Jean-Luc Ponche

Anatomically modern human in Southeast Asia (Laos) by 46 ka

Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51–46 ka, and direct U-dating of the bone indicates a maximum age of ∼63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic–modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ∼50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia.

Mass transfer at the air/water interface: Mass accommodation coefficients of SO2, HNO3, NO2 and NH3

We present here experimental determinations of mass accommodation coefficients β using a low pressure tube reactor in which monodispersed droplets, generated by a vibrating orifice, are brought into contact with known amounts of trace gases. The uptake of the gases and the accommodation coefficient are determined by chemical analysis of the aqueous phase.We report in this article measurements of βexp=(6.0±0.8)×10−2 at 298 K and with a total pressure of 38 Torr for SO2, (5.0±1.0)×10−2 at 297 K and total pressure of 52 Torr for HNO3, (1.5±0.6)×10−3 at 298 K and total pressure of 50 Torr for NO2, (2.4±1.0)×10−2 at 290 K and total pressure of 70 Torr for NH3.These values are corrected for mass transport limitations in the gas phase leading to β=(1.3±0.1)×10−1 (298 K) for SO2, (1.1±0.1)×10−1 (298 K) for HNO3, (9.7±0.9)×10−2 (290 K) for NH3, (1.5±0.8)×10−3 (298 K) for NO2 but this last value should not be considered as the true value of β for NO2 because of possible chemical interferences.Results are discussed in terms of experimental conditions which determine the presence of limitations on the mass transport rates of gaseous species into an aqueous phase, which permits the correction of the experimental values.

Vapor pressures in the ternary system water‐nitric acid‐sulfuric acid at low temperature: A reexamination

The equilibrium partial vapor pressures over the binary solutions H2O/HNO3, H2SO4/H2O, HNO3/H2SO4 and the ternary mixture H2SO4/HNO3/H2O have been re-determined for temperatures below 25°C. The model presented here is valid over the entire range of concentrations, for temperatures in the range 190–298 K. The predictions of this model are compared with the existing measurements and other predictions, both at room temperature and at low temperatures down to about 190 K. The calculated partial pressures agree very well with the available experimental data

Experimental determination of HONO mass accommodation coefficients using two different techniques

The mass accommodation coefficient αHONO of gaseous nitrous acid on water surfaces has been determined in a cooperation between the Universities of Strasbourg and Bonn. The droplet train technique (Strasbourg) yielded 0.04<αHONO<0.09 for an estimated surface temperature of 245 K, while the liquid jet technique (Bonn) yielded 0.03<αHONO<0.15 for a surface temperature of 297 K. The uncertainty ranges allow for experimental scatter and estimated uncertainties in diffusion coefficients. The same HONO source and analytical equipment were used for both experiments, which were run in parallel. The results indicate that the exchange rate of HONO between atmospheric water droplets and interstitial air is not inhibited by interfacial resistance.

Fate of ClNO2 over aqueous solutions containing iodide

The uptake of nitryl chloride ClNO2 by pure water and NaI solutions was studied as a function of temperature in the range from 268 to 279 K with the droplet train technique. An upper limit of 10−5 was derived for the uptake on pure water, while the uptake rate was observed to be greatly enhanced in the presence of 10−3–10−2 M iodide, yielding uptake coefficients in the range from 1.1 × 10−3 to 6.6 × 10−3. This enhancement is a consequence of a reaction between I− and ClNO2 where we suggest that a transfer of Cl+ to iodide is involved. We also suggest that bulk kinetics alone is unable to describe the measured uptake rate which is influenced by surface reactions. These results show that heterogeneous chemistry in concentrated aerosols may play an important role for the fate of ClNO2, and may affect the concentration of atomic chlorine in the marine boundary layer.

Methodology and results of the REKLIP atmospheric emission inventory of the upper Rhine valley transborder region

In the frame of the climatological project REKLIPwhich involves part of Switzerland, Germany and Franceand concerns the upper Rhine valley, an atmosphericemission inventory has been established with a spatialresolution of a square kilometer and a time resolutionup to one hour. Anthropogenic emissions of SO2, NOx,CO, HCl and volatile organic compounds (VOC) divided into thirty compounds or group of compounds as well as biogenic emissions of NMVOC have been taken into account for the year 1990. This inventory has been updated for the following years until 1993 and some hourly emissions inventories have been derived for a period of several days of September 1992,corresponding to a REKLIP intensive measurement campaign.

