Fate of nutrients in shallow groundwater receiving treated septage, Malibu, CA.

ABSTRACT: Treated wastewater discharged from more than 400 onsite wastewater treatment systems (OWTS) near the Civic Center area of Malibu, California, 40 km west of downtown Los Angeles, composes 28% of the recharge to a 3.4 km(2) alluvial aquifer. On the basis of δ(18) O and δD data, the fraction of wastewater in some samples was >70%. Ammonium and nitrate concentrations in water from 15 water-table wells sampled in July 2009 and April 2010 ranged from <0.01 to 12 milligrams per liter as nitrogen (mg/L as N), and from <0.01 to 11 mg/L as N, respectively. Chemical and isotopic data (δ(15) N of ammonium and nitrate, and δ(18) O of nitrate) show two processes remove nitrogen discharged from OWTS. Where groundwater was reducing, sorption of ammonium resulted in 30 to 50% nitrogen removal. Where ground

SUBMITTER: Izbicki JA 

PROVIDER: S-EPMC4265202 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature