顺序进样流动注射光度法测定水中氨氮

将顺序进样与流动注射分光光度法相结合,研发了氨氮自动在线检测仪,用于测定水中氨氮质量浓度.实验结果表明:当进样量为0.39 mL、显色剂体积为0.33 mL、停留时间为5 min、载流液流量为2.0 mL/min时,氨氮质量浓度p与吸光度A在氨氮质量浓度为0～ 15.00 mg/L的范围内呈良好的线性关系,标准工作曲线方程为A=0.01929+ 0.2362,相关系数为0.9993(n=11);检出限为0.020 mg/L;相对标准偏差为0.50％～2.38％;实际水样的加标回收率为94.5％～106.0％.     

Identification of important factors for water vapor flux and CO2 exchange in a cropland

Water vapor flux and carbon dioxide (CO₂) exchange in croplands are crucial to water and carbon cycle research as well as to global warming evaluation. In this study, a standard three-layer feed-forward back propagation neural network technique associated with the Bayesian technique of automatic relevance determination (ARD) was employed to investigate water vapor and CO₂ exchange between the canopy of summer maize and atmosphere in responses to variations of environmental and physiological factors. These factors, namely the photosynthetically active radiation (PAR), air temperature (T), vapor pressure deficient (VPD), leaf-area index (LAI), soil water content in root zone (W), and friction velocity (U*), were used as inputs in neural network analysis. Results showed that PAR, VPD, T and LAI were the primary factors regulating both water vapor and CO₂ fluxes with VPD and W more critical to water vapor flux and PAR and T more crucial to CO₂ exchange. Furthermore, two time variables “day of the year (DOY)” and “time of the day (TOD)” could also improve the simulation results of neural network analysis. The important factors identified by the neural network technique used in this study were in the order of PAR > T > VPD > LAI > U* > TOD for water vapor flux and in the order of VPD > W > LAI > T > PAR > DOY for CO₂ exchange. This study suggests that neural network technique associated with ARD could be a useful tool for identifying important factors regulating water vapor and CO₂ fluxes in terrestrial ecosystem.     

松花江、黑龙江水中可溶性铁与有机质含量的相关性

以黑龙江和松花江为研究对象,分析了河水中可溶性铁含量的分布特征及其与有机质含量、pH值的关系.结果表明,黑龙江、松花江水体中可溶性铁质量浓度分别为0.10～0.62和0.11～0.73 mg·L-1,Fe2+质量浓度分别为0.01～0.16和0.04～0.35 mg·L-1.松花江水体中可溶性铁、Fe2+浓度平均值均略高于黑龙江.同一年份内水体可溶性铁含量峰值以平水期居多.黑龙江水体CODCr与Fe2+含量呈显著负相关,松花江水体CODCr与可溶性铁含量呈显著正相关.松花江水体中BOD5、pH值与Fe2+含量呈显著负相关.人为来源的难生物降解有机质的大量输入提高了河水中铁离子的络合容量,使水中可溶性铁和有机络合铁含量增加.     

差压式直读BOD测定仪的验证实验

本文对“Ⅱ型差压式直读BOD测定仪进行了精密度、准确度、适用性和等效性的一系列验证实验,结果表明,“差压式直读BOD测定仪”是一种较为理想的BOD测定仪器,从而为该仪器法定为国家标准分析方法提供了科学依据。     

Routine, automated determination of inorganic and total mercury in multimedia using cold vapour atomic absorption spectrometry

A routine, automated analytical method for simultaneous determination of total and inorganic mercury by cold vapour atomic absorption spectrometry in multimedia is described. Excellent accuracy and precision results were obtained with human hair certified reference materials namely, BCR-397 and IAEA-086. The reproducibility relative standard deviation for total mercury was 4% and 22%, respectively. The limit of detection for total and inorganic mercury was 0.2 μg/g hair. The described method has been successfully applied in determination of total and inorganic mercury as well as organic mercury in human hair, urine and fish tissue samples.     

水中痕量氰化物的高灵敏冷原子吸收间接测定方法

鉴于汞冷原子吸收光度法测定汞的高灵敏度，提出了一种间接地测定水中痕量氰化物的新方法。由于汞与ＣＮ－能生成稳定的络合物，处于化合态的汞不再被还原为原子态的乘，因而，可在不经分离的情况下，用汞冷原子吸收光度法测定剩余的汞，从而求出氰化物的含量．方法经实验证明，灵敏度高，重现性好，快速简便。     

REVERSIBLE ADSORPTION OF AQUEOUS DIVALENT COPPER ION BY ESTUARINE SEDIMENTS1

Sediments were equilibrated with solutions containing divalent copper ion. A colorimetric method using the triethylenete-tramine complex of the metal ion was employed to measure changes in uptake of copper by the sediments. Studies were made with sediments from rivers in the British Isles which were in the proximity of areas which had been mined for metals for several hundred years. For comparison, similar studies were performed with a sample of sand and a soil with a high organic content. It was possible to follow the uptake of copper ion by the materials and estimate their abilities to adsorb copper ion. In particular, a strong correlation was observed between the organic content of the sediment and the total amount of copper adsorbed by the sample. Under the employed circumstances it was possible to demonstrate that the adsorption of the metal ion was reversible.     

我国生产安全领域个人风险和社会风险标准界定方法研究

通过对国内外风险标准界定研究,结合我国实际情况,提出包括安全生产责任制、安全管理组织机构、安全生产管理法规、安全生产投入、安全生产科学研究等12个影响生产安全领域的风险影响因素,并采用层次分析法对风险影响因素进行分析。其结果表明,安全生产规划、安全生产控制指标、安全生产管理法规和安全管理组织机构对风险值的影响程度最高。率先提出我国风险影响因素评价指标计算方法、个人风险标准和社会风险标准计算方法。研究成果对制定我国生产安全领域风险标准界定方法、建立我国安全生产风险标准具有重要意义。     

水质总氮测试中高空白值形成规律与对策

通过一系列对比试验考察了根据GB 11894-89检测水质总氮时高空白值的形成规律.结果表明,过硫酸钾、氢氧化钠都可能造成空白值过高,且混合液消解后2种药剂会形成较强的交互作用,是空白值过高的主要原因.根据高空白值对总氮标准曲线不同部分的影响,建议将总氮标准曲线范围设定为1～10 mg/L(而非国标设定的0～10 mg/L),在高空白值条件下,该措施能显著提高总氮测试的准确性,满足大多数水质检测的需要.此外,国标规定的检测上限(4 mg/L)应理解为所测水样总氮浓度最高可达到10 mg/L.