Figure 1: Site map and U content in the stream.

(a) The two black arrows show the stream flow direction and the seven numbered orange triangles indicate locations where stream water was sampled in April and November 2011 and July 2012 (locations number 1 and 7 outside the wetland were only sampled in July 2012). (b) U concentration data for the sampled stream water in the three seasons indicate a clear increase with distance downstream within the wetland and a decrease in the lake inlet because of dilution from lake water, which suggests that U is released gradually into the stream water from the wetland; the black arrow shows the stream flow direction; the blue zone shows the distance range within the wetland; the dashed line represents the background U concentration (0.0042 μM) for surface water in the region. The stream water samples were filtered with 0.22 μm pore-size membrane. The highest s.d. (Δ) is 10% of the reported values based on three replicate measurements and is not shown.