Iridoid glycoside sequestration byThessalia leanira (Lepidoptera: Nymphalidae) feeding onCastilleja integra (Scrophulariaceae)

A small population of a polyvoltine checkerspot butterfly,Thessalia leanira fulvia (also known asChlosyne leanira ssp.fulvia), was found to useCastilleja integra as a larval food plant at a localized site (Burnt Mill) southwest of Pueblo, Colorado. Field-captured adult butterflies contained the major iridoid glycosides (catalpol and macfadienoside) of theCastilleja. The content of a third iridoid glycoside, methyl shanzhiside, was also relatively high in the collected butterflies even though most individualCastilleja plants at Burnt Mill contained little or no methyl shanzhiside. Only a few plants, restricted to a small area, did contain appreciable methyl shanzhiside. Most of the plants that lacked the ester methyl shanzhiside contained shanzhiside, the corresponding free carboxylic acid.Thessalia larvae did not normally methylate the acid to produce methyl shanzhiside. Larvae that stopped feeding at an early instar, but yet survived several weeks, did contain major amounts of methyl shanzhiside. It is suggested that only larvae that overwinter or otherwise enter diapause convert shanzhiside to methyl shanzhiside. TheCastilleja food plant also contained iridoids other than catalpol and macfadienoside, sometimes in major amounts, but these were never found in larvae, pupae, or butterflies.Paper 27 in the series Chemistry of the Scrophulariaceae. Paper 26: Stermitz, F.R., Foderaro, T.A., and Li, Y.-X., 1993.Phytochemistry 32:1151     

Host plant utilization and iridoid glycoside sequestration byEuphydryas anicia (Lepidoptera: Nymphalidae)

The iridoid glycoside content of individual adultEuphydryas anicia butterflies from two Colorado populations was quantitatively determined. At one site (Red Hill), larval host plants wereCastilleja integra andBesseya plantaginea, while at the other site (Cumberland Pass) a single host plant,B. alpina, was used. At Red Hill, macfadienoside and catalpol were sequestered, while at Cumberland Pass, catalpol and aucubin were sequestered. Artificial diet studies showed that larvae hydrolyzed a major iridoid ofB. plantaginea, 6-isovanilIylcatalpol, to catalpol (which was sequestered) and isovanillic acid (which was excreted). Large year-to-year and individual variation in butterfly iridoid content was established as was a female-male difference in macfadienoside vs. catalpol content. Larval host plant distributions and numbers were determined at Red Hill for two years and compared with changes in butterfly populations and sequestered iridoids.     

Iridoid glycoside content ofEuphydryas anicia (Lepidoptera: Nymphalidae) and its major hostplant,Besseya plantaginea (Scrophulariaceae), at a high plains colorado site

The checkerspot butterfly,Euphydryas anicia, utilizes mainlyBesseya plantaginea and only occasionallyCastilleja integra as a larval hostplant at Michigan Hill, a few kilometers from a site whereC. integra is used by over 90% of the butterflies. TheB. plantaginea leaves that are consumed contain 9–22% iridoid glycosides, composed mainly of catalpol and catalpol esters, while larvae from the same plants contain 6–18% iridoids, mainly catalpol and no esters. Field-collected adult butterflies contain 0.5–4.3% iridoids. Laboratory-reared adults secrete iridoids in the meconium upon eclosion and retain similar amounts. The adult and meconium iridoid content is considerably lower than in the larvae, and metabolism in the pupal stage may be occurring.This work was supported by grant CHE-8521382 from the National Science Foundation. Paper 13 in the series Chemistry of the Scrophulariaceae. Paper 12: G.N. Belofsky and F.R. Stermitz,J. Nat. Prod. 51:614–616, 1988.     

气体膜分离技术在煤清洁化利用中的应用

归纳分析了燃煤电厂减排CO2的途径,以煤气化为核心的多联产系统具有提高燃煤利用效率和减排CO2的最大潜力。CO2的分离是未来零排放火电厂所面临的主要挑战之一,在CO2的各分离技术中,膜分离法对电厂效率影响最小。无机膜在涉及高温的分离过程中具有有机高分子膜所无法比拟的优势,为使回收的CO2达到理想的纯度,一方面应开发性能更好的无机膜材料,另一方面还应把膜法和其它有关分离技术进行优化集成。     

Floodplain nutrient and sediment dynamics on the Kent Stour

Floodplain land use is currently of concern. Agri‐environmental policy favours grass over arable agriculture, while urban development is deemed unsuitable. The role of meadowland requires evaluation because it exhibits a potential to deliver environmental goods beyond flood detention and habitat creation; it has the potential to take up particular elements and trap sediment. This is particularly important where there is eutrophication of water from agriculture and wastewater and also physical degradation of the channel and floodplain. In this study, carbon (C), nitrogen and phosphorus (P) status and sediment deposition at typical locations on a southern English floodplain were investigated. It is concluded that C sequestration could be significant and there is sediment trapping during times of flood but further P accumulation in the topsoil of grazing land is limited. It is concluded that nutrient loading of the river from sewage effluent and from agriculture is best prevented at source.     

