Disinfection processes are utilized in wastewater treatment with the intent to eliminate microorganisms and improve water quality. However, these treatments may also impact chemicals entering the wastewater system, producing unexpected disinfection byproducts in effluent. This study focuses on parabens, a class of commonly used antimicrobials, and their movement after release as effluent. The goal of this research is to quantify parabens and transformation products in the Brazos River upstream and downstream of wastewater effluent release and also to evaluate concentrations of these products in fish tissues at similar sites. Five parent parabens and nine transformation products were quantified to determine if the release of effluent effects concentrations in river water or fish tissues. The two fish species evaluated were smallmouth buffalo (Ictiobus cyprinellus) and gizzard shad (Dorosoma cepedianum). The four parent parabens analyzed were methyl paraben, ethyl paraben, propyl paraben and butyl paraben. Disinfection byproducts that showed spatial trends include para-hydroxybenzoic acid (PHBA), 3,4-dihydroxybenzoic acid (DHBA), 3,5-dichloro-4-hydroxybenozic acid (Cl2PHBA), methyl 3,5-dichloro-4-hydroxybenzoic acid (Cl2MeP) and ethyl 3,5-dichloro-4-hydroxybenozic acid (Cl2EtP). Compounds were quantified using UPLC-MS. Parent paraben concentrations generally decreased at sites downstram of effluent release. The nearest downstream site had greater concentrations of chlorinated transformation products, with Cl2MeP being present at an average concentration of 8.564 pM (4.997 pM to 14.67 pM) as compared to 0.5831 pM (0.1550 pM to 1.667 pM) at the nearest upstream site. The change in concentration shows an increase in dichlorinated transformation product after effluent release. Concentrations in fish were not significantly different in any parent paraben but did have differences in dichlorinated species between the closest upstream and downstream site, with current Cl2MeP concentrations averaging at 0.2235 pmol/g (0.0422 pmol/g to 1.174 pmol/g) upstream and 0.6011 pmol/g (0.1566 pmol/g to 2.307 pmol/g) at the downstream site for gizzard shad. Smallmouth buffalo had higher Cl2MeP concentrations than gizzard shad downstream at 2.032 pmol/g (0.2776 pmol/g to 12.38 pmol/g) and similar concentrations to gizzard shad at the nearest upstream site 0.4980 pmol/g (0.0865 pmol/g to 2.866 pmol/g)

Evaluating parabens and transformation products in the Brazos river and in fish tissues upstream and downstream of wastewater effluent release

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