多源遥感数据沙尘暴强度监测的信息可比方法

综述了利用遥感技术进行沙尘暴监测研究的国内外进展，提出了利用多源遥感数据识别和提取沙尘暴信息的新方法，利用近红外1．6μm波段特性，构建了可比沙尘强度指数。研究表明：利用卫星探测器11μm，12μm波段差值进行沙尘暴信息识别和提取，可以达到满意的效果，但不能刻画沙尘暴强度；构建的可比沙尘强度指数，能够解决多源遥感数据由于卫星平台、监测时间、监测区域等不同因素导致的监测结果不可比的问题；同时监测结果与地面气象站监测数据有较好的一致性，能够从时间、空间两方面刻画沙尘暴强弱分布，可以作为沙尘暴定量研究的参数，为利用多源遥感数据持续定量地监测沙尘暴的起源、移动、传输路径、扩散等待征奠定了基础。     

不同价态无机砷对罗非鱼肝脏砷积累及GSH/GST解毒代谢的影响

低剂量中长期暴露下的氧化胁迫是砷对水生生物致毒的重要机制之一。本文通过对罗非鱼进行32 d的食物相砷暴露,测定不同时间点罗非鱼肝脏中谷胱甘肽(glutathione,GSH)含量和谷胱甘肽巯基转移酶(glutathione S-transferase,GST)活性,揭示不同价态无机砷对罗非鱼肝脏中GSH/GST的影响机制。经三价砷(As(III))暴露后,砷含量在2 d内显著增加而在随后的30 d内无显著性差异; 0～2 d内GSH含量显著增加,后降低,13 d后GSH含量均低于空白组; 0～6 d GST活性均大于空白组,6～8 d GST活性降低,8 d后活性高于空白组,且32 d达到最大值。经五价砷(As(V))暴露后,罗非鱼肝脏中砷含量逐渐增加,在20 d时达到最大值而后无显著性差异; 0～2 d时GSH含量降低,随后逐渐增加,在16 d达到最大值,16 d后GSH含量均低于空白组; 0～8 d时GST被大量诱导合成,8～20 d时GST合成被抑制,20 d后活性增加,在32 d达到最大值。As(III)和As(V)对罗非鱼GSH/GST的不同影响与其在罗非鱼体内的积累量有关。As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GSH含量呈统计学正相关,而As(V)暴露无明显相关性。这是因为As(V)进入罗非鱼肝脏后会还原为As(III),进而GSH作为可提供巯基的还原剂而被大量消耗。另外,As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GST活性呈显著负相关,而As(V)暴露却呈现出很强的滞后性,这是由于进入生物体内的As(V)需转化为As(III)后,才可直接作用于酶系统。可见,不同形态砷对水生生物的致毒机制需进一步深入研究。     

麻疯树胚乳愈伤组织诱导及其污染消除

经过比较分析各种消毒方法,获得了较为理想的麻疯树(Jatrophacurcas)胚乳愈伤组织,并动态观察其类型、形态特征、增殖速率和形态发生能力,为麻疯树胚乳植株再生及愈伤组织和细胞培养生产药用成分奠定了基础.以麻疯树成熟胚乳为外植体进行愈伤组织的诱导,测试0.4mg/L的分裂素(BA、KT与TDZ)与2.0mg/L的生长素(IAA、IBA、NAA与2,4D)搭配组合的诱导效果.结果表明,对胚乳愈伤诱导效果而言,2.0mg/L的2,4D效果最好,NAA的效果次之,IBA又次之,IAA的效果最差.BA和KT诱导效果差异不显著,TDZ的添加可促进胚乳愈伤组织的诱导.选择适宜的消毒剂(种类、浓度)和消毒(处理)时间对胚乳外植体的接种成功具有至关重要的作用.在本试验所采取的灭菌方式中,用70%酒精处理30s,然后用10%NaClO处理25min,灭菌效果最佳,同时对胚乳外植体的生长影响最小.图3表1参23     

Effects of aluminum substitution on the surface charge of colloidal goethite particles: experiments and MUSIC modeling

Environmental Science and Pollution Research - Proton adsorption behavior on the surface of Al-substituted goethites as a function of pH and ionic strength was investigated and simulated with the...     

Evaluating the outcomes of genetic rescue attempts

Augmenting gene flow is a powerful tool for the conservation of small, isolated populations. However, genetic rescue attempts have largely been limited to populations at the brink of extinction, in part due to concerns over negative outcomes (e.g., outbreeding depression). Increasing habitat fragmentation may necessitate more proactive genetic management. Broader application of augmented gene flow will, in turn, require rigorous evaluation to increase confidence and identify pitfalls in this approach. To date, there has been no assessment of best monitoring practices for genetic rescue attempts. We used genomically explicit, individual-based simulations to examine the effectiveness of common approaches (i.e., tests for increases in fitness, migrant ancestry, heterozygosity, and abundance) for determining whether genetic rescue or outbreeding depression occurred. Statistical power to detect the effects of gene flow on fitness was high (≥0.8) when effect sizes were large, a finding consistent with those from previous studies on severely inbred populations. However, smaller effects of gene flow on fitness can appreciably affect persistence probability but current evaluation approaches fail to provide results from which reliable inferences can be drawn. The power of the metrics we examined to evaluate genetic rescue attempts depended on the time since gene flow and whether gene flow was beneficial or deleterious. Encouragingly, the use of multiple metrics provided nonredundant information and improved inference reliability, highlighting the importance of intensive monitoring efforts. Further development of best practices for evaluating genetic rescue attempts will be crucial for a responsible transition to increased use of translocations to decrease extinction risk.     

