Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2006
Publication Date: 10/1/2006
Citation: Ibekwe, A.M. 2006. Impact of plant density and microbial composition on water quality from a free water surface constructed wetland. American Society of Agronomy Abstracts, annual meeting, Salt Lake City, UT. [CD-ROM]
Technical Abstract: The Prado Wetlands in Chino, CA is a free water surface (FWS) constructed wetland consisting of 50 shallow ponds that treats approximately 50% of Santa Ana River water prior to its passage to Orange County, CA where it is used for groundwater recharge. The main function of Prado Wetlands has been the removal of nitrate-nitrogen. The method of removal is a combination of microbial and plant processes. This study was conducted to understand the changes in water chemistry and microbial composition of the wetlands as affected by different concentrations of plants per wetland pond. Community profile using DGGE of total DNA was used to determine the major microbial composition in different sections of the wetland. Bacterial populations associated with the wetland sediment, rhizosphere, and surface water were characterized by cloned 16S rRNA gene sequence analysis. Bacterial rRNA gene libraries were constructed, and 300 clones were analyzed by amplified ribosomal DNA restriction analysis and grouped into operational taxonomic units (OTUs). A total of 35, 31, and 36 different OTUs were obtained from soil, rhizosphere, and surface water, respectively. The most dominant group of our clone library was allocated to an unidentified bacterium followed by the phylum Proteobacteria. The dominant organisms within the class were in the gamma, beta, and delta classes. There was a substantial fluctuation in nitrate and orthophosphate levels throughout the summer and fall. The ponds with 50% plant cover had as high as 99% nitrate removal. The average change between the influent and effluent was 50-60% nitrate removal and 40-50% orthophosphate removal. .