Study On The Distribution Of PAHs And N-alkanes In The Soil From North Lake Area Of Wuhan

This subject based on the task of China University of Geosciences(Wuhan)Key Laboratory of Biological & Enviromental Geology of Ministry of Education research for the Open fund. this paper researched the collected 34 surface soil of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes (n-alkane) in the North Lake area of Wuhan,and based on this,analyzes the distribution and the source of polycyclic aromatic hydrocarbons and n-alkanes in soil of North Lake area, also made ecological risk and health risk assessment of PAHs.The traditional Soxhlet extractor is used for the extraction of Polycyclic aromatic hydrocarbons and n-alkanes in the samples, Purified by column chromatography, and GC-MS is used to finish the quality and quantity, quantitative analysis method on PAHs and qualitative analysis method on n-alkanes.Test showed that there are 16 priority control PAHs and n-C12 to n-C33 n-alkanes about 22 kinds of compounds in samples , The average recovery rate of PAHs is about 86%; according to the NIST mass spectrum could calculat the relative content of n-alkanes, which have received good results.The content of PAHs in the soil is in the range of 119.7-29844 ng/g, the overall average is 4114.2ng/g, much higher than the natural background value which is 1-10 ng/g, Analysis of 16 priority control PAHs, in addition indeno (1,2,3-d) pyrene, dibenzo (a, h) anthracene, benzo [g, h, i] perylene were 88.2% detection rate , The remaining compounds were 100% detection rate, showing that PAHs contaminated soil in the study area has been very popular and level of soil pollution differ greatly in different locations. Compare domestic and foreign similar regional pollution of PAHs in soil PAHs in soil, The pollution is more serious in study area.The results show that the source of PAHs in the study area mainly from burning fossil fuels or grass / wood / coal burning, atmospheric deposition may be the most important way to lead to pollution of PAHs in the study area.Ecological risk and health risk assessment results show that the ecological risk of PAHs in the North Lake area soil at a moderate level, but the local area has a potential ecological risks, and appropriate control measures must be taken; cancer risk is currently within acceptable limits in the soil of North Lake area.N-alkanes distribution range of C12-C33 in soil of North Lake area in Wuhan, the sampling points 0-5cm and 5-20cm soil layers relative content of n-alkanes in the same tendency, indicating that the the n-aklanes have the same source.Results show that bimodal distribution in the Most of sampling points, the low carbon peak locates at C17 with no odd-even predominance,and the high carbon peak is at C27 or C29 with an odd even predominance, there is parity distribution advantages, few carbon peak locates at C17 or C18 and C24 or C31.According to samples taken from different soil and source of n-alkanes, we can draw the conclusion that the n-alkanes mainly from higher plant wax in the farmland soil of the North Lake area, this is due to agricultural cultivation of rice and canola, the rest comes from the incomplete combustion of fossil fuels,then reaches the ground by means of dry deposition input.sources of n-alkanes in the slopes and vegetable plots are basically the same as the agricultural land, n-alkanes from fossil fuel combustion have became weakened; Sandy soil near the Yangtze River affected by many factors, and there is clear evidence that the n-alkanes may come from petroleum hydrocarbons and lower organisms.