The Study Of Clay Minerals In Modern Sediments Of Dianchi Lake

Researching on Dianchi lake's status quo and pollution treatment are main tasks of environmental science and geological science. While researching on contemporary sediments of Dianchi lake is one point of the contents. Researching on sediments, especially clay minerals in contemporary sediments is important for mineralogist. Combining with new methods and achievements of related sciencific fields, this paper took a systematic investigation to clay mienrals of Dianchi lake's contemporary sediments.Samples of sediments distributed to the whole water area of Dianchi lake with a frequency of about every three square kilometers, and was purified by conventional method. Every sample was purified into two samples, one with grain's diameter larger than 2 micron, and the other smaller than 2 micron. All samples was analysised qualitivly and quantitativly by method of X-ray diffraction.Analysis results showed that compose of crude samples is only quartz while minute samples contain with some clay minerals including kaolinite, illite, montmorillonite, chlorite, vermiculite, and mixed-layering minerals. Half-quantity analysis showed that kaolinite hold a quantum of 39.7%, and illite of 33.55%,montmorilonite and mixed-layring minerals of 19.4%, chrolite of 7.4%. Vermiculite and other minerals' quantum is little.Every mineral's quantiy is variable on surface.Clay minerals showed a farily regional diference through half-quantity analysising. From I to V, clay mineral sediment was divided into five sections, each section has quantity diference. In one section, there must be a mineral's quantity depart its average rate apparently. Primary argument about the reason is because of the variation of sediment source. In addition.it may include physical, chemical and biotic condition.Montmorillonite is good adsorb material. Its adsorb capability is much better than kaolinite and illite, so the content of montmorillonite can represent sediments of clay minerals' adsorb capability, thus determine its self-purify capability. In five partition of Dianchi, because of vary content of montmorillonite on surface, its self-purify capability is variable. Part II,IV and V has a relative faint self-purifycapability, while these parts take a large area of Dianchi, in addition that montmorillonite's content is little, the self-purify capability of Dianchi lake' contemporary clay minerals is faint on the whole.Researching on some main clay minerals' elements, structure, physical and chemical character has been done. While a emphatic research on the thermodynamic mechanism of generation and transformation of kaolinite, illite and montmorillonite has been done too. The arguments showed that kaolinite is relative stable mineral of these clay minerals, illite is inferior to kaolinite. Montmorillonite's thermodynamic stableness is inferior to that of kaolinite, and it can mutually transform with illite in different condition. Chrolite and vermiculite's stableness is inferior to that of montmorillonite. These arguments verfied that the section action of Dianchi lake's sediments is reasonable. The content of illite in new stratum of Quaternary in Kunming basin is more than that of old, so the vary area of Dianchi which receive substances from vary stratum display a vary content of illite, from which to form area partition of sediments. At the same time, the chapter explained that clay minerals of five centimeters on the surface of Dianchi's sediments have taken little tranformation on thermodynamics and kinetics because of faint alkalinity and reductiveness of the environment of Dianchi and time limitation.