Arsenic Concentrations Research Articles

Comparative evaluation of diffusion kinetics of arsenic adsorption on iron (oxy) hydroxides containing biopolymer nanocomposite beads

Exposure to arsenic-contaminated water poses great health risks to mankind. Nanocomposite beads have been proven to be an effective alternative for large-scale treatment of arsenic-loaded water. The larger size of the beads makes the adsorbent retrieval process less energy-intensive and prevents accidental leaching of nanoparticles into the surrounding environment. Adsorption using macroporous beads is predominantly a diffusion-controlled process. Therefore, in the present study, the shrinking core model (SCM) was used to compare and evaluate the diffusion kinetics of arsenic adsorption using in-situ precipitated iron (oxy)hydroxide alginate (IIAB) and chitosan beads (IICB). Simulated dynamic nondimensional liquid phase arsenic concentration profiles fit well with the experimental data (SSE = 0.018–0.025). External mass transfer coefficient (kf) and effective diffusivity coefficient (De) for both kinds of beads at different initial arsenic concentrations (C0 ∼ 1 mg.L−1 and 5 mg.L−1) were derived. By comparison of diffusivity values and the simulated concentration front profiles, it was observed that chitosan provided a better porous polymer template with more easily accessible adsorption sites covering up to 85 % of the beads’ volume. Comparison with progression conversion models has also been made to test the effectiveness of SCM fitting.

Synthesis of Phosphorus/Arsenic Tridentate Ligands and Their Application for Luminescent Copper (I) Halide Complexes

AbstractWe synthesized arsenic analogs of a tridentate PPP ligand, bis[2‐(diphenylphosphino) phenyl] phenylphosphine, achieving yields of 40 % to 71 %. Additionally, we prepared copper (I) halide (CuX, X=Br, I) complexes with these ligands, with yields between 43 % and 84 %. Using both experimental and computational methods, we examined their structures and photophysical characteristics. Single crystal X‐ray diffraction showed that all eight complexes had distorted tetrahedral geometries. These complexes exhibited photoluminescence with emission bands peaking from 506 nm to 551 nm and quantum yields up to 0.92 at room temperature. Emission lifetimes varied and showed no direct correlation with quantum yields or wavelengths. Physical manipulation and solvent variations significantly altered their photoluminescent properties. DFT and TD‐DFT calculations revealed that higher arsenic content increased spin‐orbit coupling constants, with iodide complexes performing better than bromide ones due to heavier elements enhancing spin‐orbit coupling. Substituting phosphorus with arsenic significantly affected the luminescence quantum yield and lifetime, demonstrating the heavy‐atom effect of arsenic. The position of arsenic in the ligands critically influenced the photophysical outcomes of the CuX complexes.

Exposure assessment of metal(loids) in indoor air and biomonitoring in six urban residential areas in Iran

Exposure to metal(loid)s can cause adverse health effects. This study evaluated the concentrations of aluminum, arsenic, cadmium, chromium, mercury, nickel, and lead in particulate matter <10 μm (PM10) and in the urine of 100 participants from urban residential areas in Iran. A total of 100 residential buildings (one adult from each household) in six cities across Iran were recruited for this study. The levels of metal(loid)s in PM10 and the urine of participants were measured using acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). The average (±SE) PM10 concentration in the buildings was 51.7 ± 3.46 μg/m3. Aluminum and cadmium had the highest and lowest concentrations among the metal(loid)s, averaging 3.74 ± 1.26 μg/m3 and 0.01 ± 0.001 μg/m3, respectively. In 85 % of the samples, the concentration of metal(loid)s in indoor air exceeded WHO air quality standards. Cadmium and lead had the highest and lowest numbers of indoor air samples exceeding the recommended standards, respectively. A significant correlation was found between the concentration of metal(loid)s in urine samples and indoor PM10 levels, as well as the wealth index of participants. There was also a significant direct relationship between the concentrations of nickel, arsenic, lead, and mercury in urine and the age of participants. Factors such as building location, type of cooling systems, use of printers at home, and natural ventilation influenced the concentration and types of metal(loid)s in the indoor air.

Tampons as a source of exposure to metal(loid)s

BackgroundBetween 52–86% of people who menstruate in the United States use tampons—cotton and/or rayon/viscose ‘plugs’—to absorb menstrual blood in the vagina. Tampons may contain metals from agricultural or manufacturing processes, which could be absorbed by the vagina’s highly absorptive tissue, resulting in systemic exposure. To our knowledge, no previous studies have measured metals in tampons. ObjectivesWe evaluated the concentrations of 16 metal(loid)s in 30 tampons from 14 tampon brands and 18 product lines and compared the concentrations by tampon characteristics. MethodsAbout 0.2 – 0.3 g from each tampon (n = 60 samples) were microwave-acid digested and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine concentrations of arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, manganese, mercury, nickel, lead, selenium, strontium, vanadium, and zinc. We compared concentrations by several tampon characteristics (region of purchase, organic material, brand type) using median quantile mixed models. ResultsWe found measurable concentrations of all 16 metals assessed. We detected concentrations of several toxic metals, including elevated mean concentrations of lead (geometric mean [GM] = 120 ng/g), cadmium (GM = 6.74 ng/g), and arsenic (GM = 2.56 ng/g). Metal concentrations differed by region of tampon purchase (US versus European Union/United Kingdom), by organic versus non-organic material, and for store- versus name-brand tampons. Most metals differed by organic status; lead concentrations were higher in non-organic tampons while arsenic was higher in organic tampons. No categoriy had consistently lower concentrations of all or most metals. DiscussionTampon use is a potential source of metal exposure. We detected all 16 metals in at least one sampled tampon, including some toxic metals like lead that has no “safe” exposure level. Future research is needed to replicate our findings and determine whether metals can leach out of tampons and cross the vaginal epithelium into systemic circulation.

Evaluation of As, Cd, Ni and Se Content of Some Mineral Concrete Agents

In this study, the variation of arsenic (As), cadmium (Cd), nickel (Ni) and selenium (Se) concentrations in some materials used as concrete admixtures were evaluated. These heavy metals are extremely hazardous elements for both human and other living organisms and the environment. Due to these hazards, they are on the priority pollutant list of both ATSDR and EPA. Study results show that heavy metal concentrations in some additives are at very high levels. As a result of the study, the highest As concentrations were obtained in copper slag, vermiculite and cem III cement, the highest Cd concentrations in crushed stone and copper slag, the highest Ni concentrations in copper slag, wood ash and brick powder, and the highest Se concentrations in blast furnace slag and cem III cement. This may pose a great risk to the health of people working in the industry and the environment.

Multistage stabilization of Cd, Pb, Zn, Cu and As in contaminated soil by phosphorus-coated nZVI layered composite materials: characteristics, process and mechanism

This study developed a shell-like slow-release material, PF@ST/Fe-0.5, by encapsulating nanoscale zero-valent iron composites (NZC) with phosphate fertilizer (PF) and a starch binder (ST). The material dissolved in soil in stages, first releasing P and Ca to increase the soil pH from 4.95 to 7.14. This was followed by the formation of phosphates and hydroxides precipitates with Pb, Cu, Zn, and Cd in soil, reducing their bioavailable forms by 81.73 %, 79.58 %, 91.05 %, and 86.47 %, respectively. The process also involved the competitive adsorption between PO43-/HPO42- and arsenate/arsenite led to the release of specifically adsorbed arsenic, increasing the probability of reaction with the material. Afterwards, the exposure of the NZC core reacted with arsenate/arsenite to form ferric arsenates, thus reducing the content of bioavailable arsenic in the soil by 73.57 %. Excess PO43- and alkali metal cations were captured and mineralized by the iron (hydro) oxides and reactive silicates in NZC, enhancing the remediation effect. Furthermore, the wet-dry alternation test had demonstrated the adaptability of PF@ST/Fe-0.5 to the rainy dry-wet soil environment in Yunnan, which enabled the bioavailable content of As, Pb, Cu, Zn, and Cd decreased by 71.2 %, 94.8 %, 84.1 %, 79.8 %, and 83.9 %, respectively. The layered structure minimized internal reactive substance consumption and protected the internal nZVI from oxidation. The phased release of phosphate and Fe0 stabilized Pb, Cu, Zn, and Cd, enhancing As stabilization and providing a new perspective for the synchronous stabilization of soil contaminated.

