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101.
制备了邻菲口罗啉化学修饰碳糊电极,在含噻吩甲酰三氟丙酮的HAc-NaAc体系中,Co(Ⅱ)离子经化学富集在电极表面上形成三元络合物.采用2.5次微分伏安法测定痕量Co(Ⅱ)离子.Co(Ⅱ)浓度在8.0×10-9~7.0×10-7mol·L-1范围内与阳极溶出峰峰高成良好的线性关系,检出限达1.2×10-9mol·L-1.电极用于水样中钴的测定,结果令人满意.  相似文献   
102.
以石油焦为活性炭原料,运用化学活化法制备了超级电容器用高比表面积活性炭。利用SEM和BET对实验制备的活性炭进行了分析和表征。以实验制备的活性炭为超级电容器电极材料,利用恒流充放电测试对其电容特性进行了研究。结果表明,实验研制的活性炭的比表面积为1674m2/g,中孔含量达到40%,在10mA/cm2的电流密度下其比容达到285F/g,而且基于实验研制的活性炭的超级电容器具有低内阻和良好的功率特性。  相似文献   
103.
为了提升农林废弃物在储能领域的高附加值利用,该研究以杉木屑为原料,磷酸三聚氰胺为磷、氮源,基于冷冻NaOH/硫脲体系溶解木质原料中纤维素,通过一步热解制备氮、磷、硫共掺杂多孔炭,并考察活化温度、NaOH/杉木屑质量比和冷冻条件对多孔炭结构及电化学性能的影响。通过X射线光电子能谱(XPS, X-ray photoelectron spectroscop )和比表面积分析仪(BET,Brunauer-Emmett-Teller)研究多孔炭的表面结构和孔隙结构;采用循环伏安(CV,cyclic voltammetry)、恒流充放电(GCD,galvanostatic charge/discharge)和交流阻抗(EIS,electrochemical impedance spectroscopy)等测试手段表征其电化学性能。研究结果表明:随着活化温度和NaOH/杉木屑质量比的增加,多孔炭的表面积、全孔孔容和比电容呈现先增加后减小的趋势;冷冻条件和磷酸三聚氰胺的加入可以增加多孔炭的比表面积和全孔孔容,提升电化学性能。当活化温度900 ℃,NaOH/杉木屑质量比为1.2时,制备的氮、磷、硫共掺杂多孔炭的比表面积为2 048 m2/g,全孔孔容为1.655 cm3/g,介孔率为99.7%,氮、磷、硫的含量为3.41%、0.29%、1.40%。三电极体系下、6 mol/L KOH电解液中,当电流密度0.5 A/g时,比电容可达261 F/g。用NPS-900-1.2组装的对称超级电容器5 A/g电流密度条件下,比电容值为108 F/g,循环5 000次后库伦效率接近100%,电容保持率为92%。对称的超级电容器功率密度为248 W/kg时,能量密度可达17.2 Wh/kg。该研究为农林废弃物制备高性能超级电容器提供了参考依据。  相似文献   
104.
The rate of oxidation of peat soils is highly seasonal and varies with temperature and soil moisture content. Large variations in soil moisture content result in wet–dry cycles that can enhance peat degradation. Water‐table management plays a crucial role in controlling and damping the effect of these environmental factors. However, maintaining high ditch water levels in fields bounded by ditches does not guarantee a high field groundwater level. The effect of installing subsurface irrigation at different spacings on water table elevation was studied in a low‐lying peat grassland. The water table elevation data were compared against values predicted with a water balance model. In addition, greenhouse experiments were carried out on undisturbed soil core samples collected from the peat grassland as well as a low‐lying peatland under intensive arable faming to measure CO2 evolution under different water regimes. The field data from the peat grassland suggest that sub‐irrigation spacing as low as 10 m is necessary during summer periods to maintain groundwater levels similar to those in the ditches. Over the same period of observation, the difference in water level between the ditches and the non‐irrigated fields is as high as 0.7 m. Modelled outputs are in good correlation with the field observations, and demonstrate that simple water balance models can provide an effective tool to study the effect of water management practices and potential changes in subsurface conditions, climate and land use on water‐table levels. The measurement of CO2 emission from undisturbed peat soil columns shows that the rate of oxidation of soil organic matter from peat soils is highly seasonal and that drainage exacerbates the rate of peat mineralization.  相似文献   
105.
The large scale conversion of extensive swidden agriculture to intensive market oriented production of maize in upland areas of South East Asia is a cause of environmental concern. This study investigates how intensive maize cultivation affects soil quality in an upland area of Northern Thailand by comparing commonly used indicators of soil quality in soils from maize fields used at various intensities. Relations between these indicators and concentration of permanganate oxidizable carbon (Pox‐C) – a low cost proxy for soil quality – are also examined. The extent, type and drivers of land use changes between 2002 and 2012 are investigated by classification of high resolution satellite images, interviews, participatory mapping and questionnaires. We document a widespread change from traditional swidden agriculture to intensive cultivation of maize that is mainly brought about by economcic and political drivers. We show that the concentration of Pox‐C in the top soil of the maize fields is closely related to common indicators of soil quality and to farmers' perceptions of soil quality. Most of the other soil quality indicators are negatively – albeit not significantly – related to intensity of maize cultivation. There is a strong negative correlation between intensity of maize cultivation and concentration of Pox‐C in the upper 5 cm of the soil where the Pox‐C concentration declines with a rate of 40 mg year under maize−1. We conclude that Pox‐C is a sensitive indicator of effects of land use intensity on the soil and a useful integrative measure of soil quality. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
106.
Abstract. Field margins are a valuable resource in the farmed landscape, providing numerous environmental benefits. We present a preliminary analysis of the carbon mitigation potential of different field margin management options for Great Britain, calculated using data from long-term experiments and literature estimates. The carbon sequestration potential of the individual options investigated here varies from 0.1 to 2.4% of 1990 UK CO2-C emissions, or 0.7–20% of the Quantified Emission Limitation Reduction Commitment (QELRC). The scenarios investigated covered three possible margin widths and options for the management of margins at each width (viz. grass strips, hedgerows and tree strips). Scenarios involving margin widths of 2, 6 or 20 m would require approximately 2.3, 6.7 or 21.3% of the total arable area of Great Britain, respectively. Scenarios including tree strips offered the greatest potential for carbon sequestration, since large amounts would be accumulated in above-ground biomass in addition to that in soil. We also accounted for the possible impacts of changed land management on trace gas fluxes, which indicated that any scenario involving a change from arable to grass strip, hedgerow or tree strip would significantly reduce N2O emissions, and thus further increase carbon mitigation potential. There would also be considerable potential for including the scenarios investigated here with other strategies for the alternative management of UK arable land to identify optimal combinations. We assumed that it would take 50–100 years for soil carbon to reach a new equilibrium following a land use change. More detailed analyses need to be conducted to include environmental benefits, socioeconomic factors and the full system carbon balance.  相似文献   
107.
中国正在不断推进农村绿色经济转型与乡村振兴战略,田园综合体等各种以生态环境为导向的农业开发模式是乡村振兴建设的新途径,驱动农业固碳减排的同时,也带动着传统农业不断向现代农业发展的转变。以EOD(Ecology-Oriented-Development,生态环境导向的开发)模式的上海市金山区枫泾镇郊野村庄田园综合体为研究对象,在现场调研与数据统计的基础上,分析了园区内的碳输入和碳输出以及碳在园内各区域间的流动和储积;同时,根据碳源和碳汇清单和估算结果,分析了田园综合体各区的碳平衡特点。结果显示,上海市金山区郊野村庄田园综合体2021年碳平衡表现为净碳汇区,净碳汇量为152.09 tC,其中排放量为588.79 tC,碳固定量为740.88 tC。田园综合体内,作物种植区通过低碳有机种植模式成为净碳汇量最大的区域,净碳汇量185.76 tC;水产养殖区通过高效的水草多级循环利用模式净碳汇量达62.20 tC;高空间利用率的立体农业区因农肥的碳排放量大表现为碳源区,净碳汇量为-10.81 tC;生产生活区是最大的碳源区,净碳汇量达-85.05 tC,人类文旅活动是其中最大的碳排放源。分析结合该田园综合体的碳流动,提出了发展高物质循环利用率、高空间利用率、低碳有机种植模式和农业科学管理四个农业降碳增汇的方向。  相似文献   
108.
Abstract: Will future transportation carbon dioxide (CO2) emissions per capita in Asia Pacific economies follow historical trends of the now developed world? Evidence to date is inconclusive. A comparison at similar income levels (purchasing power parity) between recent emissions in Asia Pacific countries and historical emissions in developed countries suggests diverging patterns. (A) High‐income Asia economies (Japan, Hong Kong and Singapore –‘low emitters’) exhibit lower emissions than a selected sample of seven developed countries (United States, Australia, France, the Netherlands, Italy, Sweden and United Kingdom). (B) Another set of Asian countries (South Korea and Taiwan –‘medium emitters’) follow the emissions trends of European countries, which are lower than those of Australia and the United States. (C) A third Asian group (Malaysia and Thailand –‘high emitters’) exhibit emission trends comparable to that of Australia. We describe these trends, examine their causes and extrapolate likely futures for emissions in low‐income Asia Pacific economies (China, Indonesia, Philippines and Vietnam). Although such predictions are speculative, the available evidence suggests that road CO2 emissions for Indonesia, the Philippines and Vietnam will follow those of the third group (high emitters), while those for China may follow either Group B or Group C.  相似文献   
109.
长期以来都是通过测定四氯化碳荷量或吸苯率,来评价用于气相吸附活性炭的吸附性能。由于四氯化碳是剧毒试剂,苯是致癌物质、所以本文改用环己烷作为吸附质,通过测定各种活性炭对环己烷的吸附等温线,详细讲话他环己烷荷量作为评价活性炭吸附性能的条件。并介绍了快速测定活性炭对环己烷的吸附荷量的迎头色谱穿透曲线法。  相似文献   
110.
Overgrazing contributes to rangeland degradation altering plant community composition, erosion and biodiversity. Little unanimity in the literature exists on the effects of livestock grazing on soil carbon and biodiversity, in part, due to uncontrolled grazing pressure from native and feral animals. Paired paddock contrasts at three, long‐term (>8 years) study locations in the southern Australian rangelands were used to examine the effects of managing grazing intensity through the use of exclusion fencing and rotational grazing on soil organic carbon (SOC), soil nitrogen (TN), ground cover and biodiversity (flora and invertebrates). Grazing management had no effect on SOC or TN on grey soils (Vertisols), but for red soils (Lixisols), significantly higher levels of SOC were found for both the 0 to 5 and 5 to 10‐cm soil depths (0·3% and 0·27% respectively) and associated with increased TN. We found strong and consistent relationships among SOC and higher perennial (p < 0·001), higher litter (p < 0·05) cover and close proximity to trees (p < 0·05). Managing grazing intensity resulted in significantly higher perennial ground cover (p < 0·001) on Vertisols (8·9 to 11%) and Lixisols (12·5 to 15%) and higher plant diversity (both native and exotic) but negatively impacted invertebrate diversity, indicating trade‐offs between production and resources. We provide evidence that the effects of grazing management on SOC are mediated by ground cover and increased organic matter supply and/or reduced soil carbon redistribution (erosion), which indicates that the management of grazing intensity may provide a tool to avoid soil carbon loss in rangelands. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
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