The influence of hydroxyl volatile organic compounds on the oxidation of aqueous sulfur dioxide by oxygen

Although the effect of volatile organic compounds (VOCs) on the oxidation of dissolved sulfur dioxide by oxygen has been the subject of many investigations, this is the first study which examines the effect of a large number of precisely 16 hydroxy compounds. The kinetics both in the absence and the presence of VOCs was defined by rate laws (A and B): A $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_o={k}_o\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ B $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_i={k}_i\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ where R _o and k _o are the initial rate and first-order rate constant, respectively, in the absence of VOCs, R _i , and k _i are the initial rate and the first-order rate constant, respectively, in the presence of VOCs, and [S(IV)] is the concentration of dissolved sulfur dioxide, sulfur(IV). The nature of the dependence of k _i on the concentration of inhibitor, [Inh], was defined by Eq. (C). C $$ {k}_i={k}_0/\left(1+B\left[\mathrm{Inh}\right]\right) $$ where B is an empirical inhibition parameter. The values of B have been determined from the plots of 1/k _i versus [Inh]. Among aliphatic and aromatic hydroxy compounds studied, t-butyl alcohol and pinacol were without any inhibition effect due to the absence of secondary or tertiary hydrogen. The values of inhibition parameter, B, were related to k _inh , the rate constant for the reaction of SO₄ ^? radical with the inhibitor, by Eq. (D). D $$ B=\left(9\pm 2\right)\times 1{0}^{-4}\times {k}_{inh} $$ Equation (D) may be used to calculate the values of either of B or k _inh provided that the other is known. The extent of inhibition depends on the value of the composite term, B[Inh]. However, in accordance with Eq. (C), the extent of inhibition would be sizeable and measurable when B[Inh]?>?0.1 and oxidation of S(IV) would be almost completely stopped when B[Inh]?≥?10. B[Inh] value can be used as a guide whether the reaction step: SO₄ ^??+?organics? \( \overset{k_{inh}}{\to } \) ?SO₄ ^2??+?non-chain products: should be included in the multiphase models or not.     

Column with CNT/magnesium oxide composite for lead(II) removal from water

Background  

In this study, manganese dioxide-coated multiwall carbon nanotube (MnO₂/CNT) nanocomposite has been successfully synthesized.     

PCR-RAPD profiling of Fusarium spp. causing guava wilt disease in India

Wilt is a serious disease of the guava crop in India. Fusarium oxysporum f. sp. psidii and F. solani have been reported as causative agents of this disease. In this study, 42 isolates each of F. oxysporum f. sp. psidii and F. solani, were isolated from guava cultivars and characterized by randomly amplified polymorphic DNA (RAPD) method. Thirty RAPD primers were tested in the genome of Fusarium spp. and the number of scorable bands for corresponding primer ranged from 1-8 with an average of 5 bands per individual. DNA band size ranged from 200 bp to 5090 bp. A 0.21 per cent polymorphism was found in individual isolates of F. solani indicating that the 42 isolates were similar. However, a 2.58 percent polymorphism among individual isolates of F. oxysporum f.sp. psidii showed a higher level of genetic diversity. Cluster analysis of the RAPD band patterns clearly separated the isolates of F. oxysporum f.sp. psidii into three clusters. Two clusters were formed with F. solani isolates, showing a higher degree of similarity. Unique fingerprint profiles generated by the PCR-RAPD can be exploited for genetic characterization purposes.     

The academic medical centre and nongovernmental organisation partnership following a natural disaster

The global response to the 12 January 2010 earthquake in Haiti revealed the ability to mobilise medical teams quickly and effectively when academic medical centres partner non-governmental organisations (NGO) that already have a presence in a zone of devastation. Most established NGOs based in a certain region are accustomed to managing the medical conditions that are common to that area and will need additional and specialised support to treat the flux of myriad injured persons. Furthermore, an NGO with an established presence in a region prior to a disaster appears better positioned to provide sustained recovery and rehabilitation relief. Academic medical centres can supply these essential specialised resources for a prolonged time. This relationship between NGOs and academic medical centres should be further developed prior to another disaster response. This model has great potential with regard to the rapid preparation and worldwide deployment of skilled medical and surgical teams when needed following a disaster, as well as to the subsequent critical recovery phase.     

Forest sustainability and development in hills of Uttarakhand,India: Can they move together?

