酸法地浸采铀的地下水生态环境问题

本文综述了利用酸法地浸采铀对采铀区及其周围地下水生态环境的影响方式、影响程度以及针对这些影响所采用的各种治理手段和效果。并就我国刚刚起步不久的酸法地浸采铀中地下水生态环境的保护和恢复,提出了一些建议。     

亚南极冰川雪冰内MSA的季节变化(英)

Methanesulphonate was investigated as a potential contributor to the sulphur budget based on the analysis on Antarctic snow/ice from Coffins Ice Cap, King George Island (62°10' S, 58°50,W). The anion was found to be present at a mean concentration of 0. 17 μeq. L-1 with a maximum of 0.73 μeq. L-1. A distinct seasonal variation exists in the top 10 m of the core, equivalent to more than two years of deposition. Dating resulted from δ18O profile suggests that the principal peaks of methanesulphonate are associated with snow deposited in autumn and secondary peaks in spring. The seasonal patterns of methanesulphonate in the subantarctic snow displays a phase difference from that observed in marine air from low and middle latitudes.     

山西孙家庄中酸性杂岩体及其邻近地区的找矿远景评价

通过“面型”岩石测量和多子样剖面岩石测量,对山西孙家庄中酸性杂岩体作出找矿远景评价,并对其邻近地段进行矿化追踪。确定该岩体的主要指示元素和伴生元素,圈出以Cu为主的斑岩矿化多元素组合异常,在Cu异常浓集中心发现斑岩矿化。孙家庄岩体周围地区,存在斑岩型矿化—接触交代矿化—热液多金属矿化的环带状分布模式。     

有机酸对高岭石形成影响的模拟试验研究

利用富里酸、胡敏酸和盐酸与天然矿物－长石、蒙脱石和云母在常温常压下进行反应,探讨矿物溶解及高岭石形成机理。实验表明富里酸对这些矿物具有较大的溶解能力,其原因是由于形成了具有较大溶解度和活动性的有机硅和有机铝复合体。在中性－碱性条件下有利于有机硅复合体的形成,酸性条件下有利于有机铝复合体的形成。在富里酸作用下,蒙脱石和云母分别在４个月和８个月有少量转化成高岭石,说明层状硅酸盐矿物比架状硅酸盐矿物更易     

Humic Ion-Binding Model VI: An Improved Description of the Interactions of Protons and Metal Ions with Humic Substances

Humic Ion-Binding Model VI, a discrete site/electrostatic model of the interactions of protons and metals with fulvic and humic acids, is applied to 19 sets of published data for proton binding, and 110 sets for metal binding. Proton binding is described with a site density, two median intrinsic equilibrium constants, two parameters defining the spread of equilibrium constants around the medians, and an electrostatic constant. Intrinsic equilibrium constants for metal binding are defined by two median constants, log K_MA and log K_MB, which refer to carboxyl and weaker-acid sites respectively, together with a parameter, LK₁, defining the spreads of values around the medians. A further parameter, LK₂, takes account of small numbers of strong binding sites. By considering results from many data sets, a universal average value of LK₁ is obtained, and a correlation established between log K_MB and log K_MA. In addition, a relation between LK₂ and the equilibrium constant for metal-NH₃ complexation is tentatively suggested. As a result, metal-binding data can be fitted by the adjustment of a single parameter, log K_MA. Values of log K_MA are derived for 22 metal species. Model VI accounts for competition and ionic strength effects, and for proton-metal exchange.     

Measurements of Reaction Coefficients of NO2 and HONO on Aerosol Particles

The reaction coefficients of nitrogen dioxide and nitrous acid with monodisperse sodium chloride and ammonium sulphate aerosols have been measured in a flow reactor at atmospheric pressure. These experiments were performed at relative humidities above and below the deliquescence points of both aerosols (r.h. 50 and 85%) at 279 K. The results for NO₂ afford a reaction coefficient in the range (2.8–10) × 10^-4 and for HONO, (2.8–4.6) × 10^-3. For both species, there appears to be an enhancement of the reaction coefficient on sodium chloride aerosol at 50% r.h. The results are compared with reaction coefficients determined by other experimental methods. A good agreement is found for both gases between this method and the coated denuder method previously developed in our research laboratories (Msibi et al., 1993) and with the majority of other published data for NO₂. In the case of HONO, our estimate of reaction coefficient is smaller than, or at the lower limits of the ranges reported by other published studies.     

Fast Oxidation Reaction of Nitrite by Dissolved Oxygen in the Freezing Process in the Tropospheric Aqueous Phase

Nitrite oxidation in the tropospheric aqueous phase by freezing was evaluated by freezing a field sample. Nitrite oxidation by dissolved oxygen in the freezing process is much faster than by other oxidation processes, such as reactions with ozone, hydrogen peroxide or dissolved oxygen in an aqueous solution at pHs 3 to –6. At pH 4.5 and 25°C, the lifetime of nitrite in the aqueous phase is ca. 1 hr in oxidation by ozone (6×10^-10 mol dm^-3), ca. 10 hr in oxidation by H₂O₂ (2×10^-4 mol dm^-3), and 7.5 hr (Fischer and Warneck, 1996) in photodissociation at midday in summer. Under the same conditions at a temperature below 0°C, the lifetime of nitrite in the freezing process is estimated as ca. 2 sec when the droplets are frozen within a second. The reaction by freezing is affected by the presence of salts, such as NaCl or KCl, or orgnaic compounds, such as methanol or acetone. The results of freezing a field rain or fog sample showed that nitrite oxidation proceeds below pH 6, and the conversion ratio of nitrate from nitrite increases with decreasing pH. The oxidation of nitrite by freezing was also observed in freezing fog particles generated by an ultrasonic humidifier. The ratios of the concentrations of ions in the winter sample to those in the summer sample (or those in the fog sample) were almost the same values. However, the concentration of nitrite in the winter sample was lower than that estimated by the ratios of other ions. From the present study, it seems that the freezing process plays an important role in the nitrite sink process in the tropospheric aqueous phase.     

The Henry's Law Constants of the Haloacetic Acids

Henry's law constants K_H (mol kg^-1 atm^-1) have been measured between 278.15 K and 308.15 K for the following organic acids: CH₂FCOOH (ln(K_H[298.15 K]) = 11.3 ± 0.2), CH₂ClCOOH (11.59 ± 0.14), CH₂BrCOOH (11.94 ± 0.21), CHF₂COOH (10.32 ± 0.10), CHCl₂COOH (11.69 ± 0.11), CHBr₂COOH (12.33 ± 0.29), CBr₃COOH (12.61 ± 0.21), and CClF₂COOH (10.11 ± 0.12). The variation of K_H with temperature was determined for all acids except CH₂FCOOH and CBr₃COOH, with _r H° for the dissolution reaction ranging from –85.2 ± 2.6 to –57.1 ± 2.5 kJ mol^-1, meaning that their solubility is generally more sensitive to temperature than is the case for the simple carboxylic acids. The Henry's law constants show consistent trends with halogen substitution and, together with their high solubility compared to the parent (acetic) acid (ln(K_H[298.15 K]) = 8.61), present a severe test of current predictive models based upon molecular structure. The solubility of haloacetic acids and strong dissociation at normal pH mean that they will partition almost entirely into cloud and fog in the atmosphere (0.05–1.0 g H₂O m^-3), but can reside in both phases for the liquid water contents typical of aerosols (10^-5-10^-4 g H₂O m^-3).     

Aminostratigraphy and sea-level history of the Pleistocene Bridgewater Formation,Mount Gambier region,southern Australia

A geochronological framework based on amino acid racemisation (AAR) and constrained by previously reported optically stimulated luminescence (OSL) ages is presented for the evolution and paleosea-level record of the Pleistocene Bridgewater Formation of the Mount Gambier region, of southern Australia. Within the study area, the Bridgewater Formation is represented by late early Pleistocene [Marine Isotope Stage (MIS) 23 at 933 ka] to Holocene barrier shoreline successions deposited during sea-level highstands. Regional monotonic uplift (0.13 mm yr^–1) and pervasive calcrete development during the Pleistocene have preserved the sequence of calcarenite (mixed quartz-skeletal carbonate sand) shoreline complexes from denudation. AAR analyses confirm that the barriers generally increase in age landwards and correlate with sea-level highstands associated with interglacials as defined by the marine oxygen isotope record. AAR analyses on the benthic foraminifer Elphidium crispum have proved more reliable than the whole-rock method in extending the age range of AAR dating of these relict shoreline successions. Paleosea-levels from the coastal plain are as follows: MIS 7, –9 ± 2 m; MIS 9, 4 ± 1 m; and a minimum sea-level of 2 ± 2 m is derived for MIS 11. Paleosea-level could not be determined for MIS 15, 19 or 23 as diagnostic sea-level indicators were not identified within these sedimentary successions. Dismal Range, dated at 933 ± 145 ka (MIS 23), represents a correlative feature to the East Naracoorte Range but is some 25 km seaward of the Kanawinka Fault compared with the same barrier at Naracoorte. Mingbool Range (788 ± 18 ka) is of similar age to the West Naracoorte Range (MIS 19) and formed as an arcuate shoreline complex that became attached to the higher relief of the area represented by the Mount Burr Volcanic Province. The higher topographical relief resulted from crustal doming of the Oligo-Miocene Gambier Limestone caused by the intrusion of magma associated with the volcanic province. The AAR age of 788 ± 118 ka for Mingbool Range indicates that the Mount Burr volcanics predate the deposition of this shoreline complex.     

光谱对许氏平鲉消化代谢节律及生理应激研究

为探究不同光谱下许氏平鲉的消化代谢水平及外周激素节律,在5种光谱(红光、绿光、黄光、蓝光、白光,光周期12L∶12D)下,通过对许氏平鲉的血清、肠道、肝脏进行24 h (8:00,12:00,16:00,20:00,24:00)取样,结果显示:不同的光谱下许氏平鲉的消化代谢酶活性除胰蛋白酶(TRY)外均具有节律性,红光、黄光下α-淀粉酶(α-AMS)、脂肪酶(LPS)活性的峰值相位与白光组相比左移;胰蛋白酶活性无时间差异性;在绿光、黄光及红光下乳酸脱氢酶(LDH)活性的峰值相位与白光组相比发生左移,在五种光谱环境中,红、黄光影响消化酶活性峰值提前出现;丙酮酸激酶(PK)活性在绿、蓝及红光下峰值相位左移;己糖激酶(HK)的活性在绿、蓝、黄光下,其峰值相位与白光组相比发生左移,在五种光谱环境中,绿、蓝光影响代谢酶活性类峰值提前出现。许氏平鲉血清中褪黑素含量呈现昼低夜高分泌水平;皮质醇的含量表现为在白天降低,午夜显著升高至最高值后又持续降低。峰值相位的改变预示着生理节律的变动,以上结果表明不同光谱可以影响鱼类的生理代谢节律,在今后养殖过程中需要充分考虑光谱对养殖生物的生物学作用,进而制定更为合理的光照条件。