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1.
PLoS One ; 15(8): e0237573, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797087

RESUMO

The Late Mesolithic in Southern Europe is dated to the 7th and the first part of the 6th millennia BCE and is marked by profound changes which are mostly evident in the technical know-how and tool-kit of the last hunter-fisher-gatherer societies. The significance of this phase also relates to the fact that it precedes the Early Neolithic, another period of major transformations of human societies. Nonetheless, the Late Mesolithic still remains a poorly known age in this area. A burial discovered at Mondeval de Sora (Northern Italy) in 1987, represents a unique window into this period. In this paper, we provide a detailed analysis of more than 50 lithic and osseous artifacts associated with this burial. We highlight important contextual data regarding the techno-economic dimension and the notion of personal burial possessions. Based on the association and location of some items, we propose a new interpretation of the social status of this individual and the possible impact of technological innovation on the social organization and symbolic sphere of Late Mesolithic groups.


Assuntos
Osso e Ossos/química , Carbonato de Cálcio/análise , Lítio/análise , Magnésio/análise , Arqueologia , Osso e Ossos/anatomia & histologia , Sepultamento , Fósseis/história , História Antiga , Humanos
2.
PLoS One ; 15(7): e0234075, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32678823

RESUMO

Ocean acidification (OA) represents a serious challenge to marine ecosystems. Laboratory studies addressing OA indicate broadly negative effects for marine organisms, particularly those relying on calcification processes. Growing evidence also suggests OA combined with other environmental stressors may be even more deleterious. Scaling these laboratory studies to ecological performance in the field, where environmental heterogeneity may mediate responses, is a critical next step toward understanding OA impacts on natural communities. We leveraged an upwelling-driven pH mosaic along the California Current System to deconstruct the relative influences of pH, ocean temperature, and food availability on seasonal growth, condition and shell thickness of the ecologically dominant intertidal mussel Mytilus californianus. In 2011 and 2012, ecological performance of adult mussels from local and commonly sourced populations was measured at 8 rocky intertidal sites between central Oregon and southern California. Sites coincided with a large-scale network of intertidal pH sensors, allowing comparisons among pH and other environmental stressors. Adult California mussel growth and size varied latitudinally among sites and inter-annually, and mean shell thickness index and shell weight growth were reduced with low pH. Surprisingly, shell length growth and the ratio of tissue to shell weight were enhanced, not diminished as expected, by low pH. In contrast, and as expected, shell weight growth and shell thickness were both diminished by low pH, consistent with the idea that OA exposure can compromise shell-dependent defenses against predators or wave forces. We also found that adult mussel shell weight growth and relative tissue mass were negatively associated with increased pH variability. Including local pH conditions with previously documented influences of ocean temperature, food availability, aerial exposure, and origin site enhanced the explanatory power of models describing observed performance differences. Responses of local mussel populations differed from those of a common source population suggesting mussel performance partially depended on genetic or persistent phenotypic differences. In light of prior research showing deleterious effects of low pH on larval mussels, our results suggest a life history transition leading to greater resilience in at least some performance metrics to ocean acidification by adult California mussels. Our data also demonstrate "hot" (more extreme) and "cold" (less extreme) spots in both mussel responses and environmental conditions, a pattern that may enable mitigation approaches in response to future changes in climate.


Assuntos
Carbonatos/metabolismo , Mudança Climática , Mytilus/crescimento & desenvolvimento , Oceanos e Mares , Água do Mar/química , Adaptação Fisiológica , Exoesqueleto/química , Animais , Oceano Atlântico , Carbonato de Cálcio/análise , Ecossistema , Concentração de Íons de Hidrogênio , Mytilus/metabolismo , Nutrientes , Tamanho do Órgão , Fitoplâncton , Temperatura , Ondas de Maré
3.
Nature ; 582(7812): 379-383, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32555488

RESUMO

The ongoing uptake of anthropogenic carbon by the ocean leads to ocean acidification, a process that results in a reduction in pH and in the saturation state of biogenic calcium carbonate minerals aragonite (Ωarag) and calcite (Ωcalc)1,2. Because of its naturally low Ωarag and Ωcalc (refs. 2,3), the Arctic Ocean is considered the region most susceptible to future acidification and associated ecosystem impacts4-7. However, the magnitude of projected twenty-first century acidification differs strongly across Earth system models8. Here we identify an emergent multi-model relationship between the simulated present-day density of Arctic Ocean surface waters, used as a proxy for Arctic deep-water formation, and projections of the anthropogenic carbon inventory and coincident acidification. By applying observations of sea surface density, we constrain the end of twenty-first century Arctic Ocean anthropogenic carbon inventory to 9.0 ± 1.6 petagrams of carbon and the basin-averaged Ωarag and Ωcalc to 0.76 ± 0.06 and 1.19 ± 0.09, respectively, under the high-emissions Representative Concentration Pathway 8.5 climate scenario. Our results indicate greater regional anthropogenic carbon storage and ocean acidification than previously projected3,8 and increase the probability that large parts of the mesopelagic Arctic Ocean will be undersaturated with respect to calcite by the end of the century. This increased rate of Arctic Ocean acidification, combined with rapidly changing physical and biogeochemical Arctic conditions9-11, is likely to exacerbate the impact of climate change on vulnerable Arctic marine ecosystems.


Assuntos
Carbono/análise , Oceanos e Mares , Água do Mar/química , Animais , Organismos Aquáticos , Regiões Árticas , Carbonato de Cálcio/análise , Carbono/química , Dióxido de Carbono/análise , Ecossistema , História do Século XXI , Atividades Humanas , Concentração de Íons de Hidrogênio
4.
Nature ; 583(7816): 406-410, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32555457

RESUMO

Calcified eggshells protect developing embryos against environmental stress and contribute to reproductive success1. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite, and an outermost waxy cuticle2-7. The calcitic eggshell consists of one or more ultrastructural layers that differ markedly among the three major dinosaur clades, as do the configurations of respiratory pores. So far, only hadrosaurid, a few sauropodomorph and tetanuran eggshells have been discovered; the paucity of the fossil record and the lack of intermediate eggshell types challenge efforts to homologize eggshell structures across all dinosaurs8-18. Here we present mineralogical, organochemical and ultrastructural evidence for an originally non-biomineralized, soft-shelled nature of exceptionally preserved ornithischian Protoceratops and basal sauropodomorph Mussaurus eggs. Statistical evaluation of in situ Raman spectra obtained for a representative set of hard- and soft-shelled, fossil and extant diapsid eggshells clusters the originally organic but secondarily phosphatized Protoceratops and the organic Mussaurus eggshells with soft, non-biomineralized eggshells. Histology corroborates the organic composition of these soft-shelled dinosaur eggs, revealing a stratified arrangement resembling turtle soft eggshell. Through an ancestral-state reconstruction of composition and ultrastructure, we compare eggshells from Protoceratops and Mussaurus with those from other diapsids, revealing that the first dinosaur egg was soft-shelled. The calcified, hard-shelled dinosaur egg evolved independently at least three times throughout the Mesozoic era, explaining the bias towards eggshells of derived dinosaurs in the fossil record.


Assuntos
Dinossauros , Casca de Ovo/anatomia & histologia , Casca de Ovo/química , Fósseis , Dureza , Animais , Evolução Biológica , Biomineralização , Carbonato de Cálcio/análise , Carbonato de Cálcio/química
5.
Environ Sci Pollut Res Int ; 27(20): 25794-25800, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32356060

RESUMO

Pelagic Sargassum is considered an ecological plague that is causing adverse economic impacts to the tourist and fishing industries in the Caribbean. However, its proliferation might be playing an important role to reduce global warming, as it removes a high content of CO2 from the atmosphere and transforms it into calcium carbonate, in its calcite phase, producing sediment after it dies. We quantified the amount of calcite in Sargassum samples collected from the Mexican Caribbean coast in 2019. Samples were divided into three parts: vesicles, thallus, and leaves. In each part, the amount of carbon, oxygen, and calcium was determined by means of X-ray energy dispersion to confirm the existence of a calcite crystalline phase. Imaging methodologies and IR spectroscopy complemented the structural studies. The thermogravimetric analysis determined that approximately 5% of the CO2 captured by the Sargassum was converted into calcite. Thus, by extrapolation, the Atlantic Sargasso Belt retained approximately 19.3 million tons of CO2 from 2011 to 2019.


Assuntos
Sargassum , Carbonato de Cálcio/análise , Dióxido de Carbono/análise , Região do Caribe , México
6.
Mar Pollut Bull ; 150: 110695, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31740181

RESUMO

The aragonite saturation state (Ωarag) was determined to assess its seasonal variations and the major controlling factors in the southeastern Yellow Sea (YS) over four seasons. Ωarag showed large seasonal variation in the surface waters, with dissolved inorganic carbon (DIC) as a major factor controlling the seasonal variation. In the bottom waters, Ωarag exhibited only small seasonal variation compared with the surface waters; DIC and total alkalinity were the main factors contributing to the variation. The bottom water of the southeastern YS was undersaturated with aragonite during the fall, even though the southeastern YS was not typically associated with upwelling, freshwater discharge, or eutrophication processes. Aragonite undersaturation was most likely due to ocean dumping of organic materials. Therefore, ocean pumping should be prohibited in shallow marginal seas to prevent aragonite undersaturation.


Assuntos
Carbonato de Cálcio/análise , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Oceanos e Mares , Estações do Ano , Água do Mar/química
7.
Environ Pollut ; 259: 113765, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31884208

RESUMO

We utilized volcanic CO2 vents at Castello Aragonese off Ischia Island as a natural laboratory to investigate the effect of lowered pH/elevated CO2 on the bioactivities of extracts from fleshy brown algae Sargassum vulgare C. Agardh. We analysed the carbohydrate levels, antioxidant capacity, antibacterial, antifungal, antiprotozoal, anticancer properties and antimutagenic potential of the algae growing at the acidified site (pH âˆ¼ 6.7) and those of algae growing at the nearby control site Lacco Ameno (pH∼8.1). The results of the present study show that the levels of polysaccharides fucoidan and alginate were higher in the algal population at acidified site. In general, extracts for the algal population from the acidified site showed a higher antioxidant capacity, antilipidperoxidation, antibacterial, antifungal, antiprotozoal, anticancer activities and antimutagenic potential compared to the control population. The increased bioactivity in acidified population could be due to elevated levels of bioactive compounds of algae and/or associated microbial communities. In this snapshot study, we performed bioactivity assays but did not characterize the chemistry and source of presumptive bioactive compounds. Nevertheless, the observed improvement in the medicinal properties of S. vulgare in the acidified oceans provides a promising basis for future marine drug discovery.


Assuntos
Ácidos/análise , Carbonato de Cálcio/análise , Oceanos e Mares , Sargassum/fisiologia , Água do Mar/química , Animais , Dióxido de Carbono/farmacologia , Concentração de Íons de Hidrogênio , Invertebrados/fisiologia , Ilhas , Alga Marinha , Erupções Vulcânicas
8.
Appl Spectrosc ; 73(12): 1388-1393, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31617367

RESUMO

We present the accurate terahertz spectra of between imitation and cultured pearls using continuous-wave terahertz (CW-THz) spectroscopy. Using Fourier transform infrared (FT-IR) spectroscopy and optical coherence tomography (OCT) measurements, cultured pearls can be distinguished from imitation pearls by observing distinct absorption peaks and discriminative boundaries. The THz absorption spectra up to 0.3 THz obtained from CW-THz spectroscopy show several absorption peaks at specific frequencies with the cultured pearls but no peaks with the imitation pearls, which results from the existence of the nacre polymorph of cultured pearls. Hence, it is expected that the CW-THz system proposed herein will be applicable to fast, nondestructive spectrum analysis including pearl identification.


Assuntos
Carbonato de Cálcio/análise , Plásticos/análise , Espectroscopia Terahertz/métodos , Animais , Pinctada/metabolismo
9.
Environ Pollut ; 255(Pt 1): 113124, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31622956

