Since total organic carbon (TOC) is not a routine hydrological monitoring data, the monitoring frequency is much lower than that of flow data and it often has missing values, which makes it difficult to evaluate TOC flux. This study proposes an improved computational model based on functional data analysis (FDA) for the evaluation of riverine TOC fluxes. First, the discrete data set is functionalized, and all the indicators are transformed into s function curves in the same evaluation time domain. And then the TOC flux of the evaluation section during the study period is calculated by Riemann integral. The results of the TOC evaluation at the Zhutuo station on the Yangtze River show that, The average value of the annual TOC flux at Zhutuo Station from 2018 to 2020 is 702 000 t; The intra-annual distribution of TOC fluxes is extremely uneven, with a high concentration in the flood season, especially in summer; The annual average value of TOC flux during the flood season (June to September) is 438 200 t, equivalent to 62.43% of the total; The annual average TOC flux in summer is 349 000 t, equivalent to 49.72% of the total; While the annual average value of TOC flux during the dry season (October to May) is 263 700 t, equivalent to 37.57% of the total; The annual average TOC flux in winter is 71 300 t, equivalent to 10.15% of the total; Compared with the traditional method, the improved TOC flux model is also able to deal with missing values and inconsistencies in multi-indicator monitoring sequences more effectively, and to accurately assess the course of TOC fluxes over different seasons and periods of abundance and depletion.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |