Assessment of streams and aquatic organisms in the vicinity of Birmingham, Alabama for the presence and biological activity of endocrine-disrupting chemicals.

摘要

Freshwater ecosystems play a central role in the environment. Through various processes such as nutrient recycling, groundwater recharging, and the attenuation of many pollutants these biological systems help to maintain environmental health. Unfortunately, many recent studies have identified emerging threats to these special environments and the life they sustain. One source of mounting concern is a group of compounds that interact with the endocrine systems of humans and wildlife. Known as endocrine disrupting chemicals (EDCs), these natural and synthetic chemicals may mimic or interfere with the action of natural hormones---thus disrupting the endocrine system. Multiple studies have reported negative effects associated with EDCs on both the health of humans and wildlife; however more information is needed on the reproductive effects that EDCs may pose to wildlife, in particular fish inhabiting these freshwater ecosystems. Fish serve as a useful indicator of the health of an aquatic ecosystem. To this end, the scope of the current investigation provides an integrated approach in assessing the streams and aquatic organisms in the vicinity of Birmingham, Alabama for the presence and biological activity of EDCs. It follows a preliminary study conducted at several sites along the Cahaba River in which a yeast estrogen screen (YES) detected sufficient estrogenicity in water samples to imply the possible feminization of fish. Repeated samples were collected between 2012 and 2013 providing an assessment to the extent of seasonal and annual variation in estrogenic activity. Using the same YES assay as employed previously, it was determined that water samples collected at several wastewater treatment plant (WWTPs) outfalls contained estrogenic components in concentrations sufficient to cause endocrine disruption in aquatic organisms. Water samples were further analyzed using tandem liquid chromatograph/mass spectrometry and the predominant estrogenic components identified. At WWTPs where habitats were suitable, specimens of largescale stoneroller ( Campostoma oligolepis) were collected and biomarkers of endocrine disruption evaluated. Such biomarkers included the presence of intersex, reduced gonad size in males and/or females, and reduced secondary sex characteristics within males. In each study described within this dissertation, chemical and biological evidence suggests that environmental estrogens were present at low-level concentrations during the sampling window represented here. Environmental estrogens detected in water samples from the WWTPs investigated illustrated non-significant seasonal influence of environmental concentration. Neither LC/MS nor the YES assay detected significant estrogen loading into receiving bodies of water via wastewater effluent. Additionally, biomarkers for endocrine disruption evaluated within C. oligolepis failed to detect significant differences in either histology or morphology between WWTP present and WWTP absent sites. We conclude that the WWTPs assessed in this study are not currently contributing environmental estrogens to the receiving waters in concentrations sufficient to produce discernible effects upon the fish populations within Jefferson County, Alabama; this is primarily due to their presence at low-level concentrations and intermittent persistence within receiving bodies of water.