The dissolved concentrations of U behave opposite to the discharge.
They decrease with increasing discharge and vice versa in
group 1 of Fig. 4. Thereby, the colloidal part of dissolved U temporarily
increases. In contrast, the content of Ti in the total sample
is dominated by the particulate fraction over the whole flood
(group 2 of Fig. 4). Dissolved concentrations at the end of the event
were negligible. The particulate part of the sample increases for Cu
(group 3 of Fig. 5) and As (group 4 of Fig. 5) at the beginning of the
flood event (up to the 4th day), reversed to the dissolved part. In
contrast, the colloidal proportion within the dissolved fraction is
low and shows only little fluctuation. In general, the proportion
of the colloidal fraction within the dissolved fraction fluctuated
at low level. The concentrations varied between 17.7% (U) and
1–2% (Ti). Notable colloidal proportions were calculated only for
U, Zn and Fe. Generally, the ‘‘colloidal fraction” within the operationally
defined dissolved fraction decreased in the following
order:
U > Zn > Fe > As > Cu > Mn; Ti; Cr; Ni
The dissolved part within the total fraction fluctuated from
81.6% (U) to 2.4% (Ti). The proportion was comparable to investigations
in 2005 (Baborowski et al., 2007) and decreased as follows:
2006 : U > As; Ni > Zn; Cu > Mn > Pb; Al; Fe; Cr > Ti
2005 : U > As; Ni > Cu; Zn > Mn > Cr > Al; Pb; Fe