28 



encourage more rapid oxidation of elemental S, and leaching losses of 

 mineralized or fertilizer-applied S would be high. 

 1.2 ATMOSPHERIC SOURCES 

 1.2.1 Sulfur as a Pollutant 



Most studies of atmospheric S were done by those concerned with S 

 as an environmental pollutant. Atmospheric S is the cause of acid- 

 rainfall and direct S0 damage to plants in areas of high atmospheric 

 concentrations. Areas of heavy industrial development have been con- 

 cerned with this problem for decades, but rural areas of the southeast- 

 ern United States have not been as concerned with atmospheric S as a 

 pollution source. A few researchers have discussed the beneficial 

 aspects of atmospheric S as a nutrient source for crops (Fried, 1948; 

 Hoeft et al. , 1972; Jones et al. , 1979). This subject will be dis- 

 cussed in a later section. 

 1.2.1.1 Damage to plants 



The Copper Basin of southeastern Tennessee is an extreme example 

 of an area where 9,300 ha were denuded of vegetation by a combination 

 of SO from Cu smelting, forest removal, and over-grazing. Acute 

 damage can occur on certain forest trees at concentrations less than 

 0.25 ppm S0„ for 8 hours. Chronic injury or long-term effects were 

 noted in a Canadian forest when the trees were exposed to an average 

 S0„ concentration of 0.017 ppm for 5 months (Linzon, 1975). Acute and 

 chronic damage to agronomic plants by atmospheric S0 o has been 

 reported, but critical atmospheric levels of SO., have been difficult 

 to define (Heagle, 1972; Taniyama and Sawanaka, 1973; Tingey et al . , 

 19 73). 



