Assessment effects of cage culture on nitrogen and phosphorus dynamics in relation to fallowing in a shallow lake in China

Nitrogen and phosphorus dynamics in relation to fallowing in a fish cage farm was investigated in a shallow lake in China. Four sampling sites were set: beneath the cages, at the cage sides, and 50 and 100 m east of the cage farm. Total nitrogen (TN) and total phosphorus (TP) in lake water and sediment were analyzed during a 2-year rearing cycle. The cage culture had a fish yield of 16.3-39.2 tonnes in the study period. Based on the mass balance equation, 1533-3084 kg TN and 339-697 kg TP were contributed to the lake environment. Nitrogen and phosphorous concentrations showed greater increase in the first culture period than in the second rearing cycle. No obvious changes were found at the sampling sites 50 and 100 m east of the cages during the study periods. Main impacts were found close to the cages (beneath the cages and at the cage side); the sampling points at the cage side showed relatively high TN and TP sedimentation. After 3 months of fallowing, water TN and TP decreased significantly but the sediment TN and TP contents remained high. Therefore, recovery seems to happen during fallowing but attention should be paid to whether the culture continues to operate in the future.

Budgets and dynamics of nitrogen and phosphorus in a shallow, hypereutrophic lake in China

Budgets and dynamics of nitrogen and phosphorus in Lake Donghu were investigated from Oct. 1997 to Sept. 1999. The water residence time was estimated to be 89 days in 1997-1998 and 124 days in 1998-1999. The total external loadings were 53 g N m(-2) yr(-1) and 3.2 g P m(-2) yr(-1) in 1997-1998, and 42 g N m(-2) yr(-1) and 3.1 g P m(-2) yr(-1) in 1998-1999. On average, about 80% of nitrogen and phosphorus input was from sewage outlets, while the rest was from land runoff and precipitation. Ammonium ion was the most abundant form of inorganic nitrogen in the sewage. The nutrient output was mainly through water outflow and fish catch. The percentages of nutrients in fish were estimated to be 7.8%-11.2% for nitrogen and 47.6%- 49.6% for phosphorus. Lake Donghu has a very high nutrient retention (63% for nitrogen and 79% for phosphorus) mainly due to its closure and long water residence time. Sedimentation is an important nutrient retention mechanism in this lake. Using mass balance method, we estimated that denitrification of Lake Donghu involves about 50% of the retained nitrogen. Lake Donghu is rich in inorganic nitrogen and phosphorus and showed great seasonal variation.

The role of plants in channel-dyke and field irrigation systems for domestic wastewater treatment in an integrated eco-engineering system

Eight kinds of plants were tested in channel-dyke and field irrigation systems. The removal rates of TP, phosphate, TN, ammonia, CODcr and BOD, in the channel-dyke system with napiergrass (Pennisetum purpurem Schumach, x Pennisetum alopecuroides (L.) Spreng American) were 83.2, 82.3, 76.3, 96.2, 73.5 and 85.8%, respectively. The field irrigation systems with rice I-yuanyou No.1(88-132) (Oryza sativa L.) and rice II- suakoko8 (Oryza glaberrima) had high efficiency for N removal; the removal rate were 84.7 and 84.3%, respectively. The mass balance data revealed that napiergrass, rice I and II were the most important nutrient sinks, assimilating more than 50% of TP and TN. Plant uptake of N and P as percentage of total removal from wastewater correlated with biomass yield of and planting mode. (C) 2000 Elsevier Science B.V. All rights reserved.

Theoretical gain of strained GeSn0.02/Ge1-x-y ' SixSny ' quantum well laser

Using effective-mass Hamiltonian model of semiconductors quantum well structures, we investigate the electronic structures of the Gamma-conduction and L-conduction subbands of GeSn/GeSiSn strained quantum well structure with an arbitrary composition. Our theoretical model suggests that the band structure could be widely modified to be type I, negative-gap or indirect-gap type II quantum well by changing the mole fraction of alpha-Sn and Si in the well and barrier layers, respectively. The optical gain spectrum in the type I quantum well system is calculated, taking into account the electrons leakage from the Gamma-valley to L-valley of the conduction band. We found that by increasing the mole fraction of alpha-Sn in the barrier layer and not in the well layer, an increase in the tensile strain effect can significantly enhance the transition probability, and a decrease in Si composition in the barrier layer, which lowers the band edge of Gamma-conduction subbands, also comes to a larger optical gain.

A finite-element algorithm for modeling variably saturated flows

A general numerical algorithm in the context of finite element scheme is developed to solve Richards’ equation, in which a mass-conservative, modified head based scheme (MHB) is proposed to approximate the governing equation, and mass-lumping techniques are used to keep the numerical simulation stable. The MHB scheme is compared with the modified Picard iteration scheme (MPI) in a ponding infiltration example. Although the MHB scheme is a little inferior to the MPI scheme in respect of mass balance, it is superior in convergence character and simplicity. Fully implicit, explicit and geometric average conductivity methods are performed and compared, the first one is superior in simulation accuracy and can use large time-step size, but the others are superior in iteration efficiency. The algorithm works well over a wide variety of problems, such as infiltration fronts, steady-state and transient water tables, and transient seepage faces, as demonstrated by its performance against published experimental data. The algorithm is presented in sufficient detail to facilitate its implementation.

A QUANTITATIVE ASSESSMENT OF SOURCE CONTRIBUTIONS TO INHALABLE PARTICULATE MATTER POLLUTION IN METROPOLITAN BOSTON

In this paper, source apportionment techniques are employed to identify and quantify the major particle pollution source classes affecting a monitoring site in metropolitan Boston, MA. A Principal Component Analysis (PCA) of paniculate elemental data allows the estimation of mass contributions for five fine mass panicle source classes (soil, motor vehicle, coal related, oil and salt aerosols), and six coarse panicle source classes (soil, motor vehicle, refuse incineration, residual oil, salt and sulfate aerosols). Also derived are the elemental characteristics of those source aerosols and their contributions to the total recorded elemental concentrations (i.e. an elemental mass balance). These are estimated by applying a new approach to apportioning mass among various PCA source components: the calculation of Absolute Principal Component Scores, and the subsequent regression of daily mass and elemental concentrations on these scores.

一个改进的随机动力学水平衡模型及其应用研究Ⅱ.应用

本文用黄土高原长武农业生态试验站的冬小麦长期定位试验资料对改进的随机动力学水平衡模型进行了准确性检验 .从模型对参数反映的敏感性分析和模型计算值与数值模型WAVES的比较 ,以及模型对黄土区旱作高生产力的水分环境效应的评价结果 ,均证明改进的随机动力学水平衡模型能比较准确地预测一定生产力水平、特定生态系统平衡体系水均衡要素的定量分配和土壤含水量的动态变化 .

Extraction kinetics of cerium(IV) from sulfuric acid medium by the primary amine N1923 using a constant interfacial area cell with laminar flow

BACKGROUND: Thermodynamic studies on Ce(IV) extraction with primary amine N1923 demonstrate that primary amine N1923 is an excellent extractant for separation of Ce(IV) from Re(III). In order to clarify the mechanism of extraction and to optimize the parameters in practical extraction systems used in the rare earth industry, the extraction kinetics was investigated using a constant interfacial area cell with laminar flow in the present work.RESULTS: The data indicate that the rate constant (k(ao).) becomes constant when stirring speed exceeds 250 rpm. The apparent forward extraction rate is calculated to be 10(-1.70). The activation energy (E.) was calculated to be 20.5 kJ/mol from the slope of log kao against 1000/T. The minimum bulk concentration of the extractant necessary to saturate the interface (C-min) is lower than 10(-5) mol L-1.CONCLUSION: Studies of interfacial tension and the effects of stirring rate and specific interfacial area on the extraction rate show that the extraction rate is kinetically controlled, and a mass transfer model has been proposed. The rate equation has been obtained as: -d[Ce(IV)]/dt = 10(-1.70)[Ce(IV)] [(RNH3)(2)SO4](1.376). The rate-controlling step has been evaluated from analysis of the experimental results.

Distribution of uranium isotopes in the main channel of Yellow river (Huanghe), China

Uranium isotopes were measured in waters and suspended particulate matters (SPM) of the main channel of Yellow River, China that were sampled during four field trips between August 2005 and July 2006. The results show that the concentration of dissolved U (2.04-7.83 mu g/l) and the activity ratio of U-234/U-238 (1.36-1.67) are much higher than the average U concentrations and activity ratios of global major rivers. Mass balance calculations using the results of simulated experiments and measurement data show that the section of the Yellow River between Lanzhou and Sanmenxia has its dissolved U derived from two sources: suspended sediments (68%) and groundwater/runoff from loess deposits (32%). Both sources are related to the heavy erosion of the Chinese Loess Plateau. (C) 2008 Elsevier Ltd. All rights reserved.

Interannual horizontal heat advection in the surface mixed layer over the equatorial Pacific Ocean: assimilation versus TAO analysis

The interannual anomalies of horizontal heat advection in the surface mixed layer over the equatorial Pacific Ocean in an assimilation experiment are studied and compared with existing observational analyses. The assimilation builds upon a hindcast study that has produced a good simulation of the observed equatorial currents and optimizes the simulation of the Reynolds sea surface temperature (SST) data. The comparison suggests that the assimilation has improved the simulation of the interannual horizontal heat advection of the surface mixed layer significantly. During periods of interrupted current measurements, the assimilation is shown to produce more meaningful anomalies of the heat advection than the interpolation of the observational data does. The assimilation also shows that the eddy heat flux due to the correlation between high-frequency current and SST variations, which is largely overlooked by the existing observational analyses, is important for the interannual SST balance over the equatorial Pacific. The interannual horizontal heat advection anomalies are found to be sensitive to SST errors where oceanic currents are strong, which is a challenge for ENSO prediction. The study further suggests that the observational analyses of the tropical SST balance based on the TAO and the Reynolds SST data contain significant errors due to the large gradient errors in the Reynolds SST data, which are amplified into the advection anomalies by the large equatorial currents.

On the western boundary currents in the Philippine Sea

In this study we describe the velocity structure and transport of the North Equatorial Current (NEC), the Kuroshio, and the Mindanao Current (MC) using repeated hydrographic sections near the Philippine coast. A most striking feature of the current system in the region is the undercurrent structure below the surface flow. Both the Luzon Undercurrent and the Mindanao Undercurrent appear to be permanent phenomena. The present data set also provides an estimate of the mean circulation diagram (relative to 1500 dbar) that involves a NEC transport of 41 Sverdrups (Sv), a Kuroshio transport of 14 Sv, and a MC transport of 27 Sv, inducing a mass balance better than 1 Sv within the region enclosed by stations. The circulation diagram is insensitive to vertical displacements of the reference level within the depth range between 1500 and 2500 dbar. Transport fluctuations are, in general, consistent with earlier observations; that is, the NEC and the Kuroshio vary in the same phase with a seasonal signal superimposed with interannual variations, and the transport of the MC is dominated by a quasi-biennial oscillation. Dynamic height distributions are also examined to explore the dynamics of the current system.

Stable carbon isotope analyses show dominance of C3 grasses in the feed selected by small herbivores at the alpine meadow at the Tibetan Plateau

Muscle samples were collected from small herbivorous mammals (Ochotona curzoniae, Microtus oecnomus, Myospalax fontanierii and Lepus oiostolus) at the alpine meadow ecosystem at the Tibetan Plateau in order to address variability in stable carbon isotope composition. Stable carbon isotope values of muscles remain steady and show no significant variations (-25.72 to -27.04 parts per thousand) among the four small mammal species. Based on the mass balance theory of stable isotopes, it is proposed that small herbivorous mammals mainly (or totally) rely on C3 grasses as food supply, and there is few or no distribution of C4 grasses at the ecosystem. The results reflect our previous study on the isotope patterns of plant species. Thus, stable carbon isotope analysis of muscles provides a method to address dietary selection and dietary variability in herbivores. In addition, stable carbon isotopic analyses can be used to address changes in vegetation distributions in ecosystem and paleovegetaion and paleoclimate.

一种使用GPS、罗盘和激光测距仪测定南极冰川运动的方法

南极冰川运动,是研究南极冰雪物质平衡、环境变化等的重要因素,对其的监测具有重大意义。本文提出了一种配合使用GPS、罗盘和激光测距仪实现测定冰川运动的方法。该方法在完成标定和在冰川上放置标志杆后,无需靠近冰川,只根据远处工作站的GPS、罗盘读数和激光测距仪的测量值就能给出标志杆的GPS数值,从而监测冰川的运动。

中国西部大气和雪冰黑碳及其传输过程研究

Glaciers in west China are the sources of the major great rivers in Asia, and the solid water resources are crucial to China and South Asia. Black carbon (BC) results in very complex climate effects not only in the atmosphere, but accelerates the melting after its deposit on the surface of snow/ice. As the main distributed area of glaciers in China, the Tibetan Plateau (TP) and Xinjiang region are abutted by South Asia, Central Asia, and Russia, and east China, and the atmospheric environment would be influenced by the BC emitted from these regions. Whereas, the BC’s temporal and spatial distributions for concentration in the mid and top troposphere in west China, its transport, and its radiative forcing after deposited on the snow/ice surface are not well understood at the present. In the field, we collected samples from surface snow, snow pits, ice core, and aerosol in the glaciers, analyzed BC content mainly by the thermo-oxidized method in the laboratory, and discussed temporal and spatial distributions for BC concentrations in glaciers, the transport, and its impacts on the environment. Several conclusions were derived as follows: 1_Spatial distribution and the impact on albedos for BC concentrations in snow/ice: the BC concentrations in the surface snow for the investigated glaciers could be placed in areas, the Tianshan Mountains ＞ the central TP ＞ the Pamirs ＞ the Qilian Mountians ＞ the Himalayas. This distribution could be attributed to the elevation of the glaciers, the topography of the TP, and more regional emissions. Probably significant impacts on the albedos of the glacier surface could be caused by BC deposits, and the estimated reduced albedos on the glaciers are 9.8% (the Zhadang glacier), 8.7% (the Miao’ergou Riverhead No.3 glacier), and 6.8% (the Kuitun River Haxilegen No.48 glacier), and 6.2% (the Dongkemadi glacier), and 5.3% (the La’nong glacier), and 4.2% (the Muztagata glacier), etc. 2_The temporal variance of BC concentrations in ice of the East Rongbuk Glacier (ERG) and its climatic implications: major cations and anions (e.g., SO42- and Ca2+) concentrations in aerosols during summer monsoon seasons showed their close relationships with the sources of air masses, in which the variance of SO42- concentrations suggested the atmospheric environment over the ERG was significantly influenced by the aerosols from South Asia. BC record based on an ice core suggested its deposit was dominantly transported by monsoons in summers and by westerlies in other seasons, and the BC from South Asia in summers dominated the varying trend of its concentrations in the ice core and caused higher concentrations in summers than those in other seasons. In the past 50 yrs, BC concentrations showed fluctuations, whereas showed an increasing tread in the most recent decade, and exceeded 50 μg kg-1 in the summer of 2001; correspondingly, the radiative forcing caused by BC showed an increasing trend since 1990s, and exceeded 4.5 W m-2 in the summer of 2001. 3_Cabonaceous aerosols in the Nam Co region: organic carbon (OC) concentration accounted for ～95% and BC for ～5% in the total carbonaceous aerosol concentration, which was significantly influenced by summer precipitations. OC was dominantly derived from fossil fuel burning and BC from both fossil fuel and biomass burning. Trajectory analysis and aerosol optical depth suggested the atmospheric environment in the Nam Co region was most probably influenced by the emissions from South Asia. The potential source regions of air pollutants in the Nam Co regions in summers might be Bangladesh and east India, and in winters might be the Indo-gangetic basin. The scavenging ratio of atmospheric BC by rainfalls was less than those at other sites. West China is a less-developed region for industry, where BC concentrations in the atmosphere and snow/ice could be significantly influenced by the emissions from the abutted regions with rising industries (South Asia, Central Asia, and Russia). For example, snow/ice BC concentrations in the glaciers of the Parmirs, the Tianshan Mountains, and the Qilian Mountains in the northeast margin of the TP might be more influenced by the emissions from Centrial Asia (transported by the westerlies), those in the glaciers of the Himalayas might be more influenced by the emissions from South Asia (transported by the monsoons and the westerlies), and atmospheric carbonaceous aerosols might also be more influenced by the emissions from South Asia (transported by the monsoons and the westerlies). The BC concentrations in some glaciers might cause significant impacts on the albedos for the glaciers, and therefore enhanced the radiative forcings, for example, the ERG. The research on the relationships among atmospheric and snow/ice BC and its radiative forcing, variance of snow cover, mass balance of glaciers, and climate forcing would be needed in future.

东海榴辉岩向斜长角闪岩的转化过程

The Ultrahigh Pressure Metamorphic (UHPM) eclogite, which was resulted from deep subduction of crustal continent, is very significant due to its continental dynamic implications. Further more, this kind of rocks experienced great P-T, fluid and stresses changes during its forming and exhumation, causing mineral reactions occur intensively, which resulted in a lot of fantastic micro-texture. The micro-texture was preserved duo to a rapid exhumation of the eclogite. This PhD dissertation takes such micro-textures in 10 Donghai eclogite samples South Sulu UHPM terrene, as research object to reveal the transformation of the eclogite to amphibolite. Microscope and Scanning Electron Microscope were employed to observe the micro-texture. Basing on microprobe analysis of minerals, the ACF projections and iso-con analysis were used to uncover the mineral reactions during the transformation. Micro-texture observation (both of Microcopy and Electron Scanning Microscope), demonstrated: l.The peak mineral assemblage of the researched Donghai eclogites is garnet + omphacite + rutile (+ kyanite + aptite +coesite). 2.The transformation of the Donghai eclogite to amphibolite can be divided into two stages: The earlier one is Symplectization, resulting in the forming of diopside + albite (+magnetite) symplectite that occurred only along the boundary between two adjacent omphacite grains. Other minerals were not involved in such reaction. The latter stage is Fluid-Infiltration of the eclogite, which was caused by fluid-intrusion. The infiltration is demonstrated by amphibolization of the symplectite, decomposition of garnet and the forming of some hydrous minerals such as phengite and epidote, and resulted in an amphibole + plagioclase + phengite + epidote or ziosite assemblage. Basing on microprobe analysis of the minerals, ACF projections indicated: In the ACF diagrams, the two joint lines of peak Grt + Omp and Dio + Ab crossed at Omp projection-point, indicating that the garnet had not taken part in the forming reaction of the Dio + Ab symplectite, just like that had been pointed out by micro-texture observation. In the ACF diagrams, the hornblende + plagioclase + epidote + phengite quadrilateral intersected with Dio + Ab + Grt triangle, demonstrating that the hydrous mineral assemblage was formed by fluid infiltration through garnet, diopside and albite. Iso-con (mass-balance) analysis of the symplectization and infiltration reveals: 1.The symplectization of the omphacite has a very complex mass exchange: Some symplectite gained only silicon from its surroundings; and some one requires Ca, but provides Na to its surroundings; while other symplectite provides Ca, Mg and Fe to its surroundings. 2.The infiltration cause variable mass exchanges occurring among the garnet, diopside and albite: In some eclogite sample, no mass, except H2O, exchange occurred during the infiltration. Meanwhile, there was not any hydrous mineral except hornblende formed in the sample accordingly. In some samples, the mass exchange among the three minerals is complex: amphibolization of the diopside in a symplectite gained Al from garnet, and provided Si and Ca to its surrounding, resulting in a Si, Ca and Al-rich fluid. Correspondingly, there was a lot of phengite and ziosite occurred in the sample. In other samples, the amphibolization of a symplectite provided Fe and Mg besides Si and Ca to its surrounding while gained Al. In such kind of sample, epidote occurred within the hydrous mineral assemblage. Synthesizing the micro-texture observation, ACF analysis and iso-con analysis, we deduced the transformation procedure as following: 1. A symplectite after an omphacite was resulted by one, or two, or all of following mineral reactions together: Jd (Ca-Tsch) +SiO2=Ab (An) (1) 4NaA IS i.A+CaO=2NaAlS i308+Na20+CaAl2S 1208 (2) 2NaAlSi2OB (Jd in Omp)+CaMgSi;,0B(Dio in Omp)-2NaAlSi:,O"(Ab)+Ca0+Mg0 (3) 2(CaAl2Si0fi) (Ca-tsch in Omp)+CaFeSi2O6(Hed in 0mp)-H>2CaAl2Si208(An)+Ca0 + FeO (4) A CO2-rich fluid is suggested as cataclysm for the above reactions, which largely increased the mobility of Ca, Mg and Na resulted from reaction (2), (3) and (4). The immobile product Fe2* combined with rutile to form ilmenite, resulting in rutile + ilmenite symplectite. Or, the Fe was precipitated as hematite locally. A procedure of the fluid infiltration as following is suggested: I .A hydrous fluid intruded into the eclogite, and reacted first with garnet to form hornblende and extra Al, resulting in a hornblende film around the garnet grain and an Al-rich fluid. 2.The Al-rich fluid infiltrated through the symplectite, OH" and part of the Al in the fluid combined with Dio while some Si and Ca in the Dio were dissolved made the Dio transferred to amphibole. Meanwhile, plagioclase-type cation exchange occurred between the fluid and plagioclase in the symplectite, making the plagioclase have a higher An-content. 3.Above infiltration and cation exchange resulted in an Al, Si, Ca (and K, providing the primary hydrous fluid contain K)-rich fluid. 4.Under suitable conditions, the solute in the fluid precipitated to form phengite firstly. After the K element in the fluid was consumed up, ziosite or epidote was formed. If the fluid did not contain any K. element, only ziosite or epidote was precipitated. For those eclogites, where all omphacite had been replaced by symplectite before infiltration, neither element exchange occurred, nor did phengite or epidote form during the infiltration. At the last stage, the garnet was oxidized and breakdown: garnet + H2O = epidote + hornblende + hematite, due to more and more fluid intruding into the eclogite. At this time, all the peak minerals were replaced by amphibolite-phase ones, and the eclogite transformed to an amphibolite completely. Tentative pressure calculation indicates that the infiltration occurred at 3-6kbar (about 10-20km depth), where the deformation mechanics transformed from brittle to ductile yield. At such depth, the surface water can permeate the rocks through fault system, causing a rapid cooling.