Carbon sequestration in willow (Salix spp.) plantations on former arable land estimated by repeated field sampling and C budget calculation

Short rotation coppice (SRC) plantations are of interest as producers of biomass for fuel, but also as carbon (C) sinks to mitigate CO₂ emissions. Carbon sequestration in biomass and soil was estimated in 5-year-old replicated SRC plantations with willows (Salix spp.) on former arable land at five sites in Sweden. Total standing C stocks, i.e. C stored in woody biomass above- and belowground, fine root standing crop, litter, and soil organic carbon (SOC) were estimated by repeated field sampling and C budget calculation.Overall, the SRC willow plantations represented a C sink after five years. Estimated increase of total standing C stock was 15% on average compared to pre-planting conditions. There was no change in SOC when including all sites. Analyses within sites revealed a decrease in SOC at one site, although the decrease was compensated for by C stored in willow biomass. After removal of stem biomass, C in other plant pools was sufficient to compensate for the SOC decrease. Remaining C in stumps, stool, and coarse roots was estimated at ca 20% of stem C.There was a discrepancy between SOC sequestration rates from soil sampling and C budget calculation, −2.1–1.0 and 0.15–0.45 Mg ha⁻¹ y⁻¹, respectively. Mineralization of old organic material from previous land-use and input to SOC from understory vegetation were not included in the calculations, which may explain part of the differences. The importance of understory litter in C budgets for young plantations was apparent, as it comprised 24–80% of aboveground litter C.     

Study of Parameters Affecting Enhanced Coal Bed Methane Recovery

Abstract

Laboratory and field scale trials conducted so far indicate that injection of CO₂ and N₂ into deep coalbeds has the potential to enhance coalbed methane (ECBM) recovery while simultaneously sequestering CO₂. The work has identified that the fundamental processes involved in CO₂ sequestration/CBM recovery in deep coalbeds are not fully understood and further research is needed to advance this technology. ECBM is affected by several parameters; prominent among them are coal characteristics, in-situ conditions prevailing in deep coalbeds, and changes arising from the interaction of coal with various fluids. These parameters do not act independently, thereby making it difficult to isolate their impacts separately. An attempt has been made in this article to classify these parameters and understand their role in ECBM. Past work in this area is reviewed and the future work that is critical for an improved understanding of ECBM recovery is discussed.     

A Simulation Study of CO2 Sequestration in the Arno River Plain (Tuscany,Italy)

We present a geochemical model for the sequestration of anthropogenic CO₂ (from hypothetical hydrocarbon-based H₂ production) consequent to the theoretical injection of gas beneath the River Arno plain, near the city of Pisa, Italy. The potential reservoirs for gas disposal are of two different types: dolostones or sandstones. The model predicts the sandstones to be the best reservoirs because CO₂ sequestration in these rocks can occur via the deposition of solid carbonates. On the contrary, the injection of gas into the dolostone could generate gas accumulation and high gas pressures (50–100 atm) that could possibly promote rock fracturing and gas leakage in these shallow (500–1000 m depth) reservoirs. The best sites for gas disposal are therefore located west of the town of Pisa, along the coastal plain.     

多孔介质中CO2-CH4水合物置换的影响因素及强化机理研究进展

天然气水合物因其储量巨大、清洁无污染而成为未来最具潜力的清洁能源之一，CO₂置换法可实现天然气水合物的安全开采和温室气体的地层封存。然而，多孔介质中CO₂-CH₄水合物的置换过程存在反应周期长、速率慢、效率低等特点，已成为制约天然气水合物高效开采的瓶颈问题。本文全面综述了多孔介质体系中CO₂-CH₄水合物的置换特性，分析了CO₂-CH₄水合物的置换机理及其动力学过程。在此基础上，详述了不同因素对多孔介质中CO₂-CH₄水合物置换效率的影响规律及强化机理，包括热刺激、置换压力、小分子气体、化学添加剂等的作用机理及其规律。最后指出了多孔介质体系中CO₂-CH₄水合物置换过程强化技术存在的不足和未来的发展方向。对多孔介质体系中CO₂-CH₄水合物置换过程的强化机理及其动力学机制的认识仍需进一步研究。     

Characterization of water gas shift reaction in association with carbon dioxide sequestration

The characteristics of a water gas shift reaction (WGSR) in association with carbon dioxide sequestration under the effects of a high-temperature catalyst (HTC) and a low-temperature catalyst (LTC) are studied experimentally. With the condition of fixed residence time (0.1 s) for the reactants in the catalyst bed, it is found that the reaction behaviors with the HTC are inherently different from those with the LTC. Specifically, for the WGSR with the HTC, the reaction can be divided into a rapid growth regime, a progressive growth regime and a slow growth regime with increasing reaction temperature or steam/CO ratio. With regard to the WGSR with the LTC, three different regimes are also exhibited; however, they consist of a rapid growth regime, a progressive decay regime and a growth-frozen regime. According to the aforementioned characteristics, proper or better operation conditions using the HTC and the LTC for the application of fuel cells are suggested. When the product gas passes through a Ca(OH)₂ solution, the obtained results reveal that CO₂ removal efficiency increases with increasing solution concentration or steam/CO ratio for both the HTC and the LTC used in the WGSR.