A methodology for defining homogeneous water bodies in estuaries – Application to the transitional systems of the EU Water Framework Directive

A methodology is developed and tested for division of estuarine and coastal systems into water bodies for monitoring and management purposes. This division is often implicit in the choice of sampling stations and in pollution abatement measures applied to different locations – it is now an explicit requirement of European Union Directive 2000/60/EC (Water Framework Directive) and recommended by United States Agencies such as EPA and NOAA. The approach considers both natural characteristics and the human dimension, by means of a stepwise methodology, which considers, on the one hand, morphology and salinity distribution, and, on the other, appropriate indicators of pressure and state. In the present application, nitrogen and phosphorus loading was used as the pressure component and chlorophyll a and dissolved oxygen as indicators of state. The criteria for system division were defined based on (1) an adimensional shape factor and salinity classes for the natural component; and (2) a normalised pressure index and (ASSETS) eutrophication symptom classes for the human dimension. Water quality databases and GIS were used to develop spatial distributions for the various components, and the results were aggregated into a final water body division, using tidal excursion as a “common sense” test. The methodology was applied to three well-studied systems in Portugal, a tubular estuary (Mondego), a wide lagunal estuary (Sado) and a coastal barrier island system (Ria Formosa). Although a final definition of water bodies will usually be a policy decision, this type of approach for the division of coastal systems into management units scientifically informs the decision-making process.     

淤泥质海岸形态的演变及形成机制

在淤长型和侵蚀型岸段之间,存在着一种由淤积到侵蚀的过渡型岸段。通过剖面测量、粒度分析和地质调查,认为过渡型岸段具有上部淤积下部冲刷、冲刷逐渐向上部扩展、潮滩表层沉积物不断租化、淤积带逐渐变窄最后过渡到全剖面侵蚀的基本特征和发展趋势。     

Principal Modes and Related Frequencies of Sea Surface Temperature Variability in the Pacific Coast of North America

We examined monthly time-series (1950 to 1999) of sea surface temperature (SST) anomalies in 47 quadrants (2° × 2°) along the Pacific coast of North America. Correlation, clustering and principal components analyses were applied to identify the spatial structure in coastal SST. The resulting modes and the individual series were investigated using spectral analysis to identify the most significant time-scales of variability, and the propagation of the main signals was explored by computing the wavenumber-frequency spectrum of each spatial mode. Results showed that coastal SST variability in the northeast Pacific conformed to three main geographical modes. A tropical mode extends from the equator to about the entrance to the Gulf of California. This mode appears related to two low frequency components of the El Niño-Southern Oscillation of about 3 and 5 years. The SST anomaly related to these signals propagates poleward, seemingly at low speeds (≈0.08 m s^?1). A temperate (or transitional) mode, which includes the coastal areas along the California Current System, also shows the 5-year signal plus a decadal-scale component (periods between 10–17 years). Finally, a subarctic mode includes the coastal areas along the Gulf of Alaska and is dominated by the interdecadal variability that is characterized by the Pacific Decadal Oscillation.     

A preliminary note on the dispersal of the Cambrian Burgess Shale-type faunas

The common or similar elements of faunas shared by the Early Cambrian Chengjiang fauna and the Middle Cambrian Burgess Shale fauna are listed in a generic level so as to have a better understanding of the palaeogeographic relationship between the South China Block and Laurentia. The Burgess Shale-type faunas probably had a worldwide distribution during the interval ranging from the Late Tommotian to Atdabanian. The geographic and biological contributions to the cosmopolitan geographic distribution of the Burgess Shale-type faunas are discussed. However, newly developed pelagic larvae in many phyla, which probably acquired their first bloom in the Cambrian, might have promoted the dispersal.     

1970-2015年秦岭南北气温时空变化及其气候分界意义

基于秦岭南北70个气象站点观测资料,辅以极点对称模态分解方法（ESMD）,对秦岭南北近期气温时空变化特征进行分析,进而以日平均温≥ 10 ℃积温天数为主要指标,以1月0 ℃等温线变化为辅助指标,探讨秦岭山脉的气候分界意义。结果表明：① 1970-2015年秦岭南北气温变化具有同步性,呈现出“非平稳、非线性、阶梯状”的增暖过程,变化阶段可分为：1970-1993年为低位波动期、1994-2002年为快速上升期、2003-2015年为增温停滞期;② ESMD信息分解结果表明,秦岭南北气温变化以年际波动为主导,并未呈现出明显的线性增暖趋势;③ 在空间上,秦岭南北气温趋势呈现“同步增温,南北分异”的响应特征,即秦岭以北地区空间增温具有一致性,秦岭以南地区则呈现“西乡—安康盆地交界”、“商丹盆地”两个低值中心;④ 在气候变暖背景下,秦岭作为气候分界线的作用依然明显,但是南北响应方式存在差异。其中,秦岭以南,北亚热带北界沿山地“垂直上升”,汉江谷地热量资源逐年增加;秦岭以北,尽管以城市带为中心的增温区不断延展,但是冷月气温偏低的格局并未改变。     

Heterozoan carbonates from the equatorial rocky reefs of the Galápagos Archipelago

