Environmental Isotopes in the Hydrological Cycle
Principles and Applications

VOLUME II: ATMOSPHERIC WATER
by 
Joel R. Gat   Weizmann Institute, Rehovot, Israel
Willem G. Mook  and  Harro A.J. Meijer
Centre Isotope Research, Groningen, The Netherlands

Preface
CONTENTS
1	THE  ATMOSPHERE	  1
	1.1	Atmospheric constitution		  1
	1.2	Atmospheric moisture		  5          

2	ISOTOPE  METHODOLOGY	  7
	2.1	Isotope abundance			  7
	2.2	Isotope fractionation			  9
		2.2.1	Equilibrium isotope fractionation	  9
		2.2.2	Kinetic isotope fractionation	11
		2.2.3	Transport isotope fractionation	12
	2.3	Isotopic enrichment and depletion by the Rayleigh process	13          

3	STABLE  ISOTOPE  PROCESSES  IN  THE  WATER  CYCLE	17
	3.1	Relation between 18O/16O and 2H/1H in natural waters	20
	3.2	Evaporation			21
		3.2.1	The case of complete mixing of the liquid reservoir	21
		3.2.2	The case of incomplete mixing of the liquid reservoir	26
	3.3	Clouds and precipitation		27
		3.3.1	In-cloud processes		27
		3.3.2	Interaction between rain droplets and ambient moisture	28
		3.3.3	Evolution of the isotopic composition during a shower	29
	3.4	Seawater and the marine atmosphere	30
	3.5	The continental atmosphere		31
		3.5.1	The Rayleigh regime		31
		3.5.2	Evaporation and transpiration; recycling of moisture overland	36
		3.5.3	Selection versus fractionation	38
	3.6	The 17O - 18O relation		40          

4	OBSERVED  ISOTOPE  EFFECTS  IN  PRECIPITATION	43
	4.1	The latitude / annual temperature effect	43
	4.2	Seasonal effect			45
	4.3	Oceanic and continental precipitation	50
	4.4	Altitude effect			53
	4.5	Amount effect			55
	4.6	Interannual variations		56
          

	4.7	Small-scale variations		57
		4.7.1	Small-scale spatial variations	57
		4.7.2	Small-scale temporal variations	58
	4.8	Palaeoclimate reconstruction		59          

5	TRITIUM  IN  THE  ATMOSPHERE	63
	5.1	Characteristics of tritium		63
	5.2	Geophysical aspects			64
	5.3	Hydrological aspects		69
		5.3.1	Long-term recovery of natural 3H levels	69
		5.3.2	Seasonal variations in 3H		69
		5.3.3	Geographical variations in 3H	72
		5.3.4	Small-scale 3H variations		72
			5.3.4.1	Small-scale spatial 3H variations	74
			5.3.4.2	Small-scale temporal 3H variations	74          

6	ISOTOPES IN ATMOSPHERIC CO2 AND O2	75
	6.1	Atmospheric CO2 concentrations		75
	6.2	Stable carbon isotopes in atmospheric CO2	78
	6.3	Stable oxygen isotopes in atmospheric CO2	82
	6.4	Radiocarbon in atmospheric CO2		84
	6.5	Atmopheric oxygen			86
		6.5.1	Atmospheric oxygen concentration	86
		6.5.2	Isotopes in atmospheric oxygen	87          

REFERENCES	91          

LITERATURE	 103          

IAEA PUBLICATIONS	 105          

SYMBOLS AND ABBREVIATIONS	 109          

CONSTANTS	 110          

SUBJECT INDEX	 111