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1.
Optical properties of estuarine dissolved organic matter isolated using cross-flow ultrafiltration 总被引：1，自引：0，他引：1
Dissolved organic matter(DOM) from freshwater, mid-salinity, and seawater endmember samples in the Jiulong River Estuary, China were fractionated using cross-flow ultrafiltration with a 10-kDa membrane. The colloidal organic matter(COM; 10 kDa–0.22 μm) retentate, low molecular weight(LMW) DOM(10 kDa) permeate, and bulk samples were analyzed using absorption spectroscopy and three-dimensional fluorescence excitation-emission-matrix spectroscopy. The UV-visible spectra of COM were very similar to those obtained for permeate and bulk samples, decreasing monotonically with increasing wavelength. Most of the chromophoric DOM(CDOM, expressed as the absorption coefficient a355) occurred in the LMW fraction, while the percentage of CDOM in the colloidal fraction was substantially higher in the freshwater endmember(13.4% of the total) than in the seawater endmember(6.8%). The bulk CDOM showed a conservative mixing behavior in the estuary, while there was removal of the COM fraction and a concurrent addition of the permeate fraction in the mid-salinity sample, implying that part of the colloidal CDOM was transformed into LMW CDOM. Two humic-like components(C1: 250, 325/402 nm; and C2: 265, 360/458 nm) and one protein-like component(C3: 275/334 nm) were identified using parallel factor analysis. The contributions of the C1, C2, and C3 components of the COM fraction to the bulk sample were 2.5%–8.7%, 4.8%–12.6%, and 7.4%–14.7%, respectively, revealing that fluorescent DOM occurred mainly in the LMW fraction in the Jiulong River Estuary. The C1 and C2 components in the retentate and permeate samples showed conservative mixing behavior, but the intensity ratio of C2/C1 was higher in the retentate than in the permeate fractions for all salinity samples, showing that the humic component was more enriched in the COM than the fulvic component. The intensity ratio of C3/(C1+C2) was much higher in the retentate than in the permeate fraction for mid-salinity and seawater samples, revealing that the protein-like component was relatively more enriched in COM than the humic-like component. The contribution of the protein-like component(C3) to the total fluorescence in the retentate increased from 14% in the freshwater endmember to 72% for the seawater endmember samples, clearly indicating the variation of dominance by the humic-like component compared to the protein-like component during the estuarine mixing process of COM. 相似文献
2.
Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China 总被引：1，自引：1，他引：0
L&#; E ZHANG Lei CHEN Min QIU Yusheng XING N YANG Weifeng LI Yanping HUANG Yipu 《海洋学报(英文版)》2008,27(1):29-41
Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （ 〈 0.4 μm） exis- ted in the low molecular mass fraction （ 〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （ 〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the partic 相似文献
3.
Distribution of organic carbon in sediments and its influences on adjacent sea area in the turbidity maximum of Changjiang Estuary in China 总被引：2，自引：0，他引：2
Distributions and sources of total organic carbon （TOC）in seabed sediments and their implications for hydrodynamics are analyzed, in the turbidity maximum of the Changjiang Estuary. Ecology ecoenvironmental effects of estuary water on the continuously increasing terrigenous organic carbon from the Changjiang River are also explored through variations of organic carbon content and water quality indicators. Results show that, hydrodynamics exert important influences on distributions of organic carbon in the tur- bidity maximum of Changjiang Estuary. For their redistribution effect of terrigenous organic carbon within the moving layer in the whole region, variations from land to sea are not indicated by surficial and vertical average values of TOC and total nitrogen （TN） contents in core sediment, as well as organic stable carbon isotopes in surface sediments. However, on the long-time scale, the trend of terrigenous organic carbon decreasing from land to sea is still displayed by variations of stable carbon isotopic average values becoming heavier from land to sea. Previous studies have shown that high content of Chl a cannot appear in the Changjiang Estuary in despite of adequate nourishment supply, because photosynthesis of phytoplankton is constrained by high suspended sediment concentration（SSC）. However, an area with a high content of Chl a occurs, which may be caused by resuspended benthic algae with bottom fine grain-size sediments. Tremendous pressures are imposed on the environment of Changjiang Estuary, because of uhrophication trends and special hydrodynamics. Phytoplankton bloom area tends to extend from the outer sea to the mouth of Changjiang River. 相似文献
4.
