Composition and source apportionment of dust fall around a natural lake

The aim of this study was to determine the source apportionment of dust fall around Lake Chini, Malaysia. Samples were collected monthly between December 2012 and March2013 at seven sampling stations located around Lake Chini. The samples were filtered to separate the dissolved and undissolved solids. The ionic compositions(NO-3, SO2-4, Cl-and NH+4) were determined using ion chromatography(IC) while major elements(K, Na, Ca and Mg) and trace metals(Zn, Fe, Al, Ni, Mn, Cr, Pb and Cd) were determined using inductively coupled plasma mass spectrometry(ICP-MS). The results showed that the average concentration of total solids around Lake Chini was 93.49 ± 16.16 mg/(m2·day). SO2-4, Na and Zn dominated the dissolved portion of the dust fall. The enrichment factors(EF) revealed that the source of the trace metals and major elements in the rain water was anthropogenic, except for Fe. Hierarchical agglomerative cluster analysis(HACA) classified the seven monitoring stations and 16 variables into five groups and three groups respectively. A coupled receptor model, principal component analysis multiple linear regression(PCA-MLR), revealed that the sources of dust fall in Lake Chini were dominated by agricultural and biomass burning(42%),followed by the earth's crust(28%), sea spray(16%) and a mixture of soil dust and vehicle emissions(14%).     

爆炸超压场景下危化品社会风险对允许规划人口密度的影响分析*

为研究危化品重大危险源基于社会风险基准的规划管控影响,采用我国标准规定的定量风险评价方法,TNT当量炸药简化方法,针对最大TNT当量炸药、事故发生总累计频率、人口密度分布控制参数等不同工况条件,对比分析国土开发强度的允许人口密度受社会风险约束影响的变化规律。研究结果表明:人口密度指数分布控制参数Nk与Nb的允许取值随最大TNT当量炸药和事故发生总累计频率降低而提高;确定工况下,允许总人口规模受最大TNT当量炸药影响很小;在最大TNT当量炸药大于100 t或事故发生总累计频率小于1×10-8次/a时可按最大事故场景进行规划控制分析。     

深埋水平岩层隧道开挖稳定性分析及控制*

针对深埋高地应力水平岩层掌子面开挖稳定性及支护结构失效问题,以大峡谷隧道为工程背景,通过现场测试、室内试验、数值模拟等方法,探究深埋高地应力水平岩层失稳机理及控制措施。研究结果表明:坚硬岩体被节理面切割后,在高地应力作用下容易发生挤压破碎,破碎岩体遇水发生软化,导致掌子面发生大范围塌方,初支和超前支护失效;隧道开挖后岩层发生不均匀沉降,浅部岩层最先发生弯折破坏,层内块体错动滑移,继而向上方岩层发展,并伴随层间分离和层内裂隙发育,最终形成宏观破裂面;提出的台阶法、2 m开挖进尺、砼喷层、双层小导管、提高初支强度的整体优化控制措施,可有效提高现场支护效果。     

焙烧炉筒体结构强度有限元分析

对焙烧炉筒体结构进行有限元建模仿真,考虑热应力、压力和重力对筒体结构受力的影响,计算了焙烧炉关键部位的蠕变疲劳寿命,同时探究进气温度、保温层及对流系数等参数的影响。结果表明:热应力是影响结构强度的关键因素;焙烧炉筒体在许用蠕变变形量为5%的情况下,其使用寿命超过设计寿命;在筒体加热过渡段铺设保温层,降低与外界空气对流和提高进气温度,有利于降低筒体应力。     

关于区域可持续发展的系统分析

本文从更高、更新、更综合的高度和角度,对区域社会可持续发展系统进行了单元要素分析、结构层次分析。提出了三单元要素、三结构层次、三种发展类型的设想。这种分析尽管还是初步的、定性的、不很深刻的,但是为研究可持续发展系统提供了一种新的思路。     

The Chemistry of Throughfall, Stemflow and Soil Water Beneath Oak Woodland and Moorland Vegetation in Upland Wales

The chemistry of bulk precipitation, throughfall, stemflow and soil waters beneath an oak wood (Quercus petraea) canopy and soil waters under moorland vegetation were measured at two sites on acid brown podzolic soils near Llyn Brianne in rural mid-Wales, UK. Between March 1986 and November 1988, precipitation was 4354 mm and annual interception losses from the oak canopy averaged 13% of incident precipitation. Throughfall and stemflow were more acid and concentrations of most solutes were increased 2- to 4-fold compared with bulk precipitation. Nitrate was the only solute retained within the tree canopy. Throughfall collected beneath patches of bracken on the forest floor was less acidic but contained substantially higher concentrations of major ions than bulk precipitation and oak throughfall. the moorland soil was more acidic, contained more exchangeable calcium but less exchangeable aluminium and potassium than the woodland soil. Soil waters beneath both vegetation types were acidic (mean pH range 4.5-4.9) and dominated by sodium and chloride. with the exception of calcium, soil water solute concentrations were greater beneath oak. These differences are ascribed to larger atmospheric inputs beneath the oak canopy compared with the shorter grasses, combined with the effect of differences in nutrient dynamics and water fluxes. Variations in soil water aluminium chemistry are explained in terms of ion exchange and podzolisa-tion processes. the water quality implications of increased upland afforestation of moorland by broadleaved trees are discussed.     

Ammonia volatilization and availability of Cu, Zn induced by applications of urea with and without coating in soils

Ammonia volatilization and the distribution of Cu and Zn were investigated in two types of soil treated with coated and uncoated urea. The rate of ammonia volatilization in two weeks after fertilizing with coated urea was 8% in soil 1 (soil derived from river alluvial deposits in Dongting Lake Plain) and 5.15% in soil 2 (red soil derived from quaternary red clay), about half the rates observed when fertilizing with common urea, implying that the hydrolysis speed of the coated urea was lower than for common urea, and that the coated urea can increase nitrogen use efficacy. As for the availability of Cu and Zn, their concentrations decreased in the first week after fertilization, and then increased, which was contrary to the effect of treatment on soil pH. For example, when the pH was 7.99, there was 0.79 mg/kg exchangeable Cu and 0.85 mg/kg exchangeable Zn in the soil derived from river alluvial deposits in Dongting Lake Plain. However, the concentrations of exchangeable Cu and Zn were generally lower for the common urea treatments than those with the coated urea because the peak pH for the common urea treatment was greater. The concentrations of these elements correlated well with pH in the range 4-8 in second order polynomial fits.     

藏南羊卓雍错湖水化学空间分异特征

2010年7月对藏南羊卓雍错流域进行了水样采集,通过测定与分析,揭示了流域最大湖泊羊卓雍错表层湖水化学水平分布特征和深水剖面变化规律,并探讨了该湖与流域其他水体化学性质的差异。结果表明:流域特殊的高寒气候、湖泊形状与补给来源、湖岸水系发育程度不同是造成羊卓雍错湖水化学空间分异特征明显的关键。在水平方向上,湖水HCO3-、Ca2+以及矿化度南高北低,而SO42-和Mg2+南低北高。这是由于湖水从南向北缓慢流动过程中蒸发浓缩所致;卡鲁雄曲径流量经空姆错补给羊卓雍错北部,使其矿化度较低。在垂直方向上,愈向湖泊深处,湖水SO42-、Cl-、CO32-和矿化度愈大,HCO3-则降低。与流域其他湖泊相比,羊卓雍错水化学性质与同属以降水补给为主的湖泊相近,与以冰雪融水补给为主的湖泊差异显著。与河水和地下水相比,羊卓雍错湖水SO42-和Mg2+当量浓度最大,河水和地下水则HCO3-和Ca2+含量较大。     

某海洋平台上海水篮式过滤器事故分析

目的研究分析东海某一海上平台海水用篮式过滤器发生的腐蚀和堵塞事故原因。方法从海洋平台海水系统用篮式过滤器的原理、工艺流程、材料选择、滤网精度,滤芯设计、人工操作等多方面进行分析。结果受内压滤芯结构要优于受外压滤芯结构,如果过滤精度选择过高,会增加压差,造成滤芯堵塞。结论篮式过滤器滤芯单元应采用多滤芯的受内压结构,过滤精度应根据下游用户要求来确定。     

闽江口秋茄红树林凋落物产量及分解动态

于2017年以闽江口粗芦岛秋茄(Kandelia obovata)红树林为研究对象,分别采用凋落物收集框和分解袋法,研究秋茄凋落物产量及其碳(C)、氮(N)、磷(P)含量月动态及凋落叶分解过程中C、N、P含量与水解酶活性.结果表明:①秋茄凋落物年产量为618.79 g·m~(-2)·a~(-1),其中,叶占61.2%,果、枝和花分别占23.7%、10.5%和4.6%.②凋落叶总氮(TN)含量8月显著高于其他月份(p0.05),而TP含量在1—3月显著高于其他月份;C/N在8月显著低于其他月份(p0.05),而C/P及N/P在9月显著升高(p0.05).③在凋落叶分解过程中,C、N、P含量及其化学计量比随时间存在明显差异(p0.01),并且地上组TC、TN、C/N和C/P明显不同于地下组(p0.05).④在分解过程中,4种水解酶随时间存在明显差异(p0.01).⑤凋落叶酸性磷酸酶活性与土壤温度、电导率和凋落叶TP含量存在显著相关关系(p0.01).这些结果说明,秋茄凋落物产量及元素含量随季节变化存在明显差异;沉积作用对凋落叶分解过程中元素含量有显著影响,水解酶活性主要受凋落叶元素含量和土壤环境因子的控制.