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During 1986, the Montana Department of Health and Environmental 

 Sciences continued to operate an extended network of lead dioxide 

 sulfation plates in the Poplar River area. The sulfation plate 

 network includes the existing primary monitoring site and eight 

 additional locations: International Boundary, Richardson, Hanrahan 

 Ranch, Microwave Tower, Flaxville, TV Tower Hill, Scobey Downtown and 

 Four Buttes. The objective of the sulfation plate network is to 

 obtain a broad geographical indication of sulphur dioxide concentra- 

 tions and to investigate the relationship between sulfation rate and 

 sulphur dioxide concentrations. 



During 1986, the highest monthly sulfation rate was 0.02 milligram 

 per 100 centimetres squared per day (mg/100 cm^/day) at Flaxville and 

 Scobey Downtown. These readings, which occurred during January and 

 February, are low. 



