Effect of Lead on Soil Enzyme Activities in Two Red Soils

Abstract

Listen

Translate article

Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate (FDA) hydrolysis were measured in two red soils spiked with Pb2+ ranging from 0 to 2 400 mg kg−1 to relate the enzyme activity values to both plant growth and the levels of available and total Pb2+ concentrations in soils, and to examine the potential use of soil enzymes to assess the degrees of Pb contamination. Soil samples were taken for enzyme activities assaying during 3 month's incubation and then after planting of celery (Apium graveolens L.) and Chinese cabbage (Brassica chinensis L.). Enzyme activities in the red soil derived from arenaceous rock (RAR) were generally lower than those in the red soil developed on Quaternary red earths (REQ). At high Pb2+ loadings, in both incubation and greenhouse studies, urease activity and FDA hydrolysis were significantly inhibited. But there were no significant relationships between soil dehydrogenase, acid phosphatase or invertase activity and soil Pb2+ loadings in both RAR and REQ soils. The growth of celery and Chinese cabbage increased soil urease activity and FDA hydrolysis, but had minimal effect on dehydrogenase and invertase activities. There were positive correlations between celery biomass and soil urease activity and FDA hydrolysis. These results demonstrate that urease activity and FDA hydrolysis are more sensitive to Pb2+ than acid phosphatase, dehydrogenase and invertase activities in the RAR and REQ soils.