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1.
Nat Commun ; 12(1): 5032, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413314

RESUMO

Methane, along with other short-chain alkanes from some Archean metasedimentary rocks, has unique isotopic signatures that possibly reflect the generation of atmospheric greenhouse gas on early Earth. We find that alkane gases from the Kidd Creek mines in the Canadian Shield are microbial products in a Neoarchean ecosystem. The widely varied hydrogen and relatively uniform carbon isotopic compositions in the alkanes infer that the alkanes result from the biodegradation of sediment organic matter with serpentinization-derived hydrogen gas. This proposed process is supported by published geochemical data on the Kidd Creek gas, including the distribution of alkane abundances, stable isotope variations in alkanes, and CH2D2 signatures in methane. The recognition of Archean microbial methane in this work reveals a biochemical process of greenhouse gas generation before the Great Oxidation Event and improves the understanding of the carbon and hydrogen geochemical cycles.


Assuntos
Bactérias/metabolismo , Planeta Terra , Gases/química , Sedimentos Geológicos/química , Hidrogênio/química , Hidrogênio/metabolismo , Metano/metabolismo , Fenômenos Microbiológicos , Alcanos/química , Alcanos/metabolismo , Biodegradação Ambiental , Canadá , Isótopos de Carbono/química , Ecossistema , Metano/química , Oxirredução
2.
Nat Commun ; 12(1): 4403, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34285238

RESUMO

Sulfur cycling is ubiquitous in sedimentary environments, where it mediates organic carbon remineralization, impacting both local and global redox budgets, and leaving an imprint in pyrite sulfur isotope ratios (δ34Spyr). It is unclear to what extent stratigraphic δ34Spyr variations reflect local aspects of the depositional environment or microbial activity versus global sulfur-cycle variations. Here, we couple carbon-nitrogen-sulfur concentrations and stable isotopes to identify clear influences on δ34Spyr of local environmental changes along the Peru margin. Stratigraphically coherent glacial-interglacial δ34Spyr fluctuations (>30‰) were mediated by Oxygen Minimum Zone intensification/expansion and local enhancement of organic matter deposition. The higher resulting microbial sulfate reduction rates led to more effective drawdown and 34S-enrichment of residual porewater sulfate and sulfide produced from it, some of which is preserved in pyrite. We identify organic carbon loading as a major influence on δ34Spyr, adding to the growing body of evidence highlighting the local controls on these records.


Assuntos
Bactérias Anaeróbias/metabolismo , Sedimentos Geológicos/microbiologia , Ferro/metabolismo , Oxigênio/metabolismo , Sulfetos/metabolismo , Enxofre/metabolismo , Carbono/metabolismo , Ciclo do Carbono , Geografia , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Ferro/química , Oxirredução , Peru , Sulfetos/química , Isótopos de Enxofre/análise
3.
Arch Microbiol ; 203(7): 4259-4272, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34100100

RESUMO

Polycyclic aromatic hydrocarbons (PAHs), originating from anthropogenic and natural sources, are highly concerned environmental pollutants. This study investigated the impact of two model PAHs (pyrene and phenanthrene) on bacterial community succession in the seagrass meadows sediment in a lab-scale microcosm. Halophila ovalis sediment slurry microcosms were established, one group was placed as a control, and the other two were treated with pyrene and phenanthrene. Bacterial community succession in response to respective PAHs was investigated by 16S rRNA amplicon sequencing. The results demonstrated that bacterial diversity decrease in each microcosm during the incubation process; however, the composition of bacterial communities in each microcosm was significantly different. Proteobacteria (37-89%), Firmicutes (9-41%), and Bacteroides (7-21%) were the predominant group at the phylum levels. Their abundance varies during the incubation process. Several previously reported hydrocarbon-degrading genera, such as Pseudomonas, Spinghobium, Sphingobacterium, Mycobacterium, Pseudoxanthomonas, Idiomarina, Stenotrophomonas, were detected in higher abundance in pyrene- and phenanthrene-treated microcosms. However, these genera were distinctly distributed in the pyrene and phenanthrene treatments, suggesting that certain bacterial groups favorably degrade different PAHs. Statistical analyses, such as ANOSIM and PERMANOVA, also revealed that significant differences existed among the treatments' bacterial consortia (P < 0.05). This work showed that polycyclic aromatic hydrocarbon significantly affects bacterial community succession, and different PAHs might influence the bacterial community succession differently.


Assuntos
Bactérias , Sedimentos Geológicos , Microbiota , Fenantrenos , Pirenos , Bactérias/efeitos dos fármacos , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Microbiota/efeitos dos fármacos , Fenantrenos/farmacologia , Pirenos/farmacologia , RNA Ribossômico 16S/genética
4.
Ecotoxicol Environ Saf ; 220: 112354, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34116335

RESUMO

Hydropower generation, a renewable source of electricity, has been linked to elevated methylmercury (MeHg) concentrations in impoundments and aquatic biota. This study investigates the impact of water level fluctuations (WLF) on MeHg concentrations in water, sediment, and fish. Using a set of controlled microcosm experiments emulating the drawdown/refill dynamics and subsequent sediment exposure to air experienced in reservoirs, we demonstrate that less frequent WLFs, and/or increased exposure of sediment to air, can lead to elevated MeHg concentrations in sediment, and total mercury (THg) and MeHg concentrations in water. In examining the effects of WLF frequency (two-day, weekly, and monthly), the monthly treatment displayed the highest THg and MeHg water levels, while the weekly treatment was characterized by the highest MeHg levels in the sediment. Our work supports emerging evidence that longer duration between WLF creates a larger surface area of sediment exposed to air leading to conditions conducive to higher MeHg concentrations in sediments and water. In contrast, THg, MeHg, and fatty acid trends in fish were largely inconclusive characterized by similar among-treatment effects and minimal temporal variability over the course of our experiment. This result could partly be attributed to overall low mercury levels and simple "worm-forage fish" food web in our experiment. To elucidate the broader impacts of water fluctuations on aquatic chemistry and biota, other factors (e.g., longer WLF cycles, dissolved organic matter, temperature, more complex food webs) which modulate both methylation rates and food web dynamics must be considered.


Assuntos
Mercúrio/análise , Movimentos da Água , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , Peixes/metabolismo , Cadeia Alimentar , Sedimentos Geológicos/química , Compostos de Metilmercúrio/análise , Água/química
5.
Nat Commun ; 12(1): 3037, 2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-34031392

RESUMO

Microbialites accrete where environmental conditions and microbial metabolisms promote lithification, commonly through carbonate cementation. On Little Ambergris Cay, Turks and Caicos Islands, microbial mats occur widely in peritidal environments above ooid sand but do not become lithified or preserved. Sediment cores and porewater geochemistry indicated that aerobic respiration and sulfide oxidation inhibit lithification and dissolve calcium carbonate sand despite widespread aragonite precipitation from platform surface waters. Here, we report that in tidally pumped environments, microbial metabolisms can negate the effects of taphonomically-favorable seawater chemistry on carbonate mineral saturation and microbialite development.


Assuntos
Compostos de Cálcio/química , Ecossistema , Óxidos/química , Areia/química , Areia/microbiologia , Carbonato de Cálcio/metabolismo , Carbonatos , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Microbiota , Minerais , Água do Mar/química , Água do Mar/microbiologia , Índias Ocidentais
6.
Ecotoxicol Environ Saf ; 220: 112360, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34058680

