Lanthanum-doped ordered mesoporous hollow silica spheres were fabricated and utilized as phosphate adsorbents for the first time. Our prepared adsorbents exhibited spherical shapes with macropores in the center and ordered 2D hexagonal mesopores in the shell. By increasing the actual loading of La from 4.19 wt% to 22.44 wt%, the BET surface areas of the adsorbents decreased from 987.48 m 2 g À1 to 420.38 m 2 g À1 , coupled with a decline in average pore diameters and total pore volumes. In the batch adsorption tests, the adsorbents with greater amounts of La loading possessed markedly enhanced adsorption capacities; in contrast, the un-doped pure ordered mesoporous hollow silica particles could hardly adsorb any phosphate in solution. The adsorption isotherms of the La-doped ordered mesoporous hollow silica spheres were represented better by using the Langmuir model than the Freundlich model. The sample with 22.44 wt% La loading exhibited a maximum phosphate capture capacity of 47.89 mg P g À1 . In the kinetic study, its phosphate adsorption followed the pseudo-secondorder model well. Moreover, a dramatically fast kinetic adsorption was observed in the solution with a low phosphorus concentration of 2 mg P L À1 ; the adsorption equilibrium was reached in 15 min, with a 99.71% phosphate removal rate. High adsorption capacities were achieved within the pH range 3.0 to 8.0; relatively high selectivity to phosphate was observed in the presence of coexisting anions.

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The present three-year field investigation on sediment in the eutrophic Pearl River in South China showed that concentrations of sulfonamides (SAs), fluoroquinolones (FQs), and macrolides (MLs) in the river areas where blooms occurred were 4.6, 2.4, and 3.4 times higher than those without blooms, respectively, but the respective concentrations of tetracycline (TC) and oxytetracycline (OTC) in the areas with blooms were 2.6 and 3.8 times lower than those without. Significant positive correlations were found between concentrations of chlorophyll a in water and most antibiotics in sediment. Further investigation in each season suggested that lower diffusion but higher sinking were possible reasons driving the burial of sulfapyridine (SPD), sulfamethoxazole (SMX), and trimethoprim (TMP) in sediment from areas where blooms occurred, with burial rates up to 14.86, 48.58, and 52.19 g month–1, respectively. Concentrations of TCs in both water and sediment were inversely correlated with phytoplankton biomass, which might be related to the enhanced biodegradation capacity of bacteria caused by phytoplankton blooms. Phytoplankton also affected concentrations of antibiotics in the snail, Bellamya purificata, with higher values in March but lower values in September. The concentration of antibiotics in snails positively correlated with that in sediment when snails were dormant but with antibiotics in water after dormancy.

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