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1.
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   

2.
杨海丽  郑玉龙 《海洋学报》2008,30(4):95-103
2005年8月在海南洋浦湾内湾取得1根柱状样,在铅-210定年的基础上分析沉积物粒度、总有机碳含量及其同位素值(δ13C)、总氮含量及其同位素值(δ15N)、生物硅含量、重金属(镍、镉、铬、铜、锌、铅)含量及有机氯农药(六六六、滴滴涕)含量等参数发现,111cm至表层,沉积物中有机碳、总氮、生物硅含量升高,特别是从45cm至表层,它们的含量明显增加,说明该湾内有富营养化趋势。由有机碳与总氮的原子比和有机碳同位素指示的物源信息可知,该湾内有机质来源为藻类和陆源脉管植物的混合,且以陆源输入为主。陆源有机碳含量与总有机碳含量的相关系数为0.917。自23cm至表层有机碳同位素明显偏轻,氮同位素偏重。从111cm至表层,重金属和有机氯农药含量升高。综合分析各环境指标可知,洋浦湾近百年来环境演变可分为三个时期,即20世纪70年代以前、70年代至90年代、90年代至21世纪初,洋浦湾经历了未污染期、轻度污染期、显著污染期。  相似文献   

3.
北极快速变化的生态环境响应   总被引:1,自引:0,他引:1  
北冰洋由于其特殊的地理位置,成为全球变化响应最为敏感的地区。本文聚焦北极海冰变化幅度最大的西北冰洋,从营养盐、叶绿素、浮游植物群落和沉积碳埋藏等变化来讨论海洋生态环境对北极快速变化的响应。尽管太平洋北向流和北极周边河流输入加强可以增加西北冰洋上层营养盐储库,但由于夏季硅藻旺发向沉积物迁出大量生源元素,使得上层营养盐相对亏损,部分海域存在显著的氮限制和硅限制。随海冰减退,尽管夏末海盆区浮游植物呈现小型化趋势,但西北冰洋总体上浮游植物现存量和初级生产力呈现增高的趋势;伴随叶绿素极大层下移、北扩,以硅藻为代表的生物泵过程得以更高效的运转。在沉积物埋藏的有机碳中,除原先北冰洋生态系统占据重要比份的冰藻外,硅藻等藻类的有机碳埋藏也逐渐增加。西北冰洋海洋初级生产力的增加不仅促进了生物泵的运转和碳的埋藏,而且给海洋生态系统提供了更多的食物来源。北极海域目前已成为全球碳源汇格局变化最大、海洋生态系统改变最显著的地区之一。  相似文献   

4.
渤海中南部沉积物中生源要素的分布特征   总被引:3,自引:0,他引:3  
从化学结合形式出发,对渤海中南部海区沉积物中OC、N、P、BSi等生源要素的含量进行调查分析,讨论了各生源要素的分布及其影响因素。结果表明:受陆源输入的影响,表层沉积物中各形态氮、磷及有机碳均呈现"近岸高,远岸低"的分布趋势,生物硅的含量分布则与海区浮游硅藻的分布趋势相一致;可交换态氮是总氮中较活跃的部分,占总氮的比例约为3.7%;固定态铵是总氮的主要组成部分,约占总氮的38.4%,其主要与有机质含量及黏土矿物组成有关;渤海表层沉积物中OC/BSi、ON/BSi以及OP/BSi的比值分别为2.38、0.19、0.03,低于Redfield比值,说明有机质优先于生物硅分解;OC/ON平均值在6.0~14.0之间,判断渤海沉积物中有机质受陆源输入和海洋自生共同影响;其中,有机碳主要以陆源输入为主,而有机氮在沉积物表层主要以陆源输入为主,在沉积物下层则主要来源于海洋自生。  相似文献   

5.
为了解南海北部末次间冰期以来的沉积环境演化,分析了西沙海槽83PC柱状沉积物的浮游有孔虫氧碳同位素、碳酸钙、有机碳和粒度组成。浮游有孔虫的δ18 O值具有冰期-间冰期旋回特征,记录了海平面的升降和古气候的变化,而海平面变化控制了沉积物的碳酸钙和有机碳含量。冰期,海平面下降,陆源物质输入增多,带来了大量的碎屑物质和陆源有机质,沉积物具有低碳酸钙含量和高有机碳含量;间冰期,海平面上升,陆源物质输入减少,碎屑物质的稀释作用减弱,沉积物具有高碳酸钙含量和低有机碳含量。南海北部83PC柱状沉积物记录了末次间冰期以来的多次海平面升降旋回,还记录了气候变冷事件以及低碳酸钙沉积事件,其中,150、510、660和740cm处的低碳酸钙含量和相对重δ18 O值记录了全球性气候变冷事件,而冰后期的低碳酸钙沉积事件,则主要反映了季风降雨的增强,出现了洪水高发期,陆源碎屑物质对碳酸钙沉积的稀释作用明显增强。  相似文献   

