Cadmium and phosphorus cycling in the water column of the South China Sea: The roles of biotic and abiotic particles

The concentrations of cadmium, phosphorus, and aluminum in size-fractionated phytoplankton, zooplankton, and sinking particles are determined using ICPMS to evaluate the roles of biotic and abiotic particles on the cycling and ratios of Cd and P in the water column. Plankton were collected with a filtration apparatus equipped with 10-, 60-, and 150-μm aperture plankton nets on two occasions (2002 and 2006), and sinking particles were sampled by moored sediment traps deployed at depths of 120, 600, and 3500 m from 2004 to 2005. In contrast to what our previous study revealed, i.e., that most of the other bioactive trace metals in plankton were strongly correlated with abiotic Al and adsorbed on phytoplankton [Ho, T.Y., Wen, L.S., You, C.F., Lee, D.C., 2007. The trace metal composition of size-fractionated plankton in the South China Sea: biotic versus abiotic sources. Limnol Oceanogr 52, 1776–88.], Cd/P ratios, ranging from 0.12 to 0.34 mmol/mol P, did not vary with Al and exhibited fairly consistent values among different sizes of plankton, showing that Cd was mostly incorporated on an intracellular basis. In terms of the sinking particles, fluxes in Cd and P as well as in Cd/P ratios were strongly influenced by both biotic and abiotic particles. Overall, the Cd/P ratios in the sinking particles ranged from 0.03 to 1.2 mmol/mol, with the highest value observed in traps at 120 m during the productive season. The lowest value was observed in deep water during high flux periods for lithogenic particles. At surface depth, flux and Cd/P ratios were elevated during the most productive season in the region. The elevated ratios in the traps at 120 m were most likely related to preferential uptake of Cd for the dominant species (coccolithophores) during the productive period. Relatively, Cd/P ratios sharply decreased with increasing Al flux in deep water and ratios were much lower than the expected Cd/P ratios obtained from the relative portion of lithogenic and biogenic particles, indicating that the adsorption of soluble P into lithogenic particles was significant in the deep water during high lithogenic particle flux periods. Using averaged annual fluxes and standing stock in the water column, the residence time of biogenic Cd and P are 0.10 and 0.20, 250 and 100, and 9100 and 5000 years respectively in the top 120 m, 600 m, and water column as a whole, also showing preferential removal for Cd in the euphotic zone but relatively higher removal rates for P in the deep water. Our study suggests that the shift in microalgal community structure along with input of lithogenic minerals are both potentially important factors in influencing Cd/P ratios in oceanic water on a geological time scale.     

Inversion of two-dimensional tidal open boundary conditions of M<Subscript>2</Subscript> constituent in the Bohai and Yellow Seas

Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE) after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.     

杭州湾及邻近水域营养盐的时空分布与富营养化特征

利用2006年7月-2007年11月杭州湾及邻近水域春、夏、秋、冬四个季节的调查资料,对其营养盐的分布变化及富营养化特征进行了分析.结果表明:杭州湾及邻近水域营养盐的分布变化和富营养化不仅与湾内河流高DIN、磷、硅的输入直接有关,同时受长江冲淡水的影响十分显著.湾内营养盐的分布变化主要受物理混合作用所控制,浮游生物活动...     

A crustal seismic velocity model for the UK, Ireland and surrounding seas

A regional model of the 3-D variation in seismic P -wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity–depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 × 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data.     

