Effects of heavy metals on the activity of dehydrogenases, phosphatases and urease in naturally and artificially contaminated soils

Abstract

Most of the processes occurring in soil are catalysed by enzymes. As a result of their sensitivity towards heavy metals, enzymes in contaminated soils are usually less active. The purpose of this paper was to assess the influence of bioavailable forms of Cd, Cu, Pb and Zn on the activity of dehydrogenases, urease, acid and alkaline phosphatase, and to compare the results obtained from naturally and artificially contaminated soils. A pot experiment was carried out on two loamy sand soils, naturally and artificially contaminated with Cd, Cu, Pb and Zn. The total content of heavy metals classified these soils as very heavily contaminated with Cu, heavily contaminated with Pb and contaminated with Cd and Zn, all according to the IUNG system (1995). One of the following organic materials: swine manure or triticale straw, was added to the soil batches. The experiment was carried out in three replications, in two pH ranges: slightly acid and acid. Soil samples for analyses were taken after 14, 28, 165 and 450 days of incubation. The results of the experiment showed that the activity of soil enzymes depended on the content of bioavailable heavy metals; the total concentration of trace elements and H + were less important. However, considerable differences were found in enzyme activity between naturally and artificially contaminated soils. This indicates that results obtained from other research conducted on freshly contaminated soils cannot be easily transferred to field conditions. The analysed enzymes responded differently to the concentration of bioavailable forms of heavy metals. Alkaline phosphatase was the least tolerant to bioavailable forms of heavy metals, unlike urease, which was the most tolerant soil enzyme. A similar pattern of sensitivity toward trace elements, which could be ordered as Zn > Cd > Cu > Pb, was noticed for dehydrogenases, acid and alkaline phosphatases. Urease was found to be more tolerant to Zn.

Assessment of the use of sepiolite amendment to restore heavy metal polluted mine soil

“…Although low, significant negative correlations were found between alkaline phosphatase activity values and leachable Zn and Pb contents in mine soil (|R| = 0.88 (p b 0.20) and |R| = 0.85 (p b 0.20), respectively). Similar concentrations of Zn and Cd have been reported to inhibit this enzyme activity to the same levels for most of the different soil texture types subjected to evaluation, whereas some higher concentrations are required in the case of Pb (Doelman and Haanstra, 1989;Wiatrowska et al, 2015). Mine soil Zn and Pb concentrations were about two orders of magnitude higher than those of Cd, indicating the predominant effect of Zn and Pb on this enzyme activity under such conditions.…”

“…The activity of both acid and alkaline phosphatases in soils has been shown to be inhibited by trace elements, including Zn, Pb and Cd (Tyler, 1976;Juma and Tabatabai, 1977;Doelman and Haanstra, 1989;Roy et al, 2004;Wiatrowska et al, 2015). No significant increases (p b 0.05) were produced in acid phosphatase activity after treatment with sepiolite.…”

Assessment of trace elements and its influence on physico-chemical and biological properties in coastal agroecosystem soil, Puducherry region

“…However, trace elements Cr, Zn, Cu, Pb, Co, and As were not show any positive correlation with biological properties. It indicates that Cr, Zn, Cu, Pb, Co, and As trace elements were stronger inhibitory effects on soil biological properties (Wiatrowska, Komisarek, & Dluzewski, 2015).…”

The Influence of Potentially Toxic Elements on Soil Biological and Chemical Properties

“…Wiatrowska et al [72] found that Dehydrogenases, acid and alkaline phosphatases exhibited the highest sensitivity toward Zn and it decreased in the order of metal concentrations: Zn > Cd > Cu > Pb. In contrast, urease was more tolerant to Zn.…”