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The di-π-methane photoisomerization of dimethyl 9-acetoxy- and 9- hydroxy-9,10-dihydro-9,10-ethenoanthracene-11,12-dicarboxylate has been investigated. The 9-acetoxy compound (28) rearranges regiospecifically to give dimethyl 4b-acetoxy-4b,8b,8c,8d- tetrahydrodibenzo[a,f]cyclopropa[cd]pentalene-8b,8d-dicarhoxylate (29), i.e. a dibenzosemibullvalene. Rearrangement of the 9-hydroxy compound (16) gives one of two keto diesters (17) and (18) depending on the solvent used. The keto diesters have been shown to be indeno[1,2- alinden-9-ones epimeric at C 10 and are probably formed by further rearrangement of one of the expected hydroxydibenzosemibullvalenes (31). The regiospecific rearrangement of the 9-acetoxy and 9-hydroxy compounds (28) and (16) by alternative pathways is explained in terms of the effect of hydrogen bonding and the electronegativity of the 9- substituents upon the reaction profile.

This study describes some of the effects of 8 years of annual application of 6 types of phosphatic fertilisers on the chemical composition and aluminium (Al) speciation in soil solution extracted from a soil under pasture. Soil samples at 2 depths, 0-30 and 30-75 mm, were collected at the end of 8 years. Soil solutions were extracted by centrifuging at 12 000 RCF and analysed for Al, Na, K, Ca, Mg, F, NO3, Cl, and SO4, as well as pH and ionic strength. Soil and soil solution pH were significantly increased at both depths by application of North Carolina phosphate rock (NCPR) compared with the control. In contrast, diammonium phosphate (DAP) significantly decreased the soil and solution pH. Single superphosphate (SSP) did not have any significant effect on soil or solution pH compared with the untreated control. The surface soil (0-30 mm) solution pH was on average 0.6 of a unit higher than the subsurface soil (30-75 mm) solution pH. Total monomeric Al concentration [Al], measured by the pyrocatecol violet (PCV; 4 min) method, ranged from 1.5 to 4.8 M in the surface soil and 2.5 to 12.2 M in the subsurface soil. The DAP and higher rates of SSP application resulted in a large increase in total and inorganic monomeric [Al] in the soil solution extracted from the subsurface soil. Total soluble [F] ranged from 2.7 to 23.5 M and 3.2 to 25.6 M in the surface and subsurface soils, respectively, and was significantly increased by the application of NCPR and by higher rates of SSP. The predominant forms of inorganic monomeric Al present in the soil solution were estimated to be the non-phytotoxic Al-F complexes, AlF2+, and AlF2+. There was a marked decrease in toxic Al species (Al3+, Al(OH)2+, Al(OH)2+) in soil solution following NCPR and SSP application. This was due primarily to complexation of Al with F derived from these fertilisers forming non-toxic AI-F complexes. The results suggest that the long-term application of reactive phosphate rock such as NCPR may contribute to amelioration of soil acidity and Al toxicity under legume-based pastures. In contrast ammonium-containing phosphate fertilisers such as DAP probably decrease soil pH and increase the formation of toxic Al species in the soil solution.

Sorption and movement of 2 ionic herbicides (2,4-D and atrazine) by 3 soil materials (Tokomaru silt loam, Egmont silt loam, mine tailings) which were amended with different levels of exogenous carbon (C) materials (poultry manure, sewage sludge, mushroom compost, peat, pig manure) were examined using 14C-labelled compounds. The sorption of herbicides was measured using a batch technique and the movement was examined using soil columns in which a pulse of 14C-labelled herbicide was leached with dissolved organic C (DOC). Sorption of herbicides, as measured by the distribution coefficient (Kd), increased with increasing C addition, and varied between the C sources. The difference in the effect of C sources on the sorption of herbicides was related to the difference in the amount of DOC and the pH. The increase in the Kd values per unit C addition decreased with increasing amounts of both the exogenous C addition and the indigenous C in the soil material. In a separate study, the addition of DOC to solutions of herbicides prior to sorption measurements decreased the sorption of herbicides, whereas the addition of DOC to soil increased the sorption of herbicides. Column studies have shown that DOC enhanced the movement of herbicides in soils. The effect of DOC on the movement of herbicides varied between the soil materials and may be related to the difference in the sorption of both the herbicides and the DOC.

Simple and inexpensive apparatus is described for studying the solute movement during unsaturated water flow through intact soil columns. A preset pressure head is maintained at the top and bottom of the soil. The applied solution is easily changed, and there is negligible 'dead volume' both above and beneath the soil. Columns 37-150 mm long, carved from the A horizons of a well structured silt loam and a weakly structured fine sandy loam, were used in the apparatus. After the soil was preleached with calcium sulfate solution, solid potassium nitrate was applied, followed by a solution of potassium chloride. Nitrate and chloride concentrations in the effluent, and in the soil after leaching, were measured. With the imposed pressure heads of between -40 and -150 mm, flow rates ranged from 0 . 5 to 9 mm/h. The convection dispersion equation (CDE) with the appropriate boundary conditions was found to adequately describe the flow of chloride and nitrate in both soils. The outflow concentration data indicated all the soil water participated in the solute transport, and the chloride breakthrough curves scaled with column length as predicted by the CDE rather than by stochastic-convective theory. The dispersivity values for the well structured silt loam were 15 and 19 mm. The values for the weakly structured fine sandy loam were 68 and 27 mm. The dispersivity may be a useful structure index, as well as being the key parameter needed to describe solute movement. The resident concentration data indicated all the water in the well structured soil was mobile, but about 15% of the water in the weakly structured soil was relatively immobile.

Surface samples of an allophanic (Patua silt loam) and a non-allophanic (Tokomaru silt loam) soil were used to examine the effects of drying on the adsorption and leaching of phosphate and 2,4-dichlorophenoxyacetic acid (2,4-D). Phosphate and 2,4-D adsorption isotherms and adsorption kinetics were determined for field-moist, air-dried and oven-dried soil samples using KH2PO4 and 14C labelled 2,4-D. In a separate experiment, the leaching of a pulse of phosphate or 2,4-D was examined using soil columns. The Patua silt loam adsorbed 4-7 times more phosphate and 2,4-D than the Tokomaru silt loam. Compared with field-moist soil, both air-dried and oven-dried soil increased (2-5 times) the adsorption of phosphate, and oven-dried soil decreased the adsorption of 2,4-D. The adsorption kinetics indicated that there was no effect of drying on the rate of adsorption of either phosphate or 2,4-D. In column experiments, there was less leaching of phosphate and 2,4-D from the Patua soil than from the Tokomaru soil. In both soils, there was no effect of drying on the leaching of phosphate, whereas oven-drying increased the leaching of 2,4-D. Solubilization of organic matter during drying increased the accessibility of P to adsorption sites on the mineral surface and thereby increased the adsorption, whereas the water-soluble organic matter bound 2,4-D and thereby decreased the apparent adsorption onto soil and increased leaching