Coupling surfactants/cosolvents with oxidants for enhanced DNAPL removal: A review

Surfactants and cosolvents are useful for enhancing the apparent solubility of dense nonaqueous‐phase liquid (DNAPL) compounds during surfactant‐enhanced aquifer remediation (SEAR). In situ chemical oxidation (ISCO) with permanganate, persulfate, and catalyzed hydrogen peroxide has proven to be a cost‐effective and viable remediation technology for the treatment of a wide range of organic contaminants. Coupling compatible remedial technologies either concurrently or sequentially in a treatment train is an emerging concept for more effective cleanup of DNAPL‐contaminated sites. Surfactants are effective for DNAPL mass removal but not useful for dissolved plume treatment. ISCO is effective for plume control and treatment but can be less effective in areas where large masses of DNAPL are present. Therefore, coupling SEAR with ISCO is a logical next step for source‐zone treatment. This article provides a critical review of peer‐reviewed scientific literature, nonreviewed professional journals, and conference proceedings where surfactants/cosolvents and oxidants have been utilized, either concurrently or sequentially, for DNAPL mass removal. © 2010 Wiley Periodicals, Inc.     

Development of a field method for measuring manganese in welding fume

Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(ii) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 microg filter(-1) and 17 microg filter(-1), respectively, with a dynamic range up to 400 microg filter(-1). When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.     

Likelihood Ratio Analysis of Skin Cancer Prevalence Associated with Arsenic in Drinking Water in the USA

Several published studies have examined skin-cancer prevalence in regions of the USA that have concentrations of arsenic above the USA drinking-water standard. Those studies with adequate exposure and health outcome data did not report any skin cancer cases. Because the USA's arsenic concentrations are relatively low compared to some other countries and the study populations are small, the absence of reported skin-cancer cases could be due to an absence of risk in USA populations or random variability from a predicted risk. We used the current EPA arsenic cancer slope factor (CSF) model, which is derived from Taiwanese populations exposed to high levels of arsenic, to predict the expected number of skin cancers. We then conducted a likelihood ratio analysis, which showed that a null hypothesis (no additional skin cancer risk from arsenic) was approximately 2.2 times more likely than the hypothesis that ingested arsenic causes the predicted rate of skin cancers. Although based on small numbers, our analysis of USA populations indicates that the CSF derived from arsenic exposure in Taiwanese populations may be an overestimate when applied to USA populations.     

Evaluation of a standardized method for determining soluble silver in workplace air samples

Several occupational exposure limits and guidelines exist for silver, but the values for each depend on the chemical form of the silver compound in question. In the past, it generally was not possible, without prior knowledge of the work process, to distinguish soluble silver from insoluble silver compounds collected in workplace air samples. Therefore, analytical results were historically reported as total silver. In this study, work was conducted to evaluate a method to differentiate between the quantities of water-soluble silver compounds and total silver collected on filters. The investigation entailed an evaluation of an International Organization for Standardization method to determine soluble silver in airborne particulate matter. The study design incorporated laboratory experiments to evaluate analytical figures of merit, such as selection of appropriate filter media and extraction solution, analytical recovery, and sample stability during storage. Polytetrafluoroethylene (PTFE) filters (2 microm, 37 mm) in opaque cassettes were either spiked with known amounts of silver nitrate or contained a known mass of solid silver nitrate. Results showed that over 90% of the silver was recovered from PTFE filters. Also, field studies were conducted in which workplace air samples were collected in two silver refineries. Some of these samples were analyzed only for soluble silver while others were sequentially extracted and analyzed, first, for soluble silver, then for total silver. The mass fractions of soluble silver, as compared to total silver, were approximately 2% or less. This investigation served to validate an international standard procedure for the determination of soluble silver in workplace air samples.     

Recent advances on elemental biosorption

Environmental Chemistry Letters - Industrial activities play a relevant role in environmental pollution since their wastes contain high concentrations of toxic elements that can add significant...     

Mental health and media links based on five essential elements to promote psychosocial support for victims: the case of the earthquake in Chile in 2010

This paper reviews the role of news with respect to the mental health of a population exposed to a disaster. It is based on the five essential elements of psychosocial care presented by Stevan E. Hobfoll et al. (2007) that can be introduced after a potentially traumatic event: promoting a sense of safety, calming, self and collective efficacy, connectedness, and hope. This study developed a method to relate these elements to television coverage and applied it to the stories (n=1,169) aired by the main networks in Chile in the 72 hours after an 8.8 magnitude earthquake struck on 27 February 2010. Of the five elements, promoting a sense of safety occurred most often (82.72 per cent), whereas the others were barely present (less than 10 per cent). The study argues that these elements can increase the possibility of framing the news, given that the audience watching can also be affected by a disaster.     

