Metal Enrichment Factors Research Articles

Heavy metal accumulation in a moderately polluted Ulhas estuary, Western India

The impact of industrialization and anthropogenic activities on the heavy metal accumulation in a moderately polluted Ulhas estuary, Mumbai is presented here. The estuarine pollution was evaluated based on the enrichment factor of heavy metals in four sediment cores collected between the river embayment and upstream locations. The results showed that the concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, and Hg in the top 20 cm of the three downstream cores (Core 1, 2, 3) were very low, whereas core 4 collected in the upstream location showed moderate enrichment of all the metals. Most of the metals seem to have a common source such as effluents discharged from various anthropogenic activities. Statistical analyses showed that the metals in the first three cores have significant correlations with other metals as well as with organic carbon, clay, silt, or, sand. However, the fourth core was different, as it showed no correlation with sand, silt, clay, or organic carbon, as the only significant correlation was among metals. It can be therefore concluded that the first 3 cores collected from the coast to the mid-estuary exhibited normal distribution of metals owing to their geochemical normalization. However, S4 (core 4) located upstream showing moderate contamination of heavy metals seems to be a hotspot, as it is very close to the industrial discharge point. The continuous discharge of effluents fails to normalize the metals geochemically and instead, favours increased precipitation of metals as complexes, which may easily become bioavailable.

Enrichment Factors, Health Risk, and Source Identification of Heavy Metals in Agricultural Soils in Semi-arid Region of Hainan Island

To understand the enrichment factors and pollution levels of heavy metals in agricultural soils in the semi-arid region of Hainan island, 1818 surface soil samples were collected in Gancheng Town and analyzed for their heavy metal contents and physicochemical composition. Correlation analysis was used to determine the heavy metal enrichment factors. The geo-accumulation index (Igeo), comprehensive ecological risk index (RI), and hazard index (HI), as well as carcinogenic risk (CR), were used to assess the degree of pollution and health risk. Positive matrix factorization (PMF) was used to determine the primary sources of pollution and priority sources. The average values of heavy metal contents in the topsoil were 22.7, 0.128, 33.4, 14.5, 0.032, 9.32, 32.5, and 43.3 mg·kg-1 for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively. With the exception of Zn, the concentrations of other heavy metals in the topsoil were higher than the soil background values of Hainan, showing different degrees of heavy metal accumulation effect. The Igeo revealed that the major pollutant element in soils was As, followed by Cd and Cu. The RI showed that the proportion of soil samples that were high-risk level or worse was 29.4% of the total number of samples, among which As was the major source of risk. The health risk assessment results indicated that As, Cr, and Ni exposure presented carcinogenic risk for children with high CR values. Based on PMF, four major sources of heavy metals were identified in the study area. Hg was derived mainly from industrial sources, and As was closely associated with agricultural activities. Ni, Cu, Cr, and Zn were related to soil parent materials. Pb and Cd were associated with agricultural activities and traffic emissions. The PMF models combined with correlation analysis were useful for estimating the source apportionment of heavy metals in soils.

Comparisons of pollution level and environmental changes from the elemental geochemical records of three lake sediments at different elevations, Central Asia

• Concentrations and EFs of PTEs in the AS sediments in plains of CA are higher than those in the mountain lakes. • Peak fluxes of PTEs in the AS sediments occurred during 1931–2000 AD, while the mountain lakes appeared after 2000 AD. • Recent increases in Na, Sr and Ca concentrations in the AS sediments are due to natural evaporation. • EFs and fluxes of PTEs in the mountain lakes indicated increasing human activity after 2000 AD. Central Asia (CA) is susceptible to arid climates and influences from anthropogenic activities. Due to regional differences among plains and mountainous regions in CA, the analysis and comparison of lake pollution levels and responses are essential for attaining a comprehensive understanding of climate change and the timing and intensity of human activities, as well as sustainable development . Here, the elemental geochemistry of sediment cores from three lakes at different elevations during the past 120 years was studied. The results showed that before 1930 AD, the concentrations of potentially toxic elements (PTEs) in the Aral Sea (AS) were comparatively high, and their enrichment factors (EFs) showed moderate to significant enrichment. In contrast, the EFs of PTEs in the two mountain lakes were lower, suggesting zero or minor enrichment driven mainly by natural processes. During the period 1931–2000 AD, the EFs of metals in the AS displayed a decrease followed by an increase, and they were dominantly controlled by agricultural activities. The EFs and fluxes of metals began to rise in Lake Issyk-Kul (LIK), whereas their values in Lake Son-Kul (LSK) remained relatively stable. After 2000 AD, the PTE concentrations further decreased in the AS, but the concentrations of Na, Sr, and Ca increased due to natural evaporation. However, in the mountain lakes, the increases in As, P, and total organic carbon contents in LIK were influenced by agriculture activities, and the EFs and fluxes of Cd and Pb increased in LSK due to atmospheric deposition .

