The concentration of DO in shallow water body is largely controlled by temperature. As the temperature increases, the DO decreases - both on seasonal and daily cycle. An increase in oxygen in the metalimnion during stratification is a observation. When the salinity of water increases, its ability to dissolve oxygen decreases. Depending upon your water body, generally high salinity would increase conductivity. It is good to note that a stratified water body could prevent upwelling from occurring even during heavy monsoon seasons in tropical lakes.

The maximum solubility of gases depends on the temperature. Temperature dependence of equilibrium constants, in our case the Henry´s law constant, can generally be described with the van ’t Hoff equation. However, there is NO relationship between temperature and DO in such a way that the DO could be calculated from temperature. You could calculate the maximum solubilty of oxygen in water but not the actual oxygen concentration since it depends mostly on microbial activity. With measuring only salinity, conductivity or temperature DO can not be calculated. Did you measure other parameters like dissolved Fe2+ or  Mn2+?

Dear Mohd Yusoff Ishak and Dr Jan Helge Richard, Thank you for providing valuable guidelines.  we measured physio-chemical parameters of pH, Salinity, EC, Temp, TN, DTN, TP, DTP, PO4, NH4, NOx, NO2, NO3 along with Chl-a concentrations at 3 depth profiles (surface, middle and bottom) of relatively stratified shallow (2 meter depth) water body. but we do not measured the Fe2 and Mn2 concentrations. we also measured the ODO at the middle profile but we do not have data of DO at surface and bottom profiles. Therefore, i am looking for any indirect method of measuring DO in water. 

Salinity and Electrical conductivity are interrelated. Temperature may be indirectly related. But Dissoved Oxygen is a different parameter may not much related to salinity/EC/Temperature of water.

There appears a negative correlation between DO concentration and temperature on on diurnal and seasonal cycle. The similar relation is  also witnessed between DO and salinity. With increasing salinity conductivity gradually increases,  which goes parallel to increasing Eh that is characteristic feature of aerobic/oxic state. Hence one can state one-to-one relationship and correlation but subject to a multitude of physicochemical factors in an ecosystem it relationship may not always match with the assumption or the correlation coefficient may be weak. It is better to measure DO directly, not from chart prepared on the basis of correlated factors; this is especially true for natural waterbodies or ecosystems while no two systems are same or alike on all counts!

production/concentration of DO is also subject to many other factors like type of water bodies (lentic or lotic system), mixing influx from nearby sources, biological standing biomass (plankton, macrophyte, macroinvertebrate, periphyton and fish)

The physical relationship between temperature and oxygen is true. However, it is vitally important not to leave out biological processes affecting DO, which may dominate physical processes. Salinity effects on DO are very indirect. Daytime photosynthesis can supersaturate DO below the surface, and nighttime respiration can reduce DO to anoxia, depending on the water's trophic status, completely independent of salinity (eutrophic implies strong biological effects). Chl-a concentration can be used as a surrogate for biomass, and as a trophic status indicator. NH4 and NO3 can be used as a rough measure of DO: In anoxic conditions, NO3 is biologically reduced to NH4; under oxic conditions, NH4 will be oxidized to NO3. The shallow depth may work against anoxia, however, stratification will tend to promote anoxia near the bottom.

We have conducted hydrochemical investigations of freshwater fish ponds with average depth about 1 -1,5 m. Analyses of seasonal relationships clearly indicated positive correlations between the temperature and DO especially in ponds not intensively covered with macrophytes. However, DO levels in waters were strongly dependent from aquatic plants development. Increased standing biomass of macrophytes has resulted in reduction of DO near to anoxia during the nighttime and gradual increase of DO up to saturation during the midday time (see attached photo).

https://www.researchgate.net/publication/308934198_Hydrochemical_regime_of_fish_ponds_of_the_BTB_Lmtd_Fish-farm_in_upper_Chirchiq_district_of_Tashkent_Region?ev=prf_pub

Conference Paper Hydrochemical regime of fish ponds of the “BTB Lmtd” Fish-fa...

 Thank you all the respected researchers for their constructive response, on the basis of discussion we can conclude that Salinity and EC are not physically related to DO. but temperature along with Chl-a concentrations/biomass, NH4, and NO3, NO2 have definite impact  on the concentrations of DO and are directly related to each other, especially in the state of hypoxia. As i discussed earlier, the water body sampled has dominant floating macrophytes and there were many colonies outside the diameter of 100 meters from sampling point.  what i concluded from this discussion is that temperature, biomass, NH4, and Nitrates, nitrites can be used to detect the DO concentrations in the surface and bottom profiles of shallow water body. am i right?

