2014年夏季长江口有色溶解有机物(CDOM)的分布、光学特性及其来源探究   总被引：3，自引：0，他引：3  

李奕洁  宋贵生  胡素征  XIE Hui-Xiang 《海洋与湖沼》2015,46(3):670-678

通过测定有色溶解有机物(CDOM)的吸收光谱、荧光光谱、溶解有机碳(DOC)浓度,探究了2014年夏季长江口CDOM的来源及河口混合行为。结合吸收系数a(355)、光谱斜率S275-295、比紫外吸光度SUVA254与盐度的关系,结果表明南港水道受黄浦江输入影响显著,北港水道由长江径流控制呈保守性混合行为,二者CDOM的物质结构性质较为相似。DOC的浓度可通过a(275)与a(295)模拟估算:ln[DOC]=4.94–0.87ln[a(275)]+0.90ln[a(295)],a(275)8.0 m–1;ln[DOC]=4.77–6.79ln[a(275)]+8.05ln[a(295)],a(275)≥8.0 m–1。模拟结果表明,在长江口及邻近海域,CDOM对DOC具有示踪意义。利用三维荧光光谱-平行因子分析(EEMs-PARAFAC)技术,可得到夏季长江口FDOM含有3个类腐殖质组分(C2,C4和C5)和3个类蛋白质组分(C1,C3和C6)。类腐殖质组分具有相似的来源及地球化学行为,且与a(355)及盐度存在显著相关性;类蛋白质组分则与a(355)及盐度之间无显著相关性,揭示其与区域内微生物的活动有关。  相似文献   

伶仃洋河口横向环流   总被引：6，自引：4，他引：2  

易侃  龚文平 《海洋学报》2015,37(3):1-14

横向环流存在于大多数河口中,在河口的动量平衡和物质输运过程中起着重要的作用,其形成的机制众多。本文利用三维水动力模型EFDC(Environmental Fluid Dynamics Code),结合1989年和2002年的实测数据对伶仃洋河口进行研究,得到了伶仃洋河口在洪季和枯季时期不同的水动力和盐度分布结构。在文中选取了具有代表性的两个断面,针对洪枯季、大小潮以及涨落潮等不同时期的横向流结构和盐度剖面分布特点进行比较和分析。结果显示,受局地的径、潮流条件和地形约束影响,横向环流结构并不能充分形成,在不同的区域表现出截然不同的结构特点。伶仃洋河口横向环流主要是在径、潮流与地形三者之间的相互作用下形成的,不同的区域的形成机制存在差异。综合分析后,本文认为伶仃洋河口的横向环流在该区域的动力过程中相对较为次要。  相似文献   

现代黄河三角洲沉积物临界剪切应力研究   总被引：2，自引：1，他引：1  

郑杰文  贾永刚  刘晓磊  刘保华  付腾飞  张丽萍 《海洋学报》2015,37(3):86-98

为研究现代黄河三角洲沉积物临界剪切应力空间分布特征及其影响要素,本文在现代黄河三角洲不同沉积区域,垂直海岸线布设测线,采用黏结力仪进行沉积物临界剪切应力测试,并在相应测点开展沉积物物理力学性质与粒度成分测量工作。研究结果表明高潮滩沉积物临界剪切应力最高,在1.1~4.02Pa之间,沉积物不易发生侵蚀,含水量低、干容重大、黏粒与粉粒含量高、平均粒径小、不排水剪切强度大是高潮滩沉积物临界剪切应力偏高的重要因素;中潮滩沉积物受生物活动影响显著,临界剪切应力在0.10~1.90Pa之间,生物活动扰动、生物排泄及遗体遗迹的程度与数量是造成不同区域测试差异的重要原因;低潮滩沉积物临界剪切应力很低,在0.08~0.80Pa之间,沉积物极易发生侵蚀,含水量高、干容重偏低、砂砾含量高、平均粒径大、不排水剪切强度小是其典型的沉积物物理力学性质,也是造成低潮滩沉积物临界剪切应力普遍低于高潮滩的重要原因;现代黄河三角洲沉积物临界剪切应力区域特征表现为北部沉积物临界剪切应力水平最低,在0.11~0.4Pa之间,东部最高,在2.8~4.55Pa之间,南部与东北部居中,分别在0.63~0.84Pa与0.83~2.99Pa之间,东北部空间非均匀性分布显著,粒度组分的分异是导致沉积物临界剪切应力区域差异显著的重要因素,黏粒含量高的沉积区域沉积物临界剪切应力普遍高于砂砾含量高的沉积区;与世界其他大型河口三角洲相比,现代黄河三角洲沉积物临界剪切应力水平偏低但非均匀程度较高。  相似文献   

