Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms

Finitud y duración

Este artículo presenta una articulación de las ideas de duración, cosmicidad, proximidad y finitud a modo de puntos definidores de un ethos cercano al de la sostenibilidad y contrapuesto al Gestell heideggeriano de la técnica moderna, al nihilismo indistante del consumismo y a la retórica de la innovación tecnológica.This paper presents an articulation of the ideas of duration, cosmicity, proximity and finitude as the defining features of an ethos close to that of sustainability, and contrary to the heideggerian Gestell of modern technique, to the nihilism undistant from consumerism and the rhetoric of technological innovation

Finitud y duración

Este artículo presenta una articulación de las ideas de duración, cosmicidad, proximidad y finitud a modo de puntos definidores de un ethos cercano al de la sostenibilidad y contrapuesto al Gestell heideggeriano de la técnica moderna, al nihilismo indistante del consumismo y a la retórica de la innovación tecnológica

Philosophy as attentive gaze

There is something unusual, even paradoxical, about the way that we look at the world around us: the utter ease of looking contrasts with the difficulty of performing the same act well. If there is light, we just open our eyes and the things around us appear. In contrast, we must pay attention to become aware of certain aspects of reality and, in particular, to perceive things in a different way. Simply seeing, mere visual perception, involves virtually no effort (hence, for example, the success of television and screens in general), but looking with care is harder: directing our gaze and concentrating on something involves an effort and can therefore be tiring. The attentive gaze is more uncommon than we might expect. What is it that attention adds to the gaze to transform it in such a significant way? Why does the effort of directing our attention imply much more than a simple zoom effect? Philosophical gaze and attentive gaze is the same thing

Hannah Arendt y el totalitarismo: Implicaciones para una teoría política

El centro del pensamiento político de Hannah Arendt lo ocupa el concepto de acción, que se identifica con la capacidad humana de comenzar, de empezar algo nuevo. Junto a este concepto e interrelacionándose con él podemos encontrar los de novedad, nacimiento, pluralidad, espacio publico, pensamiento, mal ... La finalidad de este artículo consiste en mostrar cómo la mayoría de estos conceptos se forjan ya en los análisis de Arendt sobre el totalitarismo. La «lógica» totalitaria conduce, precisamente, a la anulación de la pluralidad y de la diversidad humanas, de la acción y del pensmiento, de la [(polis~y del .mundo

Malignant Transformation of Rat Kidney Induced by Environmental Substances and Estrogen

The use of organophosphorous insecticides in agricultural environments and in urban settings has increased significantly. The aim of the present study was to analyze morphological alterations induced by malathion and 17β-estradiol (estrogen) in rat kidney tissues. There were four groups of animals: control, malathion, estrogen and combination of both substances. The animals were injected for five days and sacrificed 30, 124 and 240 days after treatments. Kidney tissues were analyzed for histomorphological and immunocytochemical alterations. Morphometric analysis indicated that malathion plus estrogen-treated animals showed a significantly (p less than 0.05) higher grade of glomerular hypertrophy, signs of tubular damage, atypical proliferation in cortical and hilium zone than malathion or estrogen alone-treated and control animals after 240 days. Results indicated that MFG, ER-α, ER-β, PgR, CYP1A1, Neu/ErbB2, PCNA, vimentin and Thrombospondin 1 (THB) protein expression was increased in convoluted tubules of animals treated with combination of malathion and estrogen after 240 days of 5 day treatment. Malignant proliferation was observed in the hilium zone. In summary, the combination of malathion and estrogen induced pathological lesions in glomeruli, convoluted tubules, atypical cell proliferation and malignant proliferation in hilium zone and immunocytochemical alterations in comparison to control animals or animals treated with either substance alone. It can be concluded that an increased risk of kidney malignant transformation can be induced by exposure to environmental and endogenous substances