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Particle-associated organic contaminant and cytotoxicity transport in a river during storm events
Ist Teil von
Journal of hydrology (Amsterdam), 2023-06, Vol.621, p.129600, Article 129600
Ort / Verlag
Elsevier B.V
Erscheinungsjahr
2023
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
•Total suspended solids correlated linearly with PAHs and musk fragrances in a river during a storm event.•Total concentrations of hydrophobic compounds and their cytotoxicity increased with increasing total suspended solids.•Cytotoxicity per mass of particles and volume of water remained stable throughout storm events.
Storm events lead to mobilization of particles as well as organic contaminants that can pose a risk to river ecosystems. Assessment of total loads of particle-bound and dissolved contaminants in rivers is challenging, especially during rain events since multiple, often unknown contamination sources may be triggered, among them tributaries, combined sewer overflows, direct soil and road runoff, and the riverbed sediment. We investigated whether cytotoxicity (i.e., reduction of the cell viability of human cell lines) could be used as a proxy for the total chemical mixture to assess the transport of organic contaminant mixtures either in particle-associated form or in the aqueous phase. Time-proportional composite samples were collected in the Ammer River (Southwestern Germany) during two storm events in June 2021. All samples were screened for 127 organic contaminants and cytotoxicity in the water and particle phase separately. In total, 56 organic compounds were found, of which 14 and 34 were detected only in the water and particle extracts, respectively, and eight compounds were present in both phases. Thermodynamic equilibrium between the aqueous phase and suspended solids was observed for four compounds namely triphenyl phosphate, octocrylene, galaxolide, and p-chlorocresol. Substances that were not in equilibrium were mainly constituents of plastics and tire rubber, and their high concentrations in the particle phase were probably due to extractions from the particles themselves. Linear correlations between TSS and total compound concentrations were found for 17 PAHs and two musk fragrances, suggesting stable particle loadings and aqueous concentrations over the course of the rain event, most likely due to particle delivery from a particle source with a constant degree of contamination. The total cytotoxicity of water plus particles in the river correlated linearly with TSS during storm events. Inflowing water and particles from all sources appeared to be integrated, such that the total cytotoxicity of all contaminants per mass of particles and volume of water in the river was stable throughout storm events. From this relationship, a threshold of 0.5 g L-1 TSS was derived, above which particle-facilitated transport exceeded dissolved cumulative contaminant transport in the Ammer River, indicating the relevance of particle-facilitated contaminant transport.