Sources and implications of particulate organic matter from a small tropical river—Zuari River,India     

Fernandes Dearlyn  Wu Ying  Shirodkar Prabhaker Vasant  Pradhan Umesh Kumar  Zhang Jing 《海洋学报(英文版)》2020,39(4):18-32

Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and its implications to small tropical rivers.Thus,changes in temporal and regional settings are more likely to affect the natural biogeochemical cycles of small tropical rivers.  相似文献   

长江口横沙浅滩冲淤演变特征分析     

冯祎琳  张行南  徐双全  李万春  方园皓  刘羽婷 《海洋工程》2024,(2):192-206

横沙浅滩作为长江口前沿滩涂湿地的重要组成部分,是“上海市长远发展战略空间”的预留区,掌握其滩涂演变规律对该地区的资源保护及合理开发具有重要的参考价值。基于2005—2021年长江口实测水下地形数据,定量分析研究了横沙浅滩地形演变过程,及其对周边河口工程建设和水沙条件变化的响应。研究结果表明：横沙浅滩近年来整体呈现“长高长不大”的演化格局,中、东部区域明显淤高,沙体向海延伸与河口泥沙滞流点的向外海移动关系紧密。流域输沙量锐减是横沙浅滩滞涨的重要原因,滩面北沿和深水航道北侧冲刷明显,造成N23堤顶冲坑的扩大与滩面潮水沟的贯通。深水航道工程与横沙东滩促淤圈围工程的建设是潮水沟与N23堤顶冲坑迅速发育的主要原因。  相似文献   

基于DEM及高分影像的河口流域信息快速提取     

晏王波  朱晨曦  戴煜暄 《地理空间信息》2019,17(6):93-97,I0004

入海河口是陆地和海洋之间的过渡区域,由于入海河口受海陆交互作用,受水沙过程、水动力过程影响明显,河口滩面地形变化频繁,空间数据特别是滩面地形数据获取较为困难,难以开展滩面水文过程分析。本研究首先提出一个总体框架用于河口流域提取,其核心是通过ModelBuilder构建链式河口流域地理处理过程,基于DEM进行一站式滩面信息处理,实现河口流域信息的快速提取。对于一些侵蚀性河口或者人工干预比较多的河口,研究辅以高分辨率影像非监督分类方法,进行河口流域信息的快速提取。研究结果表明,本研究在河口流域提取方面有良好的实用性,可方便地进行多种情境分析与比较,减少中间数据处理过程,进而有效地应用辅助规划决策。  相似文献   

Tracking stormwater discharge plumes and water quality of the Tijuana River with multispectral aerial imagery     

Jan Svejkovsky  Nikolay P. Nezlin  Neomi M. Mustain  Jamie B. Kum 《Estuarine, Coastal and Shelf Science》2010

Spatial–temporal characteristics and environmental factors regulating the behavior of stormwater runoff from the Tijuana River in southern California were analyzed utilizing very high resolution aerial imagery, and time-coincident environmental and bacterial sampling data. Thirty nine multispectral aerial images with 2.1-m spatial resolution were collected after major rainstorms during 2003–2008. Utilizing differences in color reflectance characteristics, the ocean surface was classified into non-plume waters and three components of the runoff plume reflecting differences in age and suspended sediment concentrations. Tijuana River discharge rate was the primary factor regulating the size of the freshest plume component and its shorelong extensions to the north and south. Wave direction was found to affect the shorelong distribution of the shoreline-connected fresh plume components much more strongly than wind direction. Wave-driven sediment resuspension also significantly contributed to the size of the oldest plume component. Surf zone bacterial samples collected near the time of each image acquisition were used to evaluate the contamination characteristics of each plume component. The bacterial contamination of the freshest plume waters was very high (100% of surf zone samples exceeded California standards), but the oldest plume areas were heterogeneous, including both polluted and clean waters. The aerial imagery archive allowed study of river runoff characteristics on a plume component level, not previously done with coarser satellite images. Our findings suggest that high resolution imaging can quickly identify the spatial extents of the most polluted runoff but cannot be relied upon to always identify the entire polluted area. Our results also indicate that wave-driven transport is important in distributing the most contaminated plume areas along the shoreline.  相似文献   

基于时序InSAR的珠江口大面积地面沉降监测          下载免费PDF全文

高辉  罗孝文  吴自银  阳凡林 《海洋学研究》2020,38(2):81-87

珠江口是我国沿海地面沉降灾害较严重地区之一,长期地面沉降威胁着人类生产生活的质量和安全。针对传统InSAR在河口等沿海地区空间采样率不足的现状,采用基于KS检验和特征分解的DS-InSAR时序分析方法,获得了珠江口地区2015—2018年间地面沉降监测数据,并分析了几处沉降严重地区的沉降特征和原因。采用的DS-InSAR方法在沥青路面、裸土等非城市区域提取了较大密度的高相干点,提高了时序InSAR形变反演的精度。研究表明,研究区域总体呈地面沉降趋势且分布不均匀,珠江三角洲西北部和东南部为主要沉降区,最大沉降速率可达25 mm/a,珠江口西岸沉降相对东岸分布更广,沉降量更大。  相似文献   

SeaBeam 3030多波束系统在南海冷泉调查中的应用     

张建兴  宋永东  杜增丰  马小川  栾振东  张鑫  阎军 《海洋科学》2022,46(1):154-162

在冷泉调查研究中,多波束系统因其快速高效、成本较低的特点被广泛应用.本文靶定南海北部陆坡琼东南盆地冷泉发育区,介绍了SeaBeam 3030多波束系统在冷泉发育区中的调查应用实例.通过分析多波束水深数据和水体数据,确定了调查区海底地形地貌以及水体羽状流特征,同时对该冷泉区开展综合调查的必要性进行了初步分析.研究表明,调...  相似文献