Strongly influenced by seasonal and interannual (i.e. El Niño‐Southern Oscillation) upwelling, the equatorial setting of the Galápagos Archipelago is divided into well‐defined temperature, nutrient and calcium carbonate saturation (Ω_aragonite) regions. To understand the relationship between oceanographic properties and sediment grain associations, grain size, carbonate content and components from sea floor surface samples were analysed, representing the main geographical regions of the Galápagos Archipelago. The shallow‐water rocky reefs of the Galápagos Archipelago are characterized by mixed carbonate–siliciclastic slightly gravelly sands. Despite minor differences in carbonate content, major differences exist in the distribution and composition of key carbonate producing biota. Halimeda is absent and benthic foraminifera occur in extremely low abundance. The western side of the Galápagos Archipelago is strongly influenced by nutrient‐rich, low‐Ω_aragonite, subtropical water, which generates a heterozoan carbonate biofacies in a tropical realm resembling cold‐water counterparts (i.e. serpulid, echinoderm, gastropod, barnacle and bryozoan‐rich facies). The Central East region is composed of a transitional‐heterozoan biofacies. Biofacies observed in the northern region have an increased occurrence of tropical corals, albeit with a minor overall contribution to the carbonate components. Although the temperature gradient would allow for a broader distribution of photozoan biofacies, the increased nutrient concentration and related reduced light penetration from the upwelled waters favour heterozoan carbonate factories, mimicking cool‐water, deeper or higher latitude environments. The recent sedimentary record of the Galápagos Archipelago presents a range of tropical heterozoan carbonate communities, responding to more than simply latitude or temperature but a much more complex mixture of physical, evolutionary and geological processes.     

秦岭-黄淮平原交界带自然地理若干特征分析

文章探讨了秦岭-黄淮平原交界带划分的依据和方法,然后就其自然地理过渡性、暴雨频繁发生和坡地暖带及其自然地理效应进行讨论。研究表明:交界带自然地理要素不仅具有西部山地和东部平原之间的过渡性,而且北亚热带和暖温带地理成分在这里彼此交汇。交界带暴雨频繁,且以大暴雨为主,集中分布在海拔100~200 m之间。交界带冬季气温高于平原0.5~0.8℃,1月最高气温出现在海拔350~400 m之间,形成特有的坡地暖带,暖带厚度100~250 m。交界带暴雨频繁和暖坡效应是大气环流和交界带地貌格局共同作用的结果,且对本区土壤发育和植物分布等具有重大影响。     

Effect and Prospect of Basic Geological Survey Based on Airborne Gravimetry in China

The airborne gravimetry was an important leap and innovation in the world’s history of geophysical exploration. China's first test of the airborne gravity geological survey in the onshore-offshore transitional area of the western and southern part of the Bohai Sea was successful and effective in geology. Based on the airborne gravity data, and combining previous ground gravity, seismic and drilling data etc., we carried out the geological interpretation by forward and inverse methods. The result shows that the airborne Bouguer gravity anomaly was clear, the fracture interpretation was reliable, and the inversion depth of the main geological interfaces was relatively accurate. This airborne gravity geological survey not only filled the exploring gaps in the onshore-offshore transitional area, and realized the geological and tectonic junction between the sea and the land, but also discovered four local gravity anomalies, 11 fractures and three sags or subsags, and so on. The good geological effect of airborne gravimetry not restricted by terrain condition shows that it can be served as a new geophysical method in the exploration of complex terrain physiognomy area such as mountain, jungle, desert, marsh, onshore-offshore transitional area and so on, and has an extensive application prospect in China in the future.     

山区过渡性地理空间人文自然交互性识别与分异解析

山区因其人文自然交互过程具有显著的地域性、时空分异性与不确定性,成为典型的过渡性地理空间,其类型量化识别与分异特征的解析可为山区乡村振兴背景下国土空间高质量发展提供决策依据。本文基于地理不确定性的概念构建时空变率指数,识别出中国山区过渡性地理空间分布与分区,并运用地理探测器解析其地理时空变率的驱动力谱。结果发现：中国山区过渡性地理空间总面积为238.32×10⁴ km²（约占中国陆表面积的1/4）,其地理时空变率从第一阶梯到第三阶梯呈递减趋势;全国山区过渡性地理空间可分为12个分区,其中昆仑—祁连山分区面积最大;人文驱动因子对人口与土地利用的时空变率解析力最强,基础地形因子对植被覆盖时空变率与地理时空变率指数的解析力最为显著,各因子中海拔与夜间灯光的解析驱动力最强。整体而言,人文要素的时空动态均对东南山区过渡性地理空间具有显著的塑造性,而西北山区过渡性地理空间主要受到自然要素的时间变化和人文要素的空间变化所驱动。本文为山区过渡性地理空间的不确定性、多样性与人地关系地域性的定量研究提供了新的见解与启示。     

单体“海大1号”长牡蛎苗种室内人工培育模式的优化

为提高单体“海大1号”长牡蛎(Crassostrea gigas)的培育效率,本研究以3种培育模式(下降流、上升流和静水)、6个水流量梯度(20、35、50、65、80和95 mL/s)和6个培育密度梯度(2.5、5、7.5、10、12.5和15个/mL)对单体“海大1号”长牡蛎苗种中间培育生长情况进行了研究。研究表明,单体“海大1号”长牡蛎苗种中间培育时,上升流和下降流均比静水培育效果好,培育前5天采用下降流、第6~29天采用上升流时,稚贝生长快、死亡率低;水流量小于65 mL/s时,随水流量的增加,稚贝生长加快,死亡率降低,水流量在65~80 mL/s时,单体牡蛎稚贝生长存活最优,第29天时最大壳高达(1534.81±65.23)μm。单体“海大1号”长牡蛎稚贝苗种中间培育时,随着培育密度的增大,挤迫效应逐渐显现,密度为7.5个/mL时,死亡率相对较低,且稚贝生长速度快,在第29天时稚贝壳高最大可达(1520.63±51.72)μm。基于以上研究结果,建议在规模化单体“海大1号”长牡蛎稚贝中间培育时,采用上升流和下降流相结合的流水培育方式,适当增加水流量,及时疏散密度。本研究优化了单体“海大1号”长牡蛎室内培育模式,为单体牡蛎规模化培育提供了参考方法和理论依据。