Western Sites Research Articles

Fifty percent overestimation of black carbon concentration measured in aerosols of the Tibetan Plateau

Elemental carbon (EC), also known as black carbon, plays an important role in climate change. Accurately assessing EC concentration in aerosols remains challenging due to the overestimations caused by carbonates and organic carbon (OC) during thermal-optical measurement in the Tibetan Plateau (TP). This study evaluates the extent of EC overestimated by carbonates and OC at four remote sites (Nyalamu, Lulang, Everest and Ngari) in southern and western of the TP using different treatments. The average overestimation of EC concentration due to acid treatment was consistent across all sites (25.5 ± 2.4 %). After correction, the proportion of EC overestimated by carbonates were approximately 8.5 ± 7.3 %, 12.3 ± 6.9 %, 18.1 ± 11.8 % and 22.7 ± 13.3 %, respectively, revealing an increasing trend from humid to arid regions. Methanol-soluble OC (MSOC) concentrations were significantly correlated with the reduction of EC concentrations, indicating that the methanol extraction effectively mitigates EC overestimation. Seasonal variation of carbonaceous aerosol concentrations was significantly affected by sources from South Asia. Despite the variations in climate and aerosol sources, the average overestimations of measured EC concentration by carbonates and OC were similar at Nyalamu (49.4 ± 14.0 %), Lulang (47.8 ± 8.4 %), Everest (48.7 ± 15.9 %) and Ngari (49.3 ± 13.7 %) sites. Therefore, the actual EC concentrations were only about 51.2 ± 13.1 % of the original values. This estimation will significantly enhance the contribution of brown carbon (BrC) to radiative forcing relative to EC, highlighting a critical area for future research. Investigating the actual concentrations of EC in the TP provides critical data to support model simulation and validate model accuracy, further enhancing our understanding of EC’s impacts on climate warming and glacier melting.

Evaluation of the ecological quality of the macroalgal communities along the Algerian coast (Algeria, Mediterranean Sea)

The assessment and preservation of the marine environment, particularly coastal ecosystems, has emerged as a global priority. In this study, the rocky bottom quality (CFR) index, which is based on macroalgae composition and abundance, was used to assess the ecological quality of coastal waters at six sites along the Algerian coast that represent a wide range of anthropogenic pressures. The sensitivity of the CFR index to the anthropogenic pressure index (MALUSI) was also assessed. Multivariate analyses (DCA, nMDS, cluster, SIMPER, and PCA) were used to assess the variability of macroalgal community structure. The CFR index calculated for this study was compared to the EEI-c and CARLIT indices. The CFR index classified the study sites based on ecological quality: good to high quality in the western sites (Ténès, Kouali1, and Kouali2) and moderate quality in the central sites (Fontaine, Fort de l’eau, and Surcouf). The findings indicate that the CFR and MALUSI indices are highly correlated. The abundance and composition of macroalgal communities are useful indicators of rocky shore quality, as demonstrated by structural analyses of characteristic macroalgae and opportunistic species. The competitive characteristic macroalgae of the Cystoseira sensu lato species were found to be associated with sites of good and high ecological quality. Stress-tolerant characteristic macroalgae (Pachymeniopsis lanceolata, Ellisolandia elongata, and Halopteris scoparia) and opportunistic ruderal species (Ulva rigida, Ulva lactuca, and Ulva linza) were found in sites with moderate ecological quality. The CFR index was compared with the EEI-c and CARLIT indices, and it can be noted that the three indices use different spatial scales, biological levels and species classifications. Therefore, CFR, EEI-c, and CARLIT indices are useful tools for assessing the quality of coastal waters.

Nexus between Western and Chinese crude oil mining firms: An examination of modalities, practices, and socio-ecological ramifications

This study examines the operational methods, procedures, and socio-ecological impacts of Western and Chinese crude oil extraction industries, focusing on regional variations. Due to institutional dynamics, the study reveals distinct emissions patterns among state-owned sectors in China and the Western Union region. This was achieved by employing DID regression models, using a sample of 60 crude oil mining companies. Furthermore, the data demonstrates that intensifying research and development endeavors directly correlate with pollution reduction, indicating that technological advancements could foster a greater sense of environmental consciousness. Nevertheless, larger corporations emit more pollution, substantially utilizing resources and manufacturing. Both nations prioritize the government's role in reducing negative environmental impacts caused by pollution by implementing regulatory frameworks. Additionally, they focus on achieving long-term ecological sustainability through corporate social responsibility (CSR) initiatives. The paper suggests government involvement is necessary to enhance socio-ecological conditions at crude oil mining sites in Western and Chinese regions.

Spatial planning offshore wind energy farms in California for mediating fisheries and wildlife conservation impacts

Achieving a blue economy will require reconciling the value of emerging ocean uses with their impacts on the seascape and sectors with historical access to marine resources and areas. To meet this challenge, we developed an analytical framework for conducting marine spatial planning through tradeoff analysis, and applied it to prospective offshore wind energy development in the ∼974 km2 Morro Bay, California, USA Wind Energy Area (WEA). We generated spatial data layers estimating MW power production and impacts on fisheries value and marine wildlife conservation (seabird and cetacean populations) from wind farm development. We then quantified each sector's response to plans of development across the WEA and inside three leases recently acquired by the energy industry for prospective development. Finally, we integrated the sector response data into an analytical framework for mitigating sector tradeoffs with novel spatial planning solutions (maps of wind farm size, location, and configuration) that optimally maximize value to the emergent energy sector (MW power) while minimizing impacts to historical (fisheries and wildlife) sectors. We found that western sites in the WEA had the highest potential power production concurrent with the lowest impact on the historical sectors, revealing the eastern lease to be less efficient at optimally balancing the sector's objectives relative to the development of the central or western leases or the optimal spatial plans identified in the tradeoff analysis. Within a lease, tradeoff analysis found spatial planning able to generate out-sized savings in fisheries value with only modest losses in MW power – for example, by avoiding development in just 5% of the eastern lease to preserve nearly half its fisheries value and still generate 95% its total power potential. Small-scale development opportunities (e.g., a pilot project) with significant power potential and no fisheries impact were also identified, in this case by placing turbines in an area in the western lease with no fisheries value and high power production potential. These plans would also have a relatively low impact on the wildlife conservation sectors, due to decreases in vulnerability levels of both seabird and cetacean populations to turbines going from east to west across the WEA. Our results can inform site evaluation and permitting processes for wind energy development in the Morro Bay WEA. We also expect the tradeoff analysis framework we developed to provide a simple and actionable analytical tool for supporting marine spatial planning of offshore wind energy and other emerging blue economy activities from a balanced perspective that values emerging uses of marine resources alongside existing socio-economic and conservation interests.

Molecular Identification, Multigenic Characterization and Phylogenetic Analysis of Ctenocephalides Canis Fleas from Humans and Domestic Animals in Iran.

Fleas belonging to the Pulicidae are prevalent ectoparasites infesting mammals and birds in Iran. This study focused on genetically identifying and characterizing Ctenocephalides canis collected both off-host and infesting humans and various domestic animals in the country. A total of 918 adult flea samples were collected from 10 sites in western and northwestern Iran between April 2018 and May 2019. Out of these, 71 specimens were found off-host, while the remaining fleas were collected from humans (121), sheep (126), goats (184), and dogs (416). Morphological identification at the genus level was performed on all fleas, and ten selected specimens selected based on the sampling sites and hosts were subjected to molecular detection at the species level by using partial amplification and sequencing of the internal transcribed spacer 1 and 2, as well as the cytochrome oxidase I (COXI) markers. The morphological identification confirmed all fleas as Ctenocephalides spp. Alignment and phylogenetic analysis of nuclear and mitochondrial partial sequences confirmed the presence of C. canis. However, molecular divergence was observed among the ten isolates based on the ITS1 and ITS2 with diversity rates estimated at 0.15% and 3.36%, respectively. Notably, the analysis of the COXI marker revealed no molecular divergence among the partial sequences representing the ten studied isolates from C. canis. This study explores the diversity of C. canis in the western and northwestern regions of Iran, providing insights into their molecular taxonomy and potential role as disease vectors in these areas.

