Contamination of Sediments in the German North Sea Estuaries Elbe, Weser and Ems and Its Sensitivity to Climate Change

Projections of climate-induced changes in temperature and precipitation let expect also altered frequencies and intensities of extreme hydrological events such as floods or prolonged periods of low river discharges. Particularly such extremes may, moreover, lead to modified inputs of particulate matter into rivers and estuaries, and may thus affect the quality of estuarine sediments. This study focuses on the assessment of potential climate-induced changes of particle-bound contaminant concentrations in the estuaries of the rivers Elbe, Ems and Weser and the resulting challenges for sediment management in the navigable waterways there. The estimation of climate-induced changes of contaminant concentrations in estuarine particulate matter (PM) was based on results of projections on the fluvial PM input into the Elbe estuary in the near (2021–2050) and far future (2071–2100) and on assumed extreme changes of such inputs. A mixing model using the concentrations of selected contaminants as indicators for marine and fluvial PM was applied. Distinct changes of contaminant concentrations were found only for the far future and with the assumed extreme PM inputs in the inner Elbe estuary. And only for the inner Elbe estuary the worst-case scenario indicated that concentrations of some organochlorine contaminants in the far future exceed the national assessment criteria for the handling of dredged material within coastal waterways more distinct than today. Therefore, adaptations of practices for the management of dredged material to higher particulate matter contaminations should be considered there in the medium or long-term perspective.