The geothermal model of Mersin (Turkey) region     

Y. Uras  M. Dag 《Geochemistry International》2016,54(6):559-568

The purpose of the study is to present the geothermal model of Mersin (Camili) region geothermal area with its geology, hydrogeology, hydrogeochemistry and isotope hydrology. The 1/25000 scale geology map obtained from the literature research is revised. In order to obtain a geothermal model, geological crosssections are extracted in certain points on the revised geology map. There are 3 hot water outlets. There are MC-1, C-1 and Uclu Cesme deep drillings. MC-1 well is 420 m, approximately 43.6°C temperature and 35 L/s flow rate and C-1 is 150 m, 40.3°C and 35 L/s. There is no exact information about the depth of Uclu Cesme well, but its average temperature is 37.5°C and it has a very low flow rate. Isotope analyses of the water samples obtained from these three wells and the Icme Dere are carried out by using the IRMS method with δ¹⁸O–δ²H (Deuterium) and IAEA method with ³H (Tritium). Radioactive Alpha-Beta determination and Physico-chemical and Bacteriological analyses of MC-1 well are made by using EPA 900.00. δ¹⁸O–δ²H isotope ratios clearly indicate a meteoric origin for the waters. In the light of all this information, the revised 1/25000 scare geology map of Mersin Guneyyolu (Camili) geothermal area is obtained; it is found out that hot waters are of meteoric origin; and the isotope hydrology and hydro-chemical assessment of the area is conducted to shape the geothermal model.  相似文献   

Transient dissolution patterns on stressed crystal surfaces     

Daniel Koehn  Dag Kristian Dysthe 《Geochimica et cosmochimica acta》2004,68(16):3317-3325

We present an experimental investigation on the dissolution of uniaxially stressed crystals of NaClO₃ in contact with brine. The crystals are immersed in a saturated fluid, stressed vertically by a piston and monitored constantly in situ with a CCD camera. The experiments are temperature-controlled and uniaxial shortening of the sample is measured with a high-resolution capacitance analyzer. Once the crystal is stressed it develops dissolution grooves on its free surface. The grooves are oriented with their long axis perpendicular to the direction of compressive stress and the initial distance between the parallel grooves is in accordance with the Asaro-Tiller-Grinfeld instability. We observe a novel, transient evolution of this roughness: The grooves on the crystal surface migrate upwards (against gravity), grow in size and the inter-groove distance increases linearly with time. During the coarsening of the pattern this switches from a one-dimensional geometry of parallel grooves to a two-dimensional geometry with horizontal and vertical grooves. At the end of the experiment one large groove travels across the crystal and the surface becomes smooth again. Uniaxial shortening of the crystal by pressure solution creep decays exponentially with time and shows no long term creep within the range of the resolution of the capacitance analyzer (accuracy of 100nm over a period of 14 days). This indicates that, while active, the fast transient processes on the free surface increase the solution concentration and thereby significantly slow down or stop pressure solution at the top of the crystal. This novel feedback mechanism can explain earlier results of cyclic pressure solution creep and demands development of a more complex theory of pressure-solution creep including processes that act on free surfaces.  相似文献   

UV-B susceptibility and photoprotection of Arctic Daphnia morphotypes     

Dag O. Hessen  Jan Borgeraas  Kirsten Kessler  Unn Hilde Refseth 《Polar research》1999,18(2):345-352

UV-B tolerance and susceptibility of high Arctic morphotypes of the Daphnia pulexl D. tenebrosa complex were assessed by in situ experiments at Ny-Ålesund, Svalbard (79°N). Animals from local ponds were exposed to ambient light plus additional UV-B from lamps in a greenhouse facility. Taxonomic affinities did not appear as major determinants of UV susceptibility, but a major difference in UV-B tolerance was seen between morphotypes with pigmented carapaces and those without, the latter being far more susceptible. Assays on levels of carotene and the anti-oxidant enzymes catalase and superoxide dismutase did not reveal clear-cut differences between populations, and could not account for the higher tolerance in pigmented populations. Levels of glutathione transferase were higher in the transparent population, however. In the absence of blue light and UV, laboratory reared animals did not reconstitute their carapace melanization after moulting, indicating that short-wave light is the cue for melanin synthesis. Tests on melanized individuals and individuals of the same population reared indoors through 1-2 moults supported the major role of melanin for UV protection. Periods with high UV exposure during hatching of ephippia could induce shifts in morphotype or clonal dominance.  相似文献   

