14 

 3.2.5.2 Boron 



Figure 3.8 shows that during 1999, boron concentrations in the East Poplar River at the International 

 Boundary varied from 0.90 (March 30 and May 18) to 1.86 mg/L (December 20). 



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 1999. 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 concentration 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) in ground water discharge may be greater than that of the 

 major cations (sodium, potassium, magnesium) and anions (sulphate, bicarbonate, and chloride) around 

 their respective long-term mean concentrations. Daily boron concentrations for the period December 

 1988 to December 1999 are shown in Figure 3.11. 



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

 during the period 1975 to 1999 is described by the equation: 



boron = (0.0013 x specific conductance) - 0.034 

 (R^ = 0.58, n = 555) 



