Humberto Aponte1, Paula Meli2, Benjamin Butler3, Jorge Paolini4, Francisco Matus5, Carolina Merino5, Pablo Cornejo6, Yakov Kuzyakov7. 1. Doctoral Program in Sciences of Natural Resources, Universidad de La Frontera, Temuco, Chile; Centro de Investigación en Micorrizas y Sustentabilidad Agroambiental, Universidad de La Frontera, Temuco, Chile. 2. Landscape Ecology and Conservation Laboratory, Departamento de Ciencias Forestales, Universidad de La Frontera, Temuco, Chile. 3. The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK. 4. Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), Venezuela. 5. Laboratory of Conservation and Dynamic of Volcanic Soils, Department of Chemical Sciences and Natural Resources, Universidad de La Frontera, Temuco, Chile; Network for Extreme Environmental Research, Universidad de la Frontera, Temuco, Chile. 6. Centro de Investigación en Micorrizas y Sustentabilidad Agroambiental, Universidad de La Frontera, Temuco, Chile. Electronic address: pablo.cornejo@ufrontera.cl. 7. Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Goettingen, 37077 Goettingen, Germany; Agro-Technological Institute, RUDN University, 117198 Moscow, Russia; Institute of Environmental Sciences, Kazan Federal University, 420049 Kazan, Russia.
Abstract
Enzyme activities (EAs) respond to contamination in several ways depending on the chemical form and content of heavy metals and metalloids (HMs) and their interactions with various soil properties. A systematic and mechanistic understanding of EA responses to HM contamination in soil is necessary for predicting the consequences for nutrient availability and the cycling of carbon (C), nitrogen (N), phosphorus (P) and sulphur (S). In this study, a meta-analysis based on 671 observations found the activities of seven enzymes to decrease in response to soil contamination with Pb, Zn, Cd, Cu and As. HM contamination linearly reduced the activities of all enzymes in the following order: arylsulfatase > dehydrogenase > β-glucosidase > urease > acid phosphatase > alkaline phosphatase > catalase. The activities of two endoenzymes: arylsulfatase (partly as exoenzyme) and dehydrogenase were reduced by 72% and 64%, respectively. These reductions were two times greater than of exoenzymes: β-glucosidase, urease, acid phosphatase, alkaline phosphatase and catalase (partly endoenzyme). This reflects the much stronger impact of HMs on living microorganisms and their endoenzymes than on extracellular enzymes stabilized on clay minerals and organic matter. Increasing clay content weakened the negative effects of HM contamination on EAs. All negative effects of HMs on EAs decreased with soil depth because HMs remain mainly in the topsoil. EAs involved in the cycling of C and S were more affected by HMs than the enzymes associated with the cycling of N and P. Consequently, HM contamination may alter the stoichiometry of C, N, P and S released by enzymatic decomposition of organic compounds that consequently affect microbial community structure and activity.
Enzyme activities (n class="Chemical">EAs) respond to contaminationpan> in several ways depenpan>ding onpan> the chemical form and conpan>tenpan>t of heavy metals and metalloids (HMs) and their interactions with various soil properties. A systematic and mechanistic understanding of EA responses to HM contamination in soil is necessary for predicting the consequences for nutrient availability and the cycling of carbon (C), nitrogen (N), phosphorus (P) and sulphur (S). In this study, a meta-analysis based on 671 observations found the activities of seven enzymes to decrease in response to soil contamination with Pb, Zn, Cd, Cu and As. HM contamination linearly reduced the activities of all enzymes in the following order: arylsulfatase > dehydrogenase > β-glucosidase > urease > acid phosphatase > alkaline phosphatase > catalase. The activities of two endoenzymes: arylsulfatase (partly as exoenzyme) and dehydrogenase were reduced by 72% and 64%, respectively. These reductions were two times greater than of exoenzymes: β-glucosidase, urease, acid phosphatase, alkaline phosphatase and catalase (partly endoenzyme). This reflects the much stronger impact of HMs on living microorganisms and their endoenzymes than on extracellular enzymes stabilized on clay minerals and organic matter. Increasing clay content weakened the negative effects of HM contamination on EAs. All negative effects of HMs on EAs decreased with soil depth because HMs remain mainly in the topsoil. EAs involved in the cycling of C and S were more affected by HMs than the enzymes associated with the cycling of N and P. Consequently, HM contamination may alter the stoichiometry of C, N, P and S released by enzymatic decomposition of organic compounds that consequently affect microbial community structure and activity.
Authors: Nontobeko Gloria Maphuhla; Francis Bayo Lewu; Opeoluwa Oyehan Oyedeji Journal: Int J Environ Res Public Health Date: 2022-09-23 Impact factor: 4.614