US EPA

92746 

Journal Article 

Pufferkapazitat gesunder und rauchgeschadigter Fichtennadeln 

Grill, D 

1971 

1 

Journal of Plant Diseases and Protection
ISSN: 1861-3829
EISSN: 1861-3837 

78 

10 

612-622 

English 

http://www.jstor.org/stable/43215996
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1. Changes of pH after addition of increasing quantities of acid and base to homogenized needles of spruce (picea abies [L.] Karsten) are tested and compared as expression of their buffer capacity. Above all buffering is considered in the pH range of homogenisates. 2. Buffer capacity showes in its formation a characteristical fluctuating course the year round: one maximum in May and a second in July. Furthermore there is a third but small one against H⁺ before young needles are peeping out. 3. Buffer capacity is diminishing when needles growing older. 4. Needles fumigated with SO₂ are usually less buffered than not damaged ones. Trees growing in city atmosphere are showing also a less buffer capacity compared with controls during a year. A resistant tree has been distinguished by high buffer capacity. 5. Buffer capacity and amount of organic acids alter in the same way. 6. Change of buffer capacity is probably produced mainly by COOH-groups of organic acids, phenolic OH⁻ and amphoteric electrolytes. 7. Alteration of buffer capacity is not to be comprehended as neutralization, because buffering against H⁺ and OH⁻ is changing equally (especially in the range of pH of homogenized needles). 8. SO₂ resistance determined by cellphysiological methods during one year and variation of the resistance with the age of needles agree well with the alteration of buffer capacity.