| Institution: | (1) Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, 305-8569 Tsukuba, Japan;(2) Department of Aquatic Bioscience, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, 113-8657 Tokyo, Japan;(3) Center for Water Environment Studies, Ibaraki University, 1375 Taisei, Itako, 311-2402 Ibaraki, Japan;(4) Geoscience Co. Ltd., 6-1-1 Ueno, Taito, 110 Tokyo, Japan |
| Abstract: | Groundwater from a shallow aquifer in Mobara, a city in a natural gas field in Chiba Prefecture, Japan, was found to contain a significant amount of dissolved methane (<3.1 mM) along with nitrate, phosphate and methane-oxidizing bacteria (methanotrophs, <9.9×106 MPN ml–1) which can degrade trichloroethylene (TCE). This water exhibited high methanotroph growth activity and rapid degradation of TCE. This water was introduced into a TCE-contaminated aquifer. The concentration of TCE at the monitoring well 2 m down-gradient of the injection pit decreased from 128  g L–1 before the injection to less than the lower detection limit of 12.5 g L–1 after the injection, while it decreased only slightly (to 86 g L–1) when control water was injected. These results demonstrate the feasibility of utilizing a natural groundwater resource containing methane and methanotrophs without any additives for bioremediation of a TCE-contaminated site. |
