Determination of Real COD in Highly Chlorinated Wastewaters     

Arslan Saral  Bülent Ilhan Goncaloğlu 《洁净——土壤、空气、水》2008,36(12):996-1000

In order to determine the interference caused by chloride ions in Chemical Oxygen Demand (COD) measurements, synthetically prepared samples with various COD and chloride concentrations were analyzed. In addition, statistical analyses of the results were performed to calculate the real COD caused by the presence of organic substances in chlorinated wastewaters. The results of regression analyses showed good correlation between chloride concentrations and COD levels. A mathematical model is proposed on the basis of the statistical analyses. To calculate the real COD value of a wastewater sample, firstly, the chloride and interfered (or apparent) COD concentrations should be measured and then interference due to the chloride is calculated using the model equation proposed in this study. The real COD value was found by subtracting the COD due to chloride from the apparent COD. The reliability of the proposed model was also validated on real domestic wastewater samples, which were mixed with real seawater in various volumetric ratios to generate a range of salinity concentrations. These real saline samples gave good estimates of real COD with the results indicating that the proposed model can be used with acceptable confidence.  相似文献   

A stable isotope study of the Garda lake, northern Italy: Its hydrological balance   总被引：1，自引：0，他引：1  

A. Longinelli  B. Stenni  L. Genoni  O. Flora  C. Defrancesco  G. Pellegrini 《Journal of Hydrology》2008,360(1-4):103-116

Discontinuous measurements of the isotopic composition of surface water samples of the Garda lake carried out between 1998 and 2006 showed almost constant δ¹⁸O, δD and d-excess values through time. During 2006 and 2007 monthly vertical profiles of water samples were collected in the northernmost section of the lake, not far from the main inflow (Sarca river) to check whether there was any detectable influence from this inflowing river and whether there was a vertical isotopic stratification of the lake water. The isotopic measurement of water samples from the vertical profiles yielded isotopic values which were almost equal to those obtained from surface waters showing no detectable effect of the inflowing river water and no isotopic vertical stratification. The attempt to evaluate the evaporation rate of lake water by means of current models was totally unsuccessful. Despite the marked summer warming of the surface layer no isotopic fractionation related to evaporation processes could be detected. This anomalous behaviour may be related to the large amount of spring and summer precipitation characteristic of this area. The water balance of the lake calculated according to the amount of the inflowing water (Sarca river water plus rain water on the lake plus 20% of the precipitations on the whole catchment basin) and to the amount of outflowing water (Mincio river) showed a large imbalance, the river outflow alone resulting on average, during the last decade, at least double the inflow. To explain this imbalance of the lake, a large recharge by concealed groundwater is suggested: its isotopic composition should be quite close to the mean isotopic composition of precipitations over that area. This would be in agreement with the almost constant isotopic composition of both surface and deep waters and with the lack of vertical isotopic stratification. A few measurements of the tritium concentration carried out on lake water show values that are considerably higher than modern tritium values either in precipitation or in the Sarca river water: these results are in good agreement with the hypothesis of a recharge of the lake by deep aquifers.  相似文献   

Melting and differentiation of early-formed asteroids: The perspective from high precision oxygen isotope studies     

《Chemie der Erde / Geochemistry》2017,77(1):1-43

A number of distinct methodologies are available for determining the oxygen isotope composition of minerals and rocks, these include laser-assisted fluorination, secondary ion mass spectrometry (SIMS) and UV laser ablation. In this review we focus on laser-assisted fluorination, which currently achieves the highest levels of precision available for oxygen isotope analysis. In particular, we examine how results using this method have furthered our understanding of early-formed differentiated meteorites. Due to its rapid reaction times and low blank levels, laser-assisted fluorination has now largely superseded the conventional externally-heated Ni “bomb” technique for bulk analysis. Unlike UV laser ablation and SIMS analysis, laser-assisted fluorination is not capable of focused spot analysis. While laser fluorination is now a mature technology, further analytical improvements are possible via refinements to the construction of sample chambers, clean-up lines and the use of ultra-high resolution mass spectrometers.High-precision oxygen isotope analysis has proved to be a particularly powerful technique for investigating the formation and evolution of early-formed differentiated asteroids and has provided unique insights into the interrelationships between various groups of achondrites. A clear example of this is seen in samples that lie close to the terrestrial fractionation line (TFL). Based on the data from conventional oxygen isotope analysis, it was suggested that the main-group pallasites, the howardite eucrite diogenite suite (HEDs) and mesosiderites could all be derived from a single common parent body. However, high precision analysis demonstrates that main-group pallasites have a Δ¹⁷O composition that is fully resolvable from that of the HEDs and mesosiderites, indicating the involvement of at least two parent bodies. The range of Δ¹⁷O values exhibited by an achondrite group provides a useful means of assessing the extent to which their parent body underwent melting and isotopic homogenization. Oxygen isotope analysis can also highlight relationships between ungrouped achondrites and the more well-populated groups. A clear example of this is the proposed link between the evolved GRA 06128/9 meteorites and the brachinites.The evidence from oxygen isotopes, in conjunction with that from other techniques, indicates that we have samples from approximately 110 asteroidal parent bodies (∼60 irons, ∼35 achondrites and stony-iron, and ∼15 chondrites) in our global meteorite collection. However, compared to the likely size of the original protoplanetary asteroid population, this is an extremely low value. In addition, almost all of the differentiated samples (achondrites, stony-iron and irons) are derived from parent bodies that were highly disrupted early in their evolution.High-precision oxygen isotope analysis of achondrites provides some important insights into the origin of mass-independent variation in the early Solar System. In particular, the evidence from various primitive achondrite groups indicates that both the slope 1 (Y&R) and CCAM lines are of primordial significance. Δ¹⁷O differences between water ice and silicate-rich solids were probably the initial source of the slope 1 anomaly. These phases most likely acquired their isotopic composition as a result of UV photo-dissociation of CO that took place either in the early solar nebula or precursor giant molecular cloud. Such small-scale isotopic heterogeneities were propagated into larger-sized bodies, such as asteroids and planets, as a result of early Solar System processes, including dehydration, aqueous alteration, melting and collisional interactions.There is increasing evidence that chondritic parent bodies accreted relatively late compared to achondritic asteroids. This may account for the fact that apart from a few notable exceptions’ such as the aubrite-enstatite chondrite association, known chondrite groups could not have been the parents to the main achondrite groups.  相似文献   

