Water Self-Dissociation is Insensitive to Nanoscale Environments.

Nanoconfinement effects on water dissociation and reactivity remain controversial, despite their importance to understand the aqueous chemistry at interfaces, pores, or aerosols. The pKw in confined environments has been assessed from experiments and simulations in a few specific cases, leading to dissimilar conclusions. Here, with the use of carefully designed ab initio simulations, we demonstrate that the energetics of bulk water dissociation is conserved intact to unexpectedly small length-scales, down to aggregates of only a dozen molecules or pores of widths below 2 nm. The reason is that most of the free-energy involved in water autoionization comes from breaking the O-H covalent bond, which has a comparable barrier in the bulk liquid, in a small droplet of nanometer size, or in a nanopore in the absence of strong interfacial interactions. Thus, dissociation free-energy profiles in nanoscopic aggregates or in 2D slabs of 1 nm width reproduce the behavior corresponding to the bulk liquid, regardless of whether the corresponding nanophase is delimited by a solid or a gas interface. The present work provides a definite and fundamental description of the mechanism and thermodynamics of water dissociation at different scales with broader implications on reactivity and self-ionization at the air-liquid interface.

Metal(oid)s content in High-Andean aquatic systems of the Atacama Desert, Chile: environmental assessment of extreme ecosystems.

The high-Andean mountain of northern Chile host numerous water systems that is in risk due to increased mining activities. Total and dissolved Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn in water, and Cd, Cu, Fe, Ni, Pb, Zn, As, Mo, Al, and V in sediments of 21 aquatic systems (rivers, saline lakes, salt flats), were studied. The presence of Pb, Cd, and As in waters and sediments could be explained, in part, by mining activities. Waters are not suitable for human consumption or irrigation due to high content of Cu and As and high pH that exceed Chilean water quality guideline values. The use of different background reference values influences noticeably the conclusion related to environmental quality of sediments, measured with different environmental indexes. The local geological background suggest that Cd, Mo, Pb, and As generate some degree of contamination, while the use of unpolluted systems as background suggest that all metals measured in sediments represent a low contamination risk. The use of background values of local unpolluted systems seems to be more realistic than geological formation or Upper Continental Crust reference values to assess the environmental condition. The ecological risk assessment suggests that Cd and As are threat for communities living in these aquatic environments. However, these systems support abundant wildlife, developing unique extreme ecosystems with great potential for non-consumptive use such as special interest tourism and conservation.

Characterization of ambient polychlorinated biphenyl background conditions in surface waters of the Pajarito Plateau, New Mexico.

This study presents the development of polychlorinated biphenyl (PCB) background threshold values (BTVs) that statistically characterize ambient background conditions for surface waters in undeveloped and developed landscapes of the Pajarito Plateau in the Rio Grande Basin of New Mexico. Between 2009 and 2018, surface water data were collected at 45 locations under a variety of flow conditions and regimes. A total of 163 samples were collected, with roughly 1/3 of samples and locations being in undeveloped areas (n = 53 from 17 locations), and the remainder being in developed areas (n = 110 from 28 locations). While there are areas on the Pajarito Plateau where PCB point sources are known or likely to have contributed to PCBs in soils, PCB BTVs calculated for undeveloped portions of watersheds (upstream of areas where PCB point sources are known or likely to have contributed to PCBs in soils, and therefore not affected by PCB sources within the watershed) are well above New Mexico's human health organism-only (HH-OO) water quality criterion (0.64 ng/L). Background threshold values are even higher in developed areas upstream of managed soil sites, suggesting that in developed areas, both diffuse ambient PCB sources (e.g., atmospheric deposition) and localized urban sources (e.g., building materials, paints, and electrical equipment) contribute to PCBs in those watersheds. These findings indicate that New Mexico's current HH-OO water quality criterion for PCBs cannot practicably be met due to ambient conditions. It is also impracticable to meet the US Environmental Protection Agency (EPA) criterion continuous concentration (CCC) of 14 ng/L in developed background areas, where the BTV is approximately 1.5 times the CCC. Integr Environ Assess Manag 2023;19:1307-1319. © 2022 SETAC.

Concentration of essential and toxic elements as a function of the depth of the soil and the presence of fulvic acids in a wetland in Cerrado, Brazil.

The protection of wetlands is essential for sustainable development. The particular hydrology of wetlands creates conditions for the formation of hydric soils. Hydric soils are formed in oxide-reducing environments and perform important removal and re-oxidation of Fe and Mn oxides and hydroxides. They are also characterized by the formation of a superficial horizon enriched by the accumulation of organic matter. The objective of this study was to determine the concentration of essential (Co, Cu, Fe, Mn, Ni, Zn) and toxic (Al, Cd, Pb) elements in the soil solution in a wetland, surrounded by an intense agricultural activity area. The concentrations of the elements were evaluated according to the level of hydromorphy (border to the center) and the depth of the soil. The physical fractionation of these elements was also assessed (total and < 30 kDa), and the results were compared with the chemical speciation of these elements. Despite the high total concentrations of Al and Fe, the concentration of these elements was very low in the < 30 kDa fraction, which suggests that these elements are complexed with organic matter, in the form of hydroxides. Evidence of removal of Fe and Mn from the surface horizon was observed at the center of the wetland, where the highest level of hydromorphy is found. The results showed that the concentration of metals in the fraction < 30 kDa is insignificant, suggesting that the mechanisms of precipitation and/or adsorption to soil colloids play an important role in the regulation of this ecosystem.

Photochemistry in Real Space: Batho- and Hypsochromism in the Water Dimer.

The development of chemical intuition in photochemistry faces several difficulties that result from the inadequacy of the one-particle picture, the Born-Oppenheimer approximation, and other basic ideas used to build models. It is shown herein how real-space approaches can be efficiently used to gain valuable insights in photochemistry through a simple example of red and blue shift effects: the double hypso- and bathochromic shifts in the low-lying valence excited states of (H2 O)2 . It is demonstrated that 1) the use of these techniques allows the perturbative language used in the theory of intermolecular interactions, even in the strongly interacting short-range regime, to be maintained; 2) one and only one molecule is photoexcited in each of the addressed excited states and 3) the electrostatic interaction between the in-the-cluster molecular dipoles provides a fairly intuitive rationalisation of the observed batho- and hypsochromism. The methods exploited and illustrated herein are able to maintain the individuality and properties of the interacting entities in a molecular aggregate, and thereby they allow chemical intuition in general states, at any geometry and using a broad variety of electronic structure methods to be kept and built.

Data set of dissolved major and trace elements from the lacustrine systems of Clearwater Mesa, Antarctica.

This article presents analytical observations on physicochemical parameters and major and trace element concentrations of water, ice, and sediment samples from the lake systems of Clearwater Mesa (CWM), northeast Antarctic Peninsula. Geochemical analyses include inductively coupled plasma mass spectrometry (ICP-MS) for cations and trace elements and ion chromatography for anions. Some figures are included (i.e. Piper and Gibbs diagrams) which indicate water classification type and rock-water interactions in CWM, respectively. It also contains PHREEQC software output, listing the chemical speciation for dissolved elements, Saturation Indexes (SI), and modelling outputs. Each lake SI are also illustrated in a figure. Finally, total organic and inorganic carbon (TOC and TIC, respectively) were determined for bottom lake sediments and marginal salt samples. This information will be useful for future research assessing the impacts of anthropogenic pollution and the effects of climate change, providing insights into naturally occurring geochemical processes in a pristine environment, and evaluating geochemical behaviour of dissolved elements in high-latitude hydrological systems. These data correspond to the research article "Dissolved major and trace geochemical dynamics in Antarctic Lacustrine Systems" [1].

First record of a freshwater bryozoan species in Cuba: Plumatella repens (Linnaeus, 1758) (Phylactolaemata, Bryozoa).

The discovery of Plumatella repens floatoblasts in wetlands of the La Niña Bonita Reservoir and the Ciénaga de Zapata Swamp, Cuba, constitutes the first record of a freshwater bryozoan species on the island and extends the distribution range of the species in the insular Caribbean. Unlike the inland waters of the Lesser Antilles the greater availability of water and lower salinity are likely the main factors that determine the distribution of P. repens in the Greater Antilles.

Can nesting waterbirds influence the community structure of macroinvertebrates in southern Brazilian intermittent wetlands? / Podem as colônias de nidificação de aves aquáticas influenciar a estrutura da comunidade de macroinvertebrados em áreas úmidas intermitentes do sul do Brasil?

The main goal of this study was to test the effect of the presence of nesting waterbirds on the taxonomic structure (richness, abundance and composition) of macroinvertebrate communities in southern Brazilian wetlands. Macroinvertebrate communities were seasonally sampled in eight intermittent wetlands differing according to the occurrence of nesting colonies of waterbirds (four with the presence of rookeries; four without). The influence of nutrients and water and sediment physicochemical variables on macroinvertebrate communities was also assessed. The community structure of aquatic macroinvertebrates was not affected by the presence of colonies of nesting waterbirds. Rather, macroinvertebrate communities varied seasonally and they were influenced by water-level environmental variables. Richness and composition changed among seasons and were influenced by nutrients and water physicochemical variables. Water turbidity and total dissolved solids influenced macroinvertebrate richness, while water nutrients affected macroinvertebrate abundance. Our results indicate that the lack of effect of nesting waterbirds on macroinvertebrates is possibly due to the variation in the composition of avian species and their reduced population sizes, and in such cases, any effects of birds on macroinvertebrates can be overridden by water chemistry and seasonal changes in intermittent wetlands.(AU)

O principal objetivo deste estudo foi testar o efeito da presença de colônias de nidificação de aves aquáticas sobre a estrutura taxonômica (riqueza, abundância e composição) de comunidades de macroinvertebrados em áreas úmidas do sul do Brasil. As comunidades de macroinvertebrados foram amostradas sazonalmente em oito áreas úmidas intermitentes, diferindo de acordo com a ocorrência de colônias de nidificação de aves aquáticas (quatro áreas úmidas com e quatro áreas úmidas sem a presença de ninhais). A influência de nutrientes e das variáveis físico-químicas da água e do sedimento nas comunidades de macroinvertebrados também foi avaliada. A estrutura da comunidade de macroinvertebrados aquáticos não foi afetada pela ocorrência de colônias de nidificação de aves aquáticas. No entanto, as comunidades de macroinvertebrados variaram sazonalmente e foram influenciadas pelas variáveis ambientais da água. A riqueza e a composição variaram entre as estações e foram influenciadas pelas variáveis físico-químicas e pelos nutrientes da água. A turbidez e o total de sólidos dissolvidos da água influenciaram a riqueza, enquanto que os nutrientes afetaram a abundância de macroinvertebrados. Nossos resultados indicam que a falta de efeito da presença de colônias de nidificação de aves aquáticas na comunidade de macroinvertebrados é possivelmente devido à variação na composição de espécies de aves e ao tamanho reduzido de suas populações, onde em tais casos, quaisquer efeitos das aves sobre os macroinvertebrados podem ser superados pela química da água e pelas mudanças temporais em áreas úmidas intermitentes.(AU)

Can nesting waterbirds influence the community structure of macroinvertebrates in southern Brazilian intermittent wetlands? / Podem as colônias de nidificação de aves aquáticas influenciar a estrutura da comunidade de macroinvertebrados em áreas úmidas intermitentes do sul do Brasil?

The main goal of this study was to test the effect of the presence of nesting waterbirds on the taxonomic structure (richness, abundance and composition) of macroinvertebrate communities in southern Brazilian wetlands. Macroinvertebrate communities were seasonally sampled in eight intermittent wetlands differing according to the occurrence of nesting colonies of waterbirds (four with the presence of rookeries; four without). The influence of nutrients and water and sediment physicochemical variables on macroinvertebrate communities was also assessed. The community structure of aquatic macroinvertebrates was not affected by the presence of colonies of nesting waterbirds. Rather, macroinvertebrate communities varied seasonally and they were influenced by water-level environmental variables. Richness and composition changed among seasons and were influenced by nutrients and water physicochemical variables. Water turbidity and total dissolved solids influenced macroinvertebrate richness, while water nutrients affected macroinvertebrate abundance. Our results indicate that the lack of effect of nesting waterbirds on macroinvertebrates is possibly due to the variation in the composition of avian species and their reduced population sizes, and in such cases, any effects of birds on macroinvertebrates can be overridden by water chemistry and seasonal changes in intermittent wetlands.

O principal objetivo deste estudo foi testar o efeito da presença de colônias de nidificação de aves aquáticas sobre a estrutura taxonômica (riqueza, abundância e composição) de comunidades de macroinvertebrados em áreas úmidas do sul do Brasil. As comunidades de macroinvertebrados foram amostradas sazonalmente em oito áreas úmidas intermitentes, diferindo de acordo com a ocorrência de colônias de nidificação de aves aquáticas (quatro áreas úmidas com e quatro áreas úmidas sem a presença de ninhais). A influência de nutrientes e das variáveis físico-químicas da água e do sedimento nas comunidades de macroinvertebrados também foi avaliada. A estrutura da comunidade de macroinvertebrados aquáticos não foi afetada pela ocorrência de colônias de nidificação de aves aquáticas. No entanto, as comunidades de macroinvertebrados variaram sazonalmente e foram influenciadas pelas variáveis ambientais da água. A riqueza e a composição variaram entre as estações e foram influenciadas pelas variáveis físico-químicas e pelos nutrientes da água. A turbidez e o total de sólidos dissolvidos da água influenciaram a riqueza, enquanto que os nutrientes afetaram a abundância de macroinvertebrados. Nossos resultados indicam que a falta de efeito da presença de colônias de nidificação de aves aquáticas na comunidade de macroinvertebrados é possivelmente devido à variação na composição de espécies de aves e ao tamanho reduzido de suas populações, onde em tais casos, quaisquer efeitos das aves sobre os macroinvertebrados podem ser superados pela química da água e pelas mudanças temporais em áreas úmidas intermitentes.

Can nesting waterbirds influence the community structure of macroinvertebrates in southern Brazilian intermittent wetlands?

ABSTRACT The main goal of this study was to test the effect of the presence of nesting waterbirds on the taxonomic structure (richness, abundance and composition) of macroinvertebrate communities in southern Brazilian wetlands. Macroinvertebrate communities were seasonally sampled in eight intermittent wetlands differing according to the occurrence of nesting colonies of waterbirds (four with the presence of rookeries; four without). The influence of nutrients and water and sediment physicochemical variables on macroinvertebrate communities was also assessed. The community structure of aquatic macroinvertebrates was not affected by the presence of colonies of nesting waterbirds. Rather, macroinvertebrate communities varied seasonally and they were influenced by water-level environmental variables. Richness and composition changed among seasons and were influenced by nutrients and water physicochemical variables. Water turbidity and total dissolved solids influenced macroinvertebrate richness, while water nutrients affected macroinvertebrate abundance. Our results indicate that the lack of effect of nesting waterbirds on macroinvertebrates is possibly due to the variation in the composition of avian species and their reduced population sizes, and in such cases, any effects of birds on macroinvertebrates can be overridden by water chemistry and seasonal changes in intermittent wetlands.

RESUMO O principal objetivo deste estudo foi testar o efeito da presença de colônias de nidificação de aves aquáticas sobre a estrutura taxonômica (riqueza, abundância e composição) de comunidades de macroinvertebrados em áreas úmidas do sul do Brasil. As comunidades de macroinvertebrados foram amostradas sazonalmente em oito áreas úmidas intermitentes, diferindo de acordo com a ocorrência de colônias de nidificação de aves aquáticas (quatro áreas úmidas com e quatro áreas úmidas sem a presença de ninhais). A influência de nutrientes e das variáveis físico-químicas da água e do sedimento nas comunidades de macroinvertebrados também foi avaliada. A estrutura da comunidade de macroinvertebrados aquáticos não foi afetada pela ocorrência de colônias de nidificação de aves aquáticas. No entanto, as comunidades de macroinvertebrados variaram sazonalmente e foram influenciadas pelas variáveis ambientais da água. A riqueza e a composição variaram entre as estações e foram influenciadas pelas variáveis físico-químicas e pelos nutrientes da água. A turbidez e o total de sólidos dissolvidos da água influenciaram a riqueza, enquanto que os nutrientes afetaram a abundância de macroinvertebrados. Nossos resultados indicam que a falta de efeito da presença de colônias de nidificação de aves aquáticas na comunidade de macroinvertebrados é possivelmente devido à variação na composição de espécies de aves e ao tamanho reduzido de suas populações, onde em tais casos, quaisquer efeitos das aves sobre os macroinvertebrados podem ser superados pela química da água e pelas mudanças temporais em áreas úmidas intermitentes.

Potential of the Biotic Ligand Model (BLM) to Predict Copper Toxicity in the White-Water of the Solimões-Amazon River.

In this study, we evaluated the capacity of the Biotic Ligand Model (BLM) to predict copper toxicity in white-waters of the Solimões-Amazon River. LC50 tests using the species Otocinclus vittatus (Regan, 1904) were performed with Solimões-Amazon river water (100%) at 20%, 40%, 60%, and 80% dilutions. A sevenfold decrease in both dissolved and total Cu toxicity was observed in the experiment conducted with 100% when compared to 20% white-water, indicating that physicochemical characteristics of white-water attenuate Cu toxicity. There was agreement between the observed LC50 and the LC50 predicted by the BLM after the adjustment of critical accumulation concentration (LA50) for O. vittatus. BLM modeling indicated that dissolved organic carbon (DOC) and pH were the most important water parameters influencing Cu toxicity, followed by Ca2+. Our results highlight the first evidence that the BLM presents potential to predict Cu toxicity to aquatic organisms in the white-water of the Solimões-Amazon River.

Amazon River dissolved load: temporal dynamics and annual budget from the Andes to the ocean.

The aim of the present study is to estimate the export fluxes of major dissolved species at the scale of the Amazon basin, to identify the main parameters controlling their spatial distribution and to identify the role of discharge variability in the variability of the total dissolved solid (TDS) flux through the hydrological cycle. Data are compiled from the monthly hydrochemistry and daily discharge database of the "Programa Climatologico y Hidrologico de la Cuenca Amazonica de Bolivia" (PHICAB) and the HYBAM observatories from 34 stations distributed over the Amazon basin (for the 1983-1992 and 2000-2012 periods, respectively). This paper consists of a first global observation of the fluxes and temporal dynamics of each geomorphological domain of the Amazon basin. Based on mean interannual monthly flux calculations, we estimated that the Amazon basin delivered approximately 272 × 10(6) t year(-1) (263-278) of TDS during the 2003-2012 period, which represents approximately 7 % of the continental inputs to the oceans. This flux is mainly made up by HCO3, Ca and SiO2, reflecting the preferential contributions of carbonate and silicate chemical weathering to the Amazon River Basin. The main tributaries contributing to the TDS flux are the Marañon and Ucayali Rivers (approximately 50 % of the TDS production over 14 % of the Amazon basin area) due to the weathering of carbonates and evaporites drained by their Andean tributaries. An Andes-sedimentary area-shield TDS flux (and specific flux) gradient is observed throughout the basin and is first explained by the TDS concentration contrast between these domains, rather than variability in runoff. This observation highlights that, under tropical context, the weathering flux repartition is primarily controlled by the geomorphological/geological setting and confirms that sedimentary areas are currently active in terms of the production of dissolved load. The log relationships of concentration vs discharge have been characterized over all the studied stations and for all elements. The analysis of the slope of the relationship within the selected contexts reveals that the variability in TDS flux is mainly controlled by the discharge variability throughout the hydrological year. At the outlet of the basin, a clockwise hysteresis is observed for TDS concentration and is mainly controlled by Ca and HCO3 hysteresis, highlighting the need for a sampling strategy with a monthly frequency to accurately determine the TDS fluxes of the basin. The evaporite dissolution flux tends to be constant, whereas dissolved load fluxes released from other sources (silicate weathering, carbonate weathering, biological and/or atmospheric inputs) are mainly driven by variability in discharge. These results suggest that past and further climate variability had or will have a direct impact on the variability of dissolved fluxes in the Amazon. Further studies need to be performed to better understand the processes controlling the dynamics of weathering fluxes and their applicability to present-day concentration-discharge relationships at longer timescales.

Inspección preliminar de algunas características de toxicidad en el agua potable domiciliaria, Bogotá y Soacha, 2012 / Preliminary survey to detect toxic substances in domestic potable water, Bogotá and Soacha, 2012

Introducción. La distribución y el almacenamiento del agua después de su potabilización, pueden originar cambios significativos en su calidad, por lo que es necesario conocer las características finales del agua domiciliaria que consumen los usuarios. Objetivo. Evaluar de forma preliminar las sustancias químicas tóxicas en el agua de tanques y grifos de viviendas abastecidas por el acueducto de Bogotá. Materiales y métodos. Se hizo un estudio descriptivo en 26 viviendas localizadas en Bogotá y Soacha. Se hicieron dos muestreos: uno en época de lluvias y otro en temporada seca, y en ambos se aplicó una encuesta y se recolectaron muestras de agua de los tanques de almacenamiento y los grifos. Las muestras se sometieron a ensayos fisicoquímicos básicos, a una prueba de tamización de sustancias orgánicas e inorgánicas, y a pruebas de determinación de metales pesados y de residuos de plaguicidas organofosforados y carbamatos. Resultados. La conductividad, el color y los nitratos presentaron valores permisibles; el pH y la turbiedad tuvieron una ligera tendencia a presentar niveles altos y, el cloro residual, niveles bajos. Hubo trazas de aluminio en el 94 % de las muestras. En el período seco, 8 % de las muestras presentó compuestos orgánicos y, en el período lluvioso, 66,7 %. Solo hubo un resultado positivo para las sustancias inorgánicas. En el 11,5 % de las viviendas, el nivel de riesgo fue medio, en el 61,5 %, bajo, y en el 27 % no se registró riesgo. Conclusiones. Se evidenció deterioro de la calidad del agua domiciliaria debido a la presencia de sustancias orgánicas en tanques y sobre todo en las redes, presumiblemente a causa de la formación de biopelículas o a la presencia de polímeros orgánicos. Los niveles de aluminio cercanos al máximo aceptable pueden explicarse por los remanentes de los coagulantes utilizados durante el tratamiento.

Introduction: Significant alterations may be found in the water of Bogotá´s water supply system after its purification, specifically during its distribution and storage in home reservoirs, which makes it necessary to study the final quality of the domiciliary water consumed by users. Objective: To conduct a preliminary study of toxic chemical substances in the water supplied by Bogotá´s water supply system in samples obtained from residential reservoirs and faucets. Materials and methods: Descriptive study made in 26 homes located in Bogotá and Soacha. Two samplings were done during different seasons, each including a survey and the collection of water samples from domiciliary storage tanks and faucets. Samples were analyzed for basic physicochemical parameters, a screening test for organic and inorganic substances and the determination of heavy metals and residues of organophosphate pesticides and/or carbamates. Results: Values obtained for conductivity, color and nitrates were acceptable, pH and turbidity were slightly high while residual chlorine levels were low; aluminum traces were found in 94% of the samples; 8% of the samples analyzed during the dry season showed organic compounds, compared to 66.7% during the rainy season, and just one positive result was obtained for inorganic compounds. Consequently, a medium risk level was observed in 11.5% of homes, low risk in 61.5% and no risk in 27.0%. Conclusion: The evidence showed deterioration of the domiciliary water by organic substances present in the reservoirs as well as in the water supply piping, probably caused by the formation of biofilms or organic polymers. Aluminum levels close to the top permissible limit can be explained by the presence of residual coagulants used during water treatment.

Determining diatom ecotones and their relationship to terrestrial ecoregion designations in the central Canadian Arctic Islands.

Ecotones are key areas for the detection of global change because many are predicted to move with shifts in climate. Prince of Wales Island, in the Canadian Arctic Archipelago, spans the transition between mid- to high-Arctic ecoregions. We analyzed limnological variables and recent diatom assemblages from its lakes and ponds to determine if assemblages reflected this ecotone. Limnological gradients were short, and water chemistry explained 20.0% of diatom variance in a redundancy analysis (RDA), driven primarily by dissolved organic carbon, Ca and SO4 . Most taxa were small, benthic forms; key taxa such as planktonic Cyclotella species were restricted to the warmer, southern portion of the study area, while benthic Staurosirella were associated with larger, ice-dominated lakes. Nonetheless, there were no significant changes in diatom assemblages across the mid- to high-Arctic ecoregion boundary. We combined our data set with one from nearby Cornwallis Island to expand the study area and lengthen its environmental gradients. Within this expanded data set, 40.6% of the diatom variance was explained by a combination of water chemistry and geographic variables, and significant relationships were revealed between diatom distributions and key limnological variables, including pH, specific conductivity, and chl-a. Using principal coordinates analysis, we estimated community turnover with latitude and applied piecewise linear regression to determine diatom ecotone positions. A pronounced transition was present between Prince of Wales Island and the colder, more northerly Cornwallis Island. These data will be important in detecting any future northward ecotone movement in response to predicted Arctic climate warming in this highly sensitive region.

Tendencias actuales para determinar la degradación de los materiales metálicos de componentes industriales / Current trends in degradation assessment on metallic materials of industrial components

En el trabajo se presentan las tendencias actuales en las metodologías para evaluar el daño de los materiales metálicos constructivos y la vida residual de las instalaciones de la industria energética, la del petróleo y otros procesos químicos. Se refirieren algunas de las ideas existentes sobre los fundamentos de la inspección de los componentes para detectar los defectos en el material metálico. Se describen los principales mecanismos de degradación de los materiales en esas instalaciones y se resumen las técnicas experimentales más empleadas in situ en el laboratorio para caracterizar esos mecanismos. Se presenta un grupo de métodos de análisis que se emplean para evaluar la degradación de los materiales y la vida residual de esas componentes.

The need to assess objectively a structural integrity analysis in nuclear and thermal power-, oil- and chemical- industry systems, represents a large challenge for engineers and researchers related to Materials Science, equipment manufactures or users. These systems share many of their problems with regards to aging mechanisms of components metallic materials, high replacement costs and increasing requirements on efficiency and safety. This paper makes an attempt to give an overview of the current trends on material damage and residual life assessment for installations of power-, oil- and chemical industry. Some of the currently existing ideas on components inspection, as an activity for damage detection are shown. A summary on mechanisms of material damage and experimental techniques for their characterization is also presented. Finally, some analytical methods with wide appliance in materials damage evaluation and residual life assessment of components are described.