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1.
Chemosphere ; 261: 128189, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113651

RESUMO

This study compared effects of pH, ionic strength and complexation with Mg2+ on the chromophores and fluorophores of aquatic and terrestrial NOM exemplified by the standard isolates Suwannee River fulvic and humic acid (SRFA and SRHA) and Pahokee Peat fulvic and humic acids (PPFA and PPHA) provided by the International Humic Substance Society (IHSS). The intensity of the differential spectra of the NOM isolates increased monotonically with pH. These spectra comprised contributions of similar chromophore systems associated with the carboxylic and phenolic moieties. The intensity of SRFA and PPFA fluorescence changed non-monotonically vs. pH indicating that the deprotonation of the phenolic fluorophores decreased their emission yields. Examination of the effects of pH on the slopes of the log-transformed absorbance of NOM showed that the influence of deprotonation on the conformations of PPFA and PPHA molecules was less prominent than those for SRFA but not dissimilar to those of SRHA. Changes of the differential spectra and spectral slopes showed that Mg2+/PPFA and Mg2+/PPHA complexation was more effected by electrostatic interactions while the involvement of phenolic groups was notable for SRFA. The observed trends highlight similarities and differences in the properties of the chromophores and fluorophores in the standard isolates of soil and aquatic NOM. These results necessitate further systematic comparison of the properties of NOM isolates and those of unaltered NOM.


Assuntos
Benzopiranos/análise , Sedimentos Geológicos/química , Substâncias Húmicas/análise , Solo/química , Benzopiranos/química , Sedimentos Geológicos/análise , Concentração de Íons de Hidrogênio , Magnésio/análise , Concentração Osmolar , Rios/química , Espectrometria de Fluorescência/métodos
2.
Chemosphere ; 261: 128186, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113661

RESUMO

Although microplastics (MPs; < 5 mm) have been recognized as one of the most challenging environmental pollutants in the ocean, our understanding of the environmental fate of freshwater MPs falls far behind, particularly on smaller MPs (<0.1 mm). Here, we seek to reveal the latest MP pollution status in the largest freshwater lake of China, Poyang Lake, by comprehensively assessing the abundance, distribution, size, shape, polymer composition, and micro-morphology of MPs in water and sediment, covering a large geographic area of the Lake and its five main river tributaries. High levels of MPs were detected in water (up to 1064 ± 90 MP/m3) and sediment (up to 1936 ± 121 MP/kg), with the highest concentrations in the Gan River and the lowest in the national Nature Reserves. While a positive correlation was identified between MP abundance in water and sediment, the size distribution of MPs in between water and sediment was distinct. The dominant MP form in sediment and water was fragment and fiber, respectively. Infrared spectroscopy analysis confirmed the dominant polymer types including polypropylene, polyvinyl chloride, polyethylene, polystyrene, and polyvinyl alcohol. Moreover, both µ-FTIR and SEM results suggested significant features of weathering and fragmentation of MPs. This study provides comprehensive data to understand the environmental behavior and pollution magnitude of MPs in China's largest freshwater lake and highlights the significant contribution of smaller-size fractions (0.03-0.1 mm) to improve future MP studies in freshwater systems.


Assuntos
Lagos/análise , Microplásticos/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Microplásticos/química , Microscopia Eletrônica de Varredura , Polietileno/análise , Polietileno/química , Polipropilenos/análise , Polipropilenos/química , Rios/química , Espectroscopia de Infravermelho com Transformada de Fourier
3.
PLoS One ; 15(10): e0236305, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33105476

RESUMO

The Indian River Lagoon, located on the east coast of Florida, USA, is an Estuary of National Significance and an important economic and ecological resource. The Indian River Lagoon faces several environmental pressures, including freshwater discharges through the St. Lucie Estuary; accumulation of anoxic, fine-grained, organic-rich sediment; and metal contamination from agriculture and marinas. Although the Indian River Lagoon has been well-studied, little is known about its microbial communities; thus, a two-year 16S amplicon sequencing study was conducted to assess the spatiotemporal changes of the sediment bacterial and archaeal groups. In general, the Indian River Lagoon exhibited a prokaryotic community that was consistent with other estuarine studies. Statistically different communities were found between the Indian River Lagoon and St. Lucie Estuary due to changes in porewater salinity causing microbes that require salts for growth to be higher in the Indian River Lagoon. The St. Lucie Estuary exhibited more obvious prokaryotic seasonality, such as a higher relative abundance of Betaproteobacteriales in wet season and a higher relative abundance of Flavobacteriales in dry season samples. Distance-based linear models revealed these communities were more affected by changes in total organic matter and copper than changes in temperature. Anaerobic prokaryotes, such as Campylobacterales, were more associated with high total organic matter and copper samples while aerobic prokaryotes, such as Nitrosopumilales, were more associated with low total organic matter and copper samples. This initial study fills the knowledge gap on the Indian River Lagoon bacterial and archaeal communities and serves as important data for future studies to compare to determine possible future changes due to human impacts or environmental changes.


Assuntos
Archaea/classificação , Bactérias/classificação , Biodiversidade , Sedimentos Geológicos/microbiologia , Células Procarióticas/classificação , Rios/microbiologia , Poluentes Químicos da Água/análise , Archaea/isolamento & purificação , Bactérias/isolamento & purificação , Estuários , Florida , Sedimentos Geológicos/análise
4.
PLoS One ; 15(10): e0239209, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33002077

RESUMO

Recent decades have been marked by unprecendented environmental changes which threaten the integrity of freshwater systems and their ecological value. Although most of these changes can be attributed to human activities, disentagling natural and anthropogenic drivers remains a challenge. In this study, surface sediments from Lake Ighiel, a mid-altitude site in the Carpathian Mts (Romania) were investigated following high-resolution sedimentological, geochemical, environmental magnetic and diatom analyses supported by historical cartographic and documentary evidence. Our results suggest that between 1920 and 1960 the study area experienced no significant anthropogenic impact. An excellent correspondence is observed between lake proxy responses (e.g., growth of submerged macrophytes, high detrital input, shifts in diatom assemblages) and parameters tracking natural hydroclimate variability (e.g., temperature, NAO). This highlights a dominant natural hydroclimatic control on the lacustrine system. From 1960 however, the depositional regime shifted markedly from laminated to homogenous clays; since then geochemical and magnetic data document a trend of significant (and on-going) subsurface erosion across the catchment. This is paralleled by a shift in lake ecosystem conditions denoting a strong response to an intensified anthropogenic impact, mainly through forestry. An increase in detrital input and marked changes in the diatom community are observed over the last three decades, alongside accelerated sedimentation rates following enhanced grazing and deforestation in the catchment. Recent shifts in diatom assemblages may also reflect forcing from atmospheric nitrogen (N) deposition, a key recent drive of diatom community turnover in mountain lakes. In general, enhanced human pressure alongside intermittent hydroclimate forcing drastically altered the landscape around Lake Ighiel and thus, the sedimentation regime and the ecosystem's health. However, paleoenvironmental signals tracking natural hydroclimate variability are also clearly discernible in the proxy data. Our work illustrates the complex link between the drivers of catchment-scale impacts on one hand, and lake proxy responses on the other, highlighting the importance of an integrated historical and palaeolimnological approach to better assess lake system changes.


Assuntos
Mudança Climática , Lagos , Altitude , Mudança Climática/história , Conservação dos Recursos Naturais , Diatomáceas , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos/análise , História do Século XIX , História do Século XX , História do Século XXI , Humanos , Lagos/análise , Recursos Naturais , Nitrogênio/análise , Romênia
5.
PLoS One ; 15(9): e0239137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32997670

RESUMO

Sediment and soil contamination with toxic heavy metals, including cadmium (Cd2+) and lead (Pb2+), represents a major long-term remediation challenge. Resuspension of contaminated sediments into the water column, or the uptake of toxic metals from top soil, can lead to exposure of aquatic or terrestrial organisms, followed by bioconcentration, bioaccumulation and biomagnification, which may pose a threat to public health. We have developed a novel nanoscale engineered material, namely ligand-coated dense nanoparticles (Ligand DNPs), which contain a dense WO3 nanoparticle core and a shell functionalized with a metal-binding organic ligand (EDTA), to effectively sequester heavy metal ions deeper into the soil and sediments. We demonstrate that one application of Ligand DNPs can remove from 60% to almost 80% of the Cd and Pb in two different soil matrices, driving these metal ions deeper into the sediment or soil column via gravity, and making them less bioavailable. Ligand DNPs can provide a relatively fast, convenient, and efficient in-situ approach for the remediation of sediments and soils contaminated with heavy metals.


Assuntos
Quelantes/química , Recuperação e Remediação Ambiental/métodos , Metais Pesados/química , Óxidos/química , Poluentes do Solo/química , Tungstênio/química , Engenharia Química , Poluição Ambiental/efeitos adversos , Estudos de Viabilidade , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Ligantes , Metais Pesados/análise , Nanocompostos/química , Nanopartículas/química , Nanotecnologia , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Fatores de Tempo
6.
Bull Environ Contam Toxicol ; 105(4): 613-619, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32964273

RESUMO

The distribution, composition, sources, and potential ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Lanzhou Reach of the Yellow River, China were investigated. The total concentration of the 18 individual PAHs (∑18PAHs) in the sediments ranged from 638 to 1620 ng/g, with a mean value of 901 ng/g. The pollution level of PAHs in the sediments was low to moderate. Spatially, the distribution of PAHs in the sediments showed an increasing trend along the direction of water flow. ∑18PAHs predominantly consisted of low molecular weight PAHs. The principal component analysis and isomer ratios of PAHs suggested the mixed sources of petroleum and those from the combustion of petroleum, coal, and biomass. The results showed that the PAHs in the sediments of the Lanzhou Reach of the Yellow River have a low ecological risk. However, the BaP equivalent exposure values suggested a potential cancer risk.


Assuntos
Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Biomassa , China , Carvão Mineral/análise , Sedimentos Geológicos/análise , Petróleo/análise , Análise de Componente Principal , Medição de Risco , Rios
7.
Bull Environ Contam Toxicol ; 105(4): 546-552, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32870331

RESUMO

The heavy metals were studied in water, sediments, algae, and various tissues of Glyptosternon reticulatum and Cyprinus carpio from River Swat, Pakistan, using flame atomic absorption spectrophotometer. The Zn, Cu, Pb and Ni were higher in water at sewage site compared to upstream and downstream sites. In sediments, the Ni and Cd were not detected whereas Cu, Pb and Zn were higher at downstream followed by sewage and upstream sites. The Ni and Zn in algae were higher at upstream and sewage sites compared to downstream site whereas Pb and Cd were higher at upstream site compared to sewage and downstream sites and Cu was found same at all the three sites. The heavy metals (Zn > Cu > Pb and Ni) in tissues (liver > gills > skin > muscles) of G. reticulatum was higher than in C. carpio. This study recommends the proper monitoring of River Swat in order to save its water and inhabitant aquatic life.


Assuntos
Carpas/metabolismo , Peixes-Gato/metabolismo , Sedimentos Geológicos/análise , Metais Pesados/metabolismo , Rios/química , Spirogyra/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Metais Pesados/análise , Paquistão , Especificidade da Espécie , Distribuição Tecidual , Poluentes Químicos da Água/análise
8.
Bull Environ Contam Toxicol ; 105(4): 538-545, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32968836

RESUMO

In the present study, heavy metals (Cd, Cu, Pb, and Zn) level in the water, sediment, and crabs were analyzed from Noyyal and Chinnar Rivers of the Western Ghats in Tamil Nadu, India. Based on our results, Noyyal River is considered as polluted environment due to the discharge of contaminants by various anthropogenic activities, whereas, Chinnar River maintained as unpolluted one due to its tributary nature of Noyyal River located in Western Ghats hills. The results showed that the heavy metals in water and sediments were higher in Noyyal River. Also, the level of bioaccumulation of studied metals and biochemical constituents were higher in the crab Spiralothelphusa hydrodroma sampled from Noyyal River than Barytelphusa cunicularis collected from Chinnar River. The present findings revealed that the crab sampled from Noyyal River had elevated heavy metals which lead to a significant increase in biochemical constituents to overcome the stress.


Assuntos
Braquiúros/metabolismo , Exposição Ambiental , Sedimentos Geológicos/análise , Metais Pesados/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Bioacumulação , Monitoramento Ambiental , Feminino , Índia , Masculino , Rios/química , Especificidade da Espécie , Inquéritos e Questionários , Poluição Química da Água
9.
PLoS One ; 15(9): e0238894, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915881

RESUMO

Quantitative analyses of soil and sediment samples are often used to complement stratigraphic interpretations in archaeological and geoscientific research. The outcome of such analyses often is confined to small parts of the examined profiles as only a limited number of samples can be extracted and processed. Recent laboratory studies show that such selectively measured soil and sediment characteristics can be spatially extrapolated using spectral image data, resulting in reliable maps of a variety of parameters. However, on-site usage of this method has not been examined. We therefore explore, whether image data (RGB data and visible and near infrared hyperspectral data), acquired under regular fieldwork conditions during an archaeological excavation, in combination with a sampling strategy that is close to common practice, can be used to produce maps of soil organic matter, hematite, calcite, several weathering indices and grain size characteristics throughout complex archaeological profiles. We examine two profiles from an archaeological trench in Yeha (Tigray, Ethiopia). Our findings show a promising performance of RGB data and its derivative CIELAB as well as hyperspectral data for the prediction of parameters via random forest regression. By including two individual profiles we are able to assess the accuracy and reproducibility of our results, and illustrate the advantages and drawbacks of a higher spectral resolution and the necessary additional effort during fieldwork. The produced maps of the parameters examined allow us to critically reflect on the stratigraphic interpretation and offer a more objective basis for layer delineation in general. Our study therefore promotes more transparent and reproducible documentation for often destructive archaeological fieldwork.


Assuntos
Arqueologia/métodos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Laboratórios/estatística & dados numéricos , Solo/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Etiópia , Reprodutibilidade dos Testes
10.
Nat Commun ; 11(1): 3831, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737305

RESUMO

Long-term time series have provided evidence that anthropogenic pressures can threaten lakes. Yet it remains unclear how and the extent to which lake biodiversity has changed during the Anthropocene, in particular for microbes. Here, we used DNA preserved in sediments to compare modern micro-eukaryotic communities with those from the end of the 19th century, i.e., before acceleration of the human imprint on ecosystems. Our results obtained for 48 lakes indicate drastic changes in the composition of microbial communities, coupled with a homogenization of their diversity between lakes. Remote high elevation lakes were globally less impacted than lowland lakes affected by local human activity. All functional groups (micro-algae, parasites, saprotrophs and consumers) underwent significant changes in diversity. However, we show that the effects of anthropogenic changes have benefited in particular phototrophic and mixotrophic species, which is consistent with the hypothesis of a global increase of primary productivity in lakes.


Assuntos
DNA/genética , Eucariotos/genética , Sedimentos Geológicos/análise , Lagos/análise , Alveolados/classificação , Alveolados/genética , Alveolados/isolamento & purificação , Biodiversidade , Evolução Biológica , Ecossistema , Eucariotos/classificação , Eucariotos/isolamento & purificação , História do Século XIX , História do Século XX , História do Século XXI , Atividades Humanas/história , Humanos , Microalgas/classificação , Microalgas/genética , Microalgas/isolamento & purificação , Microbiota/genética , Processos Fototróficos/fisiologia , Rhizaria/classificação , Rhizaria/genética , Rhizaria/isolamento & purificação , Estramenópilas/classificação , Estramenópilas/genética , Estramenópilas/isolamento & purificação
11.
PLoS One ; 15(8): e0237592, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813751

RESUMO

It remains debatable whether slash-and-burn practices were adopted in rice cultivation by the Neolithic Kuahuqiao culture in the Ningshao Plain, one of the birthplaces of rice farming. Here, we established charcoal-based indices to reconstruct the history of fire and vegetation in the Ningshao Plain since the last glacial period. We collected representative modern vegetation and conducted combustion and fragmentation experiments to simulate fire and depositional processes, respectively. Charcoals from modern vegetation show clear morphological differences between herbaceous and woody plants. In particular, the length to width ratios (L/W) of herbaceous charcoals were systematically higher than those of woody charcoals, and the associated end-member values were 4.50 and 1.94, respectively. These values were then applied to sediment cores (KHQ-14/15) collected in proximity to the Kuahuqiao archaeological site. Results show that the amount of combusted herbaceous plants increased sharply after the Holocene, and the most remarkable rise occurred around 8550 yr B.P. This observation may reflect local environment (sedimentary and/or climatic) changes or small-scale early human activities. During the Kuahuqiao cultural period (8250-7450 yr B.P.), the relative abundance of woody charcoals increased, but the overall fire intensity decreased. This finding suggests that the Kuahuqiao farming was restricted to a small geographic area and large-scale slash-and-burn farming activities were not adopted.


Assuntos
Agricultura/métodos , Carvão Vegetal/análise , Fogo/estatística & dados numéricos , Sedimentos Geológicos/análise , Solo/química , China , Atividades Humanas , Humanos
12.
PLoS One ; 15(8): e0237528, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845899

RESUMO

The Middle to Later Stone Age transition marks a major change in how Late Pleistocene African populations produced and used stone tool kits, but is manifest in various ways, places and times across the continent. Alongside changing patterns of raw material use and decreasing artefact sizes, changes in artefact types are commonly employed to differentiate Middle Stone Age (MSA) and Later Stone Age (LSA) assemblages. The current paper employs a quantitative analytical framework based upon the use of neural networks to examine changing constellations of technologies between MSA and LSA assemblages from eastern Africa. Network ensembles were trained to differentiate LSA assemblages from Marine Isotope Stage 3&4 MSA and Marine Isotope Stage 5 MSA assemblages based upon the presence or absence of 16 technologies. Simulations were used to extract significant indicator and contra-indicator technologies for each assemblage class. The trained network ensembles classified over 94% of assemblages correctly, and identified 7 key technologies that significantly distinguish between assemblage classes. These results clarify both temporal changes within the MSA and differences between MSA and LSA assemblages in eastern Africa.


Assuntos
Arqueologia/métodos , Fósseis , Sedimentos Geológicos/análise , Redes Neurais de Computação , África Oriental , Animais , Humanos
13.
PLoS One ; 15(8): e0237605, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804934

RESUMO

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Druksiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.


Assuntos
Radioisótopos de Carbono/análise , Sedimentos Geológicos/análise , Lagos/química , Monitoramento de Radiação/métodos , Animais , Radioisótopos de Césio/análise , Peixes/crescimento & desenvolvimento , Radioisótopos de Chumbo/análise , Lituânia , Centrais Nucleares
14.
PLoS One ; 15(7): e0236272, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32716947

