Changes in soil quality in the critical area of desertification surrounding the Ejina Oasis,Northern China

The critical area around an oasis where desertification occurs determines the ecological security and stability of the oasis. In this study, the soil quality in the critical area of desertification surrounding the Ejina Oasis was evaluated by using a soil quality index (SQI). The soil surface moisture content was related to vegetation cover; it remained high to a distance of 600 m from the oasis, decreased at distances of 600 to 1,700 m, and then gradually increased to a distance of 1,900 m. The sand content and soil bulk density gradually decreased to a distance of 300 m from the oasis; however, the silt and clay contents, soil pH, soil organic matter (SOM), and total and available nutrients increased away from the oasis. From 300 to 1,900 m, the sand content and soil bulk density increased; however, values of other soil properties decreased. Thus, a distance of 300 m from the edge of the oasis represents an obvious demarcation point for soil properties. SOM and the clay content were the key factors that determined soil quality. SQI increased from 0.284 at the edge of the oasis to 0.793 at 300 m, decreased to 0.262 at 1,400 m, and then decreased further to 0.142 at 1,900 m. SQI was lowest at distances of 1,400–1,900 m. The area beyond 300 m from the oasis was most vulnerable to desertification, and is thus the area where desertification control measures should be strengthened.     

库车坳陷中生代海侵事件对有机质的影响

对库车河剖面三叠侏罗系重要生烃组段进行了有机质生物标志化合物及单体烃同位素研究,研究结果表明,海侵层位与非海侵层位在生物组成和生标特征等方面明显不同,海侵带来了不同的生物体,使有机质类型发生了改变。在生物标志化合物参数方面表现为Ｐｒ／Ｐｈ小于１,甾烷含量丰富,甾烷中Ｃ_２７化合物丰度与Ｃ_２９相当,三环萜烷有Ｃ_２１＜Ｃ_２３＞Ｃ_２４的分布特点,单体烃同位素表现出富集轻碳同位素的特点。中生代海侵事件对塔北隆起区及库车拗陷油气资源具有重要的意义。     

冬春亚洲大气环流与华北中部夏季降水的相关分析

利用1957~2002年的NCEP/NCAR 500 hPa再分析资料以及同期华北地区夏季降水资料,分析了华北中部夏季降水与前期环流的关系。结果表明:夏季华北中部降水的多少与冬季东亚槽强弱、春季巴尔喀什湖到贝加尔湖的蒙古高原地区高度场呈显著相关。20世纪80年代中期以前冬季东亚槽偏强、春季蒙古高原地区高度值偏低;80年代中期之后冬季东亚槽开始转弱、春季蒙古高原地区高度值偏高。这与华北夏季降水的演变趋势相对应。说明冬季东亚槽的减弱以及春季蒙古高原地区高度值偏高是近年来华北夏季降水减少的原因之一。冬季东亚槽强对应夏季西太平洋副高在日本海地区高度呈偏强趋势,有利华北中部夏季降水偏多;春季蒙古高原地区高度值偏高有利于华北夏季出现西高东低形势,华北中部夏季降水易偏少。     

在简化的简单生物圈模式中结合新的雪盖模型

本文提出了将一个新的雪盖模型（ＳＡＳＴ）与简化的简单生物圈模型（ＳＳＩ）相结合后的ＳＳＩＢ模型的改进形式，并利用俄罗斯及法国的观测数据对改进后的模型进行了检验。文中描述了改进后的ＳＳＩＢ模型中空气－植被－雪盖－土壤复杂系统之间有关能量和质量交换的过程，并给出为求解这一组非线性方程组所发展的有效计算方法。利用俄罗斯及法国的观测结果对这一新的改进模型功能进行了验证。结果表明改进后ＳＳＩＢ的数值模拟结果能较好地重现现场观测数据，说明这个新的改进形式可以推广用于气候研究。     

The separation mechanism and application of a tapered diameter separation bed

Research on recycling waste printed circuit boards is at the forefront of preventing environmental pollution and finding ways to recycle resources. A wet process for reclaiming metals from printed circuit boards applying a tapered diameter separation bed is described, and the separation mechanism of the device is proposed. The motion of a particle in the tapered diameter fluid flow field and particle separation within this field were studied. As the material passes through the fluid field, along with the water, differences in particle density, granularity, and shape cause particles to follow at different trajectories. A tapered diameter separation bed was used to process 1?C0.074?mm-sized crushed material from discarded printed circuit boards. The separation efficiency of 91.77?% and the recovery rate of 95.79?% for recovered metal were achieved with a discharge water flow rate of 4.5m³/h, a material feed rate of 300?g/min, and an obliquity of 30°. For ?0.074?mm printed circuit boards, the metal recovery is 93.42?% and the separation efficiency is 77.63?% when the water discharge is 2?m³/h, the obliquity is 35o, and the material feed rate is 450?g/min. The superfine products in a size range of ?0.074?mm can be recovered effectively under suitable operating condition using the tapered diameter separation bed. It indicates that the lower separation limit of the tapered diameter separation bed can be close to zero. The technique will prevent environmental pollution from waste printed circuit boards and allow efficient recovery.     

兰州市大气飘尘的有机地球化学研究--Ⅱ.酮和醇脂类化合物的组成和分布特征

首次对兰州市大气飘尘中酮和醇脂类化合物进行了分析和研究。结果表明,兰州市大气飘尘中正烷基２酮和直链烷基醇的浓度分别为２０～２７０ｎｇｍ－３和５２０～９１０ｎｇｍ－３,并表现为３月份高于７月和８月份,这与兰州市特殊的地形和气候条件有关;其分布特征指示了它们来自人为活动、微生物和现代高等植物,而且它们在这３种来源中所占的比例分别为２．８％～１９．７％、１５．４％～３４．６％和５０．３％～８１．８％。甾醇化合物的浓度很低,它们由现代生物所提供。丰富的Ｃ１８类异戊二烯酮化合物的存在,反映了大气飘尘中有机质在大气氧化过程中已经被改造。     

含氟初始风化水化学组成的模型研究

在我国“三北”地区，浅层地下水中高氟苏打水分布广泛。本文利用和简化了Ｈｅｌｇｅｓｏｎ风化模型，以吉林省乾安地区为例，对含氟初始风化水化学组成作了研究和计算：探讨了二氧化碳滴定作用对风化过程的影响，从而定量确定了高氟水的成因模型。     

论德尔尼黄铁矿型铜钴矿床的成矿规律

区域深断裂带（即昆南深断裂）控制着华力西期超基性岩和印支期花岗岩的分布。由于花岗岩的成矿作用，并在构造及岩性圈闭条件下，形成了德尔尼黄铁矿型铜钴矿床。上石炭统的下部片岩组含矿性较好，是区内矿源层之一，但矿质主要来自花岗岩岩浆热液。该矿区属浅成热液矿床