當(dāng)前沿海地區(qū)可持續(xù)地提供多樣的生態(tài)系統(tǒng)服務(wù)受到日益關(guān)注,導(dǎo)致全球范圍內(nèi)越來越多的沿海地區(qū)正在經(jīng)歷快速的城市化進(jìn)程,進(jìn)而帶來環(huán)境氮(N)污染問題。由于氮飽和度將對沿海生態(tài)系統(tǒng)及其相關(guān)服務(wù)產(chǎn)生特別深遠(yuǎn)的影響,因而了解其如何應(yīng)對不斷增長的城市化進(jìn)程是重要的。盡管先前的研究已經(jīng)調(diào)查了城市化對全球不同生態(tài)系統(tǒng)中氮飽和度模式的影響,但這些研究結(jié)果揭示了不同城市化研究結(jié)果具有相互沖突的格局(增加,減少或沒有明確的模式)。因此,了解氮污染的潛在機(jī)制及其對沿海生態(tài)系統(tǒng)影響具有重要的生態(tài)學(xué)和社會意義。本文以中國南部福州閩江口流經(jīng)市區(qū)的白龍江(BJR)和郊區(qū)的烏龍江(WJR)河岸森林為研究對象,研究城市化對氮污染的影響及N元素在森林-大氣-地表水的生物地球化學(xué)循環(huán)。具體研究內(nèi)容和結(jié)果如下:(1)基于¹⁵N穩(wěn)定同位素技術(shù),探索沿BJR和WJR的亞熱帶沿岸森林土壤N有效性和循環(huán)模式。本研究內(nèi)容分析了不同土層土壤、葉片的氮變量,包括土壤和葉片的氮濃度,同位素豐度以及土壤氮礦化速率。BJR森林的土壤總氮濃度,無機(jī)氮濃度(銨和硝酸鹽),氮礦化速率(凈氮礦化和凈硝化)和土壤δ¹⁵

【文章頁數(shù)】：118 頁

【學(xué)位級別】：博士

【文章目錄】：
Dedication
List of Abbreviations and Acronyms
摘要
Abstract
1 General introduction
    1.1 Coastal areas are a magnet for people from non-coastal areas
    1.2 Urbanization of coastal areas around the world
    1.3 Urbanization of coastal areas across China
    1.4 Urbanization and nitrogen pollution globally,across China and in coastal areas
        1.4.1 Atmospheric nitrogen deposition to terrestrial and aquatic ecosystems in relation to urbanization
        1.4.2 Urbanization as an influence on nitrogen pollution in forest ecosystems
        1.4.3 Nitrogen pollution of river ecosystems as a consequence of urbanization
    1.5 Study rationale,objectives,questions and technical route
        1.5.1 Study rationale
        1.5.2 Study objectives
        1.5.3 Study questions
        1.5.4 Study technical route
    1.6 Thesis structure
2 Differential patterns of nitrogen and δ ¹⁵N in soil and foliar along two urbanized rivers in a subtropical coastal city of southern China
    2.1 Introduction
    2.2 Materials and Methods
        2.2.1 Study site descriptions
        2.2.2 Collection and pre-treatment of plant and soil samples
        2.2.3 Chemical and δ ¹⁵N analysis of plant and soil samples
        2.2.4 Statistical analysis
    2.3 Results
        2.3.1 Soil p H,N contents,and net N mineralization and nitrification rates
        2.3.2 Soil ¹⁵N natural abundance,and plant N concentration and ¹⁵N natural abundance
        2.3.3 Relationships of soilδ ¹⁵N and soil N availability and plantδ ¹⁵N
    2.4 Discussion
        2.4.1 Effect of urbanization on soil N contents and N transformation rates
        2.4.2 Effect of urbanization on soil and foliarδ ¹⁵N
    2.5 Conclusions
3 Soil carbon and nitrogen availability are key determinants of soil microbial biomass and respiration in forests along urbanized rivers of southern China
    3.1 Introduction
    3.2 Materials and Methods
        3.2.1 Study sites
        3.2.2 Soil sampling and treatment
        3.2.3 Chemical analysis of soil samples
        3.2.4 Statistical analysis
    3.3 Results
        3.3.1 Soil chemical properties
        3.3.2 Soil microbial biomass and microbial quotient
        3.3.3 Soil microbial respiration rate and metabolic quotient
        3.3.4 Correlations between soil chemical and microbial properties
    3.4 Discussion
    3.5 Conclusions
4 Increasing importance of nitrate-nitrogen and organic nitrogen concentrations in bulk and throughfall precipitation across urban forests in southern China
    4.1 Introduction
    4.2 Materials and Methods
        4.2.1 Study sites
        4.2.2 Sample collections and laboratory analysis
        4.2.3 Data analysis
    4.3 Results
        4.3.1 Patterns of nitrogen concentrations in BP and TP across rivers and seasons
        4.3.2 Relationships between precipitation,soil and foliar N variables
    4.4 Discussion
    4.5 Conclusions
5 Patterns of nitrogen concentrations and their controls in two southern China urban river ecosystems
    5.1 Introduction
    5.2 Materials and Methods
        5.2.1 Study site descriptions
        5.2.2 Sampling procedures and analytical methods
        5.2.3 Statistical analysis
    5.3 Results
        5.3.1 Spatial pattern of nitrogen concentrations in river waters
        5.3.2 Temporal pattern of nitrogen concentrations in river waters
        5.3.3 Relationships between surface water,precipitation and soil N variables
    5.4 Discussion
    5.5 Conclusions
6 Conclusions and recommendations
    6.1 Conclusions
    6.2 Recommendations
        6.2.1 Management options to reduce nitrogen pollution in urban areas
        6.2.2 Future research perspectives
References
Biographical Sketch
Published papers and other Academic Achievements during the Program
Preface and Acknowledgements



本文編號：3985291