14 



3.2.5.2 Boron 



Figure 3.8 shows that during 2000, boron concentrations in the East Poplar River at International 

 Boundary varied from 0.961 (May 26) to 2.01 mg/L (June 12). 



The three-month moving FWC for boron for the period of record is shown in Figure 3.9. The short-term 

 objective of 3.5 mg/L has not been exceeded over the period 1975 to 2000. It can be seen that the data 

 derived from grab samples and that derived from regression with specific conductance are similar, with 

 the highs and lows in some degree of correspondence. This suggests that the regression generation of 

 boron and TDS values is, in general terms, a valid procedure despite problems which arise from 

 attempting to generate representative concenfration and flow data for an entire month, based on a limited 

 number of samples. 



The five-year moving FWC for boron displayed in Figure 3.10 remained well below the long-term 

 objective of 2.5 mg/L. From mid- 1993 to the end of the data period there is a distinct drop in the 

 computed boron concentrations. 



It is apparent that TDS is better-correlated with specific conductance than is boron. Boron is a relatively 

 minor ion, and does not in itself contribute to a large degree to the total load of dissolved constituents in 

 the water. Accordingly, it appears likely that the standard deviation of dissolved boron (relative to the 

 long-term mean boron concentration) may be greater than that of the major cations (sodium, potassium, 

 and magnesium) and anions (sulphate, bicarbonate, and chloride) around their respective long-term 

 mean concentrations. Daily boron concentrations for the period December 1989 to December 2000 are 

 shown in Figure 3.1 1. 



The relationship between boron and specific conductance at the East Poplar River sampling location 

 during the period 1975 to 2000 is described by the equation: 



boron = (0.0013 x specific conductance) - 0.034 

 (R^ = 0.58, n = 555) 



