Improved slant drilling well for in situ remediation of groundwater and soil at contaminated sites

Abstract

Soil contamination has become a crucial issue in urban redevelopment. Japan has many contaminated sites on which manufacturing has been conducted over several decades. Site holders are now under pressure to manage chemical contamination; however, the use of heavy machinery is difficult in remedial operations on restricted sites, especially where there are still working factories. The slant well is a potentially useful technique in such settings, but its use is technically challenging because of the need for high drilling accuracy and the difficulty in sealing the slanted bores. In this study, we investigated an improved technique for slant drilling that can be used around existing structures to treat contaminated soil and groundwater. A key to this novel approach was the use of water-swelling materials as sealants. Research at a test site investigated the accuracy of drilling. Tracer tests were also conducted using sodium chloride and urea. The improved slant borings showed a deviation of less than 2% from the target bore. The spread of the two tracers at different depths was demonstrated. The proposed technique provides a useful approach to the treatment of brownfield sites in countries where in situ remediation has not yet been undertaken.

http://ift.tt/2j4V1PN

Comparative toxicity of nano ZnO and bulk ZnO towards marine algae Tetraselmis suecica and Phaeodactylum tricornutum

Abstract

The wide use of ZnO nanoparticles in a number of products implies an increasing release into the marine environment, resulting in the need to evaluate the potential effects upon organisms, and particularly phytoplankton, being at the base of the throphic chain. To this aim, dose–response curves for the green alga Tetraselmis suecica and the diatom Phaeodactylum tricornutum derived from the exposure to nano ZnO (100 nm) were evaluated and compared with those obtained for bulk ZnO (200 nm) and ionic zinc. The toxic effects to both algae species were reported as no observable effect concentration (NOEC) of growth inhibition and as 1, 10, and 50% effect concentrations (EC1, EC10, and EC50). The toxicity decreased in the order nano ZnO > Zn²⁺ > bulk ZnO. EC50 values for nano ZnO were 3.91 [3.66–4.14] mg Zn/L towards the green microalgae and 1.09 [0.96–1.57] mg Zn/L towards the diatom, indicating a higher sensitivity of P. tricornutum. The observed diverse effects can be ascribed to the interaction occurring between different algae and ZnO particles. Due to algae motility, ZnO particles were intercepted in different phases of aggregation and sedimentation processes, while algae morphology and size can influence the level of entrapment by NP aggregates.

This underlines the need to take into account the peculiarity of the biological system in the assessment of NP toxicity.

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Evaluation of 2D resistivity imaging technique for delineating subsurface seepage of hydrocarbon-contaminated water southeast of Karbala city, Iraq

Abstract

2D imaging technique was applied in (8) transects near a pit of contaminated water near contaminated well southeast of Karbala city, Iraq. Each transect was 30 m long with 1 m electrode spacing. Data acquisition was fulfilled by using Wenner electrode array. The resistivity of water-contaminated zone is found less than 3Ω.m and the top dry zone recorded relatively high resistivity (more than 170Ω.m). It is found that the greatest amount of seepage was found moving towards northeast direction coincided with groundwater movement direction, whereas there was no movement towards northwest and southeast directions and restricted on the closest areas to the pit location. The outcomes suggested that the 2D imaging technique is a successful and powerful tool in separating contaminated zone from clear one and in detecting underground seepage depth and moving direction.

http://ift.tt/2j5feov

Determination of cytostatic drugs in Besòs River (NE Spain) and comparison with predicted environmental concentrations

Abstract

The number of cytostatic drugs used in cancer treatments is wide and increases every year; therefore, tools have been developed to predict their concentration in the environment to prioritize those for monitoring studies. In the present study, the predicted environmental concentrations (PECs) were calculated according to consumption data in Catalonia (NE Spain) for 2014. According to PECs and to the most widely reported compounds, 19 cytostatics were monitored in two sampling campaigns performed along the Besòs River. A total of seven drugs were detected at levels between 0.5 and 656 ng L⁻¹. PEC and measured environmental concentrations (MECs) were compared in order to validate PECs. The PEC/MEC ratio presented a good agreement between predicted and measured concentrations confirming the PEC estimations. Mycophenolic acid, prioritized as the compound with the highest PEC, was detected at the highest concentrations (8.5–656 ng L⁻¹) but showed no risk for aquatic organisms (risk quotient <1) considering acute toxicity tests performed in Daphnia magna.

http://ift.tt/2jhPnYc

Efficient photo–catalytic degradation of malachite green using nickel tungstate material as photo–catalyst

Abstract

The present study focused on the evaluation of photo-catalytic and photo–electrochemical properties of the photo–catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico–chemical, optical, electrical, electrochemical, and photo–electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform–infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott–shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m²/g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo–degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.

http://ift.tt/2j4U9uq

Assessment of metal contamination in the Hun River, China, and evaluation of the fish Zacco platypus and the snail Radix swinhoei as potential biomonitors

Abstract

The Hun River is a major tributary of the Liao River in the northeast area of China and provides drinking water for 23 million local residents. This study was designed to assess the severity of metal contamination in the Hun River and the potential use of indigenous organisms (the fish Zacco platypus and the snail Radix swinhoei) as biomonitors of metal contamination. Water, sediment, and the native fish and snails were collected at four sampling sites that differed in their physicochemical characteristics and their contamination levels. The samples were analyzed for Cd, Cr, Cu, Ni, Pb, and Zn by ICP-MS. The results showed that although the overall potential ecological risks of the metals were low at our sampling sites, Cd posed a noteworthy ecological risk. Strong correlations were obtained between Cd concentrations in the organisms and in the environment. The results indicated that Z. platypus and R. swinhoei can be useful biomonitoring species for assessing Cd contamination. Biomonitoring with the snail may be most effective when focused on the gonad/digestive tissue (because of the high metal accumulation there), but further work is needed to confirm this.

http://ift.tt/2jhTq6X

The current and future role of biomarkers in type 2 cytokine-mediated asthma management

Abstract

Assessment and management of asthma is complicated by the heterogeneous pathophysiological mechanisms that underlie its clinical presentation, which are not necessarily reflected in standardised management paradigms and which necessitate an individualised approach to treatment. This is particularly important with the emerging availability of a variety of targeted forms of therapy that may only be appropriate for use in particular patient subgroups. The identification of biomarkers can potentially aid diagnosis and inform prognosis, help guide treatment decisions, and allow clinicians to predict and monitor response to treatment. Biomarkers for asthma have been identified from a variety of sources, including airway, exhaled breath and blood. Biomarkers from exhaled breath include fractional exhaled nitric oxide, measurement of which can help identify patients most likely to benefit from inhaled corticosteroids and targeted anti-immunoglobulin E therapy. Biomarkers measured in blood are relatively non-invasive and technically more straightforward than those measured from exhaled breath or directly from the airway. The most well-established of these are the blood eosinophil count and serum periostin, both of which have demonstrated utility in identifying patients most likely to benefit from targeted anti-interleukin and anti-immunoglobulin E therapies, and in monitoring subsequent treatment response. For example, serum periostin appears to be a biomarker for responsiveness to inhaled corticosteroid therapy and may help identify patients as suitable candidates for anti-IL-13 treatment. The use of biomarkers can therefore potentially help avoid unnecessary morbidity from high-dose corticosteroid therapy and allow the most appropriate and cost-effective use of targeted therapies. Ongoing clinical trials are helping to further elucidate the role of established biomarkers in routine clinical practice, and a range of other circulating novel potential biomarkers are currently being investigated in the research setting.

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