Elevated Concentrations Of As Research Articles

Elements in Invasive Redclaw Crayfish Cherax quadricarinatus Pose Human Health Risks in the Largest Floodplain System of South Africa

The Australian redclaw crayfish, Cherax quadricarinatus, has been introduced globally for aquacultural purposes, and invasive wild populations have established in several countries. An increase in population growth, has caused several low-income and rural communities to utilise it as an inexpensive protein source. Despite this introduction, limited research has been done on element accumulation, and the risks for human consumption. This study focused on elemental accumulation in C. quadricarinatus from two rivers in the Phongolo River Floodplain (PRF), South Africa. The non-carcinogenic and carcinogenic human health risks associated with its consumption were calculated. The accumulation order in the PRF was Zn > Cu > Pb > Cr > As > Ni > Hg > Cd. Elevated concentrations of As and Hg, as well as As, Cr, and Ni posed non-carcinogenic and carcinogenic risks, respectively. These results highlight that wild populations of C. quadricarinatus not only pose a threat to aquatic ecosystems but also potentially cause human health risks when consumed.

The Xilaokou carbonate-sulfide vein type gold deposit: A distinct mineralization in the giant Jiaodong gold province, North China

The Xilaokou gold deposit with ca. 50 t of gold reserve @ 2.7 g/t represents a novel type (carbonate-sulfide vein type) of gold mineralization within the Jiaodong gold province. However, its mineralization age and metallogenic mechanism remain poorly constrained, hindering a comprehensive understanding of the ore-forming processes in the Jiaodong gold province. In this study, we employ syn-ore stage hydrothermal monazite in situ U-Pb geochronology to determine the ore-forming age of the Xilaokou gold deposit. Additionally, we conduct in situ LA-(MC)-ICP-MS elemental mapping and sulfur isotope analysis in ore-related pyrite to unravel the sulfur source(s) and provide new insights into the ore-forming processes of the Xilaokou gold deposit. Our findings reveal the following key points: (1) U-Pb dating of hydrothermal monazite in Au-bearing pyrite yields an ore-forming age of119.9 ± 3.0 Ma. This age is consistent with the mineralization ages (around 120 ± 5 Ma) of other gold deposits in the region, including Liaoshang-, Jiaojia-, and Linglong-type deposits. (2) Gold in pyrite primarily occurs as micro-grains (5–20 μm) within pyrite fissures associated with sphalerite and galena. (3) Elemental mapping and sulfur isotope analysis indicate that major Au mineralization is linked to elevated concentrations of As, Sb, and Tl, along with heavy sulfur isotope values (δ34S∼24.7 ‰). (4) Early-stage Au mineralization is characterized by enrichment of As, Cu, and Bi, with normal sulfur isotopic composition (δ34S∼8 ‰). We propose that the carbonate-sulfide vein type gold deposits represented by the Liaoshang and Xilaokou gold deposits in the Jiaodong gold province are genetically linked to quartz-sulfide vein and disseminated type deposits. The major ore-forming stage involved the addition of S and Au from a metamorphic massif at slightly lower temperatures. These findings highlight a new exploration direction within the North China Craton. In summary, the Xilaokou gold deposit provides valuable insights into gold mineralization processes in Jiaodong, emphasizing the importance of considering diverse deposit types and their genetic relationships in the region.

Health risk assessment of potentially toxic elements in the riparian zone of the Sava River (southeastern Europe): effects of high and low water events

This study evaluated the source apportionment and level of contamination with potential toxic elements (PTEs)—As, Cd, Cr, Cu, Ni, Pb and Zn—in a riparian zone of the Sava River by calculating the Enrichment Factor (EF) and the Geo-Accumulation Index (Igeo). The study analysed the non-carcinogenic and carcinogenic health risks to both adults and children in the local population. Soil and sediment samples collected during high and low water events from 12 sites along 945 km of the river were screened. Elevated soil contents of As, Cr, Cu, Ni, and Zn were observed along the middle and lower stretches from Županja (ZUP) to Belgrade (BEO), and an elevated Cu content was detected in the upper stretch Čatež (CAT), highlighting these elements as a potential risk for the human population. Elevated As, Cd Cr, Ni, and Zn levels in the sediment were also detected, with the Ni content three times higher than the Permissible Exposure Limit (PEL) values, indicating high contamination. The study established that As, Cr, and Ni primarily originate from geological sources; Cu, Pb, and Zn are predominantly from anthropogenic sources; and Cd originates from both geological and anthropogenic sources. Although the EF and Igeo varied along the entire river stretch, they were significantly higher for most elements in the lower stretch, indicating intensive anthropogenic contamination and potential health risks. The carcinogenic and non-carcinogenic risks associated with soils and sediments during high and low water events did not imply a potential risk for adults. However, As, Cd, Cr, and Pb potentially pose the greatest non-carcinogenic risk for children in both high and low water events, with ingestion as the main route of exposure. According to our findings, the elevated concentrations of As, Cd, Cr, and Pb in the Sava River basin (SRB) pose a significant potential health risk to the local population based on several factors: the high levels of these elements, their potential contamination risk as determined by the EF and Igeo, and their bioavailability and solubility. Although the cumulative Total Hazard Index (THI) and Total Carcinogenic Risk (TCR) values are low, particularly in the lower stretch of the Sava River, these elements still present a high potential health threat.

A contribution to the understanding of hydrochemical properties of thermo-mineral water on the L’dži locality (eastern part of North Macedonia)

Regarding the aspect of mineral, thermo-mineral, and thermal waters, on the territory of the Republic of North Macedonia, there are 65 registered locations, of which 8 are categorized as spas. This includes the Kežovica spa, also known as the Štipska spa. In the vicinity of Kežovica Spa is the thermo-mineral L’Dži spring with mineralization around 1.3 g/L and the water temperature at the time of sampling was 50.1°C. Spring L’Dži is generated by a fault structure and is linked to a granite massif of Mesozoic age. These are alkaline waters (pH=8.3) and the hydrochemical type is chloride-sodium. Regarding the trace elements, the water of the L’Dži spring contains a large amount of boron and silica. Water also contains an increased content of arsenic (200 µg/L) and tungsten (169 µg/L). Elevated concentrations of As and W are characteristic of alkaline thermal waters in reducing conditions. Often elevated concentrations of Mo are accompanied by elevated concentrations of As and W, which is also the case.

Biogeochemical Assessment of Toxicity and Radioecological Danger of the Transboundary Kara-Balta River

The paper presents the results of researches of the concentration of chemical elements and natural radionuclide in the environmental objects of the Kara-Balta transboundary river basin (adjacent territories of Kyrgyzstan and Kazakhstan). The level of contamination of floodplain soils and bottom sediments of the Kara-Balta River with such chemical elements as U, Sb, As, Th, Pb, Sc, Co, Cu, Mo, Zn, V, Sr, Ba, Cs was established. Based on the calculated indicators of the contamination factor (CF), enrichment factor (EF), and index of geoaccumulation (Igeo), it was found that Sb, As and Br make the largest contribution to soil and bottom sediment pollution in the Kara-Balta water basin. At three checkpoints, an increased concentrations of U, B, Li, Sr, Mo were found in the water samples of the region’s reservoirs, which is related to the influence of the tailings of the Kara-Balta mining plant. The elevated concentrations of As, B, Ba, Co, Mn, Sb, V, and Zn were also established around the mouth of the Kara-Balta River, which flows into the Tasotkel reservoir (Kazakhstan). The results of the research can be explained by the fact that a significant part of the Kara-Balta transboundary river basin is located in the zone of a uranium natural–technogenic province.

Risk Assessment of Heavy Metals in Sediment Samples from the Mae Chaem River, Chiang Mai, Thailand.

