Sediment Sampling
Twenty-five representative sediment samples from seven main western
rivers of Urmia Lake basin were collected for this study (Figure 1).
These included 9 sites in Nazloo Chai (S10 and S11), 3 sites in Shahar
Chai (S13 to S15), 4 sites in Baranduz Chai (S12 to S15), 3 sites in
Ghadar Chai (S16 to S18), 2 sites in Mahabad Chai (S19 and S20), 3 sites
in Simineh Chai (S21 to S23) and 2 sites in Zola Chai (S24 and S25).
Each river was sampled near the headwater and at the discharge point to
the Urmia Lake Basin, and sometimes in-between. A total of two or three
vertical sediment cores (0-10 cm) was collected from eah sampling site
and then mixed to have a composite sample. River sediments commonly dry
out as water level recedes and this process can be expected to influence
P speciation (Schönbrunner et al., 2012). For the Urmia Lake basin,
water levels rise and overland flow occurs seasonally in the riverbed
sediments, therefore most samples were collected from dry sites.