| 人工模拟降雨条件下黄土坡面水-沙-氮磷流失特征 |
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| 引用本文： | 乔闪闪,吴磊,彭梦玲.人工模拟降雨条件下黄土坡面水-沙-氮磷流失特征[J].环境科学研究,2018,31(10):1728-1735. |
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| 作者姓名： | 乔闪闪 吴磊 彭梦玲 |
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| 作者单位： | 1.西北农林科技大学, 旱区农业水土工程教育部重点实验室, 陕西 杨凌 712100 |
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| 基金项目： | 国家自然科学基金项目（No.51679206）;陕西省青年科技新星项目（No.2017KJXX-91）;"仲英青年学者"项目（No.Z111021720） |
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| 摘 要： | 黄土坡沟水沙及养分流失严重,不仅造成土地生产力下降,对水环境也存在潜在威胁.为探索黄绵土坡面水沙氮磷流失相关关系,采用人工模拟降雨试验,研究不同雨强（45、60、75、90、105、120 mm/h）、不同坡度（5°、10°、15°、20°、25°）下黄土裸地水沙氮磷的流失规律.结果表明:①产流量可用坡度的二次多项式表达,确定系数（R2）达0.83以上,产沙量随雨强变化规律不明显,但随坡度增加呈显著增加趋势.②各雨强下,25°与5°坡面的ρ（TN）比值范围为1.63~5.42,波动较大,而ρ（TP）随坡度的增加基本呈增加趋势,但整体数值低于ρ（TN）.③各雨强下ρ（吸附态氮）随降雨历时的延长呈剧烈起伏变化;大雨强（105和120 mm/h）下ρ（吸附态磷）随降雨历时的延长逐渐减少至稳定值,其他雨强下ρ（吸附态磷）随降雨历时的延长呈现波动增加.各雨强与坡度下,ρ（吸附态氮）与ρ（吸附态磷）分别占ρ（TN）、ρ（TP）的60.66%、96.62%,是黄土裸坡氮磷的主要流失形式.④随水沙流失的氮磷中,TN占主要部分,其流失量是TP流失量的1.43~22.46倍,径流量增加时TN流失量显著增加,而产沙量增加时TP流失量显著增加.研究显示,雨强和坡度变化对水沙氮磷流失影响各异,吸附态氮磷是黄土养分流失的主要途径,可为黄土坡耕地水土流失治理提供科学依据.
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| 关 键 词： | 人工模拟降雨 雨强 坡度 氮磷流失 裸坡地 黄绵土 |
| 收稿时间： | 2018/1/17 0:00:00 |
| 修稿时间： | 2018/5/10 0:00:00 |
Simulation of Runoff, Sediment, Nitrogen and Phosphorus Loss on Bare Loess Sloping Land Using Simulated Rainfall |
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| QIAO Shanshan,WU Lei and PENG Mengling.Simulation of Runoff, Sediment, Nitrogen and Phosphorus Loss on Bare Loess Sloping Land Using Simulated Rainfall[J].Research of Environmental Sciences,2018,31(10):1728-1735. |
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| Authors: | QIAO Shanshan WU Lei and PENG Mengling |
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| Affiliation: | 1.Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A & F University, Yangling 712100, China2.State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Water and Soil Conservation, Northwest A & F University, Yangling 712100, China3.College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, China |
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| Abstract: | Serious soil loss on the Loess Plateau not only causes a decline in land productivity but also poses a potential threat to aquatic environments. In order to study the characteristics of runoff, sediment, nitrogen and phosphorus loss on bare loess slope, 30 simulated rainfalls were conducted to study the rules of soil and nutrient loss under different rainfall intensities (45, 60, 75, 90, 105, 120 mm/h) and different slopes (5°, 10°, 15°, 20°, 25°). Runoff and sediment were measured using the volume method and the dry weighing method, respectively. total nitrogen (TN) concentration was measured using the UV spectrophotometry method combined with alkaline potassium persulfate digestion. total phosphorus (TP) concentration was measured using the UV spectrophotometric method with potassium persulfate oxidation digestion. Results indicated that:(1) Runoff mainly presented a quadratic polynomial relationship with slope gradient under different rainfall intensities, the determination coefficients (R2) were all above 0.83. Under the same rainfall intensities, the sediment yield significantly decreased in the initial 10 minutes of runoff yield, after 10 minutes the sediment yield increased with the prolongation of rainfall duration. However, the relationship between sediment yield and rainfall intensity was not significant. (2) The ratio interval of TN loss concentration at the slopes of 25° and 5° was 1.63-5.42 under different rainfall intensities. TP concentration primarily showed an increasing trend with increased slope gradient, but its value was smaller than TN, the maximum value occurred in the rainfall intensity of 75 mm/h with a slope of 20°. (3) Under all rainfall intensities, adsorbed TN concentration fluctuated dramatically with the prolongation of rainfall duration. Adsorbed TP concentration first decreased sharply and then tended to stabilize under rainfall intensities of 105 and 120 mm/h. Adsorbed TP concentrations at other rainfall intensities increased in volatility with the prolongation of rainfall duration. Adsorbed TN and TP concentrations accounted for 25.66%-81.98% and 91.76%-98.66% of TN and TP and the corresponding average values were 60.66% and 96.62% respectively. (4) TN was the main component of nutrient loss and its loss load was 1.43-22.46 times than that of TP. TN increased obviously with increased runoff yield and TP increased with increased sediment yield. In conclusion, the effects of variable rainfall intensities and slopes on losses of runoff, sediment, nitrogen and phosphorus were different; adsorbed nitrogen and phosphorus were the main causes of loess nutrient loss which can provide a scientific basis for the governance of soil loss on the loess slope farmland. |
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| Keywords: | artificial simulated rainfall rainfall intensity slope gradient nutrient and phosphorus loss bare sloping land loess soil |
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