Critical Review of Environmental Forensic Techniques: Part I

A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a compound, chemical associations with discrete type processes, chemical profiling, degradation models and contaminant transport models. These techniques, however, are rarely challenged or discussed in the literature relative to the scrutiny encountered in environmental litigation. When introduced as scientific evidence, the governing assumptions and quality of the data are critically evaluated and frequently successfully challenged. The purpose of this paper is to review five types of forensic techniques and discuss their merits so that a user can decide which technique, or combination of techniques, is most appropriate for developing the technical portion of a case.     

Critical Review of Environmental Forensic Techniques: Part II

A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a chemical, chemical associations with discrete types of equipment, chemical profiling, degradation models and contaminant transport models. The success of these techniques in environmental litigation and their applicability to a particular fact situation is rarely discussed in the literature. When these techniques are introduced as scientific evidence, their governing assumptions and the adequacy of the underlying data are rigorously scrutinized and often, successfully challenged. The purpose of this paper is to review selected forensic techniques and discuss their merits so that the user can select the technique or combination of techniques most appropriate for the factual elements of the case.     

Critical Review of Environmental Forensic Techniques: Part II

A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a chemical, chemical associations with discrete types of equipment, chemical profiling, degradation models and contaminant transport models. The success of these techniques in environmental litigation and their applicability to a particular fact situation is rarely discussed in the literature. When these techniques are introduced as scientific evidence, their governing assumptions and the adequacy of the underlying data are rigorously scrutinized and often, successfully challenged. The purpose of this paper is to review selected forensic techniques and discuss their merits so that the user can select the technique or combination of techniques most appropriate for the factual elements of the case.     

Application of Forensic Techniques for Age Dating and Source Identification in Environmental Litigation

A multitude of forensic techniques are available for age dating and source identification, including corrosion models for underground storage tanks, the commercial availability of a compound, chemical associations with discrete types of manufacturing processes, chemical profiling, proprietary additives, stable isotope analysis, degradation models, biomarkers and contaminant transport models. The selection and use of these techniques in environmental litigation must be thoroughly understood and applied to be effective as forensic evidence. When introduced as scientific evidence, the governing assumptions and quality of the data are critically evaluated and frequently successfully challenged. The purpose of this paper is to present an overview of commonly used environmental forensic techniques and their possible applications so that a user can decide which technique or combination of methods is most appropriate for their case.     

Roles of physical and chemical properties of activated carbon in the adsorption of lead ions

Elucidation of the roles of chemical and physical properties of activated carbons is an important basis for the systematic development of adsorbents with optimal properties specific for certain applications. Such an understanding has challenged most researchers and this has been attributed with the difficulty in decoupling the effect of chemical and physical properties that characterize activated carbons. This study proposed empirical modeling in resolving the effects of individual carbon properties in lead adsorption. A model based on lead adsorption and carbon properties including total surface area, mean pore size and heteroatom concentrations has been shown to adequately describe the lead adsorption onto activated carbons prepared from bagasse. To support this investigation a series of activated carbons were prepared from bagasse by physical and by chemical activation techniques. The surface chemical properties of the carbons were inferred from carbon pH and heteroatom concentrations. The physical characterizations of the carbons included total surface area by the BET technique and mean pore size measured using the Horvath-Kawazoe equation. Adsorption tests were conducted using a low concentration of lead (5 ppm) and the solution pH was maintained at 1.0 to maintain lead speciation to the un-complexed Pb(2+) ion. The adequacy of the proposed empirical models was statistically assessed. This form of analysis was shown to provide valuable information in tailor making adsorbents and selecting appropriate adsorbents for lead adsorption.     

Detecting Trends Using Spearman's Rank Correlation Coefficient

Spearman's rank correlation coefficient is a useful tool for exploratory data analysis in environmental forensic investigations. In this application it is used to detect monotonic trends in chemical concentration with time or space.     

Detecting Trends Using Spearman's Rank Correlation Coefficient

Spearman's rank correlation coefficient is a useful tool for exploratory data analysis in environmental forensic investigations. In this application it is used to detect monotonic trends in chemical concentration with time or space.     

