[Characterization of Phosphorus in Urban Surface Soils in Kaifeng City and Its Risk of Loss].

Characterization of phosphorus (P) and its risk of loss in urban soils in Kaifeng City, Henan Province were studied through field sampling and laboratory experiments. The spatial distribution of P and the map of risk of loss were obtained using geostatistical and spatial analysis techniques. The P content in urban soils ranged from 400 to 1427 mg·kg-1, the proportions of inorganic P in total P ranged from 65% to 99%, and Olsen-P and CaCl2-P in soils were 3.41-115.03 mg·kg-1 and 0.01-9.40 mg·kg-1, respectively. The composition of P was consistent in different urban areas and P concentrations were higher in residential areas. Spatial variations in P concentrations in soils were significant; the concentrations of P in eastern Kaifeng City were higher than those in western Kaifeng and the highest concentrations were detected in central Kaifeng. Olsen-P can be used as an indicator of the leaching risk of soil P. The critical value of leaching P from the soil was 22.18 mg·kg-1 and the concentration of Olsen-P in 33.64% of urban soil samples exceeded the critical value. The highest risk of P loss existed in central Kaifeng City.

[Refining sample preparation procedures for solution 3P-NMR analysis of organic P in sediment].

Solution phosphorus-31 nuclear magnetic resonance spectroscopy (31P-NMR) is a novel technology in characterization of organic phosphorus (P) composition in sediments. This study was aim to refine sample preparation procedures for 31P-NMR, including determination of sample pretreatment, extraction time, sample to extractant ratio and concentration method. The results showed that recovery of P with air dried sample treatment was higher than that for the fresh samples. Most of the P was extracted within the first 8 hours, and the time could extend to 12 to 16 hours in order to improve the recovery of P. Using the extraction ratio [m(sediment): V(extractant)] of 1:8 received more spectral signals compared to 1:20 when both the extracts were concentrated at the same time. No evident loss of P was found when the extract was concentrated at 28 degrees C followed by centrifugation under low temperature.

[Algal-flocculation removal by modified sediment of Taihu Lake in wind action].

Removal effects of cyanobcateria algal cells in chitosan-mediated in-situ-sediment in the sediment resuspension was studied in the laboratory. The research simulated the sediment suspension through quantitative simulated the middle-grade wave of lake Taihu, which usually experienced, by using the Y-type sediment resuspended generator. The results showed that the blue-green algal's removal effect is 93.55% and 99.19% as the dosage adding of chitosan and sediment were (0.100 + 0.200) g x L(-1) and (0.150 + 0.200) g x L(-1), respectively. The removal rate of turbidity of the water body reached 78.60% after still 30 min, in which the chitosan adding dosage was 0.150 g x L(-1); the removal rate of turbidity achieved 93.88% after 8 h of water body still. Furthermore, adding the chitosan could decrease the PO4(3-) -P concentration of water body in a short term. Preliminary results showed that the chitosan which adding dosage was 0.15 g x L(-1) could effectively remove the cyanobacteria cells in middle-grade wave situation; and also indicates using the chitosan-mediated sediment to flocculate the algal bloom of the Taihu Lake has a better application prospect. Contrast study shows that the quantitative simulation method of hydrodynamic intensity and the height of water has the obvious advantage to determine the dosage of chitosan in algal-flocculation removal.