Contaminated Sediments News

Recent Journal Articles of Interest

• Kintetics of PCB Dechlorination by Microorganisms in the Hudson River - The kinetics of PCB dechlorination by Hudson River sediment microorganisms were investigated using Aroclor 1242 at 10 different concentrations. Dechlorination rate was a linear function of PCB concentrations, similar to the dechlorination of Aroclor 1248 by sediment microorganisms from the St. Lawrence River (New York); however, the rate was much slower. The threshold concentration below which no dechlorination occurs averaged 1.06 micromol Cl/g sediment, threefold higher than that for the dechlorination of Aroclor 1248. The results also showed that the maximum extent of dechlorination was greater at higher Aroclor concentrations. The microorganisms did not show any significant growth until late in the lag phase of dechlorination, and their maximum was greater at higher initial Aroclor 1242 concentrations. Although dechlorination rates were significantly lower for the Hudson River, when normalized they were not significantly different from those for Aroclor 1248 by St. Lawrence River microorganisms. This study lends support to the idea that PCB dechlorination is tightly linked to the growth of dechlorinating microorganisms.

  Source: Cho, Y C, R C Sokol, and G Y Rhee. 2002 (April). Kinetics of polychlorinated biphenyl dechlorination by Hudson River, New York, USA, sediment microorganisms. Environmental Toxicolology and Chemistry Volume 21(4): 715-719.

• Sediment Toxicity Test for Metal Bioavailability with Sediment pH Changes - This study investigated acidic pulses caused by rewetting of oxidized acid-sulfate soil each wet season in the Magela floodplain of northern Australia (a major sink for dissolved metals in the area). These acidic pulses have the potential to alter the bioavailability of sediment-associated metal contaminants. Acute toxicity tests using the tropical chironomid Chironomus crassiforceps showed that copper and uranium were less toxic at lower sediment pH. Sediment toxicity tests developed using C. crassiforceps also showed that both metals were less toxic at the lower sediment pH. However, a lower pH increased pore-water metal concentrations and overlying water concentrations in bioassays. The authors propose that hydrogen ion competition on metal receptor sites in C. crassiforceps might explain the decrease in toxicity in response to increased H+ activity. This study highlights the importance of site-specific physicochemical conditions which might affect the use of generic risk assessment methods.

  Source: Peck, M R, D A Klessa, and D J Baird. 2002 (April). A tropical sediment toxicity test using the dipteran Chironomus crassiforceps to test metal bioavailability with sediment pH change in tropical acid-sulfate sediments. Environmental Toxicology and Chemistry Volume 21(4):720-728.

• Fate and Transport of PCB Congeners in the Great Lakes - Transport and fate of PCB congeners in three Great Lakes food webs were compared using a food web bioaccumulation model. The model was used to quantify the contribution of sediment-derived and freely dissolved PCBs to the body burden of aquatic biota. Results showed that the chemical body burden originating from sediment varies in different food webs. For instance, in eastern Lake Erie, almost 100% of the chemical body burden of biota originates from sediment, while in western Lake Erie, benthic invertebrates and fish accumulated close to half of their chemical body burden from sediment. Field data and the model were also used to determine the effects of declining concentrations of PCBs in water and sediment on concentrations of PCBs in aquatic biota. These results indicate that as concentrations of PCB congeners in the ecosystem decline, the importance of sediment as a source of contaminant to aquatic biota increases. As sediment becomes the predominant source of contaminant to aquatic biota, the concentration of PCB congeners in biota tends to equilibrium with bottom sediment.

  Source: Morrison, H A, D M Whittle, and G D Haffner. 2002 (April). A comparison of the transport and fate of polychlorinated biphenyl congeners in three Great Lakes food webs. Environmental Toxicolology and Chemistry Volume 21(4): 683-92.

• SFE Method for Determination of Desorption Behavior of PCBs in Sediments - A supercritical fluid extraction (SFE) method was applied to determine the distribution of individual PCB congeners among sites of differing bonding strengths in two Swedish sediments (Lake Jarnsjon and Baltic Bay Orserumsviken). Four different PCB fractions were extracted in each sediment by applying consecutively harsher SFE conditions on the same sample. The two sediments had different textures, but they showed very similar extraction behaviour. It was shown that, in both sediments, a major part of the PCBs (58% and 65%, respectively) were located at "fast sites", from which they were extractable already with the mildest extraction conditions (60 min, 40 degrees C and 120 bar). Only a small fraction of the PCBs were so tightly bound to the sediments (located at "slow sites"), that they could be extracted only under the harshest conditions (60 min, 150 degrees C and 400 bar). The authors suggest the results of this study should be useful for the determination of bioavailability of pollutants in sediments and soils.

  Source: Nilsson T, S Bowadt, and E Bjorklund. 2002(January). Development of a simple selective SFE method for the determination of desorption behaviour of PCBs in two Swedish sediments. Chemosphere Volume 46(3): 469-76.

