Spatial Distribution Of Elements Research Articles

Processing and microstructure development of reactive sintered (Ti-Zr-Nb-Hf-Ta)B2 + (Ti-Zr-Nb-Hf-Ta)C high-entropy ceramics

A novel dual-phase (Ti-Zr-Nb-Hf-Ta)B2 + (Ti-Zr-Nb-Hf-Ta)C high-entropy, compositionally complex composite was synthesized by reactive spark plasma sintering using commercial ZrB2, NbB2, HfB2, TaB2 and TiC powders as starting materials. The composite with high density, consists predominantly of boride (∼39.7 vol%) and carbide (∼56.4 vol%) phases and with residual amount of (Hf-Zr)O2. The microstructure is homogenous and relatively fine due to the reaction and solid solution coupling effect with average grain sizes of 3.4 μm and 2.2 μm of the boride and carbide phases, respectively. Large-area SEM analyses confirmed no microcracks or micropore formation and no presence of large grains or clusters. Investigation from micro to nano and atomic level, focused on local chemical composition and spatial distribution of constituent elements, revealed that Ti preferentially dissolves into the boride and all other elements to the carbide phase creating a (Ti0.82Zr0.04Nb0.08Hf0.03Ta0.03)B2 + (Ti0.49Zr0.12Nb0.13Hf0.11Ta0.15)C system. The analysis of grain and phase boundary interfaces revealed a continuous, <1.5 nm wide, segregation of impurity atoms of Fe and Co. Continuous (>20 nm) and atomically flat basal interfacial termination planes (001) decorated with monoatomic Zr enriched layer in the boride phase were observed. Triple points at grain and phase boundaries exhibit metal-rich composition due to impurities from the starting raw powders.

Morphology Variation of Ternary PdCuSn Nanocrystalline Assemblies and Their Electrocatalytic Oxidation of Alcohols.

Metal alloys not only increase the composition and spatial distribution of elements but also provide the opportunity to adjust their physicochemical properties. Recently, multimetallic alloy nanocatalysts have attracted great attention in energy applications and the chemical industry. This work presents the production of three ternary PdCuSn nanocrystalline assemblies with similar compositions via a one-step hydrothermal method. The shape variation of assembly units from nanosheets and nanowires to nanoparticles were realized by adjusting the percentage of Sn in metal precursors. Experimental data show that PdCuSn nanowire networks showed the best catalytic activity by virtue of their optimized morphological characteristics and microscopic electronic structure. With electrooxidation of methanol, ethanol, ethylene glycol, and glycerol at 30 °C, PdCuSn nanowire networks demonstrated catalytic activity of 1129, 2111, 2540, and 1445 mA mg-1, respectively. The catalytic activity for alcohol oxidation is attributed to the production of the electronic structure and morphology features that are most suitable. This is achieved by introducing the proper quantities of Cu and Sn components in the first stage of synthesis. This study would help with the construction of high-efficiency nanostructured alloy catalysts by regulating the electronic structure and morphology.

Nanoparticles of dust as an emerging contaminant in urban environments.

Due to very high mobility in the environment and penetration ability into living organisms, nanoparticles (NPs) of urban dust pose a potential threat to human health and urban ecosystems. Currently, data on the chemical composition of NPs of urban dust, their fate in the environment, and corresponding risks are rather limited. In the present work, NPs of deposited urban dust have been comprehensively studied for the first time; NPs isolated from 78 samples of dust collected in Moscow, the largest megacity in Europe, being taken as example. The elemental composition, potential sources as well as environmental, ecological, and health risks of NPs of urban dust are assessed. It is found that dust NPs are extremely enriched by Cu, Hg, Zn, Mo, Sb, and Pb, and can serve as their carrier in urban environments. No regularities in the spatial distribution of elements have been found, probably, due to high mobility of dust NPs. High ecological and health risks caused by dust NPs are demonstrated. Source apportionment study has evaluated one natural and two anthropogenic sources of elements in NPs of urban dust; the contribution of natural and anthropogenic sources being comparable. It is also shown that dust NPs may be considered as an important carrier of trace elements in urban aquatic systems. Additionally, the risks associated with NPs and bulk samples of dust have been compared. The observed risks associated with NPs are significantly higher.

The spatio-temporal evolution of spatial structure and supply-demand relationships of the ecological network in the Yellow River Delta region of China

Rapid urbanization has caused unregulated transformation of land use/land cover, further exacerbating the imbalance in ecological supply-demand relationships. Constructing the ecological supply-demand network by integrating natural ecological processes and human ecological demands into a unified spatio-temporal framework and considering their internal dynamic flow characteristics is an effective approach to address this issue. However, there is currently a lack of evaluation methods for the coordination of ecological network supply-demand relationships, which could provide essential guidance and reference. This article takes Yellow River Delta region (YRDR) as an example and utilizes the integrated traditional ecological network paradigm and ecosystem services theory to simulate the ecological supply-demand network for the years 2000, 2010, and 2020 in the study area. Then, a novel evaluation index system for the ecological network supply-demand relationships was proposed from the perspectives of intensity, capacity, and equilibrium. Based on this, combined with a graph-based network structure evaluation system, it reveals the spatio-temporal evolution process of the spatial structure and supply-demand relationship of the ecological network in the study area. The study results showed that: (1) The quantity of elements in the ecological supply network and the demand network show opposite trends, leading to an exacerbation of the spatial imbalance in the arrangement of ecological supply-demand network elements. (2) Although the structural changes in the ecological supply network were significantly greater than those in the ecological demand network, the overall structure of the ecological supply-demand network gradually improved. (3) However, under the coupled influence of imbalanced change in the spatial distribution and connectivity of ecological elements, the overall coordination of the ecological supply-demand relationships within the YRDR's ecological network is gradually deteriorating. (4) The proposed optimization strategy, "Two zones, Three belts, Four corridors", for the ecological security pattern in YRDR can accommodate the ecological process cycle and human ecological demand. This study can provide scientific references for "harmonious coexistence between humans and nature" ecological protection and sustainable development planning under the background of rapid urbanization.

Assessing spatial distribution of bioindicator elements in various cutaneous tumors using correlative imaging with laser-ablation-based analytical methods

Correlative imaging of cutaneous tumors provides additional information to the standard histopathologic examination. However, the joint progress in the establishment of analytical techniques, such as Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) in clinical practice is still limited. Their combination provides complementary information as it is also shown in our study in terms of major biotic (Ca, Mg, and P) and trace (Cu and Zn) elements. To elucidate changes in the elemental composition in tumors, we have compiled a set of malignant tumors (Squamous Cell Carcinoma, Basal Cell Carcinoma, Malignant Melanoma, and Epithelioid Angiosarcoma), one benign tumor (Pigmented Nevus) and one healthy-skin sample. The data processing was based on a methodological pipeline involving binary image registration and affine transformation. Thus, our paper brings a feasibility study of a practical methodological concept that enables us to compare LIBS and LA-ICP-MS results despite the mutual spatial distortion of original elemental images. Moreover, we also show that LIBS could be a sufficient pre-screening method even for a larger number of samples according to the speed and reproducibility of the analyses. Whereas LA-ICP-MS could serve as a ground truth and reference technique for preselected samples.

