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Seasonal influence of freshwater discharge on spatio-temporal variations in primary productivity, sea surface temperature, and euphotic zone depth in the northern Bay of Bengal

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Acta Oceanologica Sinica 2024年第6期43卷 1-14页

作者： Hafez Ahmad Felix Jose Md.Simul Bhuyan Md.Nazrul Islam padmanava das. Geosystems Research Institute/Department of Geosciences Mississippi State UniversityStarkville 39759USA Department of Oceanography University of ChittagongChittagong 4331Bangladesh Department of Marine&Earth Sciences Florida Gulf Coast UniversityFort Myers 33965USA Bangladesh Oceanographic Research Institute Cox’s Bazar 4730Bangladesh Faculty of Marine Sciences&Fisheries Institute of Marine SciencesUniversity of ChittagongChittagong 4331Bangladesh Department of Geography and Environment Jahangirnagar UniversityDhaka 1342Bangladesh Department of Geosciences Mississippi State UniversityStarkville 39759USA

Ocean productivity is the foundation of marine food web,which continuously removes atmospheric carbon dioxide and supports life at sea and on ***-temporal variability of net primary productivity(NPP),sea surface temperature(SST),sea surface salinity(SSS),mixed layer depth(MLD),and euphotic zone depth(EZD) in the northern B ay of Bengal(BoB) during three monsoon seasons were examined in this study based on remote sensing data for the period 2005 to *** compare the NPP distribution between the coastal zones and open BoB,the study area was divided into five zones(Z1-Z5).Results suggest that most productive zones Z2 and Zl are located at the head bay area and are directly influenced by freshwater discharge together with riverine sediment and nutrient *** Z1-Z5,the NPP ranges from 5 315.38 mg/(m~2·d) to 346.7 mg/(m~2·d)(carbon,since then the same).The highest monthly average NPP of 5 315.38 mg/(m~2·d) in February and 5 039.36 mg/(m~2·d) in June were observed from Z2,while the lowest monthly average of 346.72 mg/(m~2·d) was observed in March from Z4,which is an oceanic *** values vary from 6-154 m for the study area,and it has an inverse correlation with NPP *** is deeper during the summer season and shallower during the wintertime,with a corresponding increase in *** the year,monthly SST shows slight fluctuation for the entire study area,and statistical analysis shows a significant correlation among NPP,and EZD,overall positive between NPP and MLD,whereas no significant correlation among SSS,and SST for the northern ***-term trends in SST and productivity were significantly po sitive in head bay zones but negatively productive in the open *** findings in this study on the distribution of NPP,SST,SSS,MLD,and EZD and their seasonal variability in five different zones of BoB can be used to further improve the management of marine resources and overall environmental condition in response to climate change

关键词： chlorophyll a sea surface temperature euphotic zone depth primary productivity Ganges-Brahmaputra ocean color Bay of Bengal monsoon

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Effect of photo-biodegradation and biodegradation on the biogeochemical cycling of dissolved organic matter across diverse surface water bodies

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Journal of Environmental Sciences 2019年第3期31卷 130-147页

作者： M.S.Sankar padmanava das. Shatrughan Singh YueHan Lu ANDrew E.Mercer Shuo Chen Department of Geosciences Mississippi State University Department of Geological Sciences University of Alabama Academy for Advanced Interdisciplinary Studies Southern University of Science and Technology

The objective of this research was to quantify the temporal variation of dissolved organic matter(DOM) in five distinct waterbodies in watersheds with diverse types of land use and land cover in the presence and absence of sunlight. The water bodies were an agricultural pond, a lake in a forested watershed, a man-made reservoir, an estuary, and a bay. Two sets of samples were prepared by dispensing unfiltered samples into filtered samples in 1:10 ratio(V/V). The first set was exposed to sunlight(10 hr per day for 30 days) for examining the combined effect of photo-biodegradation, while the second set was stored in dark for examining biodegradation alone. Spectroscopic measurements in tandem with multivariate statistics were used to interpret DOM lability and composition. The results suggest that the agricultural pond behaved differently compared to other study locations during degradation experiments due to the presence of higher amount of microbial humic-like and protein-like components derived from microbial/anthropogenic sources. For all samples, a larger decrease in dissolved organic carbon(DOC) concentration(10.12% ±9.81% for photo-biodegradation and 6.65% ± 2.83% for biodegradation) and rapid transformation of DOM components(i.e., terrestrial humic-like components into microbial humic and protein-like components) were observed during photo-biodegradation *** suggest that sunlight facilitated DOM biodegradation, resulting in simpler recalcitrant molecules regardless of original composition. Overall, it was found that combined effects of light and bacteria are more efficient than bacterial effects alone in remineralizing and altering DOM, which highlights the crucial importance of sunlight in transforming aquatic DOM.

