Eutrophication is still a water quality problem within many watersheds. The Lake Okeechobee Basin, Florida, USA, like many watersheds is impacted by eutrophication caused by excess phosphorus (P). To meet water quality criteria to reduce this impairment, several levels of information on P dynamics within the Basin are required. The use of biogeochemical indices to help determine P retention/release of different landscape units such as wetlands and streams provides useful information on P dynamics. The objective of our study was to determine P retention/release indices for a range of wetland soils and their adjacent stream sediments. We sampled several wetlands and adjacent streams within Okeechobee's Basin, which represented a range of P impacted systems. Regression analyses suggest that a single incubation of sediment/soil equilibrated at 1000 mg P kg~(-1) was sufficient ( > 96% of the time) to estimate maximum P sorption capacity (S(max)). Using this single incubation, sampled wetlands had nearly twice the P sorption capacity (238 ± 21 mg P kg~(-1)) of stream sediments (146 ± 14 mg P kg~(-1)). Stream sediments also had a greater P saturation ratio (PSR) than wetland soils, indicating that sediment had a greater potential to release P. Phosphorus sorption under ambient P conditions (soil equilibrated with ambient site water) covaried best with P concentrations in site surface water and, as concentrations increased, P sorption also increased. Finally, we used soil P storage capacity (SPSC) to help estimate the ability of soils and sediments to retain additional P loadings and found that wetland soils had a greater ability to retain P. Phosphorus sorption was predicted equally well ( > 73%) using either ammonium oxalate or 1 M HC1 extractable Fe and A1. The use of indices to quantify P dynamics of different landscape units can inform watershed management and policies aimed at reducing P loads to receiving water bodies.
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机译：富营养化仍然是许多流域内的水质问题。像许多分水岭一样，美国佛罗里达州的奥基乔比湖盆地也受到过量磷（P）引起的富营养化的影响。为了满足水质标准以减少这种损害，需要在流域内提供有关P动力学的多个信息水平。利用生物地球化学指标来帮助确定不同景观单位（如湿地和溪流）的磷保留/释放情况，可提供有关磷动力学的有用信息。我们研究的目的是确定一系列湿地土壤及其邻近河流沉积物的磷保留/释放指数。我们在奥基乔比盆地内的几个湿地和邻近溪流中进行了采样，这代表了一系列受磷影响的系统。回归分析表明，以1000 mg P kg〜（-1）平衡的沉积物/土壤的单次孵育足以（> 96％的时间）估算出最大的P吸附能力（S（max））。使用这种单次温育，采样的湿地对河流沉积物的磷吸附能力（238±21 mg P kg〜（-1））几乎是其两倍（146±14 mg P kg〜（-1））。河流沉积物还具有比湿地土壤更大的P饱和度（PSR），这表明沉积物具有更大的释放P的潜力。在环境P条件下（土壤与周围场地水平衡）磷吸附与场地表层水中的P浓度最佳相关随着浓度的增加，磷的吸收也增加。最后，我们利用土壤磷的储量（SPSC）来帮助估算土壤和沉积物保持额外的磷负荷的能力，并发现湿地土壤具有更高的磷保持能力。磷吸附的预测同样好（> 73％）。草酸铵或1 M HCl可提取的Fe和Al。使用指数来量化不同景观单元的磷动态可以为流域管理和旨在减少接收水体的磷负荷的政策提供信息。
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