CHANGES ON EEG DURING SIMULATED N2-O2 SATURATION DIVING

During N2-O2 simulated saturation at a depih of 36.5 m the frequency, amplitude and index of a waves decreased and the activities of β and θ wave increased on the EEGs at rest. After the pressure was decompressed to normal, they could recover to the predive level. During the air excursion diving at depths of 60 and 70 m , the paramenters of EEG approximated to those of N2-O2 exposure. But at that time of the air excursion diving at a depth of 75 m they appeared the maximum. This showed that the changes related to the nitrogen partial pressure. There was an increase in slow waves during the simulated N2-O2 saturation. The activities of slow wave decreased on the EEGs in case of hyperventilation. The photic scimulation to the eyes caused the slow wave to disappear, and a rhythm could recover temporarily. When the photic stimulation was over the slow rhythm reappeared on the EEG. All the changes in EEG indicated that the encephalon function of the human body showed a gradual adaptation process during the     

OBSERVATION OF HUMAN EEG AND TREMOR DURING SIMULATED He-O2 SATURATION DIVING AT A DEPTH OF 302 METRES

EEG and tremor of three divers are recorded during simulated He-O2 saturation diving at a depth of 302 m. The results ate as follows:1.During the exposure to He-O2, a decrease in a rhythm and increase in activity of 8 and wave appear in subjects' EEGs and sometimees characteristics with sleep stage I are shown in individual EEG,2.During the exposure to He-O2. the increase in the amplitude of postural tremor in 4-8 Hz and 8-13 Hz is recorded and the increase of the amplitude of 8-13 Hz is more noticeable.3. During the exposure to He-O2, all the divers suffered from fatigue, poor sleep and memory failure. These symptoms accorded with the records of the subjects' EEG and tremor.     

DECOMPRESSION FROM NITROGEN OXYGEN SATURATION DIVING

Nine experiments were carried out on 39 healthy male adults for a total of 54 decompressions from N2-O2 saturation diving at the denths of 20-50 m. Excess supersaturation pressures of nitrogen dissolved in 1200 min tissue were calculated at all depths in decompression. In Exp. Ⅷ when chamber pressure was decompressed from 50 m to 35 m, a slight decompression sickness occurred, while AAAP1200 reached 7.05 m. Based on the above-mentioned analysis and calculation, the stage decompression schedules of N2-O2 saturation exposure at 36.5 m were revised.     

模拟36.5米氮氧饱和潜水26昼夜和60、70及75米空气巡潜对人体脑电图的影响

饱和潜水技术能提高水下作业效率,还可藉巡回潜水来增加水下作业深度,因此从六十年代以来在世界潜水技术先进国家中得到迅速发展,目前已成为进行潜水作业的一种重要手段.在空气潜水中,脑功能的变化早就引起人们的注意,高压氮会引起人体象酒精中毒样的麻醉症状,因此,一些水下生理和医学家们不但把脑电图作为潜水员选拔的体检指标,而且还用作潜水时健康检查和监护的重要手段.关于长期暴露于高气压环境下人体脑电图变化的研究尚属少见.本工作系统地记录了模拟36.5米氮氧饱和和潜水26昼夜各时期及进行不同深度空气巡潜时的脑电图,以探索长期暴露于高压氮氧环境对人体脑电图的影响以及适应过程中的变化规律.     

The carbonate system in the central South China Sea

The Clements of the carbonate system (HCO3- , CO32-, CO2, ·CO2 and Pco2) in the central South China Sea have been calculated by determining the pH values and total alkalinity of the seawater samples collected at 42 stations, combining simultaneously with the data of the temperatures, salinity and depths. The distributions of their characteristics have been briefly described and discussed. The saturation degrees (Ω) of calcite and aragonite in the studied area have also been evaluated. The ΩcaIc- and Ωarag. in the surface waters are about 5.8 and 3.9, respectively. The saturation depth is about 2200m for calcite and 1200m for aragonite. The lysocline in the studied area probably lies between 3000 m and 4000 m where the saturation degree of calcite is approximately 0.78.     

热带北太平洋西部固氮速率及固氮微生物组成

In the present study, we report N_2 fixation rate(~(15)N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N_2 fixation activity and diazotroph community structure showed the dominance of unicellular N_2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N_2 fixation.In surface waters, volumetric N_2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with 10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N_2 fixation rate over the upper 200 m ranged between 150 μmol/(m~2·d)and 480 μmol/(m~2·d)(average(225±105) μmol/(m~2·d). N_2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N_2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N_2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.     

