模拟降雨条件下潮土磷素流失特征及影响因素研究
Characteristics and influencing factors of phosphorus loss from fluvo-aquic soil under simulated rainfall conditions
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摘要: 潮土是我国重要的耕作土壤，磷素的流失不仅影响土壤肥力和作物产量，而且会增加地表水环境的污染负荷。本研究采用人工模拟降雨试验方法，研究了不同降雨强度和坡度条件下，潮土径流中磷素的动态变化和径流中磷素流失特征，以期为控制潮土区径流面源污染提供理论依据。结果表明：(1)整个降雨过程中，径流中总磷(TP)和颗粒态磷(PP)变化幅度大，而可溶性总磷(TDP)变化幅度小。降雨强度为30 mm·h-1时，不同坡度潮土中TP和PP浓度在整个降雨过程中呈波状变化；降雨强度为60 mm·h-1时，径流液中TP和PP浓度呈先上升再下降的趋势；降雨强度为90 mm·h-1时，坡度为8°条件下，TP和PP浓度在整个降雨过程中呈先上升后下降的趋势，而在坡度为15°条件下，TP和PP浓度在波动中下降。(2)潮土径流液中TP浓度范围为0.323~2.315 mg·L-1，TDP浓度范围为0.083~0.163 mg·L-1，PP浓度范围为0.240~2.152 mg·L-1，潮土径流中各形态磷浓度随着降雨强度和坡度的增加呈增加趋势。(3)潮土径流中TP和PP流失量随着降雨强度和坡度的增加呈增加趋势，而TDP流失量在8°条件下随着降雨强度的增加呈先上升后下降的趋势，在15°条件下呈增加趋势；颗粒态磷是潮土径流中磷素流失的主要形态。(4)潮土径流液中TP和PP流失量与降雨强度和坡度以及降雨径流量Q之间都存在明显的线性关系，为预测一定条件下潮土区径流中TP和PP单位面积流失量的估算提供了简便的计算方法和科学依据。Abstract:
Fluvo-aquic soil is an important cultivated soil in China.The loss of phosphorus not only affects soil fertility and crop yield, but also increases the pollution load of surface water environment.In this paper, an artificial rainfall simulation was conducted to study the dynamic changes of phosphorus and the characteristics of phosphorus loss in fluvo-aquic soil runoff under different rainfall intensities and slope gradients.The aim was to provide theoretical basis for controlling non-point source pollution of runoff in fluvo-aquic soil area.The results showed that: (1) total phosphorus(TP) and particulate phosphorus(PP) in runoff changed greatly, while total dissolved phosphorus(TDP) changed little during the whole rainfall process.When the rainfall intensity was 30 mm·h-1, the concentrations of TP and PP in the fluvo-aquic soil with different slopes fluctuated throughout the rainfall process; when the rainfall intensity was 60 mm·h-1, the concentrations of TP and PP in the runoff increased first and then decreased; when the rainfall intensity was 90 mm·h-1, the TP and PP concentrations increased first and then decreased under the condition of slope 8°, while the concentrations of TP and PP decreased with fluctuation under the condition of slope 15°.(2) The concentration of TP ranged from 0.323 to 2.315 mg·L-1, TDP from 0.083 to 0.163 mg·L-1, and PP from 0.240 to 2.152 mg·L-1 in fluvo-aquic soil runoff; the concentration of various forms of phosphorus in fluvo-aquic soil increased with increasing rainfall intensity and slope gradient.(3) TP and PP losses in fluvo-aquic soil in runoff increased with increasing rainfall intensity and slope, while TDP losses increased first and then decreased with increasing rainfall intensity under the condition of slope 8°, and kept an increasing trend under the condition of slope 15°.PP was the main form of phosphorus loss in the fluvo-aquic soil runoff.(4) There was an obvious linear relationship between the loss of TP and PP in the fluvo-aquic soil runoff and the rainfall intensity, slope and runoff quality(Q) under simulated rainfall conditions.The results provided a simple calculation method and scientific basis for predicting the loss of TP and PP per unit area in the runoff of the fluvo-aquic soil area under certain conditions.
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