基于光谱分析仪的通量-梯度法测量小型池塘水-气界面温室气体交换通量

小型池塘作为内陆水体的一部分,是被忽视的温室气体重要排放源.本研究主要利用通量-梯度方法测量长江三角洲地区的一处小型池塘水-气界面温室气体(CO_2和CH_4)交换通量.结果表明:1零梯度测试结果显示本套通量-梯度系统测量H_2O、CO_2和CH_4通量的精度分别为7.525 W·m-2、0.022 mg·(m2·s)-1、0.054μg·(m2·s)-1,并且在正常实验观测期间3种气体(H_2O、CO_2和CH_4)的通量值分别有84%、80%和94%的结果高于零梯度测试精度,以上结果可以保证本套通量-梯度系统具有足够的精度测量池塘水-气界面温室气体交换通量;2通量-梯度计算结果表明此小型池塘在夏季为CO_2和CH_4的排放源,其排放通量平均值分别为0.038 mg·(m2·s)-1和0.889μg·(m2·s)-1,其中CH_4排放通量远高于内陆湖泊甲烷排放通量的中值,说明小型池塘的温室气体排放量是估算内陆水体温室气体排放量特别是CH_4排放量中不可忽视的重要量值,本研究结果可为准确估算区域温室气体排放量提供科学参考.     

电化学传感器法监测室内空气中甲醛

通过用国家标准GB/T 18204.26-2000酚试剂分光光度法与电化学传感器原理的PPM-400 ST甲醛检测仪（PPM-Tech）相对比,并对可能影响甲醛检测仪监测结果的环境因素如空气中干扰物、风速、温度、湿度等进行研究。在95%置信度下,两种方法所得数据配对t检验的结果,差别无显著性意义;并将两种方法测得的数据进行相关分析,其回归方程式：y（传感器法）=0.004 6＋1.03x（酚试剂法）,相关系数为r=0.993 4。研究结果表明PPM-400 ST甲醛快速检测便携式仪器具有轻巧、方便、快捷、可靠、实时检测甲醛浓度的优点,检测结果与现有国家标准方法具有好的可比性。     

紫外光度法臭氧分析仪性能检查与问题处理

通过对Dasibi紫外光度法臭氧分析仪日常运行维护技术的归纳、统计和总结,整理了仪器性能检查和问题处理方法。希望对仪器的正常维护使用提供一些有益的参考。     

RA-915^＋型汞分析仪测定海水中的总汞

采用RA-915^＋型汞分析仪对海水中的总汞进行了测试。进行了线性关系、检出限、准确度、精密度、回收率等实验。实验结果表明,本方法检出限0．00002mg／L,在0—40000Pg范围内线性良好。本方法操作简单,灵敏度高,结果准确。     

盘溪河ToxScreen-Ⅱ测试法水体毒性沿程变化特征分析

应用ToxScreen-Ⅱ毒性分析仪发光细菌法对盘溪河水样进行毒性测试,分析其毒性沿程变化特征以及对嘉陵江水质的影响。结果表明,受污染物、流速、溶解氧等因素的影响,盘溪河水体生物毒性沿程表现出从无到有再到无的变化过程;虽然d3、d4、d5水体为微毒性,但入河口d7无毒性水体对嘉陵江水质影响较低。鉴于该仪器具有携带方便、操作简单、测试速度快、抗干扰力强等优点,建议在我市污染事故水体急性毒性分析及区域水质毒性变化预警监测中推广使用。     

某企业分析岗位职业病危害分析与控制

通过对某企业分析人员在取样过程、分析过程及样品处理过程中的职业危害进行识别与分析,提出了分析人员在作业过程中应采取的个体防护措施及工程上的预防与控制措施。     

絮团尺寸对全尾砂絮凝沉降效果的影响研究*

为研究絮团尺寸对全尾砂絮凝沉降效果的影响,采用正交实验和图像颗粒分析相结合的方法,进行多因素耦合条件下全尾砂絮凝沉降实验,基于Giddings函数的沉降速度模型,提出全尾砂絮团图像颗粒分析,探究各时段絮团尺寸的变化规律。研究结果表明:当尾砂浆浓度为15%、絮凝剂溶液浓度为0.25%、絮凝剂单耗为20 g/t,pH值为10时,絮凝沉降效果最佳,最大沉降速度达13.12 mm/s;随着沉降时间的增加,沉降速度随絮团直径、长径比减小而减小,随圆形度增大而减小。研究结果可为实际生产中控制全尾砂絮凝沉降参数、提高沉降速率提供参考。     

Is there really a green paradox?

In the absence of a CO₂ tax, the anticipation of a cheaper renewable backstop increases current emissions of CO₂. Since the date at which renewables are phased in is brought forward and more generally future emissions of CO₂ will decrease, the effect on global warming is unclear. Green welfare falls if the backstop is relatively expensive and full exhaustion of fossil fuels is optimal, but may increase if the backstop is sufficiently cheap relative to the cost of extracting the last drop of fossil fuels plus marginal global warming damages as then it is attractive to leave more fossil fuels unexploited and thus limit CO₂ emissions. We establish these results by analyzing depletion of non-renewable fossil fuels followed by a switch to a clean renewable backstop, paying attention to timing of the switch and the amount of fossil fuels remaining unexploited. We also discuss the potential for limit pricing when the non-renewable resource is owned by a monopolist. Finally, we show that if backstops are already used and more backstops become economically viable as the price of fossil fuels rises, a lower cost of the backstop will either postpone fossil fuel exhaustion or leave more fossil fuel in situ, thus boosting green welfare. However, if a market economy does not internalize global warming externalities and renewables have not kicked in yet, full exhaustion of fossil fuel will occur in finite time and a backstop subsidy always curbs green welfare.     

Methanogenic community structure in simultaneous methanogenesis and denitrification granular sludge

A laboratory scale up-flow anaerobic sludge bed (UASB) bioreactor fed with synthetic wastewater was operated with simultaneous methanogenesis and denitrification (SMD) granules for 235 days with a gradient decrease of C/N. Molecular cloning, qRT-PCR and T-RFLP were applied to study the methanogenic community structures in SMD granules and their changes in response to changing influent C/N. The results indicate that when C/N was 20:1, the methane production rate was fastest, and Methanosaetaceae and Methanobacteriaceae were the primary methanogens within the Archaea. The richness and evenness of methanogenic bacteria was best with the highest T-RFLP diversity index of 1.627 in the six granular sludge samples. When C/N was reduced from 20:1 to 5:1, the methanogenic activity of SMD granules decreased gradually, and the relative quantities of methanogens decreased from 36.5% to 10.9%. The abundance of Methanosaetaceae in Archaea increased from 64.5% to 84.2%, while that of Methanobacteriaceae decreased from 18.6% to 11.8%, and the richness and evenness of methanogens decreased along with the T-RFLP diversity index to 1.155, suggesting that the community structure reflected the succession to an unstable condition represented by high nitrate concentrations.

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Activity and characteristics of “Oxygen-enriched” highly reactive absorbent for simultaneous flue gas desulfurization and denitrification

An “Oxygen-enriched” highly reactive absorbent was prepared by mixing fly ash, lime and a small quantity of KMnO₄ for simultaneous desulfurization and denitrification. Removal of SO₂ and NO simultaneously was carried out using this absorbent in a flue gas circulating fluidized bed (CFB). The highest simultaneous removal efficiency, 94.5% of SO₂ and 64.2% of NO, was achieved under the optimal experiment conditions. Scanning Electron Microscope (SEM) and Accessory X-ray Energy Spectrometer (EDX) were used to observe the surface characteristics of fly ash, lime, “Oxygen-enriched” highly reactive absorbent and the spent absorbent. An ion chromatograph (IC) and chemical analysis methods were used to determine the contents of sulfate, sulfite, nitrate and nitrite in the spent absorbents, the results showed that sulfate and nitrite were the main products for desulfurization and denitrification respectively. The mechanism of removing SO₂ and NO simultaneously was proposed based on the analysis results of SEM, EDX, IC and the chemical analysis methods.