Abstract
Phosphorus (P) is an essential nutrient for aquatic organisms; however, excessive P inflow to limnetic ecosystems can induce eutrophication. P concentrations in the rivers, wetlands and lakes of Eastern China have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the distribution and speciation of P is lacking at the regional scale. We determined the distribution and speciation of P in limnetic ecosystems in Eastern China using Standards, Measurements and Testing (SMT) and phosphorus nuclear magnetic resonance (31P-NMR). The results indicate that P pollution in surface sediments was serious. Inorganic P (Pi) was the primary drive of variation in total P (TP) among different river systems, and Pi accounted for 71% to 90% of TP in surface sediment in Eastern China. Also, the concentrations of TP and Pi varied among watersheds and Pi primarily drove the variation in TP in different watersheds. Sediments less than 10-cm deep served as the main P reservoir. Environmental factors affect the speciation and origin of P. NaOH-Pi, HCl-Pi and organic P (Po) were related to pH accordingly at the regional scale. The physicochemical properties of sediments from different limnetic ecosystems affect the P speciation. HCl-Pi was higher in wetland sediments than in riverine and lake sediments in Eastern China. Conversely, NaOH-Pi was lowest in wetland sediments. Total Po concentration was lower in riverine sediments than in other sediments, but Mono-P was higher, with an average concentration of 48 mg kg−1. Diesters-P was highest in lake sediments. By revealing the regional distribution of TP, Pi and Po, this study will support eutrophication management in Eastern China.
Highlights
Phosphorus (P) is an essential element for all organisms, and P availability can impact the rate of primary production in aquatic ecosystems [1]
The total P (TP) concentrations in most of the sampling points were higher than 500 mg kg-1
Pi was the main component in TP, with the concentration ranged from 243.58 to 1097.13 mg kg-1, and the percentage of Pi to TP ranged from 71.98 to 90.25%
Summary
Phosphorus (P) is an essential element for all organisms, and P availability can impact the rate of primary production in aquatic ecosystems [1]. Since the middle of the 20th century, increasing application of P fertilizers has created a one-way flow of P from bedrock to farms and into rivers, lakes, wetlands and oceans that has dramatically influenced aquatic ecosystems worldwide [3]. In the last two decades, China has the booming economy around the world with GDP growth of nearly 8% annually [4]. During this time, human agricultural and industrial activities have greatly increased P generation and consumption, accelerating the rate of P bioactivity [5]. The resulting P loads in the watershed greatly increase the risk of eutrophication in surrounding rivers, lakes and marine systems [9]. P stored in the sediment can induce environmental problems, and disrupt the P biogeochemical cycle, causing new challenges for the sustainability of finite P resources [7]
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