Groundwater sources for the Mataranka Springs (Northern Territory, Australia).

The Mataranka Springs Complex is the headwater of the iconic Roper River of northern Australia. Using environmental tracers measured in springs and nearby boreholes, the origin of groundwater contributing to the springs was evaluated to help assess the impact of proposed groundwater extraction in the Cambrian Limestone Aquifer (CLA) for irrigation agriculture and for hydraulic fracturing in the Beetaloo Sub-basin (an anticipated world-class unconventional gas reserve). Major ions, Sr, 87Sr/86Sr, δ18O-H2O, δ2H-H2O, 3H, 14C-DIC were consistent with regional groundwater from the Daly and Georgina basins of the CLA as the sources of water sustaining the major springs (Rainbow and Bitter) and one of the minor springs (Warloch Pond). However, 3H = 0.34 TU in another minor spring (Fig Tree) indicated an additional contribution from a young (probably local) source. High concentrations of radiogenic 4He (> 10-7 cm3 STP g-1) at Rainbow Spring, Bitter Spring and in nearby groundwater also indicated an input of deeper, older groundwater. The presence of older groundwater within the CLA demonstrates the need for an appropriate baseline characterisation of the vertical exchange of groundwater in Beetaloo Sub-basin ahead of unconventional gas resource development.

Modelling 85Kr datasets with python for applications in tracer hydrology and to investigate atmospheric circulation.

We present a model written in python to evaluate data from comprehensive 85Kr collection schemes comprising 11 datasets from different monitoring stations around the globe. The model is designed to (1) calculate atmospheric input functions for the application of 85Kr as a dating tracer and (2) to investigate atmospheric circulation based on a two-box model of the atmosphere. Different functions were implemented, to (1) filter the data, (2) fit polynomials and running means, (3) extrapolate fits from the northern to the southern hemisphere, (4) calculate interhemispheric exchange times and 85Kr emission rates and (5) export data to a csv file. Although the model is designed to evaluate atmospheric 85Kr datasets, some functionality and basic concepts can be applied to other dating tracers, like tritium and SF6.•Standardized method to systematically analyse atmospheric 85Kr activity concentration time series for dating water and ice and to investigate atmospheric circulation.•Easily modifiable python script to adapt functions for similar data analysis procedures.

Krypton-85 datasets of the northern and southern hemisphere collected over the past 60 years.

With a half-life of 10.7 years, the noble gas radioisotope 85Kr is perfectly suited as a tracer to date ice and water that formed during the past half century. Furthermore, due to its inhomogeneous input into the atmosphere, it is a useful tool to investigate atmospheric circulation and back-trajectory analysis. The data presented here represent a comprehensive time series of atmospheric 85Kr activity concentrations in ground level air that can be used to model northern and southern hemispheric input functions, which is essential to apply 85Kr as a dating tracer. The collection comprises 11 datasets from 4 monitoring stations in the northern and 7 monitoring stations in the southern hemisphere, respectively. In total, it contains about 8000 measurements performed over the past 60 years, making it the largest published 85Kr record.