Breaking the mould: assessing microbial pollution in the indoor environment

By Ian K.

a blog article by Ian Keyte, a Doctoral Researcher at the University of Birmingham

Understanding the levels and behaviour of mould and fungal particles in the indoor environment is essential in order to carry out more comprehensive exposure assessments and analysis of their associated health effects. Researchers at Korea University and the National Institute of Environmental Research in Seoul present a study, describing a valuable method to achieve this.

Microbial pollution (for example from bacteria and fungi) can present a serious public health risk. A particular concern has been raised regarding filamentous fungi (better known as mould). Indoor mould is primarily caused by excess moisture, for example due to leaking pipes, rising damp or rain seepage. The World Health Organisation warns that mould is a key element of indoor pollution, linked with triggering and exacerbating allergic symptoms and diseases such as asthma and other respiratory illnesses.

Children are particularly sensitive to allergen exposure and, because they spend considerable time indoors, they could be vulnerable to these serious health effects if the indoor environment is not well maintained. Elementary (primary) school children spend upwards of six hours a day in school, mostly in one classroom. This emphasises the importance of minimising the risk of developing or increasing allergic diseases due to pollutants in the school environment.  While there has been considerable interest in assessing the problem of mould in school classrooms, as yet few comprehensive assessments have been performed.

Mould in the indoor environment can be a major source of microbial pollution and associated health effects

Household mould - a cause of indoor microbial pollution (Source: http://www.yourlocalguardian.co.uk)

Traditionally, studies of microbial pollution from mould involve making spore counts by culturing from collected samples due to ease of sampling and analysis. However, this method does not allow adequate evaluation of the exposure to mould due to the different growth rates of different types of mould. Therefore, assessment of spore concentration is not adequate on its own to fully investigate fungal exposure to humans.

More recently, the measurement of (1,3)-β -D-glucan has been proposed as a new tool to determine microbial pollution. This compound exists in fungal cell walls and is more common in airborne spores, so it is proposed that analysis of (1,3)-β -D-glucan in small-scale fungal fragments could be applied for an exposure assessment of mould and associated health effects in the school environment. This research by SungChul Seo and co-workers presents the first study of its kind to apply this approach to a relatively large-scale assessment of actual classrooms.

In the study, the levels of small-size (submicron) fungal fragments as well as airborne moulds, bacteria, and particulate matter (PM10), were evaluated in both indoor and outdoor areas of 70 classrooms in 8 elementary schools and the variation in the concentrations before and after the rainy season (May and July) were investigated. The concentrations of (1,3)-β -D-glucan in submicron fungal fragments, airborne mould and bacteria, and PM10 were measured simultaneously and the association of these levels with physical factors (i.e. temperature and relative humidity) wasalso compared and analysed.

The results indicate that the indoor/outdoor ratios of (1,3)-β -D-glucan concentrations were greater than 1 in every school. It was also shown that in the sampling period after the rainy season, the (1,3)-β -D-glucan concentrations decreased by about 35%, and similar significant decreases in the concentrations of airborne mould, bacteria and PM10 were observed as well. A negative association between the concentration of submicron fungal fragments and relative humidity was also observed.

This study therefore provides valuable insights into the concentrations, behaviour and variability of microbial pollution associated with mould in the school environment. This clearly outlines some of the key practical considerations required to carry out assessments of fungal exposure and could pave the way for similar studies in different locations. The authors note that more comprehensive exposure assessments for smaller-sized fungal particles should be performed for better understanding of their health impact, particularly with regard to seasonal and temporal changes.


To access the full article, download a copy for free* by clicking the link below.

Submicron fungal fragments as another indoor biocontaminant in elementary schools
SungChul Seo, Yeong Gyu Ji, Young Yoo,  Myung Hee Kwon and Ji Tae Choung
Environ. Sci.: Processes Impacts, Advance Article, 2015
DOI: 10.1039/c4em00702f

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About the webwriter

Ian Keyte is a Doctoral Researcher at the University of Birmingham. His research focuses on the sources, behaviour and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere.

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* Access is free until 08/07/2015 through a registered RSC account.

