The ozone transfer between atmosphere and vegetation. A study on Scots pine in the field

Ozone (O3) is a reactive gas present in the troposphere in the range of parts per billion (ppb), i.e. molecules of O3 in 109 molecules of air. Its strong oxidative capacity makes it a key element in tropospheric chemistry and a threat to the integrity of materials, including living organisms. Knowledge and control of O3 levels are an issue in relation to indoor air quality, building material endurance, respiratory human disorders, and plant performance. Ozone is also a greenhouse gas and its abundance is relevant to global warming. The interaction of the lower troposphere with vegetated landscapes results in O3 being removed from the atmosphere by reactions that lead to the oxidation of plant-related components. Details on the rate and pattern of removal on different landscapes as well as the ultimate mechanisms by which this occurs are not fully resolved. This thesis analysed the controlling processes of the transfer of ozone at the air-plant interface. Improvement in the knowledge of these processes benefits the prediction of both atmospheric removal of O3 and its impact on vegetation. This study was based on the measurement and analysis of multi-year field measurements of O3 flux to Scots pine (Pinus sylvestris L.) foliage with a shoot-scale gas-exchange enclosure system. In addition, the analyses made use of simultaneous CO2 and H2O exchange, canopy-scale O3, CO2 and H2O exchange, foliage surface wetness, and environmental variables. All data was gathered at the SMEAR measuring station (southern Finland). Enclosure gas-exchange techniques such as those commonly used for the measure of CO2 and water vapour can be applied to the measure of ozone gas-exchange in the field. Through analysis of the system dynamics the occurring disturbances and noise can be identified. In the system used in this study, the possible artefacts arising from the ozone reactivity towards the system materials in combination with low background concentrations need to be taken into account. The main artefact was the loss of ozone towards the chamber walls, which was found to be very variable. The level of wall-loss was obtained from simultaneous and continuous measurements, and was included in the formulation of the mass balance of O3 concentration inside the chamber. The analysis of the field measurements in this study show that the flux of ozone to the Scots pine foliage is generated in about equal proportions by stomatal and non-stomatal controlled processes. Deposition towards foliage and forest is sustained also during night and winter when stomatal gas-exchange is low or absent. The non-stomatal portion of the flux was analysed further. The pattern of flux in time was found to be an overlap of the patterns of biological activity and presence of wetness in the environment. This was seen to occur both at the shoot and canopy scale. The presence of wetness enhanced the flux not only in the presence of liquid droplets but also during existence of a moisture film on the plant surfaces. The existence of these films and their relation to the ozone sinks was determined by simultaneous measurements of leaf surface wetness and ozone flux. The results seem to suggest ozone would be reacting at the foliage surface and the reaction rate would be mediated by the presence of surface wetness. Alternative mechanisms were discussed, including nocturnal stomatal aperture and emission of reactive volatile compounds. The prediction of the total flux could thus be based on a combination of a model of stomatal behaviour and a model of water absorption on the foliage surfaces. The concepts behind the division of stomatal and non-stomatal sinks were reconsidered. This study showed that it is theoretically possible that a sink located before or near the stomatal aperture prevents or diminishes the diffusion of ozone towards the intercellular air space of the mesophyll. This obstacle to stomatal diffusion happens only under certain conditions, which include a very low presence of reaction sites in the mesophyll, an extremely strong sink located on the outer surfaces or stomatal pore. The relevance, or existence, of this process in natural conditions would need to be assessed further. Potentially strong reactions were considered, including dissolved sulphate, volatile organic compounds, and apoplastic ascorbic acid. Information on the location and the relative abundance of these compounds would be valuable. The highest total flux towards the foliage and forest happens when both the plant activity and ambient moisture are high. The highest uptake into the interior of the foliage happens at large stomatal apertures, provided that scavenging reactions located near the stomatal pore are weak or non-existent. The discussion covers the methodological developments of this study, the relevance of the different controlling factors of ozone flux, the partition amongst its component, and the possible mechanisms of non-stomatal uptake.