• Time Evolution of Heavy Metals in Marine Sediments - In this study, the time evolution of heavy metal concentrations of Pb, Zn, Cd, and Hg in the sediments of the Bay of Cadiz (southwest of Spain) over the last century was examined. The study was performed using sedimentary profiles extracted from the seabed. The measurement of 210Pb and 137Cs radionuclides provided the dating of the sediment layers, up to the age of 115 years. The relative sedimentation rates obtained are around 0.2 cm/year. The 137Cs activity profile reflects the concentration of this radionuclide in the atmosphere and in aquatic systems during the second half of the twentieth century. This profile was used to ratify the results provided by the 210Pb dating method.

  Source: Ligero R A; M Barrera M; M Casas-Ruiz ; D Sales; and F Lopez-Aguayo. 2002. Dating of marine sediments and time evolution of heavy metal concentrations in the Bay of Cadiz, Spain. Environmental Pollution Volume 118 (1): 97-108.

• Influence of Natural Sources on Mercury in Water, Sediment and Aquatic Biota - The Leviathan mine site, a known source of acid mine drainage, is located in the East Fork of the Upper Carson River (EFUCR) drainage basin. A study began in 1999 to monitor total mercury concentrations in water, sediment, and whole aquatic macroinvertebrates from seven tributaries of the EFUCR watershed on a seasonal time step. In the fall, methylmercury in water, sediment and stoneflies was determined for three sites. Both total and dissolved mercury in water at all sites, not impacted by acid mine drainage, exhibited a seasonal trend with the lowest residues occurring in the winter, higher residues in the summer, and the highest residues recorded in the fall. Winter samples were collected during a period of ice melt. The authors hypothesized that the high fall concentrations were due to elevated mercury concentrations in groundwater, which was recharging the stream under base flow conditions and had interacted with substrate naturally enriched in mercury. Leviathan Creek mercury levels were elevated when acid mine drainage was being discharged directly into the Creek.

  Source: Fischer, P., and G M Sexauer. Influence of natural sources on mercury in water, sediment and aquatic biota in seven tributary streams of the East Fork of the Upper Carson River, California. 2002. Water Air and Soil Pollution Volume 133(1-4): 283-295.

• Significance of Coarse Sediment in Metal Pollution Measurements - This study investigated the role of coarse material (sand) in the distribution of metals in polluted marine sediments from the island of Lesvos in the Aegean Sea. The authors found that sand fraction contains a relatively significant proportion of anthropogenic metals which cannot be neglected in metal pollution studies. Also, the distribution of the anthropogenic metals (Cd, Cu, Pb and Zn) in both silt+clay and sand fractions follows the same pattern indicating similar pollution sources. In the bulk sediment, all anthropogenic metals had a significant amount (>50%) in the acid-extractable (and potentially bio-available) fraction.

  Source: Aloupi M, M O Angelidis. 2002 (January). The significance of coarse sediments in metal pollution studies in the coastal zone. Water Air and Soil Pollution Volume 133 (1-4):121-131.

• Environmental Risks of Aeration of Sediment Exposed to Mine Drainage - The authors examined freshwater sediments with respect to chemical changes upon aeration to assess the risks associated with their acidification and release of toxic metals. The sediments studies were from a pond that receives water from an open-pit lignite quarry. Three types of sediments were sampled: orange precipitates of ferric oxides, underlying black anoxic material and brown clayey material from the original bottom of the pond. The experiment revealed that only black anoxic sediment presents environmental concerns upon aeration. The redox potential of the anoxic sediments rose steeply within the first 50 h of aeration and leveled off after 362 h of aeration. The redox changes were accompanied by sulphate production and lowered pH values. The decrease of pH values was followed by increased zinc and manganese mobility.

  Source: Fajtl J, M Kabrna, R Tichy, R Ledvina. 2002 (January). Environmental risks associated with aeration of a freshwater sediment exposed to mine drainage water. Environmental Geology (Berlin) Volume 41 (5):563-570.

• Use of Ultrasound to Decontaminate Organics in Dredged Sediments - The use of ultrasound coupled with vacuum pressure is described as a potential method to decontaminate organics in dredged sediments. A set of laboratory scale experiments were carried out using simulated dredged sediments from New York/New Jersey harbor. Acoustic cavitation due to ultrasound energy coupled with vacuum pressure was used to facilitate the removal of the contaminant p-terphenyl from the sediments. Two coupled processes were used to separate and to treat both coarse and fine fractions of sediments. Laboratory-scale experiments were carried out with various combinations of parameters (including ultrasound power, solvent to sediment ratio, vacuum pressure, and sonication time) according to the factorial design. The study showed that the proposed treatment technique is effective for treating dredged sediments.

  Source: Meegoda J N, and K Veerawat. 2002 (January). Ultrasound to decontaminate organics in dredged sediments. Soil & Sediment Contamination Volume 11 (1):91-116.

