黄土高原滑坡及其利用的探讨

黄土高原滑坡是十分严重的自然灾害,往往能给人民生命财产造成极大损失,又是黄土高原严重水土流失的主要产沙方式。如何变害为利,利用滑坡天然聚湫以及利用滑坡机理,发展人工滑坡,促进水保、治理沟谷,发展农业生产是黄土高原研究的新课题。     

Dynamic preservation of the coastline in the Netherlands

In 1990, the Government and Parliament of the Netherlands decided on a new national policy for coastal defence. To ensure the enduring safety of the low-lying polders as well as the sustainable preservation of the coastal dunes, it was decided to maintain the coastline in its 1990 position. The main method for coastline preservation in the Netherlands is beach nourishment. Since 1991, approximately 7 million m³ of sand is added to the Dutch beaches annually. From an evaluation study of sand nourishment projects it is concluded that nourishment is an effective and efficient method to preserve the coastline. The evaluation study also proves that nourishment projects should be ‘tailor-made’, taking the local morphological and hydraulic conditions into account. The first results of an experimental shoreface nourishment are discussed. The choice for nourishment as the principal method to combat erosion is well in line with the intention to restore the natural dynamics of the dune-coast in the Netherlands. The key probably is a less strict policy with regard to the maintenance of the foredunes. Plans for the development of typical coastal features such as slufters^*, wash-overs, blow-outs and mobile dunes are currently under discussion. A slufter is a breakthrough in the first dune-ridge whereby the sea invades former dune slacks or beach plains situated behind the duneridge. In this way a tidal marsh is formed within the dune zone.     

Applicability of Montreal Process Criterion 4 — soil and water conservation — to rangeland sustainability

SUMMARY

Criterion 4 of the Montreal Process addresses the conservation of soil and water resources as a way to assess the sustainability of a nation's forests. For the most part, the indicators under this criterion are relevant to rangelands. The area and percent of rangeland with significant soil erosion apply equally well to both biomes. Percent of streams with flow rates and timing outside its range of historical variation is also equally important, although a measure of proper functioning and condition may provide a better measure of the indicator. The area and percent of rangeland with diminished soil productive capability because of a loss of reduced organic matter or changed physical characteristics can be useful indicators locally and regionally.     

水泥离子侵蚀规律及其对Cs+的吸附

水泥是放射性废物处置库建设的必需材料;作为第一道屏障在阻滞放射性核素迁移上发挥着重要作用. 在处置库长期的服役过程中,水泥难免会被地下水中的SO₄²⁻与Cl⁻侵蚀,破坏其微观结构,改变其对放射性核素的滞留性能,从而危害处置库安全. 为考察SO₄²⁻与Cl⁻侵蚀对水泥的影响,研究了水泥离子侵蚀规律及其对Cs⁺的吸附性能. 通过XRF、FT-IR、SEM、BET等多种表征手段探究了离子侵蚀前后水泥物化性质的变化,结果表明SO₄²⁻、Cl⁻分别与水化产物反应生成钙矾石、Friedel盐等膨胀产物,离子侵蚀后,水泥的比表面积及孔隙率增加;随着离子侵蚀程度的持续增加,侵蚀产物在孔隙内堆积降低了孔体积及比表面积. 吸附实验结果表明,水泥净浆对Cs⁺的吸附量为14.83 μg·g¹,5%的SO₄²⁻、Cl⁻侵蚀将水泥对Cs⁺的吸附量分别提升至63.17 μg·g⁻¹、82.29 μg·g⁻¹. 吸附动力学及吸附等温模型拟合结果表明,离子侵蚀前后水泥吸附Cs⁺均为单层化学吸附,离子侵蚀并未改变水泥吸附Cs⁺的机理.     

全国土壤侵蚀量估算及其在吸附态氮磷流失量匡算中的应用

应用土壤流失方程(USLE),根据我国土壤水力侵蚀分类分级标准,建立了大尺度区域土壤侵蚀量的估算模型;基于GIS技术平台,利用土壤普查数据,构建了全国表层土壤氮磷含量数据库,完成了2000年全国境内水土流失影响下吸附态氮磷的流失量估算.经数据合理性分析验证后得出以下结论:(1)全国因水土流失引发的吸附态氮素和磷素的流失总量分别达到104.22×104t和34.65×104t;(2)长江、珠江和黄河三大流域的吸附态氮、磷流失量之和分别占全国总量的83%和89%,单     

滇西北高原生态恢复过程中土壤侵蚀特征及其影响因子

滇西北高原由于地处生态脆弱的石灰岩区,水土流失严重,探讨该区生态恢复过程中土壤侵蚀的变化规律,为开展人工植被建设提供依据。以时空互代的方法,通过径流小区,对坡面的产沙产流特性及其影响因素进行研究。结果表明:天然次生林和人工混交林均有较好的调节径流和减少泥沙的作用,产沙量分别比坡耕地减少了51.46%、43.18%,产流量也相应降低了39.39%、24.24%。在最大次降雨条件下,荒草丛、坡耕地、次生林和混交林单次降雨的产沙量分别占试验期产沙总量的55.38%、55.58%、58.35%和58.05%,产流量相应占产流总量的64.72%、64.63%、73.85%和55.39%。而且,产流产沙量与土壤有机质质量分数均存在明显正相关,与乔、灌层植物多样性及均匀度指数等呈显著负相关性(P<0.05)。因此,乔灌草结合的群落结构配置模式是滇西北地区水土保持林营造的目标和方向。     

从长江洪水看土壤环境保护的重要性

从１９９８ 年长江流域发生的特大洪水说起,分析从汉代到清末２０００ 年间及近４０ 年来长江流域水旱灾害的变化趋势,认为造成长江洪水灾害的原因主要是气候异常,但也与生态环境遭到破坏有关,其中土壤侵蚀、水土流失是最重要的因素。探讨了防治长江水患的对策;基于对土壤的吸水和贮水功能主要靠地被层和土壤有机质层,而水土流失是从植被破坏、地被层消失开始的,以及对古今治水、治土正反两个方面的认识,提出了治水的同时应治土的观点及５ 条有效的途径。     

可溶性有机质对芘在泥炭和高岭土上吸附和解吸的影响

为掌握可溶性有机质(DOM)对憎水性有机污染物吸附和解吸行为的影响,本研究选取四环多环芳烃——芘作为目标污染物,通过批平衡实验研究了不同分子量组分DOM对芘在泥炭和高岭土上吸附和解吸的影响.结果表明,吸附和解吸数据均可以用Freundlich模型很好地拟合(R2＞0.93).DOM的添加抑制了泥炭对芘的吸附,并且分子量...     

Application of a ‘bio-engineering’ technique to protect ghoramara island (Bay of Bengal) from severe erosion

Ghoramara Island is located ca. 150 km south of Kolkata, Bay of Bengal, India, in the Sundarban Delta complex. This sparsely populated island is suffering from severe coastal erosion and areal reduction for the last three decades, which results in the loss of major areas on the northwest coast. Both numerous households and a significant area of agricultural land and coastal stretches for fish drying have been lost. This has rendered thousands of people homeless as ‘environmental refugess’. In the present paper an attempt is made to study the erosion and accretion process through time series analysis using a GIS technique. Also, a study of remedial measures to protect the island using a ‘bio-engineering’ technique is reported in this paper. It has been shown that, in the absence of protection measures, the eastern shore will merge with the Indian mainland during the next 25 years, while the western part will be completely washed off.