巯基棉富集分离铜试剂─吐温─80—OP水相光度法测定水中微量铜

研究了在非离子表面活性剂吐温－８０和乳化剂ＯＰ存在下，于ｐＨ８．５缓冲介质中，铜（Ⅱ）与铜试剂显色反应条件。结果表明：配合物的最大吸收波长为４５３ｎｍ，表观摩尔吸光系数为１．５４×１０４Ｌ·ｍｏｌ－１．ｃｍ－１，铜（Ⅱ）含量在０～７０μｇ／２５ｍｌ范围内符合比耳定律。该法与巯基棉富集分离相结合，应用于天然水及废水中微量铜的测定，结果满意。     

气相色谱法测定给水中三卤甲烷的方法

本文介绍了用毛细管柱气相色谱法定量测定给水中三卤甲烷（氯仿、一溴二氯甲烷、二溴一氯甲烷和溴仿）及四氯化碳的方法。其色谱条件是：检测器（ＥＣＤ）温度：３４５℃；色谱柱：ＨＰ５（２５ｍ×０３２ｍｍ×１０５μｍ）柱；进样口温度：２５０℃。该方法的最小检出下限分别为：氯仿０１μｇ／ｌ、四氯化碳０１μｇ／ｌ、一溴二氯甲烷０２μｇ／ｌ、二溴一氯甲烷０２μｇ／ｌ和溴仿０４μｇ／ｌ。     

无汞开管法快速测定工业废水中的COD

采用无汞开管法测定 COD。方法使用硫酸 -磷酸介质、重铬酸钾氧化体系 ,以硫酸银作催化剂 ,其他试剂包括硝酸银和硫酸铬钾以排除氯离子的干扰。样品在玻璃试管中进行消化 ,用一台恒温器加热样品 ,反应温度 1 65℃ ,加热时间只需 1 0 min,消解后剩余的重铬酸盐用分光光度法或滴定法测定。试验结果表明 ,本法的检出限为 1 0 .9mg/ L,测定范围为 3 0～ 1 5 0 0 mg/ L。由于方法不使用剧毒的汞盐 ,也就避免了汞对环境的污染。应用本法测定了大批量工业废水样品 ,结果令人满意     

A methodology to estimate carbon storage and flux in forestland using existing forest and soils databases

Sequestration of carbon through expansion and management offorestland can assist in reducing greenhouse gas concentrationsin the atmosphere. Quantification of the amount of carbonpresents an ongoing challenge that calls for new approaches.These new approaches must seek to simplify the science-basedaccounting of carbon storage and flux, while adhering to generalprinciples of greenhous gas accounting. Quantifying change incarbon storage and carbon flux consists of two steps: developinga baseline of carbon storage, and measuring resulting storageand flux following a change of conditions. A methodology isproposed that accomplishes both steps, applicable to anaggregate-level analysis using the state of Iowa (U.S.A.) as a case study. The method combines existing databasesfrom the U.S. Forest Service (USFS) and U.S. Department ofAgriculture (USDA), and merges these with the methods of Birdsey(USDA, 1992, 1995; IPCC, 1997; EIIP, 1999) for partitioningcarbon stocks into storage pools. Forested ecosystems in the study area contain approximately 137.3 metric tons organiccarbon per hectare, or 114 million metric tons of carbon inaggregate. Of this total, 44.7 million tons are stored inbiomass tissue, and 69.2 million tons of carbon are contained insoils. Carbon flux due to forests in the state of Iowa isestimated to be a net annual sequestration (removal from theatmosphere) of 4.3 million metric tons of CO₂-equivalent,approximately 5% of the net annual CO₂-equivalentemissions from the state (Ney et al., 1996).     

Size distribution in ultraphytoplankton: A comparative analysis of counting methods

Water samples taken at three depth layers from the offshore oligotrophic Cretan Sea were analyzed for ultraphytoplankton size fractionation using different methods: (a) sequential filtration on filters of pore size 5, 1 and 0.2 m, (b) separate filtration using filters 5 and 0.2 m as well as 1 and 0.2 m and (c) direct filtration on 0.2 m filters after staining of the samples with DAPI. Total abundance of photosynthetic organisms as well as the abundance of different groups such as flagellates and cyanobacteria measured by means of sizing after DAPI staining were significantly higher than those obtained by the other methods. This indicates that although there were no significant differences between the estimates provided by the separate and sequential filtration, both these methods underestimated total abundance by at least 25–50%. The estimates for the size fractions were also found to range from relatively imprecise to completely unreliable depending on the group and the size range. Although size fractionation through direct observation after staining largely depends on the expertise of the observer, this study suggests that it may provide more informative estimates than the other two methods. Although it is difficult to generalize the results of this study in a global context, the paper provides strong indications on the limitations of the sequential and separate methods for size fractionation of photosynthetic organisms and implies that their results are likely to be less accurate than is presently believed.     

关于水和废水中硫化物测定的几个问题

用碘量法测定废水中的硫化物,可能因无法消除干扰而使测定结果存在较大误差;对于同一废水样品,当碘量法和亚甲基蓝分光光度法的测定结果存在显著性差异时,可用Pb(Ac)2半定量法进行判定;对于某些化纤企业的废水,用氢氧化钾-乙醇溶液洗涤沉淀,可消除碘量法测定的干扰。使用光度法时,校准曲线的线性范围可由0～25μg,扩展到0～40μg。5 0μgS2- ml的ZnS混悬液置于冰箱内保存至少可以稳定一个月。     

水中硫化物突发性污染事故应急监测方法研究

水中硫化物不稳定,最好是现场即时测定。本文旨在研究现场快速测定水中的硫化物。本研究运用比色分析的朗伯-比尔定律和真空工艺设计,将复杂繁琐的实验室测试方法和操作程序有机的融合在测试管中。该测试管具有快速、简便和价格低廉等特点,测定范围0.1～10mg/L。     

常温下比色法和滴定法测定COD

在强酸溶液中，催化剂存在下，用重铬酸钾将Cr^6 还原为Cr^3 ，用比色法测定Cr^3 浓度或滴定过量的重铬酸钾来间接测定出COD浓度。     

基于针铁矿强化乙酸产甲烷过程的ADM1模型修正与模拟研究

为探究针铁矿对乙酸产甲烷途径的调控作用,利用ADM1模型（厌氧消化1号模型）对添加针铁矿的产甲烷过程进行模拟研究.首先引入氧化还原介质作为新变量,模拟SAO（syntrophic acetate oxidation,互营乙酸氧化）过程中的种间电子转移,进而建立包含DIET（direct interspecies electron transfer,直接种间电子传递）产甲烷过程的ADM1修正模型,最后利用该模型对各产甲烷途径的贡献进行评价.结果表明:①c（乙酸）分别为12和20 mmol/L时,添加40~2 000 mg/L针铁矿明显提高了乙酸体系的产甲烷速率.②修正的ADM1模型能够有效地模拟针铁矿强化乙酸产甲烷过程.③12、20 mmol/L乙酸体系的敏感性参数km_Xst（最大比乙酸氧化速率）校准值分别从1.02、1.46升至1.76、2.03,km_DIET（最大比电子消耗速率）校准值分别从0.78、1.48升至2.44、3.99,表明添加针铁矿提高了互营体系的种间电子传递速率.修正的ADM1模型对各产甲烷途径贡献的计算结果显示,针铁矿对DIET过程的强化作用与其添加量呈正相关,添加2 000 mg/L针铁矿试验组[c（乙酸）为12 mmol/L]中DIET和SAO产甲烷的贡献率相比对照组分别提升了117.99%和130.73%.研究显示,修正的ADM1模型能够有效地模拟针铁矿对乙酸产甲烷过程的强化作用,并且能用于评价各产甲烷途径的贡献.      

电热耦合强化非均质介质中三氯乙烯DNAPL的迁移去除

在氯代烃污染场地修复中,电阻加热技术因不受地层条件影响、污染物修复效率高等特点在氯代烃污染地块修复中得到了广泛关注,但仍存在用电量大、能耗较高等问题.通过创建基于脉动直流电的电热耦合修复体系,以三氯乙烯为模拟污染物,比较了其与传统基于交流电模式的电阻加热技术在修复非均质介质三氯乙烯重质非水相液体(DNAPL,dense nonaqueous-phase liquid)时的去除效率及能耗,分析了造成其修复差异的原因.结果表明:电热耦合体系下介质的增温幅度明显优于交流电体系,最高温度可达100℃,而交流电体系最高温度仅为70℃,这表明脉动直流电通过引入电极水电解反应提高了介质电导率,从而达到更高的温度,进一步促进了污染物的加热挥发作用.反应结束后,电热耦合体系中三氯乙烯主要集中在阴极侧,而交流电体系中三氯乙烯无定向分布特征,表明电热耦合体系中的直流电场可通过电渗析作用增强三氯乙烯向阴极的定向迁移.经过48 h持续反应,脉动直流电体系对三氯乙烯DNAPL的去除率为88%,可较同等电压下交流电体系提升2.2倍,而能耗仅为1.92 kW·h/(log·kg),是交流电体系的32%.研究显示,利用脉动直流电加热可通过强化相变迁移和电渗析定向迁移效应共同作用于三氯乙烯去除,有效提高三氯乙烯DNAPL的去除率,降低体系修复能耗.