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Mercury (Hg), a neurotoxicant released primarily by anthropogenic activity, is present in all the world’s oceans, estuaries, and freshwater bodies (Giang, 2013). In addition to its toxicity to marine biota, Hg bioaccumulates within fish and other seafoods, presenting a threat to human health since fish remain important sources of protein for people across the world (Giang, 2013). Despite improvements in Hg pollution control, levels in commonly consumed marine fish such as bluefin tuna often exceed human health guidelines causing recommendations to limit fish consumption (Giang, 2013). Organic forms of Hg, such as monomethylmercury (MMHg), are more toxic than other forms and are the main causes of concern for human and ecosystem health. Various forms of Hg can transform into MMHg overtime and in certain environments. Elemental mercury (Hg(0)) can transform into different chemical species before becoming MMHg while divalent mercury (Hg(II)) can transform into MMHg through biotic methylation in the water column and sediments under specific chemical and physical conditions (Ming et al., 2019).The U.S. Environmental Protection Agency (EPA) manages approximately 98 ocean dredged material disposal sites (ODMDS) around the country’s federal waters. Disposal sites are used for the disposal of nontoxic sediments that are routinely removed to maintain navigational depths in ports, harbors, and marinas, as well as to support national maritime commerce, commercial fisheries, and recreation (EPA, n.d.). The U.S. Army Corps of Engineers (USACE) is planning to dredge federal channel segments in Newport Bay in Newport Beach, California. Based on sediment samples collected and analyzed for ocean disposal testing, the USACE project sediments were found to be high in Hg contamination (Anchor QEA, LLC., 2020). However, despite the high Hg levels, toxicity tests indicated suitability for ocean disposal at EPA’s LA-3 ODMDS located offshore of Newport Bay (Anchor QEA, LLC., 2020). The current Hg levels at the LA-3 disposal site are low to non-detect, and the effects of disposing of sediments loaded with Hg from the Federal channel in Newport Bay are unknown (Battelle and DAMOSVision, 2015). To address this issue, a literature review of Hg biogeochemical cycling and Hg-methylation was conducted to assist in the understanding of Hg speciation and transport. A policy review was also completed to assess the policies relevant to sediment dredging in California and ocean dumping in federal waters. Related to the policies in place, manuals utilized by USACE and EPA for testing and analysis purposes were reviewed to determine additional sediment and water column tests to minimize the potential risk of Hg contamination in the marine environment. Through the compilation of information, testing and analysis recommendations in addition to current testing were made for the dredge and disposal site locations.

The Dredged Material Decision Tool (DMDT) was developed by the United States Environmental Protection Agency (USEPA) to allow project managers, stakeholders, and communities to quantify environmental, economic, and social considerations of using dredged material for beneficial purposes. Dredged material may be disposed in a confined disposal facility (CDF); however, this option is unfavorable because of the finite capacity problems these facilities pose. A more sustainable option is to use dredged materials beneficially such as construction material, for habitat restoration, or for brownfield remediation projects. This study demonstrates the applicability of the DMDT to three relevant candidate projects: (1) Dog Beach, Greenwood, and Lee Street Beaches (Evanston, IL, USA); (2) New York-New Jersey Harbor (New York/New Jersey); and (3) Poplar Island (Chesapeake Bay). The DMDT requires the project information and then completion of worksheets with each criteria (biophysical environment, economic, governance, social, and built environment) ranked, weighed, and scored. The DMDT is applied for all potential alternatives and the results are then analyzed to select the best beneficial reuse alternative. It was found that for the beaches in Evanston, the most beneficial option was on-beach placement with hydraulic dredging. The best option for the New Jersey Harbor was found to be using for brownfield and landfill remediation. The best option for Poplar Island was the lateral and vertical expansion of 50% uplands and 50% wetlands. Overall, DMDT is found to be a valuable tool to facilitate the evaluation of multi-criteria based on the project-specific data and help select the best beneficial use alternative for the dredged material.

Action Levels (ALs) are thresholds which are used to determine whether dredged material is suitable for disposal at sea by providing a proxy risk assessment for potential impacts to biological features such as fish and benthos. This project tested proposed scenarios for changes to the UK Action Levels to determine the likely implications for navigational dredge licensing in England and Wales. Approximately 3000 sample data records from 2009 to 2018 were collated with varying numbers of concentrations for contaminant parameters including trace metals, organotins, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). Initially, these data were assessed using current ALs to determine the percentages of the samples with levels below AL1 (generally acceptable for disposal), between AL1 and AL2 and those showing levels above AL2 (generally unacceptable for disposal). These results were then used to compare with the results of the proposed new AL scenarios for each contaminant type derived from literature reviews and historic data. The results indicate that there are changes to the ALs which could be made such as updating the current ALs with the revised ALs, as well as the introduction of ALs where there are currently none set. The benefits of changing the ALs include reducing contaminant disposal to the marine environment and increased transparency in decision making. Any proposed scenarios will need to be phased in carefully in full liaison with stakeholders.

Nowadays, sustainable environmental management of high quantities of marine dredged material (DM) together with other industrial wastes is a common problem across Turkey. The beneficial use/recovery of DM and wastes in the production of lightweight aggregate (LWA) instead of dumping at sea/disposal will provide substantial environmental savings in terms of circular economy. In this study, the production of LWA by using marine DM, coal fly ash and waste foundry sand were investigated. Three different mixtures of raw materials were granulated in pelletizing disc, dried at 105 degrees C and sintered in muffle furnace at 1100, 1150, 1170, 1180 and 1190 degrees C with 5-10 degrees C/min heating rates and 10-20 min sintering period. Sintered LWAs were analyzed in terms of physical, mechanical, microstructural, mineralogical and leaching properties. LWA produced at 1190 degrees C sintering temperature, 5 degrees C/min heating rate and 20 min sintering period resulted in better aggregate properties. Furthermore, according to the leaching test results; it is observed that the parameters of the eluate and original waste were lower than the Class III (inert waste) landfilling limit values due to the entrapment of those into the silicate matrix in sintering process; thus, causing no environmental risk to be used at construction sector.

Siltation is a big hurdle in maintaining the required depth in and around port. Dredging is required in order to maintain the desired depths in the port. Dumping of dredged material has its own impact in the surrounding area and in turn its cost effectiveness. Studies for identification of dredged material dumping ground for development of a multipurpose terminal at Karanja were carried out. Four sets of dumping grounds were initially identified and their impact was observed at three different locations. MIKE 21HD with flexible mesh setup was used for the studies. Since the capital dredging would be going on for a period of six months, model simulations with MIKE 21 HD were done for a period of one month and then extrapolated for six months period. The impact of each dumping location for continuous dumping for a period of one month was assessed using the model simulations. The time required to restore the ambient conditions once the dumping is stopped was also examined. A comparison of the suspended sediment concentration was done at some locations in the vicinity of the dumping site. A comparison on the suspended sediment concentration and the bed thickness change at different points for the different dumping ground were observed. It was found that the suspended sediment concentration will fluctuate with the tide and will attain the lowest value of 5 ppt at the dumping location. The change in bed thickness is expected to be very marginal with maximum being of the order of 5 cm and the time required restoring the ambient conditions after the dumping ceases would be about 10 to 15 days. Based on this information location of the dumping ground could be finalised which has the minimum impact on the relevant area and is cost effective.

There are many borrow pits caused by sand mining at the bottom of the coastal sea in Japan. Borrow pits have been identified as a source of oxygen-deficient water with hydrogen sulfide. It has become increasingly important to restore borrow pits to improve the marine environment. However, large quantities of sand materials are needed to restore borrow pits. Recently, dredged materials generated by sea route maintenance have been adopted instead of sand materials. However, one problem of dredged materials is that they can be weak ground materials. Therefore, slag-mixed material made from the dredged material and steelmaking slag has been proposed. In this study, control of hydrogen sulfide release resulting from changing the hardness of the slag-mixed materials has been examined. Hydrogen sulfide release strongly depends on the hardness of the slag-mixed material. Microbial analysis indicated fewer living bacteria and the relative abundance of sulfate-reducing bacteria in the slag-mixed material compared with the dredged material. The solidification of the dredged material using steelmaking slag decreased not only hydrogen sulfide release but also dissolved iron and manganese release. It is considered that controlling the hardness of the dredged material mixed with steelmaking slag provides an effective means of sulfide release control.

