Impacts of rural and urban sources on a tropical semiarid region (Acaraú River, Ceará, Brazil): sedimentary sterols and endocrine-disrupting compounds as anthropogenic molecular markers

Abstract Semiarid regions are unique, and in Northeast Brazil, estuarine basins are often impacted by human occupation, resulting in the input of chemicals. The objective of this study was to evaluate the contributions of urban and rural activities to the environmental quality of the Acaraú River, using molecular markers in superficial sediments. Concentrations of total sterols and hormones varied between 271.5 to 2525 ng g⁻¹ and 139.8 to 1728 ng g⁻¹, respectively. Fecal sterol coprostanol ranged from 6 to 124.1 ng g⁻¹. Concentrations of synthetic hormones were detected at one order of magnitude higher than those of natural hormones, and the diagnostic ratios for sterols, hormones, and coprostanol suggest sewage discharge and fecal contamination in the Aracaú River Basin. Activities such as fish and shrimp farming, which involve the use of drugs for animal handling, may also be relevant sources in the region. Regarding the ecological risks of toxicity, 17α-ethinylestradiol, mestranol, and estrone are compounds of environmental concern in the Acarú River, requiring actions to reduce or eliminate their sources.