LEVELS OF ACTIVITIES OF SOME CARBOHYDRASES, PROTEASE, LIPASE, AND PHOSPHATASE IN ORGANIC SOILS OF DIFFERING COPPER CONTENT

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Abstract
Representative pairs of muck and peat (sapric and hemic Histosol) samples were collected from a mildly cupriferous virgin bog under a normal mixed forest flora near Sackville, New Brunswick, Canada. Samples within each pair were similar in their physical and chemical properties, except for their Cu contents, in which they have varied widely for a long time. In agreement with the evidence of the mitigating effect of Cu on decomposition, already in the literature, a muck (sapric) sample containing 2922 ppm of total Cu lost C through aerobic soil respiration at half the rate of a muck sample containing 1159 ppm Cu. Similarly, the soil respiration rate of the peat (hemic) sample containing 797 ppm Cu was half that of the peat sample with 408 ppm Cu. Within each pair of samples, which were air-dried following a 6 wk incubation, C1-cellulase, Cx-cellulase, cellobiase, xylanase, chitinase, lichenase, inulase, pectinase, amylase, invertase, lactase, maltase, lipase, protease and acid phosphatase enzyme activities were all lower in samples containing higher Cu. Enzyme activities were decreased on an average by 79 .+-. 10.5 percent and 66.2 .+-. 7.1%, apparently due to the natural increments of the Cu contents of the muck and peat samples, respectively. Assays of invertase, amylase, phosphatase and protease activities in moist soil samples incubated at 21.degree. C for 368 days indicated that, as expected, the mitigating effect of Cu on degradative activities of the enzymes functioned in microbially active soils also. The suppressive effect of Cu on levels of accumulated enzyme activities noted earlier in soils that contained increased concentrations of Cu for only a decade or two, in fact prevails for a long time and may be useful in mitigating the decomposition, and therefore the subsidence of some Histosols. Due to the greater abundance of substrates in organic soils, accumulated degradative soil enzymes probably play a more important role there than in mineral soils and contribute to the decomposition and subsidence of some Histosols.