Concrete under sulphate attack: an isotope study on sulphur sources.

The formation of secondary sulphate minerals such as thaumasite, ettringite and gypsum is a process causing severe damage to concrete constructions. A major key to understand the complex reactions, involving concrete deterioration is to decipher the cause of its appearance, including the sources of the involved elements. In the present study, sulphate attack on the concrete of two Austrian tunnels is investigated.

Transpiration, CO2 assimilation, WUE, and stomatal aperture in leaves of Viscum album (L.): Effect of abscisic acid (ABA) in the xylem sap of its host (Populus x euamericana).

Leaves of the mistletoe Viscum album (L.) show a high rate of transpiration, even when the host is under severe drought stress. The hypothesis that a strong control of ABA influx from the xylem sap of the host into the mistletoe prevents stomatal closure in mistletoe leaves was tested under the following conditions: sections of poplar twigs carrying a mistletoe were perfused with artificial xylem sap that contained different ABA concentrations and both transpiration and ABA levels were analysed in mistletoe leaves.

Differences in the influx of glutamine and nitrate into Viscum album from the xylem sap of its hosts.

The flux of inorganic and organic nitrogen into the mistletoe Viscum album L. from the xylem sap of a deciduous (Populus x euamericana) and a coniferous host (Abies alba Mill.) was analyzed.

Spatial and seasonal variation in amino compounds in the xylem sap of a mistletoe (Viscum album) and its hosts (Populus spp. and Abies alba).

In a field study, the composition and concentrations of amino compounds in the xylem sap of the mistletoe, Viscum album L., and in the xylem sap of two host species, an evergreen conifer (Abies alba Mill.) and a deciduous broad-leaved tree (Populus x euramericana), were analyzed.

Seasonal and spatial variation of carbohydrates in mistletoes (Viscum album) and the xylem sap of its hosts (Populus x euamericana and Abies alba).

In the present field study we analysed the seasonal pattern of carbohydrate composition and contents in the xylem sap of Viscum album and the xylem sap of a deciduous (Populusxeuramericana) and a coniferous (Abies alba) host tree species. The results were compared with the soluble carbohydrate composition and contents of mistletoe tissues. On both hosts significant amounts of glucose, fructose, and sucrose were found in the xylem sap of Viscum throughout the seasons.