Microorganisms Collected from the Surface of Freshwater Lakes Using a Drone Water Sampling System (DOWSE)

Advancements of remote data acquisition and processing in unmanned vehicle technologies for water quality monitoring: An extensive review

Regular water quality monitoring is becoming desirable due to the increase in water pollution caused by both climate change and the generation of industrial chemicals. Unmanned vehicles have emerged as key technologies for remote data acquisition, providing fast and accurate methods for water quality monitoring. However, current research on unmanned vehicles has not systematically examined their features and limitations, which are crucial for identifying future research directions and applications of unmanned vehicle technologies. Therefore, this study extensively reviews the advancements in remote data acquisition and processing using unmanned vehicle technologies for water quality monitoring to provide valuable insights for future research. First, the types of unmanned vehicles and their application ranges for water quality monitoring are summarized. Among the unmanned vehicle technologies, unmanned aerial vehicles are considered primary platforms for water quality monitoring due to their wide data acquisition range and their ability to accommodate diverse sensors and samplers. Also, the types of samplers and sensors mounted on the unmanned vehicles are analyzed based on their characteristics. It is concluded that spectral sensors offer the most cost-effective approach for acquiring real-time water quality data. Furthermore, algorithms that convert image data into water quality data are examined, focusing on data preprocessing, analysis, and validation. The findings reveal a close relationship between the analysis of spectral characteristics of each water quality parameter and the wavelength ranges of red and red-edge. Lastly, future research directions for unmanned vehicle technologies are further suggested based on the summarized technological limitations.

Diversity and ice nucleation activity of Pseudomonas syringae in drone-based water samples from eight lakes in Austria

Bacteria from the Pseudomonas syringae complex (comprised of at least 15 recognized species and more than 60 different pathovars of P. syringae sensu stricto) have been cultured from clouds, rain, snow, streams, rivers, and lakes. Some strains of P. syringae express an ice nucleation protein (hereafter referred to as ice+) that catalyzes the heterogeneous freezing of water. Though P. syringae has been sampled intensively from freshwater sources in the U.S. and France, little is known about the genetic diversity and ice nucleation activity of P. syringae in other parts of the world. We investigated the haplotype diversity and ice nucleation activity at -8 °C (ice+) of strains of P. syringae from water samples collected with drones in eight freshwater lakes in Austria. A phylogenetic analysis of citrate synthase (cts) sequences from 271 strains of bacteria isolated from a semi-selective medium for Pseudomonas revealed that 69% (188/271) belonged to the P. syringae complex and represented 32 haplotypes in phylogroups 1, 2, 7, 9, 10, 13, 14 and 15. Strains within the P. syringae complex were identified in all eight lakes, and seven lakes contained ice+ strains. Partial 16S rDNA sequences were analyzed from a total of 492 pure cultures of bacteria isolated from non-selective medium. Nearly half (43.5%; 214/492) were associated with the genus Pseudomonas. Five of the lakes (ALT, GRU, GOS, GOL, and WOR) were all distinguished by high levels of Pseudomanas (p ≤ 0.001). HIN, the highest elevation lake, had the highest percentage of ice+ strains. Our work highlights the potential for uncovering new haplotypes of P. syringae in aquatic habitats, and the use of robotic technologies to sample and characterize microbial life in remote settings.

Lab-on-a-Drone: remote voltammetric analysis of lead in water with real-time data transmission

The present work describes a laboratory-on-a-drone (Lab-on-a-Drone) developed to perform in situ detection of contaminants in environmental water samples. Toward this goal, the system was mounted on an unmanned aerial vehicle (UAV) (drone) and remotely controlled via Wi-Fi to acquire a water sample, perform the electrochemical detection step, and then send the voltammetry data to a smartphone. This Lab-on-a-Drone system was also able to recharge its battery using a solar cell, greatly increasing the autonomy of the system, even in the absence of a power line. As a proof of concept, the Lab-on-a-Drone was employed for the detection of Pb2+ in environmental waters, using a simple electrochemical cell containing a miniaturized screen-printed boron-doped diamond electrode (SP-BDDE) as a working electrode, an Ag/AgCl as a reference electrode, and a graphite ink as a counter electrode. For quantification purposes, analytical curves were constructed covering a concentration range from 1.0 μg L-1 (4.83 nmol L-1) to 80.0 μg L-1 (386.10 nmol L-1), featuring a detection limit of 0.062 μg L-1 (0.30 nmol L-1). The Lab-on-a-Drone was applied to monitor a water reservoir in the Metropolitan Region of Recife, Brazil. To evaluate its performance regarding accuracy and precision, a reference method based on inductively coupled plasma optical emission spectrometry (ICP-OES) was applied, and the results obtained by both methods showed no statistical differences (t-test at 95% confidence level, n = 3). These results represent the first demonstration of the capabilities of an adapted UAV for the quantification of electroactive environmental contaminant using voltammetry, with real-time data transmission. Thus, the Lab-on-a-Drone makes it possible to reach difficult-to-access environmental reserves and to monitor potentially polluting activity in distant water bodies. Thus, this tool can be used by governments and non-profit organizations to monitor environmental waters using fast, low-cost, process autonomy with accurate and precise data useful to decision making.

