挺水植物水田芥对镉的积累特性研究

通过前期的初步研究发现,挺水植物水田芥(Nasturtium officinale R.Br.)地上部分镉含量超过了超富集植物的临界值(100mg/kg),可能是镉超富集植物。为进一步了解水田芥在不同镉浓度梯度条件下的镉积累特性,通过盆栽试验研究了不同土壤镉浓度(0、25、50、75、100mg/kg)对水田芥生长特性、镉耐性和镉积累特性的影响。结果表明:随土壤镉浓度的增加,水田芥根系和地上部分镉含量增大,分枝数量、根系生物量、地上部分生物量、抗性系数及叶绿素SPAD值均呈降低的趋势。当土壤镉浓度大于0mg/kg时,随着土壤镉浓度的增加,水田芥的根冠比呈增加的趋势。土壤镉浓度为50~100mg/kg时,水田芥地上部分镉含量均大于100mg/kg,最大值为214.84mg/kg(土壤镉浓度为100mg/kg),地上部分富集系数(BCF)大于1,但转运系数(TF)小于1。在土壤镉浓度为50mg/kg时,水田芥地上部分镉积累量达到最大值,为192.233μg/株。因此,水田芥是一种镉富集植物,适合用于土壤镉污染浓度在50mg/kg以内的水田修复。     

鄱阳湖流域千年旱涝变化特点及R/S分析

为揭示鄱阳湖流域旱涝变化规律,预测未来变化,搜集整理了鄱阳湖流域地方志、奏折等古文献记载的旱涝记录,根据灾害现象、灾害后果、救灾情况等综合研判旱涝等级。对1160~1950s旱涝频次序列进行了变化周期分析。采用了R/S方法分析了年代际旱涝频次的Hurst指数,结合变化周期分析结果,对1950s以后鄱阳湖流域的旱涝频次变化趋势进行预测,采用基于1951~2010年器测降水量的SPI指数进行验证。研究结果表明:1160~1940s鄱阳湖流域及各子流域的干旱、洪涝频次呈波动变化,周期性变化明显,干旱、洪涝的3~6个年代周期段在整个时段内均非常显著,通过了95%的信度检验;鄱阳湖流域及各子流域的年代际干旱频次的Hurst指数普遍在0.7~0.8之间,洪涝在0.8~0.9之间。预测1950s后鄱阳湖流域年代际旱涝频次整体变化将呈阶段性上升趋势,经验证预测结果与实况较为吻合。     

R134a在水平环形通道内的凝结换热性能

在空气源热泵热水器中,对水平套管冷凝器环形通道内R134a的凝结换热特性进行实验研究。在冷凝器不同进水流量、进水温度时,实验测试了水平套管冷凝器凝结换热系数随热流密度、冷凝压力及干度的变化。实验工况为:冷凝器的进水流量为0.6~1.0 m~3/h,进水温度为15~60℃。实验结果表明:水平环形通道内R134a的凝结换热系数随热流密度和冷凝压力(温度)的升高而减小,当冷凝压力为1.3 MPa,热流密度由18 k W/m2增加至20.5 k W/m~2时,R134a的凝结换热系数减小了6.9%;当热流密度为15 k W/m~2,冷凝压力由1.78 MPa增大至1.83 MPa时,R134a的凝结换热系数减小了5.8%。R134a的局部凝结换热系数随干度的增大而增大,当冷凝压力为1.1 MPa,热流密度为18.3 k W/m~2,制冷剂干度由0.1增大至0.9时,R134a的局部凝结换热系数增大了24.4%。     

2000-2013年塔里木河流域生长季NDVI时空变化特征及其影响因素分析

受塔里木河流域综合治理工程实施和近期气候变化的影响,流域植被覆被时空分布产生一定的变化,厘清植被覆被与流域气候变化及人类活动的关系可以为塔里木河流域生态维护与治理提供科学参考依据。为此,论文以NDVI为指示因子,运用趋势分析、R/S分析、偏相关分析以及残差分析等方法,分析了2000-2013年综合治理工程期间NDVI的时空变化特征,并探讨及区分降水、气温气候因子以及人类活动对植被覆被变化的影响范围和程度,结果表明：1）2000-2013年,塔里木河流域植被生长季NDVI总体呈现增加趋势,增加速率为0.8%/10 a,平原区增速明显高于山区;且开都河-孔雀河流域山区、塔里木河干流的上、中游部分地区呈现比较明显的退化趋势。与此同时,塔里木河干流下游生长季NDVI持续改善。2）山区植被覆被变化主要受气候变化的影响,其中温度是高山区植被生长的主要限制因子,温度的增加促进植被的生长;中低山区以及出山口平原地区植被生长季NDVI变化是降水和温度共同作用的结果,且主要受降水的影响。降水与植被生长季NDVI变化呈正相关,温度与植被生长季NDVI变化呈负相关。3）平原绿洲区植被生长季NDVI增加主要是绿洲灌区面积不断增加以及塔里木河流域生态治理工程对植被恢复的结果,人类活动是该区域植被生长的主要驱动力。4）塔里木河干流生态闸工程在恢复下游植被的同时,也在一定程度上影响了上、中游地区的用水,尤其是导致中游植被出现退化趋势,退化速率约为0.1%/10 a。相关部门应进一步加强水资源的合理配置,充分发挥生态闸工程的水资源调度调控作用。     

Assessing development options in mining communities using stated preference techniques

In this paper, two key insights are generated about community development options using stated preference techniques. Surveys were conducted to identify how residents of a mining town in central Queensland, Australia, viewed options for the development of their township. First, residents were asked in a Choice Modelling experiment how worthwhile it would be to achieve some more attractive development options if it came at a cost to them. Second, residents were asked in a Choice Behaviour experiment how the different development options might influence their decision to stay or shift from the town in the future. The same development options were used in both experiments to facilitate comparisons between the two assessment forms.     

γ-Al2 O3 负载磷钨酸催化强化电化学法处理水中酸性大红3R的研究

采用浸渍法制备γ-Al2O3负载磷钨酸(HPW/γ-Al2O3)催化剂.运用红外光谱(FTIR)、X射线衍射(XRD)、热重-差热分析(TG-DTA)、扫描电镜(SEM)对催化剂的微观结构、形貌进行表征.结果表明杂多阴离子保持Keggin结构.将HPW/γ-Al2O3负载型催化剂填充于电化学反应器中,考察催化剂强化电化学法降解酸性大红3R染料的效果.研究表明,HPW/γ-Al2O3催化剂对酸性大红3R溶液显示了良好的催化活性,催化剂负载量为4.6%时,在pH为3、槽电压25.0 V、空气流速0.04 m3.h-1、极板间距3.0 cm反应条件下,60 min后,色度去除率达到97.6%.催化剂重复使用10次后,体系脱色率仍可达到80%左右,但会出现部分活性组分的流失现象.采用可见-紫外光谱对反应中间产物进行定性分析显示,在脱色反应过程中,染料分子中的共轭体系已基本被破坏.     

近49年中国北方典型强沙尘暴事件的分形特征与R/S分析

通过对1954-2002年我国北方的典型强沙尘暴事件的分形研究发现：该时间序列具有明显的分形特征。其饱和关联维数为3．34．说明要恰当描述其变化特征。进行动力系统建模，至少需要4个状态变量；该时间序列的Kolrnogorov熵近似为0．1142．说明该混沌动力系统的平均可预测时间尺度为8～9a。R／S分析表明。Huvst指数能够较好的表征我国北方典型强沙尘暴事件的发生规律，可以借此推断未来相应时间段中国北方强沙尘暴事件的变化趋势。     

1950～1997年我国洪涝灾害成灾面积的分形特征研究

运用分形理论对1950～1997年我国洪涝灾害农田成灾面积序列进行了研究。分析结果表明，洪涝灾害系统的变化具有分形特征，农田成灾面积时间序列的平均可预测时间尺度为8～9年；同时运用R／S分析方法对1950～1997年中各时段农田成灾面积的变化趋势进行了测算，测算结果与实际农田成灾面积的变化趋势十分吻合，表明上述方法是进行洪涝灾害系统分形研究的有效途径。     

Human serum paraoxonase gene polymorphisms and association with chronic symptoms of pesticide toxicity in Indian farmers

The association between PON1 (serum paraoxonase) genotype and symptoms of pesticide toxicity was examined in a total of 268 farm workers in Andhra Pradesh, India. Approximately 140 of the farm workers who did not report at least two of the symptoms of chronic toxicity, such as abdominal pain, nausea, dizziness, headache, drowsiness, fatigue, tremors of fingers, numbness, or limb weakness were categorized as controls. The remaining 128 farmers showed 2 or more of the above symptoms. All the farm workers were genotyped for polymorphisms of PON1 gene at amino acid positions 55 (exon 3) and 192 (exon 6). A decrease in the percentage of high-activity genotypes at both L55M and Q192R was observed in the farm workers reporting symptoms of pesticide toxicity. When combined genotype distribution at both exons was analyzed, a marked increase in the percentage of low-activity genotypes LLQQ, LMQQ, MMQQ, and MMQR was also observed in symptomatic farmers compared to controls. Age, working years, smoking, duration of exposure, and alcoholism were not statistically significant when compared to symptoms of chronic toxicity. Our findings suggest that L55M and Q192R gene polymorphisms influence the variable susceptibility of farmers to pesticide; and thus may be considered a useful biomarker of genetic susceptibility in assessing an individual's risk of pesticide exposures.     

The impact of flooding on property prices: A repeat-sales approach

In this paper we use a repeat-sales model to analyse the price path of properties affected by flooding in England between 1995 and 2014. Our dataset contains information on 4.8 million houses with at least one repeat-sale. This database is merged with high-definition GIS data delineating the spatial extent of all recorded flood incidents in England covering a total area of 2,654 km². Our results show that immediately after a flood event the price of property in a postcode entirely inundated by inland flooding is on average 24.9% lower than non-flooded property, whereas for property in a postcode entirely inundated by coastal flooding the price reduction is 21.1%. Nonetheless, we find that this discount is short-lived and the discount is no longer statistically significant for properties affected by inland flooding after 5 years, which falls to just 4 years for properties affected by coastal flooding. For lower-priced properties however, the post-flood price discount can be observed up to 6–7 years for both inland and coastal flooding. The magnitude of the impact also depends on the characteristics of the properties, the characteristics of the flood and the existence of flood protection assets.