TY  - JOUR
A1  - Kamjunke, Norbert
A1  - Beckers, Liza-Marie
A1  - Herzsprung, Peter
A1  - von Tümpling, Wolf
A1  - Lechtenfeld, Oliver
A1  - Tittel, Jörg
A1  - Risse-Buhl, Ute
A1  - Rode, Michael
A1  - Wachholz, Alexander
A1  - Kallies, Rene
A1  - Schulze, Tobias
A1  - Krauss, Martin
A1  - Brack, Werner
A1  - Comero, Sara
A1  - Gawlik, Bernd Manfred
A1  - Skejo, Hello
A1  - Tavazzi, Simona
A1  - Mariani, Giulio
A1  - Borchardt, Dietrich
A1  - Weitere, Markus
T1  - Lagrangian profiles of riverine autotrophy, organic matter transformation, and micropollutants at extreme drought
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - On their way from inland to the ocean, flowing water bodies, their constituents and their biotic communities are ex-posed to complex transport and transformation processes. However, detailed process knowledge as revealed by La-grangian measurements adjusted to travel time is rare in large rivers, in particular at hydrological extremes. To fill this gap, we investigated autotrophic processes, heterotrophic carbon utilization, and micropollutant concentrations applying a Lagrangian sampling design in a 600 km section of the River Elbe (Germany) at historically low discharge. Under base flow conditions, we expect the maximum intensity of instream processes and of point source impacts. Phy-toplankton biomass and photosynthesis increased from upstream to downstream sites but maximum chlorophyll con-centration was lower than at mean discharge. Concentrations of dissolved macronutrients decreased to almost complete phosphate depletion and low nitrate values. The longitudinal increase of bacterial abundance and production was less pronounced than in wetter years and bacterial community composition changed downstream. Molecular analyses revealed a longitudinal increase of many DOM components due to microbial production, whereas saturated lipid-like DOM, unsaturated aromatics and polyphenols, and some CHOS surfactants declined. In decomposition exper-iments, DOM components with high O/C ratios and high masses decreased whereas those with low O/C ratios, low masses, and high nitrogen content increased at all sites. Radiocarbon age analyses showed that DOC was relatively old (890-1870 years B.P.), whereas the mineralized fraction was much younger suggesting predominant oxidation of algal lysis products and exudates particularly at downstream sites. Micropollutants determining toxicity for algae (terbuthylazine, terbutryn, isoproturon and lenacil), hexachlorocyclohexanes and DDTs showed higher concentrations from the middle towards the downstream part but calculated toxicity was not negatively correlated to phytoplankton. Overall, autotrophic and heterotrophic process rates and micropollutant concentrations increased from up-to down-stream reaches, but their magnitudes were not distinctly different to conditions at medium discharges.
KW  - Phytoplankton
KW  - Nutrients
KW  - Dissolved organic matter (DOM)
KW  - bacteria
KW  - Respiration
KW  - Micropollutants
Y1  - 2022
U6  - https://doi.org/10.1016/j.scitotenv.2022.154243
SN  - 0048-9697
SN  - 1879-1026
VL  - 828
PB  - Elsevier
CY  - Amsterdam
ER  -