Phosphorus export across an urban to rural gradient in the Chesapeake Bay watershed
Phosphorus export across an urban to rural gradient in the Chesapeake Bay watershed
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DOI：
10.1029/2011jg001782
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发表时间：
2012-03-01
影响因子：
3.7
通讯作者：
Belt, Kenneth T.
中科院分区：
文献类型：
--
作者：
Duan, Shuiwang;Kaushal, Sujay S.;Belt, Kenneth T.
人为来源的磷（P）的流域输出有助于淡水和沿海生态系统的富营养化。我们探讨流域城市化的影响的大小和出口流量分布的P沿着城乡梯度监测的巴尔的摩生态系统研究长期生态研究网站的一部分，在8个流域。可溶性活性磷（SRP）和总磷（TP）的输出量在森林和低密度居民用地的小流域最低（2.8-3.1 kg（-1）km（-2）yr（-1））。相比之下，SRP和TP输出随着流域不透水表面覆盖率的增加而增加，并在小城市流域达到最高值（24.5-83.7 kg（-1）km（-2）yr（-1））。沿着格温斯福尔斯（Gwynns Falls），一个土地利用混合的较大流域，最大比例的SRP（68%）和TP（75%）来自较低的流域，其中城市地区是主要的土地利用。负荷持续时间曲线分析表明，流域城市化的增加与磷输出向高流量条件（>2 mm d（-1））的转变有关。在城市水源地低流量条件下的SRP浓度在夏季最高，冬季最低。这种季节性模式是一致的沉积物培养实验表明，从沉积物中释放的SRP是温度依赖性。我们的研究结果表明，由于城市化和气候的变化，在径流和水温的变化，可以影响流水磷浓度和磷从城市流域的出口。
Watershed export of phosphorus (P) from anthropogenic sources has contributed to eutrophication in freshwater and coastal ecosystems. We explore impacts of watershed urbanization on the magnitude and export flow distribution of P along an urban-rural gradient in eight watersheds monitored as part of the Baltimore Ecosystem Study Long-Term Ecological Research site. Exports of soluble reactive phosphorus (SRP) and total P (TP) were lowest in small watersheds with forest and low-density residential land use (2.8-3.1 kg(-1) km(-2) yr(-1)). In contrast, SRP and TP exports increased with watershed impervious surface coverage and reached highest values in a small urban watershed (24.5-83.7 kg(-1) km(-2) yr(-1)). Along the Gwynns Falls, a larger watershed with mixed land use, the greatest proportion of SRP (68%) and TP (75%) was contributed from the lower watershed, where urban areas were the dominant land use. Load duration curve analysis showed that increasing urbanization in watersheds was associated with shifts in P export to high-flow conditions (>2 mm d(-1)). SRP concentrations during low-flow conditions at urban headwater sites were highest during summer and lowest during winter. This seasonal pattern was consistent with sediment incubation experiments showing that SRP release from sediments was temperature dependent. Our results suggest that shifts in streamflow and alterations in water temperatures owing to urbanization and climate can influence stream water P concentrations and P export from urban watersheds.