Effects of Trace Elements on Phosphatase Activity in Soils

Abstract

Studies to evaluate the effects on the activity of acid and alkaline phosphatases of 20 trace elements showed that all trace elements inhibit the activity of phosphatases in soils. Results showed that the relative effectiveness of the trace elements in inhibition of phosphatase activity depends on the soil. When the trace elements were compared by using 25 µmole/g soil, the average inhibition of acid phosphatase in three soils showed that Hg(II), As (V), W(VI), and Mo(VI) were the most effective (average inhibition >50%) and that Ba(II), Co(II), and As(III) were the least effective (average inhibition <10%) inhibitors. Other elements that inhibited acid phosphatase activity in soils were: Cu(I), Ag(I), Cd(II), Cu(II), Zn(II), Mn(II), Sn(II), Ni(II), Pb(II), Fe(II), Cr(III), Fe(III), B(III), Al(III), V(IV), and Se(IV); their degrees of effectiveness varied in the three soils used.The most effective inhibitors of alkaline phosphatase activity in soils were Ag(I), Cd(II), V(IV), and As(V). All the trace elements that inhibited acid phosphatase activity also inhibited alkaline phosphatase activity. The order of effectiveness of the trace elements in inhibition of acid phosphatase activity was different from that of inhibition of alkaline phosphatase activity. Generally, the inhibitory effect of trace elements was less in the presence of 2.5 µmole/g soil than in the presence of 25 µmole/g soil. In addition to the effect of trace elements, phosphate ion inhibited acid and alkaline phosphatase activities in soils. Related anions such as NO2‐, NO3‐, Cl‐, and SO42‐ were not inhibitory in the presence and absence of buffer.

A Modified Molybdenum Blue Method for Orthophosphate Determination Suitable for Investigating Enzymatic Hydrolysis of Organic Phosphates

“…When one-half, one-fourth, and one-eighth diluted extracts (i.e., 10-2.6 mg P i mL 21 of the reaction mixture) were incubated, respectively, with the combination of acid phosphatases from potato and wheat germ and nuclease P1 (0.25, 0.25, and 4.0 U mL 21 of reaction mixture, respectively) for 1 h at 378C, the P i determined was 1587 + 80, 1585 + 78, and 1536 + 59 mg kg 21 DM (average + standard deviation). Although P i and other metal elements could inhibit the phosphatases activities (Dick and Tabatabai 1984;Juma and Tabatabai 1977), no substantial difference in P o concentrations indicated their levels in manure extracts did not affect completeness of P o hydrolysis.…”

Effect of recycling wood ash on microbiological and biochemical properties of soils

“…It is well established that phosphatase activity depends on available P (Perucci, 1992;Nannipieri, 1994;Juma and Tabatabai, 1997). Effect of recycling wood ash on microbiological and biochemical properties of soils 161 WA addition increases alkaline phosphatase activity (Fig.…”

Toxicological benchmarks for screening potential contaminants of concern for effects on soil and litter invertebrates and heterotrophic process

“…It is possible that activity in this soil would have been inhibited to a somewhat lesser degree by 240 ppm Mo, as it was in the two remaining soils. Juma and Tabatabai (1977) used the system described for Al to evaluate the effect of Mo on soil acid and alkaline phosphatase activities. Acid phosphatase activity in all three soils was reduced at 2398 ppm.…”

“…Some metal ions may inhibit enzyme reactions by complexing with enzyme substrates, combining with the protein active group of the enzyme, or reacting with the enzyme-substrate complex (Juma and Tabatabai, 1977).…”