An odd discrepancy in the EC-Temperature relationship
As stated above, “Conductivity increases approximately 2-3% per 1°C increase in temperature”. Bruce S. in his volunteer monthly monitoring of EC in surface waters associated with Sandy Lake, makes in-situ measurements of temperature and EC, and then brings a sample back to his home which he leaves at room temperature overnight and then measures them again the next day. We have kept records of these dual measurements – see Original Field Observations on the Seasonal Monitoring page – and typically the next-day EC values are somewhat higher (as is the temperature).
In 2023 he began occasional sampling of some standing water near a salt pile within the watershed. Here are two sets of values:Upper Pond by salt storage
Date EC (uS/cm) Temp (deg C) May 5 1693 12.6 Next Day 908 17.7 May 8 3066 14.3 Next Day 2107 20.4 I had commented that I thought the Next Day value for the May 5 sample was odd, so he took another sample, and obtained similar results. Clearly, EC decreased after overnight incubation/higher temperature. This suggests there was some chemical changes overnight, perhaps related to an additive in the road salt.