A nonadsorbing (conservative) tracer (chloride) was injected into an unconfined, homogeneous, groundwater aquifer along with two adsorbing organic compounds: carbon tetrachloride and tetrachloroethylene. A test well 5 m downstream from the injection well was monitored for all three compounds. The average time of arrival (breakthrough time) at the monitoring well was 66 days for chloride ion, 120 days for carbon tetra chloride, and 217 days for tetrachloroethylene.

1) Obtain retardation factors for carbon tetrachloride ad tetrachloroethylene.

2) Determine Kd values for carbon tetrachloride and tetrachloroethylene.

3) For carbon tetrachloride only, compare the Kd values you obtained in part B with the value you get using a LFER by Curtis et al. and discuss potential causes for any differences you find. Log Koc = 0.92log Kow - 0.23