Element-specific detectors for liquid chromatography: The determination of arsenic compounds

Systems for the determination of trace element compounds consisting of liquid chromatographs (LC) (high pressure liquid chromatographs, ion chromatographs) and graphite furnace atomic absorption spectrometers (GFAAS) or inductively coupled argon plasma emission spectrometers (ICP) as single- or multi-element-specific detectors are described. The applications of these systems to the determination of arsenic compounds are reviewed. The absolute detection limits of these systems for arsenic are in the low nanogram range. These detection limits can probably be improved by two-three orders of magnitude by coupling an inductively coupled argon plasma-mass spectrometer instrument to the liquid chromatograph. The advantages and drawbacks of the LC-GFAAS and LC-ICP systems are outlined. These systems can separate and identify trace element compounds that are kinetically or thermodynamically stable under the conditions of the chromatography. Labile compounds cannot be determined by these systems. Wide application of these systems to problems of trace element research will lead to the identification of hitherto unknown trace element compounds, to a better understanding of the nutritional and toxic properties of trace element compounds, and to a better definition of trace element cycles.     

Submarine structures in the Gulf of İzmit,based on multichannel seismic reflection and multibeam bathymetry

Multichannel seismic reflection and multi-beam bathymetry data were used to study the active tectonic and syn-tectonic stratigraphic setting of the Gulf of ?zmit in the Marmara Sea (Turkey). The gulf and its near surroundings are deformed by the northern strand of the dextral North Anatolian Fault. Three connected basins of the gulf, the western (Dar?ca), central (Karamürsel) and eastern (Gölcük) basins are formed by active faults, as observed in the stacked and migrated seismic sections, as well as the bathymetry map. The main branch and its surrounding sedimentary strata are confined by normal faults to the north and south. These normal faults converge at depth towards the main fault, forming a negative flower structure in the gulf. The average maximum sedimentation rate is 0.4 mm/year according to the three most recent seismo-stratigraphic units that are located to the south of the main fault branch within the central basin. A 20° south-dipping major discontinuity along the northern shoreline of the gulf represents the top of Paleozoic basement.     

Northern Adriatic Rocky Reef Fishes at Low Winter Temperatures

Abstract. The behavioural ecology of certain northern Adriatic fishes was observed from January to April at a water temperature of 7–11 ^oC. The fishes studied here do not migrate to deeper waters. Most of the benthic fishes show a similar distribution over the substrate in winter and in summer; in winter, however, they are very inactive and hide in the substrate. Suprabenthic fishes aggregate in littoral caves where they form dense, inactive, mixed aggregations. Certain hemipelagic and pelagic fishes join to form very dense aggregations at specific sites in the open waters of bays. Littoral predators display high feeding activity at a time when their prey is inactive. I present a hypothesis concerning possible implications of seasonally cyclic environmental temperatures for a sympatric community of non-migrating fishes.     

Feeding Ecology of three Populations of Blennius incognitus BATH 1968 (Pisces: Teleostei: Blenniidae) during the Reproduptive Period and under Human Influence

Abstract. Samples of Blennius incognitus from three differently polluted locations on the Istrian west coast (Adriatic Sea, Yugoslavia) were collected in early July during the spawning season. The gut content was analyzed employing the occurrence and point (relative volumetric) method. This fish grazes the surface of the rocky substratum. Inhabiting small benthic animals are ingested together with algae and detritus. The diet depends on the composition and condition of the covering phytal and its inhabiting fauna. A decrease of available animal food seems to intensify grazing on the substrate. A sexual dimorphism in the feeding habit during the reproductive period exists. Females feed more on animals; males feed more on substrate and in cases also on eggs of their own species.     