During the cement solidification treatment of dredged material (DM) for planting use, the pH value of treated DM may be too high and impair plants growing. To lower the pH value, methods of breaking solidified DM, adding gypsum and rice straw powder (RSP) were studied, respectively. Test results show, after breaking solidified DM, the pH value can be reduced at the first two weeks, but the value still higher than 9.0. By adding gypsum, the pH value downs quickly before 5% the content of cement, when gypsum content higher than 30%, the pH value can be controlled under 9.0. After adding RSP, the pH value decrease with RSP content and curing time, when the RSP content higher than 5%, the pH value can be lower than 9.0 in one month. The mechanism for gypsum lower the pH value may be for the acidity property and reaction with calcium hydroxide which form ettringite. The mechanism for RSW action is for the acidic matter releases from organic carbon decomposition.

To maintain the navigational depth, 1.15 million cubic meters (1.5 million cubic yards) of sediment is dredged out from the federal harbors every year from Lake Erie, Ohio Coast. Treating this huge amount of dredged material is a major challenge due to the mobilization of potential contaminants causing depreciation in water quality and depletion of valuable land. Rather than treating the dredged material as a waste, we suggest investigating alternative ways to recycle and reuse the material within Green Infrastructure (GI) and living architecture applications. This study identifies potential applications of the dredged material in bioretention and vegetative roof systems, and examines the role of dredged material in these edaphic conditions. The paper discusses the beneficial uses of dredged material in GI by investigating the quality of dredged material and performances of GI built using dredged material through laboratory and field-testing. Preliminary results of a growth media using dredged material for the vegetative roof have been developed in lab/field studies that possess the performance values comparable to the current commercial product. The growth media containing lightweight aggregate, made from the dredged material, is observed to have high water retention capacity and high unit weight in comparison to a commercial product. The growth media leachate water test demonstrated the water quality to be comparable to the drained water from the commercial product. The growth media overwintered and advanced a rare plant species, Viola pedatifida, which is similar to conventional media. The beneficial uses of dredged material in the GI will help maintain the economic viability of harbors and ports along the shoreline of Lake Erie in Ohio and GIs, which were built using dredged material that can help address storm water management issues in urban areas due to extensive impervious surfaces.

The paper reports the comparison of the results of laboratory tests conducted on reconstituted samples of high-plasticity lagoon sediment before and after ultrasonic treatment. The purpose of the work was to evaluate the effects of ultrasonic treatment on the compressibility and velocity of sedimentation and consolidation. The improvement of these geotechnical characteristics may lead to the storage of a greater volume of dredged material in the confined disposal facilities. Tests in a sedimentation column were performed in salt water to investigate the influence of ultrasonic treatment on the occurrence of two different sedimentation processes: zone settling and compression settling. The zone settling velocity of sediment subject to ultrasonic treatment was six times slower than that of natural soils and a significant variation of grain size of the particles was noted. The mechanical effect of sonication produced a reduction in coarse particles, with enrichment of the silty fraction. Different methods of consolidation testing were conducted on reconstituted samples of sediment treated with ultrasound: oedometer with standard loading sequence, with small stress increments and with constant rate of strain. Comparison of the results confirms an appreciable increase in the compression index and a reduction in the permeability of sonicated samples.

