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11.
Landscape characterization gives an overall information on the status of Land Use and Land Cover(LULC),changes in its composition and the impact of natural and human influences operating at different spatial and temporal scales.This information can be used to monitor changes in natural forest resources and protected areas,delineate potential conservation areas and can serve in effective management of ecologically fragile landscapes.In the present study,geo-spatial tools were used to characterize the landscape of Sariska National Park and its surroundings.Satellite data was used to prepare LULC maps for 1989 and 2000,change detection analysis and computation of landscape metrics.Climatic data,field records and modeling tools were used to map the po-tential spread of two invasive species,Prosopis juliflora and Adhatoda vasica.The results show that the forest area increased from 1989 to 2000,indicating better management practices.Landscape metrics(PAFRAC,PLADJ and AI)also support this argument.Improvements in the degraded forest can further enhance this effect.The entire reserve however is suitable for the invasion of P.juliflora and A.vasica but is more pronounced in Boswellia serrata and Anogeissus pendula-Acacia catechu(open)forests.A detailed landscape characterization map can help forest managers to make important policy decisions concerning issues such as in-vasive species. 相似文献
12.
The concentration of trace metals was measured in groundwater samples collected from Malwa region of Punjab, India. The samples were analyzed by using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The results were compared with permissible limits prescribed by various health and environmental protection agencies. The concentrations of trace metals such as Mn, Se, Mo, Cd, Sb and Pb were higher than their respective permissible limits at some sampling sites. The total hazard index (HItotal) (summing the hazard index through ingestion and dermal routes) at all the sampling sites exceeded or nearing unity, indicating the presence of non-carcinogenic health effects from ingestion of groundwater and dermal contact with groundwater. The results reveal that the total excess lifetime cancer risk (ELCRtotal) of metals exposure was in accordance with the acceptable lifetime risks for carcinogens in drinking water. 相似文献
13.
P. S. Meenu S. Sowmya R. Asha Latha B. S. Shashank D. N. Singh 《Geotechnical and Geological Engineering》2017,35(2):607-614
Dependence of soil suction on factors such as formation of the soil, its particle size, mineralogy, pore-size distribution characteristics, water content, fabric, stress history and presence of salts has been extensively investigated by researchers. However, the influence of the microbial presence and its activity on the soil suction has not yet received researchers’ attention. With this in view, a methodology that facilitates investigation regarding the presence of ‘soil-microbial interface’, which has been termed as ‘bio-geo interface’, has been proposed in this study. Furthermore, the influence of this ‘interface’ on suction characteristics of such soils has also been investigated and the utility of the proposed methodology in addressing such issues, successfully, has been demonstrated. 相似文献
14.
C.R. Asha Devi R. JyothibabuP. Sabu Josia JacobH. Habeebrehman M.P. PrabhakaranK.J. Jayalakshmi C.T. Achuthankutty 《Continental Shelf Research》2010
The seasonal ecological response of microzooplankton in the southeastern Arabian Sea is presented. During the spring intermonsoon period, stratification and depletion of nitrate in the surface waters (nitracline was at 60 m depth) cause low integrated chlorophyll a (av. 19±11.3 mg m−2) and primary production (av. 164±91 mgC m−2 d−1). On the other hand, nutrient enrichment associated with coastal upwelling and river influx during the onset and peak summer monsoon resulted in high integrated chlorophyll a (av. 21±6 mg m−2 and av. 29±21 mg m−2, respectively) and primary production (av. 255±94 mgC m−2 d−1 and av. 335±278 mgC m−2 d−1, respectively). During all three periods, diazotropic cyanobacterium Trichodesmium erythraeum dominated in the nutrient depleted surface waters. A general increase in abundance of larger diatoms was evident in the surface waters of the inshore region during monsoon periods. The microzooplankton abundance was found to be significantly higher during the spring intermonsoon (av.241±113×103 ind m−2) as compared to onset of summer monsoon (av. 105±89×103 ind m−2) and peak summer monsoon (av.185±175×103 ind m−2). Microzooplankton community during the spring intermonsoon was numerically dominated by ciliates while heterotrophic dinoflagellate was the dominant ones during the monsoon periods. The high abundance of ciliates during the spring intermonsoon could be attributed to the stratified environmental condition prevailed in the study area which favors high abundance of smaller phytoplankton and cyanobacteria, the most preferred food of ciliates. On the other hand, the dominance of heterotrophic dinoflagellates during the monsoon periods could be linked to their ability to graze larger diatoms which were abundant during the monsoon periods. The overall results show low abundance of microzooplankton in the eastern Arabian Sea during the monsoon periods mainly due to a decline in ciliates abundance. This decline during the monsoon periods could be the result of (a) low abundance of smaller phytoplankton and (b) high stock of mesozooplankton predators (av. 245 ml 100 m−3). 相似文献
15.
