so4<-tacoma[,1]
year<-tacoma[,2]
year<-factor(year)
station<-tacoma[,3]
station<-factor(station)
tacoma.frame<-data.frame(so4=so4,year=year,station=station)
tacoma.aov<-aov(so4~year*station, data=tacoma)
summary.lm(tacoma.aov)