فصلنامه اقیانوس شناسی
پیاپی 4 (زمستان 1389)

babak1409@yahoo.com Study Type: Research | Subject: Special Article abstract: The shallow parts of the coastal zone are usually affected by strong flow parallel to the coast lines. Thus, the bed morphology of these areas is subjected to permanent changes and engineering treatment is essential for controlling bed erosion and sedimentation. In this work, laboratory experiments are performed to investigate the effects of spur dikes end shape (which are located perpendicular to the shore line in shallow continental shelves) on formation of flow pattern and scouring due to strong parallel shore currents. To achieve this goal, the effects of single spur dike which covers about thirteen present of the continental shelf are studied. The three spur dike end shapes of rectangular, trapezoidal and semicircular are studied in present work. The measurements on velocity patterns and morphology changes of a sandy bed around the spur dike in a laboratory model are utilized to get general idea of spur dike end shape effects.

Macrobenthic assemblages of the Anzali lagoon were studied in order to investigate their population density, distribution and abundance. Anzali lagoon with an area of 200 km² is situated in the south-west of the Caspian Sea. Samples were obtained in 4 stations seasonally and taken with a 250 Cm² Van Veen grab in Anzali lagoon from spring 2006 to winter 2006 with 3 replicates. Environmental factors such as temperature, grain size, T.O.M, salinity, pH and dissolved oxygen were also studied. 36 taxa were identified to species or lowest taxonomic level. The most abundant recorded species were Chironomus, Scirtes tibiolis, Ambrysus mormon of insecta, and Tubifex of Oligochaeta, which present in samples through the study area. However Valvata cristata of Gastropoda was observed only in summer. According to the results, the Shannon-wiener index fluctuated between lowest up to 2.64. Abundance and diversity of macroinvertebrates were maximum in spring and autumn. In spring it can be related to spawning and recruitment of the macrobenthos in Siah Keshim Wetland. In autumn however, greater amount of invertebrates in the environment can be as a result of reduction in water temperature which diminishes the feeding rate of predatory fishes. Summer and winter benthic invertebrates of Siah Kashim were lower in number and diversity. Most fishes of Anzali Lagoon are benthic feeders, so in summer when water temperature rises, they become more active in feeding macrobenthos. As a result their frequency and diversity reduces in summer. Winter in Siah Kashim coincides with death of many macrophytes, which provide space for aggregation of insect larvae as benthic animals. This may cause a reduction in benthos of Siah Kashim in winter.

The Khorramshahr soap factory is the biggest and most advanced Iranian soap and glycerine factory with daily producing 100 tons soap-chips and 14 tons glycerine. The produced sewage of this factory is directly drained into the Karoon River through a channel. In this study, samples were collected from 4 stations including: 50 meter above, 50 and 500 meter lower and the sewage evacuation area during 10 months starting from October 2006 to July 2007 using Van Dorn sampler. The comparison of physic-chemical parameters of water and sewage with the standard values defined by Department of Environment, showed that the amount of COD, BOD and Chlorine (means 1300, 169.8 and 4042.9 ppm, respectively) in sewage is higher than the standard level. Based on water quality index, stations 1, 2, 3 and factory sewage with annual quality index of 54.63, 40.29, 45.71 and 24.32 were classified as moderate, bad and very bad, respectively. There was significant difference (p<0.05) in factors such as BOD, COD, nitrate, phosphate and bicarbonate among the stations during the sampling period. The results also revealed factory sewage has affected the river water quality in spite of high water volume and sewage exit flow. These changes in the quality of river water indicate increase of many parameters in second station and decrease in third station which shows Karoon River high ability of self purification.

Agar extraction for Gracilaria corticata by investigating the effects of various extraction variables such as soaking time, soaking temperature, seaweed to water ratio, extraction temperatures and extraction time and also Alkali treatment method. The results showed that agar yield was significantly affected by all the tested variables. The agar yield was maximized when extraction process was carried out with 1 h soaking time at 40° C with seaweed to water ratio of 1:100 and extracted for 1.5 h at 90° C. the result of alkali treatment showed that alkali treatments at 5% is the best concentration and 80 °C is the best alkali temperature for agar extracting. Also some of chemical and physical properties of agar such as gel strength and sulfate content were determinate. The result showed negative correlation between gel strength and sulfate content of Agar.

This research will discuss an assessment of the Economic value of Kish Island's coral reefs regarding their recreational usage, and estimate a visitor’s willingness to pay (WTP) for recreational benefits obtained, based on contingent valuation (CV) and dichotomous choice (DC). For determination of visitor’s willingness to pay semi-nonparametric distribution-free (SNPDF) model was employed. The visitors contain scuba diving and glass ship for visiting coral reefs. Results indicate that 73% of visitors in scuba diving and 52% of visitors in glass sheep are willing to pay for recreational values of Kish Island's coral reefs. The mean value for willingness to pay for the recreational annual value of the coral reefs is 45460 Rls/ha and 1684 Rls/ha per visit for scuba diving and glass sheep respectively. The total recreational annual value was estimated at 144,840 US$/ha for the Kish Island. This provides enough justification for policy makers to maintain the quality of coral reefs habitat, and along with that to avoid the degradation of marine resources.

Surface discharge of dens jet as a common way for disposal of produced waste water in coastal areas is strongly influenced by the hydraulical and physical fissures of discharge stream and ambient water. In the current study, considering different mechanisms of flow in surface discharge of negative buoyant jets, dominated regimes are studied. Using Length Scale (L.S.) method and utilizing an experimental set up which are merely designed for this studies, different flow regimes were experimentally simulated and its behavior were investigated. As a result of this study, the observed criteria for free jet regime, shoreline attached jet regime and intruding upstream plume in the case of surface discharge of dens jets were précised and their ranges of diversity in the form of dimensionless diagram were developed. The axis’s of this diagram are a couple of dimensionless parameters that formed by the flow variables where each shows classification criteria in the boundaries of diagram. Finally, extracted criteria as a separator of these regimes were used to develop a tree-like classification scheme in surface discharge of dens jets. In this method, through identifying the range of flow variables in occurrences of each regime and sub regimes, coming prediction of flow characteristics by empirical equations will easily be possible.

Surface discharge of dens jet as a common way for disposal of produced waste water in coastal areas is strongly influenced by the hydraulical and physical fissures of discharge stream and ambient water. In the current study, considering different mechanisms of flow in surface discharge of negative buoyant jets, dominated regimes are studied. Using Length Scale (L.S.) method and utilizing an experimental set up which are merely designed for this studies, different flow regimes were experimentally simulated and its behavior were investigated. As a result of this study, the observed criteria for free jet regime, shoreline attached jet regime and intruding upstream plume in the case of surface discharge of dens jets were précised and their ranges of diversity in the form of dimensionless diagram were developed. The axis’s of this diagram are a couple of dimensionless parameters that formed by the flow variables where each shows classification criteria in the boundaries of diagram. Finally, extracted criteria as a separator of these regimes were used to develop a tree-like classification scheme in surface discharge of dens jets. In this method, through identifying the range of flow variables in occurrences of each regime and sub regimes, coming prediction of flow characteristics by empirical equations will easily be possible.