POTENTIAL FOR 4-n-NONYLPHENOL BIODEGRADATION IN STREAM SEDIMENTS

Abstract

The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring-14 C]4-n-nonylphenol (4-n-NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfalls and incubated under oxic conditions showed rapid and complete mineralization of [U-ring-14 C]4n-NP to 14 CO 2 in all three systems. In contrast, no mineralization of [U-ring-14 C]4-n-NP was observed in these sediments under anoxic (methanogenic) conditions. The initial linear rate of [U-ring-14 C]4-n-NP mineralization in sediments from upstream and downstream of the respective WWTP outfalls was inversely correlated with the biochemical oxygen demand (BOD) of the streambed sediments. These results suggest that the net supply of dissolved oxygen to streambed sediments is a key determinant of the rate and extent of 4-NP biodegradation in stream systems. In the stream systems considered by the present study, dissolved oxygen concentrations in the overlying water column (8-10 mg/L) and in the bed sediment pore water (1-3 mg/L at a depth of 10 cm below the sediment-water interface) were consistent with active in situ 4-NP biodegradation. These results suggest WWTP procedures that maximize the delivery of dissolved oxygen while minimizing the release of BOD to stream receptors favor efficient biodegradation of 4-NP contaminants in wastewater-impacted stream environments.

Managing the Effects of Endocrine Disrupting Chemicals in Wastewater-Impacted Streams

“…Extending this experience to EDC, the efficiency of environmental EDC biodegradation would be expected to be greatest under oxic conditions and severely limited under anoxic conditions. The results of a recent assessment of the potential for 4-n-NP biodegradation in stream sediments are consistent with this expectation [63]. While substantial mineralization of 14 C-4-n-NP was observed in sediment microcosms incubated under oxic conditions, the rate of mineralization under oxic conditions was inversely related to the sediment biological oxygen demand (BOD)( Fig.…”

“…The potential for EDC biodegradation was assessed in microcosms using 14 C-radiolabeled model compounds [see for example, 46,63] representing the two general classes of EDC: endocrine hormones and endocrine mimics. Each 14 C-model contaminant compound contained a cyclic (aromatic) ring structure that is considered essential to compound toxicity and biological activity.…”

“…Each 14 C-model contaminant compound contained a cyclic (aromatic) ring structure that is considered essential to compound toxicity and biological activity. Consequently, the 14 C-radiolabel of each model contaminant was positioned within the aromatic ring such that recovery of 14 C-radioactivity as mineralization products ( 14 CO 2 and/or 14 CH 4 ) indicated ring cleavage and presumptive loss of endocrine activity [see for example, 46,63].…”

“…While substantial mineralization of 14 C-4-n-NP was observed in sediment microcosms incubated under oxic conditions, the rate of mineralization under oxic conditions was inversely related to the sediment biological oxygen demand (BOD)( Fig. 5) and no evidence of mineralization was observed under anoxic conditions [63].…”

Fate of 4-Nonylphenol and 17β-Estradiol in the Redwood River of Minnesota

“…12,63,64 A primary removal mechanism for 4-nonylphenol is sorption to bed sediments and stream biofilms. 54,55,63,64 Although attenuation of 4-nonylphenol can occur by the previously described mechanisms, it also can be produced by biodegradation of other 4-nonylphenol-containing degradation products (4-NPEO and 4-NPEC).…”