The mandibles are among the most important appendages of insects\' mouthparts. Their morpho-functional organization is correlated with the variation in dietary preferences. In this study, we investigated the ultrastructural organization and metal composition of the mandibles of two ladybird species with different dietary habits: Harmonia axyridis (an entomophagous species) and Subcoccinella vigintiquatuorpunctata (a phytophagous species). The ultrastructural organization was studied using Scanning and Transmission Electron Microscopy, whereas the metal composition was investigated using Energy-Dispersive X-ray spectroscopy (EDX). Significant differences were observed in the general organization and metal enrichment pattern between the two species. The mandibles of H. axyridis are large and present a molar part with two teeth, with the apical one showing a bifid apex. In contrast, S. vigintiquatuorpunctata exhibited a molar region with several teeth on its apical part. The study revealed significant differences in metal content between the teeth and the prostheca of H. axyridis. Mn was the most abundant element in teeth, whereas Cl was more abundant in the prostheca. In the case of S. vigintiquatuorpunctata, Si was the most abundant element in the prostheca, while Mn was more present in the teeth. A comparison between the two species revealed that both teeth and prostheca showed significant variation in the elemental composition. These findings underscore the role of dietary preferences in shaping the structural and metal composition variations in the mandibles of these two ladybird species.

Magnetic iron concentrate (MIC) and nonmagnetic tailings (NT) are obtained from magnetization roasting of iron tailings (IT). MIC containing Pb adversely affects blast furnace ironmaking, while Cu in NT poses leaching risks. This study utilizes fast pyrolysis-suspension magnetization roasting to recover iron from IT. The enrichment of Pb, Cu, and the phase transformation mechanism of Cu in the process of suspension magnetization roasting and magnetic separation were clarified. Results show 96.13 % of Cu in IT is in limonite and 47.23 % of Pb is associated with iron. At 750 °C, with 10 % dosage of biomass pyrolysis and 10 min roasting, Pb, Cu and Fe contents in MIC are 0.96, 2.14 and 3.17 times that of NT. Increasing roasting temperature enhances Cu associated with iron enrichment into the MIC, while oxidation of free copper oxide associated with iron forms magnetic copper ferrite. Increased pyrolyzed biomass leads to over-reduction of magnetite associated with Cu to FeO associated with Cu, promoting magnetic copper ferrite decomposition into FeO and free copper oxide. This research holds significant importance in controlling the quality of MIC and the storage risk of IT, and provides theoretical guidance for the regulation and recovery of valuable metals in subsequent processes.

Black shales are highly enriched in essential elements containing critical information on metallic richness and paleoclimatic imprints during deposition. The Cretaceous period marks the age of Basin formation from which the Mamfe Basin was formed from the Albian to Cenomanian. The purpose of this study is to investigate the geochemical behaviour of the shales in the Mamfe Basin and their paleoclimatic and metallogenic significance. Twenty-five representative shale samples were collected from seven sites outcrops in the Mamfe Basin. The major and trace elements composition in the shale samples were analysed using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In comparison with standard values for metalliferous shales, the shales from the Mamfe Basin are enriched in Boron (B), with only few samples enriched in Li, Rb, Cu, Pb and Zn. The Aluminium module (Alm) and ternary diagram plotted from Al-Fe-Mn shows that all the shales are considered as terrigenous sediments with only 02 samples (08%) falling within the zone of metalliferous sediments. The paleoclimatic characteristics that were inferred from the C-values (0.3-3.1), Sr/Cu (0.6-8.9), Sr/Ba (0.1-2.8), Rb/Sr (0.3-0.9), Fe/Mn (1.8-180), Al/Mg (0.31-31) and Mg/Ca (0.05-16.4) data of the shales in the Mamfe Basin indicate that the climate that existed during source area weathering ranged from a sub humid to a more humid climate with few samples ≤5% displaying arid climate.

Peatlands are unique habitats that function as a carbon (C) sink and an archive of atmospheric metal deposition. Sphagnum mosses are key components of peatlands but can be adversely impacted by air pollution potentially affecting rates of C and metal accumulation in peat. In this study we evaluate how the loss of Sphagnum in peatlands close to a copper (Cu) and nickel (Ni) smelter in Sudbury, Ontario affected C accumulation and metal profiles. The depth of accumulated peat formed during the 100+ year period of smelter activities also increased with distance from the smelter. Concurrently, peat bulk density decreased with distance from the smelter, which resulted in relatively similar average rates of apparent C accumulation (32-46 g/m2/yr). These rates are within the range of published values despite the historically high pollution loadings. Surface peat close to the smelters was greatly enriched in Cu and Ni, and Cu profiles in dated peat cores generally coincide with known pollution histories much better than Ni that increased well before the beginning of smelter activities likely a result of post-deposition mobility in peat cores.

Monitoring and assessment of soil quality are important in mining areas. In this study, indexical, spatiotemporal, and chemometric models were developed to monitor and assess the pollution level and health risk of potentially toxic elements (PTEs) within the Iyamitet-Okurumutet mine province, SE Nigeria. Surface soils were sampled within the mine area and analyzed for pH, cation exchange capacity, organic matter, and PTEs (Pb, Zn, Cd, Mn, Fe, Ba) following standard techniques. It was revealed that the soils are slightly acidic and the enrichment of PTEs except for Cd (4.08 mg/kg-1) was within recommended standards. Contamination factor, enrichment factor, and pollution index suggest that the soils are moderately polluted. Geospatial maps and ecological risk indices revealed that higher ecological risk imprints seem to increase towards the south-eastern parts of the area. Chemometric analysis revealed that PTE enrichment in the soil is majorly influenced by anthropogenic activities. Further, bioavailability/bioaccessibility risk assessment index (BRAI) and health risk assessment models were developed to quantify the bioavailable/human bioaccessible portion of elements in soils and the associated health risks. The BRAI ranged from high (3 ≥ 5) to very high (> 5) risk of human bioaccessibility; hence, greater amount of PTEs will be bioaccessible for absorption into the human gastrointestinal system than they would for plants uptake. The hazard index and lifetime cancer risk (LCR) revealed that most of the samples present high chronic cancer risks from dermal contact and ingestion for children and adults. The LCR values ranged between 1.0E-6 and 1.0E - 04, with the children population showing greater vulnerability to cancer risks.

Biota of coastal estuarine habitats of tropics and subtropics are extremely vulnerable. In the study, we have investigated the role of rhizosphere process in bio-accumulation of heavy metals in fine nutritive roots of riparian mangroves at eleven sampling locations of river Hooghly. The rhizospheric sediment of river Hooghly was accumulating HMs due to the presence of organic content and anthropogenic inputs. The mean EF (2.03-8.3), Igeo (-2.27-0.71), and CF (0.62-2.53) values signifies the enrichment of HMs in sediment fine fraction (<62.5 μm) whereas, the mean PLI (0.83 to 1.18) indicates gradual environmental degradation of river Hooghly. Low BCF observed in the river Hooghly might be due to barrier to hypodermal structures and/or any prevailing mechanism of saturation of HMs. However, BCF > 1 for Al, Cu, Cr, Mn, and Zn, signifies the phyto-remediation potential of riparian mangroves to mitigate amplified global anthropogenic environmental changes.

Since 1997, sediment metal concentrations have been monitored in the Alberta Oil Sands Region (AOSR) of the Lower Athabasca River by the Regional Aquatics Monitoring Program (RAMP; 1997-2002), the Joint Oil Sands Monitoring Program (JOSM; 2012-2014), and the Oil Sands Monitoring Program (OSM; 2015-present). However, it has remained difficult to differentiate industrial sources from natural sources and quantify the extent of pollution due to inadequate knowledge of predevelopment reference conditions. Here, baselines were constructed using predevelopment (i.e., pre-1967) sediment concentrations of US EPA priority pollutants (Be, Cr, Cu, Ni, Pb) and V, an element elevated in bitumen and associated waste materials, normalized to Al concentration in cores from floodplain and upland lakes within the AOSR to characterize the natural range of variability. The Lower Athabasca River sediment metal monitoring data were examined in the context of the predevelopment baselines. Most metals are below the threshold for minimal enrichment (<1.5x baseline) except for chromium (up to 4.8x) in some RAMP samples. The predevelopment baselines for sediment metal concentrations will be of particular importance as the oil sands industry potentially shifts from a no-release policy to the treatment and release of oil sands process waters directly to the Lower Athabasca River.

In recent decades, anthropogenic activities have resulted in road dust and roadside soil hosted metal(oid)s pollution in the urban environment. In the South-Asian megacity \"Dhaka\", schools are situated in the areas with high population density and high traffic emissions. As the school-going children are the most vulnerable receptor, school premises in Dhaka city represent an important yet overlooked exposure point to contaminated dust and soil. Therefore, the present study investigated the metal(oid)s (Cu, Pb, Zn and As) pollution in dust and soil at school compounds, explored their possible sources and estimated the associated human health risk. This study revealed that dust contained higher concentration of metal(oid)s than soil, and the Azimpur Govt. Girls School & College was identified as the most contaminated site. The enrichment of school dust with Cu, Zn and Pb were strictly related to the dense population and substantial traffic activity in the study areas. Arsenic content in school soil was several folds higher than its concentration in the upper crust. Natural and anthropogenic activities possibly posed a synergistic effect on such high soil As. The multivariate statistics suggested that Cu, Zn and Pb were likely to be originated from traffic-related activities, while Zr, Fe, Ti and Rb from natural sources, and K, Sr and Ca from industrial activities. The assessment of health risk suggested the children as a vulnerable receptor and ingestion was identified as the dominant pathway of dust and soil exposure. The hazard index (HI) values were lower than unity, suggesting no possible non-cancer health risk. Arsenic posed a lifetime carcinogenic risk to the population in the study area through soil ingestion and dermal adsorption.

The study of trace and major elements in the biosphere has traditionally focused on the transition and basic metals; the rare earth (REMs), alkaline earth (AEMs) and alkali metals (AMs) that equally constitute environmental contaminants are rarely considered especially in the tropics. The levels and spatial variation of some REMs, AEMs and AMs in the 0-50-cm layer of agricultural soils of Ikwo in southeastern Nigeria typing a humid tropical environment were studied. Soil sampling was undertaken at five zones namely north, south, east, west and centre (covering over 60% of the land area) in the 2017 dry season. Four soil samples were collected from each of the four cardinal points (with evidence of mining and agricultural activities), and two from the centre (serving as reference zone), totalling 18. Metal concentrations were determined using inductively coupled plasma atomic emission spectroscopy. The metals were grouped into REMs (Ce, La, Sm), AEMs (Ba, Ca, Mg, Sr) and AMs (Cs, K, Na, Rb). All metals increased in concentration from the north, or the south (for Ce and Sm only), towards the centre. Overall, they were reasonably similar in distribution pattern among the five zones. Cationic ratios did not vary markedly, reflecting the greater role of pedogenesis than anthropogenic activities in the area. Nevertheless, their variations showed more K, Ca, Sr and La enrichments over the other metals. Enrichment factor and pollution index of the REMs showed healthy levels of these elements in the soils. The data from this preliminary study may add to the data pool on levels and occurrence of REMs, AEMs and AMs in largely disturbed ecosystems of the humid tropics.

An increasing use of Al and Fe as normalising elements in assessment of anthropogenic change (metal enrichment) in marine environments has prompted the current study. This investigation was facilitated by a unique, large data set comprising total- and size-normalised sedimentary metals data from 41 estuaries (n = 3494) in central New South Wales, Australia. Total sediment Al and Fe concentrations varied substantially in these estuaries, even for samples comprising 100% fine fraction (ff), due to changes in the clay mineral mix and variable clay mineral chemistry. Normalising sedimentary metals to 100% ff produced variable results, however this approach improved markedly when samples with <10% ff was removed. The technique of normalising sedimentary metals by adjusting total Al to 50,000 μg/g considered to represent 100% ff was critically assessed. Results showed that total Al for 100% ff varied between estuaries and the most appropriate Al concentration for normalisation was the intercept value of the trend line in total Al vs ff bivariate plots and the 100% ff axis. It is recommended that, in the absence of size-normalised metals data, this intercept value be used as the normalising Al concentration, which should be determined locally for 100% ff. Iron was also assessed as a normalising element using the same approach and provided similar results, but was less attractive due to diagenetic alteration. The post-extraction normalisation (PEN) method provided valid, normalised metals data capable of estimating enrichment (magnitude of anthropogenic change) in marine environments.