High Anthropogenic Organic Matter Inputs during a Festival Increase River Heterotrophy and Refractory Carbon Load.

Astrid Harjung,Victor Aigner,Jakob Schelker,Michael Schagerl,Helena Švecová,Nikola Krlovic,Gertraud Steniczka,Katrin Attermeyer

doi:10.1021/acs.est.0c02259

Abstract

Streams and rivers metabolize dissolved organic matter (DOM). Although most DOM compounds originate from natural sources, recreational use of rivers increasingly introduces chemically distinct anthropogenic DOM. So far, the ecological impact of this DOM source is not well understood. Here, we show that a large music festival held adjacent to the Traisen River in Austria increased the river’s dissolved organic carbon (DOC) concentration from 1.6 to 2.1 mg L–1 and stream ecosystem respiration from −3.2 to −4.5 mg L–1. The DOC increase was not detected by sensors continuously logging absorbance spectra, thereby challenging their applicability for monitoring. However, the fluorescence intensity doubled during the festival. Using parallel factor analysis, we were able to assign the increase in fluorescence intensity to the chemically stable UV-B filter phenylbenzimidazole sulfonic acid, indicating organic compounds in sunscreen and other personal care products as sources of elevated DOC. This observation was confirmed by liquid chromatography coupled with mass spectrometry. The elevated respiration is probably fueled by anthropogenic DOM contained in beer and/or urine. We conclude that intense recreational use of running waters transiently increases the anthropogenic DOM load into stream ecosystems and alters the fluvial metabolism. We further propose that chemically distinct, manmade DOM extends the natural range of DOM decomposition rates in fluvial ecosystems.

Highlights

Since the advent of organic synthesis, scientists have created an unprecedented diversity of organic compounds for human use.[6]
We define anthropogenic dissolved organic matter (DOM) as any organic compound dissolved in water originating from organic synthesis, biotechnological production, or human excretion
We investigated if inputs of anthropogenic DOM during the festival can be detected by high-frequency absorbance sensors[15] and fluorescence spectroscopy

Summary

INTRODUCTION

Streams and rivers transport dissolved organic matter (DOM) from the terrestrial ecosystem to the oceans.[1,2] Along this journey, most fractions of DOM are metabolized, resulting in an overall predominance of heterotrophy in fluvial ecosystems.[3,4] Most DOM compounds transported in streams originate from natural sources such as soil organic matter.[1,5] Since the advent of organic synthesis, scientists have created an unprecedented diversity of organic compounds for human use.[6]. Studies of swimming pools suggest that humans can introduce substantial amounts of anthropogenic DOM from sweat, personal care products, hair, and skin as well as urine and feces.[11,12] Previous studies on large festivals have already shown significant alterations of adjacent aquatic ecosystems, caused by the introduction of pharmaceuticals and drugs into river water.[13,14] so far, no previous study has addressed the effects of a large cultural event on DOM fluxes and stream metabolism. We predict that deliveries of potentially labile anthropogenic DOM stimulate ecosystem respiration and enhance heterotrophy

METHODS

RESULTS AND DISCUSSION

■ ACKNOWLEDGMENTS

■ REFERENCES