Laser-induced breakdown spectroscopy application in environmental monitoring of water quality: a review

Water quality monitoring is a critical part of environmental management and protection, and to be able to qualitatively and quantitatively determine contamination and impurity levels in water is especially important. Compared to the currently available water quality monitoring methods and techniques, laser-induced breakdown spectroscopy (LIBS) has several advantages, including no need for sample pre-preparation, fast and easy operation, and chemical free during the process. Therefore, it is of great importance to understand the fundamentals of aqueous LIBS analysis and effectively apply this technique to environmental monitoring. This article reviews the research conducted on LIBS analysis for liquid samples, and the article content includes LIBS theory, history and applications, quantitative analysis of metallic species in liquids, LIBS signal enhancement methods and data processing, characteristics of plasma generated by laser in water, and the factors affecting accuracy of analysis results. Although there have been many research works focusing on aqueous LIBS analysis, detection limit and stability of this technique still need to be improved to satisfy the requirements of environmental monitoring standard. In addition, determination of nonmetallic species in liquid by LIBS is equally important and needs immediate attention from the community. This comprehensive review will assist the readers to better understand the aqueous LIBS technique and help to identify current research needs for environmental monitoring of water quality.     

Environmental applications of single collector high resolution ICP-MS

The number of environmental applications of single collector high resolution ICP-MS (HR-ICP-MS) has increased rapidly in recent years. There are many factors that contribute to make HR-ICP-MS a very powerful tool in environmental analysis. They include the extremely low detection limits achievable, tremendously high sensitivity, the ability to separate ICP-MS signals of the analyte from spectral interferences, enabling the reliable determination of many trace elements, and the reasonable precision of isotope ratio measurements. These assets are improved even further using high efficiency sample introduction systems. Therefore, external factors such as the stability of laboratory blanks are frequently the limiting factor in HR-ICP-MS analysis rather than the detection power. This review aims to highlight the most recent applications of HR-ICP-MS in this sector, focusing on matrices and applications where the superior capabilities of the instrumental technique are most useful and often ultimately required.     

The occurrence of the herbicide dalapon (2,2-dichloropropionate) in potable water as a disinfection by-product

Salts of 2,2-dichloropropionic acid, such as dalapon, are well known as herbicides and are regulated as such in potable water in Australia and elsewhere. It is also an identified disinfection by-product (DBP), but little is known about the compound's formation and typical levels from this source. This work presents results from a sampling campaign where 2,2-dichloropropionate was found at levels between 0.1 and 0.5 μg l(-1) in potable water samples from a major treatment plant in South East Queensland, Australia. However, levels were below the reporting limit (0.01 μg l(-1)) in the immediate source water for the plant. Also, temporal trends in 2,2-dichloropropionate observed in treated water during sampling mirrored those of trihalomethanes albeit at much lower concentrations, suggesting that the occurrence is due to in situ formation as a DBP. This could present a regulatory dilemma in some jurisdictions.     

Economics of place-based monitoring under the safe drinking water act, part II: Design and development of place-based monitoring strategies

The goals of environmental legislation and associated regulations are to protect public health, natural resources, and ecosystems. In this context, monitoring programs should provide timely and relevant information so that the regulatory community can implement legislation in a cost-effective and efficient manner. The Safe Drinking Water Act (SDWA) of 1974 attempts to ensure that public water systems (PWSs) supply safe water to its consumers. As is the case with many other federal environmental statutes, SDWA monitoring has been implemented in relatively uniform fashion across the United States. In this three part series, spatial and temporal patterns in water quality data are utilized to develop, compare, and evaluate the economic performance of alternative place-based monitoring approaches to current monitoring practice. Part II: Several factors affect the performance of monitoring strategies, including: measurable objectives, required precision in estimates, acceptable confidence levels of such estimates, available budget for sampling. In this paper, we develop place-based monitoring strategies based on extensive analysis of available historical water quality data (1960-1994) of 19 Iowa community water systems. These systems supply potable water to over 350,000 people. In the context of drinking water, the objective is to protect public health by utilizing monitoring resources to characterize contaminants that are detectable, and are close to exceeding health standards. A place-based monitoring strategy was developed in which contaminants were selected based on their historical occurrence, rather than their appearance on the SDWA contaminant list. In a subset of the water systems, the temporal frequency of monitoring for one ubiquitous contaminant, nitrate, was tailored to patterns in its historical occurrence and concentration. Three sampling allocation models (linear, quadratic, and cubic) based on historic patterns in peak occurrence were developed and evaluated. Random and fixed-interval sampling strategies within the context of such models were also developed and evaluated. Strategies were configured to incorporate a variety of options for frequency and number of samples (depending on budget and the desired precision in estimate of peak concentrations).     

Evaluation of significant sources influencing the variation of water quality of Kandla creek, Gulf of Katchchh, using PCA

To evaluate the significant sources contributing to water quality parameters, we used principal component analysis (PCA) for the interpretation of a large complex data matrix obtained from the Kandla creek environmental monitoring program. The data set consists of analytical results of a seasonal sampling survey conducted over 2 years at four stations. PCA indicates five principal components to be responsible for the data structure and explains 76% of the total variance of the data set. The study stresses the need to include new parameters in the analysis in order to make the interpretation of principal components more meaningful. The PCA could be applied as a useful tool to eliminate multi-collinearity problems and to remove the indirect effect of parameters.     

固相微萃取技术在环境监测分析中的应用进展

样品前处理是整个样品分析过程中的关键一环,其目的在于减少杂质对待测物的干扰及对目标物进行富集。固相微萃取技术是集采样、萃取、富集、进样于一体的样品前处理新技术。近年来,固相微萃取技术在环境污染物监测分析领域得到了广泛应用,该文章系统地综述了固相微萃取技术在不同环境基质(水体、大气、土壤及沉积物)预处理的方法,比较了不同类型涂层材料(如纳米材料、离子液体等)与装置形式(如内部冷却固相微萃取、箭形固相微萃取等)的优缺点及应用范围。针对现阶段固相微萃取技术应用于不同环境基质中存在的问题和不足,提出进一步研究的方向。     

Environmental Isotopes for Resolution of Hydrology Problems

The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in the environment describe hydrological processes, estimate ages, fingerprint sources and pathways, yet are not subject to the regulatory restraints of artificial isotope injections nor the limited extent of many chemical tracers, particularly dyes and particulates. A short review is presented for practicing hydrologists on the basis for employing stable and radioactive isotopes and a synopsis of recent isotope hydrology applications is provided. Special focus is presented on the emergent role of water isopopes (¹⁸O, ²H, ³H) in wet-weather flow research in urban watersheds. A brief technical approach for an experimental site in the Mill Creek Watershed, Ohio is outlined.     

Chromatographic techniques for pollution analyses

Pollution studies of air and water samples have been greatly enhanced by the use of chromatographic techniques. The selection of the proper detectors coupled with the various column types and substrates have broadened the capabilities of environmental analyses. Proper care in sampling protocols and sample treatment has steadily improved the sensitivity of these measurements. The recommended methods for air, wastewater, drinking water and solid waste samples all utilize some type of chromatographic analysis for the determination of organic contaminants. Three complimentary techniques: i.e., headspace sampling (dynamic and static methods), microextractions (liquid-liquid and/or liquid-solid) and solid-phase extractions have expanded the capabilities of such studies to permit the analytical chemist to perform fast in-the-field monitoring, concentrate low levels of analytes and determine solubilities of toxic substances. A discussion of other environmental areas which should be studied, along with the changes and/or modifications in analytical technology which should be investigated, will be presented.Plenary speaker.     

