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Dredged material can cause several negative impacts to the ecosystems. Its management is a key issue for the protection of the aquatic environments. Sediment quality guidelines alone are not able to estimate the potential adverse effects that contaminants bound to sediment can cause. The in situ approach using caged bioindicator species has been chosen lately as a new sensitive tool for the assessment of dredged material. In a tier testing approach, Neutral Red Retention Assay (NRRA) has been applied as a screening tool in order to detect adverse changes in health status associated to contaminated environments. Nevertheless, to the authors' knowledge, little is known about the application and validation of NRRA in sediment bioindicator species and under field conditions. Caged Ruditapes philippinarum and Carcinus maenas were exposed during 28 days to 3 potentially contaminated sites in the Algeciras Bay (SW Spain) and to a reference site in the Cadiz Bay (SW Spain). Health status of exposed organisms was measured through NRRA in haemolymph samples. No significant differences of Neutral Red Retention Time (NRRT) were measured neither in clams nor in crabs over time in the organisms from control site (70 ± 10min). However significant differences (p < 0.05) were found at the end of the exposure period in clams and crabs exposed to contaminated sediments from Algeciras Bay, showing a decrease of NRRTs from 30 to 70% compared to the control organisms. The results obtained confirmed the use of NRRA as a suitable and sensitive method to be used in the assessment of sediment quality.

Caged, transplanted, intermoult, female shore crabs (Carcinus maenas) were exposed to sediments from the Port of Cadiz (SW, Spain); the Port of Huelva (SW, Spain), the Port of Pasajes (NE, Spain) and the Port of Bilbao (NW, Spain) for a period of 28 days. Organisms were sampled on days 0, 7, 14, 21 and 28 allowing examination of different biomarkers to exposure to metals and organic compounds; metallothioneins (MTs), ethoxyresorufin O-deethylase (EROD), glutathione-S-transferase (GST) and glutathione peroxidase (GPX). Sediment samples were also analyzed to determine chemical concentration of metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn), PAHs and PCBs. Metals such as As, Cu and Zn associated with mining activities (Port of Huelva), and contaminants such as Ni, Pb, Hg and PCBs, associated with oil spills and industrial activities (Ports of Cadiz, Pasajes and Bilbao), were found to interfere in detoxification and/or anti-stress oxidative defenses in C. maenas. Positive, significant (p0.05) induction of MTs concentration was associated with increasing sediment As, Cu, Zn and Hg concentrations. EROD activity was associated with PCBs, GST activity with Hg and GPX activity with As, Cu, Ni, Pb and Zn. The use of the parameter AR, which involves the kinetic patterns of the battery of biomarkers tested, was found to be a powerful and sensitive tool for evaluating the bioavailability and adverse effects of contaminants bound to sediments, enabling polluted and nonpolluted sites to be easily distinguished.

14 páginas, 4 figuras, 2 tablas., Recent research efforts in sediment and dredged material assessment research have focused on the inclusion of sublethal endpoints (biomarkers) in acute and long-term bioassays for dredged material characterisation and management. The incorporation of biomarkers as a new line of evidence in a weight of evidence approach allows the determination of more sensitive, longer-term biological information for use in laboratory and in situ sediment/tissue quality guidelines., This work was conducted under the framework of the projects INTEGRAL (Spanish Ministry of Education and Science; CTM2005-07282-C03-C01/TECNO; PHB2005-0100-PC) and was partially financed by the Master Erasmus Mundus (UNESCO/UNITWIN/WiCop and Unidad Asociada CSIC). Dr. Laura Martín-Díaz would like to thank the Juan de la Cierva Program (Ministry of Education and Science).

10 páginas, 4 figuras, 3 tablas., Two marine invertebrates, the crab Carcinus maenas and the clam Ruditapes philippinarum, were used as bioindicator species to assess contamination when exposed in situ to sediment from different sites from four Spanish ports Cadiz (SW Spain), Huelva (SW Spain), Bilbao (NE Spain) and Pasajes (NE Spain). In an attempt to determine sediments toxicity, a combination of exposure biomarkers was analyzed in both species: metallothionein-like-proteins (MTLPs), ethoxyresorufin O-deethylase (EROD), glutathione S-transferase activity (GST), glutathione peroxidase (GPX) and glutathione reductase (GR). In parallel, physical and chemical characterization of the different sediments was performed and biological responses related to the contaminants. Significant induction of MTLPs was observed when organisms were exposed to metal contaminated sediments (port of Huelva), and EROD and GPX activities after exposure to sediments containing organic compounds (port of Bilbao and Pasajes). No significant interspecies differences were observed in biomarker responses except for the GST and GR., This research has been funded by the Project of the Spanish Government (CTM2005-07282-C03-C01/TECNO)

The disposal of contaminated dredged material has become an economical and environmental issue. Firstly, this study presents the Novosol® process which was used for the treatment of polluted sediments. This process is based on the stabilisation of heavy metals and on the thermal elimination of organic matter. A physical characterization of the processed material reveals high porosity (60%) and water absorption (45%). Moreover, the treated sediment aggregate (TSA) has a relatively low strength and a high content of fine particles. Secondly, an experimental study on the feasibility of TSA introduction in cement-based materials was performed. Three mortars for which a given sand volume was replaced by the same sediment volume (33%, 66% and 100%) were designed. A strong increase of drying shrinkage was observed (up to 10 times higher, when compared to a reference mortar). Permeability remained virtually constant, though. There was a significant increase in strength for low to moderate substitution, while high incorporated quantity of sediment led to a strength on the same order of that of the reference mortar.

Dredging is a necessary maintenance operation on harbours, access channels and rivers. Dredged volumes are significant and heavy metals and organic pollutants contaminate a large part of them. Their management has become an environmental and economical concern for a large number of countries. The Novosol® process, developed by Solvay, offers a reliable solution for the treatment of sediments. This process is divided into two distinct parts: phosphatization to stabilise heavy metals and calcinations in order to eliminate organic matter. As a result, sediments, treated like this, can be regarded as a new product which could be valorisable.The feasibility of sand substitution in cementitious materials has been investigated in this study.A characterisation study of this new material was performed and has revealed a low strength, a high porosity and amount of absorbed water, and a coating of fine particles. For both strength and permeability, standard levels of performances were reached for substituted mortars. This was attributed to the improvement of compactness, hydration and paste aggregate interface quality. Characteristics such as high porosity and drying shrinkage have underlined the restrictions on application area. A durability study focused on the impact of various parameters on the performances and resistance to aggressive conditions such as freeze/thawing cycles or sea water exposure was performed. It demonstrated the importance of the granulometry of the substitution to reduce porosity and increase material durability.The study proved the practical feasibility of treated sediment introduction in cement based materials and the quality of the produced material.; L'accumulation des sédiments au fond des cours d'eau et des ports pose un problème économique et environnemental. En effet, les particules les plus fines fixent une contamination à la fois organique (HAP, PCB, hydrocarbures) et inorganique (métaux lourds). Une législation de plus en plus sensible à la protection de l'environnement réglemente désormais le dragage et le relargage des sédiments. La société Solvay a mis au point un procédé de traitement baptisé Novosol®, basé sur l'immobilisation des métaux lourds par phosphatation et sur l'élimination des matières organiques par calcination.La valorisation des sédiments traités comme granulat de substitution dans les matériaux à matrice cimentaire fait l'objet de ce travail de thèse.La caractérisation de ces granulats a révélé une porosité et une absorption d'eau très élevées. Constitués par l'agglomération de particules plus fines ils se révèlent friables. Cependant, utilisés en substitution d'un sable de Seine classique pour la confection d'un mortier, l'étude expérimentale de valorisation a montré des gains de résistance à la compression uniaxiale, et ce, même pour une substitution complète du sable. Ces gains ont été attribués au phénomène de cure interne, à l'amélioration de l'interface pâte granulat ainsi qu'à un effet filler. Cela pourrait également expliquer la réduction observée de la perméabilité au gaz. La déformabilité des granulats conduit toutefois à un retrait de dessiccation élevé. Une formulation appropriée permet également l'obtention d'un matériau durable vis-à-vis, notamment, du gel/dégel ou de l'exposition à l'eau de mer.La valorisation dans les matériaux cimentaires est donc envisageable.

8 páginas, 1 figura, 3 tablas., [EN] Several species of bivalves and procedures have been used to characterize sediment toxicity. Here we report the results of an interlaboratory exercise that included three different laboratories to evaluate the use of the bioassay using the commercial clam Ruditapes philippinarum. Six different dredged sediments were studied using two different endpoints: lethality after two different exposure periods (7 and 14 days) and burrowing activity after 48 h of exposure. The lethal endpoint was only sensitive to characterize samples with high metallic concentration and following the 14-day exposure period. The burrowing activity showed very variable results that evidence the unsuitability of this endpoint for dredged material characterization. According to these results, a new design is recommended for the test using juvenile bivalves if it is to be used to characterize sediment samples on a regulatory context especially if sediments are not affected by metallic contamination., [ES] Este estudio resume los resultados del ejercicio interlaboratorio realizado en tres laboratorios para evaluar el uso del ensayo con la almeja comercial de Manila Ruditapes philippinarum. Seis muestras de sedimentos dragados se estudiaron mediante dos medidas finales distintas: mortalidad tras dos periodos de exposición distintos (7 y 14 días) y la medida subletal que estudia el porcentaje de organismos enterrados tras 48 h desde el inicio de la exposición. La medida de la letalidad fue sólo sensible tras el periodo más largo de exposición y la contaminación metálica más elevada. La actividad de enterramiento mostró resultados muy variables y altamente dependientes del operador responsable. De acuerdo con estos resultados se recomienda la revisión del protocolo para mejorar su uso en la gestión de dragados portuarios especialmente si se trata de zonas no afectadas por contaminación metálica., Este trabajo fue financiado parcialmente por el Ministerio de Ciencia y Tecnología (REN2002_01699/TECNO). El diseño de los ensayos de toxicidad para la caracterización de material de dragado se realizó mediante un proyecto conjunto entre el CEDEX y la Universidad de Cádiz (2001 y 2003). MC Casado fue financiada por el Ministerio Español de Educación y Ciencia en el programa de Formación de Personal Investigador (FPI).

9 páginas, 3 figuras, 4 tablas., [EN] The present paper reports the results of an interlaboratory variability study of a bioassay using larval stages of the marine sea urchin Paracentrotus lividus. This exercise was developed in two different phases and included four laboratories, each of which determined the toxicity of six sediment samples. The samples were collected from different Spanish ports and were characterized by exposing sea urchin embryos for 48 h to sediment elutriates. Phase I was used to redesign test parameters and to avoid possible interfering factors when interpreting test results. Laboratories were more homogeneous in the classification of sediments according to the toxic responses in Phase II despite the high variability of the elutriate testing protocols. Based on our results, the test seems suitable to characterize dredged material, the interlaboratory variability being similar to that found for other bioassays in previous studies., [ES] El presente trabajo resume los resultados del ejercicio realizado para estudiar la variabilidad interlaboratorio del ensayo con estadios larvarios del erizo de mar Paracentrotus lividus. Este ejercicio, que se desarrolló en dos fases distintas, incluyó cuatro laboratorios cada uno de los cuales estudió la toxicidad de las seis muestras de sedimento distribuidas. Las muestras, provenientes de distintos puertos de la costa española, se caracterizaron mediante la exposición de embriones del erizo de mar Paracentrotus lividus durante 48 h a los lixiviados de los sedimentos. La Fase I se utilizó para rediseñar las condiciones del ensayo y evitar posibles factores de confusión al interpretar los resultados. Los resultados de la Fase II fueron más homogéneos al clasificar las muestras según la toxicidad registrada, a pesar de la variabilidad en los protocolos de obtención y ensayo de los lixiviados. De acuerdo con estos resultados, el ensayo es adecuado para la caracterización de este tipo de muestras con una variabilidad interlaboratorio similar a la encontrada para otros bioensayos en estudios interlaboratorio previos., Este estudio fue parcialmente desarrollado bajo subvención del Ministerio Español de Ciencia y Tecnología (REN2002_01699/TECNO). El diseño de los ensayos agudos para la caracterización de materiales de dragado se realizó en un proyecto conjunto entre el CEDEX y la Universidad de Cádiz (2001 y 2003). MC Casado-Martínez agradece la financiación del Ministerio Español de Educación y Ciencia en el programa de becas de Formación de Personal Investigador (FPI).

9 páginas, 3 figuras, 4 tablas. [EN] The present paper reports the results of an interlaboratory variability study of a bioassay using larval stages of the marine sea urchin Paracentrotus lividus. This exercise was developed in two different phases and included four laboratories, each of which determined the toxicity of six sediment samples. The samples were collected from different Spanish ports and were characterized by exposing sea urchin embryos for 48 h to sediment elutriates. Phase I was used to redesign test parameters and to avoid possible interfering factors when interpreting test results. Laboratories were more homogeneous in the classification of sediments according to the toxic responses in Phase II despite the high variability of the elutriate testing protocols. Based on our results, the test seems suitable to characterize dredged material, the interlaboratory variability being similar to that found for other bioassays in previous studies. [ES] El presente trabajo resume los resultados del ejercicio realizado para estudiar la variabilidad interlaboratorio del ensayo con estadios larvarios del erizo de mar Paracentrotus lividus. Este ejercicio, que se desarrolló en dos fases distintas, incluyó cuatro laboratorios cada uno de los cuales estudió la toxicidad de las seis muestras de sedimento distribuidas. Las muestras, provenientes de distintos puertos de la costa española, se caracterizaron mediante la exposición de embriones del erizo de mar Paracentrotus lividus durante 48 h a los lixiviados de los sedimentos. La Fase I se utilizó para rediseñar las condiciones del ensayo y evitar posibles factores de confusión al interpretar los resultados. Los resultados de la Fase II fueron más homogéneos al clasificar las muestras según la toxicidad registrada, a pesar de la variabilidad en los protocolos de obtención y ensayo de los lixiviados. De acuerdo con estos resultados, el ensayo es adecuado para la caracterización de este tipo de muestras con una variabilidad interlaboratorio similar a la encontrada para otros bioensayos en estudios interlaboratorio previos. Este estudio fue parcialmente desarrollado bajo subvención del Ministerio Español de Ciencia y Tecnología (REN2002_01699/TECNO). El diseño de los ensayos agudos para la caracterización de materiales de dragado se realizó en un proyecto conjunto entre el CEDEX y la Universidad de Cádiz (2001 y 2003). MC Casado-Martínez agradece la financiación del Ministerio Español de Educación y Ciencia en el programa de becas de Formación de Personal Investigador (FPI).

7 páginas, 4 figuras, 3 tablas., Sediment quality assessments for regulatory purposes (i.e. dredged material disposal) are characterized by linking chemical and acute ecotoxicological data. The design of chronic bioassays that incorporate more sensible endpoints than acute tests is discussed to address sediment quality for environmental quality assessment and regulatory proposes. The chronic tests use juveniles of commercial species of fish Sparus aurata and Solea senegalensis, to assess sediment toxicity in samples collected along different littoral areas in the North and the South of Spain. The organisms were exposed during 60 days and sublethal endpoints were selected including biomarkers of exposure to metals (metallothioneins — MTs) and to organic contaminants (ethoxyresorufin-O-deethylase activity — EROD activity) and biomarkers of effect (histopathology in different tissues, gill and liver). A Multivariate Analysis Approach was conducted in order to associate these biological responses with sediment metal concentration from the ports and with chemical residues in biological tissues exposed to sediments under laboratory conditions., The work was partially funded by the Spanish ministry for Development (BOE 13/12/2002) and Ministry for Science and Education (CTM2005-07282-C03-01/TECNO). Maria Jose Salamanca thanks the i3p program for her fellowship. Carmen Morales thanks MEC for her FPU fellowship.

9 páginas, 2 figuras, 3 tablas., [EN] Interlaboratory variability was studied for the bioassay using crustacean amphipods. Nine series of data were obtained from different laboratories using four different species (Ampelisca brevicornis, Corophium volutator, Corophium multisetosum and Microdeutopus gryllotalpa), all previously used for sediment toxicity assessment in Spain. Results were studied for interlaboratory variability and according to different confounding factors. The coefficients of variation were similar to those previously reported for this bioassay and sample classification was homogeneous among the laboratories that successfully completed the exercise. No significant tendencies related to test species were identified and it seems that the factor most critically affecting test results and the classification of samples is storage time before testing., [ES] Se estudió la precisión interlaboratorio del bioensayo con crustáceos anfípodos. Se recogieron nueve series de datos procedentes de distintos laboratorios europeos y de cuatro especies distintas (Ampelisca brevicornis, Corophium volutator, Corophium multisetosum y Microdeutopus gryllotalpa), todas ellas usadas previamente para la caracterización de la toxicidad de sedimentos en España. Esos resultados se estudiaron para evaluar la variabilidad interlaboratorio de acuerdo a las diferentes especies y los distintos tiempos de almacenamiento de las muestras antes del ensayo. Los resultados mostraron coeficientes de variación similares a los encontrados en estudios previos y permitieron una clasificación homogénea de las muestras entre los laboratorios que completaron el ejercicio con éxito. No se identificaron tendencias significativas debidas al uso de distintas especies y, al parecer, el factor que puede afectar más críticamente la clasificación de las muestras y, por lo tanto, el uso de los resultados para la toma de decisiones, es el tiempo de almacenamiento de los sedimentos previamente al desarrollo del ensayo., This study was carried out under a joint research project between CEDEX and the University of Cádiz. Part of the work was funded by the Spanish Ministry of Science and Technology REN2002_01699/TECNO). The first author was supported by a grant (FPI) from the Spanish Ministry of Education and Science.

10 páginas, 1 figura, 6 tablas., [EN] The Microtox® bioassay was tested in an interlaboratory study to evaluate the variability when using solid-phase samples. The exercise consisted of two consecutive phases each one carried out with six sediment samples from Spanish ports. Phase I included six laboratories that reported results for the solid-phase test (SPT) protocol, while Phase II included seven laboratories for the SPT protocol and three laboratories for the basic solid-phase test (BSPT) protocol. Even though some interfering factors were identified that could affect the results and sample classification, the coefficients of variation (CV) can be considered in the range for biological tests. When these factors are considered for further assessments, interlaboratory variability is significantly reduced. The BSPT showed lower CV values than the SPT despite the small number of participating laboratories. This better performance may be explained either by the simplicity of the methodology., [ES] El presente trabajo resume el ejercicio interlaboratorio realizado para evaluar la variabilidad del ensayo Microtox® sobre fase sólida. El ejercicio se dividió en dos fases consecutivas, cada una de ellas desarrollada sobre seis muestras de sedimento de puertos españoles. La Fase I incluyó seis laboratorios y se obtuvieron resultados para el protocolo SPT (Solid Phase Test). La Fase II incluyó siete laboratorios y, además de obtenerse resultados del protocolo SPT, tres de ellos utilizaron también el protocolo para la fase sólida BSPT (Basic Solid Phase Test). Si bien se han identificado factores que pueden tener un cierto efecto sobre los resultados, y por lo tanto en la clasificación de las muestras, los coeficientes de variación obtenidos pueden considerarse entre los valores normales para ensayos biológicos. Si esto se tiene en cuenta para el análisis de los resultados, especialmente para los de la Fase I, la variabilidad baja considerablemente. El protocolo BSPT obtuvo resultados más consistentes que el protocolo SPT aun contando sólo con los resultados de un número reducido de laboratorios. La mayor simplicidad del ensayo pudo ser la causa de esta menor variabilidad., Parte del trabajo fue subvencionado por el Programa Nacional del Ministerio Español de Ciencia y Tecnología (REN2002_01699/TECNO). MC Casado-Martínez agradece la financiación del Ministerio Español de Educación y Ciencia en el programa de becas de Formación de Personal Investigador (FPI).

International audience; In rivers, sediments are frequently accumulating persistent chemicals, especially for those that are more contaminated as a consequence of pressure related to environmental pollution and human activity. The Seine river basin (France) is heavily polluted from nearby industrial activities, and the urban expansion of Paris and its suburbs within the Ile de France region and the sediments present in the Seine river basin are contaminated. To ensure safe, navigable waters, rivers and waterways must be dredged. In this paper, the quality of the sediment dredged in 1996, 1999 and 2000 is discussed. Physico-chemical characteristics of the sediment itself and of the pore-water are presented. Seine basin sediments show very diverse compositions depending on the sampling site. Nevertheless, a geographic distribution study illustrated that the Paris impact is far from being the only explanation to this diversity, the quality of this sediment is also of great concern. The sediment once dredged is transported via barges to a wet disposal site, where the dredged material is mixed with Seine water in order to be pumped into the receiving site. This sort of dumping might be responsible for the potential release of contaminants to the overlying water from the significantly contaminated sediments.

The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dutch coast was investigated using the dioxin receptor-chemically activated luciferase gene expression (DR-CALUX) bioassay. The DR-CALUX response varied between 0.2 and 136 ng/kg dry weight expressed in units of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalency quotients (TEQ). The highest CALUX-TEQ values (50 ng TEQ/kg dry wt) were found in sediments from the center of the Port of Rotterdam and from the North Sea canal near Amsterdam. The DR-CALUX activity of harbor sediments was classified by setting guideline values. None of the 257 harbor sediment samples investigated exceeded the maximum value of 1,000 ng TEQ/ kg, while 94% of the samples fail the target value of 2 ng TEQ/kg. Threshold values (25 and 50 ng TEQ/kg) are intended as pass/ fail criteria for offshore disposal of dredged material and were exceeded in 12 and 3% of the samples, respectively. DR-CALUX response did not always match with contamination of polychlorinated biphenyls (PCBs) as determined in bulk sediments (sigma7-PCB ranging from1 to 456 microg/kg dry wt). Concentrations of planar PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated-dibenzofuranes (PCDFs), polybrominated biphenyls (PBBs), and polybrominated-diphenylethers (PBDEs) were determined in 20 selected sediment extracts. On average, PCDD/Fs explained 50% of the DR-CALUX activity and planar PCBs 6%. Further research is needed to elucidate the unexplained part of the DR-CALUX response. The DR-CALUX is a highly sensitive and reproducible bioassay that can usefully complement standard PCB analysis, improving the hazard assessment of the disposal of dredged material in the North Sea.

Disposal sites for dredged material are often polluted with heavy metals. The uptake of Cd and Zn by small mammals and willow trees was assessed on three sites with a different pollution degree. Detailed soil sampling showed a huge variation in soil characteristics within the sites, typical for disposal sites for dredged material. This variation made risk assessment and interpretation of soil chemical analyses complicated. Small mammals were thought to give a more integral description of the contaminant level because they cover a large area. Cd concentrations in small mammals were elevated compared with background levels whereas Zn concentrations were rather low. There were no significant differences between sites in Cd or Zn levels in animals. Leaf analysis showed a clear response to the pollution degree of the sites. The calculations using the BIOMAG model indicated that the Cd of the soil caused low risk for predators. However, the elevated Cd and Zn concentrations in the willow leaves on the polluted sites and the high Cd concentrations in the small mammals on all sites indicated that ecosystem development should be carefully considered. Copyright ?? 2001 Elsevier Science Ltd.

A decision support system for treatment of dredged sediments (DSTS) has been constructed, in which the environmental effects of various treatment options applied can be compared. The effects are evaluated by scores on environmental themes like global warming and acidification, using life cycle assessment methodology.

A decision support system for treatment of dredged sediments (DSTS) has been constructed, in which the environmental effects of various treatment options applied can be compared. The effects are evaluated by scores on environmental themes like global warming and acidification, using life cycle assessment methodology.

During April 1997, a cultural resource assessment survey was conducted of a proposed dredged material management area and associated pipeline access route in Brevard County, Florida. The intent of this survey was to locate and assess the potential significance of all cultural resources within the proposed BV-11 dredged spoil location and associated pipeline route.

The Arap and Melez Rivers discharge to Izmir Bay bringing wastewater together with rainwater coming from their catchment areas. There is an artificial harbor built at the discharge point of the Melez River acting as a sedimentation area for the suspended matter carried by these rivers. This area has a storage capacity of 3 to 4 years. After this period, the sediments are dredged and disposed from the region. In this study, various studies were carried out in order to determine the geotechnical properties and pollution parameters of the sediments; the results of many previous studies are also given. In the analyses done on dredging samples, it was observed that sulfur, oil and grease, phosphorus, nitrogen and heavy metal concentrations were very high. The reason for these high concentrations is the direct discharge of untreated wastewater formed in the industries located along the Arap and Melez Rivers. The pollutants carried to Izmir Bay by these rivers then settle down inside the artificial harbor and reach high concentrations in bottom sediments. As a result of this study, some possible environmental effects of land disposal of this material are discussed and suggestions are given for final disposal alternatives. © 1995, International Association on Water Quality. All rights reserved.

Source: https://erdc-library.erdc.dren.mil/jspui/ The installation, testing, and analysis of data from an automated monitoring system aboard a contract hopper dredge is detailed in this report. The automated dredge monitoring system consists of sensors to monitor the dredge displacement, volume of material in the hopper, velocity and density of material in the drag arms, drag arm depth, and vessel position, as well as a data acquisition system to store and manage the information. The data are recorded continuously during two dredging projects performed for the U.S. Army Corps of Engineers. Detailed analysis of the data is performed to determine the bin measure production and overflow efficiency during the two projects. A detailed uncertainty analysis is also performed.

The problems associated with contaminated dredged material disposal (basically lack of disposal sites and potential adverse environmental impacts) have become major issues in many industrialized and developing countries. The sediment removed for environmental reasons is obviously contaminated, but in many cases the sediment removed during normal maintenance dredging of waterways and harbours also contains a wide range of potentially toxic substances. In the Netherlands for instance, out of the 50 million m3 of dredged material produced annually during normal maintenance dredging work 20 million m is contaminated to such a degree that its dispersion into the environment without measures to impede contaminant release is unacceptable (Vellinga, 1989). This paper gives a review of the disposal and treatment options currently in use or considered to have the potential for practical use in the near future with an emphasis on land disposal. It briefly discusses the main contaminant release pathways, the governing processes and the state-of-the-art methodology, used to assess potential environmental impacts.

Assessment of the environmental risk of discharges, containing both chemicals and suspended solids (e.g., drilling discharges to the marine environment), requires an evaluation of the effects of both toxic and nontoxic pollutants. To date, a structured evaluation scheme that can be used for prognostic risk assessments for nontoxic stress is lacking. In the present study we challenge this lack of information by the development of marine species sensitivity distributions (SSDs) for three nontoxic stressors: suspended clays, burial by sediment, and change in sediment grain size. Through a literature study, effect levels were obtained for suspended clays, as well as for burial of biota. Information on the species preference range for median grain size was used to assess the sensitivity of marine species to changes in grain size. The 50% hazardous concentrations (HC50) for suspended barite and bentonite based on 50% effect concentrations (EC50s) were 3,010 and 1,830 mg/L, respectively. For burial the 50% hazardous level (HL50) was 5.4 cm. For change in median grain size, two SSDs were constructed; one for reducing and one for increasing the median grain size. The HL50 for reducing the median grain size was 17.8 mum. For increasing the median grain size this value was 305 mum. The SSDs have been constructed by using information related to offshore oil- and gas-related activities. Nevertheless, the results of the present study may have broader implications. The hypothesis of the present study is that the SSD methodology developed for the evaluation of toxic stress can also be applied to evaluate nontoxic stressors, facilitating the incorporation of nontoxic stressors in prognostic risk assessment tools.