RESUMO
This study analyzes the distribution of nine potentially toxic trace elements (arsenic, antimony, bromine, cobalt, chromium, mercury, rubidium, selenium, and zinc) in sediments and plankton from two small mesotrophic lakes in a non-industrialized area impacted by the Caviahue-Copahue volcanic complex (CCVC). The two lakes have different plankton community structures and received different amounts of pyroclastic material after the last CCVC eruption. Trace element concentrations of surface sediments differed between lakes, according to the composition of the volcanic ashes deposited in the lakes. The size of organisms was the principal factor influencing the accumulation of most trace elements in plankton within each lake, being trace element concentrations generally higher in the microplankton than in the mesozooplankton. The planktonic biomass in the shallower lake was dominated by small algae and copepods, while mixotrophic ciliates and different-sized cladocerans dominated the deeper lake. These differences in the community structure and species composition influenced the trace element bioaccumulation, especially in microplankton, while habitat use and feeding strategies seem more relevant in mesozooplankton bioaccumulation. This work contributes to the scarce records of trace elements and their dynamics in plankton from freshwater ecosystems impacted by volcanic activity.
Assuntos
Plâncton , Oligoelementos , Plâncton/química , Lagos/química , Ecossistema , Argentina , Altitude , Monitoramento AmbientalRESUMO
On a global scale, cetaceans are recognized well indicators of marine ecosystem health. Trace elements accumulate in their bodies and potentially constitute a toxicological threat. Here, the concentrations of essential Se; unknown physiological elements Br, Rb, Cs, Ni, and Sr; and pollutants arsenic, Cd, Hg, and Ag were assessed in the skin of false killer whales (Pseudorca crassidens) stranded at Estrecho de Magallanes, South America, and next, tissue comparisons and relationships between elemental concentrations in the skin and internal tissues (liver, kidney, spleen, lung, skeletal muscle, and testis) were assessed. Results showed elemental concentration variations among tissues. Selenium concentration was found to be higher in the liver 398 (75) µg g-1 dry weight (DW) (standard deviation in parenthesis), followed by skin. Rubidium and Br concentrations were higher in testis 7.92 (0.42) and 99.1 (5.4) µg g-1 DW, respectively, and Cs in muscle 0.36 (0.12) µg g-1 DW, while Ni concentrations range (<0.05-0.91 µg g-1 DW) did not show differences among tissues. Cadmium and arsenic were found to be higher in kidneys, 71.2 (17.6) and 2.54 (1.77) µg g-1 DW, respectively, while Hg was highest in the liver 1068 (234) µg g-1 DW. Concerning inter-tissue relationships, a positive skin-to-kidney and skin-to-muscle correlations were observed for Cs concentrations, and also Hg showed positive skin-to-spleen, skin-to-kidney, and skin-to-testis correlations, which support its use as potential offshore marine biomonitor.
Assuntos
Golfinhos , Oligoelementos , Poluentes Químicos da Água , Animais , Ecossistema , Biomarcadores Ambientais , Monitoramento Ambiental , Fígado/química , Masculino , América do Sul , Oligoelementos/análise , Poluentes Químicos da Água/análiseRESUMO
Silver (Ag) is a non-essential metal known to bioaccumulate in aquatic organisms. We determined Ag concentrations in five false killer whales stranded in South America. Silver concentrations (in dry weight basis) range as 6.62-10.78⯵gâ¯g-1 in liver, 0.008-7.41⯵gâ¯g-1 in spleen, 0.004-5.71⯵gâ¯g-1 in testis, 0.757-1.69⯵gâ¯g-1 in kidney, 0.011-0.078⯵gâ¯g-1 in lung andâ¯<â¯0.01-0.038⯵gâ¯g-1 in muscle, whereas in the single samples of uterus and ovary were 0.051 and 0.023⯵gâ¯g-1; respectively. Overall, Ag concentration in liver and kidney exceeded the cetacean toxic thresholds, proposed as "unhealthy concentrations" and "critically dangerous" in liver and kidney. These results warrant further eco-toxicological studies, to examine biological effects of elevated silver levels for individuals and to assess the species' conservation status with respect to marine pollution.
Assuntos
Golfinhos , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Feminino , Rim/química , Fígado/química , Masculino , Ovário/química , Prata/análise , América do Sul , Testículo/química , Poluentes Químicos da Água/análiseRESUMO
Andean Patagonian lakes are oligotrophic systems characterized by low dissolved organic carbon (DOC) levels and moderate to high Hg concentration that determine naturally high Hg/DOC ratios and bioavailability. In these lakes, microbial food webs are extremely important in Hg trophodynamics, being that the picophytoplankton fraction is a major entrance path of Hg2+ into pelagic food webs. This study analyzed the bioaccumulation of Hg2+ by the picocyanobacteria Synechococcus sp. using the radiotracer 197Hg2+ and water from four Andean Patagonian lakes presenting a natural gradient of DOM concentration and quality. Hg2+ bioaccumulation by Synechococcus was calculated as the uptake of Hg2+ per biovolume unit (volume concentration factor VCF; pL µm-3). Hg uptake showed a wide variation (13â¯<â¯VCF< 300â¯pL⯵m-3) in the natural DOC gradient tested (0.7-4â¯mgâ¯L-1; Hg2+/DOC ratio: 1.8-14â¯ngâ¯mg-1). The bioaccumulation of Hg2+ in Synechococcus decreased exponentially with DOC concentration. Differences in the quality of dissolved organic matter (DOM) among lake water influenced also Hg2+ bioaccumulation. Naturally degraded DOM, with low molecular weight/size, promoted higher Hg uptakes in Synechococcus compared to humic DOM, rich in high molecular weight/size aromatic compounds, that retained Hg in the dissolved phase. In Andean Patagonian lakes picocyanobacteria are pivotal organisms in the Hg cycling, taking dissolved Hg2+ and transferring it to pelagic food webs, as well as fueling the benthic Hg pathway through sedimentation.
Assuntos
Monitoramento Ambiental/métodos , Substâncias Húmicas/análise , Lagos/química , Mercúrio/análise , Synechococcus/metabolismo , Poluentes Químicos da Água/análise , Argentina , Cadeia Alimentar , Lagos/microbiologia , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismoRESUMO
Zinc (Zn) bioaccumulation and trophic transfer were analyzed in the food web of Lake Nahuel Huapi, a deep, unpolluted ultraoligotrophic system in North Patagonia. Benthic macroinvertebrates, plankton, and native and introduced fish were collected at three sites. The effect of pyroclastic inputs on Zn levels in lacustrine food webs was assessed by studying the impact of the eruption of Puyehue-Cordón Caulle volcanic complex (PCCVC) in 2011, by performing three sampling campaigns immediately before and after the PCCVC eruption, and after 2 years of recovery of the ecosystem. Zinc trophodynamics in L. Nahuel Huapi food web was assessed using nitrogen stable isotopes (δ15N). There was no significant increase of Zn concentrations ([Zn]) in L. Nahuel Huapi biota after the PCCVC eruption, despite the evidence of [Zn] increase in lake water that could be associated with volcanic ash leaching. The organisms studied exhibited [Zn] above the threshold level considered for dietary deficiency, regulating Zn adequately even under a catastrophic situations like PCCVC 2011 eruption. Zinc concentrations exhibited a biodilution pattern in the lake's food web. To the best of our knowledge, present research is the first report of Zn biodilution in lacustrine systems, and the first to study Zn transfer in a freshwater food web including both pelagic and benthic compartments.
Assuntos
Organismos Aquáticos/metabolismo , Exposição Ambiental/análise , Cadeia Alimentar , Erupções Vulcânicas , Poluentes Químicos da Água/metabolismo , Zinco/metabolismo , Animais , Argentina , Monitoramento Ambiental , Peixes/metabolismo , Invertebrados/metabolismo , Lagos , Plâncton/metabolismoRESUMO
Microbial assemblages are typical of deep ultraoligotrophic Andean Patagonian lakes and comprise picoplankton and protists (phytoflagellates and mixotrophic ciliates), having a central role in the C cycle, primary production and in the incorporation of dissolved inorganic mercury (Hg2+) into lake food webs. In this study we evaluated the mechanisms of Hg2+ incorporation in hetero- and autotrophic bacteria, in the autotrophic dinoflagellate (Gymnodinium paradoxum) and in two mixotrophic ciliates (Stentor araucanus and Ophrydium naumanni) dominating the planktonic microbial assemblage. The radioisotope 197Hg was used to trace the Hg2+ incorporation in microbiota. Hg uptake was analyzed as a function of cell abundance (BCF: bioconcentration factor), cell surface (SCF: surface concentration factor) and cell volume (VCF: volume concentration factor). Overall, the results obtained showed that these organisms incorporate substantial amounts of dissolved Hg2+ passively (adsorption) and actively (bacteria consumption or attachment), displaying different Hg internalization and therefore, varying potential for Hg transfer. Surface area and quality, and surface:volume ratio (S:V) control the passive uptake in all the organisms. Active incorporation depends on bacteria consumption in the mixotrophic ciliates, or on bacteria association to surface in the autotrophic dinoflagellate. Hg bioaccumulated by pelagic protists can be transferred to higher trophic levels through plankton and fish feeding, regenerated to the dissolved phase by excretion, and/or transferred to the sediments by particle sinking. In ultraoligotrophic Andean Patagonian lakes, picoplankton and planktonic protists are key components of lake food webs, linking the pelagic and benthic Hg pathways, and thereby playing a central role in Hg trophodynamics.
