Multiple-year black carbon measurements and source apportionment using Delta-C in Rochester,New York

Black carbon (BC), an important component of the atmospheric aerosol, has climatic, environmental, and human health significance. In this study, BC was continuously measured using a two-wavelength aethalometer (370 nm and 880 nm) in Rochester, New York, from January 2007 to December 2010. The monitoring site is adjacent to two major urban highways (I-490 and I-590), where 14% to 21% of the total traffic was heavy-duty diesel vehicles. The annual average BC concentrations were 0.76 μg/m³, 0.67 μg/m³, 0.60 μg/m³, and 0.52 μg/m³ in 2007, 2008, 2009, and 2010, respectively. Positive matrix factorization (PMF) modeling was performed using PM_2.5 elements, sulfate, nitrate, ammonia, elemental carbon (EC), and organic carbon (OC) data from the U.S. Environmental Protection Agency (EPA) speciation network and Delta-C (UVBC_370nm – BC_880nm) data. Delta-C has been previously shown to be a tracer of wood combustion factor. It was used as an input variable in source apportionment models for the first time in this study and was found to play an important role in separating traffic (especially diesel) emissions from wood combustion emissions. The result showed the annual average PM_2.5 concentrations apportioned to diesel emissions in 2007, 2008, 2009, and 2010 were 1.34 μg/m³, 1.25 μg/m³, 1.13 μg/m³, and 0.97 μg/m³, respectively. The BC conditional probability function (CPF) plots show a large contribution from the highway diesel traffic to elevated BC concentrations. The measurements and modeling results suggest an impact of the U.S Environmental Protection Agency (EPA) 2007 Heavy-Duty Highway Rule on the decrease of BC and PM_2.5 concentrations during the study period.

Implications: This study suggests that there was an observable impact of the U.S EPA 2007 Heavy-Duty Highway Rule on the ambient black carbon concentrations in Rochester, New York. Aethalometer Delta-C was used as an input variable in source apportionment models and it allowed the separation of traffic (especially diesel) emissions from wood combustion emissions.     

Comparison between lab- and full-scale applications of in situ aeration of an old landfill and assessment of long-term emission development after completion

Sustainable landfilling has become a fundamental objective in many modern waste management concepts. In this context, the in situ aeration of landfills has been recognised for its potential to convert conventional anaerobic landfills into biological stabilised state, whereby both current and potential (long-term) emissions of the landfilled waste are mitigated. In recent years, different in situ aeration concepts have been successfully applied in Europe, North America and Asia, all pursuing different objectives and strategies.In Austria, the first full-scale application of in situ landfill aeration by means of low pressure air injection and simultaneous off-gas collection and treatment was implemented on an old, small municipal solid waste (MSW) landfill (2.6 ha) in autumn 2007. Complementary laboratory investigations were conducted with waste samples taken from the landfill site in order to provide more information on the transferability of the results from lab- to full-scale aeration measures. In addition, long-term emission development of the stabilised waste after aeration completion was assessed in an ongoing laboratory experiment. Although the initial waste material was described as mostly stable in terms of the biological parameters gas generation potential over 21 days (GP₂₁) and respiration activity over 4 days (RA₄), the lab-scale experiments indicated that aeration, which led to a significant improvement of leachate quality, was accompanied by further measurable changes in the solid waste material under optimised conditions. Even 75 weeks after aeration completion the leachate, as well as gaseous emissions from the stabilised waste material, remained low and stayed below the authorised Austrian discharge limits. However, the application of in situ aeration at the investigated landfill is a factor 10 behind the lab-based predictions after 3 years of operation, mainly due to technical limitations in the full-scale operation (e.g. high air flow resistivity due to high water content of waste and temporarily high water levels within the landfill; limited efficiency of the aeration wells). In addition, material preparation (e.g. sieving, sorting and homogenisation) prior to the emplacement in Landfill Simulation Reactors (LSRs) must be considered when transferring results from lab- to full-scale application.     

When workplace safety depends on behavior change: Topics for behavioral safety research

Introduction

Comprehensive interventions that address public-health concerns invariably include behavior-change strategies. In occupational safety and health, behavioral safety is an approach designed to improve safety performance directly through peer observations of safe behaviors, goal setting, performance feedback, and celebrations or incentives for reaching safety goals. Although the basic components of behavioral safety processes have been studied and widely documented, the current safety literature reveals several gaps in knowledge. These gaps are associated mostly with wide practice variations among the common process elements and uncertainty about the influence of organizational and other external factors.

