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夏季大亚湾悬浮颗粒有机物碳、氮同位素组成及其物源指示 总被引：5，自引：1，他引：4
2015年夏季开展了大亚湾悬浮颗粒有机物碳（POC）、氮含量（PN）及其同位素组成的研究,结果表明,δ13CPOC和δ15NPN的变化范围分别为-25.7‰~-17.4‰和-6.3‰~10.4‰,平均值分别为-20.2‰和8.2‰。大亚湾悬浮颗粒有机物含量及其碳氮同位素组成的空间变化反映了不同有机质来源的影响:喜洲岛附近海域表现出高POC、PN、δ13CPOC和δ15NPN的特征,指征着浮游植物水华的主导贡献;东北部范和港附近海域具有高POC、PN、低δ13CPOC和高δ15NPN的特征,反映了河流/河口水生有机物的影响;湾顶白寿湾附近海域的δ13CPOC和δ15NPN出现低值,体现了陆源有机质和人类污水排放的影响。借助δ13CPOC和δ15NPN的三端元混合模型,定量出海洋自生有机质、陆源有机质、河流/河口水生有机质等3个来源的贡献平均分别为70%、13%和17%,其中海洋自生有机质是夏季大亚湾悬浮颗粒有机物的最主要来源。从这3种来源颗粒有机物含量的空间变化看,海洋自生有机质含量由湾内向湾外减少,与初级生产力的空间变化相对应;河流/河口水生有机质含量在大亚湾东北部出现高值;陆源有机质含量在表、底层出现不同态势,表层陆源有机物含量在湾中部海域最低,而底层则呈现出自湾内向湾口增加的趋势,主要受控于离岸距离和珠江冲淡水、粤东沿岸上升流输送的影响。 相似文献
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基于2020年7月洪水期间采集的长江口及邻近海域的温度、盐度、总悬浮物(Total Suspended Matter,TSM)质量浓度、颗粒有机碳(Particulate Organic Carbon,POC)质量浓度和颗粒有机碳稳定同位素(δ13CPOC)等数据,分析了洪水事件对该区域POC分布与来源的影响。结果显示,研究区域内POC和盐度呈显著负相关(r2=0.41,p＜0.01),与TSM呈显著正相关(r2=0.92,p＜0.01),表明咸淡水的混合是影响POC分布的重要因素。研究区域东北部表层海水POC质量浓度局部升高,并且δ13CPOC值显示为海源信号,表明浮游植物生产是影响该海域POC分布的另一重要因素。此外,由于高径流量形成的稀释效应,洪水事件会降低陆源输入的POC质量浓度,研究区域东南侧偏轻的δ13CPOC也表明,洪水事件会扩大陆源POC在东海的影响范围。 相似文献
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南沙渚碧礁生态系营养关系的稳定碳同位素研究 总被引：4，自引：0，他引：4
利用稳定碳同位素分析技术研究了南沙渚碧礁生态系食物网主要生物类群之间的营养关系。结果表明，生物的稳定碳同位素组成与其营养来源有密切关系。浮游植物的δ^13C为-18.3‰，与其所处海域的环境条件一致，浮游动物的δ^13C值变化较大，范围为-20.4‰～-10.9‰,表明可能存在浮游植物和碎屑两种营养来源。珊瑚和砗磲的碳同位素组成（-17‰～-15‰）与浮游动物相差较大，暗示共生虫黄藻可能在这些珊瑚的营养来源中起重要作用。底栖海参（-9.6‰)和蜘蛛螺（-12.5‰)的碳同位不比组成与它们沉积物食性的营养特征吻合。鱼类的δ^13C值变化范围较大（-17.7‰～-10.9‰），未表现出随营养级升高而增大的趋势，说明影响鱼类碳同位素组成的因素比较复杂。 相似文献
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为了解中街山列岛的食物网结构特征,本研究于2020年7月在中街山列岛海域采集鱼类、虾蟹类、头足类、贝螺类和浮游动物等消费者样本,利用碳、氮稳定同位素技术,分析大型海藻、浮游植物、悬浮颗粒有机物(POM)和沉积物有机物(SOM)4种潜在碳源对消费者的贡献率以及中街山列岛海域的食物网结构和营养关系。结果表明：(1)碳源的δ13C值范围在-22.93‰～-9.73‰之间,δ15N值范围在1.72‰～7.68‰之间,消费者的δ13C值范围在-21.95‰～-12.55‰之间,δ15N值范围在4.13‰～12.92‰之间,不同碳源及不同消费者类群之间的碳、氮稳定同位素均有显著性差异(p<0.01);(2)应用SIBER模型计算中街山列岛海域的营养结构指标,与其他海域的研究结果对比发现,该海域生态系统的食源多样性更加丰富,营养级长度和生态位总空间较高;(3)应用SIAR模型计算碳源贡献率,结果表明浮游植物和POM是该海域的重要碳源,平均贡献率为29.63%和28.72%;浮游植物对浮游动物的贡献率最大为80.58%,POM对鱼类的贡献率最大为79.... 相似文献
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长江口海域悬浮颗粒有机物的稳定氮同位素分布及其生物地球化学意义 总被引：4，自引：0，他引：4
对2006年2,5,8,11月份长江口海域表层水体中的悬浮颗粒物(SPM)进行稳定氮同位素分析,根据不同季节、不同区域内其1δ5N值的变化研究水体中氮的迁移、转化等生物地球化学过程,揭示其环境行为,从而对该海域的氮循环机制进行探索。研究发现:该海域悬浮颗粒有机物的稳定氮同位素组成(1δ5Np)分布范围较宽,在0.6‰~8.2‰之间,具有明显的时空分布特点,反映了不同程度的陆源输入和氮的生物地球化学过程的影响。口门内,表层水体中1δ5Np的变化主要受长江径流的陆源输入影响,生物地球化学作用影响较弱;最大浑浊带,水体中的悬浮颗粒有机氮受微生物的降解活动影响明显,各季节均存在不同程度的颗粒物分解作用;外海区,陆源输入减弱,悬浮颗粒物的δ15Np值主要受微藻的同化吸收作用以及一定程度的颗粒物分解作用影响。 相似文献
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长江口海域悬浮颗粒有机物的稳定氮同位素季节分布与关键生物地球化学过程 总被引：2，自引：2，他引：0
对2010年2、5、8、11月份长江口海域水体中的悬浮颗粒物进行稳定氮同位素分析。根据不同季节、不同区域内悬浮颗粒有机物的稳定氮同位素组成(δ15 Np)值的变化研究水体中氮的迁移、转化等生物地球化学过程,揭示其环境行为,从而对该海域的氮循环机制进行探索。研究发现:长江口海域悬浮颗粒物的稳定氮同位素组成具有较宽的分布范围,δ15 Np值分布范围为-1.1‰~8.6‰,具有明显的时空分布特点,反映了不同程度的陆源输入和氮的生物地球化学过程的影响。其中,2月份生物反应较弱,δ15 Np分布体现了陆源和海源的混合特征;5月和11月份上层水体δ15 Np随叶绿素a升高而降低,指示了生物的同化吸收作用;8月和11月δ15 Np和总溶解无机氮呈现极显著正相关关系,说明该海域发生了氮的矿化再生。 相似文献
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~(13)C/~(12)C比值在海洋生态系统营养关系研究中的应用──海洋植物的同位素组成及其影响因素的初步探讨 总被引：6，自引：0，他引：6
于1993年2月-1995年5月,采用生物显微镜鉴定并计数和高温氧化的方法,对崂山湾海洋植物的种类组成及其有机碳同位素组成的季节性变化作了5个季度月的研究。结果表明,该区同采浮游植物全年以硅藻为主,甲藻在夏季也可成为优势种之一。浮游植物的碳同位素组成在夏季较重,冬季和春季较轻,并与海水温度有弱的正相关性。浮游植物δ13C值的变化范围为-259ｘ10-3—-19.2ｘ10-3,全年平均值为（-23.2±2.4）ｘ10-3。该生态系统的另一碳源为底栖藻类,其δ13C平均值为（-18.5±2.4）ｘ10-3,明显区别于浮游植物。对除温度以外的其它影响海洋植物同位素组成的因素,诸如植物种类组成、海水中溶解无机碳δ13C值、CO2供应速率以及CO2固定过程中不同验化酶的同位素分馏作用等也作了初步探讨。 相似文献
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南海北部浅表层沉积底栖有孔虫碳同位素及其对富甲烷环境的指示 总被引：3，自引：0，他引：3
对南海北部陆坡东沙海域、神狐海域及西沙海槽甲烷渗漏环境和无甲烷渗漏环境87个浅表层沉积物中的底栖有孔虫Uvigerinaspp.进行碳同位素分析研究,结果表明,东沙海域δ13C值为-0.52‰~-5.68‰,平均值为-1.41‰,出现明显的负偏移;神狐海域δ13C值介于-0.36‰~-1.10‰,平均值为-0.75‰,未见明显的δ13C值负偏移;西沙海槽δ13C值介于-0.01%~-0.89‰,平均值为-0.45‰;对Uvigerinaspp.碳同位素组成与沉积物有机碳(TOC)、甲烷(CH4)间的关系进行探讨,发现δ13C负偏移主要出现在甲烷渗漏环境,发生在末次盛冰期,与溶解无机碳负偏移以及沉积物全样的δ13C值负偏移层位相吻合,有可能作为富甲烷环境的替代指标。 相似文献
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魁蚶（Anadara broughtonii）是我国北方重要的经济贝类,筏式养殖是其主要的生产方式。2014年5月至2015年1月,测定了不同季节灵山湾筏式养殖魁蚶及其3种潜在食物源（表层颗粒有机物SPOM、底层颗粒有机物BPOM和附着微藻AM）的碳氮稳定同位素（δ13C和δ15N）,结合胃含物分析研究了海区食物源结构的季节变化对魁蚶食物组成的影响。结果显示,魁蚶及其食物源的稳定同位素比值均存在明显的季节差异,魁蚶的δ13C值（-19.6‰~-19.2‰）介于SPOM （-23.3‰~-21.8‰）、BPOM （-22.1‰~-21.2‰）和AM（-17.0‰~-16.0‰）之间,δ15N值范围集中在8.7‰~9.9‰。冬季魁蚶的δ13C值最低,δ15N值则最富集。水体颗粒有机物（主要由浮游植物组成）是魁蚶的主要食物来源（60.0%~77.8%）,以夏季的饵料贡献率最高;海区再悬浮作用使BPOM的贡献率始终维持在较高水平（30.8%~47.1%）;而养殖网笼上的附着微藻也可为魁蚶提供约22.1%~40.0%的食物。研究揭示了筏式养殖魁蚶可以混合滤食颗粒有机物和附着微藻,附着微藻是其重要的食物补充。 相似文献
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Chunyan Ren Min Chen Laodong Guo Jian Zeng Renming Jia Xiao Liu Minfang Zheng Yusheng Qiu 《海洋学报(英文版)》2020,39(12):42-53
