Potentially Harmful Elements Research Articles

Accumulation of potentially harmful elements (PHEs) in lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.) irrigated with wastewater: a systematic review and meta-analysis and probabilistic health risk assessment.

Water shortage and stress around the world lead to increasing wastewater reuse for the agricultural sector. In addition to its benefits, it can be a way to transfer pollutants such as potentially harmful elements (PHEs) to the human food chain. Many studies have been conducted for this purpose on various vegetables; however, no comprehensive study has been performed on lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.). In this respect, the study was aimed to meta-analyze the PHEs concentration in the edible part of lettuce and coriander vegetables irrigated by wastewater. Carcinogenic risk (CR) and noncarcinogenic risk (non-CR) assessments were also done for consumers. After reviewing 32 included articles (41 studies), the rank order of the PHEs in lettuce was obtained as Fe (194.76 mg/kg) > Zn (133.47 mg/kg) > Cu (55.70 mg/kg) > Ni (26.96 mg/kg) > Pb (12.80 mg/kg) > Cr (9.68 mg/kg) Cd (8.24 mg/kg) > As (1.13 mg/kg) and for coriander Fe (1056 mg/kg) > Zn (79.80 mg/kg) > Cr (28.34 mg/kg) > Ni (24.71 mg/kg) > Cu (17.46 mg/kg) > Pb (13.23 mg/kg) > Cd (2.23 mg/kg). Total target hazard quotient (TTHQ) for adults in all countries except UAE, France, and Kenya and for children all countries except Kenya was more than 1 value. The carcinogenic risk for adult groups in Nigeria, France, China, and Iran countries was not acceptable (CR > 1E-4). As a consequence, it can be noted that wastewater reuse in the agriculture sector can endanger the health of consumers.

Geochemistry and Acute Toxicity in Rat of Calabash Clay Consumed in Douala (Cameroon)

Background: Calabash chalk geophagia commonly consumed in Sub-Saharan countries such as Cameroon may be a source of potential harmful elements such as lead and mercury. We sought to determine its geochemical composition on representative sample collected in the central market of Douala and evaluate their acute toxicity profile using rat. Methods: The geochemical analysis of three prototypes of Calabash chalk samples collected in the Douala central market, their main place of supply in the town, has been performed using the X-ray Fluorescence (XRF) and the inductively Coupled Plasma-Mass Spectrometry (ICPMS) for major and trace elements respectively. Acute toxicity was assessed according to Organisation for Economic Cooperation and Development (OECD) guidelines test No 423. Results: The geochemistry displays the Al2O3 as their main major component with iron, titanium, cerium and zinc as metal and metalloid trace elements. No acute toxicity was found in rat after administration of 5000 mg/kg body weight. Conclusion: Calabash chalk belong to the kaolinite family which had showed evidence for digestive pharmacologic propriety. Their acute consumption may be less toxic while toxicity profile of chronic consumption should be investigated.

Influence of site-classification approach on geochemical background values

AbstractThis study of peri-urban minerogenic topsoil on glacigenic or post-glacial deposits shows the influence of the site-classification approach on the differentiated median background (DMB) values of major elements and the potentially harmful elements (PHEs) Ba, Cr, Cu, Mn, Ni, Pb and Zn. Composite samples from forests and meadows were taken in 25 sites, each of which had five sub-sites. A fraction of <2 mm was used to determine the organic matter by loss on ignition (LOI), grain size by laser diffraction and the elemental contents by X-ray fluorescence. The following five site-classification approaches are compared: geochemical (G), using relative median contents of Al, K, Ti; textural (T), according to mean percentages of clay-sized fraction (CLF) and silt fraction (SIF); lithological (L), based on soil parent material texture from the soil database; soil type (S), presented in the soil database; and parent material (P), generalising the underlying Quaternary deposits. Sites were classified into four level groups in which the DMB values were estimated after eliminating anomalies. The average ranks of three scores according to SIF, CLF, LOI, Al, K, Ti, Fe, Mg, Ca and S in the respective groups revealed the highest value for the G approach. It better eliminates the CLF and SIF influences on the median assessment indices of PHEs in sites.

Contamination of groundwater by potential harmful elements from gold mine tailings and the implications to human health: A case study in Welkom and Virginia, Free State Province, South Africa

Mining of gold in the Welkom and Virginia areas of the Free State Province in South Africa has produced numerous gold mine tailings, which contain a variety of contaminants. The extent of contamination of groundwater in the area was studied by measuring several water quality indicators at eight sampling sites, and within three zones. The overall contamination of groundwater was quantified by computing a Drinking Water Quality Index (WQI). The results revealed that majority of the groundwater in the Welkom and Virginia areas is unsuitable for drinking, as confirmed by high WQIs. At only three sites was the water samples suitable for drinking. One site revealed water to be of very poor quality, while the remainder 40% of the sites indicated water to be of poor quality. The high indicator microbiological counts also affirmed the poor quality of the groundwater. Faecal coliform bacterial counts were 100% non-compliant to drinking water quality limits when compared to the World Health Organization and South African National Standard on Drinking Water 241, while E. coli counts exceeded both the drinking water quality limits at 50% of the sampling sites. Of the potential harmful elements analysed, Pb and Fe were found to be at toxic levels. For Pb, 40% of the water samples exceeded the drinking water quality limits while 63% of water samples were non-compliant for Fe. This result exposes the poor quality of the groundwater in the Welkom and Virginia areas, which poses a serious threat to the health of the local people, as groundwater is their primary source of drinking water. This research highlights the urgent need for mitigation measures to be introduced by the local authorities to improve the quality of the groundwater in the study area.

Concentration of Potentially Harmful Elements (PHEs) in Trout Fillet (Rainbow and Brown) Fish: a Global Systematic Review and Meta-analysis and Health Risk Assessment.

In this work, articles regarding the concentration on potentially harmful elements (PHEs) in fillet trout (rainbow and brown) fishes were retrieved from Cochrane, Scopus, and PubMed databases between 1 January 1983 and 30 April 2020. The pooled concentration of PHEs in fillet trout fishes was meta-analyzed using a random-effect model (REM) and following the non-carcinogenic and carcinogenic risks was calculated using the Monte Carlo simulation (MCS) method. The meta-analysis of 42 articles (43 data report) revealed that a sort of PHEs in fillet trout was 19,996.64μg/kg ww for Fe; 1834.75μg/kg ww for Co; 772.21μg/kg ww for Cu; 335.78μg/kg ww for Ni; 290.46μg/kg ww for Se; 226.20for Cr; 178.11μg/kg ww for Pb; 77.40μg/kg ww for Hg; 19.40μg/kg ww for Cd; and 3.66μg/kg ww for inorganic As. The non-carcinogenic risk assessment indicated that the lowest and highest hazard index (HI) in the adults was Pakistan (0.0012) and Turkey (0.2388), respectively, and in children was Pakistan (0.0057) and Turkey (1.114), respectively. The non-carcinogenic risk was acceptable for adult consumers in all countries (HI > 1 value) but non-carcinogenic risk for children was not acceptable in Turkey. The sort of countries based on carcinogenic risk in the adults due to inorganic As was China (1.44E-06) > Iran (9.14E-08) > Turkey (4.45E-08) > Portugal (9.04E-10). The carcinogenic risk was threshold for adult consumers in China (CR < 10-6). Consumption of fillet trout (rainbow and brown) content of PHEs in many countries cannot endanger the health of consumers.

Respiratory bioaccessibility and solid phase partitioning of potentially harmful elements in urban environmental matrices

Studies regarding the role of geochemical processes in urban environmental matrices (UEM) and their influence on respiratory bioaccessibility in humans are scarce in humid tropical regions, especially in Brazil. Contaminated UEM are potentially hazardous to humans if particles <10 μm in diameter are inhaled and reach the tracheobronchial region. In this study, we evaluated samples collected in Brazilian UEMs with a large environmental liability left by former mining industries and in a city with strong industrial expansion. UEM samples were classified into soil, sediment and mine tailings according to the characteristics of the collection sites. The respiratory bioaccessibility of potentially harmful elements (PHE) was evaluated using artificial lysosomal fluid (ALF, pH 4.5), and the BCR-sequential extraction was performed to evaluate how the respiratory bioaccessibility of the PHE was related to the solid phase partitioning. The bioaccessible fraction (BAF) ranged from 54 to 98% for Cd; 21–89% for Cu; 46–140% for Pb, 35–88% for Mn and; 41–84% for Zn. The average BAF of the elements decreased in the following order: Soil: Cd > Pb > Mn > Zn > Cu; Tailing: Pb > Cd > Zn > Mn > Cu; and Sediments: Pb > Mn > Cd > Zn > Cu. BCR-fractions were useful to predict the PHE bioaccessibility (R2 = 0.79–0.98), thus suggesting that particle geochemistry and mineralogy can influence PHE behaviour in the pulmonary fluid. Therefore, this approach provides a combination of quantitative and qualitative data, which allows us to carry out a more realistic assessment of the current situation of the potentially contaminated site and possible alternatives for decision making by the stakeholders.

Comparison of two non-specific flow-through sequential extraction approaches to identify the physico-chemical partitioning of potentially harmful elements in a certified reference material

Two non-specific sequential extraction methods utilising chemometric data processing (chemometric identification of substrates and element distribution, CISED) have been developed and used to determine the physico-chemical partitioning of potentially harmful elements (PHE) in certified reference material BCR CRM 701 (lake sediment). A miniaturized centrifugation method in which the sample was extracted on a filter insert in a polypropylene centrifuging tube, and a quasi-flow through method in which the sample was supported on a TX40 filter in a 47 mm in-line polycarbonate filter holder, gave similar results. The CISED data processing identified nine components. Seven of these were of geochemical origin – two carbonate components, an Al/Fe oxide/hydroxide component, three Fe-dominated components and one Si-dominated component – while the others represented the TX40 filter blank. The overall extraction capabilities of the methods were similar to that of the well-established BCR sequential extraction (Σsteps 1–3). However, whilst the BCR extraction is operationally defined, the CISED provides information on associations between PHE and the geochemical components identified. The flow through CISED procedure has potential applications in investigating the chemical speciation of PHE associated with urban airborne particular matter.

Fourteen years of compost application in a commercial nectarine orchard: effect on microelements and potential harmful elements in soil and plants

The objective of this experiment was to valuate, after 14 years, the impact of annual compost applications on micronutrient and potentially toxic trace elements on nectarine tree uptake and soil fertility. The study was performed in the Po valley, Italy, on the variety Stark RedGold (grafted on GF677). Since orchard planting, the following treatments were applied, in a randomized complete block design, with four replicates: 1. unfertilized control; 2. mineral fertilization (N was supplied as NO3NH4 at 70–130 kg ha−1 year−1); 3. compost at 5 t DW ha−1 year−1; 4. compost at 10 t DW ha−1 year−1. The actual rate of application was 12.5 (LOW) and 25 (HIGH) t ha−1, since compost was concentrated in the tree row. Compost was made from domestic organic wastes mixed with pruning material from urban ornamental trees and garden management and stabilized for 3 months.The supply of compost HIGH induced an enrichment of soil total Cu, Zn and Cd, and a decrease of Fe and Co concentration; with values always below the European threshold limits for heavy metals in the soil. In addition, compost (at both rates) increased availability (DTPA-extractable) of Fe, Mn and Zn, Cd, Ni, and Pb in the top soil (0–0.15 m).Total micronutrient and trace element tree content was not affected by fertilization treatments; however, the recycled fraction returned to the soil at the end of the season through abscised leaves and pruned wood of Cu, Fe, Mn and Zn was increased by mineral fertilization; Fe and Zn also by compost HIGH. Our data show that the introduction of compost at both 12.5 and 25 t ha−1 year−1 in the row did not increase the risk of pollution related to potentially toxic trace elements and at the same time increased the bioavailability of Fe, Mn and Zn.

Recent and historical pollution legacy in high altitude Lake Marboré (Central Pyrenees): A record of mining and smelting since pre-Roman times in the Iberian Peninsula

We have analyzed potential harmful trace elements (PHTE; Pb, Hg, Zn, As and Cu) on sediment cores retrieved from lake Marboré (LM) (2612 m a.s.l, 42°41′N; 0° 2′E). PHTE variability allowed us to reconstruct the timing and magnitude of trace metal pollutants fluxes over the last 3000 years in the Central Pyrenees. A statistical treatment of the dataset (PCA) enabled us to discern the depositional processes of PHTE, that reach the lake via direct atmospheric deposition. Indeed, the location of LM above the atmospheric boundary layer makes this lake an exceptional site to record the long-range transport of atmospheric pollutants in the free troposphere. Air masses back-trajectories analyses enabled us to understand the transport pathways of atmospheric pollutants while lead isotopic analyses contributed to evaluate the source areas of metal pollution in SW Europe during the Late Holocene. PHTE variability, shows a clear agreement with the main exploitation phases of metal resources in Southern Europe during the Pre-Industrial Period. We observed an abrupt lead enrichment from 20 to 375 yrs CE mostly associated to silver and lead mining and smelting practices in Southern Iberia during the Roman Empire. This geochemical data suggests that regional atmospheric metal pollution during the Roman times rivalled the Industrial Period. PHTE also increased during the High and Late Middle Ages (10–15th centuries) associated to a reactivation of mining and metallurgy activities in high altitude Pyrenean mining sites during climate amelioration phases. Atmospheric mercury deposition in the Lake Marboré record mostly reflects global emissions, particularly from Almadén mines (central Spain) and slightly fluctuates during the last three millennia with a significant increase during the last five centuries. Our findings reveal a strong mining-related pollution legacy in alpine lakes and watersheds that needs to be considered in management plans for mountain ecosystems as global warming and human pressure effects may contribute to their future degradation.

Assessment of potentially harmful elements in floodplain soils and stream sediments in Ile-Ife area, South-western Nigeria

The enrichment of potentially harmful elements (PHEs) in stream sediments (SS) and floodplain soils (FS) poses great environmental hazards to water bodies and other parts of the ecosystem. The aim of this research was to evaluate the distribution pattern of selected PHEs (Cu, Pb, Zn, Co, Mn, As, Cd, V, Cr, Ni, Th, Sr and La) in SS of selected rivers that drain Ile-Ife area and their adjacent FS, to ascertain the pollution status of these elements in the study area. Sixty samples (40 SS and 20 FS) were purposely collected for this study; the samples were analysed with ultra-trace inductively coupled plasma mass spectrometry method (ICP-MS). The PHEs results showed decreasing trend of average contents of PHEs studied; Mn > Zn > V > Cr > Pb > La > Sr > Cu > Ni > Co > Th > As > Cd for both SS and FS. Also, PHEs concentration in the studied geo media showed a significant level of enrichment as observed from the results. Elemental association showed positive correlation for topsoil, Pb/Zn = R2, 0.85 and negative correlation for topsoil Cr/Zn = R2 0.02 among the other PHEs. Source apportionment showed that the studied metal enrichment is largely anthropogenic rather than geogenic. Geoaccumulation and metal ratio indexes indicated that FS and SS studied have received significant PHEs of between moderately to strongly polluted, which implies significant environmental implications in the study area.

Annual Characteristics, Source Analysis of PM1-Bound Potentially Harmful Elements in the Eastern District of Chengdu, China.

Chengdu, a megacity in southwestern China, experiences severe air pollution; however, knowledge of the seasonal variation in mass concentration, extent of potentially harmful elements (PHEs) contamination, and sources caused by heavy metals remains lacking. This study adopted a weighting method to calculate the daily mass concentration of PM1 and used ICP-MS to determine PHE concentrations. Results indicated that PM1 mass concentration was in the range 5.44-105.91μg/m3. Seasonal PM1 mass concentration could be arranged in the following order: winter > fall > spring > summer. The concentrations of PHEs in the PM1 sample mostly showed the same seasonal variation characteristics as mass concentration. The average concentration of each PHE decreased as follows: Cu (107.44) > Zn (81.52) > Pb (22.04) > As (8.17) > Sb (1.91) > Ni (1.87) > Cr(VI) (0.84) > Cd (0.40) > Tl (0.33) (ng/m3). Enrichment factor values varied markedly from mild to anomalous enrichment. Principal component analysis revealed mainly derived from the fossil fuel combustion (55.215%).

Settled bus dust as a proxy of traffic-related emissions and health implications of exposures to potentially harmful elements

Limited information on potentially harmful elements (PHEs) contents of settled bus dusts and associated health risks for commuters is available in the literature. Here, magnetic measurements were combined with geochemical analysis to provide insight into the origin and occurrence of PHEs (Cr, Cu, Fe, Hg, Ni, Pb, and Zn) in settled bus dust samples from the urban area of Athens, Greece. Microscopic observations showed the abundance of angular and spherical Fe-rich particles, carbonaceous spherules, and a variety of Ba, Cu, Pb, and Zn-containing particles, typically deriving from vehicular emissions. Settled bus dust was magnetically enhanced in relation to the road-verge Athens soil, and exhibited a ten-fold (Hg), eight-fold (Zn, Cu), and four-fold (Pb) enrichment. The oral bioaccessibility of PHEs followed the order Zn > Pb > Cu > Cr > Ni > Fe > Hg. Potential adverse health risk effects through ingestion, inhalation of particles and Hg vapors, and dermal contact were assessed using the U.S. EPA risk assessment model. Potential cancer risk for drivers and children (1–6 years old), commuting four days per week for 120 min per day, were above the regulatory levels of 1 × 10−4. Non-cancer risks may also arise, mainly because of inhalation of Hg vapors. Despite the intrinsic uncertainty related mainly to toxicity data and exposure parameters, the risk assessment helped to prioritize Cr and Hg as the elements of major concern.

Enrichment, Source Apportionment and Health Risk Assessment of Soil Potentially Harmful Elements Associated with Different Land Use in Coastal Tidelands Reclamation Area, Eastern China.

Coastal tidelands are important ecological habitat resources and valuable resources for agricultural land reclamation. Enrichment of potentially harmful elements (PHEs) in soil caused by anthropogenic activity is an important factor implicated in the ecological deterioration of soil in China. A total of 54 soil sample sites were selected from a 30-year reclaimed tideland and an adjoining coastal wetland. Descriptive and multivariate statistical analyses were performed to describe the enrichment, source, health risk status of eight PHEs (As, Co, Cr, Cu, Mn, Ni, Pb, and Zn) after long-term reclamation. Results indicated that after 30 years of reclamation, most soil PHEs are slightly enriched, whereas no serious threat of environmental pollution was observed. In the reclamation area, the enrichment of PHEs in the aquaculture land, industrial land, and cropland was relatively high compared with other land use types, such as tideland and halophyte land. The source analysis divided the PHEs into five categories: (1) Cu; (2) Co and Mn; (3) Cr; (4) As and Pb; (5) Zn and Ni. Cu was completely derived from natural parent materials and other elements were governed by both weathering of parent rock and human activities, including agricultural activities, industrial production, and transportation emissions. The health risk assessment showed that the soil PHEs potentially had no non-carcinogenic risk to the public, but there was an acceptable probability to have cancer due to Cr and As. Meanwhile, children are more susceptible to harm from the PHEs in soil than adults. According to the economic and social development situation in the coastal region, it is necessary to pay attention to the environmental threats of PHEs enrichment.

Metals and PFAS in stormwater and surface runoff in a semi-arid Canadian city subject to large variations in temperature among seasons.

Because compounds accumulate through dry periods and enter aquatic systems in just a few seasonal events such as snowmelt and summer storms, surface waters in semi-arid, cold regions, such as the Canadian Prairies, are particularly vulnerable to loading of contaminant from runoff events from surfaces. This study assessed concentrations of metals and selected trace organics entering a river via surface runoff from an urban region and how these semi-arid regions with large seasonal variations in temperature might differ from more temperate regions. Selected potentially harmful elements (PHEs) including, Mn with Cr, Cu, Zn, Ba and U all exceeded guideline discharge values set by the Canadian Council of the Ministers of the Environment (CCME) by as much as 16-fold. Variation among discharges during spring, summer and winter was observed. For example, across the whole city, an estimated 6kg of zinc was discharged in a spring storm, 36kg in a summer storm and 17tonnes in snowmelt. The mass of Zn discharged is similar to the annual loading estimated for Stockholm, Sweden, but in Saskatoon, Saskatchewan, Canada, the bulk of runoff was during snowmelt. The mean sum of poly- and per-fluoroalkyl substances (PFAS)in stormwater was 9.0ngL-1, which is consistent with concentrations observed in other Canadian cities (6.5-16ngL-1). These concentrations of PFAS are likely due to dispersed sources and orders of magnitude less than thresholds for toxicity to fish and aquatic invertebrates.

Human Health Risk Assessment and Potentially Harmful Element Contents in the Cereals Cultivated on Agricultural Soils.

Potentially harmful element (PHE) contents were investigated in six species of cereals in southern Poland, with human health risk implications assessed afterwards. The PHE contents belonged to the following ranges (mg/kg wet weight): As below the limit of detection (<LOD)–0.013, Cd <LOD–0.291, Co <LOD–0.012, Cu 0.002–11.0, Hg <LOD–0.080, Ni <LOD–8.40, Pb <LOD–12.0, Sb <LOD–0.430, Tl <LOD–0.160, and Zn 5.47–67.7. The Pb and Cd contents exceeded the maximum allowable concentration (MAC) values for wheat, oat, rye, and barley in the Śląskie region. The bioaccumulation coefficient (BA) for the total PHE content in the soil indicated that cereals had no potential of PHE accumulation. Regarding the statistical daily consumption of cereals, the PHE intake rates, expressed as a percentage of permissible maximum total daily intake (% PMTDI), were the following: As 0.0003, Cd 0.193, Co 0.0003, Cu 0.075, Hg 0.424, Ni 3.94, Pb 3.16, Sb 0.23, Tl 0.27, and Zn 0.44. The total non-carcinogenic risk values (HQ) exceeded the target risk value of 1 for wheat (HQ = 13.3) and rye (HQ = 3.44). For other cereals, the total non-carcinogenic risk values decreased in the following order: barley (HQ = 0.47) > oat (HQ = 0.38) > maize (HQ = 0.02). The total non-carcinogenic risk value of the statistical daily consumption of cereals was acceptable low (HQ = 0.58). The acceptable cancer risk (CR) level of 1.0 × 10−5 investigated only for As was not exceeded under any of the intake scenarios. Concerning the mean As content in cereals consumed daily in statistical amounts the CR value was equal to 5.1 × 10−8. The health risk value according to the Pb content in cereals using the margin of exposure (MOE) approach was equal to 1.27, indicating an acceptable low risk.

Distribution of Potential Harmful Trace Elements and Potential Ecological Risk in the Jiulongchi Wetland of Fanjing Mountain, Southwest China.

In order to understand the distribution and ecological risk of potential harmful trace elements (PHTEs) in the high altitude areas of the Fanjing Mountain World Natural Heritage Property, 30 surface samples including soil and plants were collected in April, 2019 in the Jiulongchi wetland which lies in the saddle between the New Jinding Peak of Fanjing Mountain and Fenghuang Peak. The contents of 23 major and trace elements were determined, and the pollution characteristics and potential ecological risk of 11 PHTEs (Mn, V, Zn, Cr, Co, Ni, Cu, As, Cd, Sb and Pb) were discussed. The element contents showed significant differences in plant and soil samples. Enrichment factor and single-factor pollution index demonstrated that Mn, Zn, Co, As and Cd in the soil were in a clean state. The potential ecological risk index and pollution load index indicated an overall good ecological condition of Jiulongchi wetland, with a weak pollution degree. Comparisons of relevant studies showed the anthropogenic activities have considerable impacts on the pollution status of PHTEs with significant spatial differences in Fanjing Mountain. Multivariate statistical analysis proved that Pb and Sb were main pollutants of the soil in the Jiulongchi wetland, and the mining and smelting of minerals such as mercury, manganese and lead-zinc ore in the adjacent areas could be the main pollution sources through atmospheric deposition. This study could provide targeted strategies for the environmental protection and management of the Property and give scientific evidence for the pollution prevention in southwest China.

The classic aqua regia and EPA 3051A methods can mislead environmental assessments and certifications: Potentially harmful elements resorption in short-range order materials

EPA 3051A and Aqua Regia (AR) are widely adopted by global environmental agencies to assess soil quality in relation to potentially harmful elements (PHE). However, previous study has shown the formation of large amounts of short-range order materials (SRO) in the residues of these extractions. Residues obtained from the 3051A and AR were recovered from filter papers. To characterize the SRO in these residues, sequential extractions were performed with 0.2 mol L−1 ammonium oxalate (AO) and 0.5 mol L−1 NaOH. On average (n = 15), the 3051A and AR residues contained 37% and 60% of SRO, respectively. The largest amounts of SRO formed in the AR residue was in sample 5 (99% of SRO). The main component of the SRO was Al2O3-AO, Fe2O3-AO and SiO2–NaOH. The formation of SRO and PHE resorption levels were random and highly dependent on the mineralogy of the soil clay fraction. Soils rich in smectites, which are more common in temperate regions, formed larger amounts of SRO. The association of Pb with the SRO was more pronounced in the 3051A residue than in the AR residue. If SRO was not extracted after 3051A, in sample 7, for example, 595 mg kg−1 of Pb (10.2%) would have not been accounted. The maximum PHE resorptions in SRO were (%): Pb – 10; Cu – 470; Ba – 280; As – 21. The underestimation of PHE contents due to resorption mechanisms may lead an environmental agency to certify the use of an area contaminated with PHE.

