Structural Diversity of Organic Contaminants in a meso-scaled River System

Abstract

Due to intensive anthropogenic usage, a complex mixture of inorganic and organic contaminants entered and still enters freshwater systems, released by various activities and emission sources. However, because of the highly dynamic nature of rivers, the individual occurrence, fate, and behavior, especially of organic contaminants, are highly complex and not fully understood. Here, a GC/MS non-target screening was applied to identify and determine the chemical diversity in the aqueous phase of the meso-scaled Rur river and to categorize indicative and relevant contaminants according to their load profiles for a distinct emission characteristic. Besides very well-known or widespread lipophilic to semi-polar contaminants, also so far unknown or only sporadically identified substances have been detected. In particular, wastewater treatment plants and the paper industry have been identified as major emission sources. Additionally, temporal variations in organic contamination were investigated over three sampling campaigns (2004, 2015, and 2020). Within this timespan, the overall composition of the contamination in the Rur has changed slightly, but nevertheless, the high chemical diversity remained. A detailed consideration such as that undertaken in this study is necessary as the occurrence of substances in a river system depends on many different factors. For a holistic assessment of environmental behavior, not only the sampling locations and associated development of emission profiles must be considered but also temporal variations and mitigation measures. Such a multi-parameter scenario provides an important basis for the mitigation and reduction of organic pollutants in our environment.