The role of urban wetland diversity and function in contaminant fate

Abstract

It is recognized that microbial transformations are the primary mechanism of organic contaminant removal in natural and constructed wetland systems. However, not much is known about urban wetland microbial communities or their functional capacity to process contaminants. The objective of this research was to first characterize the physiological and phylogenetic diversity of microbial communities of different urban wetland types using the BIOLOG™ method and through DGGE of 16S rRNA sequences. The capacity of urban wetlands to attenuate model chlorinated aromatic compounds (2,4-D and 3-CBA) was assessed by UPLC biodegradation and 14C mineralization experiments. Toxicity tests were conducted to assess microbial tolerance to pollutant addition. In general, results indicate that urbanization has a homogenizing effect on microbial community structure and distribution within urban wetland systems, regardless of type. Urban wetlands also appear to have a limited capacity to remove chlorinated organic pollutants. Microbial community tolerance to chlorinated organic pollutants is relatively high, whereas heavy metal tolerance was found to coincide with history of contaminant exposure.