Study of changes in bacterial and viral abundance in formaldehyde-fixed water samples by epifluorescence microscopy

Accurate measurement of bacterial and viral abundance in coastal marine environments is important to understand the dynamics of microbial communities in these ecosystems. In this study, the effect of formaldehyde preservation on the abundance of bacteria and viruses in water samples from Cochin Backwater was determined by SYBR Green I staining and epifluorescence microscopy. The counts were determined for 45 days in samples fixed with 1?C6% formaldehyde. The results suggest rapid decline in counts of bacteria and viruses in samples preserved in formaldehyde, and the decline increased with increase in the final concentration of formaldehyde in the sample. The initial bacterial and viral counts in the sampling site were 5.2 × 10⁶/ml and 3.9 × 10⁷/ml, respectively. The bacterial count dropped by 5.1%, 53.3%, 55.7%, and 85% after 1, 7, 15, and 45 days, respectively, in sample fixed with 1% formaldehyde. The decline in viral counts was higher, being 32.4%, 47.9%, 68.1%, and 93% after 1, 7, 15, and 45 days, respectively. Storage of fixed samples at ??20°C did not halt the decline in microbial counts, suggesting that, irrespective of storage temperature, formaldehyde-fixed samples lead to underestimation of microbial counts.     

Sorption and desorption of cadmium by different fractions of biosolids-amended soils

To evaluate the importance of both the inorganic and organic fractions in biosolids on Cd chemistry, a series of Cd sorption and desorption batch experiments (at pH 5.5) were conducted on different fractions of soils from a long-term field experimental site. The slope of the Cd sorption isotherm increased with rate of biosolids and was different for the different biosolids. Removal of organic carbon (OC) reduced the slope of the Cd sorption isotherm but did not account for the observed differences between biosolids-amended soils and a control soil, indicating that the increased adsorption associated with biosolids application was not limited to the increased OC from the addition of biosolids. Removal of both OC and Fe/Mn further reduced the slopes of Cd sorption isotherms and the sorption isotherm of the biosolids-amended soil was the same as that of the control, indicating both OC and Fe/Mn fractions added by the biosolids were important to the increased sorption observed for the biosolids-amended soil samples. Desorption experiments failed to remove from 60 to 90% of the sorbed Cd. This "apparent hysteresis" was higher for biosolids-amended soil than the control soil. Removal of both OC and Fe/Mn fractions was more effective in removing the observed differences between the biosolids-amended soil and the control than either alone. Results show that Cd added to biosolids-amended soil behaves differently than Cd added to soils without biosolids and support the hypothesis that the addition of Fe and Mn in the biosolids increased the retention of Cd in biosolids-amended soils.     

Identification of hot spots and well managed areas of Pichavaram mangrove using Landsat TM and Resourcesat—1 LISS IV: an example of coastal resource conservation along Tamil Nadu Coast, India

The present work is a multi-temporal satellite based study on the spatial dynamic of an important coastal habitat, the Pichavaram mangrove ecosystem, over a period of 15 years. The Pichavaram mangrove forest near Chidambaram, South India is the second largest mangrove forest in the world. Unsupervised classification, the Iterative Self Organising Data Analysis Technique (ISODATA), has been used to classify the mangrove cover into the open and dense classes. The status of the classes has been monitored using Landsat TM of 1991, 2001, and Resourcesat–1 LISS IV of 2006 satellite data. The study demonstrated that by classifying mangrove ecosystem into just the 3 classes using remote sensing data and by studying their temporal variations, it is possible to get a reasonably accurate picture of the extent and condition of the mangrove ecosystem. The total area of the Pichavaram mangrove showed a net increase of 2.51 km² within a span of 15 years (1991 to 2006). The hot spots that are at a risk of being degraded, and on the other hand, the mangrove areas that are well managed are identified using Geographical Information System (GIS) tools for the restoration and conservation measures.     

Population exposure to airborne thorium at the high natural radiation areas in India

High natural radiation areas in the coastal and peninsular India were studied for airborne thorium and resultant population exposure due to inhalation. Four locations covering three states viz., Ayiramthengu and Neendakara in Kerala, Kudiraimozhi in Tamil Nadu and Bhimilipatnam in Andhra Pradesh were investigated. External gamma radiation fields 1 m above the monazite ore bodies ranged from 200 to 3000 nGy h^-1. Soil samples showed ²³²Th specific activity varying from 0·1 to 1·5 Bq g^-1 with surface alpha activity in the range of 1·0–12·5 Bq cm^-2. Suspended particulates in the samples ranged from 60–140 μg m^-3 with ²³²Th showing a wider variation of <0·03–0·3 mBq m^-3. There was poor correlation between suspended particulates and long-lived alpha airborne activity . The resuspension factors for ²³²Th were in the range of 1·5×10^-8–7·9×10^-7 cm^-1. Higher resuspension was correlated with dry sand dunes. The upper limits for Committed Effective Dose (CED) due to inhalation of airborne ²³²Th at the respective high natural radiation areas were estimated to range from 50±30 to 300±130 μSv (5–30 mrem) per year per adult member of public assuming an activity median aerodynamic diameter of 1 μm for the airborne particulates.     

Do national levels of individualism and internal locus of control relate to well‐being: an ecological level international study

Data were collected from managers in 24 nations/territories on work locus of control (LOC), individualism–collectivism (I–C), and well‐being (job satisfaction, absence of psychological strain, and absence of physical strain). There were significant mean differences across samples on all five of these measures, and consistent with our hypothesis, at the ecological or sample mean level well‐being was associated with an internal locus of control. However, contrary to our hypothesis, well‐being was not associated with I–C, despite a strong correlation between I–C and LOC. Findings at the ecological level were consistent with the literature concerning the salutary effects of control on well‐being. Copyright © 2001 John Wiley & Sons, Ltd.     

Thermodynamics of chromium(III) adsorption onto a cation exchanger derived from saw dust of Jack wood

A novel cation exchanger, polymethacrylic acid-grafted saw dust (SD) with spacer group (SP) containing carboxylate functional group at the chain end (SDGPMA-SP-COOH) was prepared from saw dust of Jack wood, and its adsorption equilibrium and thermodynamics of Cr(III) ions were studied at different initial concentrations and temperatures at pH 7.0 using batch technique. Thermodynamic parameters such as change in standard free energy, ΔG ⁰, standard enthalpy, ΔH ⁰ and standard entropy, ΔS ⁰ were determined. The values of isosteric heat of adsorption (ΔH _x ) remain constant at different surface loading of Cr(III) indicating homogeneous surface sites and the absence of lateral interaction between adsorbed ions.     

Acute toxicity evaluation of copper,arsenic and HCH to paddy field crab,Paratelphusa hydrodromus (Herb.)

Routine static tests were conducted for determining the median lethal tolerance limit of paddy field crab, Paratelphusa hydrodromus exposed to Copper, Arsenic and HCH at different time intervals of 24, 48, 72 and 96 hour. The LC50 values for Copper came to be 28.00, 22.00, 18.20 and 15.70 ppm; Arsenic 136.00, 128.00, 121.500 and 114.00 ppm and HCH 10.00, 8.80, 7.00 and 6.00 ppm, respectively. The safe concentration, application factor and safe application rate were also calculated. They were for, Copper: 5.56, 1.59 and 3.26 ppm, Arsenic: 38.53, 11.40 and 76.00 and HCH : 4.07, 0.06 and 1.28 ppm. Animals exposed to different concentrations of test chemicals (Copper, Arsenic and HCH) showed prominent behavioural/morphological alterations viz., coughing, redness on the ventral side, paralysis and disorientation in scaphognathite activity. Animals exposed to high concentrations showed an avoidance behaviour by keeping away from the direct contact with the toxic solution either by climbing on the wall of aquarium or by mounting over the weak individual and forming a type of pyramid.     

Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model

The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint-based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species and multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The modeling system is designed in such a way that constraint-based models targeting different microorganisms or competing organism communities can be easily plugged into the system. Constraint-based modeling is very costly given the size of a genome-scale reaction network. To save computation time, a binary tree is traversed to examine the concentration and solution pool generated during the simulation in order to decide whether the constraint-based model should be called. We also show preliminary results from the integrated model including a comparison of the direct and indirect coupling approaches and evaluated the ability of the approach to simulate field experiment.     

In situ stabilization of soil lead using phosphorus and manganese oxide: influence of plant growth

In situ stabilization of Pb contaminated soils can be accomplished by adding P and Mn(IV) oxide. However, the long-term efficacy of in situ stabilization under continual P removal through plant growth is unknown. Moreover, the effects these treatments have on phytoavailability of other metals (Cd and Zn) commonly associated with Pb in soil are not well understood. Greenhouse experiments using sudax [Sorghum vulgare (L.) Moench] and Swiss chard [Beta vulgaris (L.) Koch] were carried out to evaluate the effects of plant growth on soil Pb bioavailability to humans after addition of P and other amendments, and the effects of these treatments on Pb, Cd, and Zn phytoavailability in three metal-contaminated soils. Eight treatments were used: zero P; 2500 mg of P as triple superphosphate (TSP); 5000 mg of P as TSP or phosphate rock (PR); 5000 mg of Mn oxide/kg; and combinations of Mn oxide and P as TSP or PR. The addition of P and/or Mn oxide significantly reduced bioavailable Pb, as measured by the physiologically based extraction test (PBET), in soils compared with the control even after extensive cropping. The PBET data also suggested that removal of P from soluble P sources by plants could negate the beneficial effects of P on bioavailable Pb, unless sufficient soluble P was added or soluble P was combined with Mn oxide. In general, Ph, Cd, and Zn concentrations in shoot tissues of sudax and Swiss chard were reduced significantly by TSP and did not change with the addition of PR. The combination of PR and Mn oxide significantly reduced Pb concentrations in plants compared with the control.     

Study on the gill of field crab,Paratelphusa hydrodromus (Herbst.) exposed to nickel

Paratelphusa hydrodromus (Herbst.) was exposed to 50 ppm nickel chloride solution for a period of 10 days under laboratory conditions. The gills of the treated and non-treated animals were sectioned, stained and examined under a compound microscope and noticed significant changes such as enlargement of gill lamellae, lifting up and rupture of epithelial cells, enlargement of mid rachis, hyperplasia and hypertrophy, appearance of pyknotic nuclei and a general necrosis in the treated gills. Results suggest that a comparatively low concentration of nickel (50 ppm) is enough to elicit pathological changes in Paratelphusa hydrodromus.