Impact to Industry

A major objective of this paper was to highlight not only key topic areas that warrant further research, but also to propose a list of research questions that are tied to uncertainties about various intervention practices. If only a portion of these topic areas and research questions are addressed through systematic reviews, field interventions, surveys, and laboratory-based studies, then the knowledge gained will significantly improve the delivery and effectiveness of behavioral safety interventions and thus their impact on worker health and safety.     

Investigations into the transport and pathways of scallop larvae--the use of numerical models for managing fish stocks

The scallop fisheries off the southeast coast of Ireland have historically been considered a valuable resource for coastal communities, and hence their management is important. The scallop fishing grounds consist of a number of scallop beds dispersed throughout the St George's Channel and the southern Irish Sea. The boundaries between stocks and the interconnection in populations of adult scallops, through larval transport, is generally unknown. Until the time of this research, the stocks of scallop in this region had not been assessed. A research project was undertaken to develop novel, spatially explicit and multi-disciplinary approaches to the assessment of the scallop fisheries in the region. The project supported research in three related areas under the broad objective of developing stock assessment protocols and methods in order to promote sustainable management of these fisheries. One of these areas was the development and application of numerical models. The objectives of this modelling research were: (a) to reconstruct the physical environment of the study area; (b) investigate how this environment affects the demographics and nature of scallop; and (c) determine migration-transport pathways of the scallop larvae. From these investigations, light is shed on how the spatial variability in certain parameters of the natural environment determine habitats and the scallop populations. Also, the investigations now enable determinations to be made on the interconnectivities of 'disparate' scallop beds and where larvae are, in general, likely to be found. Thus, through the use of complex computer models, important clues are deduced that enable us to now understand key behavioural components of scallop larvae and their transport pathways. The analysis of these clues is assisting the development of protocols for managing the fish stock in a sustainable manner.     

Spatial and temporal variability of water repellency in a sandy soil contaminated with tar oil and heavy metals

Water repellency can induce preferential flow and thus affect water flow and contaminant transport at hazardous waste sites. Since the spatial patterns of water repellency are mostly unknown, it is problematic to use numerical transport models to predict leachate composition. In this study, the spatial variability of soil water repellency was studied at an industrial site contaminated with tar oil, chromium, copper and arsenic. The persistence of water repellency was assessed by the water drop penetration time (WDPT), and the degree of water repellency was quantified by the ethanol percentage (EP) test. Measurements were made at the soil surface along 3.5-12.1 m long transects at different times between March and October 2002. The spatial variability of WDPT, EP, water content, and organic matter content was quantified by variogram analyses. Both the persistence and the degree of water repellency varied seasonally, with the highest water repellency during the summer months. The correlation lengths of WDPT values ranged between 16 and 406 cm, whereas EP values showed no spatial correlation. For field-moist samples, a critical soil water threshold, below which water repellency prevails, was estimated to be 2.5-4%. For oven dry samples, the WDPT values were dependent on the water content prior to drying. The wide range of correlation lengths and the temporal dynamics of spatial repellency patterns suggest that simulations of solute leaching must consider the spatial and temporal variability of soil hydrophobic properties.     

Titration Curves: A Useful Instrument for Assessing the Buffer Systems of Acidic Mining Waters (10 pp)

Background, Aims and Scope The acidification of mine waters is generally caused by metal sulfide oxidation, related to mining activities. These waters are characterized by low pH and high acidity due to strong buffering systems. The standard acidity parameter, the Base Neutralization Capacity (BNC) is determined by endpoint titration, and reflects a cumulative parameter of both hydrogen ions and all buffering systems, but does not give information on the individual buffer systems. We demonstrate that a detailed interpretation of titration curves can provide information about the strength of the buffering systems. The buffering systems are of importance for environmental studies and treatment of acidic mining waters. Methods Titrations were carried out by means of an automatic titrator using acidic mining waters from Germany and Canada. The curves were interpreted, compared with each other, to endpoint titration results and to elemental concentrations contained therein. Results and Discussion The titration curves were highly reproducible, and contained information about the strength of the buffer systems present. Interpretations are given, and the classification and comparison of acidic mining waters, by the nature and strength of their buffering systems derived from titration curves are discussed. The BNC-values calculated from the curves were more precise than the ones determined by the standard endpoint titration method. Due to the complex buffer mechanisms in acidic mining waters, the calculation of major metal concentrations from the shape of the titration curve resulted in estimates, which should not be confused with precise elemental analysis results. Conclusion Titration curves provide an inexpensive, valuable and versatile tool, by which to obtain sophisticated information of the acidity in acidic water. The information about the strength of the present buffer systems can help to understand and document the complex nature of acidic mining water buffer systems. Finally, the interpretation of titration curves could help to improve treatment measurements and the ecological understanding of these acidic waters.