The national geophysical data center bathymetric program

The National Geophysical Data Center's (NGDC's) mission is data management in the broadest sense, playing a role in the nation's research into the environment and providing data to a wide group of users. NGDC also operates components of the International Council of Scientific Unions (ICSU) World Data Center A. The Marine Geology and Geophysics Division of NGDC handles bathymetric data acquisition, manipulation, archival, and dissemination and operates the International Hydrographic Organization Data Center for Digital Bathymetry. Four major data bases have been developed to manage the large volume of data received: the Global Marine Geophysical Data Base (geophysical data acquired in a time series); the NOAA National Ocean Service Hydrographic Data Base; the International Hydrographic Data Base (contains bathymetric data, other than NOS surveys, with no time‐tagging); and the Multibeam Bathymetric Data Base. In addition, gridded data sets such as ETOPO5 are available from NGDC. Bathymetric data are acquired by NGDC through data exchange, funded and contract programs, processing of long‐term data holdings, data digitization from hardcopy sources, and national and international linkages. NGDC personnel participate nationally and internationally on numerous committees associated with studies of the seafloor including charting and bathymetric needs.     

Mud transportation on a steep shelf,Rio de La Plata shelf,Puerto Rico

Hurricanes David (August 29–30, 1979) and Frederick (September 2–5, 1979) caused major flooding of the Rio de La Plata in northern Puerto Rico. A thin mud layer was deposited across the narrow insular shelf adjacent to the river mouth. Within 5 months, fair-weather shelf-winnowing processes moved the mud layer entirely from the shelf, 0.5 to 2 km to the shelf break at the 50-m contour and beyond. The process of mud movement is termed “mud hopping.”     

用标记法压缩色域

提出了一种新的色域压缩方法。用此种方法不仅能将超色域颜色压缩到目标设备的色域内,使色域内大部分颜色保护不变,而且能保证被压缩图像部分的灰色级不受损失;提出了判断色域的检测方法。试验证明,使用该检测方法处理的图像的超色域与用Photoshop中的色域警告处理的超色域非常相似。     

Polarimetry and spectroscopy of RX J1141.3−6410: a single‐pole AM Her system

We present polarimetric and spectroscopic observations of the ROSAT source RX J1141.3−6410, recently identified as a polar. The detection of circular polarization variations, with an amplitude of 10 per cent, over a 3.16-h period confirms that the system is a polar (AM Herculis star). Supporting evidence comes from the nature of the emission lines and their radial velocity variability. In addition, we observe continuum slope changes in the far-red spectral region (∼6000–8200 Å), indicative of phase dependent cyclotron emission. Polarimetric modelling at two wavelengths establishes RX J1141.3−6410 as a single-pole system, with i ∼ β ∼70°. The accretion region is extended in magnetic longitude, and is totally self-occulted for ∼25 per cent of the orbit. The radial velocity curves derived from the emission lines show a phasing with maximum blueshift occurring with Δ φ ∼0.05 of maximum intensity and circular polarisation. In addition, the broader component of the lines exhibit a substantial radial velocity phase shift with respect to the narrower component, in the sense that the broad component preceeds the narrow. This can be readily understood if the narrower component is principally a result of orbital motion of the stream material and the broad component mainly a result of streaming motion near the coupling region. The phasing of the Ca  ii near-infrared line radial velocities also supports this general picture.     

The hydrogeochemistry of the Kärkevagge Valley, Lapland, Sweden

The Kärkejokk (jokk = Lappish for brook) is rich in sulfate and calcium, both elements having been considered enigmatic. To resolve these problems we collected waters at 13 sites during 27 June to 1 September 1996. Nine sites were in the Kärkevagge, and the others in the drainage towards lake Torne Träsk. Rain waters were collected the same period. Conductivity, pH, and temperature were measured in the field, whereas salt load and the elements Na, K, Ca, Mg, S, Si, Fe, Al, Mn, Zn, Sr, and Ba were determined in the laboratory.
Mixing models based on rain water and leaching products of the major bedrocks do not explain observed element patterns except in the lower parts of the jokk. However, oxidation of pyrite has formed acid, sulfate–rich solutions that released Ca and Mg from limestones, and Fe, Mn, Al, and Si, from black shales (Malmsten 1998; Malmsten et al. 2000). Conservative mixing models, using rain water, leached bedrock and pyrite, match the jokk waters quite well, and sulfur isotope data corroborate these findings. The nearby Låktajokk, and Vassijokk also contain much S.
Where these waters debouch they may deposit Si, Al, and Ca, but only little S on various rocks. Total rock analyses, thermodynamic and X–ray data suggest that gypsum, barite, or alunite are not formed in major quantities.
These models show that the hydrogeochemistry of the Kärkejokk may be less enigmatic than often assumed.