The total N in enviromental samples is commonly determined by K_2S_2O_8-spectrophotometric method,and the total P is commonly determined by phosphatic molybdenum spectrophotometry.

• 环境样品总氮的测定常用过硫酸钾氧化-紫外分光光度法测定,而总磷一般为磷钼蓝分光光度法。