Nitrogen (N) loss is a significant source of water quality pollution in alluvial watersheds. However, the mechanisms linking N loss and elevated CO₂ concentration (eCO₂) are not well recognized. In this study, we comprehensively calibrated the SWAT model equipped with a dynamic CO₂ input and response module to investigate the response mechanisms between multiform N losses and eCO₂ in a representative large-scale watershed. Results revealed nitrate loss under eCO₂ exceeding 100% in some upstream zones under the SSP5-8.5 scenario (P < 0.05) compared to the constant CO₂ concentration. This was directly related to the great increase in hydrological variables, which were the carriers of N losses, and the intensive inputs of N fertilizer. Results also found that nitrate leaching was greater than the other two processes for future periods, peaking at 309.3%, as compared to the baseline period. The findings suggested reducing fertilizer inputs by 10%–20% was promising, especially for reducing nitrate loss through runoff and leaching by up to 17.7% and 12.2%. This study explored the mechanisms of increased N loss in response to eCO₂ and provided scientific evidence for early warning and making decisions to improve water quality at a large watershed scale.

中文翻译：

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评估黄金玉米带二氧化碳浓度升高对各种形式氮素损失的响应机制


氮（N）损失是冲积流域水质污染的重要来源。然而，氮损失和 CO ₂ 浓度升高 (eCO ₂ ) 之间的联系机制尚未得到充分认识。在本研究中，我们全面标定了配备动态CO ₂ 输入和响应模块的SWAT模型，以研究代表性大范围内多种形式N损失与eCO ₂ 之间的响应机制。分水岭。结果显示，与恒定 CO ₂ 浓度相比，在 SSP5-8.5 情景下，eCO ₂ 下某些上游区域的硝酸盐损失超过 100%（P < 0.05）。这与作为氮素流失载体的水文变量的大幅增加以及氮肥的密集投入有直接关系。结果还发现，与基准期相比，未来一段时期的硝酸盐浸出量高于其他两种工艺，峰值达到 309.3%。研究结果表明，减少化肥投入 10%–20% 是有希望的，特别是可以将径流和淋溶造成的硝酸盐损失减少 17.7% 和 12.2%。本研究探讨了eCO ₂ 导致氮素损失增加的机制，并为大流域范围内改善水质的早期预警和决策提供了科学依据。