Heavy metals are significant environmental pollutants that are recognized as posing a potential health hazard to human beings. We investigated the concentrations of the heavy metals As, Cd, Cr, Cu, Ni, Pb, and Zn in surface sediments collected from the Mae Chaem River in Chiang Mai, Thailand, during the dry season in 2021. The mean concentrations of heavy metals in sediments were, in decreasing order, Zn > Cr > As > Pb > Ni > Cu > Cd. The mean values of As, Cd, Cr, and Cu were determined to be 32.5 ± 18.3, 0.33 ± 0.07, 45.8 ± 11.9, and 21.9 ± 7.42 mg Kg-1, respectively. These levels are higher than their standard levels in Thailand, namely 10.0, 0.16, 45.5, and 21.5 mg Kg-1, respectively. Principal component analysis (PCA) revealed that the primary origins of heavy metal contamination are predominantly attributed to residential settlements and agricultural areas. The hazard quotient (HQ) was used to estimate the non-carcinogenic risk of exposure to heavy-metal-bound surface sediments for both children and adults. The results showed that the HQ values for both groups were less than 1.0 (HQ < 1.0), indicating no risk. Moreover, assessment of the long-term risk for ingestion of toxic metals indicated no risk (<10-6) based on the lifetime cancer risk (LCR). However, the LCR values of As and Cr were 5.3 × 10-6 and 2.5 × 10-6, respectively, demonstrating the most elevated LCR among the hazardous metals in terms of children's exposure. Therefore, it is possible that children living in agricultural areas and participating in activities around the study area may be exposed to elevated concentrations of As and Cr.

Sources, pathways and concentrations of potentially toxic trace metals in home environments

Despite ongoing concerns about trace metal and metalloid (trace metals) exposure risks from indoor dust, there has been limited research examining their sources and relationship to outdoor soils. Here we determine the concentrations and sources for potentially toxic trace metals arsenic (As), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) and their pathways into homes in Sydney, Australia, using home-matched indoor dust (n = 166), garden soil (n = 166), and road dust samples (n = 51). All trace metals were more elevated indoors versus their matched garden soil counterparts. Indoor Cu and Zn dust concentrations were significantly more enriched than outdoor dusts and soils, indicating indoor sources were more relevant for these elements. By contrast, even though Pb was elevated in indoor dust, garden soil concentrations were correspondingly high, indicating that it remains an important source and pathway for indoor contamination. Elevated concentrations of As, Pb and Zn in garden soil and indoor dust were associated with home age (>50 years), construction materials, recent renovations and deteriorating interior paint. Significant correlations (p < 0.05) between road dust and garden soil Cu concentrations, and those of As and Zn in soil and indoor dust, and Pb across all three media suggest common sources. Scanning electron microscopy (SEM) analysis of indoor dust samples (n = 6) showed that 57% of particles were derived from outdoor sources. Lead isotopic compositions of soil (n = 21) and indoor dust (n = 21) were moderately correlated, confirming the relevance of outdoor contaminants to indoor environments. This study illustrates the source, relationship and fate of trace metals between outdoor and indoor environments. The findings provide insight into understanding and responding to potentially toxic trace metal exposures in the home environment.

Investigating the potential impacts of coal ash runoff on the freshwater Seminole ramshorn snail (Planorbella duryi) under laboratory conditions

Coal fly ash is an industrial waste product generated by coal fired powerplants which has been shown to contain elevated concentrations of several toxic trace metals. When stored in landfills or other repositories, these trace metals can enter nearby surface waters via a number of routes including leaching or runoff. Our study examined 1) the presence and concentration of eleven trace elements in a range of lab-created coal ash leachate solutions at neutral pH using ICP-OES, 2) the physiological effects of these leachate solutions on a freshwater gastropod (Planorbella duryi), and 3) the ability of these trace metals to bioaccumulate in the tissues of exposed individuals. As, Cd, Cu, Mg, Mn, and Pb were detected in solutions at increasing concentrations concurrent with ash concentration. Exposure to leachates caused significant delays in embryonic development, reduced juvenile shell growth, decreases in egg and clutch production, and the display of avoidance behaviors. Tissues of exposed snails contained elevated concentrations of As, Cd, Cu, and Cr, with bioconcentration factors 177,550 times higher in cadmium and 85,468 times higher in arsenic in the highest treatment compared to control organisms. Our results highlight the potential harmful effects of coal ash leachates on a novel freshwater invertebrate species using several unique methodologies, providing key information regarding their potential impacts on surrounding aquatic ecosystems.

Distribution of siderophile elements during sulphide fractionation within magmatic Ni-Cu-PGE systems: A LA-ICP-MS investigation of the Crystal Lake Intrusion, 1.1 Ga Midcontinent rift

Within the magmatic pyrrhotite-pentlandite-chalcopyrite assemblage, which is ubiquitous of many Ni-Cu-PGE deposits, the spatial distribution of PGEs and semi-metals during both sulphide fractionation and low temperature alteration is not well documented. In-situ characterisation of sulphides provides a mechanism to trace the behaviour of elements during ore formation, with trace element distribution patterns providing valuable insights at the microscale into the genesis of magmatic sulphide deposits. Here we report trace element data determined by quantitative LA-ICP-MS mapping for a suite of variably altered samples from the taxitic rocks of the undeformed Crystal Lake Intrusion, within the 1.1 Ga Midcontinent Rift. Combining LA-ICP-MS data with detailed petrography and multivariate statistics helps identity the processes responsible for elevated metal concentrations and observed trace element distribution patterns within Ni-Cu-PGE systems. Such data can also improve our understanding of the effects fluid interaction and assimilation of volatile rich rocks has on the metal contents of sulphides.Element maps reveal complex distribution patterns throughout the disseminated sulphides of the Crystal Lake Intrusion, which are notably enriched in Pd relative to the massive sulphides developed locally along the basal contact. Replacement of the primary sulphides by low temperature phases is restricted to the northern limb of the intrusion and results in heterogeneous distributions and elevated concentrations of As, Pd, Ag and Bi along fractures. Zonation of As, Mo, Ru, Rh, Re and Bi is observed in both pentlandite and chalcopyrite. Within the globular ores, petrographic observations suggest the pyrrhotite-chalcopyrite contact with which ‘contact’ pentlandite resides along, may not be indicative of the initial boundary between monosulphide solid solution (MSS) and the residual sulphide liquid. This has implications for the interpretation of trace element zonation patterns, which in the case of this study are not considered to be indicative of formation by peritectic reaction. This is further supported by the spatial distribution of multivariate clusters which show features in the granular and contact pentlandite that are consistent with exsolution from MSS.Within the locally vapour saturated taxites of the southern limb, a new microfabric is documented within the globular ores, revealing a close spatial relationship between enhanced trace element concentrations and microstructures within undeformed magmatic sulphides. The microfabric, which is defined by V, Cr, As, Pb and Bi and less frequently by Mo, Rh, Pd and Re, is prevalent in unaltered coarse pyrrhotite and in contact, granular and fan textured pentlandite, and is developed in association with both silicate-capped and uncapped sulphide globules. Regardless of the exact mechanism by which the microfabric formed (e.g., fluid interaction, exsolution, gravitational compaction), this study highlights that regional deformation is not required to drive the preferential enrichment of select elements along discrete planes. Only as more high resolution element map data become available will it become apparent if the microfabric is a common feature of magmatic Ni-Cu-PGE deposits or a unique characteristic of the Crystal Lake Intrusion.

Sediment-hosted disseminated gold deposits in orogenic belts: An example from the giant Jiagantan gold deposit in the West Qinling orogen, China

Sediment-hosted disseminated gold deposits in orogenic belts share many similarities to both epizonal orogenic and Carlin-type gold deposits, leading to a lot of difficulties in their genetic classification. The giant Jiagantan gold deposit was newly discovered in the West Qinling orogen, central China, and was selected to provide a better understanding of this issue. Gold mineralization at Jiagantan is hosted within sandstone and silty slate, and the gold is intimately associated to disseminated pyrite and arsenopyrite. Three generations of pyrite (Py0, Py1, and Py2) and two generations of arsenopyrite (Apy1 and Apy2) are recognized and used to perform in situ textural, chemical, and sulfur isotopic analyses.The diagenetic Py0 is framboidal and porous, and contains elevated concentrations of As, Sb, Co, Ni, Cu, Ti, and V. The early mineralization stage Py1 and Apy1 are disseminated within sandstone and silty slate, and have the highest average Au concentrations of 7.7 ppm and 12.6 ppm, respectively. The intermediate mineralization stage Py2 and Apy2 are hosted by quartz veins and veinlets, coexisting with stibnite, chalcopyrite, and minor amounts of other sulfides. Gold mineralization mainly took place during the early mineralization stage. Microscopic observations and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) output graphs confirm the majority of gold may reside in the crystallographic structures of Py1 and Apy1.The diagenetic Py0 grains show negative δ34S values of −25.2 to −20.1‰, implying the derivation of sulfur by bacterial reduction of marine sulfate. The hydrothermal Py1, Py2, Apy1, and Apy2 have higher but still negative δ34S values ranging from −16.4 to −5.0‰, suggesting an origin of sulfur from metamorphism of the underlying Devonian sedimentary rocks.The Jiagantan gold deposit can best be classified as an epizonal orogenic gold deposit owing to the possible metamorphic origin of Au, As, S, and other associated elements. The source of ore-forming materials is the key to discriminating orogenic gold deposits from Carlin-type gold deposits, while the type of host rocks, the style of mineralization, and the occurrence state of gold may not be the effective indicators.

Transport of Potentially Toxic Elements in Solid Particulate Matter during Flash Flood Events in Upper and Lower Stretch of the Sava River

During extreme hydrological conditions such as flood events, sediments and alluvial soils may become re-suspended. As a consequence, the concentration of solid particulate matter (SPM) in the water column increases. As sediments represent a sink for the contaminants, when such perturbation occurs, the toxic substances may be re-dissolved into the water, causing harmful effects to the freshwater habitat. The purpose of this study was to evaluate the release of potentially toxic elements associated to SPM during flash floods. Two sampling sites on the Sava River were chosen: Litija (Slovenia), where the river has still the characteristics of an alpine river, and in Belgrade (Serbia), where Sava is a lowland river with a flat riverbed, slower flow and bigger quantities of fine-grained sediment. The results of the study showed a good correlation between the SPM mass concentration and water level/discharge. At both sampling sites, elevated concentrations of As, Cd, Cr, Cu, Pb, Ni and Zn were determined in SPM, indicating a moderate level of contamination at Litija and a high level at Belgrade. The results demonstrated that during the two investigated flash flood events limited the dissolution of PTE from SPM-bearing particles.

Assessment of sediment arsenic and iron occurrence and leaching potential in a potable water treatment plant wastewater stabilization pond system

Wastewater stabilization ponds (WSPs) are commonly used to reduce wastewater metal(loid) concentrations from drinking water treatment plants (DWTPs) through sedimentation. However, this results in increased sediment concentrations that can be released back into the overlying water. Thus, our goal was to evaluate the WSP metal(loid)s occurrence and leaching potential. Currently, a Saskatchewan based DWTP’s WSP system was investigated given historically elevated effluent As and Fe concentrations. The WSP consists of five ponds that were sampled on six occasions in 2019 and 2020. In addition, sediments were used in laboratory-based experiments to determine their leaching potential. Overall, the sediments were found to contain elevated concentrations of As and Fe of 25 to 400 mg/kg and 10 000 to 45 000 mg/kg, respectively. Leaching experiments indicated that the pond sediments could potentially release As and Fe with log Kd values ranging from 2.21 to 4.31 L/kg, whereas Fe ranged from 3.32 to 5.53 L/kg.

