A hierarchical approach for desertification assessment

Environmental systems are complex and multi-scaled open systems. To understand land degradation, one has to consider the interactions between landscape patterns and environmental processes at different scales. Patterns and processes in the landscape are perceived to be organized in nested hierarchical structures. To study land degradation in this context, a coupled top-bottom/bottom-up approach was developed. The top-bottom landscape analysis is aimed at identifying landscape systems at different scales. The bottom-up analysis focuses on system dynamics at finer scales. Applied in a study in central Spain, the approach is aimed at understanding the functional differences between three types of degraded seminatural slopes at different scales. Six levels of organization were distinguished: ped-level, terracette-level, hummock-level, slope part-level, slope level, and watershed level. Properties that characterize these levels were selected for different disciplines. The bottom-up analysis focused on water movement at different spatial scales. Successfully applying this approach revealed the importance for land degradation of the close linkage between spatial patterns and hydrological processes at different spatial scales. Identifying constraining and dynamic indicators related to water conservation at different scales can be useful for assessing desertification.     

Bioremediation assessment of diesel–biodiesel-contaminated soil using an alternative bioaugmentation strategy

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO₂ evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.     

Antimicrobial Activity of the Chitosan Extracted from Metapenaeus stebbingi Shell Wastes

In the study, chitosan chemically extracted from Metapenaeus stebbingi shells obtained from shrimp processing factories and commercial chitosan were used as antimicrobial materials. Antimicrobial activities of the chitosans dissolved in acetic, lactic, formic and hydrochloric acid at different concentrations (1.00, 0.50, 0.25, 0.10 and 0.05%) were tested in vitro by using the disk diffusion method with standard microorganisms (Pseudomonas putida, Pseudomonas fluorescens, Vibrio parahaemolyticus, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli 1, Escherichia coli 2, Listeria monocytogenes, Enterecoccus faecalis, Aeromonas caviae). On the other hand, gentamicin was used as positive control. Antimicrobial test results indicated that chitosan demonstrated different effects depending on the chitosan concentration, solvent material and bacteria type. In the present study, both the extracted and commercial chitosans were observed to have antimicrobial effects on nearly all types of the bacteria.     

Narrow stack emissions: Errors in flow rate measurement due to disturbances and swirl

ABSTRACT

European legislation continues to drive down emission limit values, making the emission measurement of narrow stacks of increasing importance. However, the applicable standards (EN ISO 16911–1 and EN 15259) are poorly validated for narrow stacks, and the effect of flow disturbances on the described methods are largely unknown. In this article, measurement errors are investigated in narrow stacks with flow disturbances and swirl, both experimentally and through computational fluid dynamics (CFD) simulations. The results indicate that measurement errors due to misalignment of the flow with typical measuring probes (pitot tubes) are small compared to errors resulting from the positioning of these probes in the measurement plane. Errors up to 15% are reported using the standardized methods, while the measurement error is both smaller and more predictable when using additional measurement points.

Implications: Current international standards provide methods to measure emissions from industrial stacks. With increasingly small emission limit values, the accuracy of these measurements is becoming considerably more important. The data from this study can be used to inform revisions of these standards, in particular with respect to flow disturbances in narrow stacks, and can help law- and policy-makers to obtain insight into the uncertainties of emission measurements in these specific situations.     

Spatial distribution of potentially bioavailable metals in surface soils of a contaminated sports ground in Galway, Ireland

Assessing the environmental risk of metal contamination in soils requires the determination of both total (TCs) and bioavailable (BCs) element concentrations. A total of 200 surface (0–10 cm) soil samples were collected from an urban sports ground (South Park) in Galway, Ireland, a former landfill and dumping site, which is currently under remediation. The potential BCs of metals were measured using ethylene-diamine-tetra-acetic acid (EDTA) extraction followed by inductively coupled plasma-optical emission spectrometry analysis, while the TCs were determined using portable X-ray fluorescence spectrometry. It was found that Zn was primarily present in the insoluble residue (EDTA un-extractable) fraction in soils, with the median ratio of BCs/TCs 0.27. However, Pb and Cu had higher ratios of BCs/TCs (median values of 0.60 and 0.39, respectively) suggesting that they are potentially more bioavailable in the soils. The spatial distribution maps showed that both TCs and BCs for Cu, Pb and Zn in the study area were spatially heterogeneous. It was found that the BCs exhibited generally similar spatial patterns as their TCs of Cu, Pb and Zn: high values were mainly located in the west, north-east and south-east portions of the study area, where only a thin layer of topsoil existed. It was recommended that the current remediation action for this site needs to be carried out on an urgent basis.     

Removing nitric oxide from flue gas using iron(II) citrate chelate absorption with microbial regeneration

The addition of metal chelates such as Fe(II)EDTA or Fe(II)Cit to wet flue gas desulfurization systems has been shown to increase the amount of NO(x) absorption from gas streams containing SO(2). This paper attempts to demonstrate the advantage of not only using Fe(II)Cit chelate to absorb nitrogen oxides from flue gas but also the advantage gained from adding microorganisms to the system. Two distinct classes of microorganisms are needed: denitrifying and iron-reducing bacteria. The presence of oxygen in flue gas will affect the absorption efficiency of NO by Fe(II)Cit chelate. The oxidation of Fe(II) can be slowed with the help of bacteria in two ways: bacteria can serve to directly reduce Fe(III) to Fe(II) or they can serve to keep levels of dissolved oxygen in the solution low. As a result, after NO absorption, Fe(II)(Cit)NO will be reduced by denitrifying bacteria to Fe(II)Cit while Fe(III) is reduced by anaerobic bacteria back to Fe(II). Our experiments have shown that the implementation of our protocol allowed for an NO reduction rate constant increase from standard levels of 0.0222-0.100 m Mh(-1) with inlet NO changed from 250 to 1000 ppm. We have also found that total Fe concentration tends to decrease after prolonged periods of operation due to the loss of some Fe to the formation of Fe(OH)(3) that settles together with the sludge at the bottom of bioreactor tank.     

Carbon trading across sources and periods constrained by the Marrakesh Accords

We examine the potential effects on permit prices and abatement costs of four compliance rules governing emissions trade across sources and periods in the Kyoto Protocol: The banking rule that allows excess permits to be used later; the restoration rate rule that penalizes borrowing; the commitment period reserve rule that limits sales; and finally, the suspension rule that restricts borrowing and sales. Our framework is a two-period model where parties may be out of compliance in the Kyoto period, but are assumed to comply at a later time. Under varying assumptions about market power and US participation, we find that the rules may have pronounced effects on individual costs, but overall efficiency is not severely affected.