Abdul, I think most of your summary is on the right track. NO3 and NH4 will only provide an imprecise oxic-anoxic threshold. It's unlikely to enable you to measure DO precisely in the oxic range. I'm not sure exactly where the threshold is, but I think bacteria will energetically prefer available O2 over NO3, and won't start reducing NO3 to NH4 until O2 levels are VERY low.

Dear Abdul, I think Ted is right here when he says that DO cannot be calculated from the concentrations of NO3 and NH4. In general the so called redox sequence is from O2 reduction over denitrification (reduction of NO3), Mn- and Fe-reduction, to sulfate reduction (e.g. Appelo & Postma, 2005). However, in your case there might also be other factors of importance. Can you exclude the influence of sewage or other types of waste water? NH4+ is a product from protein degredation and isoxydized to NO2 and NO3 by microorganisms under O2 consumption. Fish may also have an influence on the NH4+ concentration in the water body. That means that NH4+ can be elevated in the water body without O2 having to be very low, so I think you simply cannot use the parameters you measured for DO estimation. However, if I got you right, you said that you measured DO in one of your depth profiles, but only at medium depth and not at the surface or close to the bottom. In general, DO is highest close to the surface of a stratified water body and may even exceed oxygen solubility during daytime because of O2 production by algae, leading to O2 degasing to the atmosphere. DO concentration is usually lowest close to the bottom of the water body because of degredation processes. Dissolved Mn (Mn2+) and (further down) Fe (Fe2+) are here a good indicators for anoxia. See also the link below for typical profiles of different parameters in a stratified lake (from: Geochemistry of a large impoundment – Part II: Fe and Mn cycling and metal transport).

https://d3crioero8yadl.cloudfront.net/content/geochem/16/2/165/F6.medium.gif

No single parameter can exactly serve as 'surrogate' of DO. No the nitrogen species (NH4-N, NO3-N & NO2-N) transformation are closely related to DO levels in the aquatic systems but nitrogen cycling is too dynamic to estimate exactly the said species! Microbial decomposition of organic matter is another issue to be reckoned. Bacteria has preference to derive energy from organics with regard to available terminal electron acceptors, which follows: O2>NO3>Mn2+>Fe3+>..........Naturally all those species may be used as indicator of DO but not as an indirect scale for measuring  the DO. Only again I repeat, the prevailing physicochemical regime (which is not a in stasis but dynamic state!) in the aquatic system is the product of the complex interplay of a multitude of physicochemical factors which are also in changing state. But through modelling of an aquatic system using the best subset method or principal component analysis one can indirectly measure approx. DO level of the system on a time scale (day, month), again that would be an approximation!

The solubility of O2 is affected by temperature nonlinearly, generaly it decreases with increasing temperature and increases considerable in cold waters.You can find orthograde oxygen profile in an oligotrophic lake, where DO levels with depth are controlled by physical processes during summer stratification. DO decreases with gradual increase in temperature. But in eutrophic system the DO content of the hypolimnion gets depleted due to high oxidative processes. Due to such depletion of DO the hypolimnion becomes anaerobic and results a clinograde oxygen profile.

With increase in temperature salinity increases while there occurs a decreasing trend  in DO.

Again with an increase in temperature increases conductivity due to decrease in viscosity plus increase in ionic concentration.

But in no case you should not take indirect measure as measuring scale for DO. It can give you just an impression, an approximation, not the proper value while the system is too dynamic.

Now dear  Abdul, i think you have understood the matter!

Abdul Jalil, I wonder if you found an algorithm for your polluted water body which correlated DO with salinity, conductivity and/or temperature. Care must be taken to specify the environment in which it was done. But off course there is a correlation... a complicated one. Oxygen dissolves better on low temperature because, at a higher temperature, the kinetic of the molecules and they will scape easier. However in higher temperature weather the sun radiation would be higher, and fauna and flora would increase their photosynthesis/respiration processes, so that would likely increase the oxygen content since it would be the final electron receptor, but the decomposition of the organic matter would consume oxygen. Salinity, on the other hand, would increase the facility in which the electrons move (conductivity). Increment on temperature would also increase conductivity and decrease viscosity. However the Conductivity increases with salinity depending upon the amount of type of electrolytes, so by pH 7 the charges would be neutralised and would increase towards the extreme pHs. Eutrophication in water bodies deplete Oxygen, so the final acceptor is not likely to be Oxigen, but Nitrogen, Manganese, Iron, Sulfur or organic matter. So depending upon de type and content of the main substances/metabolites/substrates/ in solution would depend on the type and amount of animals, plants, fungi, bacteria, archaea or even virus, that adapt to this conditions, or is it the contrary?. In any case, oxygen is likely to become complexed or consumed. Ultimately it would be too many different parameters to take into account and the direct measure would be advised.