0141683 



Heilman and Ekuan (1977) investigated soil extractable 

 arsenic levels around the ASARCO smelter near Tacoma, Washington. 

 They extracted soil arsenic with concentrated HC1 in a 1:5 soil to 

 acid ratio; the same method was used for the Helena Valley 

 investigation. These investigators determined a significant 

 correlation (r = .625) between extractable soil arsenic and the 

 arsenic levels present in above ground garden biomass. The 

 correlation was also significant (r = .475) between extractable 

 soil arsenic and below ground garden biomass (roots). These 

 results suggest determination of extractable soil arsenic with 

 concentrated HC1 is indicative of the soil arsenic level that the 

 plant can absorb. Therefore this method has merit for the deter- 

 mination of plant available arsenic in soils. 



As a check between soil test levels obtained from this method 

 and the NaHCC>3 method (which may be considered a more standard 

 method), duplicate samples from two soils (one with high and one 

 with low arsenic levels) were extracted with both solutions, and 

 analyzed for arsenic (Table 33). All work was performed by the 

 Soil, Plant, and Irrigation Water Testing Laboratory at Montana 

 State University, Bozeman, MT. 



Table 33. Comparison between concentrated HC1 and NaHC03 for 

 determination of extractable soil arsenic (ppm) . 



Concentrated 



Sample HC1 NaHCC>3 



"2518 40.46 36.34 



2518-2 37.31 No Data 



STD-C 3.01 2.67 



STD-C-2 1.98 1.50 



The samples designated STD-C are in-house laboratory stan- 

 dards used for quality control. The close agreement in soil- 

 arsenic levels provided by the two extracting solutions suggests 

 that the concentrated HC1 method provides results similar to the 

 NaHC03 method for these soils. 



33 



