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1.
Bulk particulate organic carbon in the East China Sea: Tidal influence and bottom transport 总被引：4，自引：0，他引：4
Five oceanographic surveys were carried out in the East China Sea (ECS) and Yellow Sea from 1999 to 2003. In all, seven different sections were surveyed, but one section (the PN section) was observed on every cruise. Two time-series stations were also surveyed, one located at the Changjiang River mouth, the other over the continental shelf in the PN section.We identified biogeochemical characteristics for waters close to the Changjiang Estuary and in the Kuroshio waters (KW), respectively. Resuspension is a strong feature near bottom over the ECS continental shelf, with suspended matter values 13 times higher than that for the surface. A model of particulate organic carbon (POC) dynamics based on a rectangle equation reveals that POC concentration close to the Changjiang Estuary varies with a semidiurnal period of ∼13 h, coinciding with the tidal period. The upper limit for POC residence times in the seasons we covered over the shelf are estimated to be on the order of weeks and generally increase seaward from near the Changjiang Estuary to the KW. Short POC residence times suggest that POC in the ECS is rapidly exported from euphotic waters.A nepheloid layer, observed as elevated suspended matter in near the bottom of the water column, is important in particle transfer over the shelf, especially in winter when the residual current flows mainly eastward. Cross-shelf transport of POC via the nepheloid layer is estimated to be 0.22 × 1012 g yr−1. Comparison with other work indicates that POC transport is ∼2% of the Changjiang POC input. 相似文献
2.
V.V.S.S. Sarma S.N.M. GuptaP.V.R. Babu T. AcharyaN. Harikrishnachari K. VishnuvardhanN.S. Rao N.P.C. ReddyV.V. Sarma Y. SadhuramT.V.R. Murty M.D. Kumar 《Estuarine, Coastal and Shelf Science》2009
To examine the influence of river discharge on plankton metabolic balance in a monsoon driven tropical estuary, daily variations in physico-chemical and nutrients characteristics were studied over a period of 15 months (September 2007 to November 2008) at a fixed location (Yanam) in the Godavari estuary, India. River discharge was at its peak during July to September with a sharp decrease in the middle of December and complete cessation thereafter. Significant amount of dissolved inorganic nitrogen (DIN, of 22–26 μmol l−1) and dissolved inorganic phosphate (DIP, of 3–4 μmol l−1) along with suspended materials (0.2–0.5 g l−1) were found at the study region during the peak discharge period. A net heterotrophy with low gross primary production (GPP) occurred during the peak discharge period. The Chlorophyll a (Chl a) varied between 4 and 18 mg m−3 that reached maximum levels when river discharge and suspended loads decreased by >75% compared to that during peak period. High productivity was sustained for about one and half months during October to November when net community production (NCP) turned from net heterotrophy to autotrophy in the photic zone. Rapid decrease in nutrients (DIN and DIP by ∼15 and 1.4 μmol l−1, respectively) was observed during the peak Chl a period of two weeks. Chl a in the post monsoon (October–November) was negatively related to river discharge. Another peak in Chl a in January to February was associated with higher nutrient concentrations and high DIN:DIP ratios suggest possible external supply of nitrogen into the system. The mean photic zone productivity to respiration ratio (P:R) was 2.38 ± 0.24 for the entire study period (September 2007–November 2008). Nevertheless, the ratio of GPP to the entire water column respiration was only 0.14 ± 0.02 revealing that primary production was not enough to support water column heterotrophic activity. The excess carbon demand by the heterotrophs could be met from the allochthonous inputs of mainly terrestrial origin. Assuming that the entire phytoplankton produced organic material was utilized, the additional terrestrial organic carbon supported the total bacterial activity (97–99%) during peak discharge period and 40–75% during dry period. Therefore, large amount of terrestrial organic carbon is getting decomposed in the Godavari estuarine system. 相似文献
3.
根据2017年12月—2019年12月和2018年小浪底水库泄洪期间对黄河下游营养盐的月观测和日观测,系统的分析了黄河下游溶解态营养盐浓度、组成和通量变化.结果表明,除DON(溶解有机氮)、DSi(溶解态硅)和DIP(溶解无机磷)外,其他各溶解态营养盐浓度均呈丰水期低、枯水期高的特点.在观测期间,DSi/DIN(溶解态... 相似文献
4.
