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Going deep: investigating the physical and chemical properties of humic substances in groundwater

Humic substances play an important role in the speciation of metal ions in the aquatic environment. Understanding these processes is important to ensure the safety of drinking water. In this study, Japanese researchers reveal how physiochemical properties and ion-binding behaviour of HSs can differ between surface water and groundwater environments.

Groundwater constitutes the largest reservoir of freshwater in the world, accounting for over 97% (excluding glaciers and ice caps) of all available freshwater on the planet. It is estimated that about 75% of EU inhabitants depend on groundwater for their water supply. Groundwater also plays an integral role in the hydrological cycle, crucial to the maintenance of wetlands and river flows. Maintaining the quality of groundwater resources is therefore of major environmental, social and economic importance. This requires a good understanding of the physical and chemical processes that may influence groundwater environments.

For future use of deep underground space it is necessary to monitor and protect the quality of deep groundwater. The World Health Organisation (WHO) acknowledges the importance of groundwater resources and the potential risks that poor quality groundwater can cause to human health. Indeed, the WHO has produced a guidance document, “analysing hazards to groundwater quality, assessing the risk they may cause for a specific supply, setting priorities in addressing these, and developing management strategies for their control.”

Humic substances (HSs) are a class of natural organic molecules, ubiquitous in various environments including surface and ground water, oceans, soils, and the atmosphere. HSs are known to play an important role in freshwater systems. For example HSs can effectively capture inorganic and organic contaminants due to the tendency of protons and metal ions to readily bind to the functional groups of HS ligands e.g., carboxylic and phenolic groups and to a lesser extent amine- and sulphur-containing groups. This process can therefore alter the reactivity, bioavailability, and mobility of chemical constituents in fresh water.

The physical and chemical nature of HSs is likely to differ between deep underground and surface aquatic systems, due to slower water movement and more prolonged contact with underlying rocks and dissolved/suspended components, low oxygen, and lack of sunlight. However, while some characteristics of groundwater HSs are understood, their ion binding properties over a wide range of conditions is largely unknown. Given that in many areas, deep underground space may be used in the future for such uses as geological disposal of nuclear wastes, the potential deterioration of groundwater quality, the ion binding properties of deep groundwater HSs need to be studied carefully, and mechanistic models developed to describe these processes.

This study by Takumi Saito and co-workers investigates the physicochemical and binding properties of HSs isolated from deep groundwater in a sedimentary rock formation in the Horonobe Underground Research Laboratory of the Japan Atomic Energy Agency (JAEA). Binding isotherms of protons (H+) and copper (Cu2+) were measured over a wide range of conditions by potentiometric titration and were fitted to the NICA-Donnan model and the obtained parameters were compared with average parameters for HSs from surface environments. The oxidation state and local coordination environment of Cu2+ bound to the HA fraction of the HSs were also assessed by X-ray absorption spectroscopy (XAS).

The results clearly indicate distinctive physical and chemical characteristics for the HSs from surface and groundwater environments. It is found that the deep ground HSs were characterised by high aliphaticity and sulphur (S) content and relatively small sizes. Differences in the binding behaviours of H+ and Cu2+ with the HSs in deepwater and surface water were also observed.

The authors discuss the differences in chemical binding behaviour with reference to the unique chemical nature of the functional groups of groundwater HSs compared with those of surface waters and how the binding sites and binding mode can change with changes in conditions (e.g. pH). X-ray absorption spectroscopy also revealed that Cu2+ binds to O/N containing functional groups and to a lesser extent S containing functional groups.

The study therefore demonstrates how HSs could influence freshwater resources differently in deep-ground and surface environments. Although the HSs in this study were derived from a single groundwater source, the authors suggest the outcomes can be applied or be a good starting point to estimate the degree of metal binding to HSs in sedimentary groundwater in general.

The authors also suggest these results should be examined in the future by performing similar investigations for HSs isolated from a range of different groundwater samples and for a wider range of metal ions. This would allow accurate and realistic parameter sets applicable for groundwater HSs to be developed for further modelling for a more extensive range of chemical species.


