Managing the cost of emissions for durable,carbon-containing products

We recognize that carbon-containing products do not decay and release CO₂ to the atmosphere instantaneously, but release that carbon over extended periods of time. For an initial production of a stock of carbon-containing product, we can treat the release as a probability distribution covering the time over which that release occurs. The probability distribution that models the carbon release predicts the amount of carbon that is released as a function of time. The use of a probability distribution in accounting for the release of carbon to the atmosphere realizes a fundamental shift from the idea that all carbon-containing products contribute to a single pool that decays in proportion to the size of the stock. Viewing the release of carbon as a continuous probabilistic process introduces some theoretical opportunities not available in the former paradigm by taking advantage of other fields where the use of probability distributions has been prevalent for many decades. In particular, theories developed in the life insurance industry can guide the development of pricing and payment structures for dealing with the costs associated with the oxidation and release of carbon. These costs can arise from a number of proposed policies (cap and trade, carbon tax, social cost of carbon, etc), but in the end they all result in there being a cost to releasing carbon to the atmosphere. If there is a cost to the emitter for CO₂ emissions, payment for that cost will depend on both when the emissions actually occur and how payment is made. Here we outline some of the pricing and payment structures that are possible which result from analogous theories in the life insurance industry. This development not only provides useful constructs for valuing sequestered carbon, but highlights additional motivations for employing a probability distribution approach to unify accounting methodologies for stocks of carbon containing products.     

An enzyme-linked immunosorbent assay for the determination of dioxins in contaminated sediment and soil samples

A 96-microwell enzyme-linked immunosorbent assay (ELISA) method was evaluated to determine PCDDs/PCDFs in sediment and soil samples from an EPA Superfund site. Samples were prepared and analyzed by both the ELISA and a gas chromatography/high resolution mass spectrometry (GC/HRMS) method. Comparable method precision, accuracy, and detection level (8 ng kg(-1)) were achieved by the ELISA method with respect to GC/HRMS. However, the extraction and cleanup method developed for the ELISA requires refinement for the soil type that yielded a waxy residue after sample processing. Four types of statistical analyses (Pearson correlation coefficient, paired t-test, nonparametric tests, and McNemar's test of association) were performed to determine whether the two methods produced statistically different results. The log-transformed ELISA-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin values and log-transformed GC/HRMS-derived TEQ values were significantly correlated (r=0.79) at the 0.05 level. The median difference in values between ELISA and GC/HRMS was not significant at the 0.05 level. Low false negative and false positive rates (<10%) were observed for the ELISA when compared to the GC/HRMS at 1,000 ng TEQ kg(-1). The findings suggest that immunochemical technology could be a complementary monitoring tool for determining concentrations at the 1,000 ng TEQ kg(-1) action level for contaminated sediment and soil. The ELISA could also be used in an analytical triage approach to screen and rank samples prior to instrumental analysis.     

活性污泥合成聚羟基烷酸酯代谢机制研究进展

聚羟基烷酸酯(PHAs)是生物制备型环境友好塑料,具有广阔的应用前景.活性污泥合成PHAs可降低生产成本,实现废水处理厂剩余污泥的减量化和资源化.研究微生物合成PHAs的代谢机制,有利于优化PHAs的工业化生产,目前其代谢研究多集中在以纯菌种合成PHAs,而以活性污泥合成PHAs的研究尚不成熟.资料表明,DO变化对活性污泥合成PHAs的代谢途径有显著影响,进而改变其PHAs产物的产量和单体组成.综述了活性污泥合成PHAs在厌氧/好氧工艺、微氧/好氧工艺、缺氧/好氧工艺、好氧动态底物投加工艺条件下的代谢机制,分析了现有PHAs合成代谢模型中存在的问题,展望了PHAs合成代谢机制研究的发展方向.     

A chemical view of the most ancient metazoa--biomarker chemotaxonomy of hexactinellid sponges

Hexactinellid sponges are often considered to be the most ancient metazoans. Lipid biomarkers from 23 species were studied for information on their phylogenetic properties, particularly their disputed relation to the two other sponge classes (Demospongiae, Calcarea). The most prominent lipid compounds in the Hexactinellida comprise C28 to C32 polyenoic fatty acids. Their structures parallel the unique patterns found in demosponge membrane fatty acids ('demospongic acids') and strongly support a close phylogenetic association of the Demospongiae and the Hexactinellida. Both taxa also show unusual mid-chain methylated fatty acids (C15-C25) and irregular C25- and C40-isoprenoid hydrocarbons, tracers for specific eubacteria and Archaea, respectively. These biomarkers indicate a similar, highly conservative symbiont community, although some shift in the abundance of the associated microbiota was observed. The lack of these features in calcareous sponges further contradicts the still common view that Calcarea and Demospongiae are more closely related to each other than either is to the Hexactinellida.     

Dominance rank,resource availability,and reproductive maturation in female savanna baboons

Summary Ten years of data collected from a population of savanna baboons, Papio cynocephalus anubis, residing near Gilgil, Kenya were analyzed to ascertain the extent to which social and ecological factors influence reproductive maturation in females. First sexual swelling occurred at an average age of 4.79 years and first birth occurred at an average age of 6.92 years. Age at first menses was significantly correlated with age at first sexual swelling, but age at first sexual swelling was not a good predictor of age at first birth. The amount of rainfall in the 6 months preceding first sexual swelling and resource availability were significantly correlated with age at first sexual swelling. When ecological factors were taken into account, dominant females had an earlier age at onset of puberty, but not an earlier age at first birth, than did subordinate females. We suggest that nutritional and social stress operate at the same physiological level to disrupt GnRH pulsatility and retard reproductive maturation in some females. Given that socioecological variables modify the timing of life history events related to fitness in female baboons, the task for the future is to unravel how socioecological factors influence different life history components and generate variation in lifetime reproductive success. Correspondence to: F.B. Bercovitch