Multi-tracer use to assess groundwater contamination after land-use changes

Abstract:

Land-use modifications from agricultural to protected areas does not guarantee the reduction of agricultural contaminants in groundwater, even after several years since such changes. Many contaminants tend to be persistent and have long lives, making difficult to have any plausible explanation on why high concentrations are still present if recharge sources of contaminants have been completely eliminated. Natural attenuation is helpful to reduce harmful concentrations of contaminants to desirable levels but requires long periods of time, especially with some types of contaminants. In order to understand how contamination is interacting with groundwater and how long will it take to have lower (or desirable) levels of the concentrations from contaminants, it is important to understand groundwater dynamics, particularly mean residence times of water in relation to contamination. A multi-tracer study may support this understanding by giving a measurable and enough evidence on how both, groundwater and contaminants interact and react to recharge and discharge and to estimate how long will it take for natural attenuation to reduce contamination until concentrations are considered not harmfull for health.