Persistence and Dissipation of Readymix Formulations of Insecticides In/On Okra Fruits

Dissipation behaviour of ready mix polytrin C 44EC (profenophos 40% + cypermethrin 4%) and spark 36EC (triazophos 35%+.deltamethrin 1%) applied at 1 L/ha in okra crop during Kharif in year 2000 was studied at 0, 1, 3, 5 and 7 days after treatment. Dissipation on 7th day was found to be maximum (98.4%) for profenophos followed by triazophos (86.2%), cypermethrin (73.5%) and deltamethrin (55.7%). Half life (t1/2) values for the above insecticides were 1.35, 2.55, 4.11 and 7.60 days, respectively. All the insecticides followed a first order kinetics. Profenophos and triazophos followed a biphasic dissipation pattern with faster dissipation in phase I (0–1 days) and manifesting slower rate of dissipation in phase II (1–7 days).     

Assessment of genotoxic effects of lead in occupationally exposed workers

The genotoxicological effects in 200 lead acid storage battery recycling and manufacturing industry workers in Hyderabad along with matched 200 controls were studied. The genetic damage was determined by comet, micronucleus (MN), and chromosomal aberration (CA) test in peripheral blood lymphocytes (PBL). The MN test was also carried out in buccal epithelial cells (BECs). Pb in ambient air, blood Pb (B-Pb) concentrations, and hematological parameters were measured. The superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), and malondialdehyde (MDA) formed were also studied. The results of the present study showed that there was a statistically significant (P?P?GPx, and CAT levels were significantly decreased while GSH and MDA levels increased in exposed group when compared to control group. The present study suggests that environmental health standards should be enforced to control Pb contamination from battery industries to reduce human health risk.     

Microbe-induced changes in metal extractability from fly ash

A low cost and eco-friendly technology to bioremediate toxic metals associated with fly ash dumps that contaminate ground and surface water in and around fly ash settling ponds, was investigated. The impact of augmentation of fly ash tolerant bacterial strains, isolated from Typha latifolia growing naturally on fly ash dumps, was studied for metal extractability. It was observed that most of the bacterial strains either induced the bioavailability of Fe, Zn and Ni or immobilized Pb, Cr, Cu, Cd in the fly ash. However, there were few exceptions also. In case of Ni, eight strains enhanced metal mobility, while others caused metal immobilization. The findings also suggest that metal solublization and immobilization are specific to bacterial strains. While induced bioavailability of metals by bacteria may be used to accelerate the phytoextraction of metals from fly ash by hyper accumulator plants, immobilization of metals can check their migration to water reservoirs and reduce the human suffering in affected areas. Thus, bacteria serve the dual purpose and may result in the microbe- assisted phytoremediation of contaminated sites.     

Toxicology of arsenic in fish and aquatic systems

Arsenic (As) is found in waters such as seawater, warm springs, groundwater, rivers, and lakes. In aquatic environments, As occurs as a mixture of arsenate and arsenite, with arsenate usually predominating. The unrestricted application of As pesticides, industrial activities, and mining operations has led to the global occurrence of soluble As above permissible levels of 0.010 mg/L. Continuous exposure of freshwater organisms including fish to low concentrations of As results in bioaccumulation, notably in liver and kidney. As a consequence As induces hyperglycemia, depletion of enzymatic activities, various acute and chronic toxicity, and immune system dysfunction. Here we review arsenic chemistry, the occurrence of arsenic in aquatic system, the transformation and metabolism of arsenic; arsenic bioaccumulation and bioconcentration; behavioral changes; and acute and other effects such as biochemical, immunotoxic, and cytogenotoxic effects on fish.     

Chemometric characterization of river water quality

Various industrial facilities in the city of Varanasi discharge their effluent mixed with municipal sewage into the River Ganges at different discharge points. In this study, chemometric tools such as cluster analysis and box–whisker plots were applied to interpret data obtained during examination of River Ganges water quality. Specifically, we investigated the temperature (T), pH, total alkalinity, total acidity, electrical conductivity (EC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), nitrate nitrogen (N), phosphate (PO ₄ ^2? ), copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), iron (Fe), lead (Pb), and zinc (Zn) in water samples collected from six sampling stations. Hierarchical agglomerative cluster analysis was conducted using Ward’s method. Proximity distance between EC and Cr was the smallest revealing a relationship between these parameters, which was confirmed by Pearson’s correlation. Based on proximity distances, EC, Cr, Ni, Fe, N, COD, temperature, BOD, and total acidity comprised one group; Zn, Pb, Cd, total alkalinity, Cu, and phosphate (PO ₄ ^2? ) were in another group; and DO and pH formed a separate group. These groups were confirmed by Pearson’s correlation (r) values that indicated significant and positive correlation between variables in the same group. Box–whisker plots revealed that as we go downstream, the pollutant concentration increases and maximum at the downstream station Raj Ghat and minimum at the upstream station Samane Ghat. Seasonal variations in water quality parameters signified that total alkalinity, total acidity, DO, BOD, COD, N, phosphate (PO ₄ ^2? ), Cu, Cd, Cr, Ni, Fe, Pb, and Zn were the highest in summer (March–June) and the lowest during monsoon season (July–October). Temperature was the highest in summer and the lowest in winter (November–February). DO was the highest in winter and the lowest in summer season. pH was observed to be the highest in monsoon and the lowest in summer season.     

