Spatiotemporal variations in stream and groundwater chemistry and microbial community in an intensive agricultural area

초록

Multivariate analyses including factor analysis (FA) and cluster analysis (CA) were used to evaluate the hydrogeochemical variations in stream and groundwater in an intensive agricultural area in the Haean basin of Korea. In total, 143 stream and groundwater samples were collected from sites with different land uses in August and November 2011 and April, June, and September 2012 during the farming and agricultural off seasons, and analysed for their physicochemical constituents and isotopic compositions. From the FA, four latent factors were identified as being responsible for the physicochemical weathering and anthropogenic influences in the sampled waters. The results of CA revealed four groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the study area. The hyporheic exchange was also measured in August 2011 to investigate hydroecological processes and the flux indicated a strong loss of stream water. The contaminants in stream water derived from agricultural activities were loaded to groundwater through the hyporheic exchange. In addition, pyrosequencing of 16S rRNA analysis were used to evaluate the microbial ecosystem in the hyporheic zone. The bacterial communities acted as a sink for contaminated stream water depending on the flux and microbial community. The study results provide useful information regarding variation in stream and groundwater quality and can aid in the development of effective pollution control and management systems in an intensive agricultural area. © 2016, International Association for Environmental Hydrology. All rights reserved.