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Chemical Erosion Effect Of Loess Byacid Rain

Posted on:2014-07-11Degree:MasterType:Thesis
Country:ChinaCandidate:Y P HanFull Text:PDF
GTID:2253330401972728Subject:Hydrology and water resources
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In recent years, the acid rain problem emerges in an endless stream, acid rain has becomea major environmental problem in China, and our research has focused on acid rain insouthern acid rain-prone areas. Northwestern region of the acid rain problems are highlighted,and the acid rain in northwest loess soil element migration behavior of the impact is not yetclear, so further to study the effect of acid rain on soil in the northwest region is a meaningfulwork. Paper according to the Xi’an rainfall chemical composition of the preparation ofsimulated acid rain of five different gradients, utilizing three typical Shaanxi yangling loesssoil (the standard loess, clay and humus) soil column leaching experiment was carried out.The contrast of the filtrate and soil chemical indicators to study the elements of acid rain onsoil release and migration characteristics of law, including soil acidification, the release andmigration of nutrient elements phosphorus, base cations calcium and magnesium. The mainconclusions of the paper are as follows:(1) Caused by acid rain on soil acidification effect: The smaller the pH of the acid rain,soil drench filtrate pH. After acid leaching of soil, the soil will be a certain degree ofacidification, the greater the acidity of the acid rain leaching after the more serious the soilacidification, three kinds of soil buffering capacity to acid rain: standard loess> clay> humussoil. Standard and clay loess acidification mainly occurs in the surface soil, and the humussoil acidification mainly occurs in the underlying soil, humus soil acidification is the mostserious after the erosion of acid rain.(2) After acid leaching of soil nutrient phosphorus leaching rule: with the increase ofaccumulative leaching amount of acid rain, the soil phosphorus release amount increased, butthe leaching rate will decline After the leaching of acid rain, soil total phosphorus contentincreased with depth first increase then decrease. In the pH value of5.6and6.5in standardloess each section under the acid rain erosion of phosphorus content is lower than thebackground value content, loss of phosphorus nutrition elements under the erosion of acidrain. Acid rain caused when pH is5the accumulation of soil phosphorus leaching amount isthe largest, acid rain of humus soil phosphorus has the strongest effect.(3) Acid rain leaching of soil calcium leaching pattern: Soil calcium release rate with theincrement of the leaching of acid rain falling fast first, then gradually stable, long-term eluviation causes sustained release of soil calcium; soil water-soluble calcium contentdecreases with depth increasing. Humus soil calcium release speed under the continuousleaching of acid rain is consistent with the basic, standard and clay loess calcium release ratedecreases gradually as the leaching. PH value of3of the leaching of acid rain in three kindsof soil calcium release quantity are the largest, strong acid rain, easy cause soil salt ionleaching. Humus soil calcium leaching minimum under acid rain erosion, standard loess underthe effect of acid leaching of soil mineral weathering, be released large amounts of acidsoluble calcium, the calcium content in soil profile after the leaching of acid rain are greaterthan soil background content of calcium.(4) Acid rain caused by leaching the soil magnesium leaching phenomenon: with theincrease of accumulative leaching amount of acid rain, the soil magnesium release amountincreased, and the leaching rate gradually decreases; Soil water soluble magnesium contentincreases slightly with the increase of depth. PH value of3of the leaching of acid rain inthree kinds of soil magnesium release quantity are the largest, strong acid rain, easy cause soilsalt ion leaching, humus magnesium leaching minimum. Standard loess soil leaching of acidrain mineral hydrolysis, released a large number of acid-soluble magnesium hydrolysis, acidrain leaching the magnesium content of the soil profile is greater than the background value ofsoil content.(5) Select the one-way ANOVA, respectively for three kinds of soil under the effect ofdifferent acid rain acidity of soil phosphorus, calcium and magnesium to release a quantitydifference significance analysis, humus soil under different acidity is to release a quantity hadno significant difference, while the standard and clay loess in acid rain acidity difference bigdifferences. Long-term erosion of acid rain can cause the loss of soil phosphorus, calcium,magnesium nutrition, soil nutrient impoverishment.
Keywords/Search Tags:acid rain, loess soil, nutritional elements phosphorus, base cations calcium, magnesium, acidification, leaching
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