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A robot that identifies toxic bacteria in shallow water

a blog article by Fernando Gomollón-Bel, PhD student at the University of Zaragoza

Anabaena are a group of cyanobacteria species that populate shallow water areas. They are a bit Janus-faced, both good and bad for the ecosystem at the same time. On the one hand, as many bacteria do, they fixate nitrogen. They are also rich in chlorophyll, thus being able to produce photosynthesis. On the other hand, they produce a handful of neurotoxins. These toxins are a huge risk for any other living creature around –even human beings, if they happen to drink contaminated water.

Hence, knowing the density and coverage area of cyanobacteria in a particular ecosystem may be interesting to assess ecological risk. However, when the water is not too deep, fieldwork becomes harder: divers cannot work well and boats can hardly approach the study zone. Moreover, Anabaena species often form filaments that attach to rocks, seagrass and algae. These filaments are very fragile, so the system can be easily perturbed if someone moves around to collect samples.

Image 1. The USV robot equipped with all sort of different sensors and a video camera.

But J. Gutiérrez and colleagues came up with a pretty elegant solution. They designed a missile-shaped robot that is able to sail the surface of shallow lakes and ponds, and measure the amount of Anabaena on the surface without perturbing the ecosystem. This unmanned surface vehicle (USV) features a GPS that tracks the position at all times, as well as a wide variety of chemical sensors that simultaneously record the concentration of different ions (nitrate, ammonium). It is able to measure conductivity and temperature, too. All of this while being operated from the lab using a radio-frequency remote control.

The USV also carries a camera, equipped with an image stabilization system that was improved by Gutiérrez’s team. The camera records video at all time. This video will be analysed frame by frame with the help of a state-of-the art computer programme that will be able to identify Anabaena filaments or colonies in every picture.

Combining these data with the different physicochemical measurements obtained with the sensors, researchers are able to quantify and locate toxic bacteria. The USV-robot allows them to obtain very promising results with a fraction of the usual cost of other on-water monitoring systems.


To access the full article, download a copy for free* by clicking the link below.

On-water remote monitoring robotic system for estimating the patch coverage of Anabaena sp. filaments in shallow water
E. Romero-Vivas, F. D. Von Borstel, C. J. Pérez-Estrada, D. Torres-Ariño, J. F. Villa- Medina and J. Gutiérrez.
Environmental Science: Procceses & Impacts, 2015, Advance Article.
DOI: 10.1039/c5em00097a

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About the webwriter

Fernando Gomollon-Bel is a PhD Student at the ISQCH (CSIC-University of Zaragoza). His research focuses on asymmetric organic synthesis using sugars as chiral-pool starting materials towards the production of fungical transglycosidase inhibitors.

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* Access is free until 05/07/2015 through a registered RSC account.

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2nd National Environmental Eco-Toxicology Conference

Held in Xiamen (China), April 2015

The 2nd National Environmental Eco-Toxicology Conference was held in Xiamen, China, 25th-28th of April, 2015.

This exciting conference was jointly organised by the Research Center for Eco-environmental Sciences of the Chinese Academy of Sciences (CAS), Xiamen University and the Institute of Urban Environment of CAS.

More than 700 attendees shared new ideas and recent development on the are six topics discussed during this conference:

  • Screening and assessment of high risk chemical contaminants
  • Transfer and distribution of chemical contaminants in the environment and organisms
  • Chemical hazards evaluation
  • Toxicology mechanism of chemical ecology
  • Toxicological mechanism of chemical health effects
  • Chemical risk management


During the conference, the Environmental Science (ES) series of journals sponsored three poster prizes. Let’s introduce the winners!

ES: Processes & Impacts: ‘Study on the toxicity behavior of organic phosphate ester flame retardant to pattern fish’, by Liwei Sun (Zhejiang Institute of Technology)

ES: Water Research & Technology: ‘Bioaccumulation behaviour of short chain chlorinated paraffins in Antarctic ecosystem’, by Huijuan Li and Aiqian Zhang (Research Center for Eco-Environmental Sciences)

ES: Nano: ‘Proinflammatory effects of silver nanoparticles and silver ions on human skin keratinocytes’, by Yang Di, Wei Hong-ying, Wang Bin, Fan Jing-pu, Qin Yu, Liu Yue, Guo Xin-biao and Deng Fu-rong (Peking Universty)

Congratulations to all the winners!

The judges of the prize thought the quality of the posters was really high and, from the Environmental Science team, we would like to thank all the researchers that attended or presented at the conference.

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Tracing the impact of the Fukushima nuclear accident

By Ian K.

a blog article by Ian Keyte, Doctoral Researcher at the University of Birmingham

Monitoring the environmental effects of major nuclear incidents is an essential but complex undertaking. The use of the iodine-129 isotope as a tracer for detecting nuclear pollution in the environment has been widely established. The present study, by researchers from the Horia Hulubei National Institute for Physics and Engineering in Bucharest, Romania, applies this method to assess the impact of radioactive releases after the 2011 Fukushima accident  in Japan.

On March 11th 2011, a magnitude 9.0 earthquake stuck 130 km off the east coast of Japan, causing a 15 m tsunami, which inundated about 560 sq km of land. In addition to causing a death toll of over 19,000 and destroying or damaging over a million coastal buildings, this tsunami also disabled the power supply and cooling of three nuclear reactors at the Fukushima Daiichi plant, causing a major nuclear accident. Over 100,000 people were evacuated from the area, and an exclusion zone of 20 km around the plant was established. A comprehensive account of the cause and effects of this Fukushima incident is provided by the World Nuclear Association.

exclusion zone at the site of the Fukushima nuclear incident

Fukushima exclusion zone. Source: Thom Davies (http://thomdavies.com/tag/fukushima/)

In the wake of the disaster, much research and discussion has been undertaken to assess its environmental impact and the future safety of nuclear energy generation. Experts estimate that the Fukushima incident caused the largest ever direct release of radioactive material, such as iodine-129 and caesium-137 isotopes into the Pacific Ocean. The nature and extent of how this nuclear material is transported and dispersed in the ocean requires careful consideration, in order to assess the full environmental impact of the accident.

There is considerable uncertainty regarding the eastward migration of this radioactive plume in the Pacific Ocean and efforts to locate and characterise its position and movement have been unsuccessful so far. Iodine-129 displays a long residence time (half-life of 15.7 million years) and relatively low bioavailability. In very small quantities, it can act as an effective sensitive tracer of the radioactive plume in ocean waters. As a consequence, this study by C. Stan-Sion and co-workers used iodine-129 to determine the nuclear plume impact on the West Coast of the USA, roughly two years after the Fukushima incident.

For this research, ocean water samples were collected in La Jolla, San Diego, California on the West Coast of the USA (approx. 8770 km east of Fukushima) between April and July of 2013. Accelerator Mass Spectrometry (AMS) was used to determine the iodine-129/ iodine-127 ratio in the collected samples. Its very high sensitivity for measuring such isotopes was the main reason why this analytical method was chosen.

The results showed two sudden increases of the iodine-129/ iodine-127 isotopic concentration in the ocean water during late spring of 2013. The isotopic iodine-129/ iodine-127 ratio was more than a 2.5 factor higher in USA West Coast water samples, compared with those measured 40 km offshore of Fukushima immediately after the accident.

Map of Fukushima study area

Also, compared with the pre-Fukushima background values, the results of this study show an isotopic ratio of about two orders of magnitude higher. Based on these results, the authors calculated that the plume travelled with an average speed of approximately 12 cm s-1, which is consistent with the zonal current speed in the Pacific Ocean.

This investigation therefore demonstrates how the iodine-129/ iodine-127 isotopic ratios can be used to assess the impact of a certain nuclear accident in locations far removed from the accident site. Finally, the authors also coupled their iodine-129 results with the results of the Ka’imikai-O-Kanaloa international expedition in June 2011 to assess the activity of other radioactive isotopes such as hydrogen-3 and caesium-137, and the activity of these radio-isotopes were compliant with the international regulatory limits.


To access the full article, download a copy for free* by clicking the link below.

AMS analyses of I-129 from the Fukushima Daiichi nuclear accident in the Pacific Ocean waters of the Coast La Jolla – San Diego, USA
C. Stan-Sion, M. Enachescu and A. R. Petre
Environ. Sci.: Processes Impacts, 2015, 17, 932-938
DOI: 10.1039/c5em00124b

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About the webwriter

Ian Keyte is a Doctoral Researcher at the University of Birmingham. His research focuses on the sources, behavior and fate of polycyclic aromatic hydrocarbons (PAHs) in the urban atmosphere.

