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根据2018年7月、11月和2019年1月、4月对广东考洲洋牡蛎养殖海域进行4个季节调查获得的pH、溶解无机碳(DIC)、水温、盐度、溶解氧(DO)及叶绿素a(Chla)等数据,估算该区域表层海水溶解无机碳体系各分量的浓度、初级生产力(PP)、表层海水CO2分压[p(CO2)]和海-气界面CO2交换通量(FCO2),分析牡蛎养殖活动对养殖区碳循环的影响。结果表明:牡蛎养殖区表层海水中Chla、DIC、HCO3–和PP显著低于非养殖区;养殖淡季表层海水中pH、DO、DIC、HCO3–、和CO32–显著大于养殖旺季,养殖旺季的p(CO2)和FCO2显著大于养殖淡季。牡蛎养殖区表层海水夏季、秋季、冬季和春季的海-气界面CO2交换通量FCO2平均值分别是(42.04±9.56)、(276.14±52.55)、(–11.59±18.15)和(–13.02±6.71)mmol/(m2·d),冬季各站位FCO2值离散度较大,其中位数是–10.73mmol/(m2·d)。在全年尺度,表层海水p(CO2)及FCO2与水温呈显著正相关,与盐度呈显著负相关。在非养殖区,浮游植物光合作用可能对影响表层海水p(CO2)及FCO2起主导作用。养殖牡蛎钙化、呼吸作用等生理因素释放的CO2对表层海水p(CO2)及FCO2未产生显著影响。考洲洋养殖海域养殖旺季为CO2的源,养殖淡季整体为CO2的弱汇。 相似文献
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东海中北部海域秋季表层海水中无机碳与海气界面碳的迁移 总被引：2，自引：0，他引：2
基于2010 年11 月对长江口外东海中北部海域的综合调查, 系统研究了该海域的无机碳体系参数的分布特征、海?气界面二氧化碳通量及其影响因素。研究结果表明, 该海域秋季溶解无机碳(DIC)高值区主要出现在调查海域东北部及长江口附近海域, 而调查海域南部DIC 含量较少且变化平缓, 其主要是受台湾东部流向东北方向的黑潮支流及长江冲淡水的影响; 表层海水CO2分压(pCO2)值变化范围为40.8～63.5 Pa, 呈现沿黑潮支流流入方向由东南向西北逐渐增高的趋势。秋季表层海水pCO2与温度(T)、盐度(S)有较好的负相关性, 说明海水温度升高和盐度增加, pCO2降低, 反之亦然。另外, 通过估算得出, 秋季CO2海-气交换通量为2.69～33.66 mmol/(m2·d), 平均值为(14.35 ± 7.06 )mmol/(m2·d),其在长江口邻近海域相对较大, 而在调查海域南部相对较小; 2010 年秋季水体向大气释放CO2的量(以碳计)为(2.35 ± 1.16)×104 t/d, 是大气CO2较强的源, 说明东海中北部海域秋季总体上是CO2的源。 相似文献
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由于存在极高的初级生产和高效的碳代谢速率, 珊瑚礁海域二氧化碳(CO2)的汇/源属性仍存有争议。为明晰中国典型珊瑚礁海域CO2的汇源属性及驱动因素, 作者基于2022年11月(秋季)和2023年2月(冬季)在深圳杨梅坑海域的调查结果并结合室内培养实验所获得的数据, 探究了枯水季节典型亚热带珊瑚礁海水二氧化碳分压(pCO2)的分布特征及主要控制机制。结果表明, 调查期间pCO2的变化较大, 其范围为233.3~465.3 μatm。秋季表现为大气CO2的汇, CO2吸收通量为1.66±0.41 mmol C/(m2/d);冬季表现为大气CO2的弱源, 其释放通量为0.36±0.17 mmol C/(m2/d)。调查期间(枯水季)杨梅坑海域受淡水输入的影响较小, 季节性温度影响下的生物过程是驱动pCO2变化的关键因素, 其贡献pCO2总变化量的73.6%(表层)和66.5%(底层)。其中, 浮游植物光合作用的季节差异是导致海水CO2汇源转变的主要成因, 而微生物呼吸作用的影响甚微。相比较, 物理过程(CO2海-气交换、温度和盐度变化)对pCO2的影响相对较小, 其作用结果远低于生物过程。此外, 珊瑚的代谢活动对杨梅坑局部海域pCO2分布产生一定影响, 造成礁区pCO2值高于非礁区。因此, 海气CO2通量估算中不能忽视局部海域珊瑚代谢作用的影响。 相似文献
4.
近年来, 渤海夏季低氧现象频发, 引起了人们的广泛关注。然而对该海域低氧形成的机制还未得到充分认识。研究基于在秦皇岛外海的现场观测, 分析了海水中颗粒物吸收光谱特征及其与不同粒径浮游植物叶绿素a (chl a)组成、环境因子的关系, 评估了夏季底层水体脱氧过程中有机物来源与特征。结果显示,夏季秦皇岛外海微型浮游植物chl a占总量的80%。表层水体中, 总颗粒物吸收光谱[ap(l)]特征由浮游植物色素吸收光谱[aph(l)]主导, 在中、底层水体中则由碎屑颗粒物吸收光谱[ad(l)]主导。垂向上, ap(440)和ad(440)均表现为表层<中层<底层。结果还表明, 浮游植物粒径主导秦皇岛外海chl a的光吸收效率, 即a*ph(440)。基于三粒级chl a含量, 可利用多元回归预测aph(440)。碎屑颗粒物的吸收光谱同样受浮游植物群落、有机质相对含量等的影响。研究结果表明初级生产产生的微型颗粒有机物是底层水体脱氧的主要底物。 相似文献
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2013年春季崂山湾浮游植物群落及其环境控制 总被引：4，自引：0，他引：4
2013 年春季(3、4、5 月)对崂山湾海域浮游植物群落及其理化环境进行了3 个航次的调查研究。共鉴定浮游植物40 属75 种, 硅藻是调查区主要的浮游植物类群; 浮游植物细胞丰度平均为1.27×106个/m3,3 月份的平均丰度显著高于4、5 月份(P<0.01); 优势种主要为冰河拟星杆藻(Asterionopsis glacialis)、加拉星平藻(Asteroplanus karianus)、密联角毛藻(Chaetoceros densus)和夜光藻(Noctiluca scintillans), 浮游植物群落演替明显, 由3 月份硅藻控制逐步过渡到4、5 月份硅/甲藻共同控制; 相对较低的硝酸盐水平是导致4、5 月份浮游植物丰度显著低于3 月份的主要原因; 物种–环境数据的冗余分析(RDA)结果显示, 温度、硝酸盐含量是控制崂山湾春季浮游植物分布的重要环境因子。 相似文献
6.
为研究沙尘沉降和营养盐输入对中国陆架海域浮游植物群落结构的影响,于2017年3—4月在中国黄、东海进行沙尘和不同营养盐(NO-3、PO-4、尿素)添加的船基围隔培养实验。结果表明,与对照组相比,沙尘(2 mg/L)和尿素添加实验组的浮游植物群落细胞密度及群落结构变化不显著,叶绿素a含量差异不显著,优势种均为海链藻属 (Thalassiosira)。不同比值的氮、磷无机营养盐添加对水体中叶绿素a含量和细胞密度的影响不同,其中氮磷比为64∶1的实验组叶绿素a含量和细胞密度最高,分别为18.20 μg/L和7.86×105cells/L。沙尘和营养盐添加对浮游植物群落的影响主要表现为叶绿素a含量、细胞密度峰值及不同优势种所占比例的差异,而各个实验组的种类组成及优势种具有一定的相似性。 相似文献
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2016年秋季热带西太平洋网采浮游植物群落结构 总被引：1，自引：0，他引：1
作者于2016年9月27日～10月25日对热带西太平洋(0°～20°N, 120°～130°E)10个站位的网采浮游植物群落结构进行了采样调查。应用Uterm?hl方法对调查海域浮游植物的物种组成、细胞丰度、优势物种以及群落多样性等相关生态特征进行了分析。希望为热带西太平洋提供一些基础的背景资料,为以后的研究奠定基础。结果表明, 鉴定出浮游植物共计4门、66属、243种(包括变种、变型), 含硅藻门(Bacillariophyta)34属、103种, 甲藻门(Pyrrophyta)28属、133种, 金藻门(Chrysophyta)2属、4种,蓝藻门(Cyanophyta)2属、3种。浮游植物细胞丰度1 965.573×103 细胞/m3 , 其中蓝藻的细胞丰度为1 945.169×103 细胞/m3 , 决定了浮游植物的分布格局, 占总细胞丰度的98.96%, 高值区分布在0°N130°E-10°N130°E的4个站位(E130-13、E130-15、E130-17、E130-19); 硅藻丰度在20°N断面N20-4站位存在高值区; 甲藻丰度在130°E断面的3个站位(E130-10、E130-13、E130-15)存在高值区。本次调查的优势种依次为铁氏束毛藻(Trichodesmium thiebaultii)、扁形原甲藻(Prorocentrum compressum)、扁豆原甲藻(Prorocentrum leniculatum)、胞内植生藻(Richelia intracellularis)、菱形海线藻(Thalassionema nitzschioides)、细弱海链藻(Thalassiosira subtilis)、具边线形圆筛藻(Coscinodiscus marginato-lineatus)、科氏角藻(Ceratium kofoidii)、鲁比膝沟藻(Gonyaulax lurbynaii)、中华半管藻(Hemiaulus sinensis)、霍氏半管藻(Hemiaulus hauckii)、小等刺硅鞭藻(Dictyocha fibula)。Shannon-Weiner多样性指数的均值为2.440,Pielou 均匀度指数的均值为0.163。相关分析结果显示浮游植物空间分布主要受PO4-P、NH4-N的影响,且由蓝藻的相关性决定的。聚类分析得出群落结构分为大洋群聚和近岸群聚两种类型(其中大洋群聚的站位又划分为0°～10°N纬度范围聚集和10°～20°N纬度范围聚集)。 相似文献
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球形棕囊藻(Phaeocystis globosa)赤潮是一种全球范围的生态灾害,而硝酸盐稳定同位素技术是研究海洋富营养化与赤潮暴发机制的前沿技术。为将该技术应用于球形棕囊藻赤潮暴发机制方面的研究,首先需了解其同化吸收硝酸盐的稳定同位素分馏特征。为此开展了球形棕囊藻室内培养实验,获取培养过程中氮、磷、硅等营养盐的浓度及硝酸盐氮、氧稳定同位素(δ15N-NO3-、δ18O-NO3-)等参数的变化特征,计算球形棕囊藻同化吸收硝酸盐的稳定同位素分馏系数。结果显示,NO3-和PO43-浓度随培养时间均呈现先明显下降后稳定的特征,同时伴随直径2~3mm的囊体出现并生长至2~3cm。NH4+浓度先后两次出现升高,推测可能是受到有机氮矿化过程的补充所致。随NO3-浓度降低,δ15N和δ18O的值分别在第13天和第7天达到相对峰值。经计算,球形棕囊藻同化吸收硝酸盐过程δ15N和δ18O分馏系数分别为3.32‰±0.38‰和3.12‰±0.59‰,而前者的分馏系数呈逐渐降低的特点,原因可能是随球形棕囊藻生长,发生酶还原的NO3-较参与跨膜运输的NO3-比例逐渐升高。研究首次给出了球形棕囊藻同化吸收硝酸盐过程的氮、氧稳定同位素分馏系数及其变化特征,补充了海洋微藻同位素分馏数据库,为稳定同位素技术研究球形棕囊藻赤潮暴发的营养机制提供了重要的基础数据。 相似文献
