铅锌尾矿砂污染下的岩溶土壤微生物群落碳源代谢特征

以广西阳朔思的村铅锌矿尾砂污染的水稻田、玉米地、柑橘园以及对照(旱地)土壤为研究对象,采用碳素利用法和18S rRNA变性梯度凝胶电泳技术探究岩溶区重金属污染下土壤微生物群落碳源代谢特征以及土壤真菌与土壤有机碳的交互关系.结果表明,广西阳朔思的村铅锌矿尾砂污染区土壤重金属总体含量(Pb、Zn、Cu、Cd)依次为:水稻田玉米地柑橘园对照;同时地累积综合指数显示该区重金属污染以Pb、Cd为主,其中Cd带来的环境风险最高.受Pb、Zn、Cu、Cd等重金属复合污染物影响,土壤微生物生物量碳、微生物熵和碳源代谢速率表现出随总体重金属质量分数增加而降低的变化规律,但土壤总有机碳质量分数却表现为:水稻田对照柑橘园或玉米地.DGGE结果进一步显示对照组土壤存在担子菌门多孔菌目Pycnoporus sp.ZW02.30,柑橘园和玉米地土壤存在镰刀菌属Fusarium solani和Fusarium oxysporum以及柑橘园土壤存在青霉属Penicillium decumbens.然而,上述参与淀粉、纤维素、半纤维素、木质素等糖类降解过程的真菌没有在水稻田土壤检出.加之,水稻田土壤微生物功能多样性指数和微生物熵最低而土壤有机碳质量分数最高,说明铅锌尾矿砂通过影响不同样地土壤微生物糖类代谢过程,进而调节土壤碳在微生物特别是真菌作用下的矿化速率.     

浑河流域底质类型对硅藻群落分布特征的影响

河流底质可以为硅藻提供附着的基质,不同的底质类型对硅藻群落结构有一定的影响.本研究对浑河流域上23个采样点位进行调查研究,并运用多响应置换过程、典范对应性分析、线性回归分析等,分析河流底质类型对硅藻群落的影响.多响应置换过程结果显示,苏子河、红河和英额河、浑河中游及浑河下游水系之间硅藻群落空间差异显著;香农多样性指数、均匀度指数与物种丰富度的平均值分别为2.57、0.69和15;典范对应性分析结果显示,IOS指数、电导率、总氮和总磷是显著影响硅藻群落结构的环境因子;相关分析结果显示,香农多样性指数、均匀度指数和物种丰富度与IOS指数呈正相关.本研究中,河流底质类型为大石块、鹅卵石等类型时,硅藻多样性较高;而底质类型为淤泥和细沙时,硅藻多样性较低.     

江西丰城生态硒谷土壤硒有效性及其影响因素

为了解丰城市生态硒谷土壤的供硒能力及其影响因素,通过实地调查采样,对丰城生态硒谷96个0~20 cm耕层土壤样品中硒含量、形态分布、重金属含量及部分土壤理化性质进行研究,并探讨与土壤硒有效性的关系。结果表明,该地区土壤全硒质量比变幅(541~831μg/kg)达到富硒土壤标准。易被生物利用的水溶态硒和可交换态硒质量比较少且在不同土壤样品中差异较大,变幅分别为10.30~38.23μg/kg和10.68~38.45μg/kg,且与土壤全硒有一定的相关性。土壤全硒、不同土地利用方式和土壤理化性质均对土壤硒的有效性产生影响,其中稻田土壤的供硒能力大于旱地,全P和速效P均与水溶态硒呈极显著正相关,在土壤硒有效性一定的条件下,全硒含量较高的土壤能够向作物提供较多的有效硒。     

2002-2014年我国煤矿重特大事故特征及发生规律研究

为了研究我国煤矿重特大事故的一般规律,分析了2002-2014年我国煤矿发生的421起重特大事故,得到我国煤矿重特大事故的基本特征.利用统计分析法从地域、类型、所有制3个维度综合分析了421起煤矿重特大事故.结果表明:山西、贵州、河南、黑龙江和湖南5个省份的重特大事故起数和死亡人数分别占全国总数的56.1％和56.8％,是我国需重点监管和治理的省份,并对山西、河南和黑龙江3省重特大事故频发的原因进行了分析;瓦斯事故和水害事故的发生起数及死亡人数占比分别为83.3％和86.3％,是需要重点防治的事故类型;国有重点煤矿重特大事故平均每起死亡人数为29.87,且近两年重特大事故起数和死亡人数均大幅度上升,是需要重点防范的对象;乡镇煤矿重特大事故起数及死亡人数下降速度均较快,但事故起数和死亡人数仍较多,是国家重点监控、治理的对象.     

CeO_2/Fe_2O_3对高浓度苯酚废水微波诱导的氧化催化

对高浓度苯酚废水提出了用复合催化剂CeO2/Fe2O3进行微波诱导催化氧化的降解方法,并与单一催化剂Fe2O3的催化氧化效果进行了比较,对两者的表观反应动力学进行了分析,结果表明复合催化剂的催化效果比单一催化剂的催化效果高15%以上,其主要原因是CeO2/Fe2O3复合物具有很强的催化能力和较高的干电流变活性,有利于电子的迁移和羟基自由基·OH的形成,从而有利于苯酚的氧化降解。     

基于总磷的长湖水环境容量核算

在对长湖流域水资源状况、水质现状、水文条件调查的基础上,根据水质目标的要求,利用纳污水体的概率型水环境容量模型,对基于总磷的长湖水环境容量进行了核算。结果表明：长湖的水环境容量是动态变化的,而模型的选取和参数的取值对概率型水环境容量的计算非常关键。通过计算分析得到长湖磷的概率水环境容量为：19％丰水期：41．9t／a-45．9t／a;49％平水期：31．8t／a～41．9Va;32％枯水期：11．8t／a～31．8t／a。     

集约农区不同土地利用方式对土壤养分状况的影响

选择山东省寿光市,通过野外调查和室内分析,利用数理统计软件SPSS,系统分析不同土地利用方式下土壤养分的分布特征、变异情况及其相关性,研究集约农区不同土地利用方式对土壤养分状况的影响。结果表明,在不同土地利用方式下,各养分含量分布存在明显规律。有机质均值的分布特征是菜地水浇地果园旱地盐碱地;全氮、碱解氮、速效钾、速效磷和有效锌均值的分布特征是菜地果园水浇地盐碱地旱地;土壤pH值、交换性镁均值的分布特征为盐碱地旱地水浇地果园菜地;交换性钙在不同利用方式中的含量为盐碱地旱地水浇地菜地果园;有效硼为果园菜地盐碱地水浇地旱地;有效铁为菜地果园水浇地旱地盐碱地;有效铜和有效锰均为果园菜地水浇地盐碱地旱地。水浇地、菜地和果园在各养分含量上差异较小,旱地和盐碱地在各养分含量上较为相似。除pH值外,其它12种土壤养分在不同土地利用方式下变异系数均较高,其中以速效磷的变异系数最大。土壤养分中除了交换性镁、有效硼与其它各养分之间的相关性较低外,其它养分之间基本为显著或极显著相关,其中pH值与其它各土壤养分均呈现显著或极显著负相关,有机质与其它各土壤养分均呈现显著或极显著正相关。     

Degradation and detoxification of microcystin-LR in drinking water by sequential use of UV and ozone

Microcystins (MCs) produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens.MCs pose a considerable threat to human health through tainted drinking and surface waters.Herein filtrated water from a waterworks in Harbin,China,was spiked with microcystin-LR (MC-LR) extracted from a toxic scum of microcystis aeruginosa,and the spiked sample waters were treated using UV irradiation with consequent ozonation process (UV/O3),compared with ozonation at a dose range commonly applied in water treatment plants,UV irradiation at 254 nm and UV irradiation combined with ozonation (UV+O3),respectively.The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay,which was utilized to evaluate the reduction in toxicity.Results indicated that in comparison to other three processes (O3,UV,and UV+O3),UV/O 3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L (below 1 μg/L),while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L.The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition,stabilizing the ozone residual.These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water.     

Characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater e uent

Constructed wetland (CW) is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary e uent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery wastewater e uent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the CW were non-apatite phosphorus (59%) and residual phosphorus (32%) suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW system and design.     

An in-depth analysis of self-reported cycling injuries in single and multiparty bicycle crashes in Denmark

Introduction: Cycling is one of the main forms of transportation in Denmark. However, while the number of traffic crash fatalities in the country has decreased over the past decade, the frequency of cyclists killed or seriously injured has increased. The high rate of serious injuries and fatalities associated with cycling emphasizes the increasing need for mitigating the severity of such crashes. Method: This study conducted an in-depth analysis of cyclist injury severity resulting from single and multiparty bicycle-involved crashes. Detailed information was collected using self-reporting data undertaken in Denmark for a 12-month period between 1 November 2012 and 31 October 2013. Separate multilevel logistic (MLL) regression models were applied to estimate cyclist injury severity for single and multiparty crashes. The goodness-of-fit measures favored the MLL models over the standard logistic models, capturing the intercorrelation among bicycle crashes that occurred in the same geographical area. Results: The results also showed that single bicycle-involved crashes resulted in more serious outcomes when compared to multiparty crashes. For both single and multiparty bicycle crash categories, non-urban areas were associated with more serious injury outcomes. For the single crashes, wet surface condition, autumn and summer seasons, evening and night periods, non-adverse weather conditions, cyclists aged between 45 and 64 years, male sex, riding for the purpose of work or educational activities, and bicycles with light turned-off were associated with severe injuries. For the multiparty crashes, intersections, bicycle paths, non-winter season, not being employed or retired, lower personal car ownership, and race bicycles were directly related to severe injury consequences. Practical Applications: The findings of this study demonstrated that the best way to promote cycling safety is the combination of improving the design and maintenance of cycling facilities, encouraging safe cycling behavior, and intensifying enforcement efforts.