RESUMO

Recently, emerging pollutants, such as anthelmintics have attracted an increasing attention worldwide due to their extensive use and notable stability. However, the information on anthelmintics in the environment of southwest China is scarce. Thus, the occurrence, ecological risk and exposure evaluation of nineteen anthelmintics in Tuojiang River, which is one of the largest tributaries of Yangtze River, and drinking water source of Sichuan, southwest China, were investigated. The result showed that the detection frequency of anthelmintics was relatively high in Tuojiang River, ranging from 65% to 100% in river water. Among the seven kinds of anthelmintics, benzimidazoles are the primary anthelmintics, with concentrations up to 61.12 ng/L and 596.06 ng/g in water and sediment of the Tuojiang river, respectively. The total concentration of 19 anthelmintics in sediment samples from non-agricultural area was higher than that in agricultural area(p = 0.000 < 0.05). This could be attributed to anthropogenic activities, which lead to greater discharge and accumulation of anthelmintics in residential area along the river. It's worth to mention that the highest total concentrations of anthelmintics (109.28 ng/L) was found at the junction of rivers in R31 site. The results could be ascribed to the complexity of junction of Tuojiang River and Yangtze River, which could influence the distribution of pollutant. Besides, the ecological risk assessment showed that the macrocyclic lactones rather than benzimidazoles had relatively high toxicity to non-target organisms in aquatic environment (p = 0.000 < 0.05), with the highest RQEcotox value of 101 for Daphnia magna, while benzimidazoles had relatively high concentrations. The exposure risk could be ignored for both children and adults because the daily intake of anthelmintics via water ingestion were below 10 ng/kg/d. In addition, strong correlations were found between sucralose and most of the selected anthelmintics in Tuojiang River, indicating that sucralose might be a good tracer to evaluated the source of anthelmintics in surface water. This study provides the levels, risks and even some tracer information of pollutants for better understanding of anthelmintics in southwest China.


Assuntos
Anti-Helmínticos/análise , Exposição Ambiental/análise , Rios/química , Poluentes Químicos da Água/análise , Adulto , Animais , Anti-Helmínticos/toxicidade , Organismos Aquáticos/efeitos dos fármacos , Criança , China , Daphnia/efeitos dos fármacos , Sedimentos Geológicos/química , Humanos , Medição de Risco , Sacarose/análogos & derivados , Sacarose/análise , Poluentes Químicos da Água/toxicidade
7.
Aquat Toxicol ; 236: 105862, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34049114

RESUMO

Over the last 60 years, valuable progress was made in the standardization of environmental monitoring with model zooplankton. However, obligate dormancy in zooplankton life cycles is not yet considered in standardized toxicology methods. Most zooplankton from coastal and inland waters use dormancy as a critical ecological strategy, and exposure to toxicants during dormancy or resurrection from dormancy alters developmental patterning and hatching success. The present study accounts for this by using both standardized and novel toxicology assays to assess the impacts of coal ash contaminated sediments and water on development, hatching, and survivorship of model zooplankton. The results demonstrate that standardized assays with rotifer and cladoceran models detect no toxicity in surface water and sediment pore water from Lake Sutton, North Carolina, USA. By contrast, novel toxicity assays with cladoceran and anostracan models demonstrate that development and larval survivorship are negatively impacted by Lake Sutton water and sediment. Embryos of Artemia franciscana display developmental patterning and hatching aberrations that match those observed in previous studies with metals when hatched in filtered surface water or pore water after a period of anoxia-induced dormancy. Larval survivorship in Daphnia magna and A. franciscana also decreases when post-diapause embryos are hatched in the presence of sediment. The effects of whole sediment on larval survivorship are not explained by coal ash impacts on water pH. These data provide an explanation for the missing egg bank and historic community restructure in Lake Sutton. The data also demonstrate a need for standardized assays that include dormant life stages.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água/toxicidade , Zooplâncton/fisiologia , Animais , Artemia , Daphnia/efeitos dos fármacos , Sedimentos Geológicos/química , Lagos/química , Larva , Estágios do Ciclo de Vida , Metais/toxicidade , Rotíferos , Zooplâncton/efeitos dos fármacos
8.
Nat Commun ; 12(1): 2816, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33990580

RESUMO

The organic carbon produced in the ocean's surface by phytoplankton is either passed through the food web or exported to the ocean interior as marine snow. The rate and efficiency of such vertical export strongly depend on the size, structure and shape of individual particles, but apart from size, other morphological properties are still not quantitatively monitored. With the growing number of in situ imaging technologies, there is now a great possibility to analyze the morphology of individual marine snow. Thus, automated methods for their classification are urgently needed. Consequently, here we present a simple, objective categorization method of marine snow into a few ecologically meaningful functional morphotypes using field data from successive phases of the Arctic phytoplankton bloom. The proposed approach is a promising tool for future studies aiming to integrate the diversity, composition and morphology of marine snow into our understanding of the biological carbon pump.


Assuntos
Sedimentos Geológicos/química , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/metabolismo , Animais , Regiões Árticas , Ciclo do Carbono , Ecossistema , Eutrofização , Cadeia Alimentar , Oceanos e Mares , Tamanho da Partícula , Água do Mar/química , Análise Espaço-Temporal , Zooplâncton/crescimento & desenvolvimento , Zooplâncton/metabolismo
9.
Science ; 372(6542)2021 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-33858989

RESUMO

Bones and teeth are important sources of Pleistocene hominin DNA, but are rarely recovered at archaeological sites. Mitochondrial DNA (mtDNA) has been retrieved from cave sediments but provides limited value for studying population relationships. We therefore developed methods for the enrichment and analysis of nuclear DNA from sediments and applied them to cave deposits in western Europe and southern Siberia dated to between 200,000 and 50,000 years ago. We detected a population replacement in northern Spain about 100,000 years ago, which was accompanied by a turnover of mtDNA. We also identified two radiation events in Neanderthal history during the early part of the Late Pleistocene. Our work lays the ground for studying the population history of ancient hominins from trace amounts of nuclear DNA in sediments.


Assuntos
Núcleo Celular/genética , DNA Mitocondrial/genética , Homem de Neandertal/classificação , Homem de Neandertal/genética , Animais , Cavernas/química , DNA Mitocondrial/análise , DNA Mitocondrial/isolamento & purificação , Sedimentos Geológicos/química , Filogenia , População/genética , Análise de Sequência de DNA , Sibéria , Espanha
10.
Bioelectrochemistry ; 140: 107819, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33894567

RESUMO

To limit the nitrate contamination of ground and surface water, stimulation of denitrification by electrochemical approach is an innovative way to be explored. Two nitrate reducing bio-cathodes were developed under constant polarization (-0.5 V vs SCE) using sediments and water from a constructed wetland (Rampillon, Seine-et-Marne, France). The bio-cathodes responded to nitrate addition on chronoamperometry through an increase of the reductive current. The denitrification efficiency of the pilots increased by 47% compared to the negative controls without electrodes after polarization. 16S rRNA gene sequencing of the biofilms and sediments evidenced the significant and discriminating presence of the Azoarcus and Pontibacter genera in the biofilms from biocathodes active for nitrate reduction. Our study shows the possibility to promote the development of efficient Azoarcus-dominated biocathodes from freshwater sediment to enhance nitrate removal from surface waters.


Assuntos
Azoarcus/fisiologia , Bacteroidetes/fisiologia , Biofilmes , Desnitrificação , Sedimentos Geológicos/microbiologia , Nitratos/metabolismo , Áreas Alagadas , Eletrodos , Transporte de Elétrons , Sedimentos Geológicos/química
11.
Food Microbiol ; 98: 103765, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33875201

RESUMO

This study evaluated the occurrence and distribution of total and pathogenic V. parahaemolyticus in oyster culture environments in Taiwan. V. parahaemolyticus levels in oysters, seawater, and sediment were quantified using the most probable number (MPN) method combined with a qualitative polymerase chain reaction (PCR). Total V. parahaemolyticus was determined based on the presence or absence of tlh gene, whereas pathogenic V. parahaemolyticus was determined based on the detection of tdh and/or trh gene. The results showed that: 1) V. parahaemolyticus was detected in 93% of the collected samples, 2) the mean concentrations of total V. parahaemolyticus in oysters, seawater, and sediment were 4.1 log MPN/g, 2.1 log MPN/mL, and 4.2 log MPN/g, respectively, and 3) variations in the abundance of V. parahaemolyticus was significantly associated with sea surface temperature (SST). Findings in this study could be used to improve the accuracy of the risk assessment model for V. parahaemolyticus in oysters in Taiwan.


Assuntos
Contaminação de Alimentos/análise , Ostreidae/microbiologia , Frutos do Mar/microbiologia , Vibrio parahaemolyticus/crescimento & desenvolvimento , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clima , Contagem de Colônia Microbiana , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Ostreidae/crescimento & desenvolvimento , Água do Mar/química , Água do Mar/microbiologia , Taiwan , Temperatura , Vibrio parahaemolyticus/genética , Vibrio parahaemolyticus/isolamento & purificação
12.
Nature ; 592(7853): 232-236, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33782617

RESUMO

The rise of atmospheric oxygen fundamentally changed the chemistry of surficial environments and the nature of Earth's habitability1. Early atmospheric oxygenation occurred over a protracted period of extreme climatic instability marked by multiple global glaciations2,3, with the initial rise of oxygen concentration to above 10-5 of the present atmospheric level constrained to about 2.43 billion years ago4,5. Subsequent fluctuations in atmospheric oxygen levels have, however, been reported to have occurred until about 2.32 billion years ago4, which represents the estimated timing of irreversible oxygenation of the atmosphere6,7. Here we report a high-resolution reconstruction of atmospheric and local oceanic redox conditions across the final two glaciations of the early Palaeoproterozoic era, as documented by marine sediments from the Transvaal Supergroup, South Africa. Using multiple sulfur isotope and iron-sulfur-carbon systematics, we demonstrate continued oscillations in atmospheric oxygen levels after about 2.32 billion years ago that are linked to major perturbations in ocean redox chemistry and climate. Oxygen levels thus fluctuated across the threshold of 10-5 of the present atmospheric level for about 200 million years, with permanent atmospheric oxygenation finally arriving with the Lomagundi carbon isotope excursion at about 2.22 billion years ago, some 100 million years later than currently estimated.


Assuntos
Atmosfera/química , Oxigênio/análise , Oxigênio/história , Isótopos de Carbono/análise , Carbonatos/análise , Clima , Ecossistema , Sedimentos Geológicos/química , História Antiga , Oceanos e Mares , Oxirredução , Água do Mar/química , África do Sul , Isótopos de Enxofre/análise , Fatores de Tempo
13.
Nature ; 592(7854): 397-402, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33731930

RESUMO

The ocean contains unique biodiversity, provides valuable food resources and is a major sink for anthropogenic carbon. Marine protected areas (MPAs) are an effective tool for restoring ocean biodiversity and ecosystem services1,2, but at present only 2.7% of the ocean is highly protected3. This low level of ocean protection is due largely to conflicts with fisheries and other extractive uses. To address this issue, here we developed a conservation planning framework to prioritize highly protected MPAs in places that would result in multiple benefits today and in the future. We find that a substantial increase in ocean protection could have triple benefits, by protecting biodiversity, boosting the yield of fisheries and securing marine carbon stocks that are at risk from human activities. Our results show that most coastal nations contain priority areas that can contribute substantially to achieving these three objectives of biodiversity protection, food provision and carbon storage. A globally coordinated effort could be nearly twice as efficient as uncoordinated, national-level conservation planning. Our flexible prioritization framework could help to inform both national marine spatial plans4 and global targets for marine conservation, food security and climate action.


Assuntos
Biodiversidade , Clima , Conservação dos Recursos Naturais , Abastecimento de Alimentos , Aquecimento Global/prevenção & controle , Animais , Sequestro de Carbono , Pesqueiros , Sedimentos Geológicos/química , Atividades Humanas , Cooperação Internacional
14.
Proc Natl Acad Sci U S A ; 118(6)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33526681

RESUMO

Near-shore marine sediments deposited during the Paleocene-Eocene Thermal Maximum at Wilson Lake, NJ, contain abundant conventional and giant magnetofossils. We find that giant, needle-shaped magnetofossils from Wilson Lake produce distinct magnetic signatures in low-noise, high-resolution first-order reversal curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant, needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Wilson Lake sediments. These simulations underscore the single-domain characteristics and the large magnetic coercivity associated with the extreme crystal elongation of giant needles. Giant magnetofossils have so far only been identified in sediments deposited during global hyperthermal events and therefore may serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a nondestructive method for identifying giant magnetofossil assemblages in bulk sediments, which will help test their ecology and significance with respect to environmental change.


Assuntos
Organismos Aquáticos/isolamento & purificação , Sedimentos Geológicos/química , Magnetossomos/química , Organismos Aquáticos/química , Óxido Ferroso-Férrico/química , Fósseis , Sedimentos Geológicos/análise , Humanos , Fenômenos Magnéticos , Magnetismo , Fenômenos Físicos
15.
Arch Microbiol ; 203(5): 1981-1993, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33528590

RESUMO

Anthropogenically impacted urban canals represent distinct freshwater ecosystems that could shape microbial communities in underlying sediments; however, knowledge of the relationships between environmental factors and microbial community compositions and their functions in such an environment is limited. This study characterized the microbial community compositions of malodorous canal sediments at six locations along the Saen Saep Canal in Thailand. 16S rRNA gene amplicon sequencing (MiSeq, Illumina) revealed dominant genera classified as fermentative bacteria, methanogens, and sulfate-reducing bacteria (SRB), all of which emphasized anaerobic environments. SRB, as the primary producers of malodorous hydrogen sulfide, accounted for 8.2-30.4% of the total sequences. dsrB gene clone libraries further identified the SRB species. A constrained correspondence analysis demonstrated a spatial pattern of SRB that correlated with physicochemical parameters in which nitrate and sulfate in sediments were the most influencing factors. Overall, a better understanding of the SRB and other related microorganisms in canal sediments can assist in the future implementation of appropriate olfactory abatement and management methodologies in urban canals.


Assuntos
Bactérias/metabolismo , Sedimentos Geológicos/microbiologia , Microbiota , Sulfatos/metabolismo , Anaerobiose , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Água Doce/química , Água Doce/microbiologia , Sedimentos Geológicos/química , Nitratos/análise , Nitratos/metabolismo , Filogenia , RNA Ribossômico 16S/genética , Sulfatos/análise , Tailândia
16.
Nat Commun ; 12(1): 1101, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33597520

RESUMO

It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy. However, the presence of such primordial ingredients in early Earth habitats has not yet been demonstrated. Here we report the existence of indigenous organic molecules and gases in primary fluid inclusions in c. 3.5-billion-year-old barites (Dresser Formation, Pilbara Craton, Western Australia). The compounds identified (e.g., H2S, COS, CS2, CH4, acetic acid, organic (poly-)sulfanes, thiols) may have formed important substrates for purported ancestral sulfur and methanogenic metabolisms. They also include stable building blocks of methyl thioacetate (methanethiol, acetic acid) - a putative key agent in primordial energy metabolism and thus the emergence of life. Delivered by hydrothermal fluids, some of these compounds may have fuelled microbial communities associated with the barite deposits. Our findings demonstrate that early Archaean hydrothermal fluids contained essential primordial ingredients that provided fertile substrates for earliest life on our planet.


