The transmissive critical zone: understanding the karst hydrology-biogeochemical interface for sustainable management

Lead Research Organisation: University of Glasgow
Department Name: School of Geographical & Earth Sciences


The Earth's surface (soil and plants), and the rock underneath interact, linked by rainwater flowing through the soil into the rock. The soil imparts a chemical signature to the water, sometimes bad leading to loss of water quality. This signature is mediated by movement through the rock, and then, when underground water re-emerges, in streams and rivers by bacterial activity. As such, how this outer layer of planet Earth functions is 'critical' to key needs of mankind - how much water we have available and its quality; how well the soil functions as a result of water draining through it. The study of how these layers interact is thus called 'critical zone' research.
Our research programme uses such 'critical zone' research in an environment where the local residents face significant environmental challenges - in rural China, an area of rapid growth and where many live under the poverty line. This is a joint research programme between UK and China. We will focus on two of these challenges: water availability and quality, and how movement of water in the critical zone influences surface vegetation. Crucial to this research is that the underlying rock is mostly limestone. Limestone is easily dissolved and water can move very quickly through the subsurface. So soils may dry sooner (as the subsurface beneath is freely-draining) and there is limited water storage on the surface and underground. Limestone is widely distributed world-wide, but particularly in China and so study here is relevant to many world-wide.
The people living in the catchment generally live-off-the-land. It provides their water and food - a phenomenon known as the ecosystem providing services. Where the slopes are not too steep, the land surface is heavily-cultivated. This in turn presents problems e.g., the water quality is poor, with dangerously high-level of nitrate (a chemical that is found in fertiliser); clearance of vegetation exposes rock, limiting how land may be used. Further challenging to local residents is that the climate is changing. How rain is delivered to the catchment has been changing such that water is not available as before. Thus there have also been water shortages, and this led to crop failure and so loss of food.
Land use change is important in shaping these ecosystem services, but climate change may be one of the most significant threats the residents will face; science must help them prepare for facing these threats with successful outcomes. Our research will generate models of how the critical zone functions currently and from these we can then investigate how the critical zone functioning may adapt to different environmental drivers. There is a large body of scientific modelling outside this project that has identified how the climate may change. Thus, we can draw on this to run the models we will develop of the critical zone functioning, not only under land use change, but also under future climate scenarios.
All this research will contribute to understanding where this catchment critical zone is most sensitive to future threats. However, it is important that this understanding reaches the people who need to use it. So the final activity we will undertake comes under the umbrella of 'knowledge exchange' - sharing our findings with those who need this research, and adjusting our understanding based on knowledge they too have. Thus our last, but not least, activity is working with those who live in the landscape and those who manage it, to help them identify how their activities can cause the least harm and offer the most protection to their ecosystem services.
Our collaboration with Chinese colleagues is therefore crucial. We bring new skills to the project (e.g. new hydrological modelling skills) that they will benefit from. Additionally as catchment management practices will be quite different across UK-China, they will learn about other good practice to help improve their environment and remove residents from poverty

Planned Impact

The following will benefit from this research:
1. Those living in and managing the 'research' catchment (and wider karst systems) will benefit from a better understanding of the critical zone system resilience, and threats to, its ecosystem services. This knowledge will allow them to think about how best to manage their environment and will lead to improvements in their quality of life, ensuring the fundamental needs (access to water of appropriate quality) and how to manage water resources (to also ensure sustainable soils for food provisioning), are underpinned by a useful knowledge-base.
2. The catchment managers, and those responsible for innovation, that will visit comparable UK organisations will benefit from a deeper understanding of best practise.
3. This joint research will be of benefit to NSFC, raising their profile in the UK and amongst other critical zone scientists. The skill and information exchange that will occur during this research with Chinese colleagues, ultimately demonstrating to the international scientific community, that we value sensitive environments internationally, and particularly international co-operation in research, will help consolidate each country's position as a future key research partner and particularly the Chinese National Science Foundation as a partner of choice for future co-funded research.
4. Through publication and conference activity, the SUERC AMS (NERC-recognised Facility) will receive publicity in China for excellence in novel 14C-dating approaches. They will benefit through enhanced international standing and resultant funded research collaboration.
5. The wider public, and local communities hosting the research, will benefit during the research activity through research team communication activity that meets their passion for and excites them to understand the natural world more deeply. In turn if this encourages greater interest in STEM subjects, the relevant country science base will benefit.


