A Hydrological Budget (2002–2008) for a Large Subtropical Wetland Ecosystem Indicates Marine Groundwater Discharge Accompanies Diminished Freshwater Flow

Water budget parameters are estimated for Shark River Slough (SRS), the main drainage within Everglades National Park (ENP) from 2002 to 2008. Inputs to the water budget include surface water inflows and precipitation while outputs consist of evapotranspiration, discharge to the Gulf of Mexico and seepage losses due to municipal wellfield extraction. The daily change in volume of SRS is equated to the difference between input and outputs yielding a residual term consisting of component errors and net groundwater exchange. Results predict significant net groundwater discharge to the SRS peaking in June and positively correlated with surface water salinity at the mangrove ecotone, lagging by 1 month. Precipitation, the largest input to the SRS, is offset by ET (the largest output); thereby highlighting the importance of increasing fresh water inflows into ENP for maintaining conditions in terrestrial, estuarine, and marine ecosystems of South Florida.     

Iron speciation in minerals and glasses probed by $$\hbox{M}_{2/3}$$-edge X-ray Raman scattering spectroscopy

We present a spectroscopic study of the iron \(\hbox{M}_{2/3}\)-edge for several minerals and compounds to reveal information about the oxidation state and the local coordination of iron. We describe a novel approach to probe the iron \(\hbox{M}_{2/3}\)-edge bulk sensitively using X-ray Raman scattering. Significant changes in the onset and shape of the Fe \(\hbox{M}_{2/3}\)-edge were observed on ferrous and ferric model compounds with Fe in octahedral and tetrahedral coordination. Simulation of the spectra is possible using an atomic multiplet code, which potentially allows determination of, e.g., crystal-field parameters in a quantitative manner. A protocol is discussed for determination of the Fe oxidation state in compounds by linear combination of spectra of ferric and ferrous end members. The presented results demonstrate the capabilities of Fe \(\hbox{M}_{2/3}\)-edge spectroscopy by X-ray Raman scattering to extract information on the ratio of trivalent to total iron \(\hbox{Fe}^{3+}/\sum \hbox{Fe}\) and local coordination. As X-ray Raman scattering is performed with hard X-rays, this approach is suitable for in situ experiments at high pressure and temperature. It thus may provide indispensable information on oxidation state, electronic structure and local structure of materials that are important for physical and chemical processes of the deep Earth.     

Oxygen fugacity control in piston-cylinder experiments: a re-evaluation

Jakobsson (Contrib Miner Petrol 164(3):397–407, 2012) investigated a double capsule assembly for use in piston-cylinder experiments that would allow hydrous, high-temperature, and high-pressure experiments to be conducted under controlled oxygen fugacity conditions. Using a platinum outer capsule containing a metal oxide oxygen buffer (Ni–NiO or Co–CoO) and H₂O, with an inner gold–palladium capsule containing hydrous melt, this study was able to compare the oxygen fugacity imposed by the outer capsule oxygen buffer with an oxygen fugacity estimated by the AuPdFe ternary system calibrated by Barr and Grove (Contrib Miner Petrol 160(5):631–643, 2010). H₂O loss or gain, as well as iron loss to the capsule walls and carbon contamination, is often observed in piston-cylinder experiments and often go unexplained. Only a few have attempted to actually quantify various aspects of these changes (Brooker et al. in Am Miner 83(9–10):985–994, 1998; Truckenbrodt and Johannes in Am Miner 84:1333–1335, 1999). It was one of the goals of Jakobsson (Contrib Miner Petrol 164(3):397–407, 2012) to address these issues by using and testing the AuPdFe solution model of Barr and Grove (Contrib Miner Petrol 160(5):631–643, 2010), as well as to constrain the oxygen fugacity of the inner capsule. The oxygen fugacities of the analyzed melts were assumed to be equal to those of the solid Ni–NiO and Co–CoO buffers, which is incorrect since the melts are all undersaturated in H₂O and the oxygen fugacities should therefore be lower than that of the buffer by 2 log $a_{{{\text{H}}_{ 2} {\text{O}}}}$ .     

Morphology and geology of the continental shelf and upper slope of southern Central Chile (33°S–43°S)

The continental shelf and slope of southern Central Chile have been subject to a number of international as well as Chilean research campaigns over the last 30 years. This work summarizes the geologic setting of the southern Central Chilean Continental shelf (33°S–43°S) using recently published geophysical, seismological, sedimentological and bio-geochemical data. Additionally, unpublished data such as reflection seismic profiles, swath bathymetry and observations on biota that allow further insights into the evolution of this continental platform are integrated. The outcome is an overview of the current knowledge about the geology of the southern Central Chilean shelf and upper slope. We observe both patches of reduced as well as high recent sedimentation on the shelf and upper slope, due to local redistribution of fluvial input, mainly governed by bottom currents and submarine canyons and highly productive upwelling zones. Shelf basins show highly variable thickness of Oligocene-Quaternary sedimentary units that are dissected by the marine continuations of upper plate faults known from land. Seismic velocity studies indicate that a paleo-accretionary complex that is sandwiched between the present, relatively small active accretionary prism and the continental crust forms the bulk of the continental margin of southern Central Chile.     

