Short-term spatio-temporal changes in urban pollution by means of faecal sterols analysis

Changes in the spatial and temporal distribution of faecal sterols in sediments of the Bilbao Estuary, one of the most densely urbanized areas on the Atlantic coast of Spain, have been investigated. The results indicate elevated concentrations of faecal sterols, including coprostanol, in surface sediments throughout the estuary. Highest concentrations are associated with two major point sources within the estuary, where up to 293 μg−1 of coprostanol were measured. On the other hand, temporal patterns in faecal sterols concentrations are presumably related to weather conditions at the time of the sampling, implying that more samples are required for a meaningful record of the actual variation of sewage contaminated sediments. This study provides baseline data for future examination of the efficacy of the ongoing sewerage plan promoted by the Local Water Authority.