四种电化学分析仪器的研制

本报告介绍我们实验室以原有研究工作为基础，结合国家十五科技攻关课题，适应市场需要，研发的生化需氧量(BOD)快速监测仪、溶氧(DO)在线检测仪、毛细管电泳电化学发光检测仪(CE/ECL)、USB插头式超微型电化学研究系统(uECS)等四种电化学分析仪器。BOD、DO仪采用纳米、自组装等技术制作电化学探头，可实现对水体中的BOD、DO的快速、灵敏的检测，所得结果与使用传统的方法相一致，而所需时间很短，可以实时、在线监测;CE/ECL仪系结合了毛细管电泳的高分离能力和电化学发光的高灵敏度的特点开发出的整体仪器;uECS突破了原有电化学分析仪器的概念，结合了先进的USB2.0技术，整个系统体积小巧(如U盘)，通过计算机的USB接口提供电源并进行高速数据传输，具有一般研究型电化学仪的各项功能，并且具有较强的可扩展性。

Robust core-shell supramolecular assemblies based on cationic vesicles and ring-shaped {Mo-154} polyoxomolybdate nanoclusters: Template-directed synthesis and characterizations

Substantial progress has been made recently in extending the supramolecular assembly of biomimetic structures to vesicle-based sophisticated nanocomposites and mesostructures. We report herein the successful preparation of unilamellar surfactant vesicles coated with a monolayer of ring-shaped {Mo-154} polyoxometalate (POM) nanoclusters, (NH4)(28)[Mo-154 (NO)(14)O(448)Hi(4)(H2O)(70)].approximate to 350H(2)O, by coulomb attractions using preformed didodecyldimethylammonium bromide (DDAB) surfactant vesicles as templates. The resultant vesicle-templated supramolecular assemblies are robust (they do not disintegrate upon dehydration) both at room-temperature ambient and vacuum conditions, as characterized by conventional transmission electron microscopy (TEM) and atomic force microscopy (AFM). The flexibility of the complex soft assemblies was also revealed by AFM measurements. The effect of POM-vesicle coulomb attractions on the dimensions of the templating vesicles was also investigated by using dynamic light scattering (DLS).Although origins of the structure stability of the as-prepared supramolecular assemblies are not clear yet, the nanometer scale cavities and the related properties of macroions of the POM clusters may play an important role in it.

固相反应法合成Pt/MoO_3及其电催化作用

采用固相合成的方法制得直接甲醇燃料电池催化甲醇氧化的Pt/MoO3.XRD分析、循环伏安测试表明,Pt/MoO3对甲醇的氧化具有较好的催化作用,氧化峰电位出现在0.63V(vs.SCE),峰电流密度可达78.1mA·cm-2.

Enriched accumulation and biotransformation of selenium in the edible seaweed Laminaria japonica

Accumulations of selenium in kelp Laminaria japonica cultured in seawater was achieved by adding selenite (Na2SeO3) with or without N-P (NaNO3 + NaH2PO4) nutrients at different concentrations. Biotransformation of selenium in the kelp was investigated through measuring the selenium of biological samples and different biochemical fractionations. The results showed that the optimal selenite-enrichment concentration is 200 mg L-1, which can allow the kelp to accumulate a total selenium content from 0.51 +/- 0.15 to 26.23 +/- 3.12 mug g(-1) of fresh weight (fw). Selenium composition analysis of kelp (control group) showed that selenium is present as organic selenium, which is up to 86.22% of the total selenium, whereas inorganic selenium is barely 4.85%. When L. japonica was exposed for 56 h in seawater containing 200 mg L-1 Na2SeO3, the organic selenium was 16.70 mug g(-1) of fw (68.23%) and inorganic selenium was 4.71 mug g(-1) of fw (19.26%). The capability of accumulation of selenium was further enhanced by adding N-P nutrients to the selenite-enriched medium. Total selenium is increased to be 33.65 mug g(-1) of fw at optimal concentration of N-P nutrient (150 mg L-1 NaNO3 and 25 mg L-1 NaH2PO4), whereas the inorganic selenium was not increased and remained at 4.597 mug g(-1) of fw (13.36%), and the increased part of selenium was organic selenium. This implied that kelp L. japonica could effectively transform inorganic selenium into organic selenium through metabolism.