Numerical study on the surface depression of the concrete runway pavement under impact load

Airport runway pavement always subjected to huge impact loading due to the hard landing of aircraft on the pavement surface. Therefore runway pavements should have sufficient impact resistance capability to avoid damage causing by hard impact like surface deflection in downward or penetration since the repair works is cumbersome within the operating condition of airport and also increases the service life cost of the pavement structure. Several research works have been carried out on airport runway pavement to measure the present condition of pavement and also to predict future performance of it. However, most of the works are confined by pavement response under moving aircraft loading. Nevertheless, no comprehensive research work is yet conducted to identify the controlling factors which might have significant effect in changing the common pavements damage like surface penetration depth under impact of aircraft. Therefore, a 3D FE study is conducted to determine some effective factors in controlling the top surface penetration depth of runway pavement. Among the exterior factors, mass of the impactor, velocity of the impactor, impact angle and boundary conditions are selected and as interior factors, thickness of the runway pavement, compressive strength and density of materials used in the runway pavement are selected.

Rule-based modelling of iron homeostasis in tuberculosis

To establish itself within the host system, Mycobacterium tuberculosis (Mtb) has formulated various means of attacking the host system. One such crucial strategy is the exploitation of the iron resources of the host system. Obtaining and maintaining the required concentration of iron becomes a matter of contest between the host and the pathogen, both trying to achieve this through complex molecular networks. The extent of complexity makes it important to obtain a systems perspective of the interplay between the host and the pathogen with respect to iron homeostasis. We have reconstructed a systems model comprising 92 components and 85 protein-protein or protein-metabolite interactions, which have been captured as a set of 194 rules. Apart from the interactions, these rules also account for protein synthesis and decay, RBC circulation and bacterial production and death rates. We have used a rule-based modelling approach, Kappa, to simulate the system separately under infection and non-infection conditions. Various perturbations including knock-outs and dual perturbation were also carried out to monitor the behavioral change of important proteins and metabolites. From this, key components as well as the required controlling factors in the model that are critical for maintaining iron homeostasis were identified. The model is able to re-establish the importance of iron-dependent regulator (ideR) in Mtb and transferrin (Tf) in the host. Perturbations, where iron storage is increased, appear to enhance nutritional immunity and the analysis indicates how they can be harmful for the host. Instead, decreasing the rate of iron uptake by Tf may prove to be helpful. Simulation and perturbation studies help in identifying Tf as a possible drug target. Regulating the mycobactin (myB) concentration was also identified as a possible strategy to control bacterial growth. The simulations thus provide significant insight into iron homeostasis and also for identifying possible drug targets for tuberculosis.

Partition Energy Absorption of Axially Crushed Aluminum Foam-Filled Hat Sections

The "interaction effect" between aluminum foam and metal column that takes place when foam-filled hat sections (top-hats and double-hats) are axially crushed was investigated in this paper. Based on experimental examination, numerical simulation and analytical models, a systemic approach was developed to partition the energy absorption quantitatively into the foam filler component and the hat section component, and the relative contribution of each component to the overall interaction effect was therefore evaluated. Careful observation of the collapse profile found that the crushed foam filler could be further divided into two main energy-dissipation regions: densified region and extremely densified region. The volume reduction and volumetric strain of each region were empirically estimated. An analytical model pertinent to the collapse profile was thereafter proposed to find the more precise relationship between the volume reduction and volumetric strain of the foam filler. Combined the superfolding element model for hat sections with the current model according to the coupled method, each component energy absorption was subsequently derived, and the influence of some controlling factors was discussed. According to the finite element analysis and the theoretical modeling, when filled with foam, energy absorption was found to be increased both in the hat section and the foam filler, whereas the latter contributes predominantly to the interaction effect. The formation of the extremely densified region in the foam filler accounts for this effect.

Cruise Report: Spring 2007 Survey of ecological conditions along the continental shelf off Florida from Anclote Key to West Palm Beach NOAA Ship NANCY FOSTER NF-07-08-NCCOS (May 15 - May 28, 2007)

This cruise report is a summary of a field survey conducted in coastal-ocean waters off Florida from Anclote Key to West Palm Beach and from approximately 1 nautical mile (nm) offshore seaward to the shelf break (100 m). The survey was conducted May 15 - May 28, 2007 on NOAA Ship NANCY FOSTER Cruise NF-07-08-NCCOS. Multiple indicators of ecological condition were sampled synoptically at each of 50 stations throughout the region including 10 stations within the Florida Keys National Marine Sanctuary (FKNMS) using a random probabilistic sampling design. Samples were collected for the analysis of benthic community structure and composition; concentrations of chemical contaminants (metals, pesticides, PAHs, PCBs, PBDEs) in sediments and target demersal biota; nutrient and chlorophyll levels in the water column; and other basic habitat characteristics such as depth, salinity, temperature, dissolved oxygen, pH, sediment grain size, and organic carbon content. The overall purpose of the survey was to collect data to assess the status of ecological condition in coastal-ocean waters of the region, based on these various indicators, and to provide this information as a baseline for determining how environmental conditions may be changing with time. The results will be of value in helping to broaden our understanding of the status of ecological resources and their controlling factors, including impacts of potential ecosystem stressors, in such strategic coastal areas. (PDF contains 34 pages

Cruise Report: Spring 2006 Survey of ecological conditions of the U.S. Middle Atlantic Bight NOAA Ship Nancy Foster NF-06-06-NCCOS (May 12 - May 21, 2006)

This cruise report is a summary of a field survey conducted in coastal-ocean waters of the Mid-Atlantic Bight from Nags Head, North Carolina to Cape Cod, Massachusetts and from approximately 1 nautical mile (nm) of shore seaward to the shelf break (100 m). The survey was conducted May 12 - May 21, 2006 on NOAA Ship NANCY FOSTER Cruise NF-06-06-NCCOS. Multiple indicators of ecological condition were sampled synoptically at each of 49 stations throughout the region using a random probabilistic sampling design. Samples were collected for the analysis of benthic community structure and composition; concentrations of chemical contaminants (metals, pesticides, PAHs, PCBs, PBDEs) in sediments and target demersal biota; nutrient and chlorophyll levels in the water column; and other basic habitat characteristics such as depth, salinity, temperature, dissolved oxygen, pH, sediment grain size, and organic carbon content. The overall purpose of the survey was to collect data to assess the status of ecological condition in coastal-ocean waters of the region, based on these various indicators, and to provide this information as a baseline for determining how environmental conditions may be changing with time. The results will be of value in helping to broaden our understanding of the status of ecological resources and their controlling factors, including impacts of potential ecosystem stressors, in such strategic coastal areas. (18pp.) (PDF contains 24 pages)

Soft-bottom benthic assemblages and levels of contaminants in sediments and biota at Gray's Reef National Marine Sanctuary and nearby shelf waters off the coast of Georgia (2000 and 2001)

A series of studies was initiated to assess the condition of benthic macroinfauna and chemical contaminant levels in sediments and biota of the Gray’s Reef National Marine Sanctuary (GRNMS) and nearby shelf waters off the coast of Georgia. Four key objectives of the research are (1) to document existing environmental conditions within the sanctuary in order to provide a quantitative benchmark for tracking any future changes due to either natural or human disturbances; (2) to examine broader cross-shelf spatial patterns in benthic fauna and sediment contaminant concentrations and to identify potential controlling factors associated with the observed patterns; (3) to assess any between-year temporal variability in benthic fauna; and (4) to evaluate the importance of benthic fauna as prey for higher trophic levels. Such questions are being addressed to help fulfill long-term science and management goals of the GRNMS. However, it is anticipated that the information will be of additional value in broadening our understanding of the surrounding South Atlantic Bight (SAB) ecosystem and in bringing the knowledge to bear on related resourcemanagement issues of the region. We have begun to address the first three of these objectives with data from samples collected in spring 2000 at stations within GRNMS, and in spring 2001 at stations within the sanctuary and along three cross-shelf transects extending from the mouths of Sapelo, Doboy, and Altamaha Sounds out to sanctuary depths (about 17-20 m). This report provides a description of baseline conditions within the sanctuary, based on results of the spring 2000 survey (Section II), and uses data from both 2000 and 2001 to examine overall spatial and temporal patterns in biological and chemical variables within the sanctuary and surrounding inner-shelf environment (Section III). (PDF contains 65 pages)