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* Access is free until 21/06/2015 through a registered RSC account.

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Using fluorescence to measure the quality of water

a blog article by webwriter Fernando Gomollón-Bel, PhD student at the University of Zaragoza

We use fluorescence to identify counterfeit money. Could we use a very similar technique to assess the quality of fresh water? K. Khamis and colleagues suggest tryptophan-like fluorometers to do so. In their paper, they discuss a novel way of measuring pollutants thanks to this procedure, and also propose novel mathematical models to better conduct in situ experiments, thus avoiding the storage and transportation of samples.

When water is polluted with sewage or farm waste, the amount of dissolved organic matter (DOM) increases. Organic matter contains sugars, lipids, nucleic acids and proteins. The latter are biomolecules which have a very interesting property: fluorescence. Folded proteins are fluorescent, mainly because of the tryptophan residues, and they can absorb and emit light at 280 nm and 350 nm, respectively. As a consequence, fluorescence may be directly correlated with the quantity of organic waste dissolved in water.

However, very few fluorescence sensors have been developed to measure OM in freshwater, mostly because freshwater systems are quite dynamic in space and time. Moreover, certain factors such as temperature or suspended inorganic particles often alter the measurements. Temperature allows electrons to return to their ground-energy state without emitting any fluorescence. Additionally, soil particles can scatter light and reduce the fluorescence signal by up to 80%.

But Khamis and his team did not see a problem in this. On the contrary, they saw this fact as an opportunity to develop new tryptophan-like sensors and state-of-the art algorithms to minimize the effect of quenchers like temperature or soil particles. Researchers located in situ detectors near Birmingham to study urban streams and near Nottingham to study groundwater; they also took a wide set of samples which were analyzed in the lab.

The data obtained from these analyses was then compared to the in situ measurements. Using these two different groups of data, they elaborated mathematical models to compensate the effect of quenchers. These algorithms were fundamental to ensure the accuracy of the quantifications. When the corrections were applied, in situ and lab results appeared to correlate much better.

Thanks to these amazing results, scientists may soon be able to develop cheap, small sized, highly accurate tryptophan-like pollution sensors for freshwater. These detectors could be easily used in the field, hence completely eliminating the need to collect, preserve, store and carry around thousands of samples.


To access the full article, download a copy for free* by clicking the link below:

In situ tryptophan-like fluorometers: assessing turbidity and temperature effects for freshwater applications
K. Khamis, J. P. R. Sorensen, C. Bradley, D. M. Hannah, D. J. Lapworthc and R. Stevens
Environ. Sci.: Processes Impacts, 2015, 17, 740-752
DOI: 10.1039/C5EM00030K

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About the webwriter

Fernando Gomollon-Bel is a PhD Student at the ISQCH (CSIC-University of Zaragoza). His research focuses on asymmetric organic synthesis using sugars as chiral-pool starting materials towards the production of fungical transglycosidase inhibitors.

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* Access is free until 14/06/2015 through a registered RSC account.

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Passive sampling for improved monitoring of indoor air quality

By Ian K.

Indoor air pollutants require careful and accurate monitoring in order to ensure people are not exposed to levels that could cause adverse health effects. This study, commissioned by the U.S. Department of Defense, demonstrates the usefulness of diffusive passive air samplers for this purpose.

People can potentially be exposed to dangerous levels of air pollutants indoors, either directly from indoor sources or from polluted air transported from outside. The WHO has acknowledged the threat of poor indoor air quality, identifying a number of specific pollutants of concern and providing guidance on health effects and recommended guideline exposure limits associated with these contaminants. One class of pollutants causing concern are volatile organic compounds (VOCs). The USEPA warn that VOCs have been linked with a number of adverse health effects including damage to the kidney, liver and central nervous system, as well as eye, nose and skin irritation, headaches and nausea.

Domestic combustion sources, such as heating and cooking, are known to be important sources of VOCs; however, an emerging source of interest is the intrusion of vapour from contaminated soil or groundwater into a building. Careful monitoring of VOCs is clearly needed to carry out appropriate risk assessment and identify the relative contribution of this intrusive source on total VOC concentration in the indoor environment. Conventional air sampling methods typically do not allow for monitoring for more than a 24 hour period. However, due to the temporal variability of some VOCs, longer sampling duration is needed to better represent the long-term average concentrations of VOCs.

