Kathleen Murphy

Kathleen Murphy
Chalmers University of Technology · Department of Civil and Environmental Engineering

BSc (Hons.), BE (Hons.), PhD (Env. Eng.)

About

68
Publications
66,475
Reads
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5,671
Citations
Introduction
Kathleen Murphy works at the department of Architecture and Civil Engineering (ACE), Chalmers University of Technology. Her research is at the interface of Water Engineering, Analytical Chemistry, and Chemometrics. Her current projects focus on understanding and predicting natural organic matter optical properties and behaviours in aquatic environments (drinking water, freshwater, marine,....) and during water treatment.
Additional affiliations
April 2016 - present
Chalmers University of Technology
Position
  • Docent
July 2014 - present
Chalmers University of Technology
Position
  • Professor (Assistant)
January 2010 - June 2014
UNSW Sydney
Position
  • PostDoc Position

Publications

Publications (68)
Article
Full-text available
An online repository of published organic fluorescence spectra has been developed, which can be searched for quantitative matches with any set of unknown spectra. It fills a critical gap by increasing access to measured and modelled (PARAFAC) spectra, and linking across studies and systems to reveal "global" fluorescence trends. Fluorescence spectr...
Article
Full-text available
Dissolved organic matter (DOM) in aquatic environments forms a vast reservoir of carbon present as a complex super-mixture of compounds. An efficient approach to tracking the production and removal of specific DOM fractions is needed across disciplines, for purposes that range from improving global carbon budgets to optimising water treatment in en...
Article
Full-text available
The spectra responsible for natural dissolved organic matter (DOM) fluorescence in 90 peer-reviewed studies have been compared using new similarity metrics. Numerous spectra cluster in specific wavelength regions. The emerging...
Article
Full-text available
Dissolved organic matter (DOM) is a complex pool of compounds with a key role in the global carbon cycle. To understand its role in natural and engineered systems, efficient approaches are necessary for tracking DOM quality and quantity. Fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) is very widely used to identify and q...
Article
Full-text available
A study was conducted at a water treatment plant to optimize parallel rapid gravity biofilters for dissolved organic matter (DOM) removal. The biofilters treat urban and agriculturally impacted river water using a commercial non-adsorptive, expanded-clay filter medium. The study aimed to locate the optimal operating conditions via experimental mani...
Article
Full-text available
Samples from fifty-five surface water resources and twenty-five drinking water treatment plants in Europe, Africa, Asia, and USA were used to analyse the fluorescence composition of global surface waters and predict aromaticity and treatability from fluorescence excitation emission matrices. Nine underlying fluorescence components were identified i...
Article
Despite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental...
Article
Full-text available
Absorbance-based sensors produce large raw attenuation datasets. We developed AbspectroscoPY, an open-source Python toolbox to implement semi-automated processing of these data and explore the full potential of high-frequency measurements.
Technical Report
Full-text available
Optical sensors are very valuable tools for process optimization or detecting deviations in the process Site-specific calibration in combination with semi-automatic signal processing aids process control thus remedying possible negative effects caused by changes in water quality. Within the last 4 years, the project collected experiences on the use...
Article
The capacity of an artificial recharge field to alter organic matter and the bacterial flora of surface water was assessed by following changes in bacterial communities and composition of natural organic matter (NOM) over the first meter of infiltration depth. The sampling strategy applied in this study ensured that water samples consisted only of...
Article
Full-text available
Two in situ optical sensors, a single-excitation fluorescence-based sensor (fDOM) mounted on a multi-parameter EXO2 sonde (YSI), and a stand-alone, multispectral absorbance-based instrument (spectro::lyser, scan Messtechnik GmbH), were evaluated for their capability to (i) estimate river dissolved organic carbon (DOC) concentrations and (ii) provid...
Article
Despite the numerous studies that have investigated the occurrence and the fate of plastic particles in the environment, only a limited effort has been devoted towards exploring the characteristics of the dissolved organic matter (DOM) leached from microplastics. In this study, using excitation emission matrix-parallel factor analysis (EEM-PARAFAC)...
Technical Report
Rapporten ger en översikt av arbetet som genomförts inom forskningsprojektet Riskbaserat beslutsstöd för säker dricksvattenförsörjning (RiBS). Rapporten beskriver den beslutsstödsmodell som har utvecklats och ger exempel på tillämpning. Dessutom beskrivs hur mikrobiologiska risker kan uppskattas och hanteras i olika delar av dricksvattensystemet –...
Article
Full-text available
The roles of dissolved organic matter (DOM) in microbial processes and nutrient cycles depend on its composition, which requires detailed measurements and analyses. We introduce a package for R, called staRdom (“spectroscopic analysis of DOM in R”), to analyze DOM spectroscopic data (absorbance and fluorescence), which is key to deliver fast insigh...
Article
Full-text available
Seasonal variability in the removal of dissolved organic matter (DOM) by drinking water biological activated carbon (BAC) filters is often attributed to temperature changes. However, it can be rather difficult to directly relate temperature to treatment efficiency at full scale due to seasonal variations in other influential parameters like DOM con...
Article
Full-text available
Investigating the biogeochemistry of dissolved organic matter (DOM) requires the synthesis of data from several complementary analytical techniques. The traditional approach to data synthesis is to search for correlations between measurements made on the same sample using different instruments. In contrast, data fusion simultaneously decomposes dat...
Article
Advancing our understanding of the behaviour of dissolved organic matter (DOM) in aquatic environments necessitates efforts to combine complementary analytical data sets. However, some analytical measurements require sample pre-treatment, while others are carried out on bulk water samples, and it remains unclear if the resulting data sets can be co...
Article
Full-text available
There is a trend of increasing natural organic matter (NOM) in raw drinking waters of Nordic countries due to climate change. Seasonal deterioration in NOM quality imparts challenges for delivering a consistently high drinking water quality. In this study, a simple and cost-effective operational strategy was investigated that improved short-term NO...
Article
Molecular size plays an important role in dissolved organic matter (DOM) biogeochemistry, but its relationship with the fluorescent fraction of DOM (FDOM) remains poorly resolved. Here high-performance size exclusion chromatography (HPSEC) was coupled to fluorescence emission-excitation (EEM) spectroscopy in full spectral (60 emission and 34 excita...
Article
Full-text available
Treated drinking water may become contaminated while travelling in the distribution system on the way to consumers. Elevated dissolved organic matter (DOM) at the tap relative to the water leaving the treatment plant is a potential indicator of contamination, and can be measured sensitively, inexpensively and potentially on-line via fluorescence an...
Data
MATLAB mfiles for PARAFAC analysis on fluorescence EEMs. Several minor bug fixes since previous releases.
Article
Full-text available
Fluorescence by naturally occurring dissolved organic matter (FDOM) is a sensitive indicator of ballast water source, with high FDOM in coastal ballast water decreasing typically dramatically when replaced by oceanic seawater during ballast water exchange. In this study, FDOM was measured in 92 ships arriving at Pacific ports on the US west coast a...
Article
Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce u...
Article
Full-text available
Absorbance and fluorescence spectroscopy are economical tools for tracing the supply, turnover and fate of dissolved organic matter (DOM). The colored and fluorescent fractions of DOM (CDOM and FDOM, respectively) are linked by the apparent fluorescence quantum yield (AQY) of DOM, which reflects the likelihood that chromophores emit fluorescence af...
Code
Simplified, annotated MATLAB code for implementing PARAFAC using the drEEM toolbox (and the N-way toolbox of course, thanks Rasmus!). For a discussion and further details, see the Appendix to our 2013 PARAFAC tutorial in Analytical Methods. Also, see the examples at the bottom of the help for any individual function in drEEM.
Article
Full-text available
Absorbance and fluorescence spectroscopy are economical tools for tracing the supply, turnover and fate of dissolved organic matter (DOM). The colored and fluorescent fractions of DOM (CDOM and FDOM, respectively) are linked by the apparent fluorescence quantum yield (AQY) of DOM, which reflects the likelihood that chromophores emit fluorescence af...
Article
Full-text available
Purpose: Odour is an important aspect of systems for human and agricultural waste management and many technologies are developed with the sole purpose of reducing odour. Compared with greenhouse gas assessment and the assessment of toxicity, odour assessment has received little attention in the life cycle assessment (LCA) community. This article ai...
Chapter
Full-text available
Cambridge Core - Geochemistry and Environmental Chemistry - Aquatic Organic Matter Fluorescence - edited by Paula G. Coble
Chapter
Full-text available
In multivariate data analysis (MVA), statistical and mathematical modeling techniques are used to analyze data that result from measuring multiple variables on several samples. Important variables infl uencing the fl uorescence characteristics of a dissolved organic mat-ter sample might include, among others, its composition, temperature, pH, and t...
Article
Full-text available
The fluorescence of dissolved organic matter (DOM) is suppressed by a phenomenon of self-quenching known as the inner filter effect (IFE). Despite widespread use of fluorescence to characterize DOM in surface waters, the advantages and constraints of IFE correction are poorly defined. We assessed the effectiveness of a commonly used absorbance-base...
Article
Full-text available
Non-methane volatile organic compounds (NMVOCs) emitted from mechanically ventilated poultry sheds in similar stages (32-36d) of broiler production were measured by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS), then identified using parallel factor analysis (PARAFAC2) and the NIST11 database. Calibration models predicting odor...
Article
Full-text available
PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many...
Data
San Francisco Bay dataset used in the drEEM PARAFAC tutorial (see linked publication). The data are corrected and PARAFAC ready.
Raw Data
Data Log for tutorial dataset
Article
To minimize the risk of biological invasions associated with commercial shipping, vessels are required to conduct ballast water exchange (BWE) ≥ 200 nautical miles offshore when arriving in the US from foreign ports, and some states require coastal BWE ≥ 50 miles offshore along domestic routes. Previous research suggests that the intensity of fluor...
Article
Full-text available
The task of identifying individual compounds within complex gas chromatography – mass spectrometry (GC–MS) chromatograms is made more difficult by interferences between peaks with similar mass spectra eluting at the same time, typically against a background of chemical and electronic noise. Although chemometric techniques like parallel factor analy...
Article
Full-text available
Continued population growth, expansion of poultry production and urban encroachment has resulted in increased odour complaints from local residents. Odour management has typically been based on buffer distances, however poultry expansion now requires accurate and reliable odour monitoring data for setting-up new broiler sheds and enlarging existing...
Article
Membrane fouling remains an operational challenge in the ultrafiltration (UF) membrane treatment of wastewater effluent and research is on-going to improve understanding of the organic character of foulants. Two advanced organic characterisation techniques that have potential to lend insight into membrane fouling are size exclusion chromatography w...
Article
Organic matter (OM) is a ubiquitous constituent of natural waters quantifiable at very low levels using fluorescence spectroscopy. This technique has recognized potential in a range of applications where the ability to monitor water quality in real time is desirable, such as in water treatment systems. This study used PARAFAC to characterize a larg...
Article
Full-text available
A method is proposed for automatically determining the upper and lower boundaries of the Raman scatter peak in fluorescence spectroscopy from empirical data. Accurate peak boundaries are needed to calculate accurate Raman peak areas, used for normalizing fluorescence signals to produce data in units that are comparable between instruments. Comparis...
Article
The fluorescent properties of dissolved organic matter (DOM) are often studied in order to infer DOM characteristics in aquatic environments, including source, quantity, composition, and behavior. While a potentially powerful technique, a single widely implemented standard method for correcting and presenting fluorescence measurements is lacking, l...
Article
To limit the spread of non-indigenous marine species, ships can be legally required to conduct ballast water exchange (BWE) prior to discharging ballast water. It has been proposed to verify BWE by measuring concentrations of coastal tracers in ballast tanks, which should track their removal. Using 3 Australian ports as case studies (Port Botany, P...
Conference Paper
In 2008, 20 laboratories around the world participated in an intercalibration study of organic matter fluorescence measurements via Excitation-Emission Matrix Spectroscopy (EEMS). The goal was to assess the variability of fluorescence measurements obtained for identical samples (n = 5 natural samples, Suwanee River Fulvic Acid, quinine sulphate and...
Article
Full-text available
The assessment of compliance by ships with mandatory ballast water exchange (BWE) is limited by the difficulty of verifying whether BWE was implemented. Previous research indicates that concentrations in ballast water of barium, phosphorous and manganese and chromophoric dissolved organic matter (CDOM) can be robust tracers of BWE. The current stud...
Article
Full-text available
The transfer of organisms in ballast water of commercial ships is a leading cause of biological invasions in coastal ecosystems. Ships arriving in New Zealand are now required to treat their ballast water to reduce the risk of transferring invasive aquatic organisms between ports. Most of these ships conduct mid-ocean ballast water exchange (BWE),...
Article
A rapid, highly sensitive and selective detector is urgently required to detect contamination events in recycled water systems - for example, cross-connection events in dual reticulation pipes that recycle advanced treated sewage effluent - as existing technologies, including total organic carbon and conductivity monitoring, cannot always provide t...
Article
Recent regulation mandates that ships conduct mid-ocean ballast water exchange (BWE) prior to discharging foreign ballast in U.S. territorial waters. We investigated the utility of dissolved concentration measurements for 6 elements (Ba, P, Mn, U, V and Mo) in the ballast tanks of ships operating in the North Pacific and Atlantic oceans as tracers...
Article
The optical properties of chromophoric dissolved organic matter (CDOM) are frequently used as tracers of water masses in bays and estuaries but present unique challenges in the ocean due to the small quantities of organic matter present and the similarities between spectra from coastal and offshore environments. Samples collected on trans-oceanic c...
Article
Full-text available
A rapid high-throughput method is presented for the determination of trace elements (P, V, Mn, As, Mo, Ba and U) in seawater with application to tracing ballast water exchange in ocean-going vessels. By employing direct flow injection and methane addition the method is capable of >700 continuous determinations of ten-fold diluted seawater samples i...
Presentation
Significant losses in fluorescence intensity were observed in seawater chromophoric dissolved organic matter (CDOM) samples stored frozen for up to 8 months prior to analysis. Samples (N = 155) were collected from ships' ballast tanks on two cruises in 2003, frozen and shipped to the laboratory. The stability of the fluorometer response over the an...
Article
Mid-ocean ballast water exchange is mandatory for ships discharging foreign ballast in US territorial waters in order to reduce the risk of biological invasions. However, a reliable tool for determining whether the procedure took place is lacking. We investigated chromophoric dissolved organic matter (CDOM) fluorescence as a tracer of mid-ocean exc...
Article
Full-text available
Correction for ‘Supply-side invasion ecology: characterizing propagule pressure in coastal ecosystems’ by Emma Verling, Gregory M. Ruiz, L. David Smith, Bella Galil, A. Whitman Miller and Kathleen R. Murphy (Proc. R. Soc. B 272 , 1249–1256. (doi: 10.1098/rspb.2005.3090 )). A reference was omitted from the print version of this paper; the missing re...
Article
Full-text available
The observed rates and deleterious impacts of biological invasions have caused significant alarm in recent years, driving efforts to reduce the risk (establishment) of new introductions. Characterizing the supply of propagules is key to understanding invasion risk and developing effective management strategies. In coastal ecosystems, ships' ballast...
Article
Full-text available
Ballast water management of ships entering the United States is a key component in stopping invasions of non-indigenous aquatic species. Ballast water exchange (BWE) is currently the most common method of ballast water management and it is likely to remain an approved management technique for the foreseeable future. The United States Coast Guard's...
Article
We examined methods for verifying whether or not ships have performed mid-ocean ballast water exchange (BWE) on four commercial vessels operating in the Pacific and Atlantic Oceans. During BWE, a ship replaces the coastal water in its ballast tanks with water drawn from the open ocean, which is considered to harbor fewer organisms capable of establ...
Article
Full-text available
Laws designed to reduce the number of introductions of aquatic nuisance species into U.S. waters require ships from outside the Exclusive Economic Zone to conduct mid-ocean ballast water exchanges (BWE) before entering the Great Lakes and upper Hudson River. The National Invasive Species Act of 1996 requests ships entering any U.S. waters to conduc...