Artificial Water Research Articles

Improvement of water yield and net primary productivity ecosystem services in the Loess Plateau of China since the “Grain for Green” project

The Loess Plateau of China is one of the regions with the most serious soil erosion globally. The ambitious “Grain for Green” project was there implemented to restore degraded ecosystems, profoundly changing the water yield and carbon sequestration ecosystem services. To understand the changes of water- and carbon-related ecosystem services (hereafter WCES) in the Loess Plateau, this study combined the CASA (Carnegie-Ames-Stanford Approach) model and InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) model to thoroughly reveal the changes and intrinsic linkages of water yield and net primary productivity since the “Grain for Green” project in the Loess Plateau. The results show that the WCES of the Loess Plateau were increasing since 2001, dominated by both the climate change and human afforestation. The water yield and net primary productivity showed strong synergistic effects in 80% of the Loess Plateau, mainly resulting from the rapid increase of precipitation in recent years. The increasing atmospheric precipitation contributed to more WCES provisions, which may have offset the trade-off between WCES caused by large-scale afforestation. In view of the synergistic effects of WCES, enhancing water input into the ecosystem may be an effective measure to respond with future WCES degradation in dry years, such as artificial basin-cross water transfer project. Despite the low correlation between teleconnection factors and WCES, the low water yield and reduction of net primary productivity may be associated with a strong El Niño event in 2015. This study assists in a wise decision-making on the future “Grain for Green” and ecological management in the Loess Plateau.

Bis‐Alkylureido Imidazole Artificial Water Channels

AbstractNature creates aquaporins to effectively transport water, rejecting all ions including protons. Aquaporins (AQPs) has brought inspiration for the development of Artificial Water Channels (AWCs). Imidazole‐quartet (I‐quartet) was the first AWC that enabled to self‐assemble a tubular backbone for rapid water and proton permeation with total ion rejection. Here, we report the discovery of bis‐alkylureido imidazole compounds, which outperform the I‐quartets by exhibiting ≈3 times higher net and single channel permeabilities (107 H2O/s/channel) and a ≈2–3 times lower proton conductance. The higher water conductance regime is associated to the high partition of more hydrophobic bis‐alkylureido channels in the membrane and to their pore sizes, experiencing larger fluctuations, leading to an increase in the number of water molecules in the channel, with decreasing H‐bonding connectivity. This new class of AWCs will open new pathways toward scalable membranes with enhanced water transport performances.

Survival trends (2008–2020) of three tree species in response to elephant impact, environmental variation, and stem wire-netting protection in an African savanna

Reduced levels of the survival of large trees (≥5 m height) in Africa’s savannas are a conservation concern, particularly where large trees co-occur with African elephants (Loxodonta africana). Elephants, as ecosystem engineers, can structurally modify and lesson the savanna large tree component. Wire-netting, which involves wrapping chicken-mesh around a tree’s main stem, has been used as a mitigation method to increase tree survival. We assess the trends in survival of three large tree species of conservation importance, namely Lannea schweinfurthii, Senegalia nigrescens and Sclerocarya birrea, within the Associated Private Nature Reserves (APNR) on the western boundary of the Kruger National Park, South Africa. We consider survival trends linked by both elephant impact, as well as external environmental factors. We conducted four field assessments on 2,758 trees in 2008 (baseline), 2012, 2017, and 2020, where we recorded i) elephant impact levels on each tree, ii) whether the tree had wire-netting, and iii) the tree’s survival status. We then modelled tree survival status as a dependent variable against multiple environmental factors. We found that tree survival was lowest when mean annual rainfall was lowest due to the drought, particularly amongst L. schweinfurthii and S. nigrescens. Wire-netting significantly increased large tree survival in comparison to control trees over the 12-year period, however, this effect decreased after four years if the wire-netting had lost its structural integrity. We illustrate how various environmental factors, in combination with elephant impact, affect large tree survival in an African savanna with a high density of artificial water points. We also provide results on the longest known study on wire-netting as a mitigation method for elephant impact on large trees and provide evidence on how a period of drought may have accelerated large tree decline in a southern African savanna.

Bis-Alkylureido Imidazole Artificial Water Channels.

Nature creates aquaporins to effectively transport water, rejecting all ions including protons. Aquaporins (AQPs) has brought inspiration for the development of Artificial Water Channels (AWCs). Imidazole-quartet (I-quartet) was the first AWC that enabled to self-assemble a tubular backbone for rapid water and proton permeation with total ion rejection. Here, we report the discovery of bis-alkylureido imidazole compounds, which outperform the I-quartets by exhibiting ≈3 times higher net and single channel permeabilities (107 H2 O/s/channel) and a ≈2-3 times lower proton conductance. The higher water conductance regime is associated to the high partition of more hydrophobic bis-alkylureido channels in the membrane and to their pore sizes, experiencing larger fluctuations, leading to an increase in the number of water molecules in the channel, with decreasing H-bonding connectivity. This new class of AWCs will open new pathways toward scalable membranes with enhanced water transport performances.

Simulating 2,4,6-trinitrotoluene (TNT) elimination in a pond inhabited by freshwater algae of the Rhizoclonium genus

Military operations over large areas of Ukraine lead to release of explosives and their derivatives into the environment with subsequent accumulation in natural and artificial water bodies, which unwittingly serve as reservoirs for collecting pollutants from the catchment area. The need to restore aquatic ecosystems dictates the search for efficient, cost-effective and environmentally friendly methods for the elimination of explosives, which corresponds to the processes of biological treatment. In this work, we examined the ability of common freshwater algae of the genus Rhizoclonium to detoxify 2,4,6-trinitrotoluene (TNT) under model conditions of water pollution (at a TNT concentration of 100 mg/L). The exposure time of the algae to TNT was 48 hours, during which the content of TNT and nitrites in the aqueous medium was monitored, as well as the content of chlorophyll and the activity of glutathione S-transferase in plant tissues. 2,4,6-trinitrotoluene was extracted from the aqueous medium with toluene, followed by separation in a separatory funnel, removal of residual water with sodium sulfate, and reduction of the extract volume using a rotary evaporator. The decrease in the concentration of TNT, established by GC-MS technique, was 66.4% by the end of the experiment, while the content of nitrites increased almost 15-fold. In the algae cells, a threefold increase in the enzymatic activity was observed already in the second hour of exposure, followed by a gradual decrease and maintenance at a level of 50% of the control until the end of the experiment. The total chlorophyll content increased significantly from the sixth hour of exposure to the end of the experiment due to an increase in the content of chlorophyll b. The results obtained indicate the efficient biodegradation process and prospects of using algae of the genus Rhizoclonium for cleaning water bodies contaminated with TNT.

Impact of the antibiotic doxycycline on the D. magna reproduction, associated microbiome and antibiotic resistance genes in treated wastewater conditions

Wastewater Treatment Plant (WWTP) effluents are important sources of antibiotics, antibiotic resistance genes (ARGs) and resistant bacteria that threaten aquatic biota and human heath. Antibiotic effects on host-associated microbiomes, spread of ARGs and the consequences for host health are still poorly described. This study investigated changes of the Daphnia magna associated microbiome exposed to the recalcitrant antibiotic doxycycline under artificial reconstituted lab water media (lab water) and treated wastewater media. D. magna individual juveniles were exposed for 10 days to treated wastewater with and without doxycycline, and similarly in lab water. We analysed 16 S rRNA gene sequences to assess changes in community structure, monitored Daphnia offspring production and quantified ARGs abundances by qPCR from both Daphnia and water (before and after the exposure). Results showed that doxycycline and media (lab water or wastewater) had a significant effect modulating Daphnia-associated microbiome composition and one of the most discriminant taxa was Enterococcus spp. Moreover, in lab water, doxycycline reduced the presence of Limnohabitans sp., which are dominant bacteria of the D. magna-associated microbiome and impaired Daphnia reproduction. Contrarily, treated wastewater increased diversity and richness of Daphnia-associated microbiome and promoted fecundity. In addition, the detected ARG genes in both lab water and treated wastewater medium included the qnrS1, sul1, and blaTEM, and the integron-related intI1 gene. The treated wastewater contained about 10 times more ARGs than lab water alone. Furthermore, there was an increase of sul1 in Daphnia cultured in treated wastewater compared to lab water. In addition, there were signs of a higher biodegradation of doxycycline by microbiomes of treated wastewater in comparison to lab water. Thus, results suggest that Daphnia-associated microbiomes are influenced by their environment, and that bacterial communities present in treated wastewater are better suited to cope with the effects of antibiotics.

Water use strategy of nitraria tangutorum shrubs in ecological water delivery area of the lower inland river: Based on stable isotope data

Excessive water use in the upper and middle reaches of arid inland river basins will inevitably lead to the drying up of the lower reaches. Water allocation and ecological water delivery have been widely used as water resources management strategies in global arid regions, and the implementation of such strategies has a great impact on the downstream ecosystem. We established an ecohydrological observation system at the lower reaches of the Shiyang River, an inland river in the arid region of China. The stable hydrogen and oxygen isotope technique was used to study the influence mechanism of artificial water delivery on the water use strategy of nitraria tangutorum shrubs, the typical dominant species around Qingtu Lake. The results showed that: (1)12.33% of the water used by the dominant species in the terminal lake area came directly from ecological water delivery, 77.88% from soil water formed by water delivery, and only 9.79% from precipitation. (2)With the increase of distance, nitraria tangutorum shrubs absorbed less surface soil water and lake water, and gradually turned to using deeper soil water and precipitation. (3) Ecological water delivery cycles affected the water use strategies of nitraria tangutorum shrubs. The proportion of deep soil water used by plants increased in the non-water delivery period, and the proportion of precipitation absorbed by plants also increased. Thus, Vegetation in the terminal lake region mainly depended on ecological water use, and the amount and time of water delivery directly determined the water use of dominant species. The results help us to understand the adaptation mechanism of plants under the background of artificial water delivery in the low reaches of arid inland river basins and provide a reference for the rational use of water resources and ecological construction.

Impact of urbanization factors considering artificial water dissipation on extreme precipitation: A numerical simulation of rainfall in Shanghai

AbstractClimate change and rapid urbanization have jointly altered the climate characteristics of cities, including rainfall, humidity, and temperature, and have resulted in an increase of extreme precipitation. In this study, to identify the hydrothermal driving factors responsible for extreme precipitation in urban areas, sensitivity experiments were carried out on two extreme precipitation events in Shanghai, China, using the weather research and forecasting (WRF) model coupled with the artificial water dissipation urban canopy model (AWDUCM). The simulation results from the WRF model and observations from 35 weather stations across Shanghai were compared. The results showed that WRF could simulate the spatial distribution and precipitation intensity of extreme rainfall more accurately when integrated with the AWDUCM. With the AWDUCM incorporated, the root‐mean‐square errors of the two simulated precipitation events were 9.1 and 9.9 mm respectively (accounting for approximately 20% of the total rainfall). The near‐surface temperature and specific humidity in the AWDUCM simulation were approximately 0.5°C and 1 g·kg−1 higher than in the NON simulation (that did not invoke the AWDUCM) respectively. Urbanization factors increase the near‐surface temperature and specific humidity in urban and built‐up land, and the results of this study indicate that these are two of the driving forces affecting precipitation. Increased water vapor and urban heat island effects caused by urbanization are enhancing the intensity of extreme precipitation in Shanghai.

GRACE Data Quantify Water Storage Changes in the Shiyang River Basin, an Inland River in the Arid Zone

Global changes and human activities have significantly altered water cycle processes and water resource patterns in inland river basins in arid zones. New tools are needed to conduct more comprehensive and scientific assessments of basin water cycle processes and water resource patterns. Based on GRACE satellite and Landsat data, this study investigated terrestrial water storage changes and surface water area in the Shiyang River Drainage Basin from 2002 to 2021. It explored the effects of climate change and water conservancy construction on terrestrial water storage changes in the basin. The results of the study show that, although the surface water quantity in the Shiyang River basin has increased in the past 20 years, the overall decreasing trend of terrestrial water storage in the basin of the Shiyang River has an interannual decreasing rate of 0.01 cm/a. The decreasing trend of water storage in the midstream and downstream areas is more prominent. The change in precipitation controls the change in water storage in the Shiyang River Drainage Basin. Artificial water transfer has changed the spatial distribution of water resources in the basin of the Shiyang River. However, it still has not completely reversed the trend of decreasing water storage in the middle and lower reaches of the Shiyang River.

Are rotifer indices suitable for assessing the trophic status in slow-flowing waters of canals?

Abstract Zooplankton indicators based on rotifers (TSIROT) and an indicator based on Secchi disk visibility (TSISD) were used to assess trophic state changes in artificial, slow-flowing, and stagnant canal waters. The study was conducted in the summers of 2019, 2021, and 2022 in the Bydgoszcz Canal and the Noteć Canal (Poland). Water samples were taken from five sites once in the month of July and once in August. In terms of the species number and density, rotifers dominated among zooplankton (at almost all sites), which reflected the high trophic state. Our results showed statistically significant correlations between TSIROT and TSISD as well as between the individual indicators TSIROT1 (Rotifer numbers), TSIROT2 (Rotifer biomass), TSIROT3 (bacterivorous numbers of rotifers), TSIROT6 (rotifers indicating high trophic state), and TSISD. According to our study, the presented indices most likely determine the trends between TSIROT cumulative and TSISD in the studied canals. Similarly to previous studies performed on lakes and small reservoirs, zooplankton constituted a useful indicator of trophic state. It seems that, for stagnant and slowly flowing waters of canals such as the Bydgoszcz Canal and the Noteć Canal, the method of zooplankton trophic status indicators based on rotifers may be applied.

Prevalence and Characterization of Legionella pneumophila and Related Species from Water-Based Recreational Sites

Abstract Background and Objectives Legionella is a genus of gram-negative bacteria common in soil and aquatic systems and is associated with protists. They have emerged as a pathogenic group due to the increased use and poor maintenance of artificial water environments. This study aims at phenotypic and molecular identification of Legionella in water and swab samples collected from water-based recreational sites. The biofilm-forming ability of Legionella on exposure to various temperatures and iron concentrations was also studied. Methods A total of 60 samples including 30 swab samples and 30 water samples (decorative fountain ponds, swimming pools, garden sprinklers, drip irrigation system) were collected from in and around Mangalore, Karnataka, India. From each source, swab and water samples were collected as per the Indian standard IS: 1622. The collected samples were processed within 4 hours of collection. The samples were subjected to microbiological and chemical estimation followed by filtration through a 0.2 µm membrane filter. Isolation of Legionella from collected samples was performed as per US Centers for Disease Control and Prevention guidelines 2005. The positive isolates were then checked for biofilm-forming ability at various temperatures (25°C, 35°C, and 45°C) and iron concentration (3 mg/L, 30 mg/L, and 300 mg/L) using crystal violet assay. Results Out of 30, water and swab samples tested, one water sample from a garden sprinkler, swimming pool, and one from both water and swab samples from a decorative fountain showed the presence of Legionella. A biofilm study of Legionella at various temperatures and iron concentrations categorized the bacteria as a moderate biofilm former. Conclusion This study revealed that most of the water and swab samples were found to be negative for Legionella that is quite encouraging and the contamination of water systems in recreational facilities can be reduced by decontamination techniques and proper hygienic practices.

Artificial Water Channel that Couples with Cell Protrusion Formation

Artificial Water Channel that Couples with Cell Protrusion Formation

Assessing the impacts of dam/weir operation on streamflow predictions using LSTM across South Korea

Recently, weather data have been applied to one of deep learning techniques known as “long short-term memory (LSTM)” to predict streamflow in rainfall-runoff relationships. However, this approach may not be suitable for regions with artificial water management structures such as dams and weirs. Therefore, this study aims to evaluate the prediction accuracy of LSTM for streamflow depending on the availability of dam/weir operational data across South Korea. Four scenarios were prepared for 25 streamflow stations. Scenarios #1 and #2 used weather data and weather and dam/weir operational data, respectively, with the same LSTM model conditions for all stations. Scenarios #3 and #4 used weather data and weather and dam/weir operational data, respectively, with the different LSTM models for individual stations. The Nash–Sutcliffe efficiency (NSE) and the root mean squared error (RMSE) were adopted to assess the LSTM’s performance. The results indicated that the mean values of NSE and RMSE were 0.277 and 292.6 (Scenario #1), 0.482 and 214.3 (Scenario #2), 0.410 and 260.7 (Scenario #3), and 0.592 and 181.1 (Scenario #4), respectively. Overall, the model performance was improved by the addition of dam/weir operational data, with an increase in NSE values of 0.182–0.206 and a decrease in RMSE values of 78.2–79.6. Surprisingly, the degree of performance improvement varied according to the operational characteristics of the dam/weir, and the performance tended to increase when the dam/weir with high frequency and great amount of water discharge was included. Our findings showed that the overall LSTM prediction of streamflow was improved by the inclusion of dam/weir operational data. When using dam/weir operational data to predict streamflow using LSTM, understanding of their operational characteristics is important to obtain reliable streamflow predictions.

Biomanipulation of Periphytic Algae in the Middle Route of South–North Water Diversion Project Canal: An In Situ Study in the Lushan Section

The biomanipulation technique has been developed and implemented for decades, yielding favorable results in various lakes both domestically and globally. This technology uses fish to reduce algae biomass, giving a natural and environmentally friendly solution to improve water quality. The effectiveness of biomanipulation technology in large-scale artificial water canals, on the other hand, has been unclear. To address this, from 15 December 2019 to 30 April 2020, an in situ experimental study on the biomanipulation of periphytic algae was conducted in the Lushan section of the main canal of the Middle Route of the South-to-North Water Diversion Project (MSNWDP). The study aimed to verify the control effect of fish on periphytic algae. Various combinations of Megalobrama terminalis and Xenocypris davidi were fixed on the canal with a triangular cylindrical cage, and their feeding effects on periphytic algae were observed. The results showed that the density of periphytic algae at the bottom of the cages was substantially lower than before the experiment, with a 68.75% average reduction. We graded the food-filling results based on the amount of digestive tract content, which was represented using Arabic numerals ranging from 0 to 5. The study discovered that M. terminalis had the best adaptability to the environment, with full intestines primarily composed of periphytic algae and a food-filling degree between grades 4 and 5. X. davidi, on the other hand, had a food-filling degree of 0. Furthermore, the weight of each M. terminalis increased significantly following the experiment, whereas the weight of each X. davidi decreased to varying degrees. Additionally, the study highlights the importance of selecting the appropriate fish species for biomanipulation, as different species may have varying levels of effectiveness in controlling periphytic algae. Overall, this study provides valuable insights into the potential of biomanipulation technology in large-scale artificial water canals and other water conservancy projects.

Dual-ligand two-dimensional terbium-organic frameworks nanosheets for ratiometric fluorescence detection of phosphate

Here, we reported a ratiometric fluorescence strategy for the detection of phosphate (Pi) in artificial wetland water. The strategy was based on dual-ligand two-dimensional terbium-organic frameworks nanosheets (2D Tb-NB MOFs). 2D Tb-NB MOFs were prepared through blending 5-boronoisophthalic acid (5-bop), 2-aminoterephthalic acid (NH2-BDC) and Tb3+ ions at room temperature in the presence of triethylamine (TEA). The dual-ligand strategy realized dual emission originated from ligand NH2-BDC and Tb3+ ions at 424 and 544 nm, respectively. Pi could compete with ligands to coordinate Tb3+ due to the strong binding ability between Pi and Tb3+, resulting in structural destruction of 2D Tb-NB MOFs, so static quenching and antenna effect between ligands and metal ions were interrupted, and emission at 424 nm was enhanced and emission at 544 nm was weakened. This novel probe had excellent linearity with Pi concentrations from 1 to 50 μmol/L; the detection limit was 0.16 μmol/L. This work revealed that mixed ligands improved sensing efficiency of MOFs by enhancing the sensitivity of the coordination between the analyte and MOFs.

Coagulation–flocculation of aquaculture effluent using biobased flocculant: From artificial to real wastewater optimization by response surface methodology

Coagulation–flocculation is currently the best practice for aquaculture effluent treatment, and biobased compounds are emerging as coagulant/flocculants. This study aimed to characterize the bioflocculant produced from Serratia marcescens and applied it to treat artificial turbid water (kaolin substrate) and real aquaculture effluent using the combination of one variable at a time (OVAT) and response surface methodology (RSM) analyses. The bioflocculant produced by S. marcescens was characterized as anionic flocculant with isoelectric point at pH 1.7 and 13.3. At pH 7, its protein content was 1.3 μg/mL, and its total carbohydrate level was 0.53 mg/L. The bioflocculant consisted of various carboxylic acids and enzyme intermediates, indicating the presence of polysaccharides and protein. Comparison of optimized treatment conditions between OVAT and RSM showed that rapid mixing speed, slow mixing time, and sedimentation time were the most influential factors for coagulation–flocculation. The aquaculture effluent required lower rapid mixing speed (125 rpm) and shorter sedimentation time (39 min) than artificial wastewater (160 rpm and 67 min, respectively). The low performance of the bioflocculant in treating aquaculture effluent was due to the more complex characteristics of real aquaculture effluent compared with those of kaolin substrate. Environmental implicationsThe characterization of bioflocculant produced by Serratia marcescens in terms of its protein level, total carbohydrate content, and isoelectric point has never been reported. The obtained results may provide an insight into the potential of this compound to substitute widely used chemical flocculants with reliable performance. The findings may also be used as a basis to upscale coagulation–flocculation from being applied to artificial wastewater in the laboratory to treating real wastewater, especially with the use of biobased compounds.

Toxicology studies involving optimization of soil contaminated with spent engine oil using leaves of maize

The effect of spent engine oil-contaminated soil on morphological and biochemical properties of Zea mays (maize) was investigated. Thirty polythene pots with drainage holes at the bottom, each containing 10 kg of surface soil, were randomly placed on a table in the greenhouse in a factorial combination of five treatment levels (5 ml, 10 ml and 15 ml) of spent engine oil and additional three variants of each with pH adjustment to 5.5, 7 and 8.5 and were designated S0 for Control, S5 for soil containing 5 ml engine oil with no pH adjustment and S5A, S5B and S5C for pH adjustment to 5.5, 7.0 and 8.5 respectively. Three seeds of maize per pot were planted. Growth parameters (plant height, stem girth, relative water content (RWC), selected leaf properties (chlorophyll content (SPAD value) and soluble protein content (SPC)) and antioxidant indices were determined in the corn over a period of eight weeks after planting (WAP). The maize planted in contaminated soil with pH adjustment recorded significantly higher height than their corresponding contaminated soil without pH adjustment (p<0.05). The girth of plant decreased with increased concentration of contaminant (spent engine oil). SPC of Control (S0) is significantly higher (p<0.05) than any of the maize planted in soil contaminated with spent engine oil. Generally, activities of antioxidant enzymes of Control were significantly lower (p<0.05) than those of maize planted in soil contaminated with spent engine oil. It could be inferred that spent engine oil in soil hindered the growth and development of maize, it created artificial water deficit to cellular system of maize and induced a condition of oxidative stress. However, maize planted in soil amended to pH 5.5 recorded favourable biochemical indices.

Landsat Satellite Image-Derived Area Evolution and the Driving Factors Affecting Hulun Lake from 1986 to 2020

The area fluctuation of lakes directly affects the stability of the surrounding ecological environment. Research on the area evolution of lakes and the driving factors affecting it plays an important role in sustainable water resource management. In this study, Hulun Lake, located in the Hulunbuir grassland, was taken as the research object. Based on remote sensing images of the Hulun Lake area from 1986 to 2020, MNDWI interpretation was used to obtain the change law of lake surface area over a long time frame. Combined with natural factors and anthropogenic factors, Pearson correlation analysis and principal component analysis were used to analyze the driving force. The results showed that (1) in the past 35 years, the water surface area of Hulun Lake has decreased significantly. The dynamic change in water area could be divided into four stages. The areas with dramatic changes in water area are distributed mainly in the northeast and south of Hulun Lake. (2) In terms of natural factors, the meteorological factors based on evaporation and relative humidity, the runoff of rivers entering the lake, and the vegetation with medium-high coverage and medium-low coverage had significant effects. In terms of anthropogenic factors, the population had the most significant impact. The artificial water diversion project had different degrees of influence on the response of the Hulun Lake area change to natural factors. (3) Anthropogenic factors were the main driving force causing the rapid change in the Hulun Lake area from 2000 to 2016, explaining 48% of the change in the Hulun Lake area. These research results can provide a scientific basis for the development and utilization of water resources and sustainable development in the Hulun Lake area.

Lightning Protection of Floating Photovoltaic Power Plants—Simulation Analysis of Sample Solutions

Photovoltaic power plants are gaining in popularity and availability every year, resulting in a massive increase in their number and size. However, each such investment involves allocating large land areas, the cost of which may be high. For this reason, there has been an increasing interest in the use of post-industrial wastelands in the form of artificial water reservoirs which often occupy large areas. Because their use as places of recreation can be dangerous for people, it is a cheap alternative for the foundation of a floating photovoltaic power plant. In addition, it has an advantage over the land version in that it is possible to produce a more significant amount of energy by using the sun’s rays reflected from the water’s surface. Despite these undeniable advantages, such a structure poses several technological challenges. This article focuses on the aspect of lightning protection, which is particularly important due to the structure’s location in the open, and also a specific ground type with noticeably different mechanical and electrical characteristics than typical soil. Aspects such as the lightning hazard, arrangement of lightning rods, down conductors, lightning equipotential bonding, and various earthing configurations are discussed. The presented analysis is based on geometric models and simulations made in the Ansys/Maxwell 3D environment and is supplemented with calculations in Matlab/Simulink.

Immunomagnetic separation coupled with flow cytometry for the analysis of Legionella pneumophila in aerosols

Legionella pneumophila are pathogenic bacteria that can be found in high concentrations in artificial water systems like evaporative cooling towers, which have been the source of frequent outbreaks in recent years. Since inhaled L. pneumophila can lead to Legionnaires’ disease, the development of suitable sampling and rapid analysis strategies for these bacteria in aerosols is therefore of great relevance. In this work, different concentrations of viable L. pneumophila Sg 1 were nebulized and sampled by the cyclone sampler Coriolis® µ under defined conditions in a bioaerosol chamber. To quantify intact Legionella cells, the collected bioaerosols were subsequently analyzed by immunomagnetic separation coupled with flow cytometry (IMS-FCM) on the platform rqmicro.COUNT. For analytical comparison, measurements with qPCR and cultivation were performed. Limits of detection (LOD) of 2.9 × 103 intact cells m−3 for IMS-FCM and 7.8 × 102 intact cells m−3 for qPCR indicating a comparable sensitivity as in culture (LOD = 1.5 × 103 culturable cells m−3). Over a working range of 103 − 106 cells mL−1, the analysis of nebulized and collected aerosol samples with IMS-FCM and qPCR provides higher recovery rates and more consistent results than by cultivation. Overall, IMS-FCM is a suitable culture-independent method for quantification of L. pneumophila in bioaerosols and is promising for field application due to its simplicity in sample preparation.Graphical abstract