砷是一種有毒的致癌物質(zhì),可以通過巖石風(fēng)化、地?zé)崃黧w、火山噴發(fā)等自然過程,也可以通過含砷農(nóng)藥、除草劑的使用、采礦、工業(yè)廢水的排放、化石燃料的燃燒等人為活動釋放到環(huán)境中。地?zé)崃黧w中砷的濃度一般在1-10 mg/L,有的甚至高達(dá)50 mg/L以上。深部地?zé)崃黧w是一種還原環(huán)境,砷主要以三價砷存在。當(dāng)它上升至地表的過程中遇到淺層富氧的地下水,或者出露地表后的排泄,就會在微生物的作用下被氧氣氧化成五價砷。因而匯集地?zé)崃黧w的地下水或者地表水就會含有較高的砷的濃度,從而構(gòu)成一種潛在的環(huán)境威脅。在過去的十年,地?zé)崃黧w來源砷的遷移和轉(zhuǎn)化及其環(huán)境威脅越來越引起研究者的關(guān)注,并且已經(jīng)在很多國家調(diào)查過,包括美國、加拿大、日本、新西蘭、菲律賓、冰島、法國、西班牙、俄羅斯、土耳其以及像墨西哥、智利等一些拉丁美洲的國家。然而在各種類型熱泉的環(huán)境中,微生物介導(dǎo)砷的環(huán)境地球化學(xué)作用還尚不清楚。本研究選取我國典型的高溫地?zé)崃黧w云南騰沖地?zé)釁^(qū)為研究區(qū),采用地球化學(xué)與微生物分子生態(tài)學(xué)相結(jié)合的方法,分析騰沖地?zé)釁^(qū)砷的地球化學(xué)特征和不同類型熱泉環(huán)境中砷的生物地球化學(xué)作用,調(diào)查砷功能微生物群落的多樣性和豐度,以及研究分離的砷氧化菌作...

【文章頁數(shù)】：128 頁

【學(xué)位級別】：博士

【文章目錄】：
作者簡歷
摘要
Abstract
Chapter 1 Introduction
    1.1 Geothermal arsenic
        1.1.1 Arsenic in the environment
        1.1.2 Arsenic distribution and source in geothermal areas
        1.1.3 Geochemical characteristics of As in geothermal water
        1.1.4 Microbially mediated As transformation in geothermal environments
    1.2 Tengchong geothermal area
    1.3 Objectives of this study
Chapter 2 Arsenic geochemistry in geothermal systems of Tengchong,China
    2.1 Introduction
    2.2 Geological setting of the study area
    2.3 Materials and methods
        2.3.1 Sample collection and preservation
        2.3.2 Hydrochemical and statistical analyses
    2.4 Results and discussion
        2.4.1 Chemical characteristics of geothermal water
        2.4.2 Arsenic geochemical behavior of geothermal water
        2.4.3 Potential mixing of geothermal water and shallow groundwater and derived As environmental risk
    2.5 Summary
Chapter 3 Arsenic biogeochemistry and microbial community at theoutflow of an acid vapor-formed spring
    3.1 Introduction
    3.2 Materials and methods
        3.2.1 Site description
        3.2.2 Field measurements and sample collection
        3.2.3 Laboratory geochemical analysis
        3.2.4 DNA extraction, amplification and sequencing
        3.2.5 Sequence data preprocessing and statistical analysis
    3.3 Results
        3.3.1 Water and sediment geochemistry
        3.3.2 Alpha diversity of microbial communities
        3.3.3 Microbial community compositions
        3.3.4 Microbial community structure statistics
    3.4 Discussion
        3.4.1 Potential As, S and Fe oxidation processes
        3.4.2 Significant environmental factors shaping the microbial community structure
    3.5 Summary
Chapter 4 Arsenic biogeochemistry and microbial community at theoutflow of an alkaline sulfide-rich hot spring
    4.1 Introduction
    4.2 Materials and methods
        4.2.1 Site description
        4.2.2 Field measurements and sample collection
        4.2.3 Laboratory geochemical analysis
        4.2.4 As(Ⅲ) oxidization experiments
        4.2.5 DNA extraction, amplification and sequencing
        4.2.6 Sequence data preprocessing and statistical analysis
    4.3 Results
        4.3.1 Water and sediment geochemistry
        4.3.2 Alpha diversity of microbial communities
        4.3.3 Microbial community compositions
        4.3.4 Microbial community structure statistics
        4.3.5 As(Ⅲ) oxidization and As(Ⅲ) oxidase gene (aioA) diversity
    4.4 Discussion
        4.4.1 Microbially mediated As species transformation
        4.4.2 Significant environmental factors shaping microbial community structure
    4.5 Summary
Chapter 5 Diversity and abundance of the As(Ⅲ) oxidase gene aioA ingeothermal areas of Tengchong, Yunnan, China
    5.1 Introduction
    5.2 Materials and methods
        5.2.1 Site description and sample collection
        5.2.2 Geochemical measurements
        5.2.3 DNA extraction and aioA gene amplification
        5.2.4 Clone library construction and phylogenetic analysis
        5.2.5 qPCR
        5.2.6 Statistical analyses
    5.3 Results
        5.3.1 Geochemistry
        5.3.2 Abundance of aioA and 16S rRNA genes
        5.3.3 Diversity of aioA gene
    5.4 Discussion
        5.4.1 Neutral or alkaline springs contained higher As concentrations than acidic springs
        5.4.2 Abundance of aioA and its correlation with environmental factors
        5.4.3 aioA origin:bacterial or archaeal?
        5.4.4 Different aioA genes in hot springs with different geochemistry
    5.5 Summary
Chapter 6 Isolation and identification of As(Ⅲ) oxidizing bacteria inTengchong geothermal area, China
    6.1 Introduction
    6.2 Materials and Methods
        6.2.1 Site description and sample collection
        6.2.2 Enrichment and isolation
        6.2.3 Phylogenetic analysis
        6.2.4 Physiological characteristics and As(Ⅲ) oxidization
        6.2.5 As(Ⅲ) oxidase assays
    6.3 Results and Discussion
        6.3.1 Isolate characterization and identification
        6.3.2 As(Ⅲ)oxidization
        6.3.3 As(Ⅲ)Oxidase Genes
    6.4 Summary
Chapter 7 Conclusions and suggestions
    7.1 Conclusions
    7.2 Suggestions
Acknowledgements
References



本文編號：3952911