长江三峡柑桔的冻害和热害（二）

本文从柑桔冻害和热害的危害因子和指标等级划分的研究和选取入手,着重探讨了长江三峡地区(湖北境内)两害显著的时空变化特征、差异与关联性及对柑桔生产的影响;揭示了80年代以来冬暖春热的重大气候变化是使两害向“两极分化”的根本原因;讨论了三峡水利工程对两害时空格局的可能调整及减灾原理;最后提出了可能的对策。     

飓风“桑迪＂的影响及启示研究

城市地区突发自然灾害常常会对给水排水设施造成不利影响。飓风“桑迪”于2012年10月29日登陆美国,多个东部城市出现大面积停电,缺水,交通中断以及罕见的城市内涝,造成重大人员伤亡和巨额财产损失,严重地影响了当地人们正常的生产和生活。从飓风“桑迪”对美国城市给水和排水系统造成的巨大破坏出发,并结合当地政府采取的紧急应对措施展开讨论,总结其中的经验教训及启示。     

三峡水库消落带土壤与优势植物淹水后对土-水系统汞形态的影响

三峡库区消落带落干期植被生长茂盛,蓄水后消落带被淹没,土壤-植物系统在长时间淹水情况下,随着体系内物理化学性质的改变,汞形态也会发生变化,从而对库区水生生态系统中汞含量以及形态带来一定的影响.为此,本研究选取三峡库区4种优势植物室内栽培,再进行室内模拟淹水试验,研究淹水后土壤、水体中甲基汞(Me Hg)以及其他形态汞的变化.结果表明,淹水过程中植物的存在有利于土壤Me Hg的生成,同时对上覆水不同形态汞浓度影响显著.狗牙根作为消落带优势种,由于其体内总汞及甲基汞含量较高,淹水后对土壤以及上覆水系统中甲基汞以及其他汞形态的影响最为明显.淹水第90 d,狗牙根+土+江水(B1)处理土壤Me Hg的含量最高,为(1 135.86±113.84)ng·kg~(-1),是不加植物的对照处理土+江水(CK2)中土壤Me Hg含量的2倍左右;上覆水总甲基汞(TMe Hg)、溶解态甲基汞(DMe Hg)、总汞(THg)、溶解态汞(DHg)和活性汞(RHg)均呈峰值偏左的抛物线状变化,在第30 d时达到峰值,其中B1处理上覆水TMe Hg、THg和DHg最高,分别为(2.88±0.06)、(40.29±2.42)和(35.51±3.77)ng·L~(-1),三者中溶解态汞是其主要存在形式.因此可以推测三峡库区消落带植物淹水后将增加水库汞污染负荷.     

Urbanisation and flood vulnerability in the peri-urban interface of Mexico City

Chronic flooding in the Chalco valley, state of Mexico, Mexico, is the outcome of past and present socio‐environmental changes which have taken place in Mexico City's south‐eastern peri‐urban interface. This flooding is the result of a complex interaction between urbanisation in an ex‐lacustrine area, permanent ecological deterioration and ground subsidence, poor sanitation and inadequate policy responses. Far from solving the flooding problem, short‐term policy responses have created increasingly unsafe conditions for current residents. A socio‐historical analysis of disasters reveals the importance of taking into consideration particular social actors and institutions in hazard generation and flood vulnerability over time. This paper analyses three aspects of this flooding: first, the importance of approaching floods from a socio‐historical perspective; second, the relation between urbanisation, former policies and flood risk generation; and third, current policy responses to and the failure in the risk management of La Compañía Canal.     

Recent Changes in Stream Flashiness and Flooding,and Effects of Flood Management in North Carolina and Virginia

The southeastern United States has undergone anthropogenic changes in landscape structure, with the potential to increase (e.g., urbanization) and decrease (e.g., reservoir construction) stream flashiness and flooding. Assessment of the outcome of such change can provide insight into the efficacy of current strategies and policies to manage water resources. We (1) examined trends in precipitation, floods, and stream flashiness and (2) assessed the relative influence of land cover and flow‐regulating features (e.g., best management practices and artificial water bodies) on stream flashiness from 1991 to 2013. We found mean annual precipitation decreased, which coincided with decreasing trends in floods. In contrast, stream flashiness, overall, showed an increasing trend during the period of study. However, upon closer examination, 20 watersheds showed stable stream flashiness, whereas 5 increased and 6 decreased in flashiness. Urban watersheds were among those that increased or decreased in flashiness. Watersheds that increased in stream flashiness gained more urban cover, lost more forested cover and had fewer best management practices installed than urban watersheds that decreased in stream flashiness. We found best management practices are more effective than artificial water bodies in regulating flashy floods. Flashiness index is a valuable and straightforward metric to characterize changes in streamflow and help to assess the efficacy of management interventions.     

Evaluating Infiltration Requirements for New Development Using Extreme Storm Transposition: A Case Study from Dane County,WI

Changes in land use and extreme rainfall trends can lead to increased flood vulnerability in many parts of the world, especially for urbanized watersheds. This study investigates the performance of existing stormwater management strategies for the Upper Yahara watershed in Dane County, WI to determine whether they are adequate to protect urban and suburban development from an extreme rainfall. Using extreme storm transposition, we model the performance of the stormwater infiltration practices required for new development under current county ordinances. We find during extreme rainfall the volume of post‐development runoff from impervious surfaces from a typical site would increase by over 55% over pre‐development conditions. We recommend the ordinance be strengthened to reduce vulnerability to flooding from future urban expansion and the likely increase in the magnitude and frequency of extreme storms.     

骨炭修复重金属污染土壤和降低基因毒性的研究

采用分级提取的方法研究了施加骨炭对污染土壤重金属的固定效果,结果表明,土壤施加10 mg·kg^-1骨炭后水溶态、交换态、碳酸盐结合态和铁锰氧化物结合态Pb的浓度都显著下降;而加入骨炭后土壤有机结合态Pb的浓度显著上升,表明骨炭可以吸附、固定土壤中的Pb,改变Pb的化学形态,降低Pb的生物可利用性.加入骨炭后土壤中水溶态和交换态Cd的浓度都显著下降,残渣态Cd的浓度明显上升.骨炭处理对土壤中Cu化学形态的影响和Pb相似,表明骨炭可以吸附固定土壤中的Cu.骨炭处理对Zn也有一定的固定效果,降低了土壤中水溶态的Zn.采用植物彗星实验研究了施加骨炭对土壤基因毒性的影响,表明加入骨炭后减轻了污染土壤对洋葱根尖细胞的DNA的损伤,降低了土壤污染对植物的基因毒性.生物评价和化学评价的结果均表明骨炭是重金属污染土壤的有效修复剂,能有效降低污染土壤中重金属的生物有效性和对植物的毒性.     

油田聚合物驱采出污水絮凝过程研究

针对油田聚合物驱（简称聚驱）采出污水,通过对油滴粒度分布、絮凝指数、油水分离特性和Zeta电位等指标的测定,研究了聚合物、温度、药剂以及搅拌强度对絮凝过程的影响,并探讨了影响聚驱采出污水油水分离效果的主要原因.结果表明,静电排斥并不是聚驱采出污水异常稳定的主要原因. 聚驱采出污水的油水分离特性与水驱采出污水相比存在显著差别,主要因为聚合物阻碍了小油滴的碰撞絮凝. 投加250mg/L由改性聚醚类破乳剂和弱阳离子絮凝剂复合而成的CHP-03药剂,可以有效克服聚合物的阻碍作用,获得92%的含油去除率. 该药剂在絮凝过程中并不依靠电中和机理来实现油滴的脱稳. 在现场条件下,温度的提高不能明显地促进油滴絮凝的有效性. 适当的高速搅拌可以加快絮体生长. 油滴之间的聚结破乳滞后于絮凝,絮凝的后期应避免剧烈搅拌,防止尚未聚结破乳的油滴重新分散.     

生态环境损害赔偿诉讼：定义与定位矫正

面对生态环境损害赔偿诉讼这一新型诉讼形式,准确把握其定义和定位至关重要。现有生态环境损害赔偿诉讼按国家自然资源所有权私权化路径进行制度构建,其现行定义为特殊私益诉讼,现行定位为环境行政替代工具。这种定义与定位导致其与环境公益诉讼割裂,运行序位上优先于环境民事公益诉讼,引起国家机关角色错位。生态环境损害赔偿诉讼与环境民事公益诉讼的诉讼标的相同,救济和保护的利益均为环境公益,其定义应回归公益诉讼本位;政府在环境公益保护上有着广泛的职权和手段,是环境公共治理的优先主体,仅在少数行政不能的情形下才有借助司法的必要性和合理性,其在定位上应作为环境行政执法的补充机制在有限范围内发挥作用。据此,生态环境损害赔偿诉讼在制度体系上应与既有环境民事公益诉讼置于同一诉讼系属统筹立法,在诉讼序位上应让位于社会组织提起的环境民事公益诉讼。