The flood-prone transport of historical contaminants to the Elbe Estuary:
Modelling deposition and monitoring ecosystem effects
S. Heise1, J. Angelstorf1, B. Fricke2, P. Hsu1, K. Moshenberg1, A. Schulte-Rentrop2, H. Weilbeer2, N. Winkel2
1 Hamburg University of Applied Sciences,
Sciences Lohbrügger Kirchstraße 65,
65 D-21033
D 21033 Hamburg
2 Federal Waterways Engineering and Research Institute, Wedeler Landstraße 157, D-22559 Hamburg

Contaminated Sediments in the Elbe
Ecological risks from contaminants in the Elbecatchment derive mainly from mobile, historicallypolluted sediment, coming from the Czech Republic,
the tributaries Mulde and Saale, and from groyne
fields (Heise et al. 2007). No information is available
yet on whether high water discharge situations willlead to deposition of particle bound contaminants(from upstream Areas of Risk) in the ecologicallyimportant mudflats of the estuary, impairing sedimentquality and increasing ecotoxicity.

Modelling of Transport

Coastalmudflats

Fresh water
mudflats

Saale:
Cd,Hg, Cu, Zn,
P

Mulde:

Fig. 1: Elbe estuary - areas of field surveys
Fig. 2: Areas of Risk from contaminants in the Elbe catchment

AsDioxine
HCHCR
HCH, HCB, PCB, DDXTBTCatchment

Estuary

Using the 3- dimensional hydrodynamic
model UnTrim in combination with themorphological module SediMorph, BAW
modelled contaminant transport in theestuary. Fig. 4 depicts major
sedimentation areas for particle-boundheavy metals:. harbour basins, thefreshwater mudflat „Mühlenberger
Mühlenberger Loch“
Loch
and the coastal mudflat „Neufelder Watt“(Fig. 1).
Contaminant transport in the catchment
area is modelled using a flexible meshmodel (MIKE 21 FM). The model reflects
the accumulation of contaminants with thefine material in the groyne fields along theElbe River (Fig. 3)

GoogleEarthFig. 4:Spatial distribution of Zinc in the harbour area (right) and at themouth of the Elbe (left) after modelling the inflow of 1500 mg/kg Zinc
to the system under high water conditions.

Monitoring of Effects
Particle-bound contaminant loads in theElbe River are strongly dependent onhigh discharge events (Data: Arge-Elbe)(Fig. 5).
In multiple sampling surveys of 2009 and2010, freshly deposited material wasgathered from mudflat areas in theestuary under normal and high waterconditions. No correlation was observed
between ecotoxicity and water disharge(Fig. 6).
After the hundred-years flood in 2002,
ecotoxicity of sediments was strongly
increased in the area of Neufelder Wattand Otterndorf. Data are based on 4
biotests. Results were integrated in
toxicity classes, ranging from green (notoxicity) to red (strongly toxic) (Fig. 7).

Catchment

Estuary
Flood event in 2002

Various samples
2009/2010

Fig. 3: Example model results showing
the accumulation of sediment-sorbed
HCB in groyne fields (photo: R.
Schwartz) downstream of Wittenberg

Discharge profile

BeforeAfterFig. 7: Ecotoxicologicaleffects before and after
the Elbe extreme highwater discharge 2002
Fig. 6: Ecotoxicological effect of elutriates from freshly deposited material
in the Microtox-Test. Flood event samples shown in green and red.

Fig. 5: Cd-loads of the Elbe River during
different discharge conditions(Data: ARGE-Elbe)
ARGE Elbe)

Summary and Conclusions: Impact of high water discharge on estuarine sediment quality?
 Model-based simulation of contaminant transport in the catchment and estuary so far reflect reality in terms ofsedimentation of fine sediment, and, hence, contaminant accumulation in groyne fields, harbour basins, and mud flats.
Additional model runs with different contaminants will aid in understanding contaminant mobility in the catchment and in
the estuary under high water conditions.
 In the aftermath of the 100 yrs-flood event in 2002, mudflats in the Elbe mouth showed increased toxicity (4 biotests),
potentially related to historic polluted sediments from upstream areas.
 During mean high water discharges in 2010, no increased toxicity was detected. Future surveys during high water
discharge events will determine whether the toxicity increase observed in 2002 was an exception or whether only
extreme high water events have the potential to impair sediment quality in the estuary.