Assuntos
Cilióforos/metabolismo , Dinoflagellida/metabolismo , Lagos/química , Compostos de Mercúrio/análise , Plâncton/metabolismo , Poluentes Químicos da Água/análise , Animais , Argentina , Peixes/metabolismo , Cadeia Alimentar , Compostos de Mercúrio/metabolismo , Modelos Teóricos , Poluentes Químicos da Água/metabolismoRESUMO
Lake Nahuel Huapi (NH) is a large, ultraoligotrophic deep system located in Nahuel Huapi National Park (NHNP) and collecting a major headwater network of Northwestern Patagonia (Argentina). Brazo Rincón (BR), the westernmost branch of NH, is close to the active volcanic formation Puyehue-Cordón Caulle. In BR, aquatic biota and sediments display high levels of total Hg (THg), ranging in contamination levels although it is an unpolluted region. In this survey, Hg species and fractionation were assessed in association with dissolved organic matter (DOM) in several aquatic systems draining to BR. THg varied between 16.8 and 363â¯ngâ¯L-1, with inorganic Hg (Hg2+) contributing up to 99.8% and methyl mercury (MeHg) up to 2.10%. DOC levels were low (0.31-1.02â¯mgâ¯L-1) resulting in high THg:DOC and reflecting in high Hg2+ availability for binding particles (partitioning coefficient log Kd up to 6.03). In streams, Hg fractionation and speciation related directly with DOM terrestrial prints, indicating coupled Hg-DOM inputs from the catchment. In the lake, DOM quality and photochemical and biological processing drive Hg fractionation, speciation and vertical levels. Dissolved gaseous Hg (Hg0) reached higher values in BR (up to 3.8%), particularly in upper lake layers where solar radiation enhances the photoreduction of Hg2+ and Hg-DOM complexes. The environmental conditions in BR catchment promote Hg2+ binding to abiotic particles and bioaccumulation and the production of Hg0, features enhancing Hg mobilization among ecosystem compartments. Overall, the aquatic network studied can be considered a "natural Hg hotspot" within NHNP.
Assuntos
Sedimentos Geológicos/química , Lagos/química , Mercúrio/análise , Compostos de Metilmercúrio/análise , Rios/química , Poluentes Químicos da Água/análise , Argentina , Ecossistema , Erupções Vulcânicas/análiseRESUMO
Niche segregation between introduced and native fish in Lake Nahuel Huapi, a deep oligotrophic lake in Northwest Patagonia (Argentina), occurs through the consumption of different prey. Therefore, in this work we analyzed total mercury [THg] and methylmercury [MeHg] concentrations in top predator fish and in their main prey to test whether their feeding habits influence [Hg]. Results indicate that [THg] and [MeHg] varied by foraging habitat and they increased with greater percentage of benthic diet and decreased with pelagic diet in Lake Nahuel Huapi. This is consistent with the fact that the native creole perch, a mostly benthivorous feeder, which shares the highest trophic level of the food web with introduced salmonids, had higher [THg] and [MeHg] than the more pelagic feeder rainbow trout and bentho-pelagic feeder brown trout. This differential THg and MeHg bioaccumulation observed in native and introduced fish provides evidence to the hypothesis that there are two main Hg transfer pathways from the base of the food web to top predators: a pelagic pathway where Hg is transferred from water, through plankton (with Hg in inorganic species mostly), forage fish to salmonids, and a benthic pathway, as Hg is transferred from the sediments (where Hg methylation occurs mostly), through crayfish (with higher [MeHg] than plankton), to native fish, leading to one fold higher [Hg].
Assuntos
Peixes , Cadeia Alimentar , Lagos/química , Mercúrio/análise , Compostos de Metilmercúrio/análise , Poluentes Químicos da Água/análise , Animais , Argentina , Monitoramento AmbientalRESUMO
At the beginning of the 21st century, digital imaging technology replaced the traditional silver-halide film photography which had implications in Ag contamination. Lake Nahuel Huapi is a popular Patagonia tourist destination impacted by municipal silver (Ag) contamination from photographic processing facilities since 1990's. Silver concentrations in a dated sediment core from the lake bottom showed a 10-fold increase above background levels in the second half of the 20th century, then a decrease. This trend corresponds well with published annual global photography industry demand for Ag, which clearly shows the evolution and replacement of the traditional silver-halide film photography by digital imaging technology. There were significant decreases in Ag concentrations in sediments, mussels and fish across the lake between 1998 and 2011. Lower trophic organisms had variable whole-body Ag concentrations, from 0.2-2.6 µg g-1 dry weight (DW) in plankton to 0.02-3.1 µg g-1 DW in benthic macroinvertebrates. Hepatic Ag concentrations in crayfish, mussels and predatory fish were significantly elevated relative to muscle which often have Ag concentrations below the detection limit (0.01-0.05 µg g-1 DW). Trophodynamic analyses using δ15N and whole-body invertebrate and muscle Ag concentrations indicated food web biodilution trends. High sedimentation rates in conjunction with the reduction of silver waste products discharged to the lake, as a result of the change to digital image processing technologies, are resulting in unplanned but welcome remediation of the Ag contamination in Lake Nahuel Huapi.
Assuntos
Monitoramento Ambiental , Resíduos Industriais/análise , Lagos/química , Fotografação/métodos , Prata/análise , Poluentes Químicos da Água/análise , Animais , Organismos Aquáticos/química , Argentina , Biodegradação Ambiental , Peixes/metabolismo , Cadeia Alimentar , Sedimentos Geológicos/química , Invertebrados/química , Tamanho da Partícula , Plâncton/químicaRESUMO
Despite located far from point sources of Hg pollution, high concentrations were recorded in plankton from the deep oligotrophic Lake Nahuel Huapi, located in North Patagonia. Native and introduced top predator fish with differing feeding habits are a valuable economic resource to the region. Hence, Hg and Se trophic interactions and pathways to these fish were assessed in the food web of this lake at three sites, using stable nitrogen and carbon isotopes. As expected based on the high THg in plankton, mercury did not biomagnify in the food web of Lake Nahuel Huapi, as most of the THg in plankton is in the inorganic form. As was observed in other aquatic systems, Se did not biomagnify either. When trophic pathways to top predator fish were analyzed, they showed that THg biomagnified in the food chains of native fish but biodiluted in the food chains of introduced salmonids. A more benthic diet, typical of native fish, resulted in higher [THg] bioaccumulation than a more pelagic or mixed diet, as in the case of introduced fish. Se:THg molar ratios were higher than 1 in all the fish species, indicating that Se might be offering a natural protection against Hg toxicity.
Assuntos
Monitoramento Ambiental , Cadeia Alimentar , Lagos/química , Mercúrio/análise , Selênio/análise , Poluentes Químicos da Água/análise , Animais , Argentina , Isótopos de Carbono/química , Peixes , Mercúrio/química , Isótopos de Nitrogênio/química , Plâncton , Selênio/química , Poluentes Químicos da Água/químicaRESUMO
Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.
Assuntos
Organismos Aquáticos/química , Metais Pesados/análise , Folhas de Planta/química , Salix/química , Oligoelementos/análise , Argentina , Ecossistema , Monitoramento Ambiental , Lagos , Mercúrio/análise , Árvores/químicaRESUMO
The Commerson's dolphin is the most common endemic odontocete of subantarctic waters of Tierra del Fuego, Argentina incidentally caught in fishing nets. The species is classified as "Data Deficient" by the IUCN. Metallothioneins (MTs) are considered as suitable biomarkers for health and environmental monitoring. The aims of the study were to assess MT concentrations in the liver and kidney of bycaught specimens. Moreover, correlations with Zn, Se, Cd, Ag and Hg, and the molar ratios of MT:metals were estimated to evaluate if there is an indication of their respective protective role against metal toxicity in tissues. Hepatic and renal MT concentrations were similar, ranging from 11.6 to 29.1nmol·g(-1) WW, and Kidney/Liver ratios ranging from 0.73 to 1.93 corresponded to normal ranges. Results suggest that MTs are related to physiological ranges for the species. This information constitutes the first MT report on Commerson's dolphins and possibly considered as baseline for species' conservation.
Assuntos
Golfinhos/metabolismo , Monitoramento Ambiental/métodos , Rim/química , Rim/metabolismo , Fígado/química , Metalotioneína/metabolismo , Animais , Argentina , Oceano Atlântico , Golfinhos/fisiologia , Feminino , Fígado/metabolismo , Masculino , Metais Pesados/análise , Poluentes Químicos da Água/análiseRESUMO
The skin of bycaught Commerson's dolphins was tested for mercury (Hg) and selenium (Se) biomonitoring in Subantarctic environments. The correlation of levels detected in the skin with those found in internal tissues - lung, liver, kidney and muscle - was assessed to evaluate how skin represents internal Hg and Se distribution for monitoring purposes. Mercury in skin had a concentration range of 0.68-3.11 µg g(-1) dry weight (DW), while Se had a higher concentration range of 74.3-124.5 µg g(-1) DW. There was no significant correlation between selenium levels in any of the analyzed tissues. Thus, the skin selenium concentration did not reflect the tissular Se levels and did not provide information for biomonitoring. The lack of correlation is explained by the biological role of Se, provided that each tissue regulates Se levels according to physiological needs. However, the skin Hg level had significant positive correlation with the levels in internal tissues (ANOVA p<0.05), particularly with that of muscle (R(2)=0.79; ANOVA p=0.0008). Thus, this correlation permits the estimation of Hg content in muscle based on the multiplication of skin biopsy levels by a factor of 1.85. Mercury bioindication using skin biopsies is a non-lethal approach that allows screening of a large number of specimens with little disturbance and makes possible an adequate sampling strategy that produces statistically valid results in populations and study areas. The correlation between Hg levels in the skin and internal tissues supports the use of the epidermis of Commerson's dolphins for Hg biomonitoring in the waters of the Subantarctic, which is a poorly studied region regarding Hg levels, sources and processes.
Assuntos
Golfinhos/metabolismo , Monitoramento Ambiental/métodos , Mercúrio/análise , Selênio/análise , Pele/química , Poluentes Químicos da Água/análise , Animais , Argentina , Rim/química , Fígado/química , Mercúrio/farmacocinética , Músculos/química , Selênio/farmacocinética , Distribuição Tecidual , Poluentes Químicos da Água/farmacocinéticaRESUMO
Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, [Formula: see text]), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m(-3), that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m(-3)) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m(-3). We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au-Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical-chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Mercúrio/análise , China , Cidades , Coleta de Dados , Europa (Continente) , Mineração , África do Sul , América do Sul , Erupções VulcânicasRESUMO
Food web trophodynamics of total mercury (THg) and selenium (Se) were assessed for the double-basined ultraoligotrophic system of Lake Moreno, Patagonia. Each basin has differing proportions of littoral and pelagic habitats, thereby providing an opportunity to assess the importance of habitat (e.g. food web structure or benthic MeHg production) in the transfer of Hg and Se to top trophic fish species. Pelagic plankton, analyzed in three size classes (10-53, 53-200, and >200 µm), had very high [THg], exceeding 200 µg g(-1) dry weight (DW) in the smallest, and a low ratio of MeHg to THg (0.1 to 3%). In contrast, [THg] in littoral macroinvertebrates showed lower values (0.3 to 1.8 µg g(-1) DW). Juvenile and small fish species feeding upon plankton had higher [THg] (0.2 to 8 µg g(-1) muscle DW) compared to large piscivore fish species (0.1 to 1.6 µg g(-1) muscle DW). Selenium concentrations exhibited a much narrower variation range than THg in the food web, varying from 0.5 to 2.7 µg g(-1) DW. Molar Se:Hg ratios exceeded 1 for the majority of organisms in both basins, with most ratios exceeding 10. Using stable nitrogen isotopes as indicator of trophic level, no significant correlations were found with [THg], [Se] or Se:Hg. The apparent lack of biomagnification trends was attributed to elevated [THg] in plankton in the inorganic form mostly, as well as the possibility of consistent Se supply reducing the biomagnification in the food web of the organic portion of THg.
Assuntos
Cadeia Alimentar , Mercúrio/metabolismo , Selênio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Organismos Aquáticos/metabolismo , Argentina , Isótopos de Carbono/metabolismo , Monitoramento Ambiental , Lagos , Espectrometria de Massas , Análise de Ativação de Nêutrons , Isótopos de Nitrogênio/metabolismoRESUMO
A survey of the elemental contents of K, Mg, Mn, Na, Cl, Br, Cs, Co, Rb, Fe, Zn, Al, Ti, V, As, Ag, Au and Cd in liver, kidney and muscle was performed in specimens of Commerson's dolphins (Cephalorhynchus c. commersonii) from subantarctic waters. The concentrations were determined by Instrumental Neutron Activation Analysis and the specimens derives from animals incidentally caught in artisanal fishing nets. Liver had the highest concentrations of Fe, 897(79) µg g(-1) DW (dry weight) (average; standard deviation in parenthesis), kidney had the highest Cd, 35 (24) µg g(-1) DW; Cl, 9,200 (1,700) µg g(-1) DW; Na, 6,800 (1,100) µg g(-1) DW and Br, 73(12) µg g(-1) DW; and muscle the highest Mg 954 (71) µg g(-1) DW. Potassium and Cs concentrations in muscle and kidney ranged in 12,510-13,020 and 0.230-0.252 µg g(-1) DW, respectively; Zn and Mn concentrations were similar in liver and kidney (117-122.1 and 3.66-16.5 µg g(-1) DW, respectively). Silver was high in liver 5.4(5.0) µg g(-1) DW and kidney 1.2(2.7) µg g(-1) DW. Gold, Rb, Co and As had no differences among tissues. Likewise, as in other odontocete species, the concentrations of essential elements showed little variation between the specimens analyzed, since they are regulated biochemically; however, heavy metals showed high variability. This study constitutes the first large description of the elemental composition in Commerson's dolphins from subantarctic waters of the South Atlantic Ocean.
Assuntos
Golfinhos/metabolismo , Metais Pesados/metabolismo , Oligoelementos/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Oceano Atlântico , Monitoramento Ambiental , Feminino , Rim/metabolismo , Fígado/metabolismo , Masculino , Metais Pesados/análise , Músculos/metabolismo , Análise de Ativação de Nêutrons , Oligoelementos/análise , Poluentes Químicos da Água/análiseRESUMO
We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Patagonia (Argentina) through the seasonal analysis of two pelagic allochthonous indicators: i) water color, as a proxy of allochthonous dissolved organic matter in lakes; and ii) the color to chlorophyll a ratio (Color:Chla), as an indicator of the relationship between allochthonous and autochthonous carbon pools. We also evaluated the potential transfer pathways of the allochthonous dissolved organic matter into the pelagic food webs of these deep lakes, including the natural zooplankton δ(13)C in the analysis. The dynamics of the allochthonous indicators were related to the precipitation regime, water level fluctuations, and hydrogeomorphic and catchment features of lakes Moreno East and Moreno West. The water color (absorbance at 440 nm) was extremely low (<0.28 m(-1)) in both lakes regardless of the season. However, precipitation and snowmelt regimes drove the increase and decrease of water color, respectively. A significant positive relationship between the zooplankton bulk δ(13)C with the water color would suggest an input of allochthonous organic carbon into the pelagic consumers. The incorporation of the dissolved allochthonous material into higher trophic levels is likely favored by the bacterivorous behavior of planktonic organisms, mixotrophic flagellates and ciliates, which dominate the pelagic food webs of these Patagonian lakes. Morphometric aspects, mainly the higher water residence time, led to lower values of allochthony in Moreno East compared to Moreno West, probably accentuated by its upper position in the lake chain. Overall, our results suggest that these allochthonous signals can bring insight into the magnitude of the interaction between terrestrial environments and lake ecosystems, even in extremely clear and ultraoligotrophic systems, such as the Andean Patagonian lakes.