We examined the carbonate system, mainly the partial pressure of CO2 (pCO2), dissolved inorganic carbon (DIC) and total alkalinity (TAlk) in the Changjiang (Yangtze) River Estuary based on four field surveys conducted in Sep.–Oct. 2005, Dec. 2005, Jan. 2006 and Apr. 2006. Together with our reported pCO2 data collected in Aug.–Sep. 2003, this study provides, for the first time, a full seasonal coverage with regards to CO2 outgassing fluxes in this world major river–estuarine system. Surface pCO2 ranged 650–1440 μatm in the upper reach of the Changjiang River Estuary, 1000–4600 μatm in the Huangpujiang River, an urbanized and major tributary of the Changjiang downstream which was characterized by a very high respiration rate, and 200–1000 μatm in the estuarine mixing zone. Both DIC and TAlk overall behaved conservatively during the estuarine mixing, and the seasonal coverage of these carbonate parameters allowed us to estimate the annual DIC export flux from the Changjiang River as ∼ 1.54 × 1012 mol. The highly polluted Huangpujiang River appeared to have a significant impact on DIC, TAlk and pCO2 in the lower reaches of the inner estuary. CO2 emission flux from the main stream of the Changjiang Estuary was at a low level of 15.5–34.2 mol m− 2 yr− 1. Including the Huangpujiang River and the adjacent Shanghai inland waters, CO2 degassing flux from the Changjiang Estuary may have represented only 2.0%–4.6% of the DIC exported from the Changjiang River into the East China Sea. 相似文献
5.
2012年2月至2014年3月在黄河下游采集水样,分析黄河下游营养盐浓度与通量的月际、季节性以及在调水调沙期和暴雨期的变化情况,并估算了调水调沙期和洪水期输水量和营养盐入海通量对黄河年入海通量的贡献。结果表明NO3- 是TDN的主要存在形式,各形态氮营养盐枯水期高于丰水期;DIP是TDP的主要存在形式,PIP是TPP的主要存在形态,颗粒态磷和DSi丰水期高于枯水期。黄河水体中具有高DIN/DIP和DSi/DIP,低DSi/DIN,严重偏离Redfield比值。营养盐输送通量具有很强的月际变化,在径流量及输沙量最大月份也存在营养盐入海通量峰值。2002-2012年10年间调水调沙和暴雨在营养盐输送通量上占黄河下游营养盐输送通量的23%~68%和5%~59%,对营养盐年入海通量的平均贡献分别为 38%和24%,二者均在短期内导致水、沙和营养盐的大量输送,将对黄河口及其邻近海域的生态环境产生重要的影响。 相似文献
6.
Transfer and transport of phosphorus and silica in the turbidity maximum zone of the Changjiang estuary 总被引：1，自引：0，他引：1
The concentration of suspended particulate matter (SPM), sedimentation flux, and various forms of phosphorus and silica in turbidity maximum zone (TMZ) in the Changjiang (Yangtze) estuary was studied. Based on the budget of P and Si, their mass balances in the TMZ were calculated. Results show that the variation in concentration of dissolved inorganic silicon (DISi) was mainly controlled by seawater dilution, while that of dissolved inorganic phosphorus (DIP) was considerably affected by the buffering of suspended matter and sediment. Our experiments showed that the sedimentation fluxes of SPM and particulate inorganic phosphorus (PIP), total particulate phosphorus (TPP), particulate inorganic silicon (PISi), and biological silicon (BSi) in the TMZ were 238.4 g m−2 d−1 and 28.3, 43.1, 79.0, 63.0 mg m−2 d−1, respectively. In addition, a simple method to estimate the ratio of resuspension of sediment in the TMZ was established, with which the rate in surface and bottom waters of the TMZ accounted for 55.7 and 66.1% of the total SPM, respectively, indicating that the sediment resuspension in the TMZ influenced significantly the mass balances of P and Si. Particulate adsorbed P (60.8%) and 35.5% of total particulate P discharged from the river were filtered and then deposited in the TMZ. The input flux of PIP from the river mouth was 55.9% of that of DIP, being important as biologically available P, while that of PISi was only 3.5% of DISi, showing that particulate adsorbed Si was much less important than particulate adsorbed P. 相似文献
7.
