The Impact of Dairy Farms on the Groundwater Quality of Israel?s Coastal Aquifer
Ben Gurion University
Concentrated animal feeding operations (CAFOs), such as dairy farming, have been repeatedly found to impair underlying groundwater quality. Little is known about the impact of dairy farms on Israel's groundwater quality, even though the overall pollutants mass generated by the dairies equals that of the entire population. Nevertheless, the dairy farming industry was recently reformed in order to minimize liquid waste (including manure, feces, water from washing shades and cooling water) and contaminated runoff from reaching the environment. The objective of this work is to assess the direct impact of dairy farms on the quality of groundwater recharge in Israel's phreatic Coastal Aquifer at its most intensive dairy farming area. Groundwater observation wells and unique vadose-zone monitoring systems (VMSs) that enable monitoring of the temporal variation in the sediment's water content along with continuous sampling of the sediment's pore water in deep sections of the vadose zone were installed in a representative dairy farm. Results from 3 years of continuous monitoring showed that unlined dairy farm waste lagoons are point sources for highly concentrated solutions recharging the aquifer (~4000 mg L-1 chloride and ~700 mg L-1 nitrate). Overflows from the waste lagoon as well as local runoff during high intensity rain events, preferentially infiltrate into desiccation cracks around the dairy farms. This process accelerates groundwater contamination since it rapidly transports contaminants and salts (such as nitrate, testosterone and estrogen) into the deep sections of the vadose zone (>10m) bypassing the sediment's most bio-geo-active parts. The VMS is shown to be an effective tool for continuous long-term monitoring of contaminant transport along the vadose zone as well as for assessments of natural attenuation and early detection of pollutants in the vadose zone.