Streamflow response of a small forested catchment on different timescales

The hydrological response of a catchment to rainfall on different timescales is result of a complex system involving a range of physical processes which may operate simultaneously and have different spatial and temporal influences. This paper presents the analysis of streamflow response of a small humid-temperate catchment (Aixola, 4.8 km(2)) in the Basque Country on different timescales and discusses the role of the controlling factors. Firstly, daily time series analysis was used to establish a hypothesis on the general functioning of the catchment through the relationship between precipitation and discharge on an annual and multiannual scale (2003-2008). Second, rainfall-runoff relationships and relationships among several hydrological variables, including catchment antecedent conditions, were explored at the event scale (222 events) to check and improve the hypothesis. Finally, the evolution of electrical conductivity (EC) during some of the monitored storm events (28 events) was examined to identify the time origin of waters. Quick response of the catchment to almost all the rainfall events as well as a considerable regulation capacity was deduced from the correlation and spectral analyses. These results agree with runoff event scale data analysis; however, the event analysis revealed the non-linearity of the system, as antecedent conditions play a significant role in this catchment. Further, analysis at the event scale made possible to clarify factors controlling (precipitation, precipitation intensity and initial discharge) the different aspects of the runoff response (runoff coefficient and discharge increase) for this catchment. Finally, the evolution of EC of the waters enabled the time origin (event or pre-event waters) of the quickflow to be established; specifically, the conductivity showed that pre-event waters usually represent a high percentage of the total discharge during runoff peaks. The importance of soil waters in the catchment is being studied more deeply.

Oxygen isotopes and volatiles in martian meteorites

Oxygen isotopes were measured in mineral separates from martian meteorites using laser fluorination and were found to be remarkably uniform in both δ18O and Δ17O, suggesting that martian magmas did not assimilate aqueously altered crust regardless of any other geochemical variations.

Measurements of Cl, F, H, and S in apatite from martian meteorites were made using the SIMS and NanoSIMS. Martian apatites are typically higher in Cl than terrestrial apatites from mafic and ultramafic rocks, signifying that Mars is inherently higher in Cl than Earth. Apatites from basaltic and olivine-phyric shergottites are as high in water as any terrestrial apatite from mafic and utramafic rocks, implying the possibility that martian magmas may be more similar in water abundance to terrestrial magmas than previously thought. Apatites from lherzolitic shergottites, nakhlites, chassignites, and ALH 84001 (all of which are cumulate rocks) are all lower in water than the basaltic and olivine-phyric shergottites, indicating that the slow-cooling accumulation process allows escape of water from trapped melts where apatite later formed. Sulfur is only high in some apatites from basaltic and olivine-phyric shergottites and low in all other SNCs from this study, which could mean that cumulate SNCs are low in all volatiles and that there are other controlling factors in basaltic and olivine-phyric magmas dictating the inclusion of sulfur into apatite.

Sulfur Kα X-rays were measured in SNC apatites using the electron probe. None of the peaks in the SNC spectra reside in the same position as anhydrite (where sulfur is 100% sulfate) or pyrite (where sulfur is 100% sulfide), but instead all SNC spectra peaks lie in between these two end member peaks, which implies that SNC apatites may be substituting some sulfide, as well as sulfate, into their structure. However, further work is needed to verify this hypothesis.

Deepwater Horizon oil spill: assessment of potential impacts on the deep soft-bottom benthos; interim data summary report

