Ten-year observation of the Gironde tributary fluvial system: fluxes of suspended matter, particulate organic carbon and cadmium     

Jrg Schfer  Grard Blanc  Yvon Lapaquellerie  Noëlle Maillet  Eric Maneux  Henry Etcheber 《Marine Chemistry》2002,79(3-4)

A program of long-term observation of suspended solids (TSS), particulate organic carbon (POC) and cadmium transported into the Gironde estuary (France) by its major tributaries has been carried out between 1990 and 1999. This decade included contrasting hydrologic cycles and appears representative of a much longer period (1959–1999). The Garonne and the Dordogne river systems are the main tributaries of the Gironde estuary and derive their waters from drainage basins with different geological, industrial and agricultural features. To better understand their respective contributions, they have been observed separately and compared. Water and TSS fluxes of the Garonne River show greater temporal variations and discharge is more related to the hydrology of the drainage basin (e.g. wet/dry years, local flood events etc.). As POC and particulate Cd concentrations in suspended matter are much less variable than turbidity, their fluxes are mainly controlled by the TSS transport. A major part of annual fluxes of TSS and associated pollutants may occur within few flood days (depending on various parameters, e.g. intensity, duration, season, etc.), and also the succession of dry and wet years has an important influence on annual fluxes. The presented data allow calculating fluvial inputs into the Gironde as the sum of fluxes transported by its major tributaries, the Garonne and the Dordogne river systems. Mean annual fluxes into the Gironde observed in 1990–1999 are about 34×10⁹ m³ year⁻¹ for river water, 3.24×10⁶ t year⁻¹ for suspended solids (TSS) and 9.88×10⁹ mol year⁻¹ for particulate organic carbon (POC). Generally, these fluxes are dominated by the contributions of the Garonne River. However, in dry years, the mean contribution of the Dordogne river system (including Dronne and Isle rivers) to the POC input into the estuary exceeded that of the Garonne. This reflects significant differences in vegetation and soil due to natural properties and land management of the basins. Mean Cd fluxes into the estuary are about 110×10³ mol year⁻¹ of which 19.6×10³ mol year⁻¹ are transported in the dissolved and 90.8×10³ mol year⁻¹ in the particulate phases, respectively. In 1991 (dry year), the net (dissolved) Cd flux towards the ocean exceeded the gross fluvial input of total Cd, suggesting the release of Cd from an important stock in the maximum turbidity zone (MTZ) or the fluid mud of the Gironde estuary.  相似文献   

Measurement of sediment resuspension rates in Long Island Sound   总被引：1，自引：0，他引：1  

Henry Bokuniewicz  Larry McTiernan  Wayne Davis 《Geo-Marine Letters》1991,11(3-4):159-161

Resuspension rates have been measured on Long Island Sound sediments (New York/Connecticut, USA) under an oscillating grid, using a flume, and in place, using high frequency acoustics, transmissometers, and sediment traps. Despite differences, the results compare favorably. The methods all provide an order-of-magnitude estimate of the resuspension rate and increases under storm conditions can be estimated.  相似文献   

Characterizing benthic substrates of Santa Monica Bay with seafloor photography and multibeam sonar imagery     

Edwards BD  Dartnell P  Chezar H 《Marine environmental research》2003,56(1-2):47-66

Seafloor photography from three cruises is combined with multibeam sonar imagery to characterize benthic substrates and associated fauna of Santa Monica Bay, California. The multibeam EM1000 imagery was collected in 1996. Two sampling cruises (in 1998 and 1999) provided photographs at 142 sites throughout the Bay; a final cruise (in 2000) collected still photographs and continuous video along nine transects on the mainland shelf from Pt. Dume to the Palos Verdes peninsula. Muddy substrates (typically low backscatter) were the predominant habitat throughout the Santa Monica Bay, from the 20 m isobath to the adjacent Santa Monica basin floor (780 m). Bioturbation was pervasive as evidenced by abundant open burrows, mounds, and faunal tracks and trails. Sandy substrates (typically intermediate to high backscatter) were restricted to the innermost mainland shelf and a narrow outer shelf band north of Santa Monica Canyon. Cobble and gravel substrates (high backscatter) were restricted to the innermost shelf south of El Segundo and limited parts of the shelf edge. Rocky substrates (high backscatter) with interspersed patches of sand and gravel occurred on the high-relief marginal plateau and along parts of the shelf break offshore of Malibu.  相似文献   

Time varying rotary spectra     

Henry Crew  Noel Plutchak 《Journal of Oceanography》1974,30(2):61-66

A method for computing and displaying the temporal variation of rotary spectral estimates is described. The method is applied to time series measurements of highly nonstationary winds and currents. The results indicate approximately fortnightly modulation of diurnal wind energy and inertial current energy.  相似文献   

