JOURNAL OF THE PERSIAN GULF (MARINE SCIENCE)
Year:2010 | Volume:1 | Issue:1|Papers Count:6

Parts of oil spills reach Iranian coastline along the Persian Gulf in the form of tar balls and scattered oil patches. There are many published reports regarding oil spills reaching northern coasts of the Persian Gulf, but none report on the content of heavy metals associated with petroleum in sediments and plants of contaminated areas. This research was conducted to determine and map petroleum- related heavy metals (Ni, V and S) distribution in sediments and weathered tar balls and bitumen using XRF analysis. It is determined there was contamination of heavy metals associated with petroleum, for example, Ni, V, and S in sediments of northern coasts of the Persian Gulf in Bushehr and Nayband Bay Area.

Collecting information on suspended sediments concentration (SSC) in coastal waters and estuaries is vital for proper management of coastal environments. Traditionally, SSC used to be measured by time consuming and costly point measurements. This method allows the accurate measurement of SSC only for a point in space and time. Remote sensing from air-borne and space-borne sensors have proved to be a useful method for such studies as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. The reason for success of remote sensing in such surveys is the strong positive relationship that exists between SSC and remotely sensed spectral radiance. This spectral radiance could be in the sun reflected and/or scattered or thermal terrestrial wavelength band. To find an algorithm relating SSC to spectral radiance over Bahmansheer River estuary at the North-West of Persian Gulf, a three-month field measurement (April to June 2003) was conducted while we had MODIS sensor on board of Terra over-passed the scene simultaneously. Ninety samples in fifteen trips were collected. Also the environmental parameters such as atmospheric visibility, air and water temperature, current direction and speed at the sampling point, wind speed and humidity were measured simultaneously. A close correlation between tide and SSC was observed. It is found that in the flood, the width of the turbid area at the estuary decreases while in the ebb, the suspended sediment distribution extends to the deeper region. Change detection by comparison between a base image of high tide/low tide conditions and any image could be used as a tool for detection of tidal conditions. This would be a powerful tool for monitoring erosion at the coastal area and estuaries.

The depth average module of NASIR finite volume solver was applied to study the tide induced currents in Khowr-e-Musa estuary. The model computes water level variation and velocity components in horizontal plane solving depth average continuity and momentum equations considering the hydrostatic pressure distribution. The software takes into account the bed and wall geometric complexities and resistances. In the present work, the option of cell vertex finite volume method of the software was applied for discretizing the governing equations. The descritized equations were solved on a triangular unstructured mesh. The solution domain was descretized using Delauni triangulation method. For damping out numerical oscillations of explicit solution procedure, an artificial viscosity formulation suitable for the triangular unstructured meshes was applied. After verification of the accuracy of the software with analytical solution of tidal currents in a dead end channel, the efficiency of the results was assessed by simulating flow on Khowr-e-Musa multi-branch estuary.

CTD (conductivity, temperature and depth) data collected in the coastal waters of Rudsar in summer 2008 were analyzed to identify the isothermal layers, thermocline depth and vertical structure of seawater properties. During the survey, probe was released into the seawater column down to 117 m depth. Results showed a vertical variation of temperature between 29oC at the sea surface and less than 8oC at 117 m depth. In the southern coastal waters of the Caspian Sea, stratification process of seawater is completed in mid summer. In time of measurements, a strong thermocline was present between 10 m and 40 m depths with 18oC temperature decrease across it. Below thermocline, the temperature gradually decreased and reached less than 8oC at 117 m depth. Vertical and horizontal distributions of salinity were mainly between 12.18 psu and 13.1 psu. Density variations were in agreement with the temperature changes and the variations of density in the study area were between 1005.8 kg/m3 in the sea surface and 1010.4 kg/m3 near the bottom.

The percentage cover and distribution of scleractinian corals were studied at two Iranian islands in the Persian Gulf. Survey techniques involved the use of 20-m line transects placed at 4-9 m depth interval, parallel to the shore. GIS based maps were employed to show the distribution of hard corals. In Farurgan Island, hard coral cover was concentrated in the west and north-west of the island, while in Hengam it was mostly concentrated in the eastern side of the Island. Mean hard coral cover was 25.91% (±5.80) and 48.47% (±1.36) in Farurgan and Hengam Islands, respectively. There was a significant difference (p<0.01) in hard corals coverage among different reefs in each island. Other benthic life forms showed similar patterns with significant differences (p<0.01) among reefs. It was observed that the predominant hard coral forms were massive (Porites) in Farurgan Island, whilst those in Hengam Island were mainly branching corals (Acropora).

Biodiversity and community structure of macro fauna of the intertidal sandy beach at Chabahar Bay were studied for a period of ten months in 2007. A total of 32 species were observed and identified in this study so that polychaete with 16 species was numerically dominant. The results showed changing densities were influenced by monsoon season so that maximum density (1935.47 ind/m2) was observed at pre-monsoon while minimum (181 ind/m2) was obtained at monsoon. The highest and lowest value of diversity and richness indices were obtained at pre-monsoon and during monsoon, respectively. Also, multivariate analysis separated monsoon season from pre and post monsoon clearly. Our results show that monsoon can be the most important factor on biodiversity and community structure of macro fauna at Chabahar Bay and intertidal of this bay have not favorable environment for macro fauna development.