ࡱ > R t bjbjVV ? < < + 1 1 1 1 1 E E E 8 } T E g ' ' ' ' ( ( ( a a a a a a a $ %j l a I 1 ( ( ( ( ( a 1 1 ' ' Eg J J J ( 1 ' 1 ' "] J ( a J J : N , vO ' @úe=w E pB O
] [g 0 g $O R {m rG m vO vO {m m $ 1 bP ( ( J ( ( ( ( ( a a lH ( ( ( g ( ( ( ( m ( ( ( ( ( ( ( ( ( : Vibrational spectroscopy for water quality analysis: a review
A.A. Gowen1,2*, R.Tsenkova2, M. Bruen3, C. ODonnell1
1Biosystems Engineering, University College Dublin, Ireland
2Biomeasurement Laboratory, Kobe University, Japan
3Centre for Water Resources Research, University College Dublin, Ireland
*corresponding author. Email address: HYPERLINK "mailto:aoife.gowen@ucd.ie" aoife.gowen@ucd.ie, Phone: 35317167413
Abstract
Maintaining a clean water supply is one of the key challenges facing humanity today. Pollution, over-use and climate change are just some of the factors putting increased pressure on our limited water resources. Contamination of the water supply presents a high risk to public health, security and the environment; however, no adequate real-time methods exist to detect the wide range of potential contaminants. There is a need for rapid, low cost, multi target systems for water quality monitoring. Information rich techniques such as vibrational spectroscopy have been proposed for this purpose. This review presents developments in the applications of vibrational spectroscopy to water quality monitoring over the past 20 years, identifies emerging technologies and discusses future challenges.
Keywords: water, quality, vibrational, spectroscopy, monitoring, real-time, continuous, infra-red, Raman spectroscopy
Running title: Vibrational spectroscopy for water quality analysis
1. Introduction
A wide range of parameters are used to describe water quality, which can be broadly subdivided into the following groups: indicator, microbiological, organic and inorganic. Thus, the concept of water quality is essentially a multivariate one. Some examples of indicator parameters are colour, conductivity, hydrogen ion concentration, odour and taste. Organic chemicals which may be found in natural waters include chlorinated Alkanes, Benzenes and Ethenes; inorganic chemicals include Cadmium, Lead and Nickel. Microbiological organisms of concern include Escherichia coli (E. coli), Enterococci and Pseudomonads. These groups of quality parameters may be further subdivided; for example, the United States Environmental Protection Agency (EPA) further subdivides organic parameters into disinfectants and pesticides.
Environmental waters are exposed to contamination by thousands of micro-pollutants from pharmaceutical, agricultural and natural origins. Monitoring of water quality presents a complicated multi-spatial and multi-temporal problem extending from surveillance monitoring of surface or ground waters to operational monitoring of waste waters, both prior to and after treatment, in order to control treatment performance and enable re-use. International organisations such as the World Health Organisation (WHO), United States Environmental Protection Agency (EPA) and European Union (EU) provide guidelines including maximum allowable concentrations of various contaminants in water which may be found in (WHO, 2006; EPA, 2010; EU, 2010). Table 1 lists the highest priority contaminant substances and their maximum allowable levels for inland surface water quality as published recently by the EU Water Framework Directive (WFD) ( ADDIN EN.CITE Porcher200911211211217Porcher, J. P.EU water framework directive : measurement tools and water status evaluationHouille Blanche-Revue Internationale De L EauHouille Blanche-Revue Internationale De L Eau41-45320090018-6368ISI:000267791500004<Go to ISI>://000267791500004FrenchPorcher (2009)).
Standard methods for water quality analysis involve intensive sampling regimes and multi-step sample preparation, requiring manual inputs, which prohibits their integration in continuous monitoring systems. Analytical determination of contaminants is typically carried out by extraction of the compounds of interest from the water matrix, using high performance liquid chromatography (HPLC) or gas chromatography (GC) coupled to selective detection methods such as Mass Spectrometry (MS). Sample preparation required in these multi-step methods is lengthy and typically the most crucial step in the detection process. In some cases, turnaround times for such laboratory tests are so slow that consumption of contaminated water may occur before the test results are known. Consequently there is a need for low cost, robust, reliable monitoring techniques that can be easily integrated into water flow systems. For instance, ADDIN EN.CITE Karlberg201019319319317Karlberg, B.Worsfold, P.Andersen, J. E. T.Andersen, JET
Tech Univ Denmark, Dept Chem, Bldg 207, DK-2800 Lyngby, Denmark
Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark
Univ Plymouth, Sch Geog Earth & Environm Sci, Plymouth PL4 8AA, Devon, England
Stockholm Univ, Dept Analyt Chem, S-10691 Stockholm, SwedenEuropean analytical column no. 38 (January 2010)Analytical and Bioanalytical ChemistryAnalytical and Bioanalytical ChemistryAnal. Bioanal. Chem.1647-165139752010Jul1618-2642ISI:000278810000005<Go to ISI>://000278810000005DOI 10.1007/s00216-010-3797-2EnglishKarlberg et al. (2010) concluded that there is a growing need for in situ sensor technologies that can provide high temporal and spatial resolution data in real time, with an appropriate standard of data quality, to supplement techniques and methods for laboratory analysis .
The term Early Warning System (EWS) encompasses all scanning, monitoring, and analysing efforts related to contaminant detection in water. The EPA has defined a need for EWSs with the following characteristics: rapid response, detection of a wide range of potential contaminants, low skill operation, sufficient sensitivity, remote and continuous operation (Hassan et al., 2005). At present, viable integrated EWSs that meet the desired performance characteristics and that can be routinely used are not available. However, a wide range of new screening and monitoring emerging tools (SMETs) have been developed to aid in the task of water quality monitoring. A review of advances in online drinking water quality monitoring has recently been published ( ADDIN EN.CITE Storey41641641617Storey, Michael V.van der Gaag, BramBurns, Brendan P.Advances in on-line drinking water quality monitoring and early warning systemsWater ResearchWater ResearchWater Res.In Press, Corrected ProofWater qualityOn-line monitoring0043-1354http://www.sciencedirect.com/science/article/B6V73-50YF6F3-1/2/4884e4c8c1d9b7b41e6c64cfd92c38f3Storey41641641617Storey, Michael V.van der Gaag, BramBurns, Brendan P.Advances in on-line drinking water quality monitoring and early warning systemsWater ResearchWater ResearchWater Res.In Press, Corrected ProofWater qualityOn-line monitoring0043-1354http://www.sciencedirect.com/science/article/B6V73-50YF6F3-1/2/4884e4c8c1d9b7b41e6c64cfd92c38f3Storey et al.), based on visits to water utilities, research and technology providers throughout Europe. These include immunoassays, optical sensors, bio sensors and chemical test kits ( ADDIN EN.CITE Graveline37937937917Graveline, Nina