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1.
Sci Total Environ ; 803: 149857, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34496345

RESUMO

Owing to the local characteristics of stable nitrogen isotopes in nitrogen oxides (δ15N-NOx) emitted from biomass burning, the lack of data on δ15N-NOx values associated with biomass burning in China limits the use of this parameter in identifying and quantifying the sources of atmospheric nitrate (NO3-) and NOx. The results showed that the δ15N-NOx values of open burning and rural cooking stoves in China ranged from -3.7‰ to 3.1‰ and -11.9‰ to 1.5‰, respectively. The δ15N values of nine biomass fuel sources (δ15N-biomass) ranged from 0.1‰ to 4.1‰. Significant linear relationships between the δ15N-biomass values and δ15N-NOx values of open burning (δ15N-NOx = 1.1δ15N-biomass - 2.7; r2 = 0.63; p < 0.05) and rural cooking stoves (δ15N-NOx = 1.7δ15N-biomass - 9.8; r2 = 0.72; p < 0.01) suggested that the variations in δ15N-NOx values from biomass burning were mainly controlled by the biomass fuel source. The isotopic fractionation of nitrogen during the biomass burning process might have led to the higher δ15N-NOx values from open burning in comparison to rural cooking stoves. By combining the δ15N-NOx values of biomass burning with biomass burning emission inventory data, a model for calculating the δ15N-NOx values of biomass burning in different regions of China was established, and the estimated δ15N-NOx value of biomass burning at the national scale was -0.8 ± 1.2‰. But the limited δ15N-biomass values increase the uncertainty of model in national scale.


Assuntos
Poluentes Atmosféricos , Nitrogênio , Poluentes Atmosféricos/análise , Biomassa , China , Monitoramento Ambiental , Isótopos de Nitrogênio/análise
2.
J Sci Food Agric ; 102(1): 330-340, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34097746

RESUMO

BACKGROUND: The natural abundance of stable isotope 15 N (δ15 N) in production systems has emerged as an alternative to distinguish organic products from conventional ones. This study evaluated the use of δ15 N values recorded for nitrogen fertilizers, soil and plant tissue in order to set the differences between organic and conventional agricultural production systems applied to rice, potatoes, apple and banana crops. RESULTS: Values of δ15 N recorded for N sources ranged from +5.58‰ to +18.27‰ and from -3.55‰ to +3.19‰ in organic and synthetic fertilizers, respectively. Values recorded for δ15 N in food from organic rice, potatoes and banana farms were higher than values recorded for δ15 N in conventional farms; the same was observed for values recorded for δ15 N in leaves from the four crops. CONCLUSION: Results have allowed for differentiation between production systems due to values of δ15 N recorded in leaves of all crops and food, for rice, potatoes and banana trees. © 2021 Society of Chemical Industry.


Assuntos
Alimentos Orgânicos/análise , Alimentos Orgânicos/normas , Isótopos de Nitrogênio/análise , Certificação , Qualidade dos Alimentos , Malus/química , Musa/química , Oryza/química , Solanum tuberosum/química
3.
Sci Total Environ ; 806(Pt 1): 150408, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34571224