Comparison of drone and vessel-based collection of microbiological water samples in marine environments

Many water quality metrics cannot be measured in situ and require collection of a physical sample for laboratory analysis. This includes microbiological samples for detection of fecal coliform bacteria in marine and freshwater systems which are a critical component of food safety programs for human consumption of bivalve shellfish worldwide. Water sample collection programs are typically vessel-based which can be time and resource intensive. In Canada, the Canadian Shellfish Sanitation Program aims to avoid consumption of contaminated molluscan bivalves by monitoring fecal coliform bacteria through vessel-based water sample collection. Uncrewed aerial vehicles or drones are becoming more commonly used for water sample collection given their relatively low cost but are rarely used to support microbiological analyses. A prerequisite for the acceptance of a new collection method for a regulatory program is to determine if the method of sample collection affects results. To assess this potential, we designed, developed, and tested a sampling device attached to the underside of a drone to collect water samples for bacteriological analysis. Drone and vessel-based samples were collected in the same location, at the same 20-cm depth, within a minute apart, at ten different geographic locations in coastal Nova Scotia waters to compare fecal coliform counts. Bacterial count estimates obtained from drone-collected samples were not significantly different than estimates obtained from vessel-collected samples (p < 0.5). Results from this study suggest novel water sampling techniques using drones could supplement or replace traditional vessel-based sampling methods.

In situ voltammetric analysis of 2,4-dichlorophenoxyacetic acid in environmental water using a boron doped diamond electrode and an adapted unmanned air vehicle sampling platform

In the present work a voltammetric method was developed for in situ detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in environmental water samples, using a compact and lightweight electrochemical cell using a fused deposition modeling (FDM) 3D printer with biodegradable polylactic acid filament, and a boron-doped diamond electrode (BDDE). The samples were collected by an adapted unmanned aerial vehicle (UAV) with a micropump and a miniature solenoid valve powered by an open source microcontroller. After optimizing the supporting electrolyte, pH and parameters of the square wave voltammetry (SWV) a linear analytical curve for 2,4-D in 0.5 mol L^-1 Na₂SO₄ (pH = 2.0 regulated using 0.5 mol L^-1 H₂SO₄ solution) in a concentration range from 100 nmol L^-1 to 911 nmol L^-1 with 34 nmol L^-1 as the limit of detection was obtained. The same samples in situ analyzed by SWV were sent to the laboratory for gas chromatography-mass spectrometry (GC-MS) analysis; and there was no statistical difference from the concentration of 2,4-D in any of the samples at a 95% confidence level. Therefore, the method developed for quantification of 2,4-D in water provides an important environmental monitoring tool since it enables access to difficult areas in a fast, practical and safe way. This is the first time that an adapted UAV with these features has been used to collect environmental water for in situ electrochemical analysis as a screening tool to alert the presence of environmental hazard compounds, such as 2,4-D. Thus, this method can be used by environmental and sanitary control agencies to monitor or to supervise environmental water quality with response in real time.

Seasonal ice nucleation activity of water samples from alpine rivers and lakes in Obergurgl, Austria

Heterogeneous ice nucleation plays an important role in many environmental processes such as ice cloud formation, freezing of water bodies or biological freeze protection in the cryosphere. New information is needed about the seasonal availability, nature, and activity of ice nucleating particles (INPs) in alpine environments. These INPs trigger the phase transition from liquid water to solid ice at elevated subzero temperatures. We collected water samples from a series of alpine rivers and lakes (two valleys and their rivers, an artificial pond, and a natural lake system) in Obergurgl, Austria in June 2016, July 2016, November 2016, and May 2017. Each alpine river and lake was sampled multiple times across different seasons, depending on site access during different times of the year. Water samples were filtered through a 0.22 μm membrane filter to separate microbial INPs from the water, and both fractions were analyzed for ice nucleation activity (INA) by an emulsion freezing method. Microorganisms were cultured from the filters, and the cultures then analyzed for INA. Portions of the filtered samples were concentrated by lyophilization to observe potential enhancement of INA. Two sediment samples were taken as reference points for inorganic INPs. Sub-micron INPs were observed in all of the alpine water sources studied, and a seasonal shift to a higher fraction of microbial ice nucleators cultured on selective media was observed during the winter collections. Particles larger than 0.22 μm showed INA, and microbes were cultured from this fraction. Results from 60 samples gave evidence of a seasonal change in INA, presence of submicrometer INPs, and show the abundance of culturable microorganisms, with late spring and early summer showing the most active biological INPs. With additional future research on this topic ski resorts could make use of such knowledge of geographical and seasonal trends of microbial INPs in freshwater habitats in order to improve the production of artificial snow.

Toys or Tools? Utilization of Unmanned Aerial Systems in Mosquito and Vector Control Programs

Organized mosquito control programs (MCP) in the United States have been protecting public health since the early 1900s. These programs utilize integrated mosquito management for surveillance and control measures to enhance quality of life and protect the public from mosquito-borne diseases. Because much of the equipment and insecticides are developed for agriculture, MCP are left to innovate and adapt what is available to accomplish their core missions. Unmanned aerial systems (UAS) are one such innovation that are quickly being adopted by MCP. The advantages of UAS are no longer conjectural. In addition to locating mosquito larval habitats, UAS affords MCP real-time imagery, improved accuracy of aerial insecticide applications, mosquito larval detection and sampling. UAS are also leveraged for applying larvicides to water in habitats that range in size from multi-acre wetlands to small containers in urban settings. Employing UAS can reduce staff exposure to hazards and the impact associated with the use of heavy equipment in sensitive habitats. UAS are utilized by MCP nationally and their use will continue to increase as technology advances and regulations change. Current impediments include a dearth of major UAS manufacturers of equipment that is tailor-made for mosquito control, pesticides that are optimized for application via UAS and regulations that limit the access of UAS to national airspace. This manuscript highlights the strengths and weaknesses of UAS within MCP, provides an update on systems and methods used, and charts the future direction of UAS technology within MCP tasked with public health protection.

Ice Nucleation Activity of Alpine Bioaerosol Emitted in Vicinity of a Birch Forest

In alpine environments, many plants, bacteria, and fungi contain ice nuclei (IN) that control freezing events, providing survival benefits. Once airborne, IN could trigger ice nucleation in cloud droplets, influencing the radiation budget and the hydrological cycle. To estimate the atmospheric relevance of alpine IN, investigations near emission sources are inevitable. In this study, we collected 14 aerosol samples over three days in August 2019 at a single site in the Austrian Alps, close to a forest of silver birches, which are known to release IN from their surface. Samples were taken during and after rainfall, as possible trigger of aerosol emission by an impactor and impinger at the ground level. In addition, we collected aerosol samples above the canopy using a rotary wing drone. Samples were analyzed for ice nucleation activity, and bioaerosols were characterized based on morphology and auto-fluorescence using microscopic techniques. We found high concentrations of IN below the canopy, with a freezing behavior similar to birch extracts. Sampled particles showed auto-fluorescent characteristics and the morphology strongly suggested the presence of cellular material. Moreover, some particles appeared to be coated with an organic film. To our knowledge, this is the first investigation of aerosol emission sources in alpine vegetation with a focus on birches.

Carbonate biomineralization differentially induced by two psychrophilic Pseudomonas psychrophila strains isolated from an alpine travertine landform

Besides geography and climate, biological factors play an important role in shaping travertine landforms, but the biochemical mechanisms of microbial processes in travertine formation have been rarely studied. Two psychrophilic bacterial strains, A20-18 and B21-3 of Pseudomonas psychrophila, isolated from travertine pools of Huanglong, a typical alpine travertine landform, were investigated for their roles in calcium carbonate mineralization, including the deposition process and products. X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy were used to characterize the crystal phase and morphology of CaCO₃ precipitation. The results showed that there were no significant differences between the two strains in CaCO₃ deposition rate. Extracellular polymeric substances (EPS)-free cells significantly inhibited calcification, compared with a control. Irregular crystals and polyhedral structures are common to all treatments using the two strains. These complex polycrystals were the result of the synergistic effect of homogeneous nucleation and heterogeneous nucleation. EPS and cells of strain B21-3 formed ring-like structures of calcium carbonate, which was possibly from the amphiphilic polymer forming a circular arrangement in water. These results are significant for understanding the microbial factor in Huanglong travertine deposition and providing new insights into the morphological control of the biomineralization mechanism at low temperatures.

Calcium carbonate crystals induced by two Pseudomonas psychrophila strains and their organic compounds were studied.

A Drone-Based Bioaerosol Sampling System to Monitor Ice Nucleation Particles in the Lower Atmosphere

Terrestrial ecosystems can influence atmospheric processes by contributing a huge variety of biological aerosols (bioaerosols) to the environment. Several types of biological particles, such as pollen grains, fungal spores, and bacteria cells, trigger freezing processes in super-cooled cloud droplets, and as such can contribute to the hydrological cycle. Even though biogenic particles are known as the most active form of ice nucleation particles (INPs), the transport to high tropospheric altitudes, as well as the occurrence in clouds, remains understudied. Thus, transport processes from the land surface into the atmosphere need to be investigated to estimate weather phenomena and climate trends. To help fill this knowledge gap, we developed a drone-based aerosol particles sampling impinger/impactor (DAPSI) system for field studies to investigate sources and near surface transport of biological INPs. DAPSI was designed to attach to commercial rotary-wing drones to collect biological particles within about 100 m of the Earth’s surface. DAPSI provides information on particulate matter concentrations (PM10 & PM2.5), temperature, relative humidity, and air pressure at about 0.5 Hz, by controlling electrical sensors with an onboard computer (Raspberry Pi 3). Two remote-operated sampling systems (impinging and impacting) were integrated into DAPSI. Laboratory tests of the impinging system showed a 96% sampling efficiency for standardized aerosol particles (2 µm polystyrene latex spheres) and 84% for an aerosol containing biological INPs (Betula pendula). A series of sampling missions (12 flights) were performed using two Phantom 4 quadcopters with DAPSI onboard at a remote sampling site near Gosau, Austria. Fluorescence microscopy of impactor foils showed a significant number of auto-fluorescent particles < 0.5 µm at an excitation of 465–495 nm and an emission of 515–555 nm. A slight increase in ice nucleation activity (onset temperature between −27 °C and −31 °C) of sampled aerosol was measured by applying freezing experiments with a microscopic cooling technique. There are a number of unique opportunities for DAPSI to be used to study the transport of bioaerosols, particularly for investigations of biological INP emissions from natural sources such as birch or pine forests.

Perspectives on Harmful Algal Blooms (HABs) and the Cyberbiosecurity of Freshwater Systems

Harmful Algal Blooms (HABs) have been observed in all 50 states in the U.S., ranging from large freshwater lakes, such as the Great Lakes, to smaller inland lakes, rivers, and reservoirs, as well as marine coastal areas and estuaries. In 2014, a HAB on Lake Erie containing microcystin (a liver toxin) contaminated the municipal water supply in Toledo, Ohio, providing non-potable water to 400,000 people. Studying HABs is complicated as different cyanobacteria produce a range of toxins that impact human health, such as microcystins, saxitoxin, anatoxin-a, and cylindrospermopsin. HABs may be increasing in prevalence with rising temperatures and higher nutrient runoff. Consequently, new tools and technology are needed to rapidly detect, characterize, and respond to HABs that threaten our water security. A framework is needed to understand cyber threats to new and existing technologies that monitor and forecast our water quality. To properly detect, assess, and mitigate security threats on water infrastructure, it is necessary to envision water security from the perspective of a cyber-physical system (CPS). In doing so, we can evaluate risks and research needs for cyber-attacks on HAB-monitoring networks including data injection attacks, automated system hijacking attacks, node forgery attacks, and attacks on learning algorithms. Herein, we provide perspectives on the research needed to understand both the threats posed by HABs and the coupled cyber threats to water security in the context of HABs.