Developing a passion for work passion: Future directions on an emerging construct

Although the passion that people demonstrate at work would appear to be a topic of considerable interest and importance to organizational scholars and practitioners, we know virtually nothing about it. In response, we introduce the work passion construct, discuss what we currently understand, and provide needed directions for future research. Copyright © 2013 John Wiley & Sons, Ltd.     

Assessing vulnerability to sea-level rise using a coastal sensitivity index: a case study from southeast Australia

Many of the world’s coasts appear vulnerable to the impacts of climate change and sea-level rise. This paper assesses the application of a coastal sensitivity index (CSI) to the Illawarra coast, a relatively well-studied shoreline in southeast Australia. Nine variables, namely (a) rock type, (b) coastal slope (c) geomorphology (d) barrier type (e) shoreline exposure (f) shoreline change (g) relative sea-level rise (h) mean wave height and (j) mean tide range, were adopted in calculation of the CSI (the square root of the product of the ranked variables divided by the number of variables). Two new variables, shoreline exposure and barrier type, were trialled in this analysis and the extent to which these increased the discriminatory power of the index was assessed. Four iterations of the CSI were undertaken using different combinations of ranked variables for each of 105 cells in a grid template, and the index values derived were displayed based on quartiles, indicating sections of coast with very high, high, moderate and low sensitivity. Increasing the number of variables increased the discriminatory power of the index, but the broad pattern and the rank order were very similar for each of the iterations. Rocky and cliffed sections of coast are least sensitive whereas sandy beaches backed by low plains or dunes record the highest sensitivity. It is difficult to determine shoreline change on this coast, because individual storms result in substantial erosion of beaches, but there are prolonged subsequent periods of accretion and foredune rebuilding. Consequently this variable is not a good indicator of shoreline sensitivity and the index is unlikely to provide a clear basis for forecasting future recession of beaches. The results of this study provide a framework for coastal managers and planners to prioritize efforts to enhance the resilience or consider adaptation measures in the coastal zone within a study region. Sensitivity of the coast if considered in conjunction with other social factors may be an input into broader assessments of the overall vulnerability of coasts and their communities.     

Assessing the micro-phytoplankton response to nitrate in Comau Fjord (42°S) in Patagonia (Chile), using a microcosms approach

Anthropogenic (aquaculture) changes in environment nutrient concentrations may affect phytoplankton (biomass and taxa composition) in marine coastal waters off the Chilean Patagonia. The effects of adding nitrate (NO₃ ^?) to natural phytoplankton assemblages were evaluated considering biomass, cell abundance, and taxonomic composition. Microcosm experiments were performed in the spring, summer, and winter in the Comau Fjord located in Subantarctic Patagonia. At the end of the experiments, NO₃ ^? decreased rapidly and was undetectable in treatments, indicating a strong NO₃ ^? deficiency associated with an exponential increase in Chl-a concentrations, particulate organic nitrogen, and carbon in these treatments. Moreover, given the depleted nitrate concentrations of the spring and summer experiments, the micro-phytoplankton taxa structure shifted from mixed diatom and dinoflagellate assemblages (Ceratium spp., Dinophysis spp., Coscinodiscus sp., Rhizosolenia pungens) to assemblages dominated by blooms of the classic chain-forming diatoms found in temperate and cold waters such as Chaetoceros spp., Skeletonema spp., and Thalassiosira spp. Thus, nitrogen sources (i.e., nitrate, ammonia) may influence phytoplankton abundance and biomass accumulation dynamics in the northern section of Patagonia. It also emphasizes the importance of diatom taxa in regards to the short-term response of phytoplankton to changing environmental nutrient conditions due to natural (decreasing freshwater stream flow) and anthropogenic (aquaculture) events. This situation may be one of the future scenarios in the Patagonian fjords, thus stressing the needs for active environmental monitoring and impact assessment.     

Monitoring fugitive dust emissions from off-highway vehicles traveling on unpaved roads and trails using passive samplers

Vehicles traveling on dry, unpaved roads generate copious quantities fugitive dust that contributes to soil erosion, and potentially threatens human health and ecosystems. The purpose of this study was to develop a low-cost technique for monitoring road dust that would enable land managers to estimate soil loss. The "sticky-trap" collectors developed were evaluated at the Turkey Bay off-highway vehicle (OHV) riding area on the Land Between the Lakes National Recreation Area, in western Kentucky. The results showed that the dust plume created by vehicle traffic was heterogeneous: larger particles were in the lower part of the plume and deposited closer to the source, smaller particles were carried higher in the plume and traveled at least 100 m away from the source. Collection of particles parallel to the source was also heterogeneous, suggesting that measurements taken at a single point may not be appropriate for estimating erosion losses. Measurements taken along two trails indicate that when large numbers of riders are present, dust concentrations may reach unhealthful conditions for riders, but that it is unlikely that fugitive dust is harming native vegetation, given frequent rainfall. The study demonstrated that OHV traffic contributes to substantial erosion of roadbeds because of aeolian transport.