CPC/CaO_2氧缓释复合材料的制备及其释氧性能探讨

利用过氧化钙(CaO2)遇水释放氧气的特性,采用混合法将CaO2载入到磷酸钙骨水泥(CPC)中,并通过挤出-滚圆造粒方法制备出CPC/CaO2氧缓释复合材料,旨在为污染地下水的好氧生物修复技术提供一种长期、高效的供氧源。由X射线衍射(XRD)分析可知,通过固相反应制取的CPC主要成分为Ca5(PO4)3(OH)和Ca10(PO4)6(OH)2,具有较快的固化时间和固化效果;CPC/CaO2氧缓释复合材料分3个阶段进行释氧,其中2、3阶段分别符合一级和零级释氧动力学特征,且其释氧速率和释氧周期得到明显改善。本研究成果可用于实际地下水修复工程,解决污染地下水原位生物修复过程中溶解氧(DO)的输送问题。     

四城市空气粗、细颗粒物元素质量谱及富集特征

以武汉市 X荧光光谱分析数据为例 ,介绍了粗、细颗粒物中元素的质量谱及富集特征。并且 ,比较了广州、武汉、兰州、重庆四城市的污染元素及可能污染元素的某些富集特征     

偶极荷电静电凝并除尘器收尘机理及性能研究

提出一种高效去除微细颗粒物的偶极荷电静电凝并除尘装置,其主要由凝并区和收尘区组成.对其凝并收尘机理进行了分析,并对收尘性能进行了实验研究.结果表明,偶极荷电静电凝并系数高于库仑凝并系数;偶极荷电静电凝并除尘器中颗粒的凝并效果好,且在相同的条件下,其对微细颗粒物的除尘效率明显高于普通静电除尘器.     

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe(III) in the presence of citric acid

Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting H₂O₂ generation. The generation of HO? and O₂^-? in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO?, while O₂^-? strengthened the generation of HO? by promoting Fe(III) transformation in the CP/Fe(III)/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl^-, HCO₃^-, and humic acid (HA) inhibited TCE degradation to different extents for the CP/Fe(III)/CA system. Analysis of Cl^- production suggested that TCE degradation in the CP/Fe(III)/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe(III)-activated calcium peroxide for treating TCE contaminated groundwater.     

Effect of calcium supplementation on lead-induced genotoxicity and bioaccumulation in suckling Wistar rats

The study investigated the effect of calcium (Ca) supplementation on lead-induced toxicity in suckling male Wistar rats. The sucklings were exposed to lead acetate (5 mg/kg b wt./week) orally for a period of six weeks. The unexposed group of sucklings was the negative control. Out of the lead-exposed groups, two groups were supplemented with Ca at 3% and 6% as CaHPO₄ × 2H₂O in suspension in cow's milk. The artificial feeding regimen was followed for 7 h each day for 6 weeks. Sucklings exposed to lead with Ca supplementation recorded a significantly higher increase in body weight and a significant reduction of lead concentration in all tissues. The lead-induced histopathological alterations in the liver and kidney were also reversed with Ca supplementation. Sodium rhodizonate staining of liver sections showed distinct presence of lead granules in the group exposed to lead while the Ca-supplemented groups were comparable to the control. Lead exposure reduced the expression of rad 51 in the testis and liver which was markedly enhanced with Ca supplementation and was restored to the level in the control. Thus, Ca supplementation during the suckling period was effective in ameliorating the lead-induced toxicity.     

Upgrade of three municipal wastewater treatment lagoons using a high surface area media

Lagoon-based municipal wastewater treatment plants (WWTPs) are facing difficulties meeting the needs of rapid population growth as well as the more stringent requirements of discharge permits. Three municipal WWTPs were modified using a high surface area media with upgraded fine-bubble aeration systems. Performance data collected showed very promising results in terms of five-day biochemical oxygen demand (BOD₅), ammonia (NH₃) and total suspended solids (TSS) removal. Two-year average ammonia effluents were 4.1 mg·L^-1 for Columbia WWTP, 4 mg·L^-1 for Larchmont WWTP and 2.1 mg·L^-1 for Laurelville WWTP, respectively. Two- year average BOD₅ effluents were 6.8, 4.9 and 2.7 mg·L^-1, and TSS effluents were 15.0, 9.6 and 7.5 mg·L^-1. The systems also showed low fecal coliform (FC) levels in their effluents.     