基于“资源三号”卫星的黄河口湿地景观格局及其空间尺度效应分析   总被引：1，自引：0，他引：1  

肖艳芳  张杰  马毅  王建步 《海洋科学》2015,39(2):35-42

为了在更精细尺度上分析黄河口湿地的景观格局特征,作者基于2012年的国产高分辨率"资源三号"卫星遥感影像,选取斑块类型面积(CA)、斑块个数(NP)、平均斑块面积(AREA_MN)、边缘密度(ED)、平均周长面积比(PARA_MN)、散布与并列指数(IJI)、香农多样性指数(SHDI)和香农均匀度指数(SHEI)8种常用的景观指数,表征景观类型的面积与结构特征、形状特征、聚集特征和景观多样性特征,开展了黄河口湿地的景观格局现状分析,以及空间尺度对黄河口湿地景观格局分析的影响。结果表明:黄河口湿地以裸滩和自然植被等自然景观为主,人工景观所占比重较小,但研究区内油井散布且数量众多,道路修建所导致的景观破碎化已较为明显;总体上,研究区的景观特征具有较强的尺度依赖性,其中表征面积和结构特征的斑块个数、边缘密度、平均斑块面积随着空间尺度的增大有明显的变化,斑块面积则相对稳定,形状特征表现出对空间尺度较强的依赖性,聚集特征随空间尺度的变化不规律,景观多样性特征随空间尺度的变化不明显;不同景观类型的景观特征随空间尺度的变化有较大差异,斑块为条状或斑块边界不规则的景观类型对空间尺度的依赖性更为显著。  相似文献   

Evaluating sustainability of community endeavours in an Indian floodplain wetland using multi‐criteria decision analysis          下载免费PDF全文

Debajit Datta  Proshanta Kumar Ghosh 《Singapore journal of tropical geography》2015,36(1):38-56

The floodplain wetlands of Ganga‐Ichamati interfluves in India have become severely degraded due to incessant, unsustainable utilization practices and lack of community awareness. In spite of the wetlands being the prime source of livelihood for millions, no comprehensive management strategy to accommodate the diverse aspirations and priorities of different users has been implemented for the wetlands to date. In this paper, the authors applied a framework of criteria and indicators to evaluate the status of sustainability achieved by community endeavours in one such wetland. The priorities, consumption patterns and contributions towards wetland conservation of major user groups functioning in that area were assessed by the framework developed through participatory multi‐criteria decision analysis. Results show the deteriorating status of the wetland at present regarding biodiversity conservation and livelihood generation. Fishing activities were identified as the dominant utilization option here followed by agriculture. The paper further explored the preferred alternative utilization strategies for achieving sustainability. Effectiveness of the developed framework in evaluating the extent of sustainability achieved in community endeavours was also highlighted in this context.  相似文献   

广东省自然资源调查监测分类标准体系研究     

杨娜娜  张新长  朱紫阳  淳锦  金诗程 《测绘通报》2021,(9):145-150

自然资源分类是自然资源管理和国土空间规划的基础,是开展调查监测工作的前提,应遵循山水林田湖草是一个生命共同体的理念。本文首先综合分析了现有自然资源分类标准的现状和面临的问题,然后结合广东省特色,对其自然资源调查监测分类标准的总体思路、分类原则、体制机制及具体分类建议等进行了深入探讨,着力解决现有自然资源分类中存在的概念不一、内容有交叉、指标相矛盾等问题,以期为正在开展的广东省自然资源调查监测试点工作提供思路,同时为国家自然资源分类标准的制定提供一定启发。  相似文献   

Groundwater flushing of solutes at wetland and hillslope positions during storm events in a small glaciated catchment in western New York,USA     

