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This study investigates spatio-temporal variations of PM10 mass concentrations and associated metal(oid)s, δ13C carbon isotope ratios, polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC) and equivalent black carbon (eBC) concentrations over a half year period (from March 2017 to October 2017) in two residential areas of Medellín (MED-1 and MED-2) and Itagüí municipality (ITA-1 and ITA-2) at a tropical narrow valley (Aburrá Valley, Colombia), where few data are available. A total of 104 samples were analysed by using validated analytical methodologies, providing valuable data for PM10 chemical characterisation. Metal(oid)s concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion, and PAHs concentrations were measured by Gas Chromatography-Mass Spectrometry (GC-MS) after Pressurised Hot Water Extraction (PHWE) and Membrane Assisted Solvent Extraction (MASE). Mean PM10 mass concentration ranged from 37.0 µg m-3 to 45.7 µg m-3 in ITA-2 and MED-2 sites, respectively. Al, Ca, Mg and Na (from 6249 ng m-3 for Mg at MED-1 site to 10,506 ng m-3 for Ca at MED-2 site) were the major elements in PM10 samples, whilst As, Be, Bi, Co, Cs, Li, Ni, Sb, Se, Tl and V were found at trace levels (< 5.4 ng m-3). Benzo[g,h,i] perylene (BghiP), benzo[b + j]fluoranthene (BbjF) and indene(1,2,3-c,d)pyrene (IcdP) were the most profuse PAHs in PM10 samples, with average concentrations of 0.82-0.86, 0.60-0.78 and 0.47-0.58 ng m-3, respectively. Results observed in the four sampling sites showed a similar dispersion pattern of pollutants, with temporal fluctuations which seems to be associated to the meteorology of the valley. A PM source apportionment study were carried out by using the positive matrix factorization (PMF) model, pointing to re-suspended dust, combustion processes, quarry activity and secondary aerosols as PM10 sources in the study area. Among them, combustion was the major PM10 contribution (accounting from 32.1 to 32.9% in ITA-1 and ITA-2, respectively), followed by secondary aerosols (accounting for 13.2% and 23.3% ITA-1 and MED-1, respectively). Finally, a moderate carcinogenic risk was observed for PM10-bound PAHs exposure via inhalation, whereas significant carcinogenic risk was estimated for carcinogenic metal(oid)s exposure in the area during the sampling period.
Assuntos
Poluição do Ar , Exposição Ambiental , Material Particulado , Poluentes Atmosféricos/análise , Carbono/análise , Colômbia , Monitoramento Ambiental/métodos , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Medição de Risco , Poluição do Ar/estatística & dados numéricos , Exposição Ambiental/estatística & dados numéricos , HumanosRESUMO
Marine species from the Gulf of Mexico often have higher mercury (Hg) concentrations than conspecifics in the Atlantic Ocean. Spatial differences in Hg sources, environmental conditions, and microbial communities influence both Hg methylation rates and the bioavailability of Hg to organisms at the base of the food web. Mercury bioaccumulates within organisms and biomagnifies in marine food webs, and therefore reaches the greatest concentrations in long-lived marine carnivores, such as dolphins. In this study, we explored whether differences in trophic position and foraging habitat among bottlenose dolphins (Tursiops truncatus) from the northern Gulf of Mexico (nGoM) contributed to the observed variation in skin total Hg (THg) concentrations. Using the δ13C and δ34S values in dolphin skin, we assigned deceased stranded dolphins from Florida (FL; n = 29) and Louisiana (LA; n = 72) to habitats (estuarine, barrier island, and coastal) east and west of the Mississippi River Delta (MRD). We estimated the mean trophic position of dolphins from each habitat using δ15N values from stranded dolphin skin and tissues of primary consumers taken from the literature following a Bayesian framework. Finally, we compared trophic positions and THg concentrations among dolphins from each habitat, accounting for sex and body length. Estimated marginal mean THg concentrations (µg/g dry weight) were greatest in dolphins assigned to the coastal habitat and estuarine habitats east of the MRD (range: 2.59-4.81), and lowest in dolphins assigned to estuarine and barrier island habitats west of the MRD (range: 0.675-0.993). On average, dolphins from habitats with greater THg concentrations also had higher estimated trophic positions, except for coastal dolphins. Our results suggest that differences in trophic positions and foraging habitats contribute to spatial variability in skin THg concentrations among nGoM bottlenose dolphins, however, the relative influence of these factors on THg concentrations are not easily partitioned.
