Trace Element Concentrations Research Articles

Tracing the Origin of Oxide Inclusions in Vacuum Arc Remelted Steel Ingots Using Trace Element Profiles and Strontium Isotope Ratios

Non-metallic inclusions (NMIs) in steel have a detrimental effect on the processing, mechanical properties, and corrosion resistance of the finished product. This is particularly evident in the case of macroscopic inclusions (>100 µm), which are rarely observed in steel castings produced using state-of-the-art technologies, whereby casting parameters are optimized towards steel cleanliness, and post-treatment steps such as vacuum arc remelting (VAR) are used, but frequently result in the rejection of the affected product. To improve production processes and develop effective countermeasures, it is essential to gain a deeper understanding of the origin and formation of NMIs. In this study, the potential of elemental and isotopic fingerprinting to trace the sources of macroscopic oxide NMIs found in VAR-treated steel ingots using SEM-EDX, inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS (LA-ICP-MS), and laser ablation multicollector ICP-MS (LA-MC-ICP-MS) were exploited. Following this approach, main and trace element content and 87Sr/86Sr isotope ratios were determined in two specimens of macroscopic NMIs, as well as in samples of potential source materials. The combination of the data allowed the drawing of conclusions about the processes leading to the formation of these inclusions. For both specimens, very similar results were obtained, indicating a common mechanism of formation. The inclusions were likely exogenous in origin and were primarily composed of calcium–aluminum oxides. They appeared to have undergone chemical modification during the casting and remelting process. The results indicate that particles from the refractory lining of the casting system most likely formed the macroscopic inclusions, possibly in conjunction with a second, calcium-rich material.

Composting Urban Biowaste: A Potential Solution for Waste Management and Soil Fertility Improvement in Dolisie, Congo

Population growth, urbanization, and changing consumption patterns are contributing to an increase in household waste production, particularly in sub-Saharan Africa. Composting of biowaste presents a sustainable solution by reducing the volume of waste sent to landfills while enriching the soil. The main objective of this study was to evaluate the suitability of solid household biowaste for composting in market garden crops in Dolisie (the Republic of Congo). Specifically, the study aimed to (i) assess the production and management practices of solid household waste in relation to socio-economic factors, (ii) analyze the chemical composition of solid household biowaste and its concentration of trace elements (TEs), and (iii) determine the potential phytotoxicity of solid household biowaste across different production seasons. In this study, wastes were collected from 40 households over a 60-day period, with daily sorting conducted during both the dry and wet seasons. Using a completely randomized design, various compost application rates were incorporated into the soil to conduct a germination test. The quality of the biowaste and compost was evaluated through physicochemical analyses. Results showed that approximately 90% of high-income households received regular waste collection services and practiced waste separation in contrast to middle- and low-income households. The composition of the biowaste was primarily composed of fruit and vegetable scraps, with slight contamination by chromium and cadmium. Temperature, pH, and humidity levels showed similar trends during compost formation in both the rainy and dry seasons. Germination rates were above 80% in all treatments across both seasons, indicating that the compost was mature. Overall, all physicochemical parameters of the compost met established quality standards, and trace element concentrations were below the recommended thresholds. The study concluded that biowaste, once converted into compost, can be safely applied to agricultural soils without posing any risk of phytotoxicity or contamination to crops.

The Source and Significance of Silicon in the Late Permian Dalong Formation, Northeastern Sichuan Basin

The Late Permian was a critical interval in geological history, during which dramatic changes occurred in the Earth’s surface system, and a set of black rock series rich in organic matter and silicon, the Dalong Formation, was deposited in the northeastern Sichuan Basin. We conducted a detailed sedimentological and petrological investigation integrated with (major and trace) element contents in the deep-water sequence of the Xibeixiang and Jianfeng sections. It demonstrates the source of silicon, tectonic background, and sedimentary environment of the Dalong Formation, and explores the influence of hydrothermal activities on organic matter enrichment. The results show that the upper part of the Dalong Formation contained more radiolarians in the Xibeixiang section compared to the Jianfeng section. Hydrothermal proxies such as Eu/Eu*, Al-Fe-Mn diagram, Al/(Al + Fe + Mn), and LuN/LaN suggest a biotic origin for the chert in the Dalong Formation in the Xibeixiang and Jianfeng sections, while the Xibeixiang section was slightly affected by hydrothermal activities. The La-Th-Sc diagram and the La/Sc and Ti/Zr crossplots point to a continental island arc and active continental margin origins for the Xibeixiang and Jianfeng sections. Combined with previous research, the silicon of the Dalong Formation in the northeastern Sichuan Basin is mainly derived from biological sources. The Xibeixiang section was affected by a small amount of hydrothermal fluid due to its proximity to the Paleo-Tethys Ocean and continental island arcs. Furthermore, the enrichment of organic matter was predominantly driven by high productivity, with minimal impact from hydrothermal activities. These insights hold significant research value and practical implications for shale gas exploration in the Sichuan Basin.

Land-derived metals impact the survival and settlement of larval mussels.

Global declines in wild mussel populations and production have been linked to the impacts of climate change and pollution. Summer die-offs of mussels (Perna canaliculus), spat retention issues, and a severe decline in mussel spat settlement have been reported in the Marlborough Sounds, an important area for mussel farming in New Zealand. Preliminary evidence suggests that naturally occurring contaminants and changing land use in the surrounding areas, could contribute to the decline of this species. The aim of this study was to determine whether trace metals affect the larval survival and settlement of mussels. Concentrations of trace elements in surface waters, mussel gill tissues and sediments were characterized across the Marlborough Sounds. Over a two-year period, diffusive gradients in thin film (DGT) passive samplers were deployed at three locations, to estimate trace metal levels in the water column. Mussel gills and sediment were also collected to complement metal monitoring. Lead and zinc were the most abundant bioavailable metals detected during in-situ monitoring, with strong temporal variability. Ecotoxicity thresholds affecting P. canaliculus embryo-larval development and settlement were determined for these metals and overlapped with levels of lead and zinc found in the field during the reproductive season of mussels. Furthermore, high concentrations of zinc and lead in waters were strongly correlated with rain events, suggesting land runoff in the surrounding catchments as their main source. We hypothesize that vulnerable early life stages of mussels are exposed to these metals, especially following summer rainfalls, delivering pulses of these metals into the environment while triggering mussel spawning events. Climate-associated stressors (intense storms, marine heatwaves, freshwater and sedimentation inputs, acidification) are likely to exacerbate any toxic effects from land-derived inputs; a better understanding of these complex interactions is essential to prevent further P. canaliculus recruitment declines occurring in NZ, and in other mussel species globally.

The Distribution of Rare Earth Elements in Coal Fly Ash Determined by LA-ICP-MS and Implications for Its Economic Significance

Coal fly ash represents a potential resource of some critical elements, including rare earth elements (REEs), which are retained and concentrated during coal combustion. Understanding the distribution and modes of occurrence of REEs within fly ash is vital to developing effective recovery methods and enhancing their economic value. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was applied to investigate the in situ elemental constituents of coal fly ash phases, including aluminosilicates, Ca-(Fe)-enriched aluminosilicates, Fe-oxides, and SiO2/Quartz, in order to explore the distribution of REEs in combustion products. LA-ICP-MS results show that V, Cr, and Nb are mainly enriched in Ca-Ti-enriched aluminosilicates with trace element concentrations referenced to the original fly ash composition. Lithium is primarily enriched in SiO2 glassy grains, followed by Ca, (Fe)-enriched aluminosilicates. Co, Ni, and Cu present a concomitant distribution in the Fe-enriched phases, such as Fe-oxides and Fe-enriched aluminosilicates. The chondrite normalized REE distribution patterns show characteristics of LREE enrichment and Eu-negative anomalies in most phases, while the REE patterns of SiO2 glassy grains have a distinct positive anomaly in Sm, Gd, and Dy, coupled with a deficiency in LREEs. Compared to feed coal, elements such as Li, V, Cr, Co, Ni, and Nb and REEs are enriched 2~10 times in various phases of fly ash, with REEs notably concentrated six times higher in aluminosilicates and Ca-Ti-enriched aluminosilicates than the original coal. This study further discusses the feasibility, calibration principles, and advantages of using LA-ICP-MS to determine REE distribution, as well as the economic implications of REE extraction from coal fly ash.

The dead can talk: Investigating trace element and organic pollutant exposure in mammalian roadkill under contrasting habitats.

Urban environments are exposed to a substantial range of anthropic pressures, including chemical exposure. While trace metals and legacy pollutants have been well documented, the extent of wildlife exposure to emerging contaminants has received little attention, in terrestrial mammals. Concentrations of trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn) and 48 organic pollutants (Polychlorinated Biphenyls: PCBs, Organochlorine Pesticides: OCPs, Polycyclic Aromatic Hydrocarbons: PAHs, phthalates and pyrethroid pesticides) were measured in tissues of European hedgehogs (Erinaceus europaeus) in southern Sweden. Road kills and carcasses collected in 2021 and 2022by citizen science participants were used to characterize the level, tissue distribution and composition of mixtures in liver, spines and teeth samples. Phthalate diesters and PCBs were the most prevalent compounds in liver samples, with mean concentrations (±SD) of 1090±681 and 284±231ngg-1 of dry weight, respectively. Bioaccumulation patterns were observed for some organochlorine compounds but were hampered by the small sample size. Trace element concentrations and tissue distribution were strikingly equivalent between tissue type and age-classes (juveniles and adults) of hedgehogs, except for a handful of elements (e.g., Pb, Al, As), but contamination profiles differed between habitat types. While no adverse health effects are expected to occur from the body burdens measured for most of the target analytes, concerns might be expressed for the exposure to PCBs, phthalates and some non-essential trace metals (e.g., lead >15μgg-1 dw), which were found at levels above or approximating toxic thresholds in mammal tissues. The present study demonstrates the suitability of road kills as an alternative approach for environmental monitoring and the relevance of nondestructive biomonitoring to evaluate endogenous exposure in hedgehogs and possibly other terrestrial mammals and humans.

A proposed methodology for the definition of background and reference values for trace elements in fluvial sediments.

The Water Framework Directive (WFD, 2000/60/EC) mandates member states to consider trace element background values when establishing environmental quality standards (EQS) for sediments. This study proposes defining the "background" value as the trace element concentration that is consistently present in the unaltered natural environment, and the "reference" value as an upper limit of variation of naturally occurring concentrations, suggestive of anthropogenic enrichment if exceeded. We argue that background and reference values can be computed as the upper limits of the one-sided 95 % confidence interval for the median and for the 90th percentile, respectively. This proposition has been tested in two European river basins with different historical anthropogenic impacts: the Nalón (impacted by mining activities) and the Esva (mostly unpolluted) basins. For 110 bottom sediment samples collected from both pristine (background) and potentially impacted (non-background) locations, 19 elements were analyzed by ICP-MS/ICP-AES. The proposed background and reference values, calculated using the Bootstrap method, demonstrated consistency despite geological differences between the basins. The methodology proved particularly effective in datasets with a limited sample size and highly skewed data distributions. In the Nalón basin, with higher anthropogenic activity, the percentage of samples exceeding reference values was higher than in the Esva basin (e.g., 29 % vs 7 % for As and 11 % vs 0 % for Pb), suggesting the utility of these values in discerning potential impacts of historic mining activities. In the Esva basin, background and reference values were either near or below generic thresholds for good ecological status (LEL, TEL) unlike the Nalón basin, in which reference values for all elements, except three, exceeded these thresholds.

Trace elements in Alaska's ice seals in the 2000s and 2010s.

Ringed (Pusa hispida), bearded (Erignathus barbatus), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals are ice-associated seals that are important subsistence resources for coastal Alaska Native people. These seals are also mid- to upper trophic level Arctic predators and primary prey of polar bears (Ursus maritimus). We analyzed concentrations of 19 trace elements in seal liver, kidney, muscle, and blubber, including arsenic, cadmium, lead, mercury, and vanadium due to their potential toxicity. We also measured monomethyl mercury, the more biologically available and toxic form of mercury, in a subsample of seals. We tested for differences in elemental concentrations by seal sex, age, and two periods, 2003-2007 and 2011-2016, to detect environmental trends, assess seal health, and explore trace elements in seal tissues as indicators of seal diet. Trace element concentrations were within ranges that were similar or below that previously measured for these species throughout their range in the Arctic and subarctic. We found relationships between concentration and seal sex or age, as well as differences between periods, with a notable decline over time in magnesium for bearded seal liver and kidney, and ringed and spotted seal liver. Relative concentrations of methyl mercury and total mercury among the four seal species matched known patterns of piscivory and pelagic feeding. Cadmium concentrations were highest in bearded and ribbon seals, possibly due to greater benthic feeding and consumption of squid, respectively. Tissue trace element concentrations from sick seals collected during the 2011-2016 Northern Alaska Pinnipeds Unusual Mortality Event did not differ from those of healthy subsistence harvested seals. Our analysis of trace elements in four Alaskan ice seal species can inform toxicological risk assessments regarding non-essential elements of concern and assessments of nutritional benefits regarding essential elements for seals and for the people and polar bears that eat them.

Inter-island variability in trace elements and trophic ecology of Brown Booby (Sula leucogaster) in the South Atlantic.

This study investigates essential (Mg, Ca, Fe, Mn, Cu, Zn, Se, Ni) and non-essential (Li, Be, Cr, Rb, Sr, Cs, Cd, Sn, Ba, and Pb) element concentrations and stable isotope (δ13C, δ15N, δ34S) compositions in feathers of Brown Boobies (Sula leucogaster) from three distinct Atlantic islands: the Archipelagos of Saint Peter and Saint Paul (SPSP), Abrolhos, and Cagarras. We aimed to investigate the ecological and environmental factors influencing these seabird populations and assess potential variations in contaminant exposure and dietary habits based on location, sex, and maturity stages. Our finding revealed significant geographical differences in trace element concentrations. The Brown Boobies from Cagarras had higher concentrations (mean±SD, μg g-1) of Fe (29±20) and Mn (0.82±0.82) than those from Abrolhos (Fe: 21±20; Mn: 0.24±0.09) and SPSP (Fe: 15±16; Mn: 0.21±0.06). Tin concentrations were also higher in Cagarras (Sn: 0.02±0.01) than in SPSP (Sn: 0.01±0.01). Our analyses revealed significant differences in Li, Mg, Rb, and Zn concentrations between adults and juveniles. However, there were no sex-related differences in element concentrations within each locality. SIBER analyses revealed distinct dietary differences among the three Brown Boobies populations, with the Cagarras seabirds occupying a higher trophic position compared to the SPSP population. This study highlights the importance of considering different populations to understand contaminant exposure and ecological dynamics in Brown Boobies along the South Atlantic. The Cagarras population shows significantly higher contaminant levels, likely due to proximity to anthropogenic activities. These results highlight the necessity for ongoing monitoring to evaluate long-term effects on the more impacted population and to ensure seabird health and sustainability in the Atlantic Ocean.

Widespread presence of metallic compounds and organic contaminants across Pacific coral reef fish.

Coral reef fishes represent an invaluable source of macro- and micro-nutrients for tropical coastal populations. However, several potentially toxic compounds may jeopardize their contribution to food security. Concentrations of metallic compounds and trace elements (MTEs), and persistent organic pollutants (POPs, including pesticides and polychlorobiphenyls PCBs), totalizing 36 contaminants, were measured in coral reef fish from several Pacific islands. The objective of this study was to describe the spatial distribution of these compounds and contaminants in order to identify potential variables explaining their distribution at a Pacific-wide scale. To achieve this, we applied Boosted Regression Trees to model species-specific and community-level contaminant and inorganic compound concentrations at the scale of the tropical Pacific Ocean. Overall, using 15 easily accessible explanatory variables, we successfully explained between 60 and 87% of the global variation, with fish body size being the most important correlate of MTEs and POPs concentrations in reef fish. Our modeling approach allowed us to estimate and map the distribution of the community-level concentration of 19 contaminants and inorganic compounds at the scale of the equatorial and south Pacific Ocean. Spatial patterns varied significantly depending on the compound, with modeled quantities per 100g of fish flesh generally being higher in the central and southwest Pacific than in the eastern part of the basin. These patterns were influenced by a combination of biological, environmental, anthropogenic and biogeographical variables. Overall, this approach represents an important step toward the estimation of concentrations of the main compounds on the basis of species identity and fishing location. Our results enhance our understanding of the extent of contamination in the Pacific while underscoring the urgent need for long-term and large-scale spatial monitoring of diverse compounds in this region.

The occurrence and persistence of surface water contaminants across different landscapes

Surface water contaminants, including both conventional contaminants (e.g., nutrients, trace elements) and emerging contaminants (e.g., pesticides, pharmaceuticals) are heavily influenced by urban and rural land use practices. The goal of the study was to characterize the influence of watershed land use practices on surface water quality. Specific objectives were to (1) identify and quantify the type and concentration of nutrients, trace elements, pesticides, pharmaceuticals and personal care products in four watersheds and (2) understand potential sources of contamination based on the watershed's land cover and land use characteristics (i.e., oil and gas, urban, mining, agriculture). Monthly polar organic chemical integrative samples and water grab samples were collected from March–October 2022. The results showed that surface water quality varied by location, season, and flood condition Specifically, aluminum (mean = 758 μg L−1) and iron (mean = 1130 μg L−1) exceeded chronic aquatic life water quality criteria in the agricultural watershed, while imidacloprid exceeded the chronic criteria limit for freshwater invertebrates in both the urban (mean = 5.96 ng L−1) and agricultural (mean = 4.72 ng L−1) watersheds. Sulfate concentrations (mean = 666 mg L−1) also exceeded ambient water quality criteria in the watershed with a high activity of mining. This study provides important steps for developing a comprehensive understanding of land use impacts on contaminant presence and concentration in surface waters, improved understanding of the implications to non-target species, and necessary water treatment processes to ensure a safe water supply.

Trophic magnification rates of eighteen trace elements in freshwater food webs.

Trace elements play diverse roles in animal physiology ranging from essential micronutrients to potent toxicants. Despite animals accumulating many trace elements through their diets, relationships between trophic positions and biological concentrations of most trace elements remain poorly described. We report trophic transfer rates of Al, As, Ba, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, Ti, Tl, U, V, and Zn from 31 freshwaters located in distinct biogeographic regions. Elemental concentrations and stable nitrogen isotope ratios (proxies for trophic position) were determined in zooplankton, molluscs, insects, and fishes from all sites. Trophic magnification factors (TMFs) were calculated as the mean fraction of each element that transferred from prey to predators at each site. TMFs >1 indicate biomagnification and TMFs <1 indicate biodilution. Mercury was the only biomagnifying element (median TMF=3.77), and selenium neither biomagnified nor biodiluted (median TMF=1.01). All 16 remaining elements biodiluted, with median TMFs ranging from 0.07 (uranium) to 0.60 (thallium). We used a model selection procedure to determine whether intrinsic physical and chemical elemental properties explained differences in TMFs among elements. Elements with high covalent bonding indices (Q) had marginally greater TMFs than elements with low Q values. Based on their high Q values, we recommend investigation into the trophic transfer rates of ten additional trace elements, some of which may biomagnify through some aquatic food webs. The high variability in TMFs within elements suggests that ecological factors are likely more important than intrinsic elemental properties at determining elemental TMFs.

Autumn and winter air phytofiltration - Are plants able to biofilter air during peak pollutant emissions?

Air pollution is highest in winter. The high concentration of particulate matter (PM) and trace elements (TE) after the growing season is influenced by increased pollutant emissions, unfavorable meteorological conditions, and the low efficiency of air phytofiltration. Plants that can remove pollutants from the air during the growing season are leafless in autumn/winter, and therefore unable to capture PM/TE effectively. This study investigated the ability of nine species of leafy evergreen plants to accumulate PM (surface and in-wax PM; PM2.5 and PM10) and TE in autumn and winter. Plant material was harvested in November and December from the park in Wuhan, China. The amount of accumulated pollutants depended on the species. The shrubs (Loropetalum chinense, Pittosporum tobira, Rhododendron simsii) and grass (Ophiopogon japonicus), were more effective at phytofiltration of PM and TE per leaf area unit than the trees. However, to better understand the potential of plants to accumulate PM in relation to a unit of land area, the leaf area index (LAI) has to be considered. Ligustrum lucidum and P. tobira characterized by low LAI, despite having PM deposition comparable to other trees and shrubs, exhibited a markedly reduced efficacy of pollutants accumulation in relation to square metre of land they occupy. In contrast to the TE concentration in winter, PM deposition on plants did not always increase after the autumn, probably due to the park's low density of vegetation, PM resuspension by wind, and a decrease in the plants' physiological activity. Seasonal variations in pollutants accumulation among species were recorded during the autumn/winter. This study reinforces the need for biodiversity and higher-density urban greening to optimize post-growth air phytofiltration. A holistic, year-round air pollution mitigation strategy should be provided by incorporating more diverse evergreen plant species with complementary phytofiltering properties.

Tracing metals in Mediterranean and Atlantic Sardina pilchardus: Unveiling impacts on food safety.

This study evaluates the concentration of metals and trace elements (Al, Cd, Cu, Fe, Li, Pb, Zn) in the muscle tissue of Sardina pilchardus from three northeast Atlantic localities (Lisbon, Canary Islands, Rabat) and two western Mediterranean sites (Málaga, Cartagena) to assess food safety and environmental impact. A total of 100 sardines were sampled between January and June 2019, with specimens collected, homogenized by size and weight, and analyzed for metal content using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Results show significant geographical variation in metal concentrations, with Cartagena exhibiting the highest levels due to industrial and urban activities, while the Canary Islands had the lowest, likely influenced by geographical isolation and stringent environmental regulations. Intermediate levels were observed in Lisbon, Rabat, and Málaga, with Rabat ranking second highest. Importantly, none of the samples exceeded EU safety limits for lead (0.3mg/kg) or cadmium (0.25mg/kg), confirming their suitability for human consumption regarding metal content. These findings emphasize the role of local environmental and industrial factors in influencing metal bioaccumulation in marine ecosystems. Genetic and ecological dynamics, such as the Almería-Oran Front and the Canary Islands' isolation, likely contribute to these patterns. The study underscores the importance of continuous monitoring to safeguard food safety and marine ecosystem health. Despite Cartagena's elevated contamination levels, which pose a higher potential risk if sardine consumption is frequent, sardines from all locations remain within safety limits. Moving forward, research should prioritize long-term monitoring and explore genetic and ecological factors influencing bioaccumulation trends, contributing to sustainable management and effective pollution control measures. This highlights the interconnectedness of environmental health and human dietary safety, emphasizing the need for a proactive approach to monitoring marine contamination.

Non-lethal sampling of phalanges for heavy metal bioaccumulation in Pelophylax nigromaculatus from historical mercury mining areas in Southwestern China

The Wanshan mercury mining area (WMMA) in Guizhou Province, China, has been identified as a region at high ecological risk owing to heavy metal contamination. This study employed non-lethal sampling methods, using the phalanges of Pelophylax nigromaculatus in the WMMA as analytical material. Ten heavy metal (metalloid) elements were selected for analysis, including Hg, Cr, Mn, Ni, Cu, Zn, Cd, Pb, As, and Se. These elements were measured using inductively coupled plasma mass spectrometry (ICP-MS), while Hg was determined using atomic fluorescence spectrometry (AFS). The bioaccumulation characteristics of heavy metals in P. nigromaculatus were analyzed through the bioaccumulation factor (BAF), and the extent of heavy metal pollution along with potential ecological risk was assessed using the potential ecological risk index (RI). The scaled mass index (SMI) was utilized to evaluate the body condition of P. nigromaculatus. Additionally, a combination of Spearman correlation analysis and non-negative matrix factorization (NMF) was employed to identify the sources and contributions of heavy metal elements. The results indicated that the distribution characteristics of heavy metal elements in the phalanges of P. nigromaculatus varied. Except for Pb, the concentrations of essential trace elements were significantly higher than those of non-essential elements. The bioaccumulation potential of P. nigromaculatus for heavy metal elements in the soil was found to be low, whereas the exposure risk from heavy metals in the water was high. The presence of heavy metal elements poses a significant potential ecological risk to P. nigromaculatus, with Hg, Cd, and As identified as the primary contributors to this risk. The environmental sources of heavy metals were identified as follows: Hg, Pb, Zn, and Se mainly originated from mining pollution sources; As and Cd primarily came from atmospheric pollution sources; Cr and Cu were mainly from natural activities sources; and Mn and Ni had multiple composite sources. Although heavy metal pollution negatively impacted the physical condition of P. nigromaculatus, no significant differences in SMI were observed across different regions. We believe that this is primarily attributable to the high levels of Se, which effectively mitigate the toxicity of heavy metals. The study demonstrated that using frog phalanges for heavy metal bioaccumulation analysis and SMI for physical condition assessment are simple, safe, and non-lethal methods, which can serve as useful indicators of environmental pollution and help trace the sources of environmental pollutants.

