Source: Earth’s Future
Rivers flow through many types of terrain, interacting with soil, rocks, microbes and roots. River water therefore carries signatures of everything it interacts with, and its chemistry reflects the response of the critical zone – the region of the planet that extends from the tops of trees to the bottom of the water table – to climate change. On the same subject : Guide to the 2022 World Games tournament, Part 1: Sports Games. River chemistry will likely change with warming climate, but most climate-related research studies have focused on changes in river flow.
Now, Li et al. focus on changes in river chemistry and water quality under a changing climate. They investigated the influence of climate on the long-term chemistry of rivers in the contiguous United States, compiling more than 400,000 data points from 506 rivers with minimal human impacts to identify patterns of 16 common river chemical constituents (solutes).
For all geographic areas of the United States, the team found that concentrations of 16 solutes decrease with increasing mean river flow, which is the amount of precipitated water (rain and snow) that ends up in streams and rivers. This finding contradicts the common perception that river chemistry is primarily controlled by the abundance of local materials in the critical zone. Instead, river chemistry is controlled first by the river’s discharge, then by the abundance of materials the water interacts with.
Changes in climatic conditions – including higher temperatures – can influence not only the flow of the river, but also the types of materials in the critical zone that interact and dissolve in the water. The authors say that in places that become drier, such as western parts of the United States, average concentrations are expected to increase, and the magnitude of the increase depends on the sensitivity of solutes to changes in discharge. In places that become wetter, average concentrations are likely to decrease, but loads, or export rates of solutes leaving rivers, may increase with more water.
As the climate changes, increasing solute concentrations will have implications for water management and treatment efforts and may require renewed or increased treatment infrastructure. These changes can also have significant impacts on the health of the aquatic ecosystem. (The Future of Earth, https://doi.org/10.1029/2021EF002603, 2022)
—Sarah Derouin, science writer
Citation: Derouin, S. (2022), Impact of climate on river chemistry across the United States, Eos, 103, https://doi.org/10.1029/2022EO220358. Published on 26 July 2022.
