Integrated removal of NO and mercury from coal combustion flue gas using manganese oxides supported on TiO2

A catalyst composed of manganese oxides supported on titania(MnO_x/TiO_2) synthesized by a sol–gel method was selected to remove nitric oxide and mercury jointly at a relatively low temperature in simulated flue gas from coal-fired power plants. The physico-chemical characteristics of catalysts were investigated by X-ray fluorescence(XRF), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS) analyses, etc. The effects of Mn loading,reaction temperature and individual flue gas components on denitration and Hg~0 removal were examined. The results indicated that the optimal Mn/Ti molar ratio was 0.8 and the best working temperature was 240°C for NO conversion. O_2 and a proper ratio of [NH_3]/[NO]are essential for the denitration reaction. Both NO conversion and Hg~0 removal efficiency could reach more than 80% when NO and Hg~0 were removed simultaneously using Mn0.8 Tiat 240°C.Hg~0 removal efficiency slightly declined as the Mn content increased in the catalysts. The reaction temperature had no significant effect on Hg~0 removal efficiency. O_2 and HCl had a promotional effect on Hg~0 removal. SO2 and NH_3were observed to weaken Hg~0 removal because of competitive adsorption. NO first facilitated Hg~0 removal and then had an inhibiting effect as NO concentration increased without O_2, and it exhibited weak inhibition of Hg~0 removal efficiency in the presence of O_2. The oxidation of Hg~0 on Mn O x/TiO_2 follows the Mars–Maessen and Langmuir–Hinshelwood mechanisms.     

Patterns of Livestock Predation by Carnivores: Human–Wildlife Conflict in Northwest Yunnan, China

Alleviating human–carnivore conflict is central to large carnivore conservation and is often of economic importance, where people coexist with carnivores. In this article, we report on the patterns of predation and economic losses from wild carnivores preying on livestock in three villages of northern Baima Xueshan Nature Reserve, northwest Yunnan during a 2-year period between January 2010 and December 2011. We analyzed claims from 149 households that 258 head of livestock were predated. Wolves (Canis lupus) were responsible for 79.1 % of livestock predation; Asiatic black bears (Selenarctos thibetanus) and dholes (Cuon alpinus) were the other predators responsible. Predation frequency varied between livestock species. The majority of livestock killed were yak–cattle hybrids or dzo (40.3 %). Wolves killed fewer cattle than expected, and more donkeys and horses than expected. Wolves and bears killed more adult female and fewer adult male livestock than expected. Intensified predation in wet season coincided with livestock being left to graze unattended in alpine meadows far away from villages. On average, carnivore attacks claimed 2.1 % of range stock annually. This predation represented an economic loss of 17 % (SD = 14 %) of the annual household income. Despite this loss and a perceived increase in carnivore conflict, a majority of the herders (66 %) still supported the reserve. This support is primarily due to the benefits from the collection of nontimber resources such as mushrooms and medicinal plants. Our study also suggested that improvement of husbandry techniques and facilities will reduce conflicts and contribute to improved conservation of these threatened predators.     

外源褪黑素对As~(3+)胁迫下水稻种子萌发的影响

本文研究了添加外源褪黑素对As~(3+)胁迫下水稻种子萌发及生理指标的影响。结果表明:添加外源褪黑素能促进As~(3+)胁迫下水稻种子的萌发,提高水稻的发芽势和发芽率,促进水稻幼苗的生长。当As~(3+)浓度为100μmol·L~(-1)时,添加100μmol·L~(-1)褪黑素能使水稻种子发芽率和总根长比对照分别提高57.1%和50.0%。添加褪黑素能显著提高As~(3+)胁迫下水稻幼苗中抗氧化酶系统过氧化氢酶(CAT)、过氧化物酶(POD)活性和超氧化物歧化酶(SOD)的活性,并降低水稻幼芽中丙二醛(MDA)的含量。当As~(3+)浓度为100μmol·L~(-1)时,添加50μmol·L~(-1)和100μmol·L~(-1)褪黑素导致水稻幼芽中POD活性比对照处理分别提高57.5%和114.8%,CAT活性提高29.4%和53.8%,SOD活性提高31.5%和56.0%,丙二醛含量比对照处理降低16.5%和31.9%。添加褪黑素也能显著提高As~(3+)胁迫下水稻的根系活力,当As~(3+)浓度为100μmol·L~(-1)时,50、100μmol·L~(-1)褪黑素处理后根系活力比对照分别提高42.4%和124.1%。这说明添加外源褪黑素可缓解As~(3+)胁迫对水稻的脂质过氧化损害,有效降低As对水稻内膜的破坏,显著缓解As污染对水稻的毒害作用。     

苏南太湖地区乡镇工业水污染综合防治研究

分析了苏南太湖地区迅猛发展的乡镇工业对水环境造成的污染,并提出了综合防治对策和意见:①利用水环境容量,合理布局乡镇工业;②合理调整行业结构;④积极开展生产全过程的排污控制;④认真进行废水治理,切实加强环境管理。     

坚硬顶板综采工作面推进速度对矿压规律影响研究

以顾桥煤矿坚硬顶板综采工作面工程地质条件为背景,运用理论分析、数值模拟和现场实测手段,分析了开采速度对工作面覆岩运动、围岩破坏、应力分布和液压支架承载特性的影响。研究结果表明:1个周期来压内工作面落煤引起的岩梁刚性回转下沉量是一定的,工作面作业循环时间引起的岩梁蠕变下沉量与岩梁刚性回转下沉量呈正比,加快工作面推进速度仅减少围岩体蠕变引起的岩梁下沉部分。工作面开采速度增加,覆岩塑性区发育范围减小,煤壁应力集中位置变浅、应力集中系数变小。工作面快速推进时,液压支架承载多为2次増阻和3次増阻,支架工作阻力较小;缓慢推进时,液压支架承载多为1次急增阻,载荷近似呈线性增长,支架工作阻力较大。     

淮南矿区道路环境大气颗粒物重金属污染特征及来源解析

为了解煤矿开采区道路环境中大气颗粒物重金属元素的污染特征及来源,于2016年12月(采暖期)和2017年5月(非采暖期)分别采集了淮南潘集矿区交通主干线周围大气颗粒物样品,采用电感耦合等离子体质谱(ICP-MS)测定了As、Cd、Hg、Mn、Pb、Cu、Zn、Ni、V等9种重金属元素以及参比元素Al的含量,并利用富集因子法和因子分析法解析了其来源。结果表明:(1)Zn、Mn、Pb含量较高,占所测重金属元素的82%(质量分数)以上;采暖期总悬浮颗粒物(TSP)、PM10和PM2.5中重金属含量总体上均高于非采暖期。(2)富集程度较高的元素有Pb、Cd、Hg,随着颗粒物粒径减小,各重金属元素的富集因子呈现增大趋势。(3)通过因子分析法得出,潘集矿区道路环境中重金属主要来源为交通排放、煤炭燃烧和扬尘等。     

潮汐河网水质数学模型

以南通市濠河为例,建立了潮汐河网水质数学模型,并提出了参数估算的方法。所建模型可用作潮汐河网地区进行水污染控制、水质管理、评价、规划的工具。     

A case study of Asian dust storm particles: Chemical composition, reactivity to SO2 and hygroscopic properties

Mineral dust comprises a great fraction of the global aerosol loading, but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties. In this work, a case study characterizing Asian dust storm particles was conducted by multiple analysis methods, including SEM-EDS, XPS, FT-IR, BET, TPD/mass and Knudsen cell/mass. The morphology, elemental fraction, source distribution, true uptake coefficient for SO₂, and hygroscopic behavior were studied. The major components of Asian dust storm particles are aluminosilicate, SiO₂ and CaCO₃, with organic compounds and inorganic nitrate coated on the surface. It has a low reactivity towards SO₂ with a true uptake coefficient, 5.767×10^-6, which limits the conversion of SO₂ to sulfate during dust storm periods. The low reactivity also means that the heterogeneous reactions of SO₂ in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles.     

水稻不同生育期土壤砷形态分布特征及其生物有效性研究

采用田间原位试验和Tessier连续提取方法,在水稻（Oryza sativa L.）不同生育期研究了重金属复合污染高、中、低3个水平下的土壤砷的形态分布特征及其生物有效性。结果表明：在水稻不同生育期中,土壤各种形态的砷质量分数均表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤;土壤中砷在水稻整个生育期均以残留态为主,占90%以上,交换态砷所占比例最低,不到0.5%;不同形态砷之间大都显著正相关,但是两种有效性较高的砷形态（交换态和碳酸盐结合态）与有机态砷之间的相关性较差;土壤砷的生物有效性表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤,且随着水稻生育期的延长,土壤砷的生物有效性逐渐升高。     

长江流域洪灾与生态破坏的关系浅析:Ⅱ生态破坏导致洪灾加剧

与长江１９５４ 年洪灾相比较,１９９８ 年洪灾具有“中水量、高水位、大灾害”的特征。流域内原始森林的过量采伐、大量湖泊的消亡、河道的普遍淤塞等生态系统的破坏引起了长江产流、汇流、洪水调蓄、行洪等水文条件的严重恶化。这是长江流域洪灾频繁,灾情加重的主要原因。