We investigated the effects of vegetation on the fate of pentachlorophenol (PCP) in soil using a novel high-flow sealed test system. Pentachlorophenol has been widely used as a wood preservative, and this highly toxic biocide contaminates soil and ground water at many sites. Although plants are known to accelerate the rates of degradation of certain soil contaminants, this approach has not been thoroughly investigated for PCP. The fate of [14C]PCP, added to soil at a concentration of 100 mg/kg, was compared in three unplanted and three planted systems. The plant used was Hycrest, a perennial, drought-tolerant cultivar of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. The flow-through test system allowed us to maintain a budget for 14C-label as well as monitor mineralization (breakdown to 14CO2) and volatilization of the test compound in a 155-d trial. In the unplanted systems, an average of 88% of the total radiolabel remained in the soil and leachate and only 6% was mineralized. In the planted system, 33% of the radiolabel remained in the soil plus leachate, 22% was mineralized, and 36% was associated with plant tissue (21% with the root fraction and 15% with shoots). Mineralization rates were 23.1 mg PCP mineralized kg-1 soil in 20 wk in the planted system, and for the unplanted system 6.6 mg PCP kg-1 soil for the same time period. Similar amounts of volatile organic material were generated in the two systems (1.5%). Results indicated that establishing crested wheatgrass on PCP-contaminated surface soils may accelerate the removal of the contaminant.

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Covalently bound adducts of poly(L-lysine), bovine serum albumin, lysine rich histone (f1) and deoxyribonucleotidase I (DNase, EC 3.1.4.5) with adenosine diphosphoribose and ribose-5-phosphate were prepared at pH 7.4 and 9.5. Macromolecular adducts of bovine serum albumin and histone (fl) (4); and of the specific glycohydrolase which degrades poly(ADP-ribose) to ADP-ribose in nuclei (5-8), provides known enzymatic pathways for ADP-ribose formation in these DNA containing organelles. Because it is estimated that the turnover of NAD+ in HeLa cells is about 20 times higher than required to maintain the NAD+ pool size during growth (9), it is unclear whether the catabolic products of NAD+ which should be available in abundance have an as yet unrecognized biological function. Association of ADP-ribose with regulatory macromolecules generating protein products that are covalently altered is one of the possible consequences of high cellular turnover of NAD+.The first question requiring clarification is the identification of the nature of the chemical bond formed between ADP-ribose and macromolecules (2). We are describing the interaction of ADP-ribose and of ribose-5-phosphate with purified model substances: poly(L-lysine), Iysine rich (fi) histone (10), crystalline bovine serum albumin (BSA) (18), crystalline deoxyribonuclease I (DNase, EC 3.1.4.5) (11), spermine, spermidine, and L-lysine. Some conditions chosen for these studies are physiological (pH 7.4); therefore, it is predictable that the reactions described can occur in vivo.

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