• Radiocarbon Dating and Chronologic Framework of Chesapeake Sediments - Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, the authors of this study obtained sediment cores up to 20 m in length and used radiocarbon ages measured by accelerator mass spectrometry to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Analyses showed that total organic carbon ages are unreliable because much of the carbon has been transported to the bay from upstream sources and is older than surrounding sediments. Mollusk shells (clams, oysters) and foraminifera give more reliable results, but reworking and burrowing are potential problems with this method. The data show large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Mass accumulation rates at two deep-water sites rapidly increased by about fourfold, coincident with widespread land clearance for agriculture in the Chesapeake watershed. >Source: Colman S M, P C Baucom; Bratton J F, T M Cronin, J P McGeehin, D Willard, A R Zimmerman and P R Vogt. 2002 (January). Radiocarbon dating, chronologic framework, and changes in accumulation rates of Holocene estuarine sediments from Chesapeake Bay. Quaternary Research (Orlando) Volume 57(1):58-70.
• Combined Roles of Black Carbon and Natural Organic Matter as Sorbents in Sediments - The authors test the hypothesis that two mechanisms, absorption into natural organic matter and adsorption onto combustion-derived black carbon (BC), act in parallel to bind polycyclic aromatic hydrocarbons (PAHs) to Boston Harbor sediments.

  Source: Accardi-Dey A, and Gschwend P M. 2002 (January). Assessing the combined roles of natural organic matter and black carbon as sorbents in sediments. Environmental Science & Technology Volume 36(1): 21-29.

• Determination of Brominated Flame Retardants in Environmental Samples - This article gives a brief overview of the analytical methods used to detect brominated flame retardants (BFRs) in environmental samples. The levels of BFRs in the environment have increased in the past few decades as the manufacture and use of these compound has increased. Although the acute toxicity of most BFRs seems to be fairly low, they are a potential hazard to the environment as some BFRs some have shown similar toxic effects to PCBs and polychlorinated dibenzo-p-dioxins and furans.

  Source: Hyotylainen T and K Hartonen. 2002 (January). Determination of brominated flame retardants in environmental samples. Trends in Analytical Chemistry Volume 21(1):13-29.

• Geochemical Influences on Metal Partitioning in Contaminated Estuarine Sediments - This paper investigates metal partitioning in the benthic estuarine sediments of Iron Cove, an off-channel embayment of Port Jackson (Sydney, Australia), where stormwater runoff has resulted in heavy metal contamination. The study found that contamination was greatest near the stormwater canal, and sediments in that location were anoxic and contained high concentrations of sulfide. Away from the canal, a layer of surficial sediment containing high dissolved iron was found. The authors used water quality guidelines to determine that the ecological risk posed by dissolved metals from these contaminated sediments is low. The rapid oxidation then hydrolysis of iron(II) in porewaters caused a drop in pH and the formation of iron hydroxide precipitate. These processes may affect dissolved metal concentrations.

  Source: Simpson S L, Rochford L, Birch G F. 2002. Geochemical influences on metal partitioning in contaminated estuarine sediments. Marine and Freshwater Research 53(1) pp. 9-17.

• Phytotoxicity of Dredged Sediment For Land Application - The authors evaluated the phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application using pakchoi (Brassica chinensis) germination tests and pot experiments. Pakchoi germination rates in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls. In pot experiments, plant height and biomass were increased by the dredged sediment application, but decreased when the application rate was increased above a certain level. Concentrations of Zn and Cu in pakchoi increased with the increase of the application rate of the dredged sediment. The authors conclude that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment.

  Source: Chen Y X, Zhu G W, Tian G M, Zhou G D, Luo Y M, Wu S C. 2002. Phytotoxicity of dredged sediment from urban canal as land application. Environmental Pollution 117(2) pp. 233-241.

• Spatial Distribution of Mercury in Riparian Sediments - To assess the current extent of contamination from a historical point source discharge, this study examined concentrations of total mercury in sediments and riparian soils from the River Yare, Norfolk, UK . The results show the spatial distribution pattern in surficial sediments and soils follows that of a distinct pollution plume. Average mercury concentrations in the surficial sediments ranged from 0.1 to 8.13 ppm, while riparian soil concentrations ranged from 0.1 to 2.63 ppm. Over time, the downstream background sediment concentrations mercury have declined, likely as a result of burial by fresh sediments, and also possibly a result of the influence of the freshwater-saline interface in the lower reach. Channel morphology was also shown to have an effect on mercury concentrations between sample points within transects.

  Source: Birkett, J W, Noreng, J M K, Lester, J N. 2002. Spatial distribution of mercury in the sediments and riparian environment of the River Yare, Norfolk, UK. Environ Pollut 2002; 116(1):65-74

Upcoming Conferences and Events

• Conference on Contaminated Soils, Sediments & Water - The 18th Annual International Conference on Contaminated Soils, Sediments & Water will be held October 21-24, 2002 in Amherst, Massachusetts. The theme of this year's conference is "Expediting and Economizing Cleanups," and live equipment demonstrations will augment the exhibition section. Visit the conference website www.umasssoils.com for more information.

• Second International Conference on the Remediation of Contaminated Sediments - The Second International Sediment Remediation Conference will be held in the autumn of 2003 in Venice, Italy. Organizers say the city is an ideal setting for a conference on this topic because of the sediments remediation efforts being exerted there by the local, regional, and national governments. The Call for Abstracts brochure is expected to be available in July 2002, and abstracts to be considered for the program will be due in December 2002. To request a copy of the Call for Abstracts, visit the Sediment Remediation Conference website.

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