土壤中氮碳间相互作用对全球碳循环的影响(英文)

氮循环中的能量产生过程构成与全球碳循环间的重要关联。例如,氮投入土壤,一开始导致CO2排放降低。这一众所周知的效应被理解为土壤呼吸作用受到阻碍或延缓。然而,当把冗余考虑在内便知,氮投入并不使最初得到的CO2最低排放量保持不变,而是逐渐导致排放增加。土壤中硝化作用对CO2消耗过程的特异性抑制,加上铵冗余投入或乙炔作用,往往导致额外的CO2排放量。这种总自养性呼吸(GHR)与CO2净排放(NHR)之间的差就是土壤内CO2汇。土壤呼吸作用单纯由NHR产生的CO2排放量(通常情况)来决定会导致对土壤系统的曲解,特别是在氮沉降量高的地区。因此,必须重新考虑温暖区域土壤呼吸作用的"适应环境"问题。可能也需要质疑氮投入带来的"呼吸抑制"概念。无视这些过程,包括上述氮驱动下的土壤内CO2汇过程,也许会有碍于采取足够的措施来对抗气候变化。     

旅游业碳排放研究进展

全球气候变化与资源环境问题对人类可持续发展带来了巨大冲击,节能减排已成为全球社会经济和环境可持续发展的必然要求.科学分析旅游业碳排放有助于推动旅游地的旅游业及其关联产业的节能减排与可持续发展.本文概述旅游业碳排放的研究历程,分析和评述了旅游业碳排放的研究方法,然后从区域旅游和旅游业各部门的碳排放测度、旅游碳足迹、旅游业碳排放的影响、应对旅游业碳排放影响的对策等5 个方面,综述旅游业碳排放主要的研究内容.最后对中国旅游业碳排放研究提出了建议.     

中小城市家庭生活用能碳排放空间分异——以开封市为例

利用2015年开封市居民家庭生活用能的大样本问卷调查数据,采用探索性空间数据分析（ESDA）和标准差椭圆（SDE）方法,探索城市居住区家庭生活用能碳排放空间分布特征。结果表明：① 家庭生活用能碳排放存在以热点区为主的空间正相关特性,碳排放高值集聚发生在城市新建开发区和建成区向外扩张较快区域,以2000年以后新建高档商品房小区和机关事业单位家属院为主,低值集聚区则发生在建成时间长、后续开发力度小的区域,以老商品房小区和胡同社区为主;② 开封市家庭电力消耗碳排放占生活用能总碳排放的67%,但人均生活用能碳排放空间格局由供暖碳排放决定,且人均供暖碳排放空间格局又由集中供暖碳排放空间格局决定,故降低集中供暖能耗、缩小居民供暖用能差异成为居民生活用能碳减排工作的重中之重;③ 家庭经济状况、集中供暖设施分布和城市发展的空间格局是家庭生活用能碳排放空间依赖性和空间异质性形成的主要驱动因素。     

Seasonal Variations of CH_4 Emissions in the Yangtze River Delta Region of China Are Driven by Agricultural Activities

Developed regions of the world represent a major atmospheric methane(CH_4) source, but these regional emissions remain poorly constrained. The Yangtze River Delta(YRD) region of China is densely populated(about 16% of China's total population) and consists of large anthropogenic and natural CH_4 sources. Here, atmospheric CH_4 concentrations measured at a 70-m tall tower in the YRD are combined with a scale factor Bayesian inverse(SFBI) modeling approach to constrain seasonal variations in CH_4 emissions. Results indicate that in 2018 agricultural soils(AGS, rice production) were the main driver of seasonal variability in atmospheric CH_4 concentration. There was an underestimation of emissions from AGS in the a priori inventories(EDGAR—Emissions Database for Global Atmospheric Research v432 or v50), especially during the growing seasons. Posteriori CH_4 emissions from AGS accounted for 39%(4.58 Tg, EDGAR v432) to 47%(5.21 Tg, EDGAR v50) of the total CH_4 emissions. The posteriori natural emissions(including wetlands and water bodies) were1.21 Tg and 1.06 Tg, accounting for 10.1%(EDGAR v432) and 9.5%(EDGAR v50) of total emissions in the YRD in2018. Results show that the dominant factor for seasonal variations in atmospheric concentration in the YRD was AGS,followed by natural sources. In summer, AGS contributed 42%(EDGAR v432) to 64%(EDGAR v50) of the CH_4 concentration enhancement while natural sources only contributed about 10%(EDGAR v50) to 15%(EDGAR v432). In addition, the newer version of the EDGAR product(EDGAR v50) provided more reasonable seasonal distribution of CH_4 emissions from rice cultivation than the old version(EDGAR v432).     

