Deciphering the Complex Mineralogy of River Sand Deposits through Clustering and Quantification of Hyperspectral X-Ray Maps.

Alluvial mineral sands rank among the most complex subjects for mineral characterization due to the diverse range of minerals present in the sediments, which may collectively contain a daunting number of elements (>20) in major or minor concentrations (>1 wt%). To comprehensively characterize the phase abundance and chemistry of these complex mineral specimens, a method was developed using hyperspectral x-ray and cathodoluminescence mapping in an electron probe microanalyser (EPMA), coupled with automated cluster analysis and quantitative analysis of clustered x-ray spectra. This method proved successful in identifying and quantifying over 40 phases from mineral sand specimens, including unexpected phases with low modal abundance (<0.1%). The standard-based quantification method measured compositions in agreement with expected stoichiometry, with elemental detection limits in the range of <10­1,000 ppm, depending on phase abundance, and proved reliable even for challenging mineral species, such as the multi-rare earth element (REE) bearing mineral xenotime [(Y,REE)PO4] for which 24 elements were analyzed, including 12 overlapped REEs. The mineral identification procedure was also capable of characterizing mineral groups that exhibit significant compositional variability due to the substitution of multiple elements, such as garnets (Mg, Ca, Fe, Mn, Cr), pyroxenes (Mg, Ca, Fe), and amphiboles (Na, Mg, Ca, Fe, Al).

Trace elements in rice grain and agricultural soils: assessment of health risk of inhabitants near a former secondary lead smelter in Khulna, Bangladesh.

Ingestion of food grain grown in metal-contaminated soils may cause serious effects on human health. This study assessed the concentrations of Pb, As, Cd and Zn in agricultural soils and in rice grains near a former secondary lead smelter in Khulna, Bangladesh. It analyzed 29 samples of surface soil and rice grain collected around 500 m of the smelter. Contamination factor (Cf), pollution load index and total hazard quotient (THQ) were calculated to determine ecological and human health risks. Cd was not detected in any of the samples. For the soil samples, medians of the concentrations of Pb, As and Zn were 109, 6.2 and 514 mg/kg, respectively. For the rice grain samples, medians of the concentrations of Pb, As and Zn were 4, 1.4 and 25 mg/kg fw, respectively. Medians of the concentrations of Pb and As in rice grain were higher compared to their maximum allowable limit (0.2 mg/kg), which indicate potential health risks to inhabitants near the Pb smelter. The mean values of Cf for Pb, As, and Zn were, respectively, 11.6, 2.1 and 7.4. For Pb, around 41% of the samples had Cf > 6 indicating very strong contamination. THQ values for Pb and As were greater than 1.0, which evinces the health hazards of these trace elements. Measures should be taken to prevent trace elements exposure from Pb smelter in the study area.

Potential ecological risk of metal pollution in lead smelter-contaminated agricultural soils in Khulna, Bangladesh.

Lead smelters are important source of metal pollution. This study assessed ecological risks of three heavy metals (Pb, As, and Zn) in agricultural soils surrounding five Pb smelters from Khulna district in Bangladesh. A total of 81 surface soil samples collected within 500-m radius of the smelters were analyzed using an atomic absorption spectrophotometer (AAS). Concentrations of Pb, As, and Zn ranged within 6-3902, 1.8-9.6, and 45.4-563 mg/kg, respectively. About half of the Pb samples (~ 51%) exceeded soil quality standard target value (85 mg/kg), and the concentrations gradually decreased with horizontal distance from the smelter. The value of pollution index (PI) measured for Pb, As, and Zn varied respectively in the range of 0-195, 0.6-3.2, and 0.67-8.28, with mean values of 11.7, 1.9, and 3.92. The value of integrated pollution index (IPI) calculated for these metals remained between 0.58 and 66.2 with a mean of 5.7, and that designates ~ 96% of the sampled soils as moderately or highly contaminated. Potential ecological risk (PER) calculated for the metals indicate that all the samples were within low to moderate risk, and the descending order of PER of the metals was Pb > As > Zn.

Evaluation of harvested rainwater quality at primary schools of southwest coastal Bangladesh.

Rainwater is a typical source of drinking water in the coastal areas of Bangladesh given the acute scarcity of drinking water. This study assessed potability of harvested rainwater of primary schools in southwest coastal Bangladesh. Water samples collected from 23 primary schools of Mongla sub-district under Bagerhat district were evaluated for indicator bacteria (total coliform (TC) and E. coli) and physico-chemical parameters (pH, electrical conductivity, turbidity, total dissolved solid, Fe, Zn, Pb, and Cd). Median concentrations of TC and E. coli in the harvested rainwater samples were respectively 3000 cfu/100 ml and 6 cfu/100 ml. However, concentrations of these indicator bacteria were lower at the consumption points which received a prior treatment. Concentration of Pb exceeded the maximum allowable limit for drinking water indicated by WHO and Bangladesh drinking water guideline value in 92% and 61% of the samples respectively, and the mean concentration was 0.08 mg/l (8 times higher than the WHO guideline value). The Pb contamination possibly occurred from the painting on roof railing and roof stair room. Therefore, consumption of harvested rainwater at primary schools may cause substantial health risk for the school-going children.

Correlates of healthy life expectancy in low- and lower-middle-income countries.

BACKGROUND: Healthy life expectancy (HALE) at birth is an important indicator of health status and quality of life of a country's population. However, little is known about the determinants of HALE as yet globally or even country-specific level. Thus, we examined the factors that are associated with HALE at birth in low- and lower-middle-income countries. METHODS: In accordance with the World Bank (WB) classification seventy-nine low- and lower-middle-income countries were selected for the study. Data on HALE, demographic, socioeconomic, social structural, health, and environmental factors from several reliable sources, such as the World Health Organization, the United Nations Development Program, Population Reference Bureau, WB, Heritage Foundation, Transparency International, Freedom House, and International Center for Prison Studies were obtained as selected countries. Descriptive statistics, correlation analysis, and regression analysis were performed to reach the research objectives. RESULTS: The lowest and highest HALE were observed in Sierra Leone (44.40 years) and in Sri Lanka (67.00 years), respectively. The mean years of schooling, total fertility rate (TFR), physician density, gross national income per capita, health expenditure, economic freedom, carbon dioxide emission rate, freedom of the press, corruption perceptions index, prison population rate, and achieving a level of health-related millennium development goals (MDGs) were revealed as the correlates of HALE. Among all the correlates, the mean years of schooling, TFR, freedom of the press, and achieving a level of health-related MDGs were found to be the most influential factors. CONCLUSION: To increase the HALE in low- and lower-middle-income countries, we suggest that TFR is to be reduced as well as to increase the mean years of schooling, freedom of the press, and the achievement of a level of health-related MDGs.

Association between intimate partner violence during pregnancy and maternal pregnancy complications among recently delivered women in Bangladesh.

Intimate partner violence (IPV), an actual or threatened physical, sexual, or psychological abuse by a current or former partner or spouse, is a common global public health issue. Understanding both the prevalence of IPV during pregnancy and its potential impact on the health of pregnant women is important for the development and implementation of interventions to prevent maternal morbidity and mortality. The purpose of this study was to explore the association between maternal experiences of IPV during pregnancy and pregnancy complications. A health-facility-based cross-sectional study was conducted from July 2015 to April 2016 among 400 randomly selected women who were admitted to the postnatal wards of Rajshahi Medical College Hospital for delivery. Data were collected through face-to-face interviews using a structured questionnaire. Multivariable logistic regressions were performed to assess relationships between variables of interest after controlling for potential confounders. Results indicated that 39.0% of women reported physical IPV and 26.3% of women reported sexual IPV during pregnancy. Additionally, 69.5% of women experienced medical complications (MCs); of this group, 44.3% experienced obstetric complications (OCs) and 79.3% experienced any pregnancy complication (AC) during their last pregnancy. The experience of physical IPV during pregnancy was significantly associated with the experience of MCs (adjusted odds ratio (AOR): 2.05, 95% confidence interval (CI): 1.15-4.01), OCs (AOR: 4.23, 95% CI: 2.01-7.12) and AC (AOR: 5.26, 95% CI: 2.98-10.52). Women who experienced sexual IPV during pregnancy were also at increased risk of suffering from any MC, any OC, and AC. Maternal experience of IPV during pregnancy is positively associated with pregnancy complications. Preventing IPV directed at pregnant women might reduce maternal morbidity and mortality in Bangladesh.

