Partitioning of polycyclic musk compounds in soil and aquatic environment—experimental determination of KDOC

Purpose Polycyclic musk compounds (PMC) are used as fragrances in cosmetics and detergents and enter rivers via domestic wastewater and sewage treatment plants. Soils can be contaminated by PMC through application of sewage sludge. Accumulation of PMC occurs in sediments and biota due to their persistence and lipophilicity. Dissolved organic matter (DOM) is of special relevance for their transport and behavior in the environment as it acts as solubilizer and carrier in aquatic and terrestrial systems. With the distribution coefficient KDOC, one can predict their affinity to DOM. Different approaches exist to determine KDOC, resulting in a range of coefficients for a number of organic pollutants. The objective of this study was to determine KDOC values for PMC using solid-phase microextraction (SPME). Materials and methods A method to determine KDOC was customized and applied to five PMC. Sorption was analyzed using different concentrations of humic acid (HA) solutions and headspace SPME coupled with GC/MS/MS. HA represented DOM. Regarding sorption in soils, sediments, and sewage sludge, a large concentration range of HA solutions up to 660 mg L⁻¹ dissolved organic carbon (DOC) was chosen. Simultaneous determination of all components in a mixture was compared to experiments with single compounds. The method was matched using pyrene. Results and discussion Determined log KDOC values were between 3.32 and 3.67. Compared to experiments with single compounds, determination of the components in a mixture showed no significant difference. Verification experiments with pyrene revealed a close match between KDOC determined in the current study and KDOC literature data. KDOC values of most economical and environmental important PMC 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyrane (HHCB) and 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)-ethanone (AHTN) are comparable to but slightly lower than KOC values recently published. The greater KDOC for AHTN compared to the one of HHCB corresponds to greater amounts found in sediments. The large range in HA concentrations, allows for an assessment of PMC partitioning behavior in sewage treatment plants and soils contaminated with PMC. Conclusions This method is applicable for semi-volatile substances. Since compounds have varying characteristics, this method has to be verified regarding specific parameters particularly kinetics. Suitability of this method should be tested for relevant PMC metabolites and to determine KDOC with natural organic matter from soils, rivers, sediments, and sewage sludge. This adapted method can be used to establish KDOC values for a variety of substances in a short amount of time and is applicable to environmental fate modeling and registration of chemicals.