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The Effect of Designated Pollutants on Plant Species

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Annual rept. no. 5, 1 Jul 1979-30 Jun 1980

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The phytotoxicity of short 20 minute exposure of HCl and HF gases and of liquid HCl as investigated in a series of studies under controlled greenhouse conditions and in the field. Field plants exposed weekly to gaseous HCl were injured when young but final plant heights, biomasses, and flower numbers were reduced only by repeated extraordinarily high doses. No decrease in numbers was found in microflora inhabiting field soil repeatedly exposed to high HCl doses. Five plant species exposed to gaseous HCl for 20 minutes were compared. Injury to cabbage head leaves did not occur on inside leaves. Dudleya, a succulent plant native to Vandenberg AFB, Ca. was highly resistant. Plants exposed to HCl plus ozone sustained greater injury than those exposed to either pollutant separately. Distilled water vapor removed large quantities of HCl from polluted air and the resultant acid mist was less phytotoxic than the original gas. Acid precipitation based on HCl was less phytotoxic than the same concentration of H2SO4. With sensitive beam plants, 0.1 HCl was injurious while 0.01 was not. Plant or tissue age or time of treatment did not significantly alter the amount of injury caused by acid sprays. Gaseous HF was more toxic than HCl gas. Of eight species exposed to HF gas for 20 minutes, beans were most sensitive and barley and dudleya were most tolerant. Exposure to HF gas reduced seed germination and seedling growth. Unexposed seeds of exposed soil and rinsed exposed seeds also were affected. Age influenced fluoride uptake and leaf sensitivity to short exposures of HF. Missile exhaust products at the Vandenberg launch site are potential damaging sources of HCl and HF.

Subject Categories:

  • Air Pollution and Control

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