Cover

Half-title

Title

Copyright

Contents

List of contributors

Preface

1 Report Group 1 - Physical processes in the microlayer and the air-sea exchange of trace gases

Surface films

Sources, sinks, and properties of surface films

Surface films and gas exchange

Surface films and bulk material

Extent and viscoelastic properties of surface films

Physical processes in the microlayer

Comparison of surface-renewal and boundary-layer models of near surfacetransfer

Short capillary waves

The relation between heat and mass transfer

Wave breaking and bubbles

The role of bubbles in heat flux

The role of bubbles in gas exchange

The effect of surfactants on bubble-mediated gas exchange

The effects of wave breaking on microlayer composition

Bubble floatation and aerosol formation processes

The effect of rain on exchange processes

Horizontal transport and deposition of surface slicks in coastal zones

Review of experimental data on gas transfer

Gas transfer velocities

Discrepancy between 14C-based and inert gas exchange rates

Do catalysts exist in the microlayer which may enhance CO2 gas exchange?

Review of experimental techniques

'New' techniques for measuring air-sea gas exchange rates

Dual tracer technique

How can we deal with the large spatial variability ofpCQ2?

Controlled flux technique

Are direct measurements of the heat flux possible?

Novel ocean-surface sampling techniques

Parameterization of air-sea exchange processes

Best parameterization for momentum, heat, and material fluxes

Parameterizations including viscoelasticity of the air-sea interface

Conclusions and recommendations

References

2 Report Group 2 - Biological effects of chemical and radiative change in the sea surface

Introduction

Samplers and sampling techniques

The prism-dipping technique

The screen sampler

Plate and drum samplers

Techniques for sampling neuston

Characteristics of the surface microlayer

Enrichment factors

Surface excess concentrations

Variability of organisms and contaminants

Thickness of sea-surface films

Biology of the sea surface

Piconeuston

Nano- and microneuston

Mesozooneuston

Macroneuston

Freshwater neuston

Chemistry in the sea surface

Organic components of natural origin

Organic components of anthropogenic origin

Trace elements

Organotin compounds

Radionudides

Freshwater chemistry

Effects of ultraviolet radiation

Effects of chemical contamination

Effects of greenhouse warming

Global change and the microlayer

Conclusions and recommendations

References

3 Report Group 3 - Photochemistry in the sea-surface microlayer.

Introduction

Photochemistry in the upper ocean

Major photochemical reactions

Photoalteration and photoproducts of CDOM

Hydrocarbon degradation

Probable photochemical processes in the microlayer

In situ trace gas production

Atmospheric inputs of trace species

In situ halogen chemistry

Conversion of DOC

Hydrocarbon degradation

Global change issues

Changes in ultraviolet radiation

Radiation balance

Conclusions and recommendations

References

4 Transport processes in the sea-surface microlayer

Abstract

Introduction

Basic concepts

Equations of motion and boundary conditions

Secondary motions: polygonal cells and helicoidal rolls

Secondary motions: surface drift, waves, and wave breaking

Surface streaming

Observations of surface streaming

Assessment

Influence of rain

Salinity

Momentum transfer

Rain-induced turbulence and wave damping

Heatflux

Experimental studies of the microlayer: miscellaneous techniques

Early investigations

Turbulence generation at the boundary

Radon evasion technique

Velocity profiles near the interface

Temperature profiles at the interface

Forced heat flow technique

Conclusion

References

5 The role of organic films in air-sea gas exchange

Abstract

Introduction

The microlayer and air-sea processes

Air-sea gas exchange

The role ofbiogenous organic matter

Surface-active matter in the marine microlayer

Sources and chemical nature

Surface physical properties

Surfactants and mechanisms of gas exchange

Static versus dynamic effects of surfactant films

Physical models of air-water gas transfer

Experimental studies of films in stirred systems

Experimental studies of films in wind-wave systems

Influence of waves on gas exchange

Gas exchange in the presence of films

Influence of surfactants on the wave field

Concluding remarks

Acknowledgments

References

6 Bubbles and their role in gas exchange

Abstract

Introduction

Mechanisms of air-sea gas transfer

Properties of bubble-mediated transfer

The oceanic distribution of bubbles

Estimates of bubble-mediated gas transfer

Discussion

Summary

References

7 The physical chemistry of air-sea gas exchange

Abstract

Introduction

Thermodynamics: the steady-state model

Kinetics: 1. A surface-renewal model

Kinetics: 2. Incorporation of a turbulent air layer

Comparison of theory and experiment

General comments

Detailed comparison with the data ofLiss et al. (1981)

Detailed comparison with data of Smith and Jones (1985)

Detailed comparison with data of Smith et al. (1991)

Conclusions

Acknowledgments

References

8 The sea-surface microlayer and its effect on global air-sea gas transfer

Abstract

Introduction

Motivation and purpose

Background information on surfactants in the microlayer

Processes affecting gas transfer

Air-sea gas exchange background

Barrier effects and changes in ∆PX> Scy and Kh

Hydrodynamic effects

Breaking waves and the microlayer

Microlayer effects on global fluxes

Description of model

Global air-sea CO2 flux

NH3flux in the Pacific Ocean

Conclusions, implications for further research

Acknowledgements

References

9 Chemistry of the sea-surface microlayer

Abstract

Prologue

Methods for sampling the microlayer

The screen sampler

The glass plate sampler

Hydrophobic samplers

Rotating drum samplers

The prism-dipping method

The bubble microtome

Enrichment factors and microlayer thickness

Enrichment factor EF

Surface excess concentration

Organic chemical composition of the microlayer

Lipids and hydrocarbons

Dissolved and particulate organic carbon

Plant pigments

Organic pollutants

UV absorption and fluorescence

Electrochemical methods

Trace elements in the microlayer

Dissolved trace elements

Major cations of seawater

Particulate trace metals

Physico-chemical properties of sea-surface films

Sea slicks y capillary waves and film pressures

Film pressure-area measurements

Epilogue

References

10 Biophysics of the surface film of aquatic ecosystems

Abstract

Introduction

Experimental studies

Effects of surf ace-living organisms

References

11 Biological effects of chemicals in the sea-surface microlayer

Abstract

The aquatic surface layer

Sea-surface sample collection

Membrane filter:

Glass plate:

Screen:

Pump:

Nets:

Biology of the aquatic surface layer

Piconeuston

Autotrophic nano- and microneuston

Heterotrophic nano- and microneuston

Mesozooneuston

Macroneuston

Anthropogenic chemical enrichment of the sea surface

Sources of contamination

Metals

Radio nuclides

Organics

Biological effects of sea-surface contamination

Effects on intertidal biota

Effects on fish eggs and larvae

Effects on microneuston and gas exchange

Relation of effects to visible slicks

Global effects of sea-surface stress

Summary

References

12 Neuston of seas and oceans

Abstract

Introduction

The extreme surface of the sea as a specific habitat

Neuston and pleuston communities of marine organisms adapted to specific life conditions in the uppermost sea layer

Structure and taxonomic composition of the neuston

Numbers ofneustonic organisms

Neuston as a connecting link in the biosphere

Anthropogenic influences on neuston

Neuston as a factor influencing the air-sea exchange

Acknowledgements

References

13 Photochemistry in the sea-surface microlayer

Abstract

Introduction

Optical properties of microlayer and bulk-water chromophores

Photochemical reactions

Singlet dioxygen (1O2; 1∆g)

Superoxide/hydroperoxyl radical (O2~/HO2)

Hydrogen peroxide (H2O2)

Hydroxyl radical (OH)

Peroxy radicals (RO2)

Low molecular weight organic compounds and trace gases

Trace metals (Fe, Mn)

Estimated production rates and fluxes of photochemical species in the microlayer

Concluding remarks

Acknowledgements

References

14 Hydrocarbon breakdown in the sea-surface microlayer

Abstract

Microlayer samplers

Compound groups found in the microlayer

Sources and sinks of hydrocarbons in the microlayer

Sensitized photooxidation of hydrocarbons

Model experiments and natural phenomena

References

15 Applications of laser technology and laser spectroscopy in studies of the ocean microlayer

Abstract

Introduction

Laser-induced fluorescence probes

The scanning laser slope gauge

Nonlinear optical probes of the ocean surface

Conclusions

Acknowledgements

References

16 Remote sensing of the sea-surface microlayer

Abstract

Introduction

Sea-surface parameters observed by remote sensing

Temperature

Surface roughness

Ocean colour

Sampling length and timescales of remote sensing observations

Spatial scales

Temporal sampling scales

Infrared measurements of ocean surface temperature

The thermal skin effect

Radiometric observations of the thermal skin

Calibration of global SST measurements

Evidence of surface processes from infrared images

Radar measurements of surface roughness

Surface winds

Waves and swell

Surface slicks

Other dynamical features imaged by SAR

Extending remote sensing contributions to sea-surface microlayer studies

Air-sea fluxes

Spatial patterns in images

New in situ instrumentation

Conclusion

Acknowledgements

References

Index