Passive diffusive samplers are therefore well-suited to this application as they have the ability to detect relatively low concentrations of contaminants over relatively long sampling duration. Passive air samplers commonly use a sorbent material to trap VOCs, which reach the sampler via diffusive transfer from the surrounding atmosphere. A time-weighted average concentration can be calculated subsequently in the lab. Passive sampling has been used for indoor air quality monitoring in occupational settings for decades, but the application to monitoring subsurface vapour intrusion to indoor air requires further work to assess their capabilities and limitations for lower concentrations and longer exposure durations.

Passive diffusive air samplers are shown in this study to be an effective means of monitoring indoor air quality     Passive air samplers

Air samplers

This article by Todd McAlary and co-workers, combining work of research laboratories in Canada, the USA, UK and Italy, describes laboratory testing of passive diffusive samplers for assessing indoor air concentrations of VOCs in order to demonstrate and validate their potential usefulness.

Four different passive samplers were tested, utilising different types of sorbent, under a wide range of controlled laboratory conditions (temperature, humidity, VOC concentration and sampling duration) with review from leading experts on each sampler type. 10 different VOCs were measured including aliphatic compounds such as alkenes and alkanes as well as aromatic compounds such as benzene and naphthalene, in order to assess compounds that cover a range of physiochemical properties and some compounds that pose a challenge to sampling.

The results demonstrate that passive samplers can potentially provide data that is more representative of long-term average indoor air concentrations than conventional methods that are limited to shorter sample durations. The results show the passive samplers proved data that meets a set of success criteria for most of the compounds tests, although some compounds were identified as being more problematic. The study provides a unique and valuable new body of data on indoor air quality monitoring. However, the authors also caution that passive sampling programs will need to be supplemented by quality assurance measures. For example, outdoor air samples should be taken simultaneously with indoor sampling to help ascertain the relative contributions of different pollution sources.

To access the full article, download a copy for free* by clicking the link below:

Passive sampling for volatile organic compounds in indoor air-controlled laboratory comparison of four sampler types
Todd McAlary, Hester Groenevelt, Stephen Disher, Jason Arnold, Suresh Seethapathy, Paolo Sacco, Derrick Crump, Brian Schumacher, Heidi Hayes, Paul Johnson and Tadeusz Góreckic
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/c4em00560k

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About the webwriter

Ian Keyte is a Doctoral Researcher at the University of Birmingham. His research focuses on the sources, behavior and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere.

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* Access is free until 07/06/2015 through a registered RSC account.

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An improved insight into the behaviour of palladium in the environment

a blog article by webwriter Ian Keyte, Doctoral Researcher at the University of Birmingham

The presence of common organic species in the environment could potentially transform metal species from a chemically inert form into more mobile and bioaccessible species, thus influencing the extent and nature of their potential ecological impacts. This collaboration between German and Canadian research institutions demonstrates how this phenomenon can impact the environmental behaviour of palladium, a metal of increasing environmental interest.

The environmental performance of road vehicles has been enhanced in the last 20 years by the use of three-way catalytic converters (TWCCs), which are shown to dramatically reduce emissions of CO2 as well as organic pollutants.

The key active catalyst used in TWCCs is palladium (Pd), either used on its own or in combination with other metals such as platinum (Pt) and rhodium (Rh). Indeed, it is estimated that global consumption of Pd by the catalytic converter industry increased nearly 10-fold between 1993 and 2013. It has been indicated that the increased use of Pd in TWCCs has been accompanied by increasing environmental concentrations of Pd compounds observed in soils, sediments, plants and aquatic ecosystems.

This has therefore led researchers to question the possible post-emission transformation, mobility and bioavailability of Pd in the environment, and the factors influencing this behaviour. This type of research is essential in order to assess and reduce the potential ecological damage caused. It is known that organic constituents commonly present in soil, sediments and aquatic systems can form complexes with metals in the environment, which strongly influences the mobility of metals such as zinc (Zn), iron (Fe) and cadmium (Cd). However, much less is known about the chemical behaviour of Pd-containing compounds in the presence of these naturally-occurring organic substances such as humic acids in the environment , and knowledge regarding the environmental behaviour and mobility of Pd under typical environmental conditions is limited.

This study by Fathi Zereini and co-workers quantitatively examines the chemical mass transfer, stability and solubility of Pd in the presence of organic complexing agents and the key factors (such as the pH and concentration of organic species) influencing this process, to better understand the potential behaviour of Pd resulting from catalytic converters under typical environmental conditions. The investigation conducted batch experiments using metallic Pd and Pd(II) oxide catalyst particles to investigate the transformation and solubility of these particles in the presence of ethylenediamine tetra acetic acid (EDTA), a common metal chelating agent, which is ubiquitous in the environment.

The results of this experiment demonstrate that, while the EDTA has little impact on the chemical state of Pd oxide, the elemental form of Pd metal used in catalytic converters can be solubilised post-emission under ambient conditions. The pH of Pd-EDTA solutions was shown to modulate Pd solubility and solubility was found to increase with a corresponding increase in the strength of the EDTA concentrations used, in addition to the length of extraction time.

This study therefore indicates that the presence of EDTA can oxidize small amounts of Pd emitted in metallic form into the environment from catalytic converters, thereby contributing to an enhanced mobility and possible bioaccessibility of this metal. These results contrast with previous assumptions that metallic Pd present in soils is chemically inert and immobile.

To access the full article, download a copy for free* by clicking the link below.

The influence of ethylenediamine tetra acetic acid (EDTA) on the transformation and solubility of metallic palladium and palladium(II) oxide in the environment
Fathi Zereini, Clare L. S. Wiseman, My Vang, Peter Albers, Wolfgang Schneider, Roland Schindl and Kerstin Leopold
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C5EM00078e

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About the webwriter

Ian Keyte is a Doctoral Researcher at the University of Birmingham. His research focuses on the sources, behavior and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere.

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* Access is free until 27/05/2015 through a registered RSC account.

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Salty soil set to hamper Bangladesh crop production

a ChemistryWorld article by Elisabeth Bowley

Salty soil set to hamper Bangladesh crop production

Scientists have quantified the effect of climate change on soil salinity and crop production in Bangladesh. Their models suggest the monsoon will be unable to fully leach dry season salt deposits and that salt accumulation will become a major issue for farmers in coastal regions with farm productivity dropping by as much as 50%.

The team discovered that irrigation with water that contained a salinity measure of 8ppt resulted in incomplete salt leaching and an average crop loss of 50%. This level of damage is likely to make farming unsustainable and since salinisation is difficult to counteract, the ESPA Delta project is now researching salt tolerant crops.

To read the full article, please visit ChemistryWorld.

Projections of on-farm salinity in coastal Bangladesh
D. Clarke, S. Williams, M. Jahiruddin, K. Parks and   M. Salehin
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C4EM00682H

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Improving phosphorous monitoring

a blog article by webwriter Ian Keyte, Doctoral Researcher at the University of Birmingham

Improving our insight into nutrient cycling in lake systems is essential to appropriately tackle the problem of eutrophication. Researchers from the University of Oslo and the Norwegian Institute for Water Research present a technique for monitoring bioavailable phosphorous (P) concentrations, which can provide advantages over conventional water sampling and potentially open an exciting new direction for research in this field.

It is widely established that eutrophication causes serious deterioration of fresh and marine waters. The primary cause is an excessive input of plant nutrients (e.g. N and P) to water courses from human activities such as agriculture or sewage treatment, causing excessive development of algae, which severely disturbs aquatic ecosystems. The WHO has highlighted the key environmental and health risks associated with eutrophication and the need to adequately tackle this problem.

Current abatement actions, such as redirecting sewage wastewater and reducing the P input from agriculture have had limited effectiveness in many cases. This has brought attention to the role of the background flux of P in river catchments; for example, the input of Dissolved Natural Organic Matter (DNOM) and in particular the role of bioavailable low-molecular-weight organic phosphorus (LMWOP) compounds such as nucleic acid derivatives, phospholipids and sugar phosphates.

The fluctuating and very low concentrations of these compounds present major challenges in the monitoring of the bioavailable P fraction by conventional methods. This study by Christian Wilhelm Mohr and co-workers presents a technique for monitoring the ambient concentrations of dissolved reactive phosphorus (DRP) and dissolved organic phosphorus (DOP), especially the LMWOP DOP sub-fraction, using Diffusive Gradient in Thin Films (DGTs).

DGTs have been used as passive samplers based on their linear diffusive uptake of components, which allows time average concentrations to be determined for species commonly present in concentrations close to the limit of detection. However, the present challenge is how to use the amount of analyte determined from the DGTs to predict the ambient concentration of LMWOP and therefore gain better insight into the long- and short-term variation of DRP and DOP concentrations in different systems. Consequently, the ultimate aim is to use this technique to carry of real-world risk assessments.

In this study, DGTs fitted with phosphate adsorbent Fe-oxide binding gel were used to collect the orthophosphate and LMWOP compounds, adenosine monophosphate (AMP) and myo-inositol hexakisphosphate (IP6) respectively, in experimental test solutions. Theoretical modelling was used to determine diffusion coefficient (D) values, a key parameter relating the amount of analyte measured by the DGT to the time averaged ambient concentration. Validation of DGT data was performed by comparing concentrations of P fractions determined in water samples, collected via conventional means with concentrations using DGT, in three 1st order streams draining different types of catchments (e.g. forest, mixed and agriculture).

The authors discuss the appropriate use of DGT sampling data, explaining that because the relative distribution of LMWOP molecules will differ between different catchments, a range of model-derived D values should be investigated. It is suggested this could allow a ‘best fit’ of D values for different sites and a “tailored” D value for different individual water bodies to be determined in order to practically use the DGTs for estimating time average DOP.

It was shown that the DGT method was successful in the linear uptake of AMP and IP6, and could therefore potentially be applied to other LMWOP compounds. The catchment study indicated a reasonable agreement between the dissolved P fractions determined from water samples and by DGTs and that the stream water samples from the different catchments showed clear differences in relative and absolute concentrations of DRP and DOP. This study demonstrates that the use of DGT can help improve our insight into the cycling of P in eutrophic lakes and specifically the spatial variation of ambient levels of DRP and LMWOP in these systems. However, the models tested for estimating D for different LMWOP molecules are still too uncertain for practical use.

The authors note that more studies are needed to better quantify the distribution of DOP with molecular weight for a variety of catchments with different land-use. For example, further experimental and sampling studies will be needed to determine D values for a wider range of LMWOP molecules so that better calibration and validation of model performance can be performed and different environmental conditions (e.g. pH) can be investigated.

To access the full article, download a copy for free* by clicking the link below.

An in-depth assessment into simultaneous monitoring of dissolved reactive phosphorus (DRP) and low-molecular-weight organic phosphorus (LMWOP) in aquatic environments using diffusive gradients in thin films (DGT)
Christian Wilhelm Mohr, Rolf David Vogt, Oddvar Røyset, Tom Andersen and Neha Amit Parekh
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C4EM00688G

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About the webwriter

Ian Keyte is a Doctoral Researcher at the University of Birmingham. His research focuses on the sources, behavior and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere.

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* Access is free through a registered RSC account.

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Introducing Desirée Plata, new Editorial Board member

Continuing our series of blog posts introducing the newest Editorial Board members of Environmental Science: Processes & Impacts, in this article we are delighted to welcome Desirée Plata as a new Editorial Board member of the journal!

Dr Plata holds a Ph.D. in Environmental Chemistry and Chemical Oceanography from the MIT and the Woods Hole Oceanographic Institution. She has a B.S. in Chemistry from Union College and proudly attended Gould Academy for high school.

Desirée’s Research

Desirée’s interests focus on improving the development of novel chemicals and engineered systems to include environmental objectives, along with traditional performance and cost metrics.

She seeks to predict and mitigate environmental damage through physiochemical understanding of material reactivity, prognostic fate models, and geochemical analyses. Also, she is working towards the design of benign syntheses via mechanistic understanding of chemical reactions used in industrial processes.

MY RESEARCH VISION:

“I envision a future in which technological solutions do more good than harm. In particular, I think environmental scientists should work with material and process designers to ensure technologies that both sustain and advance environmental health.

My group strives to have this synergy result in a product or process that is not only better for the environment, but better performing as well. I believe this type of work will eventually redefine the role of environmental scientists and engineers in innovation and, ultimately, the approach to innovation globally.”

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