A Novel Automatic Water Autosampler Operated From UAVs for Determining Dissolved Trace Elements

Abstract

Monitoring water systems under extreme conditions or in remote areas poses a risk to scientists and staff involved, and can also result in disturbances to the local flora and fauna. In order to overcome these limitations, new techniques are being developed with the aim to gain more insight into how geochemical pathways of trace elements regulate the functioning of the ocean. Here, we present the first trace metals and inorganic nutrients concentrations measured in dissolved (<0.22 µm) surface water samples collected in the Antarctic by using an Automatic Water Autosampler (AWA) system onboard an unmanned aerial vehicle (UAV). The AWA system has been used to chemically quantify the composition of the water masses (lake and coastal water) of Deception Island (South Shetland Islands, Antarctica), with, for example, Pb values ranging from 0.01 to 0.25 nM in seawater and 1.20 to 2.11 nM in lake water. The results demonstrate the effectiveness of the AWA system in environmental studies that require the sampling of trace metals and nutrients without sample contamination.

The contribution of penguin guano to the Southern Ocean iron pool

“…We found that according to the 16,725 ± 907 penguins censed by the model, a total of 169.4 t of dry weight guano can be expected in the breeding site considering 120 days as the breeding season duration, containing up to 512 ± 246 kg Fe (see Methods). Subsequently, considering the Fe concentration (0.324 mg L −1 ) 38 in the coastal water at the specific time of study, we obtained an approximate Fe content of 26 kg in 8 × 10 4 m 3 of water under the influence of the Chinstrap penguin turbidity plume (Fig. 2a, b ).…”

“…During the campaign, one sampling was performed in the VC colony 38 , in a shore area in the vicinity of various depressions between hills which act like “funnels”, both for penguins to go to/from the nests, and for guano runoff to the ocean. The sampling location was used as a starting point from which the volume of water influenced by the guano release was calculated.…”

“…In addition, the Chinstrap penguins feed almost exclusively (>90% of their diet) on krill 33 – 36 ; and this feeding takes place within the upper 100 m of the water column, where primary production and photosynthetic fixation of carbon by phytoplankton occurs 37 . Furthermore, their significant abundance leads to the accumulation of high densities of Fe-containing guano in the coastal ecosystem, reaching concentrations of up to 3 × 10 3 times higher than the background in the waters surrounding the rookeries 38 . These facts ultimately suggest that penguins could be playing a fundamental role in the Southern Ocean through Fe recycling 39 – 42 .…”

Unmanned aerial vehicles (UAVs) as a tool for hazard assessment: The 2021 eruption of Cumbre Vieja volcano, La Palma Island (Spain)

“…The thermal camera captures non-contact temperature measurements with calibrated temperature data embedded in every pixel, its spectral band is 7.5-13.5 μm and it has a sensor resolution of 336 × 256. In addition, this UAV was equipped with a water sampling device (Sparaventi et al, 2022) with an acid cleaned plastic weighted container (2 L) and a castable instrument hanging from the UAV with a 5-meter rope providing instantaneous profiles of temperature and salinity (CastAway R -CTD) and collected surface water.…”

The contribution of penguin guano to the Southern Ocean iron pool

“…The survey (February 8, 2021) coincided with the end of the breeding season, when penguins tend to leave the colony and therefore the deep learning census corresponded to the lower limit of the whole nesting period. Subsequently, considering the Fe concentration (0.324 mg L -1 (31) ) in the coastal water at the specific time of study, we obtained an approximate Fe content of 26 kg in 8×10 4 m 3 of water under the influence of the Cp plume (Fig. 2a, b).…”