Trace Heavy Metals Research Articles

Proximate Composition, Trace and Macro Element, and Heavy Metal Content of Edible Seaweed Solieria robusta in Tawi-Tawi, Philippines

Solieria robusta is a red seaweed consumed widely by the local population in the southern Philippines. However, current information regarding its proximate composition, trace and macro element, and heavy metal content is lacking. This study marks the first attempt in the Philippines to ascertain the proximate composition, trace and macro element, and heavy metal content of edible seaweed S. robusta. Our findings revealed that S. robusta primarily consists of ash content, measuring 44.30 ± 0.4 g/100 g, followed by carbohydrates at 32.96 ± 0.45 g/100 g. The moisture content of dried S. robusta was 16.91±0.04 g/100 g. The crude protein content of this edible seaweed was determined to be 5.61 ± 0.05 g/100 g, with total fat noted at 0.22 ± 0.01 g/100 g. The average concentration of trace elements (Zn, Fe, Mg, and Cu), macro element (K), and heavy metals (Pb and Cd) followed the order of Zn > Fe > K > Mg > Pb > Cu > Cd. Notably, three essential minerals -Zn, Fe, and K- were present in significant quantities in S. robusta, with concentrations of 219±8.70, 209±5.75, and 9.83±0.22 mg/kg, respectively. However, one trace element, Zn, and one heavy metal, Pb, exceeded the permissible values, and the rest were within the safe limits. This study constitutes a significant contribution to the comprehension of the nutritional profile and mineral composition of S. robusta, emphasizing its potential as a valuable dietary resource.

Nutritional Quality, Amino Acid Profile and Phytochemicals of High Protein-fibre Cookies Produced from Whole Wheat, Orange-fleshed Sweet Potato, Defatted Peanut and Rice Bran Composite Flour

This study evaluated the nutritional qualities of cookies from whole wheat (WW), orange-fleshed sweet potato (OFSP), defatted peanut (DPN) and rice bran (RB) composite flour. The flours (WPRG 1, 2 and 3) were formulated at different ratios (5.00-37.50%) and 100% WW flour (as control). The improved protein (13.54 ̵ 18.91%) and fibre (2.96 ̵ 8.65%) of the cookies depicted the positive inclusion of OFSP, DPN and RB flours. However, the essential minerals were significantly (p≤0.05) high in the composite cookies with no traces of heavy metals. Besides, the hydrophobic amino acids (24.10 ̵ 28.91%) and biological value (74.07 ̵ 89.77%) of the cookies showcased their potential bio-availability in some cardio-disease management. Their phenol (100.28-220.35 mg/100g) and tannin (53.40-76.50 mg/100 g) contents significantly (p≤0.05) enhanced their antioxidative power. The cookies produced from 56.25% WW, 18.75% OFSP, 5% RB and 20% DPN composite flour were mostly preferred by the consumers’ ratings. Finally, the added peanut and rice bran flours showed no significant (p<0.05) effect on the physical properties, acceptability and preference of the cookie samples. Hence, we conclude that it is possible to produce better and high nutritional (protein, fibre, etc.) cookies from whole wheat, OFSP, defatted peanut and rice bran composite flours.

Synergistic utilization of industrial waste red mud and rice husk ash for eco-friendly geopolymer preparation: enhancing strength and mitigating hazardous leaching.

The prolonged stacking of substantial volumes of industrial waste red mud (RM) can have significantly hazardous effects on the environment. In order to address this critical problem, this study proposes the synergistic preparation of geopolymers utilizing RM in conjunction with another industrial waste, rice husk ash (RHA). Geopolymers with varying incorporation of RHA were prepared using sodium hydroxide and sodium silicate composite alkaline activator. The mechanical properties, microstructure, and environmental characteristics of geopolymers were investigated. The incorporation of RHA significantly enhanced the strength of RM-based geopolymers, with the highest strength of 25.40MPa achieved at 40% incorporation. According to XRD patterns and FTIR spectra, C-(A)-S-H and N-(A)-S-H were generated during the geopolymerization, thereby enhancing the strength of geopolymers. From SEM micrographs of geopolymers, it was evident that the geopolymer matrix was constituted by the encapsulation of unreacted inert particles of RM and residual fragments of RHA with C-(A)-S-H and N-(A)-S-H. The leaching levels of trace elements and heavy metals in geopolymers are both below the regulatory thresholds, thereby effectively mitigating the presence of hazardous substances in raw materials. These findings proved that the reuse of RM and RHA for the synergistic preparation of environmentally friendly geopolymers is a promising approach to address the issue of substantial RM stacking.

Unveiling the spatial differentiation drivers of major soil element behavior along traffic network accessibility

Advancements in transportation networks have induced a spatial-temporal convergence effect, accelerating socio-economic elements flow and dismantling the conventional "core-periphery" urbanization gradient. Accessibility of transportation networks emerges as a reliable indicator of urbanization. There has been a growing global and Chinese focus on the various forms of metal pollution in urban soil. This study aims to investigate the driving forces and effects of urbanization factors (Gross Domestic Product (GDP), value added of secondary industries (VA), night light (NL), population density (PD), and road density (Distance)), soil property factors (pH, electrical conductivity (EC), and total organic carbon (TOC)), and topographic factors (elevation (DEM), aspect, and slope) on toxic heavy metal elements (Cd, As, and Hg) and trace elements (Mn, Ti, V) in surface soil (0–20 cm) across varying accessibility levels in the Beijing-Tianjin-Hebei urban agglomeration. Results reveal significant influence of accessibility on Cd and Hg levels (p < 0.05), with higher accessibility areas displaying elevated element concentrations. According to the evaluation results of the single-factor pollution index, Cd and V have the highest pollution exceedance rates (93.18% and 75.76%, respectively). Moran's Index results highlight typical spatial clustering of elements, with hotspots in areas of high accessibility. Urbanization has led to distinct spatial agglomeration patterns in element concentrations and environmental factors. Geographic detector analysis reveal that in low accessibility areas, metal element pollution and distribution are influenced by a combination of complex factors, including soil properties (pH), terrain conditions (DEM), and the urbanization process (VA). In high accessibility areas, toxic heavy metal elements are primarily driven by urbanization factors, largely influenced by transportation activities, industrial development, and population density, while elements Mn, Ti, and V are still influenced by both natural processes and urbanization activities. These findings suggest that urbanization intensifies the impact on potential toxic elements in soil, and that trace elements are increasingly affected by urbanization, warranting further attention.

Heavy Metal Contamination of Medicinal Plants in India – A Perspective

The presence of heavy metals in medicinal plants (MP) is a matter of serious concern as it directly affects human health. In India, the problem is especially significant since the country is a major consumer as well as exporter of medicinal plant-based raw materials and products. Raw material available in the market is often reported to contain traces of heavy metals and these consequently compromise the quality of medicinal plants-based medicinal formulations. In the present study, the reports of heavy metals in MP from India were collated to ascertain the extent of the problem and highlight the source of contamination. The states with the highest number of metals above permissible limits included Chhattisgarh, Maharashtra, Delhi, Kerala, Karnataka, and Uttar Pradesh. The levels of Cd and Cr metals were found to be the highest in Rajasthan, Odisha, Pb in Kerala and Hg, As in the state of Tamil Nadu. Plants growing in areas having mining activities as well as those growing on urban landscapes such as along roadsides or areas having an inflow of industrial effluents or agricultural run-off showed higher metal content than the standard limit. The presence of metals in natural habitats such as the mangroves and low lands of the Himalayan range was also noted. The review provides an insight into the magnitude of the issue, its causes and the possible lacuna that needs to be addressed to mitigate the problem.

Assessing industrial wastewater effluent toxicity using boosting algorithms in machine learning: A case study on ecotoxicity prediction and control strategy development

Trace heavy metals have a tendency to persist in the effluent of industrial wastewater treatment facilities, leading to toxic effects on downstream water bodies. Traditional assessment methods relied on animal testing, but ethical concerns have rendered them unacceptable. An alternative solution is to evaluate wastewater toxicity using trophic-level aquatic organisms as bioassays. However, these bioassay methods involve costly and time-consuming chemical and biological analytical experiments. In this study, an artificial intelligence-powered water quality assessment (AiWA) approach is proposed for predicting industrial effluent ecotoxicity to further enhance the quick and cost-effective ecotoxicity assessment process. Initially, 99 samples were collected from industrial wastewater treatment plants representing 21 different industries in the Republic of Korea. Fourteen parameters were measured, encompassing both physicochemical and ecotoxicological aspects. Boosting algorithms, especially extreme gradient boosting (XGBoost) and adaptive boosting (AdaBoost), were employed for model development. XGBoost outperformed AdaBoost in terms of model performance. Feature selection analysis revealed that conductivity, copper, lead, selenium, pH, and zinc concentrations were the most suitable inputs for training the boosting model. The innovated XGBoost-based AiWA model demonstrated significantly higher performance (i.e., up to 80%) compared to conventional models with an R2 value of exceeding 0.94 and root mean square error of 3.5 toxicity unit for predicting the integrated toxicity unit (ITU). Additionally, pH and conductivity emerged as crucial indicators for reflecting ecotoxicity levels. Specially, this case study indicated that non-toxic/directly dischargeable levels (TU ≤ 1) were achieved when the pH ranged from 6.8 to 8.4 and the conductivity remained below 1651 μS/cm. These findings are expected to facilitate rapid and cost-effective detection of heavy metal ecotoxicity in industrial wastewater effluents, aiding decision-making in wastewater management.

Adsorption of trace heavy metals through organic compounds enriched biochar using isotherm adsorption and kinetic models

Trace heavy metals such as copper and nickel, when exceeds a certain level, cause detrimental effects on the ecosystem. The current study examined the potential of organic compounds enriched rice husk biochar (OCEB's) to remove the trace heavy metals from an aqueous solution in four steps. In 1st step, biochar’ physical and chemical properties were analyzed through scanning electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR). In the 2nd step, two biochar vis-a-vis glycine, alanine enriched biochar (GBC, ABC) was selected based on their adsorption capacity of four different metals Cr, Cu, Ni and Pb (chromium, copper, nickel, and lead). These two adsorbents (GBC, ABC) were further used to evaluate the best interaction of biochar for metal immobilization based on varying concentrations and times. Langmuir isotherm model suggested that the adsorption of Ni and Cu on the adsorbent surface supported the monolayer sorption. The qmax value of GBC for Cu removal increased by 90% compared to SBC (Simple rice husk biochar). The interaction of Cu and Ni with GBC and ABC was chemical, and 10 different time intervals were studied using pseud first and second-order kinetics models. The current study has supported the pseudo second-order kinetic model, which exhibited that the sorption of Ni and Cu occurred due to the chemical processes. The % removal efficiency with GBC was enhanced by 21% and 30% for Cu and Ni, respectively compared to the SBC. It was also noticed that GBC was 21% more efficient for % removal efficiency than the CBC. The study's findings supported that organic compound enriched rice husk biochar (GBC and ABC) is better than SBC for immobilizing the trace heavy metals from an aqueous solution.

Petrology and Petrochemistry of Basement Rocks in Ila Orangun Area, Southwestern Nigeria

From field studies, six (6) lithological units were identified to be common around the study area which includes quartzites, granites, granite gneiss, porphyritic granites, amphibolite and pegmatites. The results of petrographical analyses show the mineral assemblages of the various rock types in the area which include quartzites as containing quartz, biotite, muscovite and myrmekite. Granite gneiss contains quartz, biotite, orthoclase, myrmekite, microcline, nepheline, hornblende and plagioclase. Pegmatite contains quartz, myrmekite, plagioclase, hornblende, microcline and muscovites. Porphyritic granites were observed to contain quartz, biotite, microcline, orthoclase and tourmaline. Granite contains quartz, biotite, hornblende, plagioclase and orthoclase while Amphibolite schist contains quartz, biotite, hornblende and muscovites. For the purpose of this study twenty (20) pulverized rock samples were taken to the laboratory for geochemical analysis with their results used in the classification as well as suggest the geochemical attributes of the rocks. Geochemical results obtained and interpreted using various geochemical plots or discrimination plots all classified the rocks in the area as belonging to both the peralkaline metaluminous and peraluminous types. Results for the major oxides ratios produced for Na2O/K2O, Al2O3/Na2O + CaO + K2O and Na2O + CaO + K2O/Al2O3 show the excess of alumina, Al2O3 over the alkaline Na2O +CaO +K2O thus suggesting peraluminous rocks. While the excess of the alkali over the alumina suggests the peralkaline metaluminous rock type. The results of correlation coefficient show a perfect strong positive correlation which shows that they are of same geogenic sources while negative correlation coefficient values indicate a perfect weak negative correlation suggesting that they are of heterogeneous geogenic sources. The result of the factor analysis show the elemental association of the trace elements and heavy metals represented as variables in the statistical analysis. Hence, establishing the elemental association of Component 1 as consisting of Ag-As-Ba-Cd-Co, Component 2 as Cr-Cu-Ni, Component 3 as Pb-Rb, Component 4 as Zn-Fe-V and Component 5 as U-Mn. Component 1 suggest the possibilities of sulphide and gold mineralization. Component 2 suggesting pathfinder elements while Components 3, 4 and 5 suggest weathered or dispersed elements. Hence, the occurrence of heavy metallic minerals in the rocks will serve huge economic significance with focus on the pegmatites in the area.