Investigation,Remediation and Cost Allocation of Contaminants from the Britannia Mine in British Columbia: A Case Study

This case study, from the province of British Columbia, is described to illustrate the use of environmental forensic techniques. The study involves acid rock drainage (ARD) from the Britannia Mine, a mine located in southwestern British Columbia, that has been closed for approximately 25 years and discharges between 4 and 40 million litres of ARD, depending on the time of year into nearby Howe Sound every day. The ARD occurs as an oxidation of sulphide mineralization exposed to air and water. The sources of ARD contamination from this site are copper, aluminium, iron, zinc and manganese. Current copper concentrations discharging from the 4100 Portal Level range from 40 to 100 mg/L. Environmental forensic techniques are applied to describe the origin of the contaminant release, the timing of the release, the distribution of the contamination, finding the responsible parties and allocating remediation costs for cleanup. Other forensic techniques described include the use of geochemistry to determine contaminant degradation.     

State of the Art Report on Multivariate Chemometric Methods in Environmental Forensics

Environmental forensic analysis has evolved significantly from the early days of qualitative chemical fingerprint evaluations. The need for quantitative rigor has made the use of numerical methods critical in identifying and mapping contaminant sources in complex environmental systems. Given multiple contaminant sources, the environmental scientist is faced with the challenge of unraveling the contributions of multiple plumes with overlapping spatial and temporal distributions. The problem may be addressed through a multivariate statistical approach, but there is a mind-boggling array of the available “chemometric” methods. This paper provides an overview of these methods, along with a review of their advantages, disadvantages, and pitfalls. Methods discussed include principal component analysis and several receptor-modeling techniques.     

State of the Art Report on Multivariate Chemometric Methods in Environmental Forensics☆

Environmental forensic analysis has evolved significantly from the early days of qualitative chemical fingerprint evaluations. The need for quantitative rigor has made the use of numerical methods critical in identifying and mapping contaminant sources in complex environmental systems. Given multiple contaminant sources, the environmental scientist is faced with the challenge of unraveling the contributions of multiple plumes with overlapping spatial and temporal distributions. The problem may be addressed through a multivariate statistical approach, but there is a mind-boggling array of the available "chemometric" methods. This paper provides an overview of these methods, along with a review of their advantages, disadvantages, and pitfalls. Methods discussed include principal component analysis and several receptor-modeling techniques.     

Mass conservative,positive definite integrator for atmospheric chemical dynamics

Air quality models compute the transformation of species in the atmosphere undergoing chemical and physical changes. The numerical algorithms used to predict these transformations should obey mass conservation and positive definiteness properties. Among all physical phenomena, the chemical kinetics solver provides the greatest challenge to attain these two properties. In general, most chemical kinetics solvers are mass conservative but not positive definite. In this article, a new numerical algorithm for the computation of chemical kinetics is presented. The integrator is called Split Single Reaction Integrator (SSRI). It is both mass conservative and positive definite. It solves each chemical reaction exactly and uses operator splitting techniques (symmetric split) to combine them into the entire system.The method can be used within a host integrator to fix the negative concentrations while preserving the mass, or it can be used as a standalone integrator that guarantees positive definiteness and mass conservation. Numerical results show that the new integrator, used as a standalone integrator, is second order accurate and stable under large fixed time steps when other conventional integrators are unstable.     

Refining emission rate estimates using a coupled receptor–dispersion modeling approach

Receptor modeling techniques like chemical mass balance are used to attribute pollution levels at a point to different sources. Here we analyze the composition of particulate matter and use the source profiles of sources prevalent in a region to estimate quantitative source contributions. In dispersion modeling on the other hand the emission rates of various sources together with meteorological conditions are used to determine the concentrations levels at a point or in a region. The predictions using these two approaches are often inconsistent. In this work these differences are attributed to errors in emission inventory. Here an algorithm for coupling receptor and dispersion models is proposed to reduce the differences of the two predictions and determine the emission rates accurately. The proposed combined approach helps reconcile the differences arising when the two approaches are used in a stand-alone mode. This work is based on assuming that the models are perfect and uses a model-to-model comparison to illustrate the concept.     

Evolution of Organic Analytical Methods in Environmental Forensic Chemistry

Over the past few decades the development of environmental regulations, advances in analytical chemistry and other scientific disciplines, and increased rigor in quality control procedures have created a new discipline, environmental forensics. The need for analytical methods that determine qualitatively and quantitatively organic compounds in the environment, especially in drinking waters, was recognized in the early 1950s. These methods were developed gradually by the early 1960s. The important tools of gas chromatography and mass spectroscopy that evolved in the 1970s provided the early environmental forensic chemist for the first time with the ability to produce scientifically sound data that was admissible in court. By the 1990s, multivariate statistical techniques became available and accepted, including principal component analysis (PCA) and polytopic vector analysis (PVA). These techniques, coupled with the advancing analytical methods, have enabled forensic investigator tools to evaluate and demonstrate unique attributes of a set of data. Analyses of marker compounds, PCBs, PCDD/Fs and petroleum hydrocarbons are all shown to be potentially valuable in deciphering the source and fate of contamination. This paper shows how advancements in environmental analytical chemistry provide the forensic chemist with tools to assess the source(s) of site contamination.     

Evolution of Organic Analytical Methods in Environmental Forensic Chemistry

Over the past few decades the development of environmental regulations, advances in analytical chemistry and other scientific disciplines, and increased rigor in quality control procedures have created a new discipline, environmental forensics. The need for analytical methods that determine qualitatively and quantitatively organic compounds in the environment, especially in drinking waters, was recognized in the early 1950s. These methods were developed gradually by the early 1960s. The important tools of gas chromatography and mass spectroscopy that evolved in the 1970s provided the early environmental forensic chemist for the first time with the ability to produce scientifically sound data that was admissible in court. By the 1990s, multivariate statistical techniques became available and accepted, including principal component analysis (PCA) and polytopic vector analysis (PVA). These techniques, coupled with the advancing analytical methods, have enabled forensic investigator tools to evaluate and demonstrate unique attributes of a set of data. Analyses of marker compounds, PCBs, PCDD/Fs and petroleum hydrocarbons are all shown to be potentially valuable in deciphering the source and fate of contamination. This paper shows how advancements in environmental analytical chemistry provide the forensic chemist with tools to assess the source(s) of site contamination.     

The ChimERA project: coupling mechanistic exposure and effect models into an integrated platform for ecological risk assessment

Current techniques for the ecological risk assessment of chemical substances are often criticised for their lack of environmental realism, ecological relevance and methodological accuracy. ChimERA is a 3-year project (2013–2016), funded by Cefic’s Long Range Initiative (LRI) that aims to address some of these concerns by developing and testing mechanistic fate and effect models, and coupling of these models into one integrated platform for risk assessment. This paper discusses the backdrop against which this project was initiated and lists its objectives and planned methodology.     

Source diagnostic and weathering indicators of tar balls utilizing acyclic, polycyclic and S-heterocyclic components

This study represents a forensic chemical analysis to define the liability for the coastal bitumens polluting the beaches of the Mediterranean city of Alexandria. Six tar balls collected from several locations along the coast of the city were analyzed for their acyclic and polycyclic hydrocarbons as well as sulfur heterocycles using GC/FID, GC/AED and gas chromatography/mass spectrometry techniques. The analysis of one Egyptian crude oil is also included as a possible source oil. The tar ball samples were at early stages of weathering. Based on the GC traces and biomarker signatures, the tar balls could be genetically different. One sample collected from the Eastern Harbor region appears to be a Bunker C type fuel produced from Egyptian crudes. The refining process has removed the low molecular weight components. On the other hand, the wide n-alkane distribution together with the absence of an unresolved complex mixture suggests that crude oils probably from tank washings, ballast discharges or accident spills from tankers could have contributed significantly to the other tar ball samples. The distribution of source specific hopane and sterane markers revealed that the tar samples probably originate from different oil fields.     