RESUMO

The transport and retention behavior of polymer- (PVP-AgNP) and surfactant-stabilized (AgPURE) silver nanoparticles in carbonate-dominated saturated and unconsolidated porous media was studied at the laboratory scale. Initial column experiments were conducted to investigate the influence of chemical heterogeneity (CH) and nano-scale surface roughness (NR) arising from mixtures of clean, positively charged calcium carbonate sand (CCS), and negatively charged quartz sands. Additional column experiments were performed to elucidate the impact of CH and NR arising from the presence and absence of soil organic matter (SOM) on a natural carbonate-dominated aquifer material. The role of the nanoparticle capping agent was examined under all conditions tested in the column experiments. Nanoparticle transport was well described using a numerical model that facilitated blocking on one or two retention sites. Results demonstrate that an increase in CCS content in the artificially mixed porous medium leads to delayed breakthrough of the AgNPs, although AgPURE was much less affected by the CCS content than PVP-AgNPs. Interestingly, only a small portion of the solid surface area contributed to AgNP retention, even on positively charged CCS, due to the presence of NR which weakened the adhesive interaction. The presence of SOM enhanced the retention of AgPURE on the natural carbonate-dominated aquifer material, which can be a result of hydrophobic or hydrophilic interactions or due to cation bridging. Surprisingly, SOM had no significant impact on PVP-AgNP retention, which suggests that a reduction in electrostatic repulsion due to the presence of SOM outweighs the relative importance of other binding mechanisms. Our findings are important for future studies related to AgNP transport in shallow unconsolidated calcareous and siliceous sands.


Assuntos
Carbonato de Cálcio/análise , Nanopartículas Metálicas/análise , Compostos Orgânicos/química , Prata/análise , Solo/química , Água Subterrânea/química , Interações Hidrofóbicas e Hidrofílicas , Polímeros/química , Porosidade , Quartzo/química , Solo/classificação , Tensoativos
10.
Environ Monit Assess ; 191(11): 655, 2019 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-31630261

RESUMO

Mining activities are important for the country's economy, but they cause serious threats to the environment. The geology of SW Turkey comprises Southern (Çine) Submassif of Menderes Metamorphic Massif and the Lycian Nappes. These geological units are unconformably overlain by lignite-bearing Miocene deposits, Upper Miocene-Pliocene conglomerates and Quaternary alluvial deposits. The aim of this study is to determine the geospatial change of mining activities in the Mugla-Aydin provinces, SW Turkey. For this purpose, Landsat-5 TM, Landsat-7 ETM, Landsat-8 OLI and Google Earth satellite image data for 1984, 1994, 2004, 2014 and 2018 have been used for change detection analysis. In 1984, only a Miocene lignite quarry was excavated. Then, in 1994, operations for the excavation of feldspar-quartz and marble quarries were started, and from 2004 to 2014, mining activities significantly accelerated. An aerial image of 2018 shows that an area of about 3800 ha has been exploited by mining at 149 quarries. Considering access roads to quarries, plants and dam reservoirs, the human impact extends over 3800 ha. The study area is home to several archaeological sites and endemic biota. Thus, there is an urgent need for the relocation and protection of archaeological heritages and endemic biota by creating special zones. Additionally, the rich geomorphologic features in the study area that require millions of years to form are at risk of totally disappearing.


Assuntos
Conservação dos Recursos Naturais/métodos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Mineração , Imagens de Satélites , Carbonato de Cálcio/análise , Carvão Mineral/análise , Atividades Humanas , Turquia
11.
Environ Monit Assess ; 191(9): 564, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31414237

RESUMO

The objective of this study was to determine eco-edaphic characteristics and influence of different substrates on mineral characteristics of facultative serpentinophyte. The total concentration of 20 elements Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Se, and Zn in soil samples and aboveground parts of medicinal plant species Teucrium montanum from various calcareous and serpentinite habitats in the territory of Serbia was determined. The concentration of the elements was established by inductively coupled plasma optical emission spectrometry-ICP-OES. The obtained results showed that the quantities of certain elements Al, As, B, Ca, Cd, Cu, K, Li, P, Se, and Zn were detected more in the soil samples from calcareous habitats in comparison to the quantities of other metals Co, Cr, Fe, Mg, Mn, Na, Ni, which were more frequently found in the soil samples from the serpentinite habitats. Analyzed plant samples from calcareous habitats contained higher concentrations of Al, Ca, Li, and Zn as opposed to serpentinite containing higher concentrations of Co, Cr, Fe, Mg, Mn, Na, Ni, and Se. Examined species can accumulate macro- and microelements in different quantities, depending on the substrate type. Differences in the concentration of certain elements in the soil samples and aboveground parts of the T. montanum from calcareous and serpentinite habitats indicate significant phenotypic plasticity of the investigated species as well as the existence of specific serpentinite ecotypes developed by the activity of various edaphic factors.


Assuntos
Asbestos Serpentinas/análise , Carbonato de Cálcio/análise , Solo/química , Teucrium/metabolismo , Ecossistema , Monitoramento Ambiental/métodos , Íons , Metais/análise , Minerais/análise , Sérvia
12.
Nat Commun ; 10(1): 3580, 2019 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395889

RESUMO

Ocean acidification is expected to negatively impact calcifying organisms, yet we lack understanding of their acclimation potential in the natural environment. Here we measured geochemical proxies (δ11B and B/Ca) in Porites astreoides corals that have been growing for their entire life under low aragonite saturation (Ωsw: 0.77-1.85). This allowed us to assess the ability of these corals to manipulate the chemical conditions at the site of calcification (Ωcf), and hence their potential to acclimate to changing Ωsw. We show that lifelong exposure to low Ωsw did not enable the corals to acclimate and reach similar Ωcf as corals grown under ambient conditions. The lower Ωcf at the site of calcification can explain a large proportion of the decreasing P. astreoides calcification rates at low Ωsw. The naturally elevated seawater dissolved inorganic carbon concentration at this study site shed light on how different carbonate chemistry parameters affect calcification conditions in corals.


Assuntos
Aclimatação , Antozoários/fisiologia , Calcificação Fisiológica , Carbonato de Cálcio/metabolismo , Fontes Hidrotermais/química , Animais , Antozoários/química , Carbonato de Cálcio/análise , Carbonato de Cálcio/química , Geografia , Concentração de Íons de Hidrogênio , Isótopos , México , Água do Mar/química
13.
Environ Monit Assess ; 191(9): 552, 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31399843

RESUMO

The present work aims to observe the spatial distribution of metals associated with carbon forms (fraction < 2 mm) in surface sediments of two macrotidal estuaries, São Marcos Bay and Anil River Estuary, which are located within the transition region between the Amazonian and the semi-arid northeast regions. Grain size, metal content (Al, Fe, Mn, Cu, Pb, Cr, Zn, and Ni), organic matter, and calcium carbonate content were determined. Grain size analyses showed the predominance of the sand-sized fraction < 2 mm due to the local hydrodynamic conditions. Anil River Estuary sediments exhibited high organic matter content due to both the mangrove outwelling and domestic sewage discharge. They also presented high calcium carbonate content as a result of abundant remnants of gastropod shells. Organic matter acted as the primary geochemical carrier for most metals in both estuaries, while calcium carbonate acted as the secondary carrier. Enrichment factors indicated Mn sediment contamination in São Marcos Bay and Fe, Pb, and Zn contamination in the Anil River Estuary. These results also suggest that São Marcos Bay is influenced by harbor activities, mostly ore shipment, whereas Anil River Estuary sediments are enriched in these metals as a result of domestic and hospital effluents reaching the urbanized drainage basin.


Assuntos
Carbono/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Rios/química , Poluentes Químicos da Água/análise , Brasil , Carbonato de Cálcio/análise , Carbonatos/análise , Estuários
14.
Environ Geochem Health ; 41(6): 2631-2648, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31076980

RESUMO

Understanding the changes in chemical composition of soil plays an important role in effective control of irrigation and fertilization in agricultural productions, which further protects the groundwater quality and predicts its evolution. Field trials were conducted from 2014 to 2016 to investigate the impacts of irrigation and fertilization on mineral composition transformation in the soil profile. Based on HYDRUS-HP1 and Visual MINTEQ, this paper simulated and computed the migration and transformation of chemical components during the irrigation and fertilization in the vadose zone soil of Jinghuiqu district. The results showed that when the nitrogen fertilizer entered the soil, the urea was hydrolyzed to NH4+ and it was nitrified as NO2-, which caused pH value to drop around the first 4 days after irrigation, and rise slightly on the 12th day. Due to the fact that soil belongs to calcareous soil, concentration of CaCO3 and other carbonates (Mg or Na in sodic soils) could buffer the soil pH well above 8.5. Thus, on the 30th day of the post-irrigation the pH reached the same level as it was before irrigation. The change in pH resulted in the main ions reacting, dissolving and precipitating simultaneously in the soil profile. The concentrations of Ca2+, Mg2+ and HCO3- had significant correlations with the increasing ammonia nitrogen hydrolyzed from urea, and this process is accompanied with the saturation index of minerals and the main ion content changing. At the same time, the varying temperature action on pH of the soil was higher in summer than that in winter. Thus, the irrigation, fertilization and temperature had affected pH and main chemical components in the soil.


Assuntos
Irrigação Agrícola , Fertilizantes , Solo/química , Irrigação Agrícola/métodos , Agricultura/métodos , Cálcio/análise , Carbonato de Cálcio/análise , Monitoramento Ambiental , Fertilizantes/análise , Concentração de Íons de Hidrogênio , Hidrólise , Magnésio/análise , Nitrogênio/análise , Nitrogênio/metabolismo , Estações do Ano , Ureia/química
15.
Geobiology ; 17(5): 510-522, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31002215

RESUMO

Calcified microbial microfossils-often interpreted as cyanobacteria-were important components of Precambrian and Paleozoic limestones, but their paucity in modern marine environments complicates our ability to make conclusive interpretations about their taxonomic affinity and geologic significance. Freshwater spring-associated limestones (e.g., travertine and tufa) serve as terrestrial analogs to investigate mineralization in and around aquatic biofilms on observable timescales. We document the diagenesis of calcite fabrics associated with the freshwater algae Oocardium stratum, an epiphytic colonial green algae (desmid) known for producing stalks of extracellular polymeric substances (EPS) and passively producing a bifurcating tubular calcite monocrystal. Bifurcating EPS stalks produced by Oocardium colonies can become calcified and preserved in ancient carbonate deposits. Calcified micritic EPS stalks have a filamentous morphology, show evidence of branching, and maintain uniformity in diameter thickness throughout the mm-scale colony, much like the enigmatic calcimicrobe Epiphyton. We provide a mechanism by which calcification associated with a colonial semispherical micro-organism produces microfossils that deceptively resemble filamentous forms. These findings have implications for the use of morphological traits when assigning taxonomic affinities to extinct microfossil groups and highlight the utility of calcifying freshwater modern environments to investigate microbial taphonomy.


Assuntos
Carbonato de Cálcio/análise , Desmidiales/anatomia & histologia , Fósseis/anatomia & histologia , Carbonato de Cálcio/química , Cianobactérias/classificação , Cianobactérias/citologia , Desmidiales/classificação , Água Doce , Sedimentos Geológicos/química
16.
Chemosphere ; 225: 517-523, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30897475

RESUMO

The work is focusing on air pollution impacts on historical limestone buildings located in urban areas in Morocco. Black crusts sampled on the façades of two ancient limestone monuments, dating back to the 12th and 20th centuries edified in the cities of Salé and Casablanca, have been analyzed by means of ATR-FTIR and synchronous fluorescence spectroscopies. Infrared analyses revealed degradation products, mainly gypsum due to calcite sulphation under wetness and SO2 rich oil fired soot, and oxalates due to ancient biological weathering. Synchronous fluorescence permitted the identification of the most hazardous PAHs along with other non-identified fluorescent organics; this technique appeared efficient and suitable for the analysis of fluorescent pollutants entrapped in black crusts. Such results keeping track of air pollution causing disfigurement of architectural heritage must alarm both cultural heritage and environmental decision makers.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Arquitetura , Carbonato de Cálcio/metabolismo , Sulfato de Cálcio/análise , Monitoramento Ambiental/métodos , Carbonato de Cálcio/análise , Cidades , Materiais de Construção , Marrocos , Fuligem , Espectroscopia de Infravermelho com Transformada de Fourier , Tempo (Meteorologia)
17.
J Fish Biol ; 94(5): 810-814, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30847918

RESUMO

In this study we quantified the percent CaCO3 polymorph composition in otoliths of larval and juvenile Lake Sturgeon Acipenser fulvescens via X-ray microdiffraction. Sagittal otoliths of sub-adults were primarily composed of aragonite (> 90%) while the lapilli otoliths were 100% vaterite. This is the first time the presence of aragonite in otoliths has been reported in an acipenseriform and is surprising given that the ability to form aragonite otoliths was not thought to have evolved until the separation of teleost and holostean species from other Actinopterygian fishes (e.g., sturgeon, paddlefish, gar).


Assuntos
Carbonato de Cálcio/análise , Peixes/anatomia & histologia , Membrana dos Otólitos/química , Animais , Evolução Biológica , Peixes/crescimento & desenvolvimento , Peixes/metabolismo , Lagos , Larva , Membrana dos Otólitos/anatomia & histologia
18.
Sci Rep ; 9(1): 1003, 2019 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-30700797

RESUMO

Isolated spherical carbonate concretions are frequently observed in finer grained marine sediments of widely varying geological age. Recent studies on various kinds of spherical carbonate (CaCO3) concretions revealed that they formed very rapidly under tightly constrained conditions. However, the formation ages of the isolated spherical carbonate concretions have never been determined. Here we use 87Sr/86Sr ratios to determine the ages of these spherical concretions. The studied concretions formed in the Yatsuo Group of Miocene age in central Japan. Some formed post-mortem around tusk-shells (Fissidentalium spp.), while other concretions have no shell fossils inside. The deformation of sedimentary layers around the concretions, combined with geochemical analyses, reveal that Sr was incorporated into the CaCO3 concretions during their rapid formation. Strontium isotopic stratigraphy using 87Sr/86Sr ratios of all concretions indicates an age of 17.02 ± 0.27 Ma, with higher accuracy than the ages estimated using micro-fossils from the Yatsuo Group. The results imply that the 87Sr/86Sr ratio of isolated spherical carbonate concretions can be applied generally to determine the numerical ages of marine sediments, when concretions formed soon after sedimentation. The 87Sr/86Sr age determinations have high accuracy, even in cases without any fossils evidence.


Assuntos
Carbonato de Cálcio/análise , Fósseis/história , Sedimentos Geológicos/química , Geologia , Moluscos/química , Isótopos de Estrôncio/análise , Animais , História Antiga , Japão
19.
Artigo em Inglês | MEDLINE | ID: mdl-30763147

RESUMO

Calcium carbonate (E170) is a common food and pharmaceutical additive/ingredient. In addition to a source of calcium, the carbonate has uses including as a colour, acidity regulator and bulking agent. Globally, a range of regulatory agencies and pharmacopoeia control the analyses and specification of additives in food, supplements, pharmaceutical substances and excipients. Accordingly, a range of specifications and analyses exist for calcium carbonate depending on the application and market of the product. In this contribution, we analyse calcium carbonates from geological, synthetic and biogenic sources, focussing on acid insoluble impurities, a test required by current monographs. Analysis of calcium carbonate from different origins may require modification of existing tests to comply with regulatory bodies, due to the variation of impurities specific to the source of the material. We suggest an analytical approach involving centrifugation that improves analytical efficiency (up to 85% time reduction), especially for calcium carbonate of biological origin.


Assuntos
Carbonato de Cálcio/análise , Aditivos Alimentares/análise , Centrifugação , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
20.
Extremophiles ; 23(2): 201-218, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30617527

RESUMO

The Khor Al-Adaid sabkha in Qatar is among the rare extreme environments on Earth where it is possible to study the formation of dolomite-a carbonate mineral whose origin remains unclear and has been hypothetically linked to microbial activity. By combining geochemical measurements with microbiological analysis, we have investigated the microbial mats colonizing the intertidal areas of sabhka. The main aim of this study was to identify communities and conditions that are favorable for dolomite formation. We inspected and sampled two locations. The first site was colonized by microbial mats that graded vertically from photo-oxic to anoxic conditions and were dominated by cyanobacteria. The second site, with higher salinity, had mats with an uppermost photo-oxic layer dominated by filamentous anoxygenic photosynthetic bacteria (FAPB), which potentially act as a protective layer against salinity for cyanobacterial species within the deeper layers. Porewater in the uppermost layers of the both investigated microbial mats was supersaturated with respect to dolomite. Corresponding to the variation of the microbial community's vertical structure, a difference in crystallinity and morphology of dolomitic phases was observed: dumbbell-shaped proto-dolomite in the mats dominated by cyanobacteria and rhombohedral ordered-dolomite in the mat dominated by FAPB.


Assuntos
Sedimentos Geológicos/microbiologia , Microbiota , Tolerância ao Sal , Carbonato de Cálcio/análise , Cianobactérias/genética , Cianobactérias/metabolismo , Ambientes Extremos , Sedimentos Geológicos/química , Magnésio/análise , Catar , Salinidade
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