During the 29th Chinese National Antarctic Research Expedition, spatial variations in nitrogen isotopic composition of particulate nitrogen (δ15NPN) and their controlling factors were examined in detail with regard to nitrate drawdown by phytoplankton and particulate nitrogen (PN) remineralization in the Prydz Bay and its adjacent areas. To better constrain the nitrogen transformations, the physical and chemical parameters, including temperature, salinity, nutrients, PN and δ15NPN in seawater column were measured from surface to bottom. In addition, the nitrogen isotopic fractionation factor of nitrate assimilation by phytoplankton in the mixed layer, and the nitrogen isotopic fractionation factor of PN remineralization below the mixed layer were estimated using Rayleigh model and Steady State model, respectively. Our results showed that suspended particles had its lowest δ15NPN in the surface layer, which was due to the preferential assimilation of 14N in nitrate by phytoplankton. The δ15NPN in the mixed layer of the Prydz Bay and its adjacent areas decreased from the inner shelf to the outer basin, ascribing to the effect of isotope fractionation during phytoplankton assimilation. In mixed layer, the spatial distribution of δ15NPN associated with particulate organic matter (POM) production can be well interpreted according to Rayleigh model and Steady State model. The nitrogen isotope fractionation factor during phytoplankton assimilating nitrate was estimated as 10.0‰ by Steady State model, which was more reasonable than that calculated by Rayleigh model. These results validate the previous reports of fractionation factor during nitrate assimilation by phytoplankton. Increasing δ15NPN with depth below the euphotic zone correlated with the decreasing PN contents, and it was attributed to preferential remineralization of 14N in PN by bacteria. In subsurface and deep layer, the δ15NPN distributions also conformed to Rayleigh model and Steady State model during PN remineralization, with a fractionation factor of about 3.6‰ and 3.2‰, respectively. It is the first time to estimate the fractionation factor during POM production and remineralization in the Prydz Bay and its adjacent areas. Such fractionation may provide a useful tool for the follow-up study of the nitrogen dynamics in the Southern Ocean. 相似文献
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楚科奇和西伯利亚陆架颗粒有机物的来源：碳、氮同位素的线索 总被引：2，自引：1，他引：1
