Implications of phosphorus partitioning at the suspended particle-water interface for lake eutrophication in China's largest freshwater lake, Poyang Lake

Nutrient partition, especially for phosphorus (P), has been prominently changed that was caused by variation of river-lake relationship during the post-Three Gorges Reservoir and catchment alternations. Changes in proportion of total particulate phosphorus (TPP) and total dissolved phosphorus (TDP) might accelerate lake eutrophication, but limited attention has been paid to P partition over suspended particle (SP) levels. Data analysis showed that SP concentration presented a positive effect on TPP in wet season and soluble reactive phosphorus (SRP) in dry season, indicating seasonal physical and chemical variations. Based on this phenomenon, we proposed a hypothesis that the SP levels would affect TDP and TPP proportions by partition in aqueous-solid. It was found that using the parabola models to fit the sorption relationships of SRP and TDP (R-2 > 0.6, p < 0.01), the maximum sorption capacity (Q(max)) was 64.54 mg/kg and 60.52 mg/kg at 400 mg/L of SP level, respectively. In addition, the partition coefficients (K-P) of TDP and SRP were logarithmically increased with SP levels, indicating that higher SP levels (>400 mg/L) would hinder the sorption process. Furthermore, enhancing turbulence lead to less sorption of SRP and TDP at high SP levels (>800 mg/L). The sorption of SRP and TDP related to the presence of Fe/Al oxyhydroxides were enriched in the Fe/Al-P fraction (47% of TP). The findings of this study indicated that the low SP levels would increase P bioavailability for alga and is not conducive for lake eutrophication management. (C) 2020 Published by Elsevier Ltd.

Automated summary

The study revealed that suspended particle levels have a significant impact on the partitioning of phosphorus, affecting the proportions of TPP and TDP. Experimental results showed that SP concentration has a notable influence on the sorption relationships of phosphorus, with higher SP levels hindering the sorption process.