A study was initiated in May 2011, under the direction of the Deepwater Horizon (DWH) Natural Resource Damage Assessment (NRDA) Deepwater Benthic Communities Technical Working Group (NRDA Deep Benthic TWG), to assess potential impacts of the DWH oil spill on sediments and resident benthic fauna in deepwater (> 200 meters) areas of the Gulf. Key objectives of the study were to complete the analysis of samples from 65 priority stations sampled in September-October 2010 on two DWH Response cruises (Gyre and Ocean Veritas) and from 38 long-term monitoring sites (including a subset of 35 of the original 65) sampled on a follow-up NRDA cruise in May-June 2011. The present progress report provides a brief summary of results from the initial processing of samples from fall 2010 priority sites (plus three additional historical sites). Data on key macrofaunal, meiofaunal, and abiotic environmental variables are presented for each of these samples and additional maps are included to depict spatial patterns in these variables throughout the study region. The near-field zone within about 3 km of the wellhead, where many of the stations showed evidence of impaired benthic condition (e.g. low taxa richness, high nematode/harpacticoid-copepod ratios), also is an area that contained some of the highest concentrations of total petroleum hydrocarbons (TPH), total polycyclic aromatic hydrocarbons (total PAHs), and barium in sediments (as possible indicators of DWH discharges). There were similar co-occurrences at other sites outside this zone, especially to the southwest of the wellhead out to about 15 km. However, there also were exceptions to this pattern, for example at several farther-field sites in deeper-slope and canyon locations where there was low benthic species richness but no evidence of exposure to DWH discharges. Such cases are consistent with historical patterns of benthic distributions in relation to natural controlling factors such as depth, position within canyons, and availability of organic matter derived from surface-water primary production.

内蒙古锡林河流域草原群落土壤呼吸的时空变异及其影响因子研究

　　土壤呼吸是全球碳循环中的一个重要环节，其对全球碳平衡的影响是近年来人们关注的焦点之一。探讨碳素的失汇(missing sink)问题，对陆地生态系统土壤呼吸的研究是必不可少的。环境因子与土壤呼吸之间的关系可以用于将土壤呼吸从“chamber”水平的测量放大到整个生态系统或更大尺度。而温度、水分和植被状况都是对土壤呼吸有重要影响的因子，随着全球气候的变化，这些因子也会发生相应的改变，在这种情况下，它们极有可能与土壤CO2排放之间形成正反馈。温带草原是主要的陆地生态系统类型之一，目前非常缺乏有关土壤呼吸的研究资料。因此，在2001年生长季，我们在内蒙古锡林河流域南部集水区设定了一条东西长约160km、南北宽约30km的样带，从中选择了11个不同的植物群落，采用碱液吸收法周期性地对这些群落的土壤呼吸速率进行同步测定，并对土壤呼吸的时空动态及其与温度、土壤水分和植被状况之间的关系进行了研究。现将主要研究结果概述如下： 　　①锡林河流域南部集水区的土壤呼吸表现出明显的季节变化和空间变异。温度是影响土壤呼吸季节变化的主要因子之一，指数模型能够较好地揭示各群落土壤呼吸对温度变化的响应，但低温时模型的拟合效果更好。各群落土壤呼吸的季节动态与温度变化不完全同步，表明温度并不是影响土壤呼吸的唯一因子 。 　　②土壤呼吸的温度敏感性在各群落之间存在着一定的差异。春小麦群落的Q10值高于草原群落，说明不同的土地利用方式会影响到土壤呼吸对温度变化的敏感程度。水分对土壤呼吸的温度敏感性有重要影响，秩相关分析的结果表明，土壤水分与Q10值之间存在着显著的正相关关系。此外，依据不同土壤层次的温度得出的Q10值各不相同，基于变化幅度大的浅层土壤温度和气温得出的Q10值较小，而根据变化幅度小的深层土壤温度得出的Q10值较大。 　　③水分对各群落的土壤呼吸也有较大影响，但其影响程度有一定的季节差异，生长旺季水分对土壤呼吸的影响显著高于其它季节。从各群落的具体情况来看，水分对土壤呼吸的影响明显受制于群落的水分供应状况。水分供应状况比较好的和水分变化幅度小的群落中，土壤呼吸与水分之间没有显著的函数关系，而水分相对欠缺的群落则存有显著的线性关系。消除温度的影响后，这种线性关系显著增强。土壤水分含量较低的芨芨草群落中，土壤呼吸与表层水分之间的关系也不明显，这与芨芨草根系分布较深，能够利用土壤中较深层次的水分有关。 　　④土壤呼吸季节变化与植被之间的关系与各群落内水分状况以及植被对水分的利用机制有关。所有群落土壤呼吸速率随着绿色活体生物量的增长有上升趋势，且在水分供应充足的群落和植被较为耐旱或能够利用深层土壤水的群落中，这二者之间呈显著或极显著的指数关系，其它群落中相关关系不够显著。由于植被立枯量大小反映了水热的综合状况，所以群落的土壤呼吸速率随立枯量的增长呈下降趋势，二者之间的关系也可以用指数方程来表示。 　　⑤土壤呼吸在锡林河流域南部的空间变异主要受水分和植被状况的影响。总体来看，土壤水分含量高、地上生物量（包括绿色活体生物量）大或地上净第一性生产力高的草地群落，其土壤呼吸速率也较高。基础呼吸速率对于改进土壤呼吸模型在时间和空间上的预测精度有重要意义。我们的研究结果表明，在平均温度低、水分状况好、地上和地下生物量大、地上净第一性生产力高的地方，基础土壤呼吸速率也相应较高。

Numerical simulation of post-flame oxidation of hydrocarbons in spark ignition engines

About 50-90 percent of the hydrocarbons that escape combustion during flame passage in spark-ignition engine operation are oxidized in the cylinder before leaving the system. The process involves the transport of unreacted fuel from cold walls towards the hotter burned gas regions and subsequent reaction. In order to understand controlling factors in the process, a transient one-dimensional reactive-diffusive model has been formulated for simulating the oxidation processes taking place in the reactive layer between hot burned gases and cold unreacted air/fuel mixture, with initial and boundary conditions provided by the emergence of hydrocarbons from the piston top land crevice. Energy and species conservation equations are solved for the entire process, using a detailed chemical kinetic mechanism for propane. Simulation results show that the post-flame oxidation process takes place within a reactive layer where intermediate hydrocarbon products are formed at temperatures above 1100-1200 K, followed by a carbon monoxide conversion region closer to the hot burned gases. Model results show that most of hydrocarbons leaving the crevice are completely oxidized inside the cylinder. The largest contribution of remaining hydrocarbons are those leaving the crevice at temperatures below 1400 K. The largest fraction of non-fuel (intermediate) hydrocarbons results from hydrocarbons leaving the crevice when core temperatures are around 1400 K Copyright © 1997 Society of Automotive Engineers, Inc.

