Can drones be used to conduct water sampling in aquatic environments? A review

Microorganisms are ubiquitous in freshwater aquatic environments, but little is known about their abundance, diversity, and transport. We designed and deployed a remote-operated water-sampling system onboard an unmanned surface vehicle (USV, a remote-controlled boat) to collect and characterize microbes in a freshwater lake in Virginia, USA. The USV collected water samples simultaneously at 5 and 50 cm below the surface of the water at three separate locations over three days in October, 2016. These samples were plated on a non-selective medium (TSA) and on a medium selective for the genusPseudomonas(KBC) to estimate concentrations of culturable bacteria in the lake. Mean concentrations ranged from 134 to 407 CFU/mL for microbes cultured on TSA, and from 2 to 8 CFU/mL for microbes cultured on KBC. There was a significant difference in the concentration of microbes cultured on KBC across three sampling locations in the lake (P= 0.027), suggesting an uneven distribution ofPseudomonasacross the locations sampled. There was also a significant difference in concentrations of microbes cultured on TSA across the three sampling days (P= 0.038), demonstrating daily fluctuations in concentrations of culturable bacteria. There was no significant difference in concentrations of microbes cultured on TSA (P= 0.707) and KBC (P= 0.641) across the two depths sampled, suggesting microorganisms were well-mixed between 5 and 50 cm below the surface of the water. About 1 percent (7/720) of the colonies recovered across all four sampling missions were ice nucleation active (ice+) at temperatures warmer than −10 °C. Our work extends traditional manned observations of aquatic environments to unmanned systems, and highlights the potential for USVs to understand the distribution and diversity of microbes within and above freshwater aquatic environments.

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Field Study for PAH Absorption Performances of Butyl Rubber, PDMS, and SPMD Passive Samplers

10.21203/rs.3.rs-1089623/v1 ◽

2021 ◽

Author(s):

Oktay Eren Tureyen ◽

Sevil Deniz Yakan ◽

Atilla Yilmaz ◽

Berkant Yetiskin ◽

Oguz Okay ◽

...

Keyword(s):

Water Column ◽

Marine Ecosystem ◽

Butyl Rubber ◽

Passive Samplers ◽

Aquatic Environments ◽

Water Sampling ◽

Challenging Tasks ◽

Polycyclic Aromatic ◽

Absorption Performance ◽

Low Solubility

Abstract Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants having various adverse effects on the marine ecosystem. Because of their low solubility in the marine environment, their detection and monitoring in the water column are challenging tasks. Passive samplers are used to detect PAHs in aquatic environments as complementary tools to conventional water sampling. In the present study, PAH absorbance performances of four butyl rubber-based (BR) passive samplers with different structures (SN5, SN10, DN, and TN) and commercialized passive samplers (SPMD and PDMS) were determined. Stainless steel cages containing passive samplers were deployed in the water column in Istinye Bay, Istanbul, and retrieved after 7 and 28 days. Collected samplers were analyzed in the laboratory to determine their PAH contents. Results showed that, even though the SPMD samplers had the highest total PAH content, they were not able to collect PAHs with log Kow value of above 6.0. Similarly, PAHs with log Kow values higher than 5.5 could have not been collected by PDMS samplers. In contrast, BR-based passive samplers have sampled also high molecular weight PAHs in the water column, and SN10 sampler showed the highest performance in terms of the collected PAHs. Results highlighted that SN10 sampler has a wide absorption range when it is compared with the commercialized samplers, and it has also advanced absorption performance relative to the other BR samplers.

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