6.
从20世纪80年代以来古生产力的重建研究一直是国内外海洋生态学研究的热点,但已有的大多数研究是在深海区;而陆架区的特点是来自陆源物质的影响往往比较明显,因此,研究难度远较深海区大。利用现代沉积物中的有机碳稳定同位素组成来估算海源碳的含量,在此基础上,结合调查区域表层沉积物中的几个初级生产力的代表性指标(浮游植物总量、叶绿素a浓度以及硅藻含量)的调查资料,寻求岩心中海源碳与古生产力指标的相关关系,再由南黄海冷涡沉积区3个典型柱状沉积物中海源碳重建了200a以来高分辨率的古生产力记录,这对陆架海生态环境演变规律的研究有重要意义。对重建所得到的南黄海近代初级生产演化因素的初步探讨表明,近200a来初级生产力波动升高与海水表层温度的升高趋势是一致的,但其最主要的控制因素还是营养盐的供应,其中陆源营养物质和污染物质的影响起到了重要的作用。  相似文献   

7.
通过对楚科奇海及邻近的北冰洋深水区表层沉积物中有机碳同位素含量(δ13C)、氮同位素含量(δ15N)及生物成因SiO2(BSiO2)含量分析,结果表明海源和陆源有机质的分布受海区环流结构和营养盐结构所制约.楚科奇海中西部和楚科奇海台受太平洋富营养盐海水的影响,海洋生产力高,沉积物中海源有机质和BSiO2含量高;靠阿拉斯加一侧海域海水的营养盐含量和生产力都偏低,沉积物中陆源有机质比重增加;在研究区北部和东北部的楚科奇高地和加拿大海盆,冰封时间较长,营养盐供应少,海洋生产力低,但来自马更些河和阿拉斯加北部的陆源有机质增多,沉积物中BSiO2含量小于5%,海源有机质百分含量小于40%.由于亚北极太平洋水通过楚科奇海向北冰洋海盆输送,研究区营养盐池表现为开放系统,营养盐的利用率与它的供应成反比,与海洋生产力成反比.  相似文献   

8.
南沙海洋柱状沉积物的有机地球化学研究   总被引:7,自引:1,他引:6  
段毅  徐雁前 《海洋通报》1996,15(4):42-48
研究了南沙海域NS90-103柱样有机碳含量,各类生物标志化合物的组成和分布及其地球化学意义。结果表明,该柱样中有机碳含量高于南沙海域其他沉积环境,这表明南沙海域中大陆坡最适合于有机质的聚集。各类生物标志化合物组成和分布指示了沉积有机质主要起源于海洋浮游生牧细菌,其次为陆源高等植物,气溶胶输入可能是后者来源的途径之一;沉积环境具有强原还性;有机质处于未成熟阶段,并存在较好的成岩变化。  相似文献   

9.
对2003年7月至9月采自北极楚科奇海域的4个站位表层沉积物及1个站位的柱状沉积物样品的总糖、总碳、有机碳、无机碳、总氮、总磷的含量进行了测定,并对其有机碳和有机氮同位素(1δ3C和1δ5N)的变化进行了研究,结果表明:北极楚科奇海域沉积物中的总糖与有机碳为明显的正相关关系,说明糖类是有机碳重要的组成部分;表层沉积物中TOC/TN平均值为9.273,1δ3C和1δ5N的平均值分别为-21.61‰和7.1‰,显示出表层沉积物中糖类物质以海洋藻类来源为主、混入部分陆源物质的分布特征;柱状样品不同深度沉积物中TOC/TN平均值为13.45,也反映出糖类物质为海洋自生和陆源输入共存的分布特征。  相似文献   

10.
为了探讨长江口水体胶体有机碳含量的季节变化, 按季度采集长江口南支表层水样, 利用切向流超滤技术(TFF)分离水样中小胶体物质(1—5kD)、中胶体物质(5—500kD)和大胶体物质(500kD— 0.45μm), 测试分离后样品的有机碳浓度。结果表明: 长江口水体中总胶体有机碳浓度有明显的季节变化, 表现为冬季>夏季>秋季>春季, 其原因可能是冬季长江流域陆源输入增加, 水生生物生物量和生物活性减弱双方面的共同作用使得含量最高, 而春季流域陆源有机碳含量输入较少, 且流域内春汛雨量多水量大对水体中有机碳浓度具有稀释作用, 从而导致该季节胶体有机碳含量较少。总胶体有机碳在不同分子量的分配上季节差异不大, 中胶体有机碳浓度及其在总胶体有机碳中所占的比例均高于小胶体有机碳和大胶体有机碳。由于长江口胶体有机碳的含量较高, 并有明显的季节变化, 对有机碳的入海通量和生物地球化学循环发挥重要的作用。  相似文献   

