Water quality guidelines for chemicals: learning lessons to deliver meaningful environmental metrics

Many jurisdictions around the globe have well-developed regulatory frameworks for the derivation and implementation of water quality guidelines (WQGs) or their equivalent (e.g. environmental quality standards, criteria, objectives or limits). However, a great many more still do not have such frameworks and are looking to introduce practical methods to manage chemical exposures in aquatic ecosystems. There is a potential opportunity for learning and sharing of data and information between experts from different jurisdictions in order to deliver efficient and effective methods to manage potential aquatic risks, including the considerable reduction in the need for aquatic toxicity testing and the rapid identification of common challenges. This paper reports the outputs of an international workshop with representatives from 14 countries held in Hong Kong in December 2011. The aim of the workshop and this paper was to identify ‘good practice’ in the development of WQGs to deliver to a range of environmental management goals. However, it is important to broaden this consideration to cover often overlooked facets of implementable WQGs, such as demonstrable field validation (i.e. does the WQG protect what it is supposed to?), fit for purpose of monitoring frameworks (often an on-going cost) and finally how are these monitoring data used to support management decisions in a manner that is transparent and understandable to stakeholders. It is clear that regulators and the regulated community have numerous pressures and constraints on their resources. Therefore, the final section of this paper addresses potential areas of collaboration and harmonisation. Such approaches could deliver a consistent foundation from which to assess potential chemical aquatic risks, including, for example, the adoption of bioavailability-based approaches for metals, whilst reducing administrative and technical burdens in jurisdictions.     

Electrochemical treatment of domestic wastewater using boron-doped diamond and nanostructured amorphous carbon electrodes

The performance of the electrochemical oxidation process for efficient treatment of domestic wastewater loaded with organic matter was studied. The process was firstly evaluated in terms of its capability of producing an oxidant agent (H₂O₂) using amorphous carbon (or carbon felt) as cathode, whereas Ti/BDD electrode was used as anode. Relatively high concentrations of H₂O₂ (0.064 mM) was produced after 90 min of electrolysis time, at 4.0 A of current intensity and using amorphous carbon at the cathode. Factorial design and central composite design methodologies were successively used to define the optimal operating conditions to reach maximum removal of chemical oxygen demand (COD) and color. Current intensity and electrolysis time were found to influence the removal of COD and color. The contribution of current intensity on the removal of COD and color was around 59.1 and 58.8 %, respectively, whereas the contribution of treatment time on the removal of COD and color was around 23.2 and 22.9 %, respectively. The electrochemical treatment applied under 3.0 A of current intensity, during 120 min of electrolysis time and using Ti/BDD as anode, was found to be the optimal operating condition in terms of cost/effectiveness. Under these optimal conditions, the average removal rates of COD and color were 78.9?±?2 and 85.5?±?2 %, whereas 70 % of total organic carbon removal was achieved.     

TiO2/β-SiC foam-structured photoreactor for continuous wastewater treatment

Introduction

This study of photocatalytic degradation of wastewater was carried out in alveolar cell ??-SiC foam-structured photocatalytic reactors working in a recirculation mode. The immobilization of TiO2 on ??-SiC foams was efficiently obtained through a sol?Cgel technique in acidic conditions.

Discussion

In order to optimize degradation yields obtained by the foam-structured prototype reactor for the photocatalytic water treatment, the operating conditions of the photoreactor have been investigated and the efficiency of the process was evaluated by measuring the photocatalytic degradation of Diuron (3-(3,4-dichlorophenyl)-1,1-dimethyl-urea)) under UV irradiation. Kinetic studies were carried out by investigating the influence of different parameters controlling the reaction (TiO2 loading and ??-SiC foam cell size). The ageing of TiO2/??-SiC foam photocatalytic materials and the mineralization (TOC, Cl?, NO3? and NH4+) of Diuron were investigated.     

Researching Visual Representations of Climate Change

This paper responds to calls for greater clarity about the application of theory and method in research on mediated communication about climate-change. Specifically, it identifies conceptual and methodological challenges for researching visual representations of climate change. We suggest current research is impeded by a lack of methodological explication and an unclear relationship between theories of visual meaning and the application of social science methods such as content analysis and frame analysis. As a first step towards addressing these issues, we review existing research to identify the methodological procedures that require explication in order to support the replication of studies and the comparison of findings. We then draw on the seminal work of Roland Barthes to examine how theories of visual meaning may be integrated into social-scientific research methods. Specifically, we demonstrate how Barthes’ concepts of denotation, connotation and mythology may be related to research concerns about the selection of visual content, the classification of image frames, audience responses, and analyses of ideological meaning. The conclusion highlights further possibilities for developing a robust form of visual analysis that meets the standards of social scientific research while addressing the fundamental insights about visual meaning derived from cultural theories of meaning.     

Outdoor tobacco smoke exposure at the perimeter of a tobacco-free university

There are few studies measuring exposure to outdoor tobacco smoke (OTS). Tobacco users often gather at the boundaries of tobacco-free campuses, resulting in unintended consequences. The objective of this study was to measure exposure levels from OTS on sidewalks bordering a tobacco-free university campus. Data were collected while walking along a sidewalk adjacent to a medium traffic road between May and August 2011. Monitoring occurred during “background,” “stop,” and “walk-through” conditions at and near hot spot area to measure fine particulate matter (<2.5 μm; PM_2.5) from OTS using a portable aerosol monitor. The average PM_2.5 levels during stop and walk-through conditions were significantly higher than during background conditions. PM_2.5 peak occurrence rate and magnitude of peak concentration were significantly different depending on smoking occurrence. The peak occurrence rate during the stop condition was 10.4 times higher than during the background condition, and 3.1 times higher than during the walk-through condition. Average peak PM_2.5 concentrations during the stop condition were 48.7% higher than during the background condition. In conclusion, individuals could be exposed to high levels of PM_2.5 when stopping or even passing by smokers outdoors at the perimeter of tobacco-free campuses. The design and implementation of tobacco-free campus policies need to take into account the unintended consequences of OTS exposure at the boundaries.

Implications:In this study, outdoor tobacco smoke (OTS) exposure was measured at the perimeter of tobacco-free campus. OTS exposure could be determined by peak analysis. Peak occurrence rate and peak concentration for OTS exposure were identified by using peak analysis. People could be exposed to high levels of PM_2.5 when standing or even passing by smokers at the perimeter of tobacco-free campus. OTS exposure measurement in other outdoor locations with smokers is needed to support outdoor smoking regulation.     

Estimation of Economic Losses to the Agricultural Sector from Airborne Residuals in the Ohio River Basin Region

This paper reports the results of research conducted for the U.S. Environmental Protection Agency in connection with the Ohio River Basin Energy Study (U.S.-EPA Grant No. 805585, Subcontract No. R805588). The purpose of the research is to estimate monetary losses to agricultural producers in the study region from airborne residuals. Estimates of physical crop losses were provided under the direction of Dr. Orie Loucks at The Institute of Ecology and were used for estimating the related monetary losses. Economic losses are defined as producer surplus losses to the agricultural sector due to reductions in productivity from airborne residuals. Research results support the following general conclusions; monetary losses to agricultural producers in the region are on the order of 12% of the present discounted value of clean air production through the year 2000. Losses from utilities alone are on the order of 4.8%. Losses are highly concentrated in the ORBES portions of Illinois, Indiana, and Ohio and primarily related to soybean and corn production. The overwhelming monetary losses are attributable to O₃ concentrations in the region. Compliance and noncompliance with state implementation plans (SIP) does not significantly change the degree of monetary losses. Only high growth in electric demand produces annual losses which rise to the year 2000 and produces significantly greater losses among alternative scenarios.     

Measurement of Hydrocarbon Emissions Fluxes from Refinery Wastewater Impoundments Using Atmospheric Tracer Techniques

Sulfur hexafluoride (SF6) tracer was used in a series of the experiments to simulate emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX) from a refinery wastewater basin. The ratio of the measured tracer release to the ambient tracer concentration established a dilution factor which was then used to calculate the mass flux of BTEX from the wastewater basin using the ambient BTEX concentration data. Measured fluxes of BTEX varied from 7 g/min to 70 g/min.

The CHEMDAT7 air emissions model was then used to predict emissions for comparison with the emissions measured using the tracer flux simulation. CHEMDAT7 typically overpredicted total measured BTEX emissions by factors of twelve to seventeen. The degree of overprediction varied both by the individual compound and the module of CHEMDAT7 used to predict emission fluxes.     

Influence of photolysis on multispectral photoacoustic measurement of nitrogen dioxide concentration

Multispectral photoacoustic instruments are commonly used to measure aerosol and nitrogen dioxide (NO₂) light absorption coefficients to determine the radiation budget of the atmosphere. Here a new photoacoustic system is developed to explore the effect of photolysis on the measured signal in a multispectral photoacoustic spectrometer. In this system, a 405-nm laser is used primarily as light source for photolysis. Additionally, a well-overlapped 532-nm laser, modulated at the resonant frequency of the photoacoustic instrument, is used to probe the NO₂ concentration. As a result, the photolysis effect at 405 nm can be observed by the photoacoustic instrument through the 532-nm laser. This work determines an 11% reduction of the photoacoustic signal caused by the photolysis effect for typical conditions, which needs to be taken into account when calibrating multispectral photoacoustic spectrometers with NO₂.

Implications: Multispectral photoacoustic instruments are commonly used to measure aerosol and nitrogen dioxide (NO₂) light absorption coefficients to determine the radiation budget of the atmosphere. A 405-nm laser is often used in these multispectral photoacoustic instruments. Although NO₂ absorbs strongly at 405 nm, it also has a strong photolysis pathway that is accessible by light of the same wavelength. Photolysis reduces the photoacoustic signal, necessitating special care when interpreting photoacoustic measurements. This paper offers a method for the multispectral photoacoustic instrument user to quantify the influence of the 405-nm NO₂ photolysis effect on the photoacoustic signal.     

Delineating landfill leachate discharge to an arsenic contaminated waterway

Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.     

Groundwater quality assessment of one former industrial site in Belgium using a TRIAD-like approach

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and assess pollution-induced degradation due to contaminated groundwater was carried out in this study. The new concept, referred to as “Groundwater Quality TRIAD-like” (GwQT) approach, is adapted from classical TRIAD approaches. GwQT is based on measurements of chemical concentrations, laboratory toxicity tests and physico-chemical analyses. These components are combined in the GwQT using qualitative and quantitative (using zero to one subindices) integration approaches. The TRIAD approach is applied for the first time on groundwater from one former industrial site located in Belgium. This approach will allow the classification of sites into categories according to the degree of contaminant-induced degradation. This new concept is a starting point for groundwater characterization and is open for improvement and adjustment.