Quantitative aspects of inorganic nutrient fluxes in the Gazi Bay (Kenya): implications for coastal ecosystems

Fluxes of dissolved inorganic nutrients: NH4+, NO2-, NO3-, PO4(3-) and Si(OH)4 from nearshore sediments of Gazi Bay were measured in situ within mangrove, seagrass and coral reef biotopes using benthic flux bell-jar chambers of cross-sectional area 0.066 m2 and volume 0.0132 m3. The objectives were: (1) to determine the influence of benthic fluxes, fluvial discharge and seasonal variations on the nutrient budget in the Bay waters; (2) to determine the effect of tidal and spatial variations on nutrient loads in the water column and (3) to establish the relative importance of the nutrient sources with regard to total community production of the Bay. The directly measured fluxes ranged from -270 to +148 micromol NH4+-N/m2/h; -60 to +63 micromol NO2(-)-N/m2/h; -79 to +41 micromol NO3(-)-N/m2/h; -79 to +75 micromol PO4(3-)-P/m2/h and +30 to +350 micromol Si(OH)4-Si/m2/h for and respectively. It was established that benthic fluxes are the major sources of dissolved inorganic NH4+, NO2- and Si(OH)4 while fluvial sources are important for NO3- and PO4(3-) into Gazi Bay waters. Seasonal variations had an appreciable effect on the PO4(3-) fluxes, N:Si ratio, river nutrient discharge, plankton productivity and important environmental factors such as salinity and temperature. Tidal and spatial variations had no significant effect on nutrient concentrations and net fluxes within the water column. The results imply that benthic fluxes are largely responsible for the nutrient dynamics of the nearshore coastal ecosystems especially where direct terrestrial inputs do not contribute significantly to the nutrient budget.     

Developing effective environmental indicators--does a new dog need old tricks?

Environmental indicators are being increasingly used to emphasise the relevance of monitoring. However, indicators must also be effective. In particular, they must be able to answer management questions, be accessible to the target audience and be sufficiently precise. Here, we use a time series of mercury levels in plaice from Liverpool Bay to illustrate how specific management questions can be formulated, answered, and the precision of these answers assessed. We also show how a programme design can incorporate a series of management questions that are likely to arise over time in response to observed changes in a time series.     

焦家构造带控矿作用探讨——以莱州新城金矿床为例

概略陈述了新城金矿床及焦家构造带的基本地质特征.对焦家构造带成矿前后的构造应力场、矿体侧伏规律、NWW向矿化带的形成及成矿时代等问题进行了探索性讨论.     

DETERMINATION OF SEDIMENTARY RATE IN ESTUARY AND COAST BY ~(228)Th TECHNIQUE

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＨｕａｎｇｈｅＲｉｖｅｒｗｅｌｌｋｎｏｗｎｗｏｒｌｄｗｉｄｅｆｏｒｉｔｓｈｉｇｈｓｅｄｉｍｅｎｔｄｉｓｃｈａｒｇｅｉｓＣｈｉｎａ’ｓｓｅｃｏｎｄｌａｒｇｅｓｔｒｉｖｅｒ,ｗｈｏｓｅｒｕｎｏｆｆｉｓｍａｉｎｌｙｓｕｐｐｌｉｅｄｂｙｐｒｅｃｉｐｉｔａｔｉｏｎｏｖｅｒｔｈｅｕｐｐｅｒｒｅａｃｈｅｓ.Ｈｏｗｅｖｅｒ,ｔｈｅｍａｔｅｒｉａｌｆｒｏｍｓｏｉｌｅｒｏｓｉｏｎｉｎｔｈｅＬｏｅｓｓＰｌａｔｅａｕｉｎｔｈｅｍｉｄｄｌｅｒｅａｃｈｅｓｉｓａｍａｊｏｒｃｏｎｔｒｉｂｕｔｏｒｔ…     

重力勘探新技术在寻找古潜山中的应用

以渤海湾盆地某凹陷为例,介绍下延一定深度的垂直二次导数、三维视密度反演、在LCT平台上的重、磁、地震正反演等新技术在寻找一些小规模、低幅度、大埋深的古潜山构造的应用效果。下延一定深度的垂直二次导数异常比常规的重力处理技术,即常规的垂直二次导数异常,从平面上能更好、更直观地反映小规模、低幅度、大埋深的古潜山构造;三维视密度反演技术反映地质体的横向密度变化情况,从纵向上为潜山研究提供证据;利用LCT平台上的重、磁、地震联合正反演技术可以定量地确定潜山埋深、幅度等。     

金融联系视角下沿海发达地区城镇网络空间结构研究

基于世界城市网络研究路径和沿海湾区经济发展背景,以浙江省县市（区）级行政单位为研究对象,将19家国内银行在各行政单元的数量和级别分布作为基础数据,使用链锁模型、社会网络分析等研究方法,对浙江省城镇网络空间的结构特征进行分析。研究表明：一是浙江省金融机构分布层级明显,与城市行政等级及经济地位密切相关;二是除杭州金融中心作用凸显之外,宁波、台州和温州等沿海城市也成为金融机构网络中的重要空间节点;三是研究区域内的政府干预、金融需求、经济协作关系以及文化差异对金融联系下的城市网络的扩张有显著的影响,金融业比重、人均GDP和行政边界则并无显著作用。     

