The influence of long emersion on biota, ammonium fluxes and nitrification in intertidal sediments of Marennes-Oléron Bay, France

A comparative study between waterlogged and reflooded intertidal sediments was undertaken in March and June 1999 through statistical analysis of selected sediment parameters (biota, salinity, O2, Eh), pool sizes and benthic fluxes of nutrients (NH4+, NO2-, NO3-) and nitrification rates. In March samples, absence of polychaetes and oligochaetes from upper sediment horizons were due to erosional events sweeping away surface sediments. Presence of richer annelid assemblages in June samples indicated more stable hydrodynamic conditions that favoured the development of benthic microalgae biofilms. Dewatering of sediments during a 3-day emersion period promoted a salinity rise on top layers, migration of pore water ions towards the sediment surface, and created sediment fissures that accelerated water exchange on reflooding. Reflooded and waterlogged sediment systems were comparable with respect to the release of NH4+ to overlying water but were different with respect to nitrification rates. Sediment-water NH4+ fluxes were higher (P = 0.011) in March (3.3 mmol m(-2) day(-1) compared to June (1.4 mmol m(-2) day(-1) due to higher macrofauna biomasses and lower benthic microalgae concentrations in March samples. Potential nitrification rates (range from 19 to 60 mmol NO3- (-2) day(-1)) were not statistically different between March and June. A thinner oxic layer in reflooded compared with waterlogged systems reflects a decrease of O2 diffusion into sediment at high salinities which resulted in the fall of the actual nitrification rates (P < 0.05). Our data suggest that long term dessication of intertidal sediments may depress the nitrification process at the ecosystem level.     

南极西部埃尔斯沃思山脉罗斯造山运动的地层学证据：冈瓦纳古太平洋边缘的演化

南极西部埃尔斯沃思山脉罗斯造山运动的地层学证据：冈瓦纳古太平洋边缘的演化Ｐ．Ｍ．Ｇｏｌｄｓｔｒａｎｄ等冈瓦纳重建过程中存在着一个长期的疑问，即埃尔斯沃思山脉的古生代地层的明显整合与横贯南极山脉的大地构造史相矛盾，这两座山脉在中生代冈瓦纳分裂之前通常认...     

印度洋马约特（Mayotte）礁过去34ka以来的海平面变化和δ^18O记录

印度洋马约特（Ｍａｙｏｔｔｅ）礁过去３４ｋａ以来的海平面变化和δ￣（１８）Ｏ记录ＭｉｃｈｅｌＣｏｌｏｎｎａ等很少有资料证明以冰期后时期珊瑚礁为依据的海平面曲线，只有一条过去１７０００多年的参考曲线取自巴巴多斯近海处区域上受晚第四纪隆起影响的化石礁。考...     

Cell responses to xenobiotics: comparison of MCF7 multi-drug- and mussel blood cell multi-xenobiotic-defense mechanisms

Multi-drug resistance (MDR) in MCF7 breast cancer cells and multi-xenobiotic resistance (MXR) in mussel (Mytilus edulis) blood cells (MBC) are well known mechanisms that contribute to the decrease in intracellular concentrations of many unrelated but cytotoxic compounds. In the present work, we have carried out comparative investigations of the MDR/MXR protective mechanisms using a rapid colorimetric assay for cell viability and calcein accumulation for MDR/MXR activities. These studies were performed using cultured MCF7 and MBC before and after in vitro exposure to xenobiotics. Our results indicate that a 5-day exposure to doxorubicin or vincristine decreased calcein accumulation in MBC which is consistent with an induction of multi-xenobiotic resistance. The increase in calcein accumulation provoked by 1-h treatment with 50 microM verapamil was much lower in MBC when compared to the P-glycoprotein overexpressing MCF7 cell line. We conclude that such microplate assays could be used in primary cultures of MBC to estimate the effects of various chemicals on MXR activity.     

