The source of hydrogen sulfide in anoxic sediment

Putrefactive hydrogen sulfide production in the upper 4 cm of sediment in two small freshwater and eutrophic Southeast Michigan, U.S.A., lakes ranged from 0.13 to 1.51 with an average of 0.46 mg S l^?1 day^?1. Sulfate reductive production of hydrogen sulfide at the same sites ranged from 0.7 to 3.2 with an average of 1.54 mg S l^?1 day^?1. Putrefactive hydrogen sulfide production represented 5.1–53% (average of 18.3–27.6%) of the total hydrogen sulfide produced at the two lakes over an April–October study period. ³⁵S labeled substrates were used to estimate hydrogen sulfide production rates.Proteolytic bacteria averaged 2.2 × 10⁴ cells ml^?1 sediment whereas sulfate reducers averaged 4.8 × 10² cells ml^?1 sediment. Putrefactive hydrogen sulfide production correlated highly with numbers of proteolytic bacteria (r² = 0.84) but the correlation between sulfate reduction and sulfate reducing bacteria was low (r² = 0.13).Interstitial soluble inorganic sulfate, protein and organic carbon were not closely correlated with hydrogen sulfide production rates or bacteria enumeration results. Natural substrate concentrations (S_n) used to estimate hydrogen sulfide production were supported by kinetic bioassay results.     

硫化氢对遇水膨胀橡胶性能的影响

研究了不同浓度的H2S气体及其溶液对遇水膨胀橡胶(WSR)质量变化、力学性能和体积膨胀倍率的影响。结果表明,在不同浓度的H2S气体和H2S溶液中,WSR的拉伸强度、扯断伸长率和体积膨胀倍率均有较大程度降低,腐蚀时间越长、浓度越大,降低程度越大,但腐蚀时间达到20 d时,不同浓度的H2S气体或H2S溶液对WSR性能的影响差异明显减小。此外,在H2S气体中,WSR的质量逐渐增大,而在H2S溶液中,WSR的质量逐渐减小,但其质量损失率呈现先增加后减小的变化趋势。     

Evaluation of chemicals to control the generation of malodorous hydrogen sulfide in waste water

The effect of hydrogen peroxide, sodium/calcium hypochlorite and ferrous/ferric salts on hydrogen sulfide dissolved in waste water were investigated to establish an effective odour control system for Kuwait Sewage Networks. The waste water samples were collected from the inlet structure of main pumping station with pressure pipelines and analyzed for dissolved sulfide and pH before and after addition of chemicals individually and in combination under controlled laboratory conditions. The waste water contained dissolved sulfide in the range of 18 to 25 mg/l and pH ranged between 7.2 and 7.8. Various concentrations of above mentioned chemicals were tried to determine the accurate chemical requirement for oxidation or precipitation of dissolved sulfide in waste water. The reaction temperature was maintained at 35°C (±2°C), the normal temperature of waste water in Kuwait during summer. To oxidize 1 g of sulfide 1.25, 2.0 and 1.8 g hydrogen peroxide, sodium hypochlorite and calcium hypochlorite were required respectively. To remove 1 g of sulfide by precipitation with ferrous sulfate and ferric salt solution, 8 g and 4 g ferrous and ferric salt were required respectively under laboratory investigations. A combination of sodium hydroxide and sodium hypochlorite was also studied to control malodorous hydrogen sulfide in waste water. The addition of sodium hydroxide with sodium hypochlorite in waste water reduced the demand of hypochlorite 50%. This procedure was found to be cost effective and best suited for the warm climate of Kuwait and was implemented in the field at a screw conveyor type lifting station with gravity sewer pipelines. When sodium hypochlorite was injected without shock loadings of sodium hydroxide 46% reduction of dissolved sulfides was recorded and it was increased to 57% with shock loadings of sodium hydroxide, though the quantity of sodium hypochlorite was reduced to half than the former case. Similarly, 45 and 70% reduction in the emission of gaseous hydrogen sulfide was recorded with NaOCl injection without and with NaOH shock loading respectively. The cost comparison of all the chemicals when applied in field is also presented.     

河南平原第四系地下水氢氧同位素特征与补给分析

河南平原第四系地下水氢氧同位素分布特征,总体上由北向南呈渐高趋势,浅、深层地下水系统水的δ18O值变化规律基本一致。平原北部系统水的δ18O值最低,并随着距离黄河越来越近而变得愈来愈小,呈现出"∨"型变化的特征。平原南部系统水的δ18O值最高,并随着距离淮河越来越近而变得愈来愈大,呈现出"∧"的变化特征。平原中部系统水的δ18O值介于该二者之间,且变化较平缓。浅层系统水主要为大气降水补给。深层系统水受开采作用,使得浅层水的越流补给已成为主要的补给来源。此外,平原北部浅层系统水,黄河侧渗补给亦是沿岸地下水的重要补给来源;而平原南部浅层系统水在接受降水补给的同时,还受到淮河的排泄。     

Diagenetic remobilization of manganese, iron, copper and lead in anoxic sediment of a freshwater pond

The diagenetic remobilization of manganese, iron, copper and lead in anoxic sediment of a freshwater pond, T Reservoir, Japan has been examined in an in situ submerged chamber system, through the interstitial water and sediment analyses. Manganese was released continuously from the sediment into the overlying water during the experiment, whereas iron was released from the sediment abruptly after the 2nd day of the experiment. The steep vertical concentration gradients of manganese and iron were observed in the interstitial water. The release of manganese and iron from the sediment is due to the dissolution of ferro-manganese oxides and hydroxides in the surface sediment under anoxic condition. In contrast to manganese and iron, copper and lead were not released from the sediment during the experiment, and their concentrations in the interstitial water were not significantly different from the values of the overlying water. The results show that the diagenetic remobilization of copper and lead in the sediment is negligibly small. It is likely that copper and lead are fixed into the sediment by some process other than the formation of sulfides.     

高压输电线铁塔基础混凝土开裂检测及分析

本文对漯淮线高压输电线铁塔混凝土开裂基础进行了全面的检测 ,并从施工、材料、环境、荷载几方面分析了裂缝产生的原因 ,提出了开裂基础的修补和加固方案     

城市污水处理升级改造中化学除磷原理及费用

就城市污水处理升级改造中化学除磷原理及费用进行了分析和介绍，指出化学药剂与污水中的磷通过化学反应形成不溶性磷酸盐以沉淀、过滤等方式得以去除。污水中磷浓度越高，化学药剂的利用率也越高，反之亦然；出水磷浓度要求越低，则去除单位磷的化学药剂量越大。     

Rainfall intensity and phosphorus source effects on phosphorus transport in surface runoff from soil trays

Phosphorus runoff from agricultural fields amended with mineral fertilizers and manures has been linked to freshwater eutrophication. A rainfall simulation study was conducted to evaluate the effects of different rainfall intensities and P sources differing in water soluble P (WSP) concentration on P transport in runoff from soil trays packed with a Berks loam and grassed with annual ryegrass (Lolium multiflorum Lam.). Triple superphosphate (TSP; 79% WSP), low-grade super single phosphate (LGSSP; 50% WSP), North Carolina rock phosphate (NCRP; 0.5% WSP) and swine manure (SM; 70% WSP), were broadcast (100 kg total P ha-1) and rainfall applied at 25, 50 and 75 mm h-1 1, 7, 21, and 56 days after P source application. The concentration of dissolved reactive (DRP), particulate (PP), and total P (TP) was significantly (P<0.01) greater in runoff with a rainfall intensity of 75 than 25 mm h-1 for all P sources. Further, runoff DRP increased as P source WSP increased, with runoff from a 50 mm h-1 rain 1 day after source application having a DRP concentration of 0.25 mg L-1 for NCRP and 28.21 mg L-1 for TSP. In contrast, the proportion of runoff TP as PP was greater with low (39% PP for NCRP) than high WSP sources (4% PP for TSP) averaged for all rainfall intensities. The increased PP transport is attributed to the detachment and transport of undissolved P source particles during runoff. These results show that P source water solubility and rainfall intensity can influence P transport in runoff, which is important in evaluating the long-term risks of P source application on P transport in surface runoff.     

出厂水电导率与溶解性总固体的相关性分析

溶解性总固体的测定较为复杂且平行性和稳定性差,而电导率的测定简便,迅速,重现性和稳定性好,若二者相关关系显著,可通过测定电导率来推算水中溶解性总固体的含量。天津市开发区出厂水溶解性总固体与电导率的相关性分析结果表明,经检验二者线性关系显著,其比值为0.6。     

A study of the cycling of manganese and other elements in a seasonally anoxic lake, Rostherne Mere, U.K.

The vertical distribution of sulphate, dissolved sulphide, alkalinity, pH, total iron and manganese, Fe(II) and Mn(II) and humic substances was monitored for a year in a seasonally anoxic lake, Rostherne Mere, U.K. During summer stratification Mn(II), probably of sediment origin, accumulated in the hypolimnetic bottom waters to a concentration of 50μm. Release occurred in two stages and appeared to be related to the supply of organic material to the sediment. No ferrous iron or dissolved sulphide were detected in the water column, although they were measured in the interstitial waters of the sediment. Ferrous sulphide formation in the sediment controls the iron(II) and dissolved sulphide concentrations and so minimises the concentration gradients at the sediment-water interface. Electron acceptors other than oxygen are capable of oxidising ferrous and sulphide ions in the water column. pH and alkalinity were the only other chemical components to show appreciable variation with depth, reflecting the biological processes of photosynthesis, respiration and decomposition. Iron and humic substances simultaneously increased in the surface waters after a major flood indicating that they are both present in the solution in contact with the soils of the catchment.     

