Ammonium regeneration in intertidal sediments of the Yangtze estuary during air-exposure

The influences of exposure to the atmosphere on ammonium cycle in the intertidal surface sediments were in situ studied with a geochemical approach at a typical station in the Yangtze Estuary during three tidal cycles in September 2003. During an about 8-h emersion period of each diurnal tide, six high-resolution vertical profiles of adsorbed and dissolved ammonium were measured. It was observed that both adsorbed and dissolved ammonium generally had an increasing trend in sediment cores during the exposure. The rate of ammonium regeneration in sediments was estimated using the accumulation amount of ammonium including adsorbed and soluble fractions during the daytime emersion. The calculation result showed that there was relatively high ammonification rate (˜500 nmol N cm⁻³ day⁻¹), which reflected that organic nitrogen in sediments was quickly decomposed with a residence time of ˜52.7 days. Due to the dramatic temperature difference observed in sediment profiles, free convection was considered an important mechanism of regulating the efflux of produced ammonium into overlying waters. The total estimated amount of regenerated ammonium was ˜1.35×10⁵ t N year⁻¹ in the intertidal flat of the Yangtze Estuary, which occupied 7.6% of the total inorganic nitrogen annually transported to the estuarine ecosystem.     

基于GIS的商业网点选址研究与实现

利用平面／网络优化模型，综合权衡市区选址的基本费用及商业网点日常经营的成本，引入交通便利因子作为限制条件，并运用直接搜索的Dixon方法，加强了不确定性选址问题的约束条件，降低不确定性问题计算的复杂度，减少在选址问题实现中主观因素对选址结果的影响。最后以某区新建商业网点选址为例，详细分析了直接搜索算法应用的具体过程。     

淄博市洪山、寨里煤矿地下水串层污染形成原因及防治

淄博市洪山、寨里煤矿区隐伏的奥陶系灰岩裂隙岩溶水污染严重。水质污染突发于矿坑全面闭坑以后，污染范围与矿坑水区一致，地下水污染组份与矿坑水的高含量组份相同。水质恶化主要由矿坑水串层污染所致。在此针对串层污染形成原因及影响因素，提出了防治对策。     

全国资源与生态环境遥感监测数据管理与应用服务系统设计

为推动资源与生态环境遥感监测数据的应用与服务,为国家、相关行业管理决策和社会公众提供有价值的信息,需要在资源与生态环境遥感监测成果数据基础上,开发数据管理与应用服务系统。本文从国家资源与生态环境建设的实际需求出发,结合国土资源部实施的环北京地区资源与生态环境遥感监测成果,探讨资源与生态环境遥感监测数据管理与应用服务的技术解决方案,搭建资源与生态环境遥感监测数据管理与应用服务技术平台,并实现网络环境下对资源与生态环境监测形成的各种类型数据的集成化管理。     

2004年夏季哈尔滨 5次短时强降水天气过程的对比分析

2004年夏季, 哈尔滨在 40d中发生了 5次短时强降水灾害,城市内涝严重,部分交通干线瘫痪.短时强降水天气多发生于中小尺度天气系统,空间尺度小,生命史短,预报难度大.虽然前人在此方面已做过大量工作,但在干旱的气候背景下,为什么频繁发生短时强降水天气,它们的共同特征是什么？本文从环流条件、卫星云图、多普勒雷达回波以及物理量场进行分析,对上述问题进行了探讨.     

用逐步回归预测棉铃虫发生期和发生量

收集了1973年至2000年的气象，农作物、棉铃虫虫害等196年因子，以运城、汾阳和临汾为山西省代表站，利用最优二分割法把发生量分为10级，5级和不分级3种情况；使用逐步回归计算了219个模型，从中选出27个棉铃虫二、三代发生期，发生量最优模型，在农气服务中应用，预报准确率为95％，效果良好。     

安徽凤阳和张八岭地区含金石英脉的40Ar/39Ar年龄及其地质意义

用快中子活化法测定了安徽凤阳和张八岭地区朱顶、毛山和上成3个金矿床第一阶段晚期和第二阶段的含金石英脉,石英的阶段加热40Ar/39Ar坪年龄值域为(116.1±0.6～118.3±0.5)Ma,分别与其最小视年龄和等时线年龄接近.坪年龄、最小视年龄和等时线年龄3种年龄值域为(113.4±0.4～118.3±0.5)Ma,可以作为石英的形成年龄域. 根据含金石英脉和围岩的空间关系,该年龄值域作为石英脉金矿的形成年龄是合理可靠的.金矿床形成于早白垩世阿普特期,与此时郯庐断裂带略带右行走滑正断层活动一致.     

A decade of change in the Skidaway River estuary I. Hydrography and nutrients

The Skidaway River estuary is a tidally-dominated subtropical estuary in the southeastern USA surrounded by extensiveSpartina salt marshes. Weekly smapling at high and low tide began in 1986 for hydrography, nutrients, chlorophylla, particulate matter, and microbial and plankton biomass and composition; hydrographic and nutrient data during 1986–1996 are reported here. Salinity varied inversely with river discharge and exhibited variability at all time scales but with no long-term trend. Water temperature typically ranged over 25°C and was without apparent long-term frend. Seasonal cycles in concentrations of NO₃, NH₄, PO₄, Si(OH)₄, and DON were observed, with annual maxima generally occurring in late summer. Superimposed on seasonal cycles, all five nutrients exhibited steady increases in minimum, mean, and maximum concentrations; mean concentrations increased c. 50–150% during the decade. Nutrient concentrations were highly correlated with water temperature over the ten-year period, but weakly related to salinity and discharge. Nutrients were strongly correlated with one another, and the relative ratios among inorganic nutrients showed little long-term trend. Correlations among temperature and nutrient concentrations exhibited considerable inter-annual variability. Major spikes in organic and inorganic nutrient concentrations coincided with significant rainfall events; concentrations increased hyperbolically with rainfall. Although pristine compared to more heavily impacted waterways primarily outside the region, residential development and population density have been increasing rapidly during the past 15–20 years. Land use is apparently altering nutrient loading over the long-term (months-years), and superimposed on this are stochastic meteorological events that accelerate these changes over the short term (days-weeks).     

中原地区M≥6级地震后的减(增)震效应

通过对中原地区1500年－2000年所有19次M≥6级地震后空间图像的分析，初步认为M≥6级地震发生后平均63年内，在距原震中平均176km内无M≥5级地震发生，全部19次震例均呈现出内部减震效应，而在其外围出现地震增强的活动图像特征，增震效应对应率为72％。这种强震后的减（增）震效应，不仅对地震危险性分析，而且对1年尺度以上的地震趋势预测均有一定的意义。     

Kosa (yellow sand) components in precipitation collected at central Japan

In east Asia, acidic gases derived from fossil fuel combustion have increased in the past decades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported following windstorms from arid lands in the Asian continent. Many researchers have been interested in the reaction between acidic aerosols and Kosa aerosols as well as the long-range transport of these emissions. To investigate the characteristics of chemical components in precipitation on a long-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997 at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1 mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitation events with an automatic wet only precipitation collector. According to the analyses of precipitation including Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidic components during the long-range transport was discussed.