11.
Total organic carbon and organic carbon stable isotope, biogenic silica, chlorin were measured from a high resolution sediment core to indicate the variation in paleoproductivity and the environmental implications over the past decades (1942 to 1997) in the Changjiang Estuary. Based on these biomarkers, the shift in the phytoplankton community structure in the past decades was discussed in response to the long-term variations in nutrient concentrations and nutrient ratios. The results showed that the δ 13 C values varied from –26.15‰ to –19.5‰, suggesting the combined organic carbon sources of riverine and marine organisms. Based on the biogenic proxies, paleoproductivity changes were categorized into three stages: low production before 1950; an increase in production with the dominance of diatoms during 1950 to 1980, consistent with increasing of nutrient concentrations; a decrease in production after 1980 when the diatom production decreased while the production of non-silicious phytoplankton increased due to high nutrient inputs, and high N/P and P/Si ratios in the Changjiang Estuary. The sedimentation records also indicated that the riverine organic carbon increased since 1980.  相似文献   

12.
长江口沉积记录反映的近80年陆源输入和营养盐变化特征   总被引:1,自引:1,他引:0  
A variety of environmental problems have been observed in the Changjiang River Estuary and adjacent coastal area, including eutrophication, harmful algal blooms (HABs), and hypoxia in recent decades. A...  相似文献   

13.
The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon (TOC), total nitrogen (TN), biogenic silica (BSi) and stable organic carbon isotopic ratios(δ13 Corg) were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation (TOC, TN and BSi) was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.  相似文献   

14.
Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores(#34: 28.5°N, 122.272°E; CJ12-1269: 28.861 9°N, 122.515 3°E) from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B(dinosterol/brassicasterol) ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.  相似文献   

15.
近50年长江口的主要有机污染的记录   总被引:4,自引:0,他引:4  
本文通过近50年来我国长江口及长江流域有机物污染物的研究记录和成果和国内外其它重要河口海域的资料进行对比分析,认为人类近50年的活动对长江口已造成了比较严重的有机污染。本世纪初长江干流中检出的有机污染物达308种。从上世纪50年代到80年代初长江口的有机氯农药污染呈逐年上升趋势,之后开始下降,但至今还对生态系统造成影响。同时,与上世纪80年代相比,上个世纪90年代长江口的多氯联苯(PCBs)污染要来得重。在上世纪50年代和60年代在我国沿海均已出现油污染,并在上世纪90年左右最为严重,虽然从上世纪90年代中期开始呈下降趋势。长江口多环环芳烃(PAHs)污染在上世纪70年代很少,但随着长江流域工业的发展,从上世纪80年代开始加重,到上世纪90年代中期才开始下降。  相似文献   

16.
过去几十年来全球近海有害藻华(又称赤潮)发生频率持续增加。人类活动造成的河口-近海富营养化程度的加剧,被认为是导致全球有害藻华增加的主要原因。但是,富营养化程度的加剧可能不是全球有害藻华增加的惟一原因。河流入海的非营养盐类的其他物质通量变异(如泥沙),也可能显著影响河口-近海的生物活动乃至赤潮的发生。过去40年来随着长江入海营养盐通量的增加,长江入海泥沙通量减少了70%。长期观测资料显示,由于泥沙减少使得长江口羽状流区光照条件显著改善,长江口浮游植物生物量最大值区已扩展至更低盐度的区域。此外,过去40年来长江口赤潮发生频率变化与长江入海泥沙通量变化呈现镜像关系,且二者呈显著的负相关关系。因此认为,长江入海泥沙的剧烈减少降低了羽状流区水体浊度,从而对长江口区赤潮频率的增加有一定贡献。  相似文献   