Wave power statistics for individual waves     

Dag Myrhaug  Bernt J. Leira  Håvard Holm 《Applied Ocean Research》2009,31(4):246-250

The paper provides a bivariate distribution of wave power and wave height, as well as a bivariate distribution of wave power and wave period; both bivariate distributions are for individual waves within a sea state. This is relevant for e.g. making assessments of wave power devices and their potential for converting energy from waves. The results can be applied to compare systematically the wave power potential for individual waves in a given sea state at different locations.  相似文献   

Postglacial depositional environments and sedimentation rates in the Norwegian Channel off southern Norway     

Leif Rise  Reidulv Be  Dag Ottesen  Oddvar Longva  Heidi A. Olsen 《Marine Geology》2008,251(1-2):124-138

Based on seismic profiles, multibeam bathymetry and sediment cores, an improved understanding of the deglaciation/postglacial history of the southern part of the Norwegian Channel has been obtained. The Norwegian Channel Ice Stream started to recede from the shelf edge ca. 15.5 ka BP (¹⁴C ages are used throughout). Approximately 500–1000 years later the ice margin was located east of the deep Skagerrak trough. At that time, the Norwegian Channel off southern Norway had become a large fjord-like embayment, surrounded by the grounded ice sheet along the northern slope and possibly stagnant ice remnants at the southern flank. The Norwegian Channel off southern Norway has been the main sediment trap of the North Sea, and south of Egersund more than 200 m of sediments have been deposited since the start of the deglaciation. Five seismic units are mapped. The oldest unit E occurs in some of the deepest troughs, and was deposited immediately after the ice became buoyant. Unit D is acoustically massive and comprises mass-movement deposits in eastern Skagerrak and south of Egersund. Unit C (in the channel southwest of Lista/Egersund) is interpreted to comprise mainly bottom current deposits derived from palaeo-rivers, e.g. Elben. During deposition of unit C (ca. 14.5–13 ka BP), there was limited inflow of Atlantic water. A change in depositional environment at ca. 13 ka BP is related to an increased inflow of saline water and more open hydrographic circulation. Widely distributed, acoustically stratified clays of unit B were deposited ca. 13–10 ka BP. The Holocene Unit A shows a depositional pattern broadly similar to that of unit B.  相似文献   

Identification and implications of fight hydrocarbon fluid inclusions from the Proterozoic Bidjovagge gold-copper deposit, Finnmark, Norway     

David C. Ettner  Sten Lindblom  Dag Karlsen 《Applied Geochemistry》1996,11(6):745-755

Carbonic fluid inclusions were observed in quartz-bearing veins at the Proterozoic Bidjovagge AuCu deposit within the Kautokeino greenstone belt in Norway, where mineralization occurred in oxidation zones of graphitic schists. A primary fluid inclusion zonation was observed with C0₂-rich fluid inclusions in the structural footwall of the deposit, and CH₄-rich inclusions within the ore zone in the oxidation zone. Microthermometry of the primary hydrocarbon inclusions revealed 2 groups; (1) a group which homogenized between −125°C and the critical temperature of CH₄ (−82.1°C), which indicated the presence of pure CH₄, and (2) a group which homogenized between the critical temperature of CH₄ and −42°C, which indicated the presence CH₄ and higher hydrocarbons (HHC). Raman microprobe analyses of the first group confirmed the presence of CH₄. The second inclusion group were fluorescent, and Raman spectra clearly displayed CH₄,C₂H₆, and rarer C₃H₈ peaks. A typical feature of the Raman spectra were elevated baselines at the hydrocarbon peaks. Carbon peaks were also usually detected in each inclusion by Raman analysis. Bulk gas chromatography analyses of samples containing the first group (CH₄) indicated the presence of CH₄ and low concentrations of C₂H₆ and C₃H₈. Gas chromatography analyses of samples containing the second group (CH₄ and higher hydrocarbons) confirmed the presence of CH₄, and higher hydrocarbons such as C₂H₆ and C₃H₈ and also butanes. Based on the spacial zonation of hydrocarbons and the estimated PT conditions of 300 to 375°C and 2 to 4 kbars, the authors suggest an abiotic origin for the hydrocarbons. It is suggested that the hydrothermal fluids oxidized the graphitic schist, precipitated Cu and Au and formed light gas hydrocarbons.  相似文献   