Characterization of the main light-harvesting chlorophyll a/b-protein complex of green alga, Bryopsis corticulans

The main light-harvesting chlorophyll a/b -protein complex (LHC II) has been isolated directly from thylakoid membranes of shiphonous green alga, Bryopsis corticulans Setch. by using two consecutive runs of anion exchange and gel-filtration chromatography. Monomeric and trimeric subcomplexes of LHC 11 were obtained by using sucrose gradient ultracentrifugation. Pigment analysis by reversed-phase high performance liquid chromatography showed that chlorophyll a (Chl a), chlorophyll b (Chl b), neoxanthin, violaxanthin and siphonaxanthin were involved in LHC 11 from B. corticulans. The properties of electronic transition of monomeric LHC II showed similarities to those of trimeric LHC II. Circular dichroism spectroscopy showed that strong intramolecular interaction of excitonic dipoles between Chl a and between Chl b exist in one LHC II apoprotein, while the intermolecular interaction of these dipoles can be intensified in the trimeric structure. The monomer has high efficient energy transfer from Chl b and siphonaxanthin to Chl a similarly to that of the trimer. Our results suggest that in B. corticulans, LHC II monomer has high ordered pigment organization that play effective physiological function as the trimer, and thus it might be also a functional organization existing in thylakoid membrane of B. corticulans.

Product monitoring and quantitation of oligosaccharides composition in agar hydrolysates by precolumn labeling HPLC

Since the discovery of multiple bioactivities for agarobiose oligomers, a quantitative method has been in great need to monitor the agarobiose oligomers. This report demonstrates that agarobiose oligomers can be separated with high resolution in HPLC after introducing a-naphthylamine into compounds. Agarobiose oligomers ranged from biose to decaose were isolated by Sephadex column. HPLC analysis indicated that each oliomer could be quantified with good linearity and a low detection limit of 0.1-4 mug/ml. The chromatographic profiles of agaro-oligosaccharides with different hydrolysis modes (hydrochloride, citric acid, solid acid, and hydroxyl radical degradation) showed that agarobiose could be obtained more than 57.8% using solid acid mediated hydrolysis, while hydrochloride acid could degrade agar into a series of agaro-oligosaccharides from biose to decaose. The yield of oligosaccharides was low if hydrolyzed by citric acid. The Fenton degradation can increase the speed of hydrolysis, but the product was complex. (C) 2004 Elsevier B.V. All rights reserved.

Breaking seasonal limitation: year-round sporogenesis in the brown alga Laminaria saccharina by blocking the transport of putative sporulation inhibitors

Year-round induction of sporogenesis of Laminaria saccharina was performed by mechanically blocking the transport of the putative sporulation inhibitors produced by the blade meristem and culturing the plants in constant short days. Sporogenesis was successfully induced by removal of the blade meristem, either by cultivating distal blade fragments or by performing a transverse cut in the frond. The earliest sorus formation after artificial induction was 10 days. The age of the sporophytes used for induction was 6-11 months or 2 years in tank-grown or field-collected sporophytes, respectively. Zoospores were successfully released in all cases. Thus, by year-round artificial induction of sporogenesis, (1) sporeling production of L. saccharina and thereafter sporophyte cultivation could be achieved without seasonal limitation, and (2) the life cycle of L. saccharina (from spore to spore) could be completed within 8 months under controlled conditions. (C) 2004 Elsevier B.V. All rights reserved.

南黄海重金属的演变特征及控制因素

本文以南黄海1997～2006年10年表层海水和沉积物中重金属为主要研究对象，同时结合对生态环境信息的综合分析，系统探讨了海水和沉积物中重金属的生物地球化学特征、影响控制因素、演变趋势，并对海域生态风险进行了评估，获得了以下一系列新的结果和认识： 1．系统获得了南黄海海水和沉积物中重金属的地球化学分布模式，揭示了影响和控制其生物地球化学特征的因素 南黄海表层海水中重金属As、Cd、Cu、Hg、Pb、Zn的平均浓度分别为2.33、0.078、1.41、0.0036、0.37、6.21 μg/L，低于其它中国近海海水，而高于水交换较好的深海；表层海水重金属的分布模式（除Pb外）表现为在离岸较远的南黄海中部地区其含量较低，而近岸海区则普遍含量较高，区域分布呈现“高Cd-Cu-Hg-Zn区”，“高Pb-Cu-Zn区”以及“高Pb区”三个地球化学分区。 南黄海表层沉积物中重金属比邻近海域沉积物中的浓度低，南黄海重金属主要受沉积物粒度控制，即在细粒度高的南黄海中部区域重金属（除As外）的含量较高，粗粒度的近岸区则较低，区域分布呈现“高Cd-Cu-Pb-Zn区”，“高Hg低As-Cu-Zn区”以及“高As低Cd-Hg-Zn区”三个地球化学分区。 人类活动已经显著影响了南黄海海水中重金属的含量水平，重金属分布是径流、大气沉降、pH、盐度和重金属自身性质等各种影响因子耦合的结果。沉积物重金属的富集因子Pb>As>Hg>Cd>Zn>Cr>Cu，其中Pb和As主要来自人为污染排放，污染状况相对较重，Cr和Cu几乎没有受到人为污染的影响。沉积物的粒度是控制表层沉积物重金属分布的最主要因素，次要的因素包括沉积物有机质的含量、沉积速率以及重金属存在形态等。 2．首次获得了南黄海海水和沉积物中重金属的演变趋势 近10年来南黄海表层海水中，Zn呈上升趋势，As、Cd、Cu、Pb基本稳定变化不大，而Hg则呈略下降趋势。Zn的线性上升趋势明显，在近岸水域和中央水域中其浓度和公元年的统计关系分别为y=0.9524x+0.0034（R=0.97）和y=0.8622x+0.0299（R=0.95）（其中y为Zn的浓度，x为年度，取1997～2004）。近10年沉积物中重金属年际变化较小，浓度变化在多年均值的±（10%～30%）之间变动。As、Cd、Cu、Hg、Pb、Zn的均值变化范围分别为7.17±1.70、0.108±0.024、17.61±1.65、0.024±0.008、18.44±4.26、70.53±5.73 mg/kg，除了Hg随公元年呈较好的线性增加（y=0.0033x-6.50，R=0.75）外，其它重金属未显现出有明显的演变趋势。 近百年来，南黄海重金属的变化可分为3个阶段，20世纪60年代以前，20世纪60年代至90年代，及20世纪90年代至今。第一个阶段的60年可以看作是南黄海未明显受人类活动影响的一个时期，该段时期内明显的特征是重金属含量的变化受径流输入不均等多种因素影响，变化规律性不强；第二阶段是南黄海近岸工农业迅猛发展的阶段，由近岸传输到这一海域的重金属量增加，南黄海沉积物重金属浓度增加，沉积物质量有下降的趋势，这一阶段是人类活动影响南黄海最为明显的一个阶段；第三个阶段是20世纪90年代至今，南黄海沉积物重金属浓度呈降低趋势，与中韩两国减排及治污措施有关。近几年，南黄海沉积物的环境质量较20世纪末期有了较明显的改善。 3. 初步阐明了南黄海重金属的环境污染危害和潜在生态风险 采用潜在生态危害指数法和地积累指数等方法对南黄海沉积环境进行分析，结果表明，中等重金属污染程度海区占研究海区面积的38.7%，中等生态风险的区域则占了研究海区面积77.8%，但均未发现沉积物中的重金属与生物量的分布有明显的关系，总体表明，南黄海沉积物中的重金的污染状况及生态风险较低，南黄海沉积物质量良好。

南海上层海洋变异分析及海表温度统计学可预报性试验

气候变化和异常是当今地球科学研究的重大课题之一，与人类的生存、发展密切相关。南海作为我国最大的边缘海, 位于夏季风气流上游, 同时，作为热带太平洋的边缘海，具有显著的年际变异特征。近年来，随着卫星资料的积累和产品化使得我们有机会对南海的上层海洋要素进行全面的直接的观察，并进行南海气候异常变异及其可预报性的研究。 本文的研究内容就是利用近年来卫星资料产品，对南海主要海面要素，包括海面风场（SW）、表层温度场（SST）、海面高度场（SSH）的气候变化趋势以及南海表层温度变异的可预测性进行细致的探讨，并且利用较新的分析方法对南海上层海洋要素在近年来的非线性变异特点进行了分析。主要工作包括： 1. 采用南海卫星高度计及具有高精度模式输出结果通过联合经验正交函数分解（EOF）得到空间分辨率为1/3°×1/3°的南海绝对动力地形及地转流的季节变化（1－12个月）。从地转流场可以看到南海内部的表层流场主要有3种流系：西边界流、离岸流及南海多涡涡旋结构。 2. 通过南海海表大气和海洋要素（SW、风应力、SST、SSH）的气候变化趋势分析计算得到南海SST平均增暖0.5K/decade，海面高度升高6.7cm/decade，表层风场东分量和北分量的变化趋势分别为0.5m/s/decade、-0.04m/s/decade。其中南海SST增暖趋势和海面抬升速率远大于全球增暖和海面抬升速率。 3. 对南海SW、SSH和SST的异常场的EOF分析揭示南海SW、SSH及SST的年际尺度变化均表现出与ENSO变异现象一定的相关性：其中南海SW的第一模态特征表现为海盆尺度的反气旋，是西太平洋反气旋的最西南的一部分。对应的时间系数函数（TCF）滞后Nino3.4指数3个月，相关系数较高为0.90。南海SW的第二模态特征表现为均一化的西南风，TCF与印度洋偶极子（IOD）指数有一定相关性：TCF超前IOD指数4个月，相关系数达到0.58,表明南海SW第二模态似乎可以用来作印度洋偶极子现象的一个前兆。南海SSH的EOF第一模态特征为沿着南海东边界低水位，对应的TCF滞后Nino3.4指数2个月时间，二者相关系数为0.94；南海SST的EOF第一模态特征表现为整个海盆的增暖，对应的TCF与滞后Nino3.4指数8个月，相关系数等于0.62。 4. 基于典型相关分析（CCA），利用南海SSTA滞后热带太平洋Nino指数及印度洋IOD指数的关系建立南海SSTA的统计预报模式。通过对南海SSTA后报试验（1993/1994-2004年10月）与持续性预报值的预报效果进行比较分析，表明基于CCA统计方法对南海SSTA后期预报在预报时效超过3个月以上时具有更好的稳定性，提前1～12个月的后期预报水平平均值为0.60左右，误差均方根大约0.2个标准差。综合热带太平洋Nino指数为预报因子作南海SSTA统计预报的平均水平为0.55左右，亦具有较好的稳定性。 5. 基于前馈型神经网络，对南海近年的表层要素场（SW、SSH、SST）作非线性EOF分析。其中非线性EOF第一模态方差贡献与线性EOF相比均相应提高：海面风场、海面高度场的非线性作用较强，非线性EOF第一模态对变量场的方差贡献与线性EOF方法相比分别从54.75%提高到67.26%和50.43%提高至60.24%，非线性曲率强的空间范围占据绝大部分南海海域；相比较而言，南海SSTA场的非线性EOF第一模态的方差贡献提高不明显,非线性特征明显的区域仅在南海北部和南部靠近大陆的海区。对南海SSTA场1982-2003年时间长度的数据进行非线性与线性EOF分析比较，发现南海SSTA在近20年的非线性EOF分析中得到的非线性特征更不明显，表明与前10年相比，南海近10年的南海SSTA场的非线性成分有所增强。

Simple, mild and convenient synthesis of two novel N-dichloroacetyl oxazolidines and their biological activities

Two N-dichloroacetyl oxazolidines were synthesized with a simple, mild and convenient method. All the compounds were characterized by IR, (HNMR)-H-1 and elemental analysis. The preliminary biological test showed that the compounds protected maize against injury by some herbicides to some extent.

Sources and transport of dissolved and particulate organic carbon in the Mississippi River estuary and adjacent coastal waters of the northern Gulf of Mexico

Dissolved organic carbon (DOC), stable carbon isotopic (delta(13)C) compositions of DOC and particulate organic carbon (POC), and elemental C/N ratios of POC were measured for samples collected from the lower Mississippi and Atchafalaya rivers and adjacent coastal waters in the northern Gulf of Mexico during the low flow season in June 2000 and high flow season in April 2001. These isotopic and C/N results combined with DOC measurements were used to assess the sources and transport of terrestrial organic matter from the Mississippi and Atchafalaya rivers to the coastal region in the northern Gulf of Mexico. delta(13)C values of both POC (-23.8parts per thousand to -26.8parts per thousand) and DOC (-25.0parts per thousand to -29.0parts per thousand) carried by the two rivers were more depleted than the values measured for the samples collected in the offshore waters. Strong seasonal variations in delta(13)C distributions were observed for both POC and DOC in the surface waters of the region. Fresh water discharge and horizontal mixing played important roles in the distribution and transport of terrestrial POC and DOC offshore. Our results indicate that both POC and DOC exhibited non-conservative behavior during the mixing especially in the mid-salinity range. Based on a simple two end-member mixing model, the comparison of the measured DOC-delta(13)C with the calculated conservative isotopic mixing curve indicated that there was a significant in situ production of marine-derived DOC in the mid- to high-salinity waters consistent with our in situ chlorophyll-a measurements. Our DOC-delta(13)C data suggest that a removal of terrestrial DOC mainly occurred in the high-salinity (>25) waters during the mixing. Our study indicates that the mid- to high- (10-30) salinity range was the most dynamic zone for organic carbon transport and cycling in the Mississippi River estuary. Variability in isotopic and elemental compositions along with variability in DOC and POC concentrations suggest that autochthonous production, bacterial utilization, and photo-oxidation could all play important roles in regulating and removing terrestrial DOC in the northern Gulf of Mexico and further study of these individual processes is warranted. (C) 2004 Elsevier B.V. All rights reserved.

Potential P limitation leads to excess N in the pearl river estuarine coastal plume

There is excess nitrate (NO3) in the Pearl River coastal plume in the southern waters of Hong Kong in summer. We hypothesize that phosphorus (P) limitation controls the utilization of excess NO3 due to the high N:P ratio in the Pearl River. To test this hypothesis, we conducted two 1-day cruises on July 13 and 19, 2000 to examine the response of the phytoplankton to P additions with respect to changes in biomass, uptake of nutrients and nutrient uptake ratios using a batch incubation of natural water samples collected from the Pearl River estuary and adjacent coastal waters. At a station (E1, salinity =5) in the Pearl River estuary, the N/P ratio at the surface was 46:1, (64 muM DIN: 1.3 muM PO4) and decreased to 24:1 (12 muM DIN: 0.5 muM PO4) downstream at a station (Stn 26, salinity =26) in the coastal plume south of Hong Kong. Without a P addition, NO3 in the water samples collected at E1 could not be depleted during a 9 day incubation (similar to20 muM NO3 remaining). With a P addition, NO3 disappeared completely on day 6 with the depletion of the added PO4 (2-3 muM). This was also true for a station, E4 (salinity= 15) further downstream, but within the estuary. At Stn 26, in the coastal plume south of Hong Kong, NO3 (similar to11.5 muM) was eventually depleted without the addition of PO4, but it took 8 days instead of 5 days for Stn E4. The uptake ratio of dissolved inorganic nitrogen (DIN) to PO4, without a P addition was 51:1, 43:1 and 46:1 for Stns E1, E4 and 26, respectively. With a P addition, the DIN/PO4 uptake ratio decreased to 20:1, 14:1 and 12:1, respectively, for the 3 stations. These results clearly indicate potential P limitation to utilization of NO3 in the Pearl River estuary, resulting in excess NO3 in waters of the coastal plume downstream of the estuary, some of which would eventually be transported offshore. High uptake ratios of N:P without a P addition (43N:1P) suggest that phytoplankton have a nitrogen uptake capacity in excess of the Redfield ratio of 16N: 1P by 2.5-3 times. The value of 2.5-3 times was likely a maximum that should have contained a contribution of P released from desorption of P from sediments or from regeneration by zooplankton grazing and bacterial activity during the incubation of natural water samples. Without a P addition, however, phytoplankton biomass did not increase. This means that P turnover rates or regeneration may allow phytoplankton to take up additional N in excess of the Redfield ratio and store it, but without increasing the algal biomass. Therefore, high ambient N:P ratios in excess of the Redfield ratio do indicate potential P limitation to phytoplankton biomass in this estuarine coastal ecosystem. (C) 2004 Elsevier Ltd. All rights reserved.

Effects of diatoms on reproduction and growth of marine copepods

Two hot spots in marine ecology, deleterious effects of diatoms and feeding selectivity of copepods, as well as new progress on these two issues achieved in the recent ten years, are reviewed. These two issues are considered correlated closely. Diatoms and their metabolites can induce deleterious effects on growth, reproduction and development of copepods, including increase of mortality and decrease of egg production, hatching and growth rates. Such negative effects, resulting from either chemical toxin or nutritional deficiency, can be conquered in natural environments by diverse feeding. It is therefore concluded that deleterious effects of diatoms observed in laboratory or during blooming period are only a special case that accommodation of feeding strategy of copepods is disabled. To understand their feeding strategy in natural environments is a prerequisite to explaining the mechanisms of deleterious effects caused by diatoms, and makes it possible to re-evaluate the energy flow in marine ecosystems.

Dibenzyl bromophenols with diverse dimerization patterns from the brown alga Leathesia nana

Six novel dibenzyl bromophenols (1-6) with different dimerization patterns and two propyl bromophenol derivatives (7 and 8), together with 11 known bromophenol derivatives, were isolated from the ethanolic extract of the brown alga Leathesia nana. On the basis of spectroscopic methods the structures of the new compounds were determined as 5,6'-diethyloxymethyl-3,4,2'-tribromo-2,3',4'-trihydroxydiphenyl ether (1), 2-(2,3-dibromo-4,5-dihydroxybenzyl)-3,5-dihydroxy-4-methoxybenzyl alcohol (2), 6-(2,3-dibromo-4,5dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (3), 9,10-dihydro-9,10-dimethoxy-3,4,7,8-tetrabromo-1,2,5,6-tetrahydroxyanthracene (4), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (5), rel-(4aS*,10aR*)-(+/-)-6,7-dibromo-4a-hydroxy-3,8-dihydroxymethyl-10a-methoxy- 1,4,4a, 10a-tetrahydrodibenzo[b,e][1,4]dioxin-1-one (6), (E)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propenal (7), and 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)-1-propanol (8). Some compounds including 3 showed in vitro selective cytotoxicity against several human cancer cell lines. This is the first brown alga to be reported containing bromophenols.