E7 NITROGEN CONCENTRATION

NO3-N [mg l-1]
May 1982 April 1983
          Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec
Surface   0.2    1.0    1.0    0.1    0.8    0.5    0.3    0.8    0.7    0.5    0.1    0.2