Pharmaceuticals inthe groundwater of the informal settlement " Las Fincas" on Cozumel Island, México.

Abstract

The consequences of informal urbanization and the practice of pumping domestic sewage from municipality into deeper zones of the subsoil may result in anthropogenic contamination of groundwater resources by feces and pharmaceuticals on Cozumel Island, Mexico. In order to estimate the extent of this environmental impact there was long term monitoring established in 10 domestic wells in the informal settlement “Las Fincas”. Fecal contamination in all domestic wells indicated leaky septic tanks and the high porosity of the substrate. Water samples were taken in domestic wells and the municipal sewage plant. A combined liquid chromatography and mass spectrometry procedure (HPLC-MS-qToF) was applied in order to detect potential contaminants in water. The analysis was carried out by a suspected-target-screening Letzel et al. [1]. Based on high resolution mass spectra and library search several substances were indicated. In the sample of the sewage plant substances like pharmaceuticals, herbicides and pesticides were detected. This means that these substances are continuously pumped into the aquifer. The actual situation presents a health risk for the inhabitants of “Las Fincas”. Furthermore, the marine environment is in danger which has an extraordinary importance for the tourism-based economy of the island. It is recommended to stop the actual practice of wastewater grouting and replace it by a sustainable concept of wastewater treatment and disposal. Due to the dilution processes in the karstic aquifer together with the limited detection capability of the method none of the substances could be detected in the domestic wells up to now. However, investigations by Metcalfe et al. [2] and Paul et al. [3] prove the disadvantageous impacts on groundwater that results from pumping wastewater in deeper zones of the aquifer. Therefore, the longterm monitoring shall be continued and investigation on groundwater extended to remoter parts of Cozumel.