Ammonia adsorption

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Table of contents

Chapter I State of the art
1. Overview of the Critical Zone (CZ)
1.1 Current state of CZ
Definition
Compartments and interacts within the CZ
Interactions within CZ
Influence of CZ on the environment
Critical Zone Observatories (CZO)
1.2 Agriculture in the CZ
Share of land use and cover
Land occupation types in France
Fertilizer input
Pesticide input
Consequences of intensively agricultural activities
1.3 Constructed wetlands and ponds in agricultural catchments
Definition of catchments, constructed wetlands, constructed ponds, and sediments
History and types of CWs
Effects of CWs on contaminants
2. Nitrogen in aquatic ecosystem
2.1 Nitrogen in biogeochemical cycle
Fixation
Volatilization
Ammonification
Nitrification
Nitrate reduction
Assimilation and plant uptake
Ammonia adsorption
Organic nitrogen burial and accretion
Anaerobic ammonium oxidation
2.2 Nitrate transfer, transformation, and controlling factors
Anthropogenic sources of nitrogen
Nitrate transfer from soil to water
Nitrate removal pathways in aquatic system
3. Potential toxic metals (PTE) in sediments
3.1 Brief of sediments
3.2 Characteristics and toxicity of PTEs
3.3 Sources of PTEs in agricultural soils and sediments
Natural source
Anthropogenic source
3.4 Anthropogenic PTE transportation and distribution in sediments
From soil to sediment
Major pathways and controlling factors
Chapter II Materials and methods
Introduction
1. Sampling site
1.1 Pond selection
1.2 Catchment and pond descriptions
Catchment characteristics
Pond characteristics
2. Sampling strategies
2.1 Water
2.2 Sediment
3. Physicochemical and biological analyses
3.1 Water
Basic physicochemical analyses
Stable isotopes
3.2 Sediment
Physicochemical analyses
Denitrification analyses
Total digestion
single EDTA extraction
Metal analyses
Molecular analysis
4. Data analyses
Chapter III Role of constructed ponds in denitrification and nitrate behavior: key controlling factors in streams
and ponds at a catchment scale
Introduction
Materials and methods
Part I. Denitrification and its controlling factors
1. Results
1.1 Water characteristics
1.2 Sediment characteristics
Physicochemical characteristics
Potential denitrification rate (PDR)
1.3 Relationships between variables
Principal component analysis (PCA)
Relationship between PDR and N2O emission rate
1.4 qPCR assay for denitrification genes in pond sediments
1.5 Multilinear regression model for PDR
2. Discussion
2.1 PDR magnitude and spatial variation
2.2 Controlling factors of PDR
2.3 Predictive models and interest from a management perspective
Part II. Nitrate behavior and the role of ponds
1. Results
1.1 NO3
– concentration, discharge, and NO3
– flux patterns
1.2 Stable isotopes
1.3 Multilinear regression model for NO3
– removal efficiency
2. Discussion
Summary
Chapter IV Influence of ponds on hazardous metal distribution in sediments at a catchment scale (agricultural critical zone, S-W France)
Introduction
1. Materials and methods
1.1 Geoaccumulation index (Igeo)
1.2 Enrichment factor (EF)
1.3 Anthropogenic contribution (AC, %)
1.4 Statistical analysis
2. Results
2.1 Concentrations of major elements and eight potential toxic elements (PTE) in sediments
2.2 Sediment texture
2.3 Contamination indices
Geoaccumulation index (Igeo)
Enrichment factor (EF)
2.4 Principal component analysis (PCA) and correlation matrix (CM)
All sediments
Stream sediments
Pond sediments
2.5 EDTA extraction
3. Discussion
3.1 Natural vs. anthropogenic origins of PTEs in sediments, and their distributions
3.2 Distribution of PTE concentration and its controlling factors
3.3 Availability of PTE in sediments
3.4 Effect of ponds on PTE transfer in catchments
Summary
Chapter V Role of ponds in mitigating contaminants (nitrate and trace metals): a synthetical study in agricultural critical zone (southwestern France)
Introduction
1. Materials and methods
1.1 Multi-element contamination indices
Contamination degree (CD)
Modified contamination degree (mCD)
Pollution load index (PLI)
Nemerow’s pollution index (PI)
Modified pollution index (mPI)
Potential ecological risk index (PERI)
1.2 Sediment quality guidelines (SQGs)
1.3 Statistical analysis
2. Results and discussion
2.1 Overall metal contamination in sediments
Integrated contamination magnitude
Potential ecological risk in sediments and the effect of metal contamination on
denitrification
2.2 Role of ponds in types of contaminants simultaneously
All sediments
Stream and pond sediments
Summary
Conclusions and perspectives
References