两性高分子螯合絮凝剂和氯化钙对羟基亚乙基二膦酸预镀铜废水的去除性能

以羟基亚乙基二膦酸(HEDP)预镀铜废水为处理对象,考察两性高分子螯合絮凝剂(ACPF)和CaCl2对其处理效果.结果表明,单独使用ACPF或CaCl2,用量大,残余Cu2+和COD浓度均不能达到电镀污染物排放标准(GB21900—2008);将ACPF和CaCl2配合使用,Ca2+可与HEDP螯合生成HEDP—Ca沉淀,促进ACPF与Cu2+螯合;且Ca2+还可与废水中的酒石酸根离子形成溶解度很小的结晶,促进絮体的形成和沉降.因此,处理药剂的用量明显降低,Cu2+和COD残余浓度均能达标.适宜的处理条件为:弱碱或碱性条件下,ACPF投加量为3.0 g.L-1,CaCl2投加量为2.0 g.L-1,Cu2+和COD的去除率分别达99.74%和97.5%,残余浓度分别为0.335和25.27 mg.L-1.     

Effects of connectivity and spatial resolution of analyses on conservation prioritization across large extents

The outcome of analyses that prioritize locations for conservation on the basis of distributions of species, land cover, or other elements is influenced by the spatial resolution of data used in the analyses. We explored the influence of data resolution on prioritization of Finnish forests with Zonation, a software program that ranks the priority of cells in a landscape for conservation. We used data on the distribution of different forest types that were aggregated to nine different resolutions ranging from 0.1 × 0.1 km to 25.6 × 25.6 km. We analyzed data at each resolution with two variants of Zonation that had different criteria for prioritization, with and without accounting for connectivity and with and without adjustment for the effect on the analysis of edges between areas at the project boundary and adjacent areas for which data do not exist. Spatial overlap of the 10% of cells ranked most highly when data were analyzed at different resolutions varied approximately from 15% to 60% and was greatest among analyses with similar resolutions. Inclusion of connectivity or edge adjustment changed the location of areas that were prioritized for conservation. Even though different locations received high priority for conservation in analyses with and without accounting for connectivity, accounting for connectivity did not reduce the representation of different forest types. Inclusion of connectivity influenced most the outcome of fine-resolution analyses because the connectivity extents that we based on dispersal distances of typical forest species were small. When we kept the area set aside for conservation constant, representation of the forest types increased as resolution increased. We do not think it is necessary to avoid use of high-resolution data in spatial conservation prioritization. Our results show that large extent, fine-resolution analyses are computationally feasible, and we suggest they can give more flexibility to implementation of well-connected reserve networks.     

绿僵菌钙传感蛋白基因克隆及其与致病性的关系

通过筛选文库获得绿僵菌钙传感蛋白基因MaNcs1基因全长cDNA序列,并对其在致病过程中的作用进行了分析.结果显示,MaNcs1基因cDNA全长792 bp,开放阅读框为573 bp,编码190个氨基酸;采用RNA干扰技术下调该基因的表达后,对东亚飞蝗的生测实验表明,绿僵菌毒力显著下降,说明该基因与绿僵菌的致病性有关,为以后深入研究该基因的致病机制奠定了基础.     

碳酸盐岩山地土壤施用有机肥的溶蚀作用探讨

选择碳酸盐岩山地常见耕植、未耕植土层,通过概化制作为系列模拟柱试验土层,按当地正常施肥方法,向土层定量施入有机肥并浇灌及控制其它相关条件变化,再定期观测预埋土层不同深度碳酸岩石片的溶蚀量和土层其它指标的变化,作了施用有机肥的土中碳酸岩石溶蚀变化研究。结果揭示,在未耕植红黏土表层施用有机肥,大大减弱了土中碳酸岩石的溶蚀作用,且减弱程度随土深加大而降低。但对其下伏碱性岩粉层而言,施肥又引起了溶蚀量的微小增加变化;另在耕植土表层施用有机肥,对其土中碳酸岩石的溶蚀作用改变不大,且无论施肥与否溶蚀作用随土深加大又略显增大变化。而其下部红黏土中碳酸岩石的溶蚀量要远大于耕植土中的溶蚀量,并受施肥的影响较小。表明,农业施肥对未耕植土土中包被、包裹的碳酸岩石溶蚀影响较大,对下伏碱性岩粉层的层中、层下碳酸岩石的溶蚀影响较小。同时,施肥对耕植土土中、土下碳酸岩石的溶蚀影响不大。人类可采取禁令开垦较薄土层措施,来有效规避耕作施肥对土中碳酸岩石溶蚀作用的抑制,减少反石漠化的不利因素。此将为丰富碳酸盐岩山地成土演化理论和石漠化灾害的防治提供依据。