Environmental Science: Processes & Impacts blog

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.

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.

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.

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.

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.

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.