Azimuthal variation of the P phase in Icelandic receiver functions

A curious observation has been made on radial receiver functions calculated from teleseisms recorded by 29 broad-band seismometers distributed over Iceland. The arrival time of the direct P phase of the radial receiver functions depends critically upon the azimuth of the teleseismic source. For a seismic station in West Iceland, the direct P  phase of the radial receiver function arrives consistently later for easterly source azimuths than for westerly source azimuths. The reverse applies for stations in East Iceland. In the original seismograms, the delayed P phase of the receiver function appears up to 450 ms later on the radial than on the vertical component. The seismometer locations in East and West Iceland are separated by the Neovolcanic Zone, a constructive plate boundary. The delayed P phases occur for seismic rays travelling across this zone. However, it is not obvious how wave propagation across the plate boundary zone could cause the observed delays. The tentative explanation proposed here involves the regional dip of the Icelandic lava sequences towards the Neovolcanic Zone. A dipping interface at shallow depth results in a P–S converted phase arriving shortly after the P phase. These phases cannot be separated in the radial receiver functions, given the bandwidth of the observed signals. However, a calculation of receiver functions from estimates of the P , SV and SH wavefields clearly reveals a P–S converted phase at about 500 ms for easterly source azimuths in West Iceland and for westerly source azimuths in East Iceland. The amplitudes of the direct P phase and the P–S phase converted at a dipping interface would be expected to vary strongly with azimuth in accordance with the observed behaviour.     

Heavy Metal Load of Sediments of the River Gurk (Carinthia/Austria) — Merits and Limitations of Sequential Leaching Schwermetallbelastung des Sediments der Gurk in Kärnten — Vorzüge und Einschränkungen sequentieller Löseverfahren

By means of the analysis of sediments cored in the small river Gurk (Carinthia/Austria), the input of Ag, Cd, Ce, Cr, Hg, La, Mo, Ni, V, and W from a chemical industrial plant could be detected. To estimate the actual load, and to obtain data for comparison with other sites, both unsieved fine sediments and sediments sieved to 20 μm were investigated from the same cores. Environmental mobilities of toxic heavy metals (Co, Cr, Cu, Ni, Zn) have been shown by sequential leaching following Tessier/Förstner. In the last step, HNO₃ leaches a purely geogenic fraction, which is fairly constant along the investigated river. Whereas the additional Cr from the input of the chemical plant is mainly found in the oxalate-leachable fraction, short-time-load to unpolluted sediments in the laboratory is found mainly in hydroxylamine/acetic acid. Both is due to the high affinity of Cr to Fe- and Mn-oxides. Adsorption/desorption experiments reveal that the low carbonate content of the Gurk sediments increases the importance of Fe/Mn-oxides for the sorption of Cr compared to other samples containing carbonate. The Ni-load was primarily found in weak-acid-leachable and oxalate-leachable fractions. Similarly, the oxalate-leachable fraction is dominant for adsorption of other metals and phosphorus. Other interelement relationships among the amounts leached, which are attributable partly to carbonate-, silicate-, organic or coating phases, have been found by means of factor analyses together with marker fractions for each type.     

中国南阳伏牛山世界地质公园地质灾害评价

中国南阳伏牛山世界地质公园位于豫西南山区。地貌类型以中、低山为主,地表多出露变质岩及侵入岩,岩体风化强烈,多赋存基岩裂隙水,地质构造发育,人类工程活动强烈,园区地质环境条件复杂。通过野外调查及评价,园区处于地质灾害高易发区,主要地质灾害有崩塌、滑坡和泥石流。针对地质公园这一特色旅游,提出地质灾害防治对策,保障当地旅游经济可持续发展。     

李四光和卡尔宾斯基金质奖章

中国地质学家李四光与当时苏联地学界来往交流紧密,他对地质学的贡献得到了苏联地质学家的高度评价。1958年,苏联科学院全体大会选举李四光为苏联科学院院士,并授予卡尔宾斯基金质奖章;该奖章是1947年由当时的苏联科学院和俄罗斯科学院共同发起的、对地质科学有突出贡献的科学家最高单人奖励,李四光是第六位获奖人,也是至2017年止唯一获此殊荣的外籍地质学家,他的获奖理由是:在地质、古生物、地层和矿产研究工作的综合贡献。李四光有两部著作在苏联被译成俄文出版,分别是1952年的《中国地质学》和1958年的《中国西北部的旋卷构造》,这两部译作对当时的苏联地质界产生了很大影响,极大地推动了李四光学术思想的广泛认知;"地质无国界",中国地调百年的发展历程也有着俄罗斯地学理论、规范、方法实践的烙印,在新的"一带一路"合作倡议和李四光学术精神传承下,中俄、中国与中亚在地学领域的交流合作将不断深化,硕果累累。