Influences of land use/cover on water quality in the upper and middle reaches of River Njoro, Kenya

Data from 10 sampling sites along the River Njoro are used to examine the contribution of nutrients from upstream land uses draining each of the sampling sites. The data also are used to assess whether both the proportion of land uses and the size of the subwatersheds account for the variability in water quality in the River Njoro watershed. Geographical Information System analysis was used to determine the spatial distribution of land‐cover types and subwatersheds contributing run‐off to the sampling sites in the River Njoro. Standard Digital Elevation Model‐based routines were used to establish the watershed area contributing run‐off to each sampling site. Water and sediment samples were collected for chemical analysis, and the nutrient levels were related to the upstream land‐use types and the size of the subwatersheds. The mid‐stream portion of the River Njoro (near Egerton University) accounts for the highest nutrient contributions. The percentage contribution is magnified by additions from industrial, human settlements and agricultural land uses around the University. There is a significant decrease in nutrient levels downstream, however, indicating natural purification as the river flows through an area of large‐scale farming with intense, well‐preserved riparian and in‐stream vegetation. Steep slopes of the land upstream of Egerton University enhance erosion and nutrient losses from those subwatersheds. Mixed small‐scale agricultural and bare lands contribute over 55% of the phosphorus load to the upper and mid‐reaches of the River Njoro. The size of the subwatershed accounts for about 53% of the variability in the soluble phosphorus in the river. The land‐use subwatershed proportions are important for characterizing and modelling water quality in the River Njoro watershed. Upland land uses are as important as near‐stream land uses. We suggest that conservation of intact riparian corridor along the river and its tributaries contributes significantly to natural purification processes and recovery of the ecological integrity of the River Njoro ecosystem.     

渭北旱塬区典型测井地下水埋深的灰色预测研究

地下水埋深变化是地下水系统动态变化最主要的表现形式之一,通过预测地下水埋深分析地下水系统未来演变趋势,对合理开发、持续利用地下水资源有着重要的现实意义。本文选取2000-2010年渭北旱塬区的两个典型监测井的地下水埋深数据,用灰色GM(1,1)理论建立预测模型,并对该监测井的地下水埋深进行短期预测。经检验,该模型具有较高的预测精度,说明采用灰色理论预测渭北旱塬区监测井地下水埋深的方法可行。     

Soil-to-Plant Transfer Factors of Stable Elements and Naturally Occurring Radionuclides (1) Upland Field Crops Collected in Japan

In long-term dose assessment models for radioactive waste disposal, an important exposure pathway to humans is via ingestion of contaminated foods. In order to obtain soil-to-plant transfer factors (TFs) of radionuclides under equilibrium conditions, naturally existing elements were measured as analogues of radionuclides. Crops grown in upland fields and associated soil samples were collected from 62 sampling sites throughout Japan. The total concentrations of 52 elements in the crops and 54 elements in the soil samples were measured. The TFs of 40 elements (Li, Na, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Pb, Th and U) were calculated on a dry weight basis.

Among all the TF data, K showed the highest TF with a geometric mean (GM) of 2.1, followed by P. The GMs of TFs for rare earth elements, Th and U were on the order of 10^?4. Most of the TF-GMs for green vegetables were higher than GMs of all crops for the elements. The obtained TFs of some elements for green vegetables and potatoes were compared with those in the technical report series-364 (TRS-364) compiled by IAEA in 1994. The TF-GMs were usually lower than the best estimates (expected values) listed in TRS-364; however, the GMs of TF for La and TF for Th observed for potatoes were slightly higher than the expected values.     

鄂尔多斯盆地渭北地区页岩纳米孔隙发育特征及其控制因素

为深入研究鄂尔多斯盆地东南缘渭北地区页岩储层中纳米孔隙的发育特征及其地质控制因素,对采自太原组、山西组和延长组三套泥页岩层的11块样品进行低温氮吸附实验、氩离子抛光-场发射扫描电镜、显微组分、镜质体反射率（R_o）、总有机碳（TOC）和X-射线衍射等系列分析测试。研究结果表明,研究区泥页岩处于低成熟向成熟转变阶段,有机碳含量差异较大,储层纳米级孔隙以中小孔（粒径2~50 nm）为主,约占总孔体积的63.5%,BET比表面积大多在10 m²/g以上,有利于页岩气的吸附;孔隙形态以“狭缝状”和“墨水瓶”形孔隙为主。研究区页岩的矿物类型具有明显的区域差异性：韩城区以粘土矿物为主,而铜川区以脆性矿物为主。粘土矿物含量与微孔（粒径<2 nm）、中小孔总含量呈显著的正相关性,而脆性矿物含量与大孔（粒径>50 nm）含量正相关,因此矿物类型差异是影响该区页岩纳米孔隙发育的主控因素。另外,R_o与TOC对纳米孔隙发育也有一定的影响：页岩R_o越高,大孔含量越高、中小孔含量越低;有机碳含量越高,微孔和中小孔含量越高。     