Tasmanian devil (Sarcophilus harrisii) gene flow and source-sink dynamics

Increased access to genetic data has substantially improved how we manage threatened species. The Tasmanian devil (Sarcophilus harrisii) is listed as endangered due to the ongoing threat of a highly contagious cancer, devil facial tumour disease (DFTD), causing more than 80% population reductions. To assist future management interventions (e.g. releases into wild sites) we expanded upon previous studies of gene flow for the devil by assessing more recent and broad-scale patterns. We use genome-wide single nucleotide polymorphisms generated via DArTSeq across 21 devil sites to delineate source-sink dynamics across the species’ range. Our findings revealed gene flow is stronger on the northeast and central regions of Tasmania, with high rates of bidirectional gene flow among central sites. The northwest exhibits weaker connectivity relative to other regions of Tasmania, while gene flow appears to be non-existent between the southwest and other areas. Northeast coastal sites tend to serve as ‘sources’ for inland central sites, whereas gene flow appears restricted to the coastline in the northwest. These results are consistent with genetic structure of devil sites and spatial spread of DFTD, which has yet to arrive in the southwest region of Tasmania. Southwest isolation is probably due to mountain ranges and lack of roadways. Interestingly, some waterbodies did not appear to restrict devil movement among sites. Conversely, areas of high elevation act as apparent barriers, as evidenced by limited gene flow observed between eastern and western sites. Integrating source-sink dynamics into conservation management planning will be crucial in developing effective strategies to safeguard the Tasmanian devil and other threatened species facing similar threats (i.e. disease, habitat loss).

Recent shallow-water benthic foraminifera from a tropical estuary, SW Nigeria

This paper presents a comprehensive survey of benthic foraminifera from shallow waters of the Apapa-Badagry Creek estuary in southwestern Nigeria. Sediments of the Apapa-Badagry Creek, an important estuary surrounded by sprawling estates and industrial parks, yielded diverse assemblages of benthic foraminifera with a total of eighty-eight species. They include hyaline-perforate taxa which dominated the inner western sites around the Lagos Harbor in the Apapa Creek with Ammonia aoteana, A. tepida, A. convexa, Ammonia sp. 1, Ammonia sp. 2. Agglutinated taxa are well established in the westernmost areas in the Badagry Creek, where there is seamless fresh-water mixing, with high populations of Ammotium salsum and few occurrences of Milliamina fusca and Ammobaculites species. The miliolids, represented mainly by species of Quinqueloculina, occupy sample stations in the Commodore Channel which flourish under conditions of marine and tidal influences. Cribroelphidium mirum, Pararotalia sarmientoi, Bolivina striatula and Rosalina species are also found within the Commodore Channel sediments. Our study widely extends and completes previous studies from the tropical eastern Atlantic, especially within the Gulf of Guinea and provides new information on the distribution, diversity, and species richness of shallow-water benthic foraminifera fringing the Atlantic coast of Africa.

