9Paul J Squillace, Michael J Moran, Wayne W Lapham, et al. Vola- tile organic compounds in untreated ambient groundwater of the United States , 1985 - 1995 [ J].Environ. Sci. Technical. 1999,33 ( 3 ) : 4176 -4157.
10Patrick, R. , Ford, E. , Quarles , J. Groundwater Contamination in the U. S. A. [ J] ;University of Pennsylvania Press: Philadephia, 1987:538.