To read more about this research, download a copy of the manuscript for free* by clicking the link below.

Physicochemical and ion-binding properties of highly aliphatic humic substances extracted from deep sedimentary groundwater
Takumi Saito, Motoki Terashima, Noboru Aoyagi, Seiya Nagao, Nobuhide Fujitake and Toshihiko Ohnuki
Environ. Sci.: Processes Impacts, 2015,17, 1386-1395
DOI: 10.1039/C5EM00176E

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Ian Keyte

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 20/09/2015 through a registered RSC account.

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Assessing the impacts of human activity on plants in one of the world’s most remote regions

These days it seems human activity knows no bounds, reaching as far as the polar regions which have seen an increased flurry of anthropogenic disturbance due to research and tourism. As a result of these activities, fuel spills and their detrimental effects on the local ecosystem are not uncommon in the sub-Antarctic and Antarctic.

It has been estimated that soil in the Antarctic covering an area the size of (10 million cubic meters) is contaminated with hydrocarbons. This environment presents barriers to natural removal of hydrocarbons including low nutrient content and low temperatures that limit microbial activity, as well as low rates of volatilization and evaporation caused by the same reason. Establishing reasonable remediation targets requires a thorough understanding of the biological effects of petroleum hydrocarbons, which can be achieved using biological assays. Though international protocols for such assays have been modified for application to Arctic and cold-climate species, our knowledge of the effects of hydrocarbons on plants in these regions is still lacking.

A recent study by Macoustra and co-workers is one of the few to provide such data for the sub-Antarctic region. The researchers first collected seeds from 12 native plants on Macquarie Island, the site of one of Australia’s scientific research stations and multiple diesel fuel spills. They tested the seeds for their suitability for bioassays in the lab, and used the species that successfully germinated in a second bioassay involving exposure to a range of diesel concentrations in soils, at both high and low organic carbon contents. Only four species were able to germinate during the second bioassay, indicating that diesel-contaminated soils reduced germination success.

Using the four species that germinated during the second bioassay, a final bioassay was performed over a 28 day period, again with soils exhibiting a range of diesel contamination and either low or high organic carbon content. The endpoints assessed were germination success, and early-life root and shoot growth. The researchers found that soils with low organic carbon content were generally more toxic to plants than high organic carbon content, and attribute this to the lower bioavailability of organic contaminants associated with higher levels of organic matter, in addition to higher nutrient levels that promote plant growth and higher rates of microbial degradation of petroleum hydrocarbons. Root growth was the most sensitive endpoint, likely due to the high permeability of early-life root tissues.

Though the concentrations of petroleum hydrocarbons necessary to inhibit early growth were similar to those likely to be found very close to a spill site, the unique conditions in the sub-Antarctic that greatly inhibit hydrocarbon loss processes mean that such concentrations can persist in the environment.

Prior to this study by Macoustra and co-workers, there was no such toxicity data for early life stages of native sub-Antarctic plants exposed to petroleum hydrocarbons. This data is extremely useful for models currently being developed to assist in creating remediation targets for the sub-Antarctic, as the models require a certain number of species from a minimum number of taxonomic groups.


To read more about this research, download a copy of the manuscript for free* by clicking the link below.

Impact of hydrocarbons from a diesel fuel on the germination and early growth of subantarctic plants
GK Macoustra, CK King, J Wasley, SA Robinson and DF Jolley
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C4EM00680A

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About the webwriter

Abha Parajulee is a Ph.D. student at the University of Toronto Scarborough. She is interested in water resources and the behavior of organic contaminants in urban environments.

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* Access is free until 06/09/2015 through a registered RSC account.

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Getting to the chiral centre of aquatic pollution

The chemical behaviour of pollutants in the aquatic environment requires careful monitoring in order for us to understand the toxicity different compounds will exert on natural ecosystems. Researchers from Israel describe a new modelling approach that may provide an exciting new technique to address a specific aspect of the chemical and environmental behaviour of pollutants.

