Search Results (66)

Diatoms have been widely used for aquatic environment assessment. However, the progress of diatom research is uneven in different regions of the world. This study gathered both Chinese and English articles on diatom research in the Yangtze River Basin in order to explore recent progress in this field. Using the Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases, we gathered 419 articles (1995–2024) on diatom research in the Yangtze River Basin. There is a substantial increase in the number of articles since 2000. Since the mid-1990s, a total of 63 new diatom species have been identified in this region. Based on limnological investigations of lakes in the Yangtze River Basin, diatom-based conductivity and total phosphorus (TP) transfer functions have been developed for quantitative reconstruction of past conductivity and TP in the water column. The results revealed a recent shift in thematic focus from eutrophication to biodiversity dynamics, the ecosystem regime shift, and ecohydrological change. Although diatom research in the Yangtze River Basin has achieved fruitful outputs, further studies are urgently needed to explore diatom biodiversity and the ecological status of aquatic ecosystems in this rapidly-developing region. The results can improve our understanding of diatom research progress and hence provide important clues for further studies. Full article

Benthic diatoms are being used as indicators to assess the biological quality of surface waters in Kosovo. The Klina River is the left tributary of the White Drin River Basin, with a length of 69 km. The study assessed the level of surface water quality in the Klina River using 12 diatomic indices calculated with the Omnidia program. For this purpose, three stations monitored the river Klina in the autumn of 2021 to conform to international standards. A total of 88 diatom taxa were identified, with the dominant species being Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot, Gyrosigma acuminatum (Kützing) Rabenhorst, Cocconeis placenula Ehrenberg, Gomphonema minutum (Ag.) Agardh f. minutum, Gomphonema clavatum Ehr, Meridion circulare (Greville) C.A. Agardh, Cocconeis pediculus Ehrenberg, Diatoma vulgaris Bory, and Nitzschia dissipata (Kützing) Grunow ssp. dissipata etc. This study assessed the surface water quality in the Klina River using diatom indices, indicating that the river is in good to moderate ecological condition. Environmental variables such as hydrogen ion concentration (pH) and dissolved oxygen (DO) had significant positive correlations (<0.01) with the biological diatom index (IBD), Descy’s pollution metric (Descy), Sladeček’s pollution metric (SLA), the European index (CEE), and Watanabe’s Index (WAT), while the total suspended solids (TSS) also showed a strong negative significant correlation (<0.01) with the generic diatom index (IDG), Indice Diatomique Artois Picardie (IDAP), the eutrophication pollution index (EPI-D), the trophic diatom index (TDI), the Pampean diatom index (IDP), and Steinberg and Schiefele’s index (SHE). Total phosphorus (TP), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) presented a significant negative correlation (<0.05) with the IBD, Descy, SLA, CEE, and WAT indices. Our findings provide insights for organizations dealing with the state of the environment and water protection in Kosovo, and these results can be used as a starting point for assessing the ecological quality of water and monitoring environmental pollution in the Kosovo region. Full article

This research presents a significant contribution to the methodologies and protocols for studying diatom communities in cryoconite holes on glaciers. Cryoconite holes are unique microenvironments found on glacial surfaces that support intricate microbial ecosystems, with diatoms playing a pivotal role in these communities. The refined methodologies developed in this study include optimizing sampling techniques to ensure that collections are both representative and diverse, which is crucial for accurate ecological assessments. Additionally, advanced digestion processes have been implemented to effectively isolate and purify diatom samples while minimizing contaminants, thereby improving sample integrity. Improved microscopic mounting techniques enhance visual clarity, facilitating more precise identifications of diatoms under the microscope. Furthermore, integrating DNA-based taxonomy broadens the taxonomic scope, providing valuable molecular insights into the diversity and evolutionary relationships of diatoms. Collectively, these protocols aim to enhance the reliability, depth, and multidimensional understanding of diatom ecology in cryoconite holes and broader glacial ecosystems, ultimately contributing to the field of glaciology and microbial ecology. Full article

