Differential effects of salinity changes on two estuarine fishes,Leiostomus xanthurus andMicropogonias undulatus     

Mary L. Moser  Lawrence R. Gerry 《Estuaries and Coasts》1989,12(1):35-41

Salinity fluctuation has been proposed as an important determinant of estuarine fish distribution. To test this idea, we compared distribution, behavioral preference and physiological sensitivity of two juvenile estuarine fishes, spot (Leiostomus xanthurus) and croaker (Micropogonias undulatus), with respect to salinity change. In field collections, spot: croaker ratios were positively correlated with salinity variation. Subsequent behavioral observations revealed that croaker tend to cross a 10‰ salinity gradient less often than spot. We proposed that energetic costs of salinity adaptation may be higher for croaker, resulting in the observed avoidance behavior. Oxygen consumption rates over rapid salinity fluctuations showed no significant differences in metabolic response between species, although there was some indication that sensitivity changes with fish size. Apparently, juvenile spot and croaker are well-equipped to withstand extreme changes in salinity. We conclude that environmental factors correlated with salinity change may be responsible for distribution differences between these two abundant species.  相似文献   

The Sensitivity of Four Monitoring Well Sampling Systems to Low Concentrations of Three Volatile Organics     

Ronald Schalla  David A. Myers  Mary Ann Simmons  John M. Thomas  Antony P. Toste 《Ground Water Monitoring & Remediation》1988,8(3):90-96

Four state-of-the-art ground water sampling systems were analyzed to determine their reliability in providing representative samples of the volatile chlorinated hydrocarbons trichloroethylene (TCE), perchloroethylene (PCE), and 1,1,1-trichloroethane (TCA) from a simulated monitoring well. The sampling systems studied represent four commonly used devices, including a stainless steel and Teflon® piston pump, a Teflon bailer, a Teflon bladder pump, and a PVC air-lift pump.
Controlled laboratory sampling experiments were conducted in a tank and well test chamber designed to approximate field conditions. A well purging and sampling procedure was used in the test apparatus to determine the accuracy and precision of each device for detecting low concentrations of the compounds in ground water. The compounds selected are some of the most ubiquitous hazardous contaminants found in shallow aquifers near hazardous waste sites throughout the United States.
No significant statistical difference was found among the four sampling systems in detecting the compounds.  相似文献   

Book reviews     

James R. Carr 《Mathematical Geosciences》1995,27(5):703-707

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The case for planetary sample return missions. 2. History of Mars     

Gooding JL  Carr MH  McKay CP 《Eos》1989,70(31):745, 54-745, 55

Principal science goals for exploration of Mars are to establish the chemical, isotopic, and physical state of Martian material, the nature of major surface-forming processes and their time scales, and the past and present biological potential of the planet. Many of those goals can only be met by detailed analyses of atmospheric gases and carefully selected samples of fresh rocks, weathered rocks, soils, sediments, and ices. The high-fidelity mineral separations, complex chemical treatments, and ultrasensitive instrument systems required for key measurements, as well as the need to adapt analytical strategies to unanticipated results, point to Earth-based laboratory analyses on returned Martian samples as the best means for meeting the stated objectives.  相似文献   

Hydrodynamics and sedimentation in wave-dominated coastal environments,B. Greenwood and R. A. Davis,jr. (eds), developments in sedimentology, 39, Elsevier,Amsterdam, 1984. No. of Pages: 473     

Alan Carr 《地球表面变化过程与地形》1986,11(3):345-346

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The autecology and production dynamics of eelgrass (Zostera marina L.) in Netarts Bay,Oregon     