Distribution characteristics and ecological risk assessment of heavy metals in sediments of Shahe reservoir

Shahe Reservoir of Northern Canal Basin was selected as the study area. Nineteen surface (0~20 cm) sediment samples and three sediment core samples were collected to analyze the spatial distribution characteristics of As, Cd, Cu, Mn, Pb and Zn in the sediments. The geo-accumulation index, potential ecological risk index and risk assessment code were used to evaluate heavy metal pollution, as well as its potential risk was analyzed according to the speciation of heavy metals. Results showed that the average enrichment factors of heavy metals compared to the background value in soil of Beijing were ranked at the order as the point source pollution area > the central area of the reservoir > the downstream area of the reservoir > the Nansha River > the upstream area of the reservoir > the Beisha River, namely, 2.57 times, 2.06 times, 1.97 times, 1.95 times, 1.87 times and 1.85 times, respectively. The sediment core samples in the central area of the reservoir and the inlet of the Beisha River showed a trend of increasing firstly and then decreasing with the change of depth. Pollution assessment results showed that sediment was moderately contaminated or moderately to strongly contaminated by As, but the other heavy metals were not polluted or lightly polluted. The potential ecological risk index of all sampling sites was less than 150, showing a low ecological risk. As Cr and Cu were mainly in the speciation of residues, with low bioavailability. Although the content of Mn and Zn were low, they showed high bioavailability. Based on correlation analysis and principal component analysis, it was speculated that the sources of various heavy metal pollution in the sediment were similar, which were possibly input from the external wastewater. The heavy metals in sediment were positively related to nutrients and organic matter, indicating that all of them were mostly from the same point polluted sources.

Health Risk Assessment of Some Selected Heavy Metals in Agricultural Soils from Katsina State, North-Western Nigeria

This work contributes to the monitoring of heavy metal pollution of Agricultural soils, Katsina State Nigeria, using Atomic Absorption Spectrophotometry. The heavy metal contamination of the soil samples were analyzed based on the Geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and potential ecological risk index (PERI). The health risks of the evaluated heavy metals were estimated using the Hazard Quotient (HQ) and Hazard Index (HI)) to evaluate the possible non-carcinogenic effect and the Incremental Lifetime Cancer Risk (ILCR) for the cancer risk to the population. The results of the study had revealed that in the soil samples all the evaluated heavy metals lie within acceptable limits as set by the regulatory agencies. The evaluated soil samples pollution indices had revealed that the I-geo values for the soil samples were within the range of unpolluted to moderate pollution. Also, the heavy metal enrichment factor (EF) value for the soil samples have indicated that only the heavy metal Fe showed significant enrichment, with the soil samples being moderately contaminated with Fe. The pollution load index (PLI) also indicated unpolluted to moderate pollution. With the potential ecological risk index (PERI) values presenting low ecological risks. The calculated non-cancer risk indices in both the children and adults population for all the heavy metals were less than 1. With the exception of the ILCR for the heavy metal Pb in children from Daura zone that was in limits that environmental and regulatory agencies considered as unacceptable risk, risk values for all the heavy metals falls within the range of the threshold of the safe limit and limits regarded as safe by the regulatory agencies (10-7 to 10-4). The results of pollution indices have indicated that the Agricultural soil samples have low contamination and low health risks by the heavy metals evaluated.

Role of feather reed grass (Calamagrostis acutiflora) in phytoremediation of urban soils

Samples of soil and aerial mass of Calamagrostis acutiflora were obtained from an urban area adjacent to a street. The sampled material was analyzed to determine the content of Fe, Mn, Zn, Cu, Pb, Cd, Ni, Cr and Co, in addition to which soil was analyzed for the content of total organic carbon (TOC), salinity (EC) and reaction (pH). Based on the results, the enrichment factor (EF) and biological accumulation coefficient (BAC) of heavy metals as well as correlations between the analyzed characteristics were calculated. The content of heavy metals in the soil did not exceed the standards set for transportation areas, but the EF value implicated anthropogenic enrichment of soils with Zn, Cu, Pb, Cd and Co. Numerous, highly significant and positive correlations were obtained between the content of the elements in the soil, plants and in the soil-plant system, which suggests their relatively high bioavailability. The BAC values achieved for Co, Cr, Cu, Cd and Ni indicate that Calamagrostis acutiflora can be a useful species for phytoextraction of these elements from urban soils. Moreover, Calamagrostis acutiflora is a good choice for planting in urban areas due to its good adaptability, long growing season and tall conformation.

Distribution and assessment of the environmental risk of heavy metals in Aguada Blanca reservoir, Peru

Sediments containing high concentrations of heavy metals in reservoirs, lakes and rivers, can resuspend into aquatic environments and negatively impact water quality. The concentrations of 10 elements were studied in surface sediments and water from the Aguada Blanca Reservoir, Peru, an important water source to 1,080,000 people in the arid province of Arequipa. Sediment and water samples were collected from nine points in 2019. The enrichment, accumulation, ecological risk and distribution of metals in sediment were determined, and the information on heavy metals in water was used to assess the quality of the aquatic system. Spatially, heavy metals showed variations throughout the study area, with an increase for most elements near the deepest part of the reservoir. The average concentration of Cd in sediment was 4 times higher than the natural background. In water, As was the only element that exceeded Peruvian regulations (As > 10 μg L-1). The Enrichment Factor (EF) and Geoaccumulation Index (Igeo) of metals in sediment presented the following order: Cd> As> Pb> Zn> Cu> Ni> Cr, with Ni and Cr being the only elements that did not present enrichment. The most considerable Igeo was Cd (1.21 ± 1.45), presenting a classification of moderately to heavily contaminated. The integrated potential ecological risk (RI) of Cd presented high values in 5 points of the reservoir. The information developed will assist in establishing effective control strategies for the quality of the aquatic system.
 Keywords: heavy metals, reservoir, sediments, water quality.

Heavy metal levels and sources in suspended particulate matters of the glacier watersheds in Northeast Tibetan Plateau

This study collected summer meltwater runoff samples from several glacier watersheds of the northeast Tibetan Plateau during June-July 2017, and measured the concentrations of 17 trace elements (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Mo, Cd, In, Sb, Cs, Ba) in meltwater suspended particulate matter (SPM), in order to reveal the elemental concentration, spatial distribution, and water quality in remote glacier watershed under regional anthropogenic activities. Results showed that, the concentration of heavy metal elements was relatively high in Yuzhufeng Glacier basin, ranging from 0.57 μg/L (In) to 1,551.6 μg/L (Ba), whereas in Qiyi Glacier basin it was the lowest, ranging from 0.02 to 85.05 μg/L; and relatively medium in other glacier watersheds, with total elemental concentration varying from 1,503.9 to 1726.2 μg/L. Moreover, enrichment factors (EFs) of SPM heavy metals showed significantly higher value in the downstream than that of upper glacier region of the watershed. Most heavy metals with low EFs mainly originated from crust dust, while others with higher EFs (e.g., Cd, Sb) probably originated from anthropogenic sources. Spatially, the EFs of heavy metals were higher in Yuzhufeng and Laohugou Glacier basins; while in other regions the EFs were relatively low, which may be caused by regional land-surface and atmospheric environmental differences surrounding the various glacier watersheds. Compared with other remote locations in global range, heavy metals level (e.g., Cu, Ni, and Zn) in this region is relatively higher. Meanwhile, we find that, though the water quality of the glacier basin in northeast Tibetan Plateau was relatively clean and pollution-free, it is still obviously affected by regional anthropogenic activities. Mining activities, transportation and natural weathering and erosion processes in the study areas have important effects on the content of heavy metal pollutants of river-water SPM in the glacier watershed. Moreover, backward air-mass trajectories demonstrated the potential atmospheric pollutants transport from the surrounding cities and suburbs, to deposit in the snowpack and glaciers, and then melted out and released into meltwater runoff. This study provides a new perspective on more complete view of heavy metals distribution in glacier watershed, and new understanding for the cryosphere water environment evaluation in the Tibetan Plateau region.

