ISWC OpenIR  > 水保所知识产出(1956---)
137Cs 和210Pbex复合示踪研究东北黑土区 坡耕地土壤侵蚀速率
王 禹
Subtype硕士
2010-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword黑土坡耕地 侵蚀速率 137cs 210pbex Usle 模型
Abstract

中国的东北黑土区土壤肥沃,是我国著名的“粮仓”。然而由于长期以来的过度垦
殖导致土壤侵蚀日益严重,坡耕地已成为水土流失的主要源地,使得黑土区耕地的土
壤质量严重退化,对我国的粮食安全构成了严重威胁。因此,研究东北黑土区典型坡
耕地的土壤侵蚀规律,对控制坡耕地的水土流失以及深化土壤侵蚀规律的认识都具有
十分重要的意义。
本研究在黑龙江省克山县,采集了一块坡长500m,坡度3°,坡向南,开垦历史
近100年的直型坡耕地和一块坡长350m,坡向北,开垦历史54年的凸型坡耕地的土
壤样品,采用野外采样与室内分析相结合的研究方法,利用137Cs和210Pbex复合示踪
技术,结合USLE通用流失方程和小波理论的分析方法,通过SPSS等分析手段,研
究了黑土坡耕地50-100 年来的侵蚀速率,结合对土壤理化性质及养分含量的分析,
探讨了黑土区坡耕地土壤侵蚀规律及土壤退化过程,得到了以下主要结论:
(1) 通过采集开垦近100 年的黑土直型坡耕地的土壤样品,利用137Cs示踪技术,结
合小波分析方法,研究了长坡长直型坡耕地50多年来土壤侵蚀强度的空间变化规律,
结果显示4个断面顺坡方向上的坡面侵蚀强度均存在着坡长为142 m的强弱交替变化
的波动周期,这反映了长坡长直型坡土壤在长期的降雨侵蚀过程中,泥沙沿坡面输移
的强弱交替变化。通过对4个断面的侵蚀速率的数学拟合发现,用正弦函数的和拟合
的结果最好,R2 均在0.96 以上,进一步说明了直型坡面侵蚀随坡长变化的波动性规
律。通过对凸型坡面顺坡侵蚀强度的小波分析,发现整个坡面不存在侵蚀强度强弱交
替变化的波动周期,证明小波分析的方法不适用于其它坡形的坡面侵蚀强度的分析。
(2) 通过对坡耕地坡顶平坦处21个土壤样品中137Cs 含量的测定,发现所有点137Cs
含量均小于当地137Cs背景值,经过分析认为风蚀是造成坡顶处137Cs含量普遍小于背
景值的主要原因,证明该区存在一定的风力侵蚀;利用137Cs 示踪技术能得到坡面总
侵蚀速率和USLE水蚀预报模型能分析坡面水蚀速率的特点,研究了两块坡耕地的水
蚀与风蚀速率,研究结果表明:直型坡耕地和凸型坡耕地的年均侵蚀速率分别为3054  t km2 a-1和3548 t km2 a-1;由于坡向的不同,两块坡面的风蚀速率分别为631 t km2 a-1
和1155 t km2 a-1,即研究区每年约有0.5~1mm的表层土壤被风吹蚀掉,风蚀占总侵
蚀的20.7%和32.6%;而水蚀仍为研究区主要的侵蚀方式,两块坡面的水蚀速率分别
占总侵蚀的79.3%和67.4%。因此,东北黑土区坡耕地水土流失的防治要充分考虑水
和风的不同影响,综合治理。
(3) 通过对比两块坡耕地土壤剖面有机质含量的深度分布发现,开垦100 年的直型
坡耕地表层土壤中有机质含量仅为4.3%左右,而开垦54年的凸型坡耕地的表层有机
质含量则达5.6%左右,显然开垦时间更长的直型坡耕地土壤质量退化更加严重;对
两个坡面侵蚀速率与各养分含量逐步回归统计结果显示,两个坡面上侵蚀速率Y均可
用养分含量的函数表示,其中直型坡为Y=189082.80X-14503.31(R=0.506),X为TP含
量,凸型坡为Y= 2282.516X-16762.25(R=0.646),X为SOM含量,这反应了土壤养分
流失与土壤侵蚀的密切关系;利用养分流失预测模型,对研究区三种养分的流失量进
行了估算,结果表明,直型坡耕地土壤有机质、全氮、全磷的平均流失量分别为241.87、
10.94、6.14 t km2 a-1,凸型坡由于其坡度较大,坡中部侵蚀剧烈,养分流失量较大,
其有机质、全氮、全磷的平均流失量分别是367.76、14.22、9.14 t km2 a-1。
(4) 利用137Cs 和210Pbex复合示踪的方法,对两块坡耕地的侵蚀速率进行了对
比研究,结果表明:在开垦了近100 年的直型坡上,尽管137Cs 示踪的是50 多
年的年均土壤侵蚀速率,210Pbex示踪的是近100 来的年均土壤侵蚀速率,但由
于该地区近100 年内降水量变化差异不大,因此理论上两种示踪方法所得坡耕
地侵蚀速率也应该是比较接近的,实际示踪结果证实137Cs 得到的侵蚀速率为
2812 t km2 a-1,而210Pbex为2576 t km2 a-1,从而证明了两种示踪方法在该研究区
计算侵蚀速率的结果都是准确的;而在开垦历史54 年的凸型坡耕地上,由于
该坡耕地未开垦前是原始次生林地,侵蚀速率很小,所以,利用210Pbex示踪得
到的侵蚀速率结果应是开垦前和开垦后的平均侵蚀速率,研究结果表明该坡面
近100 年的侵蚀速率为1890 t km2 a-1,而其开垦后54 年的年均侵蚀速率(137Cs
示踪所得)为3771 t km2 a-1;利用加权平均的方法,计算得到了凸型坡耕地未
开垦之前46 年的平均侵蚀速率为319 t km2 a-1,而开垦后50 多年的侵蚀速率几
乎达到开垦前的12 倍,再次证明人类过度垦殖等不合理的开发利用,加速了东北黑
土区土壤侵蚀的发展。因此,必须尽快的科学的治理黑土区的水土流失,保护这片肥
沃的土地。

Other Abstract

The fertile black soil in Northeast China is famous for the "granary." However, the
long excessive reclamation had led to increasingly serious soil erosion, and cultivated
slope had become a major sediment sources. So the serious degradation of quality of
cultivated black soil had posed a serious threat to the food security in China. Therefore, an
understanding of erosion rules is important for designing conservation programs and
deepening the erosion mechanism.
In this paper, a straight cultivated for nearly 100 years slope with 500 meters long, 3°
slope gradient, southward and a convex cultivated for more than 50 years slope with 350
meters long,northward were selected in Keshan county in Hei Long Jiang Province to
study the 50-100 years erosion rates of cultivated black soil, and analysis the soil physical
and chemical properties as well as nutrient content, in order to discuss the erosion rules and
the degradation process of the cultivated black soil. Major methods contain field sampling
and laboratory analysis, 137Cs and 210Pbex composite tracer technology, USLE model,
wavelet analysis, SPSS, and so on. The main results as follow:
(1) The spatial distribution of soil erosion intensity on the long and straight cultivated
slope was studied using 137Cs measurement and wavelet analysis. The results showed that
there was a fluctuant period of soil erosion intensity with 142m along 4 transects
downslope, which suggested that the downslope intensity of soil transporting alternately
changed between weak and strong due to the impact of long-term erosive rainfall.
Moreover, the best fitting result (R2>0.96) of the soil erosion rates along the four transects
was the sum of sine function. It was further convinced the correctness of the fluctuant of
the erosion intensity on the study slope; the same study of the convex slope showed the
downslope erosion intensity was not periodic fluctuated, so the wavelet analysis was not  applicable for the erosion study of other shapes of slope.
(2) The 137Cs contents in soil samples collected on the slope flat were analyzed and the
results showed that 137Cs inventory of all samples were less than the 137Cs reference
inventory, and the primary reason was there existed some wind erosion. Because 137Cs
measurement could get the total erosion rates and USLE model could measure the water
erosion rate, the contributions of water and wind erosion rates were partitioned and the
results showed that the annual mean erosion rate on the straight slope and convex slope
was 3054 t km2 a-1 and 3548 t km2 a-1 respectively. Meanwhile, the wind erosion rate was
631 t km2 a-1 and 1155 t km2 a-1, 20.7% and 32.6% respectively because of the different
slope aspect, which means that nearly 0.5~1mm soil was blew off in the study area every
year. The water erosion rate proportion of the two slope was 79.3% and 67.4%, thus water
erosion was still the dominant erosion style in the study area. Accordingly, the prevention
needs to be considered adequately about the different influence by water and wind and
comprehensively designed.
(3) By comparing the profile distributing of the SOM content of the two slope, it was
found that the SOM content in straight slope cultivated for 100 years and convex slope
cultivated for 54 years were 4.3% and 5.6% respectively, soil degradation was more
serious in straight longer reclaimed slope obviously. By stepwise regression of the erosion
rate and nutrient content on two slopes, it was found that erosion rate Y can be represented
by function of nutrient content, for the straight slope, that was:
Y=189082.80X-14503.31(R=0.506), X was TP content. And, for the convex slope, Y=
2282.516X-16762.25(R=0.646), X was SOM content. These functions may show the
intensive relations between soil nutrient loss and soil erosion. By estimating the nutrient
loss of study area, the results indicated that the soil loss amount in straight slope were
241.87、10.94、6.14 t km2 a-1 of SOM, TN and TP respectively, but the nutrient loss on
convex slope were more 367.76、14.22、9.14 t km2 a-1 respective of SOM, TN and TP.
(4) The soil erosion rate of the two cultivated slope was studied using 137Cs and
210Pbex tracer measurement, the results showed that on the straight cutivated for nearly
100 years slope, due to the little difference of rainfall during the last 100 years in
this region, the erosion rate derived from 137Cs and 210Pbex should be similar, and the
results showed the erosion rate were 2812 t km2 a-1 and 2575 t km2 a-1 respectively by  137Cs and 210Pbex, though 137Cs traced soil erosion rate of more than 50 years while
210Pbex nearly 100 years, so it can be concluded that the two tracer measurement
were both correct in this area. However, on the convex cultivated for 54 years slope,
cause the little erosion before reclaimed, the erosion rate in the last 100 years by
210Pbex was 1890 t km2 a-1, which was significantly less than after reclaimed: 3771 t km2
a-1 derived from 137Cs measurement. Using the weighed average method, the erosion rate
of the convex slope before reclaimed can be got, it was 319 t km2 a-1 and nearly 12 times
less than that of after reclaimed. It could be concluded, because of the excessive
reclamation and other unreasonable utilizations by human, the soil erosion had been
accelerated seriously. Therefore, the fertile land in black soil region needs to be
protected scientifically and quickly.

MOST Discipline Catalogue土壤学
Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8854
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
王 禹. 137Cs 和210Pbex复合示踪研究东北黑土区 坡耕地土壤侵蚀速率[D]. 北京. 中国科学院研究生院,2010.
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