地质高背景区土壤-玉米重金属综合质量评价

为了研究地质高背景区土壤及农产品的污染程度及原因,为农产品安全生产及土壤重金属风险管控提供依据,在重庆市巫山县抱龙镇耕地区采集了土壤-玉米协同样品36套,分析了土壤-玉米中重金属(Cd、 Hg、 Pb、 As和Cr)含量及土壤pH,利用内梅罗综合污染指数法(P_N)和综合质量影响指数(IICQ)对土壤-玉米中重金属的污染程度进行了评价,并分析了土壤重金属来源及玉米重金属超标的影响因素.结果表明,研究区土壤重金属含量的平均值高于全国及重庆土壤背景值,土壤重金属富集效应明显.Cd是土壤-玉米超标的主要因子,土壤和玉米Cd的总体超标率分别为91.67%和30.55%.内梅罗综合污染指数评价结果显示,土壤以重度污染为主,占比63.89%,玉米轻度污染、中度污染和重度污染的占比分别为5.56%、 11.11%和11.11%.土壤-玉米综合质量影响指数以中度和重度污染为主,分别占比44.44%和47.22%.从重金属污染空间分布来看,玉米与土壤污染区域不一致.土壤重金属污染主要受到二叠系和三叠系地层的影响,与黑色岩系和灰岩区次生富集作用有关.玉米Cd含量主要受到土壤pH的影响,...     

2006~2020年广东省大气甲醛排放演变特征

大气甲醛（HCHO）是臭氧（O₃）和细颗粒物（PM_2.5）二次组分的关键前体物,在大气光化学反应和二次污染形成过程中扮演着重要角色,并存在致癌性.然而,当前对大气HCHO排放来源认识存在不足,制约了二次污染形成机制研究和污染防控策略制定.采用排放因子和成分谱结合方法,建立2006~2020年广东省HCHO排放趋势清单,识别了广东省主要HCHO排放来源和排放时空演变特征.结果表明,2006~2020年期间广东省HCHO排放量在3.9~5.6万t区间波动,整体呈现极微弱的下降趋势;生物质燃烧源是广东省重要HCHO排放源,而受到管控措施的显著影响,其排放量占比从2006年的58%降至2020年的27%;溶剂使用源的HCHO排放则逐渐突显,2020年占比增长至28%,并成为广东省首要排放源,其中塑料制品和沥青铺路是主要贡献行业.移动源中以柴油作为燃料的工程机械和货车也是HCHO重要排放来源;虽然珠三角和非珠三角地区对广东省HCHO排放量贡献相当,但空间分布结果表明HCHO排放热点区域分别集中于珠三角中心区域和非珠三角的东西两角,这是由于珠三角主要来源为溶剂使用源和移动源,而非珠三角主要受生物质燃烧源影响.因此,未来应进一步加强珠三角中心区域的工业和移动源减排以及粤西地区的生物质燃烧监管.     

基于不同排放清单的长三角人为CO2排放模拟

目前基于排放清单估算的区域和城市尺度上的人为CO₂排放不确定性较大.为了我国实现碳达峰和碳中和的目标,亟需对我国的区域尺度,特别是大城市群的人为CO₂排放进行准确估算.分别利用两种先验人为CO₂排放数据(EDGAR v6.0清单和EDGAR v6.0联合GCG v1.0的改进清单)作为输入数据,采用WRF-STILT大气传输模型模拟长三角地区2017年12月至2018年2月大气CO₂摩尔分数,再以安徽全椒高塔观测的大气CO₂摩尔分数作为参考值,通过贝叶斯反演方法得到的比例因子改进了模拟结果,并实现了长三角人为CO₂排放通量的估算.结果表明：(1)在冬季,相对于基于EDGAR v6.0模拟的大气CO₂摩尔分数值而言,基于改进清单模拟的大气CO₂摩尔分数与观测值更为一致;(2)模拟的大气CO₂摩尔分数在夜间高于观测值,白天则相反,主要因为排放清单的CO₂排放数据不能表征人为...     

Global Warming and Global Dioxide Emission: An Empirical Study

In this paper, the dynamic relationship between global surface temperature (global warming) and global carbon dioxide emission (CO₂) is modelled and analyzed by causality and spectral analysis in the time domain and frequency domain, respectively. Historical data of global CO₂emission and global surface temperature anomalies over 129 years from 1860–1988 are used in this study. The causal relationship between the two phenomena is first examined using the Sim and Granger causality test in the time domain after the data series are filtered by ARIMA models. The Granger causal relationship is further scrutinized and confirmed by cross-spectral and multichannel spectral analysis in the frequency domain. The evidence found from both analyses proves that there is a positive causal relationship between the two variables. The time domain analysis suggests that Granger causality exists between global surface temperature and global CO₂emission. Further, CO₂emission causes the change in temperature. The conclusions are further confirmed by the frequency domain analysis, which indicates that the increase in CO₂emission causes climate warming because a high coherence exists between the two variables. Furthermore, it is proved that climate changes happen after an increase in CO₂emission, which confirms that the increase in CO₂emission does cause global warming.     

Carbon Emission by Soils in Forests Damaged by the Siberian Moth

In the southern-taiga low grass–green moss fir forest completely defoliated by the Siberian moth, the rate of soil respiration in the third year after the pest population outbreak was 1.5 times higher than in an undisturbed tree stand. This was explained by a significant increase in the abundance and activity of soil microorganisms in the pest-defoliated forest, which occurred due to the qualitative changes in the litter composition and the increased temperature and moisture in the upper soil layers. The rate of carbon emission from the soil in the defoliated forest was 41.7 kg/ha per day, compared to 28.3 kg/ha per day in the undisturbed fir forest.     

台湾7.6级地震及其强余震前电磁辐射特征

本文总结了1986年11月15日台湾花莲海域地震及其强余震前电磁辐射的前兆特征。所用的仪器为DDC-2型电子补偿仪、XWX-2042电位差计,记录极距为100m的两埋地电极间所接收到的电磁辐射信息,震前异常波形最大幅度可达187.5mv,为正常背景的十数倍,频谱较宽(0.005—5Hz)。这种特征对认识发生在太平洋板块与亚欧板块上的地震有一定意义。     

Application of micrometeorological approaches to measure methane exchange in a dry paddy field in the western coast of Korea

The exchange processes of CH₄ were investigated in a paddy field in the Hari area of Kang Hwa Island over an 8 day period in late April 2002. The quantification of CH₄ fluxes was made under dry field condition of early spring by concurrently measuring its concentrations (at the two heights of 1 and 5 m) and the relevant micrometeorological parameters. To help elucidate the factors determining the mobilization characteristics of CH₄, the results of our measurement data were examined using a number of approaches. The results of the trajectory analysis indicated that its concentration changed very sensitively with the influence of different source types, as seen from the air mass movement patterns. The concentrations and fluxes of methane, when examined over this short-term scale, showed moderately strong patterns across 24 h period in which higher values tend to occur during morning or evening. The overall results of our field measurements suggest that CH₄ exchange processes in the paddy area proceeded in a fairly complicated manner. The study area behaved as a net source of CH₄ to the atmosphere with a net daily emission rate of 3.6 mg m⁻² despite the fact that downward deposition was observed more frequently than upward emission.     

中国加油站VOC排放污染现状及控制

应用排放因子法估算了2002年度全国加油站VOC的排放量.在综合考虑经济,社会,人口等各方面因素后,通过调整现有的活动水平估算了未来20a内全国的燃油消耗情况,以及VOC排放的增长趋势.结果表明:2002年我国加油站VOC排放量为187.6×10³t,由此造成的经济损失达到了7.5×10⁸元人民币.在维持现有控制水平情况下,到2030年VOC排放量将达到1196×10³t,经济损失高达47.8×10⁸元人民币.比较了StageⅠ、StageⅡ油气回收系统以及ORVR的回收效率和成本,并对其可行性和经济适用性进行分析.结果表明:这3种回收技术的引进将会大规模的消减加油站VOC的排放,并且选择性的措施组合能够取得更好的效果.相对于StageⅡ回收系统,ORVR的效率更高费用更低.但是ORVR的引进需要比StageⅡ更长的时间,为了达到80%的普及率至少需要11a左右.为在短期内达到一定的控制要求,可优先考虑StageⅡ回收技术;但是从长期的环境和经济效应来看,ORVR才是最终的选择.     

重型柴油车车载排放实测与加载影响研究

采用车载排放测试仪,对2辆重型柴油卡车在空载和加载条件下进行实际道路车载排放测试.通过分析获得了油耗与排放速率的速度-加速度及其工况点的分布,发现高油耗与高排放工况点主要集中在高速加速区域,加载时油耗与排放高值随工况点分布更广;车辆在(30±2.5)km·h^-1等速及加速行驶时受加载影响最大,此时加载油耗与排放约是空载的1.6～3.2倍左右;由实测结果发现,卡车Ⅰ和卡车Ⅱ加载时油耗及CO、HC、NO_x排放因子分别是空载的1.6倍、3.5倍、1.1倍、1.5倍以及1.2倍、1.0倍、0.9倍和1.5倍,加载对油耗与NO_x排放影响最为明显,对HC影响最小,CO影响取决于车辆保养水平;卡车Ⅱ较卡车Ⅰ车型更大,发动机功率更高,相同荷载时受加载影响较小,说明重型车在发动机负荷可承受的范围内合理装载,有助于避免油耗与排放恶化,提高燃油经济性和排放水平.     

耕作制度对川中丘陵区冬灌田CH4和N2O排放的影响

采用静态暗箱/气相色谱法连续2 a田间原位测定,研究川中丘陵区冬灌田CH₄和N₂O的排放特征和不同耕作制度对冬灌田CH₄和N₂O排放的影响.结果表明,1a只种1季中稻冬季灌水休闲的冬灌田(PF),在水稻生长期,CH₄平均排放通量为(21.44±1.77)mg·(m²·h)^-1,非水稻生长期为(3.77±0.99)mg·(m²·h)^-1,分别大大低于以前文献报道的在西南其它地方观测值;全年CH₄排放量以水稻生长期CH₄排放量为主,非水稻生长期CH₄排放量仅占全年总排放量的23.2%.冬灌田N₂O排放通量年均值为(0.051±0.008)mg·(m²·h)^-1,且主要集中在水稻生长季,非水稻生长期N₂O排放量仅占全年总排放量的8.1%.在采用水旱轮作制后,冬灌田CH₄排放量大大降低,稻-麦轮作(RW)和稻-油菜轮作(RR)全年CH₄排放量分别为PF的43.8%和40.6%.但冬灌田改为水旱轮作制后,N₂O排放量显著增大,RW和RR的N₂O年排放量分别是PF的3.7倍和4.5倍.综合考虑冬灌田在采用不同耕作制度后排放CH₄和N₂O的全球增温潜势(GWP),无论是短时间尺度还是长时间尺度,采用3种耕作制度全年所排放的CH₄和N₂O所产生的综合GWP都为:PF RW≈RR.在20a、100a和500a时间尺度上,PF分别约是RW和RR的2.6、2.1和1.7倍.冬灌田改为水旱轮作制度后能大大减少CH₄和N₂O所产生的综合GWP.