Air monitoring of solvent exposed workers with passive samplers in comparison to “biological monitoring (BM)"†

A study was performed comparing ambient air monitoring (AM) and biological monitoring (BM) in order to evaluate the reliability of passive sampling (PS) in occupational medicine.

Five groups of persons (total number = 188) exposed to tetrachloroethene, isopropanol, toluene, xylene and styrene at the workplace were examined.

AM was performed over several hours using one or two brands of passive samplers (Monitor 3500 and/or ORSA 5). BM includes the determination of the solvent and specific metabolites resp. in blood or urine samples taken at the end of workshift. On the basis of our results we recommend that PS can supply relevant data for the estimation of external exposure to several solvents like chlorinated‐ and aromatic‐hydrocarbons.     

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％.     

基于先验信息的产品质量安全多阶段抽样方法研究

产品安全问题与消费者的人身健康和财产安全息息相关,关系到社会和谐稳定和经济可持续发展,已经成为政府、企业和社会公众高度关注的重要问题之一。监管部门的监管方式是通过直接从市场上购买某类产品或其重要部件,采用质量安全检测技术,发掘产品存在的安全风险。为降低样本量,采用了产品安全事故先验信息分析方法,并给出了获取先验信息的重要途径。其次,在抽样方案设计过程中,将产品抽样检测分成多个阶段,利用分批购买-分批检测的方法,动态调整样品分配,提高了发现产品安全风险的效率。最后,利用消费者协会提供的电视机投诉数据,对以上多阶段目的抽样方案进行了示例说明。     

多重密度布点对土壤有机质空间特性的解析

论文以张家港市耕层土壤有机质（Soil organic matter, SOM）为目标变量,通过网格布点建立11种样点密度梯度,运用经典统计学和地统计学方法研究其空间特性随布点密度变化的趋势规律。结果表明,各密度下SOM的变异系数稳定在21.70%~23.12%之间,表现出中等程度变异;随着布点密度降低,SOM的块基比和分维数分别由37.52%、1.838波动降至18.70%、1.714,Moran’s I则由0.485起伏升高至0.857,相应地其空间变异中结构变异组分增多、随机变异贡献减少,空间自相关性也逐渐增强;SOM呈现西南-东北递减分布,随着样点密度减小,其空间格局趋于简化。论文以布点密度为视窗,揭示了SOM的多重空间尺度特征,可为解析土壤属性的层级结构提供参考依据。     

四川西部山区土壤和大气有机氯污染物的区域分布

为研究持久性有机污染物（POPs）的长距离传输和边远山区POPs的区域分布与来源,于2005年10月—2008年4月在四川西部山区的卧龙自然保护区内沿巴朗山迎风坡1个海拔梯度（1 242～4 475 m）采集表层土壤和大气被动采样样品.对色谱-高分辨质谱（GC-HRMS）的数据分析表明,在卧龙山区2 800 m以上的高海拔地区,土壤和大气中HCB,HCHs和DDTs具有浓度低、分布均匀的特点,这可归因于大气长距离传输的贡献;在有人居住和活动的地区,也观测到HCHs和DDTs的浓度异常和污染情况.通过对有机氯污染物浓度水平、相对化学组成、浓度空间分布特征和季节变化等情况的综合分析,可以区分大气长距离传输和局地污染源排放2种源贡献.大气被动采样技术能够提供边远山区有机氯污染物大气浓度水平和时空分布的信息. 结合大气和土壤的现场数据,可以综合观测和表征山区环境有机氯污染物的浓度异常现象.      

Comparison of sensitivity analysis techniques: A case study with the rice model WARM

The considerable complexity often included in biophysical models leads to the need of specifying a large number of parameters and inputs, which are available with various levels of uncertainty. Also, models may behave counter-intuitively, particularly when there are nonlinearities in multiple input-output relationships. Quantitative knowledge of the sensitivity of models to changes in their parameters is hence a prerequisite for operational use of models. This can be achieved using sensitivity analysis (SA) via methods which differ for specific characteristics, including computational resources required to perform the analysis. Running SA on biophysical models across several contexts requires flexible and computationally efficient SA approaches, which must be able to account also for possible interactions among parameters. A number of SA experiments were performed on a crop model for the simulation of rice growth (Water Accounting Rice Model, WARM) in Northern Italy. SAs were carried out using the Morris method, three regression-based methods (Latin hypercube sampling, random and Quasi-Random, LpTau), and two methods based on variance decomposition: Extended Fourier Amplitude Sensitivity Test (E-FAST) and Sobol’, with the latter adopted as benchmark. Aboveground biomass at physiological maturity was selected as reference output to facilitate the comparison of alternative SA methods. Rankings of crop parameters (from the most to the least relevant) were generated according to sensitivity experiments using different SA methods and alternate parameterizations for each method, and calculating the top-down coefficient of concordance (TDCC) as measure of agreement between rankings. With few exceptions, significant TDCC values were obtained both for different parameterizations within each method and for the comparison of each method to the Sobol’ one. The substantial stability observed in the rankings seem to indicate that, for a crop model of average complexity such as WARM, resource intensive SA methods could not be needed to identify most relevant parameters. In fact, the simplest among the SA methods used (i.e., Morris method) produced results comparable to those obtained by methods more computationally expensive.     

Isochromosome 5p mosaicism at prenatal diagnosis: observations and outcomes in six cases at chorionic villus sampling and one at amniocentesis

We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal diagnosis of infantile hypophosphatasia

Prenatal diagnosis was attempted in a pregnant Japanese woman whose son had died of infantile hypophosphatasia, using chorionic villi sampled at 10 weeks of gestation. Southern blot analysis of restriction fragment length polymorphism was used as a guide, with cDNA for the human liver-type alkaline phosphatase as a probe, and BclI as a restriction enzyme. The fetus was found to be a heterozygote; the pregnancy was allowed to continue; and the baby born was phenotypically normal.     

Optimizing Liquid Effluent Monitoring at a Large Nuclear Complex

Effluent monitoring typically requires a large number of analytes and samples during the initial or startup phase of a facility. Once a baseline is established, the analyte list and sampling frequency may be reduced. Although there is a large body of literature relevant to the initial design, few, if any, published papers exist on updating established effluent monitoring programs. This paper statistically evaluates four years of baseline data to optimize the liquid effluent monitoring efficiency of a centralized waste treatment and disposal facility at a large defense nuclear complex. Specific objectives were to: (1) assess temporal variability in analyte concentrations, (2) determine operational factors contributing to waste stream variability, (3) assess the probability of exceeding permit limits, and (4) streamline the sampling and analysis regime. Results indicated that the probability of exceeding permit limits was one in a million under normal facility operating conditions, sampling frequency could be reduced, and several analytes could be eliminated. Furthermore, indicators such as gross alpha and gross beta measurements could be used in lieu of more expensive specific isotopic analyses (radium, cesium-137, and strontium-90) for routine monitoring. Study results were used by the state regulatory agency to modify monitoring requirements for a new discharge permit, resulting in an annual cost savings of US $223,000. This case study demonstrates that statistical evaluation of effluent contaminant variability coupled with process knowledge can help plant managers and regulators streamline analyte lists and sampling frequencies based on detection history and environmental risk.