Interdisciplinary Lecture by Prof. Jidong Gu (GTIIT Env)

Title

Protection of the Old Angkor Sandstone Monuments in Cambodia

Speaker

Prof. Jidong Gu (GTIIT, Env)

Host

Prof. Yigal Achmon  (GTIIT, BFE)

Date & Time

Apr. 28 2022, Thursday, 11:00am-12:00pm

Location

E501 (Education Building, 5th floor)

Language

English

Pizza served after the lecture

Abstract

Sandstone monuments/temples of the Angkor Empire in the Southeast Asia are important UNESCO World Cultural Heritage, but they suffer severe deterioration from weathering caused by a combination of physical, chemical and (micro)biological processes under the tropical conditions over time. In this talk, I will focus on both the water holding issue in sandstone and also the recent discovery on high concentration of nitrate accumulated and the possible causes on these monuments. A conceptual framework is proposed to explain the nitrate accumulation phenomenon by multiple groups of microorganisms including ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), the complete ammonia oxidation (Comammox) bacteria, and dissimilatory nitrate reduction to ammonium (DNRA) bacteria. At the same time, nitrogen-15 stable isotope was used and analyzed to delineate a cyclic reaction between ammonium/ammonia and nitrate to promote the colonization by a diverse group of microorganisms to modify the surface properties of stone over time. Additional metagenomics and transcriptomics coupling with stable isotope N-15 analysis reveal further insights on the biochemical reactions involved on surfaces of these sandstone monuments. The fundamental information of the microbial community colonized on surfaces and their biochemical reactions is useful for protection and management of the cultural heritage.

Keywords: Angkor temples; sandstone; cultural heritage; biofilms; salting; defoliation; capillary action; secondary mineral formation

Bio

Ji-Dong received his BSc degree from Heilongjiang August First Land Reclamation University (P.R. China), MSc degree from University of Alberta (Canada), and PhD degree from Virginia Tech (USA). He worked in the Microbial Ecology Laboratory of Harvard University between 1993 and 1998 and then joined The University of Hong Kong in 1999 as an assistant professor and then in 2004 promoted to associate professor. He takes the current position with Guangdong Technion Israel Institute of Technology in the summer of 2020. He is the Editor-in-Chief for International Biodeterioration & Biodegradation, and an Associate Editor for Ecotoxicology, and Journal of Polymers and the Environment.