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101.
Phototransformation of the herbicide metsulfuron methyl was investigated on glass surface under sunlight and ultraviolet (UV) light and compared with dark condition. The half-lives of metsulfuron methyl under UV light and sunlight were found to be 0.5 and 7.8 days respectively. Rate of phototransformation followed first order kinetics with significant correlation coefficient. The major photoproducts were identified as methyl-2-sulfonyl-amino-benzoate, 2-amino-6-methoxy-4-methyltriazine and saccharin (O-sulfobenzoimide). Various metabolites from this study were identified by high performance liquid chromatography (HPLC). Authentic samples required for HPLC comparison were prepared in laboratory and characterized on the basis of nuclear magnetic resonance (NMR) and infra red (IR) spectral data. These metabolites were also identified from metsulfuron methyl treated wheat field soil. 相似文献
102.
H.C. Agarwal D.K. Singh V.B. Sharma 《Journal of environmental science and health. Part. B》2013,48(1):189-194
Abstract Persistence, metabolism and binding of 14C‐parathion in alkaline sandy loam soil under sub‐tropical conditions of Delhi were studied for 545 days. After 3 days of treatment, 14C‐residues declined to 41% of the amount applied. The dissipation curve was biphasic; an initial rapid phase (up to 7 days) followed by slow dissipation. The half life of dissipation was only 3.36 days for the first phase and 84 days for the slow phase. The overall half life was 64.5 days. The total residues at zero‐time were 10.65 μg/g dry soil and were almost totally extractable. The extracts consisted of parathion, 4‐aminophenol, 4‐nitrophenol and paraoxon. The bound residues gradually increased and accounted for the total residue at the end of one year (0.7 μg/g). 相似文献
103.
Summary In Kumaun Himalaya, India, 60 percent of the rural population is dependent on natural springs for water supply. The authors claim that substantial reductions in spring water discharges are due to losses in the indigenous oak forest coverage and its partial replacement by pine. Other factors, such as overall forest cover depletion and construction activities, combine to produce severe reductions in spring discharge rates.Drs Anil Singh and Ravindra Pande are members of academic staff at Kumaun University working in the Laboratory for Hydrological and Geomorphological Investigations in the Department of Geography. 相似文献
104.
105.
ABSTRACT: First order drainage channels originate when the tractive force exerted by flowing water is sufficient to move surface sediment. The amount of runoff available to move sediment is a function of geologic and climatic characteristics. An experimental analysis showed that soils derived from fine grained rocks had lower infiltration rates and higher runoff volume than soils derived from coarser grained rocks in a semi-arid climate. Root density and penetration increased in a more humid climate and increased infiltration rates. The number of first order channels was inversely proportional to the infiltration capacity of the soil. Each first order channel acts as a source area for surface runoff. The distribution of first order channel distances from the gage determines the timing of the delivery of water to the gage. A comparison of the frequency histogram of first order channel distances for drainage basins in Pennsylvania and their hydxographs of runoff from general storms showed marked similarity. This close correspondence indicated the shape of the surface runoff hydrograph and was largely controlled by the distribution of first order channel distances. 相似文献
106.
LR- 115 plastic track detectors have been used to measure indoor radon level in some dwellings of Una district, Himachal Pradesh, India. The annual average radon concentration in dwellings in most of the villages falls in the range of the action level recommended by the International Commission on Radiological Protection. The radon values in some of the dwellings exceed the action level and may be unsafe from the health hazard point of view. The indoor radon values are in general higher in winter than in summer. Uranium, radium and radon exhalation studies have also been carried out in soil samples collected from these areas. A good correlation is obtained between uranium concentration in the soil and indoor radon in dwellings. The soil radon exhalation rate also correlates with the uranium concentration in soil. 相似文献
107.
108.
Aquatic macroinvertebrate diversity in the Nanda Devi Biosphere Reserve (NDBR) was monitored for a period of twelve months (September 2000 to August 2001). All the important hydrological attributes were measured monthly for one year. Macroinvertebrates were sampled from three sites (S1$, S2$, & S3$) of the headwater stream Dhauliganga of NDBR. The present study revealed that the velocity of the water current, hydromedian depth, turbidity and dissolved oxygen in addition to nature and size of the bottom substrates have their significant impact on benthic invertebrate diversity. The ecological relevance of the measured hydrological attributes was investigated by comparing their degree of correlation with invertebrate density and diversity. Macroinvertebrate diversity was found to be highest (3.096 ± 0.03) in winter months (November–January) and lowest (2.816 ± 0.02) in monsoon months (July–August). The high diversity of macroinvertebrates may be due to low turbidity, high water transparency, optimum water temperature, high dissolved oxygen, low water velocity and suitable composition of the bottom substrates. 相似文献
109.
Gubrelay U Mehta A Singh M Flora SJ 《Journal of environmental biology / Academy of Environmental Biology, India》2004,25(1):65-73
Rats (male and female) were exposed to 0.5 mg/kg and 1 mg/kg cadmium as cadmium chloride for 3 days and subsequently sacrificed for cadmium concentration and other biochemical variables indicative of hepatic and renal damage. The absorption of cadmium was supported by biochemical changes, which were significantly higher in females than in males. This could be due to higher rate of intestinal absorption of cadmium in females than males. Male and female rats both showed relatively higher cadmium concentration in kidneys than in liver. Female rats also showed the similar trend in tissue metal levels as compared to male rats. However, hepatic and renal histopathological observations showed that female rats suffered from severe hepatic injury like hydropic degeneration of hepatocytes, granulation, bile duct proliferation etc. In comparison to female rats, male rats did not show much remarkable changes. Renal damage was more prominent in female than male in the form of renal tubular damage; most of the tubular nuclei were pyknotic, congestion of the boundary of cortex and medulla etc. The results suggested that females were comparatively more vulnerable to the toxic effects of cadmium than males. 相似文献
110.
Badarinath KV Madhavi Latha K Kiran Chand TR Gupta PK Ghosh AB Jain SL Gera BS Singh R Sarkar AK Singh N Parmar RS Koul S Kohli R Nath S Ojha VK Singh G 《Chemosphere》2004,54(2):167-175
Physical and optical properties of biomass burning aerosols in Northeastern region, India analyzed based on measurements made during February 2002. Large spatial extent of Northeastern Region moist tropical to moist sub-tropical forests in India have high frequency of burning in annual dry seasons. Characterization of resultant trace gases and aerosols from biomass burning is important for the atmospheric radiative process. Aerosol optical depth (AOD) observed to be high during burning period compared to pre- and post-burning days. Peak period of biomass burning is highly correlated with measured AOD and total columnar water vapor. Size distribution of aerosols showed bimodal size distribution during burning day and unimodal size distribution during pre- and post-burning days. Size distribution retrievals from biomass burning aerosols show dominance of accumulation mode particles. Weighted mean radius is high (0.22 microm) during burning period. Columnar content of aerosols observed to be high during burning period in addition to the drastic reduction of visibility. During the burning day Anderson sampler measurements showed dominance of accumulation mode particles. The diurnal averaged values of surface shortwave aerosol radiative forcing af biomass burning aerosols varies from -59 to -87 Wm(-2) on different days. Measured and modeled solar irradiances are also discussed in the paper. 相似文献