Goat hair as a bioindicator of environmental contaminants and adrenal activation during vertical transhumance.

Autochthonous breeds of livestock are considered a pivotal genetic resource for agriculture, rural development, and food and nutrition security. In the Italian Alps, local livestock breeds are maintained using the traditional alpine farming system based on vertical transhumance, with the use of alpine pastures from late spring to autumn and indoor housing with a hay-based diet for the remaining part of the year. Because of their tight link with the territory of origin, local breeds could be used to biomonitor environmental contaminations. Moreover, animal welfare should also be monitored during transhumance in animals, which are exposed to a sudden farming system change and different types of stressors. For these reasons, this investigation hypothesized that the content of trace elements, heavy metals, and cortisol in the hair of goats changes during vertical transhumance, possibly reflecting different dietary contents and activity of the hypothalamic-pituitary-adrenal (HPA) axis. This study aimed to assess the response of an Italian local goat breed to the change from indoor housing to alpine pasture in summer in terms of hair concentrations of (i) trace elements and heavy metals and (ii) cortisol. The regrown hair of Frisa goats was monthly collected for 2 consecutive years (n = 10 for heavy metals and trace elements and n = 6 for cortisol in 2021, n = 17 for both analyses in 2022), once before vertical transhumance and twice after that event. Hair was then analyzed for trace elements, heavy metals, and cortisol by inductively coupled plasma-optical emission spectrophotometer (ICP-OES) and enzyme immunoassay (EIA), respectively. Data were analyzed by multilevel models. The results showed an increase in As content during alpine pasture (p < 0.01), probably reflecting the soil and water As contents of the grazing area, while Mg, Zn, and Al (p < 0.01) followed the opposite trend, decreasing in the second month after vertical transhumance. Hair cortisol concentrations increased during 2 months of alpine pasture (p < 0.001), indicating an increase in the activation of the HPA axis, in agreement with previous studies. Future investigations can consider a longer study period and the development of ad hoc animal welfare indicators.

Analysis of persistent organic pollutants and heavy metals in mysticetes from the United Arab Emirates

Chemical pollution is a major threat that can increase the mortality and lower the reproductive success of cetaceans. In this study we assess, for the first time, the level of contamination of selected priority pollutants consisting of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals in whales found stranded in the United Arab Emirates. The samples included five Bryde’s whales (Balaenoptera edeni) and one humpback whale (Megaptera novaeangliae) from the Arabian Gulf and one blue whale (Balaenoptera musculus) from the Gulf of Oman. None of the 18 OCPs tested for were detected. Of the 20 PCB congeners tested for, only one was detected in two (40%) Bryde’s whales.The concentrations of trace elements and heavy metals were lower than reported in baleen whales from the southern hemisphere. PAHs, the predominant pollutants in this study, were detected in the tissues of all examined specimens. The predominance of low molecular weight PAHs over high molecular weight PAHs suggests that PAH exposure may have been primarily from petrogenic sources. The amputation of the tail fluke in one case and bruising of a second whale suggest trauma and marine debris entanglement may have contributed to death in at least two cases. We observed no evidence of marine debris ingestion when such examinations were possible

Development of lycopene-based whole-cell biosensors for the visual detection of trace explosives and heavy metals

