Low flow water chemistry in forested and pasture catchments,Mawheraiti River,Westland     

M. P. Mosley  L. K. Rowe 《新西兰海洋与淡水研究杂志》2013,47(3):307-320

Water samples taken at 19 locations in the Mawheraiti River catchment at weekly intervals during 1979–80 were analysed for sodium, magnesium, potassium, calcium, phosphate, nitrate, and ammonium ion concentrations and for electrical conductivity. Seasonal discharge effects were apparent, and lithology and land management practice also influenced solute concentrations. Solute concentrations were generally very low; nitrate and soluble phosphate were rarely greater than 0.05 mg.L^‐1 and ammonium was rarely greater than 0.01 mg.L^‐1. The 4 major cations (Na, Mg, K, and Ca) usually summed to less than 6 mg.L^‐1 much of which was supplied by precipitation. Forest management (clearfelling and slash‐burning) caused significant increases in solute concentrations, but concentrations declined rapidly during succeeding months and approached pretreatment levels after 2–3 years. The higher concentrations associated with forest management in small experimental catchments were rapidly diluted downstream; together with the low natural solute concentrations this suggests that harmful downstream effects of management practices are unlikely under low flow conditions.  相似文献   

适用于条斑紫菜的双向电泳样品制备方法     

赵宇鹏  周伟  赵佩佩  才金玲  朱大玲  潘光华  刘洪艳  王广策 《海洋科学》2013,37(5):19-24

为了建立适于条斑紫菜(Porphyra yezoensis)蛋白质组学分析的的样品提取方法, 作者以条斑紫菜叶状体为材料, 比较了饱和硫酸铵沉淀法、三氯乙酸/丙酮沉淀法和酚提取方法3 种方法对条斑紫菜叶状体总蛋白的提取效果。结果表明, 针对条斑紫菜叶状体细胞中含有大量多糖, 多酚化合物, 色素等干扰物质的特点, 通过酚提取方法能有效去除这些干扰杂质, 得到清晰、稳定、干净的双向电泳图谱和相对较多的蛋白质点数, 为提高其他大型海藻的总可溶性蛋白提取效率提供了重要参考。  相似文献   

四苯硼钠—季铵盐容量法快速测钾   总被引：4，自引：3，他引：1       下载免费PDF全文

冉广芬  马海州  孟瑞英  陈育刚 《盐湖研究》2009,17(2):39-42

用四苯硼钠—季铵盐容量法间接测定钾,并与四苯硼钠重量法进行比较。测定1%以上的钾含量时,相对误差<1%,平均回收率为99.52%,标准偏差分别为0.0082、0.0073,变异系数分别为0.82%、0.33%(RSD,n=7)。该方法操作简便、快速、准确,适用于含钾产品的中间控制分析及钾盐、卤水、盐化工产品、钾肥中钾的快速测定。  相似文献   

Air masses and aerosols chemical components in the free troposphere at the subtropical northeast atlantic region     

A. M. Díaz  J. P. Díaz  F. J. Expósito  P. A. Hernández-Leal  D. Savoie  X. Querol 《Journal of Atmospheric Chemistry》2006,53(1):63-90

The dynamics and the aerosol chemistry of the air masses reaching the free troposphere of the subtropical Northeast Atlantic region during the period 1995–98 have been studied. Seven days backward trajectories were calculated daily with HYSPLIT-4 model for Izaña Global Atmospheric Watch (GAW) Observatory (28.3^°N 16.5^°W, 2367 m a.s.l.). These back-trajectories were classified by means of a k-means clustering strategy. The daily air masses have been coded using 16 variables to detect the aerosol load of each one of them. Four clusters were found: Cluster 1, representative of Atlantic oceanic middle troposphere air masses, (OMT), has an average frequency of occurrence of 50.6%. Cluster 2, which includes air masses originated in the African continent (AfD), has been recorded in a 19.8% of time. Cluster 3 represents a mixture at least of two of the next sources: Europe, Africa and Ocean, (EAM), with a frequency of 12.7%. Finally, Cluster 4 includes air masses with a high load of maritime aerosols, (MaA), and it has been detected in a 16.9%. An analysis of four aerosol components: NO₃ ^?, NH₄ ⁺, non-sea-salt-SO₄ ^2?, and mineral dust and its relation with the origin and transport of the air masses have been done. The highest quantities of mineral dust and nss-SO₄ ^2? are linked with African air masses with a mean value of 86.5 and 1.9 μg/m³ respectively. Whereas the highest levels of NO₃ ^?, 1.0 μg/m³, and NH₄ ⁺, 0.4 μg/m³, were obtained for AfD and EAM. The lowest levels were associated with OMT and MaA air masses types: 12.7, 0.6, 0.2, and 0.5 μg/m³ for dust, NO₃ ^?, NH₄ ⁺, and nss-SO₄ ^2? in average for the four studied years. However, it is remarkable that the values of the median for dust are 2.2 and 3.5 μg/m³ in clusters MaA and OMT respectively. Using non-parametric statistical tests the distributions of concentrations in each cluster by year have been compared in order to detect similarities. The results show that the aerosol loads of OMT and MaA air masses are quite similar and the same occurs for AfD and EAM air masses. However, the correlation analysis between the levels of anions and ammonium evidenced important differences among the air mass types. In AfD air masses is clear a low correlation between levels of nss-SO₄ ^2? and NH₄ ⁺ (r ² = 0.08) suggesting that the sulfate speciation was dominated by sulfate species others than ammonium sulfate, such as calcium sulfate. CaSO₄ ?2H₂O (gypsum) is mainly present in the coarse mode, where the radiative effects of sulfate are less important that in the accumulative mode. For OMT air masses is noticeable an important increasing on the correlation between the levels of anions and those of NH₄ ⁺ for the two last years of the study period (1997–1998, r ² = 0.61 –0.85%) with respect to the first ones (1995–1996, r ² = 0.25–0.49%), coinciding with the second strongest ENSO (El Niño Southern Oscillation) event recorded. This behavior indicates a change in the speciation of the aerosol component.  相似文献   

振荡交换-抽滤淋洗结合凯氏定氮法快速测定土壤中的阳离子交换量   总被引：2，自引：1，他引：1  

马怡飞  张尼  魏增  高文旭  王奎 《岩矿测试》2019,38(1):129-135

测定土壤阳离子交换量(CEC)的行业标准方法(LY/T1243—1999)是采取离心分离结合手工蒸馏进行滴定,耗时长、操作繁琐。为了缩短反应时间,提高检测效率,本文利用乙酸铵对酸性和中性土壤进行处理,用氯化铵-乙酸铵对石灰性土壤进行处理,应用振荡和抽滤装置快速交换和清洗阳离子,通过全自动凯氏定氮仪对吸附的铵根离子进行测定,由此计算CEC值。结果表明:在最佳的振荡和蒸馏时间、滴定酸浓度、指示剂配比等实验条件下,一个批次样品(100件)的分析流程仅需要12h,比传统方法检测时间缩短近80%。经国家标准物质验证,测定结果与推荐值相符,5次测定的相对标准偏差均小于1. 5%。本方法免去了多次离心分离操作,解决了待测成分损失、CEC测定值偏低的问题,提高了检测效率和准确度,较林业标准方法的成本低,可操作性强,适用于土壤环境质量评价、地区土壤抽样调查等大批量土壤样品分析。  相似文献   

Measurements of Trace Substances in the Arctic Troposphere as Potential Precursors and Constituents of Arctic Haze     

W. Jaeschke  T. Salkowski  J. P. Dierssen  J. T. Trümbach  U. Krischke  A. Günther 《Journal of Atmospheric Chemistry》1999,34(3):291-319

During two measuring campaigns in early spring 1994 and 1995 (March/April) and one campaign in summer 1994, measurements of ozone, PAN, sulfur dioxide, nitric acid, and particulate nitrate, sulfate, and ammonium (only 1995) were recorded in the Arctic. Observations were made by aircraft at various sites in the eastern and western Arctic. Ozone concentrations showed a steady increase with altitude both in spring and summer. During five flights in springtime, low ozone events (LOEs) could be observed near the surface and up to altitudes of 2000 m. SO₂ background concentrations, ranging from detection limit (0.5 nmol/m³) to 5 nmol/m³, were observed during both spring and summer. Distinct maxima up to 55 nmol/m³ in lower altitudes were only obtained in springtime. Concentrations of the organic nitrate PAN were within a similar range as those of the inorganic nitrate HNO₃ during spring campaigns. In contrast, concentrations of particulate nitrate were one half an order of magnitude lower. HNO₃ concentrations increased significantly with altitude. Evidently, HNO₃ was intruded from the stratosphere into the troposphere. Sulfate concentrations ranged between 5 and 30 nmol/m³; ammonium concentrations were obtained within a range from 10 to 50 nmol/m³.  相似文献   

不同水生植物对湿地无机氮素去除效果的模拟   总被引：7，自引：1，他引：6  

万晓红  李旭东  王雨春  陆瑾  赵茵茵  刘玲花  周怀东 《湖泊科学》2008,20(3):327-333

分别以芦苇、花叶水葱和苦草构建成小规模人工湿地模拟系统,开展不同类型水生植物湿地中无机氮（硝态氮和铵态氮）去除效果的试验。试验结果表明：在分别以芦苇、花叶水葱和苦草构成的模拟湿地单元中,虽然氧化还原等环境条件呈现较大差异,但不同类型水生植物湿地单元的铵态氮和硝态氮的去除率并没有显著差别,这与以往关于不同类型水生植物对氮素去除贡献的认识有所不同;水生植物对模拟湿地体系中氮素的去除具有重要作用,在相对较低的氮负荷（NH4^＋-N约为2.85mg／L,NO3^-N约为1.07mg／L,相当于一般城市污染河流）条件下,有水生植物湿地单元中铵态氮和硝态氮的10d去除率分别在39.32％和21.91％以上,而无水生植物的空白湿地单元对铵态氮和硝态氮的10d去除率分别只有34.68％和13.86％;在提高模拟湿地体系水体氮（NH4^＋-N约为5.50mg／L,NO3^-N约为3.37mg／L,是一般城市污染程度的2倍）负荷条件下,有水生植物湿地单元中铵态氮和硝态氮的10d去除率分别大于或等于66.87％和78.92％以上,而无水生植物的空白湿地单元对铵态氮和硝态氮的10d去除率仅为40.62％和31.77％,为人工湿地对原污水或初沉池出水的处理提供了有力依据。试验结果还表明,水生植物能有效促进湿地的氮素转化过程,显著缩短无机氮素在湿地中的寄宿时间。  相似文献   

氟化氢铵快速分解-电感耦合等离子体质谱法测定含刚玉铝土矿中锂镓锆稀土等痕量元素     

刘贵磊  许春雪  陈宗定  温宏利 《岩矿测试》2020,39(5):670-681

铝土矿中常伴有锂、镓、锆、稀土等有用组分,完全提取并准确测定其含量对于铝土矿资源综合评价和综合利用具有重要意义。然而铝土矿中常常含有少量刚玉,常规的四酸、五酸和封闭压力酸溶法对其分解不完全,导致测定结果偏低。本文采用氟化氢铵作熔剂,高温下在旋盖PFA小瓶中分解样品,通过在熔样过程中使用少量硫酸,对不同熔矿温度、消解时间及试剂用量等因素详细考察,确定了最佳熔矿条件[200℃,3h,试样比4∶1(称样量50mg)],建立了氟化氢铵分解-电感耦合等离子体质谱法测定含刚玉铝土矿中37种痕量元素的分析方法。本方法能快速、有效地分解含刚玉铝土矿,经三种铝土矿国家标准物质GBW07177、GBW07181和GBW07182验证,并与四酸、五酸和封闭压力酸溶法的测定结果对比,三种标准物质中Li、Ga、Sr、Zr、Pb等9种元素的回收率分别在95.0%～115.0%、90.0%～110.0%和90.0%～110.0%之间,测定值与认定值相符。同时,本方法实现了铝土矿(Al_2O_3含量在42.97%～90.36%之间)中Al、Ti、P等主量元素的精确分析,进一步验证了其用来测定铝土矿中痕量元素的准确性。方法检出限为0.002～0.43μg/g,与传统硝酸-氢氟酸密闭消解法的检出限(0.000～0.48μg/g)基本相当,精密度在1.14%～8.84%之间,能够满足铝土矿中痕量元素的分析要求。  相似文献   

壳聚糖季铵盐的合成及性质研究   总被引：16，自引：0，他引：16  

张艳艳  马启敏  江志华 《中国海洋大学学报(自然科学版)》2005,35(3):459-462

为开发利用壳聚糖及其衍生物,采用异相法合成了壳聚糖季铵盐——羟丙基三甲基氯化铵(HACC),并分别用红外光谱、核磁共振对其结构进行了表征;通过扫描电镜图对比分析了CS和HACC的粒度和外貌形态变化。在此基础上,测定了HACC的取代度(DQ),并对其溶液性质进行研究。结果表明：通过在壳聚糖分子结构中N上引入季铵盐侧链合成的HACC,具有较好的水溶性和较高的稳定性,室温下水中溶解度达10％,1％醋酸水溶液粘度在12d内、水溶液粘度在pH=3～9范围内几乎没有降低。  相似文献   

石墨炉原子吸收法测定生物样品中微量钒     

田莉玉  贾健秀  刘淑芹 《吉林地质》2004,23(4):106-108

生物样品用灼烧法,除去有机物,在浓度为5％的盐酸介质中,加入EDTA和铵盐作为基本改进剂,清除石墨炉原子吸收法测定钒时铜、铁离子的干扰,可直接测定钒．采用标准加入法回收率为96．4-106．8％,相对标准偏差3．95％。  相似文献