Prediction of Three Sediment Phosphorus Indexes on Water Column Phosphorus Across Seasons in the Xiashan Reservoir, Northern China
2025
Wei Liu | Fang Hu | Songjie Fu | Zhenjun Liu | Yongchao Yu | Shan Jiang | Lanwei Liang | Xuemei Chen | Yang Jiao | Sen Gu | Qingman Li
Internal phosphorus (P) loading is a key driver of waterbody eutrophication. Various sediment P indexes are developed to assess sediment P risks by linking them to water column P, but their seasonal reliability remains underexplored. This study evaluated, for the first time, sediment P status in the Xiashan reservoir, a large shallow reservoir in northern China serving 9.4 million people. The ability of three P indexes, including exchangeable P (Ex-P), Olsen P (Olsen-P), and diluted HCl-extractable P (HCl-P), to predict water column P concentrations was tested across February, May, and August. Sediments in the Xiashan reservoir exhibited moderate total P levels (531&ndash:650 mg kg&minus:1) but high P availability, with Ex-P, Olsen-P, and HCl-P in ranges of 19&ndash:35, 58&ndash:101, and 327&ndash:444 mg kg&minus:1, respectively, likely due to sandy composition. Water column P concentrations significantly correlate with August sediment P indexes (r = 0.42&ndash:0.81) but not with February and May sediments, highlighting the ability of August sediment P indexes to predict water column P across seasons. Sampling in August is recommended to efficiently identify critical zones for internal P loading, with Ex-P as the preferred indicator given its simple extraction and strong correlation with water column P (r = 0.81).
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