Toxicity of cadmium nanoparticles to Bacillus subtilis

The study deals with the toxicological impact of cadmium nanoparticles (Cd NPs) on Bacillus subtilis as a model Gram-positive bacterium. Cadmium oxide (CdO) NPs (～22 nm) and cadmium sulfide (CdS) NPs (～3 nm) were used in this study. Both the NPs were found to inhibit the cell viability of B. subtilis when added to the culture at mid-log phase, the viable cell number declined with increasing concentration of Cd NPs. At mid-log phase, 15 mg L^?1 CdO NPs inhibited growth by ～50%, whereas at 30 mg L^?1 growth completely ceased. Under the same conditions, CdS NPs inhibited growth by ～50% at a concentration of 8 mg L^?1, and at 20 mg L^?1 growth was completely retarded. The cells changed their morphological features to a filamentous form with increasing Cd NPs exposure time, leading to associated with clumping. NPs treated cells when stained with 4′, 6-diamino-2-phenylindole, showed filamentous multinucleated bead structure, suggesting irregularities in cell division. Increasing intracellular oxidative stress due to Cd NPs exposure might be one of the reasons for the cell morphological changes and toxicity in B. subtilis.     

Toxicokinetics,metabolism, and microsomal studies of chlorpropham in rats

A study on the toxicokinetic behavior, metabolism of chlorpropham, and its effect on cytochrome P₄₅₀ from liver microsomes was carried out in albino rats after a single and consecutive oral administration at 500?mg?kg^?1 body weight for 10 and 20 days. Chlorpropham was detected in the blood at 0.08?h (11.43?±?1.72?µg?mL^?1) reaching a maximum concentration at 2?h (30.90?±?2.55?µg?mL^?1) and a minimum at 48?h (1.95?±?0.20?µg?mL^?1) after a single oral administration of 500?mg?kg^?1. The absorption rate constant (K _a) was 0.66?±?0.48?h^?1. The Vd _area (18.01?±?2.78?L?kg^?1) and t _1/2 β (12.23?±?1.96?h) values suggested a wide distribution and long persistence of the compound in the body, respectively. The higher Cl_R (0.82?±?0.00?L?kg^?1?h^?1) compared to Cl_H (0.18?±?0.02?L?kg^?1?h^?1) value indicated that a major portion of chlorpropham was excreted through the urine (30%) compared to the faeces (2.81%). Chlorpropham residue was detected in all tissues of rat at 0.25?h while its metabolite, meta-chloroaniline was detected in liver, kidney, heart, lung, and spleen tissue at 0.25?h. Meta-chloroaniline was not detected in skeletal muscle, brain, fat, and stomach tissue at any time of the observation period. Maximum concentrations of chlorpropham and meta-chloroaniline were detected at 2?h (except in the spleen), and minimum concentrations of chlorpropham at 24 (heart, lung, spleen, skeletal muscle, and stomach) and 48?h (liver, kidney, brain, and fat tissue) respectively; and meta-chloroaniline at 24?h (except heart and spleen). The tissue half-life of chlorpropham in rat varied from 3.80 to 11.60?h. Repeated oral administration of chlorpropham at 500?mg?kg^?1 for 10 and 20 days caused an induction of the liver microsomal pellet of rat.     

Immobilisation of manganese,cobalt and nickel by deep-sea-sediment microbial communities

Box core samples BC26 and BC36 from geologically different settings were examined to test the hypothesis that autochthonous microbial communities from polymetallic-nodule-rich Central Indian Basin sediments actively participate in immobilising metal ions. The bottom water dissolved oxygen concentration was reported to be 4.2–4.3 mL·L^?1 in the northern siliceous ooze (BC26) and 4.1–4.2 mL·L^?1 in the southern pelagic red clay (BC36); the sedimentation rates for these regions were 0.834 and 0.041 cm·kyr^?1, respectively. An onboard experiment, conducted under oxic and sub-oxic conditions with 100 μmol of Mn, Co and Ni, showed that microbial immobilisation under sub-oxic conditions was higher than in azide-treated controls in BC26 for Mn, Co and Ni at 30, 2 and 4 cm below sea floor (bsf), respectively, after 45 days. The trend in immobilisation was BC 26>BC 36, Co>Mn>Ni under oxic conditions and Mn>Co>Ni under sub-oxic conditions. The depth of maximum immobilisation for Co in BC26 under sub-oxic conditions coincided with the yield of cultured Co-tolerant bacteria and Ni only with organic carbon at 4 cm bsf. This study demonstrates that the organic carbon content and bioavailable metal concentrations in sediments regulate microbial participation in metal immobilisation.     

Consequences of manganese compounds: a review

Manufacturing of manganese (Mn) compounds, their industrial applications as well as mining overburden, has generated a potential environmental pollutant. Occupational exposure to elevated levels of Mn occurs during mining, welding, smelting and other industrial anthropogenic sources. Chronic and acute exposure of this metal pollutant leads to adverse consequences and is clinically categorized by various symptoms of neurotoxicity including cognitive, psychiatric symptoms, Parkinson's disease, extra pyramidal signs, manganism, dystonia, and motor system dysfunction. The aim of this review is to summarize the possible mechanism underlying Mn compounds-mediated neurotoxicity leading to neurodegenerative diseases. Our review endeavours to examine recent advances in research on Mn-related environmental pollution, Mn-induced poisoning, molecular mechanisms underlying Mn-induced neurotoxicity with case studies as well as current approaches employed for treatment and prevention of Mn exposure.     

Suppression of inhibition of substrate photodegradation by scavengers of hydroxyl radicals: the solvent-cage effect of bromide on nitrate photolysis

In this paper we show that bromide scavenges the ^·OH radicals formed upon photolysis of nitrate, before they leave the solvent cage. Bromide can thus inhibit the in-cage recombination between ^·OH and ^·NO₂. The consequence is an increased generation of ^·NO₂ and nitrite and of Br₂ ^?· + ^·OH, compared to ^·OH alone in the absence of bromide. We show that this effect compensates for the lower reactivity of Br ₂ ^?· compared to ^·OH toward certain organic substrates, e.g. phenol and tryptophan. Our findings could lead to a deep revision of the present views of the role of bromide in saltwater photochemistry.     

Association between skin lesion and arsenic concentration in hair by mixed bivariate model in chronic arsenic exposure

Skin lesion is one of the important health hazards caused by high intake of arsenic through drinking water and diet, and the other hazards include several types of cancers (viz. skin, lung and urinary bladder), ischemic heart disease, hypertension, etc. Two most important biomarkers to measure arsenic intake in a human body are arsenic concentration in urine and hair. The primary interest of this paper is the association between skin lesion and arsenic concentration in hair for participants with chronic arsenic exposure from West Bengal, India, using bivariate regression model based on copula function. The result showed participants with high arsenic concentration in hair had higher incidence of developing skin lesion. Arsenic concentration in hair was significantly higher for the participants with an arsenic concentration in water?>?10 mg/L.     

Natural radioactivity and radiation exposure in the high background area at Chhatrapur beach placer deposit of Orissa, India

A high natural background radiation area is reported for the Chhatrapur beach placer deposit of Orissa state, on the southeastern coast of India, due to the presence of radiogenic heavy minerals. The average activity concentrations of radioactive elements 232Th, 238U and 40K were measured by gamma-ray spectrometry using a HPGe detector, and found to be 2500 +/-1850, 230 +/- 140 and 120 +/- 35 Bq kg-1, respectively, for the bulk sand samples. The absorbed gamma dose rates in air due to the naturally occurring radionuclides varied from 375 to 5000 nGy h-1, with an average value of 1625 +/- 1200 nGy h-1. The external annual effective dose rate of the region ranged from 0.46 to 6.12 mSv y-1, with an average value of 1625 +/- 1200 mSv y-1. The absorbed gamma dose rate levels of Chhatrapur beach area were similar to the monazite sand-bearing high background radiation areas of southern and southwestern coastal tracts of India and other similar areas of the world. The major contributors to the enhanced level of radiation are monazite and zircon sands.     

Effect of the herbicides oxadiazon and oxyfluorfen on phosphates solubilizing microorganisms and their persistence in rice fields

A field experiment has been conducted with two herbicides viz. oxadiazon [5-terbutyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-one] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenyl)-4-(trifluoromethyl) benzene] at rates of 0.4 and 0.12 kg a.i. ha(-1), respectively, to investigate their effect on the growth and activities of phosphate solubilizing microorganisms in relation to availability of phosphorus as well as persistence of the herbicides in the rhizosphere soil of wetland rice (Oryza sativa L. variety IR-36). Application of herbicides stimulated the population and activities of phosphate solubilizing microorganisms and also the availability of phosphorus in the rhizosphere soil. Oxyfluorfen provided greater microbial stimulation than oxadiazon. Dissipation of oxyfluorfen and oxadiazon followed first order reaction kinetics with half-life (T(1/2)) of 8.8 and 12 days, respectively. Sixty days after application 0.5% and 3% of the applied oxadiazon and oxyfluorfen residues persisted, respectively, in the rhizosphere soil of rice.     

A process integration approach to industrial water conservation: a case study for an Indian starch industry

A case study for water using network of a Starch industry in the state of Gujarat, India, is undertaken with an aim to reduce demineralised water and freshwater flow rates and consequently the wastewater flow rate. The problem was identified as a multi contaminant, reuse and recycle problem. The freshwater consumption and demineralised water consumption were 100 t/h and 51 t/h respectively before modification and the network was dealing with three major contaminants such as total organic content, total dissolved solids and total suspended solids. A program was developed in MATLAB for analysis using Water Pinch. The improved water using network designed for the present work consumed less demineralised and freshwater. The reductions are of the tune of 28% and 64.38% for demineralised and fresh water respectively. Due to alteration in piping, there will be a saving of 406 026 INR per year, which will be utilized for development of efficient environment policy for the company. The entire concept had been implemented on plant level on 1st February-2009 and the reductions are of the tune of 25% and 60% for demineralised and fresh water respectively.