关键词： Photo-biodegradation Biodegradation Dissolved organic matter Land use and land cover Half-life EEM-PARAFAC

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Land Use/Land Cover Analysis Based on Various Comprehensive Geospatial Data Sets: A Case Study from Tirupati Area, South India

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Advances in Remote Sensing 2016年第2期5卷 73-82页

作者： Nagaraju Arveti Balaji Etikala padmanava das. Department of Geology Sri Venkateswara University Tirupati India Department of Geosciences Mississippi State University Mississippi State MS USA

Land use/land cover (LULC) information is essential for the selection, planning and implementation of management strategies to meet the increasing demands for basic human needs and welfare of the ever growing population. This paper illustrates the status of land use/land cover in the Tirupati area of Andhra Pradesh state using an integrated approach of remote sensing and Geographic Information System (GIS). The National Land use/Land cover classification developed by National Remote Sensing Centre (NRSC) and Indian Space Research Organisation (ISRO) divides the land in the study area into five Level I classes, 11 Level II classes, and fifteen Level III classes. From this three-level hierarchic based classification, it was found that the Forest is the major LULC category in the Tirupati area covering 227.46 km2 (58.55%), followed by Agricultural land, Wastelands, Built-up land and water bodies contributing to 70.36 km2 (18.11%), 43.92 km2 (11.31%), 32.71 km2 (8.42%) and 14.03 km2 (3.61%) respectively of the total geographical area. This study also reviewed the characteristics of urban sprawl and their impacts on quality of life, the evident driving forces and its impact on development activities. The study concludes that in Tirupati area forest land contributed the highest land cover (58.55%), while the lowest was contributed by water bodies (3.61%) and shows a significant impact of urbanization on the ecosystem.

关键词： Remote Sensing GIS Landuse/Land Cover Tirupati

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Assessing Net Primary Production in Montane Wetlands from Proximal, Airborne, and Satellite Remote Sensing

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Advances in Remote Sensing 2016年第2期5卷 118-130页

作者： Michael Maguigan John Rodgers padmanava das. Qingmin Meng National Strategic Planning and Analysis Research Center Mississippi State University Starkville MS USA Department of Geosciences Mississippi State University Mississippi State MS USA

In this study, several vegetation indices were examined in order to determine the most sensitive vegetation index for monitoring southern Appalachian wetlands. Three levels of platforms (in situ, airborne, and satellite) for sensors were also examined in conjunction with vegetation indices. Net primary production (NPP) data were gathered to use as a measure of wetland function. Along with the in situ radiometers, National Agricultural Imagery Program (NAIP) data and Landsat 8 Operational Land Imager (OLI) data were gathered in order to calculate vegetation indices at three platforms. At the in situ level, VARI700 was the most sensitive vegetation index in terms of NPP (r2 = 0.65, p 2 = 0.35, p = 0.11). At the satellite level, the DVI appeared to have a positive relationship with NPP. For most indices there was a drop in the coefficient of determination with NPP when the platform altitude increased, with the exception of NDVI when increasing altitude from in situ to airborne. This study provides a novel methodology comparing reflectance and vegetation indices at three platform levels.

关键词： Net Primary Production Montane Wetland In Situ Airborne Satellite

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Integrated Approach Using Remote Sensing and GIS for Assessment of Groundwater Quality and Hydrogeomorphology in Certain Parts of Tummalapalle Area, Cuddapah District, Andhra Pradesh, South India

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Advances in Remote Sensing 2016年第2期5卷 83-92页

作者： Arveti Nagaraju Yenamala Sreedhar Arveti Thejaswi padmanava das. Department of Geology Sri Venkateswara University Tirupati India Environmental Sciences School of Distance Education Kakatiya University Warangal India Mississippi State University Mississippi State MS USA

The present work deals with the assessment of groundwater potential zones and their suitability for drinking in the severely drought affected villages of Vemula mandal of Cuddapah District, Andhra Pradesh. This study is based on remote sensing and GIS approach. In this approach the IRS P6 LISS III Data (23.5 m Spatial Resolution) with Path: 100;Row: 063 of Indian Remote Sensing Satellite, Resourcesat IRS-P6 LISS-III has been utilized to analyse the onscreen interpretation and delineated different geomorphological units, lithological formations and geological structures. By integrating the above said parameters the hydrogeomorphological map is prepared on 1:50,000 scale. The study area is characteristically occupied by the Papaghni and Chitravati group of rocks. In the present study, the lithological formations on the basis of their genesis have been classified as fluvial, denudational and structural. Majority of lineaments are trending in NE-SW and NW-SE directions. The fluvial landforms namely valley fill moderate and valley have good groundwater prospects while shallow weathered buried pediplain has moderate to poor groundwater prospects. The chemical quality parameters of groundwater samples have indicated that the water samples are found to be suitable for drinking, agricultural, and industrial purposes.

关键词： Remote Sensing GIS Groundwater Hydrogeomorphology Water Quality

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