Aluminium chemistry of the soil solution in an acid forest soil as influenced by percolation rate and soil structure

Abstract

Summary The predicted activity of Al in the soil solutions of acid forest soils often differs from that observed in the field. We have investigated the influence of soil structure and flow rate of the soil solution on the aluminum release to explain this divergence. Disturbed and undisturbed samples of soil were collected from the A and B horizons of a dystric cambisol at Waldstein (Fichtelgebirge, Germany). The samples were irrigated with solutions mixed according to field data on throughfall or soil solution composition with pH 3.5 with flow rates of 4 mm d−1, 12 mm d−1 and 36 mm d−1. The percolates were analysed for major ions. Resulting relations between pH and pAl were compared with batch experiments. In neither the A horizon nor in the B horizon did soil structure influence the relation between pH and pAl. The apparent equilibrium between pH and pAl was described as the pKapp value with pKapp= pAl—a pH (where a is an empirical constant). It was found that the pKapp values for the column percolates were in the range of variation of those found in batch experiments. Flow rate had no influence on pKapp at 4 and 12 mm d−1. At 36 mm d−1 a significant increase of pKapp was observed. This relative undersaturation of Al was more pronounced in the A horizon than in the B horizon. When flow is fast Al release into the percolating soil solution might be limited by diffusion.

An evaluation of acid deposition on cation leaching and weathering rates of an Andosol and a Cambisol

“…In general, mafic rocks such as basalts or gabbros have greater weathering potential than felsic rocks such as granite due to the lower stability of their constituent's minerals and their greater concentrations of base cations (Grieve, 1999 igneous rocks of the same bulk composition (Gislason and Eugster, 1987;Wolff-Boenisch et al, submitted for publication). Studies have primarily focussed on studying the effects of acidic input on forest soils derived from felsic parent material with low CEC particularly Podzols (Franken et al, 1995;Walna et al, 1998;Hodson and Langan, 1999;Dubikova et al, 2002). There is a lack of understanding of long-term effects of acid precipitation on base cation leaching and weathering of non-forested soils derived from mafic parent material.…”

The earthworm Aporrectodea caliginosa stimulates abundance and activity of phenoxyalkanoic acid herbicide degraders

“…Polyvinyl chloride columns (14 (inner diameter) Â 30 (height) cm 2 ; Franken et al, 1995) were packed to 15 cm height, with approximately 2.4 kg (fresh weight) soil that was adjusted to a final moisture content of 21% (w w À1 ) with sterile deionized water and mixed with 2% (w w À1 ) grass pieces. Soil was supplemented with: (i) earthworms and MCPA; (ii) worms only; (iii) MCPA only; and (iv) water only.…”

Aluminum Output Fluxes from Forest Ecosystems in Europe: A Regional Assessment

“…In general, prediction of the H + and Al concentrations in soil solutions using equilibria approaches is very difficult because of the uncertainty related to the thermodynamic constants used (Schecher and Driscoll, 1987). Furthermore, disequilibria of soil solutions with respect to defined Al‐containing solids has often been found (Matzner and Prenzel, 1992; Franken et al, 1995) as well as long‐term changes in the Al chemistry (Mulder and Stein, 1994). Nevertheless, deterministic models predicting Al output are used today on both local and regional scales (e.g., MAGIC, SAFE, SMART), including the calculation of critical loads for acidic deposition (deVries et al, 1994; Warfinge and Sverdrup, 1992).…”