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Municipal Wastewater (municipal + wastewater)
Terms modified by Municipal Wastewater Selected AbstractsThe spatial epidemiology of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) use: a demonstration using a population measure of community drug load derived from municipal wastewaterADDICTION, Issue 11 2009Caleb J. Banta-Green ABSTRACT Aims To determine the utility of community-wide drug testing with wastewater samples as a population measure of community drug use and to test the hypothesis that the association with urbanicity would vary for three different stimulant drugs of abuse. Design and participants Single-day samples were obtained from a convenience sample of 96 municipalities representing 65% of the population of the State of Oregon. Measurements Chemical analysis of 24-hour composite influent samples for benzoylecgonine (BZE, a cocaine metabolite), methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA). The distribution of community index drug loads accounting for total wastewater flow (i.e. dilution) and population are reported. Findings The distribution of wastewater-derived drug index loads was found to correspond with expected epidemiological drug patterns. Index loads of BZE were significantly higher in urban areas and below detection in many rural areas. Conversely, methamphetamine was present in all municipalities, with no significant differences in index loads by urbanicity. MDMA was at quantifiable levels in fewer than half the communities, with a significant trend towards higher index loads in more urban areas. Conclusion This demonstration provides the first evidence of the utility of wastewater-derived community drug loads for spatial analyses. Such data have the potential to improve dramatically the measurement of the true level and distribution of a range of drugs. Drug index load data provide information for all people in a community and are potentially applicable to a much larger proportion of the total population than existing measures. [source] A performance comparison of individual and combined treatment modules for water recyclingENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2005Stuart Khan Abstract An Advanced Water Recycling Demonstration Plant (AWRDP) was commissioned and constructed by the Queensland State Government in Australia. The AWRDP was used to study the effectiveness of a variety of treatment processes in the upgrading of municipal wastewater for water recycling applications. The AWRDP consists of eight modules, each housing an individual specific treatment process. These processes are flocculation, dissolved air flotation, dual media filtration, ozonation, biological activated carbon adsorption, microfiltration, reverse osmosis, and ultraviolet disinfection. The individual performances of the treatment processes were determined, as well as their interdependence in series. A range of chemical water quality parameters were investigated. The study provides a broad process comparison on the basis of an important catalogue of these key parameters. This will be valuable in the selection and optimization of treatment processes trains in full-scale water recycling applications. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Investigating the link between pulp mill effluent and endocrine disruption: Attempts to explain the presence of intersex fish in the Wabigoon River, Ontario, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2010Michael S. Pollock Abstract The ability of some pulp mill effluents (PME) to act as reproductive and endocrine disrupters in fish is well documented in the literature. However, changes are not always consistent with regard to species, gender, hormones, or reproductive effects. In the present study, the presence of the first intersexed fish that, to our knowledge, has been found in a Canadian river exposed to PME, is reported. A field survey of the Wabigoon River near Dryden, Ontario, in the fall of 2000 found intersexed walleye (Sander vitreus vitreus) with significantly altered hormone levels and reduced gonad size. The Wabigoon River receives discharge from a bleached kraft pulp and paper mill and a municipal wastewater (MWW) plant. It also has historical sediment contamination (wood fiber mats) contributing to extended periods of low dissolved oxygen under low flow, drought conditions. A mesocosm-based partial life cycle test exposing fathead minnows (Pimephales promelas) to reference water, 20% effluent volume to river volume (v/v), 40% (v/v), or 60% (v/v) PME as well as a field survey of the walleye in the Wabigoon River were conducted. The only change in our mesocosm exposure was a decrease in testosterone in males with increasing effluent concentration and vitellogenin induction in males exposed to 60% (v/v) effluent. These results did not reflect the magnitude of endocrine disruption seen in the wild fish