Black Deposits Research Articles

INVESTIGATION OF SHORT-TERM CHEMICAL CHANGE IN STABLE RUTHENIUM ADDED TO RAINWATER THROUGH X-RAY ABSORPTION FINE STRUCTURE ANALYSIS.

Radioactive ruthenium may be accidentally released from spent nuclear fuel reprocessing plants to the surrounding environment. To obtain basic information regarding the effect of radioactive ruthenium on the environment, we investigated changes in the source form of stable ruthenium added to rainwater through X-ray absorption fine structure analysis. Ruthenium tetroxide (RuO4), ruthenium dioxide (RuO2), ruthenium nitrosyl nitrate (Ru(NO)(NO3)3) and ruthenium chloride (RuCl3) were employed as test sources. The Ru K-edge X-ray absorption near edge structure spectra acquired immediately after addition to ultrapure water differed among various sources. With RuO4 addition, a black deposit was observed 1 d after addition, and the spectrum was similar to that of RuO2. For RuO2, Ru(NO)(NO3)3 and RuCl3, no variances were observed between the spectra acquired immediately after addition and 1 d after addition. These results indicate that the chemical forms of RuO2, Ru(NO)(NO3)3 and RuCl3 did not change within a 1-d span in rainwater.

Spatial distribution and ecological risk evaluation of toxic metals in the southern Black Sea coastal sediments

Spatial distribution and ecological risk levels of toxic metals (Cu, Pb, Zn, Ni, Co, As, Sr, V, and La) in sediments from the southern Black Sea coastal (Türkiye) were evaluated. The sediment samples were taken in April and May 2019 from thirty-one stations, from depths ranged between 16 and 65 m. The average metal concentrations (in dry weight) varied from 59.4 ± 4.8 to 102.5 ± 12.3 for Cu, 39.3 ± 4,1 to 46.1 ± 2.9 for Pb, 104.5 ± 4.7 to 126 ± 6.9 for Zn, 21.2 ± 1.8 to 24.9 ± 1.4 for Ni, 9.8 ± 0.4 to 16.6 ± 1.5 for As, 16.7 ± 0.5 to 18.2 ± 0.9 for Co, 68.2 ± 11.4 to 123.3 ± 13.5 for Sr, 82.7 ± 13.1 to 97.3 ± 4.3 for V, and 16.2 ± 1.8 to 23.6 ± 1.8 μg g−1 for La. Geoaccumulation index (IGEO), Sediment enrichment factor (SEF), and pollution load index (PLI) indicated that Cu and Pb are above the pollution limits. Thus, continuous pollution monitoring programs should be established. Moreover, measures should be implemented more effectively to prevent pollution.

The "Infernaccio" Gorges: Microbial Diversity of Black Deposits and Isolation of Manganese-Solubilizing Bacteria.

Simple Summary“Infernaccio” gorges are one of the Earth’s hidden habitats in Central Italy. Beyond the deep incisions and high slopes, these gorges are characterized by black deposits in gorge walls and covering rock surfaces. Several geological events have shaped these unique geological formations and their microbiota. This study investigated microbial contribution to black deposit formation and isolating Mn-oxide-solubilizing bacteria. Our results provided evidence of the putative role of Bacteria and Archaea in forming manganese oxide deposits. Findings also showed that these deposits are a source of valuable strains with manganese oxide bioleaching properties, essential for bioremediation and metal recovery.The present study explored the microbial diversity of black deposits found in the “Infernaccio” gorge. X-ray Powdered Diffraction (XRPD) was used to investigate the crystallinity of the samples and to identify the minerals. Scanning electron microscope and energy-dispersive X-ray spectroscopy (SEM-EDS) were used to detect the bacterial imprints, analyze microbe–mineral interactions, and highlight the chemical element distribution in the black deposits. 16S rRNA gene metabarcoding allowed the study of Archaea and Bacteria communities. Mn-oxide-solubilizing isolates were also obtained and characterized by culturable and molecular approaches. The multidisciplinary approach showed the occurrence of deposits composed of birnessite, diopside, halloysite, and leucite. Numerous bacterial imprints confirmed the role of microorganisms in forming these deposits. The Bacteria and Archaea communities associated with these deposits and runoff waters are dynamic and shaped by seasonal changes. The uncultured and unknown taxa are the most common and abundant. These amplicon sequence variants (ASVs) were mainly assigned to Proteobacteria and Bacteroidetes phyla. Six isolates showed interesting Mn solubilization abilities under microaerophilic conditions. Molecular characterization associated isolates to Brevibacterium, Bacillus, Neobacillus, and Rhodococcus genera. The findings enriched our knowledge of geomicrobiological aspects of one of the Earth’s hidden habitats. The study also unveiled the potential of this environment as an isolation source of biotechnologically relevant bacteria.

The Black Sea Zooplankton Mortality, Decomposition, and Sedimentation Measurements Using Vital Dye and Short-Term Sediment Traps

The principal objectives of this research are to measure the non-consumptive mortality rate of marine copepod zooplankton and the sedimentation rate of copepod carcasses, using short-term sediment traps, and to reveal a correlation between the rates of the two competitive processes—sedimentation and degradation of the carcasses under turbulent mixing conditions. The traps were moored in Sevastopol Bay and adjacent coastal waters (the Black Sea) during summer and autumn seasons. A simulation model was developed to describe a wide range of processes in the trap and the water column above it and to interpret the results obtained with the sediment traps. Significant changes in the abundance of copepod carcasses (from 280 to 12,443 ind. m−3) and their fraction in the total zooplankton abundance (53 to 81%) were observed in the waters over short time periods, indicating a high variability of zooplankton mortality, sedimentation, and decomposition rates. Despite the high concentrations of copepod carcasses in the water column, the rates of their accumulation in the traps proved to be extremely low, which could be due to intense turbulent mixing of the waters. The carcass sedimentation rate and the flow of swimmers (motile copepods) into the traps were significantly higher in waters subjected to weaker turbulent mixing. The obtained estimates of the sedimentation rate of copepod carcasses (0.012 to 0.39 d−1) were comparable in value with the rate of their microbial decomposition (0.13 and 0.05 d−1 in the bay and adjacent waters, respectively). This confirmed the hypothesis on microbial decomposition as one of the key controls of the fraction of live zooplankton organisms in zooplankton.

EFFECT OF LEAD NITRATE ON HAEMOCYTE MORPHOLOGY OF FRESHWATER PRAWN, Macrobrachium dayanum (CRUSTACEA-DECAPODA)

Lead (Pb), a non-essential “Grey listed” heavy metal is a serious threat to aquatic flora and fauna. The haematological, nephrological, histopathological and neurological effects of lead are well known in vertebrates. Present study aims to investigate effect of lead on morphology of haemocytes, a important component of immune system of freshwater prawn, Macrobrachium dayanum. Prawns, collected at “Gulala-Ghat” from river Gomti, Lucknow, subjected to acute and sub-acute concentrations of lead nitrate (116.46 mg/l, 96h LC50; 29.12 mg/l, 25% of 96h LC50) showed morphological changes in haemocytes after 24, 48, 72 and 96h in acute exposure and after 10, 20 and 30 days in sub-acute exposure. The chief morphological changes like surface blebbing, vacuolization, cytoplasmic darkening, fragmentation of nuclear material, cone formation, nuclear pycnosis and breaking of plasma membrane were noticed after acute exposure (116.46 mg/litre). Black granular depositions, nuclear pycnosis and fragmentation of nuclear material; pseudopodial projections, blackening of the plasma membrane, achromatia were observed after sub-acute exposure (29.12 mg/litre). These changes were pronounced in prohaemocytes, granulocytes, plasmatocytes and spindle cells. The severity of morphological changes was dose- and duration-dependent. The present study found a positive correlation between heavy metal lead exposure and morphological changes in haemocyte morphology leading to severe immune dysfunction in freshwater prawn M. dayanum. This parameter can be used as bio-marker in health monitoring of prawns as well as environmental monitoring without sacrificing the animal.

The microbiome of phosphate-rich deposits in Muierilor Cave, South-Western Carpathians

Muierilor Cave is one of the most important caves in Romania from paleontological, biological, and archaeological points of view. A newly discovered chamber, with unique yellow calcite crystals, fine-grained crusts, and black sediments, is connected to the upper levels that contains fossil bones and a large pile of guano. Samples were taken from this chamber and another passage to investigate the diversity of microorganisms related to the substrates and identify potential pathogenic taxa for humans and animals. Chemical, mineralogical, and whole community 16S rRNA gene-based metabarcoding analyses were undertaken, and the base of the guano deposit was radiocarbon dated. Metabarcoding of the analyzed samples found that ~16% of the identified bacteria are potentially pathogenic to humans. Moreover, more than 87% of the identified genera were not previously reported in caves. We identified bacteria involved in the phosphate cycle that can only originate from the organic deposits inside the cave, such as the bats' guano in the touristic, upper level, or the fossil bones. Our study indicate also the guano deposit as the possible source of potentially pathogenic microorganisms. The results on the microbiome of different deposit types unravel the diversity of microorganisms and indicate the potentially pathogenic taxa for humans and animals.

Application of principal component analysis and a spectrum-area fractal model to identify geochemical anomalies associated with vanadium mineralization in northeastern Jiangxi Province, South China

The Jiujiang region in northeastern Jiangxi Province is known for hosting many black shale-type vanadium deposits, which are mainly found in the Cambrian Hetang Formation and Sinian Piyuancun Formation. In this paper, based on stream sediment data, principal component analysis (PCA) and spectrum–area (S–A) fractal modelling are used to identify geochemical anomalies associated with vanadium (V) mineralization. First, a dataset containing 957 samples of stream sediments with 39 elements was processed using correlation analysis and cluster analysis to find the closest V-related elements, and Ag and Cd were obtained. Secondly, the raster maps of V, Ag and Cd were created using multifractal inverse distance-weighted interpolation. PCA was then employed to combine the concentration values of V, Ag and Cd into a single variable representing the internal relationships among the three elements. Finally, S–A analysis was used to decompose the first component pattern obtained through PCA and to extract anomalies from the complex background. The results show that the known V deposits are located within highly anomalous areas, which are well corelated with the distribution of black shales of the Hetang and Piyuancun Formations. It is suggested that the northeastern part of Jiangxi Province potentially hosts undiscovered V deposits, and the identified anomalies could be further used to guide mineral exploration.Thematic collection:This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at:https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis

Experimental Study of Al-Modified Zeolite with Oxygen Nanobubbles in Repairing Black Odorous Sediments in River Channels

As an extreme phenomenon of water pollution, black odorous water not only causes ecological damage, but also severely restricts urban development. Presently, the in situ remediation technology for sediment from river channels is still undeveloped, and there are many bottlenecks in the key technologies for sediment pollution control and ecological restoration. In this study, three experimental tanks were used to explore the restoration effect of Al-modified zeolite with oxygen nanobubbles on black odorous sediment from the Shichuan River. One of the tanks housed Typha orientalis and Canna indica L. (TC), another tank housed the same plants and had Al-modified zeolite with oxygen nanobubbles (TC+AMZON), and the last tank was used as a comparison test (CS). The results show that the nitrogen (N) and phosphorus (P) in the sediment are violently released into the surrounding water. However, TC+AMZON could effectively inhibit the release of P. The released amount of soluble reactive phosphorus (SRP) from the pore water in the sediment reached its maximum at 40 d, and the amounts were 122.97% and 74.32% greater in TC and CS, respectively, than in TC+AMZON. However, the released amount of total phosphorus (TP) reached its maximum at 70 d, and the amounts were 260.14% and 218.23% greater in TC and CS, respectively, than in TC+AMZON. TC+AMZON significantly increased the dissolved oxygen (DO) and the oxidation-reduction potential (ORP) of pore water in the sediment in the early stages of the test. At 0 d, the DO content in TC+AMZON reached 10.6 mg/L, which is 112.0% and 178.95% greater than in TC and CS, respectively. The change law of ORP in the sediment is consistent with the DO. TC+AMZON significantly improved the transparency and reduced the content of chlorophylla in the upper water and could slightly reduce the N and P content in overlying water. The transparency of TC+AMZON increased by 130.76% and 58.73%, and chlorophylla decreased by 55.6% and 50.0% when compared to TC and CS, respectively.

