Distribution Characterization And Its Significance Of N-alkanes In The Main Types Soil Of Jilin Province

Soil is a complax natural body and an important part of human ecologicalenvironment. Primary mineral is the initial source of various chemical elements in soiland they constitute most of soil minerals. The most active part in soil, however, is thesecondary minerals and organic matter. Soil organic matter is an important constituentof the soil solid phase part and it has a much important function and significance onsoil formation, soil fertility, environmental protection, sustainable development ofagriculture and forestry though it is just a very little part of soil.In modern soil, n-alkanes and isoprenoid compounds, including pristane andphytane, can indicate the changing environment. The different content, carbon numberrange and geochemical parameters of them in different soil profile reflects thediversity of the soil maturity, redox properties and the organic matter’s source. Byanalysing the n-alkanes distribution in soil profile of different type in Jilin Province,we inquire into the affection of the n-alkanes distribution from the soil types and thezonal factors. We also analyse the laws of soil development and evolution, the soilforming condition of the profile, the evolution dgree of organic matter and the sourcesof n-alkanes. Then we deduce what is the circumstances of vegetation that makes thesoil organic matter forming in ancient environment. All those are aimed to getreference for recovering the ancient environment in Jilin Province and providescientific basis of protecting and improving the soil.Jilin province is located in the cold temperate zone and all four seasons areclearly defined here. The terrain characteristic is higher in the Southeast, lower in theNorthwest. The soil in the east, middle and west is distributed zonally and the azonalsoil scatteres in the typical zonal soil. There is high-yield farmland of corn and rice inJilin Province and the virgin forest in Changbai Mountain is kept completely. So, thesoil types are multiple, the geological characteristics is typical and thus thedistribution characterization of n-alkanes in different types of soil is evident.In this paper, There are133samples of different soil profiles from19types ofsoil (45subcategories) and8samples of typical plants. The main research results are: (1) Systematically analysing the content of n-alkanes and isoprenoid compounds,including pristane and phytane, in different types of soil in Jilin Province. Discussingthe environmental geochemistry changing rules of different types of soil organicmatter by using the environmental indicator of the distribution characteristics ofn-alkanes and isoprenoid compounds, including pristane and phytane.(2) Analysing the distribution characterization of n-alkanes in vertical zonal soiland horizontal zonal soil in Eastern Jilin. Most n-alkanes in the soil from the East areenriched in subsurface stratum. The soil organic matter in the East are mainly fromterrestrial higher organisms and their maturity is low, the soil in the East is in strongreducing conditions. In addition, the CPI1figure of vertical zonal soil in ChangbaiMountain distributes regularly with the altitude changing. There is no evidenthorizontal zonality distribution rule of the eastern soil.(3) Analysing the distribution characterization of n-alkanes in zonal soil inMiddle Jilin. The average figures of OEP are respectively2.37,1.79,2.39, CPI2arerespectively2.71,2.12,1.59. The odd even predominance of long chain n-alkanes isobvious. The data shows that the higher plants are the main source of soil organicmatter and their maturity is relatively low. The Pr/Ph ranging from0.64to1.17reveals that the zonal soil in the Middle is in weak Oxidation-reduction conditions.(4) Analysing the distribution characterization of n-alkanes in zonal soil inWestern Jilin. The higher plants are the main source of n-alkanes in zonal soil inWestern Jilin and their maturity is relatively high. The distribution of CPI2in the soilin the West has longitudinal zonal characteristics and with the decreasing of longitude,the maturity of the soil organic matter in the West increases. The figure of L/Hdecreases with the extension to the west of the chernozem. All those reflect thelongitude zonality factors which affect the changing nature of the soil in the west.(5) Discussing the distribution rules of n-alkanes in zonal soil in Jilin Province.The transformation characteristic of geochemical parameters OEP, CPI2, and Pr/Phreflects the zonal distribution rule of the main soil in Jilin Province. With thedecreasing of longitude, the soil geochemical parameters OEP and CPI2appear adownward trend and Pr/Ph, rising.(6) Analysing the distribution characterization of the non-zonal soil n-alkanes inJilin Province. The distribution of the non-zonal soil n-alkanes has great difference.The soil types and the zonal factors of soil distribution gives different effection. The source of non-zonal soil n-alkanes are various and the maturity of soil organic matteris generally very low. The soil redox properties are decided by the type of the soil andthe soil-forming additive process.(7) Analysing the distribution characterization of the typical plants n-alkanes inJilin Province. The same plant in different areas has the entirely different n-alkanesdistribution. The main peak carbon of n-alkanes of the weeds in the eastern mountainsis nC31, and the main peak carbon of n-alkanes of the weeds in the western grasslandsis nC29. The indexes of odd even predominance and carbon advantage of herbaceousplants in the west are obviously lower than those in the east, only the short chaincarbon ratio is all the same with the long chain.(8) Discussing the relationship between the source of the soil n-alkanes and thegrowing vegetative cover. In Jilin Province, distribution of n-alkanes in representativevegetative cover is differ from that in soil under the cover. The abundance differenceof n-alkanes shows that soil organic matter input is a function of biological and thetime factors. The distribution characteristics of n-alkanes in topsoil reveal that theyare affected by the dominant vegetation at present in different degree. There areobvious diversities about the source of n-alkanes among different soil profiles. Thatinfers the differences between the plants in ancient environment and those in moderntimes at the same time reflects the alternation of the plants on the soil and theaffection from the farming activities of human being.