Controlled release, blind test of DNAPL remediation by ethanol flushing

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedial mechanism was enhanced dissolution based on the phase behavior of the water-ethanol-PCE system. Based on the knowledge of the actual PCE volume introduced into the cell, it was estimated that 83 L of PCE were present at the start of the test. Over a 40-day period, 64% of the PCE was removed by flushing the cell with an alcohol solution of approximately 70% ethanol and 30% water. High removal efficiencies at the end of the test indicated that more PCE could have been removed had it been possible to continue the demonstration. The ethanol solution extracted from the cell was recycled during the test using activated carbon and air stripping treatment. Both of these treatment processes were successful in removing PCE for recycling purposes, with minimal impact on the ethanol content in the treated fluids. Results from pre- and post-flushing partitioning tracer tests overestimated the treatment performance. However, both of these tracer tests missed significant amounts of the PCE present, likely due to inaccessibility of the PCE. The tracer results suggest that some PCE was inaccessible to the ethanol solution which led to the inefficient PCE removal rates observed. The flux-averaged aqueous PCE concentrations measured in the post-flushing tracer test were reduced by a factor of 3 to 4 in the extraction wells that showed the highest PCE removal compared to those concentrations in the pre-flushing tracer test.     

Extractive Spectrofluorometric Determination of Quinalphos Using Fluorescein in Environmental Samples

A simple, sensitive, convenient and low cost spectrofluorometric technique for determination of quinalphos is described. Quinalphos is decomposed with sodium ethoxide. Resultant sodium diethyl thiophosphate (Na-DETP) is extracted with a cationic fluorescein as ion pair complex into 1-chloro-2-nitrobenzene. The fluorescence of the ion pair, fluorescein-DETP is measured at 530 nm after excitation at 490 nm. This technique is applicable for the determination of quinalphos in water, food grains and vegetable samples up to ng level with Amberlite XAD-4.     

Release kinetics of β-cyfluthrin from its encapsulated formulations in water

Controlled release formulations of β-cyfluthrin, a non-systemic, broad spectrum contact insecticide, have been prepared using laboratory synthesized poly(ethylene glycol) (PEG) based amphiphilic copolymers. Copolymers of polyethylene glycols of different molecular weights and various dimethyl esters, viz. dimethyl isophthalate, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of β-cyfluthrin from developed controlled release (CR) formulations were studied in comparison with that of the commercially available 025 SC. Release from the commercial formulation was faster than with the developed CR formulations. The rate of release of encapsulated β-cyfluthrin from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of β-cyfluthrin in water ranged from 0.427 to 0.622 in the tested formulations. The release was diffusion controlled with a half-release time (t(?)) of 3.92 to 7.9 days in water from different formulations, and the period of optimum availability (POA) of β-cyfluthrin ranged from 1.4 to 20.5 days. The results suggest that the application rate of β-cyfluthrin can be optimized to achieve insect control at the desired level and period.     

Experimental analysis and parameter optimization on the reduction of NOx from diesel engine using RSM and ANN Model

Environmental Science and Pollution Research - The major emission sources of NOX are from automobiles, trucks, and various non-road vehicles, power plants, coal fired boilers, cement kilns,...     

Numerical modelling of nitrate transport in fractured porous media under non-isothermal conditions

Environmental Science and Pollution Research - Subsurface contamination is a frequent occurrence in fractured porous systems, posing a potential threat for the groundwater contamination. Tracking...     

Male reproductive toxicity of organophosphorous compounds: a review

Fertility is declining in many countries and there has been substantial interest in the potential adverse effects of exposure to environmental hazardous chemicals, including pesticides on male reproduction. Organophosphorous compounds (organophosphates, OP) constitute a heterogeneous category of chemicals specifically designed for the control of pests or plant diseases. OP are known to produce reproductive toxicity, resulting in a decrease in the fertility levels of humans and animals. This review article mainly focused on toxicity of some OP such as acephate, chlorpyrifos, diazinon, dimethoate, fenitrothion, malathion, and monocrotophos especially dealing with reproductive toxicity in males. Furthermore, this review deals with mode of action and clinical syndromes of OP. Considerable lab studies on animals concluded that OP produce adverse effects on male reproductive system.     

Exploring the diversity of neem bioactives as eco-benign pesticides: a reappraisal

Biological activity of neem seeds, leaves and bark is well-established as feeding deterrent and growth disrupter against insects and other arthropods. Neem is a valuable natural pesticide with low toxicity for vertebrates. However, it has not yet achieved a prominent place among pesticides due to its unstability. Recent studies have focused on newer formulations like microencapsulation, inclusion complexes, microemulsion, and granular formulations to enhance efficacy shelf life. Several studies have been undertaken on the effects of neem on predator, parasitoids, and other beneficial organisms as well as impact on the environment. Biotechnological interventions have been carried out for mass production of the active molecule. Once stable formulations of the active molecules are developed, the farming community will benefit the most due to the low toxicity and marked efficacy of neem insecticides.     

Prioritising development planning in the Indian semi-arid Deccan using sustainable livelihood security index approach

This paper presents the status of sustainable livelihood security index (SLSI) of Karnataka, the most drought prone state in the Southern part of India. Computation of ecological security index, economic efficiency index and social equity index, and finally SLSI were carried out at the district level for the entire state, using empirical data. The selected indicators were first normalised, and then using estimated weights, indices were computed. The results indicate that the state has a very low SLSI with only 27.6% of total geographical area (TGA) and 21.7% of population being placed in the ‘sustainable’ and ‘highly sustainable’ categories (covering 10 districts) while only 34% of the TGA covering six districts falls in the ‘moderately sustainable’ category. The remaining area, confined mostly to the northern parts of the state, comprising 14 districts (51.8% of the state’s TGA) is categorised as ‘less sustainable’ and ‘very less sustainable’ exposing 44.4% (27.14 million) of state’s population to the perils of uncertain rainfall, high soil erosion rates, high social inequality and poor resource use efficiency. There is an urgent need to reorient development programmes and prioritise development investments in these vulnerable districts so that they are provided resources and opportunities to improve their ecological (more forest cover and less soil erosion), economic (higher agricultural productivity) and social (improved health and education facilities and rural infrastructure) status and achieve sustainable levels of livelihood.     

Evaluation of reproductive and developmental toxicity of cypermethrin in male albino rats

The ever-increasing use of pesticides in the agricultural and public health has become a major cause of sterility in human and various other animals particularly in males. This study was sought to screen the toxic impacts of cypermethrin (synthetic pyrethroid) on reproduction and development. Twenty-four Wistar male rats divided into four groups were orally administered cypermethrin of daily doses 50, 75, or 100 mg?kg^?1 bwt per day for 45 days; and for developmental toxicity, 12 female rats were separated into two groups. Maternal rats (experimental) were administered cypermethrin (100?mg?kg^?1) by gavage daily from 6th to 17th day of gestation, and the control group was dosed only vehicle (olive oil). The body weights, fertility index, biochemical, enzymatic, hormonal, and histopathological parameters were the criteria used to evaluate the toxicity of cypermethrin. Study showed significant decline in the weight of testes, epididymises, seminal vesicles, and ventral prostate, and reduction in sperm counts both in epididymises and testes in chemical-treated animals. Pre- and post- fertility test showed 50%, 80%, and 100% negative results after treatment. A significant degenerative reduction in testicular glycogen and sialic acid was also noted. In contrast, protein and cholesterol levels of testes were significantly increased. In addition, acid phosphatase activity was significantly increased, while alkaline phosphatase, testosterone, leutinizing hormone (LH), and follicle stimulating hormone (FSH) levels were diminished. Histology of testes showed degenerative changes in seminiferous tubules. Cypermethrin exposure during gestation produced adverse effects markedly in females and fetuses.