Pyrite paragenesis and multiple sulfur isotope distribution in late Archean and early Paleoproterozoic Hamersley Basin sediments

The sulfur isotope record in late Archean and early Paleoproterozoic rocks is of considerable importance because it provides evidence for changes in early Earth atmospheric oxygen levels and potentially constrains the origin and relative impact of various microbial metabolisms during the transition from an anoxic to oxic atmosphere. Mass independently fractionated (MIF) sulfur isotopes reveal late Archean and early Paleoproterozoic sulfur sources in different pyrite morphologies in Western Australia's Hamersley Basin. Multiple sulfur isotope values in late Archean pyrite vary according to morphology. Fine grained pyrite has positive sulfur MIF, indicating a reduced elemental sulfur source, whereas pyrite nodules have negative sulfur MIF, potentially derived from soluble sulfate via microbial sulfate reduction. The Hamersley Basin δ³⁴S–Δ³³S record suggests that the extent of oxygenation of the surface ocean fluctuated through the Late Archean from at least 2.6 Ga, more than 150 million yr before the Great Oxidation Event. In the early Paleoproterozoic, there is less distinction between pyrite morphologies with respect to sulfur isotope fractionation, and pyrite from the Brockman Iron Formation trends toward modern sulfur isotope values. An important exception to this is the strong negative MIF recorded in layer parallel pyrite in Paleoproterozoic carbonate facies iron formation. This may suggest that deeper water hydrothermal environments remained anoxic while shallower water environments became more oxidised by the early Paleoproterozoic. The results of the current study indicate that sulfide paragenesis is highly significant when investigating Archean and early Paleoproterozoic multiple sulfur isotope compositions and sulfur sources.     

“7.17”西北夏季沙尘暴数值模拟

 对2005年7月17日发生在西北地区近20 a来夏季最强的沙尘暴过程进行了数值模拟研究,结果得到:①沙尘暴发生前,沙源处于高温控制下;②起沙是水平低涡和垂直涡叠加而成的一种类似于Benard对流泡的系统扫掠沙源的结果;③起沙主要发生在水平低涡移动方向的右部。     

中国氢氟碳化物、全氟化碳和六氟化硫排放源初步估算

通过调研大量资料和统计分析,初步估算出1995年中国氢氟碳化物（HFCs）、全氟化碳（PFCs）和六氟化硫（SF6）这6种温室气体的排放量,分别为2244、2581.2和215t,分别占当年全球排放总量的0.9%、6.45%和3.7%。     

经济层面和技术层面的碳减排研究

相关资料和事实表明,全球气候发生了很大的变化。二氧化碳是温室效应中最重要的温室气体,碳减排工作是缓解温室效应的一项重要措施,为当前科学研究热点之一。本文主要从经济和技术两个方面,较为系统和全面地介绍了当前碳减排方面的研究进展。经济层面的研究,包括数量化模型、碳税机制和碳减排附加效应几个方面。专业技术方面的研究,包括对碳行为的源汇和贮量的计算研究、碳循环研究、以及减少碳排放的工业技术的运用等。文章还简要提出了中国在碳减排研究方面应采取的几点措施。     

粤北大宝山多金属矿床成矿流体的He-Ar-Pb-S同位素示踪

大宝山多金属矿床是粤北地区典型的巨厚型及细脉带型矿化的多金属硫化物矿床.层状和脉状黄铁矿的氦氩同位素表明:3He/4He的R/Ra值为0.60～4.13,40Ar/86Ar=327～411,反映该成矿流体是大气饱和水(海水)与地幔流体混合作用的结果.铅和硫同位素都揭示了层状(块状)和脉状矿体可能来自不同时期的成矿流体.其中层状矿体为泥盆纪海底火山喷发沉积作用所致,脉状矿体可能来自燕山期岩浆热液充填叠加形成,古大陆碎屑物质和部分有机质的还原对后期成矿流体具有较大的影响作用.     

The influence of medium-range transport on O3 levels at a rural site in Israel

Simultaneous ozone measurements were made at a rural site, 25 km SSW of the city of Jerusalem, and in the center of the city during a period of 28 months. The ozone data were supplemented by SO₂, NO/NO _x ,and meteorological measurements at both sites. Elevated ozone concentrations were recorded at the rural site, mostly during the spring months (May and June) during which the monthly averages and the monthly averages of the daily 30 min maximum levels equalled those measured in the city. During the summer months, both average and peak levels were lower at the rural site by 20 and 35 ppb. The increased ozone levels at the rural site were accompanied by a parallel increase of SO₂ and NO _x ,suggesting hat the excess ozone at the rural site is a result of a transformation during transport of air pollutants from coastal sources.