A one-year greenhouse experiment was conducted to study the transfer of copper from contaminated agricultural soils to edible and nonedible structures of lettuce, tomato, and onion plants. Study soils were selected from two basins of central Chile (Santiago and Cachapoal) to represent two similar total soil copper gradients with different pH values. Results showed that free ionic Cu and Cu in saturation extracts were very low in comparison to total Cu contents of study soils (<0.002% and <0.04%, respectively). The concentrations of free ionic copper and of copper in saturation extracts were correlated to total Cu levels and to soil pH. Mean copper concentrations were higher in lettuce than in tomato and onion plants and in vegetables grown on acidic soils of the Cachapoal basin. However, copper levels in edible tissues of tomato and lettuce plants were similar to copper levels described for plants grown on unpolluted soils except for onion bulbs, which had higher values. This indicates that copper translocation to edible, above-ground structures seemed to be well regulated, as their concentrations were fairly constant. The study shows that Cu concentration in study vegetables depends on various factors, including plant species and tissue; site-specific soil factors, such as pH, organic matter, dissolved organic carbon, and conductivity; and several Cu pools, such as total, extractable, and free ionic Cu. Thus, our results support the intensity/capacity concept in that Cu concentration in plants or plant tissues depends not only on the availability of free copper ions in soil solution but also on other soil copper pools that supply the element to the soil solution.

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A survey of copper levels in agricultural soils of central Chile revealed two soil clusters-one with a mean copper level of 162 mg/kg and one with a mean copper level of 751 mg/kg of soil. Samples of soils from both soil clusters were characterized on the basis of physicochemical characteristics, and copper extractability was compared by saturation and CaCl2 extraction as well as an acid-leaching procedure (TCLP). We also measured the copper content of various tissues of tomato (Lycopersicon esculentum) and onion (Allium cepa) crops growing on these soils. Other than copper levels, soils from the two clusters were quite similar, with slightly greater levels of molybdenum and cadmium in the high-copper soils. Within each cluster, extracted copper levels and total soil copper levels were not correlated. However, the three extraction procedures solubilized significantly more copper from the high-Cu soils. Mineralogical characterization of the soil particles and depth profiles of soil metal levels in a subsample of sites suggested that highly insoluble copper ore and mining wastes might account for the high copper levels. Neither total nor extractable copper levels allowed statistical prediction of the levels of copper in plant tissue. The edible tissues of both crops had the same mean copper content, regardless of the copper soil level. However, copper contents of stems and leaves were significantly higher for plants growing on the high-Cu soils. These results show that in these soils, high copper levels are associated with very insoluble copper species and thus low bioavailability of copper to crop plants.

Direct wood liquefaction of pine sawdust (Pinus radiata) in a hydrogen donor solvent (tetralin), was studied in a 0.5 L autoclave using Co‐Mo/γ‐Al2O3 and Pt/γ‐Al2O3 supported catalysts. Uncatalyzed as well as Raney Nickel catalyzed runs were also performed for comparison purposes. Reaction temperature was kept at 673 K and total system pressure at 10 MPa in all cases. Weight ratio of solvent to solid loaded was 2:1, the gas phase being either H2 or N2. Independent runs were also performed with cellulose and lignin which are the main wood constituents. Reaction products were characterized by means of gas chromatography and solvent fractionation using specific solvents.

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A one-year greenhouse experiment was conducted to study the transfer of copper from contaminated agricultural soils to edible and nonedible structures of lettuce, tomato, and onion plants. Study soils were selected from two basins of central Chile (Santiago and Cachapoal) to represent two similar total soil copper gradients with different pH values. Results showed that free ionic Cu and Cu in saturation extracts were very low in comparison to total Cu contents of study soils (<0.002% and <0.04%, respectively). The concentrations of free ionic copper and of copper in saturation extracts were correlated to total Cu levels and to soil pH. Mean copper concentrations were higher in lettuce than in tomato and onion plants and in vegetables grown on acidic soils of the Cachapoal basin. However, copper levels in edible tissues of tomato and lettuce plants were similar to copper levels described for plants grown on unpolluted soils except for onion bulbs, which had higher values. This indicates that copper translocation to edible, above-ground structures seemed to be well regulated, as their concentrations were fairly constant. The study shows that Cu concentration in study vegetables depends on various factors, including plant species and tissue; site-specific soil factors, such as pH, organic matter, dissolved organic carbon, and conductivity; and several Cu pools, such as total, extractable, and free ionic Cu. Thus, our results support the intensity/capacity concept in that Cu concentration in plants or plant tissues depends not only on the availability of free copper ions in soil solution but also on other soil copper pools that supply the element to the soil solution.

The oxidation of ferrous iron and elemental sulfur by Thiobacillus ferrooxidans that was absorbed and unabsorbed onto the surface of sulfur prills was studied. Unadsorbed sulfur-grown cells oxidized ferrous iron at a rate that was 3 to 7 times slower than that of ferrous iron-grown cells, but sulfur-grown cells were able to reach the oxidation rate of the ferrous iron-adapted cells after only 1.5 generations in a medium containing ferrous iron. Bacteria that were adsorbed to sulfur prills oxidized ferrous iron at a rate similar to that of unadsorbed sulfur-grown bacteria. They also showed the enhancement of ferrous iron oxidation activity in the presence of ferrous iron, even though sulfur continued to be available to the bacteria in this case. An increase in the level of rusticyanin together with the enhancement of the ferrous iron oxidation rate were observed in both sulfur-adsorbed and unadsorbed cells. On the other hand, sulfur oxidation by the adsorbed bacteria was not affected by the presence of ferrous iron in the medium. When bacteria that were adsorbed to sulfur prills were grown at a higher pH (ca. 2.5) in the presence of ferrous iron, they rapidly lost both ferrous iron and sulfur oxidation capacities and became inactive, apparently because of the deposition of a jarosite-like precipitate onto the surface to which they were attached.