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Modelling and analytical methods for monitoring selected organic and inorganic pollutants in surface and treated water systems in South Africa
Abstract
Abstract: As new analytical methods for monitoring water quality continue to advance and become more specific in their detection limits, geochemical modelling tools are also advancing due to increasing technological creations. These two disciplines of chemistry (analytical techniques and modelling) are aimed at ensuring clean and safe water for better quality of life. The goal of this study was to use analytical methods and geochemical modelling tools to monitor selected metals, anions, volatile organic compounds and non-volatile organic compounds from South African water systems. Two sets of samples were collected, namely, a set of seven and another set of six samples were collected from a wastewater treatment plant (WWTP) in the Gauteng province and surface water (river) in Kwa-Zulu Natal province, respectively. Inorganic and organic water contaminants were analysed using techniques such as; inductively coupled plasma mass spectroscopy (ICP-MS), ion exchange chromatography (IEC), high performance liquid chromatography (HPLC) and multi-dimensional gas chromatography – time of flight mass spectroscopy (GCxGC-TOF/MS). A new hybrid database for geochemical modelling was developed from extracted experimental data. The modification of the database involved the merging of two already existing databases (Wateqf.dat and PHREEQ C.dat) with inclusion of data on five chlorinated organic compounds (COCs) namely; pentachlorophenol, three isomers of trichlorobenzene (TCB) and trichloroethylene. In order to enhance precision and accuracy, metal speciation, fate and transport calculations were carried out using the modified geochemical database. With this new hybrid database, a mobile application running on an android operating system (OS) was developed and tested for its accuracy in prediction and efficiency.
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In 2002, the Swedish Metal Information Task Force (MITF) engaged the Environmental Research Group (MFG) to update previous monographs on copper, zinc and major alloying metals (such as chromium, nickel and molybdenum) in society and in the environment. This book presents new results on metal fluxes from society to the environment, on metal speciation in water, soil and sediment, and its interpretation in terms of mobility, biological uptake and toxicity. The scientific fundamentals of new approaches, like the Acid Volatile Sulphide (AVS) concept to predict metal bioavailability in sediments, and the Biotic Ligand Model (BLM) to calculate the toxicity of metals to aquatic organisms, are critically evaluated, with a focus on copper, nickel, zinc, and, in part, chromium.
Recent scientific advances now offer an improved understanding of the mechanisms and factors controlling the intricate behaviour of trace metals, their interactions, uptake and effect in natural systems. Traditional risk assessment methods usually built on quite crude toxicity tests done in unrealistic "laboratory waters", and did not consider natural conditions. In contrast, modern approaches now increasingly involve the full utilisation of site-specific factors, which are decisive for the formation of bioavailable and toxic metal forms.
Audience
This book provides excellent guidance to both scientists focusing on the assessment of the ecological risk of metals, and to authorities, decision makers in industry, educational staff and the interested public concerned with the occurrence and fate of trace metals.
In this book, the proceedings of the Third European Symposium on "Analysis of Organic Micropollutants in Water", held in Oslo (Norway), from 19 to 21 September 1983, are presented. The symposium was organized within the framework of the Concerted Ac tion COST 64b bis *, which has the same name and is included in the Third R&D Programme on Environment of the Commission of the European Communi ties - Indirect and Concerted Actions - 1981 to 1985. The aim of the symposium was to review the progress and results achiev ed during the past two years, since the Second symposium, held in Killarney (Ireland) in November 1981. The programme of the symposium consisted of review papers covering dif ferent areas related to the analysis of the organic pollutants in water, in cluding sampling and sample treatment, gas and liquid chromatography, mass spectrometry and specific analytical problems for some types of compounds. We think that the volume gives a rather complete overview of these activities in Europe. Moreover, the paper presented by D. Hunt reviews the development of the new technique mass spectrometry - mass spectrometry in the United States of America. Some special sessions concerned the presentation of original contri butions in form of poster, the extended versions of which are published in this volume.
A review of research into the isolation, separation and identification of non-volatile organic compounds in water is presented.
The review has been restricted to the most commonly used methods for the isolation of non-volatile organics; viz freeze-drying, reverseosmosis, activated carbon adsorption and XAD resin adsorption. It is shown that each of these techniques is capable of isolating a range of non-volatile organics from water but it is apparent that no one method is capable of extracting all organics present in a water sample.