A strategy for monitoring of contaminant distributions resulting from proposed sewage sludge disposal at the 106-mile ocean disposal site     

Thomas P O&#x;Connor  Henry A Walker  John F Paul  Victor J Bierman 《Marine environmental research》1985,16(2):127-150

It has been proposed that future ocean disposal of sewage sludge from the US east coast be done at a site beyond the edge of the continental shelf. In anticipation of that, a monitoring strategy has been developed to determine the average spatial distribution of contamination. The strategy is an iterative series of measurements developed from models of sludge dispersion and settling which are based on characteristics of the disposal site and sewage sludge. Once disposal is initiated at the site, the strategy requires sampling the upper mixed layer at 36 stations, mostly within 100 km of the site, and deployment of near-bottom sediment traps along a line extending 300 km away from the site. Based on initial results, subsequent sampling locations will be selected to refine estimates of the detectable extent of sludge-derived contamination. The sludge constituents which can be used to detect sludge in water at a dilution of 10⁶ and sludge in sediment traps when diluted by 100 with natural material include zinc, PCBs, coprostanol and spores of the bacterium Clostridium perfringens. Other synthetic organic compounds, besides PCB, may prove to be useful tracers.  相似文献   

Oxygen and hydrogen isotope evidence for meteoric water infiltration during mylonitization and uplift in the Ruby Mountains-East Humboldt Range core complex,Nevada     

Henry C. Fricke  Stephen M. Wickham  James R. O'Neil 《Contributions to Mineralogy and Petrology》1992,111(2):203-221

Stable isotope analyses of rocks and minerals associated with the detachment fault and underlying mylonite zone exposed at Secret Creek gorge and other localities in the Ruby-East Humboldt Range metamorphic core complex in northeastern Nevada provide convincing evidence for meteoric water infiltration during mylonitization. Whole-rock ¹⁸O values of the lower plate quartzite mylonites (95% modal quartz) have been lowered by up to 10 per mil compared with structurally lower, compositionally similar, unmylonitized material. Biotite from these rocks has D values ranging from -125 to -175, compared to values of -55 to-70 in biotite from unmylonitized rocks. Mylonitized leucogranites have large disequilibrium oxygen isotope fractionations ( ^{quartz-feldspar} up to 8 per mil) relative to magmatic values ( ^{quartz-feldspar}1 to 2 per mil)). Meteoric water is the only major oxygen and hydrogen reservoir with an isotopic composition capable of generating the observed values. Fluid inclusion water from unstrained quartz in silicified breccia has a D value of-119 which provides a plausible estimate of the D of the infiltrating fluid, and is similar to the isotopic composition of present-day and Tertiary local meteoric water. The quartzite mylonite biotites would have been in equilibrium with such a fluid at temperatures of 480–620° C, similar to independent estimates of the temperature of mylonitization. The relatively high temperatures required for isotopic exchange between quartz and water, the occurrence of fluid inclusion trails and deformed veins in quartzite mylonites, and the spatial association of the low-¹⁸O, low-D rocks with the shear zone all constrain isotopic exchange to the mylonitic (plastic) deformation event. These observations suggest thata significant amount of meteoric water infiltrated the shear zone during mylonitization to depths of at least 5 to 10 km below the surface. The depth of penetration of meteoric fluids into the lower plate mylonites was at least 70 meters below the detachment fault. In contrast, the upper-plate unmylonitized fault slices are dominated by brittle fracture and are often intensely veined (carbonates) or silicified (volcanic rocks and breccias). The fluids associated with the veining and silicification were also meteoric as evidenced by low ¹⁸O values of the veins, which are often 10 per mil lower than the adjacent carbonate matrix, and the exceptionally low ¹⁸O values (down to-4.4) of the breccias. Several previous studies have documented the infiltration of meteoric fluids into the brittley deformed upper plate rocks of core complexes, but this study provides convincing evidence that surface fluids have penetrated lower plate rocks undergoing plastic deformation. It is proposed that infiltration took place as the shear zone began the transition from plastic flow to brittle fracture while the lower plate rocks were being uplifted. During this period, plastic flow and brittle fracture were operating simultaneously, perhaps allowing upper plate meteoric fluids to be seismically pumped down into the lower plate mylonites.  相似文献   

Multi-proxy geoarchaeological study redefines understanding of the paleocoastlines and ancient harbours of Liman Tepe (Iskele, Turkey)     

Beverly N. Goodman  Eduard G. Reinhardt  Hendrik W. Dey  Joseph I. Boyce  Henry P. Schwarcz  Vasif Saho&#;lu  Hayat Erkanal  Michal Artzy 《地学学报》2009,21(2):97-104

Determining the position of Liman Tepe's (ancient `Clazomenae') archaeological features relative to the coastline is important for understanding their intended function and reconstructing the character of Aegean maritime activities and sea-based trade. Previous attempts at reconstructing harbour locations at Liman Tepe relied on extrapolating paleoenvironments based on modern surface topography. In light of this, samples from a sediment coring survey and terrestrial and underwater archaeological excavations were analysed using multi-proxy geoarchaeological methods to determine paleoenvironmental facies. Micropaleontological (foraminifera), sedimentological (grain-size analysis) and geochemical (δ¹³C/δ¹⁸O) analyses resulted in the reconstruction of the coastal paleogeomorphology, including the presence and absence of ancient harbouring areas. Neither of the previous coastal reconstructions was supported by the new results. Instead, two separate harbouring areas were recognized, one coincident with the Early Bronze Age (4800–3900 years bp) and a second during the archaic and classical periods ( c. 2800–2400 years bp). These results emphasize the necessity for multi-proxy geoarchaeological studies when approaching coastal archaeological sites as a means to reconstruct paleocoastal geomorphology and understand ancient maritime development better .  相似文献   

Caldera formation in the Rum Central Igneous Complex, Scotland     

Valentin R. Troll  C. Henry Emeleus  Colin H. Donaldson 《Bulletin of Volcanology》2000,62(4-5):301-317

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How well can the subsurface storage–discharge relation be interpreted and predicted using the geometric factors in headwater areas?          下载免费PDF全文

Jintao Liu  Xiaole Han  Xi Chen  Henry Lin  Aihua Wang 《水文研究》2016,30(25):4826-4840

Headwater storage–discharge (S–Q) remains one of the least understood processes, and there is renewed interest in the S–Q relation. How well can the S–Q relation be interpreted mechanistically using geometric factors? In this paper, the hillslope storage Boussinesq and hillslope storage kinematic wave equation were adopted to guide the theoretical derivations. Analytical solutions were derived based on the hsKW equation for nine idealized hillslope aquifers, which were subdivided into two groups, i.e. hillslope aquifers with exponential hillslope width function (C1) and hillslope aquifers with Gaussian hillslope width function (C2). We found that analytical expressions of the S–Q relation can be derived for C1 hillslope aquifers. For more compound hillslope aquifers, i.e. C2, no explicit S–Q relation can be obtained. The whole subsurface recession after a rainstorm is simulated by applying the initial saturation condition. We found that the simulated S–Q processes can be characterized by a two‐phase recession, i.e. quick and slow recession. The time (t_b) at the dividing point of the quick and slow recessions depends on the geometric factors, such as the plan and profile curvature. In the quick recession for C1, many of the S–Q curves can be described as linear or quasi‐linear functions, which indicate that linear reservoir models can be applied approximately for recession simulations. However, during the slow recession phase of C1 and during the whole recession of C2, the S–Q relations are highly non‐linear. Finally, we compared the hillslope storage kinematic wave and hillslope storage Boussinesq models for simulating subsurface water recession after a rainstorm event in a real‐world headwater catchment (G5) in China. Through comparison of the recession slope curves, we found that the simulated results of the models employing the Gaussian hillslope width function match the observed hydrograph. The results indicated that appropriate organization of the hillslope geometric factors enhances our ability to make S–Q predictions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

方解石和钾长石在模拟蚯蚓肠液中的初始溶解动力学机理及意义     

蔡建林  TENG Hui Henry  王钺博  张坚超 《岩石矿物学杂志》2022,41(4):818-834

蚯蚓肠道内小分子有机酸与摄入的土壤矿物相互作用,加速矿物溶解。摄入的土壤在蚯蚓肠道内平均停留时间约为12 h,不足以使土壤矿物产生显著的溶解特征,因此这一过程难以在蚯蚓体内进行评估。本研究通过体外实验控制pH值和有机酸浓度,模拟蚯蚓肠道中有机酸对土壤中常见矿物的溶解反应,探讨了方解石和钾长石在蚯蚓肠道环境中的初始溶解动力学。研究发现,矿物在混合有机酸中的溶解速率比在纯水中高一个数量级,说明有机配体和质子促进了矿物溶解。溶解速率及粒度分析表明,方解石(CaCO₃)溶解速率不受溶解过程中粒度变化的影响,而钾长石(KAlSi₃O₈)粒度在溶解期间未出现显著变化。在此基础上,采用初始速率法模拟了钾长石的初始溶解动力学,计算得出的溶解速率表明钾长石在溶解初期主要为表面K~+的释放。使用缩核模型(shrink core model)和Hixson-Crowell模型对方解石溶解过程进行动力学解析,发现方解石的溶解主要受溶液中反应物内扩散的速率影响。这定量描述了两种矿物在有机酸溶液和纯水中的溶解差异。现有研究表明,有机配体和质子协同促...  相似文献