Pre-oxidation and coagulation-flocculation as a pretreatment to UF-RO applied for surface water treatment and arsenic removal

In this paper, the effects of applying pre-oxidation, coagulation, and flocculation (C/F) as pretreatment of an ultrafiltration (UF) - reverse osmosis (RO) system treating water containing arsenic were assessed. For this, the performance of a pilot scale – with a maximum treatment capacity of 2.25 m3/h - UF-RO system with and without pretreatment was evaluated. The membranes were able to generate high-quality permeates, even when the feed presented a remarkable increase in color (>2100 uH) and turbidity (>300 NTU) due to the beginning of the rainy season. UF was not efficient for arsenic removal, so RO was essential to guarantee safe water, generating permeates with concentrations below 0.5 μg/L of arsenic. The effective removal of iron and manganese, among other ions, was verified using membranes. Given the high quality of the permeates, blend formulation strategies were carried out, mixing filtered water from the conventional water treatment plant and RO permeate (Strategy I) and mixing filtered water, UF permeate, and RO permeate (strategy II). Strategy II was viable for arsenic concentrations in filtered water of 13 and 15 μg/L. Pretreatment was important in maintaining a higher membrane permeability and ensured a more stable performance in the face of variations in feed quality, which may be seasonal in some places, as in the present case, where feed quality is significantly altered by the rainy season. Overall, although UF and RO membranes are effective processes for treating surface water containing arsenic, the results suggested that pretreatment, which is already part of the treatment of several water treatment plants, guarantees more robustness to the treatment concerning a higher and more stable membrane permeability, directly impacting operational expenses with membranes operation.

Heavy metal concentrations in drinking water sources in two mining districts in Ghana

In Ghana, mining of minerals at small-scale and large-scale is widespread across many districts, leading to significant heavy metal pollution in the environment. In this study, the concentrations of iron (Fe), manganese (Mn), arsenic (As), and mercury (Hg) in the different drinking water samples collected from households, institutions, water points and surface water in two mining districts namely the Wassa East and Asutifi North were analyzed. The water types collected included boreholes, wells, piped water into yards, public standpipes, rainwater, sachet water, and surface water. The results indicated that the levels of Fe and Mn were higher than As and Hg in all the drinking water samples. The levels of As and Hg in drinking water from households and institutions were higher in the Wassa East district compared to the Asutifi North district. However, the metal levels at water points were similar in both districts. In surface water, Fe levels were higher in the Wassa East district compared to the Asutifi North district with median values of 1243 μg/L and 860 μg/L for the Wassa East and Asutifi North districts, respectively. In contrast, the Mn levels were higher in the Asutifi North district than the Wassa East district with median values of 9.5 μg/L and 90 μg/L for Wassa East and Asutifi North districts, respectively. All the metals (Mn, As, and Hg) studied except Fe were within the recommended WHO level. The Heavy Metal Pollution Index (HPI) values for the different water types in households, institutions and water points were all below the critical limit of 100. The Water Quality Index (WQI) indicates that the boreholes, piped water into yards, and public standpipes in both districts were classified as excellent or good, making them suitable for drinking. However, the wells and surface water in both districts were classified as very poor and unfit for drinking, respectively.

Residential proximity to toxic metal-emitting industrial sites and toenail metal concentrations in a United States-wide prospective cohort

BackgroundIndustrial facilities across the United States (US) release millions of pounds of toxic chemicals, including metals. Exposure to toxic metals has been associated with adverse health outcomes, but there is limited evidence on the association between living near metal-releasing facilities and the body burden of emitted compounds. ObjectiveTo investigate the association between residential proximity to toxic metal-emitting industrial facilities and toenail metal concentrations and to evaluate whether associations differed by race. MethodsIn a sample of 1556 non-Hispanic Black (32.5%) and non-Hispanic White (67.5%) women from the Sister Study, we used the US Environmental Protection Agency Toxics Release Inventory to identify metal-emitting facilities within 3, 5, and 10 km of participants’ baseline residences. We measured toenail concentrations (μg/g) of arsenic, cadmium, cobalt, chromium, and lead. Using multivariable linear regression, we examined associations between residential proximity to and emissions from metal-emitting facilities and toenail metal concentrations, stratifying by race. We explored modification of race-stratified associations by neighborhood deprivation, using the Area Deprivation Index (ADI). ResultsBlack participants were more likely to reside within 3 km of chromium-releasing facilities and 5 and 10 km of all observed metal-emitting sites. Living near metal-releasing facilities was not associated with higher toenail metal concentrations overall. Among Black women, higher chromium emissions exposure was associated with higher toenail chromium levels (βTertile3vs.non-exposed = 2.36 μg/g, 95% CI = 0.63, 4.10). An association with lead was observed among Black women residing in the most deprived areas (≥75th ADI percentile: β = 3.08 μg/g, 95% CI = 1.46, 4.71). No associations were observed for White participants. ConclusionsDespite low exposure prevalence, our findings suggest that living near chromium- and lead-releasing facilities, especially at shorter distances, may be associated with higher corresponding toenail metal levels among Black women, particularly those residing in the most disadvantaged areas.

The effects of water content on mineralogical and drainage quality dynamics in weathering mine waste rock

Water content plays a critical yet ambivalent role in the physical and geochemical stability of mine tailings and waste rock, but its effects on individual chemical weathering reactions (dissolution and precipitation) and bulk water quality remain poorly understood. We experimented with synthetic waste rock to quantitatively reconcile modal and textural mineralogical parameters (mineral size, association, and liberation) with leachate quality at different water saturation levels (5–100%). Leachate pH consistently decreased from a 13-week average of 6.14 at 100% saturation to 5.37 at 5% saturation. Simultaneously, mineralogical analyses revealed a reduction in the size of carbonate phases over the course of weathering, decreasing from 200 µm to 145 µm as water saturation increased from 5% to 100%, which could be a contributing factor to more alkaline pH in samples with higher water saturation. Total concentrations of iron (Fe) and copper (Cu) in solution increased with lower moisture, with Cu concentrations increasing 24-fold in samples at 5% saturation compared to full saturation. In contrast, arsenic (As) concentration increased with higher moisture levels, which we attribute to reduced galvanic protection of As-bearing pyrite from oxidation. Multivariate statistical evaluation allowed us to uncover correlations between water chemistry and mineralogical data (i.e., sulfide associations or phase perimeters) and to explain chemical differences between samples, particularly those at 100% and 5% water saturation. Our findings underscore the importance of conducting quantitative mineralogical investigations on mine waste materials and considering their stored water content in the formulation of mine waste management strategies.

Krótka charakterystyka ochry ze sztolni Marta (Nižná Slaná, Spiš-Gemer Ore Mts

The contribution deals with the study on composition of ochre sample from the Marta adit at Nižná Slaná. Three samples were prepared from ochre by hand picking and screening, which were subjected to GA, AAS, XRF and XRD. Salts precipitated on surface at drying contain 17.7 % S (53 % as SO4), 16.5 % MgO, 13.6 % Fe2O3, 3.54 % CaO and 1 % MnO. As to mineral composition, sulphates such as gypsum, starkeyite and rozenite are dominant. The fraction of grain size under 250 micron contains 30 % Fe2O3, 28.6 % SiO2, 8 % Al2O3, 6.6 % CaO, 2.9 % MgO and 1.95 % S. Notable is content of arsenic in this fraction, which attain as high as 1.84 %. Quartz and gypsum occur as dominant crystalline phases. As to coarser fraction, i.e. under 150 microns, 44.5 % SiO2, 16.8 % Fe2O3, 11.3 % Al2O3, 6.9 % CaO, 2.4 % MgO a 2.3 % C were assayed. Dominant quartz is accompanied by mica, plagioclase, ankerite and dolomite. It was shown that arsenic is bonded in finer grain size fraction.

