Distribution characteristics of phosphorus in the sediments and overlying water of Poyang lake.

Lingqing Wang,Tao Liang,Yanguang Chen

doi:10.1371/journal.pone.0125859

Abstract

Phosphorus (P) is a key indicator of the aquatic organism growth and eutrophication in lakes. The distribution and speciation of P and its release characteristics from sediments were investigated by analyzing sediment and water samples collected during high flow and low flow periods. Results showed that the average concentrations (ranges) of total phosphorus (TP) in the surface and deep water were 0.06 mg L-1 (0.03–0.13 mg L-1) and 0.15 mg L-1 (0.06–0.33 mg L-1), respectively, while the average concentration (range) of TP in sediments was 709.17 mg kg-1 (544.76–932.11 mg kg-1). The concentrations of TP and different forms of P varied spatially in the surface sediments, displaying a decreasing trend from south to north. P also varied topographically from estuarine areas to lake areas. The vertical distribution of TP and different forms of P were observed to decrease as depth increased. The P concentrations during the low flow period were higher than those during the high flow period. Inorganic phosphorus (IP) was the dominant form of P, accounting for 61%–82% of TP. The concentration of bioavailable phosphorus in sediments was relatively large, indicating a high risk of release to overlying water. The simulation experiment of P release from sediments showed that the release was relatively fast in the first 0-5 min and then decreased to a plateau after 1 hr. Approximately 84–89% of the maximum amount of P was released during the first hour.

Highlights

Eutrophication can result in significant deterioration in water quality due to the increased growth of undesirable algae and aquatic weeds followed by oxygen depletion due to biomass death and decomposition [1, 2]
The average concentration of Inorganic phosphorus (IP) in Poyang Lake sediments was 490.99 mg kg-1 in wet season and 549.38 mg kg-1 in dry season, accounting for 61%-82% of total phosphorus (TP) and showing that IP accounts for the majority of P in sediments
The average concentrations of TP and various forms of P in six cores decreased as depth increased

Summary

Introduction

Eutrophication can result in significant deterioration in water quality due to the increased growth of undesirable algae and aquatic weeds followed by oxygen depletion due to biomass death and decomposition [1, 2]. Lake eutrophication has become a serious environmental problem in China, especially for shallow lakes in the middle and lower reaches of Yangtze River area [3, 4]. Poyang Lake is the largest freshwater lake in China as well as an important river-connected lake in the lower Yangtze region. Over the past several decades, an increase in nutrient inputs has led to persistent harmful algal blooms, which significantly degraded water quality of Poyang Lake [5].

Methods

Results

Conclusion