Understanding how water moves and transforms throughout the environment, from the atmosphere to deep underground, is essential to predicting and protecting freshwater quality and quantity. For example, polluted water can move through soil, rocks, and infiltrate underground into aquifers, reacting with and contaminating these parts of the environment along the way.
EESA scientists have developed a new software system called Alquimia that allows models to more easily represent both the hydrology–the movement of water–in addition to the chemical reactions of water as it’s transformed throughout an ecosystem to better capture these processes that are critical to our understanding of where, and how much, clean water is available. The tool can be applied to improving models of many other important environmental aspects, such as estimating the amount of nutrients like carbon and phosphorus within soil, which can indicate soil health and productivity.
“There are many things happening in an ecosystem that we can’t see,” explained Sergi Molins, lead author of a recent publication describing the software. “That’s why we rely on models and simulations for our understanding of, for example, how far polluted water might infiltrate into the ground, or how much nitrogen is available in soil. By allowing different models to seamlessly connect and share data, Alquimia makes it easier to capture more of these types of processes that affect important factors like soil health, water quality, and ecosystem resilience.”
Incorporating geochemical processes in Earth system models
Ecosystems are home to multiple ever-changing processes and characteristics, from the exchange of nutrients and carbon between soil, plants, and the atmosphere, to evaporation, water infiltration, and rock weathering. Representing these in models to study how the interactive, simultaneously occurring processes can affect factors like water quality or soil health however remains a challenge. For example, withdrawing too much water from aquifers can cause naturally occurring contaminants (such as minerals leaching from rocks) to be released into the water, degrading quality. This is a multi-process phenomenon that scientists rely on models to understand.
Alquimia allows scientists to more easily simulate multiple interconnected chemical, physical, and biological processes, such as rock breakdown by precipitation (chemical), which releases nutrients for plants and microbes (biological). Before Alquimia, scientists would write new code or develop new models to represent a specific type of process. Now, researchers can use the technology to build complex simulations without needing to develop them from the ground up.
For example, to simulate how polluted water moves from soil into bedrock and how it reacts with the environment along the way, Alquimia can connect a hydrology model to a “geochemical engine,” a software that calculates chemical reactions. This simplifies the process of creating a model that shows both how polluted water might contaminate aquifers, but also how different elements in the aquifer–such as carbon from organic matter and organisms–might react with the water to mitigate the pollution.
Without the need to write original code connecting the two frameworks, Alquimia can ultimately save time, reduce error, and encourage model reuse and interdisciplinary collaboration.
Alquimia applications to watershed and land surface models models
Alquimia has been used in other efforts led by Molins, such as modeling watershed exports like water, sediments, and nutrients; Alquimia allowed the team to integrate preexisting geochemical codes into their Advanced Terrestrial Simulator (ATS) rather than developing and integrating an entirely new geochemical model. Mollins helped develop ATS–a code that models river and watershed hydrology as a basis to better understand plant growth, nutrient transport, ice within frozen soils, and more–along with a course teaching people how to use it.
“Alquimia helps modelers account for important geochemistry details,” said Molins. “For example, specific chemical conditions in the environment drive important reactions like weathering, nutrient availability and utilization by plants, decomposition, and more. Now we can easily incorporate these types of reactions that drive major processes in the environment.”
Alquimia has also been used in land surface process modeling, which simulates connected ecosystem processes such as gas exchange between the soil and atmosphere, or water retention by soils. Using Alquimia, geochemistry details were incorporated into a coastal wetland model to better understand how carbon and nutrient cycling changed under different conditions like temperature, seasonality, and precipitation.
Developing a better understanding of the natural world
In a world where ecosystem health and function are responding to rapid changes, Alquimia can foster interdisciplinary collaboration, accelerate scientific development, and make it easier to account for the multitude of dynamic processes in the environment. With more holistic models, Alquimia ultimately helps to advance predictions and simulations critical to understanding environmental health and resilience.
