试论荒漠生态监测的特点和监测指标的确定

从监测目的、监测对象、监测指标和监测数据的获取四个方面,论述了进行荒漠生态环境监测工作的特点.从干旱荒漠区自然环境的基本特征和主要生态环境问题及生态环境管理工作的需要出发,提出了在我国开展荒漠生态环境监测工作的监测指标,以供商榷.     

Effect of agricultural extension on cotton farmer's efficiency in arid and semi-arid areas of Burkina Faso

This study shows that farmers in arid and semi-arid land can improve their efficiency if they have access to agricultural extension services. An exhaustive survey was used to obtain data from 423 cotton producers in the arid zones and 144 of wetlands in Burkina Faso. The method of the directional distance function modeling a multi-output technology was used. The results show that cotton farmers in the arid zones are not technically more inefficient than those in wetlands. On average, arid zone producers have a technical inefficiency of 0.056 while that of wetland producers is around 0.052. The agricultural extension, defined as receiving visits and advice from technical agents, is important for producers because it helps farmers choose soil and water conservation techniques and fertilizers adapted to the Agro-climatic conditions of their respective zones. Agriculture extension also helps farmers of the arid zones to reduce their technical inefficiency by advising them to cultivate small agricultural plots. On average, in these zones, the size of an agricultural plot is around 1.03 ha compared to those of wetlands which is about 1.6 ha.     

Evaluation of oasis ecosystem risk by reliability theory in an arid area： A case study in the Shiyang River Basin, China

Ecosystem risk is a new concept in understanding environmental problems. It is important to study and develop quantitative methods for regional ecosystem risk analysis. In this study, some new indicators and methods for measuring oasis ecosystem risk were established using reliability theory. These indicators are linked to water resource, which is the key restricting factor in arid area oasis ecosystems. They have clear meanings and can also be compared in different arid area oases. A case study in the Liangzhou oasis of the Shiyang River Basin in China shows how to calculate these ecosystem risk indicators. The results of the case study are as follows： the reliability indicator, risk indicator, stability indicator, and integrated loss indicator of the Liangzhou oasis are 0.686, 0.314, 0.743, and 0.301, respectively. This means that the reliability degree of the oasis＇s ecosystem safety is 68.6%; the degree of risk that it is unsafe is 31.4%; the stability degree is 74.3%; and 30.1% of the oasis＇s area is supported by over-exploiting underground water and damaging the lower reaches of the ecosystem. This result can be used as a guide in controlling and managing ecosystem risk in the research area.     

Heavy Metal Distribution in Valley Sediments in Wadi Al-Karak Catchment Area, South Jordan

Valley sediments samples collected from the major and minor valleys of Al-Karak catchment area (southern Jordan) were leached with hot dilute HCl and analysed for their heavy metals content. The results of leachable metal concentrations indicated the absence of anomalous values for metal occurrences. However, appreciable contamination of the sediments with Cu, Zn, Pb, Cd and Cr was observed. Using an index of pollution the extent of contamination was better delineated. The geographical distribution of the samples showed higher Cu, Zn, Pb, Cd and Cr concentrations mainly around heavily inhabited areas indicating an anthropogenic source of contamination. Lithological influence indicated from the anomalies of Fe and Mn was found to be very low.     

Competition of the active roots of Cassia siamea Lam. and Zea mays L.(cv.Katumani Composite B) in an alley cropping trial in semi arid Kenya

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PART I: METHODOLOGY AND PROBLEMS IN AN URBANIZED ARID ENVIRONMENT1

The methodology of operations research is judged in relation to its utility to water resource management in an urbanized arid environment and to the study of worth of data for such management. Conditions for existence of a managerial problem are reviewed as is the multilevel structure of the decision process, including decisions on social goals for Western water use. Worth of data can only be judged in relation to a particular use to meet a social or managerial objective. The role of data uncertainty on the decision process is reviewed in the light of past water decisions and present and future problems.     

干旱区油田采油污水的处理及综合利用

我国西部干旱地区的塔里木盆地,有许多深居欧亚大陆腹地的大型油田,都地处水资源极其匮乏的地区,在油田的开发过程中的用水量和产水量都比较大,本文就采油过程中产生的采油污水的处理和综合利用问题作了探讨。     

基于临近台站气象数据的参考作物蒸散量估算方法

参考作物蒸散量（ET₀）是评估区域植被耗水进而指导水资源优化管理所需的主要参数之一,但我国大部分地区标准化气象台站稀疏、部分研究点的气象资料通常难以获取,给ET₀的计算带来了很大困难。以地处内陆旱区的内蒙古河套灌区为例,利用该区4个标准气象站1981-2006年的气象资料,讨论了研究点在没有历史气象数据且现有气象数据不完备的情况下,采用临近台站气象数据估算ET₀的可靠性。估算方法分别为估算未知气象数据的FAO56 Penman-Monteith方程（PM56）、基于临近台站气象数据校正的经验公式以及利用临近台站气象数据训练的人工神经网络模型。结果表明：（1）在完全没有气象数据的条件下,可采用临近站点的气象数据估算研究点的ET₀,平均绝对误差（MAE）为0.43~0.52 mm d^-1,均方根误差（RMSE）为0.56~0.63 mm d^-1;估算精度与台站间的距离有关,利用维度信息校正太阳辐射值可提高估算精度。（2）仅有最高和最低气温数据时,估算气象数据的PM56方程计算误差较大,且站点之间表现不稳定,人工神经网络模型的估算精度最高,MAE和RMSE分别为0.14~0.22 mm d^-1和0.17~0.29 mm d^-1;校正后的Hargreaves公式的估算效果次之,MAE和RMSE分别为0.23~0.26 mm d^-1和0.30~0.31 mm d^-1。（3）在已知温度和辐射数据时,利用临近台站气象数据训练的人工神经网络模型依然表现最好,MAE和RMSE分别为0.13~0.19 mm d^-1和0.17~0.25 mm d^-1,其他两种方法误差较大。在内陆干旱条件下,利用研究点的气温数据结合临近台站的历史气象信息可有效估算参考作物蒸散发。     

湿润区与干旱区典型湖泊湿地对比案例研究

选取东部湿润区与西北干早区典型湖泊湿地--洞庭湖湿地与艾比湖湿地,对其湿地资源特征、湿地生态服务功能及价值、湿地退化的表征和退化湿地生态恢复对策等方面进行了比较研究.通过研究发现,湿润区湖泊湿地资源禀赋优于干早区湖泊湿地,湿润区湖泊湿地与干旱区湖泊湿地均具有较强的生态服务功能和较高的价值,在湿地退化表征方面有共性也有差异,针对不同气候区域的退化湖泊湿地应采取不同的恢复对策.     

艾比湖干涸湖底化学组成及盐尘的风运堆积

选择亚洲中部典型干涸尾闾湖——艾比湖干涸湖底及其下风向约200km的范围为研究区,并把研究区分为干涸湖底风蚀区和盐尘扩散堆积区两个子区.通过对两子区连续多年野外实地观测、采样分析、定点试验等手段,研究了干涸湖底表层沉积物的化学组成、湖底风蚀动态和盐尘的扩散堆积规律.结果表明,艾比湖干涸湖底不同地表形态(结晶盐壳、盐-淤泥-黏土壳、风蚀堆积壳)间可溶性盐含量差异显著,盐类混合物中以硫酸盐和氯化物为主,二者基本占全部可溶性盐的90%,碳酸盐含量甚微.春秋两季是湖底风蚀和盐碱尘暴的高发期,盐分堆积动态与风期变化一致,春、秋两季大风期,降尘中盐通量最高;冬、夏两季降尘中盐通量较低.干涸湖底下风向盐尘的堆积强度以精河为中心分别向西北和东北方向递减,盐尘在风运过程中表现出显著的分异规律,硫酸盐比氯化物具有更远距离的迁移能力.