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1.
Three outdoor plastic tanks were filled with North Sea water. The water was filtered free of algae and inoculated with the diatom Thalassiosira rotula. Under nearly natural nutrient supply an exponential plankton growth occurred with realistic cell concentrations. The flexible tanks (3–4 m3, 4–5 m deep) were exposed in the German Bight at a station in the outer harbour of Helgoland. The concentration changes of dissolved free amino acids (DFAA) were determined. The direct determination method applied permitted an analysis in picomole range without loss and with good reproducibility. The preliminary concentration of DFAA amounted to 0.2 μmol dm−3 in all three cultures, increasing during the development of T. rotula to 0.9–1.3 μmol dm−3 and decreasing in the stationary phase back again to smaller values. A high degree of temporal variation in DFAA was observed in all three cultures. In spite of these rapid changes in concentration, a good parallel development could be shown for all cultures, which extended as far as the spectra of the amino acids. Relationships between DFAA and other parameters of the culture-systems were examined. 相似文献
2.
Groundwater contamination with arsenic and other trace elements in an area of the pampa,province of Córdoba,Argentina 总被引:1,自引:0,他引:1
Hugo B. Nicolli Jose M. Suriano Miguel A. Gomez Peral Luis H. Ferpozzi Omar A. Baleani 《Environmental Geology》1989,14(1):3-16
A geochemical study of groundwater of the pampa in the province of Córdoba, Argentina, was performed; the area covered approximately 10,000 km2.Physical-chemical parameters, dissolved solids, and seven trace elements were determined in 60 selected water samples. Systematic and accurate measurements of arsenic, flourine, and vanadium were performed for the first time. Three trace element contaminants not reported earlier were found: an important one, selenium, and two others of less known effects, uranium and molybdenum.Eighty-four percent of the water analyzed showed arsenic contents over 0.05 mg/L, maximum contaminant level established by the U.S. Environmental Protection Agency (1982). The frequency distribution of trace elements was analyzed, and its fit to the lognormal distribution was proved by means of the Pearson and Kolmogorov-Smirnov test; the geographic distribution of the seven trace elements was mapped and its correlation with the anion-cation composition of the water was studied.The maximum arsenic, fluorine, vanadium, and uranium contents were found in the western part of the area under study, in waters containing dominant alkali metals in the cation composition. Maximum selenium and antimony contents were found in the eastern part of the area, while molybdenum distribution does not show any relationship with the other two groups. In addition, the geographic distribution of the trace elements seems to be related to the subsurface structure, which has been inferred using interactive digital analysis of Landsat imagery. The movements of the subsoil have disturbed surface and subsurface drainage influencing the water salinity and trace element contents.In order to investigate the origin of the contamination, 54 loess samples were collected in wells at depths ranging from the surface down to the water table. This loess, which has a high proportion of volcanic components, mainly rhyolitic glass, exhibits a chemical composition corresponding to that of a dacite.The loess and the volcanic glass show anomalous contents of all contaminant trace elements, mainly arsenic and selenium. For this reason loess is considered the most important contamination source in the groundwater under study. 相似文献
3.
The soil leakage ratio in the Mudu watershed,China 总被引:3,自引:0,他引:3
4.
Summary A human energy balance model is calculated using the homogeneous data set of Vienna, Austria (48°N and 16° E). Variations in the different stages of comfort since 1873 are discussed. The historical data are then used to generate scenarios of a changing climate and calculate the impact of these variations on thermal comfort.With 5 Figures 相似文献
5.
Hugo A. Loiciga 《The Professional geographer》1997,49(3):356-364
Runoff and precipitation scaling with respect to drainage area is analyzed for large river basins of the world, those with mean annual runoff in excess of 10 k3/yr. The usefulness of the specific runoff (runoff per unit drainage area, m/yr) to categorize runoff scaling laws across the complete spectrum of climatic and hydrologic conditions is evaluated. It is found that (1) runoff scales with drainage are in those river basins with specific runoff in excess of 0.15 m/yr (r2 = 0.88); (2) runoff scaling with drainage area shows remarkably high statistical correlation (r2= 0.97) in river basins with specific runoff equal to or larger than 1.0 m/yr; (3) runoff does not Inc.rease with Inc.reasing drainage area in river basins with specific runoff below 0.15 m/yr, where no discernible statistical association was found between runoff and drainage area; and (4) precipitation depth (m/yr) is inversely proportional to drainage area raised to a fractional exponent in river basins with specific runoff in excess of 0.15 m/yr. 相似文献
6.