RESUMO

The identification of nitrogen sources and cycling processes is critical to the management of nitrogen pollution. Here, we used both stable (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+) and radiogenic (222Rn) isotopes together with nitrogen concentrations to evaluate the relative importance of point (i.e. sewage) and diffuse sources (i.e. agricultural-derived NO3- from groundwater, drains and creeks) in driving nitrogen dynamic in a shallow coastal embayment, Port Phillip Bay (PPB) in Victoria, Australia. This study is an exemplar of nitrogen-limited coastal systems around the world where nitrogen contamination is prevalent and where constraining it may be challenging. In addition to surrounding land use, we found that the distributions of NO3- and NH4+ in the bay were closely linked to the presence of drift algae. Highest NO3- and NH4+ concentrations were 315 µmol L-1 and 2140 µmol L-1, respectively. Based on the isotopic signatures of NO3- (δ15N: 0.17 to 21‰; δ18O: 3 to 26‰) and NH4+ (δ15N: 30 to 39‰) in PPB, the high nitrogen concentrations were attributed to three major sources which varied between winter and summer; (1) nitrified sewage effluent and drift algae derived NH4+ mainly during winter, (2) NO3- mixture from atmospheric deposition, drains and creeks predominantly observed during summer and (3) groundwater and sewage derived NO3- during both surveys. The isotopic composition of NO3- also suggested the removal of agriculture-derived NO3- through denitrification was prevalent during transport. This study highlights the role of terrestrial-coastal interactions on nitrogen dynamics and illustrates the importance of submarine groundwater discharge as a prominent pathway of diffuse NO3- inputs. Quantifying the relative contributions of multiple NO3- input pathways, however, require more extensive efforts and is an important avenue for future research.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Monitoramento Ambiental , Nitratos/análise , Nitrogênio/análise , Isótopos de Nitrogênio/análise , Vitória , Poluentes Químicos da Água/análise
4.
Sci Total Environ ; 806(Pt 1): 150479, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34583081

RESUMO

Excessive ammonia-nitrogen (N) in aquifers has caused groundwater pollution on the Dongting Plain (DTP), which seriously threatens the safety of drinking water. It is urgent and necessary to determine the sources and enrichment mechanisms of ammonia-N in groundwater. Carrying out water and soil collaborative research on a three-dimensional scale can more comprehensively analyze the sources of N, including natural and anthropogenic sources. In this study, surface and groundwater quality characteristics were examined from a total of 77 sites on the DTP. Two subsequent boreholes were drilled in the high ammonia concentration area and normal groundwater area, respectively, to compare the effects of anthropogenic activities. Indicators from hydrogeochemical and pedogeochemical analyses, as well as various isotopes, including δ15N-NH4+, δ15N-TON, δ15N-NO3-, δ18O-NO3-, δ18O-H2O, δD-H2O, and δ13C-TOC were used to identify ammonium sources and transformation mechanisms in the strata. We found that the sediments were contaminated by manure and sewage in the aquifers, and part of the shallow groundwater was additionally contaminated by nitrogen fertilizers. Excessive ammonium-N was also detected in the deep aquitards and sediments, which were mainly dominated by mineralization. Ammonia oxidation (with weak hydroxylamine oxidation) is an important biogeochemical process in which ammonia and nitrate do not accumulate in oxidizing groundwater environments. However, heterotrophic nitrification (HN) and anaerobic ammonium oxidation (ANAMMOX) are the release mechanisms for excessive ammonium-N under reducing conditions. In addition, organic matter (OM) on the DTP had a wide range of biogeochemical proxies generated by phytoplankton within a lake, and the comparatively resilient terrestrial organic residues washed in from the surrounding terrestrial area. This study breaks through the conventional mechanisms for the release of excessive ammonium from sediments to aquifers, which provides new ideas for research on ammonium in sediments and ammonia in groundwater.


Assuntos
Compostos de Amônio , Água Subterrânea , Poluentes Químicos da Água , China , Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Poluentes Químicos da Água/análise
5.
Food Chem ; 371: 131133, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34808758

RESUMO

Octopus play an increasingly important role in ocean ecosystems and global fisheries, yet techniques for authenticating provenance are sorely lacking. For the first time, we investigate whether chemical profiling can distinguish geographical origins of octopus on international and domestic scales. Our samples consisted of wild-caught octopus from south-east Asia and southern Australia, regions with high seafood trade. We used a novel combination of stable carbon (δ13C) and oxygen (δ18O) isotope analyses (Isotope-Ratio Mass Spectrometry) of internal calcified structures called statoliths, with elemental analyses (X-Ray Fluorescence using Itrax) of soft-tissue. We found that multivariate profiles exhibited distinctive regional signatures, even across species, with high classification success (∼95%) back to region of origin. This study validates isotopic and multi-elemental profiling as an effective provenance tool for octopus, which could be used to support transparency and accountability of seafood supply chains and thus encourage sustainable use of ocean resources.


Assuntos
Octopodiformes , Animais , Isótopos de Carbono/análise , Ecossistema , Espectrometria de Massas , Isótopos de Nitrogênio/análise , Alimentos Marinhos/análise
6.
Sci Total Environ ; 804: 150072, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34509848

RESUMO

Within the East African Rift System (EARS), the complex Ali-Sabieh aquifers system, located in the south of the Republic of Djibouti, was overexploited and subjected to anthropogenic and/or geogenic pollution with high concentrations of dissolved nitrate (up to 181 mg/l) and sulfates (up to 1540 mg/l). This study is the first undertaken on the hydrochemistry of this aquifer system, combining geochemical tools and multi-isotope - δ2H(H2O), δ18O(H2O), δ18O(SO4), δ34S(SO4), δ15N(NO3), δ18O(NO3), δ13C(DIC), and 14C- was used to decipher the origin and fate of different nitrate and sulfate sources to groundwater. The groundwater samples of the region show a chemical evolution from fresh Ca(Na)-bicarbonate to brackish Na-Cl , mainly due to water-rock interaction. The combined chloride and water isotope data show that evaporation and transpiration are present, with the latter occurring primarily in the shallow alluvial aquifer waters. Inspection of δ15N(NO3) vs. δ18O(NO3) and NO3/Cl vs. Cl diagrams show that dissolved nitrates are primarily of anthropogenic origin. In particular, higher nitrate concentrations may be related to animal manure used as organic fertilizers during agricultural activities. Sulfates are from a natural origin related to the interaction of water with gypsum of hydrothermal or sedimentary origin. SO4/Cl ratio and isotopic composition show that dissolved sulfates in saline and ancient groundwater of the Cretaceous sandstone aquifer (between 7.4 ± 2.2 and 5.8 ± 1.4 k-years before the present) are generated by interaction with gypsum from oxidation of pre-existing (Jurassic?) sulfides. This work highlight that isotopic ratios of the two molecules -δ18O(SO4), δ34S(SO4), δ15N(NO3), δ18O(NO3)- are not sufficient for tracing the origin of nitrate and sulfates in groundwater, but that a complete hydrogeochemical study is needed. In the absence of this, the relatively high concentration of chloride and sulfates could be wrongly linked to the anthropogenic source of nitrate (manure or sewage).


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Animais , Djibuti , Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Sulfatos , Poluentes Químicos da Água/análise
7.
PLoS One ; 16(10): e0257444, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34710099

RESUMO

Floodplains represent critical nursery habitats for a variety of fish species due to their highly productive food webs, yet few tools exist to quantify the extent to which these habitats contribute to ecosystem-level production. Here we conducted a large-scale field experiment to characterize differences in food web composition and stable isotopes (δ¹³C, δ¹5N, δ³4S) for salmon rearing on a large floodplain and adjacent river in the Central Valley, California, USA. The study covered variable hydrologic conditions including flooding (1999, 2017), average (2016), and drought (2012-2015). In addition, we determined incorporation rates and tissue fractionation between prey and muscle from fish held in enclosed locations (experimental fields, cages) at weekly intervals. Finally, we measured δ³4S in otoliths to test if these archival biominerals could be used to reconstruct floodplain use. Floodplain-reared salmon had a different diet composition and lower δ13C and δ³4S (δ¹³C = -33.02±2.66‰, δ³4S = -3.47±2.28‰; mean±1SD) compared to fish in the adjacent river (δ¹³C = -28.37±1.84‰, δ³4S = +2.23±2.25‰). These isotopic differences between habitats persisted across years of extreme droughts and floods. Despite the different diet composition, δ¹5N values from prey items on the floodplain (δ¹5N = 7.19±1.22‰) and river (δ¹5N = 7.25±1.46‰) were similar, suggesting similar trophic levels. The food web differences in δ13C and δ³4S between habitats were also reflected in salmon muscle tissue, reaching equilibrium between 24-30 days (2014, δ¹³C = -30.74±0.73‰, δ³4S = -4.6±0.68‰; 2016, δ¹³C = -34.74 ±0.49‰, δ³4S = -5.18±0.46‰). δ³4S measured in sequential growth bands in otoliths recorded a weekly time-series of shifting diet inputs, with the outermost layers recording time spent on the floodplain (δ³4S = -5.60±0.16‰) and river (δ³4S = 3.73±0.98‰). Our results suggest that δ¹³C and δ³4S can be used to differentiate floodplain and river rearing habitats used by native fishes, such as Chinook Salmon, across different hydrologic conditions and tissues. Together these stable isotope analyses provide a toolset to quantify the role of floodplains as fish habitats.