Assuntos
Golfinho Nariz-de-Garrafa , Mercúrio , Poluentes Químicos da Água , Animais , Teorema de Bayes , Monitoramento Ambiental , Golfo do México , Mercúrio/análise , Poluentes Químicos da Água/análiseRESUMO
In seasonally dry tropical forests, plant functional type can be classified as deciduous low wood density, deciduous high wood density, or evergreen high wood density species. While deciduousness is often associated with drought-avoidance and low wood density is often associated with tissue water storage, the degree to which these functional types may correspond to diverging and unique water use strategies has not been extensively tested.We examined (a) tolerance to water stress, measured by predawn and mid-day leaf water potential; (b) water use efficiency, measured via foliar δ13C; and (c) access to soil water, measured via stem water δ18O.We found that deciduous low wood density species maintain high leaf water potential and low water use efficiency. Deciduous high wood density species have lower leaf water potential and variable water use efficiency. Both groups rely on shallow soil water. Evergreen high wood density species have low leaf water potential, higher water use efficiency, and access alternative water sources. These findings indicate that deciduous low wood density species are drought avoiders, with a specialized strategy for storing root and stem water. Deciduous high wood density species are moderately drought tolerant, and evergreen high wood density species are the most drought tolerant group.Synthesis. Our results broadly support the plant functional type framework as a way to understand water use strategies, but also highlight species-level differences.
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Due to their long life-span and top trophic position, odontocetes can accumulate high concentrations of mercury (Hg) in their tissues. This study measured the concentration of total Hg (THg) in the blubber and skin of bottlenose dolphins (Tursiops truncatus) that stranded along the Florida (FL) panhandle and Louisiana (LA) coasts and investigated the relationship between total Hg (THg) concentration and sex, body length, age, stranding location, diet/trophic position (δ13C and δ15N, respectively), and foraging habitat (δ34S). Additionally, we compared models using body length and age as explanatory variables to determine which was a better predictor of THg concentration. In both tissues, sex was not an influential predictor of THg concentration and there was a positive relationship between body length/age and THg concentration (pâ¯<â¯0.001). Florida dolphins had greater mean blubber and skin THg concentrations compared to LA dolphins (pâ¯<â¯0.001). There was a modest improvement in model fit when age was used in place of body length. δ13C, δ15N, and δ34S differed between stranding locations and together with age were significant predictors of THg concentrations (R2â¯=â¯0.52, Pâ¯<â¯0.001). Florida dolphins were δ13C enriched compared to LA dolphins (pâ¯<â¯0.001) and THg concentrations were positively correlated with δ13C (R2â¯=â¯0.22, pâ¯<â¯0.001). Our results demonstrate spatial variability in THg concentrations from stranded bottlenose dolphins from the northern Gulf of Mexico; however, future research is required to understand how fine-scale population structuring of dolphins within FL and LA impacts THg concentrations, particularly among inshore (bay, sound, and estuary) stocks and between inshore and offshore stocks, as variations in biotic and abiotic conditions can influence both stable isotope ratios and THg concentrations.
Assuntos
Golfinho Nariz-de-Garrafa , Mercúrio , Poluentes Químicos da Água , Tecido Adiposo/química , Animais , Carga Corporal (Radioterapia) , Monitoramento Ambiental , Florida , Golfo do México , Louisiana , Mercúrio/análise , Pele/químicaRESUMO
The toxic metal lead (Pb) can be harmful to human health in various manners, but is also considered as a distinguished tracer of environmental pollution since the relative abundance of its four stable isotopes with the atomic masses of 204, 206, 207, and 208 varies with the emission source. This study is focused on the Pb concentrations and isotope ratios in the particulate matter of the Brazilian city of Goiânia in order to determine the main Pb emission sources. Particulate matter samples were collected on clean Teflon filters during rainy and dry season in 2014 in the center of Goiânia city near main roads with a high traffic volume. Pb concentrations as well as stable Pb isotope ratios of the particulate matter samples were analyzed by inductively coupled plasma-mass spectrometry. To apply this analytical technique successfully, it was necessary to optimize parameters in case of acquisition time, detector dead time, and mass discrimination, which affect the measurement accuracy and precision. Results showed that Pb concentrations in Goiânia were different between rainy and dry season. Pb concentrations showed higher values and less variation in dry season than in rainy season. Pb isotope ratios demonstrated significant variations between dry and rainy season. An enrichment of 206Pb isotopes related to 207Pb and 208Pb isotopes was observed in dry season. However, the comparison of the obtained isotopic Pb signature with data of potential Pb sources from previous studies indicated that traffic-related sources should be considered as main Pb source in the particulate matter of Goiânia. These assumptions were incorporated by the calculation of the contribution factor of Pb coming from traffic-related sources by applying binary mixing equations.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Chumbo/análise , Material Particulado/análise , Brasil , Cidades , Humanos , Isótopos/análise , Espectrometria de Massas , Estações do AnoRESUMO
Aiming to investigate the effect of diet and food consumption with regard to health, environment, and economy in light of nutrition ecology, we studied the dimensions of nutrition and food security in urban and rural settings in the region of Chapada dos Veadeiros, Central Brazil. We tracked diet and food consumption through carbon and nitrogen stable isotope ratios in fingernails of these inhabitants together with food intake data as a proxy for their diet patterns. We estimated household food insecurity by using the Brazilian Food Insecurity Scale. Nutrition and food insecurity was observed in both urban and rural areas, but was accentuated in rural settings. The diet pattern had high δ(13)C values in fingernails and low δ(15)N. Both urban and rural areas have diets with low diversity and relying on low-quality processed food staples at the same time that nutrition and food insecurity is quite high in the region.
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Dieta/efeitos adversos , Manipulação de Alimentos , Abastecimento de Alimentos , Transição Epidemiológica , Internacionalidade , Saúde da População Rural , Saúde da População Urbana , Brasil , Isótopos de Carbono/análise , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Países em Desenvolvimento , Dieta/etnologia , Dieta/psicologia , Características da Família/etnologia , Qualidade dos Alimentos , Abastecimento de Alimentos/economia , Jardinagem , Humanos , Unhas/química , Isótopos de Nitrogênio/análise , Inquéritos Nutricionais/métodos , Estado Nutricional , Saúde da População Rural/economia , Saúde da População Rural/etnologia , Fatores Socioeconômicos , Saúde da População Urbana/economia , Saúde da População Urbana/etnologiaRESUMO
Leaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density. We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment. High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment. We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies.
Assuntos
Arabidopsis/anatomia & histologia , Oxigênio/metabolismo , Folhas de Planta/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , Transpiração Vegetal , Água/metabolismo , Arabidopsis/metabolismo , Isótopos de Oxigênio/análise , Folhas de Planta/metabolismo , Estômatos de Plantas/metabolismoRESUMO
In order to define the effect of nutrient enrichment on trophic webs in an Andean mountain stream we performed an experiment using stable isotope ratios (δ15N and δ13C) to analyze different trophic compartments: 1) basal level: CPOM and biofilm; 2) primary consumers - macroinvertebrates: collector-gatherers (Heterelmis sp., Thraulodes sp. and Trichorythodes sp.), and collectorfilterers (Simulium sp.); 3) predators - fish (Oncorhynchus mykiss and Trichomycterus bogotensis). The average fractionation of nitrogen among the primary consumers with respect to CPOM was 4.7 , and 1.7 with respect to biofilm. Predators incremented their δ15N signal by 5.9 % with respect to primary consumers. A depletion of δ15N was observed in Impact with respect to Control reach after fertilization in different compartments (biofilm, Heterelmis, Simulium andTricorythodes), while depletion was not significant for top predators. In most cases, the δ13C signal of biofilm overlapped with that of primary consumers, but a clear enrichment was observed with respect to CPOM. Macroinvertebrate gut contents showed fine detritus to be their most abundant food, and that in general there were no changes in diet as a consequence of nutrient enrichment. The only exception was Heterelmis, who increased its consumption in the Impact reach.
Con el fin de determinar el efecto del incremento de nutrientes sobre la red trófica de un río de montaña andino, se realizó un experimento en donde se analizaron las proporciones de isotopos estables (δ15N y δ13C) para analizar los siguientes compartimientos tróficos: 1) Nivel basal: CPMO y Biofilm; 2) Consumidores primarios - macroinvertebrados: colectores - recolectores (Heterelmis sp., Thraulodes sp., yTrichorythodes sp.) y colectores - filtradores (Simulium sp.); 3) Depredadores - peces (Oncorhynchus mykiss y Trichomycterus bogotensis). La fracción promedio de nitrógeno entre los consumidores primarios con respecto a CPOM fue de 4.7 , y de 1.7 con respecto al biofilm. Los depredadores incrementaron en un 5.9 % la señal δ15N con respecto a los consumidores primarios. Después de la fertilización, se observó en diferentes compartimientos (biofilm, Heterelmis, Simulium yTricorythodes) del tramo impacto un agotamiento de δ15N con respecto al control, mientras que el agotamiento no fue significativo para los depredadores superiores. En la mayoría de los casos la señal δ13C del biofilm se sobrepuso con la de los consumidores primarios pero un claro enriquecimiento fue observado con respecto a CPOM. Los macroinvertebrados referidos fueron seleccionados para analizar su contenido estomacal y los resultados nos mostraron que el detritus fino es el alimento más abundante para los invertebrados, y únicamente, Heterelmis mostró, después de la adición de nutrientes, diferencias significativas en el detritus fino y el material vegetal entre el tramo control y el impactado.
