热分解法测定水盐体系中硝酸铵和水含量研究

针对复杂硝酸铵水盐体系溶解度的测定,传统分析方法操作步骤繁琐,且试剂较贵,引入一种简单准确的分析方法,即热分解法,对LiNO3-KNO3-NH4NO3-H2O体系和NaNO3-KNO3-NH4NO3-H2O体系中硝酸铵和水的含量进行精确分析。结果表明,热分解温度控制在230～240℃,若控制样品质量为1.5 g,分解时间不低于36 h,能将LiNO3-KNO3-NH4NO3-H2O体系中的硝酸铵和水彻底分解,且随着样品中硝酸铵含量增加,热分解时间也将延长,分析相对误差能控制在0.2%以内。针对复杂NaNO3-KNO3-NH4NO3-H2O体系,热分解温度控制在230～255℃,若控制样品质量为1.5 g,分解时间不少于44 h,且随着样品中硝酸铵含量的增加,相应延长热分解时间,能将复杂NaNO3-KNO3-NH4NO3-H2O体系中的硝酸铵和水彻底分解,分析相对误差能控制在0.2%以内。     

莱西地区施肥对地下水硝酸盐污染的过程

通过实地调查和渗水、硝化、吸附、弥散等室内外试验,获取了所需水文地质参数。利用VS2D/T(Variably Saturat-ed 2-D Flow and Transport Model)模型,建立了莱西地区包气带水流-溶质运移模型,分析了莱西地区施肥过程中对地下水的硝酸盐污染。研究结果表明,氮肥中的硝酸盐对地下水的补给量占当次施肥量的24%和43%,进入到地下水中硝酸盐的平均浓度分别约为130mg/L和177mg/L,远高于当地地下水中硝酸盐63.5mg/L的平均浓度,说明不合理的施用氮肥是造成莱西地区地下水硝酸盐污染的1个主要原因。通过模拟不同灌溉和施肥模式下对地下水的硝酸盐污染,得出灌溉方式的改变对于减少施肥造成的地下水硝酸盐污染的作用最大。     

胶州湾双壳类壳体中的Ca,Mg,Mn,Sr元素组成及影响因素

探讨影响双壳类元素组成的可能因素,从胶州湾沿岸不同取样点采集黄海近海常见的菲律宾蛤仔(Ruditapesphilippinarum)、褶牡蛎(Oystrea denselamellosa)和紫贻贝(Mytilus galloprovincialis),分别测量了3种壳体的矿物物相类型和壳体中的Ca,Mg,Mn,Sr元素组成。研究表明:3种壳体分别属于文石质、方解石质和混合质壳;Ca,Mn元素含量在菲律宾蛤仔、褶牡蛎和紫贻贝壳体中没有差别,而Mg元素含量在菲律宾蛤仔壳体中含量较低,在褶牡蛎壳体和紫贻贝壳体中含量较高,Sr元素恰好与Mg元素相反。双壳类壳体中元素组成主要受壳体矿物物相类型的制约,而与水体环境要素之间的关系弱。     

Microbial nitrogen transformations in sediments and inorganic nitrogen fluxes across the sediment/water interface on the South Island West Coast,New Zealand

In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar $\text{C}\text{N}$ ratio of 5.9–10.9, and the total $\text{N}\text{P}$ ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m^?2 day^?1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m^?2 day^?1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m^?2 day^?1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m^?2 day^?1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m^?2 day^?1, respectively.     

官厅水库及永定河枯水期水体氮、磷和重金属含量分布规律

于枯水期 (冬季和春季 )在官厅水库库区及永定河沿线 1 3个地点采集了表层水样品 ,分别测定了原水和过滤水中 N、P和重金属的含量 ,同时进一步分析了过滤水中不同形态氮的含量 ,初步探讨了枯水期官厅水库和永定河水体 N、P及重金属含量的分布规律及污染特征。研究结果表明 ,官厅水库库区及永定河沿线重金属基本没有污染 ,大多低于地表水 类标准 ,极个别样点超过 类但仍低于 类标准。 N、 P污染比较严重 ,大部分样点的总氮、总磷指标超过湖泊水库 类标准 ,个别样点甚至超过 类标准。不同地点 ,各形态 N的含量有显著差别 ,体现了外源污染的区域分布规律。     

Measurement of gaseous HNO3 over the Atlantic Ocean

A latitudinal profile (30° W, from 30° N to 30° S) of mixing ratios of nitric acid and particulate nitrate was determined on the Atlantic Ocean during the Polarstern cruise ANT VII/1 from Bremerhaven, Germany, to Rio Grande, Brazil. The detection of HNO₃ was performed simultaneously by laser-photolysis fragment-fluorescence (LPFF) and by nylon filter packs. The detection limit was about 30 pptv for a signal accumulation time of 1 h for LPFF and about 5 pptv for the filters at a collection time of 4 h. In general, the mixing ratios of HNO₃ in the Northern Hemisphere were found to be significantly higher than those in the Southern Hemisphere. The Atlantic background concentrations frequently varied between 80 pptv and the detection limit. Larger deviations from this trend were found for the more northern latitudes and for episodes like crossings of exhaust plumes from ships or from continental pollutions sources.     

峰高与峰面积统计量表示岩心黏土矿物相对含量的差异

目前黏土矿物分析主要依据XRD衍射峰的峰高或峰面积统计量,为了分析两种统计量计算黏土矿物相对含量的差异。对取自黄海的YSZD02岩心短柱开展了黏土矿物XRD测试,分别利用峰高和峰面积表示4种主要黏土矿物蒙皂石、伊利石、高岭石、绿泥石的相对百分含量,探究两种统计量表示黏土矿物相对含量随深度变化的差异,结果发现两算法都能显示黏土矿物的相对组成特征,对YSZD02岩心而言,其黏土矿物主要为伊利石,其次为高岭石,再次为绿泥石,最次为蒙皂石。两种算法得到的4种矿物的相关系数由高到低依次为:高岭石0.94,绿泥石0.93,蒙皂石0.82,伊利石0.73,呈正相关。峰面积法求4种矿物的相对含量随深度变化的离散程度比峰高法大。用峰高、峰面积法表示黏土矿物相对含量随深度的变化,两种方法相对差异由小到大依次为伊利石,高岭石,绿泥石和蒙皂石。以上结果表明两种算法既有共性又有明显的差异。随着分析技术的不断更新,相较于峰高法较难解决的误差问题,未来峰面积法会得到更广泛的应用。因此研发更精确的计算机分析软件、统一研究方法将是未来发展的必然趋势。本文的研究加深了对峰高与峰面积统计量的理解,为其他分析方法的比较与选择提供了参考。     

THE RADIATIVE EFFECTS OF ANTHROPOGENIC AEROSOLS OVER CHINA AND THEIR SENSITIVITY TO SOURCE EMISSION

In this paper,the RIEMS 2.0 model,source emission in 2006 and 2010 are used to simulate the distributions and radiative effects of different anthropogenic aerosols over China.The comparison between the results forced by source emissions in 2006 and 2010 also reveals the sensitivity of the radiative effects to source emission.The results are shown as follows:(1) Compared with those in 2006,the annual average surface concentration of sulfate in 2010 decreased over central and eastern China with a range of-5 to 0 μg/m~3;the decrease of annual average aerosol optical depth of sulfate over East China varied from 0.04 to 0.08;the annual average surface concentrations of BC,OC and nitrate increased over central and eastern China with maximums of 10.90,11.52 and 12.50μg/m~3,respectively;the annual aerosol optical depths of BC,OC and nitrate increased over some areas of East China with extremes of 0.006,0.007 and 0.008,respectively.(2)For the regional average results in 2010,the radiative forcings of sulfate,BC,OC,nitrate and their total net radiative forcing at the top of the atmosphere over central and eastern China were-0.64,0.29,-0.41,-0.33 and-1.1 W/m~2,respectively.Compared with those in 2006,the radiative forcings of BC and OC in 2010 were both enhanced,while that of sulfate and the net radiative forcing were both weakened over East China mostly.(3)The reduction of the cooling effect of sulfate in 2010 produced a warmer surface air temperature over central and eastern China;the maximum value was 0.25 K.The cooling effect of nitrate was also slightly weakened.The warming effect of BC was enhanced over most of the areas in China,while the cooling effect of OC was enhanced over the similar area,particularly the area between Yangtze and Huanghe Rivers.The net radiative effect of the four anthropogenic aerosols generated the annual average reduction and the maximum reduction were-0.096 and-0.285 K,respectively,for the surface temperature in 2006,while in 2010 they were-0.063 and-0.256 K,respectively.In summary,the change in source emission lowered the cooling effect of anthropogenic aerosols,mainly because of the enhanced warming effect of BC and weakened cooling effect of scattering aerosols.     

Groundwater vulnerability assessment based on modified DRASTIC model: a case study in Changli County,China

Groundwater vulnerability assessment has been regarded as the initial step to understand and evaluate the susceptibility of the subsurface to contamination. As one of the most widely used models, the DRASTIC has been applied worldwide. However, problems associated with the model, such as the subjectivity in rating and weighting schemes, have led to modified versions of this model for better representing the vulnerability of the aquifer. In this study, a modified DRASTIC model was formulated by adjusting the rating and weighting scores based on Wilcoxon rank-sum test and Analytic Hierarchy Process. The modified model was then applied to the evaluation of groundwater vulnerability in Changli County, China in a GIS environment. The validity of the model was verified by analysing the correlation coefficient between the vulnerability index and the nitrate concentration. The results revealed that the modified DRASTIC model presents stronger correlation with the nitrate contamination than the traditional DRASTIC model.     

From stay to play – A travel planning tool based on crowdsourcing user-generated contents

Conventional ways of trip planning using online reviews from multiple sources are often cumbersome and uncustomizable. The advance in information and communication technology (ICT) and the surge in user-generated contents (UGC) provide great opportunities to facilitate trip planning. This paper proposes a travel-planning tool by crowdsourcing multiple UGCs to provide customized information for tourists. We harvested hotel customer reviews from TripAdvisor, photo information from Flickr, and travel costs between destinations from Uber. First, we used geospatial data mining approaches to extract tourism attractions information from Flickr; identified multi-facet characteristics of hotels with natural language processing (NLP); and provided travel route recommendations with graph analysis. Second, we developed a web-based interface to let users communicate with the system interactively, which provides integrated recommendations including attractions, hotels, and visit route sequences. Two cities in the United States (i.e. Atlanta and Chicago) were used as cases to illustrate our approaches. The proposed travel planning tool is not only beneficial to support customized travel decision-making, but also supportive for hotel managers with strategic management implications.