Effects of smelter sulfur dioxide emissions: a spatiotemporal perspective using carbon isotopes in tree rings

We wanted to test the hypothesis that forest exposure to phytotoxic gases indirectly affects their carbon uptake. We estimated that the reduction of photosynthesis may have reached 20 to 30% at a site located 9 km (test site) from the Horne copper smelter in Rouyn-Noranda, which is a point source of SO2. Twenty-one spruce trees older than 100 yr were selected from seven sites at various distances from the smelter to evaluate conditions prior to and during the periods of smelter operation. The carbon isotope results obtained from spruce tree rings at our test site reveal an unprecedented and abrupt shift of +4/1000 after the onset of smelter operations. This large and permanent shift exceeds natural variations in regional pre-smelter series or in the series at a remote control site. All trees up to 116 km downwind from the smelter show delta13C positive shifts following the onset of operations. There is also a clear inverse relationship between the amplitude of the first-order trends and distance from the smelter. Those delta13C trends indicate that trees exposed to high levels of SO2 decrease their level of CO2 uptake through activation of stomatal closure. This is strongly supported by the significant departure of the Rouyn-Noranda trends from those measured for trees from non-industrialized areas of the Northern Hemisphere, or calculated using global atmospheric conditions. Considering the large number of SO2 point sources in North America, our results imply that CO2 uptake by the boreal forest in the vicinity of these sources may be lower than previously thought.     

Effect of culture conditions on the formation of struvite by Myxococcus xanthus

The amount of struvite (MgNH₄PO₄·6H₂O) produced by Myxococcus xanthus as well as the culture parameter values (pH, total phosphorus, total Kjeldahl nitrogen) were dependent on the culture medium used. Struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. The addition of each medium component to the liquid culture influenced the amount of crystal produced. This amount did not depend on the pH increase during the culture period. The moment of the bacterial growth phase, at which each medium component was added, influenced the struvite formation.     

水质自动监测中的质量保证与质量控制

质量保证与质量拉制是水质自动监测中十分重要的技术工作和管理工作，包括人员素质、运行与管理机制、试剂与标准溶液的配制及文件记录等。在实际工作中，监测人员可根据仪器的运行状况，定期对仪器进行校准、标准溶液的棱查、比对实验验证及试剂有效性检查，用以检查仪器的基线飘移情况。如果分析中出现一个异常值，它的前后均为正常值，这种数值大多是由仪器的进样、仪器内部试剂传输等原因所致，如果发生原因不明的数据异常，就要及时检查系统的各个环节并采集实际水样进行人工分析，直至查清原因，剔除异常值，并在周报中加以说明，以确保上报数据的准确性、精密性和可比性。     

Twelve years of assessing the quality of preimplantation genetic testing for monogenic disorders

Objective

Genomics Quality Assessment has provided external quality assessments (EQAs) for preimplantation genetic testing (PGT) for 12 years for eight monogenic diseases to identify sub-optimal PGT strategies, testing and reporting of results, which can be shared with the genomics community to aid optimised standards of PGT services for couples.

Method

The EQAs were provided in two stages to mimic end-to-end protocols. Stage 1 involved DNA feasibility testing of a couple undergoing PGT and affected proband. Participants were required to report genotyping results and outline their embryo testing strategy. Lymphoblasts were distributed for mock embryo testing for stage 2. Submitted clinical reports and haplotyping results were assessed against peer-ratified criteria. Performance was monitored to identify poor performance.

Results

The most common testing methodology was short tandem repeat linkage analysis (59%); however, the adoption of single nucleotide polymorphism-based platforms was observed and a move from blastomere to trophectoderm testing. There was a variation in testing strategies, assigning marker informativity and understanding test limitations, some clinically unsafe. Critical errors were reported for genotyping and interpretation.

Conclusion

EQA provides an overview of the standard of preimplantation genetic testing-M clinical testing and identifies areas of improvement for accurate detection of high-risk embryos.     

Sustainable tourism development in remote regions? Questions arising from research in the North Kimberley,Australia

This paper is concerned with the sustainable development of a self-drive tourist destination in the remote region in Northern Australia. It first compares officially used data on visitor profiles to the information collected in the survey. Differences between data collected and available secondary data imply that tourism planning should include collection of region-specific tourism information to guide and mitigate potential environmental changes. Natural landscape features are the key attraction for visitors to the region. Visitor satisfaction levels with the current state of the destination are high. However, local residents reported perceived negative impacts of tourism, in particular on amenities and the ecology of the landscape. Visitors also reported behavior that might contribute to environmental impacts. Implications of the findings, in the context of future destination planning, are discussed.     

聚丙烯基高分子功能材料吸附卷烟烟气中多种有害成分的应用

为了寻找能同时降低卷烟烟气中甲醛、乙醛、巴豆醛和颗粒物有害成分含量的离子交换树脂吸附材料,采用电镜扫描方法观察聚丙烯基阳离子树脂高分子功能材料的表面特征,应用压汞法分析其平均孔径、中值孔径、比孔容和比表面积,并测试了该材料的交换容量,采用环境试验舱检测法对比测试了该材料和活性炭降低卷烟烟气中甲醛、乙醛、巴豆醛和颗粒物有害成分含量的效果.结果表明,聚丙烯基高分子功能材料表面多斑点状突起,凹凸状明显,微孔和缝隙多,平均孔径为0.26 μm,中值孔径为149.3 μm,比孔容为19.23 cm3/g,比表面积为293.42 m2/g,交换容量为5.16 mmol/g,对烟气中甲醛、乙醛、巴豆醛和颗粒物的净化率分别达到79.6％、79.8％、82.8％和64.7％,而活性炭的净化率分别为20.3％、0、6.4％和54.2％.研究表明,该聚丙烯基高分子功能材料具有物理吸附和化学吸附性能,净化卷烟烟气中多种有害成分的效果明显优于活性炭.     

高寒条件下振弦式传感器在线测量尾矿坝浸润线的误差分析及对策

为减少和消除高寒条件下振弦式传感器在线测量浸润线的误差,通过理论分析和现场试验,对造成误差的因素及其影响情况进行了深入研究。结果表明,振弦式传感器产生测量误差的主要来源为设备安装深度的测量误差与尾矿水密度及重力加速度的取值误差,并提出了减少或消除误差的方法和工程技术措施,为高寒地区的浸润线在线精确测量提供了重要指导意义。     

Predicting the aquatic risk of realistic pesticide mixtures to species assemblages in Portuguese river basins

Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This study estimated the impact of measured pesticide mixtures in surface waters from 2002 and 2008 within three important Portuguese river basins (‘Mondego’, ‘Sado’ and ‘Tejo’) on primary producers, arthropods and fish by toxic pressure calculation. Species sensitivity distributions (SSDs), in combination with mixture toxicity models, were applied. Considering the differences in the responses of the taxonomic groups as well as in the pesticide exposures that these organisms experience, variable acute multi-substance potentially affected fractions (msPAFs) were obtained. The median msPAF for primary producers and arthropods in surface waters of all river basins exceeded 5%, the cut-off value used in the prospective SSD approach for deriving individual environmental quality standards. A ranking procedure identified various photosystem II inhibiting herbicides, with oxadiazon having the relatively largest toxic effects on primary producers, while the organophosphorus insecticides, chlorfenvinphos and chlorpyrifos, and the organochloride endosulfan had the largest effects on arthropods and fish, respectively. These results ensure compliance with European legislation with regard to ecological risk assessment and management of pesticides in surface waters.