Physicochemical and microbiological assessment of recreational and drinking waters

The present study was aimed to make an assessment of health risk due to pollution and human pathogenic bacteria associated with the recreational and drinking water sources in twin densely populated holy Indian cities Ayodhya and Faizabad. Though physicochemical studies revealed that the water available in the area is under recommended limits for human use, it is unsafe on account of poor microbiological quality of surface and ground water in the region. The most probable number (MPN) test results revealed the preponderance of ≥2,400 total coliforms (TC) (100 ml)^− 1 in river, pond, dug well and kund waters. Contrary to that, 94% tube wells, 32% hand pumps and 25% piped supply water were under safe limits having <3 TC (100 ml)^− 1. The shallow depth (~40 ft), water logging and presence of septic tanks in the near vicinity are the possible reasons of poor microbial quality of hand pump drinking water. The municipal supply water passes along sewage line where loose connections and/or cracks in pipe lead to mixing and contamination. The significant best quality of tube well water evident from the absence of TC could be attributed to the depth of well ≥150 ft and usually their location away from the habitation. A total of 263 bacteria from 186 water samples were isolated, and at least five genera of enteric bacteria from various water sources were identified morphologically and biochemically as Escherichia coli, Klebsiella sp., Enterobacter sp., Shigella sp. and Salmonella sp. The serotyping of 72 E. coli and 36 Salmonella sp. revealed 51 as E. coli O157 and 20 as Salmonella sp. The presence of enteric pathogens in water sources pose threat to human health and therefore call for immediate remedial measures.     

Occurrence,toxicity and remediation of polyethylene terephthalate plastics. A review

Environmental Chemistry Letters - Polyethylene terephthalate is a common plastic in many products such as viscose rayon for clothing, and packaging material in the food and beverage industries....     

Exploring the multifaceted role of TGF-β signaling in diabetic complications

Environmental Science and Pollution Research - Diabetes is one of the most comprehensive metabolic disorders and is spread across the globe. The data from IDF Diabetes Atlas and National Diabetes...     

Possible cause of inhibition of seed germination in two rice cultivars by heavy metals Pb2+ and Hg2+

Seeds of two rice cultivars (Oryza sativa) cv. PR-116 and Pant Dhan-12 subjected to heavy metal lead (Pb²⁺) and mercury (Hg²⁺) exposure showed an inhibition in germination percentage, shoot and root length, and lower fresh and dry weight after 7 days. Both Pb²⁺ and Hg²⁺ inhibited the solubilization process of starch due to reduction in α-amylase activity, which is also evident from greater starch content and reduced soluble carbohydrate content of endosperms of treated seeds of the two cultivars. Mercury was more tolerated by Pant Dhan-12 when grown under in vitro culture medium containing 2% sucrose. The inhibitory effect of Pb²⁺ on embryo growth was not only abolished but also accelerated by 2% sucrose. The inhibitory effect, however, was not significantly blocked in Hg²⁺-treated embryos grown in vitro in sucrose containing medium. Embryos did not grow normally in a medium devoid of sucrose in either case. Data indicated that Pb²⁺ inhibited germination and seedling growth by impairing the solubilization of endosperm starch without markedly affecting the embryo, while Hg²⁺ inhibited germination and seedling growth by damaging the embryo itself.     

Green synthesis,activation and functionalization of adsorbents for dye sequestration

Environmental Chemistry Letters - The release of recalcitrant dyes into the biosphere is a threat because of pollution and environmental health issues. Adsorption using commercial activated carbon...     

Preliminary Studies on the Population Genetics of the Central Stoneroller (Campostoma anomalum) from the Great Miami River Basin, Ohio

Molecular approaches are particularly useful for measuring genetic diversity and were applied to samples of central stonerollers obtained from sites along tributaries to the Great Miami River in Ohio. We used Random Amplified Polymorphic DNA (RAPD) analysis to assess the level of genetic diversity within and among these populations. RAPD analysis generates genetic profiles that were used to develop indices of genetic similarity. The RAPD method provides a cost effective means of generating an arbitrary sample of anonymous loci across the genome and generate a virtually unlimited set of loci for use in genetic analysis in the absence of specific sequence information. These attributes make RAPDs well suited for use in evaluating the diversity and assessing the potential vulnerability to exposure of populations across multiple spatial scales. The results demonstrate that a significant amount of structuring exists among populations analyzed to date and that a trend exists towards genetic diversity being an inverse function of site distance from the main stem as well as a being directly related to stream order. This indicates that populations farthest from main conduits or in lower order streams, and thereby most isolated, may be the most vulnerable populations to stressor exposure. It is hoped that information pertaining to genetic diversity, when integrated with other metrics of resource condition, will aid in making scientifically grounded decisions on resource management that enhance the probability of population survival and preserve natural evolutionary processes.     

Assessing the impact of irrigation treatments on thiram residual trends: Correspondence with numerical modelling and field-scale experiments

The present study was undertaken to study the trends of transport of thiram, a dithiocarbamate pesticide, at different time and depth in the fields under real field conditions for wheat crop. Numerical simulations were carried out by solving the coupled soil–water content movement and mass transport equations using HYDRUS- 1D. The supplementary data used for paramaterization of HYDRUS-1D comprise of irrigation treatments, climatic conditions, and soil characteristics. Results focus on the effects and influence of irrigation treatments on pesticide persistence and mobility. Modelling results were in good agreement with the experimentally determined thiram concentrations. Application of the model to measured field data of thiram movement indicates that the modelling approach can provide reliable and useful estimates of the mass flux of water and non-volatile pesticide in vadose zone. For policy-makers and planners, some regulation strategies are suggested for controlling inappropriate pesticide application under deficit irrigation or rain-fed conditions.     

Chromium (VI) biosorption and bioaccumulation by chromate resistant bacteria

In this study, strains that are capable of bioaccumulating Cr(VI) were isolated from treated tannery effluent of a common effluent treatment plant. The Cr(VI) concentration in this treated effluent was 0.96 mg/l, much above the statutory limit of 0.1 mg/l for discharge of industrial effluents into inland surface waters in India. In addition to the bioaccumulation, biosorption capabilities of living and dead cells were analysed. Two strains, identified as Bacillus circulans and Bacillus megaterium were able to bioaccumulate 34.5 and 32.0 mg Cr/g dry weight, respectively and brought the residual concentration of Cr(VI) to the permissible limit in 24 h when the initial concentration was 50 mg Cr(VI)/l. Our experimental design accounts for initial as well as final residual concentration of heavy metal while selecting heavy metal accumulating strains during batch studies. Biosorption of Cr(VI) was shown by B. megaterium and an another strain, B. coagulans. Living and dead cells of B. coagulans biosorbed 23.8 and 39.9 mg Cr/g dry weight, respectively, whereas, 15.7 and 30.7 mg Cr/g dry weight was biosorbed by living and dead cells of B. megaterium, respectively. Biosorption by the dead cells was higher than the living cells. This was due to prior pH conditioning (pH 2.5 with deionized water acidified with H2SO4) of the dead cells.     

Comparison of coal/solid recovered fuel (SRF) with coal/refuse derived fuel (RDF) in a fluidized bed reactor

An experimental study was undertaken to compare the differences between municipal solid waste (MSW) derived solid recovered fuel (SRF) (complying with CEN standards) and refuse derived fuel (RDF). Both fuels were co-combusted with coal in a 50 kW fluidised bed combustor and the metal emissions were compared. Synthetic SRF was prepared in the laboratory by grinding major constituents of MSW such as paper, plastic, textile and wood. RDF was obtained from a local mechanical treatment plant. Heavy metal emissions in flue gas and ash samples from the (coal + 10% SRF) fuel mixture were found to be within the acceptable range and were generally lower than that obtained for coal + 10% RDF fuel mixture. The relative distribution of heavy metals in ash components and the flue gas stream shows the presence of a large fraction (up to 98%) of most of the metals in the ash (except Hg and As). Thermo-gravimetric (TG) analysis of SRF constituents was performed to understand the behaviour of fuel mixtures in the absence and presence of air. The results obtained from the experimental study will enhance the confidence of fuel users towards using MSW-derived SRF as an alternative fuel.     

Fluoride contamination in drinking water in rural habitations of Northern Rajasthan, India

This study was carried out to assess the fluoride concentration in groundwater in some villages of northern Rajasthan, India, where groundwater is the main source of drinking water. Water samples collected form deep aquifer based hand-pumps were analysed for fluoride content. Fluoride in presently studied sites was recorded in the ranges of 4.78 and 1.01 mg/l. The average fluoride concentration for this region was recorded 2.82 mg/l. As per the desirable and maximum permissible limit for fluoride in drinking water, determined by WHO or by Bureau of Indian Standards, the groundwater of about 95 of the studied sites is unfit for drinking purposes. Due to the higher fluoride level in drinking water several cases of dental and skeletal fluorosis have appeared at alarming rate in this region. The middle and eastern parts of the Hanumangarh, a northern most district of the state, can be classified as higher risk area for fluorosis; due to relatively high concentrations of fluoride (3-4 mg/l) in groundwater of this region. After evaluating the data of this study it is concluded that there is an instant need to take ameliorative steps in this region to prevent the population from fluorosis.