Use of the nitrate electrode for determination of nitrates in soils

Abstract

A procedure for the rapid and accurate determination of water‐extractable soil nitrates is described. Use of this procedure resulted in quantitative recovery of nitrates added to soil. Reproducibility of results was high, with nitrate‐nitrogen in 40 soil samples determined on successive days differing by a maximum of 4 ppm with 33 determinations differing by 2 ppm or less. Comparison with a phenoldisulfonic acid method on 513 soil samples had a maximum difference of 7 ppm with a majority of determinations having a difference of 4 ppm or less.     

Phosphate interference in the Devarda's alloy reduction method for nitrate

Abstract

Phosphate interfered markedly with a Devarda's alloy distillation method for the determination of nitrate. Only 9% of added nitrate was recovered by this method when 200 mg P was present. This interference can be overcome by the addition of calcium ions, to precipitate the phosphate, and an extended distillation time.     

葛粉工业废水葛根素含量测定方法的比较

【目的】验证紫外分光光度法测定葛粉工业废水葛根素含量的可靠性,建立一种可信度高、操作性强、适于监测葛粉工业废水葛根素含量动态变化的测定方法。【方法】在不同浓度的葛根素标准溶液中加入已知浓度的牛血清蛋白（BSA）,检验蛋白质对紫外分光光度法测定葛根素含量的干扰;分别采用紫外分光光度法和高效液相色谱（HPLC）法测定葛粉工业废水葛根素含量,确认紫外分光光度法测定废水中葛根素含量的可靠性。【结果】在2～20μg/mL浓度范围内,葛根素浓度与其在250nm处的吸光值呈良好的线性关系,线性方程为：y=0.0648x-0.0049,相关系数（R2）为0.9995。紫外分光光度法测定葛根素的最低检出限为0.0480μg/mL,具有精密度较高、准确度良好,且不受BSA干扰的特点。紫外分光光度法与HPLC法测定结果的相对误差为5.0%,在可接受范围内。【结论】利用紫外分光光度法替代HPLC法进行葛粉工业废水葛根素含量测定具有可信、简便的特点,适用于工厂中葛粉工业废水葛根素分离纯化生产过程的实时监测。     

天然气管网系统风险评估

为了更加客观地定量评估天然气管网系统风险,以北京市天然气管网系统为例,深入分析了引起管网事故的原因,对事故进行统计分析,建立了天然气管网系统风险评估指标体系.在对事故可能性的评估中,结合天然气管网本身参数设计和周围环境特点,通过对管道与管网的可靠性分析,实现对事故可能性的修正;在对后果严重程度的评估中,引入管网事故风险的承受能力和控制能力,对天然气管网脆弱性进行分析,实现了对后果严重程度的修正.对事故可能性和后果严重程度分级后,通过风险矩阵可以计算出天然气管网系统的风险等级.     

西三线0.8设计系数段环焊缝容许缺陷尺寸

为减少管材用量、降低工程造价,西三线27#阀室一烟墩压气站间300 km管道采用了0.8设计系数,相比以往的0.72设计系数,管道的安全设计系数由1.39降为1.25,管道环向应力水平相比提高11.5％.针对0.8设计系数的上述特点,在介绍目前国内外管道环焊缝焊接缺陷确定方法的基础上,重点对相关方法和检测标准进行对比和差异分析.基于西三线0.8设计系数段的实际工况,采用API 1104-2005标准中推荐的工程临界评估（ECA）方法,计算分析了管道环焊缝的容许缺陷尺寸,认为西二线无损检测规范规定的容许缺陷尺寸可以适用于西三线0.8设计系数段.     

长呼原油管道保温与不保温方案比选

基于长庆油田一呼和浩特石化原油管道工程项目沿线地形地貌和管输原油物性,依据相关标准,讨论了保温方案和不保温方案在设计参数、安全停输时间、经济投资等方面的差异.结果表明:相同管径下不保温方案的管道传热系数约为保温方案的2～3倍,加热油耗约为保温方案的2倍,安全停输时间比保温方案缩短15.5 h,同时总体投资比保温方案高出1 742×104元,费用现值比保温方案高出3.6×108元.因此该管道工程项目推荐采用保温方案,以减少热站数量和运行人员设置,降低运行管理费用.(表4,图4,参2)     

基于挖潜系数的农村居民点土地集约利用潜力研究

挖掘农村居民点内部潜力是解决当前土地供需矛盾的重要途径之一.以河北省霸州市为研究区域,根据用地性质和人口分布状况,对全国第二次土地调查数据进行修正;以人均建设用地面积为评价指标,将全市农村居民点土地利用按照集约程度分为集约利用、一般集约利用和粗放利用三个等级;根据现状人均建设用地面积计算农村居民点理论整理潜力;选择自然、经济、社会3类因素5项评价指标计算挖潜系数;分别以人均建设用地120 m2、150 m2为界线计算可实现的农村居民点集约利用潜力值.     

戊唑醇、丙森锌混配剂对大樱桃黑斑病菌的毒力及其增效作用

采用菌丝生长速率法测定了戊唑醇、丙森锌对大樱桃黑斑病菌的毒力,并在此基础上用Horsfall的毒力试验设计和共毒系数法进行了混配剂的最佳配比筛选。结果表明：戊唑醇对大樱桃黑斑病菌抑制活性显著优于丙森锌,戊唑醇与丙森锌按EC50值剂量1∶9比例混配后共毒系数为1 612.09,具有显著增效作用。     

Effects of diatomite on soil physical properties

Organic and inorganic soil amendments are commonly added to soil for improving its physical and chemical characteristics which promote plant growth. Although many inorganic amendments are extensively used for this purpose, diatomite (DE) is not commonly used. This study was conducted to determine effects of diatomite applications (10, 20, and 30% v/v) on physical characteristics of soils with different textures (Sandy Loam, Loam, and Clay), under laboratory conditions. The results indicated that diatomite application protects large aggregate (> 6.4 mm) formation in clay-textured soils, however it reduced the mean weight diameter in sand-textured soil. 30% diatomite reduced mean weight diameter in sand-textured soils from 1.74 to 1.49 mm. Diatomite applications significantly increased aggregate stability of all the experimental soils in all aggregate size fractions. In overall, aggregate stability increased from 28.04% to 45.70% with the application rate of 30%. Diatomite application also significantly increased soil moisture content at field capacity in SL textured soil. 30% diatomite increased field capacity in sand-textured soil in the percent of 43.78 as compared with control. Therefore it is suggested that diatomite may be considered as a soil amendment agent for improving soil physical characteristics. However, its effectiveness in enhancing soil properties depends on initial soil factors and texture. Moreover, since its protective effect against large aggregate (> 6.4 mm) formation and reducing effect on soil penetration resistance in clay textured soils, diatomite might be an alternative soil amendment agent in soil tillage practices and seedling.     

2010-2011年度四省小麦区试品种遗传多样性和抗条锈性分析

为探讨2010-2011年度四川、甘肃、河北、河南四省参加区试的小麦品种的遗传多样性和抗条锈性,采用亲缘系数(coefficient of parentage,COP)对92个供试小麦品种进行遗传多样性分析,利用各品种组合间的COP值进行聚类分析;对供试小麦品种接种条锈混合菌系CYR33、CYR32、CYR31、CYR30、CYR29、CYR17、Su-1和V26进行抗条锈性鉴定.结果表明,供试的92个品种的4 186对组合中,约14.76％的品种间存在遗传相似性,所有供试品种的COP值在0.0000～0.7500之间,亲缘系数总和为95.793 9,平均值仅为0.022 9,通过对COP值的聚类分析,将供试材料分为8大类,聚为一类的大多数品种抗病性相似,说明其骨干亲本的抗病性被很好地遗传了;甘肃、四川品种对小麦条锈病的抗性较强,河南、河北品种相对较弱.表明甘肃、四川品种的遗传多样性相对较高,河南品种的遗传多样性相对较低.