Development of determination method of bioavailable phosphorus using algal growth potential and sequence extraction and evaluation its runoff loading

将序列提取法和藻类生长势检测方法应用于长ara河流域和Asutani河流域河水和流域土壤中的悬浮物。采用序列提取法分离得到9种形态的颗粒磷。在藻类生长势的检测中，只使用来自河流水或流域土壤的悬浮固体中的颗粒磷。研究结果表明：1)暴雨期间，河流水体颗粒磷形态以碱溶无机磷、有机磷和与Fe、Mn结合的氧化还原敏感磷为主，这些形态在颗粒磷中的含量在75% ~ 90%之间。生物有效磷与颗粒磷的比值在30% ~ 40%之间。2)森林表层土壤磷约50%为有机磷，水田表层土壤磷约40%为与铁和锰结合的氧化还原敏感磷。3)藻类生长势检测表明，磷的颗粒形式可用于藻类生长。4)藻类生长势测定表明，森林表层土壤和水田表层土壤生物有效磷占总磷的比例分别为60%和90%左右。5)序列提取法计算的生物有效磷与颗粒固体的比值高于藻类生长势测定法。结果表明，序列提取法可用于颗粒物中生物有效磷的定量测定。通过藻类生长势检测来了解提取序列、提取方法和生物利用度差异的原因还需要进一步的研究。

The sequence extraction method and algal growth potential examinations were applied to suspended solids in river water and watershed soil of the Nagara River watershed and the Asutani River watershed. Particulate Phosphorus were separated and defined as 9 forms by the sequence extraction method. Only particulate phosphorus in suspended solids from the river water or the soil of the watersheds used in the algal growth potential examinations.The results of this study are the following :1)During storm events, the inorganic phosphorus compounds soluble in bases, organic phosphorus, and redox-sensitive phosphorus bound to Fe and Mn were dominated among the particulate phosphorus forms of the river water, and the content of these phosphorus forms in particulate phosphorus ranged from 75% to 90%. The ratio of bioavailable phosphorus to particulate phosphorus was between 30% and 40%.2)About 50% of total phosphorus in forest surface soil was organic, and about 40% in the paddy field surface soil was redox-sensitive phosphorus bound to Fe and Mn.3)The algal growth potential examination indicated that the particulate form of phosphorus could be available for algal growth.4)The algal growth potential examinations showed that the ratio of bioavailable phosphorus to total in forest surface soil and in paddy field surface soil were about 60% and 90%, respectively.5)The ratio of bioavailable phosphorus to particulate solids calculated by the sequence extraction method was higher than that by the algal growth potential examination.These results suggested that sequence extraction method is useful for the quantitative determination of bioavailable phosphorus in particulates. Further studies are necessary to know the reason of the difference between extracted sequence extraction method and bioavailability by algal growth potential examination.