Bromate analysis in groundwater and wastewater samples

Bromate (BrO(3)(-)) is a disinfection by-product formed during ozonation of potable water supplies containing bromide (Br(-)). Bromate has been classed by the World Health Organisation as a 'possible human carcinogen', leading to implementation of 10-25 microg L(-1)(as BrO(3)(-)) drinking water limits in legislative areas including the United States and European Union. Techniques have been developed for bromate analysis at and below regulatory limits, with Ion Chromatography (IC) coupled with conductivity detection (IC-CD), post-column reaction and ultra-violet (UV) detection (IC-PCR), or inductively coupled plasma-mass spectrometry detection (IC-ICPMS) in widespread use. The recent discovery of bromate groundwater contamination in a UK aquifer has led to a requirement for analysis of bromate in a groundwater matrix, for environmental monitoring and development of remediation strategies. The possibility of bromate-contaminated water discharge into sewage treatment processes, whether accidental or as a pump-and-treat strategy, also required bromate analysis of wastewater sources. This paper summarises techniques currently available for trace bromate analysis in potable water systems and details studies to identify a methodology for routine analysis of groundwater and wastewater samples. Strategies compared were high performance liquid chromatography (HPLC) with direct UV or PCR/UV detection, IC-CD, IC-PCR, and a simple spectrophotometric technique. IC-CD was the most cost-effective solution for simultaneous analysis of bromate and bromide within groundwater samples, having a 5 microg L(-1) detection limit of both anions with limited interference from closely-eluting species. Wastewater samples were successfully analysed for bromate only using HPLC with PCR/UV detection, with detection limits below 20 microg L(-1)(as BrO(3)(-)) and low interference. HPLC with direct UV detection was unsuitable for bromate analysis within the concentration range 50-5000 microg L(-1) which was required for this project, but column choice was shown to be a major factor in determining limits of detection. Spectrophotometry could not reproducibly determine bromate concentration, although the technique showed promise as a quick field method for high-level groundwater bromate analysis.     

Total organic carbon analysis as a precursor to disinfection byproducts in potable water: oxidation technique considerations

In recent years, an increasing number of regulations and methodologies have begun to utilize total organic carbon (TOC) analysis for monitoring microbial contamination and/or disinfectant byproduct (DBP) precursors. This paper highlights some analytical differences and similarities between the two widely used TOC oxidation techniques: UV persulfate and high temperature combustion (HTC). Previous papers have come to different and sometimes contradictory conclusions on this subject. However, these studies either compared instruments with significantly different flow paths or TOC systems from different eras. Unlike previous studies, this paper compares two modern TOC analyzers with nearly identical flow paths for sample recovery, detection limits, and analysis of real world samples. On average, both persulfate and HTC oxidation yielded good recoveries for 10 hard to oxidize compounds and potable water samples from 5 different locations across the USA. In general, persulfate yielded more precise results because of its lower background response relative to sample response while HTC gave slightly higher results (roughly 2% to 3%) for surface water samples.     

Sampling and analysis for radon-222 dissolved in ground water and surface water

Radon-222 is a naturally occurring radioactive gas in the uranium-238 decay series that has traditionally been called, simply, radon. The lung cancer risks associated with the inhalation of radon decay products have been well documented by epidemiological studies on populations of uranium miners.The realization that radon is a public health hazard has raised the need for sampling and analytical guidelines for field personnel. Several sampling and analytical methods are being used to document radon concentrations in ground water and surface water worldwide but no convenient, single set of guidelines is available. Three different sampling and analytical methods-bubbler, liquid scintillation, and field screening-are discussed in this paper. The bubbler and liquid scintillation methods have high accuracy and precision, and small analytical method detection limits of 0.2 and 10 pCi/l (picocuries per liter), respectively. The field screening method generally is used as a qualitative reconnaissance tool.     

A field-based spectrophotometric flow-injection system for automatic determination of chloride in soil water

The use of chloride as a tracer for soil water investigations is discussed. Limitations with laboratory based soil core and field based sampling are considered with respect to the poor suitability of the data for rigorous assessment of mechanistic models. Investigation of water movement in soil has been restricted by limitations in spatial and temporal sampling. Fine resolution sampling generates large numbers of samples which cause problems with post sampling laboratory analysis. This paper describes a field-based system for the analysis of chloride in soil water. There are three component parts to the system, (i) a custom sampling sub-system comprising of ceramic cup suction samplers and sample traps, (ii) a sample routing sub-system to channel sample to (iii) a sample analysis sub-system utilizing a flow injection method for sample analysis using a custom built photo-diode detector. The three sub-systems were controlled by a suitably equipped personal computer. A calibration procedure is described with a third order polynomial equation derived to convert millivolt response from the detector into chloride concentration. Field and laboratory data from a tracer experiment are presented and discussed, and it is concluded that the system is well suited to field-based applications. Finally it is noted that the photo-detector is suitable for colourimetric analysis of any tracer with suitable chemical determination.     