Shreeram Inamdar  Julia Rupp  Myron Mitchell 《水文研究》2009,23(13):1912-1926

While the role of groundwater in flushing of solutes has long been recognized, few studies have explicitly studied the within‐event changes in groundwater chemistry. We compared the changes in groundwater chemistry during storm events for a wetland and hillslope position in a small (1·5 ha) glaciated, forested catchment in western New York. Flushing responses for dissolved organic carbon (DOC) and nitrogen (DON), nitrate (NO₃) and sulfate (SO₄) in wetland and hillslope groundwaters were also compared against the corresponding responses in stream water. Eight storm events with varying intensity, amount, and antecedent moisture conditions were evaluated. Solute flushing patterns for wetland and hillslope groundwaters differed dramatically. While DOC concentrations in wetland groundwater followed a dilution trend, corresponding values for hillslope groundwater showed a slight increase. Concentrations for NO₃ in wetland groundwater were below detection limits, but hillslope groundwaters displayed high NO₃ concentrations with a pronounced increase during storm events. Flushing responses at all positions were also influenced by the size of the event and the time between events. We attributed the differences in flushing to the differences in hydrologic flow paths and biogeochemical conditions. Flushing of the wetland did appear to influence storm‐event stream chemistry but the same could not be said for hillslope groundwaters. This suggests that while a variety of flushing responses may be observed in a catchment, only a subset of these responses affect the discharge chemistry at the catchment outlet. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Recovery of added ¹⁵N-labelled ammonium-N from Louisiana Gulf Coast estuarine sediment     

C.J. Smith  R.D. DeLaune 《Estuarine, Coastal and Shelf Science》1985,21(2):225-233

The loss of added ¹⁵N-labelled NH₄⁺ from bottom sediment was studied in situ in a shallow saline Louisiana Gulf Coast lake. ¹⁵N-labelled NH₄⁺ was uniformly mixed with sediment at the level of 35 μg N g^?1 dry sediment for 24 h before being weighed into polyethylene containers. The ¹⁵N-enriched sediment was incubated on the lake bottom for periods up to 337 days. At intervals, triplicate samples were taken and analyzed for inorganic NH₄⁺, organic N, and denitrification rates. Concentrations of NH₄⁺ in the ¹⁵NH₄⁺ enriched sediment samples were at levels similar to those measured in vertical intact cores removed from the lake at each sampling date. The initial and final isotopic compositions of NH₄⁺ in the incubated sediments were 44.26 and 0.521 atom % ¹⁵N excess, respectively. ¹⁵N enrichment in the organic N fraction increased rapidly during the first 15 days of incubation and then increased slowly from 15 to 123 days. Denitrification, estimated by the acetylene blockage technique, ranged from 0.994 to 0.079 ng N g^?1 dry sediment per hour. The mean denitrification rate for the 337-day period was 0.28 ng N g^?1 h^?1. There was no statistical difference in the recovery of ¹⁵N between 15 and 337 days of incubation. When the added ¹⁵N became incorporated into the organic N pool, little or no further ¹⁵N was lost.  相似文献   

Numerical Simulation of phytoplankton productivity in partially mixed estuaries     

David H. Peterson  John F. Festa 《Estuarine, Coastal and Shelf Science》1984,19(5):563-589

A two-dimensional steady-state model of light-driven phytoplankton productivity and biomass in partially mixed estuaries has been developed. Effects of variations in river flow, suspended sediment concentration, phytoplankton sinking, self-shading and growth rates on distributions of phytoplankton biomass and productivity are investigated.Numerical simulation experiments show that biomass and productivity are particularly sensitive to variations in suspended sediment concentrations typical of natural river sources and to variations in loss rates assumed to be realistic but poorly known for real systems. Changes in the loss rate term within the range of empirical error (such as from dark bottle incubation experiments) cause phytoplankton biomass to change by a factor of two. In estuaries with adequate light penetration in the water column, it could be an advantage for phytoplankton to sink. Species that sink increase their concentration and form a phytoplankton maximum in a way similar to the formation of the estuarine turbidity maximum. When attenuation is severe, however, sinking species have more difficulty in maintaining their population.  相似文献   

The tidal exchange of Callianassa californiensis (Crustacea,Decapoda) larvae between the ocean and the Salmon River estuary,Oregon     

Gary E. Johnson  J.J. Gonor 《Estuarine, Coastal and Shelf Science》1982,14(5):501-516

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