No description available.

The effects of low pH, AI, organic and phenolic acids on the growth of naturally occurring plant species were determined. The amelioration of Al toxicity by Si and organic acids was also investigated. Plants were grown from seeds in nutrient solutions simulating the ionic composition of soil solutions from five soil types ranging from acidic peat to calcareous soil. Soil solutions were extracted and analysed using centrifugation, with and without an immiscible displacent (1,1, I-trichloroethane), at both low (4000 rpm) and high speed (12000 rpm). Races of Holcus lanatus L. and Betula pendula Roth. from acidic soils (FM and SMM) grew better in low pH solutions (pH< 4.0). In acid-sensitive races Ca absorption was inhibited at low pH. Races of B.pendula from strongly to moderately acidic soils (FM, SMM, KP) were AI-tolerant and effectively excluded Al from shoots. Root elongation and leaf expansion were inhibited by all Al concentrations in races from calcareous soils (KR). Low concentrations of Al stimulated growth in some races of B.pendula (2 and 5 mg Al lˉ¹) and Anthoxanthum odoratum L. (1.3 and 2.7 mg Al lˉ¹). Al (25 and 35 mg lˉ¹) inhibited root and shoot growth in H.lanatus. Si (1500 and 2500 µM Si(OH)₄) addition to nutrient solutions alleviated AI-damage and restored nutrient uptake to values similar to those in plants grown with neither Al or Si. The ameliorative effects of Si were possibly achieved through AI/Si co-deposition in the root cell walls and maintenance of Golgi activity. Si at 1500 µM was beneficial but inhibited growth at 2500 µM. Al and hydroxyaluminosilicates at pH 5.6 were not toxic. Formic and tartaric acid ameliorated Al toxicity by reducing its availability. These organic acids on their own stimulated growth in H.lanatus and Deschampsia flexuosa (L.) Trin. Phenolic acids stimulated growth of H.lanatus in acidic solutions (pH 4.0) but not near-neutral solutions, particularly in races from soils high in phenolics. Addition of plant residue to acidic peats increased the growth of races from calcareous and acidic mineral soils.

LD2668 .T4 1941 K71 / Master of Science

No description available.

This thesis describes the water chemistry of the River Dee and its tributaries, and the potential water chemistry changes that may occur under acid deposition and land use change scenarios. Historic water quality and flow records were collated and supplemented with new water chemistry data. These data were analysed in relation to catchment geography and river flow using both mathematical modelling and novel, GIS based techniques. This analysis established the importance of diffuse inputs and highlighted differences between upland and lowland regions in the catchment. In headwater streams, different geological types create hydrochemical source areas that strongly influence stream chemistry whilst in lowland tributaries, agricultural sources are particularly important. In the upland region most major ions were diluted as flows increased, further emphasizing the influence of deeper geological sources on baseflow chemistry, but showing soilwater controls on stormflow composition. The headwaters, which drain predominantly acid rocks, are presently oligotrophic but threatened by the impact of acid deposition and land use change (re-afforestation). In some of the lowland tributaries, increased NO3-N concentrations have resulted from more intensive land management. The potential impacts of acid deposition and land use change were simulated in both upland and lowland catchments by considering existing and new models within a Functional Unit Network. For upland regions this consisted of developing a new, two component hydrochemical mixing model to simulate the spatial and flow-related variations in streamwater acidity. The mixing model was based on End Member Mixing Analysis (EMMA), and site specific end members (alkalinity and Ca) could be predicted from emergent catchment characteristics (soil and land use) using linear regression.

No description available.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1961. / Typescript. Digitized and made available by the University of Wisconsin Digital Collections Center as part of Minds@UW. Description based on print version record. WU Includes bibliographical references (leaves 70-71).

Thesis (Ph. D.)--University of Florida, 1974. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 154-159).

Thesis (M.S.)--University of Wisconsin--Madison, 1961. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 70-71).