离子色谱法测定地下水中有机氮

本文探讨了K_2S_2O_8氧化离子色谱法测定有机氮的实验条件,考察了淋洗剂离子价态及淋洗剂总离子强度对低浓度NO_3~-与高浓度SO_4~2-分离的影响;测定了11种含氮有机化台物有机氮的回收率。本法测定地下水中有机氮的结果与经典蒸馏法结果较为一致,具有操作简便、快速、准确,效率高的特点。     

NaCl型油田水中I^-的离子选择电极法测定

采用了NaCl溶液为离子强度调节剂(TISAB),离子选择电极法测定NaCl型油田水中I-离子的含量,并对该方法进行了测定条件实验的研究。标准曲线在7.94×10-6～1.00 mol/L范围内呈良好的线形关系,相关系数R2=0.999 5,平均回收率为98.9%,RSD(n=6)=1.0%,实验结果表明,该方法测定NaCl型油田水中的I-简便、快速、准确。     

A novel high-resolution small ion spectrometer to study ion nucleation of aerosols in ambient indoor and outdoor air

An electrically based ion spectrometer is described, capable of measuring particle sizes and mobilities from molecular ions (small ions) to aerosol particles across a size range of 0.4 to 30 nm in diameter. It consists of a single cylindrical capacitor divided into three electrically insulated sections. The current arriving at the central section is measured by an electrometer and represents the ion flux over a known range of mobilities determined by the applied voltage. The applied voltage is scanned in steps to measure the ion fluxes over a large number of overlapping mobility ranges. The recorded signal and the response function of the instrument are unfolded using a maximum entropy procedure to give a high-resolution measured mobility spectrum. The maximum entropy approach offers a considerable improvement over traditional aspiration collectors and can approach the resolution of a drift tube system. In this way, the spectrometer successfully overcomes the diffusion limit to small ion resolution. Illustrative spectra are shown, demonstrating for the first time the presence of some resolved structure within the small ion spectrum at the highest mobilities. It is demonstrated that the actual mobility spectrum of small ions falls in the range 0.8–2.0 × 10⁻⁴ m² V⁻¹ s⁻¹. This represents a narrower range than that previously measured which is attributed to improved spectral resolution in the present work.     

古尔班通古特沙漠生物结皮小尺度分异的环境特征

古尔班通古特沙漠广泛存在的生物结皮,对地貌部位有极强的选择性分布,其实质是生物对环境条件综合适应的一种生态表现。2002年3~11月在个体沙丘表面初步开展了生物结皮类型小尺度环境分异规律研究。结果表明:苔藓结皮、地衣结皮和藻类结皮依次分布于垄间、沙垄两坡中部和坡上部,从垄间往垄顶,生物结皮盖度逐渐减小,厚度变薄,抗压性减弱。苔藓结皮分布区的物质组成以细沙和极细沙为主,春季表层土壤水分在5%以上,短命植物广泛发育,基质稳定;坡中部的地衣结皮分布区以细沙为主,春季表层土壤水分在4%左右,短命植物亦有广泛分布,地表受风沙活动影响较小;沙垄上部和顶部的藻类结皮分布区,是沙垄表面活动性最强和土壤水分最差的区域,物质组成以中沙为主,高等植物中白梭梭为优势种,可见藻结皮是三类结皮中最能适应恶劣环境的生物结皮类型。     

自然水体采集的生物膜上铁、锰氧化物的萃取分离

采用选择性萃取分离技术对自然水体采集的生物膜上铁、锰氧化物进行萃取分离研究,考察该技术的适用性。参考人工培养生物膜的萃取方法,分别用NH₂OH·HCl和Na₂S₂O₄为萃取剂选择性萃取生物膜上的锰氧化物和铁、锰氧化物。实验中分别依次只改变萃取剂浓度、萃取液酸度或萃取时间,保持其它两个因素不变,分别考察这三个因素对萃取效果的影响,从中选出对铁、锰氧化物萃取率高而对有机质影响小的条件为最佳条件。用选定的最佳条件对不同时间和地点采集的生物膜进行萃取,发现对目的组分的萃取率可达70.8%~94.6%,而对非目的组分的影响很小（3.3%~11.0%）,满足萃取分离的要求。这说明选择性萃取技术可以广泛应用于自然水体采集的生物膜上铁、锰氧化物的萃取分离。     

敦煌某地铁矿中磁性铁的化学物相分析

本文选用HAC—H_2O_2和HCl—NaHCO_3作为选择性溶剂,对敦煌某地铁矿中磁性铁的化学物相分析进行了研究,将磁性铁物相从传统1项细化为3项,测定了磁性铁相态中磁黄铁矿、假象赤铁矿、磁铁中铁的含量。使用国家标准物质GBW07272对方法进行了评价,分析结果与标准值或参考值吻合良好(RE为0.28%~4.75%,RSD为0.13%~5.59%)。方法简单、准确。     

盐酸及乙酸介质中的碳酸盐岩溶蚀表面特征及机理——以南堡凹陷为例

为了研究酸性条件下碳酸盐岩的溶蚀表面特征及机理,以南堡凹陷及周边凸起区10个典型碳酸盐岩样品为研究对象,进行乙酸和盐酸溶液的溶解实验,并通过扫描电镜观察样品的溶蚀特征。结果显示,岩石结构和矿物成分的选择性溶蚀,是碳酸盐岩溶蚀过程中的主要作用形式;方解石和白云石均存在特有的溶蚀现象,即"溶蚀晶锥"方解石和"蜂窝状"白云石,为晶体选择性溶蚀的产物;表生条件下,灰岩中少量白云石的加入能够增加方解石的溶解度,白云石的含量上限为13%,超过该界限,随白云石含量的增加,溶蚀作用减弱。     

Effect of Cu toxicity at different salinity on selective group of juvenile pompano Trachinotus ovatus

Effects of copper toxicity and salinity shock on selective group of juvenile pompano Trachinotus ovatus were investigated.The fish were exposed to different Cu2+ concentrations of 0(blank),0.02(C1),0.05(C2),0.10(C3),and 0.15 mg·L–1(C4)at a salinity of 10‰ or 40‰ for 96 h,with the salinity of 29‰ as the control.The results showed that the effects of the acute salinity stimulation to survival rates of pompano between control(29‰)and lower or higher salinity for 96 h were not significant(p0.05).However,the survival rates in each treatment were decreased with the increase of Cu2+ concentration.The dominant factor influencing body moisture of the fish was salinity,and there was no sign that body moisture was correlated with exposure to Cu2+.The gill lamellas in high level of Cu2+ concentration(C4 treatments)were abnormal under the salinity of 40‰ and extremely curly under the salinity of 10‰.Hemorrhage in gill was observed in the two C4 treatments.Under transmission electron microscope,pillar cells in gill lamellas appeared deformed and ruptured in some areas of the epithelia in the higher concentration of Cu2+,resulting in the death of the fish due to the destruction of gill tissue,elevation of the arithmetic mean distance from water to blood,the decrease of oxygen diffusion capacity,and other physiological functions.These findings indicate that the pompano might suffer much more pressure when encountered with Cu2+ pollution and low salinity.     

Physiological Responses of Halophyte Suaeda salsa to Water Table and Salt Stresses in Coastal Wetland of Yellow River Delta

Soil salinity and waterlogging are two major environmental problems in estuarine wetlands. The objective of this study was to investigate the effects of salt stress, water table, and their combination on growth, chlorophyll content, antioxidant system, and ion accumulation in Suaeda salsa plant, which is the pioneer plant in coastal wetland of the Yellow River Delta (YRD). The results showed that plant height, number of branches, and biomass were significantly affected by water table and salt stress. With enhanced salt stress, the ratio of leaf to total biomass increased and the ratio of root to total biomass decreased. The contents of Chl‐a, ‐b, Chl‐a + b, and carotenoids (Car) decreased significantly with increasing soil salinity and the water table level. Salt stress enhanced the activity of superoxide dismutase (SOD) and catalase (CAT), but reduced the content of protein. With the lowering water table level, the activity of CAT and protein content increased, and activity of SOD decreased. Na⁺ and Cl^? content were up‐regulated with increasing salt stress (NaCl), whereas, the contents of other cations (K⁺, Ca²⁺, and Mg²⁺) and anions ( and ) were decreased. In summary, the results indicated that the S. salsa plants could adapt to the adverse soil environments through modifying their growth and physiology status at the highly saline and intertidal zone, such as the YRD estuarine wetlands, and also could be used as a bio‐reclamation plant to decline the high salt in saline soils.     

Vertical mixing of gravel over a long flood series

Vertical sediment exchange is a fundamental component of bedload transport in gravel‐bed channels. This paper describes the characteristic depth of exchange achieved over a long flood series. Analysis is based on 11 recoveries of magnetically tagged gravels deployed in Carnation Creek, Canada, completed between 1990 and 2008. Vertical grain exchange mixes gravels throughout the streambed relatively rapidly. Within one to eight floods the mean burial depth approaches two times the surface layer thickness, quantified by the 90th percentile of the size distribution. Finer gravels are mixed more rapidly into the bed than coarser gravels. Both active and passive grain exchanges throughout most of the bed produce the overall vertical distribution of marked grains. Gravel exchanges exhibit fairly consistent patterns once tracers are well mixed by large floods. Results highlight the role of flood sequence in determining exchange depths, support the notion of an upper limit to exchange, and underscore the importance of passive grain exchange. Copyright © 2011 John Wiley & Sons, Ltd.