The use of XAD-resins for the detection of mutagenic activity in water: II. Studies with drinking water

The combined XAD-4/8-Ames test procedure for concentrating and detecting trace amounts of organic mutagens, as already described for surface water, is shown to be suitable for drinking water as well. DMSO is as effective as acetone in eluting the adsorbed mutagens, and optimal recovery of overall mutagenic activity is observed at a flow rate of 2–4 bed volumes/min. The drinking water of 6 cities in The Netherlands, which prepare their drinking water from the rivers Rhine and Meuse, has been tested for mutagenic activity. Mutagenic activity could be demonstrated in 4 cities. Dose-related responses are observed with concentrates of as little as 500 ml of drinking water and the 4 cities clearly differ with regard to the type of mutations induced (TA 98 or TA 100) and the effect of metabolic activation. The absence of mutagenic activity in drinking water of 2 cities indicates that by a proper combination of treatment processes the organics which are responsible for the detected mutagenic activity in drinking water can be removed to a high degree.     

Formation of mutagenic activity during surface water preozonization and its removal in drinking water treatment

The influence of preozonization, coagulation and double layer filtration on formation and removal of mutagenic activity was studied using XAD-8 extracts collected from neutral and acidic solutions and assaying them in the Salmonella typhimurium microsomal assay.Preozonization of surface water produced direct acting frame shift mutagens which were adsorbed on XAD-8 from neutral solutions. This phenomenon was shown to be dependent on the ozone dose applied. Coagulation with different chemicals and subsequent direct filtration partially reduced the mutagenic activity.     

The mutagenic potentials of tap water samples in Shanghai

The tap water samples were collected from the users' ends in several areas of Shanghai, which is located in Taihu Lake basin, Eastern China. Source water samples were also collected from two municipal source water facilities at the same time. Samples were assayed by three different short-term mutagenicity test systems: Salmonella/microsome assay (Ames test), the Arabinose resistance test (Ara test) and the SOS/umu test. The data showed that two source water samples did not display direct mutagenic potentials. Two tap water samples from city north, which were directly from Yangtze River, were also not mutagenic. Water samples from city south and middle which used source water originating from Taihu Lake were proved to be contaminated with mutagenic potentials by three different assay techniques. The boiled water displayed an even stronger mutagenic potential compared to its original tap water. The molecular mechanism of mutagenicity was associated with a reading frame-shifting potential. GC-MS analysis of tap water extracts from city middle and corresponding source water was compared. Qualitatively similar spectra were observed except for the peaks of three chlorinated aromatic hydrocarbon compounds, which existed only in the tap water. Since the water source has been polluted, raw water was heavily chlorinated in order to sterilize. More toxic compounds, including mutagens, might form during the multi-chlorination. Caution about the possibility of elevated cancer risks in the population that consumes heavily chlorinated water should be kept in mind. A cohort study in the residents of Shanghai is required.     

用人淋巴细胞微核试验检测地面水致突变性

用胞质阻断微核试验（CBMN）来检测浙江某地区地面水有机提取物的致突变性,并与Ames试验结果进行了比较。结果表明,该水样中含有微量致突变物,CBMN试验和Ames试验结果基本相符,说明CBMN试验用作检测地面水致突变性是可行的,但灵敏度略低于Ames试验。     

Determination of mutagenic potential and organic contaminants of Great Lakes drinking water

Extracts of organic compounds were obtained, using XAD-2 macroreticular resin, from drinking water supplies in 12 Great Lakes municipalities. The extracts were tested for mutagenic potential using the Salmonella/mammalian-microsome assay and analysed for organochlorine pesticides, polyaromatic hydrocarbons, organophosphorous pesticides and trialkyl-arylphosphates. Grab samples of drinking water were also analysed for volatile organic compounds. Dose-related increases in mutagenicity were found in extracts from 11 of the drinking water supplies.     

Characterization of industrial aqueous discharges by the TLC/Ames’ assay

The $\text{in situ}$ detection of mutagens by the TLC/Ames’ assay has been applied to aqueous discharges from a textile plant. The samples were fractionated in acid/neutral and basic fractions which subsequently were subject to the TLC/Ames’ test. The results demonstrate the presence of a number of both direct and indirect mutagens in the waste water. The chemical properties of these compounds are discussed in light of their chromatographic behaviour. The applicability of this method for characterizing mutagens in complex mixtures is demonstrated.     