8.
近30a来长江口海域生态环境状况变化趋势分析 总被引：2，自引：1，他引：1
在过去近30a监测结果基础上,对长江口海域生态环境变化趋势进行了分析。结果表明,近30a来,长江口海域水体中无机氮和活性磷酸盐呈现上升的趋势,重金属(铜、铅、镉和总汞)在一定范围内波动;浮游生物的种类数年际变化较大,浮游植物中硅藻比例有所下降,甲藻所占比例有所上升,浮游动物中桡足类的比例下降。讨论了长江径流输沙量与环境因子之间的相关性,发现硅酸盐的含量与输沙量呈显著正相关,且硅酸盐的减少与海域硅藻比例的减少具有一定相关性。长江口及其邻近海域环境与生态状况有所下降,特别是本世纪以来,海域的主要污染物仍为无机氮和活性磷酸盐,生物状态基本稳定在一个较低的水平上,近年来虽偶有波动,但没有明显改善的趋势。 相似文献
9.
长江口及邻近海域细颗粒沉积物中重金属的空间分布及沉积通量 总被引：4，自引：0，他引：4
长江每年输送大量的泥沙进入东海,其中细颗粒沉积物具有搬运距离远、扩散范围大的特点,成为示踪河口及近海沉积物源汇过程的良好载体。本文基于采自长江口及邻近海域的44个表层沉积物样品,分析了细颗粒组分中重金属的空间分布和沉积通量,探讨了重金属来源和搬运沉积过程。研究表明:长江口及邻近海域细颗粒沉积物中Cu、Cr、Ni、V和Zn含量、沉积通量的空间分布具有高度的相似性,总体表现为长江口及浙闽沿岸高,向外急剧降低;该区细颗粒沉积物中的重金属主要来自长江,入海后向两个方向扩散,其一为向西南方向扩散,沉积于内陆架泥质区;其二是向东的跨陆架输送,沉积于长江冲淡水影响的海域。从长江口向西南方向的输送和沉积是长江入海重金属最重要的汇。 相似文献
10.
An-Yi Tsai Gwo-Ching Gong Robert W. Sanders Ciou-Jyu Wang Kuo-Ping Chiang 《Estuarine, Coastal and Shelf Science》2010
Variation in the summer nanoflagellate community on the continental shelf ecosystem of East China Sea (ECS) is closely coupled with environmental variation due to extension of the Changjiang River plume. Spatial patterns of nanoflagellate abundance were studied in June and August 2003, June 2006 and July 2007 over the ECS shelf. The Changjiang River plume was smaller during the August 2003 and July 2007 cruises than during the rest other 2 cruises. Total nanoflagellates densities varied between 1 and 120 × 102 cells ml−1 with the highest abundances occurring within the Changjiang River plume during large plume periods. In the small plume periods, the range of nanoflagellates abundance was 3–33 × 102 cells ml−1 and the highest abundances were observed during these periods either within the Changjiang River plume or the Yellow Sea Coastal Water (YSCW). During large plume periods, nanoflagellate abundance closely related to changes in salinity and during the small period, abundance was most related to water temperature. The pigmented nanoflagellate community (PNF) within Changjiang River plume, especially in the <3 μm size class, appears to increase in response to terrestrial or anthropogenic inorganic nutrient loading in the discharge of fresh water from the Changjiang River. The PNF abundance pronounced increase caused the variation of nanoflagellate community of ECS in summer. We suggest that the discharge of fresh water from Changjiang River has significant ecological impacts on spatial variations in nanoflagellate community in the ECS. 相似文献
11.
悬浮体系指悬浮在水中,经过过滤能停留在滤膜或滤纸上的一切物质质点，其中包括泥沙颗粒、浮游生物及各种胶体物质等。悬浮体浓度分布是自然环境条件的综合反映，与物质来源，海洋环流、潮流、波浪等动力要素密切相关。因此，悬浮体浓度及运移途径是测试环境条件的重要参数，对其进行研究将对开发港口、合理利用土地资源、保护生态环境具有重要的实际意义，对于探讨现代沉积过程则具有理论意义。 相似文献
12.
