Exploring the use of synthetic musk fragrances as tracers of wastewater discharges in surface waters

Traces of almost all the substances consumed by humans or released by anthropic and industrial activities end up in the environment and if measured in the different environmental compartments can give some information on their sources. The need for determining the contribution of the different sources of contamination in a polluted and urbanized area in Northern Italy drove us to search for tracers of specific sources in order to find a quantitative correlation with specific human activities. Anthropogenic compounds previously suggested as potential wastewater indicators include artificial sweeteners, persistent drugs, and personal care products. Since each of these tracers has different uses, human metabolism and transformation pathways in natural systems or in treatment plants, the simultaneous analysis of different tracers with their metabolites and transformation products under different hydrological and precipitation regimes can be a powerful mean to assess the relative contribution of different sources and processes. In the framework of a wider project aimed to compare different urban tracers, we developed and tested an Isotope Dilution GC-MS method for the analysis of synthetic musk fragrances in waste and surface waters. Synthetic musks are widely used as fragrances additives in many consumer products, they are widely present in the environment and they tend to accumulate in sediment, sludge and biota. The method, validated taking carefully into account the problem of blank contamination, allows to determine 9 compounds, including nitro-, polycyclic-, macrocyclic musks and a transformation product (galaxolide lactone), which can be a specific tracer of WWTP discharge. The occurrence of this class of substances has been evaluated in the river Po basin, which is an area with a very high pressure from population, industry and intensive agriculture, through specific campaigns that will be designed to evaluate their suitability as markers of anthropic pollution. Treated wastewater from wastewater treatment plants of Milano and Monza, surface waters (River Lambro and Lambro Meridionale) and irrigation waters has been included in the analytical campaign to assess the overall mass balance of the selected tracers.