RESUMO

As part of an interdisciplinary research project on the Late La Tène period settlement at Basel-Gasfabrik, ceramic sherds, animal bones and archaeological sediments from different archaeological structures (one large pit, two ditches and four archaeological layers) were examined in respect of 21 taphonomic features (proxies). These proxies, in turn, were linked to different processes that can leave traces on objects or sediments: primary use, mechanical stress, heat impact, water, redeposition, exposure, covering and postdepositional processes. The different proxies were compared using a statistical procedure. Our results show significant differences between the different features with regard to taphonomic alteration. For example, ceramic sherds and animal bones from archaeological layers show severe alteration due to exposure, whilst a good and uniform preservation within the pit points to its rapid filling. Furthermore, there is evidence of middens which probably served as material depots. Our results suggest that waste was not simply seen as rubbish, but was stored as a resource. Therefore, materials could take different "paths", each of which resulted in specific taphonomic processes (alterations). The interdisciplinary approach taken in this project has provided new insight into the complex but probably clearly defined handling of various materials at Basel-Gasfabrik, thus allowing us to visualise part of the cultural biography of things.


Assuntos
Osso e Ossos/anatomia & histologia , Cerâmica , Sedimentos Geológicos/análise , Estudos Interdisciplinares , Animais , Arqueologia , Análise Fatorial , Geografia , Suíça
15.
PLoS One ; 15(7): e0234351, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667918

RESUMO

Planktic foraminiferal biostratigraphic zonation schemes are critical for providing first-order relative age control in deep-sea sediments and provide the basis on which to interpret evolutionary dynamics through time. Over the previous decades, the majority of published biostratigraphic zonation schemes focused on the tropical regions of the world. The mid-latitude or temperate regions, especially of the northwest Pacific, have been understudied in terms of recording plankton occurrences. Lack of detailed biostratigraphic studies have largely left out this region from plankton evolutionary analyses, thus how this part of the world ocean, which is characterized by the Kuroshio Current Extension (KCE), may contribute to global plankton biodiversity is unknown. In this study, we present the first magnetostratigraphically-calibrated late Neogene to Quaternary (15.12-0 Ma) planktic foraminiferal zonation schemes from the northwest Pacific for three Ocean Drilling Program Leg 198 holes (1207A, 1208A, and 1209A) that span the KCE. We utilize previously published warm subtropical, cool subtropical, and temperate zonation schemes from the southwest Pacific, with modifications. We find examples of significant diachroneity among primary marker taxa used to construct biozones at the three northwest Pacific sites, which ranges from 0.075 to 2.29 million years. Comparison of our primary datum markers with those of the tropical planktic foraminiferal zonation scheme also reveal diachroneity on the scale of 0.022 to 4.8 million years. We have identified times of intense dissolution in the northwest Pacific, namely in the middle to late Miocene that likely contribute to the observed diachroneity of datums. This study highlights the need for regionally specific mid-latitude biostratigraphic zonation schemes, as diachronous datums and differing assemblages may be hallmarks of oceanic ecotones created by major boundary current systems. These data also provide a framework to characterize local plankton evolutionary dynamics and paleobiogeographic patterns in future studies.


Assuntos
Sedimentos Geológicos/análise , Sedimentos Geológicos/classificação , Plâncton/classificação , Biodiversidade , Evolução Biológica , Foraminíferos/classificação , Noroeste dos Estados Unidos , Oceanos e Mares , Oceano Pacífico , Temperatura
16.
Environ Geochem Health ; 42(11): 3765-3778, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32594418

RESUMO

The heavy metal contamination of the aquatic ecosystem is still prevalent even after reduction of the external anthropogenic inputs of the metals. The release of labile heavy metals from the sediments into the water is a potential risk, responsible for the contamination of the aquatic system. Herein, samples of sedimentary column cores were collected in Nansi Lake, and the distribution profiles of the labile and soluble metals (Cd, Cu, Ni, Pb, and Zn) were obtained by the diffusive gradient in thin films (DGT) and the high-resolution dialysis (HR-peeper) technique. Furthermore, the mobility, bioavailability and release risk of the heavy metals were assessed using the results of geochemical sequential extraction, DGT as well as the DGT-induced fluxes in sediments (DIFS) model. The results showed that the profile characteristics of the DGT-labile and soluble heavy metals showed irregular distribution in the sediment cores and Cd, Pb, Zn had an obvious positive correlation with Fe/Mn (p < 0.05). Ni, Cu, and Zn existed primarily in the residual fraction (accounting for 58-76%), while Cd and Pb existed in the reducible fraction (accounting for 50-67%). The Cd and Ni (0.027-0.185) had higher mobility coefficients compared with Pb, Cu, and Zn (0-0.011), and positive diffusive fluxes also proved that Cd and Ni were easy to be released from the sediments. In addition, the R values of five metals (0.18-0.85) ranged between Rdiff to 0.95, indicating that all the metals had partially sustained case from the sediments solid phase. Based on the DIFS model, the five metals had weak mobility from the sediment to pore water, but the release risks in the Nansi Lake should also be of concern, especially for the highly mobile Cd and Ni in the Dushan Lake.


Assuntos
Sedimentos Geológicos/química , Lagos/química , Metais Pesados/análise , Poluentes Químicos da Água/análise , Disponibilidade Biológica , China , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Lagos/análise , Metais Pesados/química , Metais Pesados/farmacocinética , Modelos Teóricos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/farmacocinética
17.
Chemosphere ; 257: 127181, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32485515

RESUMO

Cadmium (Cd) and lead (Pb) are two typical heavy metals of the Jialing River, and their threat to the river has been considered by the government in recent years. In this study, the diffusive gradient in thin films (DGT) technique and sequential extraction were employed together to analyse the remobilization and fraction of Cd and Pb in the sediments. The total concentration of Cd and Pb in four sampling sites both followed the order S3>S4>S2>S1. The sequential extraction results indicated that large amounts of Cd and Pb (over 50% of the total concentration) were bound to the exchangeable and reducible fraction. The DGT results showed that both Cd and Pb presented a significant increasing trend at the bottom of the DGT probe (-10 cm to -12 cm) and that the two metals had a significant positive correlation (r = 0.831, p < 0.01). The apparent diffusive flux result indicated that Cd and Pb had a potential risk of release from surface sediments. A significant correlation was observed between the DGT-labile fraction and sequential extraction at the surface sediments. A further correlation analysis found that the concentration of labile Cd/Pb measured by DGT (CDGT-Cd and CDGT-Pb) had a strong negative correlation with CDGT-Fe, and this process was mainly mitigated by the iron oxides in the sediments. In addition, the correspondence of a "dark area" of AgI gel with corresponding "hotspots" of Chelex gel also proved that the release of Cd and Pb may regulate the dissolved sulfide in the sediments.


Assuntos
Cádmio/análise , Monitoramento Ambiental , Chumbo/análise , Poluentes Químicos da Água/análise , Difusão , Sedimentos Geológicos/análise , Metais Pesados/análise , Rios , Sulfetos/análise
18.
PLoS One ; 15(6): e0234110, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32530916

RESUMO

Sediments from stratified marine environments often show an enhanced preservation of organic matter (OM) which is attributed to the limitation, or absence, of oxygen in the bottom waters and surface sediments. Yet there is still a limited knowledge about the changes that the associated biomarker signals undergo in the different parts of a stratified environment, and as to which extent the situation in the productive upper parts of the water column is eventually reflected in the sedimentary record. To better understand these processes we studied particulate matter samples from the stratified, partly anoxic Eastern Gotland Basin (EGB, Central Baltic Sea) during a strong cyanobacterial bloom in August 2016. Endmember samples representing the main biomass producers within the phytoplankton (cyanobacteria) and mesozooplankton (copepods) were obtained from different levels of the water column. Major extractable lipids (fatty acids, n-alcohols, sterols, and selected hydrocarbons) were analysed from the same materials and compared to samples cored from the underlying surface sediments (0-12 cm). Given the annually recurring phenomenon of cyanobacterial blooms we anticipated to find a considerable lipid footprint of the major primary producers in the sedimentary record of the EGB. Unexpectedly, however, lipids in the surface sediments largely derived from the storage lipids (mainly wax esters) of the copepod Pseudocalanus spp. which thrived in deeper, more saline and oxygen-depleted waters. Carbon number and unsaturation patterns suggest that the component n-alcohols of these wax esters are transformed into the corresponding n-fatty acids prior to further degradation in the sediment. In the EGB deposits, most of the plankton-derived lipids studied appear to be degraded on a time scale of decades. In terms of relative abundances, long-chain n-alkyl lipids and C29 sterols from terrestrial plant sources instead become predominant in the deeper sediment layers. Likewise, higher stanol/sterol ratios of C27-sterols vs. C29-sterols indicate a more intense biodegradation of planktonic OM as compared to terrestrial OM. Our observations indicate that primary produced particulate OM is heavily modified by mesozooplankton grazing. This overprint adds on the influence of heterotrophic microorganisms and, in the sediment, preferential preservation of terrestrial biomarkers. Taken together, these factors result in a major decoupling of the biomarker signals between the productive upper mixed layer and the oxygen-depleted bottom waters and sediments of the EGB.


Assuntos
Biomarcadores/análise , Sedimentos Geológicos/análise , Lipídeos/análise , Zooplâncton/metabolismo , Animais , Países Bálticos , Copépodes/crescimento & desenvolvimento , Copépodes/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Ácidos Graxos/análise , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos/análise , Esteróis/análise , Poluentes Químicos da Água/análise , Zooplâncton/crescimento & desenvolvimento
19.
PLoS One ; 15(6): e0234853, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555679

RESUMO

A new method to evaluate archaeological wetland sites in a more objective way was tested. Different wetland environments have been sampled in areas of a nature reserve and their macroremain content analysed to build a modern analogue dataset. This dataset was then used to characterise archaeological samples from a navigation channel from the Roman port city Lattara. In the modern analogue samples, the different wetland types (saline/brackish or fresh water) could be differentiated in the correspondence analysis. Within these groups, the sampled area of the littoral (submerged, shoreline, unsubmerged) could also be differentiated. This dataset can therefore provide a basis for the interpretation of the nature and degree of aquatic influence and layer formation processes in archaeobotanical records of coastal sites. In the tested archaeological samples from the navigation channel of Lattara, changes in space and time could be tracked using the modern analogue dataset and geoarchaeological information. The channel lost its fresh water supply and silted up over a short period of time (approx. 100 years).


Assuntos
Água Doce/análise , Sedimentos Geológicos/análise , Plantas , Águas Salinas/análise , Áreas Alagadas , Arqueologia , Conjuntos de Dados como Assunto , França , Mar Mediterrâneo
20.
J Environ Sci Health B ; 55(9): 783-793, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32586197

RESUMO

Considering the increase in agricultural production in Tocantins and in the use of pesticides for such production, this work investigates the levels of pesticide residues in different environmental compartments (soil, sediment, and water samples) of the Formoso River in the state of Tocantins, Brazil. The presence of pesticides of the triazine, triazole, and benzimidazole classes was analyzed by UHPLC-MS/MS from April 2018 to February 2019. There were four quarterly collections in the dry and rainy periods. The active principles were not found in sediment samples. In soil samples, only the active ingredients tebuconazole and propiconazole were found in the third collection campaign. The active ingredients amethryn, atrazine, carbendazim, epoxiconazole, metconazole, propiconazole, simazine, tebuconazole, and tetraconazole were found in water samples from Formoso River at concentrations of up to 0.286 µg L-1 (atrazine). Although the substances are in low concentrations, we cannot assume that this toxicity is low considering that the risk of a certain pesticide depends on levels and exposure time. Therefore, the action of substances external to the natural environment always threatens biodiversity.


Assuntos
Benzimidazóis/análise , Praguicidas/análise , Triazinas/análise , Triazóis/análise , Poluentes Químicos da Água/análise , Brasil , Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental , Sedimentos Geológicos/análise , Resíduos de Praguicidas/análise , Rios/química , Poluentes do Solo/análise , Espectrometria de Massas em Tandem
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