Jacob Chacko

Determination and distribution of endosulfan and malathion in an indian estuary

Abstract A field survey was conducted to determine the spatial and seasonal distribution of two very common pesticides, Endosulfan and Malathion, in Cochin estuary, India. Six sampling stations along the estuary were identified and analyses were carried out during premonsoon, monsoon and postmonsoon seasons. Pesticide levels were higher during the premonsoon period than during the postmonsoon season. Throughout the monsoon season, the estuary remained largely free of the pesticides except at the mid-estuarine region which was characterized by prominent agricultural runoff. One of the sampling sites located in the riverine area was designated as “pesticide-loading site” in view of its proximity to the pesticide-manufacturing unit.

Intrazeolite cobalt(II), nickel(II) and copper(II) complexes of 3-formylsalicylic acid for oxidation reactions

Y zeolite encapsulated Co(II), Ni(II) and Cu(II) complexes of 3-formylsalicylic acid were synthesized and characterized by chemical analyses, SEM, XRD, surface area, pore volume and IR, reflectance and EPR spectroscopy with a view to confirm the encapsulation of complexes and to arrive at the composition, structure and geometry of encapsulated complexes. The analytical data indicate a composition corresponding to the binuclear complex of 3-formylsalicylic acid. The characterization data show the absence of extraneous complexes, retention of zeolite crystalline structure and encapsulation in the cavities. The shift of carbonyl-stretching frequencies of both the aldehyde and carboxylate groups of 3-formylsalicylic acid suggests binuclear coordination in the encapsulated complexes. Tetrahedral, octahedral and tetrahedrally distorted square planar symmetries are tentatively assigned to the encapsulated complexes of Co(II), Ni(II) and Cu(II) ions, respectively. Encapsulated Cu(II) complex is catalytically very efficient as compared to other complexes for the partial oxidation of benzyl alcohol and ethylbenzene and is stable to be recycled without much deterioration.

Malathion sorption by sediments from a tropical estuary

Abstract The sorptional behaviour of an organophosphorus pesticide, Malathion, has been investigated by an experiment designed to assess the effects of variations in pesticide concentrations as well as of environmental influences on sediment samples from a tropical estuary. Three different sediment samples were exposed to varying concentrations of Malathion for different periods of time. The experimental data were subjected to simple regressional analysis and the results were analysed by the Freundlich, Elovich and Langmuir models. It was observed that the Malathion adsorption was essentially a heterogenous multi-layer interaction. The relevance of solubility and partition coefficient of the solute, organic carbon content of the sediment as well as the energetics involved in controlling and regulating the sorption process have been examined.

Distribution of organic carbon in tropical mangrove sediments (Cochin, India)

Surficial sediments were sampled every month from three mangrove regions around the metropolis of Cochin (India). Sedimentary organic carbon content exhibited wide seasonal fluctuations. The hydrology of the mangrove system is regulated mainly by high rainfall during the monsoon and by tidal inundation. The results indicated the role of tidal activity and sediment texture in the preservation and retention of organic matter.

Distribution of organochlorine pesticides in a tropical waterway: HCH isomers

Pesticide residue levels in the aquatic systems are scattered and fragmentory in India. A systematic analysis of the distribution pattern of the common organochlorine pesticide Hexachlorocyclohexane (HCH) and its isomers in the waters of the tropical positive estuarine system (the Cochin Estuarine System) has been carried out for the first time. The average concentrations of HCH ranged between 0.013 and 1.125 μg 1−1. α‐HCH was found to be at an appreciable concentrations throughout the study area and formed the highest percentage (90%) of all isomers of the HCH family

Speciation and estuarine modification of zinc during transport in a tropical fluvial environment

The estuarine modifications of zinc during its transport through the tropical Cochin estuary was evaluated by speciation studies. The fractions of zinc reported include Chelex‐100 labile and organically bound metal in the aqueous phase and exchangeable and total metal in the particulate phase. The behaviour of each of the above fraction in relation to the environmental factors such as salinity, suspended solids load and DOC is presented. The behavioural profile indicates the removal of all the fractions in the saline region of this tropical estuary. The mass balance indicated accumulation of zinc in the estuarine regions.

Organophosphorus pesticide adsorption variability in diverse estuarine sediments

This paper reports on the sorption variabilities of two Organophosphorus pesticides, namely Malathion (MT) and Methyl parathion (MPT) in three distinctly different estuarine sediment types. The adsorption capacity of the pesticide has been quantified in terms of the Sorptive index, S for varying exposure times. An equilibrium/partition model has been proposed to characterize the pesticide, sediment interactions.

Sublethal effects of copper and mercury on some biochemical constituents of the estuarine clam Villorita cyprinoides var. cochinensis (Hanley)

The usefulness of sentinal organisms in environmental pollution monitoring or surveillance programs has been well established. A particularly significant attribute of sublethal physiological response is that it is amenable to both laboratory and field measurements unlike traditional toxicant testing. Such methods could be employed to develop environmental quality models to predict the biological effects of potential pollutants as well as to directly monitor the effects in the environment. This paper describes the effect of sublethal amounts of two well known aquatic pollutants namely Cu and Hg on an estuarine clam Villorita cyprinoides var. cochinensis. The changes in carotenoid content (total and unsaponifiable), metabolic rate, lactic acid as well as glycogen contents of the tissues of the clam exposed to sublethal amounts of Cu(II) and Hg(II) were investigated over a range of time.

Synthesis of silver nanoparticles and of self assembled supramolecules from marine humic acid

This paper reports on the synthesis of spherical silver nanoparticles and the consequent formation of self-assembled humic-silver supramolecules. The method described in this article is eco-friendly and the supramolecules formed were stable for several months. The silver nanoparticles themselves were synthesised from humic acid extracted from mudbank sediments (from Aleppey, south west coast of India) and characterised by UV-Vis spectra and HRTEM. Tuning of dipole and quadrouple oscillation of spherical nanoparticles was achieved. Variable self-assembled distribution mechanism of humic-silver nanoparticles in the solution responsible for quadrouple intensification was investigated.

Support effects on Cu-Cr/Al2O3 catalysts for CO oxidation

Cu and Cu-Cr based catalysts were prepared on γ alumina support to study carbon monoxide oxidation activity and resistance to thermal and hydrothermal deactivation. The effect of modification of alumina with TiO2 or CeO2 on the overall performance of the catalyst was also investigated. In general, all the Cu catalysts were found to be more active than the corresponding Cu-Cr catalysts. Performance of the Cu and Cu-Cr catalysts prepared on various supports varies as Al2O3 Al2O3-TiO2 > Al2O3-CeO2. The pronounced improvement of ceria doped catalysts is due to its ability to store oxygen under transient conditions and also to impart stability for active components against thermal and hydrothermal deactivation.