A total of 196 water samples were collected from January 2011
to June 2012 from 4 different sampling sites (Fig.1). Site A is located
80 km upstream of the river mouth (n ¼ 36 samples). The water
flow rate or mean river discharge volume at site A was 0.5 m3/s,
corresponding to 14 hm3/s of mean annual discharge. Ten WWTP
are located upstream of the sampling site and present a mean
annual effluent discharge of 6 hm3/s. Site B (n ¼ 37) is located
approximately 70 km downstream from site A and 10 km from the
river mouth close to the city of Barcelona. The Llobregat River at site
B has 255 hm3/s of annual discharge, of which 154 hm3/s come
from fifty upstream WWTP effluents.