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PubMed2005

Comparative and mixture sediment toxicity of trinitrotoluene and its major transformation products to a freshwater midge.

The explosive trinitrotoluene (TNT) is a prevalent contaminant in many military installations worldwide. Limited knowledge of the comparative toxicity of sediment-associated TNT and related compounds contributes to uncertainty when assessing ecological risks in contaminated sites. Trinitrotoluene undergoes transformation when associated with soils and sediments and typically occurs as a mixture dominated by its reduction products. The objective of this study was to comparatively evaluate the single-compound toxicity of TNT and its major transformation products to the freshwater midge Chironomus tentans in 10-day exposures to sediment spiked with TNT, 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT), or trinitrobenzene (TNB). In addition, the nature of the toxicological interactions of the latter compounds in a mixture was evaluated. Upon spiking to sediment, TNT and TNB rapidly degraded to reduced products, and disappearance of extractable compounds suggested irreversible binding to sediment particles. The high degree of transformation and reactivity occurring during 10 days at spiking concentrations as high as 4000 micromol/kg dry weight suggests that TNT and related compounds are unlikely to be encountered in fine-grained sediments at contaminated sites. Similar to previous investigations, the high reactivity of the spiked compound hampered determination of accurate toxic concentrations of TNT and related compounds, and of the nature of toxicological interaction of compounds in a mixture in this study. Sediment concentrations associated with decreased survival were similar for all four compounds, with the 10-d median lethal concentrations (LC50s) determined using initial concentrations ranging from 175 (2-ADNT) to 605 (2,4-DANT) micromol/kg dry weight. Sublethal decrease in growth was not observed for any compound. Results from the mixture experiment suggest additive interaction among TNT and related compounds in sediment exposures.

Animals↗

PubMed2006

Extraction of inhibitor-free metagenomic DNA from polluted sediments, compatible with molecular diversity analysis using adsorption and ion-exchange treatments.

PCR inhibitor-free metagenomic DNA of high quality and high yield was extracted from highly polluted sediments using a simple remediation strategy of adsorption and ion-exchange chromatography. Extraction procedure was optimized with series of steps, which involved gentle mechanical lysis, treatment with powdered activated charcoal (PAC) and ion-exchange chromatography with amberlite resin. Quality of the extracted DNA for molecular diversity analysis was tested by amplifying bacterial 16S rDNA (16S rRNA gene) with eubacterial specific universal primers (8f and 1492r), cloning of the amplified 16S rDNA and ARDRA (amplified rDNA restriction analysis) of the 16S rDNA clones. The presence of discrete differences in ARDRA banding profiles provided evidence for expediency of the DNA extraction protocol in molecular diversity studies. A comparison of the optimized protocol with commercial Ultraclean Soil DNA isolation kit suggested that method described in this report would be more efficient in removing metallic and organic inhibitors, from polluted sediment samples.

Adsorption↗

PubMed2006

Polychlorinated dibenzo-p-dioxins and dibenzofurans in paddy soils and river sediments in Akita, Japan.

Paddy soils and sediments from the Yoneshirogawa, Omonogawa, and Koyoshigawa River Basins in Akita were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The levels and compositions in those samples including soils from non-agricultural areas (non-agricultural soils) were investigated using isomer-specific analysis to determine characteristic sources. The PCDD/PCDF compositions in the samples were compared with respect to possible sources. The PCDD/PCDF concentrations in paddy soils were much higher than those in the non-agricultural soils and much higher than those found in other parts of Japan. Although PCDD/PCDFs were ubiquitous in sediments from river sources to mouths of the respective river basins, those concentrations were much lower than those from paddy soils and non-agricultural soils, and from other parts of Japan. Comparison of PCDD/PCDF homologues and isomer compositions for samples indicated that compositions of paddy soils and sediments, except for those from river sources, had similar characteristics to PCDD/PCDFs originating from impurities in herbicides, 2,4,6-trichlorophenyl 4-nitrophenyl ether (CNP) and pentachlorophenol (PCP), and that compositions of river-source sediments and non-agricultural soils resembled those of atmospheric depositions. Results of statistical analyses suggest that PCDD/PCDF contamination of paddy soils and sediments is attributable mainly to three sources: CNP, PCP, and atmospheric deposition. Results of this study also demonstrate that CNP and PCP are not only important contaminants of local areas of Japan, but that they exist throughout Akita, in northern Japan. We therefore conclude that PCDD/PCDF pollution caused by those compounds has a widespread influence on paddy soils and river sediments in Japan.

Benzofurans↗

PubMed2005

Sediment toxicity assessment in the Lagoon of Venice (Italy) using Paracentrotus lividus (Echinodermata: Echinoidea) fertilization and embryo bioassays.

The capacity of two toxicity bioassays (fertilization and embryo toxicity tests) to discriminate sediment toxicity using the sea urchin Paracentrotus lividus was tested in five stations with different levels of pollution in the Lagoon of Venice. Two stations were located in estuarine sites, two in the industrial zone, and one in a site at the top of our quality gradient (reference). Elutriate was chosen as sediment matrix to assess the potential effects of bioavailable pollutants in the water column as a consequence of sediment resuspension (dredging and dumping, fishing gear, etc.). An experimental design based on Quality Assurance/Quality Control procedures (QA/QC) was adopted in order to set the methodological basis for an effective use of these bioassays in monitoring programs. Results revealed both higher embriotoxicity than spermiotoxicity in all stations and the efficacy of combined use of both toxicity bioassays in discriminating differing pollution/bioavailability between stations and periods. The good representativeness of the integrated sampling scheme and the standardization of all experimental phases yielded high precision of results. Clear Toxicity Fingerprints were evidenced for the investigated sites through the combined use of both bioassays. A good fit between ecotoxicological data and chemical contamination levels was found, except for unnatural sediment texture.

Animals↗

PubMed2006

Fate of Irgarol 1051, diuron and their main metabolites in two UK marine systems after restrictions in antifouling paints.

Two major antifouling biocides used worldwide, Irgarol 1051 and diuron, and their degradation products in Shoreham Harbour and Brighton Marina, UK were studied during 2003-2004. The highest concentrations of Irgarol 1051 were 136 and 102 ng L(-1) in water and 40 and 49 ng g(-1) dry weight in sediments for Shoreham Harbour and Brighton Marina, respectively. As the degradation product of Irgarol 1051, M1 was also widespread, with the highest concentration of 59 ng L(-1) in water and 23 ng g(-1) in sediments in Shoreham Harbour, and 37 ng L(-1) in water and 5.6 ng g(-1) in sediments in Brighton Marina. The target compounds showed enhanced concentrations during the boating season (May-July), when boats were being re-painted (January-February), and where the density of pleasure crafts was high. Overall, the concentration of Irgarol 1051 decreased significantly from late 2000 to early 2004, indicating the effectiveness of controlling its concentrations in the marine environment following restricted use. Diuron was only detected in 14% of water samples, and mostly absent from sediment samples.

Biotransformation↗

PubMed2005

The effect of emergent macrophytes on the dynamics of sulfur species and trace metals in wetland sediments.

This study focuses on the effect of plants on the biogeochemistry of sulfur species and the mobility of heavy metals in wetland sediments. Results showed that, in the presence of plants, sediments had elevated sulfate concentrations in the rhizosphere during the growing season, ranging from 0.2 to 6.20 mmol L(-1), whereas only a small difference in the sulfate profiles between vegetated and non-vegetated sediments was observed during senescence. Based on the sulfate concentration increase, the oxygen release rate from the roots to achieve the corresponding oxidation of sulfide was estimated as 0.85 g m(-2) day(-1). Evapotranspiration-induced advection is a major contributor to the transport of sulfate from the water column into the sediments, and also allows dissolved trace metals (i.e. Cd, Pb, and Zn) to be transported into the sediments and react with the acid volatile sulfide pool, resulting in the immobilization of trace metals in these sediments.

Cadmium↗

PubMed2005

Effects of particle size, organic matter and ionic strength on the phosphate sorption in different trophic lake sediments.

The trophic status and development of lake system is significantly influenced by the phosphate sorption at the sediment-water interface. The effects of organic matter, particle size and ionic strength on the phosphate sorption by sediments were investigated in this study. The results show that maximum phosphate sorption capacity (Qmax), equilibrium phosphate concentration (EPC0), phosphate sorption efficiency (k) and phosphate sorption rate decreased as particle size increased for all the studied sediments. But the reliable desorbed phosphorus (RDP) increased. Qmax, EPC0, k and RDP of different particle size fractions varied and there were no obvious differences among different trophic lake sediments. Qmax, EPC0 increased while k and RDP decreased as the pollution level of lake sediment increased. The phosphate sorption mainly occurred within 0.5 h. Power function and simple Elovich models were the best kinetic models for the phosphate sorption of the different particle size fractions. Qmax and phosphate sorption rate decreased with the decreasing of organic matter content of sediments and the increasing of ionic strength. This study suggests that ionic strength and organic matter had similar effects on the phosphate sorption for different trophic lake sediments.