Carbonate system variability in the Mediterranean Sea: a modelling study

A basin-scale Mediterranean carbonate system model has been setup, building on the POSEIDON operational biogeochemical model. The spatial variability of carbonate system variables from a 13-year simulation (2010-2022) was validated against CARIMED in situ data (DIC, TA, pCO2), showing reasonable agreement in reproducing the observed patterns and preserving the dynamics in different areas, except a slight overestimation (~15 µmol/kg) of TA in the Eastern Levantine. The time-variability of model outputs (DIC, TA, pCO2, pH) was validated, against available time-series from Western (DYFAMED, Villefranche-PointB) and Eastern Mediterranean (HCB) sites, showing good agreement with the data, particularly for pCO2, pH and DIC. The model failed to reproduce the observed late summer peak of TA at DYFAMED/PointB sites, which may be partly attributed to the advection of lower alkalinity Atlantic water in the area. The seasonal variability of DIC and pCO2@20°C was found to be mainly controlled by winter mixing and the subsequent increase of primary production and net CO2 biological uptake, which appeared overestimated at HCB. Along with the reference simulation, three sensitivity simulations were performed, de-activating the effect of biology, evaporation and CO2 air-sea fluxes on DIC and TA, in order to gain insight on the processes regulating the simulated carbonate system variability. The effect of biological processes on DIC was found more significant (peak during spring) in the more productive North Western Mediterranean, while evaporation had a stronger impact (peak during late summer) in the Levantine basin. CO2 air-sea flux was higher in the Western Mediterranean, particularly the Gulf of Lions and Alboran Sea, as well as in river influenced areas, such as the N. Adriatic and along the pathway of the Black Sea Water in the Aegean. A weak release of CO2 was found in the Eastern Levantine and Libyan Sea. Its basin average (+2.1 mmol/m2/day) and positive trend (+0.1 mmol/m2/day/year) indicates a gradually increasing net CO2 ocean uptake. The simulated positive trends of DIC (0.77 μmol/kg/year) and TA (0.53 μmol/kg/year) in the North Western Mediterranean were consistent with observational and modelling studies, in constrast with the Levantine basin, where no significant trends were found for TA.

Re-investigation of fossil Lemmini specimens from the early and Middle Pleistocene of Western and Central Europe: Evolutionary and paleoenvironmental implications

The current study focuses on the emblematic Myopus/Lemmus species complex (tribe Lemmini) in the European Pleistocene fossil record. The members of the two genera occupy distinct ecological niches and have different external appearances, but they are remarkably similar in their dental morphology, so that they were commonly thought of as undistinguishable in the fossil record. Thus, more or less all European Lemmini fossils have been assigned to the genus Lemmus. In the Early Pleistocene site of Schernfeld (Germany), the species Lemmus kowalskii had been described. It was thought by some authors that all Lemmini from Early to late Middle Pleistocene belong to this species.In the current study, we investigated Lemmini molar morphology from Western and Central European sites including Schernfeld (Early Pleistocene), Sackdillinger Höhle (Sackdilling Cave), and Koněprusy C718 (both early Middle Pleistocene), as well as other fossil localities with fewer specimens, formerly assigned to Lemmus kowalskii. Using an extensive modern referential material of Lemmus and Myopus, this study proposes to re-evaluate taxonomic status of the Middle and Early Pleistocene Lemmini. This modern referential also allows a better understanding of the morphology of Lemmus kowalskii specimens and its variability.Our results highlight the very high variation within fossil populations, as well as significant statistical differences between populations of the Early and Middle Pleistocene localities. A large part of these fossil specimens is firmly identified as Myopus sp., including the L. kowalskii holotype. Our identifications demonstrate that in most Early and Middle Pleistocene sites considered in this study, both genera (Lemmus and Myopus) are present. Possible interpretations and consequences for current view of lemming history are discussed, as well as some of the paleoecological and paleoenvironmental implications.

