Samples taken from sediment in semi-closed bay in Eastern Mediterranean: BOD values at 150 mg/l and COD at 500 mg/l
However, no traceable amounts of TPH and FOG have been detected.
Several sewage plants and rivers discharge in the marine waters of the bay. Also, very close (100 m) to the sampling point, there is a commercial port.
Keywords: environmental engineering, marine pollution
Marine organisms, flora and fauna (both dead or alive) as well as organic settleable solids from incoming streams can contribute to BOD in marine sediments.
Dumping of municipal and industrial wastes in coastal sea areas may be ones.
I think that the main causes of the abundance of BOD5 and COD in marine ediments are mainly due to the decomposition of algae that contain a lot of organic matter (BOD5) and fish composed mainly of mineral salts. phosphates whose origin is marine and which is used for the fertilization of agricultural land is an example.
I hope that my proposal will be useful.
cordially
This is because of the collective parameters of both natural and human factors. As increase in temperature of marine water will lead to decrease in the oxygen level, which may lead to death of sensitive fishes, which may leads to bloom in bacterial colony. Along with the runoff from the nearby areas from dumping sites or from the nearby agricultural fields.
It is difficult to predict precisely as there could be many reasons, however primarily it shows remains of marine organisms in the sediments. This gives rise to biochemical oxygen demand.
If this is a closed bay and several sewage plants and river discharge is there, there could be presence of complex chemical compounds undergoing biological decomposition.
I agree with all the above. Also, I don't consider the values stated for BOD and COD to be high. The natural environment is not pure.
Anthroposenic contaimination is the main culprit. A little contribution by nature may not be rulledout.
Virendra,
Given the small amount of information provided in the question, I would be interested in knowing how you arrived at that conclusion. It sounds like you are just instantly blaming people no matter the situation. Nature can be a major contributor of contamination in many circumstances. Of course so can people.
David, appreciated your valuable remark. Biochemical oxygen demand and chemical oxygen demand in marine sediments is a complex phenamenan. answer may need detailed systematic scientific study.
Virendra, I agree with your follow-up comment. I agree that humans provide plenty of environmental pollution. However many, such as water and wastewater utilities do a lot to reduce environmental pollution caused by humans. They are often given a bad rap by the very people that send their waste to the treatment plant. 150 mg/l BOD and 500 mg/l COD are lower concentrations than most domestic wastewater and industrial wastewater, respectively. As you said, however, detailed study may be required to determine the cause of these levels in marine sediment.
I was part of e research project regarding algae blooms on a near shore reef. A municipal wastewater facility with Ocean Outfall disposal was located approximately 4 miles from the reef. A MOU was entered into between NOAA and the local water agency to test the outfall plume. Short answer, it was determined the effluent impacts of the outfall plume dissipated very shortly after the mixing zone. The reef had a near by navigable inlet -waterway that was tested. The incoming tide tested very low for any parameters that would trigger a bloom including items such as BOD-CBOD, nutrients, microorganisms, etc. All of the incoming tide samples were roughly the same. When testing the outgoing tides the water showed significant spike levels of almost all the parameters tested for. It was determined the outgoing tide was influenced by 1) Lagoon and Intercostal Waterway collecting runoff from storm control canals out west. 2) Local wastewater collection systems were compromised during high tides. The older lines would get partially submerged or the areas around where leaks had occurred found their way into the body of water and out the inlet. The tides also had an effect on local coastal communities that were on septic systems. 4) The last culprit identified was ocean upwelling events. NOAA had monitoring equipment placed onto and above the reef that was able to correlate wind and tidal events to the surge of silt and nutrients onto the reef. Sorry so long, we just found a lot of potential culprits. In the end we believe they all play a roll, the question is to what degree.