VIII
Contents
2-402 Concentrations of Nitrate and Ammonium in the
Marine Atmosphere ................................................... 61
2.4.3 Nitrate and Ammonium Aerosol Propertie ............................ 61
2.4.4 Organic Nitrogen Aerosol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62
2-405 Trends in Nitrate and Ammonium in Pollution AerosoL ............... 62
2.4.6 Atmospheric Deposition and the Nitrogen-Nutrient Budget
in the Ocean .......................................................... 63
2.5 Mineral Dust in the Marine Atmosphere ..................................... 64
2.5.1 Global Distribution of Dust ........................................... 64
2.5.2 Sources of Dust ....................................................... 65
2.5.3 Elemental Composition ............................................... 67
2.5.4 Mineralogical Composition ........................................... 70
2.5.5 Deposition of Dust to the Oceans ..................................... 70
2.5.6 Impact of Dust on Marine Biogeochemistry Cycles .................... 72
2.5.7 The Impact of Mrican Deposition on the Nutrient Cycle ............ " 72
2.6 Other Aerosol Species and the Impact of Continental Source. . . . . . . . . . . . . . . .. 74
2.7 Conclusions ................................................................. 76
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 77
3
Photochemical Processes in the Euphotic Zone of Sea Water:
Progress and Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83
3.2 General Framework ........................................................ " 84
3.2.1 Solar Flux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 84
3.2.2 Light Attenuation ..................................................... 84
3.2.3 Factors Influencing Photoreactions ................................... 86
3.3 Main Photoprocesses Occurring in Water and Air. . . . . . . . . . . . . . . . . . . . . . . . . . .. 87
3.3-1 Direct Photolysis .................................................... " 87
3.3.2 Indirect Photoreactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 88
3.4 Role of Iron and Chlorine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 95
3-401 Inorganic CI Formation in the Marine Environment .................. 95
3.4.2 Role ofIron in Surface Waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 96
3.4.3 Interactions Between Iron and Chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 99
References. . ..... . . .... . . . ..... . . .... . . . .... . . . ... . . . . . ..... . . .... . . ....... 102
4
Sedimentary Organic Matter Preservation and
Atmospheric O 2 Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 105
4.2 Global Cycles of Carbon and Oxygen ...................................... 106
4.3 Organic Matter Preservation and Sediment Texture........................ 108
4-4 Oxygen Effects on Sedimentary Preservation.............................. 110
4.5 Maintaining Atmospheric O 2 within Safe Bounds.......................... 114
4.6 The Mineral Conveyer Belt and Sedimentary Afterburner. . . . . . . . . . . . . . . . . . 119
Acknowledgements........................................................ 121
References ..................................................... '" . . . ...... 121
Contents
2-402 Concentrations of Nitrate and Ammonium in the
Marine Atmosphere ................................................... 61
2.4.3 Nitrate and Ammonium Aerosol Propertie ............................ 61
2.4.4 Organic Nitrogen Aerosol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62
2-405 Trends in Nitrate and Ammonium in Pollution AerosoL ............... 62
2.4.6 Atmospheric Deposition and the Nitrogen-Nutrient Budget
in the Ocean .......................................................... 63
2.5 Mineral Dust in the Marine Atmosphere ..................................... 64
2.5.1 Global Distribution of Dust ........................................... 64
2.5.2 Sources of Dust ....................................................... 65
2.5.3 Elemental Composition ............................................... 67
2.5.4 Mineralogical Composition ........................................... 70
2.5.5 Deposition of Dust to the Oceans ..................................... 70
2.5.6 Impact of Dust on Marine Biogeochemistry Cycles .................... 72
2.5.7 The Impact of Mrican Deposition on the Nutrient Cycle ............ " 72
2.6 Other Aerosol Species and the Impact of Continental Source. . . . . . . . . . . . . . . .. 74
2.7 Conclusions ................................................................. 76
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 77
3
Photochemical Processes in the Euphotic Zone of Sea Water:
Progress and Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83
3.2 General Framework ........................................................ " 84
3.2.1 Solar Flux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 84
3.2.2 Light Attenuation ..................................................... 84
3.2.3 Factors Influencing Photoreactions ................................... 86
3.3 Main Photoprocesses Occurring in Water and Air. . . . . . . . . . . . . . . . . . . . . . . . . . .. 87
3.3-1 Direct Photolysis .................................................... " 87
3.3.2 Indirect Photoreactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 88
3.4 Role of Iron and Chlorine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 95
3-401 Inorganic CI Formation in the Marine Environment .................. 95
3.4.2 Role ofIron in Surface Waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 96
3.4.3 Interactions Between Iron and Chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 99
References. . ..... . . .... . . . ..... . . .... . . . .... . . . ... . . . . . ..... . . .... . . ....... 102
4
Sedimentary Organic Matter Preservation and
Atmospheric O 2 Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 105
4.2 Global Cycles of Carbon and Oxygen ...................................... 106
4.3 Organic Matter Preservation and Sediment Texture........................ 108
4-4 Oxygen Effects on Sedimentary Preservation.............................. 110
4.5 Maintaining Atmospheric O 2 within Safe Bounds.......................... 114
4.6 The Mineral Conveyer Belt and Sedimentary Afterburner. . . . . . . . . . . . . . . . . . 119
Acknowledgements........................................................ 121
References ..................................................... '" . . . ...... 121