利用稳定同位素(15N)示踪技术研究浮游藻类氮素吸收速率特征     

韩菲尔  赵中华  李大鹏  张路 《海洋与湖沼》2019,50(4):811-821

浮游藻类对溶解态氮的吸收同化是湖泊氮生物循环和水体富营养化发生机制探讨的关键环节。本文通过~(15)N稳定同位素添加实验以铜绿微囊藻(Microcystis aeruginosa)、海链藻(Thalassiosira sp.)、卡德藻(Tetraselmis sp.)、剧毒卡尔藻(Karlodinium veneficum)以及盐水隐藻(Rhodomonas salina)为研究对象,从浮游藻类氮素吸收时间、营养盐基质以及藻种差异三个方面研究五种藻类对铵氮(NH_4~+-N)、硝氮(NO_3~--N)、尿素氮(Urea-N)三种形态氮的吸收特征。研究发现:(1)浮游藻类对三种形态氮的吸收均在1h时吸收速率最高,其氮素吸收过程为快速吸收。(2)浮游藻类优先吸收还原态氮,其中NH_4~+-N吸收速率最高,当培养周期为1d和4d时浮游藻类对NH_4~+-N吸收速率的均值分别为4.05和4.15μmol/(L·h);浮游藻类对Urea-N吸收相对偏好系数为25.18—713.42,表现出对小分子溶解态有机氮的特定偏好性。(3)不同藻种对氮素吸收具有不同特征,其中,剧毒卡尔藻对三种形态氮的吸收速率均为最高,而铜绿微囊藻的吸收速率均为最低;不同藻种不同培养时间氮素吸收速率差异与浮游藻类生长周期等特性有关。不同浮游藻类对不同形态氮素表现出吸收特异性,对水体氮负荷和浮游藻类水华优势种形成将产生重要影响。  相似文献   

Bathymetry,substrate and fishing areas of Southeast Atlantic high-seas seamounts   总被引：1，自引：0，他引：1  

OA Bergstad  ÅS Høines  R Sarralde  G Campanis  M Gil  F Ramil 《African Journal of Marine Science》2019,41(1):11-28

Most of the Southeast Atlantic Ocean is abyssal, and global bathymetries suggest that only ～3.2% of the areas beyond national jurisdiction (ABNJ; also known as the high seas, as defined in the United Nations Convention on the Law of the Sea [UNCLOS]) are shallower than 2 500 m. This study mapped bathymetry and characterised substrates in selected seamount summit areas, including several that have been or may become fishing areas. The southernmost location, the Schmitt-Ott Seamount, has exposed volcanic bedrock with surrounding flats covered by thin biogenic sediments and/or coral rubble that appears ancient. At Wüst, Vema, Valdivia and Ewing seamounts the basaltic base appears to be overlain by coral caps and other coral substrates (sheets, rubble). Adjacent summit plains have biogenic sediments of varying thickness. Vema has a flat, roughly circular summit, <100 m deep, with the shallowest point being a 22-m-deep summit knoll; the upper slopes have ancient coral framework, but the summit has a mixture of coralline and volcanic rock and coarse sediments, including extensive areas with coralline algae and kelp forests. Valdivia Bank is a 230-m-deep, flat, rocky area (～11 × 5 km), protruding steeply from the extensive multi-summit Valdivia subarea of the Walvis Ridge. The distribution of past fisheries in the Convention Area of the South East Atlantic Fisheries Organisation (SEAFO) was considered in relation to the new information on bathymetry and substrate.  相似文献   

新元古代末期高家山生物群的生态多样性     

华洪  蔡耀平  闵筱  柴姝  代乔坤  崔再航 《地学前缘》2020,27(6):28-46

新元古代末期是生命演化的关键转折期,也是以微生物占主导的生态系统向显生宙以后生动物占主导的生态系统的转变期,埃迪卡拉纪大型软躯体生物以固着、底栖、食悬浮为特色,普遍缺乏运动能力。作为这一时期特殊代表的高家山生物群,是目前新元古代唯一一个以黄铁矿化三维保存的管状和锥管状化石为主导,兼有骨骼生物、原生动物、钙化蓝细菌类及遗迹化石的多门类生物组合,是研究埃迪卡拉纪末期生命演化和生态系统演变十分重要的载体。本文通过对高家山生物群古生态学的初步研究,揭示出在前寒武纪—寒武纪之交,生态系统已显示一定的多样性。为适应平底面上(level-bottom)微生物席的发育,高家山生物群的许多生物采取了适应性的生存策略,通过黏附或插入微生物席中,营底栖固着食悬浮(如Cloudina、Conotubus)或化学共生(可能的Shaanxilithes)或平躺(如Gaojiashania和Sinotubulites)食碎屑生活。底内遗迹化石表明存在可能的表栖和半内栖、可自由运动、食碎屑的造迹生物。Conotubus中常见的“回春”或“复苏”现象,Gaojiashania和Sinotubulites的身体扭转或生活姿态调整则是对频繁风暴事件的被动适应。  相似文献   

准噶尔盆地玛湖凹陷风城组页岩自生长英质矿物的成因机理及其储层改造意义     

郭佩  柏淑英  李长志  雷海艳  徐文礼  张锡婷  文华国 《地质学报》2023,97(7):2311-2331

玛湖凹陷二叠系风城组是近几年准噶尔盆地页岩油接替的主攻领域,但其页岩成岩改造强烈,原始岩性归属尚不明确。X射线粉晶衍射测得风城组页岩黏土矿物含量普遍较低（<10%）,长英质矿物含量较高（60%~80%）。薄片分析发现风城组长英质页岩存在三种类型：① 粉砂级（4~63 μm）长石和石英碎屑含量丰富,为典型的粉砂岩;② 燧石条带和团块发育,为富硅页岩;③ 长英质基质发育,呈非碎屑状,且火山尘及火山玻璃少见,其矿物组成和形态与典型的黏土岩、粉砂岩及沉凝灰岩明显不同。背散射图像和高精度扫描电镜测得该长英质基质由碎屑和自生石英、钾长石和钠长石共同组成,可见黏土矿物、碎屑钾长石和钠长石向自生石英转化,碎屑钾长石向自生钠长石转化。通过调研全球中新生代碱湖沉积中自生硅酸盐矿物组合特征和成岩演化规律,探讨了二叠系风城组“贫”黏土矿物和“富”自生长英质矿物的原因,并提出风城组发育一类“改造长英质页岩”,主要由原始黏土和长石碎屑矿物和火山物质经过多期成岩改造而成。早期高碱（pH>9）沉积和成岩环境增加了SiO2溶解度和元素铝的活性,导致黏土矿物、泥级—细粉砂级长英质碎屑、火山灰等在入湖后发生“溶解、转化”,形成次稳定的硅酸盐矿物,如沸石和含镁蒙皂石,在经历漫长埋藏成岩后进一步转化为更为稳定的石英、钾长石和钠长石。碱湖页岩的成岩改造过程消耗了黏土矿物和火山灰,极大增加了页岩脆性,同时伴生了大量基质溶孔和晶间孔,是一类优质的页岩储层。  相似文献   

Variation of bacteria biomass and its possible controlling factors in the East China Sea     

Wenjuan Xia  Jiangtao Wang  Liju Tan  Qiulu Wang 《中国海洋大学学报(英文版)》2011,10(2):135-141

Two surveys were performed for determining bacteria biomass (BB), temperature, salinity, chlorophyll a (chl-a) and nutrient concentrations at 11 stations with three sampling depths in the high-incidence regions of red tide in the East China Sea (ECS) in the spring of 2006. Temperature and salinity increased from nearshore to offshore region and from high latitude to low latitude in the two cruises of 2006. BB were between 0.3–5.2 mgC m⁻³ (about 2.1 mgC m⁻³ on average) and 0.2–6.0 mgC m⁻³ (about 2.7 mgC m⁻³ on average) respectively in the two cruises. BB in the surface layer decreased from the Changjiang River estuary to high sea and from low latitude to high latitude. The results showed that bacterial growth was regulated by temperature, primary production and inorganic nutrient concentrations depending on different hydrographic conditions. In the surface and middle layers where the primary production can supply enough organic substrate, temperature was the main factor to control bacteria biomass. BB showed a good correlation between the surface and middle layers in both cruises. The distribution of nutrients during both cruises showed a similar decreasing trend from nearshore region and high latitude to offshore region and low latitude. High BB values were mainly recorded from samples in the middle layer where chl-a concentrations were also high, indicating primary production being strongly correlated with temperature over the ECS shelf. In the offshore area, phosphate and silicate became limiting factors for phytoplankton growth with indirect influence on BB. Bacteria played an important role in nitrogen regeneration process turning organic nitrogen to inorganic forms such as NH₄ ⁺. The increasing ratio of NH₄ ⁺/DIN could be a proof of that.  相似文献   

Effects of sand grain size and morphological traits on running speed of toad-headed lizard Phrynocephalus frontalis     

C. LiX. Lian  J. BiH. Fang  T.L. MaulZ. Jiang 《Journal of Arid Environments》2011,75(11):1038-1042

We conducted a manipulative experiment to investigate the influential factors of locomotor ability in steppe toad-headed lizards. By using a video-base method, we measured running speed of the lizards when they run on sands of different grain sizes. We also considered body condition, tail length and sex as fixed factors to analyze their effects on running speed of the lizard. Results showed that running speed of the lizard significantly differed among different trials of sand grain size. Specifically, the peak and the nadir values of the running speed were found on sands of 0.5-1 mm and 0.075-0.25 mm grains, respectively. When lizards ran on sands of different grain size their running speed changed significantly. Body condition and tail length also had significant effects on running speed. The findings indicated that locomotor ability of lizards depended on both body condition and the external environment. We hypothesized that sand grain size is one of the factors that influence the habitat selection in steppe toad-headed lizards. Moreover, this lizard may be used as an indicator of the development of sand dunes.  相似文献   

单体褶牡蛎(Crassostrea sp.)的研究     

王昭萍  王如才  徐从先  仇宝志  姜福正  张祝绪 《中国海洋大学学报(自然科学版)》1992,(2)

采用肾上腺素(EPI)和去甲肾上腺素(NE)诱导、颗粒固着基和先固着后脱基三种方法,对褶牡蛎的眼点幼虫进行处理,产生单体蛎苗。EPI和NE诱导的最适浓度为10~(-4)M,最适处理时间为3h,幼虫的不固着变态率分别达47.7％和46.6％。处理时间延长,变态率增加不明显。EPI和NE的诱导效果差别不明显,其诱导作用对稚贝的生长无明显副作用。颗粒固着基以贝壳粉为佳,最适颗粒的规格为幼虫的壳长。幼虫先固着后脱基而形成单体蛎苗,以可弯曲的灰色塑料板效果最好,固着的小贝可通过来回弯曲塑料板而从上面脱落下来,小贝长至1～2cm大小时,脱基最容易。  相似文献   

海山铁锰结壳基岩岩石学特征及其生长关系   总被引：2，自引：0，他引：2  

张丽洁  姚德 《海洋地质与第四纪地质》2002,22(2):49-56

为了研究海山铁锰结壳基岩类型与结壳壳层生长的关系。对麦哲伦海山及中太平洋海山区取得的铁锰结壳及其基岩样品在电子显微镜下进行了观察和研究。结果表明，上述2个区域基岩岩石类型主要有玄武岩，火山熔岩，火山碎屑岩，硅质岩和碳酸盐岩，其中麦哲伦海山玄武岩为块状构造，中太平洋海山玄武岩则主要为气孔-杏仁状构造，多发生蚀变或完全蚀变，硅质岩颗粒物质主要是硅藻，碳酸盐岩则以晶质灰岩为主，结壳壳层厚度在各类基岩类型上都有变化，以在玄武岩和碳酸盐岩上变化最大。  相似文献   

Long-term effects of a toxic algal bloom on subtidal soft-sediment macroinvertebrate communities in Wellington Harbour, New Zealand   总被引：2，自引：1，他引：2  

Kerstin Krger  Jonathan P.A. Gardner  Ashley A. Rowden  Robert G. Wear 《Estuarine, Coastal and Shelf Science》2006,67(4):589-604

The long-term effects (>1 year) of a naturally occurring toxic plankton bloom (Karenia brevisulcata) on subtidal benthic macroinvertebrate communities were investigated in Wellington Harbour, a semi-enclosed temperate embayment in New Zealand. For 3 years communities were sampled at three different sites in the harbour. Analyses revealed that community recovery following the bloom was site-specific. Multivariate analyses indicated that at one site community composition was approaching recovery 3 years post-bloom. At the second site, a sequential recovery process was indicated, whereas at the third site the community composition oscillated from year to year, but did not show any signs of a sequential recovery process. The nature of the hydrodynamic regime was identified as a major factor influencing the observed recovery processes. Communities exposed to an active hydrodynamic regime were less affected by the bloom and differed little in their composition pre- and post-bloom, as they were naturally in a perpetual state of recovery as indicated by a dominance of r-selected species. The community at the hydrodynamically less active site was more affected by the bloom and exhibited temporal differences in composition consistent with successional models. Complete recovery to a pre-disturbance climax community dominated by K-selected species is likely to take 4–5 years, if not interrupted by other disturbances. Given the increased occurrence of harmful algal blooms worldwide, more monitoring and manipulative studies are needed to further evaluate the effects of such disturbances on macrobenthic communities.  相似文献   

Inhomogeneous substrate analysis using EM300 backscatter imagery   总被引：2，自引：0，他引：2  

Yves Le Gonidec  Geoffroy Lamarche  Ian C. Wright 《Marine Geophysical Researches》2003,24(3-4):311-327

Backscatter reflectivity from multibeam echo-sounders provides a powerful tool to efficiently characterize seafloor substrates. A comprehensive EM300 bathymetric and backscatter survey has been completed of Cook Strait, in central New Zealand. This paper presents a detailed analysis of the realtime corrections applied to the raw EM300 multibeam data and additional corrections required to compute angular variations of the backscatter strength. The corrections, including the local absorption coefficient, the influence of seafloor topography and sound refraction in the water column, are determined for different Cook Strait seafloor substrates. Modifying MB-System software code, we extracted the backscatter signal parameters in order to quantify the raw backscatter strength and apply additional processing. Profiles of backscatter strength versus incidence angle were computed for a variety of sites characterized by flat seafloor and homogeneous substrates, and for which ground-truth data were available. For each homogeneous site, different but characteristic backscatter profiles are observed that can be interpreted in terms of sediment facies. To analyze heterogeneous substrates, we present a statistical technique, based on a 3-dimensional distribution of (incidence angle, backscatter strength) couples that preserves geological information of the substrate components. This analysis, using backscatter data acquired on a submarine volcano, north of New Zealand, clearly differentiates soft sediments and lava flows within a heterogeneous substrate.  相似文献