基于137Cs示踪技术的土壤侵蚀研究进展

由于应用137Cs示踪技术能够提供土壤侵蚀与沉积信息，近年来137Cs示踪技术逐渐成为土壤侵蚀研究的重要方法．本文介绍了137Cs示踪法原理，回顾了其在土壤侵蚀中的研究应用，并对其优缺点进行评价．然后，总结了。137Cs示踪剂法土壤侵蚀模型，最后展望了其在土壤侵蚀研究中的前景．     

张家口坝上地区农田土壤风蚀的137Cs示踪研究

利用137Cs示踪法,计算了张家口坝上地区1963年以来的农田土壤风蚀模数.结果表明,该区域的农田普遍处于风蚀状态,平均风蚀模数为8362.34 t·km-2·a-1,平均风蚀厚度约为0.53 cm·a-1,达到极重度风蚀.农田风蚀模数存在明显的空间差异性和规律性,反映了风蚀环境和农田管理方式等因素的空间差异性.     

137Cs示踪研究小流域土壤侵蚀与沉积空间分布特征

通过在0.17km2面积的小流域198个点、525个样品表层土壤中137Cs含量的分析、研究,结果表明:不同地貌部位137Cs含量有明显分异,为137Cs法定量研究土壤侵蚀与沉积提供了科学依据;137Cs含量升高的部位多出现在沟缘线附近和沟口附近;小流域土壤侵蚀强度从梁峁顶向沟坡逐渐增大,这是黄土高原广大水土流失区自然状态的或初步治理的小流域侵蚀强度空间变化的基本特征.     

运用137Cs示踪技术重建近30年滦河源区土壤风蚀变化过程

在持续调查与观测滦河源区土壤风蚀特征的基础上,对采集于滦河源区风积土剖面中土层样品的pH、有机碳质量分数、土壤颗粒组成进行了化验分析,运用ADCOM100超低本底γ谱仪测定了土壤样品137Cs的比活度,建立了研究区连续风积土壤剖面的时间序列,综合分析了不同时段风积层土壤的性状,运用土壤风蚀相对强度指数ISWE重建了滦河源区近30年来土壤风蚀变化过程.结果表明:20世纪70年代至80年代早期、80年代末期至90年代中后期均为研究区土壤风蚀较弱的时期;80年代中期、90年代末期至2002年均为土壤风蚀强化时期.并结合已有研究成果讨论了土壤风蚀变化与气候变化的相关性及其对京津地区大气环境的影响.     

干旱半干旱地区农田风蚀危害及其对策研究

土壤风蚀是我国干旱半干旱地区土地退化的主要原因之一,严重制约着农业的可持续发展.笔者从土壤风蚀发生机理、影响因子的角度探讨了干旱半干旱地区农田风蚀危害及防治对策,提出了实施保护性耕作是实现干旱半干旱地区农业可持续发展的必然选择.     

137 Cs在土壤中淋溶迁移的模拟试验

~(137)Cs作为示踪元素广泛应用于土壤侵蚀及泥沙沉积研究中,其在土壤中的稳定性是决定其能否用于示踪土壤沉积与侵蚀的前提条件.但也有学者对应用~(137)Cs示踪技术的重要假设提出质疑,认为被土壤颗粒吸附的~(137)Cs易解吸成Cs+离子,随水流失或被植物吸收.本文利用双层土柱模拟淋溶装置研究了~(137)Cs和土壤粒径组成在不同雨量条件下的淋失和垂直迁移特征.结果表明,在600~3 000mm降雨量内,土壤中~(137)Cs平均质量活度为10.9Bq·kg-1,略小于试验前的11.5Bq·kg~(-1),与雨量并无显著相关性,土壤中的~(137)Cs有向下垂直迁移现象,但并不显著;土壤中~(137)Cs质量活度与土壤中的黏粒含量有很好的正相关性,决定系数R2达到0.73;有待于增加模拟雨量,作进一步研究.     

春、秋整地对吉林省西部农田风蚀、土壤含水量、土壤温度的影响研究

对比研究了春、秋整地对吉林省西部农田风蚀、土壤含水量、土壤温度的影响.结果表明:由于西部地区春季的大风天气和很少的降水量,春天整地导致土壤含水量减少、风蚀加剧;对比春整地,秋整地的苗床土壤可风蚀率和风蚀数量都较小,土壤含水量较高,土壤温度略低.因此,在该地区应以秋整地代替春整地;如果不能进行秋整地,春整地也要延迟到4月25日以后进行.     

