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Title: Bioavailability and preservation of organic phosphorus in lake sediments: Insights from enzymatic hydrolysis and 31P nuclear magnetic resonance

Author
item ZHU, YUANRONG - Chinese Research Academy Of Environmental Sciences
item FENG, WEIYING - Chinese Research Academy Of Environmental Sciences
item LIU, SHASHA - Chinese Research Academy Of Environmental Sciences
item He, Zhongqi
item ZHAO, XIAOLI - Chinese Research Academy Of Environmental Sciences
item LIU, YONG - Chinese Research Academy Of Environmental Sciences
item GUO, JIANYANG - Chinese Research Academy Of Environmental Sciences
item GIESY, JOHN - Chinese Research Academy Of Environmental Sciences
item WU, FENGCHANG - Chinese Research Academy Of Environmental Sciences

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2018
Publication Date: 7/24/2018
Citation: Zhu, Y., Feng, W., Liu, S., He, Z., Zhao, X., Liu, Y., Guo, J., Giesy, J.P., Wu, F. 2018. Bioavailability and preservation of organic phosphorus in lake sediments: Insights from enzymatic hydrolysis and 31P nuclear magnetic resonance. Chemosphere. 211:50-61. https://doi.org/10.1016/j.chemosphere.2018.07.134.
DOI: https://doi.org/10.1016/j.chemosphere.2018.07.134

Interpretive Summary: Knowledge of phosphorus (P) biogeochemical cycling in sediments is fundamental to understanding the relationships between P supply and eutrophication processes in lakes. Sediments are an important component of lake ecological systems, and are a sink and an endogenous source of pollutants and nutrients. The contents, forms, and distribution characteristics of nutrients trapped in lake sediments are closely related to the nutrient status of the lake water column. In this study, the records of several nutrients in core sediments from Lake Dianchi, China were analyzed. The bioavailability of organic phosphorus from these samples was analyzed by the method of enzymatic hydrolysis. The eutrophic history of Lake Dianchi was discussed, and then biogeochemical cycling of P was studied for the different stages of the evolution of Lake Dianchi, especially in the eutrophication stage when the external P inputs were, to a large extent, controlled. The results of this study demonstrate that nutrient accumulation and biogeochemical cycling of P were closely related to the ecological evolution of Lake Dianchi. With limited release of mineral P and reduced external P inputs, bioavailable organic P would have played an important role in maintaining the eutrophic status of Lake Dianchi in the recent years.

Technical Abstract: Knowledge of phosphorus (P) biogeochemical cycling in sediments is fundamental to understanding the relationships between P supply and eutrophication processes in lakes. Two sediment profiles were collected from Lake Dianchi, a eutrophic lake in Southwest China. We investigated the lake’s evolution by studying the composition of organic matter, biogenic silica (BSi), and P fractions recorded in the sediment profiles. We were able to classify Lake Dianchi’s evolution into three distinct phases based on these parameters: Section I (oligotrophic: 55–32cm); Section II (mesotrophic: 32–12cm); Section III (eutrophic or hyper-eutrophic: 12–0cm). Biogeochemical cycling of P varied through the different evolution stages. Bioavailable organic P (Po) and Fe/Al-P were in equilibrium in the oligotrophic stage, during which the concentrations of P in the lake were controlled by adsorption or desorption at the sediment-water interface. In the mesotrophic stage, there was gradual release of bioavailable Fe/Al-P and accumulation of bioavailable Po. During the eutrophic stage, large amounts of bioavailable Fe/Al-P were transformed to Po and bioavailable Po, such as labile monoester P and diester P, in the P biogeochemical cycling process. With limited release of bioavailable Fe/Al-P and reduced external P inputs, bioavailable Po would have played an important role in maintaining the eutrophic status of Lake Dianchi in the recent years (4–0 cm of sediment). A (bioavailable Po)/(Fe/Al-P) index would be valuable for evaluating trends in the evolution of lake ecosystems.