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Abstract. We report on measurements of atmospheric transmission (ATr) and aerosol optical depth (AODr) made at three wavelengths (368, 500, and 778 nm) with a spectroradiometer placed on Tenerife (28.5øN, 16.3øW), Canary Islands. Using the National Oceanic and Atmospheric Administration (NOAA) advanced very high resolution radiometer (AVHRR) channel 1, we also measured the aerosol optical depth (AODs) and albedo over a region of the North Atlantic Ocean extending from 15ø-35øN to 12ø-25øW. We observe large changes in ATr and AODr when dust outbreaks pass over this region. Using all these data, we derive the asymmetry factor (g), the single-scattering albedo (co), and the local mean AODr and we compute 'the direct radiative forcing AF attributable to mineral

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We studied the planktonic food web in eutrophic Sau Reservoir (Catalonia, NE Spain). Along the longitudinal axis from the Ter River downstream to the dam, we characterized a microbial succession of food web dominance of bacteria‐HNF‐ciliates. The Ter River transports a large load of organic material into the reservoir, with a bacterial density of ∼9 · 106 large cells per ml. While at the first lacustrine station of the Reservoir HNF were the dominant bacterial consumers, at the others, an oligotrich ciliate, Halteria grandinella, was the main protozoan bacterivore. Most of the bacterial production in the reservoir epilimnion was consumed by grazing. The spatial succession of the reservoir microbial food webs was followed downstream by maximum densities of their potential predators among zoo‐plankters – rotifers, and early developmental stages of copepods.

Na + /K + equilibrium ion exchange isotherms on Amberlite IR-120 (known as a strong acid resin) in pure methanol, ethanol, 2-propanol, 1-butanol, and 1-penthanol and in mixtures of methanol + water, ethanol + water, 2-propanol + water, 1-butanol + methanol, and 1-penthanol + methanol at 313 K have been determined. Experimental equilibrium data have been satisfactorily correlated using the homogeneous mass action law model (LAM). This model assumes nonideal behavior for both the solution and the solid phase. Wilson and Debye-Hu ¨ckel equations have been used to calculate activity coefficients in the solid and liquid phase, respectively. It has been observed that the dielectric constant of the solvent or the mixture exerts a strong influence not only on the useful capacity of the resin but also on the equilibrium behavior of the system.

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