Biodegradation of the herbicides 2,4‐dichlorophenoxyacetic acid, 2,4,5‐trichlorophenoxyacetic acid, and 2‐methyl‐4‐chlorophenoxyacetic acid in a sulfate‐reducing aquifer

Biodegradation of trace organic compounds is one of the main mechanisms to purify infiltrating surface water during bankfiltration and underground passage. In anaerobic zones of the underground, rate and extent of degrading processes may be totally different from those in aerobic ones. To investigate this, a model ecosystem was built that reproduces an anaerobic part of the aquifer and the behavior of the three phenoxyacetic acid herbicides 2,4‐dichlorophenoxyacetic acid, (2,4‐D), 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), and 2‐Methyl‐4‐chlorophenoxyacetic acid (MCPA) tested. In anaerobic experiments with varying conditions they proved to be almost persistent. Only under aerobic conditions could biodegradation be observed after a lag period.