Dissertation > Excellent graduate degree dissertation topics show

Regional Study on Soil Polycyclic Aromatic Hydrocarbons in Liaoning: Patterns, Sources and Cancer Risks

Author: WangZhen
Tutor: ChenJingWen
School: Dalian University of Technology
Course: Environmental Engineering
Keywords: PAHs Soil Factor analysis with nonnegative constraints Probabilistic cancer risk assessment Source apportionment Dalian
CLC: X503
Type: PhD thesis
Year: 2007
Downloads: 1251
Quote: 6
Read: Download Dissertation


Polycyclic aromatic hydrocarbons (PAils), a group of ubiquitous persistent toxic substances possessing carcinogenic, mutagenic and immunotoxic properties, have become an issue of increasing concern in recent decades. PAHs are mainly originated from incomplete combustion of fossil fuel and biomass. PAHs tend to be strongly adsorbed to soil and are difficult to dissipate owing to their high octonal-water partition coefficients. Due to its high storage capacity, soil is considered as a major environmental reservoir for PAils. Liaoning province is one of typical traditional industrial bases in China. Over the last century, increases in population and industry in the region have resulted in high consumption of fuel. In addition, biomass burning is a traditional practice for heating and cooking in rural areas. Thus, it is expected that Liaoning suffered from severe PAHs pollution. However, the studies on PAHs in this area are very limited: So the investigation on PAH levels in soils is very important to understand the spatial distribution, sources, character of composition of PAils and risks on the ecological and human health.The levels and distributions of PAHs in Dalian soils were investigated. The PAH concentrations were high and/or comparable with other regions. Soil PAH concentrations showed an urban - suburban - rural gradient, with total concentrations up to 30 times higher in the urban areas than those in the rural areas. PAHs with 4-ring were dominated in the urban soils, while 3-ring PAHs in the rural areas. The composition profiles of PAHs also displayed the urban - suburban - rural gradient owing to their different transport potential. The cross plots of selected diagnostic ratios distinguished the four sampling areas, and suggested that soil PAHs were mainly from traffic emission in the urban areas and coal/wood combustion in the suburban and rural areas. The study also highlighted that benzo(a)pyrene (BaP) was a good indicator for assessing the potential toxicity of PAHs, and presented a promising toxicity assessment method for soil PAHs.For Liaoning soils, more than 50% of the samples were moderately and/or severely polluted with PAHs, and about 40% were weakly polluted. The high proportion of phenanthrene (Phe) in soil PAHs (16.3% on average) was observed in Liaoning. The results of Pearson correlation analysis and diagnostic ratios indicated that soil PAHs in the study area were mainly from the mixture of several sources with the characters of incomplete combustion of coal and biomass.An improved method, factor analysis with nonnegative constraints (FA-NNC) was employed to determine the primary sources of soil PAHs in Dalian and Liaoning based on the measured PAH concentrations. The FA-NNC model showed traffic average and coal related residential emission were two primary sources to Dalian soils, accounting for 74% and 26% of∑PAHs, respectively. In Liaoning, four primary sources were identified: coal combustion, coke oven, biomass burning and a labeled "other" source that may be a mixture profile. The contributions of these sources were quantified as 50.5% from coal combustion, 27.0% from coke oven, 19.4% from biomass burning and 3.1% from the "other" source.The incremental lifetime cancer risk (ILCR) of soil PAHs in Dalian were estimated employing the method of probabilistic risk assessment (PRA). For dermal contact and soil ingestion, the ILCRs of 90% cumulative probability were over 10-6, which indicated the potential cancer risk, while for soil particulate inhalation, the ILCR was below 10-6, revealing the cancer risk can be neglected: Due to various body weight and habits, there were differences between the ILCRs for children, adolescents and adults. The results of sensitivity analysis indicated that the most influential parameters were the BaP-based concentrations of soil PAHs and fraction skin area exposed (FE), which suggested that, to reduce the uncertainties of risk assessment, it was necessary to reduce the uncertainties of PAH concentrations and FE.

Related Dissertations

  1. Study on the Improvement Depth of Dynamic Consolidation by Methods of Mathematical Physics,TU472.31
  2. Effect of Soil Erosion on Soil Quality in the Cultivated Slope Land on the Loess Plateau, China,S157.1
  3. Cloning, Expression and Functional Analysis of STOP1 Transcriptional Factor,S336
  4. Effects of the Exotic Invasive Plant Solidago Canadensis L. on the Community Structure of Soil Anmals,S451
  5. Lijiang River,RS and GIS - based Soil Erosion Research,S157
  6. Effects of Enzymes on Metabolism of Polycyclic Aromatic Hydrocarbons in Plant,X173
  7. Activation of Polycyclic Aromatic Hydrocarbons in Soils by Root Exudate and Its Components,X53
  8. Study on Nitrogen Removal by Soil Aquifer Treatment Process That Enhanced Nature Reoxygenation and Effective Volume,X703
  9. Risk Analysis and Mitigation Experiment of Heavy Metal Pollution in Croplands in Vicinity of Pollution Sources,X820.4
  10. Preparation of the Crop Stalk-Based Shaped Activated Carbons and Fibreboard,X712
  11. Preparation of Crop Stalk-Based Sorption Materials with High Performances and Their Applications for Pah Removal from Water,X712
  12. Subarea Management of Tobacco Soil Nutrients and Adequate Fertilization Research by Micro Scale,S158
  13. Soil Organic Carbon Fractions and Its Dynamic in Different Soil Types of Wuyi Mountains,S153.6
  14. Research on Rainfall Erosivity in Jiangsu Province,S157.1
  15. Effect of Black Carbon Addition on Soil Organic Carbon Decomposition,S153.6
  16. A Research on Determinating Soil Types and Soil Boundaries under Chinese Soil Taxonomy,S155
  17. The Comprehensive Evaluation of Flue-cured Tobacco Origin Place Environment and Tobacco Leaf of Fangxian,S572
  18. Theanalysis of Harmfulness Factors about Heavy Metals in the Course of Beef Cattle Feeding,S823
  19. Effects of N Addition on Soil Soluble Nitrogen and CH4 Oxidation of Upland in Subtropical,S714
  20. Influence of Biochar Amendments on Decomposition of Soil Organic Carbon and Morphology of Heavy Metal in Red Paddy Soil,S153.6
  21. A Basic Study on the Microbial Mechanism of Soil Organic Carbon Accumulation Structures under Different Fertilization Treatments of Long-Term Argo-Ecosystem Experiments,S158

CLC: > Environmental science, safety science > Environmental pollution and its prevention > General issues > The hazards of environmental pollution
© 2012 www.DissertationTopic.Net  Mobile