ISWC OpenIR  > 水保所知识产出(1956---)
丹江中游小流域氮素分布与流失机理
徐 国
Subtype博士
Thesis Advisor李占斌
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword土壤全氮 土地利用 丹江流域 土壤颗粒分形维数 非点源污染
Abstract

丹江水源区的水环境质量对南水北调中线工程的供水安全具有重要意义。本文在
丹江鹦鹉沟小流域进行水质监测和土壤采集分析的基础上,运用地统计学方法、分形
理论、土壤侵蚀预报模型和水文学方法等对小流域土壤氮素空间变异特征和径流-泥
沙-养分流失规律进行研究,以期为水源区保护和清洁小流域建设提供依据。本研究
取得的主要结论如下:
(1)流域土壤全氮含量随土壤深度的增加而降低,不同土地利用下 0-40 cm 每
平方米土壤全氮含量表现为林地>农地>草地。不同土层间土壤全氮含量存在极显著
差异(P< 0.01),0-10 cm (A1)、10-20 cm (A2)和 20-40 cm (A3)土壤全氮含量平均值
分别为 0.85、0.47 和 0.30 g/kg;3 个土层下,土壤全氮的最优模型均为线性模型,具
有中等空间相关性;A1 和 A2 层不同土地利用下土壤全氮含量存在显著差异(P<0.05),
不同土层下土壤全氮在不同坡度均存在显著差异(P<0.05),农地不同土层下土壤全氮
含量与海拔、坡度和坡向均呈极显著相关性(P<0.01);在 0-40 cm 土壤深度下,研究
区土壤全氮储量为 562.37 t,林地、农地和草地每平方米土壤全氮含量分别为 0.343、
0.299 和 0.289 kg/m 2 。
(2)不同土壤深度下土壤含氮量与土壤颗粒特征有极显著关系,不同土地利用
土壤粉粘粒含量随土壤深度的增加而增大。土壤全氮在 0-20 cm 土层与中粗砂粒呈极
显著正相关(P<0.01),土壤颗粒分形维数和土壤全氮在 20-60 cm 土层均与土壤粉粘粒
含量呈极显著正相关(P<0.01);不同土层下土壤粉粘粒含量平均值均表现为农地>林地
>草地,不同植被类型间土壤颗粒分形维数亦存在显著差异(P<0.05),但 10-20 cm
土层的土壤颗粒分形维数更能代表不同土地利用的差异;土壤颗粒分形维数与坡度呈
显著负相关(P<0.05),与坡向和海拔无显著相关性;不同土地利用下 0-10 cm 土层
每平方米土壤粉粘粒含量表现为农地>林地>草地,分别为 74.71 kg/m 2 ,71.54 kg/m 2
和 70.23 kg/m 2 。
(3)阐明了氮素随径流的迁移转化过程及污染负荷特征,流域径流中总氮的流失模数为 0.89 t×km -2 ×a -1 。径流水质中主要是总氮含量超标,且硝氮含量均大于氨氮含
量,农村生产生活污染物排放对水质有很大影响;氨氮、硝氮和总氮的年均径流流失
模数均表现为农地>草地>林地,农地、草地和林地的总氮年均径流流失模数分别为
0.36、0.22 和 0.09 t×km -2 ×a -1 ;流域出口非点源污染物氨氮、硝氮和总氮的平均浓度分
别为 0.17、4.71 和 7.55mg/L,点源污染物氨氮、硝氮和总氮的平均浓度分别为 0.20、
2.12 和 4.08mg/L。
(4)阐明了土壤氮素流失与水土流失的关系,流域泥沙中全氮的年均流失模数
为 0.27 t×km -2 ×a -1 。鹦鹉沟流域的年均土壤侵蚀模数为 3140 t/km 2 ,侵蚀强度为中度,
坡耕地是流域需要重点治理的区域;林地、草地和农地的年均土壤侵蚀模数分别为
509.7、1511.8 和 4606.5 t/km 2 ,林草地年侵蚀量较小,农地土壤侵蚀量占流域总侵蚀
量的 95.3%;坡度每增加 5°,不同土地利用的土壤侵蚀模数增加量比坡长每增加 5 m
的增加量要大 1~2 倍;研究区表土流失造成的全氮、氨氮和硝氮损失量分别为
3799.9、44.8 和 16.9 kg,其中农地的氮素损失量最为严重。
(5)模拟了不同水土保持治理情景对流域氮素流失的阻控作用,丹江流域大于
5°的坡耕地全部退耕还林情景下,其径流总氮年均浓度将降低 0.203 mg/L。水土保持
治理下,当坡面全部是林地和草地时,丹江流域的平均侵蚀模数分别为 750.1 t×km -2 ×a -1
和 1875.2 t×km -2 ×a -1 ,土壤侵蚀强度可达到轻度土壤侵蚀;坡面林(草)措施比例与侵
蚀模数之间的关系接近于线性函数,而梯田比例与侵蚀模数之间的关系更接近于指数
函数;林草措施减水减沙效益最好,使降水大部分以壤中流形式流出,从而降低了氮
素浓度;丹江流域大于 5°的坡耕地在林地和草地极限治理状态下,其泥沙量分别减
少 205.3 和 196.6 万吨,泥沙全氮含量分别减少 732.8 和 701.9 吨,径流总氮流失量分
别减少 346.9 和 169.2 吨。
关键词 :土壤全氮;土地利用;丹江流域;土壤颗粒分形维数;非点源污染

Other Abstract

The quality of water environment in the source area of the Dan River is of great
significance to the water supply security of the middle route of the South to North Water
Diversion Project. Based on the water quality monitoring and soil sampling in
Yingwugou Small Watershed of Dan River, geostatistical method, fractal theory, soil
erosion prediction model and hydrology method are adopted to research the spatial
variability of soil nitrogen and losing rules of runoff - sediment - nutrient in the small
watershed. It is expected to provide the basis for the protection of water source area and
the construction of clean small watershed. The main conclusions of this study are as
follows:
(1)The total nitrogen content in the soil profile decreased as the soil depth
increased. The total nitrogen contents per square meter in 0-40 cm soil layer were
forestland > cropland > grassland. There were significant differences among the three
soil layers (P < 0.01). The mean total nitrogen contents in 0-10 (A1), 10-20 (A2) and
20-40 cm (A3) were 0.85, 0.47 and 0.30 g/kg, respectively. The best fitted models in the
three soil layers were all linear models indicating moderate spatial dependence. The
spatial variations of total nitrogen content under different land use types in A1 and A2
were significant (P < 0.05). The impact of slope on soil total nitrogen content in the three
soil depths was significant (P < 0.05). There were significant correlations between the
total nitrogen content and elevation, slope and aspect in different soil layers of cropland
(P<0.01). The soil total nitrogen storage in the study area in 0-40 cm was 562.37 t. The
total nitrogen contents per square meter in 0-40 cm soil layer under forestland, cropland
and grassland were 0.343, 0.299 and 0.289 kg/m 2 , respectively.
(2)There was a significant relationship between soil total nitrogen content and soil
particle distribution in the different soil depths. The soil silt and clay content in the soil  profile increased as the soil depth increased. Soil total nitrogen content had a significant
positive correlation with coarse sand at a depth of 0–20 cm (P < 0.01). The fractal
dimension and soil total nitrogen content both indicated positive correlations with silt
and clay content at a depth of 20–60 cm (P < 0.01). The mean soil silt and clay contents
in the different soil horizons were all cropland > forestland > grassland. The fractal
dimensions of soil particle-size distribution among different plant communities also
indicated significant differences (P < 0.05). Howerver, the fractal dimension of soil
particle-size distribution in 10-20 cm soil layer could better represent the differences of
the different land use types. There was a significant correlation between fractal
dimension of soil particle-size distribution and slope (P < 0.05), but no correlation with
elevation and aspect. The soil silt and clay contents per square meter in 0-10 cm soil
layer under cropland, forestland and grassland were 74.71, 71.54 and 70.23 kg/m 2 ,
respectively.
(3)The nitrogen migration process in runoff and the characteristics of pollution
load were clarified. The average total nitrogen runoff loss modulus in Yingwugou
watershed was 0.89 t×km -2 ×a -1 . The total nitrogen content was the major exceeded
pollutant in runoff and nitrate nitrogen content was always greater than the ammonia
content. Rural production and living pollutant emissions had a great impact on water
quality. The average annual nitrogen loss moduluses of ammonia nitrogen, nitrate
nitrogen and total nitrogen were all farmland> grassland> forestland. The average annual
total nitrogen loss moduluses of farmland, grassland and forestland were 0.36, 0.22 and
0.09 t×km -2 ×a -1 , respectively. The average non-point source pollutant concentration of
ammonia nitrogen, nitrate nitrogen and total nitrogen in watershed export were 0.17, 4.71
and 7.55mg / L, respectively. The average point source pollutant concentration of
ammonia nitrogen, nitrate nitrogen and total nitrogen in watershed export were 0.20, 2.12
and 4.08 mg / L, respectively.
(4)The relationship between soil nitrogen loss and soil erosion and water loss was
clarified. The annual loss moduluses of total nitrogen with sediment were 0.27 t×km -2 ×a -1 .
The annual soil erosion modulus in Yingwugou watershed was 3140 t/km 2 . It was in the
category of moderate degree erosion. The high soil erosion area was mainly distributed in
sloping cropland with big slopes which was the key management area. The annual soil  erosion moduluses of forestland, grassland and cropland were 509.7、1511.8 and 4606.5
t/km 2 , respectively. The annual soil erosion amount of forestland and grassland was
relatively small and the annual soil erosion amount of cropland accounted for 95.3% of
the total soil erosion amount in the study area. For each additional 5° slope, the increased
soil erosion modulus of different land uses was of 1 to 2 times greater than that of each
additional 5 m for slope length. The annual loss amount of total nitrogen, ammonia
nitrogen and nitrate nitrogen in topsoil was 3799.9, 44.8 and 16.9 kg, respectively. The
nitrogen loss of cropland was serious.
(5)Different scenarios of soil and water conservation to prevent and control
nitrogen loss in watershed were simulated. When the sloping cropland more than 5° was
in the ultimate governance status of forestland in Dan River watershed, the average
annual concentration of total nitrogen in Dan River would reduce 0.203mg/L. Soil
erosion intensity was in the category of light degree erosion when the slope was all
woodland or grassland. The average erosion modulus was 750.1t×km -2 ×a -1  and
1875.2t×km -2 ×a -1 , respectively. The relationship between the proportions of slope forest
(grass) measure and soil erosion modulus is close to a linear function. The relationship
between the proportions of terrace measure and soil erosion modulus is closer to an
exponential function. The effect of forest and grass measures on reducing water and
sediment was better than terracing, most of the precipitation outflows in the form of
subsurface flow, thereby reduces the nitrogen concentration. When the sloping cropland
more than 5° was in the ultimate governance status of forestland and grassland in Dan
River watershed, the sediment loads would reduce 205.3 and 196.6 million tons
respectively. The amount of total nitrogen content in sediment would decrease 732.8 and
701.9 tons, respectively. The amount of total nitrogen content in runoff would reduce
346.9 and 169.2 tons, respectively.
Key Words: soil total nitrogen; land use; Dan River watershed; fractal dimension of soil
particle-size distribution; non-point source pollution

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8963
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
徐 国. 丹江中游小流域氮素分布与流失机理[D]. 北京. 中国科学院研究生院,2013.
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