夏季闽东沿海水体中透明胞外聚合颗粒物的分布特征及影响因素

透明胞外聚合颗粒物(TEP)在海洋微食物网和海洋碳循环中发挥着重要作用。本文针对夏季闽东沿海TEP的分布特征及影响因素进行研究。结果表明,闽东沿海TEP含量(以黄原胶为标准物质计算,后同)范围为25.2～935.5 μg/L,平均值为(201.8±177.9) μg/L。整体而言,TEP的分布表现为近岸高、远岸低,表层TEP含量相对于底层要低。相关性分析显示,研究海域TEP含量与浊度和营养盐(硅酸盐、磷酸盐、硝酸盐、亚硝酸盐和铵盐)浓度呈正相关,与pH、溶解氧浓度和小型浮游生物量呈负相关。分级叶绿素a结果显示,相对于其他尺寸浮游植物,调查海域小型浮游生物可能对TEP含量的贡献最大。相比于开阔大洋中TEP主控因素为浮游植物而言,夏季闽东海域TEP主要由浮游植物在衰退阶段产生,其分布主要受颗粒物再悬浮作用影响。该结果不仅进一步阐明了近岸海域与开阔大洋TEP影响因素的区别,并且对我国近海海域不同区域TEP分布研究空白进行了补充。     

2019年夏秋季温州近海海水透明胞外聚合颗粒物（TEP）的分布及影响因素分析

透明胞外聚合颗粒物（TEP）具有高黏性、低密度和高碳氮比等特性,在颗粒有机物的聚集以及食物网循环中发挥着重要作用。为了解近岸海域TEP的分布动力学规律与机制,本文对温州近海夏秋季节水体中透明胞外聚合颗粒物的分布进行调查,并结合多项环境要素的主成分分析与相关性分析,探究了浙江南部近岸海域TEP分布的影响因素。结果显示,温州近海TEP秋季平均含量明显高于夏季,夏季TEP分布变化主要受陆地径流（瓯江）作用影响,而秋季主要受闽浙沿岸流影响。受沿岸流影响,秋季TEP的主要来源可能是其他海域以及底层颗粒物再悬浮。此外,由浮游植物释放的TEP对夏季的POC贡献最大,而秋季外源性TEP对POC的贡献较夏季有所升高。     

北白令海透明胞外聚合颗粒物的含量与来源

透明胞外聚合颗粒物(TEP)是海水中大量存在的黏性颗粒物质,它对于海洋颗粒物的聚集、有机碳的埋藏、食物网物质的传递、痕量金属的清除与迁出等均起着重要作用。本研究开展了夏季北白令海陆架、陆坡和海盆区透明胞外聚合颗粒物含量和分布的研究。结果表明,北白令海TEP含量介于34~628 mg/m3(Xeq)之间,其中陆架、陆坡和海盆区TEP的平均含量分别为240, 145和83 mg/m3(Xeq),整体呈现由陆架向外海降低的趋势。在陆坡和海盆区,TEP含量随着深度的增加而降低,但在陆架近底层水中,观察到TEP高含量的特征,与近底层水高的TSM, POC相对应。TEP与荧光强度、TSM、POC等的关系分析显示,研究海域TEP存在两个来源,其一为海洋上层水体的浮游生物,其主要贡献于陆架上层、陆坡和海盆水体;其二为陆架沉积物的底栖生物,其通过沉积物再悬浮贡献于陆架近底层水。     

透明胞外聚合颗粒物碳输运新途径

目前大家普遍认为,透明胞外聚合颗粒物(Transparent Exopolymer Particles,TEP)因其独特的凝聚效应导致碳通量向海底输出。但是,近几年的研究表明TEP不仅影响了碳沉降途径,其本身能够悬浮甚至向海水表层迁移,导致其在海洋微表层(Surface Micro-layer, SML)积累,最终显著影响海洋表层碳通量。TEP和其他颗粒物聚集形成凝聚物后,其运动趋势则由凝聚物中TEP的含量占比,即最终颗粒物密度所决定。一个新的值得注意的现象是,密度低的TEP通过与其他微粒聚合形成表面活性物质(Surface-active Substances, SAS),会在海洋–大气界面形成薄膜,显著影响海–气CO₂交换通量,甚至对全球气候变化造成影响。     