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Z.-P. Mei L. Legendre J.-. Tremblay L.A. Miller Y. Gratton C. Lovejoy P.L. Yager M. Gosselin 《Deep Sea Research Part I: Oceanographic Research Papers》2005,52(12):2301-2314
The carbon to nitrogen (C:N) stoichiometry of phytoplankton production varied significantly during the spring–summer bloom in the North Water Polynya (NOW), from April through July 1998. The molar ratio of particulate organic carbon (POC) to nitrogen (PON) production by phytoplankton (ΔPOC:ΔPON) increased from 5.8 during April through early June to 8.9 in late June and July. The molar dissolved inorganic carbon (DIC) to nitrate+nitrite (NO3) drawdown ratio (ΔDIC: ΔNO3) increased from 6.7 in April and May, to 11.9 in June (no estimate for July because of ice melting). The discrepancy between ΔPOC:ΔPON and ΔDIC:ΔNO3 was likely due to dissolved organic carbon (DOC) production. Increased ΔPOC:ΔPON of phytoplankton and surface water ΔDIC:ΔNO3 throughout the phytoplankton blooms resulted from changes in physical properties of the upper water column, such as reduced thickness of the surface mixed layer that exposed phytoplankton to increased photosynthetically available radiation (PAR), accompanied by NO3 depletion. This is expected to have significant effects on the cycling of carbon (C) and nitrogen (N) in pelagic ecosystems, as the increased C:N ratio of organic matter decreases its quality as substrate for grazers and microbial communities. Based on ΔPOC:ΔPON, the ratio of POC to chlorophyll a (Chl) production (ΔPOC:ΔChl) and the relationship between Chl yields and NO3 depletion, we estimate that 71±17% and 46±20% of the depleted NO3 went to PON production in the euphotic zone over the polynya from April to early June, and late June to July, respectively. The remaining NO3 was likely channelled to dissolved organic nitrogen (DON) and heterotrophic bacteria, which were not returned to the dissolved inorganic nitrogen (DIN) pool through recycling during the course of the study. Hence, the autotrophic production of organic N and its recycling by the microbial food web were not coupled temporally. 相似文献
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The deficit of 234Th relative to its radioactive parent 238U in the surface ocean can yield reliable estimates of vertical Particulate Organic Carbon (POC) fluxes to deeper waters, but only when coupled with an accurate ratio of POC concentration to activity of 234Th on sinking matter. Assuming a simple partitioning of suspended phytoplankton mass between single cells and flocs, we calculate the ratio of the POC flux estimated from 234Th deficit to the actual POC flux (p ratio, Smith, J.N., Moran, S.B., Speicher, E.A., in press. The p-ratio: a new diagnostic for evaluating the accuracy of upper ocean particulate organic carbon export fluxes estimated from 234Th/238U disequilibrium. Deep-Sea Research I.). The p ratios are calculated under the assumption that particle surface area is correlated with 234Th activity and particle volume is correlated with POC concentration. The value of the p ratio depends on the relative contributions of single cells and flocs to the vertical flux. When large single cells make up a significant fraction of the vertical flux, p ratios are less than one, meaning POC fluxes estimated from 234Th deficits underestimate actual POC fluxes. When large single cells are abundant but do not sink fast enough to contribute to vertical POC flux, p ratios are greater than one (up to 3 × overestimate). Factor analysis of the model indicates that altering the extent of flocculation in suspension and changing the density and maximum size of phytoplankton cells have the greatest effects on the p ratio. Failure to measure the properties of flocs when characterizing the ratio of POC to thorium on sinking matter potentially leads to large overestimation of the POC flux (over 20 ×). Failure to characterize the POC to thorium ratio of large particles, by, for example, destruction of phytoplankton cells in pumps, can lead to underestimation of POC flux. Estimates of POC flux should be most reliable in highly flocculated suspensions populated by small cells and rapidly sinking flocs. These conditions are often associated with intense phytoplankton blooms. 相似文献
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Takeo Hama Shoko Kawashima Koichi Shimotori Yuhi Satoh Yuko Omori Shigeki Wada Taiki Adachi Shun Hasegawa Takashi Midorikawa Masao Ishii Shu Saito Daisuke Sasano Hiroko Endo Tsuyoshi Nakayama Isao Inouye 《Journal of Oceanography》2012,68(1):183-194
The effect of ocean acidification, caused by the increase in pCO2 in seawater, on phytoplankton population and on related organic nitrogen production was experimentally examined by use of a natural coastal microbial population. pCO2 and pH were controlled by aeration with air in which pCO2 was at the current level (control), for which ambient air was used, and with air in which pCO2 was ??800?? and ??1200?? ppm, in 500-L culture vessels. The experiment was continued for 15?days after addition of the inorganic nutrients such as nitrate, phosphate, and silicate. During most of the experimental period, a minor increase in phytoplankton biomass was noted, probably because of low irradiance, an increase in phytoplankton biomass was observed at the end of the experiment. Flow cytometric and microscopic observations revealed that this increase was because of Chrysochromulina sp. (Haptophyceae). The growth of Chrysochromulina sp. was most obvious in the control vessel, and tended to be obscured by increasing pCO2 (decrease in pH), indicating the possibility that ocean acidification inhibits the growth of specific phytoplankton groups, for example Chrysochromulina sp. Production of particulate organic nitrogen (PON), determined by the 15N tracer method, also diminished under acidified conditions compared with that at the current level. 相似文献
14.
东海陆架典型断面颗粒态氨基酸的分布及控制因素分析 总被引：3，自引：1，他引：2
采用高效液相色谱法,通过现场调查对东海典型PN断面(文中为C断面)的颗粒态氨基酸(Particulate Amino Acids,PAA)进行了分析,并结合叶绿素a(Chla)、颗粒有机碳(POC)、颗粒有机氮(PON)及颗粒态氨基酸的构型特征(D和L型)等参数探讨了该区颗粒有机氮的来源和降解情况。结果表明,在长江口最大浑浊带,受咸淡水混合和生物现场生产双重作用影响,POC、PON以及PAA的总浓度均达到了极大值,其中,受再悬浮作用影响,底层水体中的有机物呈现高度降解的状态;近岸水华区域的颗粒态氨基酸则更多来源于现场生产,而且POC/Chla质量比值与降解因子DI值的负相关特征表明冲淡水向海洋输送的过程中,现场生产力对颗粒有机碳的贡献比重逐渐增大,悬浮颗粒物也变得越来越新鲜。值得关注的是,一些D型氨基酸[如D型天冬氨酸(D-Asp),D型丙氨酸(D-Ala)]与细菌生物量之间存在良好的正相关性,暗示颗粒态氨基酸在受到物理水团和生物现场生产作用控制的同时,还受控于微微型浮游生物以及异养细菌。 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(9):1609-1621
We used the nitrogen isotope ratio of algae, suspended particles and nitrate in the water column to track spatial variations in the marine nitrogen cycle in the Mediterranean Sea. Surface PON (5–74 m) was more depleted in 15N in the eastern basin (−0.3±0.5‰) than in the western basin (+2.4±1.4‰), suggesting that nitrogen supplied by biological N2 fixation may be an important source of new nitrogen in the eastern basin, where preformed nitrate from the Atlantic Ocean could have been depleted during its transit eastward. The δ15N of nitrate in the deep Mediterranean (∼3‰ in the western-most Mediterranean and decreasing toward the east) is significantly lower than nitrate at similar depths from the North Atlantic (4.8–5‰), also suggesting an important role for N2 fixation. The eastward decrease in the δ15N of surface PON is greater than the eastward decrease in the δ15N of the subsurface nitrate, implying that the amount of N2 fixation in the eastern Mediterranean is great enough to cause a major divergence in the δ15N of phytoplankton biomass from the δ15N of the nitrate upwelled from below. Variations in productivity associated with frontal processes, including shoaling of the nitracline, did not lead to detectable variations in the δ15N of PON. This indicates that no differential fertilization or productivity gradient occurred in the Almerian/Oran area. Our results are consistent with a lack of gradient in chlorophyll-a (chl-a) and nitrate concentration in the Alboran Sea. 15N enrichment in particles below 500 m depth was detected in the Alboran Sea with respect to surface PON, reaching an average value of +7.4±0.7‰. The δ15N in sinking particles caught at 100 m depth (4.9–5.6‰) was intermediate between suspended surface and suspended deep particles. We found a consistent difference in the isotopic composition of nitrogen in PON compared with that of chlorophyll (Δδ15N[PON-chlorin]=+6.4±1.4‰) in the surface, similar to the offset reported earlier in cultures for cellular N and chl-a. This indicates that δ15N of phytoplankton biomass was retained in surface PON, and that alteration of the isotopic signal of PON at depth was due to heterotrophic activity. 相似文献
16.
