In vitro kinetic characterization of inhibition of acetylcholinesterase by organophosphate and carbamate compounds in food animals

Organophosphate, dichlorvos (2,2-dichlorovinyldimethylphosphate, DDVP), and diazinon (DZN) as well as carbamates are currently found in contaminated water, dust, soil, agricultural waste, and elsewhere in the environment, and can be harmful after accidental or deliberate exposure. Intoxication by these compounds causes a generalized cholinergic crisis due to the inhibition of acetylcholinesterase (AChE), whose major physiological role in mammalian tissues is in nervous transmission. The half-maximal inhibitory concentration (IC₅₀) was found to be higher for carbaryl than DDVP and DZN, about 3–4 times in liver and about 4–6 times in muscles. The half time (t _1/2) of inhibition (8?µmol?L^?1 DDVP or DZN; 40?µmol?L^?1 carbaryl) ranged between 4 and 16?min and decreased as follows: pig?>?cattle?>?sheep for liver tissue, and cattle?>?sheep?>?pig for muscle. Rate constants of inhibition (k _i) ranged between 43?×?10^?3 and 168?×?10^?3?min^?1 for liver and from 46?×?10^?3 to 115?×?10^?3?min^?1 for muscles. Very little residual AChE activity (<6.1%) was seen in liver, but more was seen in muscle (<17%).     

Selective separation and preconcentration studies of chromium(VI) with Alamine 336 supported liquid membrane

Chromium compounds have received considerable attention because these are used extensively in such industrial applications as electroplating, steelmaking, tanning of leather goods, and corrosion inhibition. The use of supported liquid membranes (SLMs) to remove metals from wastewaters has actively been pursued by the scientific and industrial community. In the present work, the selective separation and preconcentration of Cr(VI) ions has been studied by using a commercial amine as the membrane liquid on the porous polypropylene support. Permeation experiments were conducted on a laboratory scale batch reactor made up of perspex, with a memberane fixed amid the two chambers. The flux of Cr(VI) ions was found to be maximum (3.15?×?10^?5?mol?cm^?2?s^?1) around pH 1. Above and below this pH the flux decreases. Distribution studies show that an increase in the amine concentration leads to higher distribution coefficients at fixed pH values. At pH around unity, the distribution of Cr(VI) ions into the organic phase was found to be maximum, of the order of 56.3. The Cr(VI) transport through the membrane increases with rise in temperature. In order to check the long-term efficiency of the flat sheet SLM, an experiment was conducted with higher Cr(VI) concentration (5000?ppm) for 24?h, at optimised parameters. It was observed that in 24?h, about 1/5th of the feed Cr(VI) is left over while the rest is transported. However, minute organic droplets were also seen in the feed and strip compartments, after 1 day. This observation suggested the loss of membrane liquid. The feasibility of preconcentration of Cr(VI) by using the proposed SLM parameters, was also studied by using the hollow fibre (HF) system. Highest enrichment factor (E.F) value was obtained for 50?mg?L^?1 whereby all of the metal was transported to the stripping phase and the resulting Cr concentration was 688?mg?L^?1 (E.F?=?13.8). It was observed that while treating more diluted solutions, the enrichment factor decreases. The values of E.F equal to 8.9 and 11.3 were found for initial Cr concentration of 10 and 30?mg?L^?1.     

Bioreduction of hexavalent chromium by Exiguobacterium indicum strain MW1 isolated from marine water of Paradip Port,Odisha, India

Hexavalent chromium-tolerant (1500?mg/L) bacterium MW1 was isolated from harbour water of Paradip Port and evaluated for Cr(VI) reduction potential. The isolate was identified as Exiguobacterium indicum by biochemical and 16S rRNA gene sequence methods. Salt tolerance of the bacterium was evaluated in a wide range of NaCl concentrations (0.5–13%, w/v). The Cr(VI) reduction of the strain was evaluated and optimised with varied Cr(VI) concentrations (100–1000?mg/L), pH (5.0–9.0), temperature (30–40°C) and shaking velocity (100–150?rpm) in two different minimal media (M9 and Acetate). Under optimised conditions, after 192?h of incubation nearly 92%, 50% and 46% reduction in the M9 minimal medium and 91%, 47% and 40% reduction in the acetate minimal medium were observed for 100, 500 and 1000?mg/L of Cr(VI), respectively. The exponential rate equation for Cr(VI) reduction yielded higher rate constant value, that is, 1.27?×?10^?2?h^?1 (M9) and 1.17?×?10^?2?h^?1 (Acetate) in case of 100?mg/L and became lower for 500 and 1000?mg/L Cr(VI) concentrations. Further, the association of bacterial cells with reduced product was ascertained by Fourier transform infrared spectrometer, UV–Vis–DRS and field-emission scanning electron microscope–energy-dispersive X-ray analyses. The above study suggests that the higher reducing ability of the marine bacterium E. indicum MW1 will be suitable for Cr(VI) reduction from saline effluents.     

Kinetics of hexavalent chromium reduction by iron metal

The kinetics of Cr(VI) reduction to Cr(III) by metallic iron (Fe⁰) was studied in batch reactors for a range of reactant concentrations, pH and temperatures. Nearly 86.8% removal efficiency for Cr(VI) was achieved when Fe⁰ concentration was 6 g/L (using commercial iron powder (< 200 mesh) in 120 min). The reduction of hexavalent chromium took place on the surface of the iron particles following pseudo-first order kinetics. The rate of Cr(VI) reduction increased with increasing Fe⁰ addition and temperature but inversely with initial pH. The pseudo-first-order rate coefficients (k _obs) were determined as 0.0024, 0.010, 0.0268 and 0.062 8 min^?1 when iron powder dosages were 2, 6, 10 and 14 g/L at 25°C and pH 5.5, respectively. According to the Arrehenius equation, the apparent activation energy of 26.5 kJ/mol and pre-exponential factor of 3 330 min^?1 were obtained at the temperature range of 288–308 K. Different Fe⁰ types were compared in this study. The reactivity was in the order starch-stabilized Fe⁰ nanoparticles > Fe⁰ nanoparticles > Fe⁰ powder > Fe⁰ filings. Electrochemical analysis of the reaction process showed that Cr(III) and Fe(III) hydroxides should be the dominant final products.     

Effects of Cr(III) organic compounds on Lactobacillus plantarum

Biotransformation of Cr(VI) to less toxic Cr(III) has been known to produce insoluble Cr(III) compounds and soluble Cr(III) organic complexes. However, recent research reports have indicated that Cr(III) organic complexes are relatively stable in the environment. Little has been reported on the fate and toxic effects of Cr(III) organic compounds on organisms. In this study, the toxic effects of the soluble Cr(III) organic complexes [Cr(III) citrate, Cr(III) histidine, Cr(III) lactate and Cr(III) glutamate] to a local strain of Lactobacillus plantarum isolated from sauerkraut was investigated. Growth inhibition, viable cell count and lactic acid inhibition were measured to determine the toxicity potential of the test compounds. The EC₅₀ values of Cr(III) citrate, Cr(III) histidine, Cr(III) lactate, and Cr(III) glutamate, calculated from the percent growth inhibition were found to be 56 mg L^?1, 70 mg L^?1, 81 mg L^?1, and 85 mg L^?1, respectively. Similar trend was observed in the viable cell counts and lactic acid production. Cr(VI) was observed to be more toxic than the Cr(III) organic compounds, while inorganic Cr(III) was the least toxic. The severity seemed to increase with increase in chromium compounds’ concentration. The results showed that Cr(III) citrate was the most toxic Cr(III) organic compound, while Cr(III) glutamate was the least.     

Uranium quantification in groundwater and health risk from its ingestion in Haryana,India

Uranium is a naturally occurring radioactive element which may cause toxicological or radiological hazards to the public if present in drinking water. This study reports the quantification of uranium in groundwater of major towns of the district Fatehabad, Haryana, India. Uranium concentrations ranged between 0.3 and 48 μg L^?1. In 22% of the groundwater samples, uranium concentrations were higher than the World Health Organization maximum permissible limit of 30 µg L^?1. The radiological dose for males was found to be in the range of 4.8?×?10^?4–7.1?×?10^?2 mSv y^?1 and for females 3.5?×?10^?4–5.2?×?10^?2 mSv y^?1. The results showed that due to the ingestion of groundwater in the study area, radiological cancer risk is in the range of 9.1?×?10^?7–1.3?×?10^?4, lower than the risk limit. Uranium ingestion from groundwater varied from 0.02 to 3.5 µg kg^?1 day^?1, which is within acceptable limit.     

Spectrophotometry determination of Congo red in river water samples using nanosilver

A spectrophotometric procedure for the anionic diazo dye Congo red was proposed based on nanosilver catalyzed oxidation by potassium iodate in a hydrochloric acid medium. The calibration graph is linear for 0.8–240?mg?L^?1, and the detection limit is 0.6?mg?L^?1. Most foreign ions do not interfere with the determination, except for Cu(II), Fe(III), and Cr(VI). The interferences of Cu(II) and Fe(III) could be eliminated by masking with ethylene diamine tetraacetate, and that of Cr(VI) by reducing to Cr(III) with ascorbic acid. The typical features of this procedure are that it is sensitive for Congo red, and the determination could be carried out at room temperature. It had been used for the determination of Congo red in the Ganjnameh river water sample.     

Abstracts to forthcoming papers

Food is the major source of metal exposure for the nonsmoking general population. Food samples of plant and animal origin from Ismailia, Egypt, were analyzed for the content of cadmium (Cd), lead (Pb), chromium (Cr), zinc (Zn), and copper (Cu) using AAS. The Cr, Zn, and Cu concentrations were in the range of 1.7–249?µg?kg^?1 wet weight (ww), 2–66?mg?kg^?1?ww, and 0.5–3.46?mg?kg^?1?ww, respectively. The mean daily intake of Cr, Zn, and Cu was 28.9?µg day^?1, 8.55?mg day^?1, and 1.7?mg day^?1, respectively. The intake estimates are within the range of the recommended intake established internationally. Concentrations of Cd and Pb were in the range of 10–321?µg?kg^?1?ww and 31–1200?µg?kg^?1?ww, respectively. The weekly dietary intake for Cd and Pb (4.02 and 20.4?µg?kg^?1 b.w, respectively) is lower than the FAO/WHO PTWI. Bread is the foodstuff that provided the highest rate of Pb and Cd (62 and 46% of the daily intake) to adults in Ismailia city.     

Oxidative stress and changes in locomotor behavior and gill morphology of Gambusia affinis exposed to chromium

Sublethal effects of chromium trioxide on mosquito fish, Gambusia affinis, were carried out for 28 days on day 4, 8, 12, 16, 20, 24, and 28. The sublethal effects of chromium (LC₁₀, 77.62?mg?L^?1) on antioxidant enzymes, thiobarbituric acid reactive substance (TBARS), locomotor behavior, and gill morphology were studied. The antioxidant enzymes like superoxide dismutase (SOD) and catalase were induced throughout the exposure span of 28 days. Percent induction was also increase with the days of exposure. Lipid peroxidation product, malondialdehyde was enhanced in the viscera tissue of chromium-exposed fish. Perturbation of locomotor behavior like decrease in distance travelled (m?min^?1) and in swimming speed (cm?s^?1) was observed in exposed fish. Chromium toxicity caused alterations in gill morphology like hypertrophy and hyperplasia in secondary lamellae followed by detached epithelium with severe necrosis. It can be concluded from the results that Cr intoxication in Gambusia fish, caused induction in antioxidant enzymes and lipid peroxidation, plus changes in gill morphology and locomotor behavior.     