Composition and sources of heavy metals in aerosol at a remote site of Southeast Tibetan Plateau, China

Knowledge of the elemental composition of aerosols at remote sites is important for evaluating the influence of anthropogenic activities. In this study, the elemental composition and sources of total suspended particles (TSP) at Yaze, a remote site in the southeastern Tibetan Plateau (TP), were investigated. The results showed that the mean elemental concentrations at Yaze were relatively low compared with those in other areas of the TP. Seasonal variations in the studied elements was characterized by low and high concentrations during the monsoon and non-monsoon periods, respectively. The enrichment factors (EFs) for some heavy metals at Yaze were slightly higher than those at Nam Co station (inland TP) but much lower than those at Mt. Yulong (southeastern TP) and in the Indian megacity of Delhi, indicating fewer anthropogenic influences at the study site relative to sites close to severely polluted regions. For the studied elements, three major sources were identified: crustal origins (e.g., Al and Fe), anthropogenic origins (e.g., Zn and Cd) and mixed origins (e.g., As and Bi). Further analysis by potential source contribution functions showed that the local TP was the primary source for elements of crustal origins. Correspondingly, the typical heavy metals were mainly attributed to pollution emitted from anthropogenic activities and transported over long-range from both South and Southeast Asia. This work demonstrates the transport of heavy metals from external sources to remote sites in the southeastern TP. These results are also useful for interpreting the historical profiles of heavy metals in the ice cores of the TP.

Possibility of Metal Accumulation in Reed Canary Grass (Phalaris arundinacea L.) in the Aquatic Environment of South-Western Polish Rivers.

A four-year research study was conducted on aquatic plants (reed canary grass) growing in the beds of three rivers and their tributaries in Lower Silesia, Poland. Metal contents (Cu, Cd, Ni, Pb, Zn, Fe, Mn) were determined in plant samples, metal accumulation in water (BCFw) and sediment (BCFB), Metal Pollution Index (MPI) and Enrichment Factor (EF) were calculated. The highest contents of copper, lead, nickel and cadmium were found in reed canary grass sampled from the Nysa Szalona River. The highest values were recorded for zinc in the Bystrzyca River, and for iron and manganese in the Strzegomka River. The series of metals were as follows: Nysa Szalona and Strzegomka: Cd < Ni < Pb < Cu < Zn < Mn < Fe, Bystrzyca: Cd < Ni < Cu < Pb < Zn < Mn < Fe. Throughout the study period, the lowest values of metals in plants were recorded in 2015 and 2018, and the highest in 2017. The general picture of MPI in aquatic plants is arranged in the series Bystrzyca < Strzegomka < Nysa Szalona. These values classify the studied material at a high level of pollution in all rivers. In the comparison of the two extreme sites, i.e., source–mouth, higher values were found at the mouth of the reservoir, which suggests that metals move with the water current and accumulate more with the direction of the river flow, which is most likely a consequence of the influence of the catchment area as the source of metals. The series of EF enrichment factor values were as follows: Bystrzyca—Ni < Cd < Fe < Cu < Zn < Mn < Pb, Nysa Szalona—Ni < Fe < Zn < Cd < Mn < Cu < Pb, Strzegomka—Ni < Cd < Fe < Zn < Cu < Pb < Mn. For all the samples studied, the values found in spring were much higher than in autumn, which indicates the great importance for research in that area. The levels of copper and iron were within the range of moderate values, lead and manganese reached very high and exceptionally high values, and the remaining metals were within the values described as significant. Bioaccumulation of metals determined relative to bottom sediments was highest in 2017 and lowest in 2018, while bioaccumulation relative to water was highest in 2018 and lowest in 2016. The four-year study found that the metal content in reed canary grass was mostly within the range of mean values presented in the literature from moderately polluted areas. Also, no significant deviation was found from levels that have been recorded for the same rivers for more than two decades.

