Different cardiac response to copper in limpets from metal polluted and clean shores of Hong Kong

The gastropod limpet, Cellana grata, is common on moderately exposed to exposed Hong Kong rocky shores. On the basis of the existing literature on trace metal contamination in Hong Kong, four sites were identified, representative of highly polluted (Aberdeen and Lei Yue Mun) and clean (Cape d'Aguilar and Clear Water Bay) conditions. Limpets from the two polluted sites showed similar, but significantly higher body concentrations of copper than limpets from the two clean sites, which were also similar. Non-invasive measurements of cardiac activity of limpets from the four sites showed between site differences in baseline heart rates under standard seawater, irrespective of pollution level. When acutely exposed to water borne copper (2 h, 0.5+/-0.06 SD ppm), however, limpets from clean sites showed a significantly higher increase in inter-beating time (bradycardia) than those from polluted sites. These results highlight the potential use of cardiac activity to assess the exposure of natural populations of limpets to trace metal pollution.     

On the effectiveness of the ocean's biological pump in global CO2 scenarios

An evaluation is made of the effectiveness of the ocean's biological pump in driving the deep-sea excess CO₂ from the atmosphere. It is based on sediment-trap data available in the literature and on estimates of present and future inputs of anthropogenic nitrogen and phosphorous. The fraction of annual CO₂ production from fossil fuel combustion going into this sink turns out to be insignificant in the total budget of man-made CO₂. A discussion is presented on the formation of macroflocs under oceanic conditions, a process that has been believed to be important for the effectiveness of the biological pump.     

Seismic evidence of small-scale lacustrine drifts in Lake Baikal (Russia)

High resolution, single-channel seismic sparker profiles across the Akademichesky Ridge, an intra-basin structural high in Lake Baikal (Russia), reveal the presence of small sediment mounds and intervening moats in the upper part of the sedimentary cover. Such features interrupt the generally uniform and even acoustic facies and are not consistent with the hemipelagic sedimentation, which is expected on such an isolated high and which would produce a uniform sediment drape over bottom irregularities. The influence of turbidity currents is excluded since the ridge is an isolated high elevated more than 600-1000 m above adjacent basins. The mounded seismic facies, including migrating sediment waves and non-depositional/erosional incisions, strongly suggest that sediment accumulation was controlled by bottom-current activity. We interpret the mounds as small-scale (< few tens of km² in area) lacustrine drifts. Four basic types of geometry are identified: 1) slope-plastered patch sheets; 2) patch drifts; 3) confined drifts; 4) fault-controlled drifts. The general asymmetry in the sedimentary cover of the ridge, showing thicker deposits on the NW flank, and the common location of patch drifts on the northeast side of small basement knolls indicate that deposition took preferentially place at the lee sides of obstacles in a current flowing northward or sub-parallel to the main contours. Deep-water circulation in the ridge area is not known in detail, but there are indications that relatively cold saline water masses are presently flowing out of the Central Basin and plunging into the deep parts of the North Basin across the ridge, a process that appears to be driven mainly by small differences in salinity. We infer that the process responsible for the observed bottom-current-controlled sedimentary features has to be sought in these large-scale water-mass movements and their past equivalents. The age of the onset of the bottom-current-controlled sedimentation, based on an average sedimentation rate of 4.0 cm/ky, is roughly estimated to be as least as old as 3.5 Ma, which is generally regarded as the age of the onset of the last major tectonic pulse of rift basin development in the Baikal region.     

On the use of current meter data to assess the realism of ocean model simulations

The evaluation of ocean simulations against observed datasets is essential to assess their realism and to guide model development, but often remains qualitative, and ignores certain datasets. This paper presents a three-dimensional, quantitative comparison of a 1/6° Atlantic numerical simulation (CLIPPER) with the WOCE current meter dataset in terms of mean velocity and eddy kinetic energy. Our metrics reveal the good behaviour of CLIPPER open boundary conditions and forcing with respect to full-depth current records. Due to its still moderate resolution, however, the model globally underestimates the observed mean speeds and eddy activity. This discrepancy is barely noticeable at low latitudes but increases toward the poles, probably since the poleward decrease of the Rossby radius exceeds that of the horizontal grid step. At least in this eddy-admitting regime, it is suggested that the numerics of geopotential-coordinate models like ours dissipate mean and eddy momentum at depth and adversely affect current–topography interactions.     

光生物反应器中光衰减特征与螺旋藻生长动力学研究

分析了光照强度在光生物反应器中的分布特征，结果表明，当光波长及光传播的路径确定时，光生物反应器中光衰减特征主要受培养物生物量浓度的影响，由回归的模型对实验数据的拟合可分析光衰减特征与培养物生物量浓度的相关性，为光生物反应器中平均光照强度的确定奠定基础。在光生物反应器中，当营养底物和环境温度不是螺旋藻生长限制因子时，通过平均光照强度对螺旋藻比生长速率的影响分析，结果表明，在实验条件下，螺旋藻比生长速率与平均光照强度的动力学模型可用Aiba光生长抑制方程描述，光亲和系数Ks为238.29umol/(m^2.s)，光抑制系数Ki为0．00493s.m^2/umol，光生物反应器中螺旋藻生长的饱和光照强度出现在190－272umol/(m^2.s)的范围内。     

海洋细菌抑菌活性菌株的筛选

从不同海区的海洋底质，生物样，水样中分离到480株海洋细菌，其中包括150株芽孢细菌和108株粪大肠杆菌，利用纸片法对其抑菌活性进行检测，结果表明：117株海洋细菌具有抑菌活性，占总分离菌株的24.4%；一般细菌，芽孢细菌，粪大肠杆菌的抑菌活性菌株分别占各供测菌株的17.1%,27.3%,35.2%；抑菌活性菌株的比例与样品来源密切相关，且各类海洋细菌的抗菌谱有很大的不同。     

High-resolution measurements of chromophoric dissolved organic matter in the Mississippi and Atchafalaya River plume regions

Chromophoric dissolved organic matter (CDOM) was measured in the spring and summer in the northern Gulf of Mexico with the ECOShuttle, a towed, instrumented, undulating vehicle. A submersible pump mounted on the vehicle supplied continuously flowing, uncontaminated seawater to online instruments in the shipboard laboratory and allowed discrete samples to be taken for further analysis. CDOM in the northern Gulf of Mexico was dominated by freshwater inputs from the Mississippi River through the Birdfoot region and to the west by discharge from the Atchafalaya River. CDOM was more extensively dispersed in the high-flow period in the spring but in both time periods was limited by stratification to the upper 12 m or so. Thin, subsurface CDOM maxima were observed below the plume during the highly stratified summer period but were absent in the spring. However, there was evidence of significant in situ biological production of CDOM in both seasons.The Mississippi River freshwater end member was similar in spring and summer, while the Atchafalaya end member was significantly higher in the spring. In both time periods, the Atchafalaya was significantly higher in CDOM and dissolved organic carbon (DOC) than the Mississippi presumably due to local production and exchange within the coastal wetlands along the lower Atchafalaya which are absent along the lower Mississippi. Nearshore waters may also have higher CDOM due to outwelling from coastal wetlands. High-resolution measurements allow the differentiation of various water masses and are indicative of rapidly varying (days to weeks) source waters. Highly dynamic but conservative mixing between various freshwater and marine end members apparently dominates CDOM distributions in the area with significant in situ biological inputs (bacterial degradation of phytoplankton detritus), evidence of flocculation, and minor photobleaching effects also observed. It is clear that high-resolution measurements and adaptive sampling strategies allow a more detailed examination of the processes that control CDOM distributions in river-dominated systems.     

Iodine chemistry in deep anoxic basins and overlying waters of the Mediterranean Sea

Iodate (IO₃⁻) is the predominant dissolved species of iodine in the oxygenated waters of the Mediterranean Sea. Iodide (I⁻) is present in significant quantities (up to 65 nM) in oxygenated waters in the photic zone and near the interface above the anoxic and saline Bannock Basin. Lesser quantities of I⁻ (< 10 nM) are found throughout the rest of the oxic water column. An additional unidentified dissolved iodine species is present immediately above the anoxic interface.Total dissolved iodine (ΣI) increases dramatically across the seawater/brine interface. Part of this increase is undoubtedly the result of the dissolution of iodine-rich evaporites during formation of the brine bodies at the Tyro and Bannock Basins. The vertical distribution of ΣI and other dissolved chemical species (particularly PO₄³⁻) in the Bannock Basin brine, however, suggests an additional, present-day, diagenetic source of dissolved iodine to the brine. Based on the increase in the concentration of the most soluble major ions across the seawater/brine interface, 5–7 μM of the 11.5-μM increase in ΣI concentration must be attributed to diagenesis.     

不同光照条件下海带体内各种化合物的含量及光合作用和呼吸作用的变化

实验检测了不同光照条件1200，600，01x下，海带体内多酚类化合物、可溶性糖、可溶性蛋白、叶绿素a、类胡萝卜素等的含量及其光合作用和呼吸作用的变化。实验结果表明，随着光照强度的减弱，海带体内多酚类化合物、可溶性糖、可溶性蛋白等的含量及其光合作用和呼吸作用均呈现下降的趋势，而叶绿素a和类胡萝卜素的含量则呈现出上升的趋势。