Low Concentrations Of Heavy Metals Research Articles

Quality nutrition, metal content, and health risks in soy milk products using aluminum and stainless steel cookers

Improper processing of soymilk, such as soybean raw materials, use of well water, and use of cooking vessels, produces soymilk that does not meet SNI standards. These conditions can contaminate soymilk with harmful metals. The purpose of this study was to measure the nutritional quality and metal content of soymilk produced using aluminum and stainless steel cooking vessels. The research was descriptive and was conducted in July 2022. Analytical tests were carried out by comparing the nutritional content in the form of total protein, fat, lactose, and solid non-fat (SNF), and analyzing the heavy metal content. The results showed that the contents of Pb, Cu, and Hg in soy milk processed with stainless steel were lower than those of aluminum, from 11,494 ppm to 2,706 ppm, 114,612 ppm to 10,211 ppm, and 0,372 ppm to 0,012 ppm, respectively. The contents of Zn and As in soymilk with stainless steel were higher than those treated with aluminum, from 884,585 ppm to 73,616 ppm and from 0,107 ppm to 0,079 ppm, respectively. Cooking water also contributed 0,055; 0,044; 0,028, and 0,156 ppm to the heavy metal content of Pb, Cu, Zn, Hg, and As, respectively. In conclusion, the use of stainless steel in soymilk processing resulted in better nutritional quality and lower heavy metal content compared to aluminum.

Properties of dredged material and potential scope of its beneficial use: A case study of the Pussur River in Bangladesh

The Pussur River, an important river in Bangladesh, requires approximately 6 × 106 m3 of sediment to be dredged per year. At present, this dredged material is mainly dumped on the nearby agricultural and fish-cultivation lands, causing a reduction in productive land and producing negative impacts on people's livelihoods. This study aimed to investigate the engineering and environmental properties of the dredged sand of the Pussur River and evaluate the viability of its potential uses in different sectors. Bed sediments from the Pussur River and dredged material from disposal sites were collected, and laboratory investigations were performed. The test results showed that the dredged material of the Pussur River mainly consisted of fine sand with a fineness modulus ranging from 0.58 to 0.72 and could be classified as poorly graded sand according to the Unified Soil Classification System. This sand was also found suitable for land development, with a fair to poor suitability rating. Given the low concentration of heavy metals (at uncontaminated/slightly contaminated levels), the dredged sand might be safely used for land reclamation, landfill cover, and horticultural purposes, or else for other geotechnical applications without further treatment. After washing/leaching, the dredged sand could also be used as a partial replacement for local sand in concrete works. Moreover, there is a possibility of exporting the dredged sand to Singapore and the Maldives as filling material. These findings will help policymakers design dredging projects with a proper spoil management plan accounting for the dredged material's beneficial use.

Determination of Water Quality Indices and Assessment of Heavy Metal Pollution of Drinking Water Sources in Thimphu

Introduction: The well-being of public health is associated with the availability of safe and clean drinking water. Heavy metals, known for their toxicity and potential health risks, are a particular focus of water quality assessments. This study investigates the heavy metal concentrations in five primary drinking water sources of Thimphu city: Motithang, Jungshina, Taba, Dechencholing and Chamgang. Methods: The ten heavy metals, known for their toxicity (Aluminum (Al), Boron (B), Barium (Ba), Cadmium (Cd), Chromium (Cr), Copper (Cu), Manganese (Mn), Nickel (Ni), Lead (Pb), and Zinc (Zn)), were assessed using inductively coupled plasma optical emission spectroscopy (ICP-OES) for precise analysis. The study employed the Heavy Metal Pollution Index (HPI) and the Heavy Metal Evaluation Index (HEI) to evaluate water quality. Results: The test results revealed low heavy metals concentration in the water sources. The HPI and HEI values were also calculated to be low (<15 and <1.24 respectively). Conclusions: The study provides valuable insights into Thimphu’s drinking water quality, indicating a positive status with low heavy metal concentrations

Integrated Management of Industrial Wastewater in the Food Sector

In 2019, a staggering 931 million tons of food went to waste, which is equal to about 17% of all the food available in stores. Dealing with this waste and managing wastewater from various industries will be among the world’s top challenges soon. This is because the global population is expected to grow to around 9 billion people by 2050. Food processing effluent is characterized by valuable material in considerable concentrations, including proteins and lipids with low concentrations of heavy metals and toxicants. Developing an integrated management system for food-processing wastewater should focus on recovering abundant resources, improving the economic value of the process, and mitigating the organic contaminant in the food-processing effluent. This state-of-the-art will review the wastewater management processes of the food processing industry. The latest wastewater treatment processes in different food processing sectors will be reviewed. This review will encompass various physicochemical treatment and recovery techniques, such as precipitation, membrane technology, solvent extraction, foam fractionation, adsorption, and aqueous two-phase systems. Additionally, it will delve into bio-treatment processes that leverage microorganisms and/or enzymes to utilize nutrients found in food-processing wastewater as cost-effective substrates for the production of valuable products. This includes a detailed examination of microalga biomass production within wastewater treatment systems. Finally, the review will put forward future research directions aimed at integrating the principles of the circular economy and developing comprehensive food-processing wastewater management systems.

Acid controlled washing of municipal solid waste incineration fly ash: Extraction of calcium inhibiting heavy metals and reaction kinetics

Washing method has attracted much attention in the research of municipal solid waste incineration (MSWI) fly ash treatment and resource utilization. However, the controlled leaching of heavy metals and the extraction of recyclable calcium in the washing process are still blank. Acid controlled washing was conducted with different acids, concentrations, times and temperatures to extract calcium while inhibiting heavy metals. The mechanism was investigated by reaction kinetics calculation and washed fly ash characterization. The high Ca concentration of 37,420 mg/L while the low heavy metal concentrations of around or <1 mg/L were achieved at 25 °C for 60 min under a liquid-solid ratio (L/S) of 3/1 in 1.5 M HCl. The reaction kinetics of acid controlled washing conformed the layer diffusion control. The results of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS) analysis indicated that the rate-limiting step was the diffusion of ions through the product layer. Simultaneously, the washing solution enriched in Ca, Na and K and the washed fly ash, which met the standard requirements (HJ 1134–2020) for leach toxicity, both had the potential for further resource utilization.

Comprehensive pollution and ecological risk of heavy metals in an industrial region of south-west Bangladesh

Deterioration of water, soil and sediment due to industrial operation is well known. This study aimed to evaluate physicochemical properties of surface water and heavy metals in industrial effluent (n = 13), river water (n = 14), pond water (n = 5), soil (n = 11) and sediment (n = 19) collected from an industrial zone in south-west Bangladesh. Among the physicochemical parameters, pH and dissolved oxygen (DO) indicated relatively higher values in most of the samples than their respective lower guideline values of 6 and 4.5 mg L-1 and showed significant variation across environments. Based on the average concentration, none of the heavy metals in any environment surpassed the guideline values in the study area, except, Cr in both industrial effluent (0.034 ± 0.055 mg L-1) and river water (0.011 ± 0.005 mg L-1), Cd in both soil (1.11 ± 0.47 mg kg−1) and sediment (1.41 ± 1.04 mg kg−1). Possibly, continuous discharge of industrial effluents might increase the heavy metal concentrations in the effluent receiving environment. Concentration of others heavy metals were below the respective guideline values but varied significantly among the environments. Depth-wise variation was negligible which might be dependent on metal chemistry in soil and sediment. A very high pollution and ecological risk were observed for Cd, specifically in soil and sediment. Multivariate statistics showed strong correlation among heavy metals, which indicated considerable contribution from industrial effluent. Industrial operations control physicochemical properties of surface water, but temperature is dependent of meteorological conditions. This study concludes that the lower concentrations of heavy metals than guideline values in environmental samples still pose significant levels of pollution and ecological risks.

Enhancing corrosion resistance in reinforced concrete structures by using innovative eco-friendly composite pigments

This is the first study to look into the use of modified feldspars as anticorrosive pigments in the coatings industry. Herein, novel anticorrosive composite pigments were prepared by the chemical deposition of thin films of different oxides (e.g., zinc oxide and vanadium oxide with doloresite phase) on the surface of feldspar, which comprises 80% of the whole structure. A new vanadium oxide (e.g., doloresite) was chosen due to its IV oxidation state and excellent anticorrosive characteristics. ZnO is also well-known for its high resistance to corrosion. Firstly, the synthesis of the composite pigments was done, and then, they were characterized via XRD, SEM/EDX, XRF, and TGA. The composite pigments were incorporated into solvent-based epoxy coatings to evaluate their anticorrosive performance on reinforced concrete steel. Their corrosion resistances were determined using linear polarization resistivity and electrochemical impedance spectroscopy techniques. The physico-mechanical properties of the dry coats containing the prepared composite pigments were also evaluated. The results revealed that the polarization resistivity (Rpo) of coatings containing Zn/F ranged from 5900 to 3900 Ohm.cm2 and that of V/F ranged from 7077 to 5500 Ohm.cm2, while the resistivity of uncoated rebar was from 1900 to 1300 Ohm.cm2. These results confirm that these novel pigments (e.g., ZnO/feldspar and doloresite/feldspar) could provide high corrosion resistivity for concrete structures that are immersed in chloride-laden environments. These composite pigments will be eco-friendly with a low impact on humans and the environment as they contain very low concentrations of heavy metals, besides their high efficiency and economic feasibility.

Lead and cadmium co-exposure modified PC12 viability and ER stress: study from a 3×3 factorial design.

Although exposure to individual metal does exhibit its toxicity, combined exposures provide a more effective representation of the toxic effects of different heavy metal exposures on public health as well as ecosystems. Furthermore, there are few studies on composite exposure to low concentrations of heavy metals, which is more consistent with real-life exposure. The purpose of this study was to explore the neurotoxicity induced by combined exposure to low concentrations of Lead (Pb) and cadmium (Cd) and the potential interaction of their mixture in vitro. PC12 cells were incubation with the corresponding concentration of cadmium chloride and/or lead acetate. Viability of PC12 cells was measured by CCK8 assay after 12, 24 and 48h incubation. Next, We measured the ROS, mitochondrial membrane potential (MMP) and apoptosis produced by different treated cells using ROS assay kit, JC-1 MMP assay kit and annexin V-FITC/propidium iodide (PI) apoptosis assay kit, respectively. Expression of proteins related to PI3K/AKT and endoplasmic reticulum (ER) stress in PC12 cells were tested by western blotting. Our study was the first to analyze the interaction between Pb and Cd using a 3 × 3 factorial design approach to observe neurotoxicity. The results showed that the combined exposure of them was more cytotoxic than the single metal. The activation of PI3K/AKT signaling pathway and several parameters related to oxidative stress and ER stress were significantly altered in combined exposure to low concentrations of Pb and Cd compared with the Pb or Cd. Regarding apoptosis and ER stress, a synergistic interaction between Pb and Cd was evident. Moreover, evoked ER stress as a mechanism involved in the apoptosis of PC12 cells by the combined exposure to Pb and Cd. The present study provides a theoretical basis used for the toxicological assessment of metal mixtures induced neurotoxicity of concern in terms of public health, and more effective control measures should be taken for the environmental pollution caused by various mixed heavy metals discharged from industry and agriculture.

Predisposing Factors that Promote Prevalence of Heavy Metals Assimilation and Bioaccumulation in Aquatic Medium and amongst Fishes

The degree of heavy metals assimilation and bioaccumulation in fish tissues (muscles, gills, liver, and kidneys), amongst scale-less fishes- Chrysichthys macrotis, Chrysichthys nigrodigitatus, Clarias gariepinus and Heterobranchus longifilis, -scaly fishes- Cynoglossus senegalensis, Oreochromis aureus, O. niloticus, Lutjanus fulgens, Pomadasys rogeri, and Tilapia galilea, water columns and sediments, were investigated. Heavy metals assimilation and bioaccumulation varied among organisms with or without scales, tissue types, and fish location (water column &amp; sediments) and pollution level. Fishes with scales had lower concentrations of heavy metals than scale- less fishes. The scalier the fish, the lower the metal assimilation and bioaccumulation. As expected, trace metals were generally lower in muscles than liver, and kidney. Liver had highest followed by kidney, gills and then muscles. Fish trophic level (water column or sediments) and water pollution levels affected heavy metal concentrations. Concentrations were always more in sediments than water column or tissues. The more polluted the water, the more the assimilation and accumulation of trace metals.

Heavy metals in wetlands of southwestern India: from sediments through invertebrates to migratory shorebirds

Heavy metal pollution in Indian wetlands is rising due to industrial, agricultural and urban development activities. Shorebirds occupy upper trophic levels and are therefore especially vulnerable to heavy metal pollution. We evaluated the concentration of heavy metals (zinc, copper, cobalt, chromium, lead and cadmium) in 22 common species of migrant shorebirds (220 shorebird dropping samples) with diverse foraging behaviors, in their different prey (55 prey samples) and in the sediments (90 sediment samples) in different habitat types (mudflats, mangroves and sand beaches) between 2019 and 2021. Further, we analyzed a total of 10 biofilm samples from mudflats and mangroves. We detected relatively low concentrations of heavy metals in the sediments (Zn concentration range: 9.11–40.91 mg/kg; Cu: 5.74–21.38 mg/kg; Co: 2.00–4.04 mg/kg; Cr: 4.05–41.03 mg/kg; Pb: 1.02–7.19 mg/kg; Cd: 0.56–4.35 mg/kg). However, we measured relatively high concentrations of heavy metals in invertebrate prey species (Zn concentration range: 84.72–224.74 mg/kg; Cu: 26.63–170.36 mg/kg; Co: 13.98–14.42 mg/kg; Cr: 14.78–98.16 mg/kg; Pb: 18.95–157.29 mg/kg; Cd: 9.33–60.56 mg/kg). In addition, we found high concentrations of heavy metals in shorebird droppings (Zn concentration range: 41.33–58.8 mg/kg; Cu: 31.42–52.11 mg/kg; Co: 36.34–55.68 mg/kg; Cr: 52.3–68.21 mg/kg; Pb: 25.94–43.13 mg/kg; Cd: 5.53–16.4 mg/kg). It is evident that concentration of heavy metals increased successively moving from sediment to prey to shorebird species, likely through trophic transfer. The biofilm samples contained very high concentrations of Cr, Pb and Cd (22.64, 28.09 and 18.46 mg/kg respectively) which could be harmful to biofilm grazing shorebirds. Since bioaccumulation of heavy metals entail risks in living species, we suggest that increasing concentrations may detrimentally affect physiological processes in invertebrates and shorebirds. There is an urgent need to identify the sources of pollution and to reduce the discharge of heavy metals and other pollutants into coastal and inland wetlands.

Complex resistivity spectrum of pollutant soils with low-concentration heavy metals

Soil contamination by heavy metals occurs globally, with varying degrees of severity, especially in agricultural fields. Investigating the frequency response characteristics of different types of heavy metal pollutants through induced polarization can provide valuable evidence for surveys based on this method. Soil specimens with varying low concentrations of copper (Cu), chromium (Cr), cadmium (Cd), and lead (Pb) heavy metals were prepared for this study, and parameters including complex resistivity, amplitude-frequency, and resistivity phase were measured. Our findings reveal the following trends: Complex resistivity decreases as heavy metal concentrations increase, demonstrating significant shifts within lower concentration ranges but presenting limitations for assessing pollution in high-concentration areas. Conversely, amplitude-frequency increases with higher heavy metal concentrations, displaying excellent performance in high-concentration scenarios. The differences in complex resistivity and amplitude-frequency among different types of heavy metal pollutants are distinct. In contrast, the absolute phase decreases with rising heavy metal concentrations. The resistivity phase spectra for various heavy metal pollutants exhibit unique patterns. For example, copper-contaminated soil exhibits phase peaks in the frequency range of 8–32 Hz, whereas chromium-contaminated soil shows phase peaks at 16–64 Hz. Cadmium-contaminated soil displays phase peaks ranging from 0.25 Hz to 2 Hz, while lead-contaminated soil exhibits phase peaks within the 0.5 Hz–4 Hz range. Leveraging the frequency range corresponding to phase peaks as an identification method for heavy metal pollution types proves effective. The frequency response characteristics of induced polarization vary significantly among different types and concentrations of heavy metal pollutants, providing important foundations for the application of induced polarization method in the field of heavy metal pollution detection.

Experimental study on the strength and water stability of concentrated solution sludge solidified with sulfoaluminate cement combined with MSWI bottom ash

Concentrated solution sludge (CSS) produced by the submersion combustion technology conducted on the municipal solid waste (MSW) sanitary landfill leachate has special characteristics, such as high water content, low organic matter and heavy metal content and extremely high salt content. In the present work, sulphoaluminate cement (SAC) was used as main curing agent and municipal solid waste incineration (MSWI) bottom ash was collaborated as auxiliary curing agent to solidify the CSS. A series of unconfined compression tests, water stability test and microscopic observation tests were conducted on the solidified CSS samples with various curing agent combinations to quantitatively investigate the influence of different curing agents on the solidification effect of the CSS, and to interpret the physical mechanism of strength improvement and deterioration of the solidified CSS in curing and soaking stage. Research results indicate that: the 7 d unconfined compression strength (UCS) of the CSS solidified with 10% SAC is 168.6 kPa, 162.8 kPa and 158.8 kPa when the water cement ratio is 0.25, 0.30 and 0.35, respectively, which are larger than 50 kPa and can satisfy the strength requirement of landfill. The UCS of the CSS solidified with 50% SAC after soaking in water for 28 days is 329.4 kPa, 276.5 kPa and 202.0 kPa when the water cement ratio is 0.25, 0.30 and 0.35, respectively, and can satisfy the strength requirement of landfill concerning water stability of the solidified CSS; the 28d UCS of the CSS solidified with 40% SAC and an addition of 0%, 5%, 10% and 15% bottom ash is 1483.8 kPa, 2144.4 kPa, 2431.2 kPa and 1537.0 kPa, respectively, and decreased to 0 kPa, 52.9 kPa, 103.9 kPa and 51.0 kPa after soaking in water for 28 days; a reasonable bottom ash content is capable of improving the USC of the cement solidified CSS and there is an optimal dosage of bottom ash for enhancing the 28 d UCS of the cement solidified CSS, which is 5% for SAC content lower than 40% and 10% for SAC content higher than 40%. The improvement effect of the solidified CSS can be achieved by using 10% bottom ash as replacement for 10% SAC. The SEM and XRD test results indicate that: the formation of the spatial interlocking structure composed of the C-S-H gels and ettringite crystals generated by the interaction between SAC and bottom ash in soaking stage is the key factor for improving the water stability of the cement solidified CSS by adding a certain dosage of bottom ash.

Enhancing environmental monitoring: utilizing plant and soil assays to track pollution in a Turkish organized industrial zone

The aim of the current investigation was to determine the concentration of different metals in Mentha spicata L. subsp. tomentosa plants and soils in order to highlight the pollution level in a Turkish Organized Industrial Zone in Dilovasi District, in Kocaeli City. The concentration of metals in plant and soil samples were examined. When the soil values were examined, the highest cadmium, chromium, copper, iron, nickel, and lead levels were collected from the location which is hosting numerous industrial facilities. All elements except boron and copper, exceeded normal limits in the leaf samples while cadmium, chromium, iron, nickel, lead, and zinc reached “toxic levels” in leaf samples. Heavy metals were accumulated in leaves more than rhizomes. Mineral element uptake and accumulation were affected from heavy metal amounts, especially in rhizomes. Although washing procedure notably reduced the concentration of some heavy metals in leaves samples, the reduced values were higher than acceptable levels in some locations of the district. According to the data, it may be said that the region, especially its industrialized parts are heavily polluted by heavy metals. Moreover, in the accordance with the fact that, the highest values of elements were determined in regions having considerable industrial activity such as metal and plastic processing facilities. Additionally, Mentha spicata plants exhibited higher heavy metal values in areas with high heavy metal content in the soil, and lower heavy metal values in areas with low heavy metal concentration. These findings indicate that Mentha spicata, a plant known for its medicinal and culinary uses, can be considered as an effective biomonitor for heavy metal pollution in the region. Consequently, constant inspection is required to prevent the excessive buildup of metals in the region and similar areas with comparable characteristics in terms of human life.

KOH-modified hydrochar produced from Cd/Zn hyperaccumulator Sedum Alfredii Hance for aqueous Cd(Ⅱ) removal: Behavior and mechanism

Hydrothermal carbonization (HTC) has been a promising treatment technology of heavy metal-enriched hyperaccumulator biomass to produce superior hydrochar adsorbent for contamination removal from the wastewater. However, a high amount of heavy metal in derived hydrochar limits its further application. In this study, the effect of reaction temperature (180–270 ℃) and medium pH during HTC on heavy metal contents, speciation and leaching risk of hydrochar from the hyperaccumulator biomass Sedum alfredii Hance was investigated to assess its environmental risk. HTC at a low reaction temperature and acid addition facilitated the removal of Zn/Cd/Pb from the solid phase, meanwhile the addition of acid favored the immobilization of Zn/Cd/Pb and lowered the potential leaching risk of Zn/Cd/Pb. Hydrochar prepared from HTC at 240 °C and pH = 2 had lower heavy metal content and lower releasing risk, followed by KOH modification to obtain high adsorption performance. The modified hydrohcar (KSAB) were characterized by SEM, XRD, BET, Boehm titration and FT-IR, and showed that the surface specific surface area and pore structure were optimized and OFGs of hydrochar were improved significantly after KOH treatment. Adsorption experiments showed that the Cd(II) adsorption process onto KSAB well accorded with pseudo-second-order kinetics and Langmuir isotherms. The maximum Cd(II) adsorption capacity of KSAB was 25.69 mg/g, which was 17 times compared to that of pristine hydrochar. Microstructure characteristics and mechanism analysis further suggested that electrostatic interactions, surface complexation, cation-π and ion exchange were the main Cd(II) removal mechanisms of KOH-modified hydrochar. Therefore, hydrochar derived from hyperaccumulator biomass can be used as a highly efficient absorbent to remove Cd(II) from wastewater after KOH modification.

Elemental, phytochemical, and toxicological assessment of Cissus rotundifolia (Forssk.) Vahl

Cissus rotundifolia (Forssk.) Vahl. (Vitaceae) is a wild plant that is commonly used by communities from rural areas as a food and medicine. There are limited studies on the phytochemical composition and the impact of soil quality on the elemental distribution in this plant. In this study, we report a phytochemical analysis to identify the phytocompounds responsible for the reported biological activities of C. rotundifolia. We also examined the impact of soil quality on elemental uptake by the edible parts of C. rotundifolia collected from eight geographical locations in KwaZulu-Natal (South Africa) to assess the nutritional benefits and potential heavy metal toxicities. Three secondary metabolites (stigmasterol, β-sitosterol, and pheophytin a) were isolated, and their structures were characterised by high-resolution mass spectrometry and nuclear magnetic resonance data. The plant was found to contribute adequately to the recommended dietary allowances for essential nutrients without exceeding tolerable upper intake limits and with low concentrations of toxic heavy metals. The average concentrations of microelements in the edible parts were found to be in decreasing order of Fe&gt;Mn&gt;Se&gt;Zn&gt;Cu&gt;Cr&gt;Ni&gt;Co. The bioaccumulation factors indicate that the plant controls the uptake of metals from the soil and would make a good indicator and biological monitor for cadmium toxicity. However, a health risk assessment exposed carcinogenic risks on regular consumption of the plant obtained from sites close to pollution sources, such as roads and landfills. The findings from this study show the synergies when consuming medicinal plants and provide evidence for C. rotundifolia as a nutraceutical. Significance: This study provides additional scientific knowledge on the phytochemical composition of C. rotundifolia. Three phytocompounds (stigmasterol, β-sitosterol, and pheophytin a) were isolated, and their presence may be correlated to this plant’s antidiabetic, anti-inflammatory, and antibacterial properties. This study shows that C. rotundifolia contributes adequately to the recommended dietary allowances for essential elements, and the plant is safe for human consumption if collected from non-polluted sites. The carcinogenic and non-carcinogenic estimates for the toxic metals due to consumption of the plant signify the possibility of developing cancer over time if the plant is consumed frequently from polluted sites.

Dynamic and static insights on the interaction mechanism between heavy metal contaminants in MSW incineration flue gas and modified carbon materials: Aggregation of PbO and CdO

Clarifying the interaction mechanism between heavy metals and adsorbent is the foundation to trigger the efficiency upgrades of adsorption technology. However, the existing studies ignore the coupling effect between heavy metal pollutants, which leads to a mismatch between theory and practice. Ab-initio molecular dynamics and density functional theory calculations are combined to uncover the dynamical interactions of mixed Pb/Cd species over the transition metal-modified carbon materials (CMs), discovering a new mechanism for enhanced heavy metal removal. Among various mixtures, PbO/CdO generates a stable and compact quadrilateral structure, greatly favorable for the nucleation and agglomeration of gas-phase heavy metals. According to the bond length tracking and electronic analyses, PbO plays an aggregating role and CdO plays a stabilizing role, resulting in dynamic stabilization of the tetragonal aggregates. Due to the different charge transfer and hybridization strengths between the surface-active sites and aggregates, the aggregates can only be stably trapped by Fe-modified CM. In addition, the Fe-modified CM exhibits excellent aggregation properties in the wide temperature region and in the low molecular environment. Overall, Fe-modified CM achieves synergistic removal of PbO and CdO, accommodating the environment of wide temperatures and low heavy metal concentrations, which provides an inspiration for the adsorbent design.

Study on pre-concentration of trace heavy metal ions in water quality detection using FO-electroosmotic integrated chip

The focus of this study is on the enhanced concentration effect of the pump effect in forward osmosis (FO) and electroosmotic integrated chip. The study investigates the strengthening effect of the FO process, driven by the pump effect, on the electroosmotic flow process under the same energy consumption, using low-concentration heavy metal ions (Cr3+) as the target enrichment. In the chip system, the pump effect, caused by capillary pressure difference, successfully replaces the osmotic pressure of the draw solution as a new driving force for the FO process. By adjusting the size and number of channels and avoiding errors, the study achieves the highest efficiency of the FO process in the chip, concentrating Cr3+ from 1.26 × 10−4 mol/L to 8.01 × 10−4 mol/L (6.4 times) within 32 min. Excluding the influence of the electrokinetic (EK) limit of low-concentration samples, the concentration efficiency of an individual electroosmotic chip in this study is positively correlated with cross-nanochannel voltage (Vcn). The integrated FO and electroosmosis chip reduce the duration required to concentrate 50 mL Cr3+ sample to the limit from 90 min to 16 min (5.6 times) compared to the single electroosmotic process. Furthermore, a series of Cr3+ samples with concentrations below the detection limit of the UV–vis spectrophotometer were concentrated and detected by the integrated chip. The results indicate that the concentration limit of the FO-electroosmotic integrated chip for samples can increase the detection limit of Cr3+ from 1.37 × 10−4 mol/L to 3.67 × 10−6 mol/L.

A novel application for magnetite tailings and municipal sludge in ceramsite preparation

AbstractMagnetite tailings and municipal sludge is two different solid wastes. Large stockpiles of magnetite tailings and municipal sludge create serious environmental problems. In this study, a new method for preparing ceramsite from magnetite tailings and municipal sludge is proposed. The effects of factors including preheating temperature, preheating time, roasting temperature, roasting time, and municipal sludge dosage on the physical properties of ceramsite were investigated. The optimal conditions for ceramsite preparation were determined as follows: magnetite tailings:municipal sludge quality ratio of 85:15, preheating temperature of 325°C, preheating time of 40 min, roasting temperature of 1120°C, and roasting time of 6 min. Under these conditions, the ceramsite with an apparent density of 1.22 g/cm3, bulk density of 0.63 g/cm3, 1‐h water absorption of 3.58%, particle strength of 231 N, and cylinder pressure strength of 3.5 MPa was obtained; the resulting ceramsite met the standard requirements and was evaluated as having high quality. A toxic leaching test indicated that the ceramsite had a much lower concentration of heavy metals than the limits described by the USA Environmental Protection Agency, meeting the environmental quality standard requirements for surface water.

