Science Diplomacy at the International Atomic Energy Agency: Isotope Hydrology, Development, and the Establishment of a Technique

This essay examines the International Atomic Energy Agency’s (IAEA’s) role in the entry of hydrological isotopic analysis techniques into the developing world. The notion of using radioisotopic tracers for hydrological study came from the initiative of individual scientists, many of whom were interested in measuring the uptake of hydrogen-bomb deposited tritium in the global environment. Their proposals to include isotope hydrology among the range of IAEA activities sparked debate in the IAEA Scientific Advisory Committee and Board of Governors. At stake was not merely the future support of the technique, but the diplomatic role of the IAEA as a provider of atomic energy to the developing world, the relationship of the IAEA to other international institutions, and the articulation of what ‘peaceful uses of atomic energy’ really meant. In the end, the IAEA opted to render conditional support for the landmark Global Network of Isotopes in Precipitation and undertook sponsorship of expert panels that brought together isotope specialists and hydrologists. As the essay shows, the IAEA’s agenda for isotope hydrology was not only a matter of technology, linked to instrumentation and technique. As a form of policy entrepreneurship, it also gave the IAEA a new diplomatic role in the larger network of international institutions.

Triple oxygen isotope systematics of evaporation and mixing processes in a dynamic desert lake system

This study investigates the combined hydrogen deuterium and triple oxygen isotope hydrology of the Salar del Huasco, an endorheic salt flat with shallow lakes at its centre that is located on the Altiplano Plateau, N Chile. This lacustrine system is hydrologically dynamic and complex because it receives inflow from multiple surface and groundwater sources. It undergoes seasonal flooding, followed by rapid shrinking of the water body at the prevailing arid climate with very high evaporation rates. At any given point in time, ponds, lakes, and recharge sources capture a large range of evaporation degrees. Samples taken between 2017 and 2019 show a range of δ18O between −13.3 ‰ and 14.5 ‰, d-excess between 7 ‰ and −100 ‰, and 17O-excess between 19 and −108 per meg. A pan evaporation experiment conducted on-site was used to derive the turbulence coefficient of the Craig–Gordon isotope evaporation model for the local wind regime. This, along with sampling of atmospheric vapour at the salar (-21.0±3.3 ‰ for δ18O, 34±6 ‰ for d-excess and 23±9 per meg for 17O-excess), enabled the accurate reproduction of measured ponds and lake isotope data by the Craig–Gordon model. In contrast to classic δ2H–δ18O studies, the 17O-excess data not only allow one to distinguish two different types of evaporation – evaporation with and without recharge – but also to identify mixing processes between evaporated lake water and fresh flood water. Multiple generations of infiltration events can also be inferred from the triple oxygen isotope composition of inflow water, indicating mixing of sources with different evaporation histories. These processes cannot be resolved using classic δ2H–δ18O data alone. Adding triple oxygen isotope measurements to isotope hydrology studies may therefore significantly improve the accuracy of a lake's hydrological balance – i.e. the evaporation-to-inflow ratio (E / I) – estimated by water isotope data and application of the Craig–Gordon isotope evaporation model.

The Isotopic Composition of Cyprus Precipitation. A Tool of Isotope Hydrology.

<p>Monitoring and profiling the isotopic composition of soil water in combination with groundwater isotope hydrology are commonly used in studying flow and transport in soils as well as in estimating groundwater recharge. Establishing the isotopic composition of local precipitation is of essence. Towards this end and in facilitating the application of isotope hydrology in Troodos Fractured Aquifer (TFA), precipitation was monitored in 16 precipitation sampling stations, stretching from the shoreline up to 1725 m above m.s.l., from January of 2015 to December of 2017. A seasonal trend was discerned, with isotopically depleted rainfall occurring in December as opposed to the more enriched autumn and spring rainfall. Northern European air masses appear to prevail during the months of December to January during which d values tend to be on average above 25‰ whereas the more enriched rain with the lowest d values occurs in July. The averaged seasonal effect between 2015 and 2017 on δ18O, δ2H and d values are 4.53‰, 30.98‰ and 14.93‰, respectively. Cyprus’ Local Meteoric Water Line (LMWL) was found to be equal to δ2H = (6.58±0.13)*δ18O + (12.64±0.91) and a general decrease of 1.22‰ for δ2H and 0.20‰ for δ18O in precipitation was calculated per 100 m altitude.  Similar values have been found by other researchers for the region. These variations in the isotope composition of rainfall can be used to earmark seasonal input of recharge water and for deriving percolation rates from tracing their movement in the soil column.</p>

Mediterranean Temporary Ponds: using isotope hydrology tools to describe and understand their behaviour

<p>Mediterranean temporary ponds are very shallow ponds, isolated from permanent water bodies, which undergo a periodic cycle of flooding and drought, and have a characteristic flora and fauna adapted to this alternation. This habitat is mainly distributed in dry and sub-arid areas. Mediterranean temporary ponds are identified as one of the worldwide biodiversity hotspots and constitutes therefore a priority habitats according to the Natura 2000 network of the European Union (3170*, Council Directive 92/43/CEE). The development of flora and fauna in this type of ecosystem is defined by the natural length of the hydro-period. However, little is known about the hydrological functioning of these very specific hydrosystems. DespiteHS10 this protective conservation status, this habitat has suffered continuous degradation and loss disappearing at a fast rate due anthropogenic impacts and climate pressures. In most cases, temporary wetland disappearance is unintentional and related to a lack of understanding of its hydrological functioning within the watershed.</p><p>The aim of this work is, hence, to use the tools of the isotope hydrology to increase our basic understanding of the hydrological functioning of the Mediterranean temporary ponds. Our study focuses on the Musella temporary pond located in Southern Corsica (France) which undergoes important man-induced and climatic pressures. During one full hydrological cycle, surface and groundwater levels, major ions, stable isotopes of the water molecules as well as field parameters (temperature, pH, electrical conductivity, dissolved oxygen) have been measured every month.</p><p>Results bring information on the water quality, chemical stability and temporal evolution in terms of surface water level as well as potential connection with the underlying carbonated aquifer. The stable isotopes inform about the origin of water, its mixing processes with groundwater, and its evaporative status through time.</p><p>Flooding and drying processes of the Musella temporary pond are now better constrained and documented projections can now be set up towards the resilience of the hydrosystem considering the future consequences of climate change in the Mediterranean region.</p>