survey. Several hypotheses that may explain these discrepancies are proposed. Specifically, evidence is offered from published studies indicating that either hypoxia or MWW, alone or in combination with PME, may explain the discrepancy between our field experiment and the wild fish survey. The present study illustrates the complexities of multistressor receiving environments and the need for the development of cumulative effects assessment approaches. Environ. Toxicol. Chem. 2010;29:952,965. © 2010 SETAC [source] Antidepressants and their metabolites in municipal wastewater, and downstream exposure in an urban watershedENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2010Chris D. Metcalfe Abstract Antidepressants are a widely prescribed group of pharmaceuticals that can be biotransformed in humans to biologically active metabolites. In the present study, the distribution of six antidepressants (venlafaxine, bupropion, fluoxetine, sertraline, citalopram, and paroxetine) and five of their metabolites was determined in a municipal wastewater treatment plant (WWTP) and at sites downstream of two WWTPs in the Grand River watershed in southern Ontario, Canada. Fathead minnows (Pimephales promelas) caged in the Grand River downstream of a WWTP were also evaluated for accumulated antidepressants. Finally, drinking water was analyzed from a treatment plant that takes its water from the Grand River 17 km downstream of a WWTP. In municipal wastewater, the antidepressant compounds present in the highest concentrations (i.e., >0.5 µg/L) were venlafaxine and its two demethylation products, O - and N -desmethyl venlafaxine. Removal rates of the target analytes in a WWTP were approximately 40%. These compounds persisted in river water samples collected at sites up to several kilometers downstream of discharges from WWTPs. Venlafaxine, citalopram, and sertraline, and demethylated metabolites were detected in fathead minnows caged 10 m below the discharge from a WWTP, but concentrations were all <7 µg/kg wet weight. Venlafaxine and bupropion were detected at very low (<0.005 µg/L) concentrations in untreated drinking water, but these compounds were not detected in treated drinking water. The present study illustrates that data are needed on the distribution in the aquatic environment of both the parent compound and the biologically active metabolites of pharmaceuticals. Environ. Toxicol. Chem. 2010;29:79,89. © 2009 SETAC [source] Ultra-trace analysis of multiple endocrine-disrupting chemicals in municipal and bleached kraft mill effluents using gas chromatography,high-resolution mass spectrometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2008Michael G. Ikonomou Abstract A comprehensive gas chromatographic,high-resolution mass spectrometric (GC-HRMS),based method was developed that permitted the simultaneous determination of 30 estrogenic endocrine-disrupting chemicals (EDCs) and related compounds, including surfactants, biogenic and synthetic steroids, fecal sterols, phytoestrogens, and plasticizers, in wastewater. Features of the method include low sample volume (,40 ml), optimized Florisil® cleanup to minimize matrix interferences and optimized analyte derivatization to improve sensitivity via GC-HRMS. Detection limits were in the low- to mid-ng/L range, and recoveries were greater than 60% for most target analytes. This new method allows for high throughput analysis of many organic wastewater contaminants in a complex matrix with relative standard deviation of less than 15% for most measurable compounds. The applicability of the method was demonstrated by examining wastewater samples from different origins. Compounds such as di(2-ethylhex-yl)phthalate, cholesterol, cholestanol, and other cholesterol derivatives were measured in much higher concentrations in untreated sewage and were reduced substantially in concentration by the treatment process. However, steroidal compounds, particularly estrone (E1), 17,-estradiol (E2), and estriol (E3), as well as plant sterols (except stigmastanol), were greater in the treated municipal wastewater versus the untreated effluent. Plant and fungi sterols, stigmastanol and ergosterol, were found largely associated with bleached kraft mill effluent (BKME) as compared to the municipal effluents. [source] Effects of irrigation with treated municipal wastewater on soil properties in arid and semi-arid regions,IRRIGATION AND DRAINAGE, Issue 5 2009Sayyed Hassan Tabatabaei eaux usées; méthode d'irrigation; transports de soluté; zone aride Abstract The use of municipal wastewater for irrigation needs special management. This is due to the environmental and health hazards. In this study, secondary treated municipal wastewater was used in five irrigation treatments. These treatments were as follows: furrow irrigation with normal water (FN), drip irrigation with wastewater (DI), subsurface drip irrigation in 15,cm depth with wastewater (SDI15), subsurface drip irrigation in 30,cm depth with wastewater (SDI30), and furrow irrigation with wastewater (FW). The results showed that the application of DI and SDI sand filters causes a decrease in wastewater index pollution, including 50.1% BOD5, 98.9% total count, 97.6% total coliform, 93.2% faecal coliform, 57.1% nematode, 81% total nitrogen, 52% N-NO3, 84% N-NH4 and 44% total suspended solids. In addition, the application of the SDI system causes a decrease in the moisture content of the soil surface, which decreases total coliform and faecal coliform on the soil surface. The average values for these parameters show no significant difference (5% level) between SDI treatments and FN. The results of this research also show that in the case of SDI with its minimal leaching, prevalence contamination (such as N-NO3) was minimized as a result of the usage of wastewater at depth and in groundwater. Moreover, in SDI treatments, the maximum EC and SAR leaching are observed at 60,cm depth, whereas in the FW this leaching is observed deeper than 90,cm. Copyright © 2008 John Wiley & Sons, Ltd. L'utilisation des eaux usées municipales pour l'irrigation nécessite une gestion spéciale afin d'éviter les risques pour la santé et l'environnement. Dans cette étude des eaux usées municipales de l'usine d'Ispahan avec traitement secondaire ont été utilisées dans cinq traitements d'irrigation. Ces traitements étaient les suivants: irrigation à la raie avec de l'eau normale (FN), l'irrigation au goutte-à-goutte avec des eaux usées (DI), irrigation en sub-surface à 15,cm de profondeur avec des eaux usées (SDI15), idem à 30,cm (SDI30), et irrigation à la raie avec des eaux usées (FW). Les résultats de cette recherche montrent que l'utilisation de filtres à sable dans DI et SDI a provoqué une diminution des index de pollution des eaux usées: 50,1% de la DBO5, 98,9% de la quantité totale, 97,6% des coliformes totaux, 93,2% des coliformes fécaux, 57,1% des nématodes, 81% de l'azote total, 52% de N-NO3, 84% de N-NH4 et 44% des matières en suspension. En outre l'application de SDI a entraîné une diminution de l'humidité de la surface du sol, ce qui a diminué les coliformes totaux et de coliformes fécaux en surface. Les valeurs moyennes pour ces paramètres n'ont révélé aucune différence significative (seuil 5%) entre les traitements SDI et FN. Les résultats de cette recherche ont également montré que avec SDI du fait d'une infiltration moindre, la contamination de prévalence (tels que le N-NO3) est minimisé du fait de l'utilisation des eaux usées en profondeur et des nappes phréatiques. En outre avec SDI les lessivages maximum de CE et de SAR ont été observées à 60,cm de profondeur alors qu'avec FW ce lessivage a été observé au-dessous de 90,cm. Copyright © 2008 John Wiley & Sons, Ltd. [source] Brackish water subirrigation for vegetables,IRRIGATION AND DRAINAGE, Issue 2 2003R. M. Patel eaux saumâtres; irrigation souterraine; poivron vert; pommes de terre Abstract As freshwater resources for irrigation are being depleted rapidly, recent emphasis has been on the development of nonconventional water sources: reuse of agricultural drainage water, use of industrial or municipal wastewater, and use of brackish water for irrigation. Experiments conducted in field lysimeters over three seasons sought to investigate the feasibility of using brackish water for growing moderately sensitive crops. Brackish waters, with salinity levels of 1, 5 and 9 dS m,1, were used. In 1993 the effects of a factorial combination of three subirrigation water salinity levels, two water table depths and four NPK fertilizer combinations on salt buildup in an initially nonsaline soil and on green pepper (Capsicum annuum L.) performance were assessed. A gradual increase in soil solution salinity (ECsw) from the water table to the soil surface was evident; however, throughout the growing season, the ECsw did not reach a level that could seriously damage the crop. There was no significant difference in pepper yields due to either salinity of subirrigation water or water table depth. In 1994, two potato (Solanum tuberosum L.) cultivars were grown in the soil, which was salinized with 3.5 dS m,1 water before planting tubers. The salt buildup pattern was similar to that observed in 1993; however, the ECsw levels were higher in 1994 due to the higher initial soil salinity. Moreover, a decrease in ECsw was observed near the water table in lysimeters subirrigated with 1 dS m,1 water. For both cultivars, no significant difference in tuber yield was observed due to either water table depth or subirrigation water salinity. In 1995, three potato cultivars were grown in a nonsaline soil as well as a soil presalinized with 2 dS m,1 water. In the topsoil layer, higher rate of increase in ECsw was observed in the saline soil compared to the nonsaline soil. No significant difference in total tuber yield was observed due to either the initial soil salinity levels or subirrigation water salinity levels. Brackish water with salinity levels of up to 9 dS m,1, when applied through subirrigation, could be used to successfully produce green peppers and potatoes under semiarid to arid conditions. Copyright © 2002 John Wiley & Sons, Ltd. RÉSUMÉ Comme les ressources en eau douce utilisées poor l'irrigation s'épuisent rapidement, les récentes recherches tentent de mettre l'emphase sur le développement de sources d'eau non-conventionnelles: la réutilisation de l'eau de drainage agricole, l'utilisation des eaux usées municipales et des eaux saumâtres pour l'irrigation des cultures. Lors de pénuries d'eau douce les eaux saumâtres ont été utilisées pour l'irrigation souterraine de maïs, mais la salinité de la couche supérieur du sol a été réduite en raison de la pluie. Dans les régions arides et semi-arides cette méthode s'est limitée à quelques essais seulement. En raison des quantités limitées d'eau de bonne qualité, on ne peut irriguer de vastes étendues agricoles en régions arides. Or, si l'utilisation des eaux saumâtres s'avérait un succès il serait possible d'améliorer les rendements agricoles. Il est donc nécessaire d'évaluer l'utilisation des eaux saumâtres dans les systèmes d'irrigation souterrains en milieu aride. Des expériences en lysimètres au cours de trois saisons, dans le but d'étudier la faisabilité d'utiliser des eaux saumâtres pour l'irrigation souterraine de cultures moyennement sensibles, furent entreprises en 1993 et 1994. Des eaux saumâtres avec des niveaux de salinité de 1, 5 et 9 dS m,1, furent utilisés. En 1993, les effets d'une combinaison factorielle de trois niveaux de salinité, deux profondeurs de nappe phréatique et quatre combinaisons de fertilisation NPK ont servi à évaluer l'accumulation de sel dans un sol initialement non-salin où le poivron vert (Capsicum annuum L.) a été cultivé. Une augmentation graduelle de la salinité de la solution du sol, de la nappe d'eau souterraine jusqu'à la surface, fut évidente. Bien que durant la saison de croissance, la conductivité électrique de la solution du sol (ECsw) n'ait pas atteint un niveau qui aurait pu endommager sérieusement la culture. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative les rendements de poivrons. En 1994, deux cultivars de pommes de terre (Solanum tuberosum L.) furent cultivés dans un sol rendu salin, après avoir été irrigué avec une eau d'un niveau de salinité de 3.5 dS m,1, préalablement à la plantation des tubercules. L'accumulation de sel suivit une tendance semblable à celle observée en 1993. Cependant, les niveaux de ECsw enregistrés en 1994 furent plus élevés en raison du taux de salinité initial plus élevé. De plus, une baisse de ECsw fut observée près de la nappe d'eau souterraine dans les lysimètres irrigués avec une eau d'un niveau de salinité de 1 dS m,1. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative le rendement de pommes de terre de chacun des cultivars. En 1995, trois cultivars de pommes de terre ont été cultivés dans un soil non salin ainsi que dans un sol rendu salin au moyen d'une eau avec une conductivité électrique de 2 dS m,1. Dans la couche supérieure du sol, un plus important taux d'augmentation de conductivité électrique a été observé dans le sol salin que dans le sol non salin. Il n'y a pas eu de différence significative observée en raison des taux initiaux de salinité ou encore en raison des taux de salinité de l'eau dans le système d'irrigation souterrain. Cette étude suggère que les eaux saumâtres d'un niveau de salinité jusqu'à 9 dS m,1 pourraient être utilisées dans les systèmes d'irrigation souterrains pour la culture du poivron vert et de la pomme de terre en régions semi-arides et arides. Copyright © 2002 John Wiley & Sons, Ltd. [source] Sequential anaerobic/aerobic biological treatment of olive mill wastewater and municipal wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2006Nikolaos Gizgis Abstract This work investigated the efficiency of the combined anaerobic/aerobic biological co-treatment of olive mill wastewater and primary municipal wastewater. A laboratory-scale (6.5 L) upflow anaerobic sludge bed reactor received a mixture of olive mill wastewater and primary municipal wastewater at a loading rate ranging between 3 and 7 kg chemical oxygen demand (COD) m,3 day,1. The input COD concentration ranged between 1800 and 4400 mg L,1. The anaerobic reactor was operated at mesophilic conditions (35 °C). The effluent organic load was between 400 and 600 mg COD L,1, while the suspended solids removal efficiency varied between 75 and 95%. Average biogas production ranged between 3 and 4 L g,1 COD removed. The anaerobic reactor effluent was further treated in a laboratory-scale activated sludge treatment plant. Aerobic treatment reduced the organic load even further to 85,175 mg COD L,1. However, the final effluent still retained a significant level of colour. Removal of colour was possible by ozonation or coagulation. Finally, the treated effluent was non-ecotoxic, as indicated by the Daphnia magna toxicity test. This treatment method showed that it is feasible to treat olive mill wastewater in a municipal wastewater treatment plant by means of a high-rate anaerobic reactor located between the primary clarifier and the aeration tank. Copyright © 2006 Society of Chemical Industry [source] Simultaneous organic carbon and nitrogen removal in an SBR controlled at low dissolved oxygen concentrationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001Peng Dangcong Abstract Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8,mg,dm,3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4,kg COD m,3 d,1 and 0.24,kg NH3 -N m3 d,1) and efficiencies (COD, NH3 -N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry [source] The effect of recycle ratio on nitrogen removal in the combined pre-denitrification/nitrification biofilter systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001Ren-Jie Chiou Abstract Previous research has shown that nitrogen in municipal wastewater could be eliminated by a biofilter system. This study investigates the effect of the recycle ratio on total nitrogen removal and the nitrogen component in the effluent. In this study, a system combining pre-denitrification/nitrification biofilters was set up. The experiments which varied the recycle ratio of the nitrifying solution to the influent were carried out in order to determine the amount of the total nitrogen removal and the form of nitrogen in the effluent. These experimental results show that total nitrogen removal might be dependent on nitrification but not on denitrification. Although the operation at a low recycle ratio would result in a lower value of total nitrogen removal, the NH3 -N content of the effluent would be lower and the flow condition would be more stable. In comparison, operation at a higher recycle ratio would result in a lower NO3, -N content in the effluent, while the NH3 -N content in the effluent would be higher. At a recycle ratio of 2.5, the total nitrogen removal is at its maximum. The relationship between specific nitrification rate and recycle ratio is also discussed. © 2001 Society of Chemical Industry [source] Clonal groups of high-level gentamicin-resistant Enterococcus faecium isolated from municipal wastewater and clinical samples in Tehran, IranLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009M. Saifi Abstract Aims:, Clonality among high-level gentamicin-resistant Enterococcus faecium (HLGR-EF) isolates obtained from clinical and sewage treatment plants (STP) were investigated using PhePlate system (PhP), ribotyping and pulsed-field gel electrophoresis (PFGE). Methods and Results:, During 1 year study (September 2005,2006), a total of 106 HLGR-EF isolates were collected from clinical (n = 48) and STP (n = 58) samples in Tehran, Iran. Biochemical fingerprinting of these isolates using the PhP showed the presence of 21 PhP types (diversity index, Di = 0·97) among the clinical and 21 PhP types (Di = 0·91) among the STP isolates. Representative isolates of each PhP type (n = 42) were further characterized by the ribotyping method. Sixteen ribotypes were identified among the isolates with five types shared between the clinical and STP isolates. PFGE recognized 24 clonal types among these isolates with three pulsotypes shared between the clinical and STP isolates. Combination of the two techniques (PFGE and ribotyping) resulted in 24 (Di = 0·96) and 16 (Di = 0·93) types among the strains isolated from clinical and STP samples, respectively. Conclusions:, We concluded that the combination of PhP typing, ribotyping and PFGE could be extremely discriminatory when examining HLGR-EF isolates. Significance and Impact of the Study:, The emergence of highly diverse HLGR-EF population in Iran is of serious concern especially because of their multi-resistances. [source] Estimation of Biological Kinetic Parameters from a Continuous Integrated Ozonation-Activated Sludge System Treating Domestic WastewaterBIOTECHNOLOGY PROGRESS, Issue 6 2000Fernando J. Beltrán The feasibility of treating municipal wastewater by a combined ozone-activated sludge continuous flow system was studied. Lab-scale experiments of both single activated sludge and combined ozone-activated sludge processes were carried out to determine the kinetic coefficients of the biological stage. The results obtained indicated a clear improvement in the kinetic parameters of the aerobic oxidation when a pre-ozonation stage was applied. Particularly, COD removal and nitrification rates were highly increased. The biokinetic parameters were also used to simulate and optimize the continuous reaction system. From the model prediction it was concluded that the integrated process (i.e., ozone-ASP) may significantly increase the waste reduction capacity. The results presented here provide a useful basis for further scaling up and efficient operation of ozone-ASP units in wastewater treatment processes. [source] Impact of five selected xenobiotics on isolated ammonium oxidizers and on nitrifying activated sludgeENVIRONMENTAL TOXICOLOGY, Issue 4 2006S. N. Dokianakis Abstract Sewage treatment plants (STPs) are usual receptors of xenobiotic compounds that have to be cotreated with municipal wastewaters before being discharged to the water environment. The presence of organic contaminants, such as surfactants, polycyclic aromatic hydrocarbons (PAHs), phthalates, and their primary degradation products in the influents of STPs may inhibit irreversibly sensitive biological processes, such as nitrification. The first step of nitrification, i.e., the oxidation of ammonium to nitrite (nitritification), is particularly sensitive. Inhibition of this step under uncontrolled conditions may completely inhibit biological nitrogen removal. The aim of this work was to study the possible inhibitory effect of five selected xenobiotics on (a) a mixed culture of ammonium-oxidizing bacteria isolated from activated sludge and (b) nitrifying activated sludge directly. The xenobiotics that were tested include nonylphenols (NP), nonylphenolethoxylates (NPEO), linear alkylbenzene sulfonates (LAS), di(2-ethylhexyl) phthalate (DEHP), as a representative phthalate ester, and the PAH phenanthrene. Remarkable inhibitory effects for all tested compounds were observed in this study even at xenobiotic concentrations as low as 1 mg/L. The observed inhibition of xenobiotics on nitrifying activated sludge was less pronounced, because of the masking effect exerted by the sludge flocs, but was still significant for many of the tested substances at concentrations up to 10 mg/L. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 310,316, 2006. [source] Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft-shell clam, Mya arenariaENVIRONMENTAL TOXICOLOGY, Issue 3 2002C. Blaise Abstract A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the St. Lawrence River estuary (Quebec, Canada) was undertaken to study the possible effects of anthropogenic contaminant input on soft-shell clam (Mya arenaria) populations. Bivalve sampling sites were selected because they reflected a range of areas representative of either no known (or apparent) pollution sources or of areas potentially influenced by different gradients and types of contamination sources. The most upstream site selected in the Saguenay Fjord, nearest to a highly populated and industrialized sector, and the most downstream site, near its mouth with the St. Lawrence River estuary, spanned a distance of some 70 km and encompassed the entire intertidal area suitable for Mya arenaria habitat. To measure effects in collected animals, we used a comprehensive battery of biomarkers composed of metallothionein-like proteins (MT), 7-ethoxyresorufin O-deethylase activity (EROD), DNA damage (DD), lipid peroxidation (LPO), vitellinlike proteins (Vn), phagocytosis (PHAG), nonspecific esterase (NspE) activity, and condition factor (weight-to-length ratio of clams). Vn, PHAG, DD, and NspE biomarkers were assayed in hemolymph (or hemocytes), whereas others (MT, EROD, LPO) were determined in the digestive gland. Whole-tissue metal content was also quantified in clams collected in the spatial survey. The spatial survey conducted in June 1997 showed significant effects at all sites, and principal component analysis indicated in addition that the more important responses were linked to the MT, LPO, and NspE biomarkers. Clams collected from sites closest to the upstream reaches of the fjord generally displayed higher levels of tissue metals (cadmium, manganese), as well as greater responses of NspE activity, MT, LPO, and PHAG. Animals collected from sites influenced by municipal wastewaters had higher levels of Vn, suggesting the presence of environmental estrogens. The results of the temporal survey (six monthly samplings of clams at three sites from May through October, 1997) showed that the bivalve reproductive cycle (vitellogenesis and spawning) can modulate the expression of several biomarkers. Vn levels, for example, were positively correlated with DD and EROD and negatively correlated with MT, suggesting that reproduction can influence the susceptibility of clams to some contaminants. Discrimination analysis over the 6 months of sampling revealed that the mean value of the discriminant function changed significantly over time, suggesting important changes in the relative contribution of each biomarker. In short, this study has provided evidence that clam populations in the Saguenay Fjord are impacted by multiple sources of contamination whose effects can be modulated by reproduction. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 170,186, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10048 [source] | |||||||||||||