Heavy Metal Transport in Different Drip-Irrigated Soil Types with Potato Crop

Heavy metal (HM)-polluted soil is a serious concern, especially as brackish water is widely used for irrigation purposes in water-scarce countries. In this study, the HYDRUS-2D model was used to simulate HM (copper (Cu), lead (Pb), and zinc (Zn)) transport through agricultural land cultivated with potato crops under surface drip irrigation to explore the potential groundwater contamination risk. Three soil types, namely, silty clay loam, sandy loam, and sandy soil, and two irrigation schemes, irrigation every two days (scheme A) and irrigation every four days (scheme B), were considered during the simulations. Firstly, the ability of HYDRUS-2D to simulate water flow was validated using data obtained from a full growing season of the potato crop in a lysimeter irrigated by surface drip irrigation using El-Salam Canal water, Egypt (i.e., water contaminated by HMs). Secondly, the model was calibrated for solute transport parameters. After that, the investigated simulation scenarios were executed. The results showed that HYDRUS-2D effectively simulated water flow. Moreover, a good agreement between the simulations and experimental results of HM concentrations under the calibrated solute parameters was obtained with R2 values of 0.99, 0.91, and 0.71 for Cu, Pb, and Zn concentrations, respectively. HM distribution is considerably influenced by the HMs’ adsorption isotherm. The results of the investigated scenarios reveal that soil texture has a greater impact on HM concentrations in the simulation domain and on the contamination risk of the groundwater than the irrigation scheme. Under both irrigation schemes, lower HM concentrations were observed in sand, while higher values were observed in silty clay loam. Subsequently, the potential shallow groundwater contamination risk is greater when cultivating potatoes in sand, as higher HM concentrations were found in drainage water compared to the two other investigated soils, regardless of the irrigation scheme. The cumulative Cu, Pb, and Zn concentrations in drainage water corresponding to scheme A for silty clay loam and sandy loam were 1.65, 1.67, and 1.67 and 1.15, 1.14, and 1.15 times higher, respectively, than scheme B. To safeguard the sustainability of groundwater and agricultural lands irrigated with water contaminated by HMs, it is recommended to adopt an irrigation frequency of once every four days in soils with silty clay loam and sandy loam textures.

Türkiye'de Perakende Satışı Yapılan Tatlı Su Balık Türlerinde Ağır Metallerin Birikimi: Toksik Metallerin Potansiyel Halk Sağlığı Tehlikesi

This study aimed to assess the concentration of fourteen elements (Al, Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, Zn) in 91 edible freshwater fish muscle samples using inductively coupled plasma-mass spectrometry (ICP-MS). Statistical analyses such as principal component, cluster, and correlation analysis were done to evaluate the obtained data. The order of mean concentrations (mg/kg wet wt.) of metals in all fish meat samples were Al (204) &gt; Zn (10.2) &gt; Fe (6.43) &gt; Cu (0.666) &gt; Hg (0.589) &gt; Ni (0.556) &gt; Pb (0.497) &gt; Cr (0.396) &gt; Ag (0.291) &gt;Se (0.144) &gt; As (0.074) &gt; Co (0.043) &gt; Cd (0.037) &gt;V (0.027). Hg, Ca, and Pb concentrations in some samples exceeded the permissible legal limits, whereas As was lower than maximum allowable limits. Ninety-one fish samples were categorized into five categories by PCA with Eigenvalues higher than 1.00. Cluster analysis results showed that the pollution with metal pairs analyzed might be from similar sources. In conclusion, as the long-term effect of low concentrations of heavy metals caused serious health problems ranging from carcinogenic effects to immunological disorders, heavy metal content in fish and fishery products must be closely monitored to protect consumer health.