DZL型锅炉水冷壁管破裂事故分析与对策

结合一台蒸汽锅炉水冷壁管爆管事故的发生及应用理论，分析了发生事故的原因，并提出相应措施，经运行证明，工况良好，取得了一定的效果。     

鞍山市区民用水表精度调查与分析

运用数理统计的方法,以90％的置信度确定随机抽样样本,以离线水表检验代替在线水表示值相对误差,调查了鞍山市区在装水表的精度和结构。运用相关分析法分析了影响水表精度的主要因素及三个流量点误差的关系,建立回归方程预测了鞍山市区水表精度并进行了经济分析。     

Assessment of the water quality and identification of pollution sources of Kaduna River in Niger State (Nigeria) using exploratory data analysis

Exploratory data analysis such as hierarchical cluster analysis and principal component analysis were applied to water quality dataset of the Kaduna River, obtained during 3 years (2008–2010), monthly monitoring of eight key different sampling sites for 19 parameters to extract correlations and similarities between variables and to classify river sampling sites in groups of similar quality. Hierarchical cluster analysis grouped eight sampling sites into three statistically significant clusters of similar water composition. Six varifactors were obtained after varimax rotation of initial principal components using principal component analysis. These techniques gave an insight into the sources of pollution. Anthropogenic influence (municipal, industrial wastewater and agricultural run‐off) was the major source of river water pollution.     

金川铜镍矿床I矿区地质体三维建模与矿化空间分析

文章利用三维建模技术对金川铜镍矿床I矿区进行建模,在此基础上分析了矿体的矿化结构。根据钻孔柱状图和各时期地质勘探报告中相关数据建立了地质数据库,利用ArcGIS,GOCAD,Datamine 软件建立了金川铜镍矿床I矿区矿体的三维实体模型、矿体块体模型、地层模型和断层模型;运用地质统计学原理,在Surpac中对Cu、Ni品位空间变化结构进行了分析,得到空间变异椭球体模型,实现了金川I矿区Cu、Ni品位变化形态的空间分布展示;得出矿化空间分布规律。     

Applying global sensitivity analysis to the modelling of flow and water quality in sewers

While several approaches for global sensitivity analysis (GSA) have been proposed in literature, only few applications exist in urban drainage modelling. This contribution discusses two GSA methods applied to a sewer flow and sewer water quality model: Standardised Regression Coefficients (SRCs) using Monte-Carlo simulation as well as the Morris Screening method. For selected model variables we evaluate how the sensitivities are influenced by the choice of the rainfall event. The aims are to i) compare both methods concerning the similarity of results and their applicability, ii) discuss the implications for factor fixing (identifying non-influential parameters) and factor prioritisation (identifying important parameters) and iii) rank the important parameters for the investigated model. It was shown that both methods lead to similar results for the hydraulic model. Parameter interactions and non-linearity were identified for the water quality model and the parameter ranking differs between the methods. For the investigated model the results allow a sound choice of output variables and rainfall events in view of detailed uncertainty analysis or model calibration. We advocate the simultaneous use of both methods for a first model assessment as they allow answering both factor fixing and factor prioritisation at low computational cost.     

核电站不锈钢衬里力学分析及焊接变形控制

采用ANSYS有限元程序建模进行力学分析,计算出不锈钢覆面在水压力作用下的变形值及应力值,同时采用现场相似模拟实验,模拟了不锈钢覆面的真实受力情况,并结合工程实践,给出了有效控制水池池底墙角处不锈钢弯折件焊接变形的方法和措施,为后续类似工程提供了良好的借鉴。     

青海托拉海冲洪积扇区水文地质及水质分析

研究区位于沙松乌拉山前托拉海冲洪积扇区,区内沉积了厚度较大的第四系松散沉积物,其岩性主要为卵砾石、砂砾石及砂层。含水层厚度大于50 m,为赋存地下水提供了良好的空间场所。该区因降水稀少,蒸发量大,松散岩类孔隙水主要接受托拉海河水的下渗补给,主要河水补给来源于托拉海东沟、西沟,其中托拉海西沟年平均流量较小。洪积扇中前部地区地下水位埋深一般为20~65 m,水量较丰富,水质较好。     

空调大温差研究（4）：空调冷水大温差系统经济分析

对空调冷水大温差系统的经济性进行了分析。结果表明：当冷水机组冷水初温等于或大于7℃时,10℃温差与5℃温差时冷水机组的能耗基本相同,而发器压降明显减小;冷水系统采用10℃温差较℃温差冷水量减少一半,水泵能减少,水系统一次投资减少;即使空调机组一次投资略有增加,空调水系统的一次投资可减少5％左右。空调水系统运行 费用减少30％左右。建议在应用空调大温差技术的同时使用大温差专用空调机组。