Levels of potentially toxic and essential elements in Tocantins River sediment: health risks at Brazil’s Savanna-Amazon interface

The field study aims to address identified research gaps by providing valuable information on the concentration, spatial distribution, pollution levels, and source apportionment of toxic and essential elements in sediment samples from four sampling sites (P1: Beira Rio (urban area), P2: Bananal (rural area), P3: Embiral (rural area), P4: Cidelândia (rural area) distributed along the middle Tocantins River, Brazil. Samples were collected in 2023 from river sections and analyzed using various contamination índices (geoaccumulation index, contamination factor, enrichment factor, pollution load index, sediment pollution index, potential ecological risk coefficients, and integrated risk index). Results indicated that the levels of aluminum, iron, manganese, and selenium exceeded legal standards in that year. Chromium, nickel, copper, zinc, and lead exceeded guidelines, mainly in section P1 for aluminum and section P3 for nickel and lead. Rainy months showed increased presence, indicating seasonal variability. The geoaccumulation index indicated low pollution levels, with lead and nickel notably present near urban and industrial areas. The enrichment factor highlighted elevated concentrations of lead and zinc in industrial areas. Both PLI and SPI indices raise concerns regarding Pb (P4) and Zn (P3) concentrations at specific times of the year. Overall, potential ecological risks were deemed low for most sites. Continuous monitoring and interventions are crucial to preserve water and environmental quality in the region.

Placental Element Content Assessed via Synchrotron-Based X-ray Fluorescence Microscopy Identifies Low Molybdenum Concentrations in Foetal Growth Restriction, Postdate Delivery and Stillbirth.

Placental health and foetal development are dependent upon element homeostasis. Analytical techniques such as mass spectroscopy can provide quantitative data on element concentrations in placental tissue but do not show spatial distribution or co-localisation of elements that may affect placental function. The present study used synchrotron-based X-ray fluorescence microscopy to elucidate element content and distribution in healthy and pathological placental tissue. The X-ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron was used to image trace metal content of 19 placental sections from healthy term (n = 5, 37-39 weeks), foetal growth-restricted (n = 3, <32 weeks, birth weight <3rd centile), postdate (n = 7, >41 completed weeks), and stillbirth-complicated pregnancies (n = 4, 37-40 weeks). Samples were cryo-sectioned and freeze-dried. The concentration and distribution of fourteen elements were detected in all samples: arsenic, bromine, calcium, chlorine, copper, iron, molybdenum, phosphorous, potassium, rubidium, selenium, strontium, sulphur, and zinc. The elements zinc, calcium, phosphorous, and strontium were significantly increased in stillbirth placental tissue in comparison to healthy-term controls. Strontium, zinc, and calcium were found to co-localise in stillbirth tissue samples, and calcium and strontium concentrations were correlated in all placental groups. Molybdenum was significantly decreased in stillbirth, foetal growth-restricted, and postdate placental tissue in comparison to healthy-term samples (p < 0.0001). Synchrotron-based XFM reveals elemental distribution within biological samples such as the placenta, allowing for the co-localisation of metal deposits that may have a pathological role. Our pilot study further indicates low concentrations of placental molybdenum in pregnancies complicated by foetal growth restriction, postdate delivery, and stillbirth.

Effect of MgO/ZnO ratio on the formation process of MgxZn1-xO ceramics

The structural characteristics, chemical composition, and element spatial distribution in MgxZn1-xO ceramics were investigated using X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, energy-dispersive X-ray spectroscopy, and cathodoluminescence techniques. The study revealed that the morphology of the ceramic samples, as well as the mechanism of solid solution formation, depend on the relative contribution of both oxides in the charge. It was discovered that hexagonal and cubic phases of the solid solution were found to form simultaneously. An increase in the MgO content in the charge results in the magnesium content rise in the hexagonal grains continuously, reaching approximately 13 at.%. It was discovered an enrichment of grain boundaries with zinc and magnesium playing a significant role in doping ZnO and MgO grains. Obtained results allowed to propose two mechanisms involved in the formation of solid solution ceramics: i) diffusion of Mg and Zn along grain boundaries, followed by their incorporation into ZnO or MgO grains, respectively, and ii) interdiffusion of Mg into ZnO and Zn into MgO due to direct contact of ZnO and MgO grains. The second mechanism appears to dominate when both ZnO and MgO contribute comparably, increasing the probability of their direct contact. This study significantly advances the understanding of the process of the formation of MgxZn1-xO ceramics under thermodynamic conditions. These insights are crucial for optimizing the doping process and improving the material properties, thereby promoting innovations in the ceramics industry.

