扰动状态下pH值对内源磷生物有效性的影响

为了阐明底泥扰动状态下pH值对内源磷生物有效性的影响机制,以富营养化河流的底泥和上覆水为材料,通过实验室试验模拟了不同初始pH值条件下,底泥扰动对上覆水中溶解性磷酸盐(SRP)和底泥中生物有效磷(BAP)含量的影响。结果表明,底泥扰动显著降低了上覆水中SRP含量,其去除率随着初始pH值升高而降低。去除率从大到小依次排序为,pH5>pH7>pH9.5.SRP的去除与较低初始pH值条件下生成的非晶型铁氧化物有关。基于不同形态磷的迁移活性,采用NH4Cl-P+%BD-P(非闭蓄态Fe-P)+NaOH-nrP估算BAP是合理的.由此计算可知,BAP占总磷(Tot-P)的百分比随着初始pH值升高而降低。不同初始pH值条件下,BAP占Tot-P的百分比为33.36%(3种初始pH值条件下的平均值),该值远小于通过传统方法计算的BAP含量占Tot-P的百分比(平均为85.04%)。但由于2种方法中计算的BAP占Tot-P的百分比的变化趋势恰好相反,其与藻类可利用磷的变化密切相关。

Effect of pH on Sedimentary Phosphorus Bioavailability under Sediment Disturbance Conditions

Effect of pH values on bioavailability of sedimentary phosphorus under sediment disturbance was studied.With sediments and waters taken from a eutrophic canal,concentrations of soluble reactive phosphorus(SRP)in overlying water and changes of phosphorus bioavailability in the sediments as influenced by disturbance and initial pH values were done in laboratory experiments.Results showed that sharp decreases in SRP from overlying water,resulting from sediment disturbance,were observed and the removal of SRP decreased gradually with an increase in initial pH,with the order of SRP removal under different initial pH values as pH 5,pH 7 and pH 9.5,which was attributed to neoformation of amorphous Fe oxides under low pH values.Based on mobility of phosphorus fractionations,BAP could be accurately estimated by the sum of NH4Cl-P,% BD-P(bioavailable,non-occluded Fe-P)and NaOH-nrP.By this estimation,proportions of bioavailable phosphorus(BAP)to Tot-P decreased gradually with an increase in initial pH.Percentage of BAP to total phosphorus(Tot-P) was 33.36%,the mean under three pH values,which was far lower than 85.04% which was calculated by traditional methods.However,the percentage of BAP to Tot-P was verse visa under both methods,which attributed to the change of algae available phosphorus.