Surface and upper air synoptic features prevailing at the time of onset of southwest monsoon over Mumbai have been examined
for a period of 50 years from 1947 to 1996. These synoptic situations have been found to fall under three broad categories.
The study shows that on about 66% of the occasions, the onset of monsoon over Mumbai is caused by low pressure area forming
over southeast and east central Arabian Sea as they move northwards, while on 28% of the occasions, the onset is due to the
low pressure systems forming over northwest/head Bay of Bengal and their movement towards northwest/west northwest. Based
on the findings of the study and the climatological aspects, a criterion for declaring onset over Mumbai has been suggested. 相似文献
16.
17.
A literature review on trace metals and organic compounds of anthropogenic origin in the Wider Caribbean Region 总被引：2，自引：2，他引：0
About 30 studies from the published literature were reviewed to determine the pollution status regarding heavy metals and organic compounds of the Wider Caribbean Region (WCR). The literature revealed that most studies were performed in the South and Central American Caribbean Region with sparse reports on the small island states. Collectively, the most frequently analyzed heavy metals were Pb, Cu, Zn, Fe, Cd, Ni, Mn and Cr while DDT and its metabolites were the most frequently reported organic pollutants. The samples which were analyzed vary in terms of sampling schemes, parameters and analytical techniques, as well as differences in data reporting presentation (i.e. dry weight versus wet weight, sediment fraction analyzed, or % lipids). These differences make meaningful comparisons of the available data very difficult. Furthermore, there is limited data available for most of these contaminants from the majority of nations in the WCR. Therefore, any attempt to create a regional scale assessment from contaminants data available in the open literature is limited by the scarcity of available information. 相似文献
18.
Persistence in surface air temperature anomaly (SATA) time series over 1901–2010 observed at four cities: Nagpur, Pune, Mumbai and Delhi of India is examined using rescaled-range and predictability index. A gap of 40 years is observed in predictability maxima, which is linked with the short-range correlations. Seasonal analysis showed unpredictability of SATA during four seasons at Nagpur, during summers at Pune and Mumbai, and during monsoon and post-monsoon at Mumbai and Delhi. Significant change is observed after 1991 at Delhi, Nagpur and Mumbai with a respective increase of 1.7, 2.2 and 3.3 °C in surface air temperature (SAT) during 1901–2010. The spatial and temporal variations in the SAT in four cities are attributed to their geographic and climatic conditions. The results suggest the utility of the rescaled-range analysis and predictability index in exploring the changes in the climatic variables. 相似文献
19.
Understanding the changes in the air pollution of an area due to implementation of control strategies is important as it helps
in making further action plans. Time series analysis provides ways to interpret the effect of any policy changes. In this
study, the applicability of the CUSUM method for change detection in air pollutant concentrations in Delhi is investigated.
The method detects any shift from mean of the process. Delhi has undergone major policy changes during the past few years.
Change of fuel in vehicles to compressed natural gas (CNG) is one amongst them. The data observed at a traffic site in Delhi
for nitrogen dioxide (NO2), carbon monoxide (CO) and particulate matter (with size less than 10 micron-PM10) concentrations is used to carry out the
analysis. Increase in NO2 concentration and decrease in CO concentration levels is observed using CUSUM method. The choice of base period does not
affect much for these two pollutants but for PM10 concentration, however its role is crucial. In order to counter any variability
shifts, the CUSUM method is further modified to account for the change in the variance of the time series. Modified CUSUM
method indicated similar nature of variability in NO2 and PM10, whereas CO variability has decreased significantly after CNG implementation. 相似文献
20.
S.V. Sunilkumar K. Parameswaran K. Rajeev B.V. Krishna Murthy S. Meenu Sanjay K. Mehta Asha Babu 《Journal of Atmospheric and Solar》2010,72(9-10):745-762
Association between semitransparent cirrus (STC) and tropospheric dynamics during the two contrasting seasons (Summer-monsoon and Winter) is studied using lidar and MST radar observations at Gadanki (13.5°N, 79.2°E) along with data from Geo-stationary satellite (KALPANA-1). The tropical tropopause layer (TTL) is found to be very conducive for the formation of STC. For those thicker STCs forming within TTL, the cloud top remains mostly steady with the top of the TTL, while the cloud base varies significantly in accordance with the altitude extent of tropospheric convective outflow. Based on depolarization characteristics of STCs (from lidar) along with regional distribution of tropospheric clouds derived from satellite data, altitude profile of horizontal wind, wind field at 150 hPa and air mass back trajectories, it can be reasonably inferred that, while the multi-layered and highly structured STCs during the monsoon period originate mostly from the deep convections, the sub-visual/ultra thin STCs during winter could mostly be of in situ origin. 相似文献