Eight plant species were subjected to artificial acid rains of pH 2.5, 2.0, 1.5, 1.0 and 0.5 in order to determine the threshold for and symptoms of damage. The plants were Erechtites, Robinia, Pinus, Quercus, Carya, Liriodendron, Acer and Cornus from the Coweeta Hydrologic Laboratory near Franklin, North Carolina. Droplets of pH 2.0 produced brown necrotic spots on all species except Pinus while droplets of pH 1.0 produced necroses on leaves of all species examined. The size of necrotic spots increased with increasing acidity. Comparison of these results with the literature suggests that developing leaves are more easily damaged than are the mature leaves used in this study. The volume weighted average rainfall pH for Coweeta is 4.6 with observations ranging from 3.2 to 5.9. Results of this study suggest that a 10-fold increase in acidity from pH 3.2 to 2.2 in a single spring or summer storm could bring damage or death to mature leaves of dominant flowering plants in the Southern Appalachians.

The herbicide bromacil was applied annually or once in 2 yr to a railway track on a sand bed. Once a year, in the Spring, just before a possible next application, samples were taken from various depths down to at least 80 cm for residue-analysis by gas chromatography. The procedure for extraction was adapted in order to eliminate interfering substances originating from the dark top layer of the soil. Bromacil contents were always highest in the 10 to 20 cm layer. Within the first 2 yr of the experiments the compound penetrated down to depths around 100 cm. Calculations showed that deeper penetration of bromacil was probable. On account of the low conversion rate of the herbicide it seems possible that a part of the bromacil dosage leached to the groundwater later on

The aerobic and anaerobic degradation of phenol and selected chlorophenols was examined in a clay loam soil containing no added nutrients. A simple, efficient procedure based on the high solubility of these compounds in 95 per cent ethanol was developed for extracting phenol and chlorophenol residues from soil. Analysis of soil extracts with UV spectrophotometry showed that phenol, o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol were rapidly degraded, while m-chlorophenol, 3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were degraded very slowly by microorganisms in aerobically-incubated soil at 23 deg C. Both 3,4,5-trichlorophenol and 2,3,4,5-tetrachlorophenol appeared to be more resistant to degradation by aerobic soil microorgamisms at 23 deg C. None of the compounds examined were degraded by microorganisms in anaerobically-incubated soil at 23 deg C. Direct microscopic observation revealed that phenol and selected chlorophenols stimulated aerobic and to a lesser extent, anaerobic microbial growth in soil, and aerobic soil bacteria were responsible for the degradation of 2,4-dichlorophenol in aerobically-incubated soil at 23 deg C. Phenol, o-chlorophenol, m-chlorophenol, p-chlorophenol and 2,4-dichlorophenol underwent rapid non-biological degradation in sterile silica sand. Non-biological decomposition contributed, perhaps substantially, to the removal of some chlorophenols from sterile aerobically-incubated soil and both sterile and non-sterile anaerobically-incubated soil