Showing papers on "Water column published in 1970"

Biological Productivity in the Dead Sea Part I. Microorganisms in the Water Column

Abstract: Studies were performed to determine the distribution of microbiota in the Dead Sea during 1963 to 1965. The dominant organisms in the surface water were found to be two red halophilic bacteria, followed in abundance by a green flagellated alga, Dunaliella virdis. Cultures inoculated with Dead Sea water produced growth of the red bacteria as well as unidentified non-pigmented halo-tolerant bacteria, capable of growing in 25% salt solution, and bacteria that grew only in dilute salt media. The latter are mainly spore-forming aerobes, probably introduced by rain-wash of the soil, as well as from the Jordan River and fresh water springs. Sulfate reducing bacteria were also cultured from the water and from the sediment. Pigment studies on extracts from laboratory cultures of the red bacteria, from centrifuged suspensions of Dead Sea water and, by comparison, from a pure culture of Halobacterium salinarium, showed that the dominant pigment in all cases was the carotene α-bacteriorubrin. The total number of organisms decreased with depth of the water column, especially below the thermocline. The interpretations given for the decrease are: lack of dissolved oxygen, decrease in incident light, and lack of dissolved phosphate. The last factor is probably due to rapid precipitation of phosphate by divalent ions.

On the seasonal distribution of temperature and salinity in rhode island sound1

Abstract: The temperature and salinity of Rhode Island Sound were measured between July 1963 and July 1964. A seasonal thermocline developed at middepth in spring and intensified through August. Early fall cooling and wind mixing rapidly destroyed the thermocline, rendering the water column practically isothermal by late October. The salinity patterns are more complex than those of temperature and are strongly influenced by seasonal variations in coastal runoff. Brackish water outflow from Narragansett Bay was traced as a salinity wedge as far as 20–30 km from the coast. The seasonal variation in thermal energy of the sound is estimated to be at least four orders of magnitude greater than the potential energy changes.

On the unusual patterns of phosphate vertical distribution in the tamar estuary

Abstract: In two previous papers on the distribution of some nutrients and phytoplankters in the Tamar estuary, anomalies in the vertical profile of phosphate concentration have been demonstrated (Mommaerts, 1969a, b). In the top three metres the water column was stratified so that a dip of no more than 50 cm revealed a PO43- (calculated as phosphorus) variation that would normally be accompanied by a marked change in salinity. On the other hand, salinity determinations revealed no dilution at all. Such unexpected variations occurred two or three times in the layer studied. There was an excellent correlation between the PO43- and NO3- (calculated as nitrogen) concentrations on the one hand and between the silicate concentration and salinity on the other hand. Such a phenomenon could indicate either pollution or biological activity distributed along specific layers. The idea of pollution seemed to be most likely but, to fit the observations, the pollutant would have to match the salinity of the estuary at the precise spot where it enters.

Length-weight relationships, age composition, growth, and condition factors of carp in lake carl blackwell

Abstract: Carp (Cyprinus carpio Linnaeus) are ubiquitous in the lower mainstream of most major U.S. rivers and occur in all large mainstream impoundments in Oklahoma ( 1-4). Carp generally comprise a sizeable percentage of the standing crop of fishes in Oklahoma reservoirs. Additional know­ ledge of the biology of carp is needed to assess their role in the function of these ecosystems. The objective of this report is to describe aspects of growth and condition of carp in Lake Carl Blaclcwell. This report presents length.weight relationships, age composition, and condi­ tion factors for c:np in Lalce Carl Blackwell, Oklahoma. The study is based upon examinations of a total of 619 carp collected, chiefly by electrofishing, in 12 monthly samples from December, 1967 through November, 1968. ual sloping contours forming many shallow Lake Carl Blackwell is a turbid, shallow mud flats, while the south shore has numer­ reservoir located in north-eentral Oklahoma, ous rocky outcroppings and fewer mud flats. approximately 9 miles west of Stillwater on The basin of the lake is quite level except State Highway SIC. The dam is situated in the former channel of Stillwater Creek in Section 3, Township 19 N, Range 1 wand its tributaries. in Payne County. The majority of the lake The low, unprotected landscape of the lies within Payne County but a small finger watershed surrounding the lake and the extends northward into Noble County. The relatively shallow water depth permit the reservoir was formed in 1937 by damming winds to promote vertical circulation. The Stillwater Creek, thus providing a water intensity of the circulation varies with dens­ supply and a recreational area for the City ity differences in the water column and of Stillwater. The reservoir first reached variations in direction and intensity of the spillway level in 1945. The maximum sur- wind. The water mass stratifies for short in­ face area at spillway level is 1,486 hectares, tervals in June, July and August, when high the volume 79.9 million rna (5). ambient temperature and diminished winds Due to below average rainfall from 1961 allow this. The wind-driven circulation, through 1967, the water level of the lake which is so prevalent, causes high turbidity, receded approximately 4 meters below the uniform vertical temperatures, and uniform spillway level at which time the surface dissolved oxygen levels (5). area was 856 hectares and the volume was The majority of fish in this study were 33.9 million rna. Growth of young-{)f.the· collected by electrofishing in the shallow, year channel catfish showed a progressive wind-protected arms that lie to the north or decline between 1962 and 1968, when rain- south of the main east-west axis of the lake.

Forecasting The Trophic Status Of ToloHarbour, Hong Kong

Abstract: It is feasible to develop, verify and calibrate a two-layer tidally averaged model which can represent the stratification in the vertical water column during the summer season and can provide reliable estimation of the pollutant concentration in the Tolo Harbour. Eleven systems of water quality parameters are modelled, including three organic parameters, six inorganic systems and two biological parameters. The mathematical model can predict the tidally-averaged results in each layer during the summer season when the coastal waters are stratified. In addition, extensive field and laboratory experiments are required to be carried out in order to determine suitable values for the relevant model parameters. These include the phytoplankton growth kinetics due to temperature, solar radiation and nutrient effects; phytoplankton death kinetics due to endogenous respiration and zooplankton grazing; sediment interactions and eutrophication; phytoplankton settling rate; phytoplankton and dissolved oxygen relationship. Some of the rate coefficients can then be obtained by tuning the parameters with the field data. A sensitivity analysis is then entailed to investigate the relative importance of the pollutant sources and other model parameters on the water quality of the coastal waters. The model can finally be used to forecast the trophic status of the Tolo Harbour, a valuable practical application.