Experimental study on the 350 msw simulated heliox saturation-370 msw excursion diving

-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 1989, 4 naval divers entered the habital of NMRI's 500 msw saturation diving system after a series of adaptive diving training. The breathing mixture was helium-oxygen. After 55 h compression (including intermediate stages) the 350 msw depth was reached, where the divers lived and worked for 72 h 10 min. No sign of discomfort or significant HPNS was found in the 4 divers.The second and third day of the saturation exposure, the divers carried out 370 msw dry and wet chamber excursion diving 2 man-time each, the divers effectively carried out operational work under water, the total excursion time was 1 h each excursion dive.Saturation decompression started after 3-day storage exposure, the divers were gradually brought toward the surface 25 msw a day on the average by employing the linear stead     

Using triple oxygen isotopes and oxygen-argon ratio to quantify ecosystem production in the mixed layer of northern South China Sea slope region

Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_2/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn) and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination of δ~(17)0,δ~(18)O,and the O_2/Ar ratio of dissolved gases.Gross oxygen production(GOP) was estimated using the triple oxygen isotopes of the dissolved O_2,and net oxygen production(NOP) was calculated using O_2/Ar ratio and O_2 concentration.The vertical mixing effect in NOP was calibrated via a N_2O based approach.GOP for autumn and spring was(169±23) mmol/(m~2·d)(by O_2) and(189±26) mmol/(m~2·d)(by O_2),respectively.While NOP was 1.5 mmol/(m~2·d)(by O_2) in autumn and 8.2 mmol/(m~2·d)(by O_2) in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5% error in the GOP and NOP estimations.A comparison with an independent O_2 budget calculation in the diel observation indicated a26% overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.     

Surface sediment carbonate mineralogy and water column chemistry: Nicaragua Rise versus the Bahamas

Periplatform surface sediments were studied for carbonate mineralogy in conjunction with analyses of the water column for carbonate chemistry on the eastern Northern Nicaragua Rise (NNR) in the Caribbean Sea. The results show a strong correspondence between variations and disappearance, with increasing water depth, of metastable carbonate minerals (fine aragonite and magnesian calcite) and their respective saturation levels in the overlying waters. Similar correspondence between variations in sediment proportions of fine aragonite and magnesian calcite and their respective saturation levels has previously been established in the Bahamas. There are, however, significant differences between the two areas. The sharp decrease in aragonite content and the measured aragonite saturation level occur at 4000 m in the Bahamas, compared to 1800 m on the eastern NNR. In both areas, magnesian calcite minima correspond to the in situ PCO₂ maxima in the water column. The magnesian calcite minimum, however, is at 950 m in the Bahamas and 750 m on the eastern NNR. Magnesian calcite disappears in the Bahamas at 3800 m and at 2000 m on the eastern NNR. These results demonstrate the importance of the influence of overlying water chemistry on the preservation of metastable carbonate minerals in off-bank periplatform sediments, and they clearly demonstrate the difference in terms of carbonate preservation between the poorly ventilated waters of the Caribbean Sea and the well-oxygenated waters of the adjacent Atlantic Ocean. They also open the possibility of obtaining paleoceanographic information on the depth of the CO₂ maximum (O₂ minimum) and its separation from the aragonite saturation depth in at least some areas.     

Comparative assessment of nitrogen fixation rate by 15N2 tracer assays in the South China Sea

Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes. The distribution, controlling factors, and flux of N₂ fixation in the global ocean remain uncertain, partly because of the lack of methodological uniformity. The 15N₂ tracer assay (the original bubble method → the 15N₂-enriched seawater method → the modified bubble method) is the mainstream method for field measurements of N₂ fixation rates (NFRs), among which the original bubble method is the most frequently used. However, accumulating evidence has suggested an underestimation of NFRs when using this method. To improve the availability of previous data, we compared NFRs measured by three 15N₂ tracer assays in the South China Sea. Our results indicate that the relationship between NFRs measured by the original bubble method and the 15N₂-enriched seawater method varies obviously with area and season, which may be influenced by incubation time, diazotrophic composition, and environmental factors. In comparison, the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable, indicating that the N₂ fixation rates based on the original bubble methods may be underestimated by approximately 50%. Based on this result, we revised the flux of N₂ fixation in the South China Sea to 40 mmol/(m2·a). Our results improve the availability and comparability of literature NFR data in the South China Sea. The comparison of the 15N₂ tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N₂ fixation in the marine nitrogen cycle.     