王正方 《海洋学报(英文版)》1986,5(3):393-399
The paper deals with the distribution of suspended particulated materials (SPM) in the Changjiang Estuary, the relation of salinity to particulated organic carbon and particulated organic nitrogen, and behaviour of SPM in mixing river-sea water. At the same time, the article shows that the SPM in Changjiang River emptying into the sea contains a large amount of organic matter. The relative concentrations of suspended particulate organic matter and living organic matter gradually increase seaward. In the estuarine environment, there is a linear relationship between log SPM and C/N ratio during the mixing of fresh water with seawater. 相似文献
5.
The bottom sediment samples were gathered during island investigation in 1994 and in the period of carrying out the natural science fund project of Fujian in 1999.The composition,distribution and assemblage characteristics of heavy minerals which granularity distributes from 0.063 to 0.125mm in the sediment from Jiulong River estuary are studied in the paper.The results show that there are 49kinds of heavy minerals and the average content of them is 9.38%.The dominant and characteristic minerals are magnetite.hematite,epidote,ilmentite,limonite,homblende,zircon,andalusite,biotite and so on,4mineral assemblage zones(Ⅰ.The watercourse gateway of Jiulong River mineral zone,Ⅱ.The northern estuary of Jiulong River mineral zone,Ⅲ.The southern estuary mineral zone,Ⅳ.The eastern estuary of Jiulong River mineral zone),can be divided based on the heavy mineral contents and the sdistribution characteristics,which not only relates to the matter sources but also is controlled by hydrodynamic condition and the sedimentary environment in the Jiulong River estuary. 相似文献
6.
Variation of reactivity of particulate and sedimentary organic matter along the Zhujiang River Estuary 总被引：3，自引：0，他引：3
To investigate organic matter source and reactivity in the Zhujiang River (Pearl River)Estuary and its adjacent areas, particulate organic carbon (POC), particulate hydrolysable amino acids (PHAA), and Chl a during two cruises in July 1999 and July 2000 were measured. The highest POC and PHAA concentration was observed in the waters with maximum Chl a. The spectra distribution,relative content (dry weight in milligram per gram), PHAA-C% POC and other indicators such as the ratios of amino acids vs. amino sugars (AA/AS) and glucosamine vs. galactosamine (Glum/Gal) suggested that particulate amino acids in the water column and sediments in the Zhujiang River Estuary were mainly derived from biogenic processes rather than transported from terrestrial erosion. In inner estuary where high turbidity was often observable, organic matter was mainly contributed by re-suspension of bottom sediments with revealed zooplankton, microbial reworked characteristics, which suggest that these organic matters were relatively “old“. In the estuarine brackish region, organic matter in water column is mainly contributed by relatively fresh, easily degradable phytoplankton derived organic matter.During physical - biological processes within the eastuary, organic matter derived from phytoplankton was subjected to alteration by zooplankton grazing and bacterial reworking. 相似文献
7.
One of the key concerns in estuarine and coastal environments is eutrophication, which is known to be closely connected to nutrient enrichment. To control and improve surface water quality, nutrient criteria are recommended in order to provide reference conditions for the environment. However, the current datasets of nutrient criteria in China are either designed for surface water or sea water, and as such these are not suitable for assessing estuarine water quality, especially given the unique ecosystem and dynamic properties of estuaries. To address this issue in current estuarine water management, nutrient criteria have been developed for a local estuary in the southeast of China. Segmentation of the Jiulong River Estuary, China was firstly analysed through field investigations carried out during 2013–2014, which resulted in the delineation of three segments characterized by their distinct properties in relation to salinity, hydrology, ecosystems, etc. Historical records from 1997 to 2014 were then analysed using statistical modelling to develop candidate nutrient criteria for the estuary.This stage of the analysis was undertaken in combination with the study of nutrient status records from the 1980s,which were used to establish a baseline reference condition. The recommended criteria values of dissolved inorganic nitrogen(DIN) in Segments Ⅰ, Ⅱ and Ⅲ of the Jiulong River Estuary are 64, 21 and 14 μmol/L,respectively, and the corresponding values for soluble reactive phosphorus(SRP) are 0.89, 0.76 and 0.89 μmol/L,respectively. It should be emphasised that these values are site-dependent, and that different results may be achieved at other locations depending on the physical and biogeochemical characteristics of an estuary, or even a single site within a catchment. It is hoped that by demonstrating a possible methodological approach and methods of nutrient criteria derivation in the Jiulong River Estuary, the current study will offer researchers some fundamental basis from which to begin to develop more complete nutrient criteria indices for the study of nutrient conditions in other estuaries throughout China. 相似文献
8.
Adsorption kinetics of the interaction between Pt, Pd and Rh(defined here as platinum group elements, PGEs)ions and macromolecular organic compounds(MOCs, 10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter(1 kDa and 3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and 1 kDa cutoff, and between Pd and humic acid.For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient(log_(10)K_d) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter(NDOM), an obvious difference in the change trends of log_(10)K_d and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log_(10)K_d of PGEs in the 1 kDa NDOM fraction were higher and more stable than those in the 3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research. 相似文献
9.
黄河口沉积物微量元素的多元统计分析 总被引：1，自引：0，他引：1
Some microelements totalled ten of sediment samples have been analysed by emission spectrometer. The samples taken from the nearshore area of the Huanghe River and the Lianhe River and the elements analysed are Ni, Co, Cu, Ga, V, Ti, Pb, Zn, Mo, and Mn. Though multivariate analysis by computer, it shows that the effective discriminant elements for the sediments of estuary area of the Huanghe River and Lianhe River are Ti, Zr, Co, V. The Lianhe River Estuary sediments are characterized by higher content of Zr, Co and the Huanghe River Estuary sediments are characterized by higher content of Ti,V. The trend surface analysis shows that the Ni, Ga, Co and Cu have similar tendency of distribution and are closely related with the clayey sediments; Zr and Ti have the similar trend distribution and closely related with coarser grain sediments; the distribution of Mn is in accordance with the area of higher pH. Eh values and is closely related with fine-sandy sediments. 相似文献
10.
夏季渤海西南部及黄河口海域营养盐分布特征 总被引：9，自引：0，他引：9
There are few papers dealing with nutrients distribution in the mixing region of the Huanghe River Estuary, although the Huanghe River is one of the largest rivers in China. We investigated nutrients (nitrate nitrite, phosphate and silicate) at 81 stations in the southwest Bohai Sea and the Huanghe River Estuary in July, 1984. The concentrations of nitrate, nitrite, phosphate and silicate are higher in the estuary and offshore than those in the centre of the Bohai Sea. They are 44.3ug-at/L for nitrate, 0.31ug-at/L for nitrite, 0.36ug-at/L for phosphate and 60.4ug-at/L for silicate. There are negative correlations between nutrients and salinity in this region. The correlation coefficients in surface layer are:γSiO3-si=-0.963(n=81) γPO4-P=-0.829(n=81) γNO3-N=-0.971(n=81) γNO2-N=-0.553(n=81) The correlation coefficients show that, in the surface layer, there are no obvious removal of nutrients during mixing river-water and seawater in the Huanghe River Estuary. 相似文献
11.
利用微滤和超滤技术研究了九龙江河口区表层水中铀及其同位素组成的粒级分布和地球化学行为.结果表明,溶解态(<0.4μm)中低分子量组分(<10 000 u)占主要份额,胶体态(10 000 u~0.4μm)238U所占比例不足1%,且随盐度的增加其所占份额逐渐降低.溶解态、低分子量组分和胶体态238U的比活度与盐度之间存在良好的线性正相关关系,证实它们在九龙江河口区呈现保守行为.在颗粒态(>0.4μm)中,各粒级组分238U所占份额主要受控于相应颗粒物的浓度,在盐度小于20的区域,各粒级颗粒组分238U占颗粒态的份额有如下变化次序:10~53μm>2~10μm>0.4~2μm>大于53μm,而在盐度大于30的近外海站位,该次序发生一些变化:0.4~2μm>10~53μm>2~10μm>大于53μm,最小粒级颗粒组分238U的贡献有所增加,反映了自生铀贡献的加强.九龙江河口区表层水中溶解态(包括低分子量组分和胶体态)的234U/238U)A.R.均大于1,显示出234U过剩的特征,而各粒级颗粒组分中的234U/238U)A.R.则接近于平衡值(1.0).这一现象与陆地岩石风化过程中水体对铀的淋滤释出量及234U的优先浸出有关.对232Th/238U质量比的研究显示,溶解态及其所包括的低分子量组分和胶体态的232Th/238U质量比均小于1,而颗粒态及其所包括的4个粒级组分中的232Th/238U质量比均大于1,反映了向外海输送过程中铀、钍地球化学行为的差异. 相似文献
12.
The spectral absorption properties of chromophoric dissolved organic matter (CDOM) and their distributions in two Chinese estuaries, the Yangtze River Estuary and the Jiulong River Estuary, were studied during August 2003 (wet season) and during different seasons between 2003−2005, respectively. The CDOM concentrations (a355) of fresh end members in the Jiulong River Estuary varied seasonally, while its quality remained relatively stable. However, the a355 of the marine end members exhibited less variability. Application of a conservative mixing model indicated that CDOM behaved conservatively in the Yangtze River Estuary. No photobleaching removal was observed at high salinity region of this estuary. Although CDOM showed conservative behavior for many cruises in the Jiulong River Estuary, there was evidence for removal in the low salinity regions during some cruises. Laboratory mixing experiments and a salt addition experiment suggested that particle sorption of CDOM maybe the possible reason for the removal. These results showed that absorption properties of CDOM can be used as a tool to observe the quantitative and qualitative dynamics of DOM during estuarine mixing. 相似文献
13.
根据2006年丰水期和枯水期对珠江口伶仃洋海域的调查资料,分析了该海域营养盐的现状,发现丰水期NO3-N和SiO3-Si含量呈自口门向外逐渐降低的变化,NO2-N和PO4-P高值区则集中在深圳附近海域,枯水期各项营养盐均呈自口门向外逐渐降低的变化。结合1990年、1998年、2001年3个年份的资料,分析了珠江口邻近海域5项营养盐(SiO3-Si,NO3-N,NO2-N,NH4-N和PO4-P)近20 a来的变化规律,并对其影响因素进行了探讨和分析。结果发现,NO3-N,NO2-N,NH4-N和PO4-P含量呈现显著上升趋势,DIN/DIP呈下降趋势。NO3-N和SiO3-Si含量丰水期显著高于枯水期,NO2-N和PO4-P则相反,径流携带作用是NO3-N和SiO3-Si的主要来源,而径流对NO2-N和PO4-P则起稀释作用。另外农业施肥的影响、围填海造成的海域面积缩小以及网箱养殖业饵料的不合理投放亦是造成珠江口伶仃洋海域DIN,DIP含量上升的因素。 相似文献
14.
The contents of total copper, total dissolved copper, particulate copper, and free ion copper in the Zhujiang River Estuary were investigated in July 2002 and January 2003 respectively, and the spatial distribution trend of these species of copper were compared in two cruises. It was found that, in summer, the total copper content in the Zhujiang River Estuary increased with salinity, while the content office ion copper decreased with salinity. However, in winter, the contents of total copper and free ion copper both decreased with salinity. So, it could be concluded that, copper content and speciation in the Zhujiang River Estuary were regulated by other factors than runoffdiffusion such as upwelling current. In order to prove the spatial trend of rice ion copper content in the Zhujiang River Estuary, the cultivation of Dunaliella tertiolecta in waters obtained from sampling stations with different salinities was carried out, and the copper uptake by algae cells was measured then. It was found that, the cells＇ uptake of copper increased with rice ion copper, not the content of total copper. 相似文献
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16.
The Zhujiang River Estuary is becoming eutrophic due to the impact of anthropogenic activities in the past decades. To understand nutrient dynamics and fluxes to the Lingdingyang water via four outlets(Humen,Jiaomen, Hongqimen and Hengmen), we investigated the spatial distribution and seasonal variation of dissolved nutrients in the Zhujiang River Estuary, based on fourteen cruises conducted from March 2015 to October 2017,covering both wet(April to September) and dry(October to March next year)... 相似文献
17.
建立了珠江口海域三维悬浮泥沙的非饱和输沙数学模型,并与珠江口三维水动力斜压模型耦合,对悬沙迁移分布进行了模拟。模型由4个点的逐时实测含沙量过程进行了验证。各点模拟含沙量与实测含沙量吻合较好,表层分布与同期珠江口悬沙分布遥感图像基本一致.模拟结果表明,珠江口海域悬沙分布分层明显,河口附近水域大多为底层含沙量大于表层,但在盐淡水交汇处出现中层含沙量最小的情况总体上,自各个口门输出的泥沙受沿岸流作用向西南万向输送明显。大多数河口落潮时相对涨潮时含沙量等值线外移,反映珠江口水域悬浮泥沙主要来自河流。 相似文献