电厂屏式过热器弯头开裂原因失效分析

通过外观检查、硬度、金相等检测方法,从金属管壁超温运行、蒸汽侧氧化行为、析出相及冷弯变形对组织性能影响等方面分析了某电厂1 000 MW超超临界机组屏式过热器弯头开裂原因,得出TP347HFG弯头开裂的主要原因是弯头组织富含较多的σ相、NbC等硬脆析出相,同时冷弯加工导致管子内部产生残余应力,加剧了弯头脆性开裂的倾向。     

辉光放电等离子体氧化降解水中邻苯二甲酸二丁酯

研究了辉光放电等离子体降解水中典型的环境内分泌干扰物邻苯二甲酸二丁酯(DBP)及降解过程中过氧化氢(H2O2)的生成规律。考察了电解质种类、共存污染物(甲醇、叔丁醇)及催化剂等条件对DBP降解及H2O2生成的影响。结果表明,在硫酸钠溶液中DBP降解效率和H2O2生成速率最高;甲醇、叔丁醇等共存污染物对DBP降解和H2O2生成有抑制作用;Fe2+,Fe3+和Cu2+对DBP的降解有催化作用,其催化效果为Fe2+>Fe3+>Cu2+。用高效液相色谱、离子色谱及气质联用仪等仪器分析了降解中间产物,提出了可能的降解机理。     

Biosorption mechanisms involved in immobilization of soil Pb by Bacillus subtilis DBM in a multimetal-contaminated soil

Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.     

碲化镉量子点Cd~(2+)释放对小鼠肝、肾组织毒作用的研究

探讨碲化镉量子点(cadmium telluride quantum dots,Cd Te QDs)Cd2+释放与其体内毒性之间的关系。将24只雄性ICR小鼠(24.7~26.8g)随机分为4组,每组6只,分别为0 nmol组(对照组)、5 nmol染毒组、50 nmol染毒组和500 nmol染毒组(以Cd2+的摩尔浓度计算)。采用尾静脉注射方式进行染毒,染毒组注射0.15 ml不同浓度的Cd Te QDs溶液,对照组注射同等体积的生理盐水。染毒24h后小鼠脱臼处死,计算脏器系数,进行血常规和血清生化指标分析以及肝、肾组织的病理组织学检查。选取金属硫蛋白(metallothionein,MT)作为生物体内游离Cd2+水平的生物标志物,通过酶联免疫吸附实验(ELISA)和免疫组织化学技术检测小鼠肝、肾组织中的MT水平。结果表明,各染毒组小鼠肝、肾脏器系数与对照组相比,差异无统计学意义(P0.05),尿素氮水平与对照组相比显著降低(P0.01)。随着染毒剂量增加,小鼠肝、肾组织病理改变逐渐加重,肝细胞可见不同程度的水性样变和肿胀;肾小管管腔水肿、肾上皮细胞水样变性,以及远曲小管水肿。染毒组小鼠肝、肾组织中MT的含量与对照组相比明显升高(P0.05),且随着染毒剂量增加MT表达增强。研究结果提示,Cd Te QDs对小鼠肝、肾组织具有一定的毒作用,其毒作用大小与Cd Te QDs降解释放的游离Cd2+含量呈正相关。     

Changes in heavy metal contents in animal feeds and manures in an intensive animal production region of China

The 360 feed and manure samples were collected from 150 animal farms in Jiangsu Province, China and analyzed for heavy metals. Concentrations of Zn and Cu in animal feeds were 15.9-2041.8 and undetected-392.1 mg/kg respectively, while Hg, As, Pb, Cd, and Cr in all feeds were below 10 mg/kg. Concentrations of Cu, Zn, and Cr in animal manures were 8.4-1726, 39.5-11379, and 1.0-1602 mg/kg respectively, while As, Cd, Hg, and Pb were 〈 10 mg/kg. The concentration of Cu, Zn, As and Cr in animal feed and manure were positively correlated （p 〈 0.001）, but the Cd, Hg, and Pb were not statistically correlated between the feed and the manure. Concentrations of Cu and Zn were highest in pig feed and manure, followed by poultry and dairy feeds and manures. During 1990- 2008, Cu, Zn, As, Cr, Cd contents increased by 771%, 410%, 420%, 220%, and 63% in pig manure, 212%, 95%, 200%, 791%, and -63% in dairy manure, and 181%, 197%, 1500%, 261, and 196% in poultry manure. Most of the increases occurred from 2002 to 2008, which reflects the extensive use of feed additives after 2002. In contrast, Pb and Hg in manures continuously decreased from 1990 to 2008. The results suggest that the heavy metal contents in animal manure have been greatly increased over 18 years and the contribution of manures to soil should be considered.     

经济新常态下的“十三五”环境压力预测

我国经济已经从高速增长转向中高速增长的新常态阶段,经济发展方式从规模速度型粗放增长转向质量效率型集约增长,产业结构从劳动密集型向资金密集型和知识密集型转换,经济发展动力从要素驱动、投资驱动转向创新驱动。经济新常态下,环境保护将迎来难得的历史机遇,同时也面临严峻的挑战。为了深入理解和准确把握经济新常态下我国"环境态"的发展特征,本文基于中长期环境经济预测模型定量测算了2020年我国社会经济、能源和水资源以及主要污染物排放趋势和特征。结果表明,"十三五"期间,我国能源和水资源消耗总量增长将趋缓,新增消耗量进入涨幅收窄期;产业转型升级加速将从源头上减轻新增污染减排的压力,主要大气和水污染物排放将进入高位平台期,排放强度将呈现高位回落。     

北京城市大气CO2浓度变化特征及影响因素

北京大气CO₂浓度日变化强烈,全年北京时间15:00时前后为全天最低值,最高值则出现在夜间,日变化幅度为23.2～39.0μmol·mol^-1,夏季和秋季日变化幅度比冬季和春季大.北京城区大气CO₂浓度季节变化明显,最大值出现在冬季,月平均浓度为421.5～441.0μmol·mol^-1;最小值则在夏季,月平均浓度367.4～371.6μmol·mol北京CO₂浓度的季节变化幅度明显高于附近的华北兴隆区域站和瓦里关山大陆本底站等的相应值,其原因是北京CO2浓度季节变化主要受人为取暖活动控制,同时植被的季节变化也起一定作用.1993～1995年北京大气CO₂浓度上升较快,平均增长率为3.7%·a^-1,1995年平均浓度达到最高,为409.7±25.9μmol·mol,随后缓慢下降.     

高硬度富锶地下水的软化沉淀-超滤膜联用工艺

针对一种高硬度富锶地下水,分别采用石灰和石灰-碳酸钠两种方法,利用药剂软化/超滤膜工艺对其进行软化处理,同时考察了药剂投量对出水锶含量的影响。结果表明,采用石灰软化/超滤膜法,Ca(OH)2最佳投加量为270 mg/L时,出水总硬度(以CaCO3计)由287.12 mg/L降低到96.44 mg/L,硬度去除率为66.41%,出水锶含量也由原水中的0.37 mg/L下降为0.21 mg/L;而采用石灰-碳酸钠软化/超滤膜法,Ca(OH)2和Na2CO3最佳投加量分别为270 mg/L、160mg/L时,出水总硬度降低到60.34 mg/L,硬度去除率达78.98%,锶含量仅为0.02 mg/L。2种处理方法出水总硬度均达到预期目标,石灰软化/超滤膜法可使出水锶含量满足富锶水的要求,而石灰-碳酸钠软化/超滤膜法则造成了对人体有益微量元素锶的大量损失。     

O3浓度升高对不同生长期冬小麦叶片抗氧化系统的影响

由于人口的快速增长,人类活动导致近地层O3浓度不断提高,O3浓度升高将对植物、动物和人体健康产生极大的危害.采用开顶式气室(OTC)原位实验方法,研究O3浓度升高对不同生长期冬小麦叶片抗氧化系统的影响,进而分析O3对植物的伤害机制.结果表明,O3浓度升高可导致冬小麦拔节期和抽穗期叶片超氧化物歧化酶(SOD)、过氧化物酶...     

滇黔桂地区土壤有机碳储量与影响因素研究

土壤有机碳(SOC)库在陆地生态系统中具有重要作用.由于土壤剖面数量和采用的土壤图比例尺等的限制,目前土壤有机碳库估箅尚存在很大不确定性.为了提高SOC库估算的精确性,利用798个土壤剖面及1:50万土壤图估算了滇黔桂地区(云南省、贵州省和广西壮族自治区)的SOC储量,并采用逐步回归分析和通径分析方法分析了影响SOC密度的主要因子.结果表明,滇黔桂地区表土层(0-20 cm)和土壤剖面(0-100 cm)的SOC储量分别为4.39 Pg和10.91 Pg;SOC密度分别为56.2Mg·hm-2和139.8 Mg·hm-2.高于全国平均水平.环境因子(海拔、经度、纬度、气温和降雨)、成土母质和土地利用方式对表土层和土壤剖面SOC密度变异性的解释度分别为37.9%和30.7%;环境因子为影响SOC密度的主要因子.环境因子中.气温对SOC密度的影响大干降雨,其中气温和降雨的变化分别主要由海拔和纬度的变化引起的.除气温和降雨外,还有其它随海拔或经纬度而变化的因子也对SOC密度产生显著影响,这种影响要大于降雨的影响.