Figuring out how chemical, biological and mechanical weathering enhance or restrict each other is one of the fundamental gaps in our knowledge of rock deterioration. This poses problems when we try to understand how much weathering processes contribute to the production of sediments and the minerals and nutrients that keep the biosphere healthy. In the face of a changing climate, especially in the Arctic where rapid changes have already been observed, we are as yet not able to predict how this will affect weathering product output. I therefore use a combination of field and lab work to tackle this problem, to disentangle chemical, biological and mechanical weathering, to see how they respond to climate change and to develop a model for weathering production under changing climate regimes.
The big (official) idea:
The Arctic Ocean is now thought to account for ca. 14% of the global uptake of atmospheric CO2, a process that is driven by the influx of weathering products (notably silicates and carbonates) into the ocean through dissolved load in stream channels. These minerals not only provide reactive chemicals for atmospheric CO2 drawdown, but also provide long-term storage of CO2 through the formation of sedimentary rock. While an increase in available weathered material due to a decrease in ice cover might lead to a higher availability of silicates and carbonates, and consequentially aid enhanced drawdown of CO2, it could also aid an acceleration of acidification of the ocean. This has potentially disastrous consequences for marine ecosystems and associated commercial fish stocks. Understanding the timing and tempo of Arctic continental weathering is therefore critical for evaluating the role of natural CO2 drawdown in climate stabilization, and for understanding the wider climate change consequences for the health of our oceans.
Despite these uncertainties, and their far-reaching consequences, no research has been conducted into the fundamental processes behind the production of silicates and carbonates (chemical, mechanical and biological weathering processes) their interaction, and their sensitivity to climate change. Though stable isotope measurements indicate that weathering output fluctuates with climate change, conventional weathering studies still overwhelmingly focus on one or at most two of the processes, yet fail to address the complex interactions that lead to weathering product development. This lack of understanding makes it very difficult to, for example, make statements regarding the potential future contribution of weathering products to acidification and CO2 uptake by the Arctic Ocean. This project aims to address this imbalance by using an innovative multi-tier quantitative modelling approach to conduct fundamental research into the complex interaction between mechanical, biological and chemical weathering and their sensitivity to climatic change. It uses a comprehensive laboratory and field study to produce a model which will allow quantitative predictions of weathering output, and their signals in the isotopic record to be made based on IPCC climate change projections, and consequently their potential contribution to CO2 drawdown.
The fieldwork idea:
During this first field season I’ll be looking at a number of different things. First of all, I’m going to investigate the progression of weathering through the catchment by setting up weathering monitoring stations; groups of 9 blocks, consisting of 3 different stone types. Within each stone type section there are three levels of pre-weathering (carried out before the fieldwork); not weathered, slightly weathered, heavily weathered. I’ll be looking at how each block responds to weathering and if there is an imbalance between chemical and biological weathering based on the weathering history of the block. I’ll also attach high-resolution temperature loggers to check for microclimate fluctuations.
Of course I will be fair and not just add more rocks to Svalbard, I will also collect samples which I’ll use for laboratory analysis to see how the small critters, chemical composition and mineral deterioration work in ‘the real world’ to compare to my lab samples.
Next, I’ll collect water samples to look at lithium and magnesium isotopes to see how much material influx from the sides of the Endalen catchment contribute to the levels of isotopes. We currently use these as a marker of weathering rates yet we do not know exactly how much weathering it takes to get to certain levels. I’ll therefore use my own field observations, 3D laser scanning and water samples to estimate where the biggest influxes are, where isotopes might get stored along the catchment and how much this one catchment contributes to the outflux of Adventdalen into Isfjorden and eventually the Arctic Ocean. I’ll be heading back to the field in early March 2015 and then hopefully August and March each year to get more isotope samples so I can check if there are seasonal fluctuations.
Water is known to be a major source of rock deterioration. Amy Lewis, a first year undergraduate at Cardiff University, and I will therefore carry out Electric Resistivity Tomography along the slopes to see how water moves through the slopes of the catchment and eventually into the run-off channels to get a better idea of the catchment processes.
Here is the link to Amy Lewis’ blog
You can find lots of information about the Arctic through the Arctic Council pages
The US has its own Arctic Research Commission where you can find information on science, articles and policy.
The NERC Arctic Office also has a lot of information on what British research groups are doing, also good if you’re interested in getting funding to go there yourself!
Alternatively, you can join the ‘Women in Polar Science’ Facebook community to keep up to date on what female scientists are achieving