Geochemical characterization of dust from arsenic-bearing tailings, Giant Mine, Canada

Dust from uncovered mine tailings at Giant mine, an abandoned mine in northern Canada, has been a concern for nearby residents. We have utilized microanalytical mineralogical analysis combined with quantitative measurements of phase distribution and bulk concentration to fully characterize the dust currently generated from the Giant mine tailings. Surface tailings material was sampled from three tailings impoundments on site and sieved to <63 μm as a proxy for dust, and total suspended particulate (TSP) samples were collected continuously over two months to represent the airborne material that is generated from the tailings. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and -mass spectrometry (ICP-MS) show elevated concentrations of As, Sb, Zn, Pb, Cu and Ni in all samples; comparison of results for sieved and unsieved samples show that As is more concentrated in the <63 μm fraction of the tailings. The X-ray absorption near edge structure (XANES) results for the tailings indicate that the As in the samples is a mixture of As1−, As5+ and As3+. Scanning electron microscope-based mineral liberation analysis (SEM-MLA) results show that roaster-generated iron-oxides (i.e., maghemite), calcium-iron arsenate (i.e., yukonite), and arsenopyrite comprise the majority of the As-bearing particles in the surface tailings; of these three solid phases, calcium-iron arsenate poses the greatest risk to human health as it exhibits the highest relative bioaccessibility. A rare lead arsenate phase, which may be bioaccessible, was also detected in minor quantities in the surface tailings; this phase was identified as mimetite through μXRD analysis. Very little arsenic trioxide was found in the surface tailings samples, and no arsenic trioxide was found in the TSP samples; this is because the tailings that were exposed to arsenic trioxide-bearing roaster stack emissions during the 1950s and 1960s have been buried by more recent tailings. Soils near the Giant mine tailings have been found to contain arsenic trioxide from historic stack emissions, which indicates that the mine-impacted environmental media surrounding a tailings impoundment could in some cases pose a greater risk to environmental and human health than the tailings themselves.

Elevated groundwater concentrations of arsenic and chromium in ultramafic environments controlled by seawater intrusion, the nitrogen cycle, and anthropogenic activities: The case of the Gerania Mountains, NE Peloponnese, Greece

This study aimed to investigate the role of seawater intrusion, nitrogen (N)-cycle, and anthropogenic activities on the elevated groundwater concentrations of oxyanion-forming trace elements in an ultramafic environment and to study the factors controlling the hydrogeochemical characteristics of groundwater in a broader, ultramafic-dominated area of the Gerania Mountains in NE Peloponnese, Greece. Sixty-eight groundwater samples from the a) Schinos area, b) Loutraki area, and c) springs in the Gerania Mountains were analysed for an extensive set of physical and chemical parameters. Elevated concentrations of As, up to 15 μg/L, along the coastline in the Schinos area, and abnormally high concentrations of Cr6+, up to 460 μg/L, in the central part of the Schinos area, were recorded. The strong spatial correlation of Cr6+, NO3-, and P in the central part of the Schinos area, indicated that the release and subsequent oxidation of geogenic Cr in groundwater can be triggered by N and P anthropogenic inputs, such as a) septic tank effluents or N-bearing fertilisers that lead to nitrification and subsequent soil acidification and drive Cr3+ oxidation by the NO2−/NO3− redox couple and b) P-bearing fertilisers that cause the desorption of anionic Cr6+ with simultaneous PO43- adsorption and contribute additional Cr and other trace elements to the soils. Unlike Cr, geogenic As follows a different pattern of groundwater release mechanism, which is driven by seawater intrusion and initial stages of denitrification along a flowpath near the Schinos coastline, as pointed out by the strong positive correlation coefficient between As and Cl− (0.78). The increased salinity controls the mobilisation of As and other oxyanion-forming trace elements, such as B, Se, and V, resulting in their elevated groundwater concentrations through a) their desorption from the surface of Fe/Mn-oxyhydroxides under alkaline pH conditions, b) the reductive dissolution of Fe/Mn-oxyhydroxides under local hypoxic conditions, and c) an increase in the ionic strength of groundwater favouring the dissolution of Fe/Mn-oxyhydroxides.

Effect of arsenate on germination and early development parameters of three forage leguminous plants

The Chacopampean plain is one of the most arsenic affected areas in Argentina, especially in groundwater, used both for animal drinking and forage irrigation. The main objective of this study was to determine the effect of arsenic (As) present in irrigation water on the germination parameters of red clover (Trifolium pratense L.), white clover (Trifolium repens L.), and alfalfa (Medicago sativa L.) seeds exposed to different concentrations of As(V). The germination and viability parameters of seeds from the three species were not affected by elevated concentrations of As. However, As significantly reduced the radicle and hypocotyl lengths of the three forage specimens. The inhibition level of the plants increased with the increase in the concentration of As. Regarding to hypocotyl length/radicle length ratio, the results evidenced that both the hypocotyl and radicle of clover species are affected in the same degree, while alfalfa radicles seemed more affected than hypocotyls at higher concentrations of As. Our results showed that irrigation with solutions containing As affect seedling growth parameters differently in the three species, and the effect of As is mostly evidenced when in high concentrations.

Arsenic, chromium, and other elements of concern in fish from remote boreal lakes and rivers: Drivers of variation and implications for subsistence consumption

Eating fish provides numerous health benefits, but it is also a dominant pathway for human exposure to contaminants. Many studies have examined mercury (Hg) accumulation in fish, but fewer have considered other elements, such as arsenic (As) and chromium (Cr). Recently, freshwater fish from several pristine boreal systems across northern Ontario, Canada, have been reported with elevated concentrations of As and Cr for reasons that are not well understood. Our goal was to investigate the ecological and environmental influences over concentrations of As, Cr, and other elements in these fish to better understand what affects metal uptake and the risk to consumers. We measured 10 elements (including As, Cr, Hg) as well as carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes in 388 fish from 25 lake and river sites across this remote region. These data were used to determine the effect of: 1) trophic ecology; and 2) watershed geology on piscine elemental content. Overall, most element concentrations were low, often below provincial advisory benchmarks (ABs). However, traces of Hg, As, Cr, and selenium (Se) were detected in most fish. Based on their exceedance of their respective ABs, the most restrictive elements on fish consumption in these boreal systems were Hg > As > Cr. Arsenic and Se, but not Cr concentrations were related to fish size and trophic ecology (inferred from δ13C and δ15N), suggesting bioaccumulation of the former elements. Fish with enriched δ34S values, suggestive of anadromous behaviour, had marginally lower Hg but higher Se concentrations. Modeling results suggested a strong effect of site-specific factors, though we found weak trends between piscine elemental content and geological features (e.g., mafic intrusions), potentially due to the broad spatial scale of this study. Results from this study address gaps in our understanding of As and Cr bioaccumulation and will help to inform fish consumption guidelines.

Assessment of spring water quality and associated health risks in a high-level natural radiation area, North Iran.

In this study, the spring water quality of a high natural background radiation region in North Iran was evaluated by measuring hydrochemical characteristics and concentration of potentially toxic elements (PTEs) and activity concentration of radioactive elements. The carcinogenicity potential from exposure to PTEs and radioactive elements was also investigated using probabilistic approach. The hydrochemical properties of water samples revealed that there were two different water types in the study area: (1) non-thermal Ca-HCO3 type and (2) thermal Na-Cl type. The concentrations of Al, Cd, Cr, Cu, Pb, Mo, Ni, Sb, Zn, and 40K were within the recommended water quality standard set by the World Health Organization (WHO). Elevated concentrations of As, Mn, Hg, 226Ra, and 232Th occur in Na-Cl water type while elevated concentrations of Fe occur in Ca-HCO3 water type. Also, health complications of dermal contact (via balneology or bathing) are within the safe limits. The major concern regarding the contaminated springs is the possibility of soil and groundwater contamination through uncontrolled runoff and spa effluents. Preventing the spread of toxic constituents in the study area via high-risk spring water requires periodic monitoring, and applying control measures where necessary.