岷江上游人工针叶、阔叶林土壤可溶性有机物质特征及其对凋落物分解的响应

土壤可溶性有机物质（Dissolved organic matter，DOM）作为土壤有机质的活性组分，在陆地生态系统物质循环中扮演非常重要的角色。土壤DOM的主要成分可溶性有机碳（Dissolved organic carbon，DOC）和氮（Dissolved organic nitrogen，DON）参与C、N循环过程。为深入揭示全球C、N循环过程机制，在未开展DOC和DON的地区进行相关研究是有必要的。森林土壤（包括枯枝落叶层）DOC、DON动态及调控机理的研究是目前国际上森林生态系统C、N循环研究热点之一。本研究立足于暖温带岷江上游茂县地区人工林植被，对土壤DOC和DON的库容量，季节动态及其与其它养分之间的关系进行了系统研究，旨在了解DOC和DON在该区生态系统中的重要作用，并探讨作为DOM主要来源的叶凋落物对DOC和DON的动态影响，研究有助于更加详细地了解该区生态系统C和N循环过程。本论文主要研究结论如下： 1研究了岷江上游地区两大主要土壤类型（棕壤和褐土）不同植物群落下土壤的DOC和DON含量及特征，结果表明：DOC和DON在两种土壤类型中均有库容量存在，DOC在0-10cm和10-20cm土层的含量幅度分别111.96~159.95 mg kg-1和69.02~100.84 mg kg-1。DON在0-10cm和10-20cm土层的含量幅度分别11.88~23.08 mg kg-1和4.70~10.77 mg kg-1。游离氨基酸在0-10cm和10-20cm土层的含量幅度分别0.84~1.66 mg kg-1和0.39~0.73 mg kg-1。DOC、DON与土壤中的一些养分因子表现出了显著的相关关系，共同反映了土壤的状况和质量，在该区开展DOC和DON的系统研究是有必要的。 2 对油松与连香树林地土壤DOC、DON以及其它化学指标的季节动态进行了研究，结果表明：油松与连香树林地土壤DOC和DON的季节动态变化表现了类似的规律，DOC和DON的含量均以秋季最高。DOC和DON的季节动态变化主要受凋落物生物因素的影响，但其微生物活力的生物因素以及降雨、温度等非生物因素也是控制土壤DOC和DON含量的重要因素。土壤DON在土壤中的行为不同于矿质氮，其季节动态不同于NO3--N和NH4+-N的季节动态，在研究N循环过程中，应考虑DON的变化情况。 3 对油松与连香树林地分解层和表层土壤（0-10cm）氨基酸周转动态进行了研究，结果表明：油松林地和连香树林地均以分解层的氨基酸含量高于矿质表层土壤的含量。每个取样时期，油松林地内各层次的氨基酸含量高于连香树林地内相应层次的含量。两林地各层次无机氮含量均超过了氨基酸的含量，并且室内培养30天后无机N的含量仍然高于氨基酸的含量，所以可以认为该区立地条件下无论是在有机分解层还是矿质土层植物吸收利用的氮素仍是以无机N为主。 4 松林下松针凋落物易于累积，这与松针凋落物分解缓慢有关，从而导致松林内养分周转缓慢。通过用不同性质凋落物和灌丛地土壤构建微生态系统，比较油松、辐射松、连香树、灌丛虎榛子凋落物分解对C、N循环过程的影响，结果显示油松和辐射松针叶凋落物比连香树、虎榛子凋落物分解更慢，减缓了养分循环过程。然而将针叶凋落物与阔叶凋落物混合后，油松和辐射松针叶凋落物的分解加快，C、N元素的循环过程也加速。此结果表明在松林内维持具有高质量凋落物的灌丛植被或在松林内栽植一些阔叶树种如连香树对维持和增进松树人工林的土壤肥力有重大的作用。室内培养的结果还显示添加凋落物后土壤DOC和DON的含量显著增加，表明凋落物是土壤DOM的直接来源。然而不同物种凋落物处理下土壤DOC和DON的含量有所不同，并随时间发生改变。混合凋落物处理下土壤DOC和DON的含量均高于松针凋落物单独处理下土壤DOC和DON的含量。DON是一个主要的水溶性N库，随时间的变化趋势与无机N的变化趋势不同，在土壤N循环过程中起到了中间N库的作用。 As a labile fraction of soil organic matter, dissolved organic matter (DOM) plays a very important role in material cycling of terrestrial ecosystem. The turnover of DOM is now being considered as main components in nutrient cycling. DOM mainly includes dissolved organic carbon (DOC), -nitrogen (DON), -phosphorous (DOP) and –sulfur (DOS). Among these constituents, DOC and DON directly participate in C and N cycling. It is essential to study DOC and DON dynamics and their controlling factors in the areas where no related study has ever been carried out. Study about them can provide data supports on understanding the mechanism of the global C and N cycling. DOC and DON dynamics and their controlling factors have been focused on in the research of C and N cycling of forest ecosystems. Based on forest plantations of Maoxian, Minjiang River in warm temperate zone, soil DOC and DON pool size, their seasonal dynamics, and the correlation between DOC, DON and other nutrients were studied in order to understand the importance of DOC and DON in the study area. Soil DOC and DON dynamics induced by leaf litter decomposition were also studied. The study contributed to comprehensively understanding C and N cycling processes and providing baseline data for including DOC and DON into the indices system of evaluating nutrient conditions. The results were as follows: 1 Several different plant communities under brown soil and Cinnamon soil were chosen as sampling plots. The contents and features of soil DOC and DON were evaluated. The results showed that DOC and DON were present under the two soil types. DOC contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 111.96 mg kg-1to 159.95 mg kg-1, and 69.02 mg kg-1 to 100.84 mg kg-1. DON contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 11.88 mg kg-1to 23.08 mg kg-1, and 4.70 mg kg-1 to 10.77 mg kg-1. Free amino acid contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 0.84 mg kg-1to 1.66 mg kg-1, and 0.39 mg kg-1 to 0.73 mg kg-1. Significant correlations were found between DOC, DON and some nutrient indices, which together reflected soil condition and quality. It was hence essential to study DOC and DON in the study area. 2 Seasonal dynamics of DOC, DON, inorganic N, microbial biomass C and N were studied under Pinus tabulaeformis and Cercidiphyllum japonicum plantation. The results indicated that seasonal dynamics of soil DOC and DON under the two plantations performed similar change pattern, with the highest values in autumn. The seasonal dynamics of soil DOC and DON were mainly influenced by the litterfall. However, biotic factors such as soil microbial activities and abiotic factors such as precipitation and temperature