Intercomparison of different methods for the determination of trace metals in seawater     

Lutz Brügmann  Lars-Gran Danielsson  Bertil Magnusson  Stig Westerlund 《Marine Chemistry》1983,13(4):327-339

During a cruise on the North Sea and the North East Atlantic, about 90 samples were obtained from various depths. Concentrations of cadmium, copper, lead, nickel and zinc were determined by atomic absorption spectroscopy after separation/concentration using two different extraction methods. One, using APDC and MIBK, was applied directly on board while the other, using a mixture of dithiocarbamates and freon, was applied after storage under acid conditions. About half of the samples were also analysed for cadmium, copper and lead using ASV. The results of these determinations are intercompared. Consistent results were obtained for cadmium with the two extraction methods and for lead with the freon extraction method and ASV. In the other cases discrepancies were found.  相似文献   

Regional distribution and temporal trends of some contaminants in the water of the Baltic Sea     

Lutz Brügmann  Horst Gaul  Karl-Heinz Rohde  Udo Ziebarth 《Ocean Dynamics》1991,44(4):161-184

During a cruise on board RV Gauss in May/June 1988, joint investigations into organochlorine compounds, dissolved trace metals, petroleum hydrocarbons and basic hydrography were carried out at representative stations of the Baltic Monitoring Programme (BMP). The aim of the cruise was to study distribution patterns and — using previous data — to establish temporal trends if at all discernible.Each group of contaminants investigated showed specific characteristics, with differences even between compounds within the same group. The differences are due to:

–	- the partition of contaminants between dissolved and adsorbed form;
–	- the response to redox conditions;
–	- the influence of microbial decay, organic production or changes in speciation.

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Multicriteria assessment of water dynamics reveals subcatchment variability in a seemingly homogeneous tropical cloud forest catchment          下载免费PDF全文

Edison Timbe  Jan Feyen  Luis Timbe  Patricio Crespo  Rolando Célleri  David Windhorst  Hans‐Georg Frede  Lutz Breuer 《水文研究》2017,31(7):1456-1468

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Continuous versus event‐based sampling: how many samples are required for deriving general hydrological understanding on Ecuador's páramo region?          下载免费PDF全文

Alicia Correa  David Windhorst  Patricio Crespo  Rolando Célleri  Jan Feyen  Lutz Breuer 《水文研究》2016,30(22):4059-4073

As a consequence of the remote location of the Andean páramo, knowledge on their hydrologic functioning is limited; notwithstanding, these alpine tundra ecosystems act as water towers for a large fraction of the society. Given the harsh environmental conditions in this region, year‐round monitoring is cumbersome, and it would be beneficial if the monitoring needed for the understanding of the rainfall–runoff response could be limited in time. To identify the hydrological response and the effect of temporal monitoring, a nested (n = 7) hydrological monitoring network was set up in the Zhurucay catchment (7.53 km²), south Ecuador. The research questions were as follows: (1) Can event sampling provide similar information in comparison with continuous monitoring, and (2) if so, how many events are needed to achieve a similar degree of information? A subset of 34 rainfall–runoff events was compared with monthly values derived from a continuous monitoring scheme from December 2010 to November 2013. Land cover and physiographic characteristics were correlated with 11 hydrological indices. Results show that despite some distinct differences between event and continuous sampling, both data sets reveal similar information; more in particular, the monitoring of a single event in the rainy season provides the same information as continuous monitoring, while during the dry season, ten events ought to be monitored. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Preliminary evaluation of the runoff processes in a remote montane cloud forest basin using Mixing Model Analysis and Mean Transit Time     

Patricio Crespo  Amelie Bücker  Jan Feyen  Kellie B. Vaché  Hans‐Georg Frede  Lutz Breuer 《水文研究》2012,26(25):3896-3910

In this study, the Mean Transit Time and Mixing Model Analysis methods are combined to unravel the runoff generation process of the San Francisco River basin (73.5 km²) situated on the Amazonian side of the Cordillera Real in the southernmost Andes of Ecuador. The montane basin is covered with cloud forest, sub‐páramo, pasture and ferns. Nested sampling was applied for the collection of streamwater samples and discharge measurements in the main tributaries and outlet of the basin, and for the collection of soil and rock water samples. Weekly to biweekly water grab samples were taken at all stations in the period April 2007–November 2008. Hydrometric data, Mean Transit Time and Mixing Model Analysis allowed preliminary evaluation of the processes controlling the runoff in the San Francisco River basin. Results suggest that flow during dry conditions mainly consists of lateral flow through the C‐horizon and cracks in the top weathered bedrock layer, and that all subcatchments have an important contribution of this deep water to runoff, no matter whether pristine or deforested. During normal to low precipitation intensities, when antecedent soil moisture conditions favour water infiltration, vertical flow paths to deeper soil horizons with subsequent lateral subsurface flow contribute most to streamflow. Under wet conditions in forested catchments, streamflow is controlled by near surface lateral flow through the organic horizon. Exceptionally, saturation excess overland flow occurs. By absence of the litter layer in pasture, streamflow under wet conditions originates from the A horizon, and overland flow. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

CODE’s new solar radiation pressure model for GNSS orbit determination   总被引：10，自引：8，他引：2  

D. Arnold  M. Meindl  G. Beutler  R. Dach  S. Schaer  S. Lutz  L. Prange  K. Sośnica  L. Mervart  A. Jäggi 《Journal of Geodesy》2015,89(8):775-791

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STAGES: the Space Telescope A901/2 Galaxy Evolution Survey     

Meghan E. Gray  Christian Wolf  Marco Barden  Chien Y. Peng  Boris Häußler  Eric F. Bell  Daniel H. McIntosh  Yicheng Guo  John A. R. Caldwell  David Bacon  Michael Balogh  Fabio D. Barazza  Asmus Böhm  Catherine Heymans  Knud Jahnke  Shardha Jogee  Eelco van Kampen  Kyle Lane  Klaus Meisenheimer  Sebastian F. Sánchez  y Taylor  Lutz Wisotzki  Xianzhong Zheng  David A. Green  R. J. Beswick  D. J. Saikia  Rachel Gilmour  Benjamin D. Johnson  Casey Papovich 《Monthly notices of the Royal Astronomical Society》2009,393(4):1275-1301

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at   z ∼ 0.165  has been the subject of an 80-orbit F606W Hubble Space Telescope (HST) /Advanced Camera for Surveys (ACS) mosaic covering the full     span of the supercluster. Extensive multiwavelength observations with XMM–Newton , GALEX, Spitzer , 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction and creation of a master catalogue. We perform the Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star formation rates for this field. We define galaxy and cluster sample selection criteria, which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues.  相似文献   

Energy Balance Closure Using Eddy Covariance Above Two Different Land Surfaces and Implications for CO<Subscript>2</Subscript> Flux Measurements     

Joe Kidston  Christian Brümmer  T. Andrew Black  Kai Morgenstern  Zoran Nesic  J. Harry McCaughey  Alan G. Barr 《Boundary-Layer Meteorology》2010,136(2):193-218

Components of the surface energy balance of a mature boreal jack pine forest and a jack pine clearcut were analysed to determine the causes of the imbalance that is commonly observed in micrometeorological measurements. At the clearcut site (HJP02), a significant portion of the imbalance was caused by: (i) the overestimation of net radiation (R _n ) due to the inclusion of the tower in the field of view of the downward facing radiometers, and (ii) the underestimation of the latent heat flux (λE) due to the damping of high frequency fluctuations in the water vapour mixing ratio by the sample tube of the closed-path infrared gas analyzer. Loss of low-frequency covariance induced by insufficient averaging time as well as systematic advection of fluxes away from the eddy-covariance (EC) tower were discounted as significant issues. Spatial and temporal distributions of the total surface-layer heat flux (T), i.e. the sum of sensible heat flux (H) and λE, were well behaved and differences between the relative magnitudes of the turbulent fluxes for several investigated energy balance closure (C) classes were observed. Therefore, it can be assumed that micrometeorological processes that affected all turbulent fluxes similarly did not cause the variation in C. Turbulent fluxes measured at the clearcut site should not be forced to close the energy balance. However, at the mature forest site (OJP), loss of low-frequency covariance contributed significantly to the systematic imbalance when a 30-min averaging time was used, but the application of averaging times that were long enough to capture all of the low-frequency covariance was inadequate to resolve all of the high-frequency covariance. Although we found qualitative similarity between T and the net ecosystem exchange (NEE) of carbon dioxide (CO₂), forcing T to closure while retaining the Bowen ratio and applying the same factor to CO₂ fluxes (F _C ) cannot be generally recommended since it remains uncertain to what extent long wavelength contributions affect the relationship between T, F _C and C.  相似文献   

Geochemistry and geochronology of HP mélanges from Tinos and Andros,cycladic blueschist belt,Greece     

Florian Bulle  Michael Bröcker  Claudia Gärtner  Alan Keasling 《Lithos》2010,117(1-4):61-81

U–Pb zircon geochronology, Sr–Nd isotope and bulk-rock geochemistry have been applied to meta-igneous and meta-sedimentary rocks from high-pressure metamorphic mélanges exposed on the Cycladic islands of Tinos, Syros and Andros. Ion microprobe (SHRIMP) U–Pb zircon dating of 7 samples representing meta-igneous blocks (Tinos), a blackwall zone (Tinos) and chlorite–talc schists from block-matrix contacts (Syros and Tinos) yielded Cretaceous ages of c. 80 Ma. Many of the criteria commonly used to distinguish between magmatic or metamorphic zircon genesis (internal structure, Th/U ratio, REE characteristics, Ti-in zircon thermometry, enclosed mineral phases) do not provide unambiguous constraints for the mode of formation. However, a magmatic origin for Cretaceous zircon of meta-gabbros and eclogites is considered likely. Supporting evidence for a previously suggested metamorphic origin for c. 80 Ma zircon in eclogite has not been found. Zircon of the same age occurring in chlorite–talc schists is presumably related to non-magmatic processes. Well-defined Cretaceous age groups clustering at c. 79 Ma also occur in the detrital zircon populations of 2 quartz mica schists representing the mélange matrix on Tinos, and suggest a much later time for sediment accumulation than previously assumed. The importance of c. 57 Ma zircon ages remains unclear, but may record either HP metamorphic processes or a post-57 Ma depositional age. The youngest age group in a third quartz mica schist from Tinos, collected outside the main mélange occurrences, clusters at c. 226–238 Ma. In all clastic metasediments from Tinos, most data points plot along the concordia between c. 300 and 900 Ma; single data points indicate concordant ages of c. 2.5 Ga, 2.3 Ga and 1 Ga, respectively. The youngest ²⁰⁶Pb/²³⁸U age group that has been recognized in a felsic paragneiss from Andros indicates an age of 163.1 ± 3.9 Ma, and mostly represents overgrowths around zircon with ages in the range from ～ 272 to ～ 289 Ma. Single data points of other inherited cores provided ²⁰⁶Pb/²³⁸U ages of c. 630 and c. 930 Ma. Meta-gabbros from Tinos show a large compositional variability and were found at 4 locations, each with distinct compositional characteristics, suggesting different crystallization histories, different sources and/or significant post-magmatic disturbance. The geochemistry of mélange blocks and the identical U–Pb zircon ages suggest that the block-matrix associations on Tinos and Syros can be grouped together. On a broader regional scale, there seem to be similarities between some meta-igneous rocks from Tinos and Evvia. Field relationships indicate that the mélanges occurring in southern Andros and northern Tinos can be correlated, but supporting geochemical and/or geochronological evidence for this interpretation could not be established. Previously published Jurassic ages for mafic and felsic mélange blocks from Andros suggest a genetic relationship to the ophiolite occurrences exposed in the larger Balkan region. A similar regional correlation is also considered likely for the Cretaceous meta-gabbros from Tinos and Syros, but cannot be documented with certainty.  相似文献   

Identifying Controls on Water Chemistry of Tropical Cloud Forest Catchments: Combining Descriptive Approaches and Multivariate Analysis     

Amelie Bücker  Patricio Crespo  Hans-Georg Frede  Kellie Vaché  Felipe Cisneros  Lutz Breuer 《Aquatic Geochemistry》2010,16(1):127-149

We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca²⁺, Ce, Gd, K⁺, Mg²⁺, Na⁺, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.  相似文献