Assuntos
Salmão/crescimento & desenvolvimento , Fenômenos Fisiológicos da Nutrição Animal , Animais , Isótopos de Carbono/análise , Ecossistema , Cadeia Alimentar , Isótopos de Nitrogênio/análise , Rios , Salmão/fisiologia , Isótopos de Enxofre/análise
8.
PLoS One ; 16(10): e0257524, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34610013

RESUMO

It is well-known that pigs (Sus scrofa) were domesticated very early in Neolithic China, but far less is known about the processes by which pig husbandry intensified so that pork became the most important animal protein for humans are less clear. Here, we explore pig feeding practices using the carbon and nitrogen isotope composition of bone collagen, focusing on developments in pig husbandry during the Yangshao period (7000-5000 BP) in the middle Yellow River region of China, and at the site of Xipo (5800-5000 BP) in particular. The results show that the diets of domestic pigs at Xipo were dominated by millet foods. Comparisons with other Yangshao sites in the region show a trend of increasing millet foddering for pigs throughout the Yangshao period. These results, and comparisons of the isotopic data for pigs against those for humans from the Xipo cemetery (5300-5000 BP), suggest that pigs were closely managed by humans. The evidence points to an intensification of Neolithic pig husbandry in the middle Yellow River region from this period.


Assuntos
Criação de Animais Domésticos/história , Sus scrofa , Ração Animal/análise , Animais , Isótopos de Carbono/análise , China , Dieta , Domesticação , História Antiga , Humanos , Isótopos de Nitrogênio/análise , Rios , Sus scrofa/crescimento & desenvolvimento , Sus scrofa/fisiologia
9.
Environ Sci Technol ; 55(21): 14946-14956, 2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34637308

RESUMO

Nitrate concentrations in high-elevation lakes of the Colorado Front Range remain elevated despite declining trends in atmospherically deposited nitrate since 2000. The current source of this elevated nitrate in surface waters remains elusive, given shifts in additional nitrogen sources via glacial inputs and atmospheric ammonium deposition. We present the complete isotopic composition of nitrate (δ15N, δ18O, and Δ17O) from a suite of nitrate-bearing source waters collected during the summers of 2017-2018 from two alpine ecosystems to constrain the provenance of elevated nitrate in surface waters during the summer open-water season. The results indicate a consistent contribution of uncycled atmospheric nitrate throughout the summer (13-23%) to alpine lakes, despite seasonal changes in source water inputs. The balance of nitrate (as high as 87% in late summer) is likely from nitrate production within the catchment via nitrification of reduced nitrogen sources (e.g., thawed soil organic matter and ammonium deposition) and released with rock glacier meltwater. The role of microbially produced nitrate has become increasingly important over time based on historical surface water samples from the mid-90s to present, a trend coincident with increasing ammonium deposition to alpine systems.


Assuntos
Nitratos , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Rios , Poluentes Químicos da Água/análise
10.
Sci Total Environ ; 792: 148353, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465044

RESUMO

Eutrophication in coastal water has compromised ecosystem services. Identification of phosphorus (P) sources and their load contributions are required for the development of effective nutrient management plans. In this research, multi-isotope proxies were applied to track P sources and evaluate their relative contributions in Love Creek, a coastal estuary in Delaware. The isotope values of carbon (ca. -22‰), nitrogen (ca.+6‰), and phosphate oxygen (ca.+18‰) of agricultural soils under different agricultural practices are generally similar even though their concentrations are distinctly different from forest soils (δ13C: ca. -27‰; δ13N: ca.+2‰; δ18OP: ca.+22‰). Comparison of these parameters among potential land sources (agricultural soils, forest soils, septic wastes, and plant debris) and sink (colloids in water) revealed that the plant debris and soils from forest sources are likely dominant sources of P in freshwater sites. The contribution of terrestrial P sources gradually decreased along the salinity gradient and agricultural soil sources gradually dominanted in the saline water portion of the creek. The variations of P loads due to weather-related discharge, changing land use and activities, and seasons were high and reflected the limitation of accurate estimation of sources. Overall, these results provide improved insights into potential sources and biogeochemical processes in the estuary, which are expected to be useful for water quality monitoring programs.


Assuntos
Estuários , Fósforo , Ecossistema , Monitoramento Ambiental , Isótopos de Nitrogênio/análise , Fósforo/análise , Salinidade
11.
Environ Pollut ; 290: 118119, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34523528

RESUMO

Although groundwater nitrogen pollution has been widely studied, the control of hydrogeological conditions on behavior of nitrogen compounds has been poorly understood. In this study, multiple stable isotopes (N/C/H/O), spectral characteristics of DOM coupled with water chemistry were used to reveal the sources and fate of nitrate and ammonium in three subareas with different hydrogeological conditions in the Central Yangtze River Basin. We identified three contrasting patterns of nitrogen sources and fate in groundwater controlled by different aquifer features. In a reducing porous aquifer mainly composed of carbonate minerals overlain by a thick low-permeability layer, the NH4-N concentration is high (mean 4.12 mg/L) but with quite low NO3-N concentration (mean 0.28 mg/L). The high ammonium is mainly from intense degradation of organic matter (OM), while denitrification at a higher rate results in nitrate removal. Feammox may be favored owing to abundant humics acting as the electron shuttle. In a weakly reducing to oxidizing porous aquifer mainly composed of aluminosilicate minerals overlain by a varying thickness of low-permeability layer, high ammonium occurs in a weakly reducing condition and is affected by both anthropogenic input and OM degradation, while high nitrate occurs in a more oxidizing condition and could be mainly from soil nitrogen, manure or sewage. Feammox may be also favored due to more acidic environment formed by weathering of aluminosilicate minerals, fluctuating redox condition and low abundance of labile organic carbon, while denitrification occurs at a slower rate coupled with concurrent re-oxidation of nitrite to nitrate. In an oxidizing porous - fissured aquifer system overlain by a thin low-permeability layer, the concentrations of ammonium and nitrate are both low, possibly due to strong hydrodynamic and flushing condition, although slightly higher concentration of nitrate exhibit similar sources and fate with the weakly reducing to oxidizing porous aquifer mentioned above.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Monitoramento Ambiental , Nitratos/análise , Nitrogênio/análise , Compostos de Nitrogênio , Isótopos de Nitrogênio/análise , Rios , Poluentes Químicos da Água/análise
12.
Environ Sci Technol ; 55(18): 12261-12271, 2021 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-34469681

