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Sediment phosphorus (P) fractions and sorption characteristics and P release from intact sediment cores of Baiyangdian Lake in North China in spring 2009 were investigated. Results of chemical fractionation showed that total P (TP) content in sediment ranged from 443 to 611 mg kg( -1). Of the P fractions including inorganic P (IP) and organic P (OP), IP was a dominant component of TP and present in the form of P bounded to calcium (Ca-P) while the bioavailable P content bounded to Al, Fe, and Mn oxides and hydroxides (Fe/Al-P) varied from 14 to 102 mg kg( -1). The batch experiments showed that the sediments had appreciable maximum P adsorption capacity from 141.86 to 377.37 mg kg( -1). However, the zero P equilibrium concentration (C⁰(eq))in most sampling sites was larger than the P concentration in water column. Accordingly, the sediments from those sampling sites would release P into the overlying water at the positive P flux rates as a P release source. Significant positive correlation between P flux rates and Fe/Al-P revealed that the sediment P release would mainly originate from the bioavailable P fraction. It is evident that the inherent phosphorus present in lake sediments would be a major threat to the water quality and ecosystem reservation in Baiyangdian lake.

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In an environment of high salinity, low temperature, and the presence of a few bacteria in seawater, improving the non-enzymatic hydrolysis of polyesters is one of the effective methods for developing seawater degradable materials. In this research, poly­(butylene furandicarboxylate-co-glycolate) (PBFGA) copolyesters were synthesized via melt polycondensation. The PBFGA copolymer possessed excellent mechanical properties and thermal stability. Its tensile strength was 15–50 MPa and the elongation at break was more than 120% from the tensile tests. GA units improved the flexibility of PBF segments, and the PBFGA copolymer exhibited an amorphous structure. The PBFGA copolymer possessed good hydrolysis properties and the weight loss of PBFGA50 was more than 30% after 84 days of degradation in deionized water. Lipase catalyzed, and the salt inhibited the hydrolysis of the ester bond. PBFGA exhibited a bulk degradation mechanism, and sponge pores were formed on the surface due to preferential degradation of the PGA component, which was conducive to the further degradation of the internal groups. Some butanediol and glycolic acid terminated oligomers were produced during the degradation process, and rearrangement crystallization occurred in the chain segment. Thus, PBFGA copolyesters have the potential to serve as promising seawater degradable materials with excellent tensile and non-enzymatic degradable properties.