Spatial distribution of soil rare earth elements in Sicily (Italy)

Rare earth elements (REEs) are becoming increasingly interesting as indicators of soil processes, and modelling their spatial distribution has become a fundamental requirement for this purpose. This study aims to model and quantify the spatial distribution of soil REEs taking into account their compositional nature in their mapping, and to assess the associated spatial uncertainty. In particular, the cerium anomaly (Ce⁎) and the ratio of the sum (Σ) of light to heavy REEs (ΣLREEs/ΣHREEs) were calculated and analysed. The study was carried out in Sicily (Italy), one of the largest (25,832 km2) and most populous island in the Mediterranean Sea. Soil REE data were obtained from the soil database of Sicily region. Soil REEs were transformed into a vector of isometric log-ratio (ilr) coordinates and analysed using a geostatistical approach for predicting their values at unsampled locations and generating 100 REEs realizations using turning bands simulation. Each REE element and Ce⁎ were mapped as well as the ΣLREEs/ΣHREEs ratio. The joint variability of the investigated REEs and the ΣLREEs/ΣHREEs ratio provided insights into their abundance and distribution patterns. From the simulated realizations, standard deviation maps were calculated for the Ce⁎ and the ΣLREEs/ΣHREEs ratio, providing a measure of their spatial uncertainty. Although with some limitations, the study established a first baseline of the Ce⁎ and the ΣLREEs/ΣHREEs ratio. The maps of spatial uncertainty may be a useful tool for planning future soil sampling and optimise the choice of new sampling locations.

Mineralogy and rare earth elements spatial distribution in the carboniferous rocks of the eastern El Galala El Bahariya, Egypt

The Carboniferous rocks in the eastern part of El Galala El Bahariya were investigated using integrated field and laboratory techniques to determine their mineralogy, rare earth elements (REEs) distribution, and structural lineament density. The succession is mainly composed of argillaceous and minor arenaceous rocks, exhibiting variations in lithology across the study area. The essential minerals of these rocks are quartz, kaolinite, and illite. The accessory minerals include microcline, gypsum, anhydrite, halite, barite, hematite, pyrite, anatase and gibbsite, in addition to, the radioactive and REEs-bearing minerals such as uranophane, xenotime, monazite, and zircon. These minerals are reported in the rocks of the study area for the first time. The types, forms, habits, and modes of occurrence of the recorded minerals indicate multiple origins: allogenic–authigenic, and primary-secondary. REEs in the rocks exhibit enriched patterns with a negative Eu anomaly, likely due to low plagioclase content or and/or Eu removal by alteration processes. The distribution of REEs is influenced by textural attributes, with finer sediments in the southern part showing higher REEs content, ascribed to the high clay content and presence of gibbsite. The preferential mobility of LREEs is evident, explaining elevated LREEs/HREEs ratios in the rocks. Utilizing remote sensing techniques, lithological units and alteration zones were determined using decorrelation stretch and band ratio methods. The structural features, identified by Laplacian filter and edge enhancement, revealed the presence of NW–SE, N–S, and NE–SW faults that structurally regulate alteration zones and REEs distribution. These alteration zones are associated with clay minerals, REEs concentrations, and high lineament structure density. Spatial distribution maps highlight higher REEs concentrations in the southern part of the study area. These findings were validated using various analytical methods, including mineralogical and geochemical investigations, main component analysis, minimum noise fraction, decorrelation stretch, and spectral reflectance studies. They provide new insights into the REEs potential of the Carboniferous rocks and heighten our understanding of REEs genesis and distribution in the region.

