Environmental Science: Processes & Impacts blog

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

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

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

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

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

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

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

In remediation of hydrocarbon contamination, it is vital to be able to monitor the levels of the desired relatively harmless end-product CO₂. There are a large number of different ways to check hydrocarbon degradation varying in cost and complexity.

Differentiating naturally derived CO₂ from contaminant-derived CO₂ for accurate measurements is often a problem. Carbon isotope ratios of the contaminant versus the product environment can be used. Radiocarbon analysis can monitor CO₂ very effectively as fossil fuel sources are radiocarbon-free and can be compared against carbon from plants and soil from photosynthesis. Enhanced radiocarbon-depleted CO₂ relative to a background measurement indicates fossil fuel degradation.

In this HOT article, soil gas and groundwater CO₂ radiocarbon analysis is used to assess whether fuel hydrocarbons at a US Navy facility are being removed naturally. Using a two end-member isotopic mixing model the researchers determine how much of the CO₂ comes from fossil fuel. The model includes two components are the fossil fuel-derived and the natural organic matter-derived CO₂ analysed using the one tracer, radiocarbon. The fraction of CO₂ from fossil fuel was 93% at the fuel contaminated site.

This is further demonstrating of radiocarbon as an on-site tool for initial or ongoing analysis to assess remediation method efficiency. This HOT article as chosen by the referees is free to access for the next 4 weeks*:

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

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

There has been recent concern that antibiotics in the environment may increase bacterial resistance, potentially having consequences on their efficacy.  The use of antibiotics on livestock has greatly increased in recent years, estimated by over 50% between 2007 and 2010, resulting in a proportional increase in the amount excreted into wastewater as active compounds.

Ben et al. surveyed 41 swine wastewaters from 21 concentrated animal feeding operation sites in the Shandong Province, China, in both the summer and winter.  The group targeted 5 sulfonamides, 3 tetracyclines and a macrolide analysing both the liquid and solid fractions of the wastewater.  The sample preparation in brief included ultrasonication (for the solid samples) and Solid Phase Extraction (SPE) followed by LC-MS.

Results in brief showed that all antibiotics, apart from one, were found at concentrations which were largely comparable to other data within this field, although occasionally up to 2.02 mg L^-1, with concentrations generally higher during the winter.  The concentrations of antibiotics added to food was proportional to the size of the site, whereas those given at times of disease were much more variable.  Partitioning coefficients for each antibiotic were calculated and reported; the antibiotics were largely present in the liquid, although significant proportions were adsorbed to solid matrices, with adsorption vary between seasons.

This paper would be of interest to anyone interested in antibiotic resistance, analytical techniques to detect antibiotics and agricultural practices with regard to antibiotic use.  You can download the paper here, free for the next 4 weeks*.

Occurrence and partition of antibiotics in the liquid and solid phases of swine wastewater from concentrated animal feeding operations in Shandong Province, China
Weiwei Ben ,  Xun Pan and Zhimin Qiang
DOI: 10.1039/C3EM30845F

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

An extensive study by Gonzalez et al. investigating persistent organic pollutants (POPs) in the Argentinian Quequ´en Grande River watershed has emphasised the importance of analysing multiple matrices to gain a fuller picture of the contamination within an environment.

The group sampled water, suspended particulate material, fish muscle, local soil, plant roots, stems and leaves and river sediments.  Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers were analysed by GC-ECD, in addition isotherm studies were carried out on the compounds.  PCA was carried out as part of the statistical analysis to determine patterns and groupings within the data.

In brief, the study is able to compare not only relative concentrations between the different types of pollutants but also differences in persistence and preferential degradation pathways in differing soil types.  Water samples, perhaps unsurprisingly, were more subject to variation depending on how recent any of the compounds had been applied locally. Roots were found to contain more than aerial parts of the plants and fish muscle was found to contain levels of all pollutants targeted, however at levels which were not deemed a risk to human health. 

This is an extensive study which incorporates a variety of matrices across an entire watershed and provides information on transformation and distribution of POPs within the catchment.  This paper would be of interest to anyone working in the fields of environmental sampling, water pollution, modelling or persistent pollutants.

Organic pollutant levels in an agricultural watershed: the importance of analyzing multiple matrices for assessing streamwater pollution
Mariana Gonzalez, Karina S. B. Miglioranza, Sebastián I. Grondona, Maria Florencia Silva Barni, Daniel E. Martinez and Aránzazu Peña
DOI: 10.1039/C3EM30882K

Collaborators at Eawag, the University of Basel, ETH Zurich and University of Zurich have come together to develop a faster, portable way to take sediment samples, extract porewater and analyse it in under 15 minutes.

Led by Beat Muller, the researchers combine a portable capillary electrophoresis instrument with MicroRhizon samplers in this Environmental Science :Processes & Impacts paper.

MicroRhizon samplers are made of chemically inert microporous tubing connected to a syringe and are inexpensive, portable and simple to use. The difficulty in analysis is that only a small sample volume is collected, extra handling and sample preparation is required and there is a risk of contamination in transferring the sample for analysis.

The previously developed portable capillary electrophoresis device with contactless conductivity detection eliminates these concerns as it enables sensitive detection of ionic compounds in the field immediately after sampling.

In this article, the team applies this combination to porewater sampling and analysis, giving high spatial resolution.

The method is validated by sampling of sediment from a eutrophic lake, comparing the results to those from ion chromatography. They successfully separate out major inorganic ionic compounds in under 15 minutes. The disturbance of the sediment samples is minimal and zero-oxygen conditions were maintained without difficulty. No splitting, acidification or dilution of the sample is necessary.

Such speedy porewater analysis will be beneficial for the study of oxidizing agents and nutrients in organic matter. Read the full article here as it’s now free to access for the next 4 weeks*

Sediment porewater extraction and analysis combining filter tube samplers and capillary electrophoresis
Natascha T. Torres, Peter C. Hauser, Gerhard Furrer, Helmut Brandl and Beat Müller
DOI: 10.1039/C3EM00068K

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

Reported removal efficiencies of micropollutants at wastewater treatment plants vary a great deal for the same substance, with negative removal efficiencies even being reported and simply averaged out.

Often, to reduce cost and effort, sampling studies are very short at one to two days. The efficiency is then based on a calculation of mass balancing the sample loads in influent and effluent, using the flawed assumptions that the volume of each is equal and that micropollutant concentrations are in steady-state conditions at all times.

Researchers at the Resource Center for Environmental Technologies in Luxembourg saw this need to systematically examine this method and the accuracy of it with regard to the sampling method and conditions. This HOT article describes the application of hydraulic modeling to match up the influent and effluent loads, reducing uncertainties.

Hydraulic residence times are often used in chemical engineering but not in evaluation of wastewater treatment sampling. In previous modeling work, the team has concluded that the load carried by an effluent sample taken over the course of one day is made up of influent load from the days before. This study takes this and attempts to calculate how much of one day’s micropollutant influent load ends up in a day’s effluent sample. The number of influent sampling days was gradually increased until 80% of the effluent sample was accounted for.

They provide a model that can be adapted for use in other wastewater treatment plants and recommend best practice for taking inevitable errors ranges into account. This article is free to access for the next 4 weeks* so you can read it now at:

A case-study on the accuracy of mass balances for xenobiotics in full-scale wastewater treatment plants
Marius Majewsky, Julien Farlin, Michael Bayerle and Tom Gallé
DOI: 10.1039/C3EM30884G

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

Julie Fox et al. tackle the problem of how different studies of exhaled breath condensate (EBC) sampling can be directly compared in this HOT article dedicated to the late Dr Alison Geyh. This requires standardisation of the method and equipment used, which are both highly dependent on the nature of the biomarker being assessed and the population studied.

The group concentrate on the assessment of metals, as elemental biomarkers that are not affected by degradation through the analysis process. The researchers based at University of Washington, Johns Hopkins Bloomeberg School of Public Health and ICF International, USA, incorporated a number of quality control aspects meaning the method can be used for different EBC sample types.

The instrument used was the commercially available Rtube, with a polypropylene condensing surface and an aluminium sleeve that is chilled to condense the EBC. This is a cheaper, more portable option with no temperature control during sampling. They add a spirometer for recording ventilation and subjects were trained to use a visual incentive spirometer to keep their breathing consistent during sampling. A HEPA filter reduces exposure to airborne particles and the modified Rtube is also able to connect up to a temperature-controlled device, the EcoVent, as needed.

The found that is vital to evaluate any possible sources of contamination prior to the experiment. The group measured a number of collection parameters and recommend detailed description of these for all experiments.

The method was validated by measurements of Mn, Cd, Ni and Cr in an unexposed population on a small scale, with a focus on Mn. Wider conclusions about the general population cannot be made from this small study, however this HOT article presents a methodology and protocol recommendations for future EBC studies that is portable, economical and widely applicable.

This article is now free to access for the next 4 weeks*, so you can read the detail of the parameters measured and the example study now:

Characterization of a portable method for the collection of exhaled breath condensate and subsequent analysis of metal content
Julie R. Fox, Ernst W. Spannhake, Kristin K. Macri, Christine M. Torrey, Jana N. Mihalic, Sorina E. Eftim, Peter S. J. Lees and Alison S. Geyh
DOI: 10.1039/C3EM30906A

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