Lake Shore Research Articles

Uncovering the Anthropogenic Influences on Water Quality: A Case of Lake Victoria Shores, Entebbe, Uganda

Lakes serve as vital ecosystems, providing freshwater resources and habitats for diverse species. However, human activities, particularly around lakeshores, have led to significant environmental degradation, including heavy metal contamination. Lake Victoria, the second-largest freshwater lake globally, has been severely impacted by pollution from industrial, agricultural, and urban sources. This research aims at examining the influence of the anthropogenic activities on the water quality of Lake Victoria. Specifically, the study tried to determine the activities undertaken at the Lake shores of Lake Victoria; determined the physico-chemical parameters of the water from the shores and the heavy metal concentration in the water samples obtained from the shores of Lake Victoria. This study utilized a cross-sectional and experimental research designs to assess water quality and anthropogenic influences around Lake Victoria. A total of 150 residents from selected communities were surveyed using a semi-structured questionnaire to gather demographic information, perceptions of water quality and the activities carried out within the shores of Lake Victoria. Water samples were collected from multiple sites along the lake shores for analysis of heavy metals using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Water quality parameters were determined In-situ using a multi-parameter water testing kit and Hanna instrument. Results showed that the anthropogenic activities that could have contributed to water degradation include: fishing, transport, agriculture and construction among others. Apart from pH which was outside the permissible limits, all the other water parameters were within the WHO permissible limits. Considering the heavy metal concentration, all the sampled sites apart from one inlet, had the concentrations above the WHO permissible levels an indication of significant heavy metal contamination in the Lake Victoria shores. These findings highlight the urgent need for targeted pollution control measures and regular monitoring to mitigate further environmental degradation. Effective interventions, including stricter regulations and sustainable land use practices within the Victoria shores are essential for safeguarding the lake's ecosystem and the health of surrounding communities.

Habitation conditions of the cave lion in the middle Indigirka River basin, North-East Siberia, during the Middle and Late Pleniglacial: Reconstruction based on palynological data

Pollen analyses of the sediment from skulls cavities of two cave lions Panthera spelaea from the middle Indigirka River basin, North-East Siberia, were performed to reconstruct the habitat conditions of the animals and to estimate changes in vegetation and climatic conditions in the region. Composition of the pollen and non-pollen palynomorphs indicates that the predators most likely died on the river floodplain or near the shore of the thermokarst lake, where grass/sedge meadows and shrub thickets, providing rich grazing grounds for large herbivores, existed. Palynological data indicate that both in the early Middle Pleniglacial and in the LGM the regional vegetation included forest, shrub tundra, meadow, mire and steppe communities similar to modern cold steppes in central Yakutia. During early Marine Isotope Stage (MIS) 3, the participation of arboreal vegetation was greater than in the Last Glacial Maximum (LGM) due to higher summer temperatures. In MIS 2, the role of open herbaceous cryoxerotic communities was greater, which is associated with a higher continentality of climate and a decrease in winter temperatures. This reconstruction is consistent with the general sequence of landscape and climatic changes in the Arctic and Subarctic regions of Siberia in the Middle and Late Pleniglacial, based on paleobotanical studies of the locations of mammoth fauna and multidisciplinary studies of the Late Pleniglacial sediments from a broader area.

Spatially explicit predictions using spatial eigenvector maps

Abstract In this paper, we explain how to obtain sets of descriptors of the spatial variation, which we call “predictive Moran's eigenvector maps” (pMEM), that can be used to make spatially explicit predictions for any environmental variables, biotic or abiotic. It unites features of a method called “Moran's eigenvector maps” (MEM) and those of spatial interpolation, and produces sets of descriptors that can be used with any other modelling method, such as regressions, support vector machines, regression trees, artificial neural networks and so on. The pMEM are the predictive eigenvectors produced by using a distance‐weighting function (DWF) in the construction of MEM. Seven types of pMEM, each associated with one of seven different DWFs, were defined and studied. We performed a simulation study to determine the power of different types of pMEM eigenfunctions at making accurate predictions for spatially structured variables. We exemplified the application of the method to the prediction of the spatial distribution of 35 Oribatid mites living in a peat moss (Sphagnum) mat on the shore of a Laurentian lake. We also provide an R language package called pMEM to make calculations easily available to end users. The results indicate that anyone of the pMEMs obtained from the different DWFs could be the best suited one to predict spatial variability in a given data set. Their application to the prediction of mite distributions highlights the capability of pMEMs for predicting distributions, and for providing spatially explicit estimates of environmental variables that are useful for predicting distributions.

The material relating to the anatomy of Rhaponticum serratuloides leaf blades according to age conditions

In the article the features of the morphological and anatomical structure of leaf blades in the process of ontogenesis of Rhaponticum serratuloides Georgi (Bobr.) during juvenile, immature, virginal, generative and senile age states were presented. It was noted that as the plant matures, the degree of dissection and linear dimensions of the leaf blades, as well as their vascular bundles and trichomes, increase. It was established that in the juvenile and immature periods of development whole and elliptical leaves predominate. In the virginal state, in addition to the typical entire leaves, leaves with an unpaired pinnate leaf blade appear. The generative state of Rh. serratuloides is characterized by having upper leaves as entire, sessile; the lower ones are petiolate, pinnately lobed with a large apical lobe. In the senile state, leaves of immature and virginal types are found. General patterns of leaf internal structure of Rh. serratuloides and another representative of the same genus Rh.carthamoides Willd (Iljin) were revealed as following: the plants are of dorsal-ventral type of leaf blade structure, with collateral vascular bundles of a closed type with a sclerenchyma covering and leaf pubescence. Along with this, characteristic diagnostic features for leaves of Rh. serratuloides were described as the following: the absence of capitate glands and long cord-like hairs during all age states, the presence of air-bearing cavities in the parenchyma of virginal and senile plants, associated with the habitat of the plant under study, because it grows in flooded meadows, along the shores of lakes and swamps.

КАЛЬДЕРА КРАШЕНИННИКОВА (ВОСТОЧНАЯ КАМЧАТКА): ВОЗРАСТ И МАГНИТУДА ИЗВЕРЖЕНИЯ

New data on the composition of the pyroclastic deposits of the Krasheninnikov caldera allowed us to correlate it to the previously studied tephra horizon Geys30, which until recently was erroneously attributed to an eruption within the Geysernaya caldera. Pyroclastic flow deposits from the eruption that led to the formation of the Krasheninnikov caldera were found on the southern shore of Kronotsky Lake, and its distal tephra was found in the sediments of the Central Kamchatka Depression (CKD) at a distance of up to 200 km from the source (from Milkovo to Kliuchi villages). The age of this tephra was previously estimated at ~30 ka, which now allows us to accept this estimate for the Krasheninnikov caldera. The identification of the tephra of the caldera-forming eruption in distal sections allows a minimum estimate of the erupted pyroclastic volume of ~13 km3 and the eruption magnitude of 6.1.

Revealing the role of land-use features on macrolitter distribution in Swiss freshwaters

Macrolitter, especially macroplastics, (> 0.5 cm) negatively impact freshwater ecosystems, where they can be retained along lake shores, riverbanks, floodplains or bed sediments. Long-term and large-scale assessments of macrolitter on riverbanks and lake shores provide an understanding of litter abundance, composition, and origin in freshwater systems. Combining macrolitter quantification with hydrometeorological variables allows further study of leakage, transport, and accumulation characteristics. Several studies have explored the role of hydrometeorological factors in influencing macrolitter distribution and found that river discharge, runoff, and wind only partially explains its distribution. Other factors, such as land-use features, have not yet been thoroughly investigated. In this study, we provide a country-scale assessment of land-use influence on macrolitter abundance in freshwater systems. We analyzed the composition of the most commonly found macrolitter items (referred to as ‘top items’, n = 42,565) sampled across lake shores and riverbanks in Switzerland between April 2020 and May 2021. We explored the relationship between eleven land-use features and macrolitter abundance at survey locations (n = 143). The land-use features included buildings, city centers, public infrastructure, recreational areas, forests, marshlands, vineyards, orchards, other land, and rivers and canals. The majority of top items are significantly and positively correlated with land-use features related to urban coverage, notably roads and buildings. Over 60% of top items were found to be correlated with either roads or buildings. Notably, tobacco, food and beverage-related products, as well as packaging and sanitary products, showed strong associations with these urban land-use features. Other types of items, however, did not exhibit a relationship with land-use features, such as industry and construction-related items. Ultimately, this highlights the need to combine measures at the local and regional/national scales for effective litter reduction.