Photoionization analysis of chemodynamical dwarf galaxies simulations. II. Detailed calculation of diffuse ionizing radiation

ABSTRACT Active star formation in dwarf galaxies shapes the morphology of the surrounding nebular environment and ensures the non-uniformity of the chemical elements spatial distribution in it due to the superwind region expansion. Ionizing radiation within the nebular gas produces observed emission lines used for modelling and diagnostics. We introduce a multicomponent photoionization modelling (MPhM) approach that incorporates detailed calculation of diffuse ionizing radiation (DCDIR) based on chemodynamical simulations (ChDSs). Our models aim to replicate crucial emission line intensity ratios within the observed range, employing a thin dense shell between the superwind region and the outer nebular environment to address ChDSs resolution limitations, which render them insensitive to the presence of a superwind shock. MPhM-generated emission line spectra within a small central synthetic aperture and a thin long-slit exhibit excellent agreement with observations, confirming the accuracy of the ionization structure of the nebular environment obtained using the MPhM + DCDIR approach. However, the outward-only approximation fails to reproduce the dwarf galaxies ionization structure. We determined the oxygen abundance using the $T_e$- and $R_{23}$-methods based on emission lines from MPhM + DCDIR. The resulting abundances align well with values obtained by averaging over the ‘observed’ volume within synthetic apertures, weighted by mass. The escape fraction of ionizing photons from the dwarf galaxy was found to be larger than that obtained using the outward-only approximation. Employing Kennicutt’s calibration corrected for near-UV data, the star formation rate (SFR) was calculated using the ${\rm H}\,\alpha$ luminosity from MPhM + DCDIR. The resulting SFR value is nearly 33 per cent higher than the true one.

Interpreting environments of deposition from facies analysis of outcrop versus seismic reflection data: A cautionary tale from the Mount Messenger Formation, Taranaki Basin (New Zealand)

The lower part of the Mount Messenger Formation, which crops out along the North Taranaki coast (North Island, New Zealand), is widely regarded to display classic examples of exhumed basin floor fan strata. This interpretation is supported by numerous publications on the sedimentary facies and depositional environments inferred for these strata, which are exposed in coastal cliff exposures about 20 m high with limited lateral extent. Consequently, for almost three decades, this succession has served as an analogue and training ground for geoscientists investigating the features of basin floor fan deposits and their reservoir characteristics. Here, we bring together seismic stratigraphy and seismic geomorphology of 2D and 3D seismic reflection datasets, as well as photogrammetric models based on images collected using uncrewed aerial vehicle (UAV) drones from selected locations along the outcrop belt to challenge this paradigm. We analyzed seismic reflection data in an area immediately offshore and down-dip of the strata exposed in the coastal outcrop and found no objective criteria for submarine fan depositional elements based on accepted seismic stratigraphic criteria. Furthermore, mapping of seismic reflectors revealed large submarine channel systems (up to 3 km wide and up to 200 m deep) within the lower part of the Mount Messenger Formation. Submarine channel depositional elements (less than 250 m wide and 25 m thick) are also observed to incise through the outcrops, but they are generally below seismic resolution. In the context of the regional geology, we conclude that the lower Mount Messenger Formation accumulated as continental slope sediments cross-cut by channels rather than as basin floor fans. This study issues a cautionary tale about applying facies analysis to outcrop with limited 3D exposure to interpret sedimentary environments. The spatial distribution of facies and architectural elements viewed in seismic data are invaluable for testing the veracity of facies interpretations.

Distribution, source identification, water quality, and risk assessment of trace elements in the surface-groundwater-sediments multifunctional system in Guohe River Basin