Unravelling the Deformation of Paleoproterozoic Marbles and Zn-Pb Ore Bodies by Combining 3D-Photogeology and Hyperspectral Data (Black Angel Mine, Central West Greenland)

The Black Angel Zn-Pb ore deposit is hosted in folded Paleoproterozoic marbles of the Mârmorilik Formation. It is exposed in the southern part of the steep and inaccessible alpine terrain of the Rinkian Orogen, in central West Greenland. Drill-core data integrated with 3D-photogeology and hyperspectral imagery of the rock face allow us to identify stratigraphic units and extract structural information that contains the geological setting of this important deposit. The integrated stratigraphy distinguishes chemical/mineralogical contrast within lithologies dominated by minerals that are difficult to distinguish with the naked eye, with a similar color of dolomitic and scapolite-rich marbles and calcitic, graphite-rich marbles. These results strengthen our understanding of the deformation style in the marbles and allow a subdivision between evaporite-carbonate platform facies and carbonate slope facies. Ore formation appears to have been mainly controlled by stratigraphy, with mineralizing fluids accumulating within permeable carbonate platform facies underneath carbonate slope facies and shales as cap rock. Later, folding and shearing were responsible for the remobilization and improvement of ore grades along the axial planes of shear folds. The contact between dolomitic scapolite-rich and calcitic graphite-rich marbles probably represents a direct stratigraphic marker, recognizable in the drill-cores, to be addressed for further 3D-modeling and exploration in this area.

Graphite/Carbon Black Counter Electrode Deposition Methods to Improve the Efficiency and Stability of Hole-Transport-Layer-Free Perovskite Solar Cells.

The interfacial compatibility between the graphite/carbon black composite counter electrode (Gr/CB CE) and the perovskite layer is a crucial determinant of the performance of the hole-transport-layer-free carbon-based perovskite solar cells, and judicious selection of the Gr/CB CE application method is essential for achieving an optimum contact. In this work, three different types of Gr/CB CEs application methods are investigated: (1) deposition of Gr/CB on the fluorine-doped tin oxide (FTO) substrate, followed by clamping to the perovskite layer, (2) direct deposition of Gr/CB onto the perovskite layer, and (3) deposition of Gr/CB onto the PbI2 precursor layer, followed by immersion in methylammonium iodide solution for the in situ conversion of PbI2 to perovskite. The results revealed that Method 3 produced superior Gr/CB–perovskite contacts, resulting in up to 8.81% power conversion efficiency. The devices prepared using Method 3 also exhibited the best stability in the air, retaining 71.1% of their original efficiency after 1600 h of continuous testing. These results demonstrate that Gr/CB CEs can be considered excellent alternatives to the costly noble metals often employed in perovskite solar cells (PSCs) when deposited using a suitable technique.

Qualitative Mineralogical Analysis of Deep-Sea Sediments Based on the Lithology in the Offshore Mannar Basin by using FTIR and XRD Techniques

The Mannar Basin, with a total area of 45,000 km2, is a key sedimentary basin for petroleum prospecting in Sri Lanka. It stretches from southeast India to southwest Sri Lanka and the basin is made primarily of Precambrian high-grade metamorphic rocks. In 2011, Cairn Lanka Private Limited (Cairn) drilled three exploration wells (Dorado, Dorado North, and Barracuda) and one exploration well (Wallago) in the recent petroleum exploration in Mannar basin. Source rock quality and maturity are important factors to consider when evaluating oil and gas potential. As a result, mineralogy plays an important role in the geochemical characterization of source rocks. In this study sediment samples of Barracuda exploration well in Mannar basin were collected from Petroleum Resources Development Secretariat in Sri Lanka (PRDS) at depth ranging from 2,260 to 4,740 m, and the samples were cleaned before analysis to eliminate drilling mud. The powdered material was made by crushing the cleansed sediment samples with a motor and petal, then screening them through a 53 µm standard sieve. After that sediment samples were analyzed through Fourier Transformation Infrared Spectroscopy (FTIR) and X-Ray Diffractometer (XRD) to obtained the available mineralogy qualitatively. The observed data were interpreted based on sample age, depth, and lithology, as well as their impact on the Mannar basin. According to previous research, the detected FTIR band wavelengths were used to determine the accessible mineralogy of the samples. The XRD peaks were determined using Crystal Impact Match 3.0 software and literature. The presence of quartz, feldspar, kaolinite montmorillonite, and calcite in the entire marlstone and mudstone samples is confirmed by FTIR analysis. The XRD analysis revealed that calcite, and quartz are dominant in marlstone with black carbon sediment samples and marlstone sediment samples. Quartz, illite, and calcite dominate in argillaceous marlstone sediment samples. Illite, montmorillonite, kaolinite, and calcite are dominant in slightly calcareous mudstone sediment samples. Quartz overgrowth and cementation were caused by the presence of quartz. In the Mannar Basin, quartz cementation can reduce reservoir rock porosity and have an effect on permeability by increasing rock brittleness and occupying pore space. Overgrowths of quartz reduce reservoir porosity and permeability. Feldspar alteration changes porosity and permeability, whereas dissolution increases secondary porosity and permeability of source rock in the basin. Clay minerals have an impact on hydrocarbon formation, accumulation, migration, and reservoir quality in the basin. Also, tectonics and sedimentation modify the abundance and crystal structure of clay minerals. Furthermore, the presence of carbonate minerals and hematite is responsible for the cement's creation. Calcite cement has an effect on the basin's reservoir quality, while hematite cement is uncommon.
 Keywords: Mannar basin, Sediment, Mineralogy, FTIR, XRD

Memory Effects in Salinity Profiles From Black Sea Sediments

AbstractThe current saline state the Black Sea is only the latest of a series of freshening‐salinization episodes that have affected that body of water during past glacial‐interglacial cycles. Here, we model the salinity history of the basin and its sedimentary porewaters since the end of the penultimate saline period, variously thought to have occurred in the period between 128 and 65 Kyrs BP (Before Present). Our results argue that the down‐core salinity profiles of Black Sea Holocene sediments have been affected by upward diffusion of salt from the penultimate saline episode and possibly from residual salinity of the basin waters captured in the accumulating porewaters. Our retrodictions require that the Black Sea bottom waters be either fresh or weakly brackish (S ≤ 4), between 80 and 10 Kyrs BP. In addition, we find that the timing of the first deposition of the Holocene sapropel corresponds to the time when salty bottom waters first reached the surface waters, and we speculate that increased organic matter production was caused by the release of nutrients stored in the saline bottom water. Finally, using current salinity proxy data, we find that the porewater salinity profiles generated from these proxies do not match the observed interstitial profiles.

A 16S rRNA Gene-Based Metabarcoding of Phosphate-Rich Deposits in Muierilor Cave, South-Western Carpathians.

Muierilor Cave is one of Romania’s most important show caves, with paleontological and archeological deposits. Recently, a new chamber was discovered in the cave, with unique yellow calcite crystals, fine-grained crusts, and black sediments. The deposits in this chamber were related to a leaking process from the upper level that contains fossil bones and a large pile of guano. Samples were taken from the new chamber and another passage to investigate the relationship between the substrate and microbial community. Chemical, mineralogical, and whole community 16S rRNA gene-based metabarcoding analyses were undertaken, and the base of the guano deposit was radiocarbon dated. Our study indicated bacteria linked to the presence of high phosphate concentration, most likely due to the nature of the substrate (hydroxyapatite). Bacteria involved in Fe, Mn, or N cycles were also found, as these elements are commonly identified in high concentrations in guano. Since no bat colonies or fossil bones were present in the new chamber, a high concentration of these elements could be sourced by organic deposits inside the cave (guano and fossil bones) even after hundreds of years of their deposition and in areas far from both deposits. Metabarcoding of the analyzed samples found that ∼0.7% of the identified bacteria are unknown to science, and ∼47% were not previously reported in caves or guano. Moreover, most of the identified human-related bacteria were not reported in caves or guano before, and some are known for their pathogenic potential. Therefore, continuous monitoring of air and floor microbiology should be considered in show caves with organic deposits containing bacteria that can threaten human health. The high number of unidentified taxa in a small sector of Muierilor Cave indicates the limited knowledge of the bacterial diversity in caves that can have potential applications in human health and biotechnology.

Synergistic Effects of Calcium Peroxide and Fe3O4@BC Composites on AVS Removal, Phosphorus and Chromium Release in Sediments

Black odorous sediment pollution in urban areas has received widespread attention, especially pollution caused by acidified volatile sulfide (AVS), phosphorus and heavy metals. In this study, an Fe3O4@BC composite was fabricated by the coprecipitate method of Fe3O4 and biochar (BC) and was mixed with calcium peroxide (CP) for sediment pollution treatment. The results showed that the AVS removal rate could reach 52.8% in the CP+Fe3O4@BC system and −18.1% in the control group on the 25th day. AVS was removed in the following three ways: AVS could be oxidized with oxygen produced by CP; H2O2 produced from CP also could be activated by Fe2+ to generate hydroxyl radicals that have strong oxidation properties to oxidize AVS; AVS could also be removed by bacterial denitrification. As for phosphorus, total phosphorus (TP) content in overlying water remained at 0.1 mg/L after CP and Fe3O4@BC were added. This is due to the conversion of NH4Cl-P and Fe/Al-P into Ca-P in sediments, which inhibited the release of phosphorus. Simultaneously, the release and migration of heavy metal chromium (Cr) were slowed, as demonstrated by the results (the acid extractable and reducible states of Cr in the sediment decreased to 0.58% and 0.97%, respectively). In addition, the results of the high-throughput genetic test showed the total number of microorganisms greatly increased in the CP+Fe3O4@BC group. The abundance of Sulfurovum increased while that of sulphate-reducing bacteria (SRBs) was inhibited. Furthermore, the abundance of denitrifying bacteria (Dechlorominas, Acinetobacter and Flavobacterium) was increased. In brief, our study showed the synergistic effect of Fe3O4@BC composites and CP had a remarkable effect on the urban sediment treatment, which provides a new way to remove sediment pollution.

Evaluating the movement of dissolved porewater species through a marine sediment 51 years after establishment of a pulp and paper effluent stabilization basin

Over 50 years ago, a marine estuary was converted to a wastewater stabilization basin for treatment of primarily pulp and paper effluent. As a result, the basin was immediately converted to a “freshwater” environment and subsequently accumulated a thin layer of black, organic-rich sediment containing varying amounts of dioxins and furans, metals, polycyclic aromatic hydrocarbons, and petroleum hydrocarbons. Previous studies on the site have shown that the majority of this contamination in the basin appears to have been contained within this black sediment layer and not migrated to any significant extent into the original underlying marine sediments. The purpose of this study is to examine sediment porewater chemistry changes that have occurred over 51 years of operation of the stabilization basin with the intent of better understanding why contamination has been minimal into the underlying natural marine sediments. Field and laboratory testing is presented to characterize the physical, chemical, and mineralogical sediments in the basin. Porewater chemistry profiles obtained from this work are then used in combination with a one-dimensional contaminant transport model to examine the role of diffusion, sorption, and upward groundwater flux in the porewater profiles found for the sediments.

The association of cosmetic-related lacrimal sac black deposits with primary-acquired nasolacrimal duct obstruction and dry eye disease.

PURPOSE:To determine the incidence of cosmetic-related lacrimal sac black deposits (LSBDs) in primary-acquired nasolacrimal duct obstruction (PANDO) biopsies and the role of LSBD in the pathogenesis of PANDO, in addition to their association with dry eye disease (DED).METHODS:A clinicopathological study included all patients who underwent surgical management of PANDO. We excluded patients in whom lacrimal sac biopsy was not taken during the surgery. Lacrimal sac tissues were evaluated for the presence of LSBD and related inflammation, with correlation to the demographics, clinical presentation, and pre-operative clinical assessment of dry eye. P <0.05 was considered statistically significant.RESULTS:Of the 177 PANDO specimens, black deposit aggregates were noted in the sac stroma of 61 lacrimal sac specimens (34.5%; 95% confidence interval: 27.5–47.5). LSBDs were significantly more common in females (P < 0.001). The age, residence, past ailments, and laterality were not associated with LSBD. Dry eye was more common with LSBD (P = 0.004). Other presenting symptoms were not significantly associated with LSBD. The stromal black deposits in biopsies were mostly extracellular or in macrophages. The LSBD in only 10 specimens demonstrated birefringence. Energy dispersive spectroscopy determined that carbon and sulfur were the main elements in the black aggregates.CONCLUSION:Cosmetic-related LSBD is unlikely to play a role in the pathogenesis of PANDO. However, they were significantly associated with DED.

The effect of mature plant resistance in sugar beet (Beta vulgaris spp. vulgaris) on survival, fecundity and behaviour of green peach aphids (Myzus persicae).

Several studies have shown the negative effects of mature plant resistance (MPR) on aphids in sugar beet, which is correlated to the formation of black deposits in their stomach. However, the underlying mechanism of MPR still needs to be elucidated, by understanding the toxicity effects of MPR on aphids and the role of the plant phenological stage and the environment. Here, we report that MPR in sugar beet does not only affect Myzus persicae mortality rate and the formation of a black deposit in the aphid stomach, but also aphid fecundity and behaviour. In addition, experiments in climate-controlled and field settings showed quantitative variation in MPR to M. persicae between six genotypes of sugar beet. Our results indicate that environmental effects, such as temperature, play a major role in MPR and underscore the importance of proper climate-controlled experiments for investigating MPR. In climate-controlled experiments, 83.3% of aphids on old leaves developed a black deposit, in contrast to only 16.8% of aphids on young leaves. This shows that not only plant age, but also leaf age plays a major role in the intensity of MPR. Further research will be needed to identify the underlying mechanism, before MPR can be used as a viable and sustainable solution to aphid pests in sugar beet.

Retracted: Memory Effects in Salinity Profiles From Black Sea Sediments

AbstractThe current saline state of the Black Sea is only the latest of a series of freshening‐salinization episodes that have affected that body of water during past glacial–interglacial cycles. Here, we model the salinity history of the basin and its sedimentary porewaters since the end of the penultimate saline period, variously thought to have occurred in the period between ∼128 and ∼65 Kyr BP. Our model results argue that the down‐core salinity profiles of Black Sea Holocene sediments have been affected by the diffusion of salt from the penultimate saline episode. Retrodiction of these porewater profiles also requires that the Black Sea bottom waters be either fresh, or very weakly brackish (S ≤ 1), between ∼50 and ∼10 Kyr BP. In addition, we find that the timing of the first deposition of the well‐known Holocene sapropel corresponds to the time when salty bottom waters first reached the surface waters, and we speculate that increased organic matter production could have been caused by the release of nutrients stored in the saline bottom water. Finally, using current salinity proxy data, we find that the porewater salinity profiles generated from these proxies do not match the observed interstitial profiles.

Black shale-hosted nickel-cobalt deposit: Current understanding and outlook to future prospecting

Black shale-hosted nickel-cobalt deposit: Current understanding and outlook to future prospecting

Black or red phosphorus yields the same blue phosphorus film.

After the discovery of graphene, many other 2D materials have been predicted theoretically and successfully prepared. In this context, single-sheet black phosphorus - phosphorene - is emerging as a viable contender in the field of (2D) semiconductors. Phosphorene offers high carrier mobility and an anisotropic structure that gives rise to a modulation of physical and chemical properties. This opens the way to many novel and fascinating applications related to field-effect transistors and optoelectronic devices. In previous studies, a single layer of blue phosphorene intermixed with Au atoms was grown using purified black phosphorus as a precursor. Starting from the observation that phosphorus vapor mainly consists of P clusters, in this work we aimed at obtaining blue phosphorus using much less expensive purified red phosphorus as an evaporant. By means of microscopy, spectroscopy and diffraction experiments, we show that black or red phosphorus deposition on Au(111) substrates yields the same blue phosphorus film.