A simplified method for sampling and analysis of high volume surface water for organic contaminants using XAD-2

A simple compressed-gas driven system for field processing and extracting water for subsequent analyses of hydrophobic organic compounds is presented. The pumping device is a pneumatically driven pump and filtration system that can easily clarify at 4 L/min. The extraction device uses compressed gas to drive filtered water through two parallel XAD-2 resin columns, at about 200 mL/min. No batteries or inverters are required for water collection or processing. Solvent extractions were performed directly in the XAD-2 glass columns. Final extracts are cleaned-up on Florisil cartridges without fractionation and contaminants analyzed by GC-MS. Method detection limits (MDLs) and recoveries for dissolved organic contaminants, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides are reported along with results of surface water analysis for the San Francisco Bay, CA.     

Approach for detecting mutagenicity of biodegraded and ozonated pharmaceuticals, metabolites and transformation products from a drinking water perspective

Many pharmaceuticals and related metabolites are not efficiently removed in sewage treatment plants and enter into surface water. There, they might be subject of drinking water abstraction and treatment by ozonation. In this study, a systematic approach for producing and effect-based testing of transformation products (TPs) during the drinking water ozonation process is proposed. For this, two pharmaceutical parent substances, three metabolites and one environmental degradation product were investigated with respect to their biodegradability and fate during drinking water ozonation. The Ames test (TA98, TA100) was used for the identification of mutagenic activity present in the solutions after testing inherent biodegradability and/or after ozonation of the samples. Suspicious results were complemented with the umu test. Due to the low substrate concentration required for ozonation, all ozonated samples were concentrated via solid phase extraction (SPE) before performing the Ames test. With the exception of piracetam, all substances were only incompletely biodegradable, suggesting the formation of stable TPs. Metformin, piracetam and guanylurea could not be removed completely by the ozonation process. We received some evidence that technical TPs are formed by ozonation of metformin and piracetam, whereas all tested metabolites were not detectable by analytical means after ozonation. In the case of guanylurea, one ozonation TP was identified by LC/MS. None of the experiments showed an increase of mutagenic effects in the Ames test. However, the SPE concentration procedure might lead to false-positive results due to the generation of mutagenic artefacts or might lead to false-negative results by missing adequate recovery efficiency. Thus, these investigations should always be accompanied by process blank controls that are carried out along the whole ozonation and SPE procedure. The study presented here is a first attempt to investigate the significance of transformation products by a systematic approach. However, the adequacy and sensitivity of the methodology need to be further investigated. The approach of combining biodegradation and ozonation with effect-based assays is a promising tool for the early detection of potential hazards from TPs as drinking water contaminants. It can support the strategy for the evaluation of substances and metabolites in drinking water. A multitude of possible factors which influence the results have to be carefully considered, among them the selectivity and sensibility of the mutagenicity test applied, the extraction method for concentrating the relevant compounds and the biocompatibility of the solvent. Therefore, the results have to be carefully interpreted, and possible false-negative and false-positive results should be considered.     

Chemical and biological characterization of emissions from a cereal straw burning furnace

Emissions from a cereal straw through-burning furnace have been characterized by chemical analysis and the Ames $\text{Salmonella/microsome}$ assay. The emissions of polycyclic aromatic hydrocarbons (PAH) were considerable, from 24 to 64 mg per kilo dry fuel. Most of the mutagenic activity was found in the extracts of the particles, while the condensate fractions and the XAD-2 extracts showed much lower mutagenic responses.     