根据１９８８年７月调查资料讨论了台湾海峡中北部海域夏季上升流区各种形态磷的分布特征。结果表明，上升流中心区（即海坛岛东侧一带水域）具有低温、高盐、低溶解氧；ＤＩｐ，ＴＤＰ，ＰＰ，ＴＰ较高；ＤＯＰ较低（０．２７）；及ＤＩＰ／ＤＯＰ比值（约为１）较高的特性。ＤＯＰ是该海域磷的主要形态（占ＴＰ的４９．２％），其含量分布及其形态转化与生物活动直接相关，是该海域生物生产力高的体现。 相似文献
13.
Seasonal variation of horizontal material transport through the eastern channel of the Tsushima Straits 总被引：2，自引：2，他引：0
Akihiko Morimoto Tetsutaro Takikawa Goh Onitsuka Atsushi Watanabe Masatoshi Moku Tetsuo Yanagi 《Journal of Oceanography》2009,65(1):61-71
We conducted hydrographic observations ten times in the Tsushima Strait to reveal seasonal variations of horizontal material
transports such as of heat, freshwater, chlorophyll a, and dissolved inorganic nitrogen (DIN) and phosphorus (DIP) through the eastern channel of the Tsushima Strait (ECTS). The
volume, freshwater, and heat transport results are of nearly the same order as results reported in previous studies. The annual
mean DIN and DIP transports of 3.59 kmol/s and 0.29 kmol/s are large relative to those of the Changjiang and the Taiwan Strait
and are horizontally transported through the ECTS. Nutrient transports are high in July–August and October and low in April
and November. Increased nutrient transports in July–August and October are due to the appearance of a cold saline water mass
in the bottom layer of the ECTS. Changes in DIN transports in summer and autumn, which account for two-thirds of the total
annual DIN transport, would have a large effect on the nitrogen budget and biological productivity in the Tsushima Warm Current
region. 相似文献
14.
长江口区营养盐的分布特征及三峡工程对其影响 总被引：9，自引：0，他引：9
在长江口海区,长江冲淡水、台湾暖流、黄海冷水等多种水系混合、交汇,错综复杂。对河口营养盐分布变化规律的研究,将为河口环境和生态变化提供可靠的依据,营养盐作为长江口这一世界著名渔场的化学物质基础具有重要意义。本文通过对长江口及其附近海域的周年观察,讨论了各种营养盐(包括磷、硅和氮)的时空变化规律和它们在河口的转移过程,估算了营养盐的年输出量,并提出了长江流量和营养盐输出量之间的关系,初步预报了三峡工程对长江口营养盐可能产生的影响。 相似文献
15.
长江口及邻近海区营养盐结构与限制 总被引：5，自引：0，他引：5
通过研究长江口及邻近海域溶解无机氮(DIN=NO3-+NO2-+NH4+)、磷酸盐(PO43-)、硅酸盐(SiO32-)所表征的营养盐区域结构特征及影响因素,在分析营养盐绝对限制情况的基础上,划分了潜在相对营养限制区域。结果表明,123°E以西近岸表层区域DIN/P比值全年均高于16,而Si/DIN除秋季外基本小于1,显示出长江冲淡水影响下"过量氮"的特征。春夏季河口锋面区(31°~32.5°N,122.5°~124°E)硅藻的大量生长可使DIN/P异常升高和Si/DIN异常降低。秋季研究区域北部DIN/P西低东高且Si/DIN西高东低是由于在高DIN、低PO43-的长江冲淡水影响下,近岸受相对低DIN、高SiO32-的苏北沿岸流南下入侵影响而被分割而成。冬季长江口门东北部存在的高DIN/P和低Si/DIN区则主要由于寡营养盐的黑潮水深入陆架,向东北输送的部分长江冲淡水和增强的苏北沿岸流共同作用造成DIN升高所致。利用Redfield比值进行了不同站位表层潜在相对营养限制情况的区分。近岸123°E以西受高DIN、SiO32-长江冲淡水影响,四季多呈现PO43-潜在相对限制,而在春夏季由于浮游植物的大量吸收PO43-,造成局部PO43-绝对限制及潜在相对限制。春夏季氮限(DIN潜在相对限制)一般发生在外海部分站位,但较为零散。秋季除了东南外海大部分站位外,受苏北沿岸流影响在长江口北部近岸也存在氮限。随着低DIN/P的黑潮表层水(KSW)的入侵加强,冬季外海氮限站位增多。硅限(SiO32-潜在相对限制)在夏季发生在赤潮高发区,而冬季南部存在较多硅限站位表明KSW中SiO32-相对较为缺乏。 相似文献
16.