Mary E. Kentula  C. David McIntire 《Estuaries and Coasts》1986,9(3):188-199

Changes in biomass, growth form and shoot net primary production in an eelgrass, Zostera marina L., bed were monitored along transects at three tidal heights in Netarts Bay, Oregon, from May 1979 through June 1981. During the growing season, April through October, the mean plastochrone interval was 16.5 d along the low intertidal transect and 11.6 d along the high intertidal transect. The mean export interval was 13.3 d along the low intertidal transect and 11.6 d along the high intertidal transect. The life span of a leaf averaged 48 d along the low intertidal transect and 36 d along the high intertidal transect. Shoot density was positively correlated with mean leaf area index (LAI) until the LAI reached 3.8 to 5.5, above which LAI was negatively correlated with density. The maximum Zostera biomass ranged from 143 (high intertidal transect) to 463 (low intertidal transect) g dry wt m^?2. Maximum values of shoot net production ranged from 4.7 (high intertidal transect) to 13.6 (low intertidal transect) g dry wt m^?2d^?1. Zostera shoot net production was related to light and to the physical damage to the shoots associated with a rapid accumulation of Enteromorpha biomass in the bay. In addition, patterns of biomass accumulation were related to the duration of water coverage, as determined by both tidal height and local impoundments of water. At all transects, biomass sloughed was equal to at least 50% of the shoot net primary production in that area during that time period; sloughed leaves accounted for 25 to 97% of these losses. An estimate of the total annual net primary production of aboveground Zostera in the bed was 17,500 kg, dry wt (SE=3,080 kg dry wt), which was equivalent to a mean annual rate of 383 g C m^?2 (SE=67 g C m^?2)  相似文献   

Nests of intermediate depth (70–160 km) earthquakes adjacent to active volcanoes during 1963–1982     

Michael J. Carr 《Journal of Volcanology and Geothermal Research》1983,19(3-4)

Uniform maps of circumpacific convergence zones constructed by the same projection and scale reveal three main associations between intermediate depth seismicity and contemporaneous volcanic activity. First, in areas of high seismicity there are usually few active volcanoes. Second, in areas of low to moderate seismicity aseismic domains can often be recognized beneath the active volcanoes. Third, adjacent to the aseismic domains there are nests of seismicity located a few 10's of km away from the active volcanoes usually in the direction of the trench. More than 40 such nests are identified in the circumpacific and Indonesian arcs. These three associations may be related to melting near the upper surface of the underthrust slab. A fluid phase, either silicate melt or a hydrous fluid released by dehydration of the slab, would lower the strength of the slab and create aseismic zones beneath the active volcanoes. Nests of earthquakes can develop by stress concentration at the margins of the weak zones. Areas not volcanically active have little or no fluid phase and a higher level of seismicity.  相似文献   

A new technique for determining the surface level of salt marshes and other uncompacted sedimentary environments     

Alan P. Carr 《地球表面变化过程与地形》1983,8(3):293-296

The method described involves the use of an electro-optical distance measurer mounted on a theodolite. Observations are taken onto a series of acrylic reflectors, aligned at right angles to the line of sight, and slope distances and vertical and horizontal angles are recorded. From these data it is possible to obtain surface heights to an accuracy of ±0·5 cm at 200 m and to avoid any direct disturbance of the site under investigation.  相似文献   

Marine risk assessment: linear alkylbenzenesulponates (LAS) in the North Sea     

Temara A  Carr G  Webb S  Versteeg D  Feijtel T 《Marine pollution bulletin》2001,42(8):635-642

The fate of linear alkylbenzenesulponates (LAS) in estuaries and coastal areas of the North Sea has been characterized with simple environmental models. The predicted concentration range in the estuaries around the North Sea (0.9-9 microg LAS l(-1)) was validated by monitoring data (1-9 microg LAS l(-1)). In offshore sites of the North Sea, it is estimated--and experimentally verified for a few sites--that the LAS concentration is below analytical detection limit (i.e., 0.5 microg LAS l(-1)). The effects of LAS on marine organisms have been reviewed. For short-term acute tests, there was no significant difference (p = 0.83) between the mean LC50 values of freshwater and marine organisms (mainly pelagic species tested, 4.1 and 4.3 mg LAS l(-1), respectively). For longer-term chronic tests, it appeared that the sensitivity (mean no-observed effect concentration (NOEC) value) of marine and freshwater organisms (0.3 and 2.3 mg LAS l(-1), respectively) was significantly different pt-test = 0.007). The predicted no-effect-concentrations (PNEC) were 360 and 31 microg LAS l(-1), for freshwater and marine pelagic communities, respectively. Given that the maximum expected estuarine and marine concentrations are 3 to > 30 times lower than the PNEC, the risk of LAS to pelagic organisms in these environments is judged to be low.  相似文献   

Sustainable Water Management Solutions for Large Cities - Edited by Dragan A Savic, Juan Carlos Bertoni, Miguel A Mariño and Hubert H G Savenije     

Mary  Dengler 《The Geographical journal》2007,173(2):192-193

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