Interspecific variation in heavy metal body concentrations in biota of Sunderban mangrove wetland, northeast India

The coastal environment of West Bengal, recognized as the most diversified and productive ecosystem among all the maritime states of India, faces organic pollution from domestic sewage and urban and industrial effluents leading serious impacts on biota. The present paper aims at providing information on concentration level of heavy metals among the tissues of benthic polychaetes, bivalve molluscs and finfishes collected from Sundarban mangrove wetland, northeast coast of India. An overall common trend in bioaccumulation was revealed with the following decreasing order: Zn>Mn>Cu>Cr>Se>Hg with few exceptions. Both species dependent variability and temporal variations were pronounced. A high degree of organ specificity was evident in the bivalves where gill and mantle exhibited higher metal accumulation due to ion exchange property of the mucous layer covering these organs. Variability between closely related species is a reflection of different uptake rates, physiology and impact of environmental factors. The results of this analysis suggest that mollusks can play a significant role in trace metal trophic transfer studies, especially as their representatives are intertidally and subtidally ubiquitous.     

Complete degradation of di-n-octyl phthalate by Gordonia sp. strain Dop5

The present study describes the assimilation of di-n-octyl phthalate by an aerobic bacterium, isolated from municipal waste-contaminated soil sample utilizing di-n-octyl phthalate as the sole source of carbon and energy. The isolate was identified as Gordonia sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic and spectrometric analyses revealed a complete di-n-octyl assimilation pathway. In the degradation process, mono-n-octyl phthalate, phthalic acid, protocatechuic acid and 1-octanol were identified as the degradation products of di-n-octyl phthalate. Furthermore, phthalic acid was metabolized via protocatechuic acid involving protocatechuate 3,4-dioxygenase while 1-octanol was metabolized by NAD⁺-dependent dehydrogenases to 1-octanoic acid, which was subsequently degraded via β-oxidation, ultimately, leading to tricarboxylic acid cycle intermediates. Apart from phthalic acid and 1-octanol metabolizing pathway enzymes, two esterases, di-n-octyl phthalate hydrolase and mono-n-octyl phthalate hydrolase involved in di-n-octyl phthalate degradation were found to be inducible in nature. This is the first report on the metabolic pathway involved in the complete degradation of di-n-octyl phthalate by a single bacterial isolate, which is also capable of efficiently degrading other phthalate esters of environmental concern having either shorter or longer alkyl chains.     

Effects of heavy metals on population growth and metallothionein gene expression in the mosquito Culex quinquefasciatus, from Calcutta, India

Major water bodies in and around the city of Calcutta (India) receive heavy metal contaminated effluents from industries, households, and vehicular traffic through sewage or drainage. We quantified concentrations of Cu, Zn, and Cd from three water bodies at Kalighat, Tangra, and VIP Road, respectively. The concentrations of these heavy metals were significantly greater in the summer than in monsoon when heavy downpours resulted in reduced metal concentrations. Concentrations of metals in the mosquito Culex quinquefasciatus also reflected such seasonal fluctuations. Hatchability and survivorship of C. quinquefasciatus significantly differed among the sites and were reduced significantly from the control. Exposure to heavy metals also induced MT-gene expression in C. quinquefasciatus, likely helping them to survive in the water bodies stressed with heavy metals. MT-gene activity demonstrated significant variation among sites and seasons with the highest activity in the summer in the VIP Road population. This study suggests that C. quinquefasciatus could be used as an ecological indicator of heavy metal pollution by monitoring its MT-gene expression.     

Community modelling: a tool for correlating estimates of exposure with perception of odour from municipal solid waste (MSW) landfills

Odours from municipal solid waste landfills have the potential to cause significant annoyance and impact to amenity in the environment surrounding sites. In order to assess the impact of odorous emissions on surrounding communities a quantitative model to predict annoyance was developed. The overall objective of this research was to develop the major components of the model namely, assessment of odorous emissions, dispersion and reception by the surrounding community around the landfill site. This study used community modelling as a tool to find a link between dispersion and perception of odour. The research completed a year-round monitoring program engaging people within the local community as regular odour monitors. Estimates of exposure from dispersion analysis were used to compare incidents causing complaint and intensity-concentration plots were fitted for each monitor whose reports were found to be logically consistent with regard to the intensity scaling. Human responses to the vast range of odour intensities, from highly intense source odours through to less intense dispersed odours at monitors' locations, were found to differ greatly. It was observed that the psychophysical models based on the Weber-Fechner law and Power law fitted the data consistently well for the entire range of the intensity scale used, 1-7. However, the other two models, based on Beidler's law and Laffort's equation showed an inconsistency with the intensity scales >3.     

Characterization of cadmium-resistant Klebsiella pneumoniae MCC 3091 promoted rice seedling growth by alleviating phytotoxicity of cadmium

Environmental Science and Pollution Research - Cadmium (Cd) phytotoxicity in agricultural land is a major global concern now-a-days resulting in very poor yield. Plant growth-promoting...     

Monitoring and evaluating the spatiotemporal variations of the water quality of a stretch of the Bhagirathi-Hugli River,West Bengal,India, using geospatial technology and integrated statistical methods

Environmental Science and Pollution Research - Water quality is a critical environmental issue because all forms of life depend on the water. The present study primarily focused on the...     

Food selectivity and reproductive biology of small indigenous fish Indian river shad,Gudusia chapra (Hamilton, 1822) in a large tropical reservoir

Environmental Science and Pollution Research - Assessment of life history strategies of economically important small indigenous fishes (SIF) which are rich in nutritive values is essential and...