Loading and Bioavailability of Colloidal Phosphorus in the Estuarine Gradient of the Deer Creek‐Susquehanna River Transect in the Chesapeake Bay
Loading and Bioavailability of Colloidal Phosphorus in the Estuarine Gradient of the Deer Creek‐Susquehanna River Transect in the Chesapeake Bay
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DOI：
10.1029/2019jg005135
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发表时间：
2019-12
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影响因子：
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通讯作者：
Qiang Li;Hezhong Yuan;Hui Li;Dengjun Wang;Yan Jin;D. Jaisi
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文献类型：
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作者：
Qiang Li;Hezhong Yuan;Hui Li;Dengjun Wang;Yan Jin;D. Jaisi
磷超载是地表水富营养化和底水缺氧的主要原因。对不同磷库及其在源汇连续体中相应的生物利用度的不完全了解限制了适当的养分管理策略的发展。在这里，我们应用多稳定同位素代理来跟踪胶体，并确定在Deer Creek - Susquehanna河口段胶体中的特定P池是否存在生物循环。结果表明，在夏季和冬季，NaOH - Pi是最主要的磷库。不同粒径的胶体组成的NaOH - Pi和HNO3 - Pi池的氧同位素值（δ18OP）比环境水中的平衡值范围重得多，这表明这两个池对生物吸收具有抵抗性。这进一步意味着这些P池的同位素特征可以用来识别胶体的来源。胶体的碳(C)和氮(N)同位素组成表明，陆源对萨斯克哈纳河下游向海湾的贡献逐渐减少，鹿溪对萨斯克哈纳河的胶体贡献不成比例地高。这些发现为研究河口生态系统中胶体磷的负载和相对生物利用度提供了有价值的信息。
Phosphorus (P) overloading is a major cause of surface water eutrophication and bottom water hypoxia. The incomplete understanding of different P pools and their corresponding bioavailability in the continuum from sources and sinks has limited the development of appropriate nutrient management strategies. Here we apply multistable isotope proxies to track colloids and identify whether specific P pools in colloids are biologically cycled at the Deer Creek‐Susquehanna River mouth stretch. Results showed that NaOH‐Pi is the most dominant P pool in the summer and winter seasons. Oxygen isotope values (δ18OP) of NaOH‐Pi and HNO3‐Pi pools of different size fractions of colloids are much heavier than the ranges of equilibrium values in the ambient water, which suggest that these two pools are recalcitrant against biological uptake. It further means isotopic signatures of these P pools could be used to identify the sources of colloids. Carbon (C) and nitrogen (N) isotope compositions of colloids showed that the contribution of terrestrial sources gradually decreases downstream of the river toward the bay and Deer Creek contributes disproportionately high amounts of colloids to the Susquehanna River. These findings provide valuable information on the loading of colloids and relative bioavailability of colloidal P pools in estuarine ecosystems.