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The effects of conventional, bole only harvesting (CH) and whole-tree harvesting (WTH) on major inorganic nutrient concentrations (K, NO3-N, NH4-N, PO4-P and Ca) in soil water are described from Beddgelert forest in North Wales. Monitoring of nutrient leaching losses, and the timing thereof, from brash through the soil and into streams draining the CH areas allowed assessments to be made of the value of brash as a nutrient source for second rotation crops. Most of the K (around 100 kg ha-1) and one-third of the P (10 out of 30 kg ha-1) leached out of the brash lying on the CH plots within one year of felling. A pulse of K passed through the soil profile, but less than half this K reached the streams. In contrast, the P was immobilized in the soil. The lack of brash resulted in the absence of K and P pulses on the WTH plots. On the CH plots, brash was a net sink for inorganic-N for 3 years after felling. However, in both CH and WTH, a pulse of nitrate was observed in the soil and also in streams draining CH areas. The source of this nitrate may have been death of fine tree roots, followed by rapid mineralization and nitrification. Calculation of a nutrient budget for a complete crop rotation indicates that P and Ca losses in harvested material are likely to result in long-term depletion of these elements, and that the effects will be significantly more severe if WTH is practised.

External carbonic anhydrase (CA) was detected in whole cells of alkaline-grown Chlorella saccharophila but was suppressed by growth at acid pH or growth on elevated levels of CO2. Internal CA activity was measured potentiometrically as an increase in activity in cell extracts over that of intact cells. Cells grown under all conditions had equal levels of internal CA activity. Two isozymes were identified after electrophoretic separation of soluble proteins on cellulose acetate plates. The fast isozyme was found in cells grown under all conditions, whereas the slow isozyme was found only in cells grown at alkaline pH. Western blot analysis following sodium dodecyl sulfate-polyacrylamide gel electrophoresis using antibodies produced against the periplasmic form of CA from Chlamydomonas reinhardtii revealed a single band at 39 kD, which did not change in intensity between growth conditions and was associated only with proteins eluted from the fast band. The slow isozyme was inactivated by incubation of cell extract at 30[deg]C and by incubation in 10 mM dithiothreitol, whereas the internal form was unaffected. These results indicate that external and internal forms of CA differ in structure and their activities respond differently to environmental conditions.