NO3 contents were also measured in order to evaluate the influence
of agriculture activity in groundwater, as agriculture, and in particular
livestock, is one of the main economic activities in the archipelago, as
shown by the gross value added to regional product due to agriculture
(8.6%; year 2010). Median values for nitrate content range from
0.88 mg/L (spring 29) and 64.35 mg/L (spring 10), therefore exceeding
the standard value of 50 mg/L in a few cases.