Distribution and sinking rates of phytoplankton, detritus, and particulate biogenic silica in the Laptev Sea and Lena River (Arctic Siberia) 总被引：1，自引：0，他引：1
Concentrations and sinking rates of particulate biogenic silica (BSi), chlorophyll a (chl a) and phaeopigments (phae) (< 3 μm, 3–10 μm, > 10 μm and total), as well as the abundances of the major phytoplankton species, were studied during September 1991 in the Eastern Laptev Sea and the lower Lena River (Siberian Arctic). The highest chl a concentrations were found in two major “new” production regimes of the study area: (1) a deep chl a maximum (5.8 mg chl a m−3) (formed by the diatom Chaetoceros socialis) at 30 m depth on the outer shelf of the northern Laptev Sea, and (2) in the Lena River, where the phytoplankton community was dominated by fresh water diatoms (1.5 to 4.5 mg chl a m−3). Elevated chl a concentrations were also found in the river plume phytoplankton community (dominated by brackish water diatoms), NE of the Lena delta. In the Laptev Sea, the low chl a (0.1 to 3 mg chl a m−3) and high phae concentrations (0.5 to 14 mg phae m−3) indicated that the phytoplankton community (dominated by picoplanktic algae and nanoflagellates) was already senescent and affected by grazing losses. Biogenic silica values were highest in the Lena River (4 to 17 μM) as compared to the low values found in the Laptev Sea (0.3 to 4 μM). The large chl a size fraction, phae and BSi in the Lena River samples revealed the highest measured sinking rates (1.4, 2.3, and 1.5 m d−1, respectively). The formation of a strong halocline, decreasing turbulence, and possible nutrient deficiency resulted in death, disintegration and rapid sedimentation of fresh water diatoms. This was accompanied by a decrease in the BSi concentration and growth of the picoplanktic size fraction (< 3 μm) in the estuarine mixing zone (Gulf of Buorkhaya). Only a minor part of BSi was bound to intact diatom cells (< 3%) in the surface layer, most of which being apparently associated with detrital particles. In the Lena River, approximately 12% of the total silica was bound to BSi fraction, yet elsewhere in the Laptev Sea and in the estuarine mixing zone the BSi:total silica ratio was ≤ 5%. Thus, the results reflected the successional stage of a late summer phytoplankton community, characterized by dominance of small autotrophs and patchy distribution of senescent diatoms no longer able to affect the relative high levels of dissolved silica supplied by the Lena River. 相似文献
17.
《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(11-12):2735-2760
An extended time series of particle fluxes at 3800 m was recorded using automated sediment traps moored at Ocean Station Papa (OSP, 50°N, 145°W) in the northeast Pacific Ocean for more than a decade (1982–1993). Time-series observations at 200 and 1000 m, and short-term measurements using surface-tethered free-drifting sediment traps also were made intermittently. We present data for fluxes of total mass (dry weight), particulate organic carbon (POC), particulate organic nitrogen (PON), biogenic Si (BSi), and particulate inorganic carbon (PIC) in calcium carbonate. Mean monthly fluxes at 3800 m showed distinct seasonality with an annual minimum during winter months (December–March), and maximum during summer and fall (April–November). Fluxes of total mass, POC, PIC and BSi showed 4-, 10-, 7- and 5-fold increases between extreme months, respectively. Mean monthly fluxes of PIC often showed two plateaus, one in May–August dominated by <63 μm particles and one in October–November, which was mainly >63 μm particles. Dominant components of the mass flux throughout the year were CaCO3 and opal in equal amounts. The mean annual fluxes at 3800 m were 32±9 g dry weight g m−2 yr−1, 1.1±0.5 g POC m−2 yr−1, 0.15±0.07 g PON m−2 yr−1, 5.9±2.0 g BSi m−2 yr−1 and 1.7±0.6 g PIC m−2 yr−1. These biogenic fluxes clearly decreased with depth, and increased during “warm” years (1983 and 1987) of the El Niño, Southern Oscillation cycle (ENSO). Enhancement of annual mass flux rates to 3800 m was 49% in 1983 and 36% in 1987 above the decadal average, and was especially rich in biogenic Si. Biological events allowed estimates of sinking rates of detritus that range from 175 to 300 m d−1, and demonstrate that, during periods of high productivity, particles sink quickly to deep ocean with less loss of organic components. Average POC flux into the deep ocean approximated the “canonical” 1% of the surface primary production. 相似文献
18.