Analysis of the Distribution of Some Potentially Harmful Elements (PHEs) in the Krugersdorp Game Reserve, Gauteng, South Africa

The Mintails Mogale Gold (MMG) and the Rand Uranium (RU) are two large-scale mining consortiums active in re-mining old tailings dams and dumps in Krugersdorp and are a source of mine discharge feed into the Krugersdorp Game Reserve (KGR). This has resulted in a noticeable accumulation of potentially harmful elements (PHEs) over a number of years. Efforts were implemented to interpret the concentration levels of PHEs in soils of the study areas of which a total of 36 georeferenced soil samples were collected (in triplicate) from the MMG, RU and KGR, including samples from farmlands and waterways adjacent to the mining sites. Samples were then analysed by both inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) for 36 elements. From the 36 elements of this study, detailed evaluations of the occurrence of 12 selected elements were discussed. The geochemical landscape at the KGR is shown to be in flux. The major mediating influences on the behaviour of As, Co, Cu, Hg and Pb, as they enter the KGR largely in the form of acid mine drainage (AMD), are the geological substrate (mostly in carbonate form). Analysis of the soils showed high levels of contamination for As and Co in ppm. The mean maximum of As ranged from (5.00–170.30) with the highest level found in the Krugersdorp site. The mean maximum of Co ranged from (46.00–102.30) with the highest level found in MMG. All of these values were well above the recommended maximum acceptable concentration (MAC) values, i.e., As (15–20) and Co (20–50). The mean maximum values for Pb (12.40–92.30); Cu (18.50–115.30) and Hg (12.40–92.30) content in surface soils of all four segments studied falls well within the MAC range for agricultural soils i.e., Cu (60–150); Hg (0.5–5) and Pb (20–300).

Geochemistry and associated human health risk through potential harmful elements (PHEs) in groundwater of the Indus basin, India

Inorganic contamination in groundwater has become a major health concern because of its acute and chronic health impacts. To investigate the major hydro-geochemical processes controlling groundwater quality in a part of the Indus river basin, 29 groundwater samples were collected and tested for major ions and potentially harmful elements (PHEs) including Mn, Cu, Cd, Cr, Pb, Fe, and Zn. The cations and PHEs were measured using the atomic absorption spectrophotometer and the anions were analyzed using ion chromatograph. Anthropogenic activities and rock–water interactions are the major factors controlling groundwater quality, along with silicate weathering and evaporation. Ca–HCO3 is the dominant water facies, followed by Na–HCO3 and Na–Cl water facies. Among PHEs, Pb is the most dominant contaminant with 21 samples exceeding WHO guidelines followed by Cr and Fe in 27% and 24% of samples, respectively. Health risk to the population for both dermal and direct ingestion was assessed by calculating chronic dose index (CDI), hazardous quotient (HQ), and hazardous index (HI) for children and adults. HQ through ingestion was highest for Cd because of its low reference dose value. HI for dermal exposure was found to be safe for both children and adults, with values below 1; for ingestion 14 samples had high HI > 1 for adults, and 27 samples for children. High HI values indicate that at a few locations, the groundwater is not suitable for consumption and can cause serious health implications. Proper planning for mitigation is required and large-scale testing along with sharing of wells among neighbors is recommended for reducing exposure.

Development of an appropriate method for measuring gross alpha activity concentration in low-mass size-fractionated samples of sediment using solid-state nuclear track detectors

A passive technique using solid state nuclear track detectors was developed to detect the low-level gross alpha activity (Aα) in low-mass size-fractionated (< 10 g) samples of urban surface deposited sediment. The measurement system was calibrated using a source containing thorium monazite. The method was applied to measure radioactivity of the samples collected from various urban landscape zones in Ekaterinburg, Russia. The correlation between Aα, gross beta activity (Aβ) and potential harmful elements (PHE) concentrations was studied. It was found that the migration of natural radionuclides and PHE in the urban environment is associated with the same environmental processes.