几种保存方法对中华哲水蚤和强壮箭虫体型的影响

选取5%的甲醛,–20℃冰冻和液氮为保存方法,以中国近海的2种优势浮游动物中华哲水蚤(Calanus sinicus)和强壮箭虫(Sagitta crassa)为研究对象,以体长、体宽和面积为体型参数,研究了上述几种保存方法在2个月的时间内对浮游动物体型的影响。研究结果显示,对于中华哲水蚤,甲醛保存2个月后,体长下降为原始体长的99.4%,体宽和面积都增加为107%;冰冻和液氮保存2个月后,体长分别增加为原始体长的101%和106.8%,体宽下降为90%和81.6%,面积下降为92.2%和88.8%。对于强壮箭虫,在甲醛、冰冻和液氮3种保存条件下,保存2个月后体长有所下降,分别为原始体长的92.8%,50.7%和48.4%。体宽和面积有所增加,体宽分别变为原始体宽的139.9%,159.4%和263.8%,面积分别变为原始面积的119%,97.8%和107%。综合分析发现,胶质类浮游动物在冰冻和液氮保存条件下,身体变形严重,因此用ZooScan测得的结果误差较大,相较而言,甲醛对胶质类浮游动物体型的影响较小;中华哲水蚤比强壮箭虫在各种保存条件下体型的变化要小;保存初期,浮游动物体型的变化幅度较大,后期趋于稳定;在3种保存条件下,中华哲水蚤和强壮箭虫体长的变化最稳定,其次是面积。对浮游动物的体型进行研究时,推荐使用甲醛保存条件下的体长或面积。     

菜州浅滩地貌特征及演化

莱州浅滩是山东半岛北部著名的海岸地貌,位于刁龙嘴外,呈Nw—SE向延伸,浅滩众多,水道纵横,地貌状况复杂。目前对菜州浅滩的形成过程、沉积特征少有研究,或只针对某一方面有所论述。通过实地调查,并对资料进行分析,研究了莱州浅滩的沉积物分布特征、矿物组成、地貌特征、储砂量和演化过程,认为波浪作用是莱州浅滩形成的主要动力,控制着研究区地貌形态分布和莱州浅滩演化趋势。通过以上研究,结合莱州浅滩现状,指出了其目前在开发与保护中存在的问题,并提出了合理开发利用的建议。     

莱州湾西北与山东半岛北部强海效应降雪个例分析

利用常规资料、NCEP再分析资料和加密自动站资料对2011年12月8日莱州湾西岸一次强海效应降雪过程进行了诊断分析。结果表明:此地的海效应降雪与山东半岛北部的海效应降雪都是在适宜的背景场、有利的海气温差及较强的低空冷平流等基本条件下发生的。但是具体到风场配置、海气温差强度、水汽分布及动力、热力条件等方面存在着差异。在这次过程中,900 hPa以上为西北风,以下维持持续的东北风,是造成此次强海效应降雪的主要原因。这种风场结构与半岛北部的高、低空均要求西北风不同。结合物理量场的诊断分析认为,莱州湾西岸的海效应降雪与山东半岛北部的同属于浅对流降雪。本次过程中900 hPa以下存在上升运动、水汽辐合中心、不稳定层结和大的海气温差,近地层的切变线触发了不稳定能量的释放。强降雪区出现在1000 hPa相当位温暖舌的区域,暖舌的位置与山东半岛北部发生强海效应降雪时的不同,前者在莱州湾,后者在半岛北部沿海。从云图上看,冷流低云在海面上表现为一条条顺气流方向的云线,云的个体呈细胞状,接近陆地时,由于海陆下垫面的差异使得云层加厚,云的走向发生偏转,降雪加大。     

A model study on dynamical processes of phytoplankton in Laizhou Bay

A three-dimensional ecosystem model, using a PIC (Particle-In-Cell) method, is developed to reproduce the annual cycle and seasonal variation of nutrients and phytoplankton biomass in Laizhou Bay. Eight state variables, i.e., DIN (dissolved inorganic nitrogen), phosphate, DON (dissolved organic nitrogen), DOP (dissolved organic phosphorus), COD (chemical oxygen demand), chlorophyll-a (Chl-a), detritus and the zooplankton biomass, are included in the model. The model successfully reproduces the observed temporal and spatial variations of nutrients and Chl-a biomass distributions in the bay. The nutrient concentrations are at high level in winter and at low level in summer. Double-peak structure of the phytoplankton (PPT) biomass exists in Laizhou Bay, corresponding to a spring and an autumn bloom respectively. Several numerical experiments are carried out to examine the nutrient limitation, and the importance of the discharges of the Yellow River and Xiaoqinghe River. Both DIN limitation and phosphate limitation exist in some areas of the bay, with the former being more significant than the latter. The Yellow River and Xiaoqinghe River are the main pollution sources of nutrients in Laizhou Bay. During the flood season, the algal growth is inhibited in the bay with the Yellow River discharges being excluded in the experiment, while in spring, the algal growth is enhanced with the Xiaoqinghe River excluded.