• Cumulative evaporation measurements from Peck pond were correlated to calculated 

 reference evapotranspiration (ET ) from a nearby CIMIS weather station in Mumeta 

 Farms. An ET^ correction factor (Y) was determined to correlate cumulative pond water 

 evaporation rates (E) at different salinities up to EC of 61 dS/m, i.e., 



Y = 1.3234 - 0.0066 EC (dS/m) 



E= (ET.)(Y) 



• The relations between evaporation rate and dependent variables such as wind speed, 

 vapor pressure differences between air and water surfaces, salinity and specific gravity 

 are presented. 



• Dal ton's model was used to calculate evaporation rates from pure water and saline 

 waters (EC = 14 dS/m) and these were compared to measured data. Although the 

 calculated results deviated in some cases substantially at hourly intervals, improved 

 trends were obtained by smoothing over longer elapsed time intervals. 



Diurnal Monitoring • Pond Waters 



• At the same time the above-the-pond weather data was being monitored at Peck, Pryse 

 and Barbizon ponds, pond waters were monitored at 2-hour intervals for water tempera- 

 ture, density, EC, pH, DO (Dissolved Oxygen) and Eh (redox potential). 



• Cyclical variations in several water quality parameters were observed. For instance 

 variations in DO are directly related to the activity of phytoplankton and water 

 temperature. Fluctuations in water temperature are dampened and lagged slightly 

 behind air temperature. 



. In contrast, diurnal changes in EC, density, pH and Eh were not readily distinguishable. 



Pond Mineralog>- and Trace Elements 



• Minerals (evaporites) precipitated along the shorelines, in drying pond bottoms, and 

 within the brine water column were sampled from 1987-1988. 



• 



The types of evaporites formed in the water column were strongly influenced by the 

 initial chemistry of the drainage influent water and degree of evapoconcentration. The 

 formation of such evaporites could be predicted by C-Salt, a brine chemistry model 

 previously reported in the Interim Report. 



In contrast, evaporites formed along shorelines are subjected to extreme ranges of 

 wetting and drying and tended to reHect larger mineral assemblages as saline waters are 

 subjected to near air dryness. 



In the Peck. Pryse and Barbizon ponds, 1 borate, 3 chloride. 10 carbonate, and 19 

 different sulfate minerals were identified. These evaporites ranged from hydrated and 

 nonhydrated species, e.g., gypsum (CaS0/2H,0) and anhydrite (CaSO^, doub e sa s, 

 e E bloedite(Na,SO .MgSO«5Hp)andburkeite(Na,C03'2Na,SO;.andtripe salts, 

 eg'p ?yhaHte(^SO •2Cas6/M^O/2Hp)andtych.te(2Na,C03.2 



p€ige 1.12 



