At present I am pursuing my phd, the area under study was found to have manganese ores. I analyzed the samples of ground water and surface water (river water) for heavy metals such as Ti Mn,Ba and more. It was found that all the metals below detection limits. I wish to know to what extent the results are relaible.
The heavy metals you list have nothing to do with the occurrence of manganese ores, right? So why do you expect the heavy metals at all? Is it because there is anthropogenic pollution? The manganese ores probably result from the rock/matrix/sediment which influences the water chemical conditions. I am not a geologist, but I have the impression that there are few rock formations which naturally result in elevated heavy metal concentration in either groundwater or stream water. So, in short, much more information is needed in order to answer your question - certainly, there is no reason to assume that you find heavy metals in EVERY sample you take SOMEwhere. It will of course also depend on the analysis method and their detection limits.
i think it's possible that the heavy metals take away from that ore because it's brought by river stream, or maybe the heavy metals settles at the bottom of the rivers, heavy metal have heavier atomic mass than water so it's possible would find on the bottom of the river,, just my opinion :D
Susanne, heavy metals occur normally in the crust, just in most places they occur in the trace amounts, but their presence is normal. Titanium is present up to 0.61% in crust in a mineral form. Manganese - 950 - 100 ppm, up to 9000 ppm in the soil and it is also present in salt water and atmosphere. Bismuth is present in the numbers that double Gold. The anthropogenic pollution increases the content of toxic substances, but they occur in the environment normally as well.
Pavan, some toxic metals in aquatic environment either sediment or like f.ex. mercury gather in aquatic organisms binding there into different forms. Did you try to check the sediments or any water organisms?
Susanne, heavy metal can be observed in the ground water samples, may be due to contaminants of the ore or the local effect, mostly high iron are associated with Mn
@Joanna and @ Sudhir, I know of course that heavy metals may be a constituent of a number of geological formations, but my question was about detectability - as long as we don't know more about the method, can we be sure that the mentioned traces of heavy metals would always be picked up, in any sample? And yes, of course I know that Fe and Mn often co-occur and even interact in certain redox reactions/processes, but would you call either Fe or Mn a heavy metal?
I suggest you have your water samples analysed for dissolved metals using ICP-MS, which has a detection limit of around 0.001 mg/L for manganese and similar levels for other metals. Also compare your concentrations to WHO trigger values for environmental health, to gain an understanding of whether yours are high or not. For river water, I have measured concentrations of manganese from 0.001 to 0.4 mg/L.
Heavy metal is a bit of an arbitrary term used in different ways by different people. Molecular weight is generally not as important as toxicity and longevity in the environment in these definitions.
Also ensure that you have acidified your water samples with nitric acid as a preservative.
And also you may concentrate your samples before analysis, at least ten times.
Concentrate your samples or use more sensitive instruments like ICP-MS or ICP-OES (axial mode). and please acidify your sample to ensure it is in dissolved phase and also prevent from precipitation.
respected Chin... all my samples are acidified with dilute nitirc acid and i analysed the samples by ICP-OES only..
Usually we used concentrated nitric acid and analyse the sample as soon as possible (within 6 months). There will be certain heavy metals that stay below detection limit but I don't think that all metals also below detection limit. How about other major cations? Did you detect any Ca, Na, Mg, K? If you can't get these elements, then I think there must be error in the ICP-OES setting, or your standard solution. Check your calibration curve.
i think you have to check the pH of water samples. because the solubility of metal will be low at neutral pH. if the pH was very high or very low for the water samples it will soluable more concentration of metal, since acid and bases enhance the ability of the metal became metal ion and metal will disolved more in water. if water pH is neutral, metal will go to sediment and not soluable. it will inflict accumulation of the metal to sediment organism and rise the metal in sediment.
Presence of heavy metals in groundwater or surface water depends upon :
Water- rock interaction. Disintegration - dissociation and dissolution process. Chemical kinetic play a important role. Contact time between interaction is also important
- Badges
- Science topic