Adventive occurrence of the fouling serpulid Ficopomatus enigmaticus (Polychaeta) in New Zealand

The exotic marine‐fouling polychaete Ficopomatus enigmaticus (Fauvel) is recorded and described from New Zealand. Its sudden occurrence in New Zealand around 1967 was marked by its ecological prominence in estuaries of Whangarei and Auckland Harbours, as a nuisance species on submerged artificial structures including pleasure craft and power station intake pipes.     

Zooidal budding in the cheilostomatous bryozoan Fenestrulina malusii var. thyreophora

Zooidal budding in Fenestrulina malusii var. thyreophora is described and notes on the budding of Micropora mortenscni are included for comparison. In both, an autozooidal bud arises from a membranous window in the exterior wall of a dietella. Dietellae themselves arise by being delimited as dichotomies of the developing lateral walls of autozooids. Because of the structural discreteness of dietellae of Fenestrulina and Micropora, and Hastings’ (1963) observation that some dietellae of Microporella occur as avicularia, dietellae in the Microporellidae and Micropora are regarded as fully formed heterozooids and not merely as incipient zooid buds, as lateral septulae are. The formation of dietellae in Fenestrulina and Micropora is a continuous process, and comparable with the con‐strictive budding of distal autozooids of Membranipora and Metrarabdotos.     

Intra-crater glacial processes in central Utopia Planitia, Mars

We describe and interpret a series of previously unidentified glacial-like lobes (34-43°N; 107-125°E) that were discovered as part of a survey of large (D > 5 km) impact craters in Utopia Planitia, one of the great northern plains of Mars. The lobes have characteristics that are consistent with a glacial origin. Evidence includes curvilinearity of form, lineations and ridges, and surface textures that are thought to form by the sublimation of near-surface volatiles. The lobes display morphologies that range from wedge-shaped to near-circular to elongate. The flow directions are towards the northern walls in the case of craters with large single lobes, and in all directions in the case of the largest (D > 30 km) craters. Concentric crater fill is also interspersed within craters of our study region, with such craters having much higher filling rates than those with flow lobes. We suggest that the impact crater population in south-west Utopia Planitia demonstrates a spectrum of glacial modifications, from low levels of filling in the case of craters with elongate lobes at one extreme, to concentric crater fill in highly-filled craters at the other.     

铂族元素在地壳中的富集:以布什维尔德杂岩为例

地幔是地壳铂族元素富集的主要源库。铂族元素迁移主要有两个途径:(1)地幔部分熔融物质侵入地壳;(2)地幔板片就位于俯冲/碰撞带。前一途径比后一途径重要得多。地幔物质进入地壳造成铂族元素富集并成为可供开采的主矿产而非副产品,这一过程可包含许多成矿作用机制:(i)基性侵入体中Ni-Cu硫化物矿浆的发育,岩浆冷却与分离结晶作用导致富含Cu,Pt,Pd的硫化物矿浆的形成;(ii)层状侵入体一定层位形成高品位的铂族元素硫化物层,伴生或不伴生铬铁岩;(iii)富铂族元素及硫化物的岩浆沿着层状侵入体的边缘就位;(iv)直至层状侵入体结晶分异作用晚期的硫化物不混溶滞后分离;(v)不发育硫化物不混溶作用的铬铁矿结晶作用;(vi)低程度硫化物浸染带中的热液作用与铂族元素富集;(vii)乌拉尔-阿拉斯加型侵入体重结晶过程中的铂族元素与铬铁矿的次生富集作用,岩体在风化过程中形成砂矿床;(viii)黑色页岩形成过程中Pt的富集。南非布什维尔德火成杂岩蕴藏世界Pt资源的75%,Pd资源的54%,Rh资源的82%,并具有(ii)、(iii)、(iv)、(v)、(vi)成矿作用的实例。在这些作用中,作用(ii)形成的现有经济储量和资源量占90%,作用(iii)占9%。Merensky矿层(占总资源量30%)是一个铂族元素富集层位,它含1~3铬铁矿薄层,在可采宽度内硫化物平均含量为1%~3%(质量分数)。硫化物一般被认为是铂族元素的主要聚集体。该矿层由两个或两个以上含硫化物的基性热岩浆上升汇聚而成。这些岩浆的汇聚造成超镁铁质堆晶岩的厚度(主要是斜方辉石岩,某些地区包括橄榄岩)变化于50cm至数米之间。开采通常集中在厚度不到1m的地带。矿层的成因至今仍存在争议,一些观点认为铂族元素来自下部上升的热液流体,另一些观点认为铂族元素来自上部岩浆的硫化物沉降作用,并形成了Merensky辉石岩。已经知道矿层上覆的辉石岩、苏长岩和斜长岩中矿物来自两种岩浆类型:一种富含MgO(12%,质量分数)和Cr,而贫Al2O3(12%);另一种含典型的粒玄岩成分。UG-2铬铁岩含有全部经济资源量的58%,由一0.6~1m厚的铬铁岩层(有时见辉石岩夹层)和上覆的1~3层由铬铁矿所构成的薄层。虽然硫化物被认为至少是某些情况下对铂族元素的富集起作用,但UG-2的硫化物含量(0.5%~1.5%)显著低于Merensky矿层。UG-2层之下共有13个铬铁岩层位,所有的都含铂族元素,虽然铂族元素总含量和(Pt+Pd)/(Ru+Ir+Os)比值远低于UG-2。UG-2内所含的辉石岩"夹层"具高的87Sr/86Sr比值,说明与顶部熔融岩石的混合促进了铬铁岩和硫化物的形成。作用(iii)的主要实例是Platreef。目前它占总资源量的9%。不过,沿该带正积极开展找矿勘探工作,这一比例将来还会提高。这一矿层的厚度比Merensky和UG-2都要大,目前开采厚度达50多米。Platreef呈带状,上部为斜方辉石岩的堆晶岩;下部为辉石岩、长石辉石岩和苏长岩,它们与页岩、铁矿层和白云岩强烈相互作用,直接形成了底盘岩石。笔者认为Platreef是不同期次岩浆作用的结果,这些作用形成了不同的单元产物,包括布什维尔德主岩浆房的UG-2和Merensky矿层。新的岩浆进入主岩浆房会造成先存岩浆移位、岩浆错动并会冲破岩浆房的壁。圆筒状、带状岩管中的超镁铁岩含极高的Pt品位,在布什维尔德杂岩的下部切穿堆晶层,被认为是热液再活化的产物。它们现在未被开采,只是构成存封的铂族元素资源,对整个杂岩体资源没有重要的贡献。     

Reconstructed Northern Hemisphere annual temperature since 1671 based on high-latitude tree-ring data from North America

Annual Northern Hemisphere surface temperature departures for the past 300 yr were reconstructed using eleven tree-ring chronologies from high-latitude, boreal sites in Canada and Alaska, spanning over 90 degrees of longitude. This geographic coverage is believed to be adequate for a useful representation of hemispheric-scale temperature trends, as high northern latitudes are particularly sensitive to climatic change. We also present a reconstruction of Arctic annual temperatures. The reconstructions show a partial amelioration of the Little Ice Age after the early 1700's, an abrupt, severe renewal of cold in the early 1800's and a prolonged wanning since approximately 1840. These trends are supported by other proxy data. Similarities and differences between our Northern Hemisphere reconstruction and other large-scale proxy temperature records depend on such factors as the data sources, methods, and degree of spatial representation. Analyses of additional temperature records, as they become available, are needed to determine the degree to which each series represents fluctuations for the entire hemisphere. There appear to be relationships between trends observed in our Northern Hemisphere reconstruction and certain climatic forcing functions, including solar fluctuations, volcanic activity and atmospheric CO₂. In particular, our reconstruction supports the hypothesis that the global warming trend over the past century of increasing atmospheric CO₂ has exceeded the recent level of natural variability of the climate system.Of Columbia University Department of Geological Sciences.     

A comparison of a GCM response to historical anthropogenic land cover change and model sensitivity to uncertainty in present-day land cover representations

This study assesses the sensitivity of the fully coupled NCAR-DOE PCM to three different representations of present-day land cover, based on IPCC SRES land cover information. We conclude that there is significant model sensitivity to current land cover characterization, with an observed average global temperature range of 0.21 K between the simulations. Much larger contrasts (up to 5 K) are found on the regional scale; however, these changes are largely offsetting on the global scale. These results show that significant biases can be introduced when outside data sources are used to conduct anthropogenic land cover change experiments in GCMs that have been calibrated to their own representation of present-day land cover. We conclude that hybrid systems that combine the natural vegetation from the native GCM datasets combined with human land cover information from other sources are best for simulating such impacts. We also performed a prehuman simulation, which had a 0.39 K ~higher average global temperature and, perhaps of greater importance, temperature changes regionally of about 2 K. In this study, the larger regional changes coincide with large-scale agricultural areas. The initial cooling from energy balance changes appear to create feedbacks that intensify mid-latitude circulation features and weaken the summer monsoon circulation over Asia, leading to further cooling. From these results, we conclude that land cover change plays a significant role in anthropogenically forced climate change. Because these changes coincide with regions of the highest human population this climate impact could have a disproportionate impact on human systems. Therefore, it is important that land cover change be included in past and future climate change simulations.