Sources and Cycling of Phosphorus in the Sediment of Rivers along a Eutrophic Lake in China Indicated by Phosphate Oxygen Isotopes

作者：Ju Wang, Tao Huang, Qianqian Wu, Chengcheng Bu, Xijie Yin · 发表于：ACS Earth and Space Chemistry · 年份：2021 · DOI：10.1021/acsearthspacechem.0c00298 · 被引用次数：15 · 研究领域：Soil and Water Nutrient Dynamics、Aquatic Ecosystems and Phytoplankton Dynamics、Phosphorus and nutrient management

Sources and cycling of phosphorus in the sediment of inflow rivers (FL, TY and QY) along the eutrophic Chaohu lake, China were discussed by using the oxygen isotope compositions of phosphorus fractions of Fe/Al–P i and Ca–P i (SMT) and Fe–P i, Auth-P i, and Detr-P i (SEDEX). The δ 18 O Fe/Al-Pi (11.9‰–19.6‰) and δ 18 O Ca-Pi (9.6‰–18.2‰) in FL, TY, and QY river sediments deviated far from the isotopic equilibrium (δ 18 O p-equ, 19.4‰–21.5‰) in the Chaohu watershed. Depletion of δ 18 O Fe/Al-Pi in river sediments indicated a likely source of 18 O-depleted phosphates from the hydrolysis of organic phosphorus. The δ 18 O Ca-Pi values in FL sediments ranged from 9.6‰ to 13.7‰, indicating phosphate source from weathered soils; while those in TY and QY ranged between 11.5‰ and 18.2‰, indicating the Ca–P i was partly inherited from agricultural fertilizers and partly taken from domestic sewage. Significant correlations ( r = 0.85, P < 0.01) between δ 18 O Fe/Al-Pi and δ 18 O Ca-Pi of FL, TY, and QY river sediments indicated common phosphate sources for Fe/Al–P i and Ca–P i, and thus suggested the new formation of secondary Ca-bound phosphates. These recycling of phosphorus in FL, TY, and QY indicated by δ 18 O Fe/Al-Pi and δ 18 O Ca-Pi were supported further by the δ 18 O Fe-Pi, δ 18 O Auth-Pi and δ 18 O Detr-Pi in new TY sediments collected independently. This study provides a new perspective on understanding the sources and cycling of phosphorus in aquatic environments.