n-Alkane evidence for the onset of wetter conditions in the Sierra Nevada,California (USA) at the mid-late Holocene transition, ~ 3.0 ka

n-Alkane biomarker distributions in sediments from Swamp Lake (SL), in the central Sierra Nevada of California (USA), provide evidence for an increase in mean lake level ~ 3000 yr ago, in conjunction with widespread climatic change inferred from marine and continental records in the eastern North Pacific region. Length distributions of n-alkane chains in modern plants growing at SL were determined and compared to sedimentary distributions in a core spanning the last 13 ka. As a group, submerged and floating aquatic plants contained high proportions of short chain lengths (< nC₂₅) compared to emergent, riparian and upland terrestrial species, for which chain lengths > nC₂₇ were dominant. Changes in the sedimentary n-alkane distribution over time were driven by variable inputs from plant sources in response to changing lake level, sedimentation and plant community composition. A shift toward shorter chain lengths (nC_21, nC₂₃) occurred between 3.1 and 2.9 ka and is best explained by an increase in the abundance of aquatic plants and the availability of shallow-water habitat in response to rising lake level. The late Holocene expansion of SL following a dry mid-Holocene is consistent with previous evidence for increased effective moisture and the onset of wetter conditions in the Sierra Nevada between 4.0 and 3.0 ka.     

A survey for planetary transits in the field of NGC 7789

We present results from 30 nights of observations of the open cluster NGC 7789 with the Wide Field Camera on the Isaac Newton Telescope, La Palma. From ∼900 epochs, we obtained light curves and Sloan   r '− i '  colours for ∼33 000 stars, with ∼2400 stars having better than 1 per cent precision. We expected to detect ∼2 transiting hot Jupiter planets if 1 per cent of stars host such a companion and a typical hot Jupiter radius is  ∼1.2  R _J  . We find 24 transit candidates, 14 of which we can assign a period. We rule out the transiting planet model for 21 of these candidates using various robust arguments. For two candidates, we are unable to decide on their nature, although it seems most likely that they are eclipsing binaries as well. We have one candidate exhibiting a single eclipse, for which we derive a radius of  1.81^+0.09_−0.00  R _J  . Three candidates remain that require follow-up observations in order to determine their nature.     

The Late‐glacial reoccupation of the British Isles and the Creswellian

This paper presents a review of AMS radiocarbon dating evidence for human occupation of Britain during the Late‐glacial Interstadial. The dates are all on humanly modified materials, including artefacts, and on human bone. The CalPal program is used to test whether the earliest evidence of human presence shows any correlation with more widespread climatic events, and if the British chronology differs significantly from that of neighbouring regions of northwest Europe. In the second part of the paper a number of well‐dated sites with British Late Upper Palaeolithic ‘Creswellian’ technology are examined and compared with lithic assemblages from The Netherlands and Belgium. The main conclusions of this work are that expansion of human populations into the northern edge of the upland zone just before or at the beginning of GI‐1 was followed by repopulation of the British Isles possibly with very little time‐lag. The British Creswellian sites offer evidence of this earliest resettlement, which is mainly focused on the upland margins of western and central Britain. Copyright © 2003 John Wiley & Sons, Ltd.     

Impact of the Late Glacial Eruption of the Laacher See Volcano, Central Rhineland, Germany

Within a period of a few weeks toward the end of the Allerød Interstadial, the major Plinian eruption of the Laacher See volcano produced some 20 km³ of eruptiva, covering and preserving the late-glacial landscape in the German Central Rhineland over an area of more than 1000 km². Correlation of terrestrial archives with the Greenland ice-core records and improved calibration of the radiocarbon timescale permit a precise, accurate age determination of the Laacher See event some 200 yr before the onset of the Younger Dryas cold episode. Carbonized trees and botanical macrofossils preserved by Laacher See Tephra permit detailed regional paleoenvironmental reconstruction and show that open woodland were typical for the cool and humid hemiboreal climatic conditions during the late Allerød. This woodland provided the habitat for a large variety of animal species, documented at both paleontological and Final Paleolithic archeological sites preserved below Laacher See deposits. Of special interest are numerous animal tracks intercalated in Middle Laacher See deposits at the south of the Neuwied Basin. This knowledge may help to evaluate possible supraregional impacts of this volcanic event on northern hemispheric environment and climate during the late Allerød.     

An unstructured-grid, finite-volume, nonhydrostatic, parallel coastal ocean simulator

A finite-volume formulation is presented that solves the three-dimensional, nonhydrostatic Navier–Stokes equations with the Boussinesq approximation on an unstructured, staggered, z-level grid, with the goal of simulating nonhydrostatic processes in the coastal ocean with grid resolutions of tens of meters. In particular, the code has been developed to simulate the nonlinear, nonhydrostatic internal wave field in the littoral ocean. The method is based on the formulation developed by Casulli, in that the free-surface and vertical diffusion are semi-implicit, thereby removing stability limitations associated with the surface gravity wave and vertical diffusion terms. The remaining terms in the momentum equations are discretized explicitly with the second-order Adams–Bashforth method, while the pressure-correction method is employed for the nonhydrostatic pressure in order to achieve overall second-order temporal accuracy. Advection of momentum is accomplished with an Eulerian discretization which conserves momentum in cells that do not contain the free surface, and scalar advection is discretized in a way that ensures consistency with continuity, thereby ensuring local and global mass conservation using a velocity field that conserves volume on a local and global basis. The nonhydrostatic pressure field is solved efficiently using a block-Jacobi preconditioner, and while stability is limited by the internal gravity wave speed and vertical advection of momentum, applications requiring relatively small time steps due to accuracy or stability constraints are run efficiently on parallel computers, since the present formulation is written entirely with the message-passing interface (MPI). The ParMETIS libraries are employed in order to achieve a load-balanced parallel partitioning that minimizes interprocessor communication, and the grid is reordered to optimize per-processor performance by limiting cache misses while accessing arrays in memory. Test cases demonstrate the ability of the code to efficiently and accurately compute the nonhydrostatic lock exchange and internal waves in idealized as well as real domains, and we evaluate the parallel efficiency of the code using up to 32 processors.     

Evolution of the Mesozoic Granites in the Xiong'ershan-Waifangshan Region,Western Henan Province,China,and Its Tectonic Implications

Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong'ershan-Waifangshan region in western Henan Province: high-Ba-SrⅠ-type granite emplaced in the early stage (～160 Ma),Ⅰ-type granite in the middle stage (～130 Ma) and anorogenic A-type granite in the late stage (～115 Ma). Geochemical characteristics of the high-Ba-SrⅠ-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New 40Ar/39Ar plateau ages of the early-stage Wuzhangshan granite (156.0±1.1 Ma, amphibole) and middle-stage Heyu granite (131.8±0.7 Ma, biotite) are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A-type granite, Taishanmiao pluton, was emplaced at～115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between～160 Ma and～115 Ma. The genesis of the early- and middle-stageⅠ-type granites could be linked to delamination of subducted lithosphere of the Qiniing orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qiniing -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial 87Sr/86Sr ratios, which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratons.     

TEMPORAL AND SPATIAL DISTRIBUTIONS OF PAHS AND PCBS IN LAKE CALUMET AREA, CHICAGO

1 INTRODUCTION Lake Calumet is located 15 miles southeast of downtown Chicago. The geographical boundaries include 130th Street to the south, Stony Island Avenue to the east, an industrial area to the north, and interstate highway I-94 to the west. The major continuous water inflow to the lake is Pullman Creek, a drainage ditch, which carries the runoff from the nearby expressway, industries, and landfills into the lake at the northwest corner. The outlet of the Lake is the Calumet R…     

Experimental study of nonlinear wave—wave interaction and white-cap dissipation of wind-generated waves

An experimental scheme was designed to obtain laboratory-scale verification of Hasselmann's nonlinear wave—wave interaction and white-cap dissipation theories. Water wave height and fluctuating air pressure were measured simultaneously in a fixed reference frame as a function of fetch in the Stanford Wind, Water-Wave Research Facility under the conditions of a steady wind and a stationary wave spectrum. All the data were obtained 5 mm above the highest point of the wind waves for five stations (3 m apart on average) and at three wind speeds (7.1, 8.0 and 8.9 m/sec). The wave height and fluctuating pressure were measured by a capacitance wave-height gauge and a crystal pressure transducer, respectively.Based on the experimental results, Hasselmann's nonlinear wave—wave interaction theory appears to be valid. Barnett's approximate parametric equation for calculating the energy transfer of nonlinear wave—wave interaction and Hasselmann's white-capping dissipation model were also verified and appeared to be applicable in the relatively low and intermediate frequency region of a wave spectrum for a normalized fetch range of 100–500. Based on the results of an overall energy balance in a gravity wind-wave spectrum, the nonlinear wave—wave interaction mechanism is shown to play a dominant role in the energy transfer processes after the wave spectrum is generated.     

Sources of Nutrients and Fecal Indicator Bacteria to Nearshore Waters on the North Shore of Kaua`i (Hawai`i,USA)

Water quality monitoring in Hanalei Bay, Kaua`i (Hawai`i, USA) has documented intermittent high concentrations of nutrients (nitrate, phosphate, silica, and ammonium) and fecal indicator bacteria (FIB, i.e., enterococci and Escherichia coli) in nearshore waters and spurred concern that contaminated groundwater might be discharging into the bay. The present study sought to identify and track sources of nutrients and FIB to four beaches in Hanalei Bay and one beach outside the bay, together representing a wide range of land uses. ²²³Ra and ²²⁴Ra activity, salinity, nutrient and FIB concentrations were measured in samples from the coastal aquifer, the nearshore ocean, springs, the Hanalei River, and smaller streams. In addition, FIB concentrations in beach sands were measured at each site, and the enterococcal surface protein (esp) gene assay was used to investigate whether the observed FIB originated from a human source. Nutrient concentrations in groundwater were significantly higher than in nearshore water, inversely correlated to salinity, and highly site specific, indicating local controls on groundwater quality. Fluxes of groundwater into Hanalei Bay were calculated using a mass-balance approach and represented at least 2–10% of river discharges. However, submarine groundwater discharge (SGD) may provide 2.7 times as much nitrate + nitrite to Hanalei Bay as does the Hanalei River. It may also provide significant fluxes of phosphate and ammonium, comprising 15% and 20% of Hanalei River inputs, respectively. SGD-derived silica inputs to the bay comprised less than 3% of Hanalei River inputs. FIB concentrations in groundwater were typically lower than those in nearshore water, suggesting that significant FIB inputs from SGD are unlikely. Positive esp gene assays suggested that some enterococci in environmental samples were of human fecal origin. Identifying how nutrients and FIB enter nearshore waters will help environmental managers address pressing water quality issues, including exceedances of the state Enterococcus water quality standard and nutrient loading to coral reefs.     

The WASP project in the era of robotic telescope networks

We present the current status of the WASP project, a pair of wide angle photometric telescopes, individually called Super‐WASP. SuperWASP‐I is located in La Palma, and SuperWASP‐II at Sutherland in South Africa. SW‐I began operations in April 2004. SW‐II is expected to be operational in early 2006. Each SuperWASP instrument consists of up to 8 individual cameras using ultra‐wide field lenses backed by high‐quality passively cooled CCDs. Each camera covers 7.8 × 7.8 sq degrees of sky, for nearly 500 sq degrees of total sky coverage. One of the current aims of the WASP project is the search for extra‐solar planet transits with a focus on brighter stars in the magnitude range ∼8 to 13. Additionally, WASP will search for optical transients, track Near‐Earth Objects, and study many types of variable stars and extragalactic objects. The collaboration has developed a custom‐built reduction pipeline that achieves better than 1 percent photometric precision. We discuss future goals, which include: nightly on‐mountain reductions that could be used to automatically drive alerts via a small robotic telescope network, and possible roles of the WASP telescopes as providers in such a network. Additional technical details of the telescopes, data reduction, and consortium members and institutions can be found on the web site at: http://www.superwasp.org/. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)