钦州湾磷营养状态与浮游植物的碱性磷酸酶活性分析

碱性磷酸酶(Alkaline phosphatase,AP)是浮游植物在磷胁迫的情况下诱导表达的一种酶,其作用是能够将溶解有机磷(Dissolved organic phosphate,DOP)水解成浮游植物可以直接利用的正磷酸盐形式,因此碱性磷酸酶活性(Alkaline phosphatase activity,APA)可用来指示海区浮游植物的磷胁迫状态。本研究以2015-2016年钦州湾4个航次(春季、夏季、秋季、冬季)的调查资料为依据,研究了钦州湾海域表层无机及有机磷的空间分布特征、APA的分布及其与磷营养之间的调控关系。调查期间,钦州湾海域春季、夏、秋、冬的单位叶绿素APA的平均值分别为20.42±5.32 nmol/μg Chl a/h,138.17±94.32 nmol/μg Chl a/h,142.60±72.60 nmol/μg Chl a/h和29.48±18.52 nmol/μg Chl a/h。经分析,APA与无机磷之间存在显著的负相关(P0.05),与N/P呈极显著负相关(P0.01),该海区APA可以反映钦州湾浮游植物的磷胁迫水平。海区氮磷比平均值在除春季外的三个季节均高于35,存在潜在的磷限制,浮游植物在夏季和秋季遭受较严重的磷胁迫。夏季和秋季浮游植物大量表达AP,由此推测DOP可能在钦州湾浮游植物生物量的维持甚至赤潮发生期间的磷补给上起着重要作用。     

秦皇岛近海褐潮高发区浮游植物的碱性磷酸酶活性分析

碱性磷酸酶(Alkaline phosphatase,AP)是浮游植物在磷胁迫状态下表达的一种水解有机磷源的胞外酶,可用于指示海区浮游植物的磷胁迫状态。本研究于2013年7月,对秦皇岛近海抑食金球藻(Aureococcus anophagefferens)褐潮发生期间浮游植物的碱性磷酸酶活性(AP activity,APA)进行研究,结合其他理化参数,分析藻华发生时浮游植物的磷营养状态及其对海水中磷源的水解与利用情况。结果表明,褐潮发生时,抑食金球藻细胞密度高达108个/L,溶解有机磷(Dissolved organic phosphorus,DOP)成为浮游植物生长利用的主要磷源。抑食金球藻的细胞密度受到海水中NO3–、DOP、溶解无机磷(Dissolved inorganic phosphorus,DIP)浓度等的显著影响。浮游植物大量表达AP水解DOP,平均APA高达217.72 nmol/(μg·h)±90.86 nmol/(μg·h)(350.44 nmol/(L·h)±130.57 nmol/(L·h)),且APA随浮游植物生物量增大而显著增加。该结果表明抑食金球藻褐潮发生时,海区遭受严峻的磷胁迫甚至限制。磷源,尤其是有机磷源的可利用性可能在秦皇岛海区抑食金球藻褐潮的发生和维持中起关键作用。     

夏季长江口不同粒级浮游植物碱性磷酸酶活性

碱性磷酸酶活性(alkaline phosphatase activity, APA)是海洋研究中用于反映浮游植物磷限制状态的重要指标。在长江口等“氮过剩”海域,磷是控制海域初级生产力水平的主要因子,然而,磷限制的范围常常难以界定,当前对不同粒级浮游植物的磷限制效应所知甚少。该文根据2020年夏季长江口航次资料,给出了海洋表层各粒级浮游植物(Net:≥20 μm;Nano:2~20 μm;Pico:0.8~2 μm)APA、浮游细菌APA(0.2~0.8 μm)和溶解态APA(<0.2 μm)的空间分布特征,并分析了APA与环境要素间的相关性。结果显示,各粒级浮游植物APA均与无机磷酸盐浓度(dissolved inorganic phosphate, DIP)呈显著负相关,这表明DIP浓度是影响浮游植物APA分布的主要因素。在平面分布上,各粒级浮游植物APA在近口门的光限制区均较低,且呈现自口门向外逐渐升高的趋势,与DIP的分布特征相反。Net和Nano级APA[平均值分别为 (40.28±32.35) nmol/(L·h)和(52.38±34.78) nmol/(L·h)]显著高于Pico级APA[平均值为(28.43±20.23) nmol/(L·h)],这表明大粒级浮游植物可能更易受DIP下降的影响。该研究中,诱导浮游植物APA快速升高的DIP浓度为0.159 μmol/L,与近岸区磷限制经验阈值相接近。该研究揭示了夏季不同粒级浮游植物对长江口磷分布的响应特征,有助于理解长江口初级生产过程的环境调控机制。     

盐度对刺参(Apostichopus japonicus)呼吸和排泄的影响

采用封闭式呼吸器法研究了(15±0.5)℃水温条件下不同盐度(22、27、31.5、36)对四种规格刺参{S[(39.60±8.77)g]、M[(71.80±14.04)g]、L[(128.30±19.69)g]和XL[(196.65±19.81)g]}呼吸和排泄的影响。结果表明,各规格组刺参单位体重耗氧率[Rwr,μg/(g·h)]和排氨率[(Rwe,μg/(g·h)]在盐度22—31.5范围内均随着盐度的升高而降低,当盐度升高至36时,二者都明显升高;各盐度下实验刺参的单位体重耗氧率分别为17.52、16.32、15.49和17.60μg/(g·h),单位体重排氨率分别为1.05、0.88、0.87和0.95μg/(g·h);在同一盐度下,刺参体重越大,其单位个体耗氧率[Rir,μg/(ind·h)]和排氨率[Rie,μg/(ind·h)]越高,二者呈幂函数关系,可用关系式Rir(或Rie)=aWb表示;关系式Rir=aWb中,a值的变动范围为40.6656—81.1900,b值为0.6432—0.8145;而关系式Rie=aWb中,a值的变动范围为2.0947—4.8489,b值为0.6507—0.8072;盐度对刺参O∶N比的影响不显著,各盐度条件下,不同规格的刺参,其O∶N比均在15左右,表明本实验条件下该参代谢所需要的能量主要由脂肪和碳水化合物提供。从呼吸和排泄的角度来看,刺参在其最适温度(15℃)条件下,具有一定的渗透压调节能力,能够适应较广的盐度变化范围(22—36)。     

秋季东海二甲基硫和二甲巯基丙酸内盐浓度分布及降解速率研究

于2013年10~11月现场测定了东海中二甲基硫(DMS)及其前体物质二甲巯基丙酸内盐(DMSP,分为溶解态DMSPd和颗粒态DMSPp)的含量,研究其水平分布特征、DMSPp的粒径分布及DMSPd的降解速率,并对DMS的海-气交换通量进行了探讨。研究结果表明,表层海水中DMS、DMSPd和DMSPp的浓度平均值分别为(4.84±0.40)、(5.84±0.93)和(13.01±0.52)nmol·L-1。海水中DMSPd的降解速率在2.59~16.36nmol·L-1·d-1之间,平均值为(6.78±0.84)nmol·L-1·d-1。调查海域范围内,小型浮游植物(20μm)是DMSPp和叶绿素a(Chl a)重要贡献者。此外,秋季东海表层海水DMS的海-气交换通量为0.66~31.73μmol·m-2·d-1,平均值为(11.63±0.71)μmol·m-2·d-1。     

冬季大鹏澳海域微表层浮游植物色素特征的日变化研究

于2013年12月3日清晨、正午、傍晚采集了大亚湾大鹏澳海域3个站位的微表层和次表层水样,经过三级分级过滤(小型:20μm;微型:2.7~20μm;微微型:2.7μm)后,对其进行高效液相色谱(HPLC)色素分析,通过藻类色素化学分类法(CHEMTAX)分析不同浮游植物对Chl a的贡献,研究了微表层及次表层光合色素粒径特征及浮游植物群落结构差异。结果表明,冬季大亚湾海域水体中存在的浮游植物光合色素主要有17种,以岩藻黄素和Chl a含量较高。微表层总Chl a平均浓度为0.797μg/L,略高于次表层的0.714μg/L,不存在显著性差异(P0.05);微表层和次表层Chl a含量清晨最高,傍晚次之,正午最低。微表层不同粒径浮游植物对Chl a的贡献率从大到小依次为小型、微型、微微型浮游植物,分别为80.7%,10.1%和9.2%。CHEMTAX分析结果得出,冬季该海域硅藻占绝对优势,甲藻、定鞭藻、青绿藻、蓝藻、隐藻所占比重相差不大。微表层中定鞭藻、青绿藻和蓝藻等较小粒径浮游植物种群所占比重高于次表层,说明相对于次表层,微表层中的浮游植物群落有小型化趋势。     

钱塘江河口浮游植物分布与环境因子的典范对应分析

2013年5月至2014年1月对钱塘江河口的浮游植物和环境因子进行了4个季度的航次调查,运用典范对应分析(CCA)技术对该海域浮游植物组成及与其他环境因子之间的关系进行了分析。主要结论为:钱塘江河口春、夏、秋、冬季水体中叶绿素a含量分别为0.48μg/L、0.83μg/L、0.77μg/L和0.51μg/L;浮游植物的总量以春季(444×105 cell/m3)最高,夏季(420×105 cell/m3)、秋季(405×105 cell/m3)次之,冬季(54×105 cell/m3)则显著降低;该海域主要浮游植物为硅藻,占浮游植物总量的87.5%~96.8%,优势种为中肋骨条藻和圆筛藻;浊度是控制该海域浮游植物种类的限制性因子,其次是温度,并在群落结构演替中发挥关键作用。与历史数据相比,该海域叶绿素a含量以及浮游植物细胞数明显降低,硅藻种类数减少了30%~50%,另外绿藻、蓝藻和甲藻的出现频率也明显增加,营养盐结构变化可能是浮游植物数量和种类变化的重要原因。     

枯水期钦州湾浮游植物群落结构组成与分布特征

应用浮游植物特征光合色素的分析方法,研究了2011年枯水期钦州湾浮游植物的结构组成与分布特征。结果表明:枯水期含量较高的浮游植物光合色素按含量高低依次为叶绿素a、岩藻黄素、叶绿素b、青绿素和多甲藻素,其他特征光合色素的含量很低。经CHEMTAX对光合色素转化计算,枯水期普遍检出的浮游植物类群为硅藻、青绿藻和甲藻,是枯水期浮游植物的优势类群,其生物量的平均值(±标准差)分别为(2.36±2.38)μg/L、(0.87±0.53)μg/L、(0.13±0.14)μg/L,变化范围为0.18~7.45μg/L、0.10~1.80μg/L和0.02~0.60μg/L。硅藻、青绿藻和甲藻占枯水期浮游植物生物量比例的平均值(±标准差)分别为59%±21%、30%±16%、6%±4%,占比变化范围为29%~96%、1%~53%和0.4%~14%,其他藻类所占比例很低。河口和外湾靠外海域两个区域以硅藻为优势类群,内湾及外湾近岸硅藻和青绿藻共同为优势类群。河流营养盐输入量和比例的不同决定了钦州湾河口海区浮游植物群落结构的差异,大面积贝类养殖导致了内湾至外湾近岸海区硅藻比例的降低,而外湾水温的增加引起暖水性硅藻大量增长成为优势类群,在温度进一步增加和营养盐持续输入等条件下存在会发生硅藻赤潮的风险。     

黄海微微型浮游植物对灰霾颗粒添加以及光照变化的响应

本研究于2020年夏、秋两季,在黄海的三个站位开展了船基受控培养实验,研究了灰霾颗粒添加和光照变化(相较于海面约40%、68%和82%的光衰减)对微微型浮游植物生长、群落演替及碳生物量和叶绿素a(Chl a)比值的影响。结果表明,微微型浮游植物均表现出对总Chl a相当甚至主导的贡献能力,且所有培养站位初始海水中微微型浮游植物优势类群均为微微型真核浮游植物和聚球藻。在黄海中部和北部的贫营养海域,灰霾颗粒添加提供的氮能够促进微微型浮游植物的Chl a(Chl a_pico)浓度、微微型真核浮游植物和聚球藻细胞丰度的增加,但光照变化的影响不显著。然而,微微型浮游植物碳生物量(C_pico)和Chl a_pico比值(C_pico/Chl a_pico)随着灰霾颗粒的添加和光照强度的衰减呈降低趋势,这与浮游植物的光合色素合成水平密切相关。在近岸富营养海域,培养实验期间海面的光照强度较低,且由于海域水体浑浊,光照强度是影响微微型浮游植物生长和C_pico/Chl a_...     

春、夏季长江口及邻近海域溶解甲烷的分布与释放通量

分别于2012年3和7月对长江口及其邻近海域进行了大面调查,测定了表、底层海水中溶解甲烷浓度,并对其海-气交换通量进行了估算。结果表明,春、夏季表层甲烷的平均浓度分别为(28.33±38.33)和(19.92±19.18)nmol·L-1,甲烷浓度从内河口向外海逐渐降低。长江口溶解甲烷浓度和饱和度有明显季节变化,其中春季内河口甲烷浓度和饱和度高于夏季,但外河口及邻近海域则相反,这主要是温度和长江冲淡水中甲烷浓度的季节差异造成的。该海域溶解甲烷的分布受陆源输入影响显著,夏季长江冲淡水影响范围较春季更广,但由于稀释效应夏季甲烷浓度低于春季。夏季沉积物的释放对河口区甲烷的贡献较春季更为明显。调查期间该海域溶解甲烷都处于过饱和状态,是大气甲烷的净源;根据W92公式初步估算出长江口及其邻近海区年释放CH4量约为8.81×108 mol·a-1,占全球海洋年释放量的0.08%,远高于其面积比0.01%,因此该海区是甲烷产生和释放的活跃海域。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.