| 内容提要: |
Determination method of fluorescein diacetate (FDA) has been widely used as a rapid and sensitive method for the quantification of microbial activity. However, as the current determination method of FDA is based on soil samples, there might be errors in its direct application to urban river sediments. Therefore, determination method of FDA in urban river sediments was optimized to improve experiential reproducibility in the present study. The optimized method describes quantitative measurement of the fluorescein produced when 1.8 g of fresh sediment is incubated with 50 mmol/L phosphate buffer solution (pH: 7.2) and 0.2 mL of 3 g/L FDA at 35 °C for 30-75 min under a rotation of 200 rpm. Subsequently, 8 mL acetone was added to terminate the reaction. The covariation coefficient of the optimized method ranged from 0.7% to 3.3%. In addition, the FDA hydrolytic rate was positively correlated with pollutants (e.g. organic matter, labile organic matter, total nitrogen and acidified volatile sulfides in sediments). Moreover, the establishment of multiple linear regression model provided valid evidence for predicting microbial activity in the sediments. |