Effects of dissolved inorganic carbon and nutrient levels on carbon fixation and properties of Thermosynechococcus sp. in a continuous system

The concept of CO₂ chemo-absorption by sodium hydroxide in a wet scrubber followed by microalgae cultivation was used as a means to reduce the major greenhouse gas. A thermophilic and alkaline tolerable cyanobacterium named Thermosynechococcus CL-1 (TCL-1) was cultivated in continuous system, with a carbonate-bicarbonate buffer as carbon source. The effects of dissolved inorganic carbon (DIC_in) and nutrient levels in influent on cell mass productivity, DIC removal efficiency, and alkaline solution regeneration by TCL-1 were investigated. The results show the highest cell mass productivity reaches 1.7 g L⁻¹ d⁻¹ under the highest DIC and nutrients level. Conversely, the best regeneration of alkaline solution proceeds from pH 9.5 to 11.3 under the lowest level. In addition, the highest ΔDIC (DIC consumption) and DIC removal efficiency are 42 mM and 43% at 113.2 and 57 mM DIC_in, respectively.     

基于生态系统服务功能理论的生态足迹模型研究

由于传统Wackemagel and Rees生态足迹模型仅研究人类对资源的需求和生态系统供给的生物生产能力之间的差距,忽略了生态系统的其它功能,无法体现生态系统的整体性.本文以传统生态足迹模型为基础,引入生态系统服务功能价值理论,提出了基于生态系统服务功能价值的生态足迹模型.该模型以生态生产性土地的生态服务功能价值评估为基础,改进传统生态足迹模型中均衡因子和产量因子的计算方法.采用生物生产性土地的综合生态系统服务功能的价值当量因子计量生态足迹模型中的均衡因子,采用生态系统单元的单位面积生态系统服务功能价值与全国该生态系统单元的平均价值的比值表示产量因子.改进后的生态足迹模型既反映了区域人类资源消费对生物生产性土地的占用,又反映了区域人类资源消费对生态系统服务功能的使用,较科学的体现了生态系统的整体性.同时,本文以大连市2005年社会经济统计数据为基础,运用改进的生态足迹模型对大连市的生态足迹进行了测算,对研究模型进行了检验.     

资源环境对南京市经济发展的“增长阻尼”

由于土地与其他自然资源的限制,经济增长速度相比没有限制情况下降低的现象,即为资源对经济增长的阻尼效应。本文将土地资源与生态环境影响因素合并,利用生态足迹模型解释资源环境复合要素,对传统的阻尼模型进行修正,定量测算资源环境对南京市经济发展的增长阻尼。结果表明,南京市经济发展迅速,土地资源和生态环境对经济发展产生了较为明显的制约作用,其对经济发展的增长阻尼为0.03611。充分发挥资本对资源环境的替代作用,合理利用土地资源,优化产业结构,降低人口的增长率是实现南京市经济可持续发展的基本途径。     

环鄱阳湖区水足迹的动态变化评价

水足迹模型是计量水资源承载力的一个较新颖且日趋成熟的方法。水资源状况对鄱阳湖区生态系统的平衡、稳定以及生态系统良性循环有着重要意义。将水足迹模型运用于环鄱阳湖区进行实证研究,通过计量模型计算出环鄱阳湖区1989~2008年水足迹的时间序列值,并评价其承载状况。结果显示,近20 a来,环鄱阳湖区的水足迹需求由1989年的735亿m3增加至2008年的110亿m3,呈现出波动上升趋势。至今为止水足迹未超载,但盈余空间呈减少趋势。最后从优化水资源利用、倡导绿色消费和促进区域间贸易交流等降低水足迹的需求和增大水足迹供给的角度提出了提高水足迹承载力的对策。进而从水足迹的角度为环鄱阳湖区提高生态系统承载力提供理论依据,促进江西省鄱阳湖生态经济区的建设     