The stable isotopic composition(δ~(13)C and δ~(15)N) and carbon/nitrogen ratio(C/N) of particulate organic matter(POM) in the Chukchi and East Siberian shelves from July to September, 2016 were measured to evaluate the spatial variability and origin of POM. The δ~(13)C_(POC) values were in the range of -29.5‰ to-17.5‰ with an average of -25.9‰±2.0‰, and the δ~(15)N_(PN) values ranged from 3.9‰ to 13.1‰ with an average of 8.0‰±1.6‰. The C/N ratios in the East Siberian shelf were generally higher than those in the Chukchi shelf, while the δ~(13)C and δ~(15)N values were just the opposite. Abnormally low C/N ratios(4), low δ~(13)C_(POC)(almost-28‰) and high δ~(15)N_(PN)(10‰) values were observed in the Wrangel Island polynya, which was attributed to the early bloom of small phytoplankton. The contributions of terrestrial POM, bloom-produced POM and non-bloom marine POM were estimated using a three end-member mixing model. The spatial distribution of terrestrial POM showed a high fraction in the East Siberian shelf and decreased eastward, indicating the influence of Russian rivers. The distribution of non-bloom marine POM showed a high fraction in the Chukchi shelf with the highest fraction occurring in the Bering Strait and decreased westward, suggesting the stimulation of biological production by the Pacific inflow in the Chukchi shelf. The fractions of bloom-produced POM were highest in the winter polynya and gradually decreased toward the periphery. A negative relationship between the bloom-produced POM and the sea ice meltwater inventory was observed, indicating that the net sea ice loss promotes early bloom in the polynya.Given the high fraction of bloom-produced POM, the early bloom of phytoplankton in the polynyas may play an important role on marine production and POM export in the Arctic shelves. 相似文献
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长江口盐度梯度下不同形态碳的分布、来源与混合行为 总被引：1，自引：0，他引：1
河口碳的生物地球化学过程是全球碳循环的重要组成。通过测定溶解无机碳（DIC）及其稳定同位素丰度（δ13CDIC），溶解有机碳（DOC），有色溶解有机物（CDOM），颗粒有机碳（POC）及其稳定同位素丰度（δ13CPOC）与元素比值（N/C）及相关指标，研究了2014年7月长江口盐度梯度下不同形态碳的分布、来源和混合行为。结果表明，DIC浓度、DOC浓度、POC含量分别为1 583.2~1 739.6 μmol/L，128.4~369.4 μmol/L和51.2~530.8 μmol/L，这些不同形态碳及CDOM的荧光组分的分布模式相似，均是从口内到口外，整体呈现先增大后减小的趋势，并与盐度呈现非保守混合行为。添加作用主要发生在在口门处最大浑浊带附近。与含量相反，从口内到口外，δ13CDIC和δ13CPOC均呈现逐渐减小再增大的趋势，在口门附近达到最低值，分别为-9.7‰和-26.7‰。在口门附近不同形态碳含量上升及δ13CDIC、δ13CPOC的降低可能主要与沉积物再悬浮及微生物作用有关。基于蒙特卡洛模拟的三端元混合模型的结果显示，河口内外POC来源变化明显，口内POC以陆源有机碳贡献为主，平均为62.3%，口外海源贡献逐渐增加。CDOM相关参数结果表明长江口CDOM主要来自陆源输入，海源及人类活动等也对其产生影响。 相似文献
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As one of the most common and dominant species in the Southern Ocean, Antarctic krill(Euphausia superba)play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in the Prydz Bay during austral summer of 2012/2013 was investigated and the ontogenetic shift in krill diet was evaluated using the stable isotope method. The nitrogen stable isotope values(δ~(15) N) of adults((2.78±0.58)‰) were much higher than those of juveniles((1.69±0.70)‰), whereas the carbon stable isotope values(δ~(13) C) of adults(–(28.26±1.08)‰) were slightly lower than those of juveniles(–(27.48±1.35)‰). Particulate organic matter(POM)from 0, 25, and 50 m depth combined(0/25/50 m) represented phytoplankton food items. The results showed that phytoplankton food items in surface water and mesozooplankton were two essential food items for Antarctic krill in the Prydz Bay during summer. POM(0/25/50 m) contributes 56%–69% and 26%–34% to the diet of juvenile and adult krill, respectively, whereas mesozooplankton composes 13%–34% and 58%–71% of the diet of juvenile and adult krill, respectively. Thus, an ontogenetic diet shift from POM(0/25/50 m), which consists mainly of phytoplankton, to a higher trophic level diet containing mesozooplankton, was detected. The capacity for adults to consume more zooplankton food items may minimize their food competition with juveniles, which rely mostly on phytoplankton food items. This suggests "diet shift with ontogeny" which may somehow help krill keep their dietary energy budget balanced and well adapted to the Antarctic marine ecosystem as a dominant species. 相似文献
15.
环境饵料丰度的季节变化对筼筜湖3种大型底栖动物食性的影响——来自稳定同位素的证据 总被引：4，自引：1，他引：3
测定了不同时期筼筜湖3种大型底栖动物(沙筛贝Mytilopsis sallei、日本大螯蜚Grandidierella japonica和腺带刺沙蚕Neanthes japonica)及其潜在食源的稳定同位素组成(δ13C和δ15 N),研究环境饵料丰度的季节变化对筼筜湖3种大型底栖动物食性的影响。结果显示,筼筜湖悬浮颗粒有机物(Particulate organic matter∶POM)的δ13C和δ15 N存在明显的季节变化。3月,受到输入筼筜湖的西海域海水大量陆源有机碎屑以及湖区周围的生活污水以及餐饮业输入的影响,筼筜湖POM的δ13 C和δ15 N明显贫化;而在9月,POM中δ13 C和δ15 N明显富集的内源性浮游植物的贡献增加。沙筛贝是典型的底栖滤食者,主要以POM为食,但它比POM富集的δ13 C值(3月和9月二者之间的Δδ13 C分别为2.9‰和1.6‰)表明它还摄入其他δ13 C相对富集的食物来源:石莼来源的有机碎屑可能是3月份沙筛贝δ13C富集的原因,而9月份则是由于再悬浮的底栖微藻对沙筛贝食源的贡献引起的。食碎屑的腺带刺沙蚕和日本大螯蜚在3月以石莼及其表面的附生生物为食,而9月份底栖微藻和浮游植物来源的POM是它们食源的主要贡献者。本研究的结果显示,筼筜湖3种大型底栖动物的δ15 N都出现明显的季节变化(Δδ15 N介于2.2‰~4.3‰),这是由于它们食源稳定同位素的季节性波动及其食性的季节变化引起的,而消费者食性的季节性变化则受到不同时期环境食物可利用性的影响。 相似文献
16.
Zixuan Li Chao Xu Minfang Zheng Mengya Chen Yusheng Qiu Hantao Zhou Min Chen Run Zhang 《海洋学报(英文版)》2023,42(1):1-11
The dual isotopes(N and O) of nitrate were measured using a denitrifier bacterial method in the western South China Sea(WSCS) during September 2015 to elucidate key information during N transformation in the lower euphotic zone(LEZ)-upper mesopelagic zone(UMZ,down to 500 m in this study) continuum,which is a vital sub-environment for marine N cycle and sequestration of atmospheric CO2 as well.The N isotopic composition(δ15N) of nitrate generally decreased from 500 m toward ... 相似文献
17.
The inner part of Isahaya Bay was converted to a freshwater reservoir following the closure of the land claim dike in 1997. Turbid water drains into Isahaya Bay when water levels increase. We investigated whether particulate organic matter (POM) from the reservoir in Isahaya Bay has caused bottom organic enrichment in the northern part of Ariake Bay. Using potential end-members from before to after the rainy seasons, during which a frequent discharge from the reservoir was expected, stable isotope analyses were performed on sediments collected from Isahaya Bay and northern Ariake Bay. Each end-member was isotopically differentiated by δ13C and δ15N (riverine POM: ?28.5 to ?27.2‰ and 3.3–4.6‰; reservoir POM: ?25.7 to ?25.3‰ and 7.4–8.4‰; marine POM: ?21.8 to ?19.7‰ and 6.7–7.6‰; microphytobenthos estimated from consumers: ?16.1 to ?15.9‰ and 5.2–6.1‰, respectively). Sediment isotopic signatures fell within the mixing space defined by the signatures of the end-members. Marine POM contributed greatly to bottom sediments in both seasons in Isahaya Bay and Ariake Bay, ranging from ca. 60–70 and 40–60%, respectively. Reservoir POM contributed around 10% to bottom sediments. This percentage slightly increased in the sediment of Isahaya Bay after the rainy season, but decreased in the sediment of Ariake Bay. Thus, most of the POM discharged from the reservoir would not reach the northern part of Ariake Bay and would not be a major contributor to organic enrichment. This study is the first to quantitatively describe the contribution of drained reservoir POM outside Isahaya Bay. 相似文献
18.
The coupling of upper ocean-benthic carbon dynamics in the ice-free western Arctic Ocean(the Chukchi Sea and the Canada Basin) was evaluated during the late July–early September 2003 using natural stable(13C) and radioactive(238U-234Th) isotope tracers. POC export flux estimated from 234Th/238 U disequilibria and dissolved CO2 concentration([CO2(aq)]) pointed out that the strengthened biological pump in the Chukchi Shelf have significantly lowered [CO2(aq)] and altered the magnitude of isotopic(12C/13C) fractionation during carbon fixation in the surface ocean. Further, d13 C signatures of surface sediments(d13Csed) are positively correlated to those of weighted d13 CPOC in upper ocean(d13Csed =13.64+1.56×d13CPOC, r2=0.73, p0.01), suggesting that the POC isotopic signals from upper ocean have been recorded in the sediments, partly due to the rapid export of particles as evidenced by low residence times of the highly particle-reactive 234 Th from the upper water column. It is suggested that there probably exists an upper ocean-benthic coupling of carbon dynamics, which likely assures the sedimentary d13 C record an indicator of paleo-CO2 in the western Arctic Ocean. 相似文献