also controlled the dynamics of soil DOC and DON. The seasonal dynamic of DON was different from that of NO3--N and NH4+-N, which showed that the behavioral differences between DON and inorganic nitrogen. And hence, it was proposed to include DON into soil N cycling in the study area. 3 Amino acid dynamics in Oa and topsoil (0-10 cm) under P. tabulaeformis and C. japonicum plantation were studied. The results showed that amino acid content in Oa was significantly higher than that in mineral soil. At each sampling time, significantly higher amino acid contents were found in P. tabulaeformis plantation than in C. japonicum plantation. The content of inorganic nitrogen was much higher than the content of amino acid in each sampling layer at each sampling time. After a 30-days laboratory incubation the content of amino acid was still lower than the content of inorganic nitrogen. The results implicated that the form of N absorbed by plants in these study sites were mainly inorganic nitrogen. 4 Usually needle litter is more resistant to decomposition, which leads to needle litter accumulation in pure coniferous stands and slows down the rate of nutrient circulation. By constructing microcosms with local shrubland soil and containing the four single-species (P. tabulaeformis, P. radiata, C. japonicum, Ostryopsis davidiana) litters, the decomposition rates and related C and N dynamics of needle litters and broadleaved litters during the early stage were compared. The results showed that the decomposition rates of pine needles were lower than those of broadleaved litters, which descended C and N cycling processes. However, the presence of C. japonicum or O. davidiana litter into pine needles increased the decomposition rates of pine needles and also dramatically promoted C and N cycling processes. It should be appropriate for plantation managers to consider C. japonicum as an ameliorative species or remain O. davidiana in pine plantations to improve soil conditions and help maintain soil fertility. The laboratory incubation still showed that DOC and DON contents in all litter-amended treatments were significantly higher than no litter-amended treatment, which proved that litter could be a direct source of DOM in soils. Different species litters induced different soil DOC and DON contents, which correspondingly changed over time. DOC and DON contents in mixed litter treatments were higher than those in pine needle litter treatments. As a major soluble N pool, DON developed a different changing pattern over time compared with inorganic N and played a role of interim N pool in soil N cycling.

Benthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough: dependance on water masses and food supply

Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modem shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata, Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispida, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4), lower continental slope - trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp., Bathysiphon flavidus, corresponds to I strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope. of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.

Os isotope dating and growth hiatuses of Co-rich crust from central Pacific

Up to now, accurate determination of the growth age and hiatuses of the Co-rich crust is still a difficult work, which constrains the researches on the genesis, growth process, controlling factors, regional tectonics, paleo-oceanographic background, etc. of the Co-rich crust. This paper describes our work in determining the initial growth age of the Co-rich crust to be of the late Cretaceous Campanian Stage (about 75-80 Ma), by selecting the Co-rich crust with clear multi-layer structures in a central Pacific seamount for layer-by-layer sample analysis and using a number of chronological methods, such as Co flux dating, dating by correlation with Os-187/Os-188 evolution curves of seawater, and stratigraphic division by calcareous nannofossils. We have also discovered growth hiatuses with different time intervals in the early Paleocene, middle Eocene, late Eocene and early-middle Miocene, respectively. These results have provided an important age background for further researches on the Co-rich crust growth process and the paleo-oceanographic environment evolution thereby revealed in the said region.