Separation methods for non-volatiles invariably use high-performance liquid chromatography and several chromatographic methods have been employed. Undoubtedly reversed-phase chromatography has received the most widespread usage although efficient separations of certain types of non-volatile compound have been obtained on normal-phase chromatography, size-exclusion chromatography and ion-exchange chromatography.
Identification of separated non-volatile compounds is difficult but feasible by the application of state-of-the-art mass spectrometric techniques. In particular the use of field desorption mass spectrometry with accurate mass measurement and collisonal activation with linked scanning is shown to be highly promising.
Contamination of water by pesticides is an important issue in many regions, posing problems in the environmental, water management and health sectors. To assess the extent of contamination of water, effective and properly designed analytical methods having sufficient sensitivity and accuracy are needed. However, no matter how excellent are the state‐of‐the‐art analytical instrumentation and techniques applied, the data on trace concentrations of pesticides provided by the analytical system will be useless unless sufficient attention is given to sampling and sample preparation.
To collect a representative water sample for pesticide analysis, all sampling parameters must be selected properly. This refers predominantly to the selection of the appropriate sampling site, sampling technique and volume of the water sample. To prevent the sample matrix from any undesirable alterations during its transport from the sampling site to an analytical laboratory, physical (e.g. temperature, light intensity) and chemical/biochemical (e.g. pH, microbial growth) conditions must be under control, i.e. the sample must be preserved carefully. An efficient alternative to the transport of liquid water samples from the sampling point to the laboratory is on‐site sorption of analytes on a solid phase. This minimizes the weight of transported samples and increases the stability of analytes.
The determination of trace concentrations of pesticides in water samples and the complexity of environmental matrices require the application of an efficient sample‐handling procedure prior to separation and detection of these analytes. At present, liquid–liquid extraction (LLE) and solid‐phase extraction (SPE) are the most frequently applied sample‐handling techniques in the determination of pesticides in water. LLE is a traditional method that is still widely used in standardized methods. The increasing popularity of SPE is a result of its versatility and effectiveness and SPE is also preferred owing to the lower health risks.
The introduction of new sorbent materials, the development of automated sample‐handling systems allowing unattended operation and newly emerging sample‐handling techniques such as solid‐phase microextraction (SPME) and membrane separation methods guarantee that sample preparation in pesticide analysis will remain a fertile area of development in the future.
In previous studies (Loper and Lang, 1978; Loper et al., 1978; Lang et al., in press; Kurzepa et al., in press), we used shortterm bioassays to demonstrate the mutagenicity, carcinogenicity, and toxicity of residues prepared from samples of drinking water from six U. S. cities. The samples were processed by Gulf South Research Institute (New Orleans, LA), using reverse osmosis plus XAD resin sorption-desorption as described by Kopfler et al. (1977). Using the Ames test, we found city-specific patterns of dose-dependent mutagenesis that were essentially independent of the microsomal activation system. One or more samples from each city showed reproducible transformation frequencies at least three times the spontaneous frequency. Focus formation induced by these samples was equivalent to malignant transformation as verified in nude mice. In these studies, quantitation of mutagenic and transformation responses were complicated by the toxicity and heterogeneity of the complex residue mixtures.
The chemical composition of natural water is derived from many different sources of solutes, including gases and aerosols from the atmosphere, weathering and erosion of rocks and soil, solution or precipitation reactions occurring below the land surface, and cultural effects resulting from human activities. Broad interrelationships among these processes and their effects can be discerned by application of principles of chemical thermodynamics. Some of the processes of solution or precipitation of minerals can be closely evaluated by means of principles of chemical equilibirum, including the law of mass action and the Nernst equation. Other processes are irreversible and require consideration of reaction mechanisms and rates. The chemical composition of the crustal rocks of the Earth and the composition of the ocean and the atmosphere are significant in evaluating sources of solutes in natural freshwater. The ways in which solutes are taken up or precipitated and the amounts present in solution are influenced by many environmental factors, especially climate, structure and position of rock strata, and biochemical effects associated with life cycles of plants and animals, both microscopic and macroscopic. -from Author
Provides professionals and students in disciplines other than chemistry who need a concise and reliable guide to key concepts in environmental chemistry with the fundamental science and necessary calculations for applying them. This text includes essential background for understanding and solving the most frequent environmental chemistry problems. It includes many useful data tables that are ordinarily scattered throughout the literature, case histories of real-world applications, tools for calculating quick estimates of important quantities and practice problems.