Intriguing Occupations at Gran Dolina (Atapuerca, Spain): the Acheulean Subunits TD10.3 and TD10.4

This paper presents the zooarchaeological, technological, use-wear, and spatial analyses of the earliest sedimentary subunits of TD10 (TD10.3 and TD10.4) of the Gran Dolina site (Sierra de Atapuerca, Burgos, Spain), dated to c. 400 ka. Both units have yielded Acheulean technology, with occupational models characterized by the superimposition of multiple and independent events paired with short, sporadic occupations. Subunits TD10.3 and TD10.4 formed during a period in which the cave was largely reopened after a temporary closure. This period of reopening is evidenced by several blocks that fell from the ceiling and walls. Fifty-seven groups of refits and anthropic conjoins, of which 43 resulted from deliberate hominin activity, confirm the low disturbance of the deposits. Contrary to TD10.4, TD10.3 shows good preservation of faunal remains, although anthropogenic modifications are very scarce. Technologically, both deposits represent well-developed Acheulean assemblages, with high proportions of large-shaped tools and percussive material, which place this area among those that have yielded the most evidence of this type among all the excavated Atapuerca sites. The question of why these subunits contain so many hammerstones, manuports, and large tools associated with faunal remains that have been so scarcely modified is discussed based on data from spatial, technical, and use-wear analyses, which have identified butchery activities, and for the first time in the Pleistocene Atapuerca record, borer elements and possible thrusting stone spear tips. Furthermore, the occupational and technological characteristics of these subunits were compared with other western European archaeological sites, including the nearby site of Galería, with which a broad correlation can be made.

Exposure of African ape sites to climate change impacts

Large gaps remain in our understanding of the vulnerability of specific animal taxa and regions to climate change, especially regarding extreme climate impact events. Here, we assess African apes, flagship and highly important umbrella species for sympatric biodiversity. We estimated past (1981–2010) and future exposure to climate change impacts across 363 sites in Africa for RCP2.6 and RCP6.0 for near term (2021–2050) and long term (2071–2099). We used fully harmonized climate data and data on extreme climate impact events from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Historic data show that 171 sites had positive temperature anomalies for at least nine of the past ten years with the strongest anomalies (up to 0.56°C) estimated for eastern chimpanzees. Climate projections suggest that temperatures will increase across all sites, while precipitation changes are more heterogeneous. We estimated a future increase in heavy precipitation events for 288 sites, and an increase in the number of consecutive dry days by up to 20 days per year (maximum increase estimated for eastern gorillas). All sites will be frequently exposed to wildfires and crop failures in the future, and the latter could impact apes indirectly through increased deforestation. 84% of sites are projected to be exposed to heatwaves and 78% of sites to river floods. Tropical cyclones and droughts were only projected for individual sites in western and central Africa. We further compiled available evidence on how climate change impacts could affect apes, for example, through heat stress and dehydration, a reduction in water sources and fruit trees, and reduced physiological performance, body condition, fertility, and survival. To support necessary research on the sensitivity and adaptability of African apes to climate change impacts, and the planning and implementation of conservation measures, we provide detailed results for each ape site on the open-access platform A.P.E.S. Wiki.

Ecotypic variation in multiple traits of European beech: selection of suitable provenances based on performance and stability

Induced by climate change associated disturbances and further promoted by changes in forest management, the proportion of European beech, a highly competitive climax species, is increasing in Central Europe. However, its climatic stability is questioned by the recent loss of vitality. In this regard, the evaluation of seed sources used for reforestation receives great attention. Here, we present a multi-trait evaluation of height, basal area and stem quality assessed over 25 years for 85 provenances grown at three sites in northern, western and eastern Germany. Considerable provenance differentiation exists, explaining 21% (proportion of trees with acceptable stem form) to 45% (basal area) of the variance on single sites and 20 to 39% across sites, while provenance by environment interactions are absent. On the landscape level, this results in distinct patterns with spatially adjacent provenances showing a similar trait expression. These patterns are highly similar for height and basal area but divergent for stem form. They could be directly linked to geographic variables with multivariate regression tree analysis that captured 58% of the phenotypic variation, delineating eleven ‘ecotypes’ shaped by local adaptation. A selection based on two multi-trait indices gives highly concordant results. Particularly, the intermediate elevations of the central highlands in Western Germany host highly suitable provenances. Lower elevation provenances from continental climates in the south-east profit from the transfer to favorable growing conditions. Since the majority of provenances was already exposed to elevated temperatures compared to their origin during the observation period, this study gives a first indication for the potential benefits of assisted migration facing climate change.

