Elsevier

Science of The Total Environment

Volume 624, 15 May 2018, Pages 323-332
Science of The Total Environment

Characterization of how contaminants arise in a dredged marine sediment and analysis of the effect of natural weathering

https://doi.org/10.1016/j.scitotenv.2017.12.130Get rights and content

Highlights

  • In-depth study of contaminated sediments is advised for accurate management.

  • Reactive mineral species in particular framboïdal pyrite were observed in materials.

  • The natural weathering has led to a significant decrease in PAHs and organotins.

  • The leaching test revealed the low potential for release of Cu, Pb and Zn.

  • Size separation and/or a valorization in civil engineering could be envisaged.

Abstract

Millions of tons of contaminated sediments are dredged each year from the main harbors in France. When removed from water, these sediments are very reactive, therefore their geochemical behavior must be understood in order to avoid dispersion of contaminated lixiviates in the surrounding soils. In this objective, it is necessary to evaluate the principal physicochemical parameters, and also achieve advanced mineralogical characterization. These studied sediments are highly contaminated by metals, notably copper (1445 and 835 mg/kg, in the unweathered and naturally-weathered sediments, respectively), lead (760 and 1260 mg/kg, respectively), zinc (2085 and 2550 mg/kg, respectively), as well as by organic contaminants (PAH, PCB) and organometallics (organotins). A high concentration of sulfide minerals was also observed both in the unweathered sediment preserved under water (3.4 wt% of pyrite especially), and in the naturally weathered sediment (2 wt% pyrite), and in particular framboïdal pyrite was observed in the two materials.

The presence of reactive mineral species in the naturally-weathered sediment can be explained by the deposit of a protective layer, composed of sulfide and their oxidation products (sulfate and iron oxides), thus preventing oxygen from diffusing through to the sulfide minerals. Additionally, the presence of aluminosilicates aggregates coating the sulfide minerals could also explain their presence in the naturally-weathered sediment. As organic matter is one of the principal constituents of the sediments (5.8 and 6.3 wt% total organic carbon in the unweathered and weathered sediment, respectively), the aggregates are probably partially constituted of refractory humic material. It therefore appears that the natural weathering has led to a significant decrease in PAHs and organotins, but not in PCBs. The evolution of the granulometric structure and the distribution of the metallic contaminants could therefore lead us to consider a treatment by size separation, and a possible valorization of the dredged sediments in civil engineering.

Introduction

Careful management of the dredged sediment is necessary for the good operation of ports and navigable waterways. In 2010, about 18.6 million tons of sediment (dry weight) were dredged in mainland France and France's overseas territories, 33.56 million tons in 2009, and 23.2 million tons in 2008 (Le Guyader, 2011, Le Guyader, 2013). According to European legislation, once the sediments are extracted from their natural environment, they are considered as waste and thus must be consequently managed according to the legislation in force (Commission Decision of 3 May 2000 Replacing Decision 94/3/EC Establishing a List of Wastes, 2002; JORF, 2007).

These marine sediments are mainly composed of mineral species (quartz, silicates, carbonates, iron and manganese oxyhydroxides and sulfides, etc.) and organic matter. As they accumulate by the deposit of solid and colloidal matter, marine sediments are also the final “reservoir” for numerous contaminants coming from industrial and port activities, urban effluent, nautical activities or deposited in the form of aerosols. In this way, they integrate and amplify the contaminant concentrations (DelValls et al., 1998). Inorganic pollutants such as copper, zinc, lead, chromium, mercury, and arsenic, are a particular issue due to their ubiquity and persistence in the environment (Frémion et al., 2017, Jones and Turki, 1997, Caplat et al., 2005, Eek et al., 2008, Lions et al., 2010, Chatain et al., 2013a). A large number of organic pollutants also accumulate in the marine sediments such as PCBs, PAHs, residues of medicines and endocrine disruptors, as well as organometallic compounds e.g. organotin compounds principally coming from antifouling paints used to prevent aquatic organisms from attaching to boats. These compounds, frequently encountered at various concentrations in the dredged marine sediments, are considered dangerous for the environment as well as for human health (Dı́ez et al., 2002, Mamindy-Pajany et al., 2012, Casado-Martínez et al., 2009, Ribecco et al., 2011, Staniszewska et al., 2011).

