Engineering and microstructure properties of contaminated marine sediments solidified by high content of incinerated sewage sludge ash

Management of incinerated sewage sludge ash(ISSA) and dredged contaminated marine sediments(CMSs) is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20% of sediment by mass) of ISSA in combination with cement/lime for solidification/stabilization(S/S) treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(～80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC) for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10% of lime and 20% of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(C-S-H)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.     

挂式沉箱干作业法加固水中桥墩的工程应用

在水中要对桥梁的墩柱进行加固的主要困难是构建隔离水的施工操作空间,特别是需要加固的部位在水中墩柱的上半部分而水底又很深时采用传统的沉底式沉箱干作业法施工造价很高。本文介绍一种新颖、费用低廉的挂式沉箱,箱体与墩柱之间采用专用自适应变截面橡胶带止水和混凝土封闭二道止水装置,能够有效解决水中桥墩加固的施工空间问题,并详细介绍了具体的工程应用实例。     

胸腔积液引流沉淀物组织病理学检查对恶性胸腔积液患者诊疗价值评估

目的:评估胸腔积液引流沉淀物组织病理学检查对恶性胸腔积液(Malignant pleural effusion,MPE)的诊断价值。方法:选择2012年5月至2014年3月在我院接受治疗的MPE患者120例,所有患者用中心静脉导管行胸腔闭式引流,引流沉淀物行组织病理学检查(组织病理法),同时胸腔积液行脱落细胞学检查作为对照组(细胞学法);比较两种方式的诊断准确性。结果 :组织病理法检查出MPE阳性108例,阳性率为90.0%,细胞学法检出MPE 77例,诊断阳性率为64.2%,两组阳性检出率相比,差异具有统计学意义(P<0.05);组织病理法检出的108例中,明确组织类型者105例,明确率为97.2%,而细胞学法检出的77例中,明确组织类型者61例,明确率为79.2%,两组组织类型明确率相比,差异具有统计学意义(P<0.05)。结论 :胸腔积液引流沉淀物组织病理学检查对MPE诊断准确率高,具有微创和快速特点,值得临床进一步推广。     

下荆江熊家洲至城陵矶弯曲型河段河床调整规律

三峡水库运用后, 坝下游水沙过程发生了较大调整, 对下荆江熊家洲至城陵矶弯曲型河段河床冲淤演变造成较大影响, 从而对本河段河势稳定、防洪、航运等可能造成不利的影响, 基于此, 根据最新实测资料分析水沙条件变 化及其对本河段河床调整规律的影响。研究成果显示: 三峡水库运用后, 水流含沙量大幅减小, 且水库调蓄导致熊 家洲至城陵矶河段在枯水期径流量明显增加, 使弯道主流长期偏向于凸岸, 引起凸岸边滩大幅冲刷, 这是近期该河段发生“撇弯切滩”的主要原因之一; 随着三峡上游干支流水库群陆续建成运用, 坝下游河道将会长期遭受清水冲 刷, 河床仍将呈单向冲刷下切的趋势, 弯顶段主流平面摆动仍将较大, 弯道顶冲点也将相应下移, 导致主流贴岸距离 进一步下延, 引起河道岸线的崩退, 未来一段时期内典型弯曲型河道的局部河势变化仍将明显。     

三门峡水库汛期排沙效果研究

三门峡水库汛期排沙是解决泥沙淤积问题、控制潼关高程的关键途径。"蓄清排浑"运用以来,非汛期蓄水期库区发生淤积、汛期降低水位运用排泄全年泥沙,基本保持了库区动态冲淤平衡。不同控制水位和入库流量过程存在不同的排沙效果,针对三门峡水库汛期排沙过程的差异,对"蓄清排浑"运用以来汛期排沙特征进行统计,分析了水库敞泄和不同控制水位运用对排沙效果的影响。结果表明,在汛期平水305 m、洪水敞泄的运用条件下,水库排沙具有多来多排的特点,汛期排沙总量与入库含沙量和水量密切相关;完全敞泄时库区冲刷取决于流量大小和敞泄时间,净排沙效率随着水量的增加和敞泄时间的延长而减小,冲刷效率降低;汛期控制运用期,当流量在1000 m~3/s以上时、水位在305～311 m也会产生一定的排沙,排沙效果取决于含沙水流在壅水段的滞留时间和出入库流量之比。研究成果可为三门峡水库运用方式的优化提供依据。     

Sediment-associated metals levels along the sewer-natural treatment wetland continuum,Phnom Penh,Cambodia

Sediment deposited within open sewers of Phnom Penh and the natural wetland that treats the waste was sampled and analyzed by X-ray fluorescence (XRF). Mean levels of Pb, Zn (P < 0.05), and Cu (P = 0.08) were greater in the sewer samples than the wetland, while As was not different (P>0.2), and Mn was greater (P < 0.06) in the wetland. Pb, Cu, and Zn levels generally were lower at the wetland outlet and in quiescent areas, suggesting deposition occurs along the sewer/wetland continuum. Background (natural) levels of Mn and As are higher in soils/sediments of this region and levels in the wetland likely reflect these background levels than enrichment from anthropogenic activity. Although 60% of all metals levels in the wetland samples exceeded USEPA threshold effect concentrations, results of recent studies that analyzed fish and vegetables from the wetland showed a small health risk associated with consumption. The XRF was a good tool for environmental analysis in a developing country.     

大气颗粒物及其组成研究进展(上)

颗粒物是空气中最重要的污染物之一,由于颗粒物表面的吸附作用,其组分非常复杂,其中含有多种有毒有害的化学成分,对大气环境造成不良影响,并危及人体健康。借助大气颗粒物及其组成成分的测定,通过污染源解析分析其来源及影响因素,控制大气颗粒物的排放,对于保证大气环境质量、改善人们的生存环境具有重大意义。本文对此进行综述。着重介绍大气颗粒物及其组成成分、源解析及测量技术的最新进展。     

市区交通干道路面沉积物理化特性分析

通过对某市区主要交通干道路面沉积物理化特性的监测分析,得出研究区域路面沉积物的基本物理化学性质,包括街道灰尘的pH、有机质和其粒径分布特征.同时,还分析了不同季节路面沉积物理化特性.