An integrated program has been developed to explore the reactivity of 2:1 phyllosilicates (biotite and the clays montmorillonite, hectorite, and nontronite) with respect to acid dissolution using in situ atomic force microscopy (AFM). Three techniques are described which make it possible to fix these minerals and other small particles to a suitable substrate for examination in the fluid cell of the atomic force microscope. A suite of macros has also been developed for the Image SXM image analysis environment which make possible the accurate and consistent measurement of the dimensions of clay particles in a series of AFM images, so that dissolution rates can be measured during a fluid cell experiment. Particles of biotite and montmorillonite were dissolved, and their dissolution rates normalized to their reactive surface area, which corresponds to the area of their edge surfaces (A_e). The A_e-normalized rates for these minerals between pH 1-2 are all ~10E^-8 mol/m²*s, and compare very well to other A_e-normalized dissolution rates in the literature. Differences between the A_e-normalized rates for biotite and the BET-normalized rates (derived from solution chemical studies) found in the literature can be easily explained in terms of the proportion of edge surface area and the formation of leached layers. However, the differences between the A_e-normalized montmorillonite rates and the literature values cannot be explained the same way. Rather, it is demonstrated that rates derived from solution studies of montmorillonite dissolution have been affected by the colloidal behavior of the mineral particles. Finally, the dissolution behavior of hectorite (a trioctahedral smectite) and nontronite ( a dioctahedral smectite) were compared. Based on the differential reactivity of their crystal faces, a model of their surface atomic structures is formulated using Hartman-Perdock crystal growth theory, which explains the observed data if it is assumed that the rate-determining step of the dissolution mechanism is the breaking of connecting bonds between the octahedral and tetrahedral sheets of the mineral structure. / Ph. D.

Abstract Mechanical harvesting of peat changes the original mire ecosystem completely, and without active measures these areas may remain non-vegetated even for decades. Afforestation is one of the most popular after-use options for cut-away peatlands in Finland since it has both economic and aesthetic values. Recycling of wood-ash as a fertilizer has been studied extensively in peatlands drained for forestry. Wood-ash is reported to promote tree growth in these areas without any significant negative impact to the environment and could, therefore, be a suitable option also on cut-away peatlands. However, the environmental effects of ash-fertilization on cut-away areas and on ground vegetation are not fully understood. The impact of wood- and peat-ash application on the early establishment of ground vegetation and downy birch (Betula pubescens) seedlings and on post-fertilization element concentrations in plants and peat substrate were studied in a cut-away peatland. Six treatments of wood-ash, peat-ash, biotite or Forest PK-fertilizer were replicated in three blocks in different mixtures and quantities corresponding to 50 kg ha-1 of phosphorus. All the fertilizers accelerated the revegetation of the bare peat surface significantly, whereas the establishment of plants in the unfertilized area was non-existent even several years after the peat harvesting had ceased. The most striking difference between the wood- and peat-ash-fertilizers and the commercial Forest PK-fertilizer was the extensive coverage of fire-loving moss species in all the areas where ash was spread. Wood- and peat-ash application also accelerated the germination and early establishment of downy birch seedlings more efficiently than the PK-fertilizer. Ground vegetation proved to be highly important in increasing the early biomass production and carbon sequestration on ash-fertilized cut-away peatland. In addition, the below-ground biomass was equal to the above-ground biomass, or even greater. Both wood- and peat-ash fertilization ensured an adequate level of nutrients for the early establishment of ground vegetation and birch seedlings in a cut-away peatland. The mosses and herbaceous plants proved to have a major role in retaining the nutrients and heavy metals that otherwise might have leached away from the ash-fertilized cut-away site during the early stages of the afforestation. Although both wood- and peat-ash proved to be suitable for the initial fertilization of afforested cut-away peatlands, a later application of nutrients may be needed to guarantee the growth in a energy-wood stand of downy birch over its entire rotation. / Tiivistelmä Turvetuotannon päätyttyä jäljelle jäävä suopohja on aluksi täysin paljas ja vailla maaperän siemenpankkia. Kasvipeitteen luontainen uudistuminen voi viedä jopa vuosikymmeniä. Ympäristönhoidollisesti onkin tärkeää, että suopohjat otetaan uuteen käyttöön mahdollisimman nopeasti tuotannon päätyttyä. Metsitys on tällä hetkellä suosituin suopohjien jälkikäyttömuoto Suomessa. Suopohjan turpeessa on tyypillisesti runsaasti typpeä, mutta niukasti muita kasvuun tarvittavia ravinteita. Puutuhka on osoittautunut pitkäaikaisissa metsäojitettujen turvemaiden tutkimuksissa kilpailukykyiseksi vaihtoehdoksi kaupallisille lannoitteille. Energiantuotannon sivutuotteena syntyvä puu- ja turvetuhka voisi soveltua hyvin myös suopohjien lannoitteeksi. Tuhkan käytöstä lannoitteena turvetuotannosta vapautuneilla suopohjilla ei kuitenkaan ole riittävästi tutkimustietoa. Tässä työssä tutkittiin puu- ja turvetuhkan vaikutuksia turvetuotannosta vapautuneen suopohjan kasvittumiseen ja puun taimien alkukehitykseen viiden ensimmäisen kasvukauden ajan. Lisäksi tutkittiin kasvillisuuden ravinne- ja raskasmetallipitoisuuksien muutoksia sekä turpeen ravinteisuutta lannoituksen jälkeen. Kaikki lannoitteet nopeuttivat merkittävästi kasvillisuuden muodostumista paljaalle suopohjalle, kun taas lannoittamaton alue pysyi kasvittomana. Tuhkalannoitetuille alueille syntyi nopeasti laajoja palopaikoilla viihtyvien pioneerisammalten kasvustoja, jotka peittivät ja samalla sitoivat paljaan ja irtonaisen turvemaan pinnan. Tuhkalannoitus edisti myös koivun taimien alkukehitystä tehokkaammin kuin kaupallinen Metsän PK-lannoite. Sammalista ja ruohovartisista kasveista muodostuva aluskasvillisuus ylitti puuntaimet selvästi biomassan määrässä ja toimi metsityksen alkuvaiheessa puuntaimia merkittävämpänä hiilensitojana. Lisäksi kasvien maanalainen biomassa oli maanpäällistä biomassaa suurempi. Sekä puu- että turvetuhka takasivat riittävän määrän ravinteita energiapuumetsikön alkukehitykselle. Aluskasvillisuus osoittautui tärkeäksi tuhkasta liukenevien ravinteiden ja raskasmetallien sitojaksi metsityksen alkuvaiheessa. Vaikka sammalten kadmiumpitoisuudet nousivat tuhkalannoituksen seurauksena, ne olivat kuitenkin alhaisia Suomessa aiemmin mitattuihin sammalten yleisiin pitoisuuksiin suhteutettuna. Tuhkalannoitus ei lisännyt haitallisten raskasmetallien pitoisuuksia koivun taimien ja ruohovartisten kasvien lehdissä ja varsissa. Tutkimuksen tulokset tukevat puu- ja turvetuhkan käyttöä energiapuumetsiköiden alkuvaiheen lannoitteena turvetuotannosta vapautuneilla suopohjilla.

Isolated granitic rock bodies (granites, granodiorites, quartz monzonites) in the vicinity of Benson in southeastern Arizona were studied to trace the behavior of rock weathering. Thin sections of fresh granites were examined to characterize the original mineralogy which consisted mainly of quartz, feldspars, and micas. The weathering products show up on the granites as grus and soil profiles as well as down slope in the basin deposits. X -ray diffraction studies of the < 2 micrometers fraction of the weathering products proved illite, smectite, illite-smectite mixed layer, and kaolinite to be the dominant clays; quartz and feldspar also persisted into this size fraction. Silt sized material produced similar results. The quartz monzonite of Texas Canyon afforded a special study of the initial weathering stages of feldspars and micas. In the < 2 micrometers fraction obtained from granitic material placed in an ultra sonic bath, the feldspars weathered to a Na-montmorillinite while biotite weathered to vermiculite.