Methodologies for determination of antimony in terrestrial environmental samples

Methodologies for the environmental analysis of total antimony and aqueous chemical speciation are critically reviewed, including preparation techniques for aqueous and solid matrices and the determination of solid state partitioning and recommendations are given for future research directions. Concentrations of total antimony commonly present in aqueous and solid environmental samples are readily determined using present day analytical techniques. This has resulted primarily from technological advances in microwave digestion for solid matrices and the development of plasma based analyte detection systems. ICP-AES and ICP-MS techniques are both utilised for the environmental analysis of total antimony concentrations. However, ICP-MS is increasingly favoured as a result of reduced spectral interferences and the potential for analyte detection in the pg mL(-1) range. Determination of aqueous antimony speciation presents a number of complex analytical challenges and highly selective separation and identification techniques are required prior to detection. The majority of published techniques including common applications of hydride generation are insufficiently selective for the determination of intrinsic chemical speciation and often only oxidation state data are obtained. The recent in-line applications of HPLC-ICP-MS offer the potential for highly selective separations of aqueous antimony species and determination of detailed chemical speciation data. However, considerable development work is required to optimise chromatographic separations and identify uncharacterised species resident in environmental systems. Analytical techniques to aid the determination of antimony's associations with solid environmental matrices include the application of chemical extraction procedures and leaching experiments. To date, this area of analytical research has received little attention and further studies are required to elucidate this aspect of antimony's environmental chemistry.     

Techniques and methods for the determination of haloacetic acids in potable water

Haloethanoic (haloacetic) acids (HAAs) are formed as disinfection byproducts (DBPs) during the chlorination of natural water to make it fit for consumption. Sundry analytical techniques have been applied in order to determine the concentrations of the HAAs in potable water supplies: gas chromatography (GC-MS, GC-ECD); capillary electrophoresis (CE); liquid chromatography (LC), including ion chromatography (IC); and electrospray ionization mass spectrometry (ESI-MS). Detection limits required to analyze potable water samples can be regularly achieved only by GC-ECD and ESI-MS. Without improvements in preconcentration or detector sensitivity, CE and LC will not find application to potable water supplies. The predominant GC-ECD methods use either diazomethane or acidified methanol to esterify (methylate) the carboxylic acid moiety. For HAA5 analytes, regulated under the EPA's Stage 1 DBP Rule, diazomethane is satisfactory. For HAA9 data gathered under the Information Collection Rule, acidified methanol outperforms diazomethane, which suffers from photo-promoted side reactions, especially for the brominated trihaloacetic acids. Although ESI-MS can meet sensitivity and selectivity requirements, limited instrumentation availability means this technique will not be widely used for the time being. However, ESI-MS can provide valuable confirmatory information when coupled with GC-ECD in a research setting.     

我国地下水环境监测现状和工作建议

基于近些年的调查和监测结果，统计分析了我国地下水环境质量基本状况及主要超标指标的地区分布情况。指出，当前我国地下水环境监测工作主要由自然资源、水利、生态环境等部门分别组织开展，存在地下水监测信息共享与整合难度较大、尚未形成全国统一的地下水环境监测体系、“双源”地下水监测现状尚未摸清、地下水监测能力明显不足、地下水监测的生态环境保护作用尚未体现等问题。提出，进一步推动部门资源共享与整〖JP2〗合、统一全国地下水监测体系、优化完善考核机制、尽快摸清地下水监测现状和逐步提升监测能力等工作建议，以期为下一阶段全国地下水环境监测工作提供借鉴。     

Simplification and validation of a large volume polyurethane foam sampler for the analysis of persistent hydrophobic compounds in drinking water