长江口邻近海域透明胞外聚合颗粒物浓度和沉降速率研究

透明胞外聚合颗粒物（Transparent exopolymer particles,TEPs）在海洋中分布广泛,其沉降被认为是海洋中生物碳沉降的途径之一。本研究于2011年春季和夏季调查了长江口邻近海域TEPs的浓度和沉降速率,并且估算了其碳沉降通量。研究发现,TEPs浓度春季介于40.00~1040.00 μg Xeq L^-1,平均值为209.70±240.93 μg Xeq L^-1;夏季介于56.67~1423.33 μg Xeq L^-1,平均值为433.33±393.02 μg Xeq L^-1。两个季节,TEPs在水华站位的浓度明显高于非水华站位。相关性分析表明,TEPs与水体叶绿素a浓度呈显著正相关性,表明在调查区浮游植物是TEPs的主要生产者。TEPs沉降速率在春季介于0.08~0.57 m d^-1,平均值为0.28±0.14 m d^-1;夏季介于0.10~1.08 m d^-1,平均值为0.34±0.31 m d^-1。经估算,TEPs碳沉降通量春季介于4.95~29.40 mg C m^-2 d^-1,平均值为14.66±8.83 mg C m^-2 d^-1;夏季介于6.80~30.45 mg C m^-2 d^-1,平均值为15.71±8.73 mg C m^-2 d^-1。TEPs的碳沉降通量可以占到浮游植物碳沉降通量的17.81%~138.27%。水华站位TEPs的碳沉降通量明显高于非水华站位,这是由于水华站位较高的TEPs浓度及沉降速率所致。本研究表明,TEPs的沉降在长江口邻近海域是碳沉降的有效途径,在相应的碳沉降相关研究中应该被考虑进来。     

东海PN断面透明胞外聚合颗粒物分布特征及来源研究

透明胞外聚合颗粒物（TEP）是凝聚网的重要组成部分甚至核心,在微尺度范围上形成了水环境结构的重要梯度,对于元素地球化学生物循环、碳沉降以及食物网有着举足轻重的作用。本文研究了东海典型断面PN透明胞外聚合颗粒物的分布特征及来源。结果表明:东海典型断面PN透明胞外聚合颗粒物含量介于28~376 μg Xeq./L之间,平均值为（115±67）μg Xeq./L;呈现出明显的夏季 > 冬季 > 秋季 > 春季的季节变化特征以及近岸 > 外海和底层 > 表层的分布趋势。通过对比透明胞外聚合颗粒物分布趋势和硅藻、甲藻分布趋势以及统计分析得出,东海典型断面PN透明胞外聚合颗粒物主要来源于硅藻,甲藻贡献不大;而外海TEP的来源可能主要由超微型浮游植物贡献。     

Thorium isotopes as tracers of particles dynamics and deep water circulation in the Indian sector of the Southern Ocean (ANTARES IV)

Dissolved and particulate samples were collected to study the distribution of thorium isotopes (²³⁴Th, ²³²Th and ²³⁰Th) in the water column of the Indian sector of the Southern Ocean (from 42°S to 47°S and from 60°E to 66°E, north of the Polar Front) during Austral summer 1999. Vertical profiles of excess ²³⁰Th (²³⁰Th_xs) increases linearly with depth in surface water (0–100 m) and a model was applied to estimate a residence time relative to the thorium scavenging (τ_scav). Low τ_scav in the Polar Front Zone (PFZ) are found, compared to those estimated in the Subtropical Front Zone (STZ). Changes in particle composition between the PFZ and STZ could influence the ²³⁰Th_xs scavenging efficiency and explain this difference. An innovative coupling between ²³⁴Th and ²³⁰Th_xs was then used to simultaneously constrain the settling velocities of small (0.6–60 μm) and large (above 60 μm) particles. Although the different hydrological and biogeochemical regimes visited during the ANTARES IV cruise did not explain the spatial variation of sinking velocity estimates, our results indicate that less particles may reach the seafloor north (60 ± 2 m d^− 1, station 8) than south of the Agulhas Return Current (119 ± 23 and 130 ± 5 m d^− 1 at stations 3 and 7, respectively). This information is essential for understanding particle transport and by extension, carbon export. In the deep water column, the ²³⁰Th_xs concentrations did not increase linearly with depth, probably due to lateral transport of North Atlantic Deep Water (NADW) from the Atlantic to the Indian sector, which renews the deep waters and decreases the ²³⁰Th_xs concentrations. A specific ²³⁰Th_xs transport model is applied in the deep water column and allows us to assess a “travel time” of NADW ranging from 2 to 15 years.     

Vertical and horizontal distribution of fluorescent dissolved organic matter in the Southern Ocean

The vertical and horizontal distribution of fluorescent dissolved organic matter (FDOM), determined by fluorescence intensity at 320 nm excitation and 420 nm emission, were clarified in nine stations on two transects at the Southern Ocean, including a subtropical, subantarctic, polar frontal and Antarctic zone. All vertical profiles of fluorescence intensity showed that levels were lowest in the surface waters, increased with increasing the depth in mid-depth waters ( 2000 m), and then stayed within a relatively narrow range from there to the bottom. Such vertical profiles of FDOM were similar to those of nutrients, but were adverse to dissolved oxygen. In water columns below the temperature-minimum subsurface water (dichothermal waters) in the Antarctic zone and below the winter mixed layer in the other zones, we determined the relationships of fluorescence intensity to concentrations of nutrients and apparent oxygen utilization (AOU) over the entire area of the present study, and found significant linear correlations between the levels of fluorescence intensity and nutrient concentrations (r =  0.70 and 0.71 for phosphate and nitrate + nitrite, respectively) and AOU (r = 0.91). From the strong correlation coefficient between fluorescence intensity and AOU, we concluded that FDOM in the Southern Ocean is formed in situ via the biological oxidation of organic matter. The regeneration of the nutrients/consumption of the oxygen/formation of FDOM was active in mid-depth waters. However, the correlations between fluorescence intensities and nutrients and AOU were different in the mid-depth water masses, Subantarctic Mode Water (SAMW), and Antarctic Intermediate Water (AAIW), indicating that the sources of organic matter responsible for FDOM formation were different. A considerable amount of FDOM in the SAMW is thought to be produced by the remineralization of DOM in addition to sinking particulate organic matter, while DOM is less responsible for FDOM formation in the AAIW.     

Abundance and size distribution of transparent exopolymer particles (TEP) in a coccolithophorid bloom in the northern Bay of Biscay

The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEP_micro) and colorimetric (TEP_color) methods, showed abundant (6.1×10⁶–4.4×10⁷ L^?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEP_micro and similar vertical profiles of TEP_color. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L^?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms.     

Diversity and large-scale biogeography of Paramesochridae (Copepoda, Harpacticoida) in South Atlantic Abyssal Plains and the deep Southern Ocean

Multicorer samples for meiofaunal study were obtained within the framework of the international project CeDAMar, at 21 stations occupied during the DIVA and ANDEEP campaigns (2000, 2002 and 2005) to the southern Atlantic Ocean (Guinea, Angola and Cape Basins) and the Southern Ocean (Weddell and Scotia Seas), respectively. A total of 311 adult Paramesochridae Lang, 1944 (Copepoda, Harpacticoida) was extracted from 437 cores obtained during 83 deployments of the corer at depths between 1107 and 5655 m. All specimens were determined to species based on morphological characteristics. They belonged to 19 species and four genera (Kliopsyllus Kunz, 1962, Leptopsyllus T. Scott, 1894, Paramesochra T. Scott, 1892 and Scottopsyllus Kunz, 1962). Eleven species were restricted to single regions, whereas the others showed a much wider distribution. For example, Kliopsyllus andeep Veit-Köhler, 2004 and Kliopsyllus diva Veit-Köhler, 2005, were both collected from Guinea, Angola and Weddell Abyssal Plains, and Kliopsyllus schminkei Veit-Köhler & Drewes, 2009 occurred in the three West-African basins. This study provides a first insight into the large-scale biogeography of deep-sea harpacticoids, represented by the Paramesochridae, and indicates that distribution ranges, at least in this family, may extend across South Atlantic and Southern Ocean Abyssal Plains.     

南大洋气旋气候与变化特征

A new climatology of cyclones in the Southern Ocean is generated by applying an automated cyclone detection and tracking algorithm(developed by Hodges at the Reading University) for an improved and relatively highresolution European Centre for Medium-Range Weather Forecasts atmospheric reanalysis during 1979–2013.A validation shows that identified cyclone tracks are in good agreement with a available analyzed cyclone product.The climatological characteristics of the Southern Ocean cyclones are then analyzed,including track,number,density,intensity,deepening rate and explosive events.An analysis shows that the number of cyclones in the Southern Ocean has increased for 1979–2013,but only statistically significant in summer.Coincident with the circumpolar trough,a single high-density band of cyclones is observed in 55°–67°S,and cyclone density has generally increased in north of this band for 1979–2013,except summer.The intensity of up to 70% cyclones in the Southern Ocean is less than 980 h Pa,and only a few cyclones with pressure less than 920 h Pa are detected for1979–2013.Further analysis shows that a high frequency of explosive cyclones is located in the band of 45°–55°S,and the Atlantic Ocean sector has much higher frequent occurrence of the explosive cyclones than that in the Pacific Ocean sector.Additionally,the relationship between cyclone activities in the Southern Ocean and the Southern Annular Mode is discussed.     

