Impact of Environmental Factors on the Formation and Development of Biological Soil Crusts in Lime Concrete Materials of Building Facades

Wenxuan Xiong,Yue Tao,Kaiting Wu,Panpan Wang,Lanzhou Chen

doi:10.3390/app12062974

Abstract

Microbial colonization leads to the formation of biological soil crusts (BSCs) on the surface of architecture, which causes the deterioration of construction materials. However, little information is available on the formation of BSCs on lime concrete materials of early architecture. In this study, the variances of microbial communities, physicochemical properties, and surrounding environmental factors of the lime concrete facades from the early architecture of Wuhan University were investigated. It was found that the surface of lime concrete materials was internally porous and permeable, embedded with biofilms of cyanobacteria, mosses, bacteria, and fungi. Redundancy analysis (RDA) analysis showed that the abundances of photoautotrophic microorganisms depended on light intensity and moisture content of construction materials, while that of heterotrophic microorganisms depended on total nitrogen (TN) and NO3−-N content. The deposition of total carbon (TC), NH4+-N, and total organic carbon (TOC) was mainly generated by photoautotrophic microorganisms. The lime concrete surface of early architecture allowed internal growth of microorganisms and excretion of metabolites, which promoted the biodeterioration of lime concrete materials.

Highlights

Ancient and modern cultural heritage structures deteriorate because of variable interactions between physicochemical and biological factors
The total organic carbon (TOC) content of the samples ranged from 1.89 g·kg−1 to 19.4 g·kg−1, with an average of 6.71 g·kg−1
Sample sites Site 4 (S-4) and Site 5 (S-5) had distinct thick biofilms on the structure surfaces, and these biofilms may be related to the high total carbon (TC) and total organic carbon (TOC) levels of the materials

Summary

Introduction

Ancient and modern cultural heritage structures deteriorate because of variable interactions between physicochemical and biological factors. Microbial activities and their effects combined with physicochemical attack are considered central to the deterioration of cultural heritage [1]. Structural damage caused by microorganisms is defined as biodeterioration. The colonization and deterioration processes on matrices are usually induced by heterotrophic microorganisms and photoautotrophic microorganisms, including bacteria, cyanobacteria, algae, fungi, and mosses, the complexes formed by which are usually named biological soil crusts (BSCs) [5,6]. Biodeterioration processes caused by various microorganisms reduce the strength and weights of construction materials, affecting the structural integrity and aesthetic appeal of the cultural heritage structures [10]. There is little information about the biodeterioration of lime concrete materials, especially in the early architecture of China

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Discussion

Conclusion