夏季北黄海水体浊度分布特征的初步研究

应用2007月7月国家908专项北黄海区块水体调查获取的浊度资料,与同步获得的悬浮物质量浓度进行拟合分析,结果表明,中底层水的相关系数在0.94以上,表层相关度较差.根据调查海域浊度的水平大面分布及选取的6个典型断面的垂直分布,初步阐述了夏季北黄海水体浊度的分布特征——近岸高和底层高,山东半岛北部沿岸、成山角海域和老铁山水道以及庄河河口附近海域为高浊度区.夏季北黄海冷水团对水体浊度分布具有控制性影响:调查海域水体垂向层结稳定,北黄海冷水团海域中下层表现为高盐、低温、高密特征,水体浊度小,且浊度锋面的分布与温度较为相近.同时,夏季北黄海冷水团对悬浮物的分布起到了屏障作用——在山东半岛北部沿岸和辽东半岛南部沿岸阻止了近岸悬浮物的经向输送,而在山东半岛东部沿岸则阻止了近岸悬浮物的纬向输送.     

胶州湾大沽河口潮间带沉积物中叶绿素和有机质含量的季节变化

为了解胶州湾大沽河口潮间带沉积物中底栖微藻和有机质含量的季节变化,于2010年4月至2011年2月,分4次(春、夏、秋、冬)测定分析了沉积物中的叶绿素含量和有机质含量,并分析了沉积物的粒度组成及现场温度。结果表明,表层(0～2cm)沉积物叶绿素a含量为0.42～6.06mg/kg,有机质含量为0.48%～3.71%;次表层(2～5cm)叶绿素a含量为0.13～3.53mg/kg,有机碳质量为0.31%～3.78%;深层(5～8cm)叶绿素a含量为0.14～1.95mg/kg,有机质含量为0.47%～3.72%。经统计检验和Pearson相关性分析得出,胶州湾大沽河口沉积物中的叶绿素a含量春冬两季最高,夏季和秋季最低;叶绿素a含量与深度和温度呈负相关;与所处潮带、有机质含量、粉砂黏土含量在本实验中均无显著的相关性;有机质含量与季节关系不大,高潮带最高,其含量与粉砂黏土含量呈正相关,与叶绿素含量、深度和温度关系不明显。     

Suspended particulate matter in the St. Lawrence estuary and Gulf surface layer and development of a remote sensing algorithm

Remote sensing of chlorophyll concentration is potentially affected by the presence of inorganic matter in the water column. Seasonal variability of total suspended particulate matter (SPM) concentration and its partition into organic and inorganic fractions was thus measured in the estuary and Gulf of St. Lawrence during five cruises. These measures were made in the surface layer down to the depth of the 0.1% light level. Results indicate that vertical variability was small for the entire study area. Data analysis lead to the definition of two main regions having different SPM characteristics: 1) the estuary zone characterized by a strong spatial variability, intermediate SPM concentrations and a clear spring phytoplankton bloom that is combined to an increased inorganic matter load; 2) the gulf region characterized by a relatively low SPM concentration and phytoplankton blooms in the spring and fall periods. Combined with in situ measurements of remote sensing reflectances, the database was used to validate existing inorganic matter retrieval algorithms and develop a new one better adapted to the low concentrations encountered in the St. Lawrence estuary and Gulf.     