Assuntos
Archaea/química , Sulfeto de Hidrogênio/análise , Metano/análise , Compostos de Sulfidrila/análise , Sulfato de Bário/análise , Planeta Terra , Ecossistema , Microbiologia Ambiental , Evolução Química , Cromatografia Gasosa-Espectrometria de Massas , Geografia , Sedimentos Geológicos/química , Fatores de Tempo , Austrália Ocidental
17.
Ecotoxicol Environ Saf ; 213: 112017, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33582414

RESUMO

The distribution of hydrophobic organic contaminants (HOCs) in eutrophic ecosystems has been widely studied, but how phytoplankton blooms affect their occurrence and benthic bioaccumulation is poorly understood. To fill this knowledge gap, the biological pump effects of phytoplankton on the fate of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in sediments and benthos (Corbicula fluminea) from Lake Taihu, a hypereutrophic lake in China, were identified. The spatial-temporal distribution of HOCs suggests that higher phytoplankton biomass, coupled with sediment organic matter (SOM) content, greatly increased the concentration of HOCs in sediments in both winter and summer seasons. This could be attributed to the biological pump effects sequestering more HOCs from water to sediments with settling phytoplankton, especially during the summer. The biological pump effects further promoted the uptake of sediment-bound HOCs by benthos. The significant positive relationships between concentrations of HOCs in sediments and benthos were observed during the winter dormancy phase of benthos. Furthermore, the benthic bioaccumulation of HOCs could be strengthened by phytoplankton, due to their contribution to SOM and the following increased bioavailability of HOCs in sediments. Further research is needed to elucidate the phytoplankton biological pump effects on the fate of HOCs in benthic food chain, especially for hypereutrophic waters.


Assuntos
Monitoramento Ambiental , Hidrocarbonetos Clorados/análise , Poluentes Químicos da Água/análise , Bioacumulação , Biomassa , Ecossistema , Cadeia Alimentar , Sedimentos Geológicos/química , Interações Hidrofóbicas e Hidrofílicas , Lagos/química , Proteínas de Membrana Transportadoras , Praguicidas/análise , Fitoplâncton , Hidrocarbonetos Policíclicos Aromáticos/análise , Estações do Ano
18.
Nature ; 590(7844): 97-102, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33536651

RESUMO

Following early hypotheses about the possible existence of Arctic ice shelves in the past1-3, the observation of specific erosional features as deep as 1,000 metres below the current sea level confirmed the presence of a thick layer of ice on the Lomonosov Ridge in the central Arctic Ocean and elsewhere4-6. Recent modelling studies have addressed how an ice shelf may have built up in glacial periods, covering most of the Arctic Ocean7,8. So far, however, there is no irrefutable marine-sediment characterization of such an extensive ice shelf in the Arctic, raising doubt about the impact of glacial conditions on the Arctic Ocean. Here we provide evidence for at least two episodes during which the Arctic Ocean and the adjacent Nordic seas were not only covered by an extensive ice shelf, but also filled entirely with fresh water, causing a widespread absence of thorium-230 in marine sediments. We propose that these Arctic freshwater intervals occurred 70,000-62,000 years before present and approximately 150,000-131,000 years before present, corresponding to portions of marine isotope stages 4 and 6. Alternative interpretations of the first occurrence of the calcareous nannofossil Emiliania huxleyi in Arctic sedimentary records would suggest younger ages for the older interval. Our approach explains the unexpected minima in Arctic thorium-230 records9 that have led to divergent interpretations of sedimentation rates10,11 and hampered their use for dating purposes. About nine million cubic kilometres of fresh water is required to explain our isotopic interpretation, a calculation that we support with estimates of hydrological fluxes and altered boundary conditions. A freshwater mass of this size-stored in oceans, rather than land-suggests that a revision of sea-level reconstructions based on freshwater-sensitive stable oxygen isotopes may be required, and that large masses of fresh water could be delivered to the north Atlantic Ocean on very short timescales.


Assuntos
Água Doce/análise , Camada de Gelo/química , Oceanos e Mares , Regiões Árticas , Foraminíferos/isolamento & purificação , Fósseis , Sedimentos Geológicos/química , História Antiga , Isótopos/análise , Plâncton/isolamento & purificação , Protoactínio/análise , Tório/análise , Fatores de Tempo
19.
Arch Environ Contam Toxicol ; 80(2): 474-489, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33582838

RESUMO

This study provides data on the characteristic levels, spatial patterns, sources, and risk of n-alkanes (AHs) [octane, n-C8, to tetracontane, n-C40] and polycyclic aromatic hydrocarbons (PAHs) in surficial sediments from the Escravos River Basin (ERB), Nigeria. The n-alkane and PAH concentrations in sediments were quantified by chromatographic methods. The concentrations of AHs and PAHs in the ERB sediments varied from 95 to 3430 µg g-1 and from 0.75 to 213 µg g-1, respectively. Both the concentrations of AHs and PAHs in ERB sediments exceeded their respective guideline values. The carbon preference index and other AH markers provide evidence that the AHs in the ERB sediments originated from petroleum sources. Ecological risk assessment indicated that the ecological risk relating to an organism's contact with PAHs in the ERB sediments was high. The possible carcinogenic risk arising from human exposure with PAHs in surface sediments through accidental oral ingestion and skin contact exceeded the safe level of 10-6, indicating a considerable probable cancer risk for fishermen and other inhabitants of the ERB. PAH isomer ratios and multivariate statistics suggested that the PAHs in sediments from the ERB originated from gas flaring inputs, discharges from oil drilling platforms, diesel engines, ships, and speed boats, and combustion of wood and other biomass.


Assuntos
Alcanos/análise , Monitoramento Ambiental , Petróleo/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Sedimentos Geológicos/química , Humanos , Níger , Nigéria , Indústria de Petróleo e Gás , Poluição por Petróleo , Medição de Risco , Rios/química
20.
Ecotoxicol Environ Saf ; 212: 112010, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33550081

RESUMO

Coastal areas are under continuous and increasing pressure from different human activities. A mixture of contaminants (e.g. hydrocarbons, pesticides, persistent organic pollutants (POPs), emerging contaminants, and others), originating mainly from populated, industrialised and agricultural areas, can reach the marine environment through different means such as wastewater discharge, soil runoffs, leaching from agriculture, and volatilisation/deposition. In this context, marine sediments have increasingly been considered repositories for a variety of pollutants that can accumulate and be stored for long periods, acting as a secondary source of contaminants during subsequent dredging operation or vessel manoeuvring. Chemical and ecotoxicological analyses of sediments are routinely conducted to evaluate the potential hazard/risk to the environment, either on bulk sediment or elutriate. In general, sediment elutriates are commonly prepared according to ASTM Guide even if alternative protocols are proposed by USACE for the various condition that they have to represent. The goal of the present study was to determine if the toxicological properties of ASTMprepared elutriates are comparable to those obtained from the USACE protocol. Sediment coming from 3 harbours (Olbia, Cagliari, and Toulon), as part of the "Se.D.Ri.Port" Interreg Project, were processed to obtain elutriates according to ASTM Guide and USACE Dredging Elutriate protocol and tested with the sea urchin Paracentrotus lividus embryo development test. Moreover, the significance of different stirring times of water/sediment mixture (1 h, 3 h, and 24 h) was tested with both the ASTM and USACE protocol. In addition to the biological analysis, for each sediment sample, heavy metals concentration, granulometry, and organic matter were determined. Even if for the ports of Toulon and Cagliari, the ASTM and USACE elutriates showed comparable results with P. lividus bioassay, for the port of Olbia the two protocols showed different criticalities. Preliminary results show that for the site Olbia elutriates prepared with the USACE protocol resulted in higher toxicity than elutriates obtained with ASTM (p < 0.001). In conclusion, differences in preparation protocols appear to be significant and can lead to different results in biological testing. To overcome this problem and to obtain more reliable evaluations of risk to the environment, standardisation and regulation must be the next goals in sediment management procedure.


Assuntos
Desenvolvimento Embrionário/efeitos dos fármacos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/toxicidade , Paracentrotus/efeitos dos fármacos , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Bioensaio , Ecotoxicologia , Humanos , Itália , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mar Mediterrâneo , Metais Pesados/análise , Paracentrotus/embriologia , Poluentes Químicos da Água/análise
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