Validation studies of an automated preconcentration water sampler (APS) for chlorinated dibenzo-p-dioxins and dibenzofurans

An Automated Preconcentration Sampler (APS) was developed by the Ontario Ministry of the Environment (MOE) and Carleton University for the determination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in drinking water. The APS employs a two-stage particulate filtration system followed by an XAD-2 resin column. Field and laboratory testing of the APS is required to validate the device before it is put into regular service.The capacity of the APS filtration system is 30 L for a 4 Formazin Turbidity Unit (FTU) input water turbidity and greater than 50 L for a typical treated water. Flushing of a clean XAD-2 resin column with 200 L of spiked water showed that the optimum flowrate in terms of spike breakthrough is equal to three times the resin bed volume per minute. This flowrate is used for APS operation. Testing also showed that no spike breakthrough occurred after 200 L of clean water was flushed through a spiked XAD-2 resin column at flowrates in excess of the APS operating flowrate. Spike testing was also carried out on the filters and results are pending. An analytical comparison between the present MOE sampling and analytical procedure and the proposed APS sampling and analytical procedure using a PCDD/PCDF source water is planned.     

Application of semipermeable membrane device for assessing toxicity in drinking water

Semipermeable membrane devices (SPMDs) mimic passive diffusive transport of bioavailable hydrophobic organic compounds through biological membranes and their partitioning between lipids and environmental levels. Our study was developed on a surface water treatment plant based in Turin, Northern Italy. The investigated plant treats Po River surface water and it supplies about 20% of the drinking water required by Turin city (about one million inhabitants). Surface water (input) and drinking water (output) were monitored with SPMDs from October 2001 to January 2004, over a period of 30 days. The contaminant residues, monthly extracted from SPMDs by dialysis in organic solvent, were tested with the Microtox^TM acute toxic test and with the Ames mutagenicity test. Same extracts were also analyzed with gaschromatography—mass spectrometry technique in order to characterise the organic pollutants sampled, especially Polycyclic Aromatic Hydrocarbons (PAHs).

Although the PAHs mean concentration is about one hundred times lower in the output samples, the mean toxic units are similar in drinking and surface water.

Our data indicate that the SPMD is a suitable tool to assess the possible toxicity in drinking water.     

Adsorption of pesticides on resins

The objective of this work was to assess the capability of organic hydrophobic polymeric resins Amberlite XAD-4 and XAD-7 to remove the pesticides alachlor and amitrole from water. The pesticides adsorption on the two different adsorbents was measured by batch equilibrium technique and isotherm types and parameters were estimated. Two theoretical models were applied based on a Freundlich and a Langmuir isotherms. The effect of pesticides chemical composition and structure as well as the nature of solid surface on the efficiency of adsorption was evaluated. The influence of pH also was studied. In low pH solutions adsorption of amitrole was higher upon the nonionic aliphatic acrylic ester copolymer XAD-7 in comparison to the nonionic, crosslinked macroreticular copolymer of styrene divinylbenzene XAD-4. In neutral and intermediate pH solutions the polar acrylic ester copolymer XAD-7 was more effective to the retention of alachlor. The acrylic ester copolymer showed at pH 3 the lower effectiveness in alachlor removal from water. The data of the adsorption isotherms of pesticides upon the examined polymeric resins seemed to conform to both the Freundlich and the Langmuir isotherm models.     

长江、嘉陵江(重庆段)源水有机提取物的致突变活性及其季节变化

为了确定并比较重庆主城区段长江、嘉陵江源水有机提取物的致突变性及其季节变化规律，分别于春、夏、冬季采用GDX－120大孔树脂，对位于城区上游、城区中段、城区下游以长江、嘉陵江源水的5个水厂的进厂水进行了有机物的浓缩提取。提取物的致突变活性采用经典的Ames试验平板掺入法评估，测试菌株为TA98及TA100，同时做加与不加S9的比较。结果显示，嘉陵江及长江源水的有机提取物均有不同程度的致突变活性。嘉陵江源水明显大于长江源水，城区中段源水明显大于上游段及下游段源水。多数断面显示平水期致突变活较为显著并且移码型致突变性大于碱基置换型致密变性。研究结果提示，城市污染源已导致长江、嘉陵江源水具备致突变活性，控制两江沿岸的各种水污染源已成为当务之急。     

Role of surface functionality in the adsorption of anionic dyes on modified polymeric sorbents