RESUMO

Formation pathways and sources of atmosphere nitrate (NO3-) have attracted much attention as NO3- had detrimental effects on Earth's ecosystem and climate change. Here, we measured nitrogen (δ15N-NO3-) and oxygen (δ18O-NO3- and Δ17O-NO3-) isotope compositions in nitrate aerosols at the Qomolangma station (QOMS) over the Himalayan-Tibetan Plateau (HTP) to quantify the formation mechanisms and emission sources of nitrate at the background site. At QOMS, the enhanced NO3- concentrations were observed in the springtime. The average δ15N-NO3-, δ18O-NO3-, and Δ17O-NO3- values were 0.4 ± 4.9, 64.7 ± 11.5 and 27.6 ± 6.9‰, respectively. Seasonal variations of isotope ratios at QOMS can be explained by the different emissions and formation pathways to nitrate. The average fractions of NO2 + OH and N2O5 + H2O to nitrate production were estimated to be 43 and 52%, respectively, when the NO3 + hydrocarbon (HC)/dimethyl sulfide (DMS) (NO3 + HC/DMS) pathway was assumed to be 5%. Using stable isotope analysis in the R (SIAR) model, the relative contributions of biomass burning (BB), biogenic soil emission, traffic, and coal combustion to nitrate were estimated to be 28, 25, 24, and 23%, respectively, on yearly basis. By FLEXible PARTicle (FLEXPART) dispersion model, we highlighted that NOx from BB emission over South Asia that had undergone N2O5 + H2O processes enhanced the nitrate concentrations in the springtime over the HTP region.


Assuntos
Nitratos , Nitrogênio , Aerossóis , China , Ecossistema , Monitoramento Ambiental , Nitratos/análise , Nitrogênio/análise , Isótopos de Nitrogênio/análise , Isótopos de Oxigênio/análise , Tibet
13.
J Environ Manage ; 300: 113693, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34547573

RESUMO

A dual isotopes approach and the Bayesian isotope mixing model were applied to trace nitrogen pollution sources and to quantify their relative contribution to river water quality. We focused on two points to enhance the applicability of the method: 1) Direct measurement on the end-members to distinguish "sewage" and "manure" which used to be grouped in one pollution source as their isotope ranges overlap; 2) The Lagrangian sampling method was applied to consider the transport of nitrogen pollutants in a long river so that any fractionation process can be dealt with in the given Bayesian modeling framework. The results of the analysis confirmed the NO3- isotope composition in the river of interest to be within the range of NO3- with origins in "NH4+ in fertilizer", "Soil N", and "Manure and sewage" pollution. This suggests that nitrogen pollution is mostly attributed to anthropogenic sources. The δ18O NO3 value follows the range +2.5∼+15.0‰, implying that NO3- in the river is mainly derived from nitrification, and possible nitrification in groundwater or waterfront other than surface water. The ratio of the concentration of δ15N NO3 to that of δ18O NO3, and the corresponding regression equation indicates that the denitrification effect in surface water was insignificant during the study period. From the results of the contribution ratio of each source, improving the water quality of the discharge from the sewage treatment plants was proved to be the key factor to reduce nitrogen pollution in the river.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Teorema de Bayes , China , Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Poluentes Químicos da Água/análise
14.
Int J Mol Sci ; 22(17)2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34502545

RESUMO

Prion diseases are associated with conformational conversion of cellular prion protein into a misfolded pathogenic form, which resembles many properties of amyloid fibrils. The same prion protein sequence can misfold into different conformations, which are responsible for variations in prion disease phenotypes (prion strains). In this work, we use atomic force microscopy, FTIR spectroscopy and magic-angle spinning NMR to devise structural models of mouse prion protein fibrils prepared in three different denaturing conditions. We find that the fibril core region as well as the structure of its N- and C-terminal parts is almost identical between the three fibrils. In contrast, the central part differs in length of ß-strands and the arrangement of charged residues. We propose that the denaturant ionic strength plays a major role in determining the structure of fibrils obtained in a particular condition by stabilizing fibril core interior-facing glutamic acid residues.


