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Incorporating materials into sediment caps that can sequester contaminants will greatly improve their ability to isolate contaminants in the underlying sediments from the rest of the aquatic environment. For highly sorptive media ...
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Incorporating materials into sediment caps that can sequester contaminants will greatly improve their ability to isolate contaminants in the underlying sediments from the rest of the aquatic environment. For highly sorptive media a thin layer (cm) maybe sufficient, but accurately placing a thin layer (cm) of material over submerged contaminated sediment is difficult. A reactive core mat (RCM) was designed to accurately place a 1.25 cm thick sorbent (coke) layer in an engineered sediment cap. In April 2004, twelve 3.1 m x 31 m sections of RCM were placed in the Anacostia River, Washington, D.C., and overlain with a 15 cm layer of sand to secure it and provide a habitat for benthic organisms to colonize without compromising the integrity of the cap.Placement of the RCM did not cause significant sediment re-suspension or impact site hydrology. The RCM is an inexpensive and effective method to accurately deliver thin layers of difficult to place, high value, sorptive media into sediment caps. The approach can also be used to place granular reactive media that can degrade or mineralize contaminants.
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Throughout the European Union (EU), agricultural soils with high phosphorus (P) status due to surplus fertiliser input have been identifi ed as a landscape pressure impacting on water quality. In Republic of Ireland, approximately...
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Throughout the European Union (EU), agricultural soils with high phosphorus (P) status due to surplus fertiliser input have been identifi ed as a landscape pressure impacting on water quality. In Republic of Ireland, approximately 80% of agricultural land is devoted to grass, 11% to rough grazing, and 9% to arable cereal and crop production. Consequently, the majority of erosion research has focused on quantifying nutrient and sediment losses from grassland. Tillage soils are, however, more susceptible to erosion than grassland soils and, in general, have higher levels of soil P. This paper reviews the current state of research and the regulatory regime relating to diffuse P and sediment loss for tillage soils. It identifi es the key threats to soil quality associated with cultivated soils, and proposes the targeting and remediation of critical source areas for effective mitigation of P losses from tillage soils. A multiscaled approach is recommended, in which catchment and fi eld-scale monitoring is complemented with controlled laboratory and small plot-scale rainfall simulation experiments to identify areas where P loss and soil erosion are at critical levels and may pose a threat to water quality. Catchment scale research will help to link critical source areas of sediment and P loss with hydrological pathways to surface waters in the catchment area. These areas can then be targeted for remediation in the river basin management plans.
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Since the beginning of North America's industrialization, the Great Lakes have been negatively impacted by the discharge of industrial, agricultural and munic- ipal pollutants. The governments of Canada and the United States have...
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Since the beginning of North America's industrialization, the Great Lakes have been negatively impacted by the discharge of industrial, agricultural and munic- ipal pollutants. The governments of Canada and the United States have recog- nized that the accumulation of pollutants within the bottom sediment and the water column has had a detrimental effect on the Great Lakes ecosystem.
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Batch washing experiments were used to evaluate the feasibility of using biosurfactants for the removal of heavy metals from sediments. Surfacing from Bacillus subtilis, rhamnolipids from pseudomonas aeruginosa an sophorolipid fro...
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Batch washing experiments were used to evaluate the feasibility of using biosurfactants for the removal of heavy metals from sediments. Surfacing from Bacillus subtilis, rhamnolipids from pseudomonas aeruginosa an sophorolipid from Torulopsis bombicola were evaluated using a metal-contaminated sediment (110 mg/kg copper and 3300 mg/kg zinc). A single washing with 0. 5/100 rhamnolipid removed 65/100 of the copper and 18/100 of the zinc, whereas 4/100 sophorolipid 1. removed 25/100 of the copper an 60/100 of the zinc.
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A former mining site has been the subject of extensive remediation and restoration, with a significