Flow injection online spectrophotometric determination of uranium after preconcentration on XAD-4 resin impregnated with nalidixic acid

In this work, spectrophotometer was used as a detector for the determination of uranium from water, biological, and ore samples with a flow injection system coupled with solid phase extraction. In order to promote the online preconcentration of uranium, a minicolumn packed with XAD-4 resin impregnated with nalidixic acid was utilized. The system operation was based on U(VI) ion retention at pH 6 in the minicolumn at flow rate of 15.2 mL min^?1. The uranium complex was removed from the resin by 0.1 mol dm^?3 HCl at flow rate of 3.2 mL min^?1 and was mixed with arsenazo III solution (0.05 % solution in 0.1 mol dm^?3 HCl, 3.2 mL min^?1) and driven to flow through cell of spectrophotometer where its absorbance was measured at 651 nm. The influence of chemical (pH and HCl (as eluent and reagent medium) concentration) and flow (sample and eluent flow rate and preconcentration time) parameters that could affect the performance of the system as well as the possible interferents was investigated. At the optimum conditions for 60 s preconcentration time (15.2 mL of sample volume), the method presented a detection limit of 1.1 μg L^?1, a relative standard deviation (RSD) of 0.8 % at 100 μg L^?1, enrichment factor of 30, and a sample throughput of 42 h^?1, whereas for 300 s of the preconcentration time (76 mL of sample volume), a detection limit of 0.22 μg L^?1, a RSD of 1.32 % at 10 μg L^?1, enrichment factor of 150, and a sampling frequency of 11 h^?1 were reported.     

Selenium in surface and irrigation water in the Kendrick irrigation district, Wyoming

High selenium (Se) concentrations have been found in surface waters in the Kendrick Reclamation Project, Wyoming. Precipitation and irrigation water moving over seleniferous soils are contributing causes, and drought may exacerbate this. This study surveyed Se concentrations and discharges in local surface streams, irrigation drains, and the delivery canal. Sites were sampled monthly and analyzed for Se and total suspended solids (TSS). A completely randomized design with two factors (soil parent material and location, inside or outside irrigation district) was used. Mean Se concentrations were 64 μg L^???1 inside the irrigation district on shale soils, 17 μg L^???1 inside the district off shale soils, 5 μg L^???1 outside the district on shale soils, and 3 μg L^???1 outside the district off shale soils. Correlations between discharge and Se concentrations were generally negative, while correlations between discharge and Se load were generally positive. There was little correlation between load and concentration, and little correlation between TSS and Se. A comparison of Se concentrations in streams and drains showed Se concentrations were significantly higher (p?<?0.001) in streams during the irrigation season, but not in the off-season (p?=?0.515). We conclude that higher discharges decrease Se concentration, but increase load. Conversion from flood to sprinkle irrigation may increase Se concentrations by reducing discharge, but decrease Se loads going into the N. Platte River, and will likely alter the timing and magnitude of flows. Both load and concentration should be considered when implementing Se regulations and standards.     

Hazard assessment of metals in invasive fish species of the Yamuna River,India in relation to bioaccumulation factor and exposure concentration for human health implications

Monitoring of heavy metals was conducted in the Yamuna River considering bioaccumulation factor, exposure concentration, and human health implications which showed contamination levels of copper (Cu), lead (Pb), nickel (Ni), and chromium (Cr) and their dispersion patterns along the river. Largest concentration of Pb in river water was 392 μg L^?1; Cu was 392 μg L^?1 at the extreme downstream, Allahabad and Ni was 146 μg L^?1 at midstream, Agra. Largest concentration of Cu was 617 μg kg^?1, Ni 1,621 μg kg^?1 at midstream while Pb was 1,214 μg kg^?1 at Allahabad in surface sediment. The bioconcentration of Cu, Pb, Ni, and Cr was observed where the largest accumulation of Pb was 2.29 μg kg^?1 in Oreochromis niloticus and 1.55 μg kg^?1 in Cyprinus carpio invaded at Allahabad while largest concentration of Ni was 174 μg kg^?1 in O. niloticus and 124 μg kg^?1 in C. carpio in the midstream of the river. The calculated values of hazard index (HI) for Pb was found more than one which indicated human health concern. Carcinogenic risk value for Ni was again high i.e., 17.02?×?10^?4 which was larger than all other metals studied. The results of this study indicated bioconcentration in fish due to their exposures to heavy metals from different routes which had human health risk implications. Thus, regular environmental monitoring of heavy metal contamination in fish is advocated for assessing food safety since health risk may be associated with the consumption of fish contaminated through exposure to a degraded environment.     

Evaluation of optimal conditions for determination of low selenium content in shellfish samples collected at Todos os Santos Bay,Bahia, Brazil using HG-AFS

This work proposes a procedure for the determination of total selenium content in shellfish after digestion of samples in block using cold finger system and detection using atomic fluorescent spectrometry coupled hydride generation (HG AFS). The optimal conditions for HG such as effect and volume of prereduction KBr 10 % (m/v) (1.0 and 2.0 ml) and concentration of hydrochloric acid (3.0 and 6.0 mol L^?1) were evaluated. The best results were obtained using 3 mL of HCl (6 mol L^?1) and 1 mL of KBr 10 % (m/v), followed by 30 min of prereduction for the volume of 1 mL of the digested sample. The precision and accuracy were assessed by the analysis of the Certified Reference Material NIST 1566b. Under the optimized conditions, the detection and quantification limits were 6.06 and 21.21 μg kg^?1, respectively. The developed method was applied to samples of shellfish (oysters, clams, and mussels) collected at Todos os Santos Bay, Bahia, Brazil. Selenium concentrations ranged from 0.23?±?0.02 to 3.70?±?0.27 mg kg^?1 for Mytella guyanensis and Anomalocardia brasiliana, respectively. The developed method proved to be accurate, precise, cheap, fast, and could be used for monitoring Se in shellfish samples.     

Solid-phase extraction and separation procedure for trace aluminum in water samples and its determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS)

In the present study, a separation/preconcentration procedure for determination of aluminum in water samples has been developed by using a new atomic absorption spectrometer concept with a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double-echelle monochromator, and a charge-coupled device array detector. Sample solution pH, sample volume, flow rate of sample solution, volume, and concentration of eluent for solid-phase extraction of Al chelates with 4-[(dicyanomethyl)diazenyl] benzoic acid on polymeric resin (Duolite XAD-761) have been investigated. The adsorbed aluminum on resin was eluted with 5 mL of 2 mol L^-1 HNO₃ and its concentration was determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimal conditions, limit of detection obtained with HR-CS FAAS and Line Source FAAS (LS-FAAS) were 0.49 μg L^?1 and 3.91 μg L^?1, respectively. The accuracy of the procedure was confirmed by analyzing certified materials (NIST SRM 1643e, Trace elements in water) and spiked real samples. The developed procedure was successfully applied to water samples.     

Seasonal perspective of dietary arsenic consumption and urine arsenic in an endemic population

Exposure to arsenic in arsenic endemic areas is most remarkable environmental health challenges. Although effects of arsenic contamination are well established, reports are unavailable on probable seasonal variation due to changes of food habit depending on winter and summer seasons, especially for endemic regions of Nadia district, West Bengal. Complete 24-h diets, drinking–cooking water, first morning voided urine samples, and diet history were analyzed on 25 volunteers in arsenic endemic Chakdah block of Nadia district, once in summer followed by once in winter from the same participants. Results depicted no seasonal variation of body weight and body mass index. Arsenic concentration of source drinking and cooking water decreased (p?=?0.04) from 26 μg L^?1 in summer to 6 μg L^?1 in winter season. We recorded a seasonal decrease of water intake in male (3.8 and 2.5 L day ^?1) and female (2.6 and 1.2 L day^?1) participants from summer to winter. Arsenic intake through drinking water decreased (p?=?0.04) in winter (29 μg day^?1) than in summer (100 μg day^?1), and urinary arsenic concentration decreased (p?=?0.018) in winter (41 μg L^?1) than in summer (69 μg L^?1). Dietary arsenic intake remained unchanged (p?=?0.24) over the seasons. Hence, we can infer that human health risk assessment from arsenic needs an insight over temporal scale.     

FIA-coupled spectrophotometric method for determination of Cr (VI) traces in natural waters: application of in-line dissolution of 1,5-diphenylcarbazide after heat treatment and activated alumina as adsorbent for preconcentration

This work proposes the quantification of Cr (VI) ions in natural waters in trace level, using activated alumina (Al₂O₃) as preconcentration support, controlled in-line dissolution of the solidified chromophore diphenylcarbazide after heat treatment and spectrophotometric detection. The manifold ensures high sensitivity of analytical response, good repeatability, and stability. In this work, optimization of experimental conditions of a flow injection system was chosen as the parameters for greater sensitivity and better selectivity. The selected optimized conditions were 0.30 mol L^?1 for H₂SO₄ concentration, system flow rate as 0.40 mL min^?1, sample injection volume of 192.50 μL, 2 min for preconcentration time, and 0.10 mol L^?1 for eluent concentration. The analytical curves obtained for real sample analysis show linear range from 0.192 to 0.961 μM, linear correlation coefficient R?=?0.9997 and LOD?=?0.024 μM. The preconcentration factor of about four times was obtained through the passage of 800 μL of a standard solution containing 0.961 μM of Cr (VI) through mini-column of preconcentration followed by elution at 192.5 μL of NH₄OH 0.1 mol L^?1 solution. The solid chromogenic reagent presented high durability (weeks in daily use with mass of 0.0993 g) and good reproducibility in analytical signal. The reactivation of the mini-column of alumina should be executed after ten injections of eluent, using 800 μL of HCl 0.02 mol L^?1 solution in flow through the same. Each cycle of injection and elution of the sample takes about 5 min on the proposed terms. Despite the length of each cycle still be high, low concentrations can be detected using a technique of relatively low cost. This is due in part, the association dissolution of the chromogenic reagent directly in the line and the preconcentration step. Another important factor is the economy of reagent chromogenic, low generation of reject contributing to better quality of the environment, and the high potential for applications to work in field.     

Removing arsenic from groundwater in Cambodia using high performance iron adsorbent

In Cambodia, groundwater has been contaminated with arsenic, and purification of the water is an urgent issue. From 2010 to 2012, an international collaborative project between Japan and Cambodia for developing arsenic-removing technology from well water was conducted and supported by the foundation of New Energy and Industrial Technology Development Organization, Japan. Quality of well water was surveyed in Kandal, Prey Veng, and Kampong Cham Provinces, and a monitoring trial of the arsenic removal equipment using our patented amorphous iron (hydr)oxide adsorbent was performed. Of the 37 wells surveyed, arsenic concentration of 24 exceeded the Cambodian guideline value (50 μg L^?1), and those of 27 exceeded the WHO guideline for drinking water (10 μg L^?1). Levels of arsenic were extremely high in some wells (>1,000–6,000 μg L^?1), suggesting that arsenic pollution of groundwater is serious in these areas. Based on the survey results, 16 arsenic removal equipments were installed in six schools, three temples, two health centers, four private houses, and one commune office. Over 10 months of monitoring, the average arsenic concentrations of the treated water were between 0 and 10 μg L^?1 at four locations, 10–50 μg L^?1 at eight locations, and >50 μg L^?1 at four locations. The arsenic removal rate ranged in 83.1–99.7 %, with an average of 93.8 %, indicating that the arsenic removal equipment greatly lower the risk of arsenic exposure to the residents. Results of the field trial showed that As concentration of the treated water could be reduced to <10 µg L^?1 by managing the As removal equipment properly, suggesting that the amorphous iron (hydr)oxide adsorbent has high adsorbing capacity for As not only in the laboratory environment but also in the field condition. This is one of the succeeding As removal techniques that could reduce As concentration of water below the WHO guideline value for As in situ.     

A very sensitive flow-injection spectrophotometric determination method for iron (II) and total iron using 2′, 3, 4′, 5, 7-pentahydroxyflavone

In this study, an ultra-sensitive and highly selective, rapid flow-injection spectrophotometric method for the determination of iron (II) and total iron has been proposed. The method was based on the reaction between iron (II) and 2′, 3, 4′, 5, 7-pentahydroxyflavone in slightly acidic solution with a strong absorption at 415 nm. The carrier solution used was 1?×?10^?5 M 2′, 3, 4′, 5, 7-pentahydroxyflavone in 0.1 M HAc/Ac^? buffer solution at pH 4.5. Parameters that affect simultaneously the determination of iron (II) and interfering ions were tested. The relative standard deviation for the determination of 50 μg L^?1 iron (II) was 0.85 % (n?=?10), and the limit of detection (blank signal plus three times the standard deviation of the blank) was 3 μg L^?1, both based on injection volumes of 20 μL. The method has been successfully applied to the determination of iron (II) and total iron in water samples and ore samples. The method was verified by analysing a certified reference material Zn/Al/Cu 43XZ3F.     

Spatial and seasonal distribution of 17 endocrine disruptor compounds in an urban estuary (Mondego River,Portugal): evaluation of the estrogenic load of the area

The Mondego River estuary demonstrates signs of pollution, but the levels of endocrine disrupting compounds (EDCs), such as the natural (17β-estradiol and estrone) and pharmaceutical (17α-ethynylestradiol) estrogens, xenoestrogenic industrial pollutants (4-octylphenol, 4-nonylphenol, and their mono- and diethoxylates and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, and genistein), and sitosterol were either poorly or never measured in this area. Thus, to conclude about the influx of EDCs in this estuary, water samples were taken every 2 months, during 1 year (2010) in low tide, at eight sites distributed along the estuary. Water samples (1 L) were preconcentrated in the Oasis HLB cartridges and cleaned in silica cartridges before their analysis by GC-MS. In summer, potentially hazardous amounts of estrogens (≈26 ng L^?1), alkylphenols (≈11.5 μg L^?1), alkylphenolethoxylates (≈13 μg L^?1), and phytoestrogens (≈5.6 μg L^?1) were measured. These data suggest that changes in the hydrodynamics of the estuary coupled with the increase of water temperatures interfere with the amount of EDCs in the water. Complementary physicochemical parameters also point to high levels of anthropogenic pollution in this area. Globally, the estrogenic load, expressed in ethynylestradiol equivalents, attained 71.8 ng L^?1 demonstrating that, all together, the measured EDCs pose important health risks for both biota and humans.     

Single drop microextraction and gas chromatography–mass spectrometry for the determination of diflufenican, mepanipyrim, fipronil, and pretilachlor in water samples

An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography–mass spectrometry. A factorial fractionated design of type 2^6–1 at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 μL of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 μg L^?1 for diflufenican, 0.03 μg L^?1 for mepanipyrim, 0.08 μg L^?1 for pretilachlor, and 1.39 μg L^?1 for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples.     

Assessment of cylindrospermopsin toxin in an arid Saudi lake containing dense cyanobacterial bloom

This study reports the presence of the cyanobacterial toxin cylindrospermopisn (CYN) and its producer Cylindrospermopsis raciborskii for the first time in Saudi freshwater sources. C. raciborskii was found in Gazan Dam Lake water with two morphotypes (coiled and straight). The appearance and cell density of this species was significantly positively related to high temperature and high ammonium concentrations, and negatively with nitrate and phosphate concentrations in the lake. Intracellular concentrations of CYN (4–173 μg L^?1) were associated with C. raciborskii rather than other cyanobacteria with a maximal value obtained in June 2011, coinciding with the highest bloom of this species (19?×?10⁷ trichome L^?1). CYN cell quotas (0.6–14.6 pg cell^?1) varied significantly along the study period and correlated with most environmental factors. The results of ELISA and liquid chromatography-mass spectrometry proved that the CYN production by strains of this species was isolated from this lake during the present study, with an amount reaching 568 μg g^?1. Extracellular CYN was also detected in cell-free lake water at concentrations 0.03–23.3 μg L^?1, exceeding the drinking water guideline value of 1 μg L^?1 during the Apr–Jul period. As this lake is an important source for drinking and irrigation waters, CYN monitoring should be included in the environmental and health risk assessment plans of these water bodies.     