土壤风蚀农业区实施保护性耕作技术的策略研究

在中国北方干旱、半干旱及半湿润地区,土壤风蚀是土地退化的主要原因之一,土壤风蚀已经严重影响了农业可持续发展。因此,在土壤风蚀农业区实施保护性耕作技术已势在必行。保护性耕作技术的实施受到自然、社会经济、灾害等诸多因素的影响,本文在广泛征求专家意见的基础上,根据层次分析法构建了土壤风蚀农业区农田防治土壤风蚀的保护性耕作技术层次决策模型。研究表明,人口压力、农民因素、政府因素与科技因素是制约土壤风蚀农业区实施保护性耕作技术的最主要的四大因素,它们的权重值依次递减。由此,针对存在问题采取相应策略,对于土壤风蚀农业区实施保护性耕作技术将是有益的借鉴。     

河北坝上地区不同土地利用类型的土壤风蚀研究

通过Cs示踪和土壤粒度分析, 着重探讨了河北坝上地区土地利用与土壤风蚀的关系, 揭示了不同土地利用类型的侵蚀强度为沙质丘陵草原 > 耕地 > 退耕还草地 > 人工林 > 石质丘陵草原, 提出了对研究区保持石质丘陵草原现状、保护原有人工林等植被恢复的建议。     

重庆岩溶槽谷区山坡土壤的漏失研究

岩溶地区区别于非岩溶地区水土流失的关键是岩溶地区土壤存在地下漏失.本文运用同位素137Cs和配比法研究土壤地下漏失机理,得出以下结论:岩溶槽谷区土壤存在地下漏失现象,但土壤漏失现象并不随处可见,地表土壤漏失难以通过裂隙垂直渗漏到达土石界面,这可从137Cs剖面分布深度以及溶洞壁上土壤137Cs含量几乎为0看出;在有落水洞发育的溶蚀洼地内,通过分析土壤剖面分层137Cs含量,证明土壤从落水洞流失明显;土石界面的土壤可以通过裂隙进入地下河,但量很少;研究区运用137Cs配比法得出地表流失和地下漏失比例分别为75%和25%.     

Characteristics of 137Cs deposition in steppe area

Soil wind erosion in the semiarid steppe area was studied using the 137Cs tracing technique. Comparisons of 137Cs deposition characteristics between different soil profiles indicated that slight aeolian activities occurred on sandy grasslands and semi-fixed dunes with erosion/deposition rates of less than 0.108 cm/a, whereas they were intense on semi-shifting dunes with erosion/deposition rates of higher than 1.35 cm/a.     

Characteristics of 137Cs deposition in steppe area

Soil wind erosion in the semiarid steppe area was studied using the ¹³⁷Cs tracing technique. Comparisons of ¹³⁷Cs deposition characteristics between different soil profiles indicated that slight aeolian activities occurred on sandy grasslands and semi-fixed dunes with erosion/deposition rates of less than 0.108 cm/a, whereas they were intense on semi-shifting dunes with erosion/deposition rates of higher than 1.35 cm/a.     

Extracting change information of land-use and soil-erosion based on RS & GIS technology

Rapid land-use change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Land-use change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine land-use transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in land-use and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of land-use and soil erosion change.     

Extracting change information of land-use and soil-erosion based on RS & GIS technology

Rapid land-use change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Land-use change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine land-use transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in land-use and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of land-use and soil erosion change.     

^210Pbex depth distribution in soil and calibration models for assessment of soil erosion rates from ^210Pbex measurements

Throughout the past decade, the potential for using nuclear weapon-produced 137Cs ( half-life 30.2 a) fallout to quantify soil erosion rates on both cultivated and uncul- tivated lands for medium-term timescales (≈ 40 a) has been successfully demonstrated in a wide range of envi- ronments in different regions of the world[1—6]. Because in difficulties of distinguishing Chernobyl-derived compo- nent from total 137Cs input in many parts of Europe, and in measuring low activity samples of…     

广西岩溶区的水土流失特点及其防治

广西岩溶地区水土流失遥感数据和典型地区监测资料显示,广西岩溶地区水土流失有3个显著的特点:土壤侵蚀模数低,以水土漏失为主要过程,坡耕地是重要水土流失区。水土流失的突出危害是导致严重的岩溶内涝灾害和大面积耕地丧失。21世纪以来,国家和广西区政府对于广西岩溶地区水土流失防治工作高度重视,组织实施了一大批水土保持工程,治理水土流失面积14 000km~2,遏制了石漠化,降低了土壤侵蚀模数,形成了高效生态产业,创建了弄拉、龙何等生态与经济协调发展的水土保持模式。但广西岩溶地区水土漏失和内涝灾害防治力度不够,建议进一步加大力度实施广西岩溶地区水土漏失、内涝防治以及耕地资源丧失的水土保持工程。     

Using 137Cs tracing technique to estimate wind erosion rates in the typical steppe region,northern Mongolian Plateau

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using ^137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km^-2.a^-1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm. a^-1, and wind erosion rates up to 6723.06 t· km^-2. a^-1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not induce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.     

我国水土流失发生的原因、危害和防治途径

中国是世界上水土流失最严重的国家之一，水土流失已成为我国的头号环境问题．它不仅造成土地资源的破坏，导致农业生产环境恶化，生态平衡失调，水灾旱灾频繁，而且妨碍社会经济的发展和人民生活水平的提高．从自然条件和人为因素等方面出发，探讨了我国水土流失产生的原因；分析了水土流失对耕地资源、旱涝灾害、水资源利用、经济发展等方面的影响；介绍了水土保持的一些有效途径和措施。