地下水污染风险评价中特征污染物量化方法探讨

针对地下水污染风险评价中的外界胁迫脆弱性评价缺乏有效量化体系这一问题,通过地下水污染源解析,提出了基于特征污染物及其对应排放量的量化体系;通过特征污染物属性解析及利用层次分析法确定研究侧重点,构建了该体系中的特征污染物量化方法.将该量化方法应用于北京市地下水污染风险评价,结果表明,依据不同研究侧重点得出的3种特征污染物危害性计算结果具有明显差异,并且3种危害性排序与对应的3种属性排序亦存在差异.由此表明,确定研究侧重点的主观倾向对特征污染物危害性计算结果有决定性影响.此外,在计算过程中,以序列值的方式解决3种属性的归一化及不同类别特征污染物属性量化结果的统一,会造成不同特征污染物之间相对属性特征的放大或缩小.     

浅析渣油催化裂化装置腐蚀与防护

目的研究渣油催化裂化装置在生产运行中存在的问题,解决该装置因腐蚀损害而造成停工停产的问题。方法对该装置典型的易腐蚀部位进行分析研究,主要包括对再生器卸剂线阀门冲蚀、膨胀节露点腐蚀、螺栓断裂的形貌分析及换热器管束端口腐蚀的具体分析,针对不同部位不同的腐蚀机理及采取的相关有效措施。结果基于上述典型案例的研究,提出该催化裂化装置日常防腐的4个措施,主要措施为强化腐蚀监测、强化施工质量监督、强化助剂管理及生产操作平稳运行。采用三指式电化学和电感腐蚀监测方式,对催化裂化装置的分馏塔顶油气系统、分馏塔顶循环系统、富气冷却系统、吸收稳定系统等易腐蚀部位进行重点监测,做到月汇总分析,根据腐蚀率进行重点关注,做好防腐和腐蚀率的对应措施。结论找准造成腐蚀的根本原因,针对腐蚀情况制定相应的应对措施,降低腐蚀速率,减低设备损坏,从而保证装置安稳长时间的运行。     

考虑气体传输和应力耦合作用的页岩表观渗透率演化机理

为模拟页岩气抽采过程中孔隙压力对其吸附特性和渗透特性的影响,通过吸附及多孔弹性理论,建立考虑过剩吸附量的吸附模型,并进一步建立考虑气体传输影响的页岩表观渗透率模型,通过试验数据验证其合理性。结果表明,1)随孔隙压力逐渐升高,页岩过剩吸附量呈先快速增加后趋于平缓的变化趋势;随温度升高,其吸附量呈降低趋势。考虑过剩吸附量和温度修正的吸附模型计算结果与试验所测结果吻合较好,且能较好地反映不同温度下页岩过剩吸附量与孔隙压力的关系。2)页岩气体吸附过程中产生的基质膨胀变形量随孔隙压力升高而升高,且温度较低时的气体吸附变形量大于温度较高时的变形量。3)在有效应力恒定的条件下,CH₄和He的表观渗透率随努森数增大而减小。相同孔隙压力条件下,随有效应力升高CH4和He的表观渗透率均呈降低的趋势,且页岩表观渗透率对有效应力的敏感程度随孔隙压力升高而降低。相同有效应力条件下,充入He的页岩表观渗透率均大于充入CH4的页岩表观渗透率。4)构建考虑气体传输和应力耦合作用的页岩表观渗透率模型,模型计算的渗透率与实测值具有良好的一致性,能较好地表征不同外应力条件下的页岩表观渗透率演化规律。     

伯克氏菌Y4对水稻幼苗镉损伤和镉吸收的影响

为探明伯克氏菌Y4(Burkholderia sp.Y4)对镉(Cd)胁迫下水稻幼苗的生长和Cd吸收积累的影响及其作用机制,以水稻低Cd积累品种湘早籼24(X24)和高Cd积累品种T优705(T705)为材料,通过水稻种子萌发和幼苗试验,利用非损伤微测技术和原子吸收等检测方法,研究外源施加伯克氏菌Y4对Cd胁迫下水稻生...     

生态足迹方法在中国应用的案例初探

生态足迹方法通过估算维持人类生存的自然资源消费量和同化人类产生的废弃物所需要的生态性生产空间面积大小,并与给定人口区域的生态承载力进行比较,衡量区域的可持续发展状况。本文介绍了生态足迹模型的理论依据和计算方法,从模型方法应用范围,计算所需资料和模型自身三方面分析了生态足迹方法在我国应用中存在的问题和方法本身的不足。详细分析和比较了生态足迹方法在我国不同省市及地区的应用案例,结果表明,经济比较发达地区很大程度上需要通过地区贸易从不发达地区输入生态足迹,因而加重了不发达地区的生态负担。     

不同容重的泥石流淤积厚度计算方法研究

泥石流的淤积厚度是泥石流灾害评估和防治的最重要的参数之一,但迄今还没有较好的方法计算不同容重的泥石流淤积厚度。本文通过研究泥石流屈服应力的特点,提出了用地区参数和泥石流体积浓度来计算泥石流屈服应力,进而计算泥石流淤积厚度的方法。采用本文方法计算已发生泥石流地区不同容重泥石流的淤积厚度,可以很好地应用于泥石流灾害评估和防治。     

恭城—栗木断裂带的应变特征与变形环境探讨

通过系统的有限应变测量与差异应力估算,探讨了恭城—栗木断裂带的应变特征与变形环境,以其推动该断裂带的研究向更深层次发展。结果表明:①付林指数K的变化范围为0.32～1.67;应变主轴平均方位为276°∠21°,与断裂带的整体逆冲方向基本一致;断裂带的平均应变程度为2.26～3.00,属中等应变程度;断裂带的应变类型属压扁型应变与单剪型平面应变的一种复合叠加类型。②断裂带的差异应力值为40～80 MPa,变形深度小于10 km,属半脆性—半韧性的变形域。③断裂带的应变特征与变形环境及宏观构造样式基本吻合。     

Resetting relationship trajectories: A reconceptualization of the relationship repair process

Negative events within and outside of work can disrupt coworkers' relationships, triggering a re-evaluation of relationship quality. The subjective experience of these events – which we term relationship threats – harms relationships, resulting in long-lasting negative interpersonal and organizational consequences. Coworkers' responses to a relationship threat determine whether relationships are repaired or whether the threat leads to a loss of commitment, lowered satisfaction, and increased negative affect. Because of the critical role that relationships play in organizational life, it is vital that we have a comprehensive understanding of the repair process. To date, researchers have focused on one of three repair processes: trust repair. In reconceptualizing relationship repair, we flesh out the remaining two processes: relationship work and sensemaking. Our reconceptualization balances the restorative actions that mitigate in-the-moment harm with those that sustain these benefits over time. We expand our understanding of relationship repair by highlighting the role that narrative foundations play in determining a relationships' vulnerabilities and determining effective repair processes. We highlight the importance of considering relationship threats as events embedded within a relationship's history; identify narrative foundations as a bridging mechanism between disrupted relationships and their repair; and expand our conceptualization of the processes that repair relationships.     

加速寿命试验三参数威布尔分布的极小变异-极大似然估计

目的 在加速试验中,对寿命服从三参数威布尔分布的产品进行可靠性评估与寿命预测,解决形状参数小于1时传统方法难以计算的问题。方法 利用三参数威布尔分布与指数分布之间的转换关系,以变异系数误差最小为优化目标,在确定最优位置参数估计值的基础上,应用拟极大似然方法估计分布模型中的其余参数,建立极小变异–极大似然估计（MV-MLE）。根据加速寿命试验中失效机理不变的原则,在失效机理等同条件下,将该方法推广至多应力水平下的可靠寿命评估。结果 在单一应力与多应力水平下,通过仿真模拟验证了所提方法的有效性。与传统方法相比,在小样本条件下,所提方法可提高形状参数（机理等同性参数）估计精度40%以上。结论 所提方法对于三参数威布尔分布的参数估计和寿命评估具有较高精度,能够有效克服传统方法的不足,在加速寿命试验评估中具有良好的应用效果。     

SOLUBLE SUGAR COMPOSITION OF POND‐CYPRESS: A POTENTIAL HYDROECOLOGICAL INDICATOR OF GROUND WATER PERTURBATIONS1

ABSTRACT: Pond‐cypress, a deciduous conifer, is a dominant canopy species in depressional wetlands of the southeastern Coastal Plain (SCP). Extensive premature decline and death of pond‐cypress trees in central Florida have been attributed to hydroperiod alterations due to excessive withdrawals of ground water from the Floridan aquifer. One factor identified in the decline process is basal decay, which may be related to the presence of Botryosphaeria rhodina and Fusarium species (nonaggressive, facultative fungal pathogens). These fungi have been cultured from sapwood tissue of declining pond‐cypress associated with ground water mining, but not from pond‐cypress away from ground water mimng areas. In this experiment, differences in soluble (nonstructural) carbohydrate composition of branch tips were evaluated for one‐and two‐year old, nursery‐grown (unsheltered) pond‐cypress, following a year of growth under treatment conditions (control, fungal inoculation, water stress, and fungal inoculation plus water stress) in a growth chamber. Results from two methods of wet chemical analysis were compared (trimethylsilyl methylglycoside‐Method A, and alditol acetate ‐ Method B). Three pentoses (arabinose, rhamnose, and xylose) and three hexoses (galactose, glucose, and mannose) were identified in branch tips from both age classes. A fourth hexose (fucose) also was identified in samples from the younger trees. The acidic sugar, galacturonic acid, was identified in both age classes using Method A. Results suggest that prolonged water stress is correlated with greater relative concentrations of the neutral soluble sugars rhamnose (P = 0.02), xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic sugar galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for Method B. These results also suggest that in the absence of water stress, the fungal pathogen B. rhodina does not penetrate to the sapwood of the trees, and that inoculation with this fungal pathogen is not correlated with differences in relative concentrations of nonstructural, soluble carbohydrates, based on Method A analysis. Empirical evidence suggests that pond‐cypress trees in depressional wetlands respond similarly to anthropogenic perturbations of ground water, but not to natural periods of drought in the absence of such perturbations. Therefore, pond‐cypress appear to be integrators of groundwater perturbations. Greater concentrations of the soluble sugars identified in this study in pond‐cypress branch tips may be hydroecological indicators of such anthropogenic perturbations as unsustainable yield from the regional aquifer and adverse impacts from aquifer storage and recovery (ASR) activities in the SCP.