不同温度和盐度对大竹蛏耗氧率和排氨率的影响     

聂鸿涛  姜力文  王海伦  邢宁宁  杨凤  闫喜武 《海洋科学》2017,41(4):44-50

在实验室条件下,设置12、17、22、27和32℃五个温度梯度和12、17、22、27和32五个盐度梯度,研究了不同温度和盐度对大竹蛏(Solen grandis)耗氧排氨的影响。结果表明:随着温度的升高耗氧率先降低再逐渐升高,在温度为22℃时为最小值1.571 mg/(g·h);排氨率先降低后升高再降低,在温度17℃时为最小值0.127 mg/(g·h)。随着盐度增加耗氧率先升高后降低,在盐度22时达到最大值3.106 mg/(g·h),排氨率先降低再升高,在盐度为27时为最小值为0.145 mg/(g·h)。在盐度32时,不同温度的O:N范围是5.525~79.037。在温度12℃时,不同盐度下的O:N范围是4.378~16.755。不同温度下耗氧率Q_(10)变化范围为1.054~2.421,排氨率的Q_(10)变化范围是0.748~1.256。研究结果为进一步完善大竹蛏的人工养殖技术提供参考。  相似文献   

中国西部典型铜镍矿床亲铜元素特征对比     

王建中  钱壮志  董富权  赵玉梅 《地球科学与环境学报》2010,32(2):137-143

通过对喀拉通克、黄山东、金川和白马寨4个铜镍矿床亲铜元素特征进行比较,结果发现所有矿床具有相似的左倾原始地幔标准化配分模式和铂族元素明显亏损的共同特点;其亲铜元素质量分数却明显不同,铂族元素质量分数最高的金川铜镍矿床以Ni为主,喀拉通克矿床则表现为Cu占优势;矿床的初始岩浆为铂族元素不亏损的玄武质岩浆,应是地幔岩石较高程度部分熔融的产物;少量硫化物预先熔离是造成中国铜镍矿床成矿母岩浆亏损铂族元素和w(Cu)/w(Pd)远大于原始地幔(w(Cu)/w(Pd))的控制因素;不同程度(量)的硫化物熔离导致母岩浆中亲铜元素质量分数不同,R值低不是主要原因;早期发生硫饱和可能是铜镍矿床成矿的必要条件,成矿的关键可能在于新鲜岩浆的不断补给;少量硫化物预先熔离结合不含矿岩石亏损铂族元素,暗示这些矿区深部具有找矿潜力。  相似文献   

Ecological footprint and major driving forces in West Jilin Province,Northeast China   总被引：6，自引：0，他引：6  

Mingquan Wang  Jingshuang Liu  Jinda Wang  Guangying Zhao 《中国地理科学(英文版)》2010,20(5):434-441

The environmental impact caused by local people (ecological footprint of consumption, EFc) and the actual environmental impact that the ecosystem burdens (ecological footprint of production, EFp) in West Jilin Province, Northeast China from 1986 to 2006 were evaluated by using ecological footprint (EF) method. And the major driving forces of EFc and EFp were analyzed by STIRPAT model. Both EFc and EFp showed increasing trends in 1986-2006, accompanied by decreasing ecological deficits but expanding ecologic...  相似文献   

Oxygen consumption rates of fecal pellets produced by three coastal copepod species fed with a diatom Thalassiosira pseudonana     

Loklun Shek 《Marine pollution bulletin》2010,60(7):1005-116

Fecal pellet production rate and oxygen consumption rate of copepod fecal pellets egested by Paracalanus sp., Acartia spinicauda and Centropages orsinii feeding on a diatom Thalassiosira pseudonana were measured. Fecal pellet production rates varied between 3.6 and 80.6 pellets ind⁻¹ d⁻¹ among three species, with fecal pellet production of Paracalanus sp. significantly higher than the other two copepod species. Average pellet size varied between 2.82 × 10⁵ μm³ for Paracalanus sp. and 5.36 × 10⁵ μm³ for A. spinicauda. Average volumetric oxygen consumption rates were 27.32, 5.84 and 45 fmol O₂ μm⁻³ d⁻¹ for fecal pellets produced by Paracalanus sp., A. spinicauda and C. orsinii, respectively. The potential oxygen consumption of fecal pellets egested from Paracalanus sp. was the highest due to its high fecal pellet production rate and high population abundance throughout the year. Overall, the approximate in situ oxygen consumption due to copepod fecal pellet degradation was significant in estuarine and coastal waters of Hong Kong. Results of this study give insight of the role of zooplankton in potential occurrence of hypoxia in coastal waters during summer.  相似文献   

中全新世河南南阳石笋记录的百年季风干旱事件   总被引：3，自引：1，他引：2  

任晓辉  董进国  陈昌海 《中国岩溶》2006,25(4):269-273

基于河南南阳洞1支石笋的5个230 Th 年龄和186个氧碳同位素数据,建立了中全新世持续1 570a( 6 115～ 4 544a B. P. )较高分辨率东亚季风降水序列。在整个研究时段,石笋氧碳同位素曲线记录了3次弱季风事件,分别发生在5 830～5 720a B. P. 、5 350～ 5 080a B. P.、4 770～ 4 640a B. P. ,其中5 350～ 5 080a B. P.时段持续干旱,历时270a。在测年误差范围内,平均分辨率达4～ 5 a 的氧同位素曲线与相应时段树轮14 C残差曲线基本对应。功率谱分析表明: 南阳洞石笋具有显著的130a 周期旋回,与树轮Δ14 C( 132a )以及低纬地区其它石笋记录的周期变化基本一致,说明中全新世东亚季风降水在百年尺度上可能主要受太阳辐射驱动。   相似文献   

近800年来内蒙古岱海地区古气温的定量重建   总被引：13，自引：5，他引：8  

曹建廷  金章东  沈吉  王苏民 《地理科学》2003,23(3):298-303

根据对现代湖水、现生介形类壳体以及湖泊沉积岩芯中同一种属介形类壳体的Sr/Ca分析,利用现代湖水Sr/Ca与湖水盐度的关系,确定了不同沉积时期湖水盐度;其次,在室内模拟实验,建立了湖水盐度与湖水氧同位素的函数关系;结合²¹⁰Pb测定沉积速率和¹⁴C测年资料,利用沉积剖面的自生碳酸盐氧同位素及由湖水盐度推算的湖水氧同位素组成,定量恢复了不同时期的湖水温度,进而根据碳酸盐结晶时水温与年均气温关系推测了古气温。结果表明:在近800年内蒙古岱海地区的气温变化序列中,中世纪暖期、现代小冰期以及近百年增温均有明显表现。研究时段内,岱海地区中世纪暖期比当代30年的年均气温高1℃以上;在公元1240年左右突然降温过程表现特别突出,在其后约60年的时段内气温下降1.8℃;小冰期最大降温幅度2℃以上,大于华北其它地区。不同于我国西部古里雅冰芯的记录,岱海地区近百年增温程度仍没有达到中世纪暖期水平,预示气候变暖对我国西部地区的影响将大于东部。  相似文献   

Formation of the salinity minimum in the Mixed Water Region between the Oyashio and Kuroshio Fronts     

Tokihiro Kono   《Deep Sea Research Part I: Oceanographic Research Papers》1998,45(12):2035-2057

The salinity minimum frequently occurring in the Mixed Water Region between the Oyashio and Kuroshio Fronts seems to originate from the salinity minimum at the density of 26.8σ_θ called the North Pacific Intermediate Water. We examined water exchange of this region with the Oyashio and the Kuroshio Extension using mixing ratio R_K defined as (θ - θ_OY)/(θ_K - θ_OY) × 100, where θ_OY, θ_K, and θ represent potential temperature of the Oyashio and Kuroshio Waters and their mixture on the isopycnal surfaces, respectively. CTD data were obtained by repeated observation from January 1990 to May 1991. R_K increases southward from the Oyashio Front to the Kuroshio Front with the range of −20 to 120%. The gradient of R_K on the isopycnal surfaces is large around the Oyashio Front above the 26.8σ_θ surface, while it is large around the Kuroshio Front below it. This agrees with the average R_K in the Mixed Water Region decreasing greatly with the increase of density at densities less dense than 26.8σ_θ. We calculated thickness and volume transport of the Oyashio between the isopycnal surfaces near the coast of Hokkaido. They increase largely with density at densities less dense than 26.8σ_θ. It is supposed that the salinity minimum in the Mixed Water Region is the upper limit of the water largely influenced by the Oyashio Water. Its density could depend only on the density structure of the Oyashio.  相似文献