Sustained deoxygenation in global flowing waters under climate warming

来自 <https://www.science.org/doi/10.1126/sciadv.aef3132>

## Abstract:

## Background:

Dissolved oxygen (DO), as a vital material sustaining aquatic ecosystems, has declined markedly in oceans, lakes, and coastal waters, yet unbiased understandings of changing DO concentrations in each individual river segment globally remain a challenge.

## What this paper did:

Here, weestimate DO concentrationsin 21,439 rivers globally between 1985 and 2023, based onLandsat observations and climatic data, andexamine their patterns and trends.

## Results/Findings:

We findsustained deoxygenationin global rivers, at a rate of −0.045 mg liter−1 decade−1, with 78.8% experiencing fluvial deoxygenation,driven mainly by oxygen solubility and temperature. Moreover, short-term heatwaves and dam impoundment exert non-neglecting influence on these changes. Future projections demonstrate that global fluvial DO concentrations decline by 1.1% ± 1.6% under SSP1–2.6 and 4.7% ± 2.7% under SSP5–8.5 throughout the 21st century.

## Implications:

Our study provides an unbiased baseline for escalating deoxygenation in global fluvial ecosystems that underscores targeted measures to mitigate deoxygenation threats and protect ecosystem health.

## Intro:

..

Satellite observations are recognized as promising ways to accurately monitor water quality in surface waters, and have been successfully applied to delineate sediment transport, water clarity, and algal bloom extents at global scales (30–32). Here, we used Landsat satellite imagery between 1985 and 2023 to systematically examine changes in fluvial DO concentrations, drawing an unbiased and comprehensive picture of global river deoxygenation risks and addressing three fundamental questions:

(i) Where and how have fluvial DO concentrations changed globally?

(ii) What have been the primary drivers behind these changes? Whether differ from regions?

(iii) How does fluvial DO respond to future climate warming?

Systematically understanding these changes is crucial for enhancing the resilience of fluvial ecosystems to sustained deoxygenation risks through targeted measures and strategies, and helps to achieve sustainable management in global rivers.

## Results:

Establishment of global fluvial DO database

Four decades of fluvial DO changes globally

Primary drivers of global fluvial DO trends

Future projections of sustained fluvial deoxygenation