Coupling of solvent-based de-emulsification dispersive liquid–liquid microextraction with high performance liquid chromatography for simultaneous simple and rapid trace monitoring of 2,4-dichlorophenoxyacetic acid and 2-methyl-4-chlorophenoxyacetic acid

A simple, rapid, and efficient sample pretreatment technique, based on solvent-based de-emulsification dispersive liquid–liquid microextraction (SD-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in water and urine samples. Some parameters such as acidity of solution, the amount of salt, type, and volume of extraction solvents, type of disperser/de-emulsifier solvent, and its volume were investigated and optimized. Under optimum extraction conditions, the limits of detections (LODs) of this method for MCPA and 2,4-D were 0.2 and 0.6 μg L^?1 (based on 3S_b/m) in water and 0.4 and 1.6 μg L^?1 in urine, respectively. Furthermore, dynamic linear range of this method for MCPA and 2,4-D was 1–300 and 2–400 μg L^?1, repectively. Finally, the applicability of the proposed method was evaluated by extraction and determination of the herbicides in urine and different water samples.     

Stability of lysosomal membrane in Carcinus maenas acts as a biomarker of exposure to pharmaceuticals

The presence of pharmaceuticals in the environment is now a major concern given their potential adverse effects on organisms, particularly human beings. Because the feeding style and habitat of the crab Carcinus maenas make this species vulnerable to organic contaminants, it has been used previously in ecotoxicological studies. Lysosomal membrane stability (LMS) in crabs is a general indicator of cellular well-being and can be visualized by the neutral red retention (NRR) assay. LMS in crab hemolymph has been evaluated as a cellular biomarker of adverse effects produced by exposure to pharmaceutical compounds. Crabs were exposed in the laboratory to four different pharmaceuticals for 28 days in a semistatic 24-h renewal assay. Filtered seawater was spiked every 2 days with various concentrations (from 0.1 to 50 μg·L^?1) of caffeine, ibuprofen, carbamazepine, and novobiocin. Results showed that NRR time, measured at day 28, was significantly reduced (p?<?0.05) after exposure to environmental concentrations of each pharmaceutical (caffeine?=?15 μg·L^?1; carbamazepine?=?1 μg·L^?1; ibuprofen?=?5 μg·L^?1; and novobiocin?=?0.1 μg·L^?1) when compared with control organisms. The predicted “no environmental effect” concentration/measured environmental concentration results showed that the selected pharmaceuticals are toxic at environmental concentrations and need further assessment. LMS monitoring in crabs is a sensitive tool for evaluating exposure to concentrations of selected drugs under laboratory conditions and provides a robust tier 1 testing approach (screening biomarker) for rapid assessment of marine pollution and environmental impact assessments for analyzing pharmaceutical contamination in aquatic environments.     

The use of rapidly synergistic cloud point extraction for the separation and preconcentration of trace amounts of Ni (II) ions from food and water samples coupling with flame atomic absorption spectrometry determination

A novel improved preconcentration method known as rapidly synergistic cloud point extraction (RS-CPE) was established for nickel preconcentration and determination prior to its determination by flame atomic absorption spectrometry. In this work, the traditional CPE pattern was changed and greatly simplified in order to be applicable in metal extraction and detection. This method was accomplished in room temperature in 1 min. Non-ionic surfactant Triton X-114 was used as extractant. Octanol worked as cloud point revulsant and synergic reagent. The various parameters affecting the extraction and preconcentration of nickel such as sample pH, 2,2′-Furildioxime concentration, amounts of octanol, amounts of Triton X-114, type of diluting solvent, extraction time, and ionic strength were investigated and optimized. Under optimal conditions, the calibration curve showed an excellent linearity in the concentration range of 2–200 μg L^?1, and the limit of detection was 0.6 μg L^?1 for nickel. The developed method was successfully applied for the determination of nickel in food and water samples. The results showed that, the proposed method can be used as a cheap, rapid, and efficient method for the extraction and preconcentration of nickel from real samples.     

Extraction of ultra traces of polychlorinated biphenyls in aqueous samples using suspended liquid-phase microextraction and gas chromatography-electron capture detection

This study reports the feasibility of applying directly suspended liquid-phase microextraction (DSLPME)-gas chromatography detection for the pre-concentration and determination of low levels of eight polychlorinated biphenyls (PCBs) in aqueous samples. The technique requires minimal sample preparation, analysis time and solvent consumption and represents significant advantages over conventional analytical methods. The experimental parameters such as salt content, sample temperature, stirring rate, extraction time, micro-drop volume and breakthrough volume were investigated and found to have significant influences on DSLPME. Under the optimal experimental conditions, the enrichment factor ranged from 578 to 729, and the recovery was above 93 %. Calibration curves possessed good linearity (R ²?>?0.99) over a wide concentration range of 0.1–10.0 μg L^?1 with limits of detection ranging from 0.01 to 0.07 μg L^?1. The relative standard deviations for 1.0 μg L^?1 of PCBs in water by using internal standard were in the range 2–14 % (n?=?3). The proposed simple, accurate and sensitive analytical method was applied successfully to the determination of trace amounts of PCBs in water samples.     

2-Nitroso-1-naphthol as a selective reagent for preconcentration of cobalt by vortex assisted combined with solidification of organic droplet and its determination by flame atomic absorption spectrometry

Highly rapid and selective vortex-assisted liquid–liquid microextraction based on solidification of organic drop has been used for determination of cobalt ion. 2-Nitroso-1-naphthol (2N1N) was used as a selective complexing agent to form stable cobalt–2N1N complex which can be extracted with 1-undecanol at a short time by the assistance of vortex agitator system followed by its determination using flame atomic absorption spectrometry. In vortex assisted, vigorous vortex stream as well as the vibrant effect of vortex system cause very fine droplets of extraction solvent to be produced and extraction occurred at a short time. Some parameters influencing the extraction process such as pH of samples, concentration of 2-nitroso-1-naphthol, extraction solvent volume, extraction time, ionic strength and surfactant addition, as well as interferences were evaluated in detail and optimum conditions were selected. At the optimum conditions, the calibration curve was linear in the range of 15 to 400 μg L^?1 of cobalt ions. The relative standard deviation based on ten replicate analysis of sample solution containing 50 μg L^?1 of cobalt was 3.4 %. The detection limit (calculated as the concentration equivalent to three times of the standard deviation of the blank divided by the slope of the calibration curve after preconcentration) was 5.4 μg L^?1. The accuracy of the proposed method was successfully evaluated by the analysis of certified reference materials. This selective and highly rapid method was used for determination of cobalt ions in different water samples.     

cDNA sequence encoding metallothionein protein from Aegiceras corniculatum and its gene expression induced by Pb2+ and Cd2+ stresses

Constructing various green wetland examples for mangrove wetland systems is a useful way to use natural power to remediate the polluted wetlands at intertidal zones. Metallothioneins (MT) are involved in heavy metal tolerance, homeostasis, and detoxification of intracellular metal ions in plants. In order to understand the mechanism of heavy metal uptake in Aegiceras corniculatum, we isolated its metallothionein gene and studied the MT gene expression in response to heavy metals contamination. Here, we report the isolation and characterization of MT2 genes from young stem tissues of A. corniculatum growing in the cadmium (Cd) and lead (Pb) polluted wetlands of Quanzhou Bay, southeast of China. The obtained cDNA sequence of MT is 512 bp in length, and it has an open reading frame encoding 79 amino acid residues with a molecular weight of 7.92 kDa and the theoretical isoelectric point of 4.55. The amino acids include 14 cysteine residues and 14 glycine residues. It is a non-transmembrane hydrophilic protein. Sequence and homology analysis showed the MT protein sequence shared more than 60 % homology with other plant type 2 MT-like protein genes. The results suggested that the expression level of MT gene of A. corniculatum young stems induced by a certain range concentration of Cd²⁺ and Pb²⁺ stresses (0.2 mmol L^?1 Pb²⁺, 1 mmol L^?1 Pb²⁺, 0.2 mmol L^?1 Pb²⁺, and 40 μmmol L^?1 Cd²⁺; 1 mmol L^?1 Pb²⁺ and 40 μmol L^?1 Cd²⁺) compared with control might show an adaptive protection. The expression levels of MT gene at 20 h stress treatment were higher than those at 480 h stress treatment. The expression levels of MT gene with 0.2 mmol L^?1 Pb²⁺ stress treatment were higher than those with 0.2 mmol L^?1 Pb²⁺ and 40 μmol L^?1 Cd²⁺ stress treatment, and the MT gene expression levels with 1 mmol L^?1 Pb²⁺ treatment were higher than those with 1 mmol L^?1 Pb²⁺ and 40 μmol L^?1 Cd²⁺ treatment. There exists an antagonistic action between Pb²⁺ and Cd²⁺ in the MT metabolization of A. corniculatum.     

Investigating toxic metal levels in popular edible fishes from the South Durban basin: implications for public health and food security

Contamination of the ocean by heavy metals may have ecosystem-wide implications because they are toxic even if present in trace levels, and the relative ease of their bioaccumulation by marine organisms may affect human health, primarily through consumption of contaminated fish. We evaluated metal concentrations in six different popular edible fish species and estimated the potential health risks from consumption of contaminated fish. There was no correlation between fish length and average metal accumulation although the fish species tended to accumulate significantly more Al and Zn (P?<?0.05) than any of the other metals. Significantly higher Mn concentrations were found in fish gills compared to other body parts in all fish species. Bronze seabream, Catface rockcod, and Slinger seabream had significantly higher mean Cr concentration in the liver than in either the tissues or gills. The highest concentration of Zn in fleshy tissue was in Horse mackerel (56.71 μg g^?1) followed by Bronze seabream (31.07 μg g^?1). Al levels ranged from 5.6 μg g^?1 in Atlantic mackerel to 35.04 μg g^?1 in Horse mackerel tissue while Cu and Cr concentrations were highest in the tissues of Horse mackerel (6.83 and 1.81 μg g^?1, respectively) followed by Santer seabream (3.15; 1.09 μg g^?1) and Bronze seabream (3.09; 1.30 μg g^?1), respectively. The highest tissue concentration of Mn was detected in Bronze seabream (8.23 μg g^?1) followed by Catface rockcod (6.05 μg g^?1) and Slinger seabream (5.21 μg g^?1) while Pb concentrations ranged from a high of 8.44 μg g^?1 in Horse mackerel to 1.09 μg g^?1 in Catface rockcod. However, the estimated potential health risks from fish consumption as determined by the target hazard quotient (THQ) and hazard index (HI) were significantly lower than 1, implying that metals were not present in sufficiently high quantities to be of any health and/or food and security concern in the studied fishes.     

Heavy metal in water and aquatic organisms from different intertidal ecosystems,Persian Gulf

Intertidal ecosystems are being damaged by anthropogenic activities, particularly in the developing countries. In this study, the load of heavy metals was determined in water, fish, shrimp, and crab collected from four intertidal ecosystems, including coral reef, rocky shore, mangrove forest, and muddy habitat along the Persian Gulf coasts. Generally, the sequence of metal accumulation in the water of coral reef and mangrove forest was Ni > Pb > V > Cd > As > Hg, whereas in muddy habitats and rocky shores, the sequence was Ni > Pb > V > Cd > Hg > As and Ni > V > Pb > As > Hg > Cd, respectively. Water of the coral reef had the highest level of Ni (97.44 μg l^?1), Pb (3.92 μg l^?1), V (10.42 μg l^?1), Cd (3.92 μg l^?1), As (1.87 μg l^?1), and Hg (0.74 μg l^?1). For the most part, the highest concentrations of the studied metals were found in the liver and the gills of Johnius belangerii and the hepatopancreas of Portunus pelagicus and Metapenaus affinis collected from the coral reef ecosystem.