Microalgae in planktonic communities are the main producers of biomass in lake ecosystems; however, their stability is influenced by many environmental factors. This study aims to assess the ecological state of Lake Maybalyk, located in Astana (Kazakhstan), based on the study of the taxonomic diversity and structure of phytoplankton, zooplankton, and the physico-chemical properties of the water. From 2019 to 2021, samples were taken for phytoplankton analysis, hydrochemical analysis of the water, zooplankton, and saprobiological analysis of the algocenosis. The study also investigated the main morphometric parameters of the lake, as well as the composition of hydrobionts, such as zooplankton, zoobenthos, and ichthyofauna. The analysis of phytoplankton revealed the presence of 97 species and intraspecific taxa of microalgae, with 71 types of microalgal indicators indicating water saprobity. The planktonic algoflora in Lake Maybalyk is predominantly composed of diatoms (Bacillariophyta) and green algae (Chlorophyta), which play a vital role in oxygen production and the food chain within the reservoir. Based on the Pantle–Buck saprobity index (2.15–2.5), the water quality in Lake Maybalyk is classified as moderately polluted. The assessment of the water quality, considering the number and composition of indicator phytoplankton species, places Lake Maybalyk in class III (β-mesosaprobic). The hydrochemical indicators align with the hydrobiological indicators, confirming the water quality as class III. The trophic status of the reservoir, during the study period, can be described as average. The obtained data on both the hydrobiological and hydrochemical indicators correlate, suggesting satisfactory water quality and the ability of the reservoir to purify itself. This study contributes to the sustainable management of water resources, by providing essential data on the ecological state of Lake Maybalyk. The results underscore the importance of continuous biomonitoring, with microalgae as indicators of water quality, which is crucial for developing effective ecosystem conservation strategies. Full article

Detecting the quantity and diversity of diatoms is of great significance in areas such as climate change, water quality assessment, and oil exploration. Here, an efficient and accurate object detection model, named SC-DiatomNet, is proposed for diatom detection in complex environments. This model is based on the YOLOv3 architecture and uses the K-means++ algorithm for anchor box clustering on the diatom dataset. A convolutional block attention module is incorporated in the feature extraction network to enhance the model’s ability to recognize important regions. A spatial pyramid pooling module and adaptive anchor boxes are added to the encoder to improve detection accuracy for diatoms of different sizes. Experimental results show that SC-DiatomNet can successfully detect and classify diatoms accurately without reducing detection speed. The recall, precision, and F1 score were 94.96%, 94.21%, and 0.94, respectively. It further improved the mean average precision (mAP) of YOLOv3 by 9.52% on the diatom dataset. Meanwhile, the detection accuracy was improved compared with those of other advanced deep learning algorithms. SC-DiatomNet has potential applications in water quality analysis and monitoring of harmful algal blooms. Full article

This paper assessed the phytoplankton structure and its relationship with the physical environment in the coastal region off Mazatlán, Mexico, in two seasons of 2022, a year in which a strong La Niña event took place: (1) the warmer (August) and (2) the transitional period to the cold phase (November), based on hydrographic data and samples collected in two systematic scientific expeditions. The results showed clear differences between both seasons. Regarding total abundance, August reached 125,200 cells L⁻¹, while November amounted to 219,900 cells L⁻¹. Regarding species composition, the diatoms Cylindrotheca closterium and Planktoniella sol were dominant in August, while Thalassionema nitzschioides and Tetramphora decussata dominated the assemblages in November. The dinoflagellate Protoperidinium punctulatum was dominant in both seasons. However, very marked differences in its abundance are reported. The differences observed in the species richness and abundance could be attributed to the physical configuration of the water column, particularly the surface temperature, which showed clear changes between both seasons. The results presented here confirmed the high phytoplankton richness (some of them with the potential to generate harmful algal blooms), abundance, and diversity values of the region, suggesting a strong relationship with the physical environment. Full article

Tufa deposits in karst rivers are unique habitats created by mutual interactions between specific environmental and biotope features and inhabited by diatoms as a highly abundant and diverse algal group. This pilot study aimed to investigate the diversity of diatom communities on tufa depositing habitats and assess the Una River’s ecological status using a comparative molecular and morphological approach for diatom identification. The 312 base pairs of the rbcL gene were barcoded and analyzed using MiSeq reads and amplicon sequence variants (ASVs) obtained by the DADA2 pipeline. The reference database Diat.barcode v7 was used for taxonomic assignment. The morphological identification of the diatoms was carried out in parallel. In total, the combined dataset revealed 46 taxa identified at genus rank, 125 on the subgenus, and 145 on combined taxonomy rank. The metabarcoding approach mostly leads to a lower number of identified taxa at species rank (58 in molecular vs. 119 in optical inventory), resulting in higher values of beta diversity and heterogeneity in diatom assemblages in samples obtained by morphological approach. Despite the high percentage of taxonomically not assigned diatom ASVs to the species rank, high Shannon diversity index values and a similar number of taxa per locations compared to the morphological approach were obtained. Taxa Achnanthidium minutissimum (Kützing) Czarnecki, Achnanthidium pyrenaicum (Hustedt) H.Kobayasi, Amphora pediculus (Kützing) Grunow, Diatoma vulgaris Bory, Navicula cryptotenella Lange-Bertalot, and Navicula tripunctata (O.F.Müller) Bory were identified at all locations in both inventories. Although limited consistency in the diatom abundances between the two inventory datasets was found, a similar grouping of samples was observed connected to the river’s longitudinal gradient. The data obtained using molecular approach in most sites indicated a mostly lower ecological status (good or moderate) compared to the data obtained from the morphological approach (high, good, and moderate). The potential of environmental DNA (eDNA) diatom metabarcoding for water monitoring and diversity studies is undeniable, but to fully realize the benefits of these methods in the future, it is essential to standardize protocols and expand the reference database for species found in specific habitats, such as tufa deposits. Full article

In recent years, tubular nanostructures have been related to immense advances in various fields of science and technology. Considerable research efforts have been centred on the theoretical prediction and manufacturing of non-carbon nanotubes (NTs), which meet modern requirements for the development of novel devices and systems. In this context, diatomic inorganic nanotubes formed by atoms of elements from the 13th group of the periodic table (B, Al, Ga, In, Tl) and nitrogen (N) have received much research attention. In this study, the elastic properties of single-walled boron nitride, aluminium nitride, gallium nitride, indium nitride, and thallium nitride nanotubes were assessed numerically using the nanoscale continuum modelling approach (also called molecular structural mechanics). The elastic properties (rigidities, surface Young’s and shear moduli, and Poisson’s ratio) of nitride nanotubes are discussed with respect to the bond length of the corresponding diatomic hexagonal lattice. The results obtained contribute to a better understanding of the mechanical response of nitride compound-based nanotubes, covering a broad range, from the well-studied boron nitride NTs to the hypothetical thallium nitride NTs. Full article

This paper reviews the evolution and integration of diatom-based water quality assessments with environmental DNA (eDNA) techniques for advancing river ecosystem health evaluations. Traditional methods, relying on microscopy and diatom indices, have significantly contributed to our understanding of aquatic ecosystems but face challenges such as the need for taxonomic expertise and the labor-intensive nature of sample collection. Recent advancements in molecular biology, particularly eDNA analysis, offer opportunities to overcome these limitations, providing more accurate and comprehensive assessments. This study highlights the benefits of combining traditional microscopy with modern molecular techniques, enhancing the precision and efficiency of water quality evaluations. By addressing the challenges of standardizing methods and improving species identification through comprehensive reference libraries and advanced bioinformatics tools, this integrated approach aims to refine and advance the effectiveness of diatom-based strategies in monitoring and managing river health amidst environmental changes. Full article

Trafficability gives tracked vehicles adaptability, stability, and propulsion for various purposes, including deep-sea research in rough terrain. Terrain characteristics affect tracked vehicle mobility. This paper investigates the soil mechanical interaction dynamics between rubber-tracked vehicles and sedimental soils through controlled laboratory-simulated experiments. Focusing on Bentonite and Diatom sedimental soils, which possess distinct shear properties from typical land soils, the study employs innovative user-written subroutines to characterize mechanical models linked to the RecurDyn simulation environment. The experiment is centered around a dual-tracked crawler, which in itself represents a fully independent vehicle. A new three-dimensional multi-body dynamic simulation model of the tracked vehicle is developed, integrating the moist terrain’s mechanical model. Simulations assess the vehicle’s trafficability and performance, revealing optimal slip ratios for maximum traction force. Additionally, a mathematical model evaluates the vehicle’s tractive trafficability based on slip ratio and primary design parameters. The study offers valuable insights and a practical simulation modeling approach for assessing trafficability, predicting locomotion, optimizing design, and controlling the motion of tracked vehicles across diverse moist terrain conditions. The focus is on the critical factors influencing the mobility of tracked vehicles, precisely the sinkage speed and its relationship with pressure. The study introduces a rubber-tracked vehicle, pressure, and moisture sensors to monitor pressure sinkage and moisture, evaluating cohesive soils (Bentonite/Diatom) in combination with sand and gravel mixtures. Findings reveal that higher moisture content in Bentonite correlates with increased track slippage and sinkage, contrasting with Diatom’s notable compaction and sinkage characteristics. This research enhances precision in terrain assessment, improves tracked vehicle design, and advances terrain mechanics comprehension for off-road exploration, offering valuable insights for vehicle design practices and exploration endeavors. Full article

Solid biomass is usually simulated by decomposing it into a solid phase (carbon, ash, and sulfur) and a gas phase (water and diatomic molecules of H₂, N₂, O₂, and Cl₂) from the proximate and ultimate analysis before entering a reactor operating under chemical equilibrium when using Aspen Plus. However, this method prevents the use of energy integration for the feed stream from the system inlet to the reactor. This paper proposes an approach to solving this issue, considering biomass with both known and unknown chemical compositions; the latter involves the decomposition of biomass into complex molecular compounds. Different process arrangements were assessed to achieve a realistic simulation, and a sensitivity analysis was carried out to examine the effect of the concentration and heating upstream of the reactor, focused on supercritical water gasification (SCWG) of orange peel. This process is very energy-intensive, so the approach is useful for a better calculation of the energy requirement and exergy losses in a plant; these are usually and mainly related to the train of heat exchangers. In addition to this application to SCWG, this approach can be used for any other thermochemical process, such as gasification, pyrolysis, or combustion, and for any real biomass. Upon a base case study using a wet biomass of 10,000 kg/h with 90 wt.% water where the SCWG reaction takes place at 240 bar and 800 °C, if the temperature at the SCWG reactor inlet increases from 350 °C to 400 °C, the heat exchange increases by 57% from 4 MW and by 34% if the water content decreases to 70 wt.%, although more heat relative to the solid is saved. Full article

In urban and agricultural streams, assessing aquatic ecosystem health is critical due to widespread pollution. Traditional methods for evaluating attached diatoms crucial for ecosystem monitoring face limitations such as species misidentification and sample damage. This study was conducted in the Miho River within the Geum River system and highlights the effectiveness of environmental DNA (eDNA) techniques for more accurate and efficient genetic-based analysis than conventional microscopic analysis methods. When eDNA-based assessments were compared with traditional microscopic methods, this study found that eDNA analysis often revealed poorer ecosystem health. Notably, eDNA assessments showed a stronger correlation with phosphorus concentrations, underlining their precision and importance in ecological studies. These findings suggest that eDNA has potential as a valuable tool for comprehensive biomonitoring. However, the use of international genetic barcode databases in eDNA analysis could lead to the identification of unrecorded species in Korea. Therefore, this study recommends developing a localized genetic barcode database and constructing eDNA information through meta-barcoding, focusing on native species. This approach is crucial for enhancing the accuracy and applicability of eDNA-based health assessments in national biomonitoring efforts. Full article

This work is the first in a series, and its purpose is the comprehensive assessment of the ecological state of the Aras River using biological indicators of water quality by diatoms based on species’ ecological preferences, pollution indices, statistics, and ecological mapping. Samples of diatoms and soft algae and measurements of water quality were analyzed at sixteen sampling sites (between 2020 and 2022) along the Aras River. The impact of anthropological activity on the river was monitored concerning water quality, river health, and ecosystem function. The physical and chemical characteristics of the water were measured. The biological properties of the algal periphyton communities, including species composition, were also measured. Based on the studies conducted in this research, 280 species were identified. The most prosperous species were Diatoma vulgaris, Amphora ovalis, Cocconeis placentula, Rhoicosphenia abbre-viatae, Cymbella helvetica, Brevisira arentii, Navicula tripunctata, Nitzschia linearis, Microcystis botrys, Microcystis aeruginosa, Pseudanabaena limnetica, Scenedesmus obliquus, and Pleurosira laevis (a pollution-resistant and salinity-resistant species first found in aquatic habitats in the Aras River). As a result, the empirical data and algal indices showed the river’s lower reaches to be in poor condition. Exploration of the algal assemblage and water chemistry data using computationally unconstrained ordination techniques such as principal component analysis (PCA) and canonical correspondence analysis (CCA) indicated two strong gradients in the data sets. The results support that water body classification is a function of water chemistry and biological and hydrological characteristics, as it is necessary to include pollutant effects on biota since the nature of the receiving waters influences the river’s water quality. Full article

Within the framework of the Interreg Italy–Slovenia programme, the project DuraSoft aimed at testing innovative technologies to improve the durability of traditional wooden structures in socio-ecologically sensitive environments. We focused on the impact of different wood treatments (i.e., copper-based coatings and thermal modification) on microbial biofilm formation in the Grado Lagoon. Wooden samples were placed in 2 areas with diverse hydrodynamic conditions and retrieved after 6, 20, and 40 days. Light, confocal and scanning electron microscopy were employed to assess the treatment effects on the microalgal community abundance and composition. Lower hydrodynamics accelerated the colonisation, leading to higher algal biofilm abundances, regardless of the treatment. The Cu-based agents induced modifications to the microalgal community, leading to lower densities, small-sized diatoms and frequent deformities (e.g., bent apices, frustule malformation) in the genera Cylindrotheca and Cocconeis. After 20 days, taxa forming 3D mucilaginous structures, such as Licmophora and Synedra, were present on chemically treated panels compared to natural ones. While in the short term, the treatments were effective as antifouling agents, in the long term, neither the copper-based coatings nor the thermal modification successfully slowed down the biofouling colonisation, likely due to the stimulating effect of nutrients and other substances released from these solutions. The need to develop more ecosystem friendly technologies to preserve wooden structures remains urgent. Full article

Lake eutrophication due to excessive nutrient enrichment by human activity is one of the most studied ecosystem regime shifts. The suddenness and irreparability of such eutrophication in shallow lakes cause substantial socio-economic losses, especially in fast-developing areas in eastern China. Although eutrophication has been well documented in many lakes, a regional assessment of the eutrophication process is still missing. Here, we provided a regional assessment of water phosphorus changes since 1900 in eutrophic lakes in eastern China using paleolimnological records and diatom-/chironomid-TP transfer functions. We collated the reconstructed water total phosphorus (TP) of ten lakes and reconstructed the other five records based on identified diatom compositions in sediment cores from previous papers. We found three trend types of decrease, increase and fluctuate in the fifteen TP reconstructions according to cluster analysis of the data correlation results. Increase is the dominated trend, in which TP changes are highly correlated. Among eight lakes with an increasing nutrient, the time-series TP data of six lakes fit step functions better than linear regression models, indicating the main non-linear change in lake nutrient levels over time. Our results show how integrating spatial information on a large scale from paleolimnological records highlights the eutrophication process and further benefits current lake management. Full article