surrounding environment. This study aimed to simulate and quantify the migration patterns and fate of heavy metals in tailings caused by precipitation in various environmental media (tailings, air, water, soil, and sediments) using leaching tests, source apportionment, and a fugacity model. Results revealed that the average contents of Cd, Cu, As, Pb, Zn, and Cr in the un-weathered tailings were 3.43, 495.56, 160.70, 138.94, 536.57, and 69.52 mg/kg, respectively. The ecological risk factors in the tailings as well as in sediments and soils, were in the following order: Cd >Cu >As >Pb >Zn >Cr. A fugacity model based on the mass-balance methods was established, achieving a good agreement between simulation and measured values. The total amounts of Cd, Cu, As, Pb, and Zn leached from abandoned tailings over the 30-year evaluation period were estimated to be 1.09, 62.44, 0.16, 0.94, and 102.12 t, respectively. Soil and sediments are important reservoirs for heavy metals. The sum of the As, Cd, Cu, Pb, and Zn storage capacities in the soil and sediment accounted for 77.28%, 75.63%, 73.94%, 69.39%, and 57.80% of the total storage capacity, respectively. This study could provide the means for the establishment of a targeted pollution control plan, a guide for restoration projects, and will aid in controlling pollution risk and improving the surrounding environment.

Distribution of Heavy Metals in Water and Bottom Sediments in the Basin of Lake Gusinoe (Russia): Ecological Risk Assessment

Fresh water scarcity is considered a significant component, and potentially one of the most critical, of global climate change. With the rapid development of industry, there is an increasing risk of freshwater contamination by heavy metals (HMs). The danger of HM pollution is also attributed to their accumulation, which can subsequently become a source of secondary pollution in aquatic environments. In the Lake Gusinoe basin, located in Russia, concentrations of HMs were measured in both water and bottom sediments within the lake area, as well as in inflowing and outflowing watercourses. Ecological risk indices were also calculated for the Gusinoe basin. Our results showed that the average concentrations of Fe, Zn, Cr, Ni, Cd, and Pb in the water did not exceed the maximum allowable concentrations (MACs) set by Russian national standards and WHO standards, while the concentrations of Mn and Cu exceeded the corresponding MACs during winter, spring, and autumn possibly due to decomposition of aquatic vegetation and influx from groundwater sources. The average concentrations of the investigated HMs in the BSs did not exceed the background values. The water hazard index indicated a low risk for all samples in the lake water area. For all BS samples, the geoaccumulation index (Igeo) and the Pollution Load Index (PLI) indicated low pollution levels, while the values of the Enrichment Factor (EF) and the Contamination Factor (CF) indicated moderate pollution in the central part of the lake. The Ecological Risk Factor (Er) for Cu in BSs at points near major settlements and in the Tel River indicated moderate pollution. The Potential Ecological Risk Index (RI) in all investigated BS samples indicated a low risk of contamination.

Moss-bag technique as an approach to monitor elemental concentration indoors

The moss-bag technique has been used for many decades to monitor outdoor pollution. More recently, however, the method has been used to monitor indoor air pollution (IAP), as humans spend the majority of their time indoors. The purpose of the research conducted was to evaluate indoor air pollution using active moss biomonitoring. Pleurozium schreberi moss bags were exposed for two seasons (summer and winter), hanging over tile stoves and coal stoves. The selected elements: Al, Cu, Cd, Co, Pb, Zn, V, Ba, Cr, Fe, Mn, Sr, P, Ni, and S were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and, for Hg, by a direct mercury analyzer. The study found the exposure season affected the concentrations of selected elements in 62.5% of cases, and their source was identified. The average concentrations of Co, Ba, Cr, and Sr were higher, and statistically significant, in winter, after a 12-week exposure period of the mosses, regardless of the type of heating or cooking stove owned. The higher phosphorus concentrations obtained in summer indicate physiological stress caused by unfavorable winter exposure conditions. In the future, the number of species used to assess indoor air pollution should be increased and the range of pollutants expanded, along with the identification of their sources, taking residents’ lifestyles into account.

Distribution of heavy metals Hg, Pb, and Cr in the coastal waters of small islands of Ternate, Indonesia

The purpose of this study was to analyse the distribution of heavy metal concentrations of Hg, Pb, and Cr in the coastal waters of Ternate Island. There are 10 sampling points, each 4 sampling points around fishing boat docks, 2 sampling points around settlements, and 4 sampling points around Pertamina's Port. Heavy metal analysis of Hg, Pb, and Cr was carried out on seawater and sediment samples using atomic absorption spectrophotometry (AAS). The measurement of the physical-chemical parameters of the waters obtained that the average of each parameter was temperature 30.39 °C, salinity 30.33 ‰, pH 7.88, dissolved oxygen (DO) 11.54 mg/l, total dissolved solids (TDS) 35.02 mg/l, and organic carbon dissolved 62.65 mg/l. The physical-chemical parameters of the waters at this research site were still good for the survival of marine organisms. Sediment texture indicated that the dominant sediment texture at the research site was sand. The average concentrations of heavy metals Hg, Pb, and Cr in the seawater were 0.00085 mg/l, 0.01 mg/l, and 0.045 mg/l, respectively. Concentrations of heavy metals Hg in the seawater was in accordance with quality standards, while heavy metals Pb and Cr have exceeded water quality standards (Government Regulation Number 21 of 2022). The average concentrations of heavy metals Hg, Pb, and Cr in the sediment were 0.390 mg/kg, 15.66 mg/kg, and 14.02 mg/kg, respectively. Based on the Canadian Council of Ministers for the Environment (CCME, 2001), concentrations of heavy metals Pb and Cr in sediments were below the threshold for the marine biota protection while Hg has exceeded the threshold. Each heavy metal has unique characteristics and a distinctive distribution pattern controlled by physical-chemical processes that occur in the marine systems so that studies of heavy metals from each region globally are always required.

Characteristics and Potential Ecological Risks of Heavy Metal Content in the Soil of a Plateau Alpine Mining Area in the Qilian Mountains

In recent years, the ecological and environmental problems caused by mining in the Qilian Mountains have attracted considerable attention, and the government has carried out a number of comprehensive ecological environment remediation projects there, among which ecological restoration in the Qilian Mountain alpine mining area is an essential task. As a result, heavy metals have been studied in the soil of the Qilian Mountain alpine mining area. This can provide a scientific basis and data support for the establishment of a demonstration index for monitoring ecological environmental restoration in mining areas. In order to understand the content and contamination status of heavy metals in the soil surrounding the alpine mining area of Qilian Mountain, 56 soil samples were collected to determine the levels of eight heavy metals, including Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni. The spatial distribution of heavy metals in the soil of the study area was analyzed based on a statistical approach. The single-factor pollution index (Pi), Nemerow comprehensive pollution index (PN), geoaccumulation index (Igeo), and potential ecological risk index (RI) were used to evaluate soil heavy metal pollution and potential ecological risk. Principal component analysis (PCA), positive matrix factorization (PMF) models, and geostatistical analysis were also used to investigate the source of heavy metals. The results show that the average Cd, As, Cr, Cu, Zn, and Ni content of the grassland soil around the mining area exceeds the soil background values in both Qinghai Lake Basin and Qinghai Province. The spatial distribution of the eight heavy metal elements in soil showed an island-like pattern, with high-value areas of each metal element appearing, indicating that human activities in the study area had negative effects on the soil environment. The value of the single pollution index showed that levels of Ni, Cd, Cu, Cr, Hg, and As pollution were low, while there was no Pb or Zn pollution. The Nemerow integrated pollution index had an average value of 1.39, indicating a slight pollution trend. The average values of Cr and Zn in the geoaccumulation index ranged from 0 to 1, indicating mild to moderate contamination in the studied region. The average value of the integrated ecological risk index in the study area was 135.43, which is in the intermediate ecological risk range. In descending order of size, the average ecological risk index of each heavy metal element was Hg &gt; Cd&gt; As &gt; Ni &gt; Cu &gt; Pb &gt; Cr &gt; Zn. From the perspective of the spatial distribution pattern of ecological risk, the two high-value discriminants were in the western part of the study area, close to the mining area. Zn, Cu, Pb, and Cd in soils were mainly affected by human activity, while Cr and Ni were mainly affected by soil geochemistry. Cd is the main contaminant in the study area, and soil Cd contamination of the grassland in the study area must be considered.

Health risk assessment of heavy metals and metalloid in drinking water in a region of Huaihe River Basin from 2015 to 2019

To evaluate the chronic health risk of heavy metals and metalloid in drinking water through oral ingestion in a typical area. Monitoring data of seven heavy metals and metalloid elements(Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd) in drinking water in a typical area of Huaihe River Basin were collected from 2015 to 2019. The health risks of heavy metals and metalloid in drinking water in the area were assessed using the classic four-step health risk assessment model. The average concentrations of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd in drinking water in the typical area of Huaihe River Basin were(0.13±0.45), (0.49±0.49), (0.34±0.99), (1.10±2.49), (32.29±126.64), (2.13±0.50) and(0.03±0.04) μg/L, respectively. In which, Hg, Mn and Ni exceeded the limit of the Standard for Drinking Water(GB 5749-2006), the exceedance rates were 2.14%, 6.79% and 0.3%, respectively, and the maximum exceedance times were 2.61, 8.90 and 0.34, respectively. The chronic non-carcinogenic risks of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd were 1.32×10~(-2), 4.99×10~(-2), 2.97×10~(-3), 1.68×10~(-3), 7.04×10~(-3), 2.17×10~(-2) and 1.83×10~(-3), respectively. The carcinogenic risks of As, Pb, Cr~(6+) and Cd were 2.24×10~(-5), 8.82×10~(-8), 3.25×10~(-5) and 5.86×10~(-7), respectively. Hg, Mn and Ni in drinking water exceeded the standard in a typical area of Huaihe River Basin from 2015 to 2019. The chronic non-carcinogenic risks of Hg, As and other 7 heavy metals and metalloid are at an acceptable level(HQ≤1), while As and Cr~(6+) have certain carcinogenic risks(10~(-6)≤CR≤10~(-4)).

Spatial Patterns, Possible Sources, and Risks Assessment of Soil Potentially Toxic Elements in an Open Pit Coal Mining Area in a Typical Arid Region

Intensive mining activities in large-scale opencast coal mines have had a significant impact on the local environment. Elements that are potentially harmful to the environment are brought to the surface from deep underground, altering the geochemical conditions for their transport and redistributing them to the surface, causing serious local pollution. However, in-depth studies of toxic metal contamination in soils of arid coal mining areas have not yet received the attention they deserve. Although previous studies have conducted a great deal of research on heavy metal elements in surface coal mine soils, there are few studies related to the more seriously polluted surface coal mines in the arid regions of Northwest China, and there are no in-depth studies on the ecology of soil heavy metal contamination, health risks and source analysis according to the authors’ knowledge. To make up for this shortcoming, the present study takes Zn, Cu, Cr, Pb, Hg, and As in the surroundings of the tertiary coal mines in the Hongsachuan Mining Area (northern Xinjiang, China) as an example. The health, ecological risks, and pollution sources of heavy metal elements in surface coal mine soils were comprehensively analyzed. The results showed that the average concentrations of Cr, Hg, and As in the soils of open-pit coal mines greatly exceeded the corresponding provincial background values, with the Cr content exceeding China’s soil environmental quality standard Ⅰ and the As content even higher than standard Ⅱ (GB15618-1995). Geostatistical and multivariate statistical results showed that the six metals analyzed in this study can be divided into four groups, as follows. Group 1 included Zn and Cu and was mainly controlled by natural sources related to soil parent materials. Group 2 consisted of Cr and Hg and was associated with industrial practices. Group 3 was explained by As and was mainly from coal combustion during the mining activities. Group 4 was Pb and was dominantly from natural sources, together with vehicular emission during the mining activities, indicating a mixed source. Potential ecological risk index (PER) values exhibited low ecological risk in contaminated soils with Zn, Cu, Pb, and Cr, and only 10% of As samples exhibited moderate risks, while 77% of Hg samples posed ecological risks at different level, implying that Hg was the main contributor for comprehensive risk index (RI). Regardless of non-carcinogenic and carcinogenic health risk assessment, As was the primary risk element followed by Cr, and children tended to have a higher health risk than adults. In this paper, statistical methods, pollution assessment methods, and potential ecological risk models are skillfully combined, and relevant conclusions are drawn based on the human and economic geographical background information of the study area. The results can provide references for the investigation and evaluation of soil heavy metals and quantitative analysis of pollution sources in the same type of areas. In order to grasp the pollution level of potential toxic elements in the soil of large open-pit coal mines in arid areas, effective source-cutting measures are taken to provide data support the sustainable management of coal mines and local soil safety utilization measures.