Intra-monsoonal variation of zooplankton population in the Sundarbans Estuarine System,India

The present study was conducted during July 2013 (early phase of monsoon or EM) and September 2013 (later phase of monsoon or LM) to ascertain the intra-monsoonal variation on zooplankton, by selecting 15 study stations in the river Saptamukhi, one of the main estuaries in the Sundarbans Estuarine System (SES). In 2013, SES experienced an unusually high monsoonal rainfall also exacerbated by cloud burst event at Himalayan region (upper stretches of SES) which tremendously increased the river runoff. The present work was aimed to decipher the effect of this unusual precipitation during the monsoon season on zooplankton assemblages along with different hydrological parameters. The abundance of zooplankton was recorded as lower during EM compared to LM. Altogether, 56 zooplankton taxa were identified with copepods forming the predominant population. Thirty-three copepod species were reported with 25 calanoid species forming the bulk of the biomass followed by 5 and 3 species of cyclopoids and harpacticoid, respectively. A combination of multivariate cluster analysis, biotic indices, and canonical correspondence analysis revealed noticeable alterations in the zooplankton community structure across the spatio-temporal scale. Furthermore, significant intra-monsoonal changes in zooplankton population correlated with several hydrological parameters were clearly noticed. Paracalanus parvus, Bestiolina similis and Oithona similis were observed to be the most dominant copepod species in both sampling periods. The result of the present study provides new insight on estuarine zooplankton community after unusual rainfall during monsoon season, and provides further evidence to support the conservation and management of the SES ecosystem.     

Seasonal and spatial variation of Yamuna River water quality in Delhi, India

Street dust was collected from five roads with different traffic volumes in the metropolitan area of Beijing and separated into five size fractions. Concentrations of polycyclic aromatic hydrocarbons (PAHs) adsorbed on street dust in different size ranges and their correlation with specific surface area and total organic carbon (TOC) were investigated. Results show that the concentration of 16-PAHs of sieved samples ranges from 0.27 to 1.30 mg/kg for all the sampling sites. Particles smaller than 40 μm in diameter have the highest 16-PAHs concentration among all of the size ranges for street dust from the four sampling sites with vehicles running on. PAHs with three or four rings account for 68% of the overall 16-PAHs on average. Remarkable positive correlation exists between 16-PAHs concentration and specific surface area with R ² values from 0.7 to 0.96 for the four sampling sites with vehicles running on. The relationship between the concentration of 16-PAHs and TOC is less clear.     

Thiamethoxam degradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> and <Emphasis Type="Italic">Bacillus</Emphasis> strains isolated from agricultural soils

Twelve bacterial species were evaluated to know the degradation pattern of thiamethoxam in liquid medium. All the bacterial species could actively degrade phorate in a mineral salt medium containing phorate (50 μg ml^–1) as sole carbon source. As these species have ability to degrade, we used these for the degradation of thiamethoxam—a neonicoitinoids. Screening of 12 active phorate-metabolizing bacterial species resulted in selection of Bacillus aeromonas strain IMBL 4.1 and Pseudomonas putida strain IMBL 5.2 causing 45.28 and 38.23 % thiamethoxam (50 μg ml^?1) reduction, respectively, in 15 days as potential thiamethoxam degrading species. These two bacterial species grew optimally at 37 °C under shake culture conditions in MSMT medium raised with initial pH of 6.0–6.5 and use of these optimum cultural conditions resulted in improved thiamethoxam degradation by these bacterial species. These species caused maximum thiamethoxam degradation only in the presence of thiamethoxam as sole source of carbon and energy and the same was reduced in the presence of easily metabolize able carbon (C₀ and C₁) and nitrogen ((N₀, N₁ and N₂) sources. This could be attributed to involvement of repressible metabolic pathways, reactions of which are inhibited by the presence of easily available nutrients for growth. Besides above, qualitative analysis of thiamethoxam residues by gas liquid chromatography revealed complete metabolization of thiamethoxam without detectable accumulation of any known thiamethoxam metabolites.     

Water pollution of Sabarmati River—a Harbinger to potential disaster

River Sabarmati is one of the biggest and major river of Gujarat that runs through two major cities of Gujarat, Gandhinagar and Ahmedabad and finally meets the Gulf of Khambhat (GoK) in the Arabian Sea. A study was conducted to evaluate the water quality of this river, as it could possibly be one of the major sources for filling up Kalpasar, the proposed man-made freshwater reservoir supposed to be the biggest one in the world. A total of nine sampling stations were established covering 163 km stretch of the river from upstream of Gandhinagar city to Vataman near Sabarmati estuary. Physicochemical (temprature, pH, salinity, chloride, total dissolved solids, turbidity, dissolved oxygen, biochemical oxygen demand, phenol, and petroleum hydrocarbons), biological (phytoplankton), and microbiological (total and selective bacterial count) analyses indicated that the river stretch from Ahmedabad-Vasana barriage to Vataman was highly polluted due to perennial waste discharges mainly from municipal drainage and industries. An implementation of sustainable management plan with proper treatment of both municipal and industrial effluents is essential to prevent further deterioration of the water quality of this river.     

Fungicidal activity and molecular modeling of fusarubin analogues from Fusarium oxysporum

Abstract

Fusarubin analogues of Fusarium oxysporum f. sp. ciceris were investigated for antifungal activity in vitro against five soil borne phytopathogenic fungi. 3-O-Methyl-8-O-methyl-fusarubin was inhibitory towards S. sclerotiorum (EC₅₀ 0.33?mmol L^?1) and Sclerotium rolfsii (EC₅₀ 0.38?mmol L^?1). A structure–antifungal activity relationship of fusarubin analogues was established from their activity performance. Possible mechanism of action of these compounds was studied using molecular docking and simulations against three target enzymes which revealed receptor ligand binding affinity. Docking of 3-O-methyl-8-O-methyl-fusarubin into the succinate dehydrogenase site revealed formation of salt bridge, hydrogen bond, π–anion, π–alkyl, and Van der Waals interactions.     

Click chemistry approach to conventional vegetable tanning process: accelerated method with improved organoleptic properties

Click chemistry approaches are tailored to generate molecular building blocks quickly and reliably by joining small units together selectively and covalently, stably and irreversibly. The vegetable tannins such as hydrolyzable and condensed tannins are capable to produce rather stable radicals or inhibit the progress of radicals and are prone to oxidations such as photo and auto-oxidation, and their anti-oxidant nature is well known. A lot remains to be done to understand the extent of the variation of leather stability, color variation (lightening and darkening reaction of leather), and poor resistance to water uptake for prolonged periods. In the present study, we have reported click chemistry approaches to accelerated vegetable tanning processes based on periodates catalyzed formation of oxidized hydrolysable and condensed tannins for high exhaustion with improved properties. The distribution of oxidized vegetable tannin, the thermal stability such as shrinkage temperature (T _s) and denaturation temperature (T _d), resistance to collagenolytic activities, and organoleptic properties of tanned leather as well as the evaluations of eco-friendly characteristics were investigated. Scanning electron microscopic analysis indicates the cross section of tightness of the leather. Differential scanning calorimetric analysis shows that the T _d of leather is more than that of vegetable tanned or equal to aldehyde tanned one. The leathers exhibited fullness, softness, good color, and general appearance when compared to non-oxidized vegetable tannin. The developed process benefits from significant reduction in total solids and better biodegradability in the effluent, compared to non-oxidized vegetable tannins.     

High reduction of 4-nitrophenol using reduced graphene oxide/Ag synthesized with tyrosine

There is a demand for the development of environmental friendly methods for the synthesis of graphene composites. Reduced graphene oxide/silver (RGO/Ag) nanocomposites are very good catalysts. Here, we propose a simple, green method for the synthesis of RGO/Ag nanocomposite using the amino acid tyrosine as bioreductant and stabilizing agent. RGO/Ag nanocomposite was characterized by using various analytical techniques and studied for its catalytic degradation of 4-nitrophenol. Results of attenuated total reflectance Fourier transform infrared spectroscopy and Zeta potential at ?55 mV reveal the surface capping of tyrosine onto the reduced graphene oxide nanosheets. RGO/Ag nanocomposites show excellent catalytic reduction of 4-nitrophenol with NaBH₄, when compared to actual individual silver nanoparticles.     

Kinetics and isotherm modeling of azoxystrobin and imidacloprid retention in biomixtures

The paper reports the kinetics and adsorption isotherm modeling for imidacloprid (IMIDA) and azoxystrobin (AZOXY) in rice straw (RS)/corn cob (CC) and peat (P)/compost (C) based biomixtures. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intraparticle diffusion models were used to describe the kinetics. The adsorption data were subjected to the Langmuir and the Freundlich isotherms. Results (r²_Adj values) suggested that the modified Elovich model was the best suited to explain the kinetics of IMIDA sorption while different models explained AZOXY sorption kinetics in different biomixtures (PFO in RS?+?C and RS?+?P; PSO in CC?+?P and Elovich in CC?+?C). Biomixtures varied in their capacity to adsorb both pesticides and the adsorption coefficient (K_d) values were 116.8–369.24 (AZOXY) and 24.2–293.4 (IMIDA). The Freundlich isotherm better explained the sorption of both pesticides. Comparison analysis of linear and nonlinear method for estimating the Freundlich adsorption constants was made. In general, r²_Adj values were higher for the nonlinear fit (AZOXY?=?0.938–0.982; IMIDA?=?0.91–0.970) than the linear fit (AZOXY?=?0.886–0.993; IMIDA?=?0.870–0.974) suggesting that the nonlinear Freundlich equation better explained the sorption. The rice straw-based biomixtures performed better in adsorbing both the pesticides and can be used in bio-purification systems.     

Pollution resistance assessment of plants around chromite mine based on anticipated performance index,dust capturing capacity and metal accumulation index

Environmental Science and Pollution Research - Plant species sustaining under a polluted environment for a long time are considered as potentially resistant species. Those plant species can be...     

Volatilization of mercury from natural water by a broad-spectrum Hg-resistantBacillus pasteurii strain DR2

Summary A broad-spectrum mercury-resistant bacterial strain was isolated from contaminated water and was identified as Bacillus pasteurii strain DR2. It could volatilize Hg-compounds including organomercurials from its growth media. It utilized several aromatic compounds as a sole source of carbon. The bacterial strain eliminated HgCl₂ from sterile river water and the presence of benzene, toluene, naphthalene and nitrobenzene at 1 mM concentration in the system increased the rate of mercury volatilization, the volatilization rate being highest with benzene. When 1.7×10⁷ cells of this bacterial strain were added per ml of non-sterile water the bacterial strain volatilized more than 90 percent of mercury from mercuric chloride and organo-mercurials like PMA, thiomersol and methoxy ethyl mercuric chloride (MEMC). In the absence of this bacterial strain the volatilization of PMA and MEMC due to the presence of other Hg-resistant organisms in nonsterile polluted water ranged between 20–25 percent and of HgCl₂ was about 40 percent. However, in the presence of B. pasteurii DR2 volatilization of these Hg-compounds from non-sterile water increased by 20–40 percent. In the presence of 1 mM benzene the rate of mercury volatilization was even higher. In all the cases the rate of volatilization was higher in the first seven days than in the next seven days.Professor A. Mandal, MSc, PhD is Head of the Department of Biochemistry at the University College of Science, 35 Ballygunge Circular Road, Calcutta 700019, to whom correspondence should be addressed. His co-workers are Dr K. Pahan, Postdoctoral Associate, Department of Cell Biology and Paediatrics, Medical University of South Carolina, USA; Dr J. Chaudhuri, Senior Lecturer, Department of Molecular Biology, BKC College, Calcutta, India; Dr D.K. Ghosh, Postdoctoral Associate, Department of Biochemistry, University College of Science, Calcutta, India; Dr R. Gachhui, Postdoctoral Associate, The Cleveland Clinic Foundation, Cleveland, USA; and Dr S. Ray, Postdoctoral Associate, The Johns Hopkins University School of Hygiene and Public Health, Department of Biochemistry, Baltimore, USA.