Nitrate loading projection is sensitive to freeze-thaw cycle representation.
Nitrate loading projection is sensitive to freeze-thaw cycle representation.
复制标题
硝酸盐负荷预测对冻融循环的呈现方式很敏感。
DOI：
10.1016/j.watres.2020.116355
复制
发表时间：
2020-08
期刊：
影响因子：
12.8
通讯作者：
Qianfeng Wang;Junyu Qi;Jia Li;J. Cole;Stephanie T. Waldhoff;Xuesong Zhang
中科院分区：
文献类型：
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作者：
Qianfeng Wang;Junyu Qi;Jia Li;J. Cole;Stephanie T. Waldhoff;Xuesong Zhang
气候变化可能对氮径流产生重大影响，而氮径流是淡水和沿海地区富营养化、有害藻类大量繁殖和缺氧的主要原因。我们研究了硝酸盐负荷对气候变化的响应，在上密西西比河流域（UMRB）与增强的土壤和水评估工具与基于物理的冻融循环表示（SWAT-FT），与原来的SWAT模型，采用经验方程。在代表性浓度路径（RCP）8.5情景下，从1960年至2099年的五个大气环流模式（GCM）的未来气候预测的驱动下，我们分析了河流硝酸盐负荷的变化，以及陆地表面和地下的UMRB在21世纪相对于基线期1960-1999年的贡献。到21世纪末，原始SWAT模型预测河流硝酸盐负荷增加约50%，几乎是SWAT-FT估计的两倍。25%）。预计硝酸盐变化的如此大的差异可能会误导旨在减少UMBR氮径流的缓解策略。进一步的分析表明，原始SWAT模型和SWAT-FT之间的差异，导致在UMBR的表面和地下硝酸盐负荷的空间分布的实质性差异。在一般情况下，SWAT-FT预测更多的硝酸盐淋溶的UMRB西北部地区，冻融循环更敏感，主要是因为SWAT-FT模拟不太频繁的冻土。这项研究强调了在水质建模中使用基于物理的冻融循环表示的重要性。未来氮径流减少战略的设计应包括仔细评估土地管理对冻融循环的影响，以提供可靠的预测气候变化下的水质。
Climate change can have substantial impacts on nitrogen runoff, which is a major cause of eutrophication, harmful algal blooms, and hypoxia in freshwaters and coastal regions. We examined responses of nitrate loading to climate change in the Upper Mississippi River Basin (UMRB) with an enhanced Soil and Water Assessment Tool with physically based Freeze-Thaw cycle representation (SWAT-FT), as compared with the original SWAT model that employs an empirical equation. Driven by future climate projections from five General Circulation Models (GCMs) from 1960 to 2099 under the Representative Concentrations Pathways (RCP) 8.5 scenario, we analyzed changes in riverine nitrate loadings, as well as terrestrial surface and subsurface contributions of the UMRB in the 21st century relative to the baseline period of 1960–1999. By the end of the 21st century, the original SWAT model predicted about a 50% increase in riverine nitrate loadings which is nearly twice as much as that estimated by SWAT-FT (ca. 25%). Such a large difference in projected nitrate changes can potentially mislead mitigation strategies that aim to reduce nitrogen runoff from the UMRB. Further analysis shows that the difference between the original SWAT model and SWAT-FT led to substantial discrepancies in the spatial distribution of surface and subsurface nitrate loadings in the UMRB. In general, SWAT-FT predicted more nitrate leaching for northwestern parts of the UMRB which are more sensitive to freeze-thaw cycle, mainly because SWAT-FT simulated less frequent frozen soils. This study highlights the importance of using physically based freeze-thaw cycle representation in water quality modeling. Design of future nitrogen runoff reduction strategies should include careful assessment of effects that land management has on the freeze-thaw cycles to provide reliable projection of water quality under climate change.