Parameters affecting azoxystrobin and imidacloprid degradation in biobed substrates in the North Indian tropical environment

Abstract

This study reports degradation of azoxystrobin (AZOXY) and imidacloprid (IMIDA) in the rice straw (RS)/corn cob (CC) and peat (P)/compost (C)-based biomixtures. The effect of biomixture preconditioning (10?days incubation prior to pesticide application), pesticide concentration and moisture content was evaluated. Results suggested that conditioning of biomixture greatly affected IMIDA degradation where half-life (t_1/2) was reduced by 5–9 times. This was attributed to higher microbial biomass carbon content and dehydrogenase activity in the conditioned biomixtures. Pesticide application in the conditioned biomixture did not show any negative impact on soil microbial parameters. Both pesticides degraded at faster rate in the rice straw-based biomixtures than in the corn cob-based biomixtures. Degradation slowed down with increase in initial concentration of pesticides in biomixture and 1.6–3.0 (AZOXY) and 2.4–3.6 (IMIDA) times increase in t_1/2 values was observed. The moisture content of biomixture showed positive effect on degradation which increased when moisture content was increased from 60 to 80% water holding capacity. The effect was significant for IMIDA degradation in the corn cob-based biomixtures and AZOXY degradation in the peat biomixtures. The rice straw-based biomixtures were better in degrading AZOXY and IMIDA and can be used in biopurification systems.     

Recovery of lithium and cobalt from waste lithium ion batteries of mobile phone

In view of the stringent environmental regulations, availability of limited natural resources and ever increasing need of alternative energy critical elements, an environmental eco-friendly leaching process is reported for the recovery of lithium and cobalt from the cathode active materials of spent lithium-ion batteries of mobile phones. The experiments were carried out to optimize the process parameters for the recovery of lithium and cobalt by varying the concentration of leachant, pulp density, reductant volume and temperature. Leaching with 2 M sulfuric acid with the addition of 5% H₂O₂ (v/v) at a pulp density of 100 g/L and 75 °C resulted in the recovery of 99.1% lithium and 70.0% cobalt in 60 min. H₂O₂ in sulfuric acid solution acts as an effective reducing agent, which enhance the percentage leaching of metals. Leaching kinetics of lithium in sulfuric acid fitted well to the chemical controlled reaction model i.e. 1 ? (1 ? X)^1/3 = k_ct. Leaching kinetics of cobalt fitted well to the model ‘ash diffusion control dense constant sizes spherical particles’ i.e. 1 ? 3(1 ? X)^2/3 + 2(1 ? X) = k_ct. Metals could subsequently be separated selectively from the leach liquor by solvent extraction process to produce their salts by crystallization process from the purified solution.     

Effective method for extraction of larvicidal component from leaves of Azadirachta indica and Artemisia annua Linn

Leaves of Artemisia annua linn. and Azadirachta indica were extracted in petroleum ether and hexane respectively by different methods of extraction i.e. cold extraction, reflux extraction and soxhlet extraction. The crude extract obtained was tested against third instar larvae of Anopheles stephensi. On comparison of larval mortality of crude extract obtained by these three methods, both soxhlet and reflux extraction method showed 100% mortality at 200 ppm after 48 hr in case of A. annua. However LC50 (20 ppm) value of crude extract obtained by soxhlet extraction showed better results than reflux extraction (35 ppm) method after 72 hr. In case of A. indica, crude obtained by soxhlet showed 100% mortality (after 48 hr) at 250 ppm and LC50 of 69 ppm at 72 hr. Reflux extraction does not show any appreciable mortality even at 250 ppm concentration.     

Bio-accumulation of some trace metals in the short-neck clam Paphia malabarica from Mandovi estuary, Goa

Monthly collections of the clam Paphia malabarica were made for period of 1 year from May 2002 to April 2003 from Verem, Mandovi estuary, Goa. Clams were categorised into two groups, 25-35 mm (small size) and 35-40 mm (big size). Significant difference was not observed in the accumulation of metals in the whole soft tissue between the two size groups. Irrespective of size, annual mean, metal content recorded as microg/g dry weight in the whole soft tissue was 3.8, 30.3, 13.5, 36.6 and 105.7, respectively, for Cd, Pb, Cu, Zn and Fe. Of the two toxic elements Cd and Pb, Cd content was almost uniform throughout the year except for a rise in September for the small size and October for the big size. Pb, on the other hand, was low from the beginning of the monsoon and exhibited distinct accumulation from December onwards up to April, May and, to some extent, June. The pattern was similar in both the size groups, the values being higher for the bigger size group. The three essential elements Cu, Fe and Zn exhibit trends similar to one another with peaks in September and December-January in both the size groups. Cadmium accumulation was highest in the mantle and adductor muscle, Lead, in foot, Copper, in digestive gland and gonad, and Zn and Fe, in gills. Correlation coefficient between different metal couplings as tested statistically revealed significant coupling for Zn-Fe (r 0.92) in the bigger size group, the same was observed between Cu-Fe (r 0.62) and Cd-Zn (r 0.94). Seasonal difference in Pb accumulation was highly significant.