土壤中石油烴的遷移轉(zhuǎn)化及其在修復(fù)中的應(yīng)用.pdf

1、China is now recognized as one of the most seriously eroded (water,wind erosion and desertification,as well as land contamination) countries in the world.Several manufacturing facilities,mainly from the chemical and stee

2、l industry,are moved out of the cities which left behind heavily contaminated sites for urban development.Further to this,China has a numberof environmental challenges to address as part of its 12th five-year plan, and c

3、ontaminated land has been highlighted as an immediate priority.In Europe Union (EU),site remediation has been carried out for three decades and still over1,000 km2 is subjected to?land take every year for industry,housin

4、g, roads or recreationalpurposes.Therefore,China and EU are potentially strong markets for contaminated site remediation and redevelopment services.
　　We have more than 30 years of research on contaminated site remedi

5、ation and we are now focusing on key indicator compounds based on their toxicity rather than the overall pollutant load in soil.There has been also acknowledged that we still need a better understanding of environmental

6、chemical fate of pollutants and better integrated management frameworkfor contaminated land. The clean-upand restoration of contaminated sitesis further moving towards sustainable and green remediation,which means that n

7、ot only remediation technical factors and performance are being considered, but also life-cycle costs and social and economic benefits.So,there are still some gaps that need to be further investigated:
　　(1)the fate a

8、nd transport of specific chemicals (risk indicator compounds) in different types of soil;
　　(2)the influences of the remediation activities on the soil environment;and;
　　(3) the energy consumption and greenhouse g

9、as (GHG) emission involved in the remediation.
　　The aim of this thesis is to investigate the fate and transport of petroleum hydrocarbons in soils and to better inform remediation strategy. The objectives of this the

10、sis are:
　　(1)to study the leaching ability of petroleum hydrocarbons in chalk;
　　(2)to investigate the effects of soil ozonation on the petroleum hydrocarbons affected soil;
　　(3)to evaluate the influences of c

11、omposting conditions on the petroleum hydrocarbons degradation; and;
　　(4)to estimate the energy consumption and GHG emissions during soil ozonation and composting.
　　In Chapter 1,the contaminated site conditi

12、ons in China and Europe,the fate and transport of contaminantsin soil,and the soil remediation approaches have reviewed.Oil products are complex mixture of hydrocarbons and they can be found in various environmental matr

13、ices.Therefore the generic remediation approach is not always adequate and there is a need for a more mechanistic and site specific approach.
　　Chapter 2is investigating a specific site context, chalk which is the lar

14、gest aquifer source in UK and is exposed to the petroleum hydrocarbons from the leaking underground storage tanks (USTs).So it is importantto study the transport of aliphatic and aromatic hydrocarbon fractions (mainly al

15、kanes and polycyclic aromatic hydrocarbons (PAH) ranging between C10 and C35)in chalk subsoil.Theinfluence of different chalk‘s particle sizes,on the behaviour of the hydrocarbon fractions was investigated using batch le

16、aching column test.Thekey findings are both the aliphaticand aromatic hydrocarbon fractions showed little tendency to transport downward and were mainly trapped in the top 10 cm layer after 60 days of leaching.Meanwhile,

17、the concentrations of target alkanes and PAH compounds were below the lower detection limit(LDL)in the leachate samples.Additionally,the chalk-water distribution property of n-alkanesand PAH increases with the chalk part

18、icle sizes.Petroleum hydrocarbonsfate and transport modelling in thesoil indicate the 99％ of the n-alkanes and PAHs were trapped within the soil system after 1000 days of leaching.The soil organic carbon content retarded

19、 the migration of petroleum hydrocarbons.MonteCarlo analysis demonstrate that environmental parameters uncertainties especially organic carbon content,water infiltration rate and initial mass of the hydrocarbons,greatly

20、influence the transport of petroleum hydrocarbons (as high as 52%). These results show that the site contamination is not only related to amount of contaminants,but also depends on the physicochemical properties of conta

21、minants and chalk.The low solubilityand high distribution coefficient of the alkanes and PAHs indicate thatis could be useful to reduce the deep located samples taken in contaminatedsite investigation and reduce the ener

22、gy consumption correspondingly.Long period remediation approaches,such as monitored natural attenuation could be applied to clean up the petroleum hydrocarbons affected chalk.
　　The leaking UST is one of the main envi

23、ronmental issues with the growing industrial development especially in China.In the following chapter,Chapter 3,the influences of ozone (O3)concentration, sand grain size and water content on the hydroxylation of n-

24、alkanes and PAHs have been evaluated.The soil ozonation was found to be effective when applied with a concentration>30 mg L-1 for initial diesel concentration of 25,000 mg kg-1.Higher ozonation (O3) efficiency was observ

25、ed in the smaller grain size samples.Water content had little influence on the residual hydrocarbon fractions of the diesel,whichindicates O3 will work relative wellboth in the dry and wet conditions.During soil ozonatio

26、n,aldehydes and carboxylic acids were formed as by-products and reached a concentration 12.7 mg kg-1 of and 80 mg kg-1,respectively, within 20 h.After being exposed to O3 20 h,the soil pH decreasedto3.Therefore,formaldeh

27、yde concentration should be monitored during ozonation and background heavy metal concentration should be analyzed before the remediation process to avoid being inhaled by the remediation constructors and increasing the

28、migration ability of the heavy metals.
　　As the requirement of green remediation,we need to integrate environment,society and economic aspects into remediation project.There is growing interest and use of compost amen

29、dment to contaminated soil as it has been shown that compost can bring nutrients and microorganisms to degrade the petroleum hydrocarbons in soil.In Chapter 4,soil-based compost and spent mushroom compost substrate compo

30、st were added to soil contaminated with 5000 mg kg-1 crude oil to investigate the effect of composting conditions on the degradation ofn-alkanes and PAHs.The composts greatly enhanced the biodegradation of n-alkanes and

31、PAHs by more than 2 and 15 times compared to the unamended contaminated soil in 42 days. After 42 days, the residual concentration of n-alkanes and PAHs was less than 38 mgkg-1 and 0.3 mg kg-1.Principle Component Analysi

32、s (PCA)indicates that the water solubility and weekly tillage were negatively correlated with the residual hydrocarbons concentrations,while partition coefficient,molecular weight of the hydrocarbons were positively corr

33、elated with the residual hydrocarbons concentrations. This finding suggests thatthe degradation of alkanes and PAHs can be enhanced by increasing the aeration.The soil composting modelling results fitwell with the experi

34、ment data in theinitial 7 days, while the deviation increases as the composting time increases.
　　Besides remediation treatment efficiency,it is also important to consider the energy consumption and gas emissions invo

35、lved in the remediation activities.Therefore in Chapter 5,the energy consumption and air footprint of soil ozonation and soil composting were investigated using the Spreadsheets for Environmental Footprint Analysis

36、(SEFA) tool.In soil ozonation,93%of the diesel was consumed by the generator while insoil composting,78% of the dieselwas consumed by transport of the compost.The total energy consumption and off gas emission of soil ozo

37、nationwere 42%and 26%less than those in soil composting.Laboratory analysis contributes to more than 60% for the GHG emissions in these two approaches.To reduce the GHG emissions,mobile analytical lab on site could be ap