Assessment of the Enrichment of Heavy Metals in Coal and Its Combustion Residues.

Coal-fired thermal power plants remain one of the main sources of electricity generation in Turkey. Combustion of coal creates coal ash and slag, which are often stored in landfills located near residential and agricultural fields, increasing the potential for high environmental contamination and health risks. This study investigates the content and enrichment factor (EF) of heavy metals in pulverized lignite coal and its combustion residues from the Kangal lignite coal-fired thermal power plant situated in the Central Anatolian Region of Turkey. The concentration of heavy metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Zr, Cd, Hg, and Pb) in lignite coal, slag, and fly ash samples were analyzed using an energy dispersive X-ray fluorescence technique. The concentration of Fe is highest while Hg concentration is lowest in the samples. The concentrations of heavy metals are higher in slag and fly ash samples than in lignite coal. Average values of EF (related to Earth’s crust average) revealed that extreme enrichment has been shown by arsenic and mercury in lignite coal and fly ash samples while very high enrichment has been shown in slag samples.

Rare earth elements and other critical elements in the magnetic fraction of fly ash from several Polish power plants

Fly ash is a promising alternative source of many critical raw materials, including rare earth elements. According to the EU report, the demand for these metals is set to grow due to the economic growth of the developing countries, along with the development of new innovative technologies. A geochemical analysis showed that the overall content of critical and excessive elements in fly ash from several Polish power plants was higher than in the magnetic fraction. However, the outlook coefficient values for magnetic concentrates were higher than for ashes. Ashes and the magnetic fraction from brown coals seem to be the most promising source of REY recovery. The separation of fine-size grades from the analyzed ashes does not have a significant impact on REY concentration in the obtained products. A microanalysis showed that iron spinels were enriched in Co, Cu, Ni, Mn, Mo, and Zn. The concentration of these metals in magnetic concentrates insignificantly exceeded the world average value of fly ash. The sample with the highest heavy metal enrichment factor also had the highest Fe enrichment factor. The phase composition of the magnetic fraction was dominated by: magnetite, hematite, magnesioferrite, and other iron spinels with Mn and Al substitutions. The chemical composition of ferrospheres was determined using energy dispersive spectroscopy (EDS) together with the SEM technique, and was then linked to their morphology. It was concluded that the impact on the enrichment efficiency and thus the composition of the magnetic fraction had: the diversity of morphological structures of iron spinels, the presence of AlSi glass interlayers, the presence of substitutions in the magnetite crystal structure as well as the ash particle size distribution.

EVALUATION OF THE PHYSICO-CHEMICAL COMPOSITION OF SOIL AT ELECTRONICS REPAIR WORKSHOPS IN BENIN, NIGERIA.

Soil samples were collected using grid method from several electronic repair workshops in Benin City, a control (TS) which was from a site with no electronic repair activity and a DTS thirty meters away from the workshops at a depth of 0-15cm. The physiochemical properties were carried out using standard methods. Heavy metals were determined using the Atomic Absorption Spectrophotometer (AAS), while the sequential extraction was carried out using the European community Bureau of Reference (BCR) method. The results of the physiochemical properties are as follows; 5.9 to 6.5 for pH, 150±0.71 to 342±1.34 µs/cm for EC, 2.1±0.29 to 6.9±0.87 for O.M, 6.3±0.35 to 14.2±0.35 mg/kg for TOC, 157.6±0.44 to 217.9±0.45 mg/kg for CEC, 08.3±0.50 to 13.3±1.93 mg/kg for SO42-, 08.5±1.30 to 16.1±2.00 mg/kg for NO3-, and 7.7±1.41 - 14.7±2.10 mg/kg for PO43-. The concentration for Fe, Pb, Cd, Ni, Zn and Cu are respectively; 321.3 to 514.3 mg/kg, 1.78 to 6.17 mg/kg, 0.59 to 1.05 mg/kg, 6.4 to 23.12 mg/kg, 35.81 to 41.38 mg/kg and 28.88 to 44.35 mg/kg. From the results, the metals concentrations were higher in soils from the electronic repair work shops (TS) compared to those soil samples that were 30m away from the workshops (DTS). The results of the fractionation revealed that Fe, Zn, Cd and Ni were mainly in residual and Fe-Mn oxide fraction while Cu and Pb were in residual and organic bound fraction. The enrichment factors of metals in all the sites range from no enrichment to very severe enrichment. Mobility factor in all the sites were low ranging from 3.13-16.48, indicating generally low availability as well as mobility. Environmental risk factors showed that these metals pose potential threat to the environment. Contamination factor of all metals except Cd, in all the sites, exceeded unity indicating that the soils are clearly contaminated with these metals. Continuous monitoring is essential as these sites are potential sources of these metals.