Residual explosives in conflicting zones have caused irreversible damage to human safety and the environment. Whole-cell biosensors can to detect remnants of buried explosives, such as 2,4-dinitrotoluene (DNT), a stable and highly volatile compound in explosives. However, all the reported whole-cell biosensors utilize fluorescence or luminescence as the biological markers, making their detection difficult in real minefields. Here, we presented a lycopene-based whole-cell biosensor in Escherichia coli to output visible signals in response to DNT, which can help in the visual detection of buried explosives. To construct the whole-cell biosensor, the DNT-responsive promoter yqjF was used as the sensing element, and the lycopene synthetic gene cassette crtEBI was served as the reporting element. Then, the metabolic flux for lycopene production was enhanced to improve the output signal of the whole-cell biosensor, and a terminator was utilized to reduce the background interference. The optimized biosensor LSZ05 could perceive at least 1 mg/L DNT. The DNT-specificity and robust performance of the biosensor under different environmental factors were confirmed. Our results showed that converting the biosensor into a lyophilized powder was an effective storage method. The biosensor LSZ05 could effectively detect DNT in two kinds of soil samples. The lycopene-based whole-cell biosensor could also be used to visually detect heavy metals. Our findings laid the foundation for visually detecting buried explosives in minefields, which was a valuable supplement to the reported biosensors. The methods used for optimizing the lycopene-based whole-cell biosensor, including the improvement of the output signal and reduction of background interference, were quite effective.

Sensitive sensing of Hg(II) based on lattice B and surface F co-doped CeO2: Synergies of catalysis and adsorption brought by doping site engineering

Transition metal oxides are widely used in the detection of heavy metal ions (HMIs), and the co-doping strategy that introducing a variety of different dopant atoms to modify them can obtain a better detection performance. However, there is very little research on the co-doped transition metal oxides by non-metallic elements for electrochemical detection. Herein, boron (B) and fluorine (F) co-doped CeO2 nanomaterial (BFC) is constructed to serve as the electrochemically sensitive interface for the detection of Hg(II). B and F affect the sensitivity of CeO2 to HMIs when they were introduced at different doping sites. Through a variety of characterization, it is proved that B is successfully doped into the lattice and F is doped on the surface of the material. Through the improvement of the catalytic properties and adsorption capacity of CeO2 by different doping sites, this B and F co-doped CeO2 exhibits excellent square wave anodic stripping voltammetry (SWASV) current responses to Hg(II). Both the high sensitivity of 906.99 μA μM−1 cm−2 and the low limit of detection (LOD) of 0.006 μM are satisfactory. Besides, this BFC glassy carbon electrode (GCE) also has good anti-interference property, which has been successfully used in the detection of Hg(II) in actual water. This discovery provides a useful strategy for designing a variety of non-metallic co-doped transition metal oxides to construct trace heavy metal ion-sensitive interfaces.

Analysis and detection of metals in synthetic food colors of sweets by TLC, FTIR and AAS

: To determine the presence of heavy metals (Pb,Cd,Co and Ni) in food colors using qualitative and quantitative methods.: Qualitatively asses food color sample purity through TLC. Quantitatively analyze heavy metal content by AAS and identify functional groups by FTIR.: Food adulteration is a global public health concern, with synthetic food colors often used, including non permitted variants. Study aimed to address this issue by analyzing 15 samples from local markets for heavy metal presence in food colors.: 15 samples collected from local markets including sweets, sweet drops, juices and gelatin, standard food color samples. Chemicals used Butanol,GAA, kbr,D/W. TLC chamber, FTIR, AAS equipment were used along with standards of Pb, Cd,Co and Ni.: TLC analysis revealed synthetic food colors in most samples FTIR identified functional groups in Samples and AAS detected metal presence in 2 out of 15 samples.: In summary, the study revealed that many local market food color samples contain synthetic colors and traces of harmful heavy metals like cadmium and Cobalt.

Highly efficient removal of trace heavy metals by high surface area ordered dithiocarbamate-functionalized magnetic mesoporous silica.

The study describes synthesizing and characterizing a novel dithiocarbamate-functionalized magnetic nanocomposite. This nanocomposite exhibits several desirable properties, including a large pore diameter of 2.55 nm, a high surface area of 1149 m2/g, and excellent capturing capabilities. The synthesis process involves the preparation of highly porous magnetic nanocomposites, followed by functionalization with dithiocarbamate functional groups through a reaction with carbon disulfide and amine. The synthesized nanocomposite was thoroughly characterized using various techniques, including X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The performance of the mesoporous nanocomposite as an adsorbent for removing Pb(II), Cd(II), and Cu(II) cations from contaminated water was evaluated. The study finds that the maximum removal efficiency for Pb(II), Cd(II), and Cu(II) cations is achieved at pH values above 4. The optimal contact time for achieving 100% removal efficiency of the mentioned cations ranged between 60 and 120 min. Within this time range, the adsorbent exhibited efficient capture of the heavy metal cations from contaminated water. Additionally, the appropriate amount of adsorbent required for complete elimination of the heavy metal cations is determined. For Cd(II), the optimal dosage was found to be 50 mg of the adsorbent. For Cu(II), the optimal dosage was determined to be 40 mg. Finally, for Pb(II), the optimal dosage was 30 mg. The adsorbent's regeneration capability was demonstrated, showing that it could be reused for five consecutive runs.

Otolith microchemistry of freshwater indigenous minor carp (Bangana dero) as a biomonitoring tool to trace heavy metals in River Sutlej, Ropar Wetland (Ramsar site), Punjab, India.

The elemental composition of the fish otolith may represent a permanent record of the environmental condition the fish inhabited. Fish otolith grows incrementally from the core to a marginal region that acts as a repository of trace metal signatures. The present study explores the potential application of otolith microchemistry of the benthopelagic indigenous minor carp Bangana dero sampled from the Ropar wetland on River Sutlej, Punjab. The concentration of sixteen metals was evaluated in the otolith (n = 42) and water (n = 48) for the post-monsoon and pre-monsoon season from 2020 to 2022 using inductively coupled plasma mass spectrometry (ICP-MS) followed by element detection in the core and marginal region of whole otolith, using energy-dispersive mass spectroscopy (EDS). All the heavy metals exhibited an increase in metal concentrations in fish otolith than water during the post-monsoon season. By indices approach, the otolith was found to have a high bioaccumulation factor for Se in the post-monsoon and Hg in the pre-monsoon. Certain trace metals like As and Hg exhibited fluctuations in their core and marginal region. Thus, trace metal patterns in the otolith could act as a potential tool for monitoring the seasonal changes of metals in water bodies. The EFHg, EFSe and EFAs in the fish otolith predicted its anthropogenic source, while the remaining studied elements showed ambient water origin. Thus, using the otoliths of Bangana dero as a long-term monitoring tool in the future may be helpful for environmental assessments and the reconstruction of historical exposure for safeguarding of water bodies.

Universal Digital Probe Electrometer for Testing Semiconductor Wafers

Non-contact electrical methods are widely used for research and control of semiconductor wafers. The methods are usually based on surface potential measurement (CPD) in combination with illumination and/or deposition of charges on the sample using a corona discharge, and are also based on the measurement of surface photo-emf. By photo-EMF (SPV) it is possible to determine the lifetime of minor charge carriers, their diffusion length and detect traces of heavy metals on the surface. In addition, using photo-EMF it is possible to determine the surface resistance of the plate, some parameters of the dielectric layer on the surface and barrier photo-EMF (JPV). Electrical performance results reflect the influence of near-surface characteristics on the final performance of devices. The aim of the work was to develop a universal digital probe electrometer that implements various non-contact electrical methods for analyzing semiconductor wafers, in which the change in operating modes and configuration, transmission of the received data, remote testing and calibration are carried out via digital local control channels. This paper describes a universal digital probe electrometer developed by the authors, which implements the above-described non-contact electrical methods for analyzing semiconductor wafers (CPD, SPV and JPV), in which the change in operating modes and configuration, transmission of the received data, remote testing and calibration are carried out via digital local control channels. Due to their high speed, electrical characterization methods are suitable for inspecting semiconductor wafers during production. The results of testing the developed probe electrometer in CPD, SPV and JPV modes are presented, which reflect the effectiveness of the proposed approaches.

Evaluation of Monochromatic Excitation X-ray Fluorescence Spectrometry for Rapid Thallium Detection in Biological Samples Using Animal Models.

Monochromatic excitation X-ray fluorescence (ME-XRF) spectrometry is a novel technique for trace element analysis, characterized by its simplicity, rapidity, and low cost. The objective of this study was to evaluate the applicability of ME-XRF technique for the measurement of thallium in biological samples. Acute and subacute thallium poisoning experiments were conducted to simulate various scenarios, with blood, urine, and 10 distinct organs collected. Detection was initially performed using ME-XRF technique, followed by validation with inductively coupled plasma mass spectrometry (ICP-MS). Excellent agreement between ME-XRF and ICP-MS values was demonstrated by means of paired sample t-tests and intraclass correlation coefficients. Subsequently, the practical implementation of the proposed technique was demonstrated through an actual case study. In conclusion, this study validates ME-XRF as a suitable alternative to ICP-MS for the measurement of trace heavy metals in biological samples. These efforts promote the development of simpler and faster techniques for heavy metal detection, thereby presenting novel avenues for the prevention and diagnosis of heavy metal poisoning.

The transformation of heavy metal speciation during rapid high-temperature aerobic fermentation of food waste and their potential mechanisms

In this study, the content changes of multiple trace heavy metals (HMs) in food waste using a new rapid high-temperature aerobic fermentation (RTAF) technology and their relationships with different physicochemical factors were researched. The results indicated that the content of HMs in the decomposed products met the industry standards for organic fertilizers (NY/T525-2021, China). Physicochemical factors played an important role in controlling the changes in HM content. The component evolution of dissolved organic matter was studied, and its influences on the transformation of HM speciation showed that the RTAF process converted proteins into humus-like substances. Redundancy analysis revealed that the main factors driving the speciation transformation of HMs were tyrosine-like substances or microbial-derived humus (C3), molecular weight of dissolved organic matter (SUVA254) and humification degree (E250/E365). The increase in humification degree contributed to passivating HMs. The correlation network analysis results showed that the exchangeable HMs (Exc-HMs) were related to Lactobacillus and Pediococcu. Additionally, the cytoskeleton, coenzyme transport and metabolic function of microorganisms affected the Exc-HM content. These research results can provide a scientific basis for the prevention and control of HM pollution during the treatment of food waste.

Concentration and Distribution of Toxic and Essential Elements in Traditional Rice Varieties of Sri Lanka Grown on an Anuradhapura District Farm.

Toxic heavy metals have been the focus of many investigations into chronic kidney disease of unknown aetiology (CKDu) within Sri Lanka. It has been hypothesised that exposure to nephrotoxic arsenic, cadmium and lead could play a role in the development of CKDu, and these metals have previously been found in unsafe concentrations in Sri Lankan rice. Traditional varieties of Sri Lankan rice remain popular due to their perceived health benefits, but their uptake of trace and toxic heavy metals remained unexplored. Here, we report a one-time, cross-sectional dataset on the concentrations of essential and toxic elements present in eleven samples of polished and unpolished traditional rice varieties, all regularly grown and sold in the Anuradhapura district, a CKDu hotspot. All rice was sourced from the same farm, with the exception of one store bought sample grown on another, unidentified farm. Cadmium concentrations varied significantly between varieties, and potentially unsafe concentrations of cadmium were detected in the store-bought sample (Suwadel, 113±13 μg kg-1). Elemental imaging of the grains revealed lead to be stored mainly in the rice bran, which is removed during polishing, while cadmium was distributed in the edible portion of the grain. Essential elements were generally higher in the traditional rice varieties than those reported for non-traditional varieties and are a potential source of trace elements for nutrient-deficient communities. The concentration of selenium, an element that plays a protective role in the kidneys, was too low to provide the minimum recommended intake. The methods developed in this study could be applied to a more comprehensive study of elemental uptake of rice under controlled growing conditions.

Utilization of Vermicompost Sludge Instead of Peat in Olive Tree Nurseries in the Frame of Circular Economy and Sustainable Development

The survival of newly planted seedlings and their successful development after transplantation, including faster plant growth, improved plant quality, larger production, and the absence of dependence on arable land, is one of the primary goals of horticultural nurseries. Although peat is the most frequently used amendment in commercial potting substrates, exploiting it degrades essential ecosystems like peatlands and uses slowly renewable resources. This study evaluated the growth and nutrition of olive-rooted cuttings when peat was partially or completely replaced with vermicompost, searching for more sustainable methods and recovering urban wastewater treatment sludge sequentially. The progress of the plants’ growth was compared to that of corresponding plants in which commercial peat had been used as substrate. Leachates from every procedure were also examined, and the results revealed that trace element and heavy metal contents were much lower than those deemed hazardous for aquifers and soil. The outcomes indicated that peat might be effectively replaced with vermicompost sludge, promoting plant growth without further fertilizer. Comparatively to olive cuttings grown in peat-based substrates, those grown in compost-based substrates experienced improved nutrition and development. Further, it was found that irrigation doses were significantly reduced in treatments with a significant amount of vermicompost as the water drained more slowly. A technical-economic analysis was being conducted in the meantime, illustrating the financial benefits for a nursery when peat is replaced with vermicomposted sludge.