Archive for the ‘Hot Articles’ Category

Nanoparticles on Fire!

schematic of nanoparticles in incineratorNanomaterials have become a ‘hot topic’ within many spheres of science, from their manufacture and use through to their toxicity.  However a critical review by Holder et al, has shed light on their disposal by incineration, an often overlooked area.

Incineration is a key route of disposal of many solid wastes, including from wastewater, which could be a significant source of silver nanoparticles.  Incineration is a complex process which could see nanomaterials released into the environment through several different pathways.

This very comprehensive article reviews social aspects of this topic, such as legislation from across the globe, as well physical scientific data on how nanomaterials behave under combustion conditions and their fate.

This article would be of interest to anyone keen to learn more about modern waste disposal, the manufacture of nanoparticles or the release and behaviour of antiparticles in the environment.

The review is free to access for the next 4 weeks, so pick it up while it’s hot!*

 *Free access to individuals is provided through an RSC Publishing personal account. It’s quick, easy and more importantly – free – to register!

Nanomaterial disposal by Incineration by Amara L. Holder, Eric P. Vejerano, Xinzhe Zhou and Linsey C. Marr. DOI: 10.1039/C3EM00224A

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HOT articles – free to access!

Take a look at our HOT articles recommended by our referees – these have been made free to access for 4 weeks*

Nanomaterial disposal by incineration
Amara L. Holder, Eric P. Vejerano, Xinzhe Zhou and Linsey C. Marr
DOI: 10.1039/C3EM00224A

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Combining multivariate statistics and analysis of variance to redesign a water quality monitoring network
Nathalie Guigues, Michèle Desenfant and Emmanuel Hance  
DOI: 10.1039/C3EM00168G

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The oxidative toxicity of Ag and ZnO nanoparticles towards the aquatic plant Spirodela punctuta and the role of testing media parameters
Melusi Thwala, Ndeke Musee, Lucky Sikhwivhilu and Victor Wepener
DOI: 10.1039/C3EM00235G

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Lability, solubility and speciation of Cd, Pb and Zn in alluvial soils of the River Trent catchment UK
Maria Izquierdo, Andrew M. Tye and Simon R. Chenery
DOI: 10.1039/C3EM00370A   

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Human exposure to aluminium
Christopher Exley
DOI: 10.1039/C3EM00374D

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Human biomonitoring issues related to lead exposure
Evert Nieboer, Leonard J. S. Tsuji, Ian D. Martin and Eric N. Liberda
DOI: 10.1039/C3EM00270E   

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Real time identification of algal phyla

algae identificationAlgae are identified in variety of research fields and used as indicators of water quality.  Quantifying and identifying algae is often a laborious task and requires a high level of skill.  Although there are several automated techniques now available, commercial developments have been limited.  Several software techniques based on imaging have been previously presented, however they’re often limited to only a few algal types, so not applicable to field samples. 

This paper presents an innovative method which provides real time recognition of multiple algaes.  The software uses image segmentation, shape features i.e. contours, centroid spectrum calculations and pigmentation.  The set up uses relatively simple hardware and no sample processing or fixation.  Coltelli et al tested the method on both cultured strains and field samples with the method correctly identifing 96.6% of 24 different algal phyla from 3423 images.

This article would be of interest to anyone involved in algal identification, whether from lab based cultures or water samples from the field. 

Automatic and real time recognition of microalgae by means of pigment and shape
Primo Coltelli, Laura Barsanti, Evangelista, Anna Maria Frassanito, Vincenzo Passarelli and Paolo Gualtieri
DOI: 10.1039/C3EM00160A

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New fungal immunoassay

antibodiesFungal antigens, e.g. from damp homes, have been linked to a variety of illnesses and allergies.  Traditional techniques of identifying them, such as culture based-methods or microscopy, have several drawbacks including not being able to identify fungal fragments and limitations in species classification.  Currently available commercial monoclonal antibody-based ELISAs are avilable, however they have not been as successful in fungal identification as they have been in other common indoor allergens.   

