ABSTRACT
This creates an opportunity for in situ remediation practitioners. However, unlike organic contaminants, metals cannot be destroyed or their recovery easily enhanced. Instead, active and passive in situ remedial strategies for the treatment of metals in groundwater generally involve direct precipitation or sorption/coprecipitation, with the goal of permanently sequestering and immobilizing the metals in the aquifer soil matrix. Therefore, the end result is a reduction in the groundwater concentrations, but the actual metals remain in situ. The success of precipitation-based in situ treatment approaches is dependent upon the following:
Kinetics: The ability to support meaningful rates of precipitation is a minimum threshold that must be met. If the reaction is thermodynamically spontaneous (i.e., requires no energy to occur) but the rate is too slow, the approach will have limited usefulness. The relationship of kinetics and thermodynamics is discussed in Chapter 6.