台湾暖流深层水变化特征的分析

潜居于闽、浙外海深、底层的台湾暖流深层水(又称东海上层水或东海次表层水),是东海陆架西部海域的主要水团之一。台湾暖流深层水的消长变化,对于东海陆架西部海域的水文状况,以及渔业生产的影响非常显著。关于台湾暖流深层水,国内、外海洋学者曾对其温、盐度特性和来源作过一些研究,但对其变化(季节变化和多年变化)特征研究尚少。探讨这一问题,将有助于进一步了解该水团的基本特征。     

晚弗拉斯期缺氧事件——弗拉斯-法门阶动物危机的原因？

弗拉斯-法门期(晚泥盆世)动物灭绝事件是显生宙五次主要生物事件中的一次，在此事件中，大约有21％的海洋生物科和50％的生物属消亡，低纬度热带生物礁生态系和浅水海洋动物所受影响最为严重，而高纬度生态系，深水生物和陆地动、植物群仅受到微弱影响，对于该事件的持续时期和最终原因存在广泛分岐。     

长江口可溶态210Pb的来源、分布和逗留时间

于１９８６年１月，采取大体积取样，Ｃｏ－ＡＰＤＣ螯合并沉淀富集分离，银片上自沉积和ａ－计算分析，研究长江口区可溶态２１０Ｐｂ的来源，分布和逗留时间。结果表明，全区平均放射性比度为７．５ｄｐｍ／ｍ＾３，从河向海纵向分布呈口内段和近外海两端高，而低谷出现在中间的口门外最大浊度及稀释带高生产力区。２１０Ｐｂ明显因悬浮颗粒物的吸附絮凝沉降和浮游生物的吸收利用被清除。经探析，该区２１０Ｐｂ主要来源是大气气溶     

台湾海峡中、北部海域夏季温、盐度的垂直分布类型和细结构

近年来,关于台湾海峡西部海域的水文状况,已有一些研究(肖晖等,1988；曾刚等，1988),但对海峡中部和东部海域的研究则较少,特别是对该海域海水温、盐度的垂直分布类型和细结构的调查研究至今尚未见报道。本文拟对台湾海峡中、北部海域夏季温、盐度的垂直分布类型和细结构进行分析研究。这将有助于进一步了解台湾海峡海域的水文状况、水团结构和海水的垂直混合过程及其机制,对该海域的资源(特别是渔业资源)开发也有现实意义。 本文所用资料是中国科学院海洋研究所和福建海洋研究所1987年7月11-20日和8月25-29日在台湾海峡中、北部海域进行的两次“上升流”专题调查中搜集的,调査站位如图1所示。这些资料包括南森站资料和CTD资料两类。前者系利用南森采水器和颤倒温度表获得,观测层次采用浅海标准层次(即0,5,10,15,20,25,30,50,75m,…底层)。后者系用美国 Interocean 公司513D型多要素探测仪(CTD)获取,为连续取样,该探测仪深度、温度和盐度的观测误差分别为±0.03m,±0.02℃和±0.05。 两次调查期间的天气状况基本相似。第一航次期间天气形势较稳定,多为晴和少云。第二航次期间天气形势基本与第一航次相似；但8月30日因受合风影响,天气状况趋于恶劣,F断面未能进行观测。在两次调査期间,台湾海峡中、北部海域的风向较稳定,多为南-西南风,仅个别测站出现东南风;风速変化也较小,一般都在2-5m/s之间,最大风速为9m/s。调査期间气温较高,大都在26.8-28.8℃间2最高为29.4℃。     

Bioaccumulation and depuration of Zn and Cd in mangrove oysters (Crassostrea rhizophorae, Guilding, 1828) transplanted to and from a contaminated tropical coastal lagoon

In order to study Zn and Cd accumulation and depuration, a set of oysters, Crassostrea rhizophorae, were transplanted to a metal contaminated coastal lagoon and another one was harvested there and transplanted to a non-polluted site. C. rhizophorae oysters and Perna perna mussels native from both sites were collected in order to monitor variability of metal concentration in resident populations. After three months exposure, oysters transplanted to the polluted site accumulated fourfold Zn (307-1319 microgg(-1)) without reaching the concentration level of resident oysters (9770 microgg(-1)). Cadmium concentrations had a slight but significant decrease during the same period (1.25-0.54 microgg(-1)). Oysters transplanted to the non-polluted site, showed threefold Zn depuration (6727-2404 microgg(-1)), while Cd had no significant variation (0.90-1.45 microgg(-1)). Results showed that transplanted oysters do not reach heavy metal concentrations in indigenous populations suggesting transplanted organisms would be better used to evaluate bioavailability instead of environmental concentrations.