Halogen contents of eclogite facies fluid inclusions and minerals: Caledonides,western Norway

Primary multiphase brine fluid inclusions in omphacite and garnet from low‐ to medium‐temperature eclogites have been analysed for Cl, Br, I, F, Li and SO₄. Halogen contents and ratios provide information about trapped lower crustal fluids, even though the major element (Na, K, Ca) contents of inclusion fluids have been modified by fluid–mineral interactions and (step‐) daughter‐crystal formation after trapping. Halogens in the inclusion fluids were analysed with crush–leach techniques. Cl/Br and Cl/I mass ratios of eclogite fluids are in the range 31–395 and 5000–33 000, respectively. Most fluids have a Cl/Br ratio lower than modern seawater and a Cl/I ratio one order of magnitude lower than modern seawater. Fluids with the lowest Cl/Br and highest Cl/I ratios come from an eclogite that formed by hydration of granulite facies rocks, and may indicate that Br and I are fractionated into hydrous minerals. Reconstructions indicate that the inclusion fluids originally contained 500–4000 ppm Br, 1–14 ppm I and 33–438 ppm Li. Electron microprobe analyses of eclogite facies amphibole, biotite, phengite and apatite indicate that F and Cl fractionate most strongly between phengite (F/Cl mass ratio of 1469 ± 1048) and fluid (F/Cl mass ratio of 0.008), and the least between amphibole and fluid. The chemical evolution of Cl and Br in pore fluids during hydration reactions is in many ways analogous to Cl and Br in seawater during evaporation: the Cl/Br ratio remains constant until the a_H2O value is sufficiently lowered for Cl to be removed from solution by incorporation into hydrous minerals.     

A multiphase flow and multispecies reactive transport model for DNAPL-involved Compound Specific Isotope Analysis

This study presents a multiphase flow and multispecies reactive transport model for the simultaneous simulation of NAPL and groundwater flow, dissolution, and reactive transport with isotope fractionation, which can be used for better interpretation of NAPL-involved Compound Specific Isotope Analysis in 3D heterogeneous hydrogeologic systems. The model was verified for NAPL-aqueous phase equilibrium partitioning, aqueous phase multi-chain and multi-component reactive transport, and aqueous phase multi-component transport with isotope fractionation. Several illustrative examples are presented to investigate the effect of DNAPL spill rates, degradation rate constants, and enrichment factors on the temporal and spatial distribution of the isotope signatures of chlorinated aliphatic hydrocarbon groundwater plumes. The results clearly indicate that isotope signatures can be significantly different when considering multiphase flow within the source zone. A series of simulations indicate that degradation and isotope enrichment compete with dissolution to determine the isotope signatures in the source zone: isotope ratios remain the same as those of the source if dissolution dominates the reaction, while heavy isotopes are enriched in reactants along groundwater plume flow paths when degradation becomes dominant. It is also shown that NAPL composition can change from that of the injected source due to the partitioning of components between the aqueous and NAPL phases even when degradation is not allowed in NAPL phase. The three-dimensional simulation is presented to mechanistically illustrate the complexities in determining and interpreting the isotopic signatures with evolving DNAPL source architecture.     

脱落酸介导的逆境响应信号传导机制及在藻类中的分布与功能研究

植物激素是一类由植物合成的痕量有机物质,调控着植物的生长发育及对环境的适应。藻类属低级植物类群,且具有与高等植物类似的大多数激素类型,相对而言,藻类激素含量更少,却发挥着更高效的生理活性。无论在藻类,还是高等陆地植物,胁迫响应一直是研究十分活跃的领域。其中脱落酸(ABA)作为应激激素,所起的调节作用已得到人们的共识。本文总结了近些年关于ABA在藻类中的分布,ABA对抗氧化酶系的调控,ABA信号传导路径在陆地植物中的发现与代谢机制,以及利用蛋白质分子系统学对ABA信号传导途径的起源与进化的分析。在此基础上,提出未来藻类ABA参与的抗逆代谢调控研究应着重从潮间带海藻出发,参考陆地植物研究的成果,应用生物信息学结合生物化学等的手段,进行相关机制的探索。     

流式细胞术检测虾类血细胞活性氧含量方法的建立

建立和优化了流式细胞术检测虾类血细胞活性氧含量的方法。以2′,7′-二氢二氯荧光黄双乙酸钠(DCFH-DA)为ROS特异探针,以斑节对虾(Penaeus monodon)血细胞为材料,用流式细胞仪检测不同染料浓度和不同染料孵育时间下血细胞的荧光强度、细胞形态特征和细胞活性的变化。结果表明,利用FCM检测虾类血细胞ROS含量的适宜的染料浓度和最佳的孵育时间分别为10μmol/L和30 min。     

Effects of temperature, algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

Gracilaria asiatica,being highly efficient in nutrient absorption,is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate.It was cultured in a laboratory simulating field conditions,and its nutrient absorption was measured to evaluate effects of environmental conditions.Ammonia nitrogen(AN),nitrate nitrogen(NN),total inorganic nitrogen(TIN),and soluble reactive phosphorus(SRP) uptake rate and removal efficiency were determined in a 4×2 factorial design experiment in water temperatures(T) at 15℃ and 25℃,algae biomass(AB) at 0.5 g/L and 1.0 g/L,total inorganic nitrogen(TIN) at 30 μmol/L and 60 μmol/L,and soluble reactive phosphorus(SRP) at 3 and 6 μmol/L.AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN,NN,TIN,and SRP(P<0.001).G.asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L.Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations;nutrient removal efficiency decreased at higher environmental nutrient concentrations.The algae preferred to absorb AN to NN.Uptake rates of AN,NN,and SRP were significantly affected by temperature(P<0.001);uptake rate was higher for the 25℃ group than for the 15℃ group at the initial experiment stage.Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups(P<0.01).The four factors had significant interactive effects on absorption of N and P,implying that G.asiatica has great bioremedial potential in sea cucumber culture ponds.     

Plume Behavior for Petroleum Hydrocarbon in a Tropical Sand Tank: Laboratory Experiments and Scenario-Specific Modelling

Numerical simulations were performed to assess the reactive transport and natural attenuation of gasoline fuel components in a 3-D sand tank model. The conceptual model includes a residual gasoline source that dissolves into the 3-D aquifer. The analysis reveals high to very high correlation between the observed and simulated values (average R² = 0.97). A retardation factor R = 1.5, and first-order decay rate of 0.0002/day were obtained from the model calibration for BTEX.

The results are highly relevant in the light of the increasing awareness of the precarious trend of lack of monitoring and remedial feasibility data for the subsoil environment in the thousands of gasoline fuel stations, and petroleum storage/distribution underground infrastructure and the riverbeds of inland waterways in Nigeria.

The biodegradation rate was the most sensitive model parameter, with about 82% increase in BTEX maximum plume concentration, for the zero biodegradation scenario.     

古海洋活性磷埋藏记录及其在氧气地球化学循环研究中的运用

在综合现代大洋活性磷循环特征的基础上,提出大洋中活性磷主要来源于有CO2 参与的地表岩石的化学风化,输入通量在很大程度上受到气候与构造等因素的控制;进入大洋之后的活性磷经光合作用而进入有机物,并通过一系列的转化环节而最终埋藏下来;从而可以根据古海洋活性磷埋藏记录,推断地质历史中不同时间尺度的全球变化情况。对比160 Ma以来的古海洋总磷和100 Ma活性磷埋藏记录可以发现:(1)总磷和活性磷的埋藏速率与长期的海平面变化明显关联,在温室气候条件下,两者基本呈正相关关系;在冰室气候条件下则为反相关关系;(2)总磷和活性磷埋藏速率的变化,能够在一定程度上指示古海洋营养条件的变化;(3)白垩纪中期大洋缺氧事件对应活性磷的埋藏峰值,表明大洋活性磷循环与大洋缺氧事件之间存在着非常密切的关系。此外还例举了古海洋活性磷埋藏记录在氧气地球化学循环研究中的运用,指出活性磷循环对大气氧含量的稳定起到重要的作用。文章最后对古海洋活性磷埋藏记录研究中存在的一些问题进行了讨论。     

基于碳化-固化技术的武汉东湖淤泥耐久性演变微观机制

引入活性MgO-粉煤灰固化材料,采用碳化-固化联合技术处理武汉东湖疏浚淤泥,通过无侧限抗压强度、X射线衍射、扫描电镜和压汞试验,研究持续浸水、干湿循环和冻融循环等复杂环境下碳化-固化淤泥力学性质和微观结构演变。结果表明:活性MgO-粉煤灰固化淤泥经碳化处理后具备更优异的水稳性,浸水破坏后碳化淤泥试样整体抗压强度高于固化试样,提升幅度约为29%;碳化试样强度随干湿循环次数增加呈缓慢增加趋势,而固化试样则表现为先上升后下降;随着冻融循环次数增加,碳化前后试样抗压强度变化一致,即快速达到峰值后缓慢减小至保持不变。微观分析表明:起骨架支撑作用的棱柱形碳酸镁石、起填充与黏结作用的花骨状和片状的水碳镁石和球碳镁石为主要碳化产物,骨架-填充-黏结协同作用使碳化试样强度高,水稳定性好,抗干湿冻融能力强;持续浸水促使球碳镁石和水碳镁石向碳酸镁石转化,大孔隙增多;干湿循环促使碳酸镁石向球碳镁石和水碳镁石转化;冻融作用下试样碳化产物之间无明显转化。     

Some Mathematical and Computational Problems in Reactive Flow

We present an overview of several applications of reactive flow and transport in which interesting mathematical issues and computational challenges arise. The topics include front propagation through porous media in the presence of dispersion; numerical simulation of large-scale reactive transport problems; the reliability of processes that involve in-situ generation of viscosifying agents; methods for describing pore-scale geometry in granular media; and the information content of reactive tracer experiments. The intent of this survey is to heighten awareness of underlying mathmetical aspects and, it is hoped, to stimulate new contributions in these areas.