J/ApJ/858/119 O_2_ laboratory atmosphere simulation experiments (Horst+, 2018) ================================================================================ Exploring the atmosphere of Neoproterozoic Earth: the effect of O_2_ on haze formation and composition. Horst S.M., He C., Ugelow M.S., Jellinek A.M., Pierrehumbert R.T., Tolbert M.A. =2018ApJ...858..119H ================================================================================ ADC_Keywords: Molecular data; Earth Keywords: astrobiology ; Earth ; planets and satellites: atmospheres Abstract: Previous studies of haze formation in the atmosphere of the early Earth have focused on N_2_/CO_2_/CH_4_ atmospheres. Here, we experimentally investigate the effect of O_2_ on the formation and composition of aerosols to improve our understanding of haze formation on the Neoproterozoic Earth. We obtained in situ size, particle density, and composition measurements of aerosol particles produced from N_2_/CO_2_/CH_4_/O_2_ gas mixtures subjected to FUV radiation (115-400nm) for a range of initial CO_2_/CH_4_/O_2_ mixing ratios (O_2_ ranging from 2ppm to 0.2%). At the lowest O_2_ concentration (2ppm), the addition increased particle production for all but one gas mixture. At higher oxygen concentrations (20ppm and greater), particles are still produced, but the addition of O_2_ decreases the production rate. Both the particle size and number density decrease with increasing O_2_, indicating that O_2_ affects particle nucleation and growth. The particle density increases with increasing O_2_. The addition of CO_2_ and O_2_ not only increases the amount of oxygen in the aerosol, but it also increases the degree of nitrogen incorporation. In particular, the addition of O_2_ results in the formation of nitrate-bearing molecules. The fact that the presence of oxygen-bearing molecules increases the efficiency of nitrogen fixation has implications for the role of haze as a source of molecules required for the origin and evolution of life. The composition changes also likely affect the absorption and scattering behavior of these particles but optical property measurements are required to fully understand the implications for the effect on the planetary radiative energy balance and climate. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 242 103 Scanning mobility particle sizer (SMPS) measurements table3.dat 185 120 High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurements -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 6 F6.2 nm Diam [7.3/289] Diameter midpoint 8- 14 I7 --- 120-0-0 [722/4335886] 19.7ppm CH_4_ (1) 16- 22 I7 --- 279-0-0 [13000/2600617] 78.8ppm CH_4_ (1) 24- 30 I7 --- 379-260-0 78.8ppm CH_4_, 260ppm CO_2_ (1) 32- 38 I7 --- 479-260-2 78.8ppm CH_4_, 260ppm CO_2_, 2ppm O_2_ (1) 40- 45 I6 --- 579-260-20 [0/182054] 78.8ppm CH_4_, 260ppm CO_2_, 20ppm O_2_ (1) 47- 52 I6 --- 679-260-200 [0/259214] 78.8ppm CH_4_, 260ppm CO_2_, 200ppm O_2_ (1) 54- 58 I5 --- 779-260-2000 [0/67033] 78.8ppm CH_4_, 260ppm CO_2_, 2000ppm O_2_ (1) 60- 65 I6 --- 879-394-0 78.8ppm CH_4_, 394ppm CO_2_ (1) 67- 73 I7 --- 979-394-2 78.8ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 75- 79 I5 --- 1079-394-20 [39/55808] 78.8ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) 81- 85 I5 --- 1179-394-200 [0/52278] 78.8ppm CH_4_, 394ppm CO_2_, 200ppm O_2_ (1) 87- 92 I6 --- 1279-394-2000 [0/325320] 78.8ppm CH_4_, 394ppm CO_2_, 2000ppm O_2_ (1) 94-100 I7 --- 13118-0-0 [28917/3237940] 