The impact of the soil sealing degree on microbial biomass, enzymatic activity, and physicochemical properties in the Ekranic Technosols of Toruń (Poland)

Anna Piotrowska-Długosz,Przemysław Charzyński

doi:10.1007/s11368-014-0963-8

Abstract

Artificial soil sealing in urban areas has attracted increasing attention because of its potential hazard to urban ecosystem. Covering soils with impervious materials has a significant impact on their properties and is essentially an irreversible process. In contrast to natural, open soils, sealed soils undergo a significant alteration of their physicochemical properties, and in turn, negatively influence microbial biomass and enzymatic activity. In general, 33 soils from different parts of the city of Torun (NW Poland) were sampled and divided into 3 groups according to the degree of soil sealing: (1) soils sealed with semi-pervious concrete paving slabs (A), (2) soils sealed with impervious surfaces, such as asphalt and concrete (B), and (3) non-sealed soils (the reference group—C). Soil samples were assayed for (1) microbial biomass carbon (MBC), and nitrogen (MBN) and soil respiration activity (RESP), (2) the activity of soil enzymes, and (3) physicochemical properties. Soil sealing significantly reduced the content of carbon and nitrogen (both total and microbial), soil respiration, the activity of urease, and fluorescein diacetate hydrolysis compared to non-sealed soils (C), while the degree of soil sealing did not significantly affect these properties. Soil moisture and nitrate reductase activity were the only properties significantly differentiated by the degree of soil sealing. Canonical correlation analysis indicated that soil biological activity was caused mainly by the variation in MBC and MBN content, as well as dehydrogenase, catalase, and cellulase activities. The highest correlation was obtained between the soil moisture and the first canonical variable for microbial biomass and enzymatic activity. The results showed that the artificial sealing in urban areas can significantly alter the soils by reducing their carbon and nitrogen content as well as microbial biomass and its activity compared with open soils. The analysis of variance showed that the degree of soil sealing did not affect most of the studied soil properties, although the differences in raw data between impervious and semi-pervious sites were remarkable.

Highlights

Most of the previous studies in soil science have focused mainly on agricultural and forest soils, but there is much stronger interest in urban soils because of the growing urban population (Lorenz and Kandeler 2005)
Soil sealing significantly reduced the content of carbon and nitrogen, soil respiration, the activity of urease, and fluorescein diacetate hydrolysis compared to non-sealed soils (C), while the degree of soil sealing did not significantly affect these properties
The results showed that microbial biomass carbon (MBC) (X1) and microbial biomass-N to NTOT (MBN) (X2) content, as well as DHA (X4), CAT (X5), and cellulase activity (CEL) (X9) activities were the key factors in ME (Eq 1), whereas trends within the first canonical variable for ME were much stronger for MBC (X1) and MBN (X2) than for other properties

Summary

Introduction

Most of the previous studies in soil science have focused mainly on agricultural and forest soils, but there is much stronger interest in urban soils because of the growing urban population (Lorenz and Kandeler 2005). Soil sealing may involve total imperviousness, as caused by concrete or asphalt, or soil may be sealed with semi-pervious surface such as concrete paving slabs, which allow partial penetration of water and air (Nestroy 2006). Most previous studies have focused on effects of sealed areas on water movement (Bhaduri et al 2001; Peffy and Nawaz 2008), gas diffusion (Wiegand and Schott 1999; Kaye et al 2004), and biodiversity (Savard et al 2000), while effects of soil sealing on nutrient cycling and biological components, such as soil microorganisms diversity and enzymatic activity, were seldom investigated (Zhao et al 2012; Wei et al 2013). This, in turn, could negatively influence the microbial and enzymatic activity, since microorganisms are the main source of enzymes in soils

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