The influence of cultivation technology on the content of trace elements in pea plants

The purpose of the research is to assess the level of accumulation of copper, zinc, manganese, cobalt and iron by peas using various cultivation technologies. The work was carried out in 2020–2023 on chernozem typical of the Kursk region. Four agrotechnologies of pea cultivation were studied, based on various methods of basic tillage: traditional, differentiated, minimal, direct sowing. The copper content was highest in the roots with minimal technology (13.37 mg/kg), in straw and grain – with direct sowing (6.16 and 5.74 mg/kg). The maximum amount of zinc in the roots was provided by traditional technology and direct sowing (34.10 and 34.63 mg/kg), in straw – differentiated (13.35 mg/kg), in grain ‒ traditional and differentiated (28.06 and 28.86 mg/kg) technologies. The highest content of manganese in the roots was with differentiated technology (369.95 mg/kg), in straw and grain – with direct sowing (68.11 and 55.30 mg/kg). The maximum amount of cobalt in the roots was observed with direct sowing (7.05 mg/kg), in straw – with differentiated technology (4.44 mg/kg), in grain – with minimal technology and direct sowing (3.51 mg/kg). The iron content in the roots did not differ significantly with traditional, minimal technologies and direct sowing, and with differentiated, it decreased by 16.3…26.0 mg/kg. In pea straw, the lowest amount of iron was found with differentiated technology (270.27 mg/kg). During direct sowing, the highest concentration of iron in the grain was noted (135.7 mg /kg). The coefficient of biological accumulation of trace elements by grain was higher than by roots and straw. The highest values of this grain index for copper (24.33), manganese (27.68), cobalt (12.14) and iron (9.19) were noted with direct sowing, and for zinc – with differentiated (28.36) and minimal (28.31) technologies.

Environmental risk assessment of the surface sediments based on trace elements analysis from the largest freshwater lake in the southern slope of the Himalaya, Nepal.

Freshwater ecosystems, including high-altitude lakes, can be affected by trace metal pollution derived from a mix of natural sources and anthropogenic activities. These pollutants often collect in surface sediments, with notable concentrations in the deeper areas of lakes. To evaluate the environmental risk associated with metal contaminated sediment in Rara Lake, southern Himalaya, surface sediment samples were systematically collected in November 2018, with a subsequent specific emphasis on determinations of trace element concentrations. Subsequent analysis revealed nine elements exhibiting a descending mean concentrations order: iron (Fe) > manganese (Mn) > chromium (Cr) > rubidium (Rb) > nickel (Ni) > strontium (Sr) > cobalt (Co) > copper (Cu) > cadmium (Cd), of 7205.55mgkg-1, 2290.34mgkg-1, 176.29mgkg-1, 153.78mgkg-1, 51.86mgkg-1, 44.61mgkg-1, 38.89mgkg-1, 29.11mgkg-1, and 0.10mgkg-1, respectively. Comparisons to sediment quality guidelines highlight that Mn, Cr, Cu, and Cd as significant threats to the aquatic ecosystem in Rara Lake. To assess the impact of metal pollution, enrichment factor (EF), geo-accumulation index (Igeo), pollution load index (PLI), and contamination factor (CF) were computed. All metals (except Cd) had Igeo value exceeding 5, displaying strong contamination. EF values for Mn, Cr, Co, and Ni metals were > 10, indicating severe effects of anthropogenic influences. CF and PLI values also indicated significant pollution for most of the investigated sites. Elevated trace element concentrations have the potential to adversely affect water, sediment, and aquatic life, also potentially impacting nutrient cycling and microbial activity. This study enhances our understanding of the metal compositions within Rara Lake sediments and provides a basis for more effective lake management and pollution control strategies. Urgent action by regional governing bodies is crucial to address the early stages of metals pollution, including identification and controlling of pollution sources, by appropriate regulations, optimizing industrial practices, and remediating existing pollution to prevent further contamination and protect the lake ecosystem.

