Water availability and seasonality shape elemental stoichiometry across space and time
Water availability and seasonality shape elemental stoichiometry across space and time
复制标题
水的可用性和季节性塑造了跨空间和时间的元素化学计量
DOI：
10.1002/eap.2842
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发表时间：
2023
影响因子：
5
通讯作者：
Golladay, Stephen W.
中科院分区：
文献类型：
--
作者：
Atkinson, Carla L.;Shogren, Arial J.;Smith, Chelsea R.;Golladay, Stephen W.
气候变化和人类取水量增加的相互作用预计将改变地表水的可用性和河流网络中碳（C），氮（N）和磷（P）的运输。但是，河流流量的变化将如何改变这些通量的平衡或化学计量尚不清楚。下弗林特河流域（LFRB）是一个州际流域的一部分，数百万人依赖于各种生态系统服务，包括季节性作物灌溉，市政饮用水供应和公共娱乐。最近，水需求增加加上干旱加剧，导致LFRB历史上常年河流停止流动，增加了生态系统的脆弱性。我们的目标是量化河流溶解的C：N：P在空间和季节上的变化，并确定每月化学计量通量如何与LFRB的主要支流的整体水供应变化。我们使用了溶质水化学（溶解有机碳，硝酸盐/亚硝酸盐，氨和可溶性活性磷）的长期记录（21-29年），以及单个LFRB流域内六个站点的长期流量数据。我们发现可溶性营养盐浓度和化学计量的空间和季节差异归因于地下水连接，存在一个主要的洪泛区湿地，和流动条件。此外，我们发现，水的可用性，如帕尔默干旱严重程度指数（PDSI）所示，强烈预测化学计量，通常较低的C：N和C：P和较高的N：P通量在低水可用性期间（PDSI < −4）。这些模式表明，随着人类需求对水的可用性产生巨大影响，可能会对河流生态系统功能产生长期和重大的变化，从而对溶质运移，流中处理和化学计量比产生影响。
The interaction of climate change and increasing anthropogenic water withdrawals is anticipated to alter surface water availability and the transport of carbon (C), nitrogen (N), and phosphorus (P) in river networks. But how changes to river flow will alter the balance, or stoichiometry, of these fluxes is unknown. The Lower Flint River Basin (LFRB) is part of an interstate watershed relied upon by several million people for diverse ecosystem services, including seasonal crop irrigation, municipal drinking water access, and public recreation. Recently, increased water demand compounded with intensified droughts have caused historically perennial streams in the LFRB to cease flowing, increasing ecosystem vulnerability. Our objectives were to quantify how riverine dissolved C:N:P varies spatially and seasonally and determine how monthly stoichiometric fluxes varied with overall water availability in a major tributary of LFRB. We used a long‐term record (21–29 years) of solute water chemistry (dissolved organic carbon, nitrate/nitrite, ammonia, and soluble reactive phosphorus) paired with long‐term stream discharge data across six sites within a single LFRB watershed. We found spatial and seasonal differences in soluble nutrient concentrations and stoichiometry attributable to groundwater connections, the presence of a major floodplain wetland, and flow conditions. Further, we showed that water availability, as indicated by the Palmer Drought Severity Index (PDSI), strongly predicted stoichiometry with generally lower C:N and C:P and higher N:P fluxes during periods of low water availability (PDSI < −4). These patterns suggest there may be long‐term and significant changes to stream ecosystem function as water availability is being dramatically altered by human demand with consequential impacts on solute transport, in‐stream processing, and stoichiometric ratios.