新安江水库二氧化碳排放的时空变化特征

新安江水库是我国华东地区最大的水库,面积580 km2,平均深度30 m,水库水体处于中贫营养状态.为了研究新安江水库中CO_2排放的时空变化特征,2014年12月至2015年12月采用静态浮箱法收集水库表面以分子扩散方式排放的CO_2,使用气相色谱仪分析CO_2浓度.结果表明,新安江水库CO_2排放通量从上游入库河流[(120.39±135.41)mg·(m~2·h)~(-1)]至库区主体[(36.65~61.94)mg·(m~2·h)~(-1)]呈下降趋势,而大坝下游河流中CO_2排放通量[(1 535.00±1 447.46)mg·(m~2·h)~(-1)]显著增加,约分别是上游入库河流和库区主体的13倍和25~42倍.但随着与大坝距离增加,大坝下游河流中CO_2排放通量显著下降,如7 km处的CO_2排放通量仅为出库水体处的20%.在库区主体中,CO_2排放通量具有明显的季节变化:CO_2排放通量在秋、冬季时为正值,最大值出现在冬季(12月或1月),说明此时库区表层水体是CO_2排放源;而CO_2排放通量在春、夏季为负值,最小值出现在春季(3、4或5月),说明此时库区表层水体是CO_2吸收汇,这可能与春、夏季时水体中藻类繁殖有关.所以,在调查水库表面CO_2排放时,应对水库的上游入库河流、库区主体和坝下河流进行全面长期的观测,才能避免低估水库中CO_2排放总量.     

黄土区典型小流域矿物化学风化及碳汇效应

黄土中蕴含了巨大的碳库,黄土中碳的转移对区域乃至全球碳循环具有重要影响。本文选择山西省临县一典型黄土小流域青凉寺沟流域进行调查分析,研究黄土水的化学特征及离子来源,分析黄土矿物的溶蚀过程及碳汇效应,并利用正演模型和水化学方法估算不同矿物的离子贡献比例及流域碳汇通量。结果发现,研究区黄土化学成分的含量由高到低依次为SiO_2、Al_2O_3、CaO、Fe_2O_3、MgO、K_2O、Na_2O,表现出贫SiO_2、Fe_2O_3,富CaO、MgO的特点;黄土水的pH呈中性偏碱,阴离子主要以HCO_3~-为主,阳离子以Na~+为主,水化学类型为重碳酸-钠型(HCO_3~--Na~+),水化学组成与黄土的化学组成相对应;流域内不同端元离子来源贡献计算结果表明,大气沉降、人类输入、蒸发盐矿物、硅酸盐矿物和碳酸盐矿物化学风化贡献的溶解物质分别占总溶解物质的1. 66%、6. 32%、10. 38%、62. 23%、19. 31%;黄土区长时间的水-矿物作用是硅酸盐矿物溶解贡献占主导的主要原因,阳离子置换反应、土壤-盐分浸出与蒸发以及人类输入对硅酸盐矿物溶解也有一定的贡献;受黄土区相对低温少雨的影响,黄土矿物的平均化学风化速率较低,为9. 31 t/(km~2·a),低于全球岩石的化学风化速率平均值36 t/(km~2·a),但是其消耗大气CO_2的速率较高,约为6. 34 t CO_2/(km2·a),明显高于同纬度三川河岩溶流域的碳汇速率(5. 28 t CO_2/(km~2·a));利用水化学径流法计算的青凉寺沟黄土小流域的矿物化学风化的大气CO_2消耗量为0. 18×10~4t/a,为中国黄土区大气CO_2消耗量的估算提供基础数据。     

室内挥发性有机化合物综合散发量及其特征

基于室内建筑污染源散发特性与汇效应机制分析,给出了建筑室内挥发性有机化合物（VOCs）综合散发量的计算模型,并进一步分析了材料内部扩散系数、气固界面分离系数和材料厚度对室内VOCs综合散发量的影响特征。研究结果表明,在近似稳定阶段室内VOCs综合散发量会随源材料内部扩散系数的增大而升高,而随源材料气固界面分离系数和材料厚度的增加而减小,且以源材料内部扩散系数的影响最为显著;同时,室内汇表面三类参数的增大均会使室内VOCs综合散发量降低;此外,在相同的环境参数条件下,室内VOCs综合散发量会因室内汇效应的存在而减小。     

生物炭的环境效应及其应用的研究进展

作为新型环境功能材料,生物炭以其优良的环境效应和生态效应成为环境科学等学科研究的前沿热点.本文介绍了生物炭结构和基本特性,对其在土壤肥力改良、碳的增汇减排以及受污染环境修复的应用和机理方面的研究进展进行了综述,并扼要分析了生物炭研究的前景和方向,为生物炭技术的应用和推广提供一定的思路.     

Use of fecundity measured directly throughout the breeding season to test a source-sink demographic model

Populations of landbirds (bird species that occupy terrestrial habitats for most of their life cycle) are declining throughout North America (north of Mexico) and Europe, yet little is known about how demography is driving this trend. A recent model of 5 geographically separated populations of Cerulean Warblers (Dendroica cerulea) that was based on within-season sampling of nest survival and fledgling success shows that all populations are sinks (annual reproduction is consistently less than annual adult mortality). I tested this indirect model by directly measuring fecundity (number of female fledglings/female) during the breeding season for 2 years in a Cerulean Warbler population occupying a mature forest in southwestern Michigan (U.S.A.) I determined territories of male birds on the basis of male plumage characters and phases of the nesting cycle (2007) and on uniquely color-banded males (2008). I transferred locations of identified males to topographic maps. I counted all fledglings in territories from May to July each year. The model I tested may apply only to single-brooded species; therefore, I searched the literature to estimate the percentage of single-brooded species in North America. The breeding season of Cerulean Warblers was short- nearly all nests were initiated from mid-May to late June. Nest predation and brood parasitism were primary and rare causes of nest failure, respectively. Significantly fewer Cerulean Warblers fledged from parasitized than from nonparasitized nests. Fledgling survival required to maintain the population size was well above previously published values for Neotropical migrants. Single-brooded species comprise 62% of North American breeding bird species for which the number of broods per year is known; I believe my results may apply to these species. The consistency between identification of populations as sources or sinks on the basis of either model estimates or direct measurements suggests that a demographic model relying on within-season sampling of fecundity is adequate to determine population status of single-brooded avian populations. In addition, on the basis of results of previous studies, annual adult survival rate of the Cerulean Warbler is typical of parulid warblers that are not declining. Thus, low fecundity, here determined with different quantitative methods, can drive status of landbird species with high-observed survival.     

湿地生态系统碳汇与碳源过程的控制因子和临界条件

湿地生态系统由于其自身的结构组分特征,已成为地球表层系统中最为重要的碳汇。但是近年来对于湿地系统的不合理开发利用、降水减少等原因使其碳＂汇＂功能减弱,湿地的碳蓄积能力下降且有转变为碳＂源＂的趋势。文章从湿地生态系统的水份、植物类型、土壤厚度、微生物（底物、pH、温度、氧化还原条件）等方面总结了影响湿地碳汇/源过程的控制因子和临界交替条件。湿地水位的高低决定湿地的氧气环境,与甲烷产生量成正相关,但却与二氧化碳产生量有一定的负相关关系。湿地植物通过通气组织与根系分泌物等影响湿地碳的吸收与排放通量,湿地植株的高度、覆盖率等也是影响湿地作为碳汇与碳源的重要因素。不同深度土层由于其产甲烷菌、甲烷氧化菌等微生物活性不同导致各个土层碳吸收、排放通量的差异,通常浅层土壤中的CO2、CH4的产生率高于深层土壤。微生物的活跃程度直接影响到湿地碳的吸收与排放,影响活跃程度的因素包括湿地底物、pH、温度与氧化还原条件等。湿地底物浓度的增加会在一定程度上提高甲烷的产生率,中性或者是弱碱性环境是产甲烷菌的最适宜条件,在一定范围内温度越高,甲烷产生量越大,而温度对于二氧化碳的影响则是通过改变光合作用来实现。氧化还原电位与甲烷产生量成负相关关系,-150 mV是产甲烷菌产生甲烷的最高电位。总体上,由于湿地生态系统的复杂性和碳吸收与排放过程的复杂,以上这些因子相互作用,且在一定条件下会相互转化。最后针对如何充分发挥湿地生态系统的碳＂汇＂功能,控制湿地向碳＂源＂转化的条件措施方面进行了讨论,包括间歇灌溉、种植多年生草本植物或木本植物等来增强湿地的固碳能力。     

Modeling of Fluid Flow and Heat Transfer in a Copper Based Heat Sink Application

With the trend towards increasing the speed of processors in smaller sized of computers, there has been considerable interest in heat sink technologies with higher levels of performance and further miniaturization. This work addresses the fundamental heat transfer augmentation question of how to design a copper-based heat sink, when the overall dimensions of the bottom plate or fan are specified. A three-dimensional finite-volume model has been developed and applied to investigate flow and conjugate heat transfer in the copper-based heat sink. The model was produced with the commercial program FLUENT, which allows this nonlinear, highly turbulent problem to be simulated using the k-ε turbulence model. The theoretical model developed is validated by comparing the model predictions with available experimental data. The thermal performance and temperature distribution for the heat sink were analyzed and a procedure for optimizing the geometrical design parameters based on less space occupation and more efficient heat transfer coefficient is presented. Several design examples with different types of cooling methods and manufacturing processes have been analyzed. The reliability and effectiveness in heat spreading of those has been compared. It has been shown that the copper-based heat sink with louvered fins (case No.3) has an optimum design configuration.     

Is the availability of different nutrients a critical factor for the impact of bacteria on subterraneous carbon budgets?

Bacteria thriving in underground systems, such as karsts, adapt to use a variety of nutrients. Most of these nutrients derive from superficial processes. This study shows that bacteria are able to differentially induce carbonate precipitation or dissolution depending on the availability of nutrients for growth. Different bacterial strains isolated from caves, representing the most common components of these microbial communities, were cultured with different carbon and nitrogen sources (e.g., acetate, glucose, peptone, humic acids) and induced changes in pH were measured during growth. Carbonate can either precipitate or dissolve during bacterial growth. The induction of carbonate precipitates or their dissolution as a function of consumption of specific carbon sources revealed the existence of an active nutrient cycling process in karsts and links nutrients and environmental conditions to the existence of a highly significant carbon sink in subterraneous environments.     

对内蒙古发展低碳经济的思考

内蒙古经济发展具有典型的高消耗、高污染、高排放特征,节能减排空间很大,同时内蒙古新能源储量丰富、森林碳汇能力较强。发展低碳经济应是内蒙古实现经济可持续发展的战略选择,具体可以通过推进产业机构优化升级,提高资源、能源利用效率;通过发展煤炭清洁利用技术和新能源等清洁和可再生能源,着力改善能源结构;通过增加森林草原碳汇、尽快启动实施碳交易来实现经济的可持续发展。     

对内蒙古发展低碳经济的思考

内蒙古经济发展具有典型的高消耗、高污染、高排放特征,节能减排空间很大,同时内蒙古新能源储量丰富、森林碳汇能力较强。发展低碳经济应是内蒙古实现经济可持续发展的战略选择,具体可以通过推进产业机构优化升级,提高资源、能源利用效率;通过发展煤炭清洁利用技术和新能源等清洁和可再生能源,着力改善能源结构;通过增加森林草原碳汇、尽快启动实施碳交易来实现经济的可持续发展。