The rate of disappearance of buried pine wood in Florida was found to be 15%/yr.As consumption by microorganisms and termites proceeded, the wood also became more compressible. After only 5 yr, consumption and compression could account for 60-70% loss of original volume of wood under pavement near the surface of an embankment. This large volume loss occurring in a relatively short time period may be responsible for many surface deformations in pavements and weaknesses in other embankments where wood may occur as a contaminant.
Potentiometric titration of weakly acidic sites on soil clays is limited in aqueous media by the acidic property of water which prevents sharp endpoints. Generally, it is not possible to obtain sharp endpoints in aqueous systems for acids with pKa > 8. In this study, kaolinite with K, H, or Al as the saturating cation was successfully titrated in water and acetonitrile using the glass‐calomel electrode system for potentiometric determination. Sharper endpoints and wider working potential ranges were obtained in acetonitrile than in the aqueous system. Titer of base needed to reach the final endpoint was greater in acetonitrile than in water; for example, K‐saturated clay required a negligible titer in water (0.4 meq/100 g clay) in contrast to acetonitrile, in which a significant titer (7.4 meq/100 g clay) was required. The larger titer in acetonitrile was attributed to (i) pH‐dependent sites for which a quantitative endpoint was not obtained in water due to the acid‐base properties of this solvent, and (ii) an increased surface acidity in acetonitrile. A comparable difference in total titers at the final endpoint was observed for the titration of H‐ of Al‐saturated kaolinite in water and acetonitrile.
In a pot‐culture experiment with four highly‐thatched turfgrasses [bermudagrass, Cynodon dactylon(L.) Pers.; centipedegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensisL.; and St. Augustinegrass, Stenotaphrum secundatum(Walt.) Kuntze] we examined the influence of selected white‐rot fungi and topdressings on the degradation of thatch components. Cores of each turfgrass were placed in pots and inoculated with one of four species of white‐rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inoculation and after the 6 month sampling. Subplot treatments of the split‐plot design were three topdressings (none, 0.31 cm sand, and 0.31 cm sand containing 4% colloidal phosphate). Samples of thatch were collected 6 and 12 months after inoculation and analyzed for cellulose and lignin by the acid detergent fiber procedure. Total oxidizable organic material and C and N were also determined. The cellulose content of bermudagrass and centipedegrass thatch was significantly reduced by Phebia gigantea, but no fungus significantly reduced the thatch cellulose content of St. Augustinegrass and Kentucky bluegrass. Coriolus versicolorsignificantly reduced the lignin content of thatch from all turfgrass species and the total oxidizable organic material of bermudagrass and centipedegrass. It appears to hold some potential for decomposing accumulated thatch. Topdressings with sand or a mixture of sand and colloidal phosphate significantly reduced the cellulose and lignin contents of thatch from most of the turfgrass species. Adding colloidal phosphate to the sand did not significantly increase the decomposition rate of the thatch. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose.
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