Stimulated mass enhancement strategy-based highly sensitive detection of a protein in serum using quartz crystal microbalance technique.

A stimulated mass enhancement strategy based on enormous biocatalytic precipitation of 4-chloro-1-naphthol using magnetic bead-supported horseradish peroxidase and glucose oxidase bienzymes was developed for the highly sensitive detection of interleukin-6 in serum using a quartz crystal microbalance technique.

Preparation, characterization, and adsorption kinetics of graphene oxide/chitosan/carboxymethyl cellulose composites for the removal of environmentally relevant toxic metals.

This study attempted to develop a low-cost and eco-friendly bio-based composite adsorbent that is highly efficient in capturing potential toxic metals. The bio-composite adsorbent was prepared using graphene oxide (GO), carboxymethyl cellulose (CMC) and chitosan (CS); and characterized using FTIR, SEM-EDX and WAXD techniques. Metal-ion concentration in an aqueous solution was measured by ICP-OES. This article reveals that the adsorption of heavy metal ions varied according to the adsorbent quantity, initial metal concentration, pH, and interaction time. The metal ions' adsorption capacity (mg/g) was observed to increase when the interaction time and metal concentration increased. Conversely, metal ions adsorption was decreased with an increase in adsorbent dosages. The effect of pH on metal ions' adsorption was ion-specific. The substantial adsorption by GO/CMC/CS composite for Co2+, CrO42-, Mn2+ and Cd2+, had the respective values of 43.55, 77.70, 57.78, and 91.38 mg/g under acidic conditions. The metal ions experimental data were best fitted with pseudo-second-order (PSO) kinetics, and Freundlich isotherm model (except Co2+). The separation factors (RL) value in the present investigation were found between 0 and 1, meaning that the metal ions adsorption onto GO/CS/CMC composite is favorable. The RL and sorption intensity (1/n) values fitted well to the adsorption isotherm.

Increased electrocatalyzed performance through dendrimer-encapsulated gold nanoparticles and carbon nanotube-assisted multiple bienzymatic labels: highly sensitive electrochemical immunosensor for protein detection.

A highly sensitive electrochemical carcinoembryonic antigen (CEA) immunosensor was fabricated by covalently immobilizing a monoclonal CEA antibody (anti-CEA, Ab(1)) and a mediator (thionine, Th) on a gold nanoparticle (AuNP)-encapsulated dendrimer (Den/AuNP). Multiwalled carbon nanotube (MWCNT)-supported secondary antibody (Ab(2))-conjugated multiple bienzymes, glucose oxidase (GOx), and horseradish peroxidase (HRP) (Ab(2)/MWCNT/GOx/HRP) were used as electrochemical labels. The highly sensitive detection was achieved by the increased HRP-electrocatalyzed reduction of hydrogen peroxide, which was locally generated by the enzyme GOx. The immunosensor surface was characterized using electrochemical impedance spectroscopy, atomic force microscopy, and quartz crystal microbalance techniques. The Den/AuNP and Ab(2)/MWCNT/GOx/HRP bioconjugates were characterized using high-resolution transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry and square wave voltammetry techniques were used to monitor the increased electrocatalyzed reduction of hydrogen peroxide by HRP. The linear dynamic range and the detection limit were determined to be 10.0 pg/mL to 50.0 ng/mL and 4.4 ± 0.1 pg/mL, respectively. The validity of the immunosensor response was tested in various CEA-spiked human serum samples, and the results were compared to those of an enzyme-linked immunosorbent assay method.

Continuation of education after marriage and its associated factors among young adult women: findings from the Bangladesh Demographic and Health Survey 2017-2018.

OBJECTIVE: To identify the individual and community-level variables associated with the continuation of education among currently married young adult women in Bangladesh. DESIGN: Cross-sectional data extracted from the Bangladesh Demographic and Health Survey (BDHS), 2017-2018. The BDHS is a stratified cluster sample of households conducted in two and three stages in both rural and urban settings. A multilevel multinomial logistic regression analysis was employed to identify the associated factors. SETTING: Bangladesh. PARTICIPANTS: Currently married young adult women aged 15-29 years (n=4595). PRIMARY OUTCOME: Continuation of education after marriage was measured in the BDHS by asking respondents, 'Did you continue your studies after marriage?' with the response options: no; yes, less than a year; yes, for 1-2 years; yes, for 3-4 years; and yes, for 5+ years. RESULTS: Among young adult women, 28.2% continued education after marriage for different durations of years (<1 year to 5+ years). The odds of continuing education after marriage for <1 year (adjusted OR (aOR): 0.68; 95% CI 0.50 to 0.90), 1-2 years (aOR: 0.67; 95% CI 0.47 to 0.96) and ≥5 years (aOR: 0.38; 95% CI 0.17 to 0.85) were lower among women who justified wife beating compared with women who did justify it. Compared with the high-literate community, women from the low-literate community were less likely to continue education after marriage for <1 year (aOR: 0.53; 95% CI 0.42 to 0.66), 1-2 years (aOR: 0.47; 95% CI 0.36 to 0.61), 3-4 years (aOR: 0.32; 95% CI 0.22 to 0.46), and for ≥5 years (aOR: 0.29; 95% CI 0.17 to 0.48). Several other individual-level and community-level variables, such as age at marriage, first birth interval, partner educational status, household wealth index, community economic status and region, were found to be associated with the continuation of education after marriage for different durations. CONCLUSIONS: The proportion of women continuing their education after marriage in this sample is low. This study provides insight into the individual-level and community-level barriers women encounter in continuing their education after marriage. The identification of these barriers helps policy-makers develop effective intervention programmes to promote women's educational attainment.

A Comprehensive Review of the Current Progress of Chromium Removal Methods from Aqueous Solution.

Chromium (Cr) exists in aqueous solution as trivalent (Cr3+) and hexavalent (Cr6+) forms. Cr3+ is an essential trace element while Cr6+ is a dangerous and carcinogenic element, which is of great concern globally due to its extensive applications in various industrial processes such as textiles, manufacturing of inks, dyes, paints, and pigments, electroplating, stainless steel, leather, tanning, and wood preservation, among others. Cr3+ in wastewater can be transformed into Cr6+ when it enters the environment. Therefore, research on Cr remediation from water has attracted much attention recently. A number of methods such as adsorption, electrochemical treatment, physico-chemical methods, biological removal, and membrane filtration have been devised for efficient Cr removal from water. This review comprehensively demonstrated the Cr removal technologies in the literature to date. The advantages and disadvantages of Cr removal methods were also described. Future research directions are suggested and provide the application of adsorbents for Cr removal from waters.

Determination of bioavailable arsenic threshold and validation of modeled permissible total arsenic in paddy soil using machine learning.

Minimizing arsenic intake from food consumption is a key aspect of the public health response in arsenic (As)-contaminated regions. In many of these regions, rice is the predominant staple food. Here, we present a validated maximum allowable concentration of total As in paddy soil and provide the first derivation of a maximum allowable soil concentration for bioavailable As. We have previously used meta-analysis to predict the maximum allowable total As in soil based on decision tree (DT) and logistic regression (LR) models. The models were defined using the maximum tolerable concentration (MTC) of As in rice grains as per the codex recommendation. In the present study, we validated these models using three test data sets derived from purposely collected field data. The DT model performed better than the LR in terms of accuracy and Matthews correlation coefficient (MCC). Therefore, the DT estimated maximum allowable total As in paddy soil of 14 mg kg-1 could confidently be used as an appropriate guideline value. We further used the purposely collected field data to predict the concentration of bioavailable As in the paddy soil with the help of random forest (RF), gradient boosting machine (GBM), and LR models. The category of grain As (MTC) was considered as the dependent variable; bioavailable As (BAs), total As (TAs), pH, organic carbon (OC), available phosphorus (AvP), and available iron (AvFe) were the predictor variables. LR performed better than RF and GBM in terms of accuracy, sensitivity, specificity, kappa, precision, log loss, F1score, and MCC. From the better-performing LR model, bioavailable As (BAs), TAs, AvFe, and OC were significant variables for grain As. From the partial dependence plots (PDP) and individual conditional expectation (ICE) of the LR model, 5.70 mg kg-1 was estimated to be the limit for BAs in soil.

Heavy Metals in Widely Consumed Vegetables Grown in Industrial Areas of Bangladesh: a Potential Human Health Hazard.

The prevalence of heavy metals in frequently consumed vegetables constitutes a considerable public health hazard. This study aims to determine the quantity of heavy metals in widely consumed watercress (WC), alligator weed (AW), red amaranth (RA), spinach (SP), cauliflower (CF), and eggplant (EP) cultivated in industrial areas (e.g., Narsingdi district) of Bangladesh to assess the potential health hazards. Atomic absorption spectroscopy (AAS) served to determine the concentrations of lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni) in vegetable samples (n = 72). The contents of Pb, Cd, Cr, and Ni were found in most of the analyzed vegetables, whereas 79.17%, 44.44%, and 1.39% samples exceeded the FAO/WHO maximum allowable concentration (MAC) for Pb, Cd, and Ni, respectively. The estimated daily intake (EDI) of single heavy metal was below the corresponding maximum tolerable daily intake (MTDI). The incremental lifetime cancer risk (ILCR) values of Cd in all samples exceeded the threshold limit (ILCR > 10-4) for both adults and children, indicating lifetime cancer risk due to the consumption of contaminated vegetables. The target hazard quotient (THQ) of each heavy metal was THQ < 1.0 (except Ni in few samples), indicating that consumers have no non-cancer risk when exposed to a single heavy metal. However, hazard index (HI) values of heavy metals were greater than unity in contaminated WC and AW for adults and children. Meanwhile, WC, AW, and SP samples for children emerged as potential health risks of inhabitants in the studied areas. The outcomes of the present investigation might assist the regulatory bodies concerned in setting new strategies through monitoring the quality of marketed vegetables to minimize the risks to humans.

Amplified electrochemical detection of a cancer biomarker by enhanced precipitation using horseradish peroxidase attached on carbon nanotubes.

An electrochemical nanoimmunosensor based on multiwall carbon nanotubes (MWCNTs)/gold nanoparticles (AuNPs) was developed for the amplified detection of prostate specific antigen (PSA). The amplified detection was achieved by the enhanced precipitation of 4-chloro-1-naphthol (CN) using a higher number of horseradish peroxidase (HRP) molecules attached on MWCNTs. The PSA nanoimmunosensor was fabricated by immobilizing a monoclonal anti-PSA antibody (anti-PSA) on the AuNP-attached thiolated MWCNT on a gold electrode. The sensor surface was characterized using scanning electron microscope, transmission electron microscope, quartz crystal microbalance, and electrochemical techniques. Cyclic and square wave voltammetric techniques were used to monitor the enhanced precipitation of CN that accumulated on the electrode surface and subsequent decrement in the electrode surface area by monitoring the reduction process of the Fe(CN)(6)(3-)/Fe(CN)(6)(4-) redox couple. Under the optimized experimental condition, the linear range and the detection limit of PSA immunosensor were determined to be 1.0 pg/mL to 10.0 ng/mL and 0.40 ± 0.03 pg/mL, respectively. The validity of the proposed method was compared with an enzyme-linked immunosorbent assay method in various PSA spiked human serum samples.

Stability and sensitivity enhanced electrochemical in vivo superoxide microbiosensor based on covalently co-immobilized lipid and cytochrome c.

Enhanced stability and sensitivity of a superoxide anion radical (O(2)(•-)) microbiosensor were achieved through the sequential immobilization of lipid and cytochrome c (Cyt c) covalently bonded onto a conducting polymer layer that showed a clear quasi-reversible direct electron transfer (DET) process. The formal potential and the apparent standard rate constant were determined to be -0.24 V and 0.62 ± 0.05 s(-1), respectively. The detection of O(2)(•-) was attained through the catalytic activity of the haem group of Cyt c stabilized by coimmobilized lipid molecules (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-n-dodecanylamine (DGPD)). The linear dynamic range and the detection limit of the O(2)(•-) analysis were determined to be 0.2-6.0 nM and 30.0 ± 0.9 pM, respectively. The in vivo microbiosensor implanted into rat brain successfully determined the extracellular level of O(2)(•-) produced by acute and repeated injections of cocaine. The present O(2)(•-) microbiosensor could be an effective tool for monitoring the change in extracellular O(2)(•-) levels in response to stimulant drug exposure.