To set up a long-lasting management plan for the dredged sediment, it is necessary to have more precise knowledge and more than just the degree of contamination. Therefore, it is essential to determine how the contaminants are distributed in the sedimentary matrix. Furthermore, these sediments are renowned for being particularly reactive materials following their abrupt change in surroundings after dredging; for example, when the saturation in water greatly diminishes, the redox potential increases significantly due to an increased availability of molecular oxygen. Wind and rain also induce cycles of lixiviation and drying favoring the formation of secondary mineral phases likely to control the mobility of dissolved metallic elements (Tack et al., 2006). Following these changes, these metals can be released into the lixiviation water and thus contaminate the soil if the effluent is not controlled (Caille et al., 2003, Chatain et al., 2013b, Stephens et al., 2001). Actually, the paper aim in characterizing the contaminant mineralogical speciation and their geochemical evolution during weathering under natural conditions. From this in-depth characterization, adapted management solutions could be proposed and evaluated.

Section snippets

Sampling, storage and treatment

The two sediments in this study come from the same sampling point, from a port in the south of France, submitted to an extensive anthropic activity during many centuries and contaminated by industrial activity. They were collected by dredging the 50–80 first centimeters of the harbor seabed with a mechanical shovel. The unweathered sediment was immediately put in 50 L opaque containers under a 10 cm layer of sea water to preserve the anoxic conditions and stored in a dark cold room at 4 °C.

Physicochemical parameters

Physicochemical parameters measurements were performed on both sediments. The natural pH, ORP (oxidation-reduction potential, which was afterward utilized to determine the Eh by using the standard reference electrode potential, SHE of 204 mV), and conductivity were measured on a sediment slurry with a water-sediment ratio of 1:2; after a contact time of 48 h using an Accumet® combined glass electrode. The redox potential of the sediment (ORP) was measured using a portable multi-meter (VWR

Physicochemical characterization

The values for the principal physicochemical parameters measured for the unweathered and naturally-weathered sediments are given in Table 1. As the samples come from the same sampling point they have some common characteristics for certain parameters, notably the density of 2.5 g/cm3 which is close to that of quartz (2.65 g/cm3) or carbonates (2.6–2.8 g/cm3) and a natural pH of 7.3 for both sediments. However, the bioremediation treatment and the method of conservation for the weathered sediment,

Discussion

Although the two sediments studied come from the same sampling campaign, the conditions in which they were kept have significantly influenced their physicochemical characteristics. First of all, the impact of storage in the open air after bioremediation treatment influences their redox state which increases as the saturation in water decreases. In fact, oxygen diffuses into the sediment to reach the phases sensitive to oxidation, such as the sulfides and organic matter. In the presence of

Conclusion

The characterization of dredged sediment is essentially done in order to choose and ensure the right management strategy. Both sediments studied possess a mineralogical composition typical of marine sediments. They are essentially constituted of quartz, aluminosilicates, evaporites (halite) and carbonates (37 and 52 wt% in the unweathered and naturally-weathered sediments, respectively). The two sediments contain framboïdal pyrite which shows significant signs of oxidation. In the weathered

Acknowledgments

The authors are grateful to the EEDEMS platform (French research network on waste and polluted materials management) for experimental support. The authors also acknowledge the Research and Service Unit in Mineral Technology (URSTM), University of Quebec in Abitibi-Temiscamingue (UQAT) for their experimental support.

References (68)

  • S. Dı́ez et al.

    Organotin contamination in sediments from the western Mediterranean enclosures following 10 years of TBT regulation

    Water Res.

    (2002)
  • E. Eek et al.

    Diffusion of PAH and PCB from contaminated sediments with and without mineral capping; measurement and modelling

    Chemosphere

    (2008)
  • J. Eggleton et al.

    A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events

    Environ. Int.

    (2004)
  • F. Frémion et al.

    Key parameters influencing metallic element mobility associated with sediments in a daily-managed reservoir

    Sci. Total Environ.

    (2017)
  • M.-P. Isaure et al.

    Quantitative Zn speciation in a contaminated dredged sediment by μ-PIXE, μ-SXRF, EXAFS spectroscopy and principal component analysis

    Geochim. Cosmochim. Acta

    (2002)
  • J.K. Jerz et al.

    Pyrite oxidation in moist air

    Geochim. Cosmochim. Acta

    (2004)
  • B. Jones et al.

    Distribution and speciation of heavy metals in surficial sediments from the Tees Estuary, north-east England

    Mar. Pollut. Bull.

    (1997)
  • A.L. Juhasz et al.

    Bioremediation of high molecular weight polycyclic aromatic hydrocarbons: a review of the microbial degradation of benzo[a]pyrene

    Int. Biodeter. Biodegr.

    (2000)
  • J. Lions et al.

    Metal availability in a highly contaminated, dredged-sediment disposal site: field measurements and geochemical modeling

    Environ. Pollut.

    (2010)
  • Y. Mamindy-Pajany et al.

    Ex situ remediation of contaminated sediments using mineral additives: assessment of pollutant bioavailability with the microtox solid phase test

    Chemosphere

    (2012)
  • T. Mayer et al.

    Geochemistry and toxicity of sediment porewater in a salt-impacted urban stormwater detention pond

    Environ. Pollut.

    (2008)
  • C.N. Mulligan et al.

    An evaluation of technologies for the heavy metal remediation of dredged sediments

    J. Hazard. Mater.

    (2001)
  • M.-C. Pierret et al.

    Sur l'origine de la pyrite framboïdale dans les sédiments de la fosse Suakin (mer Rouge)

    C. R. Acad. Sci. Ser. IIA Earth Planet. Sci.

    (2000)
  • P.X. Pinto et al.

    Environmental impact of the use of contaminated sediments as partial replacement of the aggregate used in road construction

    J. Hazard. Mater.

    (2011)
  • S. Piou et al.

    Changes in the geochemistry and ecotoxicity of a Zn and Cd contaminated dredged sediment over time after land disposal

    Environ. Res.

    (2009)
  • C. Ribecco et al.

    Biological effects of marine contaminated sediments on Sparus aurata juveniles

    Aquat. Toxicol.

    (2011)
  • D. Rickard et al.

    Acid volatile sulfide (AVS)

    Mar. Chem.

    (2005)
  • L. Saussaye et al.

    Trace element mobility in a polluted marine sediment after stabilisation with hydraulic binders

    Mar. Pollut. Bull.

    (2016)
  • M. Staniszewska et al.

    The relationship between the concentrations and distribution of organic pollutants and black carbon content in benthic sediments in the Gulf of Gdańsk, Baltic Sea

    Mar. Pollut. Bull.

    (2011)
  • S.R. Stephens et al.

    Changes in the leachability of metals from dredged canal sediments during drying and oxidation

    Environ. Pollut.

    (2001)
  • F.M.G. Tack et al.

    Soil solution Cd, Cu and Zn concentrations as affected by short-time drying or wetting: the role of hydrous oxides of Fe and Mn

    Geoderma

    (2006)
  • APHA

    Standard Methods for the Examination of Water and Wastewater

    (2005)
  • J. Bao et al.

    Changes in speciation and leaching behaviors of heavy metals in dredged sediment solidified/stabilized with various materials

    Environ. Sci. Pollut. Res.

    (2016)
  • M. Benzaazoua et al.

    Kinetic tests comparison and interpretation for prediction of the Joutel tailings acid generation potential

    Environ. Geol.

    (2004)
  • Cited by (26)

    • Development of a low-temperature thermal treatment process for the production of plant-growable media using petroleum-impacted dredged sediment

      2021, Science of the Total Environment
      Citation Excerpt :

      A massive amount of dredged sediment is generated worldwide every year to support human activities such as the management of navigational channels and the development of harbors (Couvidat et al., 2018; Kim et al., 2018).

    • Environmental-friendly non-sintered permeable bricks: Preparation from wrap-shell lightweight aggregates of dredged sediments and its performance

      2021, Construction and Building Materials
      Citation Excerpt :

      Dredged sediment is a natural deposit at the bottom of rivers and lakes. The total amount of dredged sediments produced by the dredging project each year was huge, and the dredged sediment is usually polluted by heavy metals, organic matter, humus, etc. [1–4]. The resource utilization is imminent to solve the problems that the massive accumulation of dredged sediment has caused serious land waste and environmental pollution.

    • Stabilization/solidification of sediments: Challenges and novelties

      2021, Low Carbon Stabilization and Solidification of Hazardous Wastes
    View all citing articles on Scopus
    View full text