长江口淡水端淡、盐水混合表层pCO2的急剧变化及其影响机制   总被引：4，自引：0，他引：4  

李岩  张龙军  苏征  王晓亮  潘建明 《中国海洋大学学报(自然科学版)》2006,36(2):295-298

根据2004年5月长江口淡水端淡、盐水混合初期表层水二氧化碳分压(pCO2)的实测数据,结合水文、化学和生物等要素的同步观测资料,对pCO2的变化及其影响因素进行了研究。研究结果表明:在长江口淡水端盐度0~15的淡、盐水混合初期,表层水pCO2由3 500μatm左右大幅度下降至约1 000μatm。生源要素的补充使生物活动的急剧增加是pCO2以对数形式大幅度降低的主要原因,这一性质显著体现的拐点为(S<0.6,50<浊度<110)这一范围。同时由于生物活动和物理混合作用的分别控制,使得长江口淡水端淡、盐水混合初期表层水碱度与盐度呈二次抛物线关系,拐点处的盐度约为0.6。  相似文献   

High-resolution measurements of chromophoric dissolved organic matter in the Mississippi and Atchafalaya River plume regions   总被引：4，自引：0，他引：4  

Robert F. Chen  G. Bernard Gardner 《Marine Chemistry》2004,89(1-4):103

Chromophoric dissolved organic matter (CDOM) was measured in the spring and summer in the northern Gulf of Mexico with the ECOShuttle, a towed, instrumented, undulating vehicle. A submersible pump mounted on the vehicle supplied continuously flowing, uncontaminated seawater to online instruments in the shipboard laboratory and allowed discrete samples to be taken for further analysis. CDOM in the northern Gulf of Mexico was dominated by freshwater inputs from the Mississippi River through the Birdfoot region and to the west by discharge from the Atchafalaya River. CDOM was more extensively dispersed in the high-flow period in the spring but in both time periods was limited by stratification to the upper 12 m or so. Thin, subsurface CDOM maxima were observed below the plume during the highly stratified summer period but were absent in the spring. However, there was evidence of significant in situ biological production of CDOM in both seasons.The Mississippi River freshwater end member was similar in spring and summer, while the Atchafalaya end member was significantly higher in the spring. In both time periods, the Atchafalaya was significantly higher in CDOM and dissolved organic carbon (DOC) than the Mississippi presumably due to local production and exchange within the coastal wetlands along the lower Atchafalaya which are absent along the lower Mississippi. Nearshore waters may also have higher CDOM due to outwelling from coastal wetlands. High-resolution measurements allow the differentiation of various water masses and are indicative of rapidly varying (days to weeks) source waters. Highly dynamic but conservative mixing between various freshwater and marine end members apparently dominates CDOM distributions in the area with significant in situ biological inputs (bacterial degradation of phytoplankton detritus), evidence of flocculation, and minor photobleaching effects also observed. It is clear that high-resolution measurements and adaptive sampling strategies allow a more detailed examination of the processes that control CDOM distributions in river-dominated systems.  相似文献   

A Stable Carbon Isotope Study of the Food-web in a Freshwater-deprived South African Estuary, with Particular Emphasis on the Ichthyofauna   总被引：1，自引：0，他引：1  

A.W. Paterson  A.K. Whitfield 《Estuarine, Coastal and Shelf Science》1997,45(6):705-715

The importance of macrophytes as food sources for estuarine nekton is unclear. Previous carbon isotope investigations in the macrophyte-dominated, freshwater-deprived Kariega Estuary showed that the bivalveSolen cylindraceusdid not utilize the dominant estuarine macrophytes found within the estuary as a primary food source. This finding prompted questions as to what the nekton of this estuary utilize as primary energy sources. δ¹³C analyses of the principal autochthonous and allochthonous primary carbon sources, as well as the dominant invertebrate and fish species, indicate that there are two main carbon pathways within the Kariega Estuary. The littoral community, which incorporates the majority of crustaceans, gobies, mullet and a sparid, utilizes δ¹³C enriched primary food sources namelySpartina maritima,Zosteracapensis and epiphytes. The channel fauna, which includes the zooplankton, zooplanktivorous and piscivorous fish, utilizes a primary food source depleted in δ¹³C, which is most likely a mixture of phytoplankton, terrestrial plant debris and C₄macrophyte detritus. The C₃saltmarsh macrophytesSarcocornia perennisandChenolea diffusa, as well as benthic microalgae, appear to be less important as primary food sources to the nekton of the Kariega Estuary.  相似文献   