环鄱阳湖区生态足迹与经济产业发展关系的实证研究

生态足迹是衡量区域生态承载力状况的一个较成熟的方法。首先通过计量模型计量出环鄱阳湖区1989~2008年生态足迹的时间序列值,并评价了其承载状况。结果显示,近20 a来,环鄱阳湖区的生态足迹从1989年的1 401万hm2提升到2008年的3 145万hm2,呈波动上升趋势;生态承载力从1989年的6 255万hm2上升至2008年的7 215万hm2,基本上呈不断上升的变化趋势。环鄱阳湖区生态承载力能满足区域的生态足迹需求,表现出生态盈余,但其盈余空间从1989年的4 220万hm2降低至2008年的4 069万hm2,总体上呈减少趋势。其次,将生态足迹与区域的经济总量和三次产业进行协整分析后得出,生态足迹的GDP弹性为035,其三次产业的弹性分别为0668 3、0011、0049 4。最后,从加强土地管理、强化区域贸易、改变消费方式、完善产业体系等角度提出了协调环鄱阳湖区生态环境与经济产业发展的政策措施     

Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan

Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.     

Selective redox degradation of chlorinated aliphatic compounds by Fenton reaction in pyrite suspension

Selective redox degradation of chlorinated aliphatics by Fenton reaction in pyrite suspension was investigated in a closed system. Carbon tetrachloride (CT) was used as a representative target of perchlorinated alkanes and trichloroethylene (TCE) was used as one of highly chlorinated alkenes. Degradation of CT in Fenton reaction was significantly enhanced by pyrite used as an iron source instead of soluble Fe. Pyrite Fenton showed 93% of CT removal in 140 min, while Fenton reaction with soluble Fe(II) showed 52% and that with Fe(III) 15%. Addition of 2-propanol to the pyrite Fenton system significantly inhibited degradation of TCE (99% to 44% of TCE removal), while degradation of CT was slightly improved by the 2-propanol addition (80-91% of CT removal). The result suggests that, unlike oxidative degradation of TCE by hydroxyl radical in pyrite Fenton system, an oxidation by the hydroxyl radical is not a main degradation mechanism for the degradation of CT in pyrite Fenton system but a reductive dechlorination by superoxide can rather be the one for the CT degradation. The degradation kinetics of CT in the pyrite Fenton system was decelerated (0.13-0.03 min⁻¹), as initial suspension pH decreased from 3 to 2. The formation of superoxide during the CT degradation in the pyrite Fenton system was observed by electron spin resonance spectroscopy. The formation at initial pH 3 was greater than that at initial pH 2, which supported that superoxide was a main reductant for degradation of CT in the pyrite Fenton system.     

Carbon isotope signature of dissolved inorganic carbon (DIC) in precipitation and atmospheric CO2

This paper describes results of chemical and isotopic analysis of inorganic carbon species in the atmosphere and precipitation for the calendar year 2008 in Wroc?aw (SW Poland). Atmospheric air samples (collected weekly) and rainwater samples (collected after rain episodes) were analysed for CO₂ and dissolved inorganic carbon (DIC) concentrations and for δ¹³C composition. The values obtained varied in the ranges: atmospheric CO₂: 337-448 ppm; δ¹³C_CO2 from −14.4 to −8.4‰; DIC in precipitation: 0.6-5.5 mg dm⁻³; δ¹³C_DIC from −22.2 to +0.2‰. No statistical correlation was observed between the concentration and δ¹³C value of atmospheric CO₂ and DIC in precipitation. These observations contradict the commonly held assumption that atmospheric CO₂ controls the DIC in precipitation. We infer that DIC is generated in ambient air temperatures, but from other sources than the measured atmospheric CO₂. The calculated isotopic composition of a hypothetical CO₂ source for DIC forming ranges from −31.4 to −11.0‰, showing significant seasonal variations accordingly to changing anthropogenic impact and atmospheric mixing processes.     

Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41 kg N ha⁻¹ yr⁻¹ as NH₄NO₃ to the ambient 9 kg N ha⁻¹ yr⁻¹ in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO₃ in runoff partially offset the decreasing concentrations of SO₄ and slowed ecosystem recovery from acid deposition. From 1990-2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42-59 g g⁻¹.     

Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands.