bluuebunny/crossref_metadata_2025 huggingface dataset:
Perfluoroalkyl compounds in relation to life-history and reproductive parameters in bottlenose dolphins (Tursiops truncatus) from Sarasota Bay, Florida, USA
Authors: Houde Magali , Balmer Brian C. , Brandsma Sicco , Wells Randall S. , Rowles Teri K. , Solomon Keith R. , Muir Derek C. G.
Published: August 2006

Perfluoroalkyl compounds (PFCs) were determined in plasma, milk, and urine of free-ranging bottlenose dolphins (Tursiops truncatus) from Sarasota Bay (FL, USA) during three winter and two summer capture-and-release programs (2002-2005). Plasma and urine samples were extracted using an ion-pairing method. Perfluoroalkyl compounds were extracted from milk samples using acetonitrile, and extracts were cleaned with graphitized nonporous carbon. All extracts were analyzed by high-performance liquid chromatography–tandem mass spectrometry. Mean seasonal sum of PFCs (ΣPFCs) detected in dolphin plasma ranged from 530 to 927 ng/g wet weight. No significant differences (p > 0.05) were found in concentrations between seasons, suggesting a constant exposure to PFCs. Overall, blubber thickness of dolphins did not correlate with PFC concentrations in plasma, suggesting an absence of PFC sequestration in blubber. Sexually immature calves (age, <10 years; mean ΣPFCs, 1,410 ± 780 ng/g wet wt) were significantly more contaminated (p < 0.001) than their mothers (mean ΣPFCs, 366 ± 351 ng/g wet wt). The reproductive history of females had a significant role in the burden of PFC contamination; PFC concentrations in nulliparous females (females that have not been observed with calves) were significantly greater than those detected in uniparous females (females that have been observed with one calf), suggesting an off-loading of PFCs during or after parturition. To investigate this hypothesis, PFCs were analyzed in milk samples (n = 10; mean ΣPFCs, 134 ± 76.1 ng/g wet wt), confirming a maternal transfer of PFCs through lactation in dolphins. Results from the present study showed that young and developing bottlenose dolphins are highly exposed to PFCs. These chemicals also were detected in urine (mean ΣPFCs, 26.6 ± 79 ng/g wet wt), indicating that the urinary system is an important pathway of PFC depuration in dolphins.
Chlorine toxicity to early life stages of freshwater mussels (Bivalvia: Unionidae)
Authors: Valenti Theodore W. , Cherry Donald S. , Currie Rebecca J. , Neves Richard J. , Jones Jess W. , Mair Rachel , Kane Cynthia M.
Published: August 2006

Chlorine (Cl) is a highly toxic, widely used halogen disinfectant that is present in point-source pollution discharges from wastewater treatment plants and industrial facilities. The U.S. Environmental Protection Agency freshwater criteria for Cl are 19 μg total residual Cl (TRC)/L as a maximum 1-h average concentration and 11 μg TRC/L as a maximum 4-d average; however, toxicological data for unionids were not used in these calculations. To address this void in the data, we conducted acute tests with glochidia from several species and 21-d bioassays with three-month-old Epioblasma capsaeformis and three-, six-, and 12-month-old Villosa iris juveniles. The 24-h lethal concentration 50 values for glochidia were between 70 and 220 μg TRC/L, which are 2.5 to 37 times higher than those reported in other studies for cladocerans. Significant declines in growth and survivorship were observed in the 21-d test with E. capsaeformis at 20 μg TRC/L. Lowest-observed-adverse-effects concentrations in bioassays with juvenile V. iris were higher (30–60 μg TRC/L) but showed a significant trend of declining toxicity with increased age. Although endpoints were above water quality criteria, the long life spans of unionids and potential implications of chronic exposure to endangered juvenile mussels still warrant concern.
Leaching of copper, chromium, and boron from treated timber during aboveground exposure
Authors: García-Valcárcel Ana I. , Tadeo José L.
Published: August 2006

Field studies were conducted to evaluate leaching of Cu, Cr, and B from timber treated with a Cr, Cu, and B wood preservative and exposed aboveground in Spanish weathering conditions during one year with a total rainfall of approximately 500 mm. The effect of timber orientation (horizontal for decks and vertical for fences) on metal leaching was assessed. Leaching of metals after one year was higher for decks than for fences, with total amounts of metals leached being 226.6 and 87.8 mg/m2 for Cu, 199.5 and 42.4 mg/m2 for Cr, and 110.1 and 32.6 mg/m2 for B from decks and fences, respectively. Leaching rates did not drop constantly with time, because an increase in metal leaching, except for B, was observed at the end of the year after a long dry period. The order of metal emission varied with cumulative rainfall: Leaching of B was higher than Cr initially, but the opposite occurred at the end of the assay. Total emissions of Cu and Cr obtained in a laboratory assay were lower than those for decks and fences under field conditions when expressed per unit surface area (mg/m2), but they were similar to the values obtained for fences when expressed as a percentage of the initial amount. However, the percentage of B leached from wood was higher in laboratory than in field assays for both orientations, with the amount of B leached per unit surface area under laboratory conditions being higher than that leached from fences but lower than that leached from decks. Emission rates extrapolated to one year from laboratory data underestimated metal leaching from decks and overestimated emissions from fences.
Geckos as indicators of mining pollution
Authors: Fletcher Dean E. , Hopkins William A. , Saldaña Teresa , Baionno Jennifer A. , Arribas Carmen , Standora Michelle M. , Fernández-Delgado Carlos
Published: August 2006

Catastrophic collapse of a mine tailings dam released several million cubic meters of toxic mud and acidic water into the Guadiamar River valley, southern Spain, in 1998. Remediation efforts removed most of the sludge from the floodplain, but contamination persists. Clean-up activities also produced clouds of aerosolized materials that further contaminated the surrounding landscape. Whole-body concentrations of 21 elements in the Moorish wall gecko, Tarentola mauritanica, a common inhabitant of both rural and urban areas, were compared among seven locations. Locations spanned an expected contamination gradient and included a rural and an urban non–mine-affected location, two mine-affected towns, and three locations on the contaminated floodplain. Multivariate analyses of whole-body concentrations identified pollutants that increased across the expected contamination gradient, a trend particularly evident for As, Pb, and Cd. Additionally, higher contaminant concentrations occurred in prey items eaten by geckos from mine-affected areas. Comparison of element concentrations in tails and whole bodies suggests that tail clips are a viable nondestructive index of contaminant accumulation. Our results indicate that areas polluted by the mine continue to experience contamination of the terrestrial food chain. Where abundant, geckos represent useful taxa to study the bioavailability of some hazardous pollutants.
Influence of water quality and associated contaminants on survival and growth of the endangered Cape Fear shiner (Notropis mekistocholas)
Authors: Hewitt Amanda H. , Cope W. Gregory , Kwak Thomas J. , Augspurger Tom , Lazaro Peter R. , Shea Damian
Published: August 2006

The Cape Fear shiner (Notropis mekistocholas) is a recently described cyprinid species endemic to the Cape Fear River Basin of North Carolina, USA. Only five populations of the fish remain; thus, it is listed as endangered by the U.S. Government. Determining habitat requirements of the Cape Fear shiner, including water quality and physical habitat, is critical to the survival and future restoration of the species. To assess water quality in the best remaining and in the historical habitats, we conducted a 28-d in situ bioassay with captively propagated Cape Fear shiners. Fish were deployed at 10 sites in three rivers, with three cages per site and 20 fish per cage. Water and sediment samples were collected and analyzed for selected metals and organic contaminants. Passive sampling devices also were deployed at each site and analyzed for organic contaminants at test termination. Fish survival, growth (as measured by an increase in total length), and contaminant accumulation were measured on completion of the bioassay. Survival of caged fish averaged 76% (range, 53–100%) and varied significantly among sites and rivers. Caged fish accumulated quantities of cadmium, mercury, polychlorinated biphenyls, and other persistent contaminants over the test duration and grew significantly at only four sites. No apparent relations were observed between exposure to or accumulation of a specific contaminant and reduced growth or survival of fish among all the sites. However, a generalized hazard assessment showed that certain sites exhibited trends in cumulative contaminant presence with reduced fish survival and growth, thereby enabling the identification of the existing riverine habitat most suitable for reintroduction or population augmentation of this endangered fish.
Seasonality effects on pharmaceuticals and s-triazine herbicides in wastewater effluent and surface water from the Canadian side of the upper Detroit River
Authors: Hua Wen Yi , Bennett Erin R. , Maio Xui-Sheng , Metcalfe Chris D. , Letcher Robert J.
Published: August 2006

The influence of seasonal changes in water conditions and parameters on several major pharmacologically active compounds (PhACs) and s-triazine herbicides was assessed in the wastewater and sewage treatment plant (WSTP) effluent as well as the downstream surface water from sites on the Canadian side of the upper Detroit River, between the Little River WSTP and near the water intake of a major drinking water treatment facility for the City of Windsor (ON, Canada). The assessed PhACs were of neutral (carbamazepine, cotinine, caffeine, cyclophosphamide, fluoxetine, norfluoxetine, pentoxifylline, and trimethoprim) and acidic (ibuprofen, bezafibrate, clofibric acid, diclofenac, fenoprofen, gemfibrozil, indomethacin, naproxen, and ketoprofen) varieties. The major assessed s-triazine herbicides were atrazine, simazine, propazine, prometon, ametryn, prometryn, and terbutryn. At sampling times from September 2002 to June 2003, 15 PhACs were detected in the WSTP effluent at concentrations ranging from 1.7 to 1,244 ng/L. The PhAC concentrations decreased by as much 92 to 100% at the Little River/Detroit River confluence because of the river dilution effect, with further continual decreases at sites downstream from the WSTP. The only quantifiable s-triazine in WSTP effluent, atrazine, ranged from 6.7 to 200 ng/L and was higher in Detroit River surface waters than in WSTP effluent. Only carbamazepine, cotinine, and atrazine were detectable at the low-nanogram and subnanogram levels in surface waters near a drinking water intake site. Unlike the PhACs, atrazine in the Detroit River is not attributable to point sources, and it is heavily influenced by seasonal agricultural usage and runoff. Detroit River surface water concentrations of carbamazepine, cotinine, and atrazine may present a health concern to aquatic wildlife and to humans via the consumption of drinking water.
Biomagnification of polybrominated diphenyl ether and hexabromocyclododecane flame retardants in the polar bear food chain in Svalbard, Norway
Authors: Sørmo Eugen Gravningen , Salmer Maria Pettersvik , Jenssen Bjørn Munro , Hop Haakon , Bæk Kine , Kovacs Kit Maureen , Lydersen Christian , Falk-Petersen Stig , Gabrielsen Geir Wing , Lie Elisabeth , Skaare Janneche Utne
Published: August 2006

Concentrations of brominated flame retardants (BFRs), including polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), were investigated in an arctic marine food chain consisting of four invertebrate species: polar cod (Boreogadus saida), ringed seals (Pusa hispida), and polar bears (Ursus maritimus). The most abundant BFR, brominated diphenyl ether (BDE)-47, was found in detectable concentrations even in zooplankton, the lowest trophic level examined in this study. Most of the investigated BFRs biomagnified as function of tropic level in the food chain. A noticeable exception occurred at the highest trophic level, the polar bear, in which only BDE-153 was found to increase from its main prey, the ringed seal, indicating that polar bears appear to be able to metabolize and biodegrade most BFRs. In contrast, lower-brominated PBDEs, particularly BDE-47, showed clear signs of bioaccumulation in zooplankton, polar cod, and ringed seals. We suggest that this discrepancy in the fate of BFRs among the different species may be related to greater induction of oxidative detoxification activities in the polar bear. Absorption and debromination rates may be more important for bioaccumulation rates of BFRs in zooplankton, polar cod, and ringed seals. Lipid weight–based concentrations (LWCs) and whole body–based concentrations (WBCs) of BFRs were used to assess biomagnification factors (BMFs). Whole-body concentrations gave the most realistic BMFs, as BMFs derived from LWCs seem to be confounded by the large variability in lipid content of tissues from the investigated species. This study demonstrates that PBDEs and HBCD have reached measurable concentrations even in the lower trophic levels (invertebrates and fish) in the Arctic and biomagnifies in the polar bear food chain.
Effects of cyanobacterial toxins and cyanobacterial cell-free crude extract on germination of alfalfa (Medicago sativa) and induction of oxidative stress
Authors: Pflugmacher Stephan , Jung Katharina , Lundvall Linn , Neumann Stefanie , Peuthert Anja
Published: August 2006

Cyanobacterial toxins have adverse effects on both terrestrial and aquatic plants. Microcystins are cyclic heptapeptides and an important group of cyanotoxins. When lake water contaminated with cyanobacterial blooms is used for spray irrigation, these toxins can come in contact with agricultural plants. During the exposure to these toxins, reactive oxygen species can form. These reactive oxygen species have a strong reactivity and are able to interact with other cellular compounds (lipids, protein, and DNA). Plants have antioxidative systems that will limit the negative effects caused by reactive oxygen species. These systems consist of enzymes, such as superoxide dismutase, catalase, and ascorbate peroxidase, and nonenzymatic substances, such as reduced glutathione or vitamins. The aim of the present study was to investigate the effects of cyanobacterial toxins (microcystins and anatoxin-a) and cyanobacterial cell-free crude extract on alfalfa (Medicago sativa) seedlings. Inhibition of germination and root growth was observed with toxin concentrations of 5.0 μg/L. Also, oxidative damage, such as lipid peroxidation, was detected after the exposure of alfalfa seedlings to the toxin. Reactive oxygen detoxifying enzymes were elevated, showing a marked response in alfalfa to oxidative stress caused by the exposure to cyanobacterial metabolites that might influence the growth and development of these plants negatively.
Perfluorinated compounds in streams of the Shihwa industrial zone and Lake Shihwa, South Korea
Authors: Rostkowski Pawel , Yamashita Nobuyoshi , So Iris Man Ka , Taniyasu Sachi , Lam Paul Kwan Sing , Falandysz Jerzy , Lee Kyu Tae , Kim Seung Kyu , Khim Jong Seong , Im Sook Hyeon , Newsted John L. , Jones Paul D. , Kannan Kurunthachalam , Giesy John P.
Published: August 2006

Concentrations of perfluorinated alkyl compounds (PFAs), including perfluorooctane sulfonate (PFOS), perfluorohexanesulfonate, perfluorobutanesulfonate, perfluorooctanesulfonamide, perfluorodecanoate, perfluorononanoic acid, perfluorooctanoate (PFOA), perfluoroheptanoate, and perfluorohexanoate, were measured in the streams of the Shihwa and Banweol industrial areas on the west coast of South Korea as well as the adjacent Lake Shihwa (an artificial lake) and Gyeonggi Bay. Perfluorinated alkyl compounds were concentrated from water using solid-phase extraction and were identified and quantified by liquid chromatography/triple-quadrapole tandem mass spectrometry. Of the PFAs measured, PFOS and PFOA occurred at the greatest concentrations. Concentrations of PFOS ranged from 2.24 to 651 ng/L, and concentrations of PFOA ranged from 0.9 to 62 ng/L. The concentrations of PFOS observed in Lake Shihwa were among the greatest ever measured in the environment. These results suggest local industrial sources of PFOS and PFOA as well as other PFAs. Because of dilution, the greatest concentrations occur in a rather restricted area, near the points of discharge of the streams that empty into the lake. The greatest measured concentration of PFOS exceeded the threshold for effects predicted for predatory birds consuming aquatic organisms continuously exposed to this level.
Toxicity models of pulsed copper exposure toPimephales promelasandDaphnia magna
Authors: Butcher Jonathan , Diamond Jerry , Bearr Jonathan , Latimer Henry , Klaine Stephen J. , Hoang Tham , Bowersox Marcus
Published: August 2006

Semiempirical models are useful for interpreting the response of aquatic organisms to toxicants as a function of exposure concentration and duration. Most applications predict cumulative mortality at the end of the test for constant exposure concentrations. Summary measures, such as the median lethal concentration, are then estimated as a function of concentration. Real-world exposures are not constant. Effects may depend on pulse timing, and cumulative analysis based only on integrated exposure concentration is not sufficient to interpret results. We undertook a series of pulsed-exposure experiments using standard toxicological protocols and interpreted the results (mortality, biomass, and reproduction) using a dynamic generalization of a Mancini/Breck-type model that includes two compartments, one for internal concentration as a function of exposure and one for site-of-action concentration or accumulated damage as a function of the internal dose. At exposure concentrations near the effects level, the model explained approximately 50% of the variability in the observed time history of survival, 43% of the change in biomass, and 83% of the variability in net reproduction. Unexplained variability may result from differences in organism susceptibility, amplified by the effects of small sample sizes in standard tests. The results suggest that response is sensitive to prior conditions and that constant-exposure experiments can underestimate the risk from intermittent exposures to the same concentration. For pulsed exposures, neither the average nor the maximum concentration alone is an adequate index of risk, which depends on both the magnitude, duration, and timing of exposure pulses. Better understanding about the impacts of pulsed exposures will require use of experimental protocols with significantly greater numbers of replicates.
Characterization of Pb, Cu, and Cd adsorption on particulate organic matter in soil
Authors: Guo Xueyan , Zhang Shuzhen , Shan Xiao-quan , Luo Lei , Pei Zhiguo , Zhu Yong-Guan , Liu Tao , Xie Ya-ning , Gault Andrew
Published: August 2006

Evidence exists for significant metal enrichment in particulate organic matter (POM) compared to other soil constituents, but the relevant mechanisms are poorly understood. In the present study, adsorption of the heavy metals Pb, Cu, and Cd on a loamy soil and on POM separated from this soil was investigated. The adsorption kinetic data can be well described with a pseudo–second order model, whereas the equilibrium data are well fitted by a Langmuir model. Adsorption isotherms and kinetics data, in addition to the influence of pH on metal adsorption, showed that POM had a much higher adsorption capacity for Pb, Cu, and Cd compared to the whole soil. Ionic strength effects on metal adsorption, Fourier transform infrared spectroscopy, x-ray absorption spectroscopy x-ray absorption spectroscopy including x-ray absorption near-edge structure and extended x-ray absorption fine-structure spectroscopy were employed to elucidate the adsorption mechanisms. The results suggested that Pb and Cu adsorption on POM was mainly through inner-sphere complexes with carboxyl and hydroxyl groups. Cadmium was possibly adsorbed via outer-sphere complexation, indicated by the influence of ionic strength on Cd adsorption.
Identification of compounds associated with testosterone depressions in fish exposed to bleached kraft pulp and paper mill chemical recovery condensates
Authors: Belknap Andrew M. , Solomon Keith R. , MacLatchy Deborah L. , Dubé Monique G. , Hewitt L. Mark
Published: August 2006

In previous experiments, bleached kraft chemical recovery condensates generated during softwood pulp production have been identified as a primary source of substances causing testosterone depressions in mummichog (Fundulus heteroclitus). Recent toxicity identification evaluations have encountered inconsistencies in the potential of condensates and fractions to reduce steroid concentrations between three repeated exposures. To assess the sources of these inconsistencies, temporal assessments of condensate extractives and analytical methodologies were evaluated. Condensates were collected during a six-month period, extracted by solid-phase extraction (SPE), and analyzed by gas chromatography–mass spectrometry and gas chromatography–flame photometric detection. All unique extractives were cataloged by mass spectra, peak area, and gas chromatographic retention time, and nine were confirmed and quantified against authentic standards. Confirmed components included phenolic guaiacyl–based lignin degradation products, sulfur (S8), three diterpenoids, and a dimethoxy stilbene. Concentrations of confirmed condensate extractives were consistent in all samples collected. Spiking experiments of confirmed extractives revealed substantial losses following high-pressure liquid chromatographic fractionation and three different methods of fraction preparation. In an effort to propose chemical classes associated with biological activity, all unique condensate extractives in previously established bioactive and inactive fractions were classified based on their potential to depress testosterone in mummichog. Of 39 unique components in bioactive SPE extracts of condensates, six were associated with hormonal activity. Mass spectral interpretation indicated hydroxylated diterpenoids, sesquiterpenoids, and a lignin-derived stilbene as classes of chemicals associated with steroid depressions.
Toxicity of a cadmium-contaminated diet to Hyalella azteca
Authors: Ball Angela L. , Borgmann Uwe , Dixon D. George
Published: August 2006

Four- and 10-week chronic toxicity tests were conducted using the freshwater amphipod Hyalella azteca and Cd-contaminated Chlorella sp. as a food source. Chlorella sp. was cultured in various Cd concentrations, filtered from solution, rinsed, dried, and ground into food flakes the for H. azteca. Unlike Cd toxicity from water sources, growth was found to be a more sensitive toxicological endpoint than survival, with calculated 50 and 25% effect concentrations (EC50s and EC25s, respectively) of 5.43 and 2.82 nmol/g, respectively, for Cd measured in food. Based on the regression of Cd in Chlorella sp. against Cd in filtered culture medium, the EC50 and EC25 corresponded to dissolved Cd concentrations of 11.30 and 5.09 nmol/L, respectively. Little or no bioaccumulation of Cd was found in the tissues of H. azteca that were fed contaminated food. These results demonstrate an apparent toxicological effect (either direct or indirect) of Cd-contaminated Chlorella sp. to H. azteca that is not associated with Cd accumulation. Toxicity of Cd-contaminated Chlorella sp. differs from waterborne Cd toxicity both in terms of the most sensitive endpoint (growth vs survival) and the relationship between toxicity and bioaccumulation. Unlike Cd toxicity through water exposure, Cd bioaccumulation by H. azteca cannot, therefore, be used to infer toxicity of Cd in a diet of Chlorella sp. Although the concentration of Cd in the algal culture medium that ultimately reduced growth of H. azteca in the present study was higher than Cd in water, which caused mortality to H. azteca in water-only tests during previous studies, further research regarding the contribution of dietary Cd to overall Cd toxicity is needed to verify that water-quality guidelines and risk assessments based on water-only exposures are fully protective.
Ecological consequences of copper contamination in macroalgae: Effects on epifauna and associated herbivores
Authors: Roberts David A. , Poore Alistair G.B. , Johnston Emma L.
Published: August 2006

Many contaminants of the marine environment are able to chelate to sediments, bind within organic matrices, or be accumulated by organisms such as invertebrates and macroalgae. Marine macroalgae are recognized as effective and efficient bioaccumulators of heavy metals and are sometimes used as bioindicators. Macroalgae support abundant and diverse communities of mobile invertebrates that play key roles in temperate marine environments. However, the potential ecological consequences of the contamination of algae on associated epifauna are yet to be considered. In this study, the brown alga Sargassum linearifolium was experimentally spiked with copper to assess the effects of contamination on epifaunal invertebrates in both field and laboratory assays. Copper contamination greatly reduced the colonization of a variety of epifaunal taxa in the field. Laboratory assays further examined the effects of contaminated macroalgae on habitat preferences, feeding rates, survivorship, and growth in the herbivorous amphipod Peramphithoe parmerong. Adult P. parmerong were less likely to select spiked macroalgae in short-term habitat preference assays and consumed spiked algae at lower rates in feeding assays. In a longer-term (30-d) experiment, survivorship of juvenile amphipods was reduced by up to 75% by contaminated macroalgae, but no effects on the growth of survivors was observed. Heavy metal contamination of macroalgae is a widespread phenomenon that has the potential for substantial negative consequences for associated invertebrate fauna. This issue warrants further investigation by marine ecotoxicologists.
Bioaccumulation of native polycyclic aromatic hydrocarbons from sediment by a polychaete and a gastropod: Freely dissolved concentrations and activated carbon amendment
Authors: Cornelissen Gerard , Breedveld Gijs D. , Næs Kristoffer , Oen Amy M.P. , Ruus Anders
Published: August 2006

The present paper describes a study on the bioaccumulation of native polycyclic aromatic hydrocarbons (PAHs) from three harbors in Norway using the polychaete Nereis diversicolor and the gastropod Hinia reticulata. First, biota–sediment accumulation factors (BSAFs) were measured in laboratory bioassays using the original sediments. Median BSAFs were 0.004 to 0.01 kg organic carbon/kg lipid (10 PAHs and 6 organism–sediment combinations), which was a factor of 89 to 240 below the theoretical BSAF based on total sediment contents (which is approximately one). However, if BSAFs were calculated on the basis of measured freely dissolved PAH concentrations in the pore water (measured with polyoxymethylene passive samplers), it appeared that these BSAFfree values agreed well with the measured BSAFs, within a factor of 1.7 to 4.3 (median values for 10 PAHs and six organism–sediment combinations). This means that for bioaccumulation, freely dissolved pore-water concentrations appear to be a much better measure than total sediment contents. Second, we tested the effect of 2% (of sediment dry wt) activated carbon (AC) amendments on BSAF. The BSAFs were significantly reduced by a factor of six to seven for N. diversicolor in two sediments (i.e., two of six organism–sediment combinations), whereas no significant reduction was observed for H. reticulata. This implies that either site-specific evaluations of AC amendment are necessary, using several site-relevant benthic organisms, or that the physiology of H. reticulata caused artifactually high BSAF values in the presence of AC.
Implementing ADM1 for plant-wide benchmark simulations in Matlab/Simulink
Authors: Rosen C. , Vrecko D. , Gernaey K.V. , Pons M.N. , Jeppsson U.
Published: August 2006

The IWA Anaerobic Digestion Model No.1 (ADM1) was presented in 2002 and is expected to represent the state-of-the-art model within this field in the future. Due to its complexity the implementation of the model is not a simple task and several computational aspects need to be considered, in particular if the ADM1 is to be included in dynamic simulations of plant-wide or even integrated systems. In this paper, the experiences gained from a Matlab/Simulink implementation of ADM1 into the extended COST/IWA Benchmark Simulation Model (BSM2) are presented. Aspects related to system stiffness, model interfacing with the ASM family, mass balances, acid-base equilibrium and algebraic solvers for pH and other troublesome state variables, numerical solvers and simulation time are discussed. The main conclusion is that if implemented properly, the ADM1 will also produce high-quality results in dynamic plant-wide simulations including noise, discrete sub-systems, etc. without imposing any major restrictions due to extensive computational efforts.
Identifiability study of the proteins degradation model, based on ADM1, using simultaneous batch experiments
Authors: Flotats X. , Palatsi J. , Ahring B.K. , Angelidaki I.
Published: August 2006

The objective of the present study is to analyse kinetic and stoichiometric parameter values of gelatine anaerobic degradation at thermophilic range, based on an experiment designed to elucidate if volatile fatty acids (VFA) are inhibitors of the hydrolysis process. Results showed that VFA are not inhibiting the hydrolysis process. The ADM1 model adequately expressed the consecutive steps of hydrolysis and acidogenesis, with estimated kinetic values corresponding to a fast acidogenesis and slower hydrolysis. The hydrolysis was found to be the rate limiting step of anaerobic degradation. Estimation of yield coefficients based on the relative initial slopes of VFA profiles obtained in a simple batch experiment produced satisfactory results. From the identification study, it was concluded that it is possible to determine univocally the related kinetic parameter values for protein degradation if the evolution of amino acids is measured in simultaneous batch experiments, with different initial protein and amino acids concentrations.
Description of nitrogen incorporation and release in ADM1
Authors: Wett B. , Eladawy A. , Ogurek M.
Published: August 2006

ADM1 represents a universally applicable biokinetic model for the mathematical description of anaerobic digestion of different types of organic substrates. Digestion of particulate composites is described as a five-stage process involving disintegration, hydrolysis, acidogenesis, acetogenesis and methanogenesis, of which the last three process steps are represented by growth kinetics of the specific degrading biomass. Decay of the produced biomass according to ADM1 is depicted by a recycle mass flux to the composite particulate substrate. Consequently two different actions are lumped into one process describing both conversion of feed substrate (depending primarily on influent characterisation) and generation of decay products (depending on digestion performance). In this presentation the introduction of a separate compound of inert decay products in analogy to ASM1 is suggested. Model calibration of separately monitored digestion of primary and secondary sludge (nitrogen content 0.030 g N/g TSS and 0.051 g N/g TSS, respectively) reveals the advantage of a clear distinction of disintegration and decay. The fate of nitrogen in the course of incorporation and release (0.016 g N/g TSS compared to 0.028 g N/g TSS) during digestion processes is comprehensible and the final ammonia concentration in the rejection water becomes predictable.
Modifying ADM1 to include formation and emission of odourants
Authors: Parker W.J. , Wu G.-H.
Published: August 2006

A mathematical model that is based upon the ADM1 structure has been developed to describe the formation and emission of odourous compounds in anaerobic sludge digestion. Special emphasis is given to the general mechanisms for the formation of common odorous sulfur compounds that are found in anaerobic digesters: methyl mercaptan, dimethyl sulfide and hydrogen sulfide, as well as volatile fatty acids and ammonia. The model includes multiple-reaction stoichiometry, microbial growth kinetics and conventional material balances for an ideally mixed reactor. Simulations that were performed with the model revealed that changes in common operational parameters such as temperature, HRT and sludge metal content can dramatically impact upon the gas phase concentrations of odourants. Additional research is required to reduce uncertainty in the model formulation.
Simulation of DEHP biodegradation and sorption during the anaerobic digestion of secondary sludge
Authors: Fountoulakis M.S. , Stamatelatou K. , Batstone D.J. , Lyberatos G.
Published: August 2006

Di-ethylhexyl phthalate (DEHP) has commonly been found in the sludge of municipal wastewater treatment plants especially during anaerobic processing. It is slowly biodegradable under anaerobic conditions. Due to its high hydrophobicity, sorption-desorption processes can be rate-limiting for the compound biodegradation. In this study, the anaerobic biodegradation of DEHP was investigated through batch kinetic experiments and dynamic transitions of a continuous stirred tank reactor (CSTR) fed with secondary sludge contaminated with DEHP. A widely accepted model (ADM1) was used to fit the anaerobic digestion of secondary sludge and was properly extended to account for DEHP removal, in which mass transfer processes are also involved. It was shown that DEHP removal was limited by the transfer of DEHP within the solid fraction. The criterion selected for the distinction of the two sites was whether the compound sorbed in those sites was bioavailable for biodegradation or not. Thus, the aqueous phase and the surface of the biosolids were considered as suitable sites for the compound to be bioavailable and the main bulk of the solid matrix was regarded as sites, where the compound remains “protected” against biodegradation. The model, fitted to the batch experimental data, was able to predict DEHP removal in the CSTR operated at various HRTs.
Parameter analysis of the IWA Anaerobic Digestion Model No. 1 for the anaerobic digestion of blackwater with kitchen refuse
Authors: Feng Y. , Behrendt J. , Wendland C. , Otterpohl R.
Published: August 2006

The IWA anaerobic digestion model No.1 (ADM1) had been successfully applied to the lab-scale mesophilic blackwater anaerobic digestion (BWAD) plant for cases of only blackwater (BW) feeding and of BW plus kitchen refuse (KR) feeding. In this paper, the simulation results of BW+KR anaerobic digestion are presented and discussed, followed by the analyses and discussion of the critical and important parameters as well as the performance of ADM1 based on these results. The raw BW can contain up to 30% short chain fatty acids (SCFA) which severely impact the performance of the model. The model proved that the disintegration/hydrolysis rate of BW is around 4.5 d−1, which is about ten times higher than that of KR (Kdis,KR=0.5 d−1). ADM1 is not sensitive to the distribution ratio among carbohydrates, proteins and lipids. For BWAD the C4 metabolism can be integrated in the uptake of LCFA. The uptake delay phenomenon was observed and cannot be simulated by ADM1, but it is tolerable. No unique KI,NH3,ac is found out for all investigated ammonia concentration ranges. Meanwhile, ADM1 is not sensitive to KLa and kp, so they can easily be set up.
ADM1-based methodology for the characterisation of the influent sludge in anaerobic reactors
Authors: Huete E. , de Gracia M. , Ayesa E. , Garcia-Heras J.L.
Published: August 2006

This paper presents a systematic methodology to characterise the influent sludge in terms of the ADM1 components from the experimental measurements traditionally used in wastewater engineering. For this purpose, a complete characterisation of the model components in their elemental mass fractions and charge has been used, making a rigorous mass balance for all the process transformations and enabling the future connection with other unit-process models. It also makes possible the application of mathematical algorithms for the optimal characterisation of several components poorly defined in the ADM1 report. Additionally, decay and disintegration have been necessarily uncoupled so that the decay proceeds directly to hydrolysis instead of producing intermediate composites. The proposed methodology has been applied to the particular experimental work of a pilot-scale CSTR treating real sewage sludge, a mixture of primary and secondary sludge. The results obtained have shown a good characterisation of the influent reflected in good model predictions. However, its limitations for an appropriate prediction of alkalinity and carbon percentages in biogas suggest the convenience of including the elemental characterisation of the process in terms of carbon in the analytical program.
Diffusive Boundary Layer Development Above a Sediment–Water Interface
Authors: Higashino Makoto , Stefan Heinz G.
Published: August 2006

A model to estimate the entry length to a fully developed diffusive boundary layer above a sediment bed, such as those found in lakes, reservoirs, rivers, and estuaries, is presented. The model is used to determine how the length of a sediment bed in mass‐transfer experiments influences the measured vertical diffusive flux at the sediment–water interface. A nondimensional local mass flux is introduced in the form of a Sherwood number (Sh) and expressed as a function of both the distance from the leading edge of the sediment bed (x) and the Schmidt number (Sc). Similarly, a mean Sherwood number (Shave) for a sediment bed of length (L) is introduced. The diffusive boundary layer grows with distance, and its thickness depends on the Schmidt number (i.e., the diffusive boundary layer gets thicker and develops more quickly as the Schmidt number decreases). For Schmidt numbers greater than or equal to 100, the diffusive boundary layer begins to develop slowly but is fully developed when the nondimensional horizontal coordinate (x+) is approximately 1000. The Sherwood number is largest (i.e., ∞) near the leading edge of the sediment bed (i.e., at x=0), decreases as the distance from the bed increases, and, finally, approaches a constant value for a fully developed diffusive boundary layer (Sh∞). In this paper, the distance to a fully developed diffusive boundary layer (L99) and the required length of a sediment bed are related explicitly to Sc, sheer velocity (U* ), and the relative errors of local or average Sherwood numbers (Sh or Shave, respectively) against the Sherwood number for the fully developed diffusive boundary layer (Sh∞). The lengths L99 and L decrease as the Schmidt number increases and become independent of the Schmidt number when Sc is greater than 1000. A longer sediment bed is needed when the shear velocity or the Schmidt number is small (e.g., L99 and L ≈ 1.0 m and 8.0 m, respectively, for Sc=500, U* =0.1 cm/s, and a 3% acceptable error). Experimental studies may not be able to meet these requirements and an adjustment of measured mass‐transfer rates at a sediment–water interface may be necessary. The magnitude of that adjustment is up to 50%. Its dependence on the Schmidt number, shear velocity, and bed length is given in this paper.
N‐Nitrosodimethylamine: A Disinfectant Byproduct and Its Occurrence in Wastewater
Authors: Siddiqui Mohamed , Atasi Khalil Z.
Published: August 2006

This paper will provide wastewater treatment utility professionals with a comprehensive synthesis of information pertinent to N‐nitrosodimethylamine (NDMA) so that plant operators can make informed and cost‐effective decisions regarding appropriate management techniques. A suspect disinfection byproduct, NDMA is a potential carcinogen and is presently under scrutiny from the U. S. Environmental Protection Agency because it poses a threat to groundwaters from reclaimed wastewaters. Recognizing that the current state of knowledge pertaining to the occurrence and treatment of NDMA from wastewater treatment is in its infancy, the information presented in this paper is timely and will help utility professionals develop confidence toward controlling NDMA during wastewater treatment. Given the increased probability of the formation of NDMA using current wastewater treatment technologies and also in the complex matrices of the wastewaters subjected to UV treatment, the investigation of occurrence pathways and means of suppression of NDMA formation before and after treatment needs to be investigated. This paper also summarizes strategies to minimize exposure such as modifying treatment or instituting waste and agricultural management practices that minimize inorganic and organic nitrogen discharges to wastewaters.
Slaughterhouse Wastewater Treatment In a Full‐scale System With Constructed Wetlands
Authors: Gutiérrez‐Sarabia Alejandro , Fernández‐Villagómez Georgina , Martínez‐Pereda Pedro , Rinderknecht‐Seijas Noemí , Poggi‐Varaldo Héctor M.
Published: August 2006

This work evaluated the performance of a full‐scale system with wetlands for slaughterhouse (abattoir) effluent treatment in the State of Hidalgo, México. The treatment system consisted of a primary sedimentation tank, an anaerobic lagoon, and a constructed subsurface‐flow wetland, in series. The wetland accounted for almost 30% of the removal of organic matter. In general, the treatment system achieved satisfactory pollutant removals, but the final effluent could not meet the Mexican environmental regulations for fecal coliform counts, five‐day biochemical oxygen demand (BOD5), and total suspended solids (TSS). Overall, removal levels were 91%, 89%, and 85% for BOD5, chemical oxygen demand, and TSS, respectively. However, BOD5 in the final effluent (137 mg/L) was higher than the maximum level of 30 mg/L allowed by the regulatory agency. Although organic nitrogen removal levels were approximately 80%, the nitrogen persisted in oxidation state – 3 as ammonia–nitrogen, the removal of which was only 9% in the wetland stage. On average, phosphorus removal was null, and, on occasion, the phosphorus concentration in the treated effluent was higher than that of the influent. Coliform reductions in the overall system were high (on the order of 5 logs on average), whereas the coliform removal in the wetland was between 2 to 3.5 logs. The treatment system was also effective at removing pathogens (Vibrio cholerae, Salmonella , and Shigella). Further laboratory tests with the wetland effluent suggest that post treatment in a sand filter stage followed by disinfection with sodium hypochlorite (NaOCl) could help meet the Mexican discharge regulations, particularly the criteria for coliforms and total BOD5.
Exergy Analysis: A Comparison of Source Separation Systems and Conventional Treatment Systems
Authors: Hellström Daniel
Published: August 2006

Exergy analysis and material balances are useful to describe resource use in different systems. In this study, three different sewerage systems are analyzed: a conventional system with biological nitrogen removal, a conventional system in combination with source separation of urine, and a treatment system with source separation of urine and feces. The influence of factors such as the size of the system, access to farmland, and concentration of collected urine is studied. The study shows that total exergy consumption is least for the system with source separation of urine and feces and greatest for the conventional wastewater treatment system. The primary difference results from the amount of methane gas that is produced by each alternative. Another conclusion is that a significant portion of exergy consumption in the source separation system is the transport and spreading of urine.
Identification of the Different Sources of Chlorides in Streams by Regression Analysis Using Chloride‐Discharge Relationships
Authors: Albek Erdem
Published: August 2006

Chloride‐discharge relationships at several stations on Turkish streams are investigated, both qualitatively and quantitatively, to identify natural and anthropogenic sources of chloride. Simple expressions are used to distinguish among sources. Linear regression analysis is conducted to estimate parameters of the models. Five groups of stations are distinguished respective to different sources of chloride and change of chloride concentration with stream discharge. Emphasis is placed on the identification of anthropogenic sources of chloride to aid in water pollution control strategies. The polluted Sakarya River and its primary tributary, the Porsuk Stream, are studied in detail to trace chloride behavior along the waterway and to assess the level of pollution from cities discharging to the streams. Among natural sources of chloride, evaporite sediment sources are examined in detail.
Metal Accumulation by an Epigean and a Hypogean Freshwater Amphipod: Considerations for Water Quality Assessment
Authors: Plénet S.
Published: August 2006

To evaluate their potential as biomonitors of surface and underground water quality, the accumulation of essential metals, zinc and copper, by two species of amphipod crustaceans, Gammarus fossarum (an epigean amphipod) and Niphargus rhenorhodanensis (a similar but blind and hypogean form) was investigated. These two species were exposed, under controlled laboratory conditions, to different metal concentrations for 12 days. Several concentrations of each of the two metals separately and one concentration of a mixture of both were tested. Percent mortality revealed that the hypogean species was more resistant than the epigean. During the 12 days of experiment, accumulation patterns differed between species and between metals. G. fossarum, but not N. rhenorhodanensis, accumulated zinc at exposures of up to 12 days and concentrations as great as 1000 μg/L. Zinc levels in tissue of G. fossarum were greater than in those of N. rhenorhodanensis. Epigean and hypogean amphipods did not clearly accumulate copper in exposures as great as 65 μg/L. Possible reasons for the differences in zinc and copper accumulation between the two species are discussed. Finally, the suitability of the two species as biomonitors for surface and underground water is discussed.
Effect of Marine Sediments Associated with the Orange County, California, Ocean Outfall on the Survival and Growth of Juvenile Neanthes arenaceodentata (Annelida: Polychaeta)
Authors: Reish Donald J. , Gerlinger Thomas V. , Fanizza Martina , Soong Karl , Armstrong Jeffrey L.
Published: August 2006

Sediments taken from the ocean outfall of the County Sanitation Districts of Orange County, California, were tested for toxicity using Neanthes arenaceodentata survival and growth as the criteria to measure toxic effects. Eight experiments were conducted in which juveniles taken from a laboratory‐inbred population were exposed to sediments from varying distances from the discharge. Sediment geochemical parameters measured included organic carbon, grain size, and concentrations of metals, dichlorodiphenyl trichloromethane, and polychlorinated biphenyl 1254. Controls consisted of seawater, seawater with inert silica, and sediment from control sites. Stations were grouped by their relative distance from the discharge point. Organic carbon and certain metal concentrations were greater at the discharge but not significantly different from other sites. Survival was approximately 90% in almost all test exposures. Worm growth rate, expressed as milligrams growth (dry weight) per day, was greater in animals exposed to field sediments compared to controls. This difference was attributed to the presence of organic matter in the field sediment. Results indicate that sediments from the Districts' outfall are not toxic to this species.