Seasonal Changes in Nitrogen, Free Amino Acids, and C/N Ratio in Mediterranean Seagrasses   总被引：2，自引：0，他引：2  

Helmut  Pirc Bernd  Wollenweber 《Marine Ecology》1988,9(2):167-179

Abstract. Seasonal changes in nitrogen, free amino acids, and carbon were investigated in the three Mediterranean seagrasses Posidonia oceanica, Cymodocea nodosa , and Zostera noltii. Leaves, rhizomes, roots, as well as dead plant material were analysed separately. Highest N-concentrations were obtained in the winter months, regardless of species or plant part. In contrast to the other two species, the N-content in Posidonia was higher in the rhizomes than in the leaves.
In the investigated species, marked differences in the free amino acid (FAA) composition were detected between species: Proline, lacking in Posidonia , was the main component in Cymodocea. In Posidonia , FAA decreased from 320umol g^-1 (dry wt) in leaf sheaths to 1.5 umol g^-1 (dry wt) in the leaf tips. The function of proline as a possible storage and/or stress metabolite is discussed.
High C/N values in dead P. oceanica and C. nodosa rhizomes as well as in P. oceanica wrack seem to be related to considerable resistance to decomposition. Low C/N ratios did not increase in detached C. nodosa and Z. noltii leaves, which began to decompose shortly after detachment from the plants.  相似文献   

Optical properties of low molecular weight and colloidal organic matter: Application of the ultrafiltration permeation model to DOM absorption and fluorescence   总被引：4，自引：1，他引：4  

Claude Belzile  Laodong Guo   《Marine Chemistry》2006,98(2-4):183-196

Cross-flow ultrafiltration (CFF) is often used to obtain separation and concentration of colloids from bulk natural water samples. Application of the ultrafiltration permeation model allows the quantitative determination of the low molecular weight material (LMW, < 1 kDa) and colloids in bulk dissolved organic matter (DOM) from measurements of time series permeate samples obtained from CFF. Detailed analysis of a Yukon River water sample shows that DOM absorption coefficient and fluorescence follow the permeation model and that the complex spectral optical properties of LMW DOM can be reconstructed from CFF data. A combination of measured and modeled data indicates that the LMW contribution to bulk DOM optical properties obtained from CFF can be grossly underestimated by the use of a low concentration factor (CF, the ratio of initial sample volume to retentate volume). Even at a relatively high CF of 19, optical properties of LMW DOM calculated from measurements of the retentate or integrated permeate would underestimate true values by 5–36%. In the Yukon River sample, LMW dissolved organic carbon represented 26% of the bulk concentration, but only 3–14% of the colored DOM was in the LMW fraction while 31–33% of bulk DOM florescence was due to LMW DOM. The contrasting optical properties of LMW and colloidal DOM support the concept that analysis of bulk DOM absorption and fluorescence properties reveals information about DOM molecular weight.  相似文献   