The distribution of dissolved (soluble and total) and particulate (leachable and total) aluminum was examined in the Columbia River and estuary, in near-field and far-field river plumes, and in adjacent coastal waters of Washington and Oregon during the River Influence on Shelf Ecosystems (RISE) cruise of May/June 2006. Dissolved and particulate aluminum (Al) concentrations were significantly greater in the river than in the coastal waters that mixed to form the plume. Dissolved Al concentrations in the Columbia River (∼80 nM) were low relative to other major rivers. Leachable and total particulate Al concentrations within the river reached concentrations greater than 1000 nM and 18,000 nM, respectively. Dissolved Al within the Columbia River estuary showed a significant removal (∼60%) at salinities between 0 and 10 with salt-induced flocculation of colloidal Al complexes and enhanced particle scavenging being probable explanations for aluminum removal. Dissolved and particulate Al concentrations were significantly greater in near-field plumes relative to surrounding coastal waters. As the plume advected from near-field to far-field away from the river mouth, dilution of the plume with lower dissolved Al surface waters as well as particle scavenging along the flow path appeared to be controlling dissolved Al distributions. Particle settling as well as dilution with lower particle-load waters led to observed decreases in particulate Al as the plume moved from near-field to far-field. However, the percent-leachable particulate aluminum in both near-field and far-field plumes was remarkably constant at ∼7%. Dissolved and particulate Al in a far-field plume over 100 km southwest of the Columbia River mouth were over an order-of-magnitude greater than surrounding waters, illustrating the importance of the Columbia River plume as a mechanism for transporting Al offshore. Aluminum could be used to trace the input of biologically-required elements such as iron into waters off the shelf. 相似文献
17.
Nutrients,light and phytoplankton production in the shallow,tropical coastal waters of Bandon Bay,Southern Thailand 
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下载免费PDF全文 Takashi Yoshikawa Kosuke Tomizawa Yuki Okamoto Kazuya Watanabe Jintana Salaenoi Kenichi Hayashizaki Hisashi Kurokura Satoshi Ishikawa 《Marine Ecology》2017,38(6)
Phytoplankton primary production and its regulation by light and nutrient availability were investigated in the shallow, tropical coastal waters of Bandon Bay, Southern Thailand. The bay was meso‐eutrophicated and highly turbid, receiving river water discharge. Water column stratification was consistently weak during both rainy and dry seasons. Dissolved inorganic nitrogen (DIN) was higher off the river mouth than in the other regions, suggesting that river water discharge was a main source of DIN. By contrast, dissolved inorganic phosphorus (DIP) showed a significant negative correlation with total water depth, implying that regeneration around the sea floor was an important source of DIP. Surface DIN and DIP showed positive correlations with surface primary production (PP) and water column primary productivity (ΣPP*), respectively. The combined correlation and model analyses indicate that total water depth had an ambivalent influence on water column primary production (ΣPP); shallower water depth induced more active regeneration of nutrients, but it also caused higher turbidity and lower light availability as a result of enhanced resuspension of sediments. Furthermore, there was a vertical constraint for phytoplankton during the rainy season: total water depth tended to be shallower than euphotic zone depth. In conclusion, light limitation and vertical constraint owing to shallow water depth appear to be more important than nutrient limitation for water column primary production in Bandon Bay. 相似文献
18.
F. Delgadillo-Hinojosa A. Zirino O. Holm-Hansen J.M. Hernández-Ayón T.J. Boyd B. Chadwick I. Rivera-Duarte 《Estuarine, Coastal and Shelf Science》2008
The temporal and spatial variability of dissolved inorganic phosphate (DIP), nitrogen (DIN), carbon (DIC) and dissolved organic carbon (DOC) were studied in order to determine the net ecosystem metabolism (NEM) of San Diego Bay (SDB), a Mediterranean-climate lagoon. A series of four sampling campaigns were carried out during the rainy (January 2000) and the dry (August 2000 and May and September 2001) seasons. During the dry season, temperature, salinity and DIP, DIC and DOC concentrations increased from oceanic values in the outer bay to higher values at the innermost end of the bay. DIP, DIC and DOC concentrations showed a clear offset from conservative mixing implying production of these dissolved materials inside the bay. During the rainy season, DIP and DOC increased to the head, whereas salinity decreased toward the mouth due to land runoff and river discharges. The distributions of DIP and DOC also showed a deviation from conservative mixing in this season, implying a net addition of these dissolved materials during estuarine mixing within the bay. Mass balance calculations showed that SDB consistently exported DIP (2.8–9.8 × 103 mol P d−1), DIC (263–352 × 103 mol C d−1) and DOC (198–1233 × 103 mol C d−1), whereas DIN (5.5–18.2 × 103 mol N d−1) was exported in all samplings except in May 2001 when it was imported (8.6 × 103 mol N d−1). The DIP, DIC and DOC export rates along with the strong relationship between DIP, DIC or DOC and salinity suggest that intense tidal mixing plays an important role in controlling their distributions and that SDB is a source of nutrients and DOC to the Southern California Bight. Furthermore, NEM ranged from −8.1 ± 1.8 mmol C m−2 d−1 in September to −13.5 ± 5.8 mmol C m−2 d−1 in January, highlighting the heterotrophic character of SDB. In order to explain the net heterotrophy of this system, we postulate that phytoplankton-derived particulate organic matter, stimulated by upwelling processes in the adjacent coastal waters, is transported into the bay, retained and then remineralized within the system. Our results were compared with those reported for the heterotrophic hypersaline coastal lagoons located in the semi-arid coast of California–Baja California, and with those autotrophic hypersaline systems found in the semi-arid areas of Australia. We point out that the balance between autotrophy and heterotrophy in inverse estuaries is dependent on net external inputs of either inorganic nutrients or organic matter as it has been indicated for positive estuaries. 相似文献
19.
利用2011年春季(5-6月)、2009年夏季(8月)、2010年秋季(11-12月)和2009 年冬季(12月一次年1月)4个航次实测的悬浮体质量浓度资料,分析了东海陆架表层水体总悬浮体、有机悬浮体和无机悬浮体质量浓度的季节分布特征。结果表明,东海陆架表层水体总悬浮体质量浓度冬半年高于夏半年,等值线基本平行于岸线,在浙江沿岸29°N附近有一浑水舌向东南方向延伸,常年存在2个高值中心和2个次高值中心。有机悬浮体质量浓度则为夏半年高于冬半年,存在2个高值中心和2个次高值中心,季节变化显著。无机悬浮体质量浓度分布趋势相似于总悬浮体质量浓度,但整体轮廓线向近岸收缩约0.5°,常年存在2个高值中心和1个次高值中心。有机悬浮体占总悬浮体百分比按季节从高到低依次为春季、夏季、冬季和秋季,其中长江口、杭州湾外近海海域和黑潮区为东海有机悬浮体百分含量高值区。 相似文献
20.
镭、氡同位素示踪调水调沙对黄河口水体运移及营养盐分布特征的影响 总被引：2，自引：0，他引：2
为研究调水调沙影响下的镭、氡同位素和营养盐在黄河口的分布特征,于2013年7月调水调沙期间在黄河口及其邻近海域进行了多点的连续观测。研究发现:(1)黄河口海域镭、氡同位素分布呈现明显的“分区”现象,南北两区分别为“调水调沙影响非显著区域”和“调水调沙影响显著区域”,北部海域镭、氡同位素浓度高值主要来源于陆源输入(包括河流输入和海底地下水排放);(2)调查期间,北部海域水体年龄为(2.9±1.6)d,南部海域水体年龄为(5.0±2.1)d;水龄随潮汐变化表现出涨潮时水龄增大、落潮时水龄减小的波动趋势;(3)北部海域溶解无机氮(DIN)和溶解硅(DSi)含量明显高于南部海域,而溶解无机磷(DIP)在两个区域的含量相差不大。 相似文献