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.     

Effects of Freezing on Quality of Cold-smoked Salmon Based on the Measurements of Physiochemical Characteristics

ABSTRACT: How the quality of cold-smoked Atlantic salmon ( Salmo salar ) is affected by freezing the raw fish as whole fish, as gutted fish, and as fillets before smoking, and by freezing the finished product after smoking was studied. Freezing before smoking resulted in increased product yield and water content, but softer texture and increased K-value. Freezing reduced the content of astaxanthin but increased the lightness and the color intensity of the flesh. Gaping increased when the fish was frozen as fillets before smoking. Freezing only after smoking led to fewer changes in quality than freezing before smoking, whereas refreezing the finished products had little additional effect on quality.     

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天然气脱除Ｈ２Ｓ和ＣＯ２是天然气净化领域经常遇到的问题。Ｈ２Ｓ与醇胺的反应属瞬间质子反应，ＣＯ２与醇胺的反应则复杂得多，醇胺溶液对Ｈ２Ｓ的选择性分离主要依靠ＣＯ２与醇胺的反应速度差异来实现。文章介绍了伯胺，仲胺，叔胺及空间位阻胺溶液反应的机理和动力学。     

HPD-2型非临氢降凝催化剂工艺实验

利用HPD-2型非临氢降凝催化剂进行了中试实验。结果表明：HPD-2型非临氢降凝催化剂相对其他的同类催化剂产品液体收率较高，最高可达95％以上；在反应温度为380℃时，凝点降幅在50℃左右，降凝效果较好；产品性质稳定，具有很好的应用前景。     

2,6-二甲基萘生产技术进展

概述了国外2，6-二甲基萘生产技术现状，详细介绍了ExxonMobil公司2，6-二甲基萘的工艺路线和日本神户制钢所的提纯方法，指出了实现我国2，6-二甲基萘工业化生产应注意的问题。     

Isolation of the acidic and basic lectins from winged bean seed (Psophocarpus tetragonolobus (L.) DC)

The acidic and basic lectins of the winged bean were isolated from seed extracts by affinity chromatography on lactose-Sepharose 6B and melibiose Bio-Gel P150, respectively. The lectins isolated from six varieties of Psophocarpus tetragonolobus, collected from different regions of south-east Asia, showed no significant differences in their properties; their subunit M_r and amino acid compositions were the same as those of the acidic and basic lectins isolated by non-affinity methods. On isoelectric focusing the affinity purified acidic lectins showed two major protein components (isolectins) while the affinity purified basic lectins had four protein components. The acidic lectins showed a preference for β-D-galactosides and they agglutinated trypsinised human type A, B and O erythrocytes but not trypsinised rabbit erythrocytes. The basic lectins showed a preference for α-D-galactosides and they agglutinated trypsinised rabbit and human type A and B erythrocytes but not trypsinised human type O erythrocytes.     

横管初冷器液体喷洒系统的改进

介绍了横管初冷器液体喷洒系统存在的问题，改进方法及效果。     

糠醛装置腐蚀机理分析及防护

重质糠醛精制装置设备腐蚀严重与糠醛氧化变质有关,通过分析装置设备腐蚀机理和糠醛氧化、变质的原因,提出了用N_2汽提回收和原料脱水等改进措施。     

1000m~3/h空分设备板翅式换热器带水冻堵故障处理

介绍 10 0 0m3 /h空分设备板翅式换热器循环水加杀菌剂产生泡沫 ,引起空冷塔雾沫夹带而严重带水冻堵的故障现象、原因及处理措施 ,并指出运行中的不足。     

重油催化裂化干气氢提纯技术的开发

石家庄炼油厂和西南化工研究设计院合作开发的中国石化系统第一套利用变压吸附技术进行RFCC干气氢提纯工业试生产装置一年的平稳运行说明：提纯后产品氢纯度达99．9％，回收率大于85％；操作简便灵活；装置负荷弹性裕度大；经济效益显著。实践证明它是一项富有吸引力的新工艺，为重油催化裂化装置的挖潜增效展示了美好的前景。