The term ‘chiral’ is given to molecules that exhibit identical composition, but where the components of the molecule are arranged in a non-superimposable mirror image composition, centred around an asymmetric carbon atom. The two ‘mirror images’ of a chiral molecule are termed enantiomers. The study of the enantiomer-specific properties and how these vary between different molecules is of major interest within the broad fields of inorganic, organic, physical, biological and environmental chemistry.

Many anthropogenic chemicals of environmental concern, such as pesticides, are chiral molecules. These compounds can potentially be major threat to aquatic ecosystems. For example, the molecular structures and environmental implications of many chiral pesticides have been discussed in a review by the USEPA. It is important, therefore,  to have means of accurately tracing the alteration of these compounds in the environment, particularly with reference to their enantiomer-specific environmental toxicity.

Researchers have previously proposed an enantiomeric enrichment factor (EEF), to describe the enantiomeric enrichment – conversion relationship of chiral compounds, derived using the Rayleigh equation, which describes the relationship between changes in the isotopic composition against the contaminant concentration during the degradation process. The EEF can therefore be used as an identifying tool for a specific enzymatic reaction of different molecules.

Developing models to describe enantio-selective biodegradation can alleviate the need for laborious practical work. To achieve this, there is a need to improve our understanding of the mechanisms of biodegradation, to classify chemicals according to their relative biodegradability, and to develop reliable biodegradation estimation methods for new chemicals. Quantitative structure–activity relationship (QSAR) models are typically derived based on the correlation between experimental data and physical properties (e.g. lipophilicity, steric and electronic parameters) and can be used to identify bioavailability, toxicity and biological activities of compounds as dependent variables.

This study, conducted by researchers from The Institute of Chemistry at The Hebrew University of Jerusalem and The Geological Survey of Israel, develops a QSAR model to describe the dependence of the enantiomeric enrichment factor on molecular structures and uses this method to evaluate EEF values for unstudied chiral compounds.  The authors used the multiple linear regression (MLR) method to build the QSAR based on the Linear Hansch model. The enantioselective hydrolysis of 16 derivatives of 2-(phenoxy)propionate (PPMs) (some of which are common herbicides) using three  different lipase enzymes was analysed.

The study provides a demonstration of the predictive power of QSAR and Hansch modeling for analysis of the structural dependence of the EEF, with the model shown to effectively correlate biological activity with key physicochemical properties. More importantly, at times, the QSAR of EEF values was shown to be a much better predictive tool than the QSAR of just the underlying individual kinetic parameters, clearly indicating this method could mark the way forward for research in this field.

The authors note that the use of the QSAR modelling technique used in this study may serve as a powerful tracer tool in environmental studies, assisting in source tracking the enantio-selective conversion of both known and unstudied chiral compounds in aquatic ecosystems.



To read more about this study, download a copy for free* by clicking the link below.
Quantitative structure–activity relationship correlation between molecular structure and the Rayleigh enantiomeric enrichment factor
S. Jammer, D. Rizkov, F. Gelman and O. Lev
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/c5em00084j

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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 30/08/2015 through a registered RSC account.

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Detecting endocrine disrupting chemicals in wastewater

Some steroidal estrogens and certain polyphenols may be a threat to aquatic ecosystems. These compounds, usually known as endocrine disrupting chemicals (EDCs) pollute our water inducing a potential ecological risk. They may be artificial waste products from chemical industries, but some are natural hormones excreted by cattle, poultry, or even humans. Some of them (like estriol or 4-nonyl-phenol) have been linked with very serious problems like decreasing fertility or causing feminisation in fish.

Thus, having a validated method to estimate the concentration of EDCs in water comes in handy, especially for the detection of these contaminants in the effluent of wastewater treatment plants. Treatment plants act as the last barrier before EDCs are permanently released in the environment.

A group of researchers from the Chinese Academy of Sciences has developed a new analytical method to determine the concentration of up to 12 different EDC contaminants. They have optimised an easy pretreatment that avoids enzymatic digestion of the samples, hence allowing for the first time the detection of the different EDCs conjugated salt forms (sulphate and glucuronide). As these EDC conjugates predominate in urine and faeces, having a method to analyse them effectively is useful to know the origin of these pollutants.