Application of chemical and biological tests for estimation of current state of a tailing dump and surrounding soil from the region of Tarniţa, Suceava, Romania.

This paper presents the results from a study on the current state of tailing dump, surrounding soil and water in the region of Tarniţa-Suceava, Romania. A number of chemical analyses and germination tests were applied in an attempt to estimate the ability of soil to maintain the plants growing, the bioavailability, and heavy metals uptake. Total heavy metals, exchangeable metals, acidity, and carbon and nitrogen content were determined. A modified sequential extraction method was used to determine geochemical phase distribution of heavy metals. The most abundant heavy metals in the studied samples were Cu, Zn, and Pb. Elevated concentrations of As were also found. The results from sequential extraction revealed that up to 51% of copper was retained by amorphous and crystalline iron oxides in soil. Higher content of lead was noticed in amorphous iron oxide fraction. The heavy metal concentration in river water during dry season varied from 0.13 mg/L (Fe) to 4.2 mg/L (Zn) and was below the maximum contamination level for drinking water. The soil toxicity and heavy metal bioavailability of tailing dump material and surrounding soils were studied by germination tests. The germinated plantlets on the studied soils were found to accumulate elevated concentrations of heavy metals thus indicating the bioavailability of soil contaminants. Soil decontamination by distilled water or magnesium nitrate solution was found to be efficient enough to improve the capability of the studied soils to support the germination process.

Mercury and arsenic in the surface peat soils of the Changbai Mountains, northeastern China: distribution, environmental controls, sources, and ecological risk assessment.

The potential toxic risk of mercury (Hg) and arsenic (As) in the soils of mining regions and other artificially disturbed lands receives considerable research attention. However, limited investigation has been conducted into the surface soils of natural globally distributed ecosystems, for example peatlands. In this study, we examine the distribution, controlling factors, sources, and potential ecological risks of Hg and As in 96 samples from 42 peatlands in the Changbai Mountains of northeastern China. The results showed that average concentrations (dry weight) of Hg and As at the samples sites were 169.1 ± 0.1 µg kg-1and 13.0 ± 7.7mgkg-1, respectively. The distribution of Hg is largely determined by latitude and altitude, while As is controlled more by pH, total organic carbon (TOC), and ratio of TOC and nitrogen (C/N) at the regional scale. Variations in TOC, C/N ratio, and redox conditions contribute to determining the distribution of Hg, while TOC and redox conditions mainly affected the distribution of Arsenic at the local scale. Mercury mostly comes from regional atmospheric wet deposition, whereas elevated concentrations of As are related to local anthropogenic activities. Overall, Hg and As in the peatlands of the Changbai Mountains pose a moderate level of potential risk to ecological health.

Temporal and spatial evaluation of the River Nile water quality between Qena and Sohag Cities, Egypt

BackgroundThe River Nile became under stress in the last decades from the different human (anthropogenic) activities. The present work dealt with the River Nile water quality from Qena to Sohag districts, Egypt. Sixty water samples were collected during 2016 winter and summer and subjected to chemical analysis according to standard methods.ResultsThe results indicated temporal and spatial variations in the chemical content of the collected water samples. The samples showed higher concentrations of Ca, Cl, Cd, Cu, Pb, Cr, and Zn during summer than winter, owing to intensive human activities during summer such as navigation and agricultural and industrial activities. The samples enriched with pH, TDS, Mg, Na, K, HCO3, SO4, and NO3 during winter, due to the small water column and slow flow-rate.ConclusionThe studied samples in winter and summer were unsuitable for drinking due to the recorded unacceptable concentrations of As, Cd, Cr, and Pb in the studied samples. The presence of As, Cd, Cr, and Pb may impact water consumer health because the used coagulation procedures in drinking water stations are not effective in the removal of these metals. The River Nile water is suitable for irrigation, except for some samples, which contain elevated concentrations of As and Cr. Finally, the River Nile protection laws must be strictly applied by national and international authorities to save its water quality.