Seasonal dynamics of phytoplankton in response to environmental variables in contrasting coastal ecosystems

Environmental Science and Pollution Research - Seasonal distribution of phytoplankton community and size structure was assessed in three different tropical ecosystems of the western Bay of Bengal...     

A rapid green synthesis of Ag/AgCl-NC photocatalyst for environmental applications

Environmental Science and Pollution Research - The present study focuses on extract-mediated Ag nanoparticles (NPs), AgCl-NPs, and Ag/AgCl nanocomposites (NCs) as photocatalysts along with its...     

Insecticide pollution of Indian rivers

Summary Rivers are the main source of water in India, and are particularly used for agricultural irrigation and drinking water supply. As most of the rivers pass through agricultural fields, they are subject to contamination with the different insecticides used for crop protection. Residues of persistent organochlorines, which are still used in large quantities in India, are found in water from many Indian rivers. In certain rivers, the concentrations of DDT, aldrin and heptachlor are often present in excess of their guideline limits. Although the concentration level of gamma-HCH is well below the guideline limit, the accumulation of the carcinogenic beta isomer is a matter of great concern. A few organophosphorus insecticides have also been detected in river water. Recently, some organochlorine insecticides have been banned from use in India. The use of new, readily biodegradable insecticides and biocides in agriculture and public health programmes offers some optimism.Drs Satya P. Mohapatia, Vijay T. Gajbhiye and Narendra R. Agnihotri all work within the Division of Agricultural Chemicals at the above address. Dr Manju Raina is employed by the Ganga Project Directorate of the Ministry of Environment and Forests, New Delhi 11003, India.     

Plant availability of cadmium in presence of organic acids: an interactive aspect

The present communication reports the effect of various carboxylic and amino acids on the uptake and translocation of root-absorbed Cd by maize (Zea mays). Statistically significant increases in Cd accumulation in various plant tissues with increasing supplementation of organic acids suggested the existence of Cd-organic acid interaction in soil-rhizosphere environment of the plant. The potentiality of phytochelators (organic acids) to form plant available organically bound Cd is discussed.     

Extraction of the metagenomic DNA and assessment of the bacterial diversity from the petroleum-polluted sites

The assessment of the microbial diversity of the entire community of a given habitat requires the extraction of the total environmental DNA. Metagenomic investigations of a petroleum-polluted habitat have its unique challenges. The specific methods were developed for the extraction of high-quality metagenome in good quantity from the petroleum-polluted saline and non-saline sites in Gujarat (India). The soil samples were washed to remove the toxic, hazardous organic pollutants which might interfere with the recovery of the metagenomic DNA. The metagenomic DNA extraction results were encouraging with the mechanical bead beating, soft lysis, and combination of both. The extracted DNA was assessed for its purity and yield followed by its application in the amplification of the 16S rRNA region. The amplicons were used for judging the molecular diversity by the denaturing gradient gel electrophoresis (DGGE). The microbial diversity was also analyzed statistically by calculating various diversity indices and principal component analysis (PCA). The results on the metagenomic diversity of the bacterial population among the three cohorts based on the culture-independent technique exhibited significant difference among the PAH sites and Okha–Madhi and Porbandar Madhavpur habitats.     

Amberlite XAD-7 impregnated with morpholine dithiocarbamate as trace metal extractant

Application of Amberlite XAD-7 impregnated with morpholine dithiocarbamate (MDTC) for separation and preconcentration of trace amounts of lead, copper, cobalt, iron, nickel, cadmium and zinc and determination by ICP-AES has been described. The optimum experimental parameters, such as pH, sample flow rate, eluent and effect of matrix ions on the preconcentration were investigated. Simultaneous enrichment of the seven metals was accomplished. The t _1/2 values for sorption are 2.9, 3.3, 3.7, 3.6, 2.8, 4.1 and 2.8 respectively for Pb(II), Cu(II), Co(II), Fe(III), Ni(II), Cd(II) and Zn(II). The method was applied for the determination of trace metal ions in seawater and natural water samples. The results have been compared with extraction GFAAS method.     