17.
Four cruises were conducted during 2002--2003 in the Changjiang Estuary and adjacent coastal areas. The data presented show a clear coast to open sea gradient in nutrients related to the river inputs. Maximum values of chlorophyll a were typically observed at intermediate salinities at surface water and coincided with non-conservative decreases in nutrients along the salinity gradient, indicating that removal of nutrients was related to phytoplankton uptake. The seasonal variations of nutrient concentrations were just opposite to those of chlorophyll a, indicating that the seasonal variations of nutrients were mainly controlled by phytoplankton uptake, whereas riverine inputs merely weakened or balanced its extent. During the estuarine mixing, phosphate demonstrated some remobilization during all the four cruises; whereas both conservative and non-conservative behaviors for dissolved inorganic nitrogen and silicate were observed in the study area, indicating that both biotic and abiotic events may affect their behaviors during the estuarine mixing. Under the influence of freshwater inputs with high value of ratio of nitrogen to phosphorus, the estuarine and coastal waters impacted by the Changjiang plume were high ( 〉 30) in ratio of nitrogen to phosphorus, but rates of primary production were apparently not constrained by any kind of nutrient elements. However, the low ( 〈 1 ) ratio of silicate to nitrogen in most of the study area might be linked with the rapidly increasing frequency of harmful algal bloom (HAB) incidents in recent years in the coastal waters impacted by the Changjiang plume.  相似文献   

18.
Phosphate limitation of phytoplankton growth in the Changjiang Estuary   总被引:3,自引:1,他引:2  
Laboratory experiments of bioassay with Pltaeodaetytum tricornutum, Chatoceros didymus, Chaetoreros calcitraus and Heterogtoea sp. sampled from the Changjiang Estuary in spring and summer, 1986, indicated that both N and P limit phytoplankton growth in the medium with N : P ranged between 8-30, and N limits phytoplankton production in the medium with N: P<8, while P is the limitary nutrient in the N : P>30. Generally, N : P in the Changjiang Estuary waters is 2 times higher than Redfield ratio. The bioassay experiments with high N : P water samples collected from Changjiang Estuary show that phytoplankton production is limited by P. Phytopiankton appears to give priority to the uptake of P at all periods of time. And the optimum N:P for phytoplankton growth is determined to be 18.  相似文献   

19.
Water and sediment samples were collected at Datong from June 1998 to March 1999 to examine seasonal changes in the transports of nitrogen (N) and phosphorus (P) from the Changjiang River (Yangtze River) to the East China Sea (ECS). Dissolved inorganic nitrogen (DIN; dominated by nitrate) concentration exhibited small seasonality, and DIN flux was largely controlled by water discharge. Dissolved inorganic phosphorus (DIP) concentration was inversely correlated with water discharge, and DIP was evenly delivered throughout a year. The transports of DIN and DIP from the Changjiang River were consistent with seasonal changes in nutrient distributions and P limitation in the Changjiang Estuary and the adjacent ECS. Dissolved organic and particulate N (DON and PN) and P (DOP and PP) varied parallel to water discharge, and were dominantly transported during a summer flood. The fluxes of DOP and particulate bioavailable P (PBAP) were 2.5 and 4 times that of DIP during this period, respectively. PBAP accounted for 12–16% of total particulate P (PP), and was positively correlated with the summation of adsorbed P, Al–P and Fe–P. Ca–P, the major fraction of PP, increased with increasing percent of CaCO3. The remobilization of riverine DOP and PBAP likely accounted for the summer elevated primary production in DIP-depleted waters in the Changjiang Estuary and the adjacent ECS. The Changjiang River delivered approximately 6% of DIN (1459 × 106 kg), 1% of DIP (12 × 106 kg), and 2% of dissolved organic and particulate N and P to the totals of global rivers. The construction of the Three Gorges Dam might have substantially reduced the particulate nutrient loads, thereby augmenting P limitation in the Changjiang Estuary and ECS.  相似文献   

20.
利用分级浸取分离法将黄海、东海陆架区沉积物氮分为转化态氮(TF-N)和非转化态氮,并将可转化态氮区分为4种形态:离子交换态氮IEF-N 、碳酸盐结合态氮CF-N 、铁锰氧化态氮IMOF-N及有机态和硫化物结合态氮OSF-N。 对各形态氮的平面、垂直和沉积剖面年际分布进行了分析,并进一步探讨了该区域氮形态与古生产力的替代指标——生物硅(BSi)的相关性,揭示了氮形态的地球化学特征及与浮游植物总量的关系。结果表明,黄海、东海陆架区表层沉积物中可转化态氮占总氮的百分比为16.81%,可转化态氮中4种形态氮的平均含量为:IMOF-N(66.65 μg/g)>IEF-N(22.96 μg/g)>OSF-N(17.40 μg/g)>CF-N(11.26 μg/g),IMOF-N是可转化态氮的优势形态;柱状沉积物中各形态氮垂直分布不同,长江口沉积物中各形态氮垂向变化幅度大于南黄海中部;离子交换态氮IEF-N和铁锰氧化态氮IMOF-N对浮游植物总量贡献较大。  相似文献   

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