福建近海主要经济渔业生物营养级和有机碳含量研究   总被引：2，自引：0，他引：2  

卢振彬  黄美珍 《台湾海峡》2004,23(2):153-158

本文研究了福建近海52种鱼类、6种虾类、4种蟹类、1种虾蛄和4种头足类的食性和营养级及其有机碳含量。结果表明：营养级以鱼类最高，为2．1～3．7级，平均2．65级；头足类为2．04～2．88级，平均2．60级；蟹类2．38～2．73级，平均2．58级；虾类最低，为1．64～2．21级，平均1．96级．干样有机碳含量百分率也以鱼类最高，为33．0％～76．2％(m／m)，平均46．25％(m／m)；头足类为27．80％～46．16％(m／m),平均40．24％(m／m)；虾类为30．60％～38．40％(m／m),平均34．90％(m/m)；蟹类最低,为25．00％～30．78％(m/m)，平均28．24％(m／m),鲜样有机碳含量百分率还是以鱼类最高,为4．80％～29．55％(m／m),平均13．75％(m／m)；蟹类为8．90％～12．68％(m／m),平均10．74％(m/m)；虾类为6．97％～11．53％(m/m)，平均9．55％(m/m)；头足类最低仅为7．38％～8．52％(m／m),平均7．95％(m/m),干样有机碳含量百分率和鲜样有机碳含量百分率与营养级均成正相关，但前者的相关性高于后者。  相似文献   

南黄海陆架中部沉积物反射率光谱的影响因素分析     

王昆山  石学法  程振波  王国庆  葛淑兰 《海洋科学进展》2007,25(1):46-53

利用Minolta CM-2002光谱光度计对南黄海陆架136个短柱样品20~25cm段的沉积物进行了颜色反射率数据测量,通过化学元素、粒度、磁化率等来确定影响沉积物颜色反射率变化的成分和因素,介绍了反射率光谱的一阶导数和因子分析的方法。分析结果表明,南黄海陆架沉积物颜色反射率受控于沉积物中的铁氧化物、有机质以及粘土矿物和钙质生物碎屑含量。主因子F1指示氧化环境,并与陆源物质相关,F2指示弱氧化环境,F3指示弱还原环境,主因子的波长范围分别是405~445 nm和495~595 nm,605~695 nm,445~485 nm。  相似文献   

胶州湾海水中颗粒有机碳含量的分布与变化   总被引：6，自引：1，他引：6  

孙作庆  杨鹤鸣 《海洋科学》1992,16(2):52-55

本文报道了胶州湾表层海水及C_3和D_3站中层和底层水中的颗粒有机碳(POC)的分布与变化规律。结果表明,胶州湾POC年平均浓度为155～410μg/L;平面分布有明显的规律性,近岸和河口一带的含量较高,湾中部较低,湾口诸站为最低;垂直分布有个别数值偏高或偏低现象,但没有明显的规律;季节变化较明显,初春较高,秋季较低。  相似文献   

有机饵料常规饵料对扣蟹品质的比较研究   总被引：2，自引：0，他引：2  

李廷友  谢标  阎斌伦  兰亚竹  田永祥 《海洋湖沼通报》2006,(2):82-88

从扣蟹的体重、壳长、壳宽,扣蟹体内粗蛋白、氨基酸及药物残留和重金属含量等几个方面比较了在有机养殖和常规养殖模式下扣蟹的品质。结果显示,在有机养殖模式下,扣蟹的体重增长,壳长、壳宽与常规养殖差异显著(p<0.05);体内粗蛋白含量、必需氨基酸含量中,有机养殖组为55.43%、48.07%,常规养殖组为46.55%、40.64%,常规养殖组扣蟹的氨基酸含量明显低于有机饵料养殖组;在药残和重金属含量方面,除常规养殖组的六六六检出外,其余指标均符合有机蟹卫生质量地方标准(DB32/T609.3-2003),但有机养殖组的重金属含量则远较常规养殖组低。  相似文献   

珠江口水域化学耗氧量、溶解氧、无机磷与有机磷的三维水质数学模拟   总被引：12，自引：0，他引：12       下载免费PDF全文

林卫强  李适宇 《海洋学报》2003,25(3):129-137

珠江沿岸城市排污量大,对污染源治理能力十分有限,大量污染物通过河流或直接排放到珠江口,河口区半封闭的地形及潮水顶托使得污染物不易输送出外海,致使珠江口水质恶化,原有海洋生态环境遭到破坏,反过来制约了经济的发展.  相似文献