Phosphorus Bioavailability and Release Potential Risk of the Sediments in the Coastal Wetland: A Case Study of Rongcheng Swan Lake, Shandong, China

Abstract

Rongcheng Swan Lake, a natural coastal wetland, is connected to Rongcheng Bay of Yellow Sea, China. In this lagoon, water quality has deteriorated gradually in recent 30 years and filamentous Chaetomorpha linum have bloomed during the past five years. In present study, the concentration, fractions, and bioavailability of phosphorus (P) in surface sediments were investigated throughout the lake. In order to evaluate P retention ability of the wetland, six sediment samples from different lake regions were collected to study P adsortion kinetics, adsortion capacity and the relation to sediment properties. In Swan Lake, total P concentrations in sediments varied from 79 to 616 mg/kg, which were significantly higher in northwest region than those in southeast region. Sediment grain size and external inputs were the main factors affecting P distribution. Inorganic P concentration was obviously higher than that of organic P, and Ca-P was the important form in the sediments. Fe/Al-P showed a large spatial variation, with relatively high concentrations occurring at the northeastern corner and the western tip strongly affected by the discharge of wastewater. The adsorption isotherms were well fitted by Linear equation at low P conditions and by Langmuir equation at high initial P concentrations, respectively. The sediments in the northern and central lake had higher P adsorption capacity, while in southern lake the degree of P saturation of the sediments was high. Ammonium oxalate extractable Al, organic matter, and fine particle were important factors influencing P adsorption. In Swan Lake, algae available P (AAP) was the largest form of bioavailable P, followed by Olsen-P; moreover, AAP and Olsen-P showed significant correlations with Fe/Al-P. As a whole, TP concentration in sediments from Swan Lake was low, and the sediments at most regions had buffering ability for P in overlying water; while at the western tip of lake where macroalgal blooms frequently breakout, AAP concentration was relatively high and the sediments had higher potential for releasing P into water column.

Reclamation Culture Alters Sediment Phosphorus Speciation and Ecological Risk in Coastal Zone of Southeastern China

“…The ERI is an important indicator of sediment P‐induced eutrophication risk, expressed by the following equation: where ERI is the eutrophication risk index. The PSI and DPS donate P sorption index and P adsorption saturation, respectively.…”

Forms and vertical distributions of soil phosphorus in newly formed coastal wetlands in the Yellow River Delta estuary

“…P entering these coastal wetlands, which is partitioned into organic or inorganic forms, will be partitioned into labile and refractory components to understand the soil P availability in the study of its biogeochemistry (Levy & Schlesinger, ). The transport and fate of P in soils are determined by the forms of P to a large extent (Gao, Zhang, & Shao, ; Reddy, O'Connor, & Schelske, ), and the proportion of these forms is mainly influenced by the soil, vegetation, and land use characteristics (P. Mao et al, ; W. Mao et al, ; Sun, He, Zhang, Shao, & Xud, ; G. Wang, Zhai, Liu, & Wang, ). So P as an important life element influences greatly soil fertility and land degradation by vegetation (Shao, Cui, & Bai, ).…”

“…As one important nutrient element, P forms have a close linkage with soil quality, further directly influencing land degradation, especially in the coastal zone (Gao et al, ; Tian, Zhai, Zhao, & Mu, ). Previous studies have used sequential fractionation to partition the soil P into inorganic, organic, and microbial forms (Levy & Schlesinger, ), which subdivided into the plant‐available forms (including Resin‐P i , NaHCO 3 ‐P i , and NaHCO 3 ‐P o ) and the refractory forms (including NaOH‐P i , NaOH‐P o , Dil.HCl‐P i , Conc.HCl‐P i , Conc.HCl‐P o , and Residual‐P; Yu et al, ).…”

Species and Characteristics of Organic Phosphorus in Surface Sediments of Northwest Region of Taihu Lake, Eastern China

“…Overall alkaline suggested that the pH of overlying water in the research area might facilitate the conversion from organic phosphorus to inorganic phosphorus. The internal release of phosphorus transferred from the sediment to water column due to biochemical and physical reactions was the important reason for increase of phosphorus concentration in water [8,36]. Origin of sedimentary organic matter could be distinguished by the C/N of compositions of different aquatic plants [37,38].…”