Element Contamination and Probable Ecological Concern in Surface Sediments of the Black Sea’s Iğneada Coasts

Enrichments of metals in surface sediments from Iğneada shores of the Black Sea were analysed to define the level of contamination in the region. For this purposes, Cd, Hg, Pb, Cu, Cr, Ni, Zn, Mn, Al and Fe levels in surface sediments were studied from 6 stations. Sediment samples were collected using a Van Veen grab. Elemental analyses in sediments were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The concentrations of metals varied from 0.031 to 0.091 for Cd; 0.025 to 0.064 for Hg; 3.32 to 7.88 for Pb; 5.75 to 13.42 for Cu; 25.63 to 40.07 for Cr; 14.8 to 28.2 for Ni; 18.29 to 33.21 for Zn; 268 to 377 for Mn; 10,987 to 17,101 for Al; and 11,521 to 20,700 mg·kg₋1 for Fe mg·kg₋1 dry wt. Metal levels were found to be much lower than recommended levels when compared to Sediment Quality Criteria for surface sediments. Enrichment Factors (EF), Geo-Accumulation Index (Igeo) and Pollution Load Index (PLI) were applied to the data for assessing the sediment quality. EF values were nearly between 0.33 and 2.4. Mostly EF for metals were less than 2, may be come from natural weathering processes or crustal substances, indicate no enrichment. However, some results of EF values slightly exceeding 2 indicate moderate enrichment. These rates aren’t thought to be important. Igeo values for all metals were less than 0 at all stations, suggesting that the Iğneada shores was uncontaminated by these studied metals. PLI values ranged from 0.410 in station I to 0.747 in station IV, indicating that Iğneada shores in the Black Sea were less impacted by these metals. PLI value for zone was found as 0.553665002. The Igeo and PLI values also suggest that surface sediments in Iğneada shores of the Black Sea is uncontaminated. &#x0D; HIGHLIGHTS&#x0D; &#x0D; Metal enrichments in surface sediments from the Black Sea coasts of İğneada were studied to determine the level of contamination in the area&#x0D; EF values less than or equal to 2 indicate that there is no contamination, and that the concentration is within the natural background prediction range. Only the EF values for Cr and Ni were between 2 and 5, indicating moderate enrichment&#x0D; The Igeo analyses revealed that the İğneada shores sediments were unpolluted for all studied metal levels at all stations&#x0D; All PLI values in the stations were between 0 and 1, indicating that İğneada shores were less impacted by these metals&#x0D; &#x0D; GRAPHICAL ABSTRACT

The bryophyte community as bioindicator of heavy metals in a waterfall outflow

The species diversity and heavy metal accumulation in bryophytes were determined in Huay Pah Lahd stream in Doi Suthep-Pui National Park, Thailand. Eight bryophytes from two major taxonomic groupings (epilithic mosses and liverworts) were investigated. Of these, Fissidens crispulus var. crispulus was the most dominant taxon with an importance value (IV) of 28.98%, while Ectropothecium zollingeri, Claopodium prionophyllum, and Hyophila involuta were also dominant taxa with IV ≥ 10%. Scopelophila cataractae, a rare moss species with the lowest IV (0.91%) had the greatest capacity to accumulate metals in tissue, particularly Fe, Zn, Cd and Cu in protonemata (8026.7, 1187.2, 16.9 and 530.1 mg kg−1, respectively). The highest enrichment factors (EFs) of Zn, Cd and Cu (5.3, 2.4 and 0.9, respectively) were also found in S. cataractae, while the highest EFMn (1.1) was found in H. involuta. Enrichment factors of most heavy metals were < 5 from the study bryophytes, which suggests that natural processes were the key source of heavy metals. Dilution effects caused by increased water volume during the rainy season may be responsible for low pollutant loads and the maintenance of good water quality in this waterfall stream, which is favorable for biota and general environmental health.

Terrestrial and aquatic ecotoxicity of iron ore tailings after the failure of VALE S.A mining dam in Brumadinho (Brazil)

This study consists of an ecotoxicological assessment related to one the most important environmental Brazilian disasters: the failure of an iron mining dam of the Vale S.A. in Brumadinho (Minas Gerais State, Brazil). Tailing samples (mixed with many other materials) were collected in three areas: (i) Zona Quente (n = 9) – close to the dam collapse; (ii) Parque das Cachoeiras (n = 3) – downstream of the Zona Quente; and (iii) Alberto Flores (n = 3), closer to Paraopeba river (an important tributary of one of the most important Brazilian watersheds). Acute ecotoxicological tests with Eisenia andrei and Daphnia similis and chronic reproduction tests with Folsomia candida and Chlorella vulgaris were performed. The bioassays with aquatic organisms were carried out with elutriates of the samples. Metal concentrations and physical, chemical and mineralogical properties of the samples were determined to support the interpretation of the ecotoxicological data. The increase of the particle density values (significantly correlated to an anomalous iron-enrichment and positive ΔpH values) seem to play a relevant role in the toxicity. As a result of iron-enrichment, the reduction of organic matter contents and water holding capacity were also crucial in the toxicity. Metal-enrichment factors showed abnormally high values, especially for Fe, Mn and Ni, while toxic metals concentrations exceeded the limits established by Brazilian law. Reproduction chronic effects were more intense than the acute ones, for both aquatic and soil organisms. Such extremely low reproduction levels of F. candida and C. vulgaris should be highlighted, since such organisms have a key ecological relevance. The samples collected in the Zona Quente were significantly different from the samples collected in downstream areas — fact that might be related to a high energy and turbulent flux of tailings in zones closer to dam, and the reduction of its energy in downstream areas.

Environmental capacity of heavy metals in intensive agricultural soils: Insights from geochemical baselines and source apportionment

Soil environmental capacity (EC) of heavy metals (HMs) can be used as an index to evaluate the pollution status of HMs and to provide basic data for HM remediation. However, the commonly used soil EC for HMs usually are prone to bias due to the lack of local background values (BVs) and the consideration of the contribution from various HM sources. Here, a modified method was proposed to estimate the soil EC by integrating the establishment of local BVs and the quantitative evaluation of contributions from HM sources in an intensive agricultural area of Shouguang city, China. The local BVs of HMs were established using the relative cumulative frequency distribution method. The source-specific EC was quantified based on the local BVs and the contributions of HM sources identified by receptor model and variable importance analysis. Results showed that the average BV values of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 7.67, 0.10, 62.84, 21.17, 0.031, 28.38, 19.25, and 59.60 mg kg−1, respectively, in the study area. The source-specific EC of Cd, Cu, Hg, and Zn were higher than their current EC, indicating an underestimation of soil capacity of HMs by the traditional method. The EC of HMs in these soils was generally medium indicated by their comprehensive EC index (PI) (PI >0.7), suggesting a low risk level of the targeted HMs. According to indexes such as the individual metal index (Pi) and enrichment factor (EF), special attention should be paid to Cd and Zn due to their low capacity (Pi <0.7) and high accumulation (EF > 2) in some points across this area. Altogether, our findings suggested that the modified method had a better capability for evaluating and predicting the enrichment status of soil HMs, which can be helpful for formulating the targeted measures to control HM pollution in such intensive agricultural areas.

Heavy metal pollution and associated health risk assessment of urban dust in Riyadh, Saudi Arabia.

Depending on their particle size and concentration, heavy metals in urban dust pose a health hazard to humans. This study investigated the total concentration, health risk, integrated pollution load index (IPI), and enrichment factor (EF) of various heavy metals in urban dust at different locations in Riyadh City. Surface dust samples were collected from 50 different residential yards in the north, south, west, east, and central corners of the city and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn). With respect to concentrations heavy metals were in the following order Zn > Cu > Mn > Cr > Ni > Pb > Cd. The EF trends exposed repeated anthropogenic activities were responsible for Mn, Cr, and Ni, while Pb, Zn, and Cu appeared to come from Earth’s crust. Since the heavy metal concentrations were lower than the threshold values, children and adults are exposed to lower health risk in investigated area. Also, there are no pollution of heavy metals in the dust with respect to IPI which is less than the critical limit (<1) with the exception of a sampling location in north side of the city with higher IPI showed unhealthy respiration conditions in particular areas. It was concluded that rapid industrialization and urbanization and their concentrations in dust may cause health problems in near future in north side as well as other sides of Riyadh City.

Characterization and risk assessment of metals in surface sediments and riparian zone soils of Liaohe River, China

Characterization and risk assessment of metals in surface sediments and riparian zone soils were studied in Liaohe River, northeast China. Surface sediment and riparian soil samples were collected from 24 monitoring sites along 538 km of Liaohe River. Metal concentrations and enrichment factors of Zn, Cr, Pb, Cu, Ni, and As were analyzed. Potential sources of metal contaminants along with ecological risk assessment and health risk via ingestion, inhalation, and dermal contact for residents were also assessed. Metal concentrations followed the order Cr > Zn > Cu > Ni > As > Pb in surface sediments, and Cr > Zn > Cu > Ni > Pb > As in riparian zone soils. The degree of metal pollution in Liaohe River sediments and riparian soils was considered moderate and is showing signs of recovery compared to historical concentrations reported previous studies. Enrichment factors also indicated metal pollution was not severe in both riparian and river sediments and were mainly derived from natural sources. Children had significantly higher health risks along the Liaohe River, and oral ingestion was the dominant exposure pathway. The major non-carcinogenic metal was Cr, and As was the main carcinogenic metal. Although carcinogenic and non-carcinogenic health risks of metals were considered low for both children and adults along the Liaohe River, future monitoring of metal contaminants, especially for As and Cr is recommended.

Heavy Metal Status in Some Soils of El-Gharbia Govenorate and Their Land Evaluation

The current investigation aims to study the morphological, physiochemical characteristics, classification and land capability evaluation of some soils irrigated from different water sources at the north east of Tanta city El-Gharbia governorate, Egypt. Moreover, the forms of many heavy metals (Cd, Ni, Cr, Co, Pb and Fe) in these soils namely, water soluble, exchangeable and carbonate bound as well as their relationships with soil properties were determined. For these purposes, ten soil profiles were selected representing the soils irrigated with different irrigation water sources. Three profiles were chosen representing the soils irrigated with fresh Nile water. Five profiles were selected representing the soils using agricultural drain water for irrigation. As well as, two profiles were chosen representing the soils using the mixed sewage-drainage water. The profiles were morphologically described, then soil samples were taken representing different soil layers. Moreover, ten water samples were collected from each of these water sources for integrated physical and chemical analyses. Also, soils were classified according to Soil Survey Staff (2014) and capability evaluated using ASLE model. The studied soils are deep and well drained having almost flat topography. These soils have clay loam to clay texture grade. All studied soils are moderately alkaline and non-to slightly saline. Most of these soils haven’t sodicity effect except some from those irrigated with agricultural drainage or sewage water. Most of soils have low organic matter (OM) contents except the surface layers of some from the last-mentioned soils. This could be ascribed to the factorial waste fluids and remnants in the irrigation water used for these soils. Most soils are moderately calcareous. Most of the studied soils haven’t any diagnostic horizons and classified under Entisols order and few are classified under Aridisols. The land capability evaluation indicated that, all the studied soils are considered as as good (C2). Most of the water samples have normal to slight alkalinity reaction (pH) with slight salinity hazard. Most of the agricultural drainage and all sewage waters have a slight sodium hazard and slight to moderate chloride hazard. The concentrations of heavy metals in these waters are within the permissible limits for their use as irrigation water. The total concentration of the studied heavy metals in the studied soil was in the permissible limits. The soils irrigated with drainage and/or sewage water had noticeable higher concentrations of water soluble, exchangeable and carbonate bond heavy metals fractions than those irrigated with Nile water. The relationships of these different forms of heavy metals in studied soils with soil properties were studied and determined. Also, according to the heavy metal's mobility, enrichment and contamination factors, the studied soils are considered as moderately contaminated with these heavy metals.