While synthetic polymeric sorbents effectively treat dye wastewaters by adsorption, the underlying mechanisms remain to be understood. This work determined the adsorption of an anionic dye by three polymers differing significantly in surface functionality. Surface functional groups of polymers were indicated in FTIR spectra and quantified by the Boehm titration. In reference to the commercial sorbent XAD-4 with a low degree of functionality, the laboratory synthesized NG-8 had primarily acidic functional groups, whereas its aminated product MN-8 had mainly basic amino groups. Electrophoresis determined the points of zero charge of 4.18, 3.23, and 4.51 for XAD-4, NG-8, and MN-8, respectively. The adsorption of Reactive Black 5 dye (RB5) by all the sorbents on a unit surface area basis increased with decreasing pH. At the same low pH (4.40), the adsorption by NG-8 was similar to that by XAD-4, indicating little influence of protonated (neutral) surface functional groups. In contrast, the adsorption by NG-8 at pH 6.05 was 75% lower than that by XAD-4, resulting apparently from the strong electrostatic repulsion between RB5 and deprotonated (negative) groups. Amination substantially enhanced RB5 adsorption by eliminating acidic groups and creating a positive charge on the surface of MN-8. The adsorptive enhancement was also achieved in the presence of CaCl2, due presumably to the neutralization of negative surface charge by Ca2+ and the RB5-Ca2+ pairing. These results manifest the important role of surface functionality in the adsorption of dyes by synthetic polymers.     

Use of Bioassay Methods to Evaluate Mutagenicity of Ambient Air Collected Near a Municipal Waste Combustor

An ambient air sampling study was conducted around a municipal waste combustor; a primary goal was to develop procedures and methods to evaluate the emissions of organic mutagens resulting from incomplete combustion of municipal waste. The products of Incomplete combustion from incineration include complex mixtures of organics, particularly polycycllc aromatic compounds, which are present after atmospheric dilution and cooling In emissions as semi-volatile or particle bound organic compounds. Combustion emissions are generally recognized as a potential cancer risk since they contain many carcinogenic and mutagenlc polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for the presence of even a few selected chemicals is difficult and provides risk information on only a fraction of the chemicals present. Bioassay methods, however, may be directly applied to evaluate the mutagenic and potential carcinogenic activity of the complex organics from combustion emissions. The Salmonella (Ames) assay was used to determine the mutagenicity associated with particles from ambient air collected near a municipal waste combustor. Dose-response data was generated, and mutagenicity concentrations were calculated to demonstrate the utility of bioassay In assessing the potential Impact of emissions from municipal waste combustion. This phase of study quantified mutagenicity concentrations In ambient air but did not detect organic mutagens that could be attributed to Incinerator emissions.     

Adsorption of branched alkylbenzene sulfonate onto styrene and acrylic ester resins

In this study, a series of acrylic ester resins were prepared and characterized. The adsorption behaviors of sodium 6-dodecyl benzenesulfonate (6-NaDBS) on styrene resin XAD-4 and acrylic ester resins have been studied. As compared to commercial acrylic ester resins Amberlite XAD-7 and Diaion HP2MG, YWB-38, one of the as-prepared resins, exhibits better adsorption properties toward 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir and double-Langmuir models. The two models provide very good fit for all acrylic ester resins over the temperature range studied, whereas fitted results for styrene resin XAD-4 are less accurate. The investigation indicates that the adsorbate molecules are directly adsorbed on acrylic ester resins as a bi-layer, while the molecules are adsorbed on XAD-4 as monolayer formation followed by the establishment of bi-layer. Adsorption kinetics and elution processes were also investigated for further exploring the adsorption behavior and mechanism on styrene resin XAD-4 and YWB-38.     

Surface charge and adsorption from water onto quartz sand of humic acid

The surface charge of humic acid under different conditions of ionic strength, pH, and the presence of various cationic ions (Cu(2+), Zn(2+), Ba(2+), and Ca(2+)) was determined by a titration method using a cationic polyelectrolyte as titrant. Adsorption isotherms in batch experiments of the polymer from water onto quartz sand were determined at 20 degrees C, 40 degrees C, and 60 degrees C and under different conditions of ionic strength, pH, and the presence of various cationic ions (Cu(2+), Zn(2+), Ba(2+), and Ca(2+)). The data indicate significant decrease of humic acid surface charge by decreasing the pH value from 10.0 to 4.1. Similar decrease of humic acid surface charge was observed by increasing either the ionic strength or the affinity of the divalent cation toward the humic acid. At ambient temperature the adsorption of humic acid on the quartz sand seems to be controlled mainly by electrical interaction between the organic particle and the solid substrate. A correlation is found between the surface charge and the adsorbed amount of the polymer, the adsorbed amount increases when the surface charge of humic acid decreases. The increase of the adsorbed amount with the temperature suggests that adsorption process is endothermic.     

