Determination of PCDDs and PCDFs in PCB oil from a hazardous waste site

This paper describes the analysis of hazardous waste oil samples with procedures that were developed primarily to clean up and analyze biological samples. Details of the cleanup procedure and the results from the analysis of several waste PCB oil samples are presented.     

Long series relationships between global interannual CO2 increment and climate: evidence for stability and change in role of the tropical and boreal-temperate zones

Interannual variability in global CO₂ increment (averaged from the Mauna Loa and South Pole Stations) shows certain strong spatial relationships to both tropical and temperate temperatures. There is a fairly strong positive year-round correlation between tropical mean annual temperatures (leading by 4 months) and annual CO₂ throughout the time series since 1960, agreeing with the generally held view that the tropics play a major role in determining inter-annual variability in CO₂ increment, with a major CO₂ pulse following a warm year in the tropics. This ‘almost no lag’ climatic response is very strong during winter and relatively stable in time. However, the correlation with tropical temperature appears to have weakened in the first years of the 1990s in correspondence of the Pinatubo eruption and the positive phase of the AO/NAO. A secondary concurrent temperature signal is linked to summer variations of north temperate belt. Northern summer temperatures in the region 30–60 °N—and especially in the land area corresponding to the central east USA—have become relatively more closely correlated with CO₂ increment. This trend has become increasingly stronger in recent years, suggesting an increasing role for growing season processes in the northern midlatitudes in affecting global CO₂ increment. Once non-lagged annual tropical temperature variations are accounted for, terrestrial ecosystems, especially the temperate-boreal biomes, also show a coherent large scale lagged response. This involves an inverse response to annual temperature of preceding years centered at around 2 years before. This lagged response is most likely linked to internal biogeochemical cycles, in particular N cycling. During the study period north boreal ecosystems show a strengthening of the lagged correlation with temperature in recent years, while the lagged correlation with areas of tropical ecosystems has weakened. Residuals from a multiple correlations based on these climatic signals are directly correlated with SO, confirming an additional important role of upwelling in interannual variability of CO₂ increment. Cooler summers following the Pinatubo eruption and the possible influence of the North Atlantic Oscillation (NAO/AO) are discussed as factors responsible for the shift in the relative importance of different regions over time during the series of data.     

Release of phagocytosis-stimulating factor(s) by morula cells in a colonial ascidian

In vitro yeast phagocytosis by haemocytes of the compound ascidian Botryllus schlosseri was studied, with particular attention to interactions among different immunocyte types. It is demonstrated that the supernatant from haemocyte cultures matched with yeast cells contains factor(s) able to enhance yeast ingestion by Botryllus phagocytes. The increase in phagocytosis is not the consequence of yeast opsonisation, as the phagocytic index does not significantly increase when yeast cells, previously incubated in the culture media, are washed and re-suspended in filtered sea water. When haemocytes were fractionated by density gradient centrifugation and each band was incubated with yeast, the ability to stimulate phagocytosis was found in the supernatants from haemocyte cultures of fractions rich in morula cells (MC). Previous studies have demonstrated that MC express molecules recognised by anti-cytokine antibodies, as a consequence of the recognition of foreign molecules or cells. Our results indicate that molecules immunoreactive with anti-cytokine antibodies are required for modulating phagocyte activity, as the above-reported enhancing effect is completely absent in the presence of anti-IL-1-α and anti-TNF-α, but not of anti-rabbit-IgG antibodies, and they also highlight the presence of ‘cross-talk‘ between MC and phagocytes. A new scenario is therefore sketched, in which MC actively recognise non-self molecular patterns and, upon this recognition, release humoural factor(s) recognised by phagocytes, which modulate phagocytosis.     

生物质燃烧颗粒物的定量分析和化学形态

用电子探针技术开展单个含钾颗粒物的分析表征 .第一种方法用蒙特卡洛方法模拟电子束与样品复杂的相互作用 ,对于KCl晶粒取得的计算结果与理论值一致 .K/Cl比的均值为 0 996 ,标准偏差为 0 0 1 2 .由于晶形不规则和热稳定性差 ,K2 SO4 和KHSO4 的结果没有达到KCl的准确度 .其K/S比的均值和标准偏差分别为 1 90 5±0 0 1 3和 1 0 1 4± 0 0 72 .第二种方法用回归分析方法处理了同一种类若干数目的颗粒物分析数据 .直接用同种类标准颗粒物的分析结果校准 ,进行定量分析和化学形态识别 .研究结果表明 ,非洲草原大火燃烧排放时 ,含钾颗粒经历了逐步酸化的过程 .在排放时主要以KCl形态存在 ,少量是K2 SO4 和复盐 .在大气传输过程中逐渐酸化 ,主要转变成KHSO4 .少量停空时间长的颗粒则继续酸化 ,成为高度富硫的颗粒 .     

用扫描电镜分析表征大气气溶胶单颗粒

1　IntroductionAtmosphericaerosolsarecomplexmixture,originatedfromavarietyofsources.Mostoftheanalyticaltechniquesusedforitscharacterizationarebulkmethodsthatgenerateonesetofdatapersample,describingtheoverallcompositionofthesample .Toworkoutusefulinformationonpollu tionsources,itrequiresdataofagreatnumberofsamplesandmultivariatedataanalysismethodsusuallyareneeded .Ontheotherhand ,scanningelectronmicroscope energydispersiveX rayanaly sissystem (SEM EDX)isabletoprovideanalyticaldataforeachsing…     

Two-phase modeling of sediment clouds

A sediment cloud release in stagnant ambient fluid occurs in many engineering applications. Examples include land reclamation and disposal of dredged materials. The detailed modeling of the distinct characteristics of both the solid and fluid phases of the sediment cloud is hitherto unavailable in the literature despite their importance in practice. In this paper, the two-phase mixing characteristics of the sediment cloud are investigated both experimentally and theoretically. Experiments were carried out to measure the transient depth penetration and the lateral spread of the sediment cloud and its entrained fluid using the laser induced fluorescence technique, with a range of particle sizes frequently encountered in the field (modeled at laboratory scale). A two-phase model of the sediment cloud that provides detailed predictions of the mixing characteristics of the individual phases is also proposed. The entrained fluid characteristics are solved by an integral model accounting for the buoyancy loss (due to particle separation) in each time step. The flow field induced by the sediment cloud is approximated by a Hill’s spherical vortex centered at the centroid and with the size of the entrained fluid. The particle equation of motion under the effect of the induced flow governs each computational particle. A random walk model using the hydrodynamic diffusion coefficient is used to account for the random fluctuation of particles in the dispersive regime. Overall, the model predictions of the two-phase mixing characteristics are in good agreement with the experimental data for a wide range of release conditions.     

Assessment of metal contaminations leaching out from recycling plastic bottles upon treatments

Background, aims, and scope  

Heavy metal contaminants in environment, especially in drinking water, are always of great concern due to their health impact. Due to the use of heavy metals as catalysts during plastic syntheses, particularly antimony, human exposure to metal release from plastic bottles has been a serious concern in recent years. The aim and scope of this study were to assess metal contaminations leaching out from a series of recycling plastic bottles upon treatments.