This particular analytical method uses state of the art ultra high performance chromatography (UPLC) and MS/MS detectors to improve limits of quantification to small amounts of EDCs down to 0.04 nanograms per litre. The experiments have determined that some species, like 17b-estradiol and all the glucuronide conjugates, are completely removed from wastewater after treatment.

Others, on the other hand, are only partially eliminated (removals may vary between 34 and 95% of the amount of EDC in the influent). The risk of not eliminating these contaminants from the effluent, ultimately released in the environment, has to be studied in depth.


Click on the link below to read the full article for free*:
Simultaneous detection of endocrine disrupting chemicals including conjugates in municipal wastewater and sludge with enhanced sample pretreatment and UPLC-MS/MS
Bing Zhu, Weiwei Ben, Xiangjuan Yuan, Yu Zhang, Min Yang and Zhimin Qiang
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C5EM00139K


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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 24/08/2015 through a registered RSC account.

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Developing new models to understand social problems in Bangladesh

Bangladesh is, sadly, the centre of a wide variety of meteorological disasters (cyclones, floods, saline water intrusion…). Moreover, it is one of the most vulnerable countries on Earth to any sea-level rise that global climate change may cause. In addition to all of this, Bangladesh population is quickly growing, and it is now one of the most densely populated nations. All these factors affect, of course, the country’s agricultural system and correlate directly with its ability to feed the population. A recently published paper proposes the creation of a new model framework to study both macro- and micro-scale environmental processes and link these to the prosperity of the Bangladeshi households.

Thanks to the efforts of both the government and the people of Bangladesh, poverty level has decreased from 70 to 43 percent in less than twenty years. However, poverty levels are higher in coastal regions, such as the area of this study. Could climate change aggravate this situation? To estimate this, the authors developed a new model that takes into consideration a broad diversity of factors.

To begin with, they have used mathematical models created by the Food and Agriculture Organization (FAO) to estimate the crop productivity. These models were enhanced with climate, soil salinity, cropping patterns and market price data from diverse databases. Also, they have studied demographic information from different sources.

Additionally, they have added what is one of the major innovations of this particular model: financial data of individuals and families. Thus, researchers were able to evaluate and analyse the complex relationship between nature, agriculture and day-to-day life of farmers.

Some conclusions were quite surprising: i.e., if farmers increased their productivity substantially, they would experience a very small increase in their income. This is mainly due to a quite extended access to credit that has led families to assume debt they cannot afford, even working longer hours. Besides, these study points out that crop diversification may not help overcome climate change. Nonetheless, these are the first results of a very new prediction model. This opens new opportunities to further analyses, research and improvements on the models for a better understanding of the situation in Bangladesh.



To read more about this study, download a copy for free* by clicking the link below.

Agricultural livelihoods in coastal Bangladesh under climate and environmental change – a model framework
Attila N. Lázár, Derek Clarke, Helen Adams, Abdur Razzaque Akanda, Sylvia Szabo, Robert J. Nicholls, Zoe Matthews, Dilruba Begum, Abul Fazal M. Saleh, Md. Anwarul Abedin, Andres Payo, Peter Kim Streatfield, Craig Hutton, M. Shahjahan Mondal and Abu Zofar Md. Moslehuddin
Environ. Sci.: Processes Impacts, 2015,17, 1018-1031
DOI: 10.1039/C4EM00600C

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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 16/08/2015 through a registered RSC account.

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Slick research: reviewing available technologies for tackling oils spills

Oil spills can cause widespread environmental damage. The production, refining, storage and distribution of oil are all potential sources of pollution of marine and terrestrial ecosystems. Recent high-profile accidents on offshore oil platforms such as the Deepwater Horizon incident in 2010 give the public clear insight into the effect large-scale oil spills can have. However, as dramatic as these pollution events are, these incidents represent less than 10% of total petroleum hydrocarbon discharges to the environment. The vast majority of pollution results from relatively low-level routine releases on a more local scale. The challenge is therefore to ensure safety of oil production as a whole rather than simply the prevention of large-scale incidents.