118ppm CH_4_ (1) 102-108 I7 --- 14118-260-0 118ppm CH_4_, 260ppm CO_2_ (1) 110-116 I7 --- 15118-260-2 118ppm CH_4_, 260ppm CO_2_, 2ppm O_2_ (1) 118-123 I6 --- 16118-260-20 118ppm CH_4_, 260ppm CO_2_, 20ppm O_2_ (1) 125-130 I6 --- 17118-260-200 [161/871914] 118ppm CH_4_, 260ppm CO_2_, 200ppm O_2_ (1) 132-137 I6 --- 18118-260-2000 [0/524338] 118ppm CH_4_, 260ppm CO_2_, 2000ppm O_2_ (1) 139-145 I7 --- 19118-394-0 118ppm CH_4_, 394ppm CO_2_ (1) 147-153 I7 --- 20118-394-2 118ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 155-161 I7 --- 21118-394-20 118ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) 163-168 I6 --- 22118-394-200 [0/128965] 118ppm CH_4_, 394ppm CO_2_, 200ppm O_2_ (1) 170-174 I5 --- 23118-394-2000 [0/97670] 118ppm CH_4_, 394ppm CO_2_, 2000ppm O_2_ (1) 176-182 I7 --- 24158-0-0 [17094/2730395] 158ppm CH_4_ (1) 184-190 I7 --- 25158-260-0 158ppm CH_4_, 260ppm CO_2_ (1) 192-198 I7 --- 26158-260-2 158ppm CH_4_, 260ppm CO_2_, 2ppm O_2_ (1) 200-205 I6 --- 27158-260-20 158ppm CH_4_, 260ppm CO_2_, 20ppm O_2_ (1) 207-212 I6 --- 28158-260-200 [0/353555] 158ppm CH_4_, 260ppm CO_2_, 200ppm O_2_ (1) 214-220 I7 --- 29158-394-0 158ppm CH_4_, 394ppm CO_2_ (1) 222-228 I7 --- 30158-394-2 158ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 230-235 I6 --- 31158-394-20 158ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) 237-242 I6 --- 32158-394-200 [20/454118] 158ppm CH_4_, 394ppm CO_2_, 200ppm O_2_ (1) -------------------------------------------------------------------------------- Note (1): Units are [particles/cm^3^]. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Ratio [1/120] Mass to charge ratio 5- 11 E7.1 --- 120-0-0 [0/7.1] 19.7ppm CH_4_ (1) 13- 19 E7.1 --- 279-0-0 [0/70] 78.8ppm CH_4_ (1) 21- 28 E8.1 --- 379-260-0 [-0.0009/8.2] 78.8ppm CH_4_, 260ppm CO_2_ (1) 30- 36 E7.1 --- 479-260-2 [0/21] 78.8ppm CH_4_, 260ppm CO_2_, 2ppm O_2_ (1) 38- 45 E8.1 --- 579-260-20 [-1.8/8.7] 78.8ppm CH_4_, 260ppm CO_2_, 20ppm O_2_ (1) 47- 54 E8.1 --- 679-394-0 [-0.09/2.4] 78.8ppm CH_4_, 394ppm CO_2_ (1) 56- 63 E8.1 --- 778-394-2 [-1.4/10] 78.8ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 65- 72 E8.1 --- 878-394-20 [-0.009/9.1] 78.8ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) 74- 80 E7.1 --- 9118-0-0 [0/190] 118ppm CH_4_ (1) 82- 88 E7.1 --- 10118-260-0 [0/40] 118ppm CH_4_, 250ppm CO_2_ (1) 90- 96 E7.1 --- 11118-260-2 [0/35] 118ppm CH_4_, 250ppm CO_2_, 2ppm O_2_ (1) 98-104 E7.1 --- 12118-260-20 [0/22] 118ppm CH_4_, 250ppm CO_2_, 20ppm O_2_ (1) 106-112 E7.1 --- 13118-394-0 [0/29] 118ppm CH_4_, 394ppm CO_2_ (1) 114-121 E8.1 --- 14118-394-2 [-0.2/38] 118ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 123-129 E7.1 --- 15118-394-20 [0/12] 118ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) 131-137 E7.1 --- 16158-0-0 [0/140] 158ppm CH_4_ (1) 139-145 E7.1 --- 17158-260-0 [0/63] 158ppm CH_4_, 260ppm CO_2_ (1) 147-153 E7.1 --- 18158-260-2 [0/53] 158ppm CH_4_, 260ppm CO_2_, 2ppm O_2_ (1) 155-161 E7.1 --- 19158-260-20 [0/16] 158ppm CH_4_, 260ppm CO_2_, 20ppm O_2_ (1) 163-169 E7.1 --- 20158-394-0 [0/40] 158ppm CH_4_, 394ppm CO_2_ (1) 171-177 E7.1 --- 21158-394-2 [0/44] 158ppm CH_4_, 394ppm CO_2_, 2ppm O_2_ (1) 179-185 E7.1 --- 22158-394-20 [0/9.5] 158ppm CH_4_, 394ppm CO_2_, 20ppm O_2_ (1) -------------------------------------------------------------------------------- Note (1): The intensity in arbitrary (but internally consistent) units. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Apr-2019