2.3 Sample analysis
Chemistry analyses were done
according to the American Standards
for Water Quality (APHA standards,
1995). Dissolved Organic Carbon
(DOC) was analysed with IR Spectrophotometry
after acidification and combustion
(limit of detection of 0.5 mg.L-1).
For the Total Suspended Solids (TSS),
gravimetric method was used after filtration
at 1.2 μm and drying 2 hours at
103-105 °C. Total Nitrogen (TN) and
Total Phosphorous (TP) were analysed
by spectrophotometry whereas nitrate
(NO3-N) and Soluble Reactive Phosphorus
concentrations (PO4-P) were
determined using HPLC (Metrohm 861
Advanced Compact IC after filtration at
0.45 μm). Ammonia-nitrogen (NH3-N)
was calculated from NH4-N data, combined
with pH and water temperature.
For Biological Oxygen Demand at
5 days (BOD5) and the Chemical Oxygen
Demand (COD), the Dissolved
Oxygen (DO) is measured by oxygen
membrane probe after 5 days of incubation
at 20 °C (see Chanudet et al.,
same issue for a thorough detail of the
limit of detection).