The use of a large volume polyurethane foam (PUF) sampler was validated for rapid extraction of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), in raw water and treated water from drinking water plants. To validate the recovery of target compounds in the sampling process, a (37)Cl-labeled standard was spiked into the 1st PUF plug prior to filtration. An accelerated solvent extraction method, as a pressurized liquid extractor (PLE), was optimized to extract the PUF plug. For sample preparation, tandem column chromatography (TCC) clean-up was used for rapid analysis. The recoveries of labeled compounds in the analytical method were 80-110% (n = 9). The optimized PUF-PLE-TCC method was applied in the analysis of raw water and treated potable water from seven drinking water plants in South Korea. The sample volume used was between 18 and 102 L for raw water at a flow rate of 0.4-2 L min(-1), 95 and 107 L for treated water at a flow rate of 1.5-2.2 L min(-1). Limit of quantitation (LOQ) was a function of sample volume and it decreased with increasing sample volume. The LOQ of PCDD/Fs in raw waters analyzed by this method was 3-11 times lower than that described using large-size disk-type solid phase extraction (SPE) method. The LOQ of PCDD/F congeners in raw water and treated water were 0.022-3.9 ng L(-1) and 0.018-0.74 ng L(-1), respectively. Octachlorinated dibenzo-p-dioxin (OCDD) was found in some raw water samples, while their concentrations were well below the tentative criterion set by the Japanese Environmental Ministry for drinking water. OCDD was below the LOQ in the treated drinking water.     

Selection of appropriate sampling stations in a lake through mapping

Much valuable information is obtained from water quality measurements and monitoring of lakes around the world. A powerful tool is the use of mapping techniques, as it offers potential use in water quality research. Both remote sensing techniques and traditional water quality monitoring are required to collect data at sampling stations. This study suggests another approach to determine the most appropriate distribution of sampling stations in water reservoirs that will be mapped for water quality parameters. Tests were conducted for the proposed approach for Secchi disc depth (SDD), chlorophyll-a, turbidity and suspended solids parameters in Lake Beysehir, Turkey. Results of analysis are available for a total of 30 sampling stations in August 2006. Ten sampling stations were used to model Lake Beysehir while the others were used for validation of the model. Sampling stations that offered the best representation of the lake for each parameter were determined. Then, the best representative sampling stations for all parameters in the study were determined. Moreover, in order to confirm the accuracy of these re-determined sampling stations, modelling was performed on the results of the analysis of June 2006, and it was found that the values obtained from the re-determined sampling stations were acceptable.     

地表水监测误差分析与对策

分析和探讨了地表水环境监测过程中存在的误差。在13家监测站同步采样、同步分析的基础上，筛选出地表水监测实验室间比对结果偏差较大的石油类、挥发酚、氨氮、五日生化需氧量、化学需氧量、高锰酸盐指数和总磷等7个监测指标。从方法误差、仪器误差、试剂误差、操作误差、环境误差、过失误差和质控选择不当造成的误差等各方面探讨误差成因。根据实样测定结果，提出合理选择并统一分析方法、增加平行测定次数、加强质控措施和修改允许相对偏差等切实可行的对策和措施，为地表水监测和水环境管理提供技术依据。     

The development of cryoprobe nuclear magnetic resonance spectroscopy for the rapid detection of organic contaminants in potable water

The detection of trace levels of a range of organic contaminants (including pesticides, toxins and an explosive) in potable water, using cryoprobe NMR spectroscopy with limited sample preparation and rapid acquisition times, is described. Emphasis is placed on the applicability of NMR spectroscopy for use in emergency scenarios as the unbiased nature of the technique facilitates the detection and characterization of unknown compounds at levels as low as 50 microg L(-1).     

Advances in the determination of inorganic ions in potable waters by ion chromatography

Ion chromatography (IC) is now a well-established methodology for the analysis of ionic species. The technique is applicable to the determination of a wide range of solutes in many sample types, although the determination of inorganic ions in potable waters continues to be the most widely used application of ion chromatography. Many standardization and regulatory bodies, such as the American Society for Testing and Materials (ASTM), International Organization for Standardization (ISO), and US Environmental Protection Agency (EPA), have approved methods of analysis based upon IC, most of which have been published within the last decade. Recent developments in the field of IC, such as the use of higher capacity columns, larger loop injections, more complex sample preparation and detection schemes, have been incorporated into these new approved methods. These advances allow the determination of environmentally significant contaminants, such as common inorganic anions, bromate, perchlorate and chromate, at trace levels in potable waters using ion chromatography.