This paper describes the development and validation of an enzyme sandwich ELISA designed to quantify A. versicolor antigens using polyclonal antibodies.  Samples from infected homes were collected and tested using the newly developed assay and the results were compared to the commercially available ELISA, colony forming units and fungi cultivations.

Proteins from A. versicolor spores and myecelia were extracted and subcutaneously injected into a rabbit.  The antibodies produced were then isolated and coated on to the plates to produce the immunoassays.   Positive and negative controls were run as well as the environmental samples. 

In brief the assay proved to be very sensitive (range = 0.12–4.5 ng mL-1) and precise with intra-assay coefficient of variation (CV) = 4% and inter-assay CV = 11%.  Cross reactivity with other moulds was observed, although at intensities significantly lower than A. versicolor.  The assay also appeared to be more successful in environmental analysis than the commercial assay, showing a positive result for 88% of dust and 89% of bulk samples, with the commercial AveX ELISA only indicating positive results for 27% and 24% respectively.  This may be partly attributed to all the A. versicolor samples cultured showing A. versicolor antigens, whereas only 12 contained identifiable AveX antigens.  A wide range of proteins were shown to be identifiable by the polycolonal A. versicolor antibodies, although not smaller proteins (20–6 KDa) from the myecelia.

This immunoassay has been demonstrated to be effective in environmental studies and could prove to be a significant technique for those identifying and quantifying fungal infestations.  

This HOT article would be of interest to anyone involved in fungal identification or the development of immunoassays.  You can access it from the website for free for the next couple of weeks*!

A new immunoassay to quantify antigens from the infoor mould Aspergillus versicolor
Eva Zahradnik, Sabine Kespohl, Ingrid Sander, Ursula Schies, Janett Khosravie-Hohn, Wolfgang Lorenz, Steffen Engelhart, Annette Kolk, Gerd Schneider, Thomas Brüning and Monika Raulf-Heimsoth  
DOI: 10.1039/C3EM30870G

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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Free to access HOT articles!

 
These articles are HOT as recommended by the referees. And we’ve made them free to access for 4 weeks*

 

Bacterial community of iron tubercles from a drinking water distribution system and its occurrence in stagnant tap water
Lu Chen, Rui-Bao Jia and Li Li  
DOI: 10.1039/C3EM00171G


DGT measurement in low flow conditions: diffusive boundary layer and lability considerations
Emmanuelle Uher, Marie-Hélène Tusseau-Vuillemin and Catherine Gourlay-France
DOI: 10.1039/C3EM00151B


 

Quantitative and qualitative sensing techniques for biogenic volatile organic compounds and their oxidation products
Saewung Kim, Alex Guenther and Eric Apel  
DOI: 10.1039/C3EM00040K


A new immunoassay to quantify fungal antigens from the indoor mould Aspergillus versicolor
Eva Zahradnik, Sabine Kespohl, Ingrid Sander, Ursula Schies, Janett Khosravie-Hohn, Wolfgang Lorenz, Steffen Engelhart, Annette Kolk, Gerd Schneider, Thomas Brüning and Monika Raulf-Heimsoth
DOI: 10.1039/C3EM30870G

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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Can nanotubes affect how polyaromatic hydrocarbons behave in soil?

Determining the fate of compounds once they’re released into the environment is a complex issue. However such study is vital in order to assess the persistence of a compound as well as its bioavailability.  

It is well-established that polyaromatic hydrocarbons (PAHs) bind to organic complexes through hydrophobic interactions and that this can occur within soils to matter such as humus and soot etc.  So how does the presence of multi-walled carbon nanotubes (MWNTs) impact this?  Particularly given they are organic particles with relatively high surface areas available for adsorption.  Given the increasing interest in MWNTs there is now an elevated risk of ‘traditional’ organic pollution being released into an environment where MWNTs are already present, co-released with them or for MWNTs to be released onto existing polluted soil.

Li et al. used batch equilibrium experiments to assess the relationship between soil types, MWNTs and PAHs.  The MWNTs used were 1-3 µm long, 11 nm diameter with relatively little bundling providing a high surface area.  The group assessed three soil types: sand, sandy loam and silt loam with 2 mg g-1 of MWNTs.  The compounds and concentrations of PAHs assessed were naphthalene 0.18–7.94 mg L-1, fluorine 0.16–1.62 mg L-1 and phenanthrene 0.1–0.91 mg L-1.  Sorption tests (HPLC-fluorescence) were carried out after 5 days, at which point the aqueous solution was removed and replaced with fresh and left for 24hrs under the same conditions to assess desorption.

The results confirmed that the sorption of these compounds increased with increasing organic content of the soil. However, the presence of MWNTs did not appear to influence this adsorption, even at these relatively high concentrations of MWNTs.  Desorption was minimal in all cases.

In addition, the group derived equations based on the ‘rule of mixtures’ capable of predicting the sorption coefficients of composite sorbents.  They found good correlations between predicted and experimental data using these equations despite limitations of the model, such as assuming no void spaces. 

This HOT article would be of interest to anyone carrying out batch equilibrium experiments, or is interested in the sorption of PAH and/or the fate of MWNTs.  You can access it from the website for free for the next 4 weeks*!

Polyaromatic hydrocarbons (PAHs) sorption behavior unaffected by the presence of multi-walled carbon nanotubes (MWNTs) in a natural soil system.
Shibin Li, Todd A. Anderson, Micah J. Green, Jonathan D. Maul and Jaclyn E. Cañas-Carrell
DOI: 10.1039/C3EM00099K

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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How can you assess the impact of multiple methane sources to the environment?

In this HOT article, collaborators in Australia and California devise methods of assessing contributions of landfill and natural gas methane to mixtures in soil gas and groundwater. They use half-lives and concentration ratios to evaluate the age of release.

The group at URS Australia Pty Ltd, Geosyntec Consultants and Redwood Waste Management California, focus on the problem of methane from landfill gas migrating away underneath the surface of landfill sites. It is a particular problem due to methane’s flammable nature. Landfill gas is not the only source of migrating methane. Sources include natural organic matter decomposition, natural gas in supply lines, degradation of petroleum products and underground reservoirs of natural gas. There are many indicators used to determine the source of natural gas, such as the presence of CO2 being a marker for biodegradation. Carbon and hydrogen isotope composition is also used.

These researchers argue that using multiples of these indicators is the most reliable way to understand sources and migration pathways. This paper introduces a methodology to assess all of these different indicators at a complex site with multiple methane sources. Knowing the age of landfill gas using VOCs concentrations is a helpful parameter when assessing migration distance and time. This methodology using methane radioisotope data can distinguish on-going release from an inactive source and determine relative contributions of landfill gas and thermogenic methane to the environment. The theoretical basis for estimating landfill gas age is described in detail and applied to a case study at a municipal solid waste disposal facility in California.

As always, we’ve made this fascinating HOT research free to access for 4 weeks*!

Evaluation of the age of landfill gas methane in landfill gas–natural gas mixtures using co-occurring constituents
Henry B. Kerfoot, Benjamin Hagedorn and Mark Verwiel 
DOI: 10.1039/C3EM30971A

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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HOT article! Hydrological and landscape factors affecting nutrient flux

J. Abell and colleagues at the University of Waikato and National Institute of Water and Atmospheric Research, New Zealand, have quantified nutrient and sediment inputs to a large eutrophic lake. They draw conclusions on how hydrological and landscape factors interact to produce pollutant flux.

Pollutant concentrations after a rain event such as a storm vary greatly and therefore high-frequency sampling is needed.  The amount of pollutant must be measured as a function of the stream discharge. The relationship between the two parameters can provide insights into sources and transport mechanisms in a catchment area. A catchment area can act as a filter, regulating downstream transport.  Therefore changes over time that occur after a rain event give insights into upstream hydrological and landscape factors.

The team looked at two streams flowing into a large eutrophic lake, focusing on levels of suspended sediment, nitrogen and phosphorus over a range of discharge values. One stream flowed through a mainly forested area, the other through pasture land. They conducted high frequency sampling over two years for both streams, taking over 900 samples. Comparison of two streams allowed spatial conclusions to be drawn.

This article includes an in-depth discussion of the factors related to suspended sediment and nutrient levels of the two streams, and how all of these factors contribute to the eutrophic nature of the lake. The researchers examine how these results could to lead to improved management of lake water quality.

Free to access for 4 weeks*, read the detailed discussion here:

Quantifying temporal and spatial variations in sediment, nitrogen and phosphorus transport in stream inflows to a large eutrophic lake
J. M. Abell, D. P. Hamilton and J. C. Rutherford
DOI: 10.1039/C3EM00083D

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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Issue 5 online! Bridging data gaps and sampling particulates, E-waste and radiocarbon analysis

A HOT article from a team at the US Naval Research Laboratory is featured on this month’s eye-catching outside front cover, which was recently featured on the ESPI blog. In this work, CO2 radiocarbon analysis is demonstrated as a tool to review remediation efficiency by differentiating between CO2 produced by degrading fuel contaminant and that produced naturally by organic matter. Free to access for 6 weeks*!

Radiocarbon-depleted CO2 evidence for fuel biodegradation at the Naval Air Station North Island (USA) fuel farm site
Thomas J. Boyd, Michael J. Pound, Daniel Lohr and Richard B. Coffin
DOI: 10.1039/C3EM00008G


 

Issue 5 contains two Perspective articles. The first written by Darrah Sleeth at University of Utah, USA, assesses the current air sampling techniques available for sampling beryllium particulates and outlines the components of the ideal aerosol sampler.

The impact of particle size selective sampling methods on occupational assessment of airborne beryllium particulates
Darrah K. Sleeth 
DOI: 10.1039/C3EM30877D


 

The second Perspective from Richard Brown et al. at the National Physical Laboratory, UK, follows on from their excellent HOT article featured on the front cover of Issue 3 in February. This Perspective article discusses the consequences of incomplete data coverage and evaluates strategies for making up for such data loss. The authors’ aim is to provoke debate about the best ways to address this problem, so have a read and let us know what you think by commenting below.

Improved strategies for calculating annual averages of ambient air pollutants in cases of incomplete data coverage
Richard J. C. Brown, Peter M. Harris and Maurice G. Cox
DOI: 10.1039/C3EM00039G


 

Issue 5 contains more HOT research, such as this article on E-waste which was highlighted on the blog last week:

Heavy metals and organic compounds contamination in soil from an e-waste region in South China
Ming Liu, Bo Huang, Xinhui Bi, Zhaofang Ren, Guoying Sheng and Jiamo Fu
DOI: 10.1039/C3EM00043E

Discover the full contents of Issue 5 here!

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 *Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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HOT article: The impact of e-waste recycling in China

The dumping of e-waste is an ever-increasing environmental problem. Individuals and organisations are changing their mobile phones and computers at faster and faster rates to keep up to date with the latest technological innovations. 80% of the world’s e-waste is exported to Asia, with the vast majority ending up in China where the environmental regulations are softer and the cost of labour is lower.

The recycling of e-waste in China often involves environmentally unfriendly processes. Now mostly banned from use, PCBs are still prevalent in the majority of older electronic equipment, which is now e-waste. PBDEs are also used as flame retardants in electronics. These chemicals and heavy metals are released into the environment during e-waste recycling

Researchers at the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, China, describe an extensive study into the soil contamination levels in an e-waste region of Southern China. They identify which recycling activities emit which pollutants and look at the links between contamination levels in recycling sites and in local agricultural soils.

They find that local paddy and vegetable field soils are contaminated with the same heavy metals found at the recycling sites and this contamination may have been distributed via ponds and streams. This work will inform the reform of e-waste recycling policies and the team plan to investigate the mobility and toxicity of the contaminants in detail.

This HOT article on the processes of an important modern environmental issue is now free to access for the next 4 weeks*!

Heavy metals and organic compounds contamination in soil from an e-waste region in South China
Ming Liu, Bo Huang, Xinhui Bi, Zhaofang Ren, Guoying Sheng and Jiamo Fu  
DOI: 10.1039/C3EM00043E

 *Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

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