bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological health assessments based on whole effluent toxicity tests and the index of biological integrity in temperate streams influenced by wastewater treatment plant effluents
Authors: Ra Jin Sung , Kim Sang Don , Chang Nam Ik , An Kwang-Guk
Published: August 2007

Whole effluent toxicity (WET) tests and ecosystem health assessments, based on test guidelines of U.S. Environmental Protection Agency (U.S. EPA) and index of biological integrity (IBI), were conducted on various streams located in Youngsan River watershed, Korea. The WET tests showed that about 33 and 82% of wastewater treatment plants (WWTPs) exhibited significant toxicity to Daphnia magna and Selenastrum capricornutum, respectively. Small WWTPs with low discharge volumes contributed less than 1% to the total stream toxicity. Fish community compositions and trophic guild analysis showed that the diversity index was greater in the control than in impacted streams, and the proportion of omnivore species was less in the control. Also, ecosystem health assessments, based on the IBI, showed distinct differences between the control and impacted sites of WWTPs. Model values of the IBI, based on 12 stream data sets, averaged 28, which is judged as a fair to poor condition according to the U.S. EPA criteria. The mean IBI in the control sites was 42, indicating good stream condition, whereas the impacted sites was scored 21, indicating poor condition. Overall, WET tests and ecosystem health assessments suggested the WWTP effluents had evident toxic effects on the biota, and impacted the species compositions and trophic guilds, resulting in degradation of the stream ecosystem health.
Chemical structure-based predictive model for methanogenic anaerobic biodegradation potential
Authors: Meylan William , Boethling Robert , Aronson Dallas , Howard Philip , Tunkel Jay
Published: August 2007

Many screening-level models exist for predicting aerobic biodegradation potential from chemical structure, but anaerobic biodegradation generally has been ignored by modelers. We used a fragment contribution approach to develop a model for predicting biodegradation potential under methanogenic anaerobic conditions. The new model has 37 fragments (substructures) and classifies a substance as either fast or slow, relative to the potential to be biodegraded in the “serum bottle” anaerobic biodegradation screening test (Organization for Economic Cooperation and Development Guideline 311). The model correctly classified 90, 77, and 91% of the chemicals in the training set (n = 169) and two independent validation sets (n = 35 and 23), respectively. Accuracy of predictions of fast and slow degradation was equal for training-set chemicals, but fast-degradation predictions were less accurate than slow-degradation predictions for the validation sets. Analysis of the signs of the fragment coefficients for this and the other (aerobic) Biowin© models suggests that in the context of simple group contribution models, the majority of positive and negative structural influences on ultimate degradation are the same for aerobic and methanogenic anaerobic biodegradation.
Effects of methylmercury on reproduction in American kestrels
Authors: Albers Peter H. , Koterba Michael T. , Rossmann Ronald , Link William A. , French John B. , Bennett Richard S. , Bauer Wayne C.
Published: August 2007

Sixty breeding pairs of captive American kestrels (Falco sparverius) were exposed to a range of sublethal dietary concentrations of mercury (Hg), in the form of methylmercuric chloride, and their subsequent reproduction was measured. Egg production, incubation performance, and the number and percent of eggs hatched decreased markedly between 3.3 and 4.6 mg/kg dry weight of Hg (1.2 and 1.7 mg/kg wet wt), in the diet. The number of fledglings and the percent of nestlings fledged were reduced markedly at 0.7 mg/kg dry weight (0.3 mg/kg wet wt) and declined further between 2 and 3.3 mg/kg dry weight (0.7 and 1.2 mg/kg wet wt). Dietary concentrations of ⩾4.6 mg/kg dry weight (1.7 mg/kg wet wt) were associated with total fledging failure. The estimated decline in fledged young per pair (24%, Bayesian regression) for kestrels consuming 0.7 mg/kg dry weight (0.3 mg/kg wet wt) raises concerns about population maintenance in areas subject to high inputs of anthropogenic Hg. Mercury concentrations in 20 second-laid eggs collected from all groups were related to dietary concentrations of Hg, and the Hg concentrations in 19 of these eggs were related to eggs laid and young fledged. Concentrations of Hg in eggs from the highest diet group (5.9 mg/kg dry wt; 2.2 mg/kg wet wt) were higher than egg concentrations reported for either wild birds or for captive birds (nonraptors) fed dry commercial food containing 5 mg/kg methylmercury. Accumulation ratios of Hg from diets to eggs were higher than those reported for feeding studies with other species.
Supercritical carbon dioxide extraction as a predictor of polycyclic aromatic hydrocarbon bioaccumulation and toxicity by earthworms in manufactured-gas plant site soils
Authors: Kreitinger Joseph P. , Quĩones-Rivera Antonio , Neuhauser Edward F. , Alexander Martin , Hawthorne Steven B.
Published: August 2007

The toxicity and uptake of polycyclic aromatic hydrocarbons (PAHs) by earthworms were measured in soil samples collected from manufactured-gas plant sites having a wide range in PAH concentrations (170–42,000 mg/kg) and soil characteristics. Samples varied from vegetated soils to pure lampblack soot and had total organic carbon contents ranging from 3 to 87%. The biota-soil accumulation factors (BSAFs) observed for individual PAHs in field-collected earthworms (Aporrectodea caliginosa) were up to 50-fold lower than the BSAFs predicted using equilibrium-partitioning theory. Acute toxicity to the earthworm Eisenia fetida was unrelated to total PAH concentration: Mortality was not observed in some soils having high concentrations of total PAHs (>42,000 mg/kg), whereas 100% mortality was observed in other soils having much lower concentrations of total PAHs (1,520 mg/kg). Instead, toxicity appeared to be related to the rapidly released fraction of PAHs determined by mild supercritical CO2 extraction (SFE). The results demonstrate that soils having approximately 16,000 mg rapidly released total PAH/kg organic carbon can be acutely toxic to earthworms and that the concentration of PAHs in soil that is rapidly released by SFE can estimate toxicity to soil invertebrates.
Prediction of lethal/effective concentration/dose in the presence of multiple auxiliary covariates and components of variance
Authors: Gutreuter Steve , Boogaard Michael A.
Published: August 2007

Predictors of the percentile lethal/effective concentration/dose are commonly used measures of efficacy and toxicity. Typically such quantal-response predictors (e.g., the exposure required to kill 50% of some population) are estimated from simple bioassays wherein organisms are exposed to a gradient of several concentrations of a single agent. The toxicity of an agent may be influenced by auxiliary covariates, however, and more complicated experimental designs may introduce multiple variance components. Prediction methods lag examples of those cases. A conventional two-stage approach consists of multiple bivariate predictions of, say, medial lethal concentration followed by regression of those predictions on the auxiliary covariates. We propose a more effective and parsimonious class of generalized nonlinear mixed-effects models for prediction of lethal/effective dose/concentration from auxiliary covariates. We demonstrate examples using data from a study regarding the effects of pH and additions of variable quantities 2',5'-dichloro-4'-nitrosalicylanilide (niclosamide) on the toxicity of 3-trifluoromethyl-4-nitrophenol to larval sea lamprey (Petromyzon marinus). The new models yielded unbiased predictions and root-mean-squared errors (RMSEs) of prediction for the exposure required to kill 50 and 99.9% of some population that were 29 to 82% smaller, respectively, than those from the conventional two-stage procedure. The model class is flexible and easily implemented using commonly available software.
Comparison of short-term chronic and chronic silver toxicity to fathead minnows in unamended and sodium chloride-amended waters
Authors: Naddy Rami B. , Rehner Anita B. , McNerney Gina R. , Gorsuch Joseph W. , Kramer James R. , Wood Chris M. , Paquin Paul R. , Stubblefield William A.
Published: August 2007

The chronic (early life stage [ELS]) and short-term chronic (STC) toxicity of silver (as silver nitrate) to fathead minnows (FHM) was determined concurrently in flow-through exposures (33 volume additions/d). Paired ELS (∼30 d) and STC (7 d) studies were conducted with and without the addition of 60 mg/L Cl (as NaCl). The paired studies in unamended water were later repeated using standard flow conditions (9 volume additions/d). The purpose of the paired studies was to determine if short-term chronic endpoints can be used to predict effects in ELS studies. For each experiment, a “split-chamber” design (organisms were held in a common exposure chamber) allowed the direct comparison between short-term and chronic exposures. It appeared that the chronic toxicity of silver was mitigated to some extent by NaCl addition. The maximum acceptable toxicant concentration for growth in the ELS study was 0.53 μg dissolved Ag/L under standard flow conditions. Early life stage and STC endpoints in all three studies typically agreed within a factor of two. Whole-body sodium and silver concentrations measured in individual fathead minnows during these studies showed an increase in silver body burdens and a decrease in sodium concentration. These results indicate that the STC study could be used as a surrogate test to estimate chronic toxicity and that the mechanism of chronic silver toxicity may be the same as for acute toxicity.
Orally administered bisphenol a in rainbow trout (Oncorhynchus mykiss): Estrogenicity, metabolism, and retention
Authors: Bjerregaard Poul , Andersen Sidsel B. , Pedersen Knud L. , Pedersen Søren N. , Korsgaard Bodil
Published: August 2007

The estrogenic effect of orally administered bisphenol A (BPA) was investigated in a rainbow trout (Oncorhynchus mykiss) test system. Bisphenol A was administered orally to sexually immature rainbow trout every second day for up to 12 d in doses between 1.8 and 258 mg/kg every second day (/2d). Plasma vitellogenin was measured before and during the exposures, and the concentrations of BPA in plasma, liver, and muscle and the plasma concentrations of BPA glucuronic acid (BPAGA) were determined at the end of the experiments. Increases in average plasma vitellogenin levels were seen at oral exposure to 24 mg BPA/kg/2d; the most sensitive fish responded to 9.3 mg/kg/2d. At day 12, the 10, 50, and 90% effective doses for increase in vitellogenin synthesis were 13, 19, and 25 mg/kg/2d, respectively. Bisphenol A could be detected in liver, muscle, and plasma at the end of the exposure, generally in increasing concentrations with increasing doses; liver concentrations generally were higher than muscle concentrations. Four to five hours after the last feeding of doses between 3.6 and 24 mg BPA/kg, plasma BPA concentrations ranged between 400 and 1,200 nM, whereas BPAGA concentrations were between 2- and 10-fold higher. The difference between BPA and BPAGA concentrations increased with increasing BPA dose. Bisphenol A showed little tendency to bioaccumulate in rainbow trout; less than 1% of the total amount of BPA administered orally at doses between 1.8 and 258 mg/kg/2d over the 10- or 12-d experimental period was retained in muscle and liver at 5 or 24 h after the end of the experiments.
Enantioselective acetylcholinesterase inhibition of the organophosphorous insecticides profenofos, fonofos, and crotoxyphos
Authors: Nillos Mae Grace , Rodriguez-Fuentes Gabriela , Gan Jay , Schlenk Daniel
Published: August 2007

A large number of organophosphorous insecticides (OPs) are chiral compounds, and yet enantioselectivity in their environmental fate and effects is rarely addressed. In the present study, we isolated individual enantiomers of three OPs, profenofos, fonofos, and crotoxyphos, and evaluated enantioselectivity in their inhibition of acetylcholinesterase (AChE). Acetylcholinesterase inhibition by the enantiomers and racemates was determined in vivo in the aquatic invertebrate Daphnia magna and in Japanese medaka (Oryzias latipes) as well as in vitro with electric eel (Electrophorus electricus) and human recombinant AChEs. The overall results showed variable sensitivity between AChE enzymes from different species as well as variable magnitude of enantioselectivity in enzyme inhibition. The (—)-enantiomer of profenofos was 4.3- to 8.5-fold more inhibitory to AChE in vivo, whereas (—)-fonofos was 2.3- to 29-fold more potent than the corresponding (+)-enantiomer. The (+)-enantiomer of crotoxyphos was 1.1- to 11-fold more inhibitory to AChE than the (—)-enantiomer. In contrast, the in vitro results showed (+)-profenofos to be 2.6- to 71.8-fold more inhibitory than the (—)-enantiomer and (—)-crotoxyphos to be 1.6- to 1.9-fold more active than the (+)-enantiomer. The reversed direction of enantioselectivity observed between the in vivo and in vitro assays suggests enantioselectivity within toxicodynamic processes such as uptake, biotransformation, or elimination. Findings from the present study provide evidence of enantioselectivity in the AChE inhibition of chiral OPs in nontarget organisms and indicate the need to consider enantiomers individually when assessing environmental risk of these chiral pesticides.
The sorptive capacity of animal protein
Authors: deBruyn Adrian M.H. , Gobas Frank A.P.C.
Published: August 2007

Partition coefficients that are used to predict concentrations of hydrophobic organic chemicals in biota (e.g., the bioconcentration factor) often assume that the sorptive capacity of an organism or tissue is adequately represented by its lipid content. In lean organisms and tissues, however, theory suggests that partitioning may be strongly influenced by the sorptive capacity of nonlipid materials, such as protein. Little is known about the sorptive capacity of proteins for hydrophobic organic chemicals, and methods to include proteins in bioaccumulation models do not exist. Here, we present a compilation and meta-analysis of published data to estimate the relative sorptive capacities of animal proteins and lipids for neutral organic chemicals. We found that the estimated sorptive capacity of protein in solid animal tissues ranged from around 1 to 10% that of lipid for compounds with a log octanol/water partition coefficient (KOW) of greater than two. The sorptive capacity of blood protein (albumin) appeared to be substantially higher than this, especially for low-KOW chemicals. For modeling purposes, we recommend estimating the sorptive capacity of animal protein as 5% that of lipid. According to this estimate, the sorptive capacity of an animal or tissue will be dominated by the contribution from protein if the lipid content makes up less than 5% of the dry-weight organic content. In such situations, a consideration of the sorptive capacity of nonlipid constituents, such as protein, will permit more accurate predictions of chemical accumulation and distribution.
Availability of polychlorinated biphenyls in field-contaminated sediment
Authors: You Jing , Landrum Peter F. , Trimble Tricia A. , Lydy Michael J.
Published: August 2007

Two chemical approaches, Tenax extraction and matrix solid phase microextraction (matrix-SPME), were evaluated as surrogates to estimate bioavailability of polychlorinated biphenyls (PCBs) from field-contaminated sediment. Aroclor 1254 was the primary contaminant found in sediment from Crab Orchard Lake in Marion, Illinois, USA, and a total of 18 PCB congeners were selected for study. Bioaccumulation was determined by exposing the freshwater oligochaete, Lumbriculus variegatus, to the sediment for 28 d. Differences in the rapidly desorbing fraction of PCBs and fraction desorbed within 6 h, defined by Tenax extraction, accounted for 39 and 31% of the differences among biota-sediment accumulation factor values, respectively. A better relationship (r2 = 0.95) was found between the oligochaete PCB body residues and the concentration of PCBs in the rapidly desorbing fraction of sediment. The degree of chlorination and planarity of the PCB congeners affected both desorption and bioaccumulation. The higher chlorine substituted and planar PCBs showed less chemical and biological availability, due to their stronger sorption to sediment, compared to the lower chlorinated and nonplanar PCBs. Accumulation of PCBs by L. variegatus correlated well (r2 = 0.88) with matrix-SPME fiber concentrations. The ratio of measured body residue to estimated body residue from the pore water concentration measured by matrix-SPME ranged from 0.4 to 1.3 with an average of 0.9. Overall, both Tenax and matrix-SPME approaches were useful surrogates of bioaccumulation for a field-contaminated sediment.
Determinants of variability in acute to chronic toxicity ratios for aquatic invertebrates and fish
Authors: Raimondo Sandy , Montague Brian J. , Barron Mace G.
Published: August 2007

Variability in acute to chronic ratios (ACRs; median lethal or effect concentration divided by chronic value) has been of continuing interest in aquatic toxicology because of the reliance on ACRs to estimate chronic toxicity for chemicals and species with known acute toxicity data but with limited or no information for chronic toxicity. To investigate the variability and significant differences in ACRs, an extensive data set was compiled of 456 same-species pairs of acute and maximum acceptable toxicant concentrations for metals, narcotics, pesticides, and other organic chemicals. The overall median value for 456 aquatic invertebrate and fish ACRs analyzed in the present study was 8.3, with a 16,000-fold range in values (1.1–18,550) and a 32-fold range in 10th and 90th percentile values (2.5–79.5). Median ACRs for taxa, ambient habitat media, chronic test end point, and chemical mode of action (MOA)/class categories generally were similar but, in some cases, extremely variable (ranges of 1 to gt;10,000). No significant differences (p ⩽ 0.05) were found in median ACRs between taxa, although invertebrate ACRs generally were more variable than fish ACRs. Freshwater organisms had median ACRs significantly greater than those of saltwater species and also were more variable. No significant differences were found in median ACRs among chemical MOA/class data sets; however, ACR variance differed significantly among MOAs. Although few significant differences occurred among median ACRs for different groups, those categories that were highly variable are at an increased risk of underestimated chronic toxicity when mean or median ACRs are used.
Aspects of petrochemical pollution in southeastern Louisiana (USA): Pre-Katrina background and source characterization
Authors: Iqbal Javed , Gisclair David , McMillin Debra J. , Portier Ralph J.
Published: August 2007

Background petroleum pollution before Hurricane Katrina in southeastern Louisiana (USA) coastal sediments was evaluated at 320 locations in three consecutive years for polycyclic aromatic hydrocarbons (PAHs), saturated alkanes (nC9-nC35), and petroleum biomarker compounds (hopanes, steranes, pristane, and phytane). Approximately 90% of the sample locations had a total PAH concentration of less than 2.0 μg/g and total saturated alkane concentration of less than 17 μg/g, with 50% indicating a total PAH concentration of less than 200 ng/g. Upper limit or baseline high concentration for total PAHs was 1.5 μg/g, comparable to the 2.18 μg/g reported for the National Status and Trends (NST) Program of the National Oceanic and Atmospheric Administration (NOAA). Thus, 85% of sites were below the baseline high concentration. Baseline high total PAHs at 6% of the sites (described as land) was 5.1 μg/g, comparable to the 4 μg/g benchmark calculated for NST. The three-year average total PAH concentration for 95% of the sites was less than 7.5 μg/g, a defined limit of fivefold the baseline high concentration. Samples indicated petrogenic, pyrogenic, and natural/biogenic hydrocarbon inputs. Contaminant levels exceeded the state soil screening limits at only 3% of the 320 locations. Federal screening limits proposed by the NOAA for ecological effects were exceeded at only 18% of the sites (including those sites exceeding the state limit). Only 4% of the sites had concentrations exceeding the NOAA effect range-low (ER-L) in more than one collection year. At least 61% of the analytes exceeding the ER-L were pyrogenic source indicators. Source-fingerprint analysis of these selected samples showed 10 samples with notable petroleum contamination, whereas six indicated pyrogenic input. Of all samples collected, only one site showed relatively fresh/lightly weathered petroleum.
New climate change scenarios for the Netherlands
Authors: van den Hurk B. , Tank A.K. , Lenderink G. , van Ulden A. , van Oldenborgh G.J. , Katsman C. , van den Brink H. , Keller F. , Bessembinder J. , Burgers G. , Komen G. , Hazeleger W. , Drijfhout S.
Published: August 2007

A new set of climate change scenarios for 2050 for the Netherlands was produced recently. The scenarios span a wide range of possible future climate conditions, and include climate variables that are of interest to a broad user community. The scenario values are constructed by combining output from an ensemble of recent General Climate Model (GCM) simulations, Regional Climate Model (RCM) output, meteorological observations and a touch of expert judgment. For temperature, precipitation, potential evaporation and wind four scenarios are constructed, encompassing ranges of both global mean temperature rise in 2050 and the strength of the response of the dominant atmospheric circulation in the area of interest to global warming. For this particular area, wintertime precipitation is seen to increase between 3.5 and 7% per degree global warming, but mean summertime precipitation shows opposite signs depending on the assumed response of the circulation regime. Annual maximum daily mean wind speed shows small changes compared to the observed (natural) variability of this variable. Sea level rise in the North Sea in 2100 ranges between 35 and 85 cm. Preliminary assessment of the impact of the new scenarios on water management and coastal defence policies indicate that particularly dry summer scenarios and increased intensity of extreme daily precipitation deserves additional attention in the near future.
Climate change and floods – findings and adaptation strategies for flood protection in Baden-Württemberg
Authors: Hennegriff W.
Published: August 2007

The climatic conditions in Southern Germany have changed noticeably in the 20th century, especially during the last three decades. Both in specific regions and interannually, the trends found exceed the natural margins of deviation previously known from long measurement series for some measured quantities. The mean and also the extreme floods are expected to increase significantly, although the results of the model chain global model–regional climate models–water balance models are still uncertain. As a precaution an adaptation strategy has been developed for the field of flood protection which takes into consideration the possible development for the next decades and also takes into account the uncertainties.
Impact of summer droughts on water quality of the Rhine River - a preview of climate change?
Authors: Zwolsman J.J.G. , van Bokhoven A.J.
Published: August 2007

It is generally recognized that climate change will affect the discharge regime of the Rhine River. Especially the anticipated increase in extreme river discharges (floods and droughts) poses serious problems to water management, both with regard to water quantity and water quality. Water quality effects of climate change are not sufficiently recognized, however. The purpose of this study is to investigate the impact of droughts on the water quality of the River Rhine. Time series of river flow and water quality were analyzed for station Lobith, located at the Dutch-German border. Over the past three decades, three major droughts were identified, occurring in the years 1976, 1991, and 2003. The water quality during these dry years was compared with the water quality in reference years, characterized by average hydrological conditions and similar chemical pollution. Four groups of water quality parameters were investigated: 1, general variables (water temperature, dissolved oxygen, chlorophyll-a); 2, major ions (chloride, sodium, sulfate, fluoride, bromide); 3, nutrients; and 4, heavy metals. It was found that water quality is negatively influenced by (summer) droughts, with respect to water temperature, eutrophication, major ions and heavy metals. Effects on nutrient concentrations were small for ammonium and could not be demonstrated for nitrate, nitrite and phosphate. The decline in water quality during summer droughts is both related to the high water temperatures and to low river discharges (limited dilution of the chemical load from point sources). Moreover, the impact of the 1976 drought on water quality was far more important than that of the 2003 drought, indicating that the impact of droughts on water quality will be greater when the water quality is already poor.
Exploring local knowledge of the flooding risk of the Scheldt Estuary
Authors: Slinger J. , Muller M. , Hendriks M.
Published: August 2007

‘The public should be involved in the decision making process’ is an oft heard statement, but the practice of public participation remains a worrisome issue for policy makers and planners. In this paper we describe local knowledge of flooding risk in the vicinity of the Scheldt Estuary derived through in-depth, semi-structured interviews with fourteen inhabitants. We compare and contrast this knowledge with that of scientists involved in the assessment of the flooding hazard posed by the tidal Scheldt and with that of Dutch and Flemish policy advisors. We identify areas of common knowledge, confirm the accuracy of much local knowledge and recognize the percipience of a number of the questions posed by local inhabitants. This exploratory study serves to confirm that background local knowledge can be a valuable tool in designing responsible policy processes for flood risk management.
Integrated flood management
Authors: Grabs W. , Tyagi A.C. , Hyodo M.
Published: August 2007

While there have been a number of international initiatives centred around hydrological sciences and technical approaches, the social, economic, environmental, and legal and institutional aspects of flood management have been dealt with sporadically and in a limited manner. WMO and the Global Water Partnership have established the Associated Programme on Flood Management (APFM) to address these issues and developed a concept of Integrated Flood Management (IFM) in 2002. This article is the result of the integrated flood management approaches through pilot projects and multi-disciplinary approaches launched by the initiative since the establishment of the IFM concept. This approach seeks to integrate land- and water-resources development in a river basin, within the context of Integrated Water Resources Management (IWRM) and aims at maximizing the benefits from floodplains and at the same time reducing loss of life from flooding. This approach identified the key elements of IFM and recommended that these can be put in place by: adopting a basin approach to flood management; adopting a multi-disciplinary approach in flood management; reducing vulnerability to and risks from flooding; enabling community participation; and preserving ecosystems; and addressing climate change and variability, supported by enabling mechanism through appropriate legislation and regulations.
Participatory dam systems modelling: a case study of the transboundary Guadiana River in the Iberian Peninsula
Authors: Máñez M. , Froebrich J. , Ferrand N. , Silva A.
Published: August 2007

Modelling tools have been widely used to investigate best management practices. But in contrast to the plethora of modelling studies, the practical implementation of outcomes is comparatively small. There is an urgent need to implement results and to show the practical validation of the concept developed, especially against the context of water stress mitigation.

The participative development of modelling studies as a joint effort of stakeholders and modellers is seen as a key to achieve a wider identification, acceptance, trust and applicability of results. Participatory planning in the water sector is also increasingly requested in water management, where tasks have been for clarified decades through different institutional arrangements and national laws. Stakeholder involvement in water resources management have been limited to what was long time seen as participation, merely information on action to be taken. In the last decade the need for participation has been reflected in different ways. In Europe, the implementation of the Water Framework Directive (WFD) under Art. 14, requires all the European countries to involve stakeholders in decision making processes on water resource management.

The aim of this paper is to present and discuss the research framework and possible results of investigating dam modelling through participatory systems modelling. We introduce a structured approach to use participatory modelling (PM) for stimulating the integration of modelling and decision making, also as a way of implementation of some articles of the WFD. The results and the framing of this paper are part of the AQUASTRESS Project.

The conceptual modelling has been developed by a multidisciplinary research team, local stakeholders and local experts. Some results are discussed and recommendations made.
The climate footprint: a practical tool to address climate change
Authors: Janse T. , Wiers P.
Published: August 2007

Waternet supplies clean and safe drinking water to the homes of almost one million Amsterdam citizens, and also collects and treats the resulting wastewater, ensuring its safe discharge back into the water system. Climate change poses a growing challenge. Firstly Waternet is affected by the consequences of climate change, such as longer periods of drought and heavier bursts of rainfall. Secondly, the company also plays a role in causing climate change, as emissions from the Amsterdam water chain contribute to global warming. This paper aims to focus attention on mitigation as an inseparable part of adaptation-programmes.

The Climate Footprint methodology is applied to the integrated Amsterdam water chain: from the point of withdrawing water from the surface/groundwater water system for drinking water production, to the point of returning the purified wastewater to the surface water/groundwater system. In-between, the water is pre-treated with chemicals, transported, purified by dune-filtration, again treated for drinking water quality, distributed over the area of Amsterdam, used in households and industries, collected from there by sewers and pumps, transported to purification plants and finally again treated with chemicals and purified to end with acceptable surface water quality.

The whole process generates CO2-emissions in three different ways:

Sewage treatment transforms the remains of human food consumption into CO2. These emissions do not originate from fossil fuels, but from food. They remain in a short carbon cycle and do not contribute to global warming. In fact, the sludge remaining from the purification plant is an important energy source. Transport and purification processes require energy; this results in direct emissions e.g. in the case of fuel or natural gas use, and indirect emissions in the case of electricity. The use of chemicals and materials for construction, transport systems, and all other facilities and services to keep the system running does require suppliers of these goods and services to consume energy and thus causes indirect emission.

An inventory of these three different types of emissions is made for the (about) 1990 situation, the 2004 situation, and prognosticated for the 2007 situation. The 2004 situation reveals a 0.16 ton CO2 equivalent emission per person. Compared to the worldwide 4 ton emission per person, this would mean a 4% contribution from the urban water system.

With all the improvements scheduled, a 50% elimination of greenhouse gas emissions looks attainable for the 2007 situation. Further possibilities for emission reductions may be found by talking to suppliers about the indirect emissions.
Anaerobic Co-digestion of Fruit and Vegetable Waste and Sewage Sludge
Authors: Rizk Maria Cristina , Bergamasco Rosangela , Tavares Célia Regina Granhen
Published: August 2007

Fruit and vegetable wastes are generated in large quantities around the world. This kind of residue constitutes a source of nuisance in municipal landfills because of its high biodegradability. Another residue that is generated in large quantities around the world and also constitutes a source of nuisance is the sewage sludge. Both residues can be treated together by the anaerobic co-digestion process. In this sense, the aim of the present study was to evaluate the anaerobic co-digestion of fruit and vegetable waste and sewage sludge, in order to monitor the waste stabilization time and the biogas generation, among others. The study was conducted in a 70 litter stainless steel anaerobic reactor, with no mixing system, at room temperature (25±5ºC), during a period of 105 days. The fruit and vegetable wastes were collected in a central distribution market for food, and were shredded and blended before the experiment. The seed inoculum was collected in an anaerobic domestic sewage station of treatment. The parameters analyzed were: chemical oxygen demand, C/N and C/N/P ratios, pH, alkalinity, volatile fatty acids, and biogas generation. The results showed that the chemical oxygen demand was reduced around 20%. The parameters, pH, alkalinity and volatile fatty acids were stabilized, but the C/N wasnt stabilized. The final value obtained for C/N ratio was around 20/1. The biogas generation was around 331 litters and most of the biogas production occurred during the first month of the experiment. The low chemical oxygen demand removal, the high C/N ratio and the biogas generation almost always in the first few days of the experiment probably indicate that this residue, although being organic, presents difficulties in its degradation, maybe because of the high organic load that was applied to the reactor. The fact of the reactor being disproved by a mixing system can also have contributed to the low residue degradation.
Financial Aid and Student Bargaining Power
Authors: Lang David M
Published: August 2007

To say that financial aid is a key component of the college admissions process is an understatement. For the student and her family, financial aid is a way to afford quality post-secondary education that otherwise may have been unobtainable. For the college, financial aid is a method to compete for the best and brightest students. For policymakers, financial aid is a subsidy for educational expenses where constituencies often differ over its merits. This research attempts to analyze the financial aid process by considering the ability of a student to act strategically. A game-theoretic model developed by Epple, Romano, Sarpca, and Sieg (2005) is utilized and evaluated using empirical evidence from the 1996 National Postsecondary Student Aid Study (NPSAS:96). It is shown that a student can maximize her financial aid offer by increasing the number of schools to which she has been accepted after controlling for ability, demographics, state fixed effects and institutional characteristics. A matching estimator to calculate average treatment effects and properly address endogeneity concerns.
Ideology, Inequality and Inequitable Trade Policies
Authors: Djerdjian Daron O
Published: August 2007

Does more wealth inequality lead to more inequitable trade policies? To answer this question, this study develops a political economy model of international trade theory and predicts that in a pro-worker regime, an increase in wealth inequality leads to more equitable trade policies. In a pro-capitalist regime, an increase in wealth inequality leads to more inequitable trade policies. Using cross-country data on political ideology, wealth inequality and different measures of trade policies, this paper finds empirical support for these predictions.
The 1990 Clean Air Act and the Implicit Price of Sulfur in Coal
Authors: Lange Ian , Bellas Allen S
Published: August 2007

Prior to implementation of the 1990 Clean Air Act Amendments (CAAA), many estimates of the marginal cost of SO2 abatement were provided to guide policy makers. Numerous studies estimated the marginal cost of abatement to be between $250 and $760 per ton, though permits initially traded well below $200 and remained below $220 until 2004. We use a fixed effects estimator and a hedonic price model of coal purchases in order to determine the implicit price of sulfur. Data on contract coal purchases are divided into regulatory regimes based on when the contract was signed or re-negotiated. We find that purchases by Phase I plants made under contracts signed or re-negotiated after the passage of the 1990 CAAA show an implicit price of SO2 of approximately $50 per ton, an amount much closer to the eventual permit price. The implicit market price of sulfur seems to have revealed better information than did the calculations of industry experts.
Optimal Contracts for Health Services in the Presence of Waiting Times and Asymmetric Information
Authors: Siciliani Luigi
Published: August 2007

This study presents a model of optimal contracting for health services in the presence of excess demand and waiting times. We assume that: i) hospitals differ in their demand for treatment; ii) potential demand is private information of the provider; iii) specialists can dump patients; iv) activity and waiting times are contractible. A separating equilibrium exists when it is optimal for the purchaser to contract more activity and longer waiting times to those hospitals with higher demand. Hospitals with low demand gain informational rents. A pooling equilibrium may also occur.
The Informational Value of Affirmative Action in College Admissions
Authors: Furstenberg Eric K
Published: August 2007

This article develops a theoretical model of college admissions to investigate the effects of banning affirmative action admissions policies on the efficiency of the admissions process. Previous work in this area has shown that prohibiting affirmative action causes inefficiency when college quality is an increasing function of diversity. This article identifies an additional reason why colleges and universities use racial preferences in admissions, setting aside explicit demands for diversity. In the theoretical model, the racial identity of the applicants is relevant information for making inferences about an applicant's true academic ability. Preventing admissions officers from using this information results in inefficient selection of applicants, even if diversity does not explicitly enter the objective of the university. Thus, affirmative action is justified solely on informational grounds.
Skeletal Anchorage for Orthodontic Correction of Severe Maxillary Protrusion after Previous Orthodontic Treatment
Authors: Tanaka Eiji , Nishi-Sasaki Akiko , Hasegawa Takuro , Nishio Clarice , Kawai Nobuhiko , Tanne Kazuo
Published: August 2007

The correction of a severe maxillary protrusion in an adult by distal movement of the maxillary molars has been one of the most difficult biomechanical problems in orthodontics. This article reports on the treatment of an adult case of severe maxillary protrusion and a large overjet treated with a skeletal anchorage system. A female patient, age 22 years and 3 months, complained of the difficulty of lip closure due to severe maxillary protrusion with a gummy smile. Overjet and overbite were +7.6 mm and −0.9 mm, respectively. She had a history of orthodontic treatment in which her maxillary first premolars were extracted. In order to conduct distal movement of the maxillary molars, anchor plates were placed in the zygomatic process. After achieving a Class I molar relationship, retraction and intrusion of the maxillary incisors were performed. After a 2-year treatment, an acceptable occlusion was achieved with a Class I molar relationship. Her convex facial profile with upper lip protrusion was considerably improved, and the lips showed less tension in lip closure. After a 2-year retention period, an acceptable occlusion was maintained without recurrence of maxillary protrusion, indicating a stability of the occlusion. The result of this treatment indicated that skeletal anchorage is of great importance as a remedy for achieving intrusion and retraction of the maxillary incisors in cases of severe maxillary protrusion with a patient who had previous orthodontic treatment.
Oral Breathing and Head Posture
Authors: Cuccia Antonino Marco , Lotti Maurizio , Caradonna Domenico
Published: August 2007

Objective: To determine the head posture and cephalometric characteristics in oral breathing children.

Materials and Methods: Lateral cephalograms taken in natural head posture of 35 oral breathing patients (OB) (mean age 8.8 ± 2.2 years SD; range 5–13 years) and of 35 patients with varied malocclusions and physiological breathing (PB) (mean age 9.7 ± 1.6 years SD; range 7–13 years) were examined.

