稻田灌溉河流CH4和N2O排放特征及影响因素

随着农业氮肥大量施用,大量碳氮营养物质以淋溶或径流形式进入周边灌溉水体,使其成为甲烷(CH4)和氧化亚氮(N2O)的重要排放源.以我国东南部地区典型稻田灌溉河流为研究对象,于2014年9月至2016年9月连续两年原位观测表层水体CH4和N2O溶存浓度及其排放通量,旨在明确稻田灌溉河流CH4和N2O的排放特征、排放强度及其主要驱动因子.结果表明,观测期内c(CH4溶存)的年平均值为(390.57±43.95)nmol·L-1(92.80～1 577.54 nmol·L-1),c(N2O溶存)的年平均值为(40.23±3.20)nmol·L-1(10.05～75.40 nmol·L-1).CH4和N2O的排放通量(年平均)分别为(20.73±6.08)mg·(m2·h)-1和(34.30±7.12)μg·(m2·h)-1.CH4和N2O溶存浓度和排放通量整体上均呈现出春夏排放高,秋冬排放低的季节变化趋势.两年CH4累计排放总量为(3 876.30±1 153.96)kg·hm-2,N2O累计排放总量为(5.74±0.98)kg·hm-2.两者持续性全球增温潜势(SGWP,以CO2-eq计)平均为(87.99±15.73)t·(hm2·a)-1.CH4排放通量与水温、底泥可溶性有机碳(DOC)显著正相关,而与水体溶解氧(DO)显著负相关;N2O排放通量与水温、水中铵态氮(NH4+-N)和硝态氮(NO3--N)显著正相关,而与水体DO显著负相关.该研究可为科学估算我国农业灌溉流域CH4和N2O排放总量提供数据支撑和重要参考.     

鄂尔多斯盆地马家沟组马五_1亚段地层水特征及对CO_2地质封存的意义

CO_2地质封存技术是实现碳减排的有效措施,对鄂尔多斯盆地马家沟组马五_1亚段地层水特征进行研究,是下一步实施工程化CO_2封存的首要前提。本文依据对深部钻井取样的直观观察与实验测试,采用单项指标分类评价和多项指标综合评价的方法深入分析了马家沟组马五_1亚段地层水的物理性质、化学性质、地层水类型和水化学特征参数。结果表明:马家沟组马五_1亚段地层水密度较大、矿化度极高,属于卤水,含量最多的离子是Cl~-,其次是Ca~(2+),地层水是CaCl_2型。钠氯系数、氯镁系数、脱硫系数和镁钙系数的分析表明马五_1亚段地层水封闭性极好,处于较强的还原环境。综合分析认为马家沟组马五_1亚段地层水具备实施CO_2封存的良好条件,非常适宜进行CO_2封存。     

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.     

EDTA直接滴定测定镍

参考磷酸在345~356℃时有强腐蚀性的特点,采有硫磷混合酸消解矿样,能使样品消解完全。本方法经加标校核证明,检测结果重现性好,准确度高。     

Structural chromosomal mosaicism and prenatal diagnosis

True structural chromosomal mosaicism are rare events in prenatal cytogenetics practice and may lead to diagnostic and prognostic problems. Here is described the case of a fetus carrying an abnormal chromosome 15 made of a whole chromosome 2p translocated on its short arm in 10% of the cells, in association with a normal cell line. The fetal karyotype was 46,XX,add(15)(p10).ish t(2;15)(p10;q10)(WCP2+)[3]/46,XX[27]. Pregnancy was terminated and fetus examination revealed a growth retardation associated with a dysmorphism including dolichocephaly, hypertelorism, high forehead, low-set ears with prominent anthelix and a small nose, which were characteristic of partial trisomy 2p. Possible aetiologies for prenatal mosaicism involving a chromosomal structural abnormality are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Optimization of the high-pressure, near-critical liquid-based microsortation of recyclable post-consumer plastics

High-pressure, near-critical liquids were used as float-sink separation media for the microsortation of polyolefin mixtures and PET/PVC mixtures. Near-critical carbon dioxide was used for the refinement of the polyolefins, and sulfur hexafluoride was used to separate post-consumer PVC from PET. Preliminary experiments indicated that there was no overlap in the density ranges of post-consumer HDPE, LDPE and PP containers. There was no overlap in the PET and PVC densities, with the exception of a single PVC packaging material with a density in the PET range. These initial results indicated that a float-sink separation was a viable means of microsortation. Separations of 91% LDPE (1/8′ beads)/9% PP (1/8′ chopped strands) resin mixtures and mixed post-consumer polyolefin flakes were then conducted in a laboratory-scale, 1-I batch apparatus. This apparatus not only permitted the observation of the separation, but also enabled the separated fractions to be removed from the high-pressure environment. The results indicated that LDPE purity of greater than 98.9% was obtained in 3 min or less if (a) the fluid density was 0.018 g/cm³ greater than the PP density and only 0.002 g/cm³ less than the LDPE density, thereby providing the greatest buoyancy force for the removal of the PP, (b) the fluid was recirculated upward through the bed of mixed plastics, facilitating the upward movement of the PP, and (c) the loading was kept at levels below 40% by volume. HDPE purity of 99% was also attained with clean, dry, post-consumer mixed plastic flakes. The loadings for these separations were very low, however, due to the difficulty in agitating the mixed bed of plastics using fluid recirculation. An economic analysis of these microsortation processes indicated that the value of the sorted plastics relative to the mixed feed must increase by approx. $0.08/lb for the CO₂-based separation and approx. $0.27/lb for the SF₆-based separation to justify the implementation of these high-pressure processes.     

Catastrophic Reproductive Failure, Terrestrial Survival, and Persistence of the Marbled Salamander

Abstract:  Wide variation in reproductive success is common among amphibians that breed in seasonal ponds, but persistence of adults can buffer against these fluctuations, particularly for long-lived species. We hypothesized that the frequent episodes of catastrophic failure of the marbled salamander ( Ambystoma opacum ) enhance the importance of high terrestrial survival. At Rainbow Bay in South Carolina reproductive success was poor (<1 metamorph/breeding female) in nearly half of the 22 years that the species bred. Complete failure occurred in 6 of 22 years. To study catastrophic failure, we adapted an age-structured, individual-based model with density-dependent growth and survival of larvae. The model was based on extensive data from local field studies and experiments. With consistently good survival in the pond stages, the simulated population required survival probabilities in the upland stages (juveniles and adults) near 0.5/year to persist and near 0.8/year to achieve the increases observed. Catastrophic failure, occurring randomly with probability 0.5/year, created additional fluctuations in the population, raised the thresholds of survival required for persistence, and caused extinction under conditions that were otherwise favorable. The marbled salamander at Rainbow Bay is not at great risk of extinction because of catastrophic failure, but the risk increases dramatically if life span is decreased or frequency of failure is increased. Any reduction in terrestrial survival will have deleterious consequences by reducing the breeding populations at equilibrium, even if it does not jeopardize persistence. Our model provides assessments of risk that can be applied to poorly studied species with similar life histories, such as the endangered flatwoods salamander ( A. cingulatum ).