Assuntos
Amiloide/metabolismo , Doenças Priônicas/metabolismo , Proteínas Priônicas/metabolismo , Agregação Patológica de Proteínas/metabolismo , Sequência de Aminoácidos , Amiloide/química , Animais , Isótopos de Carbono/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Camundongos , Microscopia de Força Atômica/métodos , Isótopos de Nitrogênio/metabolismo , Proteínas Priônicas/química , Conformação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Relação Estrutura-Atividade
15.
BMC Res Notes ; 14(1): 347, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34488867

RESUMO

OBJECTIVES: Existing information on Arctic marine food web structure is fragmented. Integrating data across research programs is an important strategy for building a baseline understanding of food web structure and function in many Arctic regions. Naturally-occurring stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) measured directly in the tissues of organisms are a commonly-employed method for estimating food web structure. The objective of the current dataset was to synthesize disparate δ15N, and secondarily δ13C, data in the Canadian Beaufort continental shelf region relevant to trophic and ecological studies at the local and pan-Arctic scales. DATA DESCRIPTION: The dataset presented here contains nitrogen and carbon stable isotope ratios (δ15N, δ13C) measured in marine organisms from the Canadian Beaufort continental shelf region between 1983 and 2013, gathered from 27 published and unpublished sources with associated sampling metadata. A total of 1077 entries were collected, summarizing 8859 individual organisms/samples representing 333 taxa across the Arctic food web, from top marine mammal predators to primary producers.


Assuntos
Organismos Aquáticos , Nitrogênio , Animais , Regiões Árticas , Canadá , Ecossistema , Cadeia Alimentar , Isótopos de Nitrogênio/análise
16.
An Acad Bras Cienc ; 93(4): e20190868, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34586310

RESUMO

Ontogenetic shifts in food preference reduces intraspecific competition as immature individuals eat different food types than adults. This diet plasticity could facilitate species' ability to successfully invade and establish itself in a new environment, even when co-occurring with phylogenetically close species. Here, ontogenetic diet shifts of a non-native piranha species (Serrasalmus marginatus) was tested by analyzing the relationship between its body length and the carbon and nitrogen stable isotope signatures. Carbon stable isotope was not correlated to fish length, but positive significant correlation between δ15N values and fish length was found for the non-native piranha. Also, immature and adult S. marginatus showed low isotopic niche overlap. The correlation between fish length and δ15N, and the low trophic overlap between immature and adult, indicate that the non-native S. marginatus had ontogenetic shifts in food preference, which may be viewed as an additional mechanism underlying its successful establishment in the upper Paraná River. Our findings indicate that ontogenetic shifts in food preference may be an invasive trait that facilitates the establishment of non-native fish species in tropical aquatic systems.


Assuntos
Caraciformes , Animais , Isótopos de Carbono , Dieta/veterinária , Ecossistema , Humanos , Isótopos de Nitrogênio , Rios
17.
Oecologia ; 197(2): 485-500, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34480229

RESUMO

Historically, anthropogenic fixed nitrogen has been purposely increased to benefit food production and global development. One consequence of this increase has been to raise concentrations of nitrogen in aquatic ecosystems. To evaluate whether nitrogen pollution promotes changes in the estimates of niche space of fish communities, we examined 16 sites along a Brazilian river basin highly impacted by anthropogenic activities, especially discharge of domestic and industrial sewage from a region with more than 5 million inhabitants. We analysed the carbon (δ13C) and nitrogen (δ15N) isotope ratios of fish species and both autochthonous (periphyton) and allochthonous (course and fine particulate organic matter) basal food resources. To estimate the magnitude of nitrogen pollution, we measured the nitrate and ammonium concentrations at each site. Sampling was conducted in the dry and wet seasons to evaluate the influence of seasonality. Nitrogen pollution generally increased estimates of niche space, and seasonality influenced only the niche estimates of fish communities from polluted sites. In addition, isotopic analyses of nitrogen polluted sites yielded unrealistic estimates of trophic positioning (detritivores at the top of the food web). We conclude that changes in niche space estimates reflect both alterations in baseline isotopic values and differential trophic behaviour among fishes. Our study suggests that under conditions of high pollution, other factors appear to influence isotopic estimates of niche, such as isotopically distinct sources that have not been sampled, and/or differences in δ15N turnover rates between fish tissue and basal resources, creating isotopic baselines that are challenging to interpret.


Assuntos
Ecossistema , Nitrogênio , Animais , Isótopos de Carbono/análise , Peixes , Cadeia Alimentar , Isótopos de Nitrogênio/análise , Rios
18.
PLoS One ; 16(8): e0255398, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34388162

RESUMO

Stable isotope analyses of bone collagen are often used in palaeoecological studies to reveal environmental conditions in the habitats of different herbivore species. However, such studies require valuable reference data, obtained from analyses of modern individuals, in habitats of well-known conditions. In this article, we present the stable carbon and nitrogen isotope composition of bone collagen from modern red deer (N = 242 individuals) dwelling in various habitats (N = 15 study sites) in Europe. We investigated which of the selected climatic and environmental factors affected the δ13C and δ15N values in bone collagen of the studied specimens. Among all analyzed factors, the percent of forest cover influenced the carbon isotopic composition most significantly, and decreasing forest cover caused an increase in δ13C values. The δ15N was positively related to the proportion of open area and (only in the coastal areas) negatively related to the distance to the seashore. Using rigorous statistical methods and a large number of samples, we confirmed that δ13C and δ15N values can be used as a proxy of past habitats of red deer.


Assuntos
Cervos , Animais , Isótopos de Carbono , Ecossistema , Isótopos de Nitrogênio
19.
Angew Chem Int Ed Engl ; 60(43): 23207-23211, 2021 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-34432359

RESUMO

Cellular DNA is composed of four canonical nucleosides (dA, dC, dG and T), which form two Watson-Crick base pairs. In addition, 5-methylcytosine (mdC) may be present. The methylation of dC to mdC is known to regulate transcriptional activity. Next to these five nucleosides, the genome, particularly of stem cells, contains three additional dC derivatives, which are formed by stepwise oxidation of the methyl group of mdC with the help of Tet enzymes. These are 5-hydroxymethyl-dC (hmdC), 5-formyl-dC (fdC), and 5-carboxy-dC (cadC). It is believed that fdC and cadC are converted back into dC, which establishes an epigenetic control cycle that starts with methylation of dC to mdC, followed by oxidation and removal of fdC and cadC. While fdC was shown to undergo intragenomic deformylation to give dC directly, a similar decarboxylation of cadC was postulated but not yet observed on the genomic level. By using metabolic labelling, we show here that cadC decarboxylates in several cell types, which confirms that both fdC and cadC are nucleosides that are directly converted back to dC within the genome by C-C bond cleavage.


Assuntos
DNA/metabolismo , Desoxicitidina/análogos & derivados , Genoma/fisiologia , Animais , Células CHO , Cricetulus , DNA/química , Descarboxilação , Desoxicitidina/química , Desoxicitidina/metabolismo , Deutério/química , Camundongos , Isótopos de Nitrogênio/química
20.
J Phys Chem Lett ; 12(32): 7701-7707, 2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34355903

RESUMO

The resolving power of solid-state nuclear magnetic resonance (NMR) crystallography depends heavily on the accuracy of computational predictions of NMR chemical shieldings of candidate structures, which are usually taken to be local minima in the potential energy. To test the limits of this approximation, we systematically study the importance of finite-temperature and quantum nuclear fluctuations for 1H, 13C, and 15N shieldings in polymorphs of three paradigmatic molecular crystals: benzene, glycine, and succinic acid. The effect of quantum fluctuations is comparable to the typical errors of shielding predictions for static nuclei with respect to experiments, and their inclusion improves the agreement with measurements, translating to more reliable assignment of the NMR spectra to the correct candidate structure. The use of integrated machine-learning models, trained on first-principles energies and shieldings, renders rigorous sampling of nuclear fluctuations affordable, setting a new standard for the calculations underlying NMR structure determinations.


Assuntos
Benzeno/química , Glicina/química , Ácido Succínico/química , Isótopos de Carbono/química , Cristalografia/métodos , Hidrogênio/química , Aprendizado de Máquina , Espectroscopia de Ressonância Magnética , Isótopos de Nitrogênio/química
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