Геохимия везувиана из контактово-метасоматических пород минеральных копей Южного Урала

A mineralogical and geochemical study of vesuvianite from mineral aggregates sampled in the Zelentsovskaya, Nikolaje-Maximilianovskaya, Akhmatovskaya and Shishimskaya mines located at the outer contact of the Kusa-Kopan intrusion of the Southern Urals was carried out. Vesuvianite from the silicate-carbonate rock (Zelentsovskaya mine) is significantly enriched in Fe, V, Cr, Y, Zr, Th, Sn, and Cl, and the REE distribution spectrum it is close to that for garnets from the same rocks. Vesuvianite from calcite-garnet vein in chlorite schist (Nikolaje-Maximilianovskaya mine) is enriched in U, and REE distribution spectra there are significantly differentiated, which is explained by the removal of incompatible elements. Vesuvianite from rodingites (Akhmatovskaya mine) is enriched in Mn, Ni, Zn, Sr, Nb and volatile components (F and Cl), and the REE distribution spectra are conformal to each other, which testifies to a stable geochemical equilibrium in the rock. Vesuvianite from the skarn (Shishimskaya mine) is in paragenesis with garnet, so it is significantly enriched in Al, LREE and water, and depleted in impurity elements. The content of trace and rare-earth elements in all vesuvianites shows signs of contact metasomatism: the peculiarities of their composition depend on the mineral paragenesis and the influence of the frame rocks — gabbroids of the Kusa-Kopan intrusive complex.

Origin of the Miaoling Gold Deposit, Xiong’ershan District, China: Findings Based on the Trace Element Characteristics and Sulfur Isotope Compositions of Pyrite

The Xiong’ershan district is situated on the southern margin of the North China Craton (NCC) and located within the Qinling–Dabieshan Orogen’s orogenic zone. It is adjacent to the XiaoQinling mining district and exhibits very favorable geological conditions for mineralization, as the district contains numerous gold deposits, positioning it as one of the key gold-producing areas of China. The Miaoling gold deposit is a hydrothermal deposit and is controlled by the Mesozoic nearly NS-trending fault. The ore bodies are hosted in the Mesoproterozoic Xiong’er Group of the Changcheng System of volcanic rocks, with reserves reaching large-scale levels. Pyrite is the main gold-bearing mineral and can be classified into four generations: early-stage fine- to medium-grained euhedral to subhedral cubic pyrite (Py1); medium- to coarse-grained euhedral to subhedral cubic granular pyrite in quartz veins (Py2a); fine-grained subhedral to anhedral disseminated pyrite in altered rocks (Py2b); and late-stage anhedral granular and fine-veinlet pyrite in later quartz veins (Py3). Through in situ trace element analysis of the pyrite using LA-ICP-MS, a positive correlation between Au and As was observed during the main mineralization stage; gold mainly exists as a solid solution within the pyrite lattice, and the ablation signal curve reflecting the intensity of trace element signals showed that gold also occurs as micron-scale mineral inclusions. The trace element content suggested a gradual increase in oxygen fugacity from Stage 1 to Stage 2, followed by a decrease from Stage 2 to Stage 3. The Co/Ni values in the pyrite (0.56 to 62.02, with an average of 12.34) exhibited characteristics of magmatic hydrothermal pyrite. The in situ sulfur isotope analysis of the pyrite using LA-MC-ICP-MS showed δ34S values of 4.24‰ for Stage 1, −6.63‰ to −13.79‰ for Stage 2, and −4.31‰ to −5.15‰ for Stage 3. Considering sulfur isotope fractionation, the δ34S value of the hydrothermal fluid during the main mineralization stage was calculated to be between 0.31‰ and 2.68‰.

Influence of Newborns’ Sex on Minor and Trace Element Concentrations in Human Milk During Early Lactation

Influence of Newborns’ Sex on Minor and Trace Element Concentrations in Human Milk During Early Lactation