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| Estimation and sources apportionment of nonpoint source phosphorus load in a typical subtropical agricultural and forestry watershed |
| Received:August 09, 2022 |
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| KeyWord:dissolved phosphorus;adsorbed phosphorus;load model;nonpoint source pollution |
| Author Name | Affiliation | E-mail | | LI Qing | School of Forestry, Central South University of Forestry and Technology, Changsha 410004, China
Key Laboratory of Subtropical Agroecological Process, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China | | | TANG Daisheng | School of Forestry, Central South University of Forestry and Technology, Changsha 410004, China | | | MENG Cen | Key Laboratory of Subtropical Agroecological Process, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China
Changsha Agricultural Environment Observation and Research Station, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China | mengcen@isa.ac.cn | | LI Yuyuan | Key Laboratory of Subtropical Agroecological Process, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China
Changsha Agricultural Environment Observation and Research Station, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China | | | WU Jinshui | Key Laboratory of Subtropical Agroecological Process, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China
Changsha Agricultural Environment Observation and Research Station, Institute of Subtropical Agricultural Ecology, Chinese Academy of Sciences, Changsha 410125, China | |
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| Abstract: |
| Jinjing watershed, a subtropical watershed primarily used for agriculture and forestry, is the focus of this study. Specifically, we constructed a nonpoint source phosphorus load estimation model to estimate phosphorus load. Moreover, we also analyzed the spatial distribution characteristics of each form of phosphorus load. The modified output coefficient model and the revised universal Soil Loss Equation（RUSLE）were used to establish the dissolved and adsorbed phosphorus modules of the model; simultaneously, the posterior distribution of parameters of the output coefficient model was obtained through Bayesian statistical inversion to improve the accuracy of the model's simulations. The absolute error between the modeled and observed values of total phosphorus ranged from 3.3% to 27.1%. The coefficient of determination（R2）and Nash efficiency coefficient（NSE）of dissolved phosphorus were 0.84 and 0.82, respectively; while the R2 and NSE of adsorbed phosphorus were 0.68 and 0.65, respectively. The results showed that the average of the total phosphorus load of nonpoint sources was 64.3 kg·km-2·a-1, whereas the dissolved phosphorus load was 29.6 kg·km-2·a-1. Spatially, phosporus loads were mostly concentrated in farmlands and residential areas. Specifically, the dissolved phosphorus load of forests, farmlands, and residential areas were 13.4, 40.5 kg·km-2·a-1, and 31.1 kg·km-2·a-1, respectively. The average adsorption phosphorus load of the basin was 34.7 kg·km-2·a-1, and it was mostly concentrated in forest slopes. The adsorbed phosphorus load of forests, farmlands, and residential areas was 43.1, 16.5 kg·km-2·a-1, and 4.5 kg·km-2·a-1, respectively. The control of nonpoint source phosphorus load in subtropical hilly regions should to be conducted through targeted control measures, considering spatial distribution differences of different forms of phosphorus output. |
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