学术文献库

The results of mentioned physicochemical and biological analysis show that in more polluted sampling points, the number of resistance benthos (Bivalves) are more than other points of the study area. Heavy metal concentration in sediment is between 10 to 1000 times more than water samples especially for Arsenic, Mercury, and Vanadium. Dissolved Oxygen is acceptable all over the study area (more than 4 mg/L) based on environmental quality standards for dissolved oxygen which present the range of 2-9 mg/l for sensitive aquatic lives to less sensitive ones. However the presence of chemicals causes increase in the value of Chemical Oxygen Demand (around 500 to 1000 mg/L) and consequent decrease in water purification ability Nutrient uptake capacity which shown as the ratio of Nitrogen to phosphorus is appropriate (around 6) in parts of Musa estuary with more than 3 meters depth . The study area is a semi-closed tide-dominant water body with shallow depth, in comparison to the oceans. A 2-D modelling is applied to simulate current speed and direction. The results of this modelling shows except in the creeks, we have relatively suitable circulation of water in the estuary and current speed may exceed 0.8 m/s. It means Musa estuary is not a dead zone and in some parts which have enough water circulation and nutrient uptake for aquatic life, but huge amount of heavy metal (especially Mercury) in the sediment and water samples, indicates that all aquatic bodies overwhelmed by dangerous heavy metals.