Absorption↗

PubMed2004

Avoidance of crude-oil contaminated sediment by the Australian seastar, Patiriella exigua (Echinodermata: Asteroidea).

This study attempted to determine whether Patiriella exigua, an Australian seastar, could detect and/or avoid oiled sediment when given an equal choice of unoiled sediment. The sediment was spiked once to produce one of three concentrations of oiled sediment used in the test chambers versus unoiled sediment. Behavioral observations were repeated over a 32 day period to test the effects of aging the oiled sediment. Results show that Patiriella exigua was capable of detecting oiled sediment and/or an oiled environment. Seastars avoided oiled sediment, with significantly higher numbers choosing either to reside on the clean sediment (p<0.05) or to travel up the glass sides of the tanks (p<0.001). Avoidance of oiled sediment increased with increasing sediment oil concentrations. Aging the oiled sediment decreased the oil content of the sediment and increased the number of seastars able to inhabit it (p<0.001). A potential narcotic effect of exposure to oiled sediment was observed.

Animals↗

PubMed2003

Partial mortality in massive reef corals as an indicator of sediment stress on coral reefs.

Partial mortality and fission on colonies of four common massive coral species were examined at sites differing in their exposure to river sediments in St. Lucia, West Indies. Rates of partial mortality were higher close to the river mouths, where more sediments were deposited, than away from the rivers in two coral species. Frequency of fission showed no significant trend. The percent change in coral cover on reefs from 1995 to 1998 was negatively related to the rate of partial mortality estimated in 1998 in all species. This suggests that partial mortality rates could reflect longer-term temporal changes in coral communities. Similar conclusions could also be reached using a less precise measure and simply recording partial mortality on colonies as <50% and >/=50% dead tissue. We conclude that partial mortality in some species of massive reef corals, expressed as the amount of dead tissue per colony, could provide a rapid and effective means of detecting sediment stress on coral reefs.

Anthozoa↗

PubMed2003

Economic and environmental impacts on ports and harbors from the convention to ban harmful marine anti-fouling systems.

The recent Diplomatic Conference held (1-5 October 2001) by the International Maritime Organization (IMO) in London adopted the Draft Convention prepared by The Marine Environmental Protection Committee (MEPC) of IMO for the "Control of Harmful Anti-fouling Systems for Ships." The convention has been developed to immediately ban the use of Tributyltin (TBT) globally in anti-fouling paints to "protect the marine environment". The ban on TBT has come about because TBT has detrimental effects on non-target marine organisms. In November 1999, IMO agreed that a treaty be developed by the MEPC to ensure a ban on the application of TBT based anti-fouling paints by 1 January 2003, and a ban on the use of TBT by 1 January 2008. At the meeting surious concern was expressed by some experts for the need to identify in the treaty the necessary regulatory language for: (1) the "safe" removal, treatment, and disposal of marine anti-foulants deemed "harmful" by the treaty and (2) who is liable for the future dredging and disposal of TBT-contaminated port and harbor sediments--to also "protect the marine environment". The requirement for "safe" removal and disposal was incorporated at MEPC 46 as Article 5 in the treaty, without it shipyards complying with existing national and local discharge regulations (most have none for discharge of TBT) could inadvertently release more TBT to ports and harbors in the five-year compliance period than has been leached from ships (hulls) in the past 40 years to the same waters. Virginia is the only State in the US that regulates the discharge to below 50 ng/l (50 parts per trillion). However, the liability for the future dredging and disposal costs of TBT-contaminated port and harbor sediments has not been addressed.

Commerce↗

PubMed2001

Evaluation of dioxin contamination in sewage sludge discharges on coastal sediments from Catalonia, Spain.

The fate of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in sewage sludges after discharge into the sea was investigated. Sediment samples were analysed at a sewage sludge disposal site as well as in the surrounding areas. Moreover, eight sediment samples from two rivers in Catalonia and three sediment samples from Catalonian Coast were analysed to determine the background levels of contamination. Total international toxicity equivalent (I-TEQ) values for these sediments ranged from 0.42 to 8.01 pg g, with a mean value of 4.15 pg/g and a median value of 3.69 pg/g. However, the I-TEQ values of sludge-treated areas were higher: 57.04 pg/g at the dumping site, and within a range of 13.42-47.76 pg/g near this site. Thus, European sediment quality objectives were exceeded. The higher concentrations coincided with changes in the ratio between PCDD and PCDF levels, suggesting the influence of the sewage sludge on coastal sediments.

Benzofurans↗

PubMed2003

Effects of submerged macrophytes on sediment resuspension and internal phosphorus loading in Lake Hiidenvesi (southern Finland).

The effects of submerged macrophytes on sediment resuspension and internal phosphorus loading in the shallow Kirkkojärvi basin of Lake Hiidenvesi were studied by sedimentation traps and sediment and water samples. During the 83 d study period, 793 g DW m(-2) of sediment was resuspended within the stand formed by Ranunculus circinatus, Ceratophyllum demersum and Potamogeton obtusifolius. Outside the stand, 1701g DW m(-2) sediment resuspension was measured during the same period. Water turbidity and concentration of suspended solids (SS) were significantly lower within the plant bed compared with the surrounding water area. Despite the higher concentration of inorganic suspendoids, the concentration of chlorophyll a was higher in the open water than within the submerged plant bed, owing to the enhanced nutrient recycling rate in the absence of submerged plants. With the resuspended sediment, 11.8 mg Pm(-2)d(-1) was brought into the water column within the stand and 24.5 mg Pm(-2)d(-1) outside the stand. Within the macrophyte stand, resuspended particles absorbed phosphorus from the water (indicated by the inverse relationship between SS and soluble reactive phosphorus), which was probably connected to the lowered phosphorus concentration of surface sediment due to uptake by macrophytes.

Absorption↗

PubMed2003

Sediment characteristics, phosphorus types and phosphorus release rates between river and lake sediments.

The Han river is 469.7 km long with 26219-km2 area watershed, and is the primary drinking water source for the 20 million people that live in Seoul, Kangwon-Do and Kyunggi-Do, Korea. Phosphorus release from sediments impacts water quality, and is endangering the beneficial use of the river. This research measures phosphorus release and predicts future releases from bottom sediments of two tributary areas (Chungpyung Lake (CPL) and Jamsil submerged dam (JSD) area in the Han river). Sediment samples were taken over a 4-year period from four points in the Jamsil dam area and from 92 points in CPL. The sediments were analyzed for total phosphorus, the form of the phosphorus and release rates under different conditions to the water column. Sediment phosphorus distribution from CPL was 3-5% adsorbed-P (Ads-P), 15-20% non-apatite-P (NAI-P), 25-30% apatite-P (A-P) and 45-57% residual-P (R-P). In the JSD area, the phosphorus distribution ranges were 1-3% Ads-P, 22-39% NAI-P, 26-40% A-P and 30-39% R-P. Laboratory experiments showed that phosphorus release rates from 60 to 80 mg/m2 week in JSD area and ranged from 25 to 40 mg/m2 week in CPL sediments.

Aerobiosis↗

PubMed1998

Heavy metal contamination in surface sediments in the Gulf of Finland and comparison with the Gulf of Bothnia.

Concentrations of heavy metals in sediments of the Gulf of Finland and the Gulf of Bothnia were studied during 1991-1993. Most of the concentrations reported are for the surface sediments, with background concentrations from deeper downcore included for comparison. The metals studied were mercury, lead, cadmium, zinc, copper, iron, lithium, vanadium, titanium, arsenic, chromium, nickel, manganese and aluminium. The new values for the Gulf of Finland are compared with concentrations for the Gulf of Bothnia. Explanations for the differences in values are suggested and distribution patterns are described. Concentrations of all elements are clearly higher in the easternmost part of the Gulf of Finland and throughout the Gulf the values of total organic carbon, aluminium, chromium, manganese and cadmium are higher in the surface sediments than in the Gulf of Bothnia.

Baltic States↗

PubMed2001

Modelling sedimentation processes in a constructed stormwater wetland.

The design and operation of constructed wetlands for the treatment of stormwater relies heavily on promoting sedimentation, and being able to predict accurately the expected effectiveness of the pond in removing material from the inflows. A study of sediment behaviour has been carried out in a stormwater wetland in Adelaide, Australia where computer predictions, based on solving the hydrodynamic equations and the transport equation, have been compared to deposition patterns observed in the field. The long-term residence time distribution has been shown to be useful in predicting overall sediment removal rates. Comparisons between the model and field observations indicate generally good agreement. Sources of potential error identified include the variable nature of the runoff concentrations entering the pond and the sediment size distribution. The importance of the transient nature of the flow events was highlighted by the spread of sediment throughout the whole pond.

Conservation of Natural Resources↗

PubMed2001

Sediment nutrient characteristics and aquatic macrophytes in lowland English rivers.

Aquatic macrophytes play an important role in the nutrient dynamics of streams. As a result, there is much interest in their use as trophic indicators. However, the relationship between aquatic macrophytes and the trophic status of rivers is a complex one, partly because of the effects of a wide range of environmental variables and partly because submerged, rooted macrophytes can absorb nutrients from the river sediments and/or the water column. Experiments which have tried to establish the relative importance of sediments or water as sources of nutrients are inconclusive and further work is needed to establish how sediment nutrient characteristics vary within and among rivers (spatially and temporally) and the inter-relationships between sediment nutrients, water column chemistry and macrophytes. This paper presents the initial findings from a study of 17 lowland rivers in southern England which is exploring the spatial variability of sediment characteristics (total and inorganic phosphorus, total nitrogen, organic carbon, silt-clay fraction and organic matter content) and the relationship with aquatic macrophytes. The preliminary analysis indicates that although sediment characteristics are highly variable within 100-m river reaches, the variability across the 17 rivers is even greater; this is despite the limited geographic and trophic range of the study sites. The results presented in this paper also give some indication of the sediment characteristics associated with five macrophyte species but it is too early to ascribe sediment preferences for particular species.

Environmental Monitoring↗

PubMed2001

The impact of a hydroelectric power plant on the sediment load in downstream water bodies, Svartisen, northern Norway.

When the Svartisen hydroelectric power plant was put into operation, extensive sediment pollution was observed in the downstream fjord area. This paper discusses the impact of the power plant and the contribution from various sources of sediment. Computation of the sediment load was based on samples collected one to four times per day. Grain size distribution analyses of suspended sediments were carried out and used as input in a routing model to study the movement of sediments through the system. Suspended sediment delivered to the fjord before the power station was constructed was measured as 8360 metric tons as an annual mean for a 12-year period. During the years 1995-1996 when the power plant was operating, the total suspended load through the power station was measured as 32609 and 30254 metric tons, respectively. Grain size distribution analyses indicate a major change in the composition of the sediments from 9% clay before the power plant was operative to 50-60% clay afterwards. This change, together with the increase in sediment load, is believed to be one of the main causes of the drastic reduction in secchi depths in the fjord. The effect of the suspended sediment load on the fjord water turbidity was evaluated by co-plotting secchi depth and power station water discharge. Measurements during 1995 and 1996 showed that at the innermost of these locations the water failed to attain the minimum requirement of 2 m secchi depth. In later years secchi depths were above the specified level. In 1997 and 1998 the conditions improved. At the more distal locality, the conditions were acceptable with only a few exceptions. A routing model was applied to data acquired at a location 2 km from the power station in order to calculate the contributions from various sediment sources. This model indicated that the contribution from reservoir bed erosion dominated in 1994 but decreased significantly in 1995. Future operation of the power station will mostly take place with a high water level in the reservoir and is likely to result in acceptable water quality in the fjord. However, during periods of low drawdown, sediment pollution may again become a problem.

Environmental Monitoring↗

PubMed1998

Management implications of metal transfer pathways from a refuse tip to mangrove sediments.

Mangroves have often been thought of as wasteland, and because of this attitude, many mangrove forests have been used as sites for refuse tips, sewage outfalls and as illegal dumping grounds. The transfer of metals from a refuse tip to mangrove sediments is investigated and four pathways of heavy metal migration are identified. These are direct seepage across the tip-cell floor to groundwater, tidal over-topping of the bund wall and capillary suction of leachates to groundwaters, direct seepage through the cell wall of leachates to surficial sediments, and surface runoff during rainfall events. Metal input by surficial runoff indicates that significant quantities of metals have been transferred to the mangroves via this mechanism. However, metal transfer via surface runoff is probably small in comparison to the other three mechanisms discussed. The variable nature of the transfer mechanisms operating, the variability in sediment texture both vertically and laterally, and the number of transfer pathways makes potential management of the site difficult. Any management plan for this site must consider both the feedback mechanisms that operate, and that the whole sediment column is involved in metal transfer.

Australia↗