Figure 7

Relationship between δ¹⁵N_nitrate and δ¹⁸O_nitrate values during 2010 to 2011 (a) and at three monthly sites during 2012 to 2014 (b). MR indicates main reaches samples. T stands for tributaries samples. S stands sewage waste sample. AT stands for atmospheric precipitation samples. Other abbreviations for sources were introduced in the text.