Evidence of mid-Holocene climate instability from variations in carbon burial in Seneca Lake, New York

The amounts and types of carbon delivered to the sediments Seneca Lake, New York, have varied since the middle Holocene. Concentrations of CaCO₃ first fluctuate between 14 and 6% around 7 ka before decreasing erratically until about 5 ka and then remain 2% in younger sediments. Because the amount of calcite that precipitates in hard-water lakes is related to summertime thermal stratification, the carbonate fluctuations suggest that cyclic strengthening and weakening of seasonality at intervals of about three centuries accompanied the end of the Holocene Hypsithermal in northeast North America. Organic C/total N values record short, decade-long intervals of enhanced delivery of land-plant material during episodes of wetter climate that are independent of the temperature variations. Higher organic ¹³C values indicate that recent fertilization of lake waters from soil disturbance and land-derived runoff has increased aquatic productivity.     

The Validity of Similarity Theory in the Roughness Sublayer Above Forests

Flux-gradient relationships based upon similarity theory have been reported to severely underestimate scalar fluxes in the roughness sublayer above forests, as compared to independent flux estimates (for example, eddy covariance or energy balance measurements). This paper presents the results of a unique three-month investigation into the validity of similarity theory in the roughness sublayer above forests. Eddy covariance and flux-gradient measurements of carbon dioxide (CO²) exchange were compared above a mixed deciduous forest at Camp Borden, Ontario, both before and after leaf senescence. The eddy covariance measurements used a Li-Cor infrared gas analyzer, and the flux-gradient (similarity theory) measurements featured a tunable diode laser Trace Gas Analysis System (TGAS). The TGAS resolved the CO² concentration difference to 300 parts per trillion by volume (ppt) based upon a half-hour sampling period. The measured enhancement factor (the ratio of independent flux estimates, in this case eddy covariance, to similarity theory fluxes) was smaller and occurred closer to the canopy than in most previous investigations of similarity theory. Very good agreement between the eddy covariance and similarity theory fluxes was found between 1.9 and 2.2 canopy heights (h^c), and the mean enhancement factors measured before and after leaf senescence were 1.10 plusmn; 0.06 and 1.24 ± 0.07, respectively. Larger discrepancies were measured closer to the canopy (1.2 to 1.4 h^c), and mean enhancement factors of 1.60 ± 0.10 and 1.82 ± 0.11 were measured before and after leaf senescence, respectively. Overall, the Borden results suggest that similarity theory can be used within the roughness sublayer with a greater confidence than previously has been believed.     

新疆14C年代测定及数据集（I＊）

主要介绍新疆维吾尔自治区地震局放射性同位素碳测年实验室的１４Ｃ测年原理,样品的前处理、样品的化学制备,低水平放射性测量方法及测定年代。首次公布一批１４Ｃ年代测定数据。     

The Jakucs CO2 microanalyser—problems and remedies

This note describes simple procedural changes and corrections to gas pressure calculations for use with the Jakucs CO₂ microanalyser.     

Spectroscopic measurements of atmospheric carbon monoxide and methane. 1: latitudinal distribution

The results of spectroscopic total column measurements of CO and CH₄ at different points of the Northern and Southern Hemispheres in 1970–1985, are reported. Seasonal cycles of CO are evident for all the sites. The Northern Hemispheric long-term positive trend of CO seems to be 1.5–2% per year. In the Southern Hemisphere, temporal increasing was not detected and a possible upper limit for it is about 0.6% per year. Methane concentration in the Northern Hemisphere increases at a rate of 1.2% per year.     

植物营养元素的含量和δ~(13)C值随海拔而变化的特征及营养元素相互作用对碳同位素分馏作用的影响

为了研究植物营养元素的含量和δ~(13)C值随海拔而变化的相关关系,沿着海拔450 m的贵州茂兰至海拔1330 m的贵州安顺一线,采集和分析研究了C_3植物——小果蔷薇(R.cymosa Tratt)的叶片。分析结果表明,植物叶片中营养元素含量随着海拔的上升而产生的变化是:氮、磷和钾的含量会在增高,而钙和镁的含量却会降低。植物叶片的δ~(13)C值会增大,其变幅为 2.4‰/1000m。     

Spatial characterization of the location of potentially leaky wells penetrating a deep saline aquifer in a mature sedimentary basin

This work was motivated by considerations of potential leakage pathways for CO₂ injected into deep geological formations for the purpose of carbon sequestration. Because existing wells represent a potentially important leakage pathway, a spatial analysis of wells that penetrate a deep aquifer in the Alberta Basin was performed and various statistical measures to quantify the spatial distribution of these wells were presented. The data indicate spatial clustering of wells, due to oil and gas production activities. The data also indicate that the number of wells that could be impacted by CO₂ injection, as defined by the spread of an injected CO₂ plume, varies from several hundred in high well-density areas to about 20 in low-density areas. These results may be applied to other mature continental sedimentary basins in North America and elsewhere, where detailed information on well location and status may not be available.     

Inter-trading permanent emissions credits and rented temporary carbon emissions offsets: some issues and alternatives

Permit trading among polluting parties is now firmly established as a policy tool in a range of environmental policy areas. The Kyoto Protocol accepts the principle that sequestration of carbon in the terrestrial biosphere can be used to offset emissions of carbon from fossil fuel combustion and outlines mechanisms. Although the lack of guaranteed permanence of biological offsets is often viewed as a defect, this paper argues that the absence of guaranteed permanence need not be a fundamental problem. We view carbon emissions as a liability issue. One purpose of an emissions credit system is to provide the emitter with a means to satisfy the carbon liability associated with her firm’s (or country’s) release of carbon into the atmosphere. We have developed and here expand on a rental approach, in which sequestered carbon is explicitly treated as temporary: the emitter temporarily satisfies his liability by temporarily “parking” his liability, for a fee, in a terrestrial carbon reservoir, or “sink,” such as a forest or agricultural soil. Finally, the paper relates the value of permanent and temporary sequestration and argues that both instruments are tradable and have a high degree of substitutability that allows them to interact in markets.     

A conceptual framework and its application for addressing leakage: the case of avoided deforestation

One of the most challenging technical issues associated with project-based mechanisms is that of leakage. A conceptual framework is proposed for the identification and analysis of leakage potentially generated by a project. The categorization of leakage based on the actors responsible for their manifestation is proposed, which divides sources of leakage into primary and secondary types. It is the actors or agents responsible for the baseline activities that cause primary leakage. Secondary leakage occurs when the project’s outputs create incentives for third parties to increase emissions elsewhere. This distinction, based on the source of leakage, provides a basis for the analysis outlined in the paper. The extent and type of leakage will vary depending on the project typology and design. Using a decision tree approach, the process of identifying potential sources of leakage is demonstrated for the case study of avoided deforestation projects. If the main elements determining a baseline are properly identified and understood, in particular the ‘baseline agents’, a combination of the decision tree approach and apportioning responsibility, can assist in the quantification and monitoring of primary leakage. An analysis at the project design stage can also assist in minimizing the risk of future leakage. Econometric methods may prove more useful in analyzing secondary leakage.     

黄骅坳陷二氧化碳气成因类型及分布规律

二氧化碳气是经济价值很高且应用前景十分广阔的非烃气体。黄骅坳陷二氧化碳气有多种成因类型,即有机成因、热变质成因和壳 幔混源成因,其中前两种分布较广泛。对于不同成因的二氧化碳气,其分布控制因素有所不同。有机成因二氧化碳气主要分布于生油凹陷周围,是烃类气体的次要伴生产物,并远离大断裂分布。热变质成因二氧化碳气主要分布在深部碳酸盐岩发育、岩浆活动较强烈的地区,并在大断裂附近富集;二氧化碳的含量比有机成因的高,但比壳 幔混源成因的低。壳 幔混源成因二氧化碳气主要出现在深大断裂附近,其分布虽然局限,但纯度是最高的。二氧化碳富集的地区常常是次生溶蚀作用较强的地区,因此也是寻找深部次生优质油气储层的有利地区。