Eine Methode zur Reinigung und Reinheitskontrolle optischer Glasoberflächen in Seewasser und Anwendung des Verfahrens zum Bau eines auslegbaren Trübungsmessers     

Dr. Hans Gienapp  Uwe Carstens  Karl Schomaker 《Ocean Dynamics》1981,34(6):295-301

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Land use/cover change in central Tibet, c. 1830–1990: devising a GIS methodology to study a historical Tibetan land decree     

Karl Ryavec 《The Geographical journal》2001,167(4):342-357

In this study, historical Tibetan tax-related data pertaining to cultivated land in central Tibet are studied by means of GIS and compared with contemporary patterns. A Tibetan land decree from 1830 contains aggregated data on the amount of land-based tax units for estates in 57 districts of central Tibet. The purpose of this study is to devise a GIS methodology to study the potential utility of these data for historical geographical research, and to determine the approximate changes in cultivated land areas between 1830 and 1990. Traditional Tibetan tax data are significant for current efforts to construct historical land cover databases of the Tibetan Plateau region for the study of the human dimensions of global change.  相似文献   

Investigation of groundwater contamination using electric and electromagnetic methods at an open waste-disposal site: a case study from Isparta, Turkey   总被引：4，自引：0，他引：4  

Gülçin Karlık  M. Ali Kaya 《Environmental Geology》2001,40(6):725-731

 Geophysical methods, when integrated with soil chemical and hydrogeological methods, can be used to investigate groundwater contamination. Direct current (DC) resistivity geo-electrical sounding and very-low-frequency electromagnetic (VLF-EM) data were collected at an open waste site used by the municipality of the city of Isparta, Turkey. The groundwater at shallow depths in alluvium, which is composed of gravel, sand and clay, were expected to be hazardously contaminated under and around the open waste-disposal site, in which both household and industrial wastes are known to be disposed of improperly. In this study, we mapped the spread of groundwater contamination using a VLF-EM method, which allows fast and inexpensive data collection. The method complements the results of geo-electrical sounding. There is a good correlation between the results of the VLF-EM and the DC-resistivity methods employed for the investigation of subsurface structure of the site, where soil chemical and previous hydrogeological surveys have indicated high levels of chemical concentrations. Received: 17 January 2000 · Accepted: 12 August 2000  相似文献   

Dysaerobic conditions during Heinrich events 4 and 5: Evidence from phosphorus distribution in a North Atlantic deep-sea core     

Federica Tamburini  Sylvain HuonPhilipp Steinmann  Francis E GroussetThierry Adatte  Karl B Fllmi 《Geochimica et cosmochimica acta》2002,66(23):4069-4083

Reactive phosphorus undergoes diagenetic transformation once transferred into marine sediments. The degree of regeneration and redistribution of phosphorus depends on early diagenetic and environmental conditions, which may be linked to larger scale phenomena, such as bottom water circulation, water column ventilation, and organic carbon flux. Phosphorus phases of the <50-μm-sized fraction of deep-sea sediments from core SU 90-09 (North Atlantic, 43°31′N, 30°24′W, 3375 m below sea level) have been analyzed using a sequential extraction technique (SEDEX method) to reconstruct phosphorus geochemistry during Heinrich events 4 and 5. Comparison with Holocene samples from the same site indicates that postdeposition diagenetic transformation has not affected phosphorus distribution in the deep part of the sediments. Total and reactive phosphorus average 0.40 ± 0.04 mg/g and 0.30 ± 0.05 mg/g, respectively, and are comparable to values found in analog deep-sea environments in the North Atlantic. Detrital phosphorus, the phase linked to igneous- and metamorphic-derived material, sharply increases during Heinrich events and covaries with the ice-rafted debris record, whereas authigenic and Fe-bound phosphorus phases, both influenced by redox conditions, decrease or even disappear. These findings suggest that during the deposition of Heinrich layers (HLs), environmental parameters hampered the precipitation of these phases. Large freshwater discharges in relation to iceberg surges may have provoked a temporary stratification of the water column. Accordingly, dysaerobic conditions in the sediments may have fostered the loss of dissolved phosphorus from the sediments to the water column, in a direct and rapid response to the changed conditions. Decreasing trends in organic matter elemental ratios (total organic carbon/organic phosphorus) and Rock-Eval oxygen index values, along with the presence of partly authigenic dolomite and ankerite within HLs, also support this assumption.  相似文献   

Projective ordination by SIMCA: A dynamic strategy for cost-efficient environmental monitoring around offshore installations     

Bernard G. J. Massart  Olav M. Kvalheim  Fred Olav Libnau  Karl I. Ugland  Kjell Tjessem  Karl Bryne 《Aquatic Sciences - Research Across Boundaries》1996,58(2):120-138

A method for environmental monitoring using benthic species profiles as input is developed in this work. The method, referred to as projective ordination, utilises local principal component modelling (SIMCA) to obtain a cross-validated model which spans the natural variation in a region around offshore oil-producing installations. The borderline between regions with disturbed and non-disturbed species communities is subsequently decided from the residual distribution. This distribution is used to design an approximate F-test for assessing whether a community at a particular sampling location is disturbed or not. If so, the nature of the disturbance is determined by projecting the data on the PC model.Projective ordination utilises information from previous surveys to define the permissible variation in species communities, i.e. the limit of the natural variation. In addition, the method is dynamic, in a sense that the sampling locations may vary from survey to survey.Furthermore, our analysis shows that the customary number of replicate samples per station can be reduced. Modelling with only four randomly chosen replicates out of the complete set of five for each sampling location, does not affect the model significantly. On the other hand, taking only 3 replicates into account leads to significant divergences.A model based on the 1990 and 1993 surveys at the Statfjord field is presented as an example of the technique.  相似文献   

Synthetic seismograms ofP-waves propagating in solid wedges with free boundaries     

Karl Fuchs 《Studia Geophysica et Geodaetica》1966,10(3):272-273

A numerical method for the synthesis of seismograms for body wave propagation in solid wedges is presented. The method is based on the superposition of multiple reflections arising from the entrance of a plane primary wave. Therefore the method is restricted to those domains in time-space where no diffracted waves from the wedge axis occur. In spite of this restriction, the dispersion of body waves in wedges can well be studied by this method. Seismograms have been synthesized which show the dispersion of a primary,p-signal propagating in a solid 10°- and a 5°-wedge with free boundaries. For wedge anlges less than 10° the signal from (as distinguished from the wave front) suddently decreases its velocity from that in the infinite medium to about that of the plate wave as the signal approaches the wedge axis. A decrease of the dominant period of the interference signal occurs simultaneously in this transition zone. These observations are concordant with previous seismic model studies [1]. Particle motion diagrams disclose elliptical polarization of the interference signal in the neighboorhood of the wedge axis which changes its sense from prograde to retrograde on passing through the transition zone. This paper has been submitted for publication to Geophysics. It will appear, in Vol. 31 (1966).  相似文献   

Coral Associations, Biocorrosion, and Space Competition in Pedum spondyloideum (Gmelin) (Pectinacea, Bivalvia)     

Karl Kleemann 《Marine Ecology》1990,11(1):77-94

Abstract. In the northern Red Sea several genera of sclcractinian corals arc used as hosts by Pedum spondyloideum. High population densities lead to space competition. The bivalves use chemical means to interact with each other and with their host corals. Due to dorsal attachment and predominantly ventral growth - to keep pace with coral growth - biocorrosion is less obvious, than in Lilhophuga.  相似文献   

Isolation of differentially expressed genes from contaminant exposed European flounder by suppressive, subtractive hybridisation     

Sheader DL  Gensberg K  Lyons BP  Chipman K 《Marine environmental research》2004,58(2-5):553-557

Commercially farmed European flounder (Platichthys flesus) were treated with benzo[a]pyrene or cadmium under controlled laboratory conditions. In addition, animals were collected from the polluted Tyne and relatively clean Alde estuaries in the UK. Potential differentially expressed genes were isolated from liver tissue by means of suppressive, subtractive hybridisation. A total of 284 different mRNAs were identified as having the potential for being differentially expressed, of which 84 could be tentatively identified by homology with database sequences. These clones will form part of a flounder cDNA array for validation and future applications, with full identification being pursued for those expressed sequence tags for which differential expression can be confirmed by array technology.  相似文献   

A time-series study of particulate matter export in the North Pacific Subtropical Gyre based on Th : U disequilibrium     

Claudia Benitez-Nelson  Ken O. Buesseler  David M. Karl  John Andrews 《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(12)

Depth profiles of total ²³⁴Th (dissolved+particulate) were collected at Station ALOHA (22°45N, 158°00W) in the North Pacific Subtropical Gyre during 9 cruises from April 1999 to March 2000. Samples were collected and processed by a new 2 L technique that enables more detailed depth resolution then previous ²³⁴Th studies. Significant zones of particle export (²³⁴Th deficiency) and particle remineralization (²³⁴Th excess) were measured both temporally and with depth. ²³⁴Th derived particulate carbon (PC) and nitrogen (PN) fluxes were determined with steady-state and non-steady-state models and PC/²³⁴Th and PN/²³⁴Th ratios measured with both in situ pumps and free-drifting particle interceptor traps deployed at 150 m. ²³⁴Th based export estimates of 4.0±2.3 mmol C m⁻² d⁻¹ and 0.53±0.19 mmol N m⁻² d⁻¹, were approximately 60% higher than those measured in PIT style sediment traps from the same time period, 2.4±0.2 mmol C m⁻² d⁻¹ and 0.32±0.08 mmol N m⁻² d⁻¹. Most of this difference is attributable to two large export events that occurred during October and December 1999, when traps undercollected for ²³⁴Th by a factor of 2 to 4. ²³⁴Th export (ThE) ratios based on ²³⁴Th derived PC flux/¹⁴C based primary production ranged from 4% to 22% (average=8.8%). Our results confirm the recent estimates of C export by Emerson et al. (Nature 389 (1997) 951) and Sonnerup et al. (Deep-Sea Research I 46 (1999) 777) and indicate that C export from the oligotrophic ocean must be considered when discussing C sequestration in global climate change.  相似文献   

Effects of Cropping on Growth in the Mediterranean Seagrass Posidonia oceanica (L.) Delile*     

Karl J. Wittmann  Jorg A. Ott 《Marine Ecology》1982,3(2):151-159

Abstract. In view of proposed human use of seagrass production the influence of cropping on the growth of Posidonia oceanica (L.) DELILE was investigated. Removal of photosynthetic tissue reduces productivity throughout most of the growth season. This is consistent with the observed low natural grazing rates in aquatic macrophytes. A high mortality of shoots points to possible irreversible damage to the meadow. Harvesting of Posidonia should therefore be restricted to the end of the leaf growth period in early fall.  相似文献