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The Effect of Climate Warming on the Hydrochemistry of Alpine Lakes
2003
Rogora, M. | Mosello, R. | Arisci, S.
The hydrochemistry of mountain lakes is highly conditioned by the chemicalcomposition of atmospheric deposition and by climate characteristics. Consequently these ecosystems have proved to be sensitive to long-term changes in both factors. Climate warming seems to be particularly pronounced in the Alpine region. A reduction of snow cover in space and time, due to less precipitation and higher temperatures, means a greater exposure of rocks and soils in the watersheds, which enhances weathering processes. In this paper we aim to evaluate the possible effect of these processes on long-term changes in the chemistry of alpine lakes. Recent climate changes affecting the study area were investigated through a data series referring to temperature, precipitation, snow depth and duration at some stations in the Ossola Valley. Chemical data of 35 lakes located in the Ossola and Sesia Valleys (Central Alps) were used. Lakes were sampled both in the late summer of 2000 and 2001 in the framework of two European Projects and the results compared with previous data (1984–1987). Two lakes (Boden Superiore and Inferiore, 2343 and 2334 m a.s.l., respectively), located in the northern part of the study area, have been sampled more or less continuously since the late 70s, enabling us to evaluate the trends of the main chemical variables. For lakes lying in catchments with highly soluble rocks, a comparison between the two data sets shows an increase of solute contents in the last few years. This result could be attributed to increased weathering rates due to climate warming.
Mostrar más [+] Menos [-]Development of a Multi-Resolution Emission Inventory and Its Impact on Sulfur Distribution for Northeast Asia
2003
Woo, J.-H. | Baek, J. M. | Kim, J. W. | Carmichael, G. R. | Thongboonchoo, N. | Kim, S. T. | An, J. H.
Emissions in East Asia for 1993 by administrative units and source types are estimated to support regional emission assessments and transport modeling studies. Total emission of SOₓ, NOₓ, soil NOₓ, N₂O, and NH₃are 24 150, 12 610, 1963, 908, and 8263 kton yr⁻¹, respectively.China's emission contribution is the highest for every species.The area sources are the most significant source type for SOₓand NOₓ, but the fraction due to mobile source is highest for NOₓ. Major LPSs are located from the middle to the east part of China, south and middle-west part of South Korea, and the east part of Japan. The area sources of SOₓshow a pattern similar to population density, whereas NH₃shows a strong landuse dependency. Detail emissions analysis reveals higher SOₓemission `cores' within each province. The estimated emissions are used to estimate sulfur deposition in the regions. The seasonal average sulfur distribution amounts are estimated from the ATMOS2 chemical transport model. The results showed anti-correlation with temperature for sulfur (SO₂+ SO₄⁻²) concentrations and a positive correlation with rainfall for deposition.
Mostrar más [+] Menos [-]Removal of Phosphate from Waste Waters by Adsorption
2003
Oguz, Ensar | Gürses, Ahmet | Yalçın, Mehmet
In this study, the adsorption of phosphate on gas concrete from aqueous solutions has been studied as functions of temperature, mixing rates and suspension pH. Over 99% of phosphate removal was found. The chemical composition of the gas concrete has been defined by X-ray analysis. Experimental data was fitted to the Langmuir equation in order to Langmuir coefficients. After calculating Langmuir coefficients, adsorption free energy (Δ G⁰ₐdₛ.) has been determined. In order to gather information about adsorption mechanism, electrophoretic mobilites of particles were measured at various pHs by using Zeta meter 3.0+. It has been found that the adsorption is driven by the interactions between the ionizations of CaO and Al₂O₃and the formation of AlPO₄. According to the BET (N₂) measurements, the specific surface area of gas concrete was found as 22 m²g⁻¹. The surface area after adsorption has been found as 17 m²g⁻¹. The surface area covered by adsorbate has been found as 5.23 m²g⁻¹by usingaₛ= nˢₘ. aₘ. NA. These two areas determined by BET and Langmuir model were close to each other (BET: 22 m²g⁻¹–17 m²g⁻¹).
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