Effects of wave age and air stability on whitecap coverage     

Dag Myrhaug  Lars Erik Holmedal 《Coastal Engineering》2008,55(12):959-966

The paper considers the effects of wave age and air stability on the whitecap coverage at sea. This is made by using the logarithmic mean wind velocity profile including a stability function as well as adopting a recent wave age dependent sea surface roughness formula. The results are valid for wind waves in local equilibrium with the steady wind. Examples of results demonstrate clear effects of wave age and air stability on the whitecap coverage. Comparisons are also made with field measurements by Sugihara et al. [Sugihara, Y., et al., 2007. Variation of whitecap coverage with wave-field conditions. J. Mar. Syst. 66, 47–60], representing unstable air stability conditions. Although the data basis is limited, the wave age independent Charnock sea roughness based predictions capture the main features of the observed whitecap coverage, suggesting a stronger dependence on air stability than on wave age in the data.  相似文献   

The rise and fall of factory trawlers: An eclectic approach     

Dag Standal 《Marine Policy》2008

Factory trawlers are the most controversial vessel group in Norwegian fisheries. At the time the fleet emerged, stern trawling in combination with on-board processing of cod fillets was regarded as a major innovation. However, the deep-sea fleet was intended to be a stable supplier of fish to the land-based industry. Factory trawlers were not a part of the political project. On the contrary, the vessels represented a serious departure from the traditional employment system for the fisheries’ dependent districts. Factory trawlers have, since the seventies, been regarded as the main enemy to the coastal vessels and the land-based industry. The vessels have been subject to a profound debate about several built-in contradictory goals for the fisheries policy, such as the ideal of employment for all and the need for a profitable sector without state subsidies. Despite a series of policy-driven initiatives to remove the factory trawlers, the fleet has been one of the most profitable vessel groups in the Norwegian fisheries. Nonetheless, the fleet is now marginalised in the number of vessels and transformed into an obedient supplier of round fish to the land-based industry. In this article, we outline the history of the Norwegian factory trawlers and how the fleet was subject to a series of critical changes reflecting the complexity of the vessels.  相似文献   

Random wave-induced onshore scour characteristics around submerged breakwaters using a stochastic method     

Dag Myrhaug  Muk Chen Ong 《Ocean Engineering》2010,37(13):1233-1238

This paper provides a stochastic method by which the two-dimensional onshore scour characteristics along the base of submerged breakwaters exposed to normally incident random waves on both sloping and horizontal sandy seabed can be derived. Here the formulas for the regular wave-induced scour characteristics provided by Young and Testik (2009) are used. These formulas are combined with describing the waves as a stationary Gaussian narrow-band random process to derive the random wave-induced onshore scour characteristics; the maximum scour depth, the scour length, and the distance of the maximum scour depth location from the onshore breakwater face. An example of calculation is also provided.  相似文献   

Input of organic carbon as determinant of nutrient fluxes,light climate and productivity in the Ob and Yenisey estuaries     

Dag O. Hessen  JoLynn Carroll  Berit Kjeldstad  Anton A. Korosov  Lasse H. Pettersson  Dmitry Pozdnyakov  Kai Sørensen 《Estuarine, Coastal and Shelf Science》2010

Spectral light attenuation profiles and concentrations of total and dissolved carbon (C), nutrients and chlorophyll a (Chla) were studied along transects running from the river mouth to the Kara Sea during late summer 2003 for the Yenisey and fall 2005 for the Ob estuaries. Earth Observation data were used to generate composite images of water color and Chla distribution over the estuaries and the Kara Sea to reveal the spatial impact of the river efflux in terms of optical properties.  相似文献