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[1] Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings (δ18Otr). Interannual variation in δ18Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ13C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ18Otr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18O-depleted rain in the region and seem to have affected the δ18Otr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ18Otr of M. acantholoba can be used as a proxy for source water δ18O and that interannual variation in δ18Oprec is caused by a regional amount effect. This contrasts with δ18O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in disentangling the processes influencing precipitation δ18O.
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Naturally occurring stable isotope ratios can be a powerful tool in studies of animal nutrition, provided that the assumptions required for dietary reconstruction are validated by studies such as the one presented here. The objective of this study was to document the magnitude of isotopic fractionation between swine diet and their different tissues. For this, the isotopic ratios of carbon and nitrogen of the diet and selected tissues (hair, nail, liver, muscle, fat and cartilage) were determined. The delta13C and delta15N of the diet were -15.9 and 1.3, respectively, and all delta15N of swine tissues were 2.2 to 3.0 enriched in 15N in relation to the diet. Little variation in delta15N occurred among tissues, with exception to liver that was less enriched in 15N than the nail. Nail and hair presented no 13C enrichment relative to diet. Cartilage was ~1.0 enriched in 13C as compared to diet. Liver and muscle were on average 2.1 more depleted in 13C in relation to diet as well as fat tissues. Some of the C and N isotope ratios of swine tissues differed in organs, but the isotopic fractionation trends among tissues appears to be similar to other mammals. Therefore our data provide a good baseline to interpret stable isotope patterns in domestic mammals (such as swine) in controlled or semi-controlled experiments.
O uso da abundância natural de isótopos estáveis pode ser uma ferramenta útil em estudos de nutrição animal, de forma que a base necessária para a reconstrução da dieta alimentar pode ser validada a partir de estudos como o apresentado aqui. O objetivo deste estudo foi documentar a magnitude do fracionamento isotópico entre a dieta e os tecidos de porcos domésticos. Para tanto, foram determinadas as razões isotópicas de carbono e nitrogênio de alguns tecidos selecionados (pêlo, unha, fígado, músculo, gordura e cartilagem). Os valores de delta13C e delta15N da ração fornecida foram -15,9 e 1,3, respectivamente. O delta15N desses tecidos ficou entre 2,2 e 3,0 mais enriquecido do que a dieta. Pouca variação no delta15N ocorreu entre os tecidos analisados, exceto o fígado que foi significativamente menos enriquecido em 15N do que a unha. A unha e o pêlo não apresentaram enriquecimento em 13C em relação à ração, enquanto a cartilagem ficou ~1 mais enriquecida. Os tecidos de fígado e músculo foram, em média, 2,1 mais leve em 13C em relação à dieta, assim como o tecido adiposo. Várias das razões isotópicas dos tecidos dos porcos diferiram, mas as tendências no fracionamento isotópico entre os tecidos foram similares ao encontrado em outros mamíferos. Portanto as diferenças encontradas no fracionamento isotópico podem servir de base para a interpretação de padrões isotópicos em animais domésticos oriundos de experimentos controlados ou semi-controlados.
RESUMO
Naturally occurring stable isotope ratios can be a powerful tool in studies of animal nutrition, provided that the assumptions required for dietary reconstruction are validated by studies such as the one presented here. The objective of this study was to document the magnitude of isotopic fractionation between swine diet and their different tissues. For this, the isotopic ratios of carbon and nitrogen of the diet and selected tissues (hair, nail, liver, muscle, fat and cartilage) were determined. The delta13C and delta15N of the diet were -15.9 and 1.3, respectively, and all delta15N of swine tissues were 2.2 to 3.0 enriched in 15N in relation to the diet. Little variation in delta15N occurred among tissues, with exception to liver that was less enriched in 15N than the nail. Nail and hair presented no 13C enrichment relative to diet. Cartilage was ~1.0 enriched in 13C as compared to diet. Liver and muscle were on average 2.1 more depleted in 13C in relation to diet as well as fat tissues. Some of the C and N isotope ratios of swine tissues differed in organs, but the isotopic fractionation trends among tissues appears to be similar to other mammals. Therefore our data provide a good baseline to interpret stable isotope patterns in domestic mammals (such as swine) in controlled or semi-controlled experiments.
O uso da abundância natural de isótopos estáveis pode ser uma ferramenta útil em estudos de nutrição animal, de forma que a base necessária para a reconstrução da dieta alimentar pode ser validada a partir de estudos como o apresentado aqui. O objetivo deste estudo foi documentar a magnitude do fracionamento isotópico entre a dieta e os tecidos de porcos domésticos. Para tanto, foram determinadas as razões isotópicas de carbono e nitrogênio de alguns tecidos selecionados (pêlo, unha, fígado, músculo, gordura e cartilagem). Os valores de delta13C e delta15N da ração fornecida foram -15,9 e 1,3, respectivamente. O delta15N desses tecidos ficou entre 2,2 e 3,0 mais enriquecido do que a dieta. Pouca variação no delta15N ocorreu entre os tecidos analisados, exceto o fígado que foi significativamente menos enriquecido em 15N do que a unha. A unha e o pêlo não apresentaram enriquecimento em 13C em relação à ração, enquanto a cartilagem ficou ~1 mais enriquecida. Os tecidos de fígado e músculo foram, em média, 2,1 mais leve em 13C em relação à dieta, assim como o tecido adiposo. Várias das razões isotópicas dos tecidos dos porcos diferiram, mas as tendências no fracionamento isotópico entre os tecidos foram similares ao encontrado em outros mamíferos. Portanto as diferenças encontradas no fracionamento isotópico podem servir de base para a interpretação de padrões isotópicos em animais domésticos oriundos de experimentos controlados ou semi-controlados.
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Using determinations of overnigh changes in tissue titratable acidity and of tissue stable carbon isotope ratios, 10 species of terrestrial succulents were investigatedin situ in southeastern Jamaica for the presence of Crassulacean acid metabolism (CAM). Eight of the 10 species exhibited CAM (sensu lato), confirming past reports of CAM inClusia flava (Clusiaceae),Bryophyllum pinnatum (Crassulaceae),Euphorbia tirucalli (Euphorbiaceae), andPedilanthus tithymaloides (Euphorbiaceae) and extending the number of species with CAM in two genera previously known to contain CAM species (Agave sobolifera [Agavaceae] andSansevieria metalllica [Liliaceae]). Stems of bothE. tirucalli andP. tithymaloides exhibited CAM while the leaves of both species were intermediate with regard to photosynthetic pathway. The lack of CAM acid fluctuations inTalinum paniculatum (Portulacaceae) was surprising given past findings with all other species investigated in this genus. Shoots ofPilea microphylla (Urticaceae) were C3 yet were remarkable in their extremely high pH. Both species require further investigation. Nocturnal acid accumulations indicative of CAM were found inTripogandra multiflora andCallisia fragrans, both members of the Commelinaceae. This represents the first report of CAM (probably "CAM-cycling") in this family.
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The gas exchange and water relations of the hemiparasite Pthirusa maritima and two its mangrove host species, Conocarpus erectus and Coccoloba uvifera, were studied in an intertidal zone of the Venezuelan coast. Carbon uptake and transpiration, leaf osmotic and total water potential, as well as nutrient content in the xylem sap and leaves of mistletoes and hosts were followed through the dry and wet season. In addition, carbon isotope ratios of leaf tissue were measured to further evaluate water use efficiency. Under similar light and humidity conditions, mistletoes had higher transpiration rates, lower leaf water potentials, and lower water use efficiencies than their hosts. Potassium content was much higher in mistletoes than in host leaves, but mineral nutrient content in the xylem sap of mistletoes was relatively low. The resistance of the liquid pathway from the soil to the leaf surface of mistletoes was larger than the total liquid flow resistance of host plants. Differences in the daily cycles of osmotic potential of the xylem sap also indicate the existence of a high resistance pathway along the vascular connection between the parasite pathway along the vascular connection between the parasite and its host. P. maritima mistletoes adjust to the different physiological characteristics of the host species which it parasitizes, thus ensuring an adequate water and carbon balance.