Such high COD value is likely from anthropogenic sources such as percolation from landfill leachates and/ or industrial effluents. Given the depth, the permeability of the geological strata may also help in provenance identification. Sandy lithologies are known to be highly permeable. Aquifers overlain by such media are susceptible to despoliation through percolation.
Dear Supriya,
What is your method?
Please check the interferes too, like Cl-.
As Mr. Idehai mentioned you need to undertake a survey of catchment area wrt anthropogenic sources and geological formation of the area under consideration. Once it is done, subsequently check for interference in analysis wrt Cl-, Fe++, S-- and other elements in reduced forms which could be oxidized.
definitely contamination is there.check within 10kms whether any industry is there or not.natural soil structure may enhance it ,but not at that level
Many good comments have been made above. I would also suggest that a BOD measurement be made using seed bacteria from soil in that area if possible (Standard Method 5210). The ratio of BOD to COD can give information on that fraction of COD which is biodegradable. Additionally, measurement of total organic carbon (Standard Method 5310) and UV absorption at 254 nm (Standard Method 5910) would be useful. A high value of UV absorption would indicate a likely higher amount of aromatic carbon relative to the amount of TOC.
Lastly, if fuel contamination is suspected, then extraction with hexane and analysis by GC-FID will give a characteristic "finger print" of a particular fuel by the series of peaks it contains (see Hydrocarbon Oil Index - ISO 9377-2) potentially allowing identification of type and possibly source of fuel. http://www.iso.org/iso/catalogue_detail.htm?csnumber=27604
There must be nearby a sugar or milk product or any other industry ,which may be the main cause of high BOD / COD.In ground water. COD values found 258 mg/l in the depth of 300 ft. may be due to effluents and the permeability of the geological strata specially Sandy soils/ Alluvial are known to be highly permeable.
Better points has been made above. He has to ascertain the point sources of the anthropogenic emissions if possible and then relating it with the geology of the area, trying to get the water type for the various samples to be able to explain the trend of the high COD values. Thanks
Better points has been made above. He has to ascertain the point sources of the anthropogenic emissions if possible and then relating it with the geology of the area, trying to get the water type for the various samples to be able to explain the trend of the high COD values.The water type must be identified.
Thanks
To respond the Question,plz describe the demographic details of the study area. To counter check the results, U can also measure dissolved oxygen. Some times geochemical reactions produces higher content of CO2, which produce carbonic acid and pH reduced to less than 7(acidic character). This acidity responsible for solubilisation of organic & carbonaceous solids associated with rocks/stones.
Shamsh saheb , your ans may be correct but in all the biochemical reactions which occur in subsurface in the presence of any organic matter will produce CO2 if there will be a pinch of Oxygen ; also it is a well known fact that in ground water Dissolved Oxygen will not be present. In ground water, water is present in an anaerobic condition.
Shamsh saheb , your ans may be correct but in all the biochemical reactions which occur in subsurface in the presence of any organic matter will produce CO2 if there will be a pinch of Oxygen ; also it is a well known fact that in ground water Dissolved Oxygen will not be present. In ground water, water is present in an anaerobic condition.
thanxs
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