Spatial and Temporal Variability in Attenuation of Polar Organic Micropollutants in an Urban Lowland Stream

Abstract

Contamination of rivers by trace organic compounds (TrOCs) poses a risk for aquatic ecosystems and drinking water quality. Spatially- and temporally varying environmental conditions are expected to play a major role in controlling in-stream attenuation of TrOCs. This variability is rarely captured by in situ studies of TrOC attenuation. Instead, snap-shots or time-weighted average conditions and corresponding attenuation rates are reported. The present work sought to investigate this variability and factors controlling it by analysis of 24 TrOCs over a 4.7 km reach of the River Erpe (Berlin, Germany). The factors investigated included sunlight and water temperature as well as the presence of macrophytes. Attenuation rate constants in 48 consecutive hourly water parcels were tracked along two contiguous river sections of different characteristics. Section 1 was less shaded and more densely covered with submerged macrophytes compared to section 2. The sampling campaign was repeated after macrophyte removal from section 1. The findings show, that section 1 generally provided more favorable conditions for both photo- and biodegradation. Macrophyte removal enhanced photolysis of some compounds (e.g., hydrochlorothiazide and diclofenac) while reducing the biodegradation of metoprolol. The transformation products metoprolol acid and valsartan acid were formed along the reach under all conditions.

Passive sampling of organic contaminants across the water-sediment interface of an urban stream

“…Similar concentrations were reported in a parallel study over 2 days (June 14 to June 17, 2016) based on an hourly sampling resolution (comparison provided in Fig. ESM1.I-8) (Jaeger et al, 2019).…”

“…To date, only few studies have tested these hypotheses. Studies with explicit focus on the fate of OCs in HZs were either conducted in bench-scale flumes (Kunkel and Radke, 2008;Li et al, 2015), in a sediment core of a river bank filtration site (Burke et al, 2014) or insitu river field sites (Jaeger et al, 2019;Radke, 2012, 2011;Lewandowski et al, 2011b;Posselt et al, 2018;Radke et al, 2010;Schaper et al, 2019Schaper et al, , 2018b. In these studies, HZ-like conditions have shown to enhance or induce the biotransformation of certain OCs.…”

Mapping Micro-Pollutants and Their Impacts on the Size Structure of Streambed Communities

“…In addition, from the total set of targeted compounds selected as model EOCs, the artificial low-calorie sweetener acesulfame was the most widespread chemical and was detected almost constantly in all polluted streams in our study. This pattern is consistent with previous studies in which acesulfame has been reported as the most ubiquitous EOC in streambed sediments and groundwater across Europe [12,[30][31][32][49][50][51]. Thus, our findings strongly support the use of acesulfame as a marker of EOC pollution for application in management and regulation of surface and subsurface waters [49].…”

Is the Hyporheic Zone Relevant beyond the Scientific Community?

“…For example, in a bench-scaled flume experiment designed to study hyporheic processes [175], TPs were detected, which were only formed in the sediment but released to the water, hinting at secondary contamination with TPs [176]. In particular, valsartan acid, a rather stable TP of the common blood pressure medication valsartan, forms in situ in the HZ [160,177] and significantly increases its concentrations in the surface water of wastewater receiving streams [178].…”