The potential impact of dredged sediment has been assessed at sixteen areas of the high-traffic port of Vilagarcia (Northwest Spanish Atlantic coast). The assessment has been done by three weight-of-evidence tools, which integrated data on sediment characteristics and toxicity responses of Ampelisca brevicornis, Vibrio fischeri and eggs and embryos of Paracentrotus lividus. Two of the tools also represented management options regarding the disposal of dredged material. The comparison of the logic in these tools revealed essential differences in the type and the necessity of bioassays and threshold values for chemical concentrations. However, despite this difference, assessment results and the derived management options coincided in most of the sediments. The potential toxicity of sediments was relatively low especially for eggs and embryos possibly due to different contaminant availability in solid and liquid phases. The importance of a battery of toxicity tests in the dredged material quality assessment has been emphasized to avoid an underestimation of sediment toxicity for solid phase organisms, if only liquid phase responses are considered. The potential false implications, which may result from the application of the third tool, were highlighted. The strengths and weaknesses of the tools were discussed from the dredged material management perspective., This work was partially supported by the financial help of the Spanish Ministry of Science and Innovation through project CTM2012-36476-C02-01/TECNO. The second author thanks the Erasmus Mundus Joint Doctorate program, employer Fundacion Universidad Empresa de la Provincia de Cadiz.

Phytoremediation is a technology that uses vegetation to remediate contaminants from water, soil, and sediments. Unlike traditional remediation techniques such as soil washing or vitrification, phytoremediation offers a technology that is solar-driven, aesthetically pleasing, and cost effective. Recent studies indicate that winter wheat (Triticum aestivum L.) is a potential accumulator for heavy metals such as lead (Pb) and cadmium (Cd) in hydroponic systems. Based on these findings, a laboratory study was conducted with the primary objective of determining the phytoaccumulation capability of this plant species for heavy metals from contaminated dredged materials (DMs) originating from two confined disposal facilities (CDF). The United States Army Corps of Engineers (USACE) manages several hundred million cubic meters of DMs each year, and 5 to 10 % of these DMs require special handling because they are contaminated with hazardous substances that can move from the substrates into food webs causing unacceptable risk outside CDFs. Phytoremediation may offer an alternative to decrease this risk. Chemical analyses by USACE personnel identified 17 metals in various DMs, but in this present study, only zinc (Zn) and Cd were investigated. Pre-germinated seeds of the test plants were planted under laboratory conditions in pots containing the various DMs and reference soil. Four weeks after planting, plants were harvested and separated into roots and shoots for biomass production and tissue metal concentrations analyses. Results showed that T. aestivum plants have the capacity to tolerate and grow in multiple-metal contaminated DMs with the potential of accumulating various amounts of Zn and Cd. Root and shoot biomass of T. aestivum were not significantly affected by the DMs on which the plants were grown suggesting that this plant species can grow just as well on DMs contaminated by various metals as in the reference soil. No significant differences in the Zn tissue concentrations were observed, differences in Cd tissue concentrations were noted. A maximum concentration of 26 mg Cd kg(-1) DW was detected in T. aestivum shoots. Although Cd tissue concentrations of T. aestivum plants in this study were below the Cd plant hyperaccumulation criterion of100 mg kg(-1) Cd found in other studies, this plant species however may still have beneficial uses for phytoremediation studies. T. aestivum plants may serve as an indicator plant for environmental assessment and management, in which the concentration of heavy metals (e.g. Cd) mirrors the concentration in the substrate without dying due to phytotoxicity at low metal concentrations.

The results of sediment quality assessment by two different weight-of-evidence methodologies were compared. Both methodologies used the same dataset but as criteria and procedures were different, the results emphasized different aspects of sediment contamination. One of the methodologies integrated the data by means of a multivariate analysis and suggested bioavailability of contaminants and their spatial distribution. The other methodology, used in the dredged material management framework recently proposed in Spain, evaluated sediment toxicity in general by assigning categories. Despite the differences in the interpretation and presentation of results, the methodologies evaluated sediment risk similarly, taking into account chemical concentrations and toxicological effects. Comparison of the results of different approaches is important to define their limitations and thereby avoid implications of potential environmental impacts from different management options, as in the case of dredged material risk assessment. Consistent results of these two methodologies emphasized validity and robustness of the integrated, weight-of-evidence, approach to sediment quality assessment. Limitations of the methodologies were discussed., This work was supported by the financial help of the Spanish Ministry of Science and Innovation, Projects CTM2011-28437-C02-02/TECNO, CTM2012-36476-C02-01/TECNO. The first author also thanks the Erasmus Mundus Joint Doctorate program, employer Fundación Universidad Empresa de la Provincia de Cádiz and Catedra UNESCO/UNITWIN_WiCop for the doctoral scholarship and administrative support.The second author also thanks Junta de Andalucía (Spanish regional government) for the Grant RNM-3924.

More than 1.15 million cubic meters (1.5 million cubic yards) of sediment require annual removal from harbors and ports along Ohio’s Lake Erie coast. Disposing of these materials into landfills depletes land resources, while open water placement of these materials deteriorates water quality. There are more than 14,000 acres of revitalizing brownfields in Cleveland, U.S., many containing up to 90% impervious surface, which does not allow “infiltration” based stormwater practices required by contemporary site-based stormwater regulation. This study investigates the potential of sintering the dredged material from the Harbor of Cleveland in Lake Erie to produce lightweight aggregate (LWA), and apply the LWA to green roof construction. Chemical and thermal analyses revealed the sintered material can serve for LWA production when preheated at 550 °C and sintered at a higher temperature. Through dewatering, drying, sieving, pellet making, preheating, and sintering with varying temperatures (900–1100 °C), LWAs with porous microstructures are produced with specific gravities ranging from 1.46 to 1.74, and water absorption capacities ranging from 11% to 23%. The water absorption capacity of the aggregate decreases as sintering temperature increases. The LWA was incorporated into the growing media of a green roof plot, which has higher water retention capacity than the conventional green roof system.

Sediments excavated from dredging operations are known as dredged materials. Beneficial reuse of dredged materials in confined utilization facilities (CUFs) is a new approach that has the potential to productively utilize large quantities of dredged materials. However, several factors can inhibit the use of dredged materials in CUFs. In this study, high levels of salts and polycyclic aromatic hydrocarbons (PAHs) were investigated. In the first part of this study, 176,000 m3 of saline dredged materials was placed into a CUF. In less than 4 years, most of the dredged materials had developed horizonation and converted to Inceptisols. The formation of pedogenic Bg horizons in these soils occurred after a polygonal prism network had developed which partially disintegrated into a blocky structured, oxidized horizon with an abundance of redoximorphic features. During the study period, the soil chemistry of the weathering dredged materials shifted from Na-dominated to Ca and Mg-dominated system, allowing plant invasion. In the second part of the study, a bench-scale greenhouse bioremediation experiment was conducted to test the effectiveness of biosolids, compost, and straw at enhancing PAH degradation. Initial concentrations of PAHs decreased significantly after 150 days using standard methods of extraction. However, at 327 days the concentrations of many PAHs, especially those with higher molecular weights, had rebounded close to initial levels. This indicates that PAH bioremediation studies using organic matter additions and conducted using standard methods of extraction need to be carried out longer periods of time or that extraction methods need to be improved. Master of Science

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.

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.

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.

Source: https://erdc-library.erdc.dren.mil/jspui/ A comprehensive physical oceanographic field study was conducted in November 1986 to determine the bathymetry of the New York Mud Dump site and assess the long-term stability of an experimental sand cap, or mud dump (EMD), located in the southeast quadrant of the site. Results of a precision bathymetric survey were compared with results from surveys conducted in 1980 and 1981. A REMOTS® sediment-profile survey was conducted over the entire site, and a subbottom profiling survey was conducted at the EMD. A significant accumulation of sediment was found at the dredged material disposal point in the northeast quadrant, and decreases in depth to the south and east of this point indicated accumulation of dredged material beyond the eastern boundary of the site. Significant erosion of the sand cap was not detected, and clean sand representing the final cap material was found to persist in a continuous layer in the center of the EMD. A few patches of finer-grained material, possibly dredged material transported from the north, were found to exist over the sand. The effects of bioturbation on the sand cap appeared to be negligible. It was suggested that monitoring should occur during and following disposal operations to ensure adequate management control and later to assess the stability and environmental impacts of disposal mounds.