“…For borehole samples, dissolved oxygen was measured using a calibrated Aquaprobe, by direct pumping through an Aquaprobe flow-through cell, to avoid any contact of the sample with the atmosphere. Samples for dissolved nutrient (NO3 -, NH4 + , NO2 -, PO4 3as Soluble Reactive Phosphorus -SRP) were filtered directly after sampling through 0.15μm Rhizon membranes into vacutainers for NO3 -, NH4 + , NO2 -(J. S. P. Jiang et al, 2017), and acid-washed HDPE vials for PO4 3-. These samples were then analysed using standard colourimetric methods (Grasshoff et al, 2009), less than ten days for SRP, and less than 30 days for dissolved inorganic nitrogen (DIN), following recommendations for use with vacutainers (Jiang et al, 2017).…”