Adsorption-Desorption Behavior of Arsenate Using Single and Binary Iron-Modified Biochars: Thermodynamics and Redox Transformation.

Arsenic (As) is a dangerous contaminant in drinking water which displays cogent health risks to humans. Effective clean-up approaches must be developed. However, the knowledge of adsorption-desorption behavior of As on modified biochars is limited. In this study, the adsorption-desorption behavior of arsenate (AsV) by single iron (Fe) and binary zirconium-iron (Zr-Fe)-modified biosolid biochars (BSBC) was investigated. For this purpose, BSBC was modified using Fe-chips (FeBSBC), Fe-salt (FeCl3BSBC), and Zr-Fe-salt (Zr-FeCl3BSBC) to determine the adsorption-desorption behavior of AsV using a range of techniques. X-ray photoelectron spectroscopy results revealed the partial reduction of pentavalent AsV to the more toxic trivalent AsIII form by FeCl3BSBC and Zr-FeCl3BSBC, which was not observed with FeBSBC. The Langmuir maximum AsV adsorption capacities were achieved as 27.4, 29.77, and 67.28 mg/g when treated with FeBSBC (at pH 5), FeCl3BSBC (at pH 5), and Zr-FeCl3BSBC (at pH 6), respectively, using 2 g/L biochar density and 22 ± 0.5 °C. Co-existing anions reduced the AsV removal efficiency in the order PO4 3- > CO3 2- > SO4 2- > Cl- > NO3 -, although no significant inhibitory effects were observed with cations like Na+, K+, Mg2+, Ca2+, and Al3+. The positive correlation of AsV adsorption capacity with temperature demonstrated that the endothermic process and the negative value of Gibbs free energy increased (-14.95 to -12.47 kJ/mol) with increasing temperature (277 to 313 K), indicating spontaneous reactions. Desorption and regeneration showed that recycled Fe-chips, Fe-salt, and Zr-Fe-salt-coated biochars can be utilized for the effective removal of AsV up to six-repeated cycles.

Rare earth elements (REE) for the removal and recovery of phosphorus: A review.

There is little doubt that 'rock phosphate' reserves are decreasing, with phosphorus (P) peak to be reached in the coming decades. Hence, removal and recovery of phosphorus (P) from alternative nutrient-rich waste streams is critical and of great importance owing to its essential role in agricultural productivity. Adsorption technique is efficient, cost-effective, and sustainable for P recovery from waste streams which otherwise can cause eutrophication in receiving waters. As selective P sorption using rare earth elements (REE) are gaining considerable attention, this review extensively focuses on P recovery by utilising a range of REE-incorporated adsorbents. The review briefly provides existing knowledge of P in various waste streams, and examines the chemistry and behaviour of REE in soil and water in detail. The impact of interfering ions on P removal using REE, adsorbent regeneration for reuse, and life cycle assessment of REE are further explored. While it is clear that REE-sorbents have excellent potential to recover P from wastewaters and to be used as fertilisers, there are gaps to be addressed. Future studies should target recovery and reuse of REE as P fertilisers using real wastewaters. More field trials of synthesized REE-sorbents are highly recommended before practical application.

Lead and other elements-based pollution in soil, crops and water near a lead-acid battery recycling factory in Bangladesh.

Lead (Pb) pollution in the environment predominantly occurs through anthropogenic activities, which pose significant threats to human health and that of biota. In this study, Pb and other elements were investigated in different soils (n = 52), crops (n = 24) and water (n = 13) around a lead-acid battery (LAB) recycling workshop in southwestern Bangladesh. Most of the elements' concentrations (except Se and Ag) in soil were lower than the background concentrations. However, excessive concentrations of Pb were found in both surface (966 ± 2414 mg kg-1 at 0-15 cm) and subsurface (230 ± 490 mg kg-1 at 15-30 cm) soil. Although no definitive pattern or direction in elemental concentration in soil was observed, relatively higher concentrations of most elements were detected at the southeast part of the factory. The LAB factory, brick kiln, agricultural and geogenic activities might be the sources of these elements in soil. Extremely high amounts of Cr, As, Cd, and Pb were found in the food crops around the area. In particular, the Pb concentrations were 114 ± 155 and 665 ± 588 mg kg -1 dry weight in rice grain and straw, respectively, which reflected the emissions of Pb from the LAB recycling workshop. Moreover, 40% and 100% of the groundwater samples exceeded, respectively, the WHO provisional guideline values for As (0.01 mg L-1) and Pb (0.05 mg L-1). Consequently, a high level of Pb contamination in the soil was observed while assessing different soil pollution indices. Human health risk assessment indicated severe carcinogenic (from Pb, As, and Cr intake) and non-carcinogenic (from Pb, As, Co, Cr, Ni and Sb intake) health risks are associated with rice and groundwater consumption. It is concluded that all LAB recycling workshops should be better managed to prevent Pb pollution from seeping into the environment.

Novel electrochemical PMI marker biosensor based on quantum dot dissolution using a double-label strategy.

A novel and facile post-mortem interval (PMI) biosensor was fabricated using a double-label strategy to detect the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) biomarker. A monoclonal anti-GAPDH antibody was immobilized on a surface label containing cadmium selenide quantum dots (CdSe QDs) on a cysteamine graphene oxide (Cys-GO) self-assembled monolayer. Glucose oxidase (GOx) was used as a signal label to conjugate with GAPDH. GAPDH recognition was achieved through the dissolution of the surface-attached CdSe QDs by hydrogen peroxide generated through GAPDH-conjugated GOx-catalyzed ß-glucose oxidation. To enhance sensitivity, a competitive interaction was introduced between free and conjugated GAPDH to the active site of the anti-GAPDH antibody. The electrochemical response due to CdSe dissolution decreased proportionally with the concentration of free GAPDH. Differential pulsed voltammetry was conducted to determine the analytical characteristics of the immunosensor, including the limit of detection, linear dynamic range, target selectivity, system stability, and applicability toward the analysis of real samples.

Varietal differences influence arsenic and lead contamination of rice grown in mining impacted agricultural fields of Zamfara State, Nigeria.

In Zamfara state, Nigeria, rice is cultivated in fields contaminated with Pb (lead) from artisanal and illicit mining activities. Rice grown in such contaminated agricultural areas risks not only Pb contamination but also contamination from other toxic elements, like arsenic (As); co-contamination of Pb and As in rice cultivated in mining impacted areas has been previously reported and rice is a hyperaccumulator of As. A field study was conducted with ten different commonly-cultivated Nigerian rice varieties in the mining-impacted farmlands of Dareta village, Zamfara State. The aim was to determine the optimal rice variety for cultivation on these contaminated farmlands; an optimal variety would have the lowest contaminant concentrations and highest essential elements concentrations in the rice grains. A total of 300 paired soil and rice plants were collected. The mean As and Pb concentrations in paddy soils were 0.91 ± 0.82 mg kg-1 and 288.5 ± 464.2 mg kg-1, respectively. Mean As (30.4 ± 15.1 µg kg-1) content in rice grains was an order of magnitude lower than the Codex recommendation of 200 µg kg-1 (for milled rice) while the Pb content in all the rice varieties (overall mean of 743 ± 327 µg kg-1) was approximately four times higher than the Codex recommendation of 200 µg kg-1. Contrary to previous studies, a negative correlation was observed between As and Pb in rice grains across all the varieties. Rice variety Bisalayi was the variety with the lowest Pb transfer factor (TF = 0.08), but the average Pb concentration in rice grain was still above the Codex recommendation. Bisalayi also had the highest TF for iron. Variety ART_15, which had the lowest As uptake (TF = 0.10), had the highest TF for essential elements (magnesium, potassium, manganese, zinc, and copper). In areas of Pb contamination, Bisalayi rice may therefore be a suitable variety to choose for cultivation.