Young Nathan L. Lemieux Jean-Michel Locat Pascal Demers Denis Delottier Hugo Mony Laura 《Hydrogeology Journal》2022,30(4):1337-1344
Hydrogeology Journal - An extensive network of multilevel vibrating-wire piezometers (VWP) was recently created to monitor the spatial and temporal variation of pore pressure (and hydraulic head)... 相似文献
7.
Filho Hugo Carlos Scheuermann Martins Carlos Guilherme Menezes Ricardo José Wink Dornelles Lucas Eduardo Consoli Nilo Cesar 《Geotechnical and Geological Engineering》2021,39(7):5395-5404
Geotechnical and Geological Engineering - Dispersive soils are susceptible to phenomena of internal and external erosion when in contact with relatively pure water due to its particle’s... 相似文献
8.
Pockmarks in the inner Oslofjord,Norway 总被引:5,自引:3,他引:2
Multibeam bathymetric surveys of the Inner Oslofjord, Norway have revealed a high density of pockmarks in the 179-km2 inner fjord area, which contains over 500 pockmarks of varying size, typically 20–50 m in diameter and 2–10 m deep. These
pockmarks have been investigated with a variety of techniques, including acoustic subbottom profiling, sedimentological and
geochemical analyses of cores, remotely operated vehicle observation, and morphometry. Both the distribution and shapes of
the pockmarks suggest that they are related to structures in the bedrock underlying relatively thin (<50 m) unconsolidated
glacial and postglacial sediments. The data provide no direct indication of a particular mode of pockmark formation, but release
of large amounts of biogenic, shallow methane seems unlikely. Several lines of evidence point to a continuous process of pockmark
formation followed by inactivity, with some pockmarks recently active whereas others have been inactive for a considerable
time. Some pockmarks are characterised by coarse sediment in their centres. The density, variety and easy access make this
pockmark field an ideal model area for pockmark research.
John S. Gray is deceased. 相似文献
9.
Javier García-Veigas Luis Gibert Dioni I. Cendón David Artiaga Hugo Corbí Jesús M. Soria Tim K. Lowenstein Enrique Sanz 《Basin Research》2020,32(5):916-948
The Lorca and Fortuna basins are two intramontane Neogene basins located in the eastern Betic Cordillera (SE Spain). During the Late Tortonian—Early Messinian, marine and continental evaporites precipitated in these basins as a consequence of increased marine restriction and isolation. Here we show a stratigraphic correlation between the evaporite records of these basins based on geochemical indicators. We use SO4 isotope compositions and Sr isotopic ratios in gypsum, and halite Br contents to characterize these units and to identify the marine or continental source of the waters feeding the evaporite basins. In addition, we review the available chronological information used to date these evaporites in Lorca (La Serrata Fm), including a thick saline deposit, that we correlate with the First Evaporitic Group in Fortuna (Los Baños Fm). This correlation is also supported by micropalaeontological data, giving a Late Tortonian age for this sequence. The Second Evaporitic Group, (Chicamo Fm), and the Third Evaporitic Group (Rambla Salada Fm) developed only in Fortuna during the Messinian. According to the palaeogeographical scheme presented here, the evaporites of the Lorca and Fortuna basins were formed during the Late Tortonian—Early Messinian, close to the Betic Seaway closure. Sulphate isotope compositions and Sr isotopic ratios of the Ribera Gypsum Mb, at the base of the Rambla Salada Fm (Fortuna basin), match those of the Late Messinian selenite gypsum beds in San Miguel de Salinas, in the near Bajo Segura basin (40 km to the East), and other Messinian Salinity Crisis gypsum deposits in the Mediterranean. According to these geochemical indicators and the uncertainty of the chronology of this unit, the assignment of the Rambla Salada Fm to the MSC cannot be ruled out. 相似文献
10.
Hugo G 《International journal of population geography : IJPG》1996,2(2):95-118
This paper "summarises some of the major changes which have occurred in international migration to, from, and within Asia in the last two decades....A number of theoretical challenges are put forward regarding the complex interrelationships between international population movements, economic development and social change. The employment of systems approaches, neoclassical economic theory, social networks and institutional approaches, and the potential role of population geography in developing a more comprehensive explanation of the changing dynamics of international migration in the region, are discussed. Also considered are the gender dimension in migration, remittance flows and their consequences, and policy issues." 相似文献