三峽庫(kù)區(qū)湖北段消落帶氮磷含量分布及流失特征研究
發(fā)布時(shí)間：2018-08-22 19:13
【摘要】：三峽大壩對(duì)于保障社會(huì)經(jīng)濟(jì)、水資源安全和生態(tài)屏障方面具有重要的影響。本文研究了三峽庫(kù)區(qū)湖北段消落帶氮磷含量分布及其流失特征,以期為三峽庫(kù)區(qū)消落帶防治水土流失,控制氮磷流失以及降低農(nóng)業(yè)面源污染提供一定的理論依據(jù)。本研究通過(guò)采集消落帶三種母質(zhì)(紫砂巖、花崗巖、石灰?guī)r)研究區(qū)域內(nèi)不同水位高程下的土、水樣品,并在水庫(kù)以最低水位運(yùn)行期間,選擇庫(kù)區(qū)內(nèi)廣泛分布的紫砂巖母質(zhì)區(qū)域進(jìn)行模擬徑流沖刷試驗(yàn),最后統(tǒng)計(jì)分析了三峽大壩蓄水前后、庫(kù)區(qū)不同研究區(qū)域的氮磷含量以及賦存形態(tài)變化規(guī)律。得到以下研究結(jié)果:(1)不同水位高程的土壤容重分布在1.35~1.53 g/cm3之間,均值為1.45±0.06 g/cm3;總孔隙度分布在41.87~49.81%之間,均值為46.79±2.57%。隨著海拔升高,消落帶表層土壤容重逐漸增大,總孔隙度逐漸降低,砂粒含量(28.62~51.74%)逐漸升高;隨著水位海拔升高,土壤表層土壤pH(6.87~6.57)逐漸降低,土壤有機(jī)質(zhì)和全氮逐漸升高,有機(jī)質(zhì)含量分布在8.54~22.85 g/kg之間,均值為14.22±9.68 g/kg,土壤全氮、全磷含量分別分布在0.15~0.76 g/kg和0.16~0.29 g/kg之間,均值分別為0.51±0.18 g/kg和0.22±0.04 g/kg。水樣中總氮總磷含量隨著水位下降而升高,而水質(zhì)逐漸變差,且不同母質(zhì)水樣中全氮含量存在極顯著差異,水樣中全磷含量則未表現(xiàn)出顯著性差異。(2)徑流中氮磷濃度隨時(shí)間的變化趨勢(shì)大致相同,均是在放水沖刷的初期達(dá)到最大濃度,然后呈現(xiàn)逐漸下降的趨勢(shì),并在一定時(shí)間之后慢慢趨于穩(wěn)定。初始總氮和總磷濃度分別分布在50.44~66.09 mg/L和68.56~85.06 mg/L之間;硝態(tài)氮和銨態(tài)氮初始濃度分別分布在16.91~20.57 mg/L和22.41~34.26 mg/L之間。指數(shù)函數(shù)能較好地?cái)M合徑流中氮磷濃度隨沖刷時(shí)間的變化過(guò)程。草帶對(duì)于氮磷的攔截效率為T(mén)NNO3--NNH4+-NTP,對(duì)徑流中各氮素指標(biāo)的攔截效率在85.7%以上,對(duì)總磷的攔截效率在61.3%以上;隨著寬度的增加,草帶對(duì)于氮磷的攔截效率增強(qiáng);隨著沖刷強(qiáng)度的增大,草帶對(duì)氮磷的攔截能力均有一定程度的降低;通過(guò)對(duì)比沖刷前后各層次土壤中氮磷含量發(fā)現(xiàn)沖刷結(jié)束后氮磷在土壤表層有較高程度的富集,表明草帶攔截的氮磷多被土壤所蓄存,各氮磷養(yǎng)分變化率分別于沖刷強(qiáng)度、土層深度呈現(xiàn)負(fù)相關(guān)關(guān)系,隨著沖刷強(qiáng)度和土層深度的增加,氮磷在土層中的富集程度隨之降低。(3)產(chǎn)流時(shí)間隨著沖刷強(qiáng)度的增大而顯著減小,產(chǎn)流速率隨沖刷強(qiáng)度的增大而顯著遞增。具體表現(xiàn):中、高沖刷強(qiáng)度(90、120 mm/h)相比低沖刷強(qiáng)度(60mm/h)的產(chǎn)流時(shí)間分別縮減了22.9%、40.8%(5 m草帶)和16.3%、69.5%(10m草帶),而中、高沖刷強(qiáng)度下的穩(wěn)定產(chǎn)流速率分別是低沖刷強(qiáng)度下的1.48、3.10倍(5 m草帶)和1.54、2.40倍(10 m草帶)。累積徑流量隨著產(chǎn)流歷時(shí)的延長(zhǎng)而逐漸增加,二者之間具有顯著的線性相關(guān)關(guān)系。徑流小區(qū)上、下坡位不同深度(5、10、20、30 cm)土壤含水量對(duì)徑流沖刷的響應(yīng)模式存在顯著的差異。上坡表層土壤含水量上升幅度最大,增幅約0.10 v/v;30 cm深度土壤含水量增加緩慢,增幅范圍為0.009~0.012 v/v。下坡10 cm深度土壤含水量增幅(0.121 v/v)最大。(4)在三峽水庫(kù)正式蓄水后,總氮總磷含量較蓄水前有不同程度的降低,庫(kù)區(qū)湖北段的氮磷含量普遍低于重慶段,全磷含量隨著淹水時(shí)間的延長(zhǎng)而降低。氮磷的不同賦存形態(tài)是影響其吸附和釋放的重要因素。Fe-Al/P(鐵-鋁磷)是TP中含量最低的一種賦存形態(tài),但也對(duì)沉積物向上覆水體釋放磷素造成影響。Ca-P(鈣磷)是TP中含量最高的一種賦存形態(tài),屬于穩(wěn)定態(tài)的磷,不易被生物吸收利用。OSF-N(有機(jī)硫化物結(jié)合態(tài)氮)和CF-N(碳酸鹽結(jié)合態(tài)氮)含量占據(jù)TF-N(可轉(zhuǎn)化態(tài)氮)的絕大部分,而IEF-N(離子交換態(tài)氮)和IMOF-N(鐵錳結(jié)合態(tài)氮)占比相對(duì)較小。
[Abstract]:The Three Gorges Dam has an important impact on social economy, water resources security and ecological barrier. This paper studies the distribution of nitrogen and phosphorus content and its loss characteristics in the ebb zone of Hubei section of the Three Gorges Reservoir area, in order to provide a theoretical basis for preventing and controlling soil erosion, controlling nitrogen and phosphorus loss and reducing agricultural non-point source pollution in the ebb zone of the Three Gorges Reservoir area. According to this study, soil and water samples of three parent materials (purple sandstone, granite and limestone) in the study area were collected and simulated runoff scouring test was carried out in the purple sandstone parent material area widely distributed in the reservoir area during the operation of the reservoir at the lowest water level. The results are as follows: (1) Soil bulk density at different water levels ranges from 1.35 g/cm 3 to 1.53 g/cm 3, with an average value of 1.45.06 g/cm 3; total porosity ranges from 41.87% to 49.81%, with an average value of 46.79.57%. With the increase of water level and elevation, soil pH (6.87-6.57) gradually decreased, soil organic matter and total nitrogen gradually increased, organic matter content ranged from 8.54 g/kg to 22.85 g/kg, with an average value of 14.22 + 9.68 g/kg, soil total nitrogen and total phosphorus content ranged from 0.15 to 0.15 g/kg, respectively. The total nitrogen and phosphorus content in the water sample increased with the water level decreasing, but the water quality gradually deteriorated, and the total nitrogen and phosphorus content in the different parent material water samples had extremely significant difference, but the total phosphorus content in the water sample did not show significant difference at any time. The initial concentrations of total nitrogen and phosphorus were 50.44-66.09 mg/L and 68.56-85.06 mg/L, respectively, and the initial concentrations of nitrate and ammonium nitrogen were 16.91-20.5, respectively. The interception efficiency of straw strip for nitrogen and phosphorus was TNNO3 - NNH4 + - NTP, the interception efficiency of each nitrogen index in runoff was above 85.7%, and the interception efficiency of total phosphorus was above 61.3% with the increase of straw width. The interception efficiency of nitrogen and phosphorus increased; with the increase of scouring intensity, the interception ability of grassland to nitrogen and phosphorus decreased to a certain extent; through the comparison of nitrogen and phosphorus content in different layers of soil before and after scouring, it was found that nitrogen and phosphorus had a higher degree of enrichment in the soil surface layer after scouring, indicating that nitrogen and phosphorus intercepted by grassland were mostly stored by the soil, and the nitrogen and phosphorus nutrients of each layer were stored (3) Runoff yield time decreases significantly with the increase of erosion intensity, and runoff yield rate increases significantly with the increase of erosion intensity. Specifically, high erosion intensity (90%). The runoff yield time at 120 m m/h was reduced by 22.9%, 40.8% (5 m straw belt) and 16.3%, 69.5% (10 m straw belt) respectively, compared with that at 60 m m/h. The steady runoff yield rate at high erosion intensity was 1.48, 3.10 times (5 m straw belt) and 1.54, 2.40 times (10 m straw belt) respectively, and the cumulative runoff increased gradually with the extension of runoff duration. There was a significant linear correlation between the two. In the runoff plot, the response patterns of soil water content to runoff scouring at different depths (5,10,20,30 cm) on the downhill slope were significantly different. (4) After the Three Gorges Reservoir was formally impounded, the content of total nitrogen and phosphorus decreased to some extent. The content of total nitrogen and phosphorus in Hubei section of the reservoir area was generally lower than that in Chongqing section. The content of total phosphorus decreased with the prolongation of flooding time. Fe-Al/P (Fe-Al/P) is the lowest form of phosphorus in TP, but it also affects the release of phosphorus from sediments to overlying water. Ca-P (calcium and phosphorus) is the highest form of phosphorus in TP. It is a stable form of phosphorus and is not easily absorbed by organisms. OSF-N (organic sulfide bound nitrogen) and CF-N (carbonate formation). The content of TF-N occupies the most part of TF-N, while the proportion of IEF-N and IMOF-N is relatively small.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S157
本文編號(hào)：2198045
[Abstract]:The Three Gorges Dam has an important impact on social economy, water resources security and ecological barrier. This paper studies the distribution of nitrogen and phosphorus content and its loss characteristics in the ebb zone of Hubei section of the Three Gorges Reservoir area, in order to provide a theoretical basis for preventing and controlling soil erosion, controlling nitrogen and phosphorus loss and reducing agricultural non-point source pollution in the ebb zone of the Three Gorges Reservoir area. According to this study, soil and water samples of three parent materials (purple sandstone, granite and limestone) in the study area were collected and simulated runoff scouring test was carried out in the purple sandstone parent material area widely distributed in the reservoir area during the operation of the reservoir at the lowest water level. The results are as follows: (1) Soil bulk density at different water levels ranges from 1.35 g/cm 3 to 1.53 g/cm 3, with an average value of 1.45.06 g/cm 3; total porosity ranges from 41.87% to 49.81%, with an average value of 46.79.57%. With the increase of water level and elevation, soil pH (6.87-6.57) gradually decreased, soil organic matter and total nitrogen gradually increased, organic matter content ranged from 8.54 g/kg to 22.85 g/kg, with an average value of 14.22 + 9.68 g/kg, soil total nitrogen and total phosphorus content ranged from 0.15 to 0.15 g/kg, respectively. The total nitrogen and phosphorus content in the water sample increased with the water level decreasing, but the water quality gradually deteriorated, and the total nitrogen and phosphorus content in the different parent material water samples had extremely significant difference, but the total phosphorus content in the water sample did not show significant difference at any time. The initial concentrations of total nitrogen and phosphorus were 50.44-66.09 mg/L and 68.56-85.06 mg/L, respectively, and the initial concentrations of nitrate and ammonium nitrogen were 16.91-20.5, respectively. The interception efficiency of straw strip for nitrogen and phosphorus was TNNO3 - NNH4 + - NTP, the interception efficiency of each nitrogen index in runoff was above 85.7%, and the interception efficiency of total phosphorus was above 61.3% with the increase of straw width. The interception efficiency of nitrogen and phosphorus increased; with the increase of scouring intensity, the interception ability of grassland to nitrogen and phosphorus decreased to a certain extent; through the comparison of nitrogen and phosphorus content in different layers of soil before and after scouring, it was found that nitrogen and phosphorus had a higher degree of enrichment in the soil surface layer after scouring, indicating that nitrogen and phosphorus intercepted by grassland were mostly stored by the soil, and the nitrogen and phosphorus nutrients of each layer were stored (3) Runoff yield time decreases significantly with the increase of erosion intensity, and runoff yield rate increases significantly with the increase of erosion intensity. Specifically, high erosion intensity (90%). The runoff yield time at 120 m m/h was reduced by 22.9%, 40.8% (5 m straw belt) and 16.3%, 69.5% (10 m straw belt) respectively, compared with that at 60 m m/h. The steady runoff yield rate at high erosion intensity was 1.48, 3.10 times (5 m straw belt) and 1.54, 2.40 times (10 m straw belt) respectively, and the cumulative runoff increased gradually with the extension of runoff duration. There was a significant linear correlation between the two. In the runoff plot, the response patterns of soil water content to runoff scouring at different depths (5,10,20,30 cm) on the downhill slope were significantly different. (4) After the Three Gorges Reservoir was formally impounded, the content of total nitrogen and phosphorus decreased to some extent. The content of total nitrogen and phosphorus in Hubei section of the reservoir area was generally lower than that in Chongqing section. The content of total phosphorus decreased with the prolongation of flooding time. Fe-Al/P (Fe-Al/P) is the lowest form of phosphorus in TP, but it also affects the release of phosphorus from sediments to overlying water. Ca-P (calcium and phosphorus) is the highest form of phosphorus in TP. It is a stable form of phosphorus and is not easily absorbed by organisms. OSF-N (organic sulfide bound nitrogen) and CF-N (carbonate formation). The content of TF-N occupies the most part of TF-N, while the proportion of IEF-N and IMOF-N is relatively small.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S157
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