Forest cover is viewed as a resource for the nation as it provides ecosystem services. However, it becomes a burden and retards development for the people of the area, particularly the hills, where such forests flourish. Enactment of stringent laws over the past few decades has strictly prohibited tree felling in these areas, and it has become a deterrent in their growth process. While on one hand, the plains are abuzz with economic activity, on the other hand, the sparse population of the hills is compelled to bear the responsibility of maintaining ecological balance. In this context, the issue of development along with forest sustainability becomes important. Using the case study of the hills of Uttarakhand, India, the paper attempts to highlight the problems and the possible strategies that may be adopted to facilitate inclusive socioeconomic development of forest dwellers while ensuring conservation and enhancement of forest cover.     

Organochlorine pesticide residues in maternal blood,cord blood,placenta, and breastmilk and their relation to birth size

There is a growing concern that persistent organic pollutants like organochlorine pesticides (OCPs) can impair fetal growth and affect birth size. However, currently available epidemiological evidence is inconclusive. In this case-control study, we examined the association between exposure to hexachlorocyclohexane (HCH) and its isomers (α-HCH, β-HCH and γ-HCH), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) and birth size. We recruited 60 infant-mother pairs, comprising of 30 term, small for gestational age babies with their mothers (Case group), and another 30 term, appropriate for gestational age babies with their mothers (Control group). This study was conducted in a tertiary hospital in Delhi, India, between March, 2009 and February 2010. Organochlorine pesticides were estimated in maternal blood, cord blood, placenta and breastmilk samples, using gas–liquid chromatography. Transplacental and transmammary transfer of OCPs was assessed by correlating the maternal blood OCP levels with those in cord blood and breastmilk by simple linear regression. The birthweight, crown heel length, head circumference, mid-arm circumference and ponderal index of the neonates was correlated with OCP levels in the maternal blood, cord blood, placenta and breastmilk. The OCP estimates were compared between samples of the case and control group. There was a significant (P < 0.001) transplacental transfer of all OCPs, however the transmammary transfer was insignificant for most OCPs except α-HCH. The OCP levels in the case group were higher than the control group; these were significantly more for t-HCH in cord blood and breastmilk; β-HCH in maternal blood, cord blood and breastmilk; DDE in placenta and DDT in breastmilk. There was a significant negative correlation between birthweight and t-HCH levels in maternal blood (P = 0.022), cord blood (P < 0.001), placenta (P = 0.008) and breastmilk (P = 0.005); β-HCH in cord blood (P < 0.001) and placenta (P = 0.020); γ-HCH in placenta (P = 0.045); and DDT (P = 0.009). Length at birth had a significant negative correlation with t-HCH in cord blood (P = 0.014) and breastmilk (P < 0.001); β-HCH in cord blood (P = 0.016) and breastmilk (P = 0.012); DDE in placenta (P = 0.016); and DDT in breastmilk (P = 0.006). Similarly, OCP levels were also found to be negatively correlated with head circumference, ponderal index and chest circumference in neonates. We conclude that prenatal exposure to some OCPs could impair the anthropometric development of the fetus, reducing the birthweight, length, head circumference, chest circumference and ponderal index.     

Evaluation of Acinetobacter sp. B9 for Cr (VI) resistance and detoxification with potential application in bioremediation of heavy-metals-rich industrial wastewater

Present work demonstrates Cr (VI) detoxification and resistance mechanism of a newly isolated strain (B9) of Acinetobacter sp. Bioremediation potential of the strain B9 is shown by simultaneous removal of major heavy metals including chromium from heavy-metals-rich metal finishing industrial wastewater. Strain B9 tolerate up to 350 mg L^?1 of Cr (VI) and also shows level of tolerance to Ni (II), Zn (II), Pb (II), and Cd (II). The strain was capable of reducing 67 % of initial 7.0 mg L^?1 of Cr (VI) within 24 h of incubation, while in presence of Cu ions 100 % removal of initial 7.0 and 10 mg L^?1 of Cr (VI) was observed with in 24 h. pH in the range of 6.0–8.0 and inoculum size of 2 % (v/v) were determined to be optimum for dichromate reduction. Fourier transform infrared spectroscopy and transmission electron microscopy studies suggested absorption or intracellular accumulation and that might be one of the major mechanisms behind the chromium resistance by strain B9. Scanning electron microscopy showed morphological changes in the strain due to chromium stress. Relevance of the strain for treatment of heavy-metals-rich industrial wastewater resulted in 93.7, 55.4, and 68.94 % removal of initial 30 mg L^?1 Cr (VI), 246 mg L^?1 total Cr, and 51 mg L^?1 Ni, respectively, after 144 h of treatment in a batch mode.     

Semen quality of environmentally exposed human population: the toxicological consequence

Human data on the relationship of semen quality with pesticide and metals are mostly inconsistent. The purpose of the study is to confirm the toxicity of organochlorine pesticide β- and γ-hexachlorocyclohexane (HCH), DDE and DDD, and metals lead or cadmium on sperm motility in epidemiological study among fertile and infertile men and to determine whether in vivo and in vitro results are in the same direction. Semen analysis and estimation of the toxicants were done in 60 fertile and 150 infertile men. In the in vitro studies, sperm were exposed to the highest levels of these toxicants found in vivo, as well as five and ten times higher, and to the mixture of all compounds. The study assesses sperm viability and motility for a period ranging between 30 min and 96 h. Epidemiological data showed an inverse correlation of toxicant with sperm motility. In vitro study showed that γ-HCH and lead after 12 h, cadmium after 8 h, and coexposure to toxicants after 6 h of exposure caused significant concentration- and duration-dependent decline in sperm motility. Data of in vitro study were concurrent with epidemiological finding that might be useful in establishing the possible association between exposure and effect of these selected pollutants on sperm motility.     

Removal of Cr(VI) onto Ficus carica biosorbent from water

The utilization of sustainable and biodegradable lignocellulosic fiber to detoxify the noxious Cr(VI) from wastewater is considered a versatile approach to clean up a contaminated aquatic environment. The aim of the present research is to assess the proficiency and mechanism of biosorption on Ficus carica bast fiber via isotherm models (Langmuir, Freundlich, Temkin, Harkin’s–Jura, and Dubinin–Radushkevich), kinetic models, and thermodynamic parameters. The biomass extracted from fig plant was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and contact time were studied by batch method. The equilibrium data were best represented by the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) onto biosorbent was found to be 19.68 mg/g. The pseudo-second-order kinetic model adequately described the kinetic data. The calculated values of thermodynamic parameters such as enthalpy change (?H ⁰), entropy change (?S ⁰), and free energy change (?G ⁰) were 21.55 kJ/mol, 76.24 J/mol?K, and ?1.55 kJ/mol, respectively, at 30 °C which accounted for spontaneous and endothermic processes. The study of adsorbent capacity for Cr(VI) removal in the presence of Na⁺, Mg²⁺, Ca²⁺, SO ₄ ^2? , HCO ₃ ^? and Cl^? illustrated that the removal of Cr(VI) increased in the presence of HCO^3? ions; the presence of Na⁺, SO ₄ ^2? or Cl^? showed no significant influence on Cr(VI) adsorption, while Ca²⁺ and Mg²⁺ ions led to an insignificant decrease in Cr(VI) adsorption. Further, the desorption studies illustrated that 31.10 % of metal ions can be removed from an aqueous system, out of which 26.63 % of metal ions can be recovered by desorption in first cycle and the adsorbent can be reused. The results of the scale-up study show that the ecofriendly detoxification of Cr(VI) from aqueous systems was technologically feasible.     

Lead tolerance in plants: strategies for phytoremediation

Lead (Pb) is naturally occurring element whose distribution in the environment occurs because of its extensive use in paints, petrol, explosives, sludge, and industrial wastes. In plants, Pb uptake and translocation occurs, causing toxic effects resulting in decrease of biomass production. Commonly plants may prevent the toxic effect of heavy metals by induction of various celular mechanisms such as adsorption to the cell wall, compartmentation in vacuoles, enhancement of the active efflux, or induction of higher levels of metal chelates like a protein complex (metallothioneins and phytochelatins), organic (citrates), and inorganic (sulphides) complexes. Phyotochelains (PC) are synthesized from glutathione (GSH) and such synthesis is due to transpeptidation of γ-glutamyl cysteinyl dipeptides from GSH by the action of a constitutively present enzyme, PC synthase. Phytochelatin binds to Pb ions leading to sequestration of Pb ions in plants and thus serves as an important component of the detoxification mechanism in plants. At cellular level, Pb induces accumulation of reactive oxygen species (ROS), as a result of imbalanced ROS production and ROS scavenging processes by imposing oxidative stress. ROS include superoxide radical (O₂ ^.?), hydrogen peroxide (H₂O₂) and hydroxyl radical (^·OH), which are necessary for the correct functioning of plants; however, in excess they caused damage to biomolecules, such as membrane lipids, proteins, and nucleic acids among others. To limit the detrimental impact of Pb, efficient strategies like phytoremediation are required. In this review, it will discuss recent advancement and potential application of plants for lead removal from the environment.