A review for chromium removal by carbon nanotubes

Water pollution is still a serious problem for the entire world. Adsorption technology is a promising process which is based on the fabrication of novel, cheap, non-dangerous and highly sorptive materials for application in wastewater purification processes. Nanomaterials are functional groups which find use in many important fields such as medicine, food processing and agriculture. This review collects information from published works about the use of carbon nanotubes as efficient and promising adsorbents in chromium removal from (real or synthesised) wastewater. For this purpose, isotherm (Langmuir, Freundlich, etc.), kinetic (pseudo-first-, second-order, etc.), thermodynamic (free-energy Gibbs, enthalpy, entropy) and desorption–regeneration studies were discussed in detail. Moreover, significant factors such as pH, agitation time, temperature, adsorbent dosage and initial dye concentration are also reported extensively. The maximum monolayer adsorption capacities of Cr(III) and Cr(VI) ions were 0.39–238.09 and 1.26–370.3?mg/g, respectively. The absolute values of ΔG⁰ and ΔH⁰ ranged 0.237–48.62 and 0.16–58.43?kJ/mol, respectively.     

Evaluation of metabisulfite and a commercial steel wool for removing chromium(VI) from wastewater

Efficiency of metabisulfite and a commercial steel wool as reducing agents in the removal of Cr(VI) from wastewaters was evaluated. Chromium(VI) was converted to Cr(III), precipitated with NaOH, and removed by filtration. A reduction of more than 1.0 × 10⁵ and 4.0 × 10⁵ fold in total Cr and the Cr(VI) concentrations, respectively, was observed by employing steel wool masses as low as 0.4420 g to 30-mL solutions of wastewater. Chromium(III) hydroxide obtained after the treatment was recycled and used as marker in cattle nutrition studies. The liquid residue obtained after the treatment was reused as precipitation agent replacing NaOH.     

Development of a complex-based flow injection spectrophotometric method for determination of the herbicide pinoxaden in environmental samples

A flow injection (FI) spectrophotometric method for the determination of the herbicide pinoxaden (PXD) has been proposed. PXD was converted in alkaline media with hydroxylamine hydrochloride to the hydroxamate salt. The salt was reacted with iron(III) chloride, and the absorbance of the red colored tris iron hydroxamate complex was measured at 500?nm using a FI system. The method was found to be linear between 0.5 and 40?mg?L^?1 with a molar absorptivity of 1.53?×?10^4?L?mol^?1?cm^?1. The limit of detection and limit of quantification were found to be 0.1?±?0.01?mg?L^?1 and 0.6?±?0.05?mg?L^?1, respectively. Any interference of fenoxaprop-p-ethyl (FE) was avoided by the separation of PXD by liquid chromatography with a mixture of dichloromethane and n-hexane (1?:?1) as eluent. The method was applied to the determination of PXD in soil, water, and wheat grains with percent recoveries of 98?±?2, 100?±?2, and 98?±?5, respectively. Sample throughput of 60 samples per hour was achieved under optimized conditions.     

Sublethal effect of the dispersant Goldcrew on selected blood parameters of the African cat-fish Clarias gariepinus

Selected hematological parameters of Clarias gariepinus exposed to sublethal concentrations of the dispersant goldcrew were measured weekly for four consecutive weeks under a static renewal condition in order to simulate possible effects of clean-up operations in the aquatic environment. Hemoglobin (Hb) hematocrit (PCV), red blood cell count (RBCC), white blood cell count (WBCC), and platelet values were 15.40–13.58 g dL^?1, 42.36–36.38%, 5.50–4.09 × 10² L^?1, 6.22–6.62 × 10² L^?1 and 362.87–283.0 × 10⁹, respectively, from week 1 to week 4. Duration of exposure had a marked significance (p < 0.05) on all blood parameters except WBCC. Also, Hb, PCV, RBCC, and platelet had values of 15.80–13.27 g dL^?1, 24.12–35.52%, 5.17–4.0 × 10² L^?1, 5.69–6.85 × 10⁹ L^?1, and 395.25–227.25 × 10, respectively, from control to maximum treatment levels. Exposure concentrations have a significant impact (p < 0.05) on all blood parameters. It may be concluded that Goldcrew has a marked negative effect on fish blood and therefore a need to observe restraint in its usage.     

Influence of iron plaque on chromium accumulation and translocation in three rice (Oryza sativa L.) cultivars grown in solution culture

Hydroponic experiments were conducted to investigate the role of iron plaque on root surface in chromium accumulation and translocation in three rice cultivars (90-68-2, CDR22 and Jin 23A). Rice seedlings were grown under 1.0 mg L^?1 trivalent chromium (Cr(III)) stress with and without phosphorus (P) treatments. P addition significantly increased the shoot and root biomass in all three rice cultivars. In the absence of P, the amounts of iron plaque (DCB-extractable Fe) on the root surface increased resulting in the increase of Cr accumulation in iron plaque. Compared to that with P treatment, Cr concentrations in iron plaque without P treatment were enhanced by 2–3 folds in the three rice cultivars. There was a significantly positive correlation between DCB-extractable Cr and DCB-extractable Fe on the root surface of the three rice cultivars. There were no significant effects on Cr concentration in roots and shoots between P treatments, but significant differences among cultivars were observed. Cultivar Jin 23A had the lowest Cr concentration both in roots and shoots regardless of P treatment. The results suggest that iron plaque could be a trap for immobilising Cr from environment but may not affect Cr uptake and translocation. Screening and breeding the cultivars with low Cr accumulation is considered as the most effective approach in Cr contaminated areas.     

Preconcentration of samarium with modified yeast cells for its determination by atomic emission spectroscopy

A chelating-modified biosorbent is produced by coupling of a dye, procion red, to yeast cells. The resulting modified cells have been characterized by Fourier transform infrared, elemental analysis and thermogravimetric analysis and studied for preconcentration and determination of trace Sm(III). The optimum pH value for sorption of the samarium ions is 6.2. The sorption capacity of functionalized modified yeast cells is 7.2 mg g^?1. Recovery was 99% when Sm(III) was eluted with an aqueous solution of 0.1 mol L^?1 ethylenediaminetetraacetic acid. Scatchard analysis suggested that binding sites were homogeneous. The equilibrium data were analyzed using Langmuir, Freundlich, Temkin, and Redlich–Peterson isotherm models, and the respective constants were determined as 1.0 (L mg^?1), 2.9 [(mg g^?1) (L mg^?1)^1/n], 2.4 × 10⁸ (L g^?1), and 30 (dm³ g^?1) at 20 °C. The method was applied for an Sm(III)-containing sample of ceramic industry effluent.     

Effects of nonylphenol on ovarian cancer cells PEO4 c-myc and p53 mRNA and protein expression

The molecular mechanisms underlying proliferation and apoptosis induced by p-nonylphenol (NP) through regulation of mRNA and protein expression of c-myc, p53 mRNA and the protein was investigated using ovarian cancer PEO4 cells. PEO4 cells were grown in the Dulbecco's modified Eagle medium (DMEM), 3(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay was employed to investigate cell proliferation. RT-PCR and immunohistochemistry was performed to determine mRNA and protein expression of PEO4 c-myc and p53. Within the range of approximately 8–9×10^?7 mol L^?1, NP stimulated proliferation in PEO4 cells in a concentration-and time-dependent manner. RT-PCR and immunohistochemistry analyses revealed that treatment with 32 × 10^?7 mol L^?1 NP for 72 hr resulted in increased mRNA and protein expression of PEO4 c-myc and p53. Evidence indicates that NP exerted estrogenic actions and stimulated proliferation in estrogen responsive ovarian cancer PEO4 cells by up-regulation of c-myc mRNA and protein expression.     

Dissolved nutrient dynamics along the southwest coastal waters of India during northeast monsoon: a case study

Dissolved nutrients, Chl-a and primary productivity were measured from seven transects along the coastal waters of the southeastern Arabian Sea during northeast monsoon. Ten major estuaries were chosen to study the influence of estuarine discharge on the nutrient dynamics in the coastal waters. The mean water discharge of the estuaries in the north (64.8?±?18?×?10⁵?m³?d^?1) was found to be higher than those in the south (30.6?±?21.4?×?10⁵?m³?d^?1), whereas the nutrient concentrations were found to be higher in the estuaries of the south. The results from the offshore waters were discussed in accordance with the depth contour classification, that is, shelf (depth?≤?30?m) and slope waters (depth?≥?30?m). Our results suggest that the estuarine discharge plays a major role in the nutrient distribution in near shore shelf waters, whereas in shelf and slope waters, it was mainly controlled by in situ biological processes. The inorganic form of N to P ratios were found to be higher than Redfield ratio in slope waters when compared with shelf waters, suggesting that PO₄^3? (<0.15?µmol?L^?1) is a limiting nutrient for primary production. The multivariate statistical analysis revealed that the nutrient dynamics in the coastal waters was controlled by both biological and physical processes.     

Spatial distributions,source apportionment and ecological risk of SVOCs in water and sediment from Xijiang River,Pearl River Delta

Xijiang River is an important drinking water source in Guangxi Province, China. Along the Xijiang River and surrounding tributary, the pollution profile of three important groups of semi-volatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), was analyzed. Relatively low levels of PAHs (64–3.7 × 10² ng L^?1) and OCPs (16–70 ng L^?1), but high levels of PAEs (7.9 × 10²–6.8 × 10³ ng L^?1) occurred in the water. Comparatively, low levels of OCPs (39–1.8 × 10² ng g^?1) and PAEs (21–81 ng g^?1), but high levels of PAHs (41–1.1 × 10³ ng g^?1) were found in sediment. Principal component analyses for source identification indicated petroleum-derived residues or coal and biomass combustion, and vehicular emission was the main sources for PAHs. The OCPs sources of each category were almost independent, whereas the new input of HCHs and p,p′-DDTs probably existed in some areas. PAEs were mainly originated from personal care products of urban sewage, plastic and other industrial sources. Ecological risk through the risk quotient analysis indicated a small or significant potential adverse effect on fish, daphnia and green algae. Nevertheless, the integrated risk of all pollutants should be taken into account in future study.     

The role of root organic acids in the tolerance of Festuca rubra to zinc,lead and cadmium

Abstract

Festuca rubra L. plants are pseudometallophytes colonizing abandoned Pb/Zn mine areas, successfully employed in phytostabilization. To study the contribution of low-molecular weight organic acids to metal tolerance, F. rubra plants were grown for three months in hydroponics with Cd (1.8, 18 and 36 µmol?L^?1), Pb (50, 250 and 500?µmol?L^?1) and Zn (0.3, 3 and 6?mmol?L^?1), separately, and in ternary combination (18?µmol?L^?1 Cd + 250?µmol?L^?1 Pb + 0.3?mmol?L^?1 Zn). The roots retained most of the metals but their distribution from shoot to root was altered when the plants were treated with the ternary combination. The main organic acids in roots were citrate and malate. At the lowest concentrations, the metals caused small reductions in biomass, had no effects on photosynthetic pigments nor on malondialdehyde, but led to increases in root organic acids. At higher concentrations, phytotoxic responses were observed, associated with a decline of citrate and malate in the roots.