As existing oil reserves become increasingly depleted, exploration and drilling is spreading into deeper waters and more remote, fragile environments, such as the Arctic. Since oil production from newly explored or depleted reservoirs is more difficult, the risk of accidental oil spills in the future is likely to increase. Indeed, it is estimated that, for an average platform, each 30 metres of added depth increases the probability of an accident by 8.5%. There is clearly a need for clear and coherent strategies to be in place to help prevent and/or clean up accidental oil spills and to this end, there has been considerable world-wide effort has gone into strategies for minimising accidental spills and the design of new remedial technologies.

the Deepwater Horizon Oil Spill in the Gulf of Mexico caused a major ecological hazard

Deep Water Horizon Oil Spill - US Coast Guard Photo by Petty Officer First Class John Masson (courtesy of Chemistry World)

This critical review is the result of collaboration between the Institute of Ecology and Genetics of Microorganisms in the Russian Academy of Sciences, Perm State University in Russia, The Scottish Environmental Technology Network at the University of Strathclyde in Glasgow, UK, The University of Louisville in Kentucky, USA and the OECD Directorate for Science, Technology and Industry in Paris, France. The paper provides a summary of new knowledge as well as research and technology gaps essential for developing appropriate decision-making tools in actual oil-spill scenarios. The review will therefore be of interest to a wide range of stakeholders, including the oil industry, the scientific community and the public.

The review provides a clear comparison between the behaviour and environmental effects of marine and terrestrial oil spills (e.g. the nature of the spread of oil and size of affected area). The differences in appropriate response strategy for marine and terrestrial spills are clearly defined. The importance of ‘window-of-opportunity’ technology in combating oil spills is highlighted, i.e. the integration of different types of scientific information to allow rapid decision making on the best available strategy to achieve optimal environmental and cost benefits. The authors note that effective response to oil spills will require a) adequate data oil weathering over time; b) real-time remote sensing; c) analysis of response strategy performance. The review discusses the technological advances and challenges involving the multi-media modelling approaches to generating and analysing this information.

An in-depth review of different available technologies is provided and the authors use specific case studies to illustrate their effectiveness. For the marine environment this includes a discussion of chemical treatments (e.g. dispersants, emulsion breakers); in-situ burning; mechanical recovery (e.g. booms, skimmers, adsorbants etc) and bioremediation. In relation to the terrestrial environment, the review discusses the methods to prevent oil spills both on land and into ground/surface waters as well as more advanced clean-up technologies such as thermal desorption, soil vapour extraction, pump and treat technologies and solidification/stabilisation and bioremediation. The review also discusses the details, limitations and environmental effects of on-land containment and control technologies such as diversion/containment measures, trenches, sorbent or viscous liquid barriers.

Control technologies to prevent or tackle accidental oil spills

Technologies to prevent, control or tackle accidental oil spills

The authors emphasise that, because every spill is unique, there is no ‘one size fits all’ technology that will be suitable. The environmental impact and sustainability of remedial technologies vary widely so a suite of remedial technologies is required, and this should be part of the ‘risk-based remedial design’ strategy. The review highlights bioremediation methods as sustainable, cost-effective clean-up solutions and to achieve greater penetration of these techniques into the market depends on the harmonisation of environment legislation and application of innovative laboratory techniques e.g. ecogenomics to improve the predictability of bioremediation. However, it is also stressed that prevention is far less expensive than cure, and oil spill prevention should continue to be the focus for the industry.

This paper is a comprehensive and timely review of oil spill prevention and remediation methods, providing an invaluable summary of available technologies for remediation to increase awareness that a hierarchy of remedial technologies exists. Furthermore, it demonstrates that that there is a need for further development of both “soft” technologies, such as contingency planning, and “hard” engineering solutions for spill prevention. It is stressed that ultimately an integrated approach to prevention and remediation is needed and that greater international cooperation in contingency planning and spill response would probably lead to higher safety standards and fewer accidents.



To access the full article and read more about the technologies and strategies of tackling oil spills, download a copy for free* by clicking the link below.

Oil spill problems and sustainable response strategies through new technologies
Irena B. Ivshina, Maria S. Kuyukina, Anastasiya V. Krivoruchko, Andrey A. Elkin, Sergey O. Makarov, Colin J. Cunningham, Tatyana A. Peshkur, Ronald M. Atlas and James C. Philp
Environ. Sci.: Processes Impacts, 2015, Advance Article
DOI: 10.1039/C5EM00070J

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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 18/08/2015 through a registered RSC account.

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Seeing an unseen carbon sink

Wetlands may have a small global footprint, but provide several important services including improving water quality, and providing flood protection and erosion control. In recent years, they have become increasingly recognized for their strong ability to sequester carbon. Despite covering only six to nine percent of the Earth’s surface, it is estimated that they store upwards of 35% of terrestrial carbon.

Whether an ecosystem (such as a wetland) is a carbon source or a carbon sink is determined by its net ecosystem carbon exchange (NEE). Accurate estimates of NEE in turn require accurate estimates of Gross Primary Production (GPP), which is a measure of how much carbon is fixed in plants during photosynthesis –the main pathway for transport of carbon from the atmosphere to the land. GPP can be measured directly in the field. However, these direct measurements are both financially costly and time-consuming.

A promising approach to estimate GPP that overcomes these hurdles uses empirical modeling to correlate GPP with related biogeophysical parameters derived from remote sensing data. These biogeophysical data can be much easier to obtain than field measurements of GPP, especially if the data are available for free, as is the case with data from the Moderate Resolution Imaging Spectroradiometer (MODIS), an instrument onboard two NASA satellites.

Data derived from instruments such as MODIS that are useful for estimating GPP and NEE include land surface temperatures and vegetation indices. These indices describe the health or density of vegetation. Numerous studies have been conducted to estimate the GPP of ecosystems such as forests, croplands and grasslands using remote sensing data. A recent study by Wu and co-workers, from the Chinese Academy of Sciences, is one of the few studies to focus on the GPP of wetlands.

For an estuarine wetland in eastern China, the authors extracted various biogeophysical parameters from MODIS data, and correlated these parameters with field-measured GPP. When validating their model, the authors found that they were able to estimate the GPP of their study site with a high degree of accuracy. However, they caution that their model cannot simply be taken as-is and applied to different climates and ecosystems.

As the authors demonstrate, certain relationships in the model can vary from one ecosystem to another. For example, the relationship that uses land surface temperatures and vegetation indices to estimate light use efficiency, a measure of carbon fixation via photosynthesis, will be different for a boreal forest relative to an estuarine wetland. As yet, the model has only been validated for one particular wetland across several 8-day periods. Thus, the model still needs to be tested on other wetlands and other ecosystem types to evaluate its performance within and across ecosystem types.

Despite the relative newness of this model, its performance so far combined with the free availability, high temporal resolution, and wide spatial coverage of the MODIS data it requires mean it shows great potential for simplifying the way in which we estimate an ecosystem’s ability to sequester carbon.


To access the full article and read more about using satellite data to “see” how well wetlands take up carbon, download a copy for free* by clicking the link below.

Combining remote sensing and eddy covariance data to monitor the gross primary production of an estuarine wetland ecosystem in East China
Mingquan Wu, Shakir Muhammad, Fang Chen, Zheng Niu and Changyao Wang
Environ. Sci.: Processes Impacts, 2015, 17, 753-7625
DOI: 10.1039/C5EM00061K

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About the webwriter

Abha Parajulee is a Ph.D. student at the University of Toronto Scarborough. She is interested in water resources and the behavior of organic contaminants in urban environments.

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* Access is free until 24/07/2015 through a registered RSC account.

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Breaking the mould: assessing microbial pollution in the indoor environment

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

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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Tracing the impact of the Fukushima nuclear accident

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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