Manned Testing of the Diver Gas Recovery Installation

The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, breathing gas flow rate and consumption, inspired oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2) were monitored. The results indicated that PO2 was controlled to fluctuate from 64.3 to 84.0 kPa and PCO2 went up from 0.01 kPa up to O.I kPa during 4 hours excursion diving; recovery of breathing gas reached 95%; three divers felt well and breathed comfortably during simulating heavy work. The test showed that it met desired performance goals. The DGRI is a kind of important equipment for long duration deep dive. It enables the gases exhaled by the divers to be re-cycled, and therefore it has great social, military and economic significance for diving operation and submarine rescue.     

Preliminary study on nanodiatom in the Taiwan Strait

INTRODUCTIONNanophytoplanktonhasbecomeanewresearchfieldsincethe1980s.Amongthis,nanodiatom(<20pm)isthemajorflora.ItisthefoodforaqUaticanimalsandtheimPOrtantlinkoffoodchain.NanodiatomisanimPOrtantoceanicprimaryproducer(WeberandEI-Sayed,1987;Gao,1990;ChenandQian,1992;Chengetal.,1993).Manyscholarshavedonealotoftaxonomicandecologicalworkonnanodiatom.InChina,monographswerepublishedbyProfessorT.G.Chin(JinDe-clang)(1965,1982and1992),butthoseworksfocusedonmorphologicalandecologicalcharact…     

潮优型河口动力对水深变化的响应机制研究——以葡萄牙Guadiana河口为例*

强人类活动(如航道疏浚)和自然气候变化(如海平面上升)对近岸河口环境不同影响的辨识是目前河口海岸学研究的热点和难点问题。在地形概化和动力简化条件下, 解析模型能够快速辨识强人类活动和自然气候变化对河口环境的影响, 它是探讨河口动力过程对外界干扰的响应机制的重要工具。本文基于前人对葡萄牙Guadiana河口不同分潮之间非线性相互作用的研究, 采用一维水动力解析模型探讨河口不同分潮潮波传播过程对水深变化(模拟航道疏浚和河道淤积过程)的响应机制。研究结果表明: 平均水深$\overline{h}$的变化影响无量纲河口地形参数γ和摩擦参数χ, 进一步影响河口动力参数包括潮波振幅参数ζ、流速振幅参数μ、波速参数λ、潮波振幅增大/衰减率参数δ以及流速与水位之间的相位差?等; 平均水深变化对河口中下游段(x=0~60km)的潮汐动力影响较大, 而对河口上游段(x=60~78km)影响较弱; 主要半日分潮(M₂、S₂、N₂)对水深变化的响应略大于全日分潮(K₁、O₁); 航道疏浚幅度小于2m时, 对河口潮汐动力格局影响不大, 而当疏浚幅度大于2m时, 将对河口潮汐动力格局及水环境(如盐水入侵等)产生较大影响; 河道淤积将导致潮汐动力减弱, 流速振幅、潮波振幅及传播速度减小, 流速和水位之间的相位差也减小。     

畸形波作用下双层水平板防波堤压力分布特性研究

基于物理模型试验,考虑畸形波参数、相对板宽、相对波高等影响因素,就畸形波对平顶双层水平板防波堤作用进行研究。首先对畸形波作用下双层水平板的波浪力分布特征进行了讨论,然后就最大波动压强、结构最大总垂向力与不规则波作用进行了对比分析。结果表明,畸形波作用下,双层水平板最大波动压力出现在前端迎浪区域附近,向尾端逐渐递减。双层水平板4个受力面的压力分布不同且有相位差,4个受力面的最大波动压力时间差约在0.1T_p~0.4T_p范围内变化。与不规则波作用比较,畸形波作用没有显著改变波压包络分布特征,但增大了波压包络强度值。试验范围内,就最大总力而言,两者最大总浮托力比值在1.06~2.45间变化;向下的最大总垂向力比值在1.22~2.07之间变化;就波动压力而言,其增大的幅度与畸形波参数α₁相关性最强,随α₁的增大而增大,在α₁=2.04~3.1试验范围内,畸形波作用时的最大压强比不规则波作用时可约增大20%~80%。就最大波吸力而言,两者的比值与畸形波参数α₄相关性最强,随α₄的增大而减小。在α₄=0.62~0.75试验范围内,最大波吸力强度的比值在1.61~0.87范围内变化。当α₄≤0.72时,畸形波作用时的最大波吸力大于不规则波作用时的最大波吸力;当α₄ > 0.72时则刚好相反。     

南海西北部上层海洋对台风“杜苏芮”的响应分析

基于锚碇观测资料,本文分析了南海西北部陆坡区上层海洋对台风“杜苏芮”的动力学和热力学响应特征。在动力学响应方面,台风“杜苏芮”期间上层流速显著增强,混合层纬向流速可达1.20 m/s;“杜苏芮”经过后上层海水运动以近惯性振荡为主(流向顺时针旋转周期在36～40 h之间)。近惯性能量在垂向分布上存在两个高值中心,分别位于混合层和温跃层深度上。近惯性能量耗散过程的e折时间尺度约为3.7 d,我们认为能量的向下传播在局地近惯性能量衰减过程中起主要作用。对能量谱的分析表明,“杜苏芮”作用期间近惯性频率能量相对于其作用前增大了约29.4倍,而全日和半日频率(K₁和M₂)能量有所减弱。此外,能量谱显示近惯性频率存在明显的“蓝移”现象,即对于纬向和经向流速分量在400 m以浅平均的近惯性振荡频率分别为1.167 f₀和1.170 f₀(f₀为局地惯性频率)。蓝移与近惯性内波的向下传播及正的相对涡度的输入有关。在热力学响应方面,上层海洋在台风的搅拌作用下,40～250 m深度均出现较小增温,最大增温幅度接近1°C;此外70 m以浅盐度的降低可能与台风过境时的降水相关,而Ekman抽吸引起的上升流则可能对70～100 m深度盐度的升高具有重要作用。     

自组装膜进样质谱系统及其在砂质沉积物异化硝酸盐还原研究中的应用

沉积物中的异化硝酸盐还原过程对于海洋氮循环起着至关重要的作用。基于15N标记的培养技术是目前测定沉积物异化硝酸盐还原的主要手段。准确快速测定15N标记的产物(29N2、 30N2)是量化异化硝酸盐还原各个过程速率的关键。本研究自行组装膜进样质谱系统用于29N2和30N2的测定,对其测量条件进行了优化。结果表明,进样蠕动泵进样流速0.80 mL/min,进样时间3~3.5 min,恒温槽温度20~25℃,同时铜还原炉温度在300~600℃的条件下,^29N2/^28N2和^30N2/^28N2的测试精密度分别可以控制在0.1%和1%以内,比较适合29N2和30N2的测定。利用自组装的膜进样质谱系统结合15N标记的培养技术研究了青岛石老人沙滩沉积物中的异化硝酸盐还原过程。石老人沙滩沉积物不存在将硝酸盐完全还原为氮气好氧的反硝化。厌氧铵氧化、厌氧反硝化和异化硝酸盐还原为铵(Dissimilatory Nitrate Reduction to Ammonium,DNRA)的潜在速率(以湿沉积物N计)分别为(0.05±0.01) nmol/(cm^3·h),(2.32±0.21) nmol/(cm^3·h)和(1.02±0.15) nmol/(cm^3·h)。厌氧反硝化是硝酸盐异化还原主要的贡献者,其比例接近70%,其次是DNRA,比例可达30%,而厌氧铵氧化的贡献最低,仅为1%。在N2产生过程中,主要贡献者是反硝化,厌氧铵氧化的贡献仅为2%。     

伶仃洋洪季潮波传播变形及不对称性规律分析

珠江河口伶仃洋水域潮波传播变形及其不对称性关系对河口动力环境和物质输运产生影响。研究根据珠江口伶仃洋及东四口门19个潮位站2011年6月实测逐时潮位, 利用收缩河型沿程潮幅解析理论, 阐释伶仃洋从桂山岛上行沿程潮汐传播规律特征; 在调和分析基础上, 应用偏度理论和分潮组合分析方法, 阐明了伶仃洋东西岸及洪奇门、蕉门内潮汐不对称性分布特征, 对照数值研究结果, 指出伶仃洋至虎门之间水域导致潮汐不对称性的主控因素及响应规律。研究表明, 河口平面形态呈近似指数收缩特征的伶仃洋, 沿程潮幅的变化符合指数收缩型河口波幅解析变化规律, 东岸潮幅高于西岸的主要原因是东岸水深大于西岸, 其次是科氏力影响; 行进潮波虽受地形摩擦耗能及非线性作用下不同频率分潮间能量迁移的影响, 但收缩河口能量汇聚效应可以保证收缩段天文分潮潮幅减缓衰减甚至增加, 半日分潮能量汇聚效果强于全日分潮, 各非线性项作用促使浅水分潮产生并持续增能, 保证一定距离内沿程潮幅的增大; 潮汐不对称性的偏度由湾口落潮占优向湾顶涨潮占优发展, 在伶仃洋中部赤湾至金星港一线转为涨潮占优, 产生该现象的原因是自湾口向湾顶不同频率间天文分潮K₁-O₁-M₂的相互作用, 导致表现为落潮优势潮的不对称性减弱, 而天文分潮M₂和其对应的浅水分潮倍潮M₄组合作用使涨潮优势偏度值的不对称性增强; 收缩河口形态属性要素中, 水深是影响潮不对称性的最主要因素。     

雷州市沿海风暴潮淹没危险性评估*

文章基于近岸海洋数值模式ADCIRC (a parallel advanced circulation model for oceanic, coastal and estuarine waters)和近海波浪数值模式SWAN (simulating waves nearshore), 建立雷州市高分辨率的风暴潮-海浪耦合漫滩数值模型, 并反演了对雷州市影响较为严重的1415号台风“海鸥”的风暴潮过程。经过对比分析得出, 波浪对雷州市沿海海域的风暴潮产生重要影响。然后以8007号台风路径为基础, 构造了7个不同等级共35组台风风暴潮案例, 计算分析出不同等级台风强度下雷州市风暴潮淹没范围及水深。900hPa等级下, 雷州市淹没面积达到463.2km²。文章还构造了60组可能最大风暴潮事件集, 计算得到雷州市可能最大台风风暴潮淹没范围及水深分布。在可能最大台风影响下, 大量海水将漫过海堤, 造成极其严重的淹没灾害, 雷州市总的淹没面积可达602.0km², 其中465.8km²的淹没面积达到了危险性等级 Ⅰ 级, 淹没水深大于3m。雷州市东岸的淹没灾害大于西岸。     

Top-down control on major groups of global marine diazotrophs

Dinitrogen (N₂) fixed by a group of prokaryotes (diazotrophs) is the dominant process adding bioavailable nitrogen into the ocean. Although it has been intensively studied how N₂ fixation is controlled by resources (bottom-up factors), it is unclear whether the grazing (top-down control) effectively impacts growth and distribution of different diazotroph groups. In this study, we evaluate this question by conducting log-log regression of diazotroph biomass onto corresponding N₂ fixation rates in the global ocean. The slope of the regression for Trichodesmium is ~0.8, indicating that a small portion of the increase in N₂ fixation does not accumulate as its biomass. This leads to a conclusion that Trichodesmium is under a substantial top-down control, although bottom-up control still dominates. We also analyze the residuals of the regression in the North Atlantic, concluding that free trichomes of Trichodesmium are subject to stronger top-down control than its colonies. The weak correlation between the biomass and N₂ fixation of unicellular cyanobacterial diazotrophs indicates that the degree of top-down control on this type of diazotrophs varies greatly. The analyses obtain unrealistic results for diatom-diazotroph assemblages due to complicated nitrogen sources of these symbioses. Our study reveals the variability of top-down control among different diazotroph groups across time and space, suggesting its importance in improving our understandings of ecology of diazotrophs and predictions of N₂ fixation in biogeochemical models. Measurements of size-specific N₂ fixation rates and growth rates of different diazotroph groups can be useful to more reliably analyze the top-down control on these key organisms in the global ocean.     

畸形波作用下锚泊方柱系泊张力特性研究

基于物理模型试验,探究畸形波和不规则波作用下浮体系泊张力差异问题。讨论相对波高、相对周期和畸形波参数α₁对系泊张力的影响。结果显示:畸形波参数α₁和浮体系泊张力显著相关。在α₁=2.0～2.83范围内,畸形波作用下迎浪侧系泊张力最大值可达不规则波作用的1.9倍。在相对波高H_s/d=0.032～0.097范围内,畸形波作用下迎浪侧系泊张力最大值显著大于不规则波的作用结果,但畸形波和不规则波对应的1/3值及平均值几乎一致。就相对周期影响而言,迎浪侧系泊张力最大差别出现在谱峰周期T_p0p范围内。频域方面采用小波分析方法讨论畸形波和不规则波作用下浮体系泊张力时频谱特征,两种波浪作用下系泊张力时频特征有显著差别。