Spatial and Temporal Distribution of Particulate Phosphorus and Their Correlation with Environmental Factors in a Shallow Eutrophic Chinese Lake (Lake Taihu).

Ming Kong,Guang Gao,Jianying Chao,Yu Wang,Zhaoshi Wu,Jun Hou,Peifang Wang,Chao Wang,Longmian Wang,Wei Zhuang

doi:10.3390/ijerph15112355

Abstract

Spatial and seasonal variations of particulate phosphorus (PP) in a large shallow, eutrophic Lake Taihu with different ecotypes (including a phytoplankton-dominated zone, lake center zone, estuary zone and macrophyte-dominated zone) were investigated. The results showed that particulate organic phosphorus (POP) was the dominant form of PP (>88.0%). The concentration of POP showed higher levels in the bloom-sensitive northwestern zone (phytoplankton-dominated zone and estuary zone) during warm seasons, phytoplankton blooms and input of exogenous particulate matter were the main sources of POP in the lake water. Based on 31P nuclear magnetic resonance (31P NMR) analysis, orthophosphate (Ortho-P) was the dominant molecular species of PP and positively correlated with soluble reactive phosphorus (SRP) (p < 0.01). This suggested that the release of Ortho-P from suspended particulate matter (SPM) was the main source of SRP in the lake water. Pyrophosphate (Pyro-P), which is regarded as a highly labile species of P compounds, represented a large fraction of PP, and its significant positive correlations with chlorophyll a (Chl a), indicated that the concentration of Pyro-P could be used as an important indicator for the degree of eutrophication of Lake Taihu. These results proved that PP in lake water was a significant factor supporting lake eutrophication and must be controlled.

Highlights

Phosphorus (P) is an important driver of primary production in surface waters
POP was the dominant form of PP, and correlation analysis revealed that POP was significantly correlated with total P (TP) in the overlying water (p < 0.01) (Table 2), which indicates that POP represents a important source of P in Lake Taihu
The concentrations of POP showed higher levels in hyper-eutrophic zones during warm seasons, and phytoplankton blooms and input of exogenous particulate matter were the main sources of POP in lake water

Summary

Introduction

Phosphorus (P) is an important driver of primary production in surface waters. Excessive P concentration is considered the most common cause of eutrophication [1], so it needs to be managed to avoid or reduce eutrophication. P species are found in dissolved and particulate fractions [2]. Particulate P (PP) often accounts for a larger proportion of total phosphorus than dissolved P [3], and acts as a potential source of dissolved P in lacustrine environments. PP is divided into particulate inorganic P (PIP) and particulate organic P (POP) [4].

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Discussion

Conclusion