Results: A Student's t-test showed that an increase in angles NSL/OPT (P = .000), NSL/CVT (P = .001), FH/OPT (P = .000), FH/CVT (P = .005), and NSL/VER (P = .000); a decrease in the distance MGP-CV1p (P = .0001); and a decrease in the angles MGP/OP (P = .000) and OPT/ CVT (P = .036) were found in the OB group. A low position of the hyoid bone (H-MP, P = .009), a major skeletal divergence (ANS-PNS/Go-Me, P = .000), and an increased value of the ANB angle (P = .023) were present in OB patients. To ascertain if the changes in posture were connected with posterior obstruction of the upper respiratory airways, the OB group was divided into two subgroups based on the distance Ad2-PNS being greater than or less than 15 mm. No significant differences were found between these two groups.

Conclusions: Our data suggest that OB children show greater extension of the head related to the cervical spine, reduced cervical lordosis, and more skeletal divergence, compared with PB subjects.
Duration and Anchorage Management of Canine Retraction with Bodily Versus Tipping Mechanics
Authors: Shpack Nir , Davidovitch Moshe , Sarne Ofer , Panayi Narchos , Vardimon Alexander D.
Published: August 2007

Objective: To compare tipping mechanics (TM) and bodily mechanics (BM) with respect to duration, angulation, and anchorage loss during canine retraction.

Materials and Methods: TM and BM brackets were bonded to the upper right and left canines, respectively, of 14 subjects requiring maxillary first premolar extractions. The upper canines were retracted with variable nickel titanium closed coil springs (F = 0.50 or 0.75 N) attached posteriorly to a Nance anchorage appliance through the first molars. Panoramic radiographs and dental casts were taken at five time points. Canine angulation was assessed with custom metallic jigs inserted into the vertical slots of the canine brackets prior to radiographic exposure.

Results: The canine crown contacted the second premolar after 102.2 ± 106 and 99.0 ± 80.0 days, and achieved root uprighting in 72.0 ± 31.3 and 37.2 ± 42.7 additional days with the TM and BM groups, respectively. Only the uprighting stage differed significantly between the two mechanics (P < .05). During retraction, tooth angulation differed significantly (P < .001) between the TM (6°) and BM (−0.8°) groups. Anchorage loss, as assessed by mesial molar movement, was 1.2 ± 0.3 mm and 1.4 ± 0.5 mm for the TM and BM groups, respectively.

Conclusions: Bodily canine retraction occurred faster (38 days) than tipping due to a shorter duration of root uprighting. Anchorage loss (17%–20%) was similar for both retraction methods, ie, maximum anchorage could not be provided by the Nance appliance. Both TM and BM brackets had inadequate rotational control of the retracted canine.
Dental Status and Orthodontic Treatment Needs of an 11-Year-Old Female Resident of Athens, 430 BC
Authors: Papagrigorakis Manolis J. , Synodinos Philippos N. , Baziotopoulou-Valavani Effie
Published: August 2007

This report presents the skeletal and dental features of “Myrtis”, an 11-year-old female resident of ancient Athens back in 430 BC. Her skeleton was unearthed in an archaeological excavation of a mass burial pit located in the outskirts of Kerameikos' ancient cemetery of Athens. “Myrtis” is believed to have been one of the numerous hapless victims of the Plague of Athens.

Her skull was found in relatively intact condition bearing her complete dentition corresponding to the mixed dentition stage. A complete dental and orthodontic diagnosis of Myrtis was conducted based on clinical examination, study of panoramic radiographs, and lateral cephalometric analysis of her skull. No significant dental pathology was reported pertaining to deciduous or permanent teeth of “Myrtis”. A Class II skeletal and dental malocclusion was observed. The ectopic labial eruption of the maxillary canines mesially to their retained deciduous predecessors, the ectopic distally directed eruption of a lower first premolar, and a unilaterally missing lower third molar were among the most interesting dental findings reported.
Conventional and High Intensity Halogen Light Effects on Water Sorption and Microhardness of Orthodontic Adhesives
Authors: Uysal Tancan , Basciftci Faruk Ayhan , Sener Yagmur , Botsali Murat Selim , Demir Abdullah
Published: August 2007

Objective: To test the null hypothesis that when the equivalent total light energy is irradiated to three orthodontic adhesive resins, there is no difference between the microhardness and water sorption values regardless of the curing light sources.

Materials and Methods: Samples were divided into six groups according to the combination of three orthodontic adhesives (Kurasper F, Light-Bond, Transbond XT) and two light intensities (quartz tungsten halogen [QTH] and high intensity quartz tungsten halogen [HQTH]). One half of each of the 40 samples of three adhesive pastes was polymerized for 20 seconds by a QTH light source, and the other half was polymerized for 10 seconds by a HQTH light source. Water sorption was determined and Vickers hardness was established with three measurements per sample at the top, center, and bottom. Statistical analysis was performed using two-way analysis of variance (ANOVA) with multiple comparisons (Tukey-HSD).

Results: Statistically significant differences were found among all adhesives for water sorption and hardness values cured with QTH and HQTH. The HQTH curing unit resulted in higher values than did the QTH. The highest water sorption values were observed for Kurasper F cured with HQTH and the lowest value was observed for Transbond XT cured with QTH. For microhardness Light-Bond cured with HQTH produced the highest values, and Transbond XT cured with QTH produced the lowest.

Conclusions: When the equivalent total light energy is irradiated to three orthodontic adhesive resins, there are significant differences between the microhardness and water sorption values cured with the QTH and HQTH light source. The null hypothesis is rejected.