Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: Sudan Black B versus Nile Blue A staining

Polyhydroxyalkanoates (PHA) can be produced and intracellularly accumulated as inclusions by mixed microbial cultures (MMC) for bioplastic production and in enhanced biological phosphorus removal (EBPR) systems. Classical methods for PHA quantification use a digestion step prior to chromatography analysis, rendering them labor intensive and time-consuming. The present work investigates the use of two quantitative image analysis (QIA) procedures specifically developed for PHA inclusions identification and quantification. MMC obtained from an EBPR system were visualized by bright-field and fluorescence microscopy for PHA inclusions detection, upon Sudan Black B (SBB) and Nile Blue A (NBA) staining, respectively. The captured color images were processed by QIA techniques and the image analysis data were further treated using multivariate statistical analysis. Partial least squares (PLS) regression coefficients of 0.90 and 0.86 were obtained between QIA parameters and PHA concentrations using SBB and NBA, respectively. It was found that both staining procedures might be seen as alternative methodologies to classical PHA determination.     

热喷雾进样火焰原子吸收光谱法测定河水中的铅

铅被广泛应用于蓄电池、建筑材料、电缆外套等工业生产中,是造成河水污染的主要原因。铅为生物体有害元素,当其被人体组织吸收后,分布予肝、肾、肺、脑中,损害骨髓造血系统和神经系统。在环境检测中铅是必须检测的元素之一。火焰原子吸收光谱法具有仪器简单、操作方便、抗干扰能力强、稳定性好等特点,但由于雾化效率低和灵敏度低,不能直接用于测定样品中的低含量铅。     

火焰原子吸收分光光度法测大沂河水体的重金属含量

采用火焰原子吸收分光光度法测定了山东省曲阜市大沂河水体的重金属铜、铅、镉、锌含量。结果表明,大沂河水体中铜、铅、镉、锌的最高含量分别为0.018,0.230,0.176,0.490mg/L,其中铅和镉的含量超过国家Ⅴ类水标准。     

Sources and Accumulation of Butyltin Compounds in Ganges River Dolphin,Platanista gangetica

Concentrations of butyltin compounds (mono-, di-, and tri-butyltin) were determined in dolphin ( Platanista gangetica ), fish, invertebrates and sediment collected from the River Ganges, India, in order to understand the contamination levels, sources, and potential for biomagnification in freshwater food chains. Total butyltin concentration in dolphin tissues was up to 2000 ng g⁻¹ wet wt, which was about 5–10 times higher than in their diet. The concentrations in fish and benthic invertebrates, including polychaetes, were 3–10 times greater than in sediment. The biomagnification factor for butyltins in river dolphin from its food was in the range 0.2–7.5. Butyltin concentrations in Ganges river organisms were higher than those reported for several persistent organochlorine compounds. Discharge of untreated domestic sewage was one of the major sources of butyltin residues in Ganges river biota. High concentrations of butyltin compounds in freshwater food chains suggest the need to assess their toxic effects in aquatic organisms and to regulate their use. © 1997 by John Wiley & Sons, Ltd.     

城市河道系统的景观敏感性与景观规划

运用景观生态学的原理,通过对城市河道系统的景观敏感性与视觉美学敏感性的分析,指出景观系统的敏感性是指不同时间和空间尺度上系统对干扰的反应.揭示了城市化的快速发展使土地利用方式发生大规模改变的同时,城市河道及其沿岸景观系统在结构、形态上也发生巨大变化,导致河流水文、生态系统的破坏与功能的退化,城市水文洪涝灾害频发、水质污染严重和美学质量下降等问题,提出用景观规划探讨城市河道系统的保护、修复与补偿系统及可持续发展途径.     

Preserving bounded and conservative solutions of transport in one‐dimensional shallow‐water flow with upwind numerical schemes: Application to fertigation and solute transport in rivers

This work intends to show that conservative upwind schemes based on a separate discretization of the scalar solute transport from the shallow‐water equations are unable to preserve uniform solute profiles in situations of one‐dimensional unsteady subcritical flow. However, the coupled discretization of the system is proved to lead to the correct solution in first‐order approximations. This work is also devoted to show that, when using a coupled discretization, a careful definition of the flux limiter function in second‐order TVD schemes is required in order to preserve uniform solute profiles. The work shows that, in cases of subcritical irregular flow, the coupled discretization is necessary but nevertheless not sufficient to ensure concentration distributions free from oscillations and a method to avoid these oscillations is proposed. Examples of steady and unsteady flows in test cases, river and irrigation are presented. Copyright © 2007 John Wiley & Sons, Ltd.     

