赤道暖池区漂流浮标运动轨迹分析

TOGA—COARE强化观测期间,对赤道暖池区海流作了多种方法、多层次的观测;根据美国释放的漂流浮标不同时刻位置的资料,分别对赤道及其南、北海域的表层漂流状况作了计算分析,指出:从1°N向北存在单一的北向流;从1°N～1°S这个近赤道区域内为东向流;1°N～2°S区域为过渡区,以东向流为主,个别浮标出现涡旋状运动。2°S以南为一反时针运动的大涡旋。     

底部浮泥表层推移速度分布的ADCP—GPS估测方法

ADCP对底跟踪走航观测的流速数据中包含水体底部浮泥、底沙运动信息,对比GPS定位方法算出的水体流速数据可以分离出浮泥相对于GPS定位的运动信号,从而达到对底质推移观测的目的。     

Microphytobenthos vertical migratory photoresponse as characterised by light-response curves of surface biomass

The migratory response of intertidal microphytobenthos to changes in irradiance was studied on undisturbed estuarine sediments. Two non-destructive optical techniques were used to trace variations in vivo of surface biomass: PAM fluorometry, for measuring the minimum fluorescence level (F_o); and spectral reflectance analysis, for quantifying the normalized difference vegetation index (NDVI). Following the formation of a dense biofilm at the surface, replicated sediment samples were simultaneously exposed to six different irradiance levels, ranging from 50 to 1500 μmol m⁻² s⁻¹, during a period of 120 min. The migratory photoresponse of the biofilms was characterised by constructing biomass vs. light curves (BLC), relating the accumulation of microalgal biomass after that period (estimated by F_o or NDVI) to the irradiance level incident on the surface. BLCs allow characterising the main features of the migratory photoresponse of intact biofilms. Typical BLC showed a clear biphasic pattern, with an increase in microalgal accumulation under irradiances below 100 μmol m⁻² s⁻¹, maximum values under 100–250 μmol m⁻² s⁻¹, and a gradual decrease of surface biomass under higher irradiances, indicating a strong photophobic downward migratory response. Similar BLC patterns were obtained when measuring F_o or NDVI. The construction of BLCs for biofilms from intertidal sites with distinctive sediment characteristics and diatom taxonomic composition allowed to detected significant differences in the migratory photoresponse. Biofilms from a muddy sediment exhibited considerably larger amplitude in the migratory photoresponse than the biofilms from a sandy mud site, especially under high irradiances. The photophobic migratory response to high light was found to vary among diatom species, particularly in the case of the biofilms from the muddy sediments.     

珠江口河流输沙、河口沉积与粒度信息之间的联系

河口三角洲地区泥沙供应充分，是现代沉积速率较高的区域。快速沉积的泥沙包含高分辨率的环境信息。采用放射性同位素测年方法研究了珠江口伶仃洋大铲湾海域6个柱样的现代沉积速率，以2mm的间隔分析了其中2个柱样上部的粒度，并对其平均粒径和珠江流域的年输沙量进行了快速傅里叶变换，以期获取河流泥沙供应、河口沉积速率和沉积物垂向粒度变化的对应关系。结果表明，大铲湾海域的沉积速率为1～3cm／a，受动力条件和泥沙供应条件的影响显著。2个柱样的平均粒径的最显著重现周期与珠江年输沙量的周期性有较好的对应关系，并可能反映了季节的、年的和多年的沉积速率信息。对于每年沉积厚度在厘米级的环境，以毫米级的高分辨率进行粒度分析，有可能揭示出沉积物供应的季节变化和年际变化。本研究亦可为其他河口的相关工作提供借鉴。     

Vertical distribution of the macrobenthic community and its relationships to trace metals and natural sediment characteristics in the lower Douro estuary, Portugal

Vertical distribution (0–15 cm) of the macrobenthic community and its relationships to natural sediment characteristics and trace metal contents and bioavailability were studied at five locations in the lower Douro estuary, Portugal. An analysis of vertical metal distribution, for the interpretation of anthropogenic impact on the estuarine sediments, was also investigated. Sediment characterisation included organic matter, grain size, metals (Al, Fe, Cu, Pb, Cr, Ni, Cd, Zn and Mn), acid volatile sulphide (AVS) and simultaneously extracted metals (SEM). The macrobenthic community had low diversity (14 species), was dominated by small size opportunists and seemed to be controlled mainly by natural factors such as grain size distribution, Al and Fe contents and sediment depth. The vertically heterogeneous distribution of macrobenthic community appears to affect redox status of the sediments and consequently metal bioavailability. Despite anthropogenic contamination in terms of Zn, Cu, Pb, Cr and Ni having already been detected in the north bank, the analysis of vertical distribution was essential for the identification of current anthropogenic contamination in terms of Zn, Pb and Cd in the south bank.     

Biocorrosion by Bivalves

Abstract. A survey of the historical background of chemically boring bivalves and the proposed methods of boring, indications for biocorrosion, observations, and experimental results are provided. The regional impact to the ecosystem is discussed with examples from the N. Adriatic, Caribbean, and E. Pacific. The fossil record of the geologically oldest biocorroders extends back into the Mesozoic, i.e ., U. Triassic for Lithophaga and Jurassic for gastrochaenids.     

9012号热带气旋维持的卫星云图和垂直结构特征分析

本文根据卫星云图的演变和常规天气分析相结合，对9012号热带气旋登陆后维持水消的成因进行了分析。指出该热带气旋经久不消的重要原因为其西南侧对流云团和东北侧高空槽前对流云带与热带气旋云系相衔接在中低层东北气流引导下卷入，热带气旋内部的两条云带的维持，以及利有的环流条件。     

一维扩散方程整体观测资料下的初值变分同化反演

本文考虑一维扩散方程的反问题,利用变分同化方法通过观测资料来确定方程中的未知初值,通过分析观测误差对于初值误差的影响,证明变分同化初值收敛于原问题的真实参数,并得到了参数的收敛精度。同时将得到的初值代入预报模式中,得到预报解,并分析了预报解的收敛性和预报误差。