潍北凹陷致密气藏的成藏条件研究

潍北凹陷的区域地质和石油地质研究结果表明,潍北凹陷具备了形成致密气藏的构造、沉积、烃源岩、储层、盖层和圈闭条件,其中最有利的地区和层系为北部洼陷带埋深大于3000m的孔店组二段砂岩。通过对大地构造背景和石油地质条件相似的潍北凹陷和东濮凹陷对比研究发现,这两个凹陷的致密气藏形成条件存在着差异,这些差异主要表现在烃源岩、储层和盖层条件上,其中东濮凹陷致密气藏的形成条件明显优于潍北凹陷。     

渭北油田密井网水下分流河道储层构型研究及应用

渭北油田是鄂尔多斯盆地南部最近两年新发现的含油区块,本文以其密井网区延长组四段33油组为例,应用岩心、测井、地震及动态等资料,对辫状河三角洲水下分流河道砂体内部构型开展了系统研究。在分析单河道基本发育特征的基础上,剖面上井震结合识别单河道,平面上采用最大单层厚度与砂体层数交绘的方法,在密井网区长33油组识别出八个单河道发育期,单河道宽度一般在500~800m之间,宽厚比介于100~130之间;在平面复合河道中识别出单河道发育条数及分布范围;同时提出长33油组河道内部发育下切叠加式、不完全下切式、孤立式及薄层叠加式四种砂体叠置方式,明确了不同叠置模式在密井网区分布范围,为渭北油田密井网区注水开发和外围有利区带选取提供了地质依据。     

潍北拉分盆地形成演化及其对成油气条件的控制

潍北盆地是发育于郯庐断裂带内的中，新生代盆地，在大量地震资料解释与构造成图的基础上，通过构造解析和沉积分析等基础工作，证实潍北盆地是一个典型的走滑伸展盆地，盆地演化经历了走滑挤压阶段（白垩纪末），走滑伸展阶段（孔店组沉积期），坳陷与走滑挤压阶段（新近纪）等3个阶段。构造样式包括孔状结构，伸展构造以及走滑挤压产生的压扭性断鼻等，控盆断裂的右行走滑导致了孔店组一段，二段砂体向前迁移，潍北盆地发育良好的生储盖组合以及多类型圈闭，具有良好的坳探前景。图7参6     

潍北凹陷砂砾岩体的地球物理特征研究

潍北凹陷下第三系孔店组沉积中砂砾岩体较为发育，由于地震资料质量较差，砂砾岩体的剖面特征及平面分布一直得不到较好的落实。从原始地震记录人手，分别进行了时频分析技术及均方根振幅(能量)技术处理，获得了相应的时频分析剖面及均方根振幅剖面。由时频特征确定了地震旋回体的存在，旋回体的横向变化揭示了砂砾岩体沉积环境的规律。均方根剖面能量团的变化反映了砂砾岩体的空间分布范围，揭示了研究区砂砾岩体沉积期多水系、多物源、纵向上多期叠置的沉积特征。     

Recent research on fertilizer problems in Asian agriculture

Asian agriculture has made enormous gains in food production despite rapid population growth and a shortage of land. This paper reviews the role of fertilizer in agricultural production and the results of recent research on fertilizers and plant nutrition in the region. Fertilizer use has contributed greatly to the increase in food production which has occurred largely in the high potential areas. In these areas research has shown that losses reduce the efficiency of broadcast urea and that the use of high analysis fertilizers is inducing sulfur deficiency in some areas. In upland areas, research has highlighted a major problem of boron deficiency in Thailand. Research progress is being made in understanding the magnitude of nitrogen fixation inputs and the role of shrub legumes in upland systems.     

丹东地区主要水稻和旱稻品质性状研究

试验以丹东地区主栽的4个水稻品种与4个旱稻为试材,研究了水稻与旱稻品质特性。结果表明,旱稻的整精米率低于水稻,垩白率、蛋白质含量明显高于水稻,而综合食味值明显低于水稻。综合来看,在旱稻的4个品种中,丹旱稻1号品质较好;在水稻的4个品种中,丹137和中辽9052表现突出。