Applicability and intercalibration of macrophyte quality indices to characterise the ecological status of Mediterranean transitional waters: the case of the Venice lagoon

In the framework of the WFD 2000/60/EC intercalibration process the updated versions of the EEI and R‐MaQI, proposed by Italy and Greece for the transitional waters, have been applied to the macrophytes of the Venice lagoon to test their comparability and relationships with the pressure gradients. Submerged macrophytes were collected during spring 2007 at 60 sites spread within the lagoon. At each site, five random samples were collected and the total coverage of benthic macrophytes in the field was estimated based on a number of tests of the bottom. To assess seagrass epiphytes, five shoots were collected for each replicate. Physico‐chemical data were collected in the water column at 14 sites selected to reflect the main hydro‐geomorphological and trophic gradients of the lagoon. The analyses performed indicated that the two metrics appeared to be weakly intercalibrated and only the 30% of the sampling sites displayed the same quality class. The main differences fell into the Moderate and Low classes and the two indices provided discordant results in the intermediate and confined areas of the lagoon. In contrast, the two indices showed good affinity in the marine areas of inlets, which are characterised by seagrass meadows and late‐successional macroalgae. Similar results were evidenced also in a redundancy analysis by the different relationships between quality classes and the physico‐chemical gradients. The main reason for this seems to be the heterogeneity of species–environment relationships inside the groups of species on which the indices are based. Critical aspects of methodological differences and applicability of the macrophyte indices proposed by Italy and Greece for the transitional waters of the Mediterranean eco‐region are discussed.     

南海西北部陆架区沿岸流和上升流对中华哲水蚤分布的影响

中华哲水蚤(Calanus sinicus)是广泛分布于西北太平洋大陆架水域的浮游桡足类,在海洋生态系统的物质循环和能量流动中具有重要作用。根据2006年7月至2007年10月4个季节使用网目孔径为0.505mm的浮游生物网采集的样品,分析了南海西北部陆架区中华哲水蚤的水平、季节和昼夜垂直分布以及与季风、海流和温度的关系。中华哲水蚤丰度季节变化显著,整个调查海域春季的平均达(22.30±77.78)个/m3,夏季的降低,平均为(13.74±45.10)个/m3,秋季消失,冬季调查期间仍未出现。中华哲水蚤的区域分布差异十分显著,将调查海域划分为粤西近海、琼东近海、粤西-琼东外海三个亚区,在粤西近海亚区春、夏季中华哲水蚤的平均丰度分别为(115.63±145.93),(68.12±84.00)个/m3,远高于另外两个亚区。夏季琼东沿岸上升流区的中华哲水蚤没有昼夜垂直移动行为,呈底层分布,以躲避表层高温的伤害。南海西北部陆架区是中华哲水蚤的季节分布区,冬春季东北季风期间由广东沿岸流从东海沿岸携带而来,出现的时间从北往南逐渐推迟;夏季西南季风期间雷州半岛东部近海的冷涡和琼东沿岸上升流区成为中华哲水蚤度夏的避难所;秋季季风转换时期上升流减弱或消失,中华哲水蚤因耐受不了高温(>27℃)死亡而消失。因此,中华哲水蚤对东北季风时期的沿岸流和西南季风时期的上升流均具有良好的指示作用。     

南海北部自由生活海洋线虫的群落结构和生物多样性

A quantitative study on the community structure and biodiversity of free-living marine nematodes and their relationship with environmental factors in the northern South China Sea were carried out based...     

2009年冬、夏季南海北部超微型浮游生物的分布特征及其环境相关分析

2009年2月(冬季)和8月(夏季)在南海北部海域(nSCS)采用流式细胞术对聚球藻、原绿球藻、超微型光合真核生物3类超微型光合浮游生物和异养浮游细菌的丰度和碳生物量的时空分布特征进行了研究,并分析了其与环境因子之间的关系。结果表明,夏季聚球藻和原绿球藻的平均丰度高于冬季,超微型光合真核生物和异养浮游细菌的丰度反之,为冬季高于夏季。聚球藻、超微型光合真核生物和异养浮游细菌在富营养的近岸陆架海域丰度较高,而原绿球藻高丰度则出现在陆坡开阔海域。在垂直分布上,聚球藻主要分布在跃层以上,跃层以下丰度迅速降低;原绿球藻高丰度主要出现在真光层底部;超微型光合真核生物在水层中的高值同样出现在真光层底部,且与Pico级份叶绿素a浓度分布一致;异养浮游细菌在水体中的分布与聚球藻类似。这些分布格局的差异,取决于环境条件的变化和4类超微型浮游生物生态生理适应性的差异。在超微型光合浮游生物群落中,各类群碳生物量的贡献因季节和海域类型的不同而发生变化:聚球藻在夏季近岸陆架区占超微型光合浮游生物总碳生物量的41%,原绿球藻在陆坡开阔海成为主要贡献者(50%),超微型光合真核生物碳生物量以冬季为高(在近岸陆架区占比68%)。冬、夏季异养浮游细菌碳生物量均高于超微型光合浮游生物碳生物量。     

Origin and anatomy of two different types of mass–transport complexes: A 3D seismic case study from the northern South China Sea margin

Integration of 2D and 3D seismic data from the Qiongdongnan Basin along the northwestern South China Sea margin has enabled the seismic stratigraphy, seismic geomorphology and emplacement mechanisms of eight separate, previously undocumented, mass–transport complexes (MTCs) to be characterized. These eight MTCs can be grouped into two types:(1) Localized detached MTCs, which are confined to submarine canyons and cover hundreds of km², consist of a few tens of km³ remobilized sediments and show long striations at their base. They resulted from small-scale mass-wasting processes induced by regional tectonic events and gravitational instabilities on canyon margins.(2) Regional attached MTCs, which occur within semi-confined or unconfined settings and are distributed roughly perpendicular to the strike of the regional slope. Attached MTCs occupy hundreds to thousands of km² and are composed of tens to hundreds of km³ of remobilized sediments. They contain headwall escarpments, translated blocks, remnant blocks, pressure ridges, and basal striations and cat-claw grooves. They were created by large-scale mass-wasting processes triggered by high sedimentation rates, slope oversteepening by shelf-edge deltas, and seismicity.Our results show that MTCs may act as both lateral and top seals for underlying hydrocarbon reservoirs and could create MTC-related stratigraphic traps that represent potential drilling targets on continental margins, helping to identify MTC-related hydrocarbon traps.     

红柳沟北镁铁-超镁铁质岩体矿物学特征及矿石成因分析

红柳沟北镁铁-超镁铁质岩体位于柴达木陆块北部的欧龙布鲁克微陆块东北缘,呈岩墙状,出露面积约0.1km~2,由方辉橄榄岩、橄榄二辉岩、含长单辉橄榄岩、橄榄辉长苏长岩、暗色橄榄辉长岩、苏长岩、辉长岩等组成,各岩相带在空间上呈渐变过渡关系。电子探针分析结果显示,岩体的主要造岩矿物为贵橄榄石、古铜辉石、普通辉石和斜长石,并且各矿物的结晶温度为1 307~1 122℃。岩体钛铁矿化明显,主要金属矿物为钛铁矿、钛磁铁矿和磁铁矿。利用橄榄石Fo最高值反演出原生岩浆MgO含量为8.49%,FeO含量为10.03%,TiO_2含量为1.63%,为普通玄武质岩浆。通过综合研究各矿物形成的温度和氧逸度条件,认为岩浆从橄榄石结晶到普通辉石结晶,其氧逸度是缓慢升高的,并且氧逸度是控制红柳沟北岩体Ti-Fe氧化物结晶的主要因素。     

南海北部深水区新生代岩浆岩分布规律及其与海底地质灾害的相关性

前人对南海北部新生代陆缘盆地结构、构造样式和期次等做了大量的研究工作,但对于具体体现内动力过程的岩浆活动关注较少,尤其是北部深水区的研究鲜有涉及。本文基于二维地震剖面的解译分析,将南海北部新生代岩浆岩划分为3个集中分布区:琼东南-西沙区、神狐区和东沙区。各区域岩浆岩的产出状态有所差异,其中琼东南-西沙区岩浆岩的平面展布规律性极强,主要受右行右阶的走滑断裂控制;神狐区岩浆岩位于NW向与NE向断裂的交汇处,侵位空间受先存断裂制约;东沙区岩浆岩的产生与东沙运动期间区域伸展过程有直接关系。作为内动力的表征,岩浆作用对于海底地形地貌具有重要的改造作用,与活动断裂、海底滑坡、浅层气等海底地质灾害也具有成因上的关联。     

Characteristics and implications of some Loch Lomond Stadial moraine ridges and later landforms,eastern Lake District,northern England

Moraine ridges and mounds of inferred Loch Lomond Stadial (LLS) age have been mapped at three sites (Fordingdale, Swindale and Wet Sleddale) in part of the eastern Lake District, northern England, and indicate glaciers were more widespread than envisaged by Sissons (1980, Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol. 71, pp. 13–27). The moraines delimit closely the downslope/downvalley limits of the former glaciers but there is no geomorphological evidence with which to define their upslope/upvalley margins. The former glaciers are considered to have been nourished within the confines of their individual valley, cirque and hillside embayment respectively, rather than being outlet glaciers of plateau icefields. Estimated equilibrium line altitudes (ELAs) are within the range of values determined previously for LLS glaciers in the Lake District and do not necessitate revision of established palaeoclimatic parameters. Individual ELAs were probably influenced by local factors; all three former glaciers had accumulation-area aspects between north and east, limiting the impact of direct solar radiation during the ablation season, and were adjacent to extensive areas of high ground to the west and/or south that would have facilitated transfer of snow to their surfaces by winds from those directions. In Fordingdale, three essentially contemporaneous depositional landforms occur upslope of the moraines and are considered to represent hillslope adjustments following wastage of glacier ice from the site. © 1998 John Wiley & Sons, Ltd.     

SEDIMENT BUDGETS AND RATES OF SEDIMENT TRANSFER ACROSS COLD ENVIRONMENTS IN EUROPE: A COMMENTARY

The sediment mass balance equation is the fundamental concept which underpins most sediment budget studies in cold climate environments. In these environments the interchange between water and ice plays a predominant geomorphological role. Such environments show a large variety of geomorphic processes which are conditioned by both contemporary environmental conditions but also the legacy of past events. In the northern Europe/Arctic fringe these cold regions are distributed in a fragmented fashion and are likely to be very sensitive to climate change scenarios. The significance of such changes for sediment transfer can only be established if we have good contemporary process understanding, the necessary tools to carefully monitor and model such changes, and can apply such methods at appropriate scales which integrate both sediment sources and sinks.     

西太平洋次表层海温异常与北赤道流异常海温西传

通过对热带太平洋上层XBT温度资料分析,探讨了对厄尔尼诺(El Nino)事件发生起重要作用的西太平洋暖池区次表层海温变暖异常的变化规律,揭示了影响西太平洋暖池区次表层海温变暖异常的形成机制.分析表明:西太平洋暖池区的次表层海温异常变暖与赤道太平洋的北赤道流(10°N)的海温异常存在密切关系.在El Nino事件发生的前期,位于赤道中东太平洋的异常暖水沿北赤道流温跃层潜沉向西太平洋暖池区输送,在西太平洋暖池堆积并向赤道西太平洋扩展,当异常暖水达到一定强度,并在大气的强迫下,异常暖水沿温跃层东传至赤道中东太平洋并上浮于海面,最终导致El Nino事件的爆发.北赤道流的异常海温西传是导致西太平洋暖池区次表层海温异常的重要机制,是导致El Nino事件发生的关键.