Ekonomi Kreatif dan Daya Tarik Objek Wisata Studi Kasus Objek Wisata Paepira Lakeside

This research was conducted to see an overview of the potential for creative economic development at the Paepira Lake Side tourist attraction, so that it can increase tourist attraction. The research method used was descriptive case study research. The author looked at the potential of the Paepira Lake Side tourist attraction and then analyzed it based on the following aspects. aspects of tourist attraction and creative potential. The Paepira Lake Side tourist attraction has potential but looking at the aspects of tourist attraction it can be concluded that it does not meet the criteria. Recommendations that can be given by researchers are to increase cooperation between the local community, government, business people and academics to build and develop tourism that is more interesting to visit. The economic sub-sector that can be prioritized is the culinary aspect.

Prehistoric Recycling Explained in a Playful Way: The Pfahlbauten Wimmelbild—An Interactive Digital Mediation Tool Designed by Young People

With the “Talents Internship program” established by the Austrian Research Promotion Agency (FFG, Österreichische Forschungsförderungsgesellschaft), 14- to 17-year-old students from various school types visited the Natural History Museum and the Kuratorium Pfahlbauten in summer 2022 to gain practical experience in research. The internship focused on a sustainability approach, discussing recycling methods, the sustainable use of resources and the circular economy in prehistory. The UNESCO World Heritage “Prehistoric Pile Dwellings around the Alps” was used as a research area for the project. The project also aimed to make the content developed by the students available to the public as a digital media tool. The pupils brought an illustration of a prehistoric lake shore settlement to life and created an interactive image available at the website of Kuratorium Pfahlbauten. Various scenes of the illustration have been augmented with animations created by the students of HTL Spengergasse in Vienna. Students from federal secondary schools from Vienna (Stubenbastei) and Upper Austria (Traun) researched the information about the objects and wrote texts that, as a description of the animated videos, introduce the users to the prehistoric artifact and explain the recycling process behind it. The students worked independently using the scientific literature, 140-year-old inventory books and 6000-year-old objects from the collection of the Natural History Museum Vienna. The activities and the supporting program within the internship were recorded by the students in blog posts, available at the Pfahlbauten-Blog. The co-creative approach of the FFG Talent Internship made it possible to introduce a group of school students to the process of scientific work and the communication of results. It was honored with the Creative App Award at CHNT 2023.

Effect of the Temperature on the Performance and Dynamic Behavior of HfO2-Based Rram Devices

Over the past decades, the demand for semiconductor memory devices has been steadily increasing, and is currently experiencing an unprecedented boost due to the development and expansion of artificial intelligence. Among emerging high-density non-volatile memories, resistive random-access memory (RRAM) is one of the best recourses for all kind of applications, such as neuromorphic computing or hardware security [1]. Although many materials have been evaluated for RRAM development, some of them with excellent results, HfO2 is one of the established materials in CMOS domain due to its compatibility with standard materials and processes [2].The main goal of this work is to study the switching capability and stability of HfO2-based RRAMs, as well as to explore their ability in the field of analogue applications, by analyzing the evolution of the resistance states that allow multilevel control. Indeed, analogue operation is a key point for achieving electronic neural synapses in neuromorphic systems, with synaptic weight information encoded in the different resistance states. This research has been carried out over a wide temperature range, between 40 and 340 K, as we are interested in testing the extent to which performance is maintained or modified, with a view to designing neuromorphic circuits that are also suitable in the low-temperature realm. We aim to prove that these simple, fast, high integration density structures can also be used in circuits designed for specific applications, such as aerospace systems.The RRAM devices studied in this work are TiN/Ti/8 nm-HfO2/TiN metal-insulator-metal (MIM) capacitors. Dielectric layers were atomic layer deposited (ALD). It has been demonstrated that the Ti coat in the top electrode acts as a scavenger that absorbs oxygen atoms from the HfO2 layer, and facilitates the creation of conductive filaments of oxygen vacancies [3]. In fact, the oxygen reservoir capability of Ti is well known, as it is able to attract and release oxygen atoms from or to the HfO2 layer during the RRAM operation [4]. The clustering of vacancies extends through the entire thickness of the oxide and, after an electroformig step, it joins the upper and lower electrodes and the device reaches the low resistance state (LRS). By applying adequate electrical signals, the filaments can be partially dissolved, which brings the device into the high-resistance state (HRS), with lower current values. The set process brings the device to the LRS state, while the reset one brings it to the HRS. The dependence of electrical conductivity on external applied electrical excitation allows triggering the device between the both states in a non-volatile manner [5].The experimental equipment used consisted of a Keithley 4200-SCS semiconductor parameter analyzer and a Lake Shore cryogenic probe station. Fig.1 shows current-voltage cycles measured at different temperatures; the averages values at each temperature, both in logarithmic and linear scale, are also shown. The functional window increases as temperature decreases.The evolutions of set and reset voltage values with temperature are depicted in Fig.2, whereas the current values (measured at 0.1 V) corresponding to the LRS and HRS can be seen in Fig.3. LRS resistance decreases as temperature increases, in agreement with semiconductor behaviour, probably due to a hopping conduction mechanism. Both set and reset voltages decrease as temperature increases; the reset process is smoother at high temperatures. The reduction in reset voltage variability as temperature increases is very notable.Finally, Fig. 4 shows a picture of the transient behaviour; in the right panel of the same figure, the amplitudes of the current transients in the reset state have been included in the external loop.To sum up, the resistive switching phenomena is studied in a wide temperature range. The LRS shows semiconducting behavior with temperature, most likely related to a hopping conduction mechanism. Switching voltages decrease as temperature increases, with a notable reduction in reset voltage variability. An excellent control of intermediate resistance state is shown through current transients at several voltages in the reset process.REFERENCES[1] M. Asif et al., Materials Today Electronics 1, 100004 (2022).[2] S. Slesazeck et al., Nanotechnology 30, 352003 (2019).[3] Z. Fang et al., IEEE Electron Device Letters 35, 9, 912-914 (2014).[4] H. Y. Lee et al., IEEE Electron Device Letters 31, 1, 44-46 (2010).[5] D. J. Wouters et al., Proceedings of the IEEE 103, 8, 1274-1288 (2015). Figure 1

Planting trees in buffer strips for attenuating phosphorus runoff in Jiangsu Province, China

AbstractIn the last four decades, the Jiangsu province, like the rest of China, has undergone rapid economic development coupled with a rapid increase in environmental pollution. Freshwater ecosystems have been particularly affected. In Lake Tai, China's third‐largest freshwater lake by volume, water quality has been severely reduced. There is a renewed interest in establishing riparian buffer strips in China as a conservation practice for mitigating agricultural non‐point source pollution. To study the effect of riparian buffers on phosphorus attenuation, eight 50 m × 20 m plots were established between a rice farm and the shore of Lake Tai in China, with the 20 m width facing the lake shore. They were planted with hybrid poplar (Populus deltoides × euramericana), hybrid cypress (Taxodium ascendens × mucronatum), or a mixture of both at densities of 2 m × 3 m, 2 m × 5 m, or 5 m × 5 m, while one plot was left as a control. Samples collected from soil, tree leaves, and groundwater during 2014–2018 were analyzed for multiple forms of phosphorus. Results indicated that riparian buffer width and time (year) were the most significant factors of phosphorus attenuation on all plots. Tree density had a minor effect, with medium density being the most effective, and we found negligible differences among hybrid tree species on attenuating phosphorus. Farmers should use densely vegetated buffer strips at least 15 m wide to ensure a significant reduction in nutrient runoff. Species selection should be based on market value and ecological benefits.

Palynofacies analysis of a lacustrine succession: The Maracangalha Formation (Lower Cretaceous), Recôncavo Basin, Brazil

A palynofacies analysis was carried out using samples collected from the Manguinhos, Gameleira, Praia da Falha and Penha outcrops of the Lower Cretaceous Maracangalha Formation, Recôncavo Basin, NE Brazil. Qualitative and quantitative analysis of the organic particles, as well as grouping analysis based on the characteristics of the particles found, were conducted to establish the present database. The organic particles were grouped into amorphous organic matter (AOM); opaque phytoclasts; non-opaque phytoclasts and palynomorphs and four distinct palynofacies were recognized. The palynofacies I (P I), present in the Praia da Falha outcrop, is composed of a high abundance of non-opaque phytoclasts (51.22%), followed by palynomorphs (23.61%). The palynofacies II (P II), occurring in the Penha outcrop, shows a high abundance of non-opaque phytoclasts (71.67%), followed by opaque phytoclasts (12%). The palynofacies III (P III), occurring in the Manguinhos outcrop, consists of a high abundance of AOM (48.07%), followed by opaque phytoclasts (32,6%). The palynofacies IV (P IV), occurring in the Gameleira outcrop, also has a high abundance of AOM (47.05%), followed by non-opaque phytoclasts (28.76%). According to the associations of sedimentary organic matter, essentially represented by particles of continental origin, a lacustrine setting is well characterized, corroborating what has been previously suggested in the literature. The palynofacies interpretation also indicates deposition strongly controlled by fluvio-deltaic input. Overall, the Praia da Falha and Penha outcrops suggest proximity to the depositional source in a high-energy environment. In these localities, the predominance of non-opaque phytoclasts indicates deposition under oxic conditions probably near the lake shore. On the other hand, in the Gameleira and Manguinhos outcrops, the predominance of AOM suggests deposition away from the sediment source in a more distal, low-energy environment, with prevalence of suboxic-to-anoxic conditions.

SENSITIVITY OF A 1D LAKE MODEL TO THE INPUT METEOROLOGICAL DATA

The paper evaluates how the choice of a source of meteorological data used as boundary conditions and the changes in model calibration parameters affect the adequate performance of a model of lake thermo- and hydrodynamics. The quality of simulation of water temperature dynamics in a small lake by a onedimensional GLM model using data from an automatic meteorological station on the lake shore, a state weather station and two global reanalyses was quantitatively assessed. It is shown that the best modeling result (RMSE of water temperature calculation 0,8-2,0°C, Nash-Sutcliffe efficiency >0,7) can be achieved using data sets that explicitly provide incoming shortwave and longwave radiation fluxes. At the same time, good representation of the bottom water temperature requires correct setting of wind regime, which is only possible if data from instrumental ground-based observations at a stationary weather station are applied. Combining ground-based observations of wind speed, air temperature and humidity with radiation fluxes from global reanalyses makes it possible to achieve a calculation error ≤1°C at all depths.The analysis of model sensitivity to calibration parameters in case when the reanalysis data are applied showed that parameters related to wind mixing, i.e. the scaling factor for wind speed and constants related to the in-model description of wind impact energy, have the greatest influence on the final calculation error. If we change the intensity coefficients of other types of mixing during calibration it does not lead to an obvious trend in the quantitative estimates of modeling quality. It could also be reasonable to introduce correction multipliers to the values of air temperature and solar radiation fluxes, thus neutralizing the effect of unrepresentativeness of the meteorological data applied for a particular lake, as well as to correct the value of solar radiation extinction coefficient relative to the value obtained from the Secchi depth. The results of the study could be used to justify the choice of meteorological data source and to optimize the methods of calibration of lake thermal stratification models

Bioprospecting for moderately halophilic eubacteria for potential biotechnological applications from Sambhar Lake, Rajasthan, India

Sambhar Lake an athalassohaline habitat located at 27°58′N 75°55′E, Rajasthan, India is a major source of salt production in the country. From surface lake water, soil, and shore sediments, fifty-nine moderate halophiles were isolated which were subsequently grouped according to shape, colony characteristics, and staining into twenty-two isolates. Fourier transform infrared spectroscopy profiling identifiedthese isolates as eubacterial with characteristic C=O stretching of ester functional groups. Observations further indicatedsimilarity within some Halomonasisolates indicating potential phylogenetic lineages. The FASTA sequences obtained after sequencing with universal bacterial primers were processed for phylogenetic analysis. Predominantly Gram-positive genera like Alkalibacillus, Amphibacillus, Marinococcus, Piscibacillus, Planococcus, Salinicoccus, Staphylococcusand Virgibacilluswith only two Gram-negative strains of Halomonaswere identified. The genus Amphibacilluswas recognizedfor the first time in the study of Sambhar Lake. Despite being moderately halophilic, several isolates exhibited high salt tolerance with growth in 25% salt. All isolates were mesophilic with growth observed between 18-42°C which matches the temperature profile of the region. Analysis of hydrolytic potential identified eighteen isolates as protease producers, thirteen as lipase producers, and ten as cellulase-producing strains. Further evaluation showed the dominance of C10:0, C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C18:1 FAMEs, among which presence of C16:0 and C18:1 fatty acid indicated probable antimicrobial potentials of these strains.

Reclamation of an eroded lakeshore slope using small vegetation islands and terraces

Bioengineering approaches to slope stabilization involve biological and mechanical methods with low impact on the environment and landscape. Slope stabilization using vegetation patches or islands can greatly decrease runoff and soil erosion on an eroded lake shore. While vegetation islands showed promise for forest and grassland reclamation, they have rarely been used on eroded lake shores. A study was conducted to determine whether bioengineering using native vegetation islands and terraces could successfully revegetate and stabilize a severely eroded lake shore slope in the central aspen parkland, Alberta, Canada. Three gullies and three slopes were terraced using pressure treated planks, then transplanted with non-dormant (mid-August) and dormant (mid-October) 20 cm diameter vegetation islands in a soil amended with 25% (by volume) compost. Volumetric water content was significantly less in lower slope positions than upper slope positions, and sediment transport to lower slope positions was much reduced. After one year, both non-dormant and dormant transplanted islands survived and established on the terraced slope, under relatively inhospitable growing conditions. Although non-dormant islands had significantly lower vegetation mortality (10% or less) than dormant islands on both slopes and gullies, no differences in health and vigour were found by the end of the study. Overall plant species number on the site increased during the study. Graminoid species densities increased, while those of forbs, shrub and tree species declined in the transplanted vegetation islands. Non-dormant islands had greater graminoid density than dormant islands, where Poa pratensis was the dominant species in the islands. Bioengineering with vegetation islands and terraces can assist in trapping runoff and sediment, and accelerate establishment of a diversity of plant species and groups relative to traditional revegetation methods.

Tsunami Squares: Leapfrog scheme implementation and benchmark study on wave–shore interaction of solitary waves

Impulse waves are generated by rapid subaerial mass movements including landslides, avalanches and glacier break-offs, which pose a potential risk to public facilities and residents along the shore of natural lakes or engineered reservoirs. Therefore, the prediction and assessment of impulse waves are of considerable importance to practical engineering. Tsunami Squares, as a meshless numerical method based on a hybrid Eulerian–Lagrangian algorithm, have focused on the simulation of landslide-generated impulse waves. An updated numerical scheme referred to as Tsunami Squares Leapfrog, was developed which contains a new smooth function able to achieve space and time convergence tests as well as the Leapfrog time integration method enabling second-order accuracy. The updated scheme shows improved performance due to a lower wave decay rate per unit propagation distance compared to the original implementation of Tsunami Squares. A systematic benchmark testing of the updated scheme was conducted by simulating the run-up, reflection and overland flow of solitary waves along a slope for various initial wave amplitudes, water depths and slope angles. For run-up, the updated scheme shows good performance when the initial relative wave amplitude is smaller than 0.4. Otherwise, the model tends to underestimate the run-up height for mild slopes, while an overestimation is observed for steeper slopes. With respect to overland flow, the prediction error of the maximum flow height can be limited to ± 50% within a 90% confidence interval. However, the prediction of the front propagation velocity can only be controlled to ± 100% within a 90% confidence interval. Furthermore, a sensitivity analysis of the dynamic friction coefficient of water was performed and a suggested range from 0.01 to 0.1 was given for reference.

Effect of environmental variables on the abundance of Amblyomma ticks, potential vectors of Rickettsia parkeri in central Brazil.

Amblyomma ticks are vectors of both Rickettsia rickettsii and R. parkeri in the Americas, where capybaras (Hydrochoerus hydrochaeris) are the main hosts in urban areas, thus contributing to the transmission of spotted fever. Herein, we studied: (i) the seasonal dynamics and abundance of ticks in areas where capybaras live, (ii) the effect of environmental variables on tick abundance, and (iii) the presence of Rickettsia-infected ticks. Between September 2021 and September 2022, we sampled ticks using cloth-dragging at 194 sites on the shore of Lake Paranoá in Brasília, Brazil. We measured environmental data (season, vegetation type, canopy density, temperature, humidity, and presence or vestige of capybara) at each site. Nymphs and adults were morphologically identified to the species level, and a selected tick sample including larvae was subjected to genotypic identification. We investigated Rickettsia-infected ticks by PCR (gltA, htrA, ompB, and ompA genes) and associations between tick abundance and environmental variables using Generalized Linear Models. A total of 30,334 ticks (96% larvae) were captured. Ticks were identified as Amblyomma, with A. sculptum comprising 97% of the adult/nymphs. Genotype identification of a larval sample confirmed that 95% belonged to A. dubitatum. Seasonal variables showed significant effects on tick abundance. Most larvae and nymphs were captured during the early dry season, while the adults were more abundant during the wet season. Vegetation variables and the presence of capybaras showed no association with tick abundance. Rickettsia parkeri group and R. bellii were identified in A. dubitatum, while A. sculptum presented R. bellii. We conclude that: (i) Amblyomma ticks are widely distributed in Lake Paranoá throughout the year, especially larvae at the dry season, (ii) the abundance of Amblyomma ticks is explained more by climatic factors than by vegetation or presence of capybaras, and (iii) A. dubitatum ticks are potential vectors of R. parkeri in Brasília.

Towards an understanding of hunting equipment used by early Holocene foragers of the Egyptian Southwestern Desert: Triangles of the El-Ghorab Unit

One of the Early Holocene archaeological cultures distinguished in the Egyptian Western Desert is defined as the El Ghorab Unit, and is dated to the 10th millennium cal BP. These hunter-gatherer groups lived on the shores of seasonal lakes (playas) and wetlands typical for the Early and Middle Holocene landscape of that part of the Saharan North Africa. They manufactured characteristic lithic artifact assemblages that have not been studied, so far, from a microwear perspective. The El Ghorab Unit lithic artifact assemblages are dominated by morphologically distinct triangular microliths, ca. 30–40 mm long and made from relatively wide blades, ca. 10 mm in width.This paper presents the results of morphological and functional analyses of El-Ghorab triangles from site E-16-03 located in the Gebel Ramlah/Nabta Playa region. At this locality, remnants of a few activity areas have been recorded on the northwestern margin of the Gebel Ramlah paleo-lake basin. The site consists of lithic artifact concentrations scattered around burned-earth hearth features (fireplaces). The function of the triangles is examined and interpreted here by also taking into account the specific paleoenvironmental and paleozoological record from site E-16-03.The El-Ghorab area of the Gebel Ramlah basin at E-16-03 contains three seasonally-specific, short-term hunting camps where hunting equipment was repaired and hunted game was brought to the site during spring time. Triangles were the main goal of lithic production. In the course of this research it has become evident that triangular microliths were mounted in hafts in different ways. This observation can be used as supporting evidence to conclude that various prehistoric human groups visited the Gebel Ramlah area during several seasonal cycles.

Diversity of Freshwater Turtles Melanochelys trijuga in and Around Sankarapuram Wetland Complex on Kallakurichi District, Tamil Nadu, India

India is one of the most species-rich regions of freshwater turtles in the world, also, they are being collected, for slaughter, eaten, and traded in huge numbers. The scope of this study on Melanochelys trijuga, also known as the Indian Black Turtle, focuses on collecting comprehensive information about the species in India, specifically in Tamil Nadu, with a special emphasis on Sankarapuram.The study aims to address the lack of current data about this turtle species and contribute to the understanding of its taxonomy, distribution, habitat, behavior, and conservation status. Various methods are employed in this study such as visual sighting of habitat to encounter the target animal, and, indirectly through interview-based survey information from local communities. Visual survey was conducted on 20 locations of the sankarapuram study area. On the surveyed 20 locations the tortoise was observed in five locations viz. two Coconut farm, two ordinary well which used for irrigation purpose and a lake side muddy shallow area. Totally 10 individuals were observed in this study period. We had an opportunity to examine the specimens very closely once it comes out behind the open well. The captured specimens were later examined by comparison with the standard key characteristics and manuals in order to identify the specimen and found as Melanochelys trijuga species. In this study we observed both male and female individuals. The individuals are found as adults. The characteristics and ecology information were compared with the existing data in previous record and publications and manuals. Obtained Melanochelys trijuga species was found as Nearly Threatened status in the International Union for Conservation of Nature (IUCN) category.

Diagenetic iron-oxyhydroxides formed in suboxic to anoxic mine-impacted lake sediments near Sudbury, Ontario

Iron-oxyhydroxides are common in lake sediments, typically forming in oxidizing conditions near the sediment-water interface. However, in the mine-tailings-impacted sediment delta at Long Lake near Sudbury, Ontario, diagenetic Fe-oxyhydroxides are formed in suboxic-anoxic conditions. Geochemical and mineralogical techniques were applied to investigate the diagenetic transformations of tailings-derived oxidation products following burial in the sediment delta. Two sets of vertical cores were collected, one from a shallow-water location in the sediment delta near the lake shore and the other from a deeper-water location, approximately 90 m north from the mouth of the active channel. One core from each location was sectioned in the field into 0.1 m intervals using an anaerobic globe bag and porewater was extracted for aqueous geochemical analysis. The second core from each location was dried anaerobically and sub-sampled for solid-phase geochemical and mineralogical analyses. The aqueous concentrations of As, Fe, and SO4 are elevated near the sediment-water interface at both locations but at the shallow location they decline to the lowest observed concentrations at depth in the natural sediment. The decline in their concentrations may be enhanced by bacterial SO4 reduction and precipitation of Fe- and As-sulfides which were observed in mineralogical analysis. The mine-impacted sediment consists of numerous fragments of tailings-derived ferric-arsenate-cemented crusts. Compared to the cemented crusts that occur in the tailings, these fragments exhibit partial-dissolution features and SEM-EDS analyses demonstrate that they have relatively low As/Fe ratios, suggesting the occurrence of selective As(V) dissolution during diagenesis. Diagenetic Fe-oxyhydroxides occur throughout the mine-impacted sediment, including zones that contain diagenetic Fe- and As-sulfides, suggesting they may have formed in suboxic-anoxic conditions. They occur proximal to, but separate from, the fragments of tailings-derived crusts and display diverse morphologies, including what may be a previously unreported spherulitic form. Individual Fe-oxyhydroxides range in size from nm to μm but they mostly occur in delicate clusters suggesting they are autochthonous. Compared to the cemented crusts from the tailings, they contain very small amounts of As. Analysis of one spherule indicates it contains lepidocrocite microcrystals with amorphous SiO2.nH2O in the interstitial spaces. The microcrystals contain a mixture of Fe(III) and Fe(II), with Fe(III)/ΣFe = approximately 0.8. We interpret them to have formed by burst nucleation from Fe(III)-supersaturated solution, with subsequent aggregation of crystallites to form spherules.

Manganese‐Rich Sandstones as an Indicator of Ancient Oxic Lake Water Conditions in Gale Crater, Mars

AbstractManganese has been observed on Mars by the NASA Curiosity rover in a variety of contexts and is an important indicator of redox processes in hydrologic systems on Earth. Within the Murray formation, an ancient primarily fine‐grained lacustrine sedimentary deposit in Gale crater, Mars, have observed up to 45× enrichment in manganese and up to 1.5× enrichment in iron within coarser grained bedrock targets compared to the mean Murray sediment composition. This enrichment in manganese coincides with the transition between two stratigraphic units within the Murray: Sutton Island, interpreted as a lake margin environment, and Blunts Point, interpreted as a lake environment. On Earth, lacustrine environments are common locations of manganese precipitation due to highly oxidizing conditions in the lakes. Here, we explore three mechanisms for ferromanganese oxide precipitation at this location: authigenic precipitation from lake water along a lake shore, authigenic precipitation from reduced groundwater discharging through porous sands along a lake shore, and early diagenetic precipitation from groundwater through porous sands. All three scenarios require highly oxidizing conditions and we discuss oxidants that may be responsible for the oxidation and precipitation of manganese oxides. This work has important implications for the habitability of Mars to microbes that could have used Mn redox reactions, owing to its multiple redox states, as an energy source for metabolism.