Toxic Trace Elements Associated with Airborne Particulate Matter: A Review

This article provides a concise review of published literature pertaining to sampling and analytical methodologies, aerometric studies, source identification techniques and modeling activities for the elements arsenic, cadmium, nickel, lead, vanadium, zinc, cobalt, chromium, copper, iron, mercury, manganese, selenium and antimony, and their compounds, associated with airborne particulate matter. Sampling techniques discussed include filtration and inertial separation. Analytical methodologies such as atomic absorption and atomic emission spectrometry, neutron activation analysis, and X-ray fluorescence spectrometry are summarized. Data on atmospheric levels of 14 trace elements are presented in summary form from numerous studies in remote, rural and urban areas, and generally indicate that concentrations measured at rural locations are several orders of magnitude lower than those measured for urban areas. Source identification methodologies are discussed in terms of advantages and disadvantages, and various applications are cited for the following categories: size differentiation, enrichment factors, chemical mass balance, and multivariate models. Provided that reliable trace element data are available for both the source and the receptor, chemical mass balance and multivariate methods can account for up to 80 percent of all sources contributing to the observed ambient air concentration. Wet and dry deposition processes are reviewed and environmental measurement data are provided for each element for remote, rural and urban locations. Both wet and dry deposition fluxes need to be considered for trace elements when estimating the total annual amounts of various trace elements deposited at a particular locale. Global cycles and trace element budgets are introduced in the context of the types of models currently in use. Limitations include inadequate global scale surveys of heavy metal concentrations and the lack of knowledge of sources and/or sinks.     

Development of a database for chemical mechanism assignments for volatile organic emissions

The development of a database for making model species assignments when preparing total organic gas (TOG) emissions input for atmospheric models is described. This database currently has assignments of model species for 12 different gas-phase chemical mechanisms for over 1700 chemical compounds and covers over 3000 chemical categories used in five different anthropogenic TOG profile databases or output by two different biogenic emissions models. This involved developing a unified chemical classification system, assigning compounds to mixtures, assigning model species for the mechanisms to the compounds, and making assignments for unknown, unassigned, and nonvolatile mass. The comprehensiveness of the assignments, the contributions of various types of speciation categories to current profile and total emissions data, inconsistencies with existing undocumented model species assignments, and remaining speciation issues and areas of needed work are also discussed. The use of the system to prepare input for SMOKE, the Speciation Tool, and for biogenic models is described in the supplementary materials. The database, associated programs and files, and a users manual are available online at http://www.cert.ucr.edu/~carter/emitdb.

Implications: Assigning air quality model species to the hundreds of emitted chemicals is a necessary link between emissions data and modeling effects of emissions on air quality. This is not easy and makes it difficult to implement new and more chemically detailed mechanisms in models. If done incorrectly, it is similar to errors in emissions speciation or the chemical mechanism used. Nevertheless, making such assignments is often an afterthought in chemical mechanism development and emissions processing, and existing assignments are usually undocumented and have errors and inconsistencies. This work is designed to address some of these problems.     

A new approach for the modelling of chestnut wood photo-degradation monitored by different spectroscopic techniques

The aim of this work is to study the colour and chemical modifications of the surfaces in chestnut wood samples as a consequence of irradiating in a controlled environment. The changes were investigated by a new analytical approach by combining traditional techniques such as reflectance spectrophotometry in the visible range and Fourier transform infrared spectroscopy with new hyperspectral imaging, in order to obtain forecast models to describe the phenomenon. The statistical elaboration of the experimental data allowed to validate the measurements and to obtain models enabling to relate the investigated parameters; the elaboration of the hyperspectral images by chemometric methods allowed for studying the changes in the reflectance spectra. A result of great importance is the possibility to correlate the oxidation of wood chemical components with the colour change in a totally non-invasive modality. This result is particularly relevant in the field of cultural heritage and in general in the control processes of wooden materials.