Takeshi Yoshimura Koji Suzuki Hiroshi Kiyosawa Tsuneo Ono Hiroshi Hattori Kenshi Kuma Jun Nishioka 《Journal of Oceanography》2013,69(5):601-618
Response of phytoplankton to increasing CO2 in seawater in terms of physiology and ecology is key to predicting changes in marine ecosystems. However, responses of natural plankton communities especially in the open ocean to higher CO2 levels have not been fully examined. We conducted CO2 manipulation experiments in the Bering Sea and the central subarctic Pacific, known as high nutrient and low chlorophyll regions, in summer 2007 to investigate the response of organic matter production in iron-deficient plankton communities to CO2 increases. During the 14-day incubations of surface waters with natural plankton assemblages in microcosms under multiple pCO2 levels, the dynamics of particulate organic carbon (POC) and nitrogen (PN), and dissolved organic carbon (DOC) and phosphorus (DOP) were examined with the plankton community compositions. In the Bering site, net production of POC, PN, and DOP relative to net chlorophyll-a production decreased with increasing pCO2. While net produced POC:PN did not show any CO2-related variations, net produced DOC:DOP increased with increasing pCO2. On the other hand, no apparent trends for these parameters were observed in the Pacific site. The contrasting results observed were probably due to the different plankton community compositions between the two sites, with plankton biomass dominated by large-sized diatoms in the Bering Sea versus ultra-eukaryotes in the Pacific Ocean. We conclude that the quantity and quality of the production of particulate and dissolved organic matter may be altered under future elevated CO2 environments in some iron-deficient ecosystems, while the impacts may be negligible in some systems. 相似文献
19.
Y. Feng C.E. Hare J.M. Rose S.M. Handy G.R. DiTullio P.A. Lee W.O. Smith J. Peloquin S. Tozzi J. Sun Y. Zhang R.B. Dunbar M.C. Long B. Sohst M. Lohan D.A. Hutchins 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(3):368-383
We conducted a factorial shipboard continuous culture experiment to examine the interactive effects of altered iron, irradiance and CO2 on the summer phytoplankton community of the Ross Sea, Antarctica. After 18 days of continuous incubation, iron enrichment increased phytoplankton biomass, nutrient drawdown, diatom and Phaeocystis abundance, and some photosynthetic parameters. High irradiance significantly increased the number of Phaeocystis antarctica colonies, as well as P. antarctica abundance relative to diatoms. Iron and light had significant interactive effects on diatom and P. antarctica pigment concentrations, P. antarctica colony abundance, and Si:N, Si:C, and N:P ratios. The major influence of high CO2 was on diatom community structure, by favoring the large centric diatom Chaetoceros lineola over the small pennate species Cylindrotheca closterium. The ratio of centric to pennate diatoms was significantly responsive to changes in all three variables individually, and to all of their possible two- and three-way combinations. These results suggest that shifts in light, iron, and CO2 and their mutual interactions all play a role in controlling present day Ross Sea plankton community structure, and need to be considered when predicting the possible future responses of biology and biogeochemistry in this region. 相似文献
20.
渤海颗粒有机碳与生物硅的分布及来源 总被引：2，自引：1，他引：1
海洋碳、硅循环及其相关联的生物地球化学过程是全球环境变化的热点问题,也是海洋科学关心的重要领域。利用2012年5月和11月份对渤海海域的调查结果,对该海域颗粒有机碳和生物硅的分布特征及来源进行了讨论。主要结论为:渤海有机碳以溶解有机碳为主,具有春季高和秋季低的特征;由陆地来源和海洋自生的有机碳组成,且以海洋来源的有机碳为主。渤海生物硅分布具有明显的梯度特征,河流输入同样对其含量的影响较为突出。渤海沉积物中生物硅含量较高,明显高于中国东部陆架海。渤海表层沉积物中生物硅主要是海源的,依次由浮游藻类、植硅体和海绵骨针所构成,其中浮游藻类占62.9%,陆源植硅体占31.1%。渤海沉积物发现了来自于草本植物的植硅体,这说明了陆地产生的植硅体对海洋生物硅的贡献。 相似文献