Modeling the dispersion of drilling muds using the bblt model: the effects of settling velocity

The benthic boundary layer transport (bblt) model was widely used in the Atlantic Canadian offshore region to assess the potential impact zones from drilling wastes discharges from offshore oil and gas drilling. The current version of the bblt uses a single-class settling velocity scenario, which may affect its performance, as settling velocity is size, shape, and material dependent. In this study, the effects of settling velocity on bblt predictions were assessed by replacing this single-class settling velocity scenario with a multi-class size-dependent settling velocity scenario. The new scenario was used in a hypothetical study to simulate the dispersion of barite and fine-grained drilling cuttings. The study showed that the effects of settling velocity on bblt predictions are spatial, temporal, and material dependent.     

Biocatalytic amidation of carboxylic acids and their antinemic activity

A series of novel N-alkyl substituted amides, synthesized by enzyme catalysis, were evaluated against root-knot nematode, Meloidogyne incognita and found to have potential antinemic activity. The corresponding amides were prepared by the condensation of equimolar amounts of carboxylic acids with different alkyl amines in the presence of Candida antarctica lipase at 60–90°C in 16–20 h. The reactions were carried out in a non - solvent system without the use of any activating agents. All the products were obtained in appreciable amounts and the yields for different compounds varied between 77.4–82.3%. The synthesized compounds were characterized using spectroscopy techniques namely Infra Red (IR) and Nuclear Magnetic Resonance (NMR) (¹H and ¹³C). Nematicidal activity of synthesized amides was evaluated against J₂s of Meloidogyne incognita at 500, 250, 125 and 62.5 ppm concentrations after 24 h, 48 h and 72 h of exposure. Among all the tested compounds, N-propyl-butyramide, N-propyl-pentanamide and N-propyl-hexanamide were found to possess significant activity with LC₅₀ values of 67.46, 83.49 and 96.53 respectively. N-propyl-butyramide with LC₅₀ value of 67.46 ppm was found to be most active amide against J₂s of Meloidogyne incognita. The bioactivity study showed that an increase in alkyl chain significantly decreased the activity of amides against root-knot nematode.     

Development of socio-economic impact assessment methodology applicable to large water resource projects in India

SUMMARY

The genesis of socio-economic impact assessment (SIA) in India is pressure from funding agencies like the World Bank, Asian Development Bank, and similar institutions. Of late, these institutions have stressed appraisal of environmental concerns as a pre-condition for financial support to large infra-structure projects. However, SIA studies are easier to conceptualise than to implement, because the issues involved are nebulous, complex, highly nuanced, difficult to define, and not easily amenable to quantification. These are some of the reasons for the cursory treatment of socioeconomic impact studies in India as a formality to satisfy monitoring and funding agency requirements and not as a tool for ensuring maximum social good through the developmental process. However, proper implementation of the concept of SIA in essential in attaining the goals of sustainable development. Ensuring social justice, i.e. preventing the continued impoverishment, displacement, social dislocation, and marginalisation of the weaker sections of Indian society, who always seem to bear the burden of adverse effects of such large infra-structure projects in disproportionate numbers, is also a goal of SIA. Increasing ambivalent attitudes and mounting opposition towards the implementation of large water resources projects of late in India necessitate systematic, transparent, and exhaustive consideration of all relevant socioeconomic issues before implementation of such projects. The objective of this study was to develop a comprehensive methodology for SIA for large water resource projects in India. The methodology was based on the review of the literature and other means and implicitly addresses the major goals of SIA — sustainable development and the achievement of social justice related to development.     

Use of pyrite for pH control during hydrogenotrophic denitrification using metallic iron as the ultimate electron donor

Maintenance of stable pH through provision of adequate buffering is of importance to many pollutant removal processes where either acid or base is produced as a reaction product. The objective of this study was to evaluate the suitability of pyrite (FeS2) as an in situ buffering agent for arresting pH increase during metallic iron assisted hydrogenotrophic denitrification. Pyrite is considered promising for this purpose because it is a mineral which is unstable under moderately reducing, i.e., anoxic conditions, where such denitrification takes place, and therefore expected to consume hydroxide ions produced due to hydrogenotrophic denitrification reactions and get oxidized to ferrous hydroxide Fe(OH)2. The theoretical basis for this buffering action was established through chemical speciation studies using the chemical speciation software, MINEQL+. Experimental evaluation of the buffering efficiency of pyrite showed that it was effective in arresting pH increase associated with denitrification in both batch systems and during flow through reactive porous media. Further, addition of pyrite had no demonstrable toxic effect on the denitrifying microorganisms, though elevated sulfate concentration was seen in the effluent after denitrification.