共查询到18条相似文献,搜索用时 62 毫秒
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李秋波 《中国环境管理干部学院学报》2012,(5):60-64
将微波消解-紫外法测定总氮从方法检出限、校准曲线、精密度和准确度、实际样品测定4个方面与国标紫外法作了比较研究,进行了消解时间比对实验,说明了微波消解-紫外法测定总氮的注意事项。结果表明,微波消解-紫外法检出限为0.115 mg/L,高于国标紫外法;校准曲线具有较好线性相关系数,斜率与国标紫外法一致;方法精密性和准确性较好,实际样品测定结果与紫外法保持一致,在总氮监测中具有可行性。微波消解-紫外法节省了总氮监测的整个用时。 相似文献
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紫外分光光度测定总氮的影响因素探讨 总被引:1,自引:0,他引:1
本文介绍了测定总氮过程中,不同消解方法、碱性过硫酸钾的稳定时间、悬浮物粒径对总氮测定的影响。实验表明:碱性过硫酸钾避光在冰箱中至少可保存一个月,悬浮物粒径对总氮的测定无影响,消解总氮时,可在压力锅加热到120℃开始计时,恒温消解30分钟,自然冷却。 相似文献
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分析了泥沙含量对总氮测定结果的干扰影响,结果表明:水样中泥沙的含量与其对水样总氮的贡献有显著的正相关性;泥沙对总氮测定结果有干扰影响,随泥沙含量增加,A275的测定值及总氮降低率逐渐增大,且当泥沙(SS)含量≥45 mg/L时,其A275/A220的值在20%以上,总氮降低率在15%以上,从而总氮测定值产生较大的误差。消解后离心法或消解后0.45μm滤膜过滤法能有效地消除泥沙的干扰,并均具有操作简单和准确度高的优点。 相似文献
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对王水消解-原子荧光法测定污泥中总汞的不确定度进行评定,从测定过程和计算方法的角度,对样品称量、曲线拟合、样品消解、稀释、仪器测量重复性及污泥含水率等影响不确定度的分量进行分析。结果表明:影响原子荧光法测定污泥中总汞的不确定度的主要因素是工作曲线的非线性和样品消解过程造成的损失,其次是样品消解液的稀释和仪器重复测定,而样品称量与污泥含水率的影响较小,可忽略不计。 相似文献
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对总氮测定方法HJ 636—2012的关键细节及其影响因素作了探讨和改进:可以用氢氧化钠水化过程放出的热来加速过硫酸钾的溶解,该过程过硫酸钾不降解,碱性过硫酸钾溶液室温下可保存15 d;pH值对总氮测定结果影响不大;10.0 mg/L硝酸钾标准使用液在0~10℃暗处保存可以稳定30 d;校准曲线稳定,在关键试剂没有更换时,可以不用每批样品分析同时绘制校准曲线;悬浮物影响总氮测定结果准确性,可采用一次性0.45μm水相针式过滤头过滤消解后定容的水样,快速有效去除悬浮物。 相似文献
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李秋波 《中国环境管理干部学院学报》2013,(3):65-68,76
结合紫外法测定水质中总氮空白校正吸光度值易偏高、测定结果准确度低的问题,分别从检测试剂含氮量、选择实验用水、清洗玻璃器皿、改进实验操作、改进消解环境等多个方面分析了各影响因素对总氮测定的影响,相应提出了采用测定含氮量的方法筛选试剂、新制备的去离子水作为总氮实验用水、每次总氮实验使用新刷好的器皿、增加颠倒混匀步骤提高测定结果的准确度和精密度、高压蒸汽灭菌器应定时清洗换水等对策与建议。 相似文献
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针对废水水质分析过程中出现的氨氮含量高于总氮含量的情况,对氨氮测定过程和总氮测定过程中的金属离子干扰、标准曲线绘制、消解时间等进行了分析,提出氨氮含量高于总氮含量是由于总氮消解时间不够,导致过硫酸钾的转化不完全造成的。实验结果表明,将总氮消解时间设定为40min可以解决此问题。为提高测定的准确性,在实验中还应注意实验环境、计量器具及高压灭菌锅的密封性等问题。 相似文献
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为了提高氮肥增产效益,减少对环境的污染,通过田间试验研究了施氮量对春玉米产量、氮肥效率及土壤矿质氮的影响。结果表明,施氮量较低时,春玉米籽粒产量随施氮量增加显著增加,当施氮量高于180kg·hm2时,产量保持不变或有减少趋势。氮肥农学利用率、氮素吸收效率、氮素偏生产力和氮收获指数均随着施氮量增加显著降低,氮肥表观利用率和氮肥生理利用率均先增加后降低。从苗期到收获期,施氮处理0~60cm土层硝态氮含量呈现“上升一下降一上升一下降一稳定”的变化趋势,而60~120cm土层硝态氮在春玉米生长后期有增加的趋势。随着土层加深,土壤硝态氮含量呈波浪式下降,施氮量240kg·hm-2和300kg·hm-2处理在60~100cm土层硝态氮含量均显著高于其他处理。随着施氮量增加,0~120cm土层硝态氮累积量显著增加,当施氮量超过240kg·hm-2时,土层中累积的硝态氮存在着较大的淋溶风险。综合考虑产量、氮肥效率和环境效应,179—209kgN·hm。是本试验条件下春玉米的合理施氮量。 相似文献
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Historical streamflow and concentration data were used in regression models to estimate the annual flux of nitrogen (N) to the Gulf of Mexico and to determine where the nitrogen originates within the Mississippi Basin. Results show that for 1980-1996 the mean annual total N flux to the Gulf of Mexico was 1,568,000 t yr-1. The flux was about 61% nitrate N, 37% organic N, and 2% ammonium N. The flux of nitrate N to the Gulf has approximately tripled in the last 30 years with most of the increase occurring between 1970 and 1983. The mean annual N flux has changed little since the early 1980s, but large year-to-year variations in N flux occur because of variations in precipitation. During wet years the N flux can increase by 50% or more due to flushing of nitrate N that has accumulated in the soils and unsaturated zones in the basin. The principal source areas of N are basins in southern Minnesota, Iowa, Illinois, Indiana, and Ohio that drain agricultural land. Basins in this region yield 1500 to more than 3100 kg N km-2 yr-1 to streams, several times the N yield of basins outside this region. 相似文献
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Nitrogen contamination in the Yellow River basin of China 总被引:3,自引:0,他引:3
Nitrogen contamination is one of the most serious problems in the Yellow River of China. This study was conducted to analyze monitoring data on nitrogen contamination for the Yellow River basin in the years 1980, 1990, 1997, and 1999. Several significant results have arisen from the study. First, in conjunction with an increase in economic indexes from the Yellow River's upper basin to its lower basin, the nitrogen concentration in the tributaries also showed an increasing trend from the upper to the lower basin, which, in turn, led to an increase in the nitrogen concentration of the mainstream from the upper to the lower reaches. Second, nitrogen in the river water in the mainstream and the tributaries of the Yellow River was attributed mainly to point sources. In spite of the fact that the ratio of point to nonpoint sources decreased from 2.7 in 1990 to 1.8 in 1997 for total inorganic nitrogen in river water at the Tongguan Station in the lower basin, point sources increased more than nonpoint sources. Third, the ammonium nitrogen and total inorganic nitrogen content of the river water increased significantly in the mainstream and the tributaries during the 1980-1999 period, a change caused by an increase in wastewater discharge and nitrogenous fertilizer application in the Yellow River catchment. 相似文献
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We develop an optimal control model for cost-effective management of pollution, including two state variables, pollution stock and ecosystem quality. We apply it to Baltic Sea pollution by nitrogen leachates from agriculture. We present a sophisticated, non-linear model of leaching abatement costs, and a simple model of nitrogen stocks. We find that significant abatement is achievable at reasonable cost, despite the countervailing effects of existing agricultural policies such as price supports. Successful abatement should lead to lower nitrogen stocks in the sea in 5 years or less. However, the rate of ecosystem recovery is less certain. The results are highly dependent on the rate of self-cleaning of the Baltic Sea, and less so on the discount rate. Choice of target has a radical effect on the abatement path chosen. Cost-effectiveness demands such a choice, and should therefore be used with care when stock effects are present. 相似文献
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采用纳氏试剂法测定废水中氨氮含量,其不确定度来源于标准曲线、取样体积和样品的重复测定,通过对测定过程涉及到的标准储备液、标准曲线绘制、标准曲线拟合、取样体积、移液管等因素进行分析,确定其产生的不确定度,进而提高测量的准确度。实验结果表明,通过对废水中氨氮不确定度的评定,能够准确反映实验过程中产生的不确定度的所有来源。 相似文献
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大气氮沉降增加是全球变化的重要现象之一,草原生态系统对氮沉降增加的响应成为草地生态学的研究热点之一。凋落物分解是草原生态系统养分循环和能量流动的主要途径,氮沉降增加引起草原植物群落结构变化,导致凋落物质量、土壤肥力、土壤微生物和土壤动物的变化,最终影响凋落物的分解。本文综述了氮沉降对草原凋落物结构、化学组成和分解环境的影响等方面的国内外最新研究进展,讨论了需进一步加强研究的内容,以期为进一步拓展该领域研究的广度和深度、为全面分析和评估全球变化对草原生态系统的影响提供参考。 相似文献