Formation processes of iron-based layered hydroxide in acid mine drainage and its implications for in-situ arsenate immobilization: Insights and mechanisms

The immobilization of arsenate in transformed minerals depends on their states in acid mine drainage (AMD). In this study, an iron-based layer hydroxide mineral was derived from the transformation of ferrihydrite under co-existing Mg2+ ions in AMD. The immobilization behavior of arsenate on the mineralized LDHm and pre-prepared LDHad was distinguished. 99 % immobilization efficiency was achieved from the mineralized LDHm, maintaining stability without subsequent releases, across initial arsenate concentrations ranging from 10 to 60 mg/L. LDHm outperformed the pre-prepared LDHad, which was synthesized from AMD for arsenate adsorption. Electron energy loss spectroscopy line profiles revealed predominant incorporation of arsenate in the LDHm structure, supported by higher bulk As signals within LDHm. Density functional theory calculations indicated primary arsenate incorporation into LDHm, forming stable bonds with lower energy activation barriers. Importantly, LDHm exhibited a superior electron rearrangement configuration, resulting in enhanced electron state activity and affinity for arsenate. In contrast, arsenate adsorption predominantly occurred on the pre-prepared LDHad, with notable As signals detected particularly at the edges. Adsorption energy evaluation indicated arsenate preference for bonding to Fe3+ sites on LDHad. These findings provide important insights into the role of stable LDH-like minerals for long-term arsenate immobilization in the natural AMD attenuation processes.

Assessment of Soil Contamination with Heavy Metals and Arsenic in the City of Komsomolsk-on-Amure

Research and assessment of soil contamination with heavy metals and arsenic in Komsomolsk-on-Amur have been carried out. High levels of soil contamination with heavy metals have been found — toxicants of hazard classes 1 and 2, among which the largest participation of zinc, lead, copper and cadmium has been recorded. It has been noted that the high content of arsenic in soils may be due to both technogenic influence and natural features of the area under study. A comparison has been made of the contents of heavy metals and arsenic in the soils of the city of Komsomolsk-on-Amur with the local natural background and technogenic background concentrations of other industrial cities in Russia and China. Two main technogenic geochemical anomalies (zones of increased pollution levels) associated with the main industrial hubs of the city have been identified.

Associations of toxic metals and their mixture with hyperuricemia in Chinese rural older adults.

Previous studies have related single toxic metals (TMs) to hyperuricemia (HUA) among the general population, however, the association of the TM mixture with HUA, especially in older adults, remains poorly understood. We aimed to examine the relationships between individual TMs and their mixture and HUA in Chinese rural older adults. This study consisted of 2075 rural older adults aged 60years or over. Blood concentrations of aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), cesium (Cs), gallium (Ga), mercury (Hg), lead (Pb), thallium (Tl), and uranium (U) were detected using inductively coupled plasma mass spectrometry. The associations of single TMs with HUA were assessed using logistic regression and restricted cubic spline (RCS) models, and the association of TM mixture with HUA was explored using the elastic net with environmental risk score (ENET-ERS), quantile g-computation (QGC), and Bayesian kernel machine regression (BKMR) models, respectively. Adjusted logistic regression model showed that Cs (OR = 1.65, 95% CI 1.37-1.99) and Pb (OR = 1.46, 95% CI 1.28-1.67) were positively related to HUA, andRCS model exhibited a positive linear association of Cs and Pb with HUA. ENET-ERS and QGC models quantified a positive correlation between the TM mixture and the odds of HUA, with estimated ORs of 1.15 (95% CI 1.11-1.19) and 1.84 (95% CI 1.37-2.47), respectively, and Cs and Pb had the most weight. BKMR model demonstrated a significant linear association between the TM mixture and increased odds of HUA, with the posterior inclusion probabilities (PIPs) of both Cs and Pb being 1.00. Moreover, we observed a positive interaction between Cs and Pb on HUA. The TM mixture is associated with increased odds of HUA in rural older adults, which may mainly be driven by Cs and Pb. Subsequent studies are warranted to confirm these findings and clarify the mechanisms linking multiple TMs with HUA.