Transformation of nitrogen during vermicomposting of fly ash.

In view of environmental problems generated by large-scale production of fly ash, increasing attention is now being paid to the recycling fly ash as a source of plant nutrients in agriculture. However, the low amount of nitrogen in such materials forms a major constraint for such application. In the present study, the possibility of improving the N status in mixtures of fly ash and organic matter was investigated by adopting vermicomposting technology. Different combinations of fly ash and cow (Bos taurus) dung; namely fly ash alone, cow dung alone and fly ash + cow dung at 1:1, 1:3 and 3:1 ratios were incubated with and without epigeic earthworms (Eisenia fetida) for 50 days. The occurrence of N in different bio-available forms; namely easily mineralizable, NH4+ and NO3- tended to increase considerably in the series treated with earthworms. This behaviour was attributed primarily to increased microbiological activity in the vermicomposted samples and also to a considerable rise in the concentration of nitrogen-fixing bacteria in this series. Among the three combinations of vermicomposted fly ash and cow dung, the 1:1 mixture appeared to exhibit the highest availability of nitrogen.     

House fly (Musca domestica): a review of control strategies for a challenging pest

Musca domestica L. (Diptera: Muscidae), commonly called the house fly, is a major domestic, medical and veterinary pest that causes irritation, spoils food and acts as a vector for many pathogenic organisms. In this paper, the social and health problems related to housefly are introduced with the associated need to control its population. Physical and chemical methods of house fly control are briefly discussed. The main focus of this review is on the biological control methods for house fly control, that comprise botanical, fungal, bacterial and parasitoid agents. Although several biocontrol agents are still in the nascent stage, some of them (especially fungal and parasitoid agents) have shown reliable field performance and seem to be suitable candidates for commercialization. However, the majority of these laboratory and field studies have been conducted in the temperate region. It remains to be seen whether the application of biocontrol agents would be feasible in tropical environments. The integrated pest management practices, which can provide more reliable field performance, have also been discussed. A multi-dimensional approach that exerts control on all the life stages of house fly, but simultaneously preserves the fly's natural enemies could be an ecologically sustainable way of maintaining the fly populations below maximally acceptable limits.     

Graphitic carbon nitride: a sustainable photocatalyst for organic pollutant degradation and antibacterial applications

Environmental Science and Pollution Research - Recently, graphitic carbon nitride (GCN) has been found to be of great interest in various sustainable applications. In this study, a simple...     

Metacommunity dynamics over 16 years in a pyrogenic shrubland

Metacommunity theory allows predictions about the dynamics of potentially interacting species' assemblages that are linked by dispersal, but strong empirical tests of the theory are rare. We analyzed the metacommunity dynamics of Florida rosemary scrub, a patchily distributed pyrogenic community, to test predictions about turnover rates, community nestedness, and responses to patch size, arrangement, and quality. We collected occurrence data for 45 plant species from 88 rosemary scrub patches in 1989 and 2005 and used growth form, mechanism of regeneration after fire, and degree of habitat specialization to categorize species by life history. We tested whether patch size, fire history, and structural connectivity (a measure of proximity and size of surrounding patches) could be used to predict apparent extinctions and colonizations. In addition, we tested the accuracy of incidence-function models built with the patch survey data from 1989. After fire local extinction rates were higher for herbs than woody plants, higher for species that regenerated only from seed than species able to resprout, and higher for generalist than specialist species. Fewer rosemary specialists and a higher proportion of habitat generalists were extirpated on recently burned patches than on patches not burned between 1989 and 2005. Nestedness was highest for specialists among all life-history groups. Estimated model parameters from 1989 predicted the observed (1989-2005) extinction rates and the number of patches with persistent populations of individual species. These results indicate that species with different life-history strategies within the same metacommunity can have substantially different responses to patch configuration and quality. Real metacommunities may not conform to certain assumptions of simple models, but incidence-function models that consider only patch size, configuration, and quality can have significant predictive accuracy.