Natural organic matter (NOM) removal and structural changes in the bacterial community during artificial groundwater recharge with humic lake water.
This study evaluated the removal of natural organic matter (NOM) and structural changes in the microbial community during infiltration of humic lake water at three artificial groundwater recharge (AGR) sites in Finland. The three sites were at waterworks in Hämeenlinna, Jyväskylä and Tuusula, sites A, B and C, respectively. Site A used groundwater recharge by both basin and sprinkling infiltration, site B used only sprinkling infiltration, and site C used only basin infiltration. Reductions of total organic carbon at sites A, B and C were 91%, 84% and 74%, respectively, in the winter, and 88%, 77% and 73%, respectively, in the summer. The Finnish national recommended value of 2 mg/l for TOC was achieved at all sites and the TOC of natural groundwater at site C was much lower, at 0.6 mg/l. Large molecular fractions of NOM were removed more efficiently than the smaller ones. Total amount of DAPI-stained cells decreased during infiltration at sites A, B and C in winter by 94%, 94% and 75% and in summer by 96%, 97% and 94%, respectively. Bacterial communities in raw waters and extracted groundwaters were diverse with changes occurring during infiltration, which was shown by DNA extraction followed by PCR of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE) fingerprinting. While the natural groundwater microbial community was diverse, it was different from that of the extracted groundwater in the AGR area. Simultaneous organic carbon removal and the decrease of bacterial counts during infiltration indicated biodegradation. In addition, the changing DGGE profiles during the process of infiltration, demonstrated that changing environmental conditions were reflected by changes in bacterial community composition.
Kolehmainen
Reija E
RE
Institute of Environmental Engineering and Biotechnology, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere, Finland. reija.kolehmainen@tut.fi
Langwaldt
Jörg H
JH
Puhakka
Jaakko A
JA
D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification; D002244:Carbon / Q000032:analysis; D015169:Colony Count, Microbial; D005387:Finland; D005618:Fresh Water / Q000032:analysis / Q000382:microbiology; D006812:Humic Substances; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012621:Seasons; D014871:Water Microbiology; D014873:Water Pollutants / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
D006812:Humic Substances; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014873:Water Pollutants; D002244:Carbon