Concentration Levels of Trace Elements in Carrots,Onions, and Potatoes Cultivated in Asopos Region,Central Greece

The objective of the work was to investigate the correlation between the environmental pollution of Asopos river area in Viotia, Greece and the concentration of Ni, Cr, Cd, Pb, Cu, and As in specific crops (carrots, onions, and potatoes) produced in this region. Samples of these crops from Asopos and other Greek areas (control) were collected. For method accuracy, the Certified Reference Material, CRM 281 (trace elements in rye grass) was measured. Simultaneous multi-element graphite furnace atomic absorption spectrometry was used after a microwave acid digestion. The levels of Ni in Asopos food were found up to 9 times higher than control (e.g., Asopos potatoes had an average Ni content of 800 µg/kg compared to 78 µg/kg in control, whereas Asopos carrots had an average Ni content of 474 µg/kg compared to 93 µg/kg in control). Likewise, the levels of Cr were found to be about 2 times higher than control (e.g., Asopos carrots were found to have an average Cr content of 43 µg/kg compared to 20 µg/kg in control). The levels of Cd and Pb had a high variance in the Asopos sourced food. Arsenic was not detected in any sample. Our results indicate that the mean intake of trace elements (Ni, Cr, Pb, Cd, and Cu) by adults through consumption of crops from Asopos, for an average consumption pattern, generally is well below the Allowable Daily Intakes (ADIs). Comparison was also made with data from literature from Greece.     

A Fluorescence-Based Sensor for Ammonium and Nitrate

Abstract

Measurement of nitrite and nitrate in rain samples was performed using a fluorescence based sensor. Nitrite and nitrate were reduced to ammonia using Devarda's alloy, and the gas was then passed through a membrane and reacted with o-phthalaldehyde. A linear relationship between the nitrate concentration and the luminescence intensity was observed over the concentration range of 1 – 5 mg/1, with a relative standard deviation (RSD) of 2.3% at a nitrate concentration of 1 mg/1 (n = 5). The system did not show any response toward sulfate or chloride. Results obtained from the measurement of river water samples using the sensor showed good agreement with those obtained using a conventional method.     

Evaluation of radiological hazards in the sediments of Ogun river, South-Western Nigeria

The concentrations of natural radionuclides in the sediments of Ogun river in South Western Nigeria have been measured and determined using gamma-ray spectrometry. The mean activity concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th at different locations along the course of the river were found to vary from 370.99±19.26 Bq/kg (at Olopade) to 608.02±24.66 Bq/kg (at Owere), 5.57±2.34 (at Ekerin) to 20.40±4.52 Bq/kg (at Sokori) and 5.04±2.24 Bq/kg (at mile 12-Maidan) to 23.10±4.81 Bq/kg (at Sokori) respectively. The overall calculated mean of the total indoor absorbed dose rates was 64.46±9.16 nGy/h with corresponding annual indoor effective dose of 0.32±0.05 mSv/y. Radium equivalent activity (Ra_eq), external hazard index (H_ex), internal hazard index (H_in) and representative gamma index (I_γr) were calculated in order to assess the radiation hazards associated with the use of these sediments in the construction of dwellings. The overall estimated values for the radium equivalent activity, external hazard index, internal hazard index and the representative gamma index were 67.96±10.74 Bq/kg, 0.18±0.03, 0.22±0.05 and 0.54±0.08, respectively. These values obtained for the river sediments were less than the recommended safe and criterion limits by UNSCEAR and also, they compared well with the values from other countries of normal radiation areas. It suffices to say therefore that sediments from Ogun river are safe and can be used for construction of buildings without undue radiological health concerns. Results of the study could serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.     

Confirmation Studies on Polychlorinated Biphenyls (PCB) From River Waters Using Mass Fragmentography

Abstract

A specific and sensitive method to confirm the presence of polychlorinated biphenyls (PCB) in river water is described. Mass fragmentography is shown to be a proper technique especially when utilizing naturally occurring stable isotopes of chlorine. Synthesized tetrachloro-, pentachloro-and hexachlo-ro biphenyls were used to focus the mass spectrometer at three selected masses so called multiple ion detection (MID).