Vadose Zone Journal outstanding paper award for our study on observed and simulated isotopic differences in mobile and bulk soil water
Our manuscript on "Measuring and Modeling Stable Isotopes of Mobile and Bulk Soil Water" was selected for the Outstanding Paper Award, 2020 by the Vadose Zone Journal Editorial Board. The "article was selected based on how it has advanced knowledge in the profession, the effectiveness of communication, methodology, originality, and impact". All ASA, CSSA, and SSSA awardees were announced in the latest CSA news that can be found here. I am personally very happy to see that our work has made some impact and was well received by the community. The presented study is a great example for a successful collaboration where data and model code have been shared openly to gain new understanding in subsurface hydrological processes. The work was done within the EU-funded VeWa project and you can find more publications and info here.
Plant water stable isotopes had not been used widely to study plant water use across Northern environments. Doerthe Tetzlaff's EU funded VeWa project addressed this research gap and an inter-site comparison of five involved sites has now been published in Hydrological Processes (open access). We show how the sampled xylem isotopes compare to precipitation, groundwater, and soil water and discuss why there is often a mismatch between the plant water and their potential sources.
On August 3rd I started my position as a Earth Research Scientist at the Earth & Environmental Sciences Area of the Lawrence Berkeley National Laboratory. I will be working in the DOE-funded Watershed Function Project where we are investigating "how complex, multi-scale interactions can lead to a cascade of downstream effects on water availability, nutrient and metal loading, and carbon cycling" (Susan Hubbard, Watershed Function Project Lead). The study site of the project is located in the upper Colorado River with focus on the East River catchment. I am looking forward to be working with the interdisciplinary research group working on the Watershed Function Scientific Focus Area.
Also at this year's AGU Fall Meeting, we will offer a session on "Stable Isotopes in the Critical Zone: Methods, Applications, and Process Interpretations". The last years, the session was very well attended and had lots of interesting isotope research to offer. Make sure to submit your abstract by the End of July here. The AGU Fall Meeting will be held virtually this year and you can read all about it here. This said, you will be able to attend without the usual high costs of travelling and accommodation. Further, the conference fee will be about half the usual price, due to the online form. So, it'll be a great way to keep contact with each other, despite the difficulties during the Covid crisis. You can read here about experiences some hydrologists made during the EGU General Assembly that was held as a virtual conference. I hope to see many of you again for our isotope session!
Since I met Scott in November 2017, we discussed about the concept of "ecohydrologic separation", as introduced by Renée Brooks and colleagues in a Nature Geoscience paper in 2010. In early 2019, we decided to write our thoughts down in a commentary, which was now published in the journal Water Resources Research, titled: "What ecohydrologic separation is and where we can go with it". Our main messages are:
A) Isotope ratios of plant water should differ from water flowing in soils to streams & so we need to move beyond confirming this difference
B) By focusing on dynamics of how water infiltrates into the subsurface & becomes available to plants we can better interpret past findings
C) We discuss four aspects that should be considered:
A paper from the current collaboration with the Surface Hydrology and Erosion Research Group at IDAEA-CSIC, Barcelona, was recently published in a special issue on "Using water age to explore hydrological processes in contrasting environments" in Hydrological Processes. Under the lead of Francesc Gallart, we present a study on "Investigating young water fractions in a small Mediterranean mountain catchment: both precipitation forcing and sampling frequency matter" that highlights how sampling frequency and the rainfall dynamics impact estimations of the young (2-3 month) water fraction in the runoff. We found that this measure of young water fraction depends highly on the runoff dynamics with almost all runoff being young during the highest discharge events. Our findings, based on data from the Vallcebre Catchment in the Pyrenees, are for example relevant for inter-catchment comparisons based on estimated young water fractions, since the sampling design and the runoff responses should probably be considered in such approaches. A pre-print can be downloaded from researchgate and a final version can be requested via email if you do not have access to manuscripts published in Hydrological Processes.
We put together some material for online teaching that spans from technical aspects to hydrological content for classes. If interested, then look at the EGU HS blog post with several links that provide lots of information. Please add more resources to this post by using the commenting function.
A recent paper is the result of a collaboration between James Knighton and the VeWa Team, in which we looked into the effect of different storage and mixing assumptions within the tree for the simulation of xylem stable isotope ratios in the tracer-aided hydrological model EcH2O‐iso. Usually, there is no tree water storage (and mixing) considered in hydrological models, but we showed that adding a storage and assuming either piston flow or fully mixed conditions makes a difference for the model performance. New isotope data sets of higher sampling frequencies will allow in future studies to further investigate the storage and mixing of tree water and its potential effects on xylem water sampling and the interpretation of uptake depths comparing isotope ratios of xylem and soil water. You can find Jame's paper here and if you do not have access to Ecohydrology, please contact me for a copy of the paper.
EGU Session on "Stable isotopes to study water and nutrient dynamics in the soil-plant-atmosphere continuum"
We are organizing for the fourth time a session on the application of stable isotopes to study water and nutrient dynamics in the soil-plant-atmosphere continuum for the EGU General Assembly taking place in Vienna between May 3rd and 8th 2020. You are invited to submit your abstract to this session before January 15, 2020 here. We are happy that Christiane Werner from the University of Freiburg agreed to give an invited talk.
The session description is as follows:
Stable isotopes are powerful tools for tracing fluxes of water and associated nutrients in the soil-plant-atmosphere continuum. They are increasingly used by various disciplines to better understand the functioning of the soil-plant-atmosphere system. While new methods allow measurements at high spatial and temporal resolution, studies applying tracer methods are now tackling complex interactions between soil processes, plant physiology and ecology, and variable atmospheric drivers. As such, methodological developments and changes are happening quickly and have a strong bearing on process understanding and interpretation of findings. This session aims to address the current state of the art for methods, applications, and process interpretations using stable isotopes in the critical zone and to foster interdisciplinary exchange. We welcome experimental and modeling studies that present methodological developments and applications of isotope tracers to improve the actual knowledge of the water and nutrient exchanges at the soil-plant-atmosphere interfaces. Studies that seek to cross disciplinary boundaries and reveal new eco-hydrological process understanding are especially welcome.
The list below shows two poster and two oral presentations that I contribute to the AGU Fall Meeting 2019. The presenting authors are underlined (won't be there personally).
Monday, 9 December 2019
Thursday, 12 December 2019