5篇
| The deserts, which already occupy approximately a fourth of the Earth's land surface, have in recent decades been increasing at an alarming pace. | 沙漠已经占据了地球表面积约四分之一，而且最近几十年正以惊人的速度扩张。 |
| The expansion of desertlike conditions into areas where they did not previously exist is called desertification. It has been estimated that an additional one-fourth of the Earth's land surface is threatened by this process. | 沙漠化是指类似沙漠的环境漫延到原本并非沙漠的区域。据估计，地球表面另外四分之一的地方正面临沙漠化威胁。 |
| Desertification is accomplished primarily through the loss of stabilizing natural vegetation and the subsequent accelerated erosion of the soil by wind and water. | 沙漠化主要通过以下过程实现：首先自然植被不断减少，随后风力和雨水加速了土壤的腐蚀。 |
| In some cases the loose soil is blown completely away, leaving a stony surface. | 有的时候松散的土壤全部被风刮走，留下石质化的表层； |
| In other cases, the finer particles may be removed, while the sand-sized particles are accumulated to form mobile hills or ridges of sand. | 其它情况下细小的沙粒可能会被吹走，而正常沙粒大小的砂子不断堆积，从而形成移动的沙丘或者沙脊。 |
| Even in the areas that retain a soil cover, the reduction of vegetation typically results in the loss of the soil's ability to absorb substantial quantities of water. | 即便是在保留了土壤表层的区域，植被减少也已成为土壤大量吸取地下水的能力下降的典型因素。 |
| The impact of raindrops on the loose soil tends to transfer fine clay particles into the tiniest soil spaces, sealing them and producing a surface that allows very little water penetration. | 雨水对松散土壤的冲击会把细小的粘土颗粒冲到土壤空隙中，封闭了土壤并降低土地表层水的渗透率。 |
| Water absorption is greatly reduced; consequently runoff is increased, resulting in accelerated erosion rates. | 地表对水的吸收急剧减少，大量水资源流失，因此土壤的腐蚀率也随即增加。 |
| The gradual drying of the soil caused by its diminished ability to absorb water results in the further loss of vegetation, so that a cycle of progressive surface deterioration is established. | 地表吸收水分的能力进一步弱化使得土壤越发干燥，导致植被的进一步流失，于是便形成了土壤沙漠化的恶性循环。 |
| In some regions, the increase in desert areas is occurring largely as the result of a trend toward drier climatic conditions. | 在一些地方，沙漠面积的扩大很大程度上归因于干燥的气候条件。 |