Assuntos
Clorofila/análise , Meio Ambiente , Cadeia Alimentar , Lagos/química , Animais , Argentina , Isótopos de Carbono/análise , Clorofila A , Compostos Orgânicos/análise , Chuva , Estações do Ano , Neve , Zooplâncton/metabolismoRESUMO
PURPOSE: The differential ability of apple snail tissues, endosymbionts, and eggs to bioaccumulate several metals (Sb, As, Ba, Br, Zn, Cr, Fe, Hg, Se, and U) was investigated. METHODS: Metal concentrations were determined by neutron activation analysis in several tissues, endosymbionts, and eggs from mature apple snails cultured in either drinking water or reconstituted water (prepared with American Society for Testing and Materials type I water). RESULTS: The highest bioconcentration factors (BCFs) in the midgut gland were found for Ba, Zn, Se, As, U, Br, and Hg (in decreasing order), while the highest in the kidney were for Ba, Br, and Hg. The foot showed the highest BCFs for Ba, Hg, Br, and Se (in decreasing order). Calcified tissues (uterus, shell) and eggs showed low BCFs, except for Ba. Both C corpuscles and gland tissue showed statistically higher BCFs than K corpuscles for Ba, Fe, U, Br, and Sb. The concentration of most of the studied elements was significantly lower in tissues and endosymbionts obtained from snails cultured in reconstituted water instead of drinking water. Snails cultured in reconstituted water and then exposed or not to Hg, As, and U (at the maximum contaminant level allowed by the US Environmental Protection Agency) also resulted in high levels accumulated in midgut gland, endosymbionts and kidney. CONCLUSIONS: Our findings suggest that the midgut gland (and the symbionts contained therein), the kidney, and the foot of Pomacea canaliculata may be useful bioindicators of Hg, As and U pollution in freshwater bodies and that the unrestricted use of ampullariid snails as human and animal food must be considered with caution.
Assuntos
Água Potável/química , Metais Pesados/metabolismo , Caramujos/metabolismo , Urânio/metabolismo , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Animais , Feminino , Rim/química , Metais Pesados/análise , Análise de Ativação de Nêutrons , Urânio/análise , Poluentes Químicos da Água/análise , Qualidade da ÁguaRESUMO
Seasonal trends of benthic methylmercury (methyl-Hg) production were examined in both littoral and open water sites of three lakes (Escondido, Moreno, and Morenito) in the North Andean Patagonia region of Argentina. Potentials of methyl-Hg production were measured by amending sediment samples with inorganic (197)Hg(II), incubating for either 24 and 32 h at room temperature, and subsequently assaying the radiolabelled organomercury produced. Seasonal variations of benthic methyl-Hg production were studied but no significant correlation was observed. Lake littoral sites exhibited up to two fold higher methyl-Hg production potentials in most cases. Sediment from lakes Moreno and Morenito generally exhibited much lower (up to 10 fold) methyl-Hg production potentials than those from Lake Escondido, possibly due to differences in particulate and dissolved organic matter quantity and quality, which is higher in Lake Escondido and primarily allochthonous, whereas in lakes Moreno and Morenito is primarily autochthonous. This study represents the first to directly examine benthic microbial Hg(II)-methylation in aquatic ecosystems of Patagonia.
Assuntos
Ecossistema , Mercúrio/análise , Compostos de Metilmercúrio/análise , Poluentes do Solo/análise , Argentina , Monitoramento Ambiental , Sedimentos Geológicos/química , Radioisótopos de Mercúrio/química , Compostos de Metilmercúrio/química , Estações do Ano , Poluentes do Solo/químicaRESUMO
Well preserved volcanic ashes produced in recent events, recovered from sedimentary sequences extracted from three lakes belonging to Nahuel Huapi National Park, Northern Patagonia, were geochemically characterized in order to reveal patterns that allow the identification of the source. Two water bodies are situated in the direct impact area of volcanoes Calbuco and Puyehue-Cordón Caulle, while the third, lake Moreno, is situated in-between. The sedimentary sequences were dated by (210)Pb and (137)Cs techniques; the elemental composition was determined by Instrumental Neutron Activation Analysis. Distinctive patterns were found out when comparing glass shards, and also white pumice but in a lesser degree, of tephra layers extracted from lake Ilón, related mostly to volcano Calbuco events, and lake Nahuel Huapi (Brazo Rincón site), associated to Puyehue-Cordón Caulle eruptions. The geochemical parameters that showed decisive differences were SiO(2) and Na(2)O+K(2)O contents, the Eu anomaly, Rare Earth element ratios; the concentration of incompatible elements Cs, Rb, Th, Hf, Ta and Zr, and the compatible elements Cr and V. The six upper tephra layers extracted from lake Moreno showed geochemical patterns that allowed clear association with Calbuco and Puyehue-Cordón Caulle sources. These results set up the base for tephrochronological applications in historical periods in Nahuel Huapi National Park area.