DonAndersen Posted October 11, 2008 Share Posted October 11, 2008 Guys/Gals, Looking over some data on productive waters. Some use TDS [ total disolved solids], electrical conductivity [ microSiemens/centermitre] or TFR [Total Fiterable Residue]. TFR is exprressed as: TFR=0.07 + 0505 * conductivity. OK - the question: Can TDS be expressed as TFR? Help!!!! Don Quote Link to comment Share on other sites More sharing options...
firefrog Posted October 11, 2008 Share Posted October 11, 2008 Hello Don All 3 of the results mentioned are recognized laboratory tests. (getting explainations of the test probably won't help you much) However, the TFR expressed looks like an approximation - not the true definition of TFR. Most of the time, this is a good estimate. Actually TDS and TFR are mutually exclusive. One is dissolved; the other is insoluble solids. Can you express one as the other? Technically, no. Confused? If you have a bag of dimes, and someone asks you 'How many dollars do you have?', technically you have none. But if you added up all the dimes, you would have an equivalent of x dollars. You can express one in terms of the other, but they're not the same. Science - sometimes exactly useless. Cheers Quote Link to comment Share on other sites More sharing options...
FlashGordon Posted October 11, 2008 Share Posted October 11, 2008 uhmmmm.... your what hurts??? Quote Link to comment Share on other sites More sharing options...
DonAndersen Posted October 11, 2008 Author Share Posted October 11, 2008 firefrog, So TFR and TDS are not the same. But can conductivity be used to express TDS? Strikes me that the larger amount of dissolved minerals [TDS], the higher the conductivity. As the bugs & plants use minerals for growth, the higher the TDS, the better the water is able to support biomass. regards, Don Quote Link to comment Share on other sites More sharing options...
Castuserraticus Posted October 11, 2008 Share Posted October 11, 2008 firefrog, So TFR and TDS are not the same. But can conductivity be used to express TDS? Strikes me that the larger amount of dissolved minerals [TDS], the higher the conductivity. As the bugs & plants use minerals for growth, the higher the TDS, the better the water is able to support biomass. regards, Don Conductivity is related to which ions are dissolved and does increase with concentration. There are variations in the electrical effect of different minerals but there's a reasonable relationship between TDS and NaCl equivalent TDS and conductivity. When the mineral concentrations become too high they become poisonous. Cell biochemistry holds a pretty delicate balance via osmotic transfer but there are plants and bugs adapted to many different salinities. There are rich, buy highly specialized plant and insect communities surrounding brackish sloughs in E Alta and Sask. Quote Link to comment Share on other sites More sharing options...
darrinhurst Posted October 11, 2008 Share Posted October 11, 2008 uh.....okayyyy Quote Link to comment Share on other sites More sharing options...
firefrog Posted October 12, 2008 Share Posted October 12, 2008 So TFR and TDS are not the same. But can conductivity be used to express TDS? Strikes me that the larger amount of dissolved minerals [TDS], the higher the conductivity. As the bugs & plants use minerals for growth, the higher the TDS, the better the water is able to support biomass. Hello again Conductivity can be used to express TDS if the correlation is established (eg it's linear, logarithmic, etc). This is often done to shorten workloads where hundreds or thousands of tests have to be done. The conductivity only takes a few seconds while the other tests are more labor intensive. Once a lab proves this correlation, it can go ahead with the conductivity tests. However, the correlation for one river water, for example, is not the same as that for wastewaters, or even other river waters. TDS is not just dissolved minerals (but mostly); it can also be soluble organic molecules (like sugars). True, micro-organisms readily use some of the TDS for growth, but they can also use minute particles (TFR). You're right, it's a reasonable generalization to say that more TDS supports more biomass. But as C'us mentioned there is a delicate balance here. Enough chemistry, I'm going to go play. Cheers Quote Link to comment Share on other sites More sharing options...
DonAndersen Posted October 14, 2008 Author Share Posted October 14, 2008 Guys, I have a lake with a TDS of 350. I have another with a conductivty of 185 and a TFR of 95. Now can I compare apples & oranges? I'm working from 2 data sets here and wish to compare them. Help!!, Don Quote Link to comment Share on other sites More sharing options...
firefrog Posted October 16, 2008 Share Posted October 16, 2008 Hello Don Sorry for the mumb-jumbo. You really need more information to make a good comparison. I found an article that says 'TDS=Conductivity * Factor That factor is determined emperically and can range from 0.55 to 0.9' Big ballpark. Hope this helps. Cheers Quote Link to comment Share on other sites More sharing options...
DonAndersen Posted October 20, 2008 Author Share Posted October 20, 2008 firefrog, My thanks for your help. Guess I'll have to run some TDS samples of my own. regards, Don Quote Link to comment Share on other sites More sharing options...
hydropsyche Posted October 21, 2008 Share Posted October 21, 2008 Enough chemistry, I'm going to go play. Cheers Bhurt......this here is a Pro. Quote Link to comment Share on other sites More sharing options...
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