Investigating the sources of the mutagenic activity found in a river using the Salmonella assay and different water extraction procedures

In the routine São Paulo state (Brazil) surface water quality-monitoring program, which includes the Salmonella microsome mutagenicity assay as one of its parameters, a river where water is taken and treated for drinking water purposes has repeatedly shown mutagenic activity. A textile dyeing facility employing azo-type dyes was the only identifiable source of mutagenic compounds. We extracted the river and drinking water samples with XAD4 at neutral and acidic pH and with blue rayon, which selectively adsorbs polycyclic compounds. We tested the industrial effluent, raw, and treated water and sediment samples with YG1041 and YG1042 and compared the results with the TA98 and TA100 strains. The elevated mutagenicity detected with YG-strains suggested that nitroaromatics and/or aromatic amines were causing the mutagenicity detected in the samples analyzed. Positive responses for the blue rayon extracts indicated that mutagenic polycyclic compounds were present in the water samples analyzed. The mutagen or mixture of mutagens present in the effluent and water samples cause mainly frameshift mutations and are positive with and without metabolic activation. The Salmonella assay combined with different extraction procedures proved to be very useful in the identification of the origin of the pollution and in the identification of the classes of chemical compounds causing the mutagenic activity in the river analyzed.     

Natural organic matter (NOM) in roof runoff and its impact on the Fe0 treatment system of dissolved metals

The present work investigates the impacts and mechanisms associated with natural organic matter (NOM) in the Fe0 treatment system of Cu2+ and Zn2+ under roof runoff conditions. The NOM in runoff waters was characterized using XAD-4/8 adsorption resins, copper complexation, acidic capacity and liquid chromatography with online carbon detection. Batch kinetic experiments and flow-through configurations were performed and the results of metal removal were elucidated taking into account the characteristics of NOM. Based on the findings, it is shown that NOM influences the removal of metals through several complex pathways. At an un-favored condition for adsorption of metals, i.e., on iron corrosion products, at pH相似文献   

The chemical and biogenotoxic characterization of organic xenobiotics in aquatic sediment materials 1. The application and comparison of chemically non-specific and biogenotoxic methods

The aim of this work was to evaluate the Ames assay and mixed function oxidase (MFO)-Induct Test used in parallel with chemical group tests (ECD fingerprint and PAH estimation) for the characterization of the organic pollution of water sediment materials. Sediment materials were collected from “clean” and relatively heavily polluted locations in the Middle Adriatic Sea, and from some locations in continental Croatia polluted with wastewaters from different enterprises. Characterization of the organic extracts of the sediment materials investigated was performed chemically using UV spectrofluorometry for the determination polyaromatic hydrocarbons (PAH) and gas chromatography for the determination of volatile EC detector sensitive materials. Genotoxic analysis of the extracts was performed using the MFO-Induct Test and mutagenicity testing using the Standard Plate Incorporation Test as described by Maron and Ames with Salmonella typhimurium TA 98. Measurement of the BaPMO enzyme activity in the livers of carp treated i.p. with total extracts of the sediment investigated confirmed that the methanol extracts generally contained more inducing matter than the petroleum ether extracts. Ames assay showed that for all the samples following the elimination of the sulfur, there was an increase in the number of revertants in comparison to the control number, which indicates that the samples contained mutagenic substances. The larger doses of extracts generally demonstrated cytotoxicity, as evidenced by a reduced number of spontaneous revertants in the Salmonella/Microsome Test. Investigation of the correlation of the chemical parameters with the biological parameter showed that the induction of BaPMO exhibited a statistically significant correlation with the level of the ECD fingerprint of the petroleum ether sediment extract.