Origin and biochemical cycling of particulate nitrogen in the Mandovi estuary

Mandovi estuary is a tropical estuary strongly influenced by the southwest monsoon. In order to understand, sources and fate of particulate organic nitrogen, suspended particulate matter (SPM) collected from various locations, was analyzed for particulate organic carbon (POC) and particulate organic nitrogen (PON), δ¹³C_POC, total hydrolysable amino acid enantiomers (l- and d- amino acids) concentration and composition. δ¹³C_POC values were depleted (−32 to −25‰) during the monsoon and enriched (−29.6 to −21‰) in the pre-monsoon season implying that OM was derived from terrestrial and marine sources during the former and latter season, respectively. The biological indicators such as C/N ratio, d-amino acids, THAA yields and degradation indices (DI) indicate that the particulate organic matter (POM) was relatively more degraded during the monsoon season. Conversely, during the pre-monsoon, the biological indicators indicated the presence of relatively fresh and labile POM derived from autochthonous sources. Amino acids such as alanine, aspartic acid, leucine, serine, arginine, and threonine in monsoon and glutamic acid, glycine, valine, lysine, and isoleucine in pre-monsoon were relatively abundant. Presence of bacterial biomarker, d-amino acids in the SPM of the estuary during both the seasons signifies important contribution of bacteria to the estuarine detrital ON pool. Based on d-amino acid yields, bacterial OM accounted for 16-34% (23.0 ± 6.7%) of POC and 29-75% (47.9 ± 18.7%) of PON in monsoon, and 30-78% (50.0 ± 15%) of POC and 34-79% (51.2 ± 13.3%) of the PON in pre-monsoon in the estuary. Substantial contribution of bacterial-N to PON indicates nitrogen (N) enrichment on terrestrial POM during the monsoon season. Transport of terrestrial POM enriched with bacterial OM to the coastal waters is expected to influence coastal productivity and ecosystem functioning during the monsoon season.     

Complexation of mercury by dissolved organic matter in surface waters of Galveston Bay, Texas

The chemical speciation of dissolved mercury in surface waters of Galveston Bay was determined using the concentrations of mercury-complexing ligands and conditional stability constants of mercury-ligand complexes. Two classes of natural ligands associated with dissolved organic matter were determined by a competitive ligand exchange-solvent solvent extraction (CLE-SSE) method: a strong class (L_s), ranging from 19 to 93 pM with an average conditional stability constant (K_HgLs) of 10²⁸, and a weak class (L_w) ranging from 1.4 to 9.8 nM with an average K_HgLs of 10²³. The range of conditional stability constants between mercury and natural ligands suggested that sulfides and thiolates are important binding sites for dissolved mercury in estuarine waters. A positive correlation between the estuarine distribution of dissolved glutathione and that of mercury-complexing ligands supported this suggestion. Thermodynamic equilibrium modeling using stability constants for HgL, HgCl_x, Hg(OH)_x, and HgCl(OH) and concentrations of each ligand demonstrated that almost all of the dissolved mercury (> 99%) in Galveston Bay was complexed by natural ligands associated with dissolved organic matter. The importance of low concentrations of high-affinity ligands that may originate in the biological system (i.e., glutathione and phytochelatin) suggests that the greater portion of bulk dissolved organic matter may not be important for mercury complexation in estuarine surface waters.     

Local remineralization patterns in the mesopelagic zone of the Eastern North Atlantic, off the NW Iberian Peninsula

The short-time-scale variability of the remineralization patterns in the domain of Eastern North Atlantic Central Waters (ENACW) off the NW Iberian Peninsula is studied based on biogeochemical data (oxygen, nutrient salts, total alkalinity, pH, dissolved organic matter and fluorescence of dissolved humic substances) collected weekly between May 2001 and April 2002. The temporal variability of inorganic variables points to an intensification of remineralization during the summer and autumn, with an increase of nutrients, total inorganic carbon and fluorescence and a decrease of oxygen. During the subsequent winter mixing, there is a biogeochemical reset of the system, with lower nutrients, total inorganic carbon and fluorescence and higher oxygen. In contrast to inorganic variables, the levels of dissolved organic matter in the ENACW seem to respond to short-term events probably associated with fast sinking particles, where solubilisation of organic matter prevails over remineralization. Applying a previously published stoichiometric model, we observed a vertical fractionation of organic-matter remineralization. Although there is a preferential remineralization of proteins and P compounds in the entire domain of ENACW, the percentage was higher in the upper ENACW (σ<27.10 kg/m³) than in the lower; the percentage of N and P compounds in the oxidised organic matter was >80% for the upper ENACW and 63% for the lower. Likewise, the redissolution of calcareous structures contributes about 6% and 13% to the carbon regenerated in the upper and lower layers of ENACW, respectively.     

Distribution of suspended particulate matter in the northern Bohai Bay in summer and its relation with thermocline

Field observations of suspended particulate matter (SPM) in the Bohai Bay, China have not been widely reported. The aim of this paper is to describe the horizontal and vertical distribution of mass and volume concentrations of SPM, respectively, based on observed data at 312 stations in the northern Bohai Bay during summer of 2006. A numerical model ECOMSED coupled with a sediment transport module was also established to further discuss the mechanism of the thermocline effect on the vertical distribution of SPM. The mass concentrations of SPM exhibited high inshore values and low offshore values in the horizontal distribution; while in the vertical direction, characteristics of the volume concentration of SPM can be divided into two types: one with a sharp peak at depth of 10–15 m and another without. The peak value at the depth of the thermocline was resulted from concentrated phytoplankton. A numerical experiment further displayed that the thermocline can also prevent particles from being resuspended upward.     

山东半岛沿岸流强度与悬浮体时空变化特征

基于2014—2018年NOAA/AVHRR遥感数据,在山东半岛海域选取6条剖面,结合海表温度和表层悬浮体的时空变化特征,详细研究了山东半岛沿岸流的年周期变化规律与移动路径。研究结果表明,山东半岛沿岸流年周期变化可分为4个阶段：成长期（10—12月）时开始形成于黄河口附近,沿莱州湾南部向东运移;强盛期（次年1—3月）时山东半岛沿岸流完全成型,扩散带最宽,鼎盛时期北部可以至38°N附近,东部可以至123°E附近,在35°～36°N附近分成NE—SW向的2个分支,主干部分最远可到达胶州湾东部海域,余流沿岸向西南方向转折;衰退期（4—6月）时沿岸流强度减弱,只在山东半岛北部和东部小范围内有微弱的显示;消亡期（7—9月）时基本消失。山东半岛沿岸流在冬季时对悬浮体扩散具有强烈的驱动作用,使其在黄河口南侧与山东半岛北岸-成山头东部海域分别形成呈“弧形”和“条带状”分布的2个高浓度区域。     

Palomar Testbed Interferometer Observations of Young Stellar Objects

We present observations of a sample of Herbig AeBe stars, as well as the FU Orionis object V1057 Cygni. Our K-band (2.2μm) observations from the Palomar Testbed Interferometer (PTI) used baselines of 110 m and 85 m, resulting in fringe spacings of ∼4 mas and 5 mas, respectively. Fringes were obtained for the first time on V1057 Cygnias well as V594 Cas. Additional measurements were made of MWC147, while upper limits to visibility-squared are obtained for MWC297, HD190073, and MWC614. These measurements are sensitive to the distribution of warm, circumstellar dust in these sources. If the circumstellar infrared emission comes from warm dust in a disk, the inclination of the disk to the line of sight implies that the observed interferometric visibilities should depend upon hour angle. Surprisingly, the observations of Millan-Gabet, Schloerb and Traub (2001)(hereafter MST) did not show significant variation with hour angle. However, limited sampling of angular frequencies on the sky was possible with the IOTA interferometer, motivating us to study a subset of their objects to further constrain these systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

The dynamical structure of dwarf elliptical galaxies

Deep imaging and long-slit spectroscopy was obtained for a sample of dwarf ellipticals in the Fornax cluster, NGC 5044 and NGC 5898 groups using the ESO VLT. The observational data extend out to typically 1.5–2 effective radii and indicate a kinematic dichotomy in the family of ellipticals. The observed stellar kinematics indicate a luminosity–velocity dispersion relation largely supporting Supernova-driven stellar mass loss scenarios for the formation of dwarf ellipticals. Stellar dynamical models favour dark matter halos with typical mass-to-light ratios in the range of 3 to 9 solar units. This revised version was published online in August 2006 with corrections to the Cover Date.