Within the Huaihe River Basin, Guohe River, as its second-largest tributary, serves as a critical water supply source. Recent industrial and agricultural advancements have led to increased trace element contamination, adversely impacting the water quality within Guohe River Basin. Therefore, this study aimed to investigate the distribution characteristics, sources, water quality and risk assessment of trace elements in the surface water, groundwater, and sediments across the basin. The results showed that the spatial distribution of trace elements in the surface water and groundwater of Guohe River Basin was that most of the high concentrations appeared in Qiaocheng District of Bozhou City, the mean concentration of Fe in Guohe River sediments was the highest, the mean concentration of Sb was the lowest. The PMF source analysis results showed that the main source of trace elements in Guohe River Basin was natural geological processes, followed by human activities. The sodium adsorption ratio (SAR) indicated that the surface water samples of Guohe River in two seasons had high sodium and salinity hazards. The water quality index (WQI) showed that surface water and groundwater samples in the northwestern of Guohe River Basin had poor water quality. The results of the risk assessment showed that As and Mn posed great ecological risks to surface water and groundwater, respectively, and that F− was the pollutant with the most potential health risk hazard in the basin. The Geo-accumulation index (Igeo) results showed that Cd, Se and As should be taken seriously as the main contaminants of the sediments in Guohe River Basin. KeywardsTrace elements; Source analysis; Sodium adsorption ratio; Water quality index; Risk assessment; Geo-accumulation index.

Spatial distribution of trace and rare earth elements of bottom sediments in Lake Ostrowite, Bory Tucholskie National Park, Poland

AbstractLake pollution has attracted concerns worldwide; especially the excessive accumulation of trace elements (TEs) and rare earth elements (REEs) in bottom sediments can pose a serious threat to ecosystem health. However, there is still a knowledge gap on the level of sediment pollution in lakes isolated from the direct impact of pollution sources, their spatial variability, and also on the factors influencing this state. The aim of this study is to investigate the level and spatial variability of TEs and REEs concentrations, as well as to determine their source and the factors determining their distribution in the bottom sediments of Lake Ostrowite. Lake Ostrowite is the largest and deepest water body located in the Bory Tuholskie National Park (in northern Poland), which completely isolates the lake from the direct impact of pollution sources. The study covered analyses of 32 surface samples of bottom sediments. The concentrations of 24 TEs and 14 REEs were determined using inductively coupled plasma mass spectrometry (ICP‐QQQ‐MS). The assessment of the enrichment of bottom sediments in TEs and REEs employed geochemical background values (GBV) that provided the basis for the calculation of relative concentrations and geochemical indices. The determination of their sources and supply routes was based on the cluster analysis and principal component analysis. The obtained results point to the enrichment of the bottom sediments with TEs and REEs. Relative concentration values of TEs and REEs in reference to geochemical background values were in ranges from 0.01 to 7.31, at an average of 0.99, and from 0.03 to 4.29, averaging 1.76, respectively. The enrichment factor values show moderately severe enrichment of sediments at the study sites. This was primarily determined by the concentrations of Ag (from the TEs group) and Lu (from the REEs group). The metal pollution index values showed an approximate spatial distribution of points in terms of the presence of TEs and REEs. The lowest concentrations of TEs and REEs occurred on the eastern shore of the western basin of Lake Ostrowite. TEs and REEs concentrations in sediments are positively correlated with the content of organic matter and depth and negatively correlated with distance of the sampling point from the river outflow from Lake Ostrowite. On the eastern shore of the western basin, TEs and REEs concentrations are additionally shaped by wind, predominantly from the western direction. With water wave action, organic matter is transported to the central part of the western basin, where it is accumulated. Since the lake is isolated from point and nonpoint pollution sources, relevant from a biogeochemical point of view are dry and wet depositions from the atmosphere as well as aquatic vegetation, shoreline vegetation, forest litter, soil, and groundwater.

“Hidden” mineralogical-geochemical zonality revealed by the laser microanalysis of sulfides at the Kyzyk-Chadr deposit, Republic of Tyva

A comprehensive study of the Kyzyk-Chadr porphyry copper deposit included determination of the composition and spatial distribution of trace elements in ore-forming sulfide minerals over the ore- hosting rock volume. The study was carried out using the mass spectrometric analysis with laser ablation of the analyzed material. Steady qualitative and quantitative elements of a “hidden” mineralogical and geochemical zonality have been identified, that are expressed in variations in the concentration of trace elements and their ratios in pyrites and chalcopyrites over the volume of the ore-bearing porphyry copper stockwork. The identified regularities correlate with the established centrifugal vector and concentric pattern of the mineralogical ore-metasomatic zonality of the ore deposit.

Assessment of elemental chemistry, spatial distribution, and potential risks of road-deposited dusts in Sharjah, United Arab Emirates

Road dust is a major source of pollution in the environment, carrying different pollutants, including heavy metals and metalloids, from one location to another. This study assesses the concentrations of eight heavy metals and one metalloid (Zn, Pb, Mn, Fe, Cr, Cu, Cd, Ni, and As) in dust samples collected from sixty-eight streets of Sharjah, United Arab Emirates using ICP-OES, as well as investigates their effects on both the environment and humans. Mean concentrations of the elements in μg/g across the sites were 392 ± 46 (Zn), 68.28 ± 11.3 (Pb), 1437 ± 67 (Mn), 39,481 ± 4611 (Fe), 460 ± 31 (Cr), 150 ± 44 (Cu), 1.25 ± 0.65 (Cd), 856 ± 72 (Ni), and 0.97 ± 0.28 (As). The Cdeg and ERI calculated from the study were 54.79 and 573, respectively, suggesting varying pollution levels. The highest contributions were from Ni, Cd, Zn, Cu, Cr, and Pb, especially in areas with heavy traffic. The non-carcinogenic risk assessments were generally low for the three routes of exposure, except HQoral that was slightly higher for children. Similarly, none of the elements exhibited any carcinogenic risk except chromium. Overall, the cancer risk is considered low. In view of the limited studies from UAE in relation to the metal content of road-deposited dusts, the current study serves as novel knowledge, especially in the context of geographical areas with a higher occurrence of sandstorms and the presence of particulate matter. The study also adds to the global understanding of the contribution of street dust to environmental pollution and its implications for human health.

Evaluate the spatial distribution of trace elements in soil of a karst terrain

Evaluate the spatial distribution of trace elements in soil of a karst terrain

Assessing the spatial distribution of elemental concentrations in surface sediments of Lake Victoria, Kenya: implications for ecological health and management.

Lacustrine sediment quality indicates the effects of both natural and anthropogenic activities on the ecosystem and communities. Despite its ecological importance, myriad complexities, and potential contaminant sources, the spatial distribution of surficial sediments in Lake Victoria's Winam Gulf has never been comprehensively documented. The purpose of this study was to assess the spatial distribution, pathways, and ecological risk of metal elements in the lake using a sediment matrix. Sediment samples were collected throughout the gulf in November 2022. The concentrations of Al, As, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, Ni, P, Pb, Sb, Sn, Ti, Tl, U, and Zn were compared to different contamination metrics and ecological risk assessment indices. The average concentrations were in the following decreasing order: Zn > > > Cr > > Cu > Ni > Pb > Co > As > Cd with mean (± SD) of 185 ± 45mgkg-1, 56 ± 15mgkg-1, 45 ± 16mgkg-1, 37 ± 11mgkg-1, 24 ± 5mgkg-1, 20 ± 7mgkg-1, 3.9 ± 1.3mgkg-1, 0.30 ± 0.09mgkg-1, respectively, with strong indications of anthropogenic sources. Average concentrations were in the following decreasing order: Zn > > > Cr, Cu, Ni, Pb, Co, As, and Cd levels (mean ± SD) were 185 ± 45mgkg-1, 56 ± 15mgkg-1, 45 ± 16mgkg-1, 37 ± 11mgkg-1, 24 ± 5mgkg-1, 20 ± 7mgkg-1, 3.9 ± 1.3mgkg-1 and 0.30 ± 0.09mgkg-1 with strong indications of anthropogenic sources. The geo-accumulation index (Igeo) and enrichment factor categorisation schemes, respectively, classified these as uncontaminated (level 0) and depletion to minimal enrichment (level 1), while the ecological risk analysis classified them as "low risk". The mouth of the Nyando River, as well as Kisumu, Kendu, and Homa bays, were the most element-enriched and should be prioritised for focused monitoring and remediation. As a result, targeted land management of urban, industrial, transportation, and agricultural areas offers the opportunity to reduce sediment inputs into the lake ecosystem.

Evolutionary patterns and influencing factors of relationships among ecosystem services in the hilly red soil region of Southern China.

As a crucial ecological protection area in China, the Southern hilly red soil region is characterized by uneven spatial and temporal distribution of ecological landscape elements, unpredictable and changeable interrelationships between them, diversified driving factors, and lack of comprehensive consideration of ecosystem services. In order to better understand the interaction between ecosystem services, restore regional ecology, and promote sustainable development, the evolution law and influencing mechanism of ecosystem services and their driving factors are quantitatively analyzed in the study. Based on simulations of different ecosystem services from 2000 to 2020, their spatial and temporal changes and the contributions of main drivers are quantified, their trade-offs and synergies are analyzed, and the changing rules under the influence of natural factors and socioeconomic factors are explored. The results show that (1) the crop production significantly increases in the southwest and north regions, the habitat quality decreases in urban and coastal areas, and the soil retention and water yield show an increasing trend from west to east. (2) Land use/cover is the main driver of carbon storage and habitat quality variation, and precipitation is an important driver of water yield spatial variation. (3) The crop production and the other four ecosystem services show a trade-offs relationship, and the relationship between supporting services and regulating services is the synergetic. (4) The altitude weakens the synergistic relationship between soil retention and habitat quality/carbon storage, while it enhances the synergistic relationship between soil retention and water yield. Driven by precipitation factors, ecosystem services related to water yield have significant differences in the change. The population density enhances the trade-offs of crop production and soil retention, as well as the synergistic relationship between soil retention and habitat quality/carbon storage. In different land use/cover (LULC), the influence of urban land on ecosystem services relationship change is more obvious. Overall, this study can provide scientific bases and policy suggestions for ecosystem protection/restoration in the red soil region of Southern China, which has an important theoretical and practical significance.

Remote Sensing &amp; GIS Integration Bases Evaluation of Ground Water Quality in Telangana State, India

About 85% of drinking water needs in rural and 40% drinking water needs in urban areas are met from groundwater resources in Telangana state. There is a huge demand of ground water for different uses like agriculture, drinking and industrial purposes as the command area is very low in the state and it is evidenced by the fact that around 70% irrigation is dependent on ground water sources as compared to other surface sources like Tanks/Canals/Reservoirs etc. Climate change has affected the hydrological cycle with uncertain and increased variability in rainfall followed by with high rainfall in a short span of time resulting more surface runoff which ultimately decreases there charge to groundwater. Decreased recharge to the groundwater and excess withdrawal of groundwater has accelerated the depletion of groundwater resources there by resulting in stress on groundwater regime in terms of quality as well as quantity. The groundwater quality evaluation of Telangana state is carried out by using legacy quality data (2012-14) collected from Rural Water Supply &amp; Sanitation Department, Government of Telangana. Contamination spread of groundwater is one of the most important concerns that have received attention at regional, local and global levels because of their importance on public health and its further impact in ecosystems. The spatial distribution of chemical parameters like pH, Total Dissolved Solids (TDS), Total Hardness (TH), Total Alkalinity (TA), Fluoride (F), Chloride (Cl), Iron (Fe), Nitrate (NO3) and Sulfate (SO4) are examined with respect to its contamination level. The spatial distribution and concentration of chemical elements is carried out by using spatial interpolation technique namely Inverse Distance Weightage (IDW) method from the point source data. The distribution maps reveal important information to understand the hot spot areas of the groundwater systems and for identification of potential areas for providing safe drinking water supply. Site specific water conservation and artificial recharge measures are needed to be taken up with scientific lines by using Remote Sensing &amp; GIS techniques, for enhancing the groundwater storage and also improving its quality.