Catastrophic events reveal the dynamic nature of salt-marsh vegetation in Southern California   总被引：1，自引：0，他引：1  

Joy B. Zedler  Jordan Covin  Chris Nordby  Phil Williams  John Boland 《Estuaries and Coasts》1986,9(1):75-80

Recent hydrological disturbances, including flooding, dry-season streamflow, and drought, greatly altered coastal wetland habitats in sourthern California. At Tijuana Estuary, a six-year study of salt-marsh vegetation patterns during these rare conditions documented substantial temporal variability in plant growth and distribution. Important to cordgrass (Spartina foliosa Trin.) dynamics were the amount and timing of streamflows, which reduced soil salinity and alleviated stresses on plant growth. Poorest growing conditions occurred in 1984 when both river and tidal flows were lacking; soils had low moisture and extreme salinities (avg.=104‰ in September). Plant stress was documented in 1984 as high mortality (62% fewer stems than in 1983) and reduced height (19% less than in 1983). Cordgrass height was greatest in 1980 following winter flooding (20% increase over 1979); densities were greatest in 1983 with summer freshwater influxes (60% increase over 1982). A carbon allocation model is proposed to explain the varied responses.  相似文献   

Determination of Carbonate Carbon in 41 International Geochemical Reference Samples by Coulometric Method     

Chris C.Y. CHAN 《Geostandards and Geoanalytical Research》1986,10(2):131-134

The carbonate-carbon (CO₂) content of forty-one geochemical reference samples has been determined by coulometric method following acid treatment of the sample for releasing CO₂. The method is superior to the conventional methods in speed, accuracy, sensitivity, specificity, and the coverage of CO₂ range. The results on NBS limestone samples agree well with the certified values. The precision of the method is 0.5 % r.s.d., and the practical detection limit is 10 ppm C.  相似文献   

Carbon dioxide recovery from industrial processes     

Jacco C. M. Farla  Chris A. Hendriks  Kornelis Blok 《Climatic change》1995,29(4):439-461

The ongoing human-induced emission of carbon dioxide (CO₂) threatens to change the earth's climate. One possible way of decreasing CO₂ emissions is to apply CO₂ removal, which involves recovering of carbon dioxide from energy conversion processes and storing it outside the atmosphere. Since the 1980's, the possibilities for recovering CO₂ from thermal power plants received increasing attention.In this study possible techniques of recovering CO₂ from large-scale industrial processes are assessed.In some industrial processes, e.g. ammonia production, CO₂ is recovered from the process streams to prevent it from interfering with the production process. The CO₂ thus recovered can easily be dehydrated and compressed, at low cost. In the iron and steel industry, carbon dioxide can be recovered from blast furnace gas. In the petrochemical industry CO₂ can be recovered from flue gases, using low-temperature heat for the separation process.Carbon dioxide can be recovered from large-scale industrial processes and in some cases the cost of recovery is significantly less than CO₂ recovery from thermal power plants. Therefore this option should be studied further and should be considered if carbon dioxide removal is introduced on a wide scale.  相似文献   

Congressman Mike Oxley Talks About Superfund Reform     

Chris Reimer 《Ground Water Monitoring & Remediation》1995,15(3):93-95

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Autosuspension and the energetics of two-phase flows: Reply to comments on ‘experimental test of autosuspension’ by J. B. Southard and M. E. Mackintosh     

Chris Paola  John B. Southard 《地球表面变化过程与地形》1983,8(3):273-279

The experimental programme of Southard and Mackintosh (1981) provides a definitive refutation of the autosuspension criterion as it was originally defined. A simple energy budget for dilute two-phase flow is derived from continuum theory of mixtures; it shows that Bagnold's criterion is based on an arbitrary comparison of two elements of the complete two-phase system. It is recommended that facile, ab hoc criteria for the behaviour of such complex flows be avoided in favour of analyses based on fundamental equations of motion.  相似文献   

Parajamesonite revisited: background of the discreditation of an enigmatic mineral species     

Gábor Papp  Alan J. Criddle  Chris J. Stanley  László Kriston  Géza Nagy 《Swiss Journal of Geoscience》2007,100(3):495-502

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Late Quaternary-Holocene lake-level changes in the eastern margin of the Thar Desert,India     

Hema Achyuthan  Amal Kar  Chris Eastoe 《Journal of Paleolimnology》2007,38(4):493-507

A study on two closed salt lake basins, Tal Chapar and Parihara in the eastern margin of the Thar Desert, Rajasthan, was carried out to unravel late Quaternary geomorphic evolution of these saline lakes. Both lakes are elliptical in shape bordered by stabilised dunes, and are oriented in a NE-SW direction, i.e., in the direction of the prevailing summer monsoon wind. Both lakes have been formed in the wind-shadow zones of isolated hills of Precambrian quartzite. Our study indicates that the late Quaternary sediments in the lakes began with the cyclic deposition of laminated fine silt layers (0.5 m thick), rich in organic matter, alternating with ripple cross-bedded sand layers (each ∼1.5–2 m thick). Sand layers that are moderately sorted are separated by laminated silt-clay layers with gypsum/calcite and this unit occurs in the upper most 4 m sequence in deeper sections. The presence of gypsum crystals within the laminated sediments suggests a high concentration of Ca in the inflowing water. At Parihara Lake the organic carbon-rich sediments at 95 cm depth was dated to 7,375 + 155/−150 year BP. At Tal Chapar radiocarbon dates of 7,190 + 155/−150 and 9,903 + 360/−350 was obtained from the sediments rich in organic carbon occurring at a depth of 1.35 m and 1.80 m, respectively. The study reveals strong hydrologic oscillations during the past ∼14,000 year BP (13,090 + 310/−300 year BP). Quaternary geomorphic processes, especially the strong aeolian processes during dry climatic phases, played a major role in the formation of the lake basins, as well as the fringing linear dunes. Geochemical and mineralogical analyses of the lacustrine sediments, supported by radiocarbon dates indicate the existence of an ephemeral lake earlier than ∼13,000 year BP as sediments began to be deposited in a lacustrine environment implying sustained runoff in the catchments. A freshwater lake formed between 9,000 year and 7,000 year BP. The lake dried periodically and this strong fluctuating regime continued until about ∼7,000 year BP. Mid-Holocene was wet and this was possibly due to higher winter rains A saline lake existed between 6,000 year and 1,300 year BP and finally present day semi arid conditions set in since 1,200 year BP. Remnants of a habitation site (hearth and charred bones) on stabilised dune at Devani near Tal Chapar were dated to 240 ± 120 year, while that at Gopalpura was dated to 335 ± 90 year. These historical sites on stabilised dunes were, according to the local accounts, settlements of people who used the lake brine for manufacturing salt.  相似文献   

Location-based services: technical and business issues   总被引：13，自引：0，他引：13  

Diep Dao  Chris Rizos  Jinling Wang 《GPS Solutions》2002,6(3):169-178

Geographical Information System (GIS) and Global Positioning System (GPS) technologies are expanding their traditional applications to embrace a stream of consumer-focused, location-based applications. Through an integration with handheld devices capable of wireless communication and mobile computing, a wide range of what may be generically referred to as 'Location-Based Services' (LBS) may be offered to mobile users. A location-based service is able to provide targeted spatial information to mobile workers and consumers. These include utility location information, personal or asset tracking, concierge and route-guidance information, to name just a few of the possible LBS. The technologies and applications of LBS will play an ever increasingly important role in the modern, mobile, always-connected society. This paper endeavours to provide some background to the technology underlying location-based services, and to discuss some issues related to developing and launching LBS. These include whether wireless mobile technologies are ready to support LBS, which mobile positioning technologies can be used and what are their shortcomings, and how GIS developers manipulate spatial information to generate appropriate map images on mobile devices (such as cell phones and PDAs). In addition, the authors discuss such issues as interoperability, privacy protection and the market demand for LBS. Electronic Publication  相似文献   

PERFORMANCE ANALYSIS OF INTEGRATED GPS/GLONASS CARRIER PHASE-BASED POSITIONING   总被引：2，自引：0，他引：2  

DAI LiwenHAN ShaoweiChris Rizos 《地球空间信息科学学报》2001,4(4):9-18

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DNAPL Removal from a Heterogeneous Alluvial Aquifer by Surfactant- Enhanced Aquifer Remediation     

John T. Londergan  Hans W. Meinardus  Paul E. Manner  Richard E. Jackson  Chris L. Brown  Varadarajan Dwarakanath  Gary A. Pope  Jon S. Ginn  Sam Taffinder 《Ground Water Monitoring & Remediation》2001,21(3):71-81

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