Fig. 4. Box plot of average NO₃–N concentrations sampled every 10 d from January through May 2005 for each subcatchment and during baseflow (the boundary of the box closest to zero indicates the 25th percentile, a line within the box marks the median, the boundary of the box farthest from zero indicates the 75th percentile, whiskers above and below the box indicate the 90th and 10th percentiles, and other points are outlying points).