Comparison of airsea fluxes of CO2 in the Southern Ocean and the western Arctic Ocean

The data were collected during Chinese Arctic and Antarctic Expeditions in the western Arctic Ocean and the marginal sea ice zone (MSIZ) of the Southern Ocean, respectively in the boreal summer from July to September of 1999 and in the austral summer from December of 1999 to January of 2000. The concentrations of CO2 in surface water of the survey regions would mostly present lower than those in the atmosphere. A significant biological driving force could also been observed in summer waters in both of the above oceans. Air to sea CO2 fluxes were also calculated to compare oceanic uptake capacity of CO2 in both oceans with the world oceans using Liss, Wanninkhof, and Jacobs‘s methods. The averaged CO2 fluxes of air to sea in the western Arctic Ocean or in the MSIZ of the Southern Ocean doubled that in the world oceans.     

中国南大洋水团、环流和海冰研究进展(1995-2002)

总结了1995年以来中国在南大洋物理海洋学研究和南极海冰研究中所取得的成果。普里兹湾海区是中国南大洋研究的重点区域，研究表明，在该海区存在显著的深层水涌升和陆架水北扩现象，某些年份深层水与陆架水混合后产生了较重的水体，但是尚未发现生成南极底层水的直接证据。在普里兹湾所处的印度洋区段，亚热带锋、亚南极锋和极锋表现出显著的时空变化，特别是不同年份的锋面位置存在较大的摆动。该海区的南极绕极流既是风生的，也受到密度场的影响。在凯尔盖朗海台的地形引导作用下，南极绕极流表现出显著的非纬向性特征。南极海冰除了显著的季节变化以外，也表现出长期变化的趋势。此变化与海洋、大气中的其它变化有一定的相关性，表现为两极海冰涛动、南方海洋涛动等多种变化模态，对我国气候也有一定的影响。     

南大洋大气有机胺分布及来源特征研究

依托中国第36次南极科学考察,利用船载走航气溶胶及气体组分在线分析仪对南大洋大气中气态和颗粒态有机胺进行了在线观测。获得了南大洋开阔海域及普里兹湾大气中高分辨气态和颗粒态有机胺的组成及分布,并对其来源特征进行了分析。结果表明：南大洋大气有机胺以气态三甲胺（TMA）和二甲胺（DMA）为主要存在形态,其均值分别为(104.0±285.2)、(3.5±6.0) ng/m3。普里兹湾大气中有机胺的平均浓度显著高于南大洋开阔海域,气态TMA和DMA均值分别达到(289.0±396.6)、(5.6±16.1) ng/m3。南大洋大气中气态TMA、DMA和氨气（NH3）在不同区域内均具有良好的线性关系,表明三者具有同源性。从来源分析,南大洋大气有机胺主要受到海洋生物活动的影响,但在海冰边缘区及南极近岸海域,企鹅等动物的生物活动会导致大气中有机胺的浓度显著升高。     

Development of the Southern Ocean Continuous Plankton Recorder survey

The Continuous Plankton Recorder (CPR) Type I was first used in Antarctic waters during the 1925–1927 Discovery Expedition, and has been used successfully for 70 years to monitor plankton in the North Sea and North Atlantic Ocean. Sixty-five years later the CPR as a Type II version returned to Antarctic waters when the Australian Antarctic Division initiated a survey of the Southern Ocean on RSV Aurora Australis south of Australia and west to Mawson. The objectives are to study regional, seasonal, interannual and long-term variability in zooplankton abundance, species composition and community patterns, as well as the annual abundance and distribution of krill larvae. The survey covers a large area from 60°E to 160°E, and south from about 48°S to the Antarctic coast—an area of more than 14 million km². Tows are conducted throughout the shipping season, normally September to April, but occasionally as early as July (midwinter). The large areal and temporal scale means that it is difficult to separate temporal and geographical variation in the data. Hence, CPRs are now also towed on the Japanese icebreaker Shirase in collaboration with the Japanese Antarctic programme. Shirase has a fixed route and time schedule, travelling south on 110°E in early December and north on 150°E in mid-March each year, and will serve as an important temporal reference for measuring long-term interannual variability and to help interpret the Australian data. Since 1991, over 90 tows have been made, providing over 36,000 nautical miles of records. The most successful seasons to date have been the 1997/1998, 1999/2000 and 2000/2001 austral summers with 20, 31 and 26 tows, respectively. The 1999/2000 season included a unique, nearly simultaneous three-ship crossing of the Southern Ocean along 25° 30’E, 110°E and 157°E. Typical CPR tows show very high abundance of zooplankton in the uppermost 20 m of the permanently open ocean zone between the sea-ice zone and the Sub-Antarctic Front; this is an area thought to be oligotrophic. Appendicularians and small calanoid and cyclopoid copepods dominate the plankton. By comparison the surface waters of the sea-ice zone have low species diversity and abundances. Zooplankton data, and hence distribution patterns, can be time- and geo-coded to GPS data and environmental data collected by the ships’ underway monitoring system (e.g. fluorescence, water temperature, salinity, and meteorological data).     

Vertical distributions of dissolved organic carbon and nitrogen in the Southern Ocean

Detailed vertical profiles of dissolved organic carbon (DOC), nitrogen (DON) and DOC/DON ratios in the Australian sector of the Southern Ocean (56°–65°S around 140°W transect) were obtained by a high-temperature catalytic oxidation method with a modified Shimadzu TOC-5000 unit. The simultaneous analyses of DOC and total dissolved nitrogen (TDN) gave high precision results (±0.7 μMC and ±0.3 μMN). In surface layers, DOC concentrations were lower (45–55 μM) than those generally obtained from other oceanic environments (60–90 μM). The surface concentrations of DON varied from 4 to 9 μM, but within the range generally reported for other ocean regions. Surface excesses of DOC and DON were calculated against nearly constant subsurface concentrations. A consistent contribution of low C/N ratio (2.7–5.0) was found in the mid-surface layer (30–75 m), suggesting more extensive degradation of carbon-enriched materials and/or enhanced supply of nitrogen-enriched ones.     

Dissolved iron in the Australian sector of the Southern Ocean (CLIVAR SR3 section): Meridional and seasonal trends

We report measurements of dissolved iron (dFe, <0.4 μm) in seawater collected from the upper 300 m of the water column along the CLIVAR SR3 section south of Tasmania in March 1998 (between 42°S and 54°S) and November–December 2001 (between 47°S and 66°S). Results from both cruises indicate a general north-to-south decrease in mixed-layer dFe concentrations, from values as high as 0.76 nM in the Subtropical Front to uniformly low concentrations (<0.1 nM) between the Polar Front and the Antarctic continental shelf. Samples collected from the seasonal sea-ice zone in November–December 2001 provide no evidence of significant dFe inputs from the melting pack ice, which may explain the absence of pronounced ice-edge algal blooms in this sector of the Southern Ocean, as implied by satellite ocean-color images. Our data also allow us to infer changes in the dFe concentration of surface waters during the growing season. South of the Polar Front, a comparison of near-surface with subsurface (150 m depth) dFe concentrations in November–December 2001 suggests a net seasonal biological uptake of at least 0.14–0.18 nM dFe, of which 0.05–0.12 nM is depleted early in the growing season (before mid December). A comparison of our spring 2001 and fall 1998 data indicates a barely discernible seasonal depletion of dFe (0.03 nM) within the Polar Frontal Zone. Further north, most of our iron profiles do not exhibit near-surface depletions, and mixed-layer dFe concentrations are sometimes higher in samples from fall 1998 compared to spring 2001; here, the near-surface dFe distributions appear to be dominated by time-varying inputs of aerosol iron or advection of iron-rich subtropical waters from the north.     

Mechanisms controlling the temporal variation of the sea ice edge in the Southern Ocean

This paper examines the mechanism controlling the short time-scale variation of sea ice cover over the Southern Ocean. Sea ice concentration and ice velocity datasets derived from images of the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) are employed to reveal this mechanism. The contribution of both dynamic and thermodynamic processes to the change in ice edge location is examined by comparing the meridional velocity of ice edge displacement and sea ice drift. In the winter expansion phase, the thermodynamic process of new ice production off the ice edge plays an important role in daily advances of ice cover, whereas daily retreats are mostly due to southward ice drift. On the other hand, both advance and retreat of ice edges in the spring contraction phase are mostly caused by the dynamic process of the ice drift. Based on the above mechanism and the linear relation between the degree of ice production at the ice edge and northward wind speed, the seasonal advance of ice cover can be roughly reproduced using the meridional velocity of ice drift at the ice edge.     

南大洋沉积物间隙水中营养盐分布及扩散通量研究

利用中国第18次南极考察获得的沉积物样品,对南大洋沉积物间隙水中营养盐的含量及分布特征进行了研究,估算了营养盐的底部通量.结果表明,南大洋沉积物间隙水中的营养盐以高含量的硅酸盐、铵盐为主.在垂向分布上,硅酸盐在沉积物-水界面呈现出明显的浓度梯度,这种分布特征表明,在硅的早期成岩过程中溶出是主要过程.沉积物中有机物的降解反应主要在还原状态下进行.硅酸盐与铵盐存在明显的向上释放的通量.