珠江三角洲地区大气中多环芳烃的被动采样观测

研究了珠江三角洲地区大气中多环芳烃的含量与分布.利用大气被动采样装置,在包括香港在内的珠江三角洲地区共设立了21个大气被动采样点,样品采集时间为2005-08-15—10-14.结果表明,除主要存在于气相中的2～3环PAHs与部分4环PAHs外,聚氨酯泡沫材料(PUF)被动采样器也可在一定程度上采集大气颗粒物中的5～7环PAHs.珠江三角洲地区大气PAHs的含量与组成存在较大差异,珠江三角洲内地采样点PAHs的含量远远高于香港采样点,这主要是受采样点所处的地理位置、气候条件以及能源消费结构的影响.初步研究表明,PUF大气被动采样器可较好地运用于区域大气PAHs污染分布与特征对比研究.      

被动采样技术在监测大气有机氯污染物中的应用

为了研究大气被动采样技术的可行性,评价其技术性能、特色和应用价值,采用以XAD-2树脂为吸附介质的被动采样器,对北京市和四川卧龙自然保护区大气中的典型持久性有机氯污染物分别进行了为期5个月和半年的样品采集,利用气相色谱-高分辨质谱方法对HCB,HCHs,DDTs和PCBs等进行了测定.结果表明:数据重现性良好,检测下限的范围为0.2～8.0 pg/m3;北京市有机氯污染物检出质量浓度相对较高,其中ρ(HCB)最高,为1 910 pg/m3,ρ(p,p′-DDT)最低,为21 pg/m3;卧龙自然保护区有机氯污染物检出质量浓度相对较低,其中ρ(HCB)最高,为254 pg/m3,ρ(PCB52)最低,为1.3 pg/m3.初步表征、比较了北京市和四川卧龙自然保护区大气中HCB,HCHs,DDTs和PCBs等化学组成特征.以XAD-2树脂为吸附介质的大气被动采样器,可以应用于城市和边远地区持久性有机氯污染物的长期采样和监测.      

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.     

A STAGE-ACTIVATED TRIGGERING DEVICE FOR AUTOMATIC PUMPING SAMPLERS1

A device to trigger automatic pumping samplers at discrete stages on headwater streams in southeastern Oklahoma was developed. The magnetic switch column employs a sequence of magnetic reed switches wired in parallel and set at 0.03 m (0.10 ft) intervals. A magnetic float inside the column closes the reed switches, therby triggering the sampler as stage rises and falls. The columns were constructed from inexpensive, readily-available materials. Following installation and field calibration, the columns provided relaible and representative sampling during 12 storms, at three sites. The magnetic switch column may be used in a wide range of research and monitoring sites to improve water quality sampling.     

Comparison of maternal and fetal chromosome heteromorphisms to monitor maternal cell contamination in chorionic villus samples

Maternal cell contamination (MCC) presents a potential problem in the analysis of chorionic villus sampling (CVS) preparations for early prenatal diagnosis by chromosomal, biochemical and molecular methods. Through the comparison of fluorescent chromosome variants from CVS and maternal cells, we found three out of 50 samples to have MCC. One of these was observed on a direct preparation. Routine chromosome heteromorphism analysis suggested as a reliable method for monitoring MCC in CVS specimens.     

ASSESSMENT OF SAMPLING ERROR ASSOCIATED WITH SOIL MOISTURE ESTIMATION DESIGNS1

A spectral formalism was developed and applied to quantify the sampling errors due to spatial and/or temporal gaps in soil moisture measurements. A design filter was developed to compute the sampling errors for discrete measurements in space and time. This filter has as its advantage a general form applicable to various types of sampling design. The lack of temporal measurements of the two‐dimensional soil moisture field made it difficult to compute the spectra directly from observed records. Therefore, the wave number frequency spectra of soil moisture data derived from stochastic models of rainfall and soil moisture were used. Parameters for both models were estimated using data from the Southern Great Plains Hydrology Experiment (SGP97) and the Oklahoma Mesonet. The estimated sampling error of the spatial average soil moisture measurement by airborne L‐band microwave remote sensing during the SGP97 hydrology experiment is estimated to be 2.4 percent. Under the same climate conditions and soil properties as the SGP97 experiment, equally spaced ground probe networks at intervals of 25 and 50 km are expected to have about 16 percent and 27 percent sampling error, respectively. Satellite designs with temporal gaps of two and three days are expected to have about 6 percent and 9 percent sampling errors, respectively.     

The use of cluster sampling to determine aid needs in Grozny, Chechnya in 1995

War broke out in Chechnya in November 1994 following a three-year economic blockade. It caused widespread destruction in the capital Grozny. In April 1995 Medical Relief International--or Merlin, a British medical non-governmental organisation (NGO)--began a programme to provide medical supplies, support health centres, control communicable disease and promote preventive health-care in Grozny. In July 1995 the agency undertook a city-wide needs assessment using a modification of the cluster sampling technique developed by the Expanded Programme on Immunisation. This showed that most people had enough drinking-water, food and fuel but that provision of medical care was inadequate. The survey allowed Merlin to redirect resources earmarked for a clean water programme towards health education and improving primary health-care services. It also showed that rapid assessment by a statistically satisfactory method is both possible and useful in such a situation.