The importance of the exposome and allostatic load in the planetary health paradigm

In 1980, Jonas Salk (1914-1995) encouraged professionals in anthropology and related disciplines to consider the interconnections between "planetary health," sociocultural changes associated with technological advances, and the biology of human health. The concept of planetary health emphasizes that human health is intricately connected to the health of natural systems within the Earth's biosphere; experts in physiological anthropology have illuminated some of the mechanisms by which experiences in natural environments (or the built environment) can promote or detract from health. For example, shinrin-yoku and related research (which first emerged from Japan in the 1990s) helped set in motion international studies that have since examined physiological responses to time spent in natural and/or urban environments. However, in order to advance such findings into planetary health discourse, it will be necessary to further understand how these biological responses (inflammation and the collective of allostatic load) are connected to psychological constructs such as nature relatedness, and pro-social/environmental attitudes and behaviors. The exposome refers to total environmental exposures-detrimental and beneficial-that can help predict biological responses of the organism to environment over time. Advances in "omics" techniques-metagenomics, proteomics, metabolomics-and systems biology are allowing researchers to gain unprecedented insight into the physiological ramifications of human behavior. Objective markers of stress physiology and microbiome research may help illuminate the personal, public, and planetary health consequences of "extinction of experience." At the same time, planetary health as an emerging multidisciplinary concept will be strengthened by input from the perspectives of physiological anthropology.Peer reviewe

Sulphur hexafluoride as a tracer of biogeochemical and physical processes in an open-ocean iron fertilisation experiment

The article of record as published may be found at https://doi.org/10.1016/S0967-0645(98)00022-8The first open-ocean experiment to test the iron hypothesis in the equatorial Pacific was undertaken using the tracer gas sulphur hexafluoride (SF6) to locate and track the fertilised surface water. Continuous surface measurements showed that the SF6 patch spread rapidly in the first 24 h, from an initial release area of ∼64 km2 to a total area of 214 km2, and remained relatively constant in size for the following three-day period. SF6 data was mapped in a Lagrangian frame of reference by the use of a drogued GPS buoy released at the centre of the patch. The SF6 patch remained coherent and exhibited a slow, anti-cyclonic oscillation during the first four days. The buoy was transported downwind of the patch in a northwesterly direction within two days, which has implications for the future use of buoys in surface-water advection studies. Following subduction below a low-salinity front 3–4 days after release, the patch centre was relocated by its SF6 signal at a depth of 25–30 m to the east of the residual surface patch. The latter spread rapidly to the southwest during the remainder of the experiment, whilst the subducted patch remained relatively stationary. Density-corrected SF6 profiles were used to calculate a mean vertical eddy diffusivity of 0.25 cm2/s across the thermocline following the subduction event. A vertical flux of nitrate of 2.5 mmol/m-2 d-1 into the mixed layer was estimated, which implied an f-ratio value of 0.4 on comparison with productivity data. The results demonstrate that SF6 is a successful tracer of water masses, and emphasise the potential of this technique for the in situ measurement and manipulation of open-ocean processes

Trace Gases And Air-Sea Exchanges

The most widely used approach for calculating the flux of gases across the sea surface is from the product of the concentration difference across the interface and a kinetic parameter, often called the transfer velocity. During the NERC North Sea Community Research Project (CRP) a considerable effort was made to improve our knowledge of both of these terms. Concentration measurements were made on nine survey cruises (February to October 1989) for dimethyl sulphide (DMS) (and its precursor dimethylsulphonioproprionate DMSP, both dissolved and particulate), as well as for a variety of natural and man-made low molecular mass halocarbons. To better define the relationship between transfer velocity and wind speed a novel double tracer technique was used on two of the process cruises in the North Sea CRP. The tracers added to the water were SF$_{6}$ and $^{3}$He and from the measured change in their concentration ratio over time, four estimates of the transfer velocity were made, one at a rather high wind speed (ca. 17 m s$^{-1}$). The results are in general agreement with the relationship of Liss & Merlivat (1986) based on laboratory and lake studies and theoretical considerations, and constitute their first real test at sea. Combining the above results for the transfer velocity with the detailed concentration fields measured in the CRP has enabled us to calculate fluxes across the sea surface for the measured gases with a much finer time and space resolution than was possible hitherto. Some implications of the calculated fluxes for atmospheric chemistry in Europe are discussed