Water Masses in the South China Sea and Water Exchange between the Pacific and the South China Sea

Water masses in the South China Sea (SCS) were identified and analyzed with the data collected in the summer and winter of 1998. The distributions of temperature and salinity near the Bashi Channel (the Luzon Strait) were analyzed by using the data obtained in July and December of 1997. Based on the results from the data collected in the winter of 1998, waters in the open sea areas of the SCS were divided into six water masses: the Surface Water Mass of the SCS (S), the Subsurface Water Mass of the SCS (U), the Subsurface-Intermediate Water Mass of the SCS (UI),the Intermediate Water Mass of the SCS (I), the Deep Water Mass of the SCS (D) and the Bottom Water Mass of the SCS(B). For the summer of 1998, the Kuroshio Surface Water Mass (KS) and the Kuroshio Subsurface Water Mass (KU) were also identified in the SCS. But no Kuroshio water was found to pass the 119.5°E meridian and enter the SCS in the time of winter observations. The Sulu Sea Water (SSW) intruded into the SCS through the Mindoro Channel between 50-75 m in the summer of 1998. However, the data obtained in the summer and winter of 1997 indicated that water from the Pacific had entered the SCS through the nor-thern part of the Luzon Strait in these seasons, but water from the SCS had entered the Pacific through the southern part of the Strait. These phenomena might correlate with the 1998 El-Nio event.

On the heat budget and water mass exchange in the Andaman Sea

The characteristics of the T/S structures,water mass exchange and deep circulation in the Andaman Sea are investigated based on the simulation from a high-resolution general circulation model(MITgcm).The results show that,below 1000 m,the water mass is saltier,warmer and more homogeneous in the Andaman Sea than that in the Bay of Bengal,attributing to the strong vertical mixing at the depth of^1800 m.The water mass exchange between the Andaman Sea and the Bay of Bengal goes through three major channels,which manifests itself as follows:the northern channel(Preparis Channel)is the main passage of water mass transport from the Bay of Bengal to the Andaman Sea,whereas the Middle Channel(the south of Andaman Islands and the north of Nicobar Islands)has an opposite transport;the southern channel(Great Channel)features with a four-layer water exchange which results in the least net transport among the three channels;all the transports through the three channels have an intra-annual variation with a period of half a year.At 1000-m depth,the entire Andaman Sea is occupied by a cyclonic circulation in January and July while by an anticyclonic one in April and October.The semiannual cycle found in both the deep circulation and water mass exchange is likely associated with the downwelling eastward-propagating Kelvin waves induced by the semiannual westerly component in the equatorial Indian Ocean during intermonsoon seasons.

Patterned catalyst layer boosts the performance of proton exchange membrane fuel cells by optimizing water management

Mass transport is crucial to the performance of proton exchange membrane fuel cells,especially at high current densities.Generally,the oxygen and the generated water share same transmission medium but move towards opposite direction,which leads to serious mass transfer problems.Herein,a series of patterned catalyst layer were prepared with a simple one-step impressing method using nylon sieves as templates.With grooves 100μm in width and 8μm in depth on the surface of cathode catalyst layer,the maximum power density of fuel cell increases by 10%without any additional durability loss while maintaining a similar electrochemical surface area.The concentration contours calculated by finite element analysis reveal that the grooves built on the surface of catalyst layer serve to accumulate the water nearby while oxygen tends to transfer through relatively convex region,which results from capillary pressure difference caused by the pore structure difference between the two regions.The separation of oxidant gas and generated water avoids mass confliction thus boosts mass transport efficiency.

Definition of water exchange zone between the Bohai Sea and Yellow Sea and the effect of winter gale on it

The marine dynamic environment of the Bohai Sea and the Yellow Sea in the winter of 2006 is simulated by the Regional Ocean Modelling System（ROMS） marine numerical model. Using the simulated temperature and salinity, the water exchange zone between the Bohai Sea and Yellow Sea is defined through the Spectral Mixture Model（SMM）. The influence of winter gales on the water exchange is also discussed. It is found that the Yellow Sea water masses in winter are distributed in a ＂tongue＂ shape in the Bohai Strait region, the water exchange zone presents a zonal distribution along the margin of the ＂tongue＂, with a tendency of running from northwest to southeast, and the water exchange is intensified at the tip of the ＂tongue＂. Besides, the coastal area in the northernmost Yellow Sea does not participate in the water exchange between the Bohai Sea and Yellow Sea. The result shows that the winter gale events play a role in enhancing the water exchange. It is specifically shown by the facts： the Yellow Sea warm current is enhanced to intrude the Bohai Sea by the gale process; the water exchange zone extends into the Bohai Sea; the water exchange belt in the southern part becomes wider; the mixture zone of river runoff with the Bohai Sea water upon its entry is enlarged and shifts northwards. Within two days after the gale process, the exchange zone retreats toward the Yellow Sea and the exchange zone resulted from the Huanghe River（Yellow River） runoff also shrinks back shoreward.

High-performance porous transport layers for proton exchange membrane water electrolyzers

Hydrogen is a favored alternative to fossil fuels due to the advantages of clean-liness,zero emissions,and high calorific value.Large-scale green hydrogen production can be achieved using proton exchange membrane water electrolyz-ers(PEMWEs)with utilization of renewable energy.The porous transport layer(PTL),positioned between the flow fields and catalyst layers(CLs)in PEMWEs,plays a critical role in facilitating water/gas transport,enabling electrical/thermal conduction,and mechanically supporting CLs and membranes.Superior cor-rosion resistance is essential as PTL operates in acidic media with oxygen saturation and high working potential.This paper covers the development of high-performance titanium-based PTLs for PEMWEs.The heat/electrical con-duction and mass transport mechanisms of PTLs and how they affect the overall performances are reviewed.By carefully designing and controlling substrate microstructure,protective coating,and surface modification,the performance of PTL can be regulated and optimized.The two-phase mass transport char-acteristics can be enhanced by fine-tuning the microstructure and surface wettability of PTL.The addition of a microporous top-layer can effectively improve PTL|CL contact and increase the availability of catalytic sites.The anti-corrosion coatings,which are crucial for chemical stability and conductivity of the PTL,are compared and analyzed in terms of composition,fabrication,and performance.

混合型离子交换反相吸附固相萃取-超高效液相色谱-三重四极杆质谱法测定水中23种非甾体抗炎药的残留

非甾体抗炎药(NSAIDs)作为一种新型有机污染物,在环境水体中普遍检出,对生态系统及人体健康造成潜在的威胁,开发准确、可靠的测定水中痕量非甾体抗炎药的检测方法至为重要.本文采用Oasis MCX固相萃取柱对水样进行富集,建立测定水中23种非甾体抗炎药的超高效液相色谱-三重四极杆质谱分析方法.采用酸性条件(pH=4)萃取水样,上样的流速为2 mL·min^(−1),用4 mL甲醇-4 mL5%氨水甲醇进行洗脱,浓缩定容后用ACQUITY UPLCTM BEH C18柱(2.1 mm×100 mm,1.7μm),以2 mmol·L^(−1)乙酸铵+0.05%(V/V)甲酸水溶液-乙腈作为流动相进行梯度洗脱,多反应选择离子监测(MRM)模式进行检测,内标法定量.23种NSAIDs在相关线性范围内线性良好(r=0.9951—0.9992),回收率为80.2%—120%,相对标准偏差为0.4%—12.5%,方法检出限为0.20—4.84 ng·L^(−1).将该方法应用于10份地表水的检测,结果显示有10种NSAIDs检出,质量浓度在ND—83.5 ng·L^(−1)之间.该方法简单、灵敏、高效,可应用于环境水体中NSAIDs的检测.

具有堵块结构的PEMFC阴极流场的传质性能

建立具有堵块结构的质子交换膜燃料电池(PEMFC)阴极流场模型,分析堵块的布置方式(上方、下方、上下交错)和孔隙率对流道和扩散层内气体流动特征(速度、压力和氧气摩尔浓度等)的影响,以及对流道中间和出口处堵块的前中部位垂直于流道方向的传质影响。通过可视化实验分析液态水在具有不同堵块高度流场中的运动特性。当矩形堵块布置在流道上方时,在中间和出口处堵块的前中后部位都能获得更好的垂直于流道方向的传质性能;流道上方布置矩形堵块能加速液态水的排出。当堵块高度为50%流道高时,流场大多数液滴的灰度值为40~70,已经对流道造成堵塞;当堵块高度为70%流道高时,多数液滴的灰度值为70~90,且较多液滴分布在流道出口处,液态水排出较为通畅。

The influence of patterned microporous layer on the proton exchange membrane fuel cell performances

The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MPL)on the proton exchange membrane fuel cell performances.When patterned MPL is employed,grooves are generated between the catalyst layer and the gas diffusion layer.It is found that the grooves do not increase the contact resistance,and it is beneficial for water retention.When the MEA works under low humidity scenarios,the MEA with patterned MPL illustrated higher performance,due to the reduced inner resistance caused by improved water retention,leading to increased ionic conductivity.However,when the humidity is higher than 80%or working under high current density,the generated water accumulated in the grooves and hindered the oxygen mass transport,leading to a reduced MEA performance.

酸处理钛毡对质子交换膜电解槽性能的影响

多孔传输层是质子交换膜电解水制氢系统中关系到气水的高效输运和电子有效导通的重要部件。该文采用盐酸和草酸对商用钛毡进行蚀刻处理,获得具有优异电化学性能的酸处理钛毡。对酸处理后钛毡的表面形貌及元素成分表征说明:酸处理能有效去除钛毡表面的氧化层,并且不会对钛毡本身的化学性质和孔隙结构产生影响。接触电阻与电化学测试显示:酸处理后的钛毡接触电阻得到有效降低,相同电流密度下采用草酸处理钛毡的电解槽低至1.8V,较未处理钛毡电压下降10%。同时,得益于酸处理后钛毡微观结构和湿润性的变化,相较于普通钛毡,酸处理钛毡能显著优化电解槽运行中的传质过程。结果表明:采用质量分数为10%的草酸溶液80℃处理20min的钛毡具有最小的极化损失,能有效提高电解槽的运行效率。

图案化膜对PEMFC阴极质量传递的影响研究

为了探究图案化膜通过影响单电池内部水气输运机制进而影响电池性能这一中间机理过程,建立了质子交换膜燃料电池的单电池模型,并进行了数值仿真计算,对比了微孔图案膜和凸起图案膜的性能,发现微孔膜的效果更佳。探究了质子交换膜阴极表面微孔的半径和数量对燃料电池性能和阴极质量传递的影响。结果表明,微孔的存在可以起到一定的微储水作用,使膜的湿润性增加,进而利于质子传导,这也是相较于凸起膜,微孔膜性能更好的主要原因。随着微孔半径的增加,膜的储水能力增大,产生的电流密度逐渐变大。随着微孔数量的增多,膜表面水含量和电流密度也有一定的升高趋势,但趋势均不太明显。

直接接触式烟气加热系统热质交换效果稳态响应特征

针对直接接触式烟气加热系统热质交换稳态计算,基于四区段模型建立了稳态计算模型和方法,选取了出口水温、总带水量和有效换热量3项稳态评价指标。对比现场试验结果,出口水温模拟误差在±0.90℃内,相对误差在±5%以内,总带水量模拟误差在±0.40 m^(3)/h内,模拟结果较可靠。基于该模型和方法,建立了121组模拟工况情景,对热质交换稳态效果与入口烟气流量、烟气温度、烟气压力、烟气含水率、入口废水流量和废水换热温差之间的关系进行定量分析。结果表明:出口水温与入口烟气温度、烟气压力、烟气含水率呈线性正相关,与废水换热温差呈线性负相关,对入口烟气温度和烟气含水率变化较敏感,对烟气流量、入口废水流量不敏感;总带水量与入口烟气流量、烟气温度呈线性正相关,与烟气含水率和废水换热温差呈线性负相关,对烟气温度变化更敏感,与烟气压力和入口废水流量关系不显著;有效换热量与入口废水流量、废水换热温差呈线性正相关,与烟气流量、烟气温度呈线性负相关,对烟气压力和烟气含水率变化不敏感。相较烟气流量,出口水温更取决于入口烟气温度;总带水量同时取决于入口烟气流量和烟气温度,烟气流量较低时受烟气流量影响作用增大,烟气温度较低时受烟气温度影响作用增大。入口烟气含水率和烟气压力的波动对总带水量的影响可忽略不计,但对出口水温的影响应予以考虑和修正。对于温度85~140℃、含水率9%~18%的典型原烟气,气水比为2400 m^(3)/m^(3)(标况下)时,将废水换热温差控制在3.5℃以上,系统具备烟气收水的可能。

蒸发冷却用泡沫陶瓷填料不同流道形式的性能实验

以折线型和直线型两种流道形式的新型泡沫陶瓷填料为研究对象,利用搭建的蒸发冷却实验台,在三种典型工况下,对两种流道形式填料的性能参数进行试验测试与对比分析。结果表明:折线型和直线型流道形式的泡沫陶瓷填料,其最佳淋水密度分别为10.0kg/(m·h)和6.7kg/(m·h);在乌鲁木齐、西安、常州工况下折线型流道形式填料的最佳进口风速分别为1.6、1.4、1.2m/s,直接蒸发冷却效率可达83.01%、70.74%、67.43%;而直线型流道在3种工况下的最佳进口风速均为1.0m/s,直接蒸发冷却效率分别为77.68%、68.56%、64.23%;折线型流道相比于直线型流道而言,不易受风量变化影响,空气进出口温降稳定,更加适用于各种不同风量大小的蒸发冷却空调系统,但同时也需适当考虑风机的功耗问题。

1998年夏、冬季南海的水团及其与太平洋的水交换

根据 1998年夏季和冬季 2个航次的实测资料 ,对南海的水团进行划分和分析 ,并利用1997年 7月和 12月的实测资料 ,对巴士海峡 (吕宋海峡 )和民都洛水道附近的温盐分布进行分析。1998年冬季的资料分析结果表明 ,可将南海外海水划分为 6个水团 ,即南海表层水团 (S)、南海次表层水团 (U)、南海次 -中层混合水团 (UI)、南海中层水团 (I)、南海深层水团 (D)和南海底盆水(B)。 1998年夏季还可在南海中鉴别出黑潮表层水团 (KS)和黑潮次表层水团 (KU) ,但在冬季观测期间无黑潮水越过 119.5°E经线进入南海 ;夏季有苏禄海水在 5 0～ 75 m层经民都洛水道侵入南海。然而 ,1997年夏季和冬季的资料分析表明 :夏、冬两季都有大洋水通过吕宋海峡北段进入南海 ,南段有南海水流入太平洋。这些现象可能与 1998年前后的厄尔尼诺有关。

ICP-MS测量超痕量钚时质谱干扰的消除及水中钚的测定

研究了感应耦合等离子体质谱(ICP MS)测定超痕量钚时的质谱干扰及干扰元素的去除;建立了环境水样中超痕量钚的测定方法。方法所用的解吸液适于ICP MS直接进样,并有效地消除铅等元素形成的多原子离子干扰。测量了溶液中的m/z238和2%HNO3空白液中的239Pu和242Pu计数率,对测量结果进行校正。方法的本底为20fg,方法对239Pu的检出限为43fg,测定限为88fg。所分析的水样中,井水中的239Pu含量低于检出限,地表水中239Pu的含量高于检出限,湖水和河水中的239Pu高于测定限,但属于全球沉降引起的本底,不会对公众造成辐射危害。

冬季大风影响下的渤黄海水交换特征

利用ROMS海洋数值模式对2006年冬季渤黄海的海洋动力环境进行模拟,基于温度、盐度模拟结果,使用谱混合模型进行水团分析,定义了渤海海峡地区的水交换区。并进一步讨论了冬季大风事件对水交换区的影响,给出了冬季大风影响下的渤黄海水交换特征。研究得出,冬季的黄海水团以"舌"形分布于渤海海峡地区,水交换区则表现为沿"舌"形边缘呈带状分布,具有西北--东南的走向趋势,并且在"舌"尖处的水交换面积最大。通过缩小研究范围,发现位于黄海最北部的沿岸海域并不参与渤黄海之间的水体交换。最后研究发现,冬季大风事件对渤海水交换具有促进作用,具体表现为:大风过程使黄海暖流对渤海的入侵更加深入,水交换区向渤海方向伸展,南部的水交换带变宽,河流径流进入渤海后与渤海水的混合区加大,并发生北移。

干旱胁迫对青海杨不同种群的影响

通过对青海杨的两个分别来自极端干旱和湿润地区的种群进行不同水分处理,研究其在生物量的积累与分配、气体交换、脱落酸积累以及水分利用效率上的种群差异.结果表明:①不同种群在各种生长和形态指标上均表现出了显著性差异,例如株高(Ht)、基径(Bd)、总生物量(Tb)、总叶面积(La)和细根比(Ft).②不同种群在各种生理指标上也表现出了显著性差异,例如净光合速率(A)、蒸腾速率(E)、气孔导度(g)、水分利用效率(WUEi)和脱落酸(ABA)积累.③与来自湿润地区的种群相比,来自干旱地区的种群表现出了较小的生长和形态指标值以及较大的生理指标值.这些对水分可利用性的形态和生理适应性表明,不同种群在其幼苗早期生长和建立方面采用了不同的生存策略,来自湿润地区的杨树种群采用耗水策略从而抗旱性低,而来自干旱地区的杨树采用节水策略从而抗旱性高.这些对干旱的不同反应可以为不同气候地区选择相应的生态型提供一定的参考标准.

水中微量甲基膦酸类化合物的树脂富集与 GC/MS分析

本文使用三种阴离子交换树脂（即大孔弱碱型D-301-R、强碱型D-296,201X7）柱对水中微量甲基膦酸类化合物的富集方法进行了研究,含磷毒剂降解产物的水样用气相色谱/质谱法进行定性定量分析,结果表明,D-301-R阴离子交换树脂柱对甲基膦酸的富集回收率高于60％。

高集海堤打开后马銮湾开口对厦门东西海域的影响

随着厦门高集海堤打开及东西海域清淤工程实施,厦门海域边界条件和水动力环境均发生了较大变化.根据最新边界条件、地形条件和水文泥沙条件,通过数学模型研究打开马銮湾对厦门东西海域的影响.研究结果表明大潮条件下,高集海堤打开后,高集海堤处产生自西向东的净潮量为3 930亿m3,西海域的水体交换能力显著增强;进一步打开马銮湾后,增加的涨、落潮总潮量平均4 560亿m3,增加的潮量分别通过鼓浪屿断面和五通断面进出西海域和同安湾,分配比例接近1∶1.马銮湾开口可以增加东西海域水体交换能力,但东西海域水质是否改善取决于马銮湾水质情况.

床面粗糙度和底床渗透率对泥-水界面物质交换特性的影响

泥-水界面物质交换过程对自然水体中污染物的迁移转化起重要作用,粗糙底床界面物质交换过程涉及到床面粗糙度和底床渗透率的影响。通过实验室环形水槽实验测量得到水力粗糙砂质底床条件下界面物质交换通量的定量数据和变化特征,采用参数化方法分析有效扩散系数与其主要影响参数之间的依赖关系。实验结果表明,在实验参数变化范围内,受上覆水平均流速、床面粗糙度和底床渗透率的共同作用,有效扩散系数从水力光滑区、过渡粗糙区至完全粗糙区呈现较为明显的分段变化特征,采用渗透率雷诺数可将有效扩散系数与其主要影响参数的依赖关系进行较为一致的描述。基于双参数(粗糙雷诺数和渗透率雷诺数)分析,确定了不同流动区域的相应阈值以合理表征床面粗糙度和底床渗透率对界面物质交换特性的综合影响。

赤道印度洋中部断面东西水交换的季节变化及其区域差异

采用海洋再分析资料和实测资料研究了热带印度洋中部东西水交换特征。结果表明存在两个相互独立的过程,即北印度洋过程(4°～6°N)和赤道过程(2°S-2°N)。北印度洋过程受季风影响显著,11月至翌年3月冬季风期间表现出很强的低盐水向西输送,5-9月夏季风期间则为高盐水向东输送;由于冬季风期间的输送较强,年平均表现为低盐水向西输送。赤道过程分为表层过程和次表层过程。表层赤道过程受局地风场驱动,有明显的半年周期;4-5月和10-11月的东向流将赤道西印度洋的高盐水向东输送,其余月份相反;向东的输送较强,年平均表现为净高盐水向东输送。在次表层赤道过程没有明显的季节变化,海流全年一致向东,将海盆西部的高盐水向东输送。