Environmental Science: Processes & Impacts blog

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.

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.

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.