Low Genetic Variability of the Tundra Vole in Lithuania.

The distribution and spread of the tundra vole (Alexandromys oeconomus) in Lithuania have been documented over the last 70 years, but the genetic diversity of the species has not been studied. In this study, we examined A. oeconomus trapped in three sites in northern and western Lithuania using mtDNA sequence analysis of the cytb and control region. The western and northern sites are separated by anthropogenic landscape barriers. The western site is subject to regular spring flooding. Phylogenetic analyses of the studied individuals placed them in the Central European phylogroup, suggesting that Lithuanian A. oeconomus originated from northeastern Poland. In Lithuania, the genetic diversity of A. oeconomus at both mtDNA loci was relatively low (Hd < 0.6, π < 0.002) compared to that found in other European samples (Hd = 0.833-0.958; π = 0.00402-0.01552). Individuals analyzed in Lithuania were genetically different from samples collected in Poland and Northern Europe (ΦST > 0.15, p < 0.05). The genetic divergence between the western and northern samples of A. oeconomus in Lithuania, together with the low genetic variability among the voles studied, provides new insights into the phylogeography of the species and the influence of barriers on the colonization of the country.

The prevalence of HDV among HBsAg-positive populations with and without HIV-1 in China

BackgroundExisting research has provided evidence of changes in hepatitis delta virus (HDV) prevalence worldwide. This study aimed to investigate the prevalence and molecular characteristics of HDV to elucidate its spread in China. MethodsA total of 3,000 samples were collected from 2,241 HBV monoinfections and 759 HBV/HIV-1 coinfections across 13 sites in northern, southern, western, and southwestern China. Serological and virological prevalence were determined by detecting anti-HDV antibodies and HDV RNA. ResultsThe study revealed a 2.63% (95% CI: 2.06–3.21) seroprevalence of HDV among HBV infections in China, exhibiting regional variation. HDV seroprevalence was notably higher at 7.91% (95% CI: 5.98–9.83) in HBV and HIV-1 coinfections. Region and HIV-1 infection were identified as risk factors for HDV infection. Virological prevalence was 0.67% (95% CI: 0.38–0.96) in HBV infections and 2.24% (95% CI: 1.18–3.29) in HBV/HIV-1 coinfections. The predominant HDV genotype in China was HDV-2a, followed by HDV-1. Participants with anti-HDV positivity demonstrated significantly higher proportions of abnormal liver dysfunction and elevated HBV DNA load (P < 0.001) compared to anti-HDV-negative participants. ConclusionsThis study highlights the HDV epidemic in China, sheds light on its geographical distribution and high-risk populations, and provides insights for developing strategies to manage the spread of HDV in the country.

Microtextures on quartz grain surfaces in the Bay of Bengal shoreline sediments, Bangladesh: Implications for sediment transport process and depositional environment

SEM and SEM-EDS studies of quartz grains in the shoreline sediments of the Bay of Bengal, Bangladesh were carried out to evaluate the mode of origin, paleoclimate, and depositional environment. A total of 38 microtexture types were identified, which were grouped into mechanical (23 features), mechanical/chemical (6 features), and chemical (9 features) origins. The morphology of quartz grains in the shorelines was dominantly sub-angular to sub-rounded in shape, which represents robust energy conditions, short residence time, low weathering, and nearby sediment provenance. The microtextures of mechanical origin such as straight and curved scratches, pits, broken edges, and crescent-shaped features were relatively abundant in the eastern site samples (Section-I) indicating high-energy, fluvial, and beach environments. The abundance of V-shaped marks and smooth surfaces of quartz grains indicate high-velocity storm conditions and/or high-energy impact events. The well-rounded outline, low relief with dish-shaped depressions, mechanically upturned plates, and arcuate steps were also observed on quartz grain surfaces. These features suggest that they were developed during an aeolian process in the beach berm environment. Etching, solution/irregular pits, and differential relief on quartz grains were somewhat elevated in the western site samples (Section-III), reflecting that these microtextures were associated with a subaqueous collision and humid climates in the fluvial and nearshore environments. Quartz grains in all sections represented microtextures of high energetic subaqueous environment as well as wind events. However, the absence of corrosion channels and high density of voids in the quartz grains revealed low degree of weathering.

Impacts of site aridity on intra-annual radial variation of two alpine coniferous species in cold and dry ecosystems

Climate change alters regional aridity and species composition in dryland ecosystems. However, the effect of varying aridity and species-specific responses on tree growth remains unclear. Here, we used high-resolution dendrometers to analyze the climatic factors controlling stem diameter variation in two alpine coniferous species, Qilian juniper (Juniperus przewalskii) and Qinghai spruce (Picea crassifolia), in their eastern- and western-most distributions (two species × two sites) in the Qilian Mountains during the 2018–2021 growing seasons. We observed species-, site-, and year-specific differences in growth phenology and radial growth dynamics. Juniper had early growth onset and cessation, but short growing season compared to spruce. Trees in the eastern sites showed earlier growth onset, later cessation, and a much longer growing season than those in the western sites for both species. Daily stem growth revealed similar responses for both species and site aridity, with daily vapor pressure deficit, maximum temperature, and solar radiation negatively, and relative humidity and precipitation positively affecting stem increments. However, when observation was extended to 7 or 21 days, the effect of precipitation on stem increments became weak or negligible in the wetter eastern sites, while continuing in the arid western sites. Further, soil water content appeared to have an impact on growth in the arid western site for both species. These results were confirmed by linear mixed-effects models, which revealed that site-aridity play an important role on tree stem variation, especially in junipers. Our results suggest that although short-term atmospheric water conditions influence radial stem variation, intra-annual tree growth still depends on soil water availability in drylands. Our findings provide new evidence of potential uses of dendrometers to measure environmental stress on tree growth and reveal that site aridity and species influence tree growth at different time scales in cold and arid ecosystems.

Energetic Complementarity Solar PV and Wind Power Based on Satellite Data

With the current global energy crisis renewable energy integration is expected to grow drastically in the near future. However, integrating high amount of renewables to the grid is subjected to various operational challenges. One solution for this challenge is looking for complementing intermittent renewable resources. In this paper solar PV and wind power complementarity analysis was carried out over the three topographic regions of Eritrea based on monthly satellite-based power generation data. Three different approaches (Pearson correlation coefficient, graphical and dimensionless index) were employed to investigate the complementarity of PV and wind power in the chosen sites. The analysis results showed that the southern coastal and central highlands sites have low complementarity behaviour. The solar PV and wind power synergy was however, found to be the maximum in the northern highlands and western lowlands sites of the country. It is interesting to find out that the high wind potential sites in southern coastal region are positively correlated to solar availability with peaks in winter and low in summer with no complementarity pattern.

Feasibility study of offshore wind energy on the coast of Sri Lanka

ABSTRACT Sri Lanka's energy issue is caused by underinvestment in renewable energy, resulting in rationing and power outages. Given its power output, offshore wind energy is a possible solution for a sustainable energy future. This study investigates the viability of an offshore wind farm by scrutinizing three potential sites, chosen based on wind speed, direction, and allied variables. Wind speed data from the ERA-5 repository and bathymetry information from the General Bathymetry Chart of Oceans support energy potential assessment for these locations. Employing the WAsP software, a technical analysis was performed to determine the energy output potential for water depths up to 50 m. Of the three sites, the western site emerged as the most productive, estimating an energy yield of 24.36 GWh from an 8 MW turbine. This calculation took into account a capacity utilization factor of 34.76%, with the levelized cost of energy approximating INR 7.70. The northern and southern sites trailed marginally, with estimated energy outputs of 20.31 GWh and 22.36 GWh, respectively. As evidenced by these findings, offshore wind energy holds promise as a dependable and steadfast energy source for Sri Lanka. It also highlights Sri Lanka's first offshore wind farm and future plans.

Subtle Responses of Soil Bacterial Communities to Corn-Soybean-Wheat Rotation

Crop rotational diversity can improve crop productivity and soil health, and boost soil microbial diversity. This research hypothesized that a 3-year rotation of corn-soybean-wheat (CSW), compared with a 2-year corn-soybean (CS) rotation, would result in a more diverse and more complex soil bacterial community, together with a greater abundance of beneficial bacteria. This was evaluated in a replicated experiment established in 2013 at two locations in Ohio (United States). The soil bacterial communities under soybean were compared between CS and CSW at both studied sites in 2018 and 2019, through 16S ribosomal DNA amplicon metabarcoding. Experimental site was the main driver of bacterial richness and evenness. Significant effects on bacterial community composition were observed in response to the interaction between site, rotational sequence, and year of study. Eight bacterial amplicon sequence variants were identified within all CSW treatments and were not present in CS. Several taxa were differentially abundant between rotation treatments, including the genera Ralstonia being more abundant in CS. Co-occurrence networks, including hub taxa, were generally different between rotation treatments and year, with more structure observed in CSW networks for one of the studied sites. Few bacterial genera were consistently identified as hubs across all networks, including an unidentified member of order Acidobacteriales, while other hubs were unique for CSW networks, including members of the family Gemmatimonadaceae. Finally, the composition of the bacterial communities at the northwestern site positively correlated with plant biomass and active carbon, whereas more recalcitrant pools (total carbon and organic water) correlated with the bacterial communities at the western site.

Molecular characterization of organic aerosols over the Tibetan Plateau: Spatiotemporal variations, sources, and potential implications

Organic aerosols have profound and far-reaching influences on the Earth's climate, ecosystems, environmental quality, and public health. Elucidating the precise composition and sources of these aerosols over the Tibetan Plateau, a region highly sensitive to climate change and vulnerable to ecosystems, is critically important. Sixteen organic molecular tracers in aerosols were quantified using solvent extraction-BSTFA derivatization, and GC/MS analysis at six sites over the Tibetan Plateau during 2014 and 2016. Average total tracer concentration was 32.5 ± 20.1 ng m−3. The highest levels of biomass burning tracers (anhydrosugars and aromatic acids) were found at southeastern Tibetan Plateau site Yulong (20.8 ± 21.3 ng m−3) followed by the western site Ngari (13.3 ± 10.6 ng m−3). Biomass burning tracers decreased from southern sites like Everest (9.50 ± 10.5 ng m−3) to northern aeras such as Laohugou (2.59 ± 2.19 ng m−3). Biomass burning tracers peaked in non-monsoon seasons while primary saccharides and sugar alcohols predominated during monsoon months. Using tracer-based methods, biomass burning contributed 0.4%–8.4% of organic carbon over the plateau, with higher non-monsoon contributions (3.6% ± 3.7%). Backward air mass trajectories and fire spots indicated South Asian biomass burning impacts on organic aerosols at western, southern, and southeastern Tibetan Plateau sites, particularly in non-monsoon periods. Fungal spores and plant debris comprised 0.6%–6.3% and 0.3%–1.2% of organic carbon respectively, with higher monsoon contributions (4.2% ± 4.7%) of fungal spores. Secondary organic carbon was estimated to contribute substantially (45.5%–73.5%) over the plateau but requires further investigation. These results provide insights into pollution mitigation and the assessments of climate and ecology changes for the Tibetan Plateau.