Effect of trace element arsenic on the high cycle fatigue properties and the carbide uniformity in high carbon chromium bearing steel

AbstractIn this paper, the mechanical properties and microstructures of bearing steels with arsenic contents of 30, 40, and 120 ppm have been investigated. The results show that As‐40 steel has the highest tensile strength but lower fatigue strength than As‐120 steel. The fatigue crack propagation rate of As‐120 steel is relatively low, mainly due to the increase in ΔKth. After quenching and tempering, As‐120 steel has larger prior austenite grains and more undecomposed, elongated carbides appear, reducing the uniformity of the steel. For carbides with an aspect ratio greater than 2, they cannot grow by the Oswald mechanism of spontaneous migration but are spheroidized by self‐cracking. The undissolved elongated carbides have a lower chemical potential, which increases the diffusion tendency of arsenic in the matrix. SIMS and EPMA analyses show that there is no significant distortion of the trace element arsenic.

Biochar-based nanoparticles mitigated arsenic toxicity and improved physiological performance of basil via enhancing cation exchange capacity and ferric chelate reductase activity

The modified biochars have positive effects in reducing heavy metal toxicity for plants. However, the mechanism and extent of these effects on mitigating arsenic toxicity and plant performance are not clear. Thus, a pot experiment was conducted as factorial to evaluate the potential of fresh and enriched biochars with potassium and magnesium nano-sulfates [potassium-enriched biochar (K-BC), magnesium-enriched biochar (Mg-BC) in individual and combined forms] on reducing arsenic toxicity (non-contamination, 50, and 100 mg NaAsO2 kg−1 soil) in basil plants. Biochar-related treatments reduced plant arsenic absorption rate (up to 24%), arsenic content of root (up to 38%) and shoot (up to 21%) and root tonoplast H+-ATPase activity (up to 30%). The fresh and particularly enriched biochars improved soil properties (pH, CEC, and available iron content), ferric chelate reductase activity, iron, potassium and magnesium contents of plant tissues, chlorophyll content index, photochemical efficiency of photosystem II, relative electron transport rate, leaf area, and basil growth (shoot and root dry weight). These results revealed that enriched biochars are useful soil amendments for improving physiological performance of plants via reducing heavy metal toxicity and enhancing cation exchange capacity, nutrient availability and ferric chelate reductase activity. Therefore, soil amendment by enriched biochars could be a sustainable solution for enhancing plant productivity in contaminated soils via mitigating environmental impacts. This is an environmentally friendly method for using the natural wastes to overcome the adverse effects of soil pollutants on medicinal plants.

Bioaccumulation of chemical elements in fish from areas affected by oil on the coast of Bahia, Brazil

In 2019, the Brazilian coast was affected by the largest oil spill in its history. We assessed the levels of chemical elements in Lutjanus synagris and Haemulon aurolienatum fish from Itacaré (least affected area), Tinharé-Boipeba (most affected area) and Madre de Deus (chronically affected area). The level of metals differed between species, tissues, life cycle phases, maturation stages and between sampled locations, indicating the influence of biological and environmental aspects on bioaccumulation. Only fish in Madre de Deus showed lead contamination, while arsenic concentrations in the three areas exceeded the maximum value acceptable by Anvisa (National Health Surveillance Agency). It is suggested that the oil spill may have impacted species differently, also having an impact in fish from less affected areas. However, metal concentrations in fish in Madre de Deus stood out when compared to populations in other studied areas.

The Safety of Leafy Vegetables in Oman

Leafy vegetables are potential carriers of foodborne diseases that threaten the community’s well-being. Therefore, monitoring leafy vegetable’s microbial and heavy metal contamination is crucial. This study evaluates the safety of leafy vegetables consumed in Oman by examining pathogenic bacteria such as Escherichia coli, Staphylococci, Salmonella, and Listeria, as well as the heavy metals concentration. Results indicate high levels of microbial contamination in all samples, exceeding the Gulf Standard Organization permissible levels for E. coli and Staphylococci. The highest levels of E. coli were 5.96, 6.08, 6.09, 6.25, and 6.01 log CFU/g in Arugula, Radish, Lettuce, Cabbage, and Spring onion, respectively. While for Staphylococcus the highest values were 5.59, 5.71, 4.33, 5.07, and 4.46 log CFU/g in Arugula, Radish, Lettuce, Cabbage, and Spring onion, respectively. No Salmonella or Listeria colonies were found in any samples even after several days of incubations. The Arsenic and Lead concentrations in all samples were significantly higher than the permissible levels set by FAO/WHO, while Chromium was high in some samples. The concentrations of Copper and Iron in most samples fell below their respective permissible levels, while Zinc was undetectable in all samples. These findings underscore inadequate hygiene, harvesting, storage, and agricultural practices, raising concerns about the health implications of consuming contaminated leafy vegetables.

Exposure to iodine, essential and non-essential trace element through seaweed consumption in humans

Seaweed consumption has gained popularity due to its nutritional value and potential health benefits. However, concerns regarding the bioaccumulation of several trace elements highlight the need for comprehensive studies on exposure associated with seaweed consumption. To address this gap in knowledge, we carried out a feeding intervention study of three common edible seaweeds (Nori, Kombu, and Wakame) in 11 volunteers, aiming to elucidate the extent of both beneficial and harmful trace element exposure through seaweed consumption in humans. Concentrations of total arsenic, cobalt, copper, cadmium, iodine, molybdenum, selenium, and zinc were measured in urine samples before and following seaweed consumption. Elements concentrations were also measured in the seaweeds provided for the study. Descriptive analysis for each element were conducted and we used quantile g-computation approach to assess the association between the 8-element mixture and seaweed consumption. Differences in urine element concentrations and seaweed consumption were analyzed using generalized estimating equations (GEE). Urinary concentrations of iodine and total arsenic increased after seaweed consumption. When we analyze the 8-element mixture, the largest weight was observed for iodine after Kombu consumption while for total arsenic was observed after Wakame consumption. Similar results were observed when we compared the mean differences between the elements before and after seaweed consumption through the GEE. Seaweed consumption relates with increased urinary iodine and total arsenic concentrations, particularly after Kombu and Wakame consumption.

Ultrafiltration and reverse osmosis integrated to conventional drinking water treatment to ensure human right to water in dam break scenarios: From bench- to pilot-scale

Previous events of tailing dam failures were associated with impacts in the water sources of drinking water treatment plants, which involves elevated concentrations of suspended solids and metal(oid)s. This study assesses the effectiveness of conventional treatment processes at a lab-scale, highlighting their limited robustness in treating water with different physicochemical qualities. Subsequently, it validates the integration of ultrafiltration (UF) and reverse osmosis (RO) into an existing water treatment plant to enhance its performance. The processes were conducted at a pilot scale, operating for 660 h under varied turbidity (<2 – 200 NTU) and contaminant (iron, manganese, and arsenic) concentrations. The membranes operated steadily with an average permeate flux of 38.6 ± 0.9 L/m2h and 19.6 ± 0.8 L/m2h for UF and RO, respectively. UF fouling was primarily related to internal pore blocking and attributed to organic matter and inorganic compounds, identified using excitation-emission matrix and energy-dispersive X-ray mapping across the cross-section of its fibers. Due to the limitations of UF in removing dissolved species, RO became necessary and ensured that all parameters analyzed met drinking water standards. The UF-RO contributes to higher robustness to conventional treatment processes and addresses operational challenges associated with a dam rupture event such as the unforeseen alteration in the quality of surface water that hinders the optimization of pre-oxidants and coagulants in conventional treatment process. To reduce costs, energy requirements, and the size of membrane-based systems, a blending strategy was proposed with a focus on achieving drinking water standards. The suggested blends include effluent from sand filters and RO permeate in a 1:1 ratio. That was only possible due to the high quality achieved for RO permeate. Apart from creating more compact systems, the blending strategy promotes the remineralization of RO permeate, mitigating undesirable characteristics such as corrosiveness, taste, and odor. For the concentrate, UF concentrate could be recycled back into the treatment process, improving water recovery in the drinking water facility, while the concentrate from RO adheres to discharge limits. Overall, the study advances investigations on integrating ultrafiltration and reverse osmosis with conventional drinking water treatment to address water quality issues from tailing dam ruptures.