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Description This UK funding for our grant finished in 2018 (end), and our Chinese partners' grant had another year to run and has just finished. The post-doc has returned to the Chinese group, so the ongoing interaction is strong.
The papers are coming out now and I would expect to for another year or so. The dataset is an in advanced stage of submission to CEH EIDC.
Our key findings are detailed understanding of how and when nitrate is released from Chinese agricultural karst soils to drainage systems and quantative understanding of how much nitrate is exported and when water quality is compromised. From isotope data we can partition the source of the nitrate.The hydrological modelling to understand where water is coming from is coming has partitiioned fast, medium and slow flow pathways and is now creating a new set of models that links the biogeochemical and hydrological processes. Sythetic fertiliser appears to be the dominant source of nitrate pollution and most nitrate is exported during rainfall events and in the wet season.
The knowledge exchange work-package has been particularly effective, with key findings here being the lack of KE activity there is in China, and that farmers learnt most from family and friends and so approaches to sharing information should be reconsidered.
Exploitation Route Environment agencies may be interested in the sensor technology. We have a second PDRA employed on a knowledge exchange component of the grant and she is making good inroads in understanding how the process of knowledge exchange may function effectively in China. This may be of wider value to all UKRI projects in China.
The findings of this project are now being used in a follow-on project that seeks to create decision support tools (also funded by NERC and started in Jan. 2019)
Sectors Agriculture, Food and Drink,Environment,Government, Democracy and Justice

Title Hydrochemistry and nitrate sensor data from three karst sites in SW China, 2016-2017 
Description The dataset contains hydrochemistry (temperature, specific conductivity, pH, dissolved oxygen) and nitrate-N in the Houzhai catchment (Southwestern, China). Three karst springs were investigated. Data were obtained via sensor approach with 15mins time interval between May 2016 to October 2017. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Title Literature review of knowledge management across the environment-policy interface in China 
Description Data from literature search systematically conducted using two widely-used academic databases: Web of Scienceā„¢ (WoS) and Scopus . Data include the annual amount of KM publication in China and across the world, in WoS, the total amount of knowledge management (KM) publication during the searched years for each country (top 20), in Scopus, the total amount of KM publication during the searched years for each country (top 20), information about the retained KM publication for environmental management in China. The data were generated during the NERC grant 'The transmissive critical zone: understanding the karst hydrology-biogeochemical interface for sustainable management' reference NE/N007425/1 undertaken as part of the NERC Using Critical Zone Science to Understand Sustaining the Ecosystem Service of Soil & Water (CZO) programme. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Title Stakeholder surveys to local farmers and officials in Chinese villages to understand knowledge management dynamics 
Description Data comprise results of social surveys carried out in China during 2016 - 2018 to the local stakeholders (farmers and village to county level officials) to understand their knowledge learning dynamics and preference. Surveys were conducted in the rural villages in Puding County, Guizhou Province and in Yujiang County, Jiangxi Province. The study was funded by the grant NE/N007425/1 which was awarded by the UK Natural Environment Research Council (NERC), and through cooperation with grant 41571130074 awarded by the National Natural Science Foundation (NSFC) of China, as part of the UK - China Critical Zone Observatory (CZO). 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Title Survey data of scientists on knowledge exchange in critical zone and geoscience 
Description Survey data on knowledge exchange experience of both Chinese and British scientists working on critical zone and more broadly on geoscience. Data are drawn from questionnaire surveys to explore the knowledge management methods used in their environmental research. Data are anonymised social survey data from questionnaires. The data were generated during the NERC grant 'The transmissive critical zone: understanding the karst hydrology-biogeochemical interface for sustainable management' reference NE/N007425/1 undertaken as part of the NERC Using Critical Zone Science to Understand Sustaining the Ecosystem Service of Soil & Water (CZO) programme 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes