Effects of reciprocal hybridization on cadmium accumulation in F1 hybrids of two Solanum photeinocarpum ecotypes

In this study, farmland and mining ecotypes of Solanum photeinocarpum (a potential cadmium (Cd) hyperaccumulator plant) were reciprocally hybridized each other, and the Cd accumulation characteristics of the F1 hybrids were studied. In pot experiments, higher biomasses and Cd extraction abilities were found for two S. photeinocarpum F1 hybrids than for the parents, but the Cd contents in various organs were lower in the hybrids than the parents. However, the differences between the Cd contents in the two hybrids were not significant. The antioxidant enzyme (superoxide dismutase and peroxidase) activities were higher for the S. photeinocarpum F1 hybrids than the parents. Less DNA methylation was found in the hybrids than the parents because more demethylation occurred in the hybrids than the parents. The biomass, Cd content, and Cd extraction ability effects in field experiments were similar to the effects in the pot experiments. It was concluded that reciprocally hybridizing different S. photeinocarpum ecotypes improved the ability of S. photeinocarpum to be used to phytoremediate contaminated land.

     

高分子稳定剂改良河道岸坡表层砂土水稳定性试验研究∗

针对河道岸坡表层砂土水稳定性问题,采用高分子稳定剂对砂土进行改良,结合浸泡崩解测试法和浸泡剪切测试法对改良砂土的水稳定性进行一系列的试验研究,并对砂土改良前后的水稳定性进行对比分析,并结合微观扫描电镜对改良机理进行分析。研究结果表明：稳定剂可以提高河道岸坡表层砂土的水稳定性。改良砂土随着稳定剂含量和密度的增大,崩解后的散开面积减少,当稳定剂含量达到0.3%时,试样呈现稳定状态。改良砂土试样在200 kPa轴向应力下的剪应力峰值整体上随稳定剂含量和密度的增加而增加。改良砂土的水稳定系数K随着稳定剂含量和砂土密度的增加而增大;当稳定剂含量大于3%时,改良砂土的稳定系数K均达到90以上。高分子稳定剂作为一种土体改良材料,与水混合后加入到砂土中,可填充砂土颗粒间的孔隙,包裹和连接砂土颗粒,形成一个整体的网状膜结构,提高砂土的水稳定性能。研究结果可为河道岸坡有效治理提供一定的参考。     

场开挖爆破粉尘粒度分布特征杨房沟水电站料∗

通过分析杨房沟水电站料场开挖爆破粉尘的粒度分布特征,为改进爆破降尘工艺提供粉尘粒度学依据。在料场爆破区、工作平盘、出入沟、最终边帮等处采集粉尘样品,采用激光粒度分布仪测试粉尘样品的分散度;以粉尘粒度分布数据拟合分布函数,表明爆破粉尘的粒度分布函数呈现对数正态分布特征;与经典的罗森·拉姆勒(Rosin?Rammler)分布函数模型对比分析表明,对数正态分布函数用于描述爆破粉尘的粒度分布更加准确。基于对数正态分布函数模型,厘定爆破粉尘粒度分布参数,分析TSP、PM10、PM5、PM2.5及PM1粉尘占全尘的比例,定量表达爆破粉尘粒度分布特征。结果表明：杨房沟水电站料场爆破粉尘具有显著的对数正态分布特征;离爆破中心距离越远,粒度分布范围越窄,对人体有害粉尘占比越大;建议采用爆破粉尘捕捉吸附技术、掺和湿润性抑尘剂的水雾喷洒等降尘措施。     

UV Spectroscopic Monitoring of Vaporized Monoaromatic Hydrocarbons from Petroleum-Contaminated Soils

Fast and simple systems using ultraviolet (UV) absorbance were examined for on-line monitoring of monoaromatic hydrocarbons from petroleum-contaminated soils in this research. Since soil particles hinder the UV light transmittance, the absorbance measurement of vaporized monoaromatic hydrocarbons in soil gas extracted from petroleum-contaminated soils was proposed. In the fixed system that exhibited higher sensitivity than the portable one, the absorbance intensity of benzene, toluene, ethylbenzene, and xylene increased in proportion to the concentration of the contaminants. The portable system, however, was suitable for screening purpose, while it exhibited faster response. There was no interference from water, which helps the applicability of the proposed systems to the actual fields.     

地铁区间隧道烟气层化现象研究

以重庆某一地铁区间隧道为原型,搭建了1∶15小尺寸隧道试验台,通过小尺寸试验与FDS 6.5.2数值模拟开展隧道顶部烟气温度分布及分层规律研究。基于Newman提出的烟气层分区条件,研究了不同纵向风速下的烟气分层现象,提出了烟气稳定层化长度的概念,并分析了火源热释放速率及断面型式对烟气层化长度的影响。试验证明了Newman提出的烟气分层计算方法是可信的。结果表明:纵向风速较小时,火源下游能呈现烟气分层现象;烟气稳定层化长度受火源热释放速率影响较大,随热释放速率增大而增大;隧道高度的变化对烟气稳定层化长度的影响较小。     

加轴压卸围压下含瓦斯煤岩损伤变形的能量演化机制

采动影响下含瓦斯煤岩的损伤变形是一个极其复杂的非线性过程,单纯依靠传统经典弹塑性力学无法准确分析其破坏机理。针对此情况,通过试验研究了不同初始围压条件下含瓦斯煤岩的损伤变形特征,并分析了损伤变形与能量演化规律之间的内在联系。研究表明:初始围压越高,煤样破坏时强度越大,脆性破坏特征越明显,瓦斯流量急剧增加幅度越大,煤样破坏时积累的总能量和弹性应变能越多,且初始围压与弹性能之间满足对数函数关系。采用累积耗散能定义了煤岩损伤变量,并分析了不同阶段损伤与渗透率之间的演化关系。     

Robust Regression with Data-Dependent Regularization Parameters and Autoregressive Temporal Correlations

We introduce robust procedures for analyzing water quality data collected over time. One challenging task in analyzing such data is how to achieve robustness in presence of outliers while maintaining high estimation efficiency so that we can draw valid conclusions and provide useful advices in water management. The robust approach requires specification of a loss function such as the Huber, Tukey’s bisquare and the exponential loss function, and an associated tuning parameter determining the extent of robustness needed. High robustness is at the cost of efficiency loss in parameter loss. To this end, we propose a data-driven method which leads to more efficient parameter estimation. This data-dependent approach allows us to choose a regularization (tuning) parameter that depends on the proportion of “outliers” in the data so that estimation efficiency is maximized. We illustrate the proposed methods using a study on ammonium nitrogen concentrations from two sites in the Huaihe River in China, where the interest is in quantifying the trend in the most recent years while accounting for possible temporal correlations and “irregular” observations in earlier years.     

基于DMSP-OLS夜间灯光数据的长江经济带城镇体系空间格局演变（1992～2013）

研究长江经济带城镇体系空间格局演变,对于透视长江经济带城镇体系空间格局演变特征和规律以及促进长江经济带城镇体系空间格局优化发展有着重要意义。利用多时相同期Landsat卫星数据以及运用聚类分析方法对长江经济带夜间灯光数据进行校正,并采用其他辅助数据法对比分析获取城镇建成区面积的阈值,在此阈值基础之上选取景观总面积、总斑块数量和聚集度指数等总共8个典型景观格局指标, 继而使用FRAG-STATS 4.2 软件对1992~2013年间长江经济带城镇发展的空间格局变化进行计算分析。研究结果表明：(1）1992~2013年间,长江经济带城镇化快速扩展,城镇建成区面积增加了9.68倍,斑块数量增加了2.39倍,斑块密度也得到较大的增加,反映出长江经济带城镇数量不断增加和城镇建成区面积不断扩大;（2）景观斑块形状复杂度逐渐上升,中小城市不断壮大,同时出现了较多的新兴小城镇,总边界长度和平均边界密度的年均增长速度分别为21.56%和21.58%,体现了长江经济带城镇间聚集度越来越高,相互影响也越来越大;(3）最大斑块指数和聚集度指数两个指标在整体上呈现出逐年下降的态势,但是景观总面积、总斑块数量和斑块密度等8个指标在演变过程中均存在一定的波动和无序化,反映出长江经济带在城镇化过程中呈现出不规则和无序化的特征。     

城镇化过程中的流域面源污染时空变化

以斧头湖流域为研究对象,在野外调查的基础上,借助遥感和GIS技术,对2008年、2015年斧头湖流域土地利用格局、人畜排放进行分析,利用输出系数模型解析斧头湖的面源污染负荷时空分布及主要来源。结果表明:斧头湖流域2008～2015年面源总氮（TN）和总磷（TP）负荷输出分别从由原来的 2 915 和 178 t 增长至 3 252 和 202 t。城镇化发展使得农村耕地面积减少,耕地对TN的输出贡献比例降低,但是耕地化肥使用依然是TN最主要来源。城镇化使得居民区对面源贡献增大,特别是TP的贡献显著增加。随着人们生活水平的提高,畜禽养殖对面源污染的贡献也显著增加,应予以足够重视