Studies of gas-phase clustering of water on sulphuric acid molecules

Abstract Enthalpies and free energies of gas-phase clustering of one to ten water molecules about one acid molecule are predicted from thermodynamic considerations. The enthalpy of formation of the monohydrate, H 2 SO 4 H 2 O, −53.5 kJ/mol, compare favorably with recent calculations from quantum mechanics, −67 kJ/mol.

The air quality management of the region of Great Casablanca (Morocco). Part 1: atmospheric emission inventory for the year 1992

Within the frame of an air quality study of the Great Casablanca Area (GCA), an atmospheric emission inventory concerning the major pollutants: SO2; NOx; non-methane volatile organic compounds (NMVOC); and CO has been realized. This inventory has a spatial resolution of 1 km2 and is established for the reference year 1992. The area, which covers 2500 km2 includes a region which is very sensitive to atmospheric pollution since it is heavily populated and contains up to 60% of the industrial activities of Morocco. The results, which include both biogenic and anthropogenic sources, show as expected very large emissions of pollutants mainly due to the presence of a refinery, several power plants and, contrary to the general European situation, the production of NOx is not dominated by road traffic.

Early Modern Humans from Tam Pà Ling, Laos: Fossil Review and Perspectives

Despite the importance of its geographical position for early modern human migration through Australasia, the Indochinese Peninsula has produced relatively few fossils or well-documented archaeological sites, resulting in a poor chronology for early occupation. Tam Pà Ling (TPL), a cave in northern Laos, is one of the rare sites yielding fossils contemporaneous with the earliest migrants into Australasia within a securely established chronology. From its discovery in 2008 until the most recently filed season in 2016, TPL has provided evidence of a modern human presence in the region by marine isotope stages 4 and 3. A partial cranium (TPL1), two mandibles (TPL2, TPL3), and assorted postcranial fragments (TPL4, TPL5) represent the earliest well-dated, anatomically modern humans in the Indochinese Peninsula and introduce new migration routes into the area. The sedimentary context of TPL is described and refined elsewhere, resulting in an approximate age of 44–63 ka for the TPL1 and TPL2 fossils and a maximum depositional age of 70 ka for the lowest layer containing the TPL3 mandible. This is 20 ka older than the depositional ages for the TPL1 and TPL2 fossils and establishes a new upper limit for sedimentary deposition at the site and for the associated fossil evidence. In this study, we review previously presented material (TPL1–TPL3), present unpublished postcranial material (TPL4 and TPL5), and provide dental metric analysis of the TPL1–TPL3 specimens.

The prehistoric peopling of Southeast Asia

Ancient migrations in Southeast Asia The past movements and peopling of Southeast Asia have been poorly represented in ancient DNA studies (see the Perspective by Bellwood). Lipson et al. generated sequences from people inhabiting Southeast Asia from about 1700 to 4100 years ago. Screening of more than a hundred individuals from five sites yielded ancient DNA from 18 individuals. Comparisons with present-day populations suggest two waves of mixing between resident populations. The first mix was between local hunter-gatherers and incoming farmers associated with the Neolithic spreading from South China. A second event resulted in an additional pulse of genetic material from China to Southeast Asia associated with a Bronze Age migration. McColl et al. sequenced 26 ancient genomes from Southeast Asia and Japan spanning from the late Neolithic to the Iron Age. They found that present-day populations are the result of mixing among four ancient populations, including multiple waves of genetic material from more northern East Asian populations. Science, this issue p. 92, p. 88; see also p. 31 Ancient genomes reveal four layers of human migration into Southeast Asia. The human occupation history of Southeast Asia (SEA) remains heavily debated. Current evidence suggests that SEA was occupied by Hòabìnhian hunter-gatherers until ~4000 years ago, when farming economies developed and expanded, restricting foraging groups to remote habitats. Some argue that agricultural development was indigenous; others favor the “two-layer” hypothesis that posits a southward expansion of farmers giving rise to present-day Southeast Asian genetic diversity. By sequencing 26 ancient human genomes (25 from SEA, 1 Japanese Jōmon), we show that neither interpretation fits the complexity of Southeast Asian history: Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting island SEA and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory.