Field trials took place between September and November 2019 at six lakes (Loughs Fee, Inagh, Conn, Derg, Mask and Ballyquirke lake) in the west of Ireland. The lakes chosen represented two of the main lake types found in Ireland (high and low alkalinity) and a range of trophic gradients. In addition, Lough Fee and Inagh are currently not monitored under the EPA WFD Lake monitoring programme while Lough Conn, Mask, Derg and Ballyquirke lake are included in the monitoring programme.
One location was sampled on Loughs Fee and Inagh, two locations on Lough Conn and Ballyquirke Lake and three locations on Loughs Mask and Derg. At each location, three paired water samples (traditional boat water sampling and drone water sampling) were collected (n = 36 paired water samples in total). Data and samples were collected at each location to examine the variability associated with each sampling method.
Key lake characteristics are presented below
On completion of sampling, water samples were delivered to the EPA Laboratories in Castlebar for analysis of pH, alkalinity (mg/l CaCO3), hardness (mg/l CaCO3), true colour (mg/l PtCo), chloride (mg/l), silica (mg/l SiO2), ammonia (mg/l N), total oxidised nitrogen (mg/l N) (TON), nitrite (mg/l N), nitrate (mg/l N), ortho-phosphate (mg/l P), total phosphorous (mg/l P) (TP), and chlorophyll-a (mg/m3) (Chl-a).
Real-time physico-chemical data (pH, DO, conductivity and temperature) was captured using the EXO Sonde which was deployed before sampling (traditional boat and drone water sampling) and it recorded the variables every second. On return to the lake shore, data was downloaded to a laptop. The project team used data produced from the last 90 seconds of the period the EXO Sonde was recording data while in the lake in order to sure that the probe had sufficient time to adjust from recording data while in flight.
Photos taken during field trials at Lough Conn, Co. Mayo
Photo credit: Heather Lally