Effect of hypobaric hypoxia on visual evoked potential at high altitude

The effect of hypobaric hypoxia on visual evoked potential (VEP) was studied in 27 male volunteers at sea level (SL), during the 1st and 3rd weeks of their stay at high altitude (HA) of 3,500 m and in the 1st week of their return to the sea level (RSL). Exposure to high altitude (HA) led to significant changes in VEP. The N1 wave latency of both right and left eye was significantly increased (P<0.05) during 3rd week of stay at the altitude which persisted even after the return to the sea level. The latency of P1 wave of both right and left eye was higher in 3rd week at high altitude but not significant statistically. But the delay in P1 latency persisted in 1st week of their return to sea level which was significant (p<0.05) statistically as compared to sea level. The latency of N2 wave was significantly decreased (P<0.05) during the 1st week of stay at HA and returned back to basal value in the 3rd week of stay at HA in both right and left eye. However, the changes observed in NPN complex in terms of wave latencies were within the physiological limits. The amplitude of wave N1-P1 of both the right and left eye did not show any change. The changes observed reflect the process of acclimatisation to 3500m high altitude.     

An overview of policies for managing polybrominated diphenyl ethers (PBDEs) in the Great Lakes basin

The Great Lakes are an important environmental and economic resource for Canada and the United States. The ecological integrity of the Great Lakes, however, is becoming increasingly threatened by a number of persistent, bio-accumulative and harmful chemicals that enter the Great Lakes ecosystem through fluvial and atmospheric deposition. Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardant, are among such chemicals, whose concentration in the Great Lakes has greatly increased in recent years. Despite growing concern over the possible health and environmental effects of these compounds, only four of the eight Great Lakes states have enacted regulations to ban/restrict the use of PBDE while the two Canadian Great Lakes provinces are yet to endorse any regulation. Of the three main commercial PBDE mixtures (pentaBDE, octaBDE and decaBDE), penta- and octaBDE are no longer manufactured or imported into the United States and Canada. DecaBDE, however, still finds use in a variety of products. In the present paper, the authors review the current regulations and policies for managing PBDEs in the Great Lakes jurisdictions and briefly review commercially available non-bromine chemical alternatives to PBDE. As these alternatives are comparatively more expensive than PBDE, future adoption of more eco-friendly flame retardants by the polymer industry will likely depend on stricter legislation regulating the use of PBDE and/or an increased public demand for PBDE-free products.     

Phototransformation of clodinafop-propargyl

Photodegradation of the herbicide clodinafop-propargyl was investigated on glass surface under sunlight and UV light. Four photoproducts were identified by NMR, IR, and MS. Major photolysis products were 2-[(5-chloro-3-fluoro-2-pyridyloxy) phenoxy] propanoic acid and prop-2-ynyl-2-[(5-chloro-3-hydroxy-2-pyridyloxy) phenoxy] propanoate, while minor were ethyl 2-[(5-chloro-3-fluoro-2-pyridyloxy) phenoxy] propanoate and 1-hydroxypropanyl-2-[(5-chloro-3-fluoro-2-pyridyloxy) phenoxy] propanoate. Rate of photodegradation followed first-order kinetics with significant correlation coefficient. The major photoproducts were observed in maximum quantity on the 7th and 10th day and further degraded within 15-20 days.     

Status and interconnections of selected environmental issues in the global coastal zones

This study focuses on assessing the state of population distribution, land cover distribution, biodiversity hotspots, and protected areas in global coastal zones. The coastal zone is defined as land within 100 km of the coastline. This study attempts to answer such questions as: how crowded are the coastal zones, what is the pattern of land cover distribution in these areas, how much of these areas are designated as protected areas, what is the state of the biodiversity hotspots, and what are the interconnections between people and coastal environment. This study uses globally consistent and comprehensive geospatial datasets based on remote sensing and other sources. The application of Geographic Information System (GIS) layering methods and consistent datasets has made it possible to identify and quantify selected coastal zones environmental issues and their interconnections. It is expected that such information provide a scientific basis for global coastal zones management and assist in policy formulations at the national and international levels.     

Seasonal variation of indoor radon in dwellings of Malwa region, Punjab

Indoor radon measurements in 105 dwellings belonging to 21 villages of Muktsar and Ferozepur districts of Malwa region, Punjab, have been carried out, using LR-115 type II cellulose nitrate films in the bare mode. The annual average indoor radon value in the study area varies from 76.25 to 145.50 Bq m⁻³, which is well within the recommended action level [ICRP, 1993. Protection against radon at home and work. Annals of ICRP, ICRP Publication, p. 65]. Seasonal variation of indoor radon shows high values in winter and low values in summer. The winter/summer ratio of radon concentration has been computed for all 105 dwellings. The winter/summer ratio of indoor radon ranges from 0.84 to 1.89 with an average of 1.46. The indoor radon values obtained in the present investigation are more than the world average of 40 Bq m⁻³     

Mitigating nitrous oxide and methane emissions from soil in rice-wheat system of the Indo-Gangetic plain with nitrification and urease inhibitors

Mitigation of methane (CH4) and nitrous oxide (N2O) emissions from soil is important to reduce the global warming. Efficacy of five nitrification inhibitors, i.e. neem (Azadirachta melia) cake, thiosulphate, coated calcium carbide, neem oil coated urea and dicyandiamide (DCD) and one urease inhibitor, hydroquinone, in mitigating N2O and CH4 emissions from fertilized soil was tested in rice-wheat system in the Indo-Gangetic plains. The closed chamber technique was used for the collection of gas samples, which were analyzed using gas chromatography. Reduction in N2O emission on the application of nitrification/urease inhibitors along with urea ranged from 5% with hydroquinone to 31% with thiosulphate in rice and 7% with hydroquinone to 29% with DCD in wheat crop. The inhibitors also influenced the emission of CH4. While application of neem coated urea, coated calcium carbide, neem oil and DCD reduced the emission of CH4; hydroquinone and thiosulphate increased the emission when compared to urea alone. However, the global warming potential was lower with the inhibitors (except hydroquinone) as compared to urea alone, suggesting that these substances could be used for mitigating greenhouse gas emission from the rice-wheat systems.     

Emission of nitrous oxide from rice-wheat systems of Indo-Gangetic plains of India

Nitrous oxide (N₂O) accounts for 5%of the total enhanced greenhouse effect and responsiblefor the destruction of the stratospheric ozone. The rice-wheat cropping system occupying 26 million ha ofproductive land in Asia could be a major source ofN₂O as most of the fertilizer N in this region isconsumed by this system. Emission of N₂O asinfluenced by application of urea, urea plus farm yardmanure (FYM), and urea plus dicyandiamide (DCD), anitrification inhibitor, was studied in rice-wheatsystems of Indo-Gangetic plains of India. Total emissionof N₂O-N from the rice-wheat systems varied between654 g ha^-1 in unfertilized plots and 1570 g ha^-1 in urea fertilized plots. Application of FYM and DCDreduced emission of N₂O-N in rice. The magnitude ofreduction was higher with DCD. In wheat also N₂O-Nemission was reduced by DCD. FYM applied in rice had noresidual effect on N₂O-N emission in wheat. In riceintermittent wetting and drying condition of soilresulted in higher N₂O-N emission than that ofsaturated soil condition. Treatments with 5 irrigationsgave higher emissions in wheat than those with 3irrigations. In rice-wheat system, typical of a farmer'sfield in Indo-Gangetic plains, where 240 kg N isgenerally applied through urea, N₂O-N emission is1570 g ha^-1 (0.38% of applied N) and application ofFYM and DCD reduced it to 1415 and 1096 g ha^-1,respectively.