沉淀物和生物中U,Th和226Ra的联合测定

用放射化学法对U,Th,~(226)Ra等核素进行联合测定,国外已有不少报道,只是所用的分离方法和所测的介质不同而已。我国学者也做过一些这方面的工作。本工作建立了用三正辛胺-二甲苯萃取分离法对沉积物和生物样中U,Th和~(226)Ra的联合测定方法。 二、主要仪器与试剂     

离子选择电极法测定工业废水中氟化物的探讨

用离子选择电极法测定工业废水中的氟化物含量时,针对废水pH值跨度大,沉淀物较多的特点,对比在不同pH值和不同的样品移取方法下,氟化物含量的变化,从以上两方面加以控制,准确地测定其含量.     

鸟粪石法回收养猪废水中磷时pH对沉淀物组分的影响

采用鸟粪石沉淀法对养猪废水中的磷进行回收,应用红外光谱和X射线衍射法,并结合物料衡算研究pH变化对沉淀物组分的影响.结果表明,当pH由8.0升至9.0时,磷去除率从85%增加到94%;pH在9.0～11.0范围,磷去除率稳定在94%左右;当pH升高至12.0,磷去除率急剧下降至70％.沉淀物组分为鸟粪石(MgNH₄PO₄·6H₂O)、 钾型鸟粪石(MgKPO₄·6H₂O)、 Ca₃(PO₄)₂·xH₂O和Mg(OH)₂,不含有硫酸盐和碳酸盐.当pH<9.0,沉淀物组分主要为鸟粪石;pH在9.0～10.0范围时,鸟粪石含量降低,钾型鸟粪石、 Ca₃(PO₄)₂·xH₂O含量呈逐渐增加趋势;pH由10.0升至12.0时,鸟粪石含量急剧下降,Ca₃(PO₄)₂·xH₂O和Mg(OH)₂含量快速增加,而钾型鸟粪石快速增加并在pH 11.0达到最大后急剧下降.因此,回收养猪废水中的磷时要获得纯度高的鸟粪石产品,pH值应控制在8.0～9.0.     

Kinetics study of aqueous sorption of phenanthrene to humic acids and sediments

IntroductionThesorptionofhydrophobicorganiccontaminants(HOCs)onnaturalgeosorbentsplaysasignificantroleintheirtransport,degradationandultimatefateintheaquaticenvironment (Alexander,1995 ;Luthy ,1997;Weber,2 0 0 1) .Sincethelate 1970s,theorganicmatter(OM)ha…     

鸟粪石结晶法回收猪粪废水厌氧膜出水中磷的研究

采用厌氧膜生物反应器(AnMBR)处理猪粪废水时,发现消化液膜出水可发生自结晶沉淀反应,生成类似鸟粪石的含氮磷沉淀。试验通过控制初始pH使猪粪废水厌氧膜出水发生自结晶沉淀反应,考察了初始pH(8、9、10)对沉淀物组分及形态的影响。结果表明:初始pH为8、9、10时,磷去除率分别为30.8%、67.6%及87.7%;p H从8提高到9时,沉淀物中鸟粪石晶体的粒径变大且形态更完整;而pH为10时,颗粒较小且含钙沉淀较多;进一步分析各条件下沉淀物的晶体组分可知,初始pH为8、9时,沉淀物中晶体的主要成分为鸟粪石,而初始pH为10时,沉淀物中存在大量的含钙沉淀。因此,在该试验条件下,采用鸟粪石结晶法从该猪粪废水厌氧膜出水中回收磷的最佳初始pH为9。     

Degradation kinetics and products of triazophos in intertidal sediment

This work presents taboratory studies on the degradation of triazophos in intertidat sediment. The overall degradations were found to follow the first-order decay model. After being incubated for 6 d, the percentage of degradations of triazophos in unsterilized and sterilized sediments were 94.5% and 20.5%, respectively. Between the temperatures of 15℃ and 35℃, the observed degradation rate constant（kob,d） enhanced as the incubation temperature increased. Triazophos in sediment degraded faster under aerobic condition than under anaerobic one. The water content of sediment had little influence on the degradation when it was in the range of 50%-100%. The values of kobsd decreased with increasing initial concentration of triazophos in sediment, which could result from the microorganism inhibition by triazophos. Four major degradation products, o, o-diethyl phosphorothioic acid, monoethyl phosphorothioic acid, phosphorothioic acid, and 1-phenyl-3-hydroxy-1, 2,4-triazole, were tentatively identified as their corresponding trimethylsilyl derivatives with a gas chromatography-mass spectrometer. The possible degradation pathway of triazophos in intertidal sediment was proposed. The results revealed that triazophos in intertidal sediment was relatively unstable and coutd be easily degraded.     

Long range trans-Pacific transport and deposition of Asian dust aerosols

The deposition of Asian dust aerosols during their trails-Pacific Uansport might cause significant marine phytoplankton biomass increases.However,the knowledge of the trans-Pacific dust transport,deposition,and spatial distribution is still poor due to a lack of continuous and simultaneous observations in the Asian subcontinent,the north Pacific Ocean,and North America.The severe Asian dust storm during 6 to 9 April 2001 provided an opportunity to gain a better understanding of trans-Pacific dust transport and deposition,using a comprehensive set of observations from satellites,ground-based light detection and ranging,aircraft,and surface observation networks.The observations and model simulations outline the general pattern of dust transport,deposition,vertical profile,and spatial distribution.The following points were observed(1)the surface dust concentrations decreased exponentially with the increasing dust transport distance from 80°E to 120°W along the transport pathway;(2)the altitude of the dust concentration peak increased with increasing transport distance in the north Pacific region;and (3) the spatial distribution of dust deposition mainly depended on the trans-Pacific transport route.     

Heavy metal pollution in intertidal sediments from Quanzhou Bay, China

The concentrations of eight heavy metals （Cu, Zn, Pb, Cd, Cr, Ni, Hg, and As） in the intertidal surface sediments from Quanzhou Bay were determined to evaluate their levels and spatial distribution due to urbanization and economic development of Quanzhou region, southeast China. The ranges of the measured concentrations in the sediments are as follows： 24.8-119.7 mg/kg for Cu, 105.5-241.9 mg/kg for Zn, 34.3-100. 9 mg/kg for Pb, 0.28-0. 89 mg/kg for Cd, 51.1-121.7 mg/kg for Cr, 16.1-45.7 mg/kg for Ni, 0.17-0.74 mg/kg for Hg, and 17.7-30.2 mg/kg for As. The overall average concentrations of above metals exceed the primary standard criteria but meet the secondary standard criteria of the Chinese National Standard of Marine Sediment Quality. Several contents of Cu and Hg exceed the secondary standard criteria at some stations. The results of geoaccumulation index （Igeo） show that Cd causes strong pollution in most of the study area. There are no significant correlations among most of these heavy metals, indicating they have different anthropogenic and natural sources. Some locations present severe pollution by heavy metals depending on the sources, of which sewage outlets, aquatic breeding, and commercial ports are the main sources of contaminants to the area.     

Estimation of runoff and sediment yield in the Redrock Creek watershed using AnnAGNPS and GIS

Sediment has been identified as a significant threat to water quality and channel clogging that in turn may lead to river flooding. With the increasing awareness of the impairment from sediment to water bodies in a watershed, identifying the locations of the major sediment sources and reducing the sediment through management practices will be important for an effective watershed management. The annualized agricultural non-point sourcepollution(AnnAGNPS) model and newly developed GIS interface for it were applied in a small agricultural watershed, Redrock Creek watershed, Kansas, in this pilot study for exploring the effectiveness of using this model as a management tool. The calibrated model appropriately simulated monthly runoff and sediment yield through the practices in this study and potentially suggested the ways of sediment reduction through evaluating the changes of land use and field operation in the model for the purpose of watershed management.