低碳试点政策是否提高了城市碳排放效率——基于低碳试点城市的准自然实验研究

作为推动我国低碳经济发展的重要政策,低碳试点城市建设成效在当今我国面临碳减排及经济下行双重压力的情况下显得尤为重要。基于2006—2018年间的279个地级市样本数据,运用超效率SBM模型核算了城市碳排放效率,并通过双重差分模型实证检验了低碳试点政策对城市碳排放效率的影响。研究表明：低碳试点政策能够显著提高城市碳排放效率,这一结论在经过PSM-DID等一系列稳健性检验后仍然成立。异质性分析发现,低碳试点政策对碳排放效率的影响在东西部及非资源型地区更显著。机制分析则表明,低碳试点政策的政策效应主要通过提高城市技术创新水平和调整城市能源结构来发挥作用。区分东中西地区的作用机制检验结果表明,东部地区的试点政策主要通过调整能源结构及产业结构合理化来影响碳排放效率,西部地区和中部地区则分别主要通过技术创新和产业结构合理化发挥作用。本文为加强低碳试点城市建设、实现碳减排与经济发展双赢提供了有益的经验启示。     

事故车辆影响下的城市道路交通仿真研究

为研究事故车辆影响下城市道路交通的特征，构建考虑车辆抢道行为的元胞自动机交通流模型，研究给定冲突区域长度下不同进车率和不同事故持续时间对城市道路交通流的影响。研究结果表明:事故车辆会诱发交通瓶颈，对城市交通产生显著干扰并形成拥堵带，且拥堵带向事故车辆上游传递。不同事故持续时间下交通流演化存在差异，道路平均车流量、车流平均密度随着事故持续时间的增加而增加，车辆平均速度随之减小。当道路中车辆较少（pin=0.3）且事故持续时间达到15 min时，交通处于严重拥堵状态；当道路中车辆较多（pin=0.5）、事故持续时间达到5 min时，交通即处于严重拥堵状态。研究结果可为优化城市交通事故处理机制提供依据。     

Performance analysis and life cycle greenhouse gas emission assessment of an integrated gravitational-flow wastewater treatment system for rural areas

Environmental Science and Pollution Research - Due to the lack of appropriate wastewater treatment facility in rural areas, the discharging of wastewater without sufficient treatment results in...     

基于事故风险源的城市环境风险分区研究——以南京市为例

以事故风险个案评价原理为基础,从风险受体角度出发,研究城市内部风险源最大可信事故发生时的最大影响半径,针对不同类型风险源的影响半径做空间分析得到区域风险等级,并结合自然和城市敏感区数据分析得到综合的事故风险分区结果。以南京市为研究对象,从城市内部多类型风险源的影响范围和程度入手,采用风险制图法评价城市事故风险,对本市数百家危化品单位、危废单位、涉重单位、高压走廊及天然气高压管道等涉及的风险源布局和影响半径进行分析,综合南京市城市用地布局及市域城镇体系规划提出防范措施与优化建议,其分区结果对未来南京市城市总体规划、土地利用规划中的安全规划、布局选址及工业结构调整升级等有直接的现实意义和指导意义。     

Toxicity and oxidative stress induced by chromium in workers exposed from different occupational settings around the globe: A review

The present review focused on the levels and toxicological status of heavy metals especially chromium (Cr) in the exposed workers from different occupational settings around the globe and in Pakistan. It was found that exposed workers from leather tanning and metal plating units showed elevated levels of Cr than the workers from other occupational settings. Cr and other heavy metals level in biological matrices of the exposed workers in different occupational settings revealed that developing countries are severely contaminated. Occupational settings from the Sialkot district, Pakistan exhibited elevated level of Cr in biological entities of the exposed workers. Review suggested that higher level of Cr exposure to the workers enhance the oxidative stress (reactive oxygen species (ROS) and hydroxyl (OH) radical generation) which may cause; cellular and molecular damage such as genotoxicity and chromosomal aberration formations, and carcinogenic effects. This review will help to understand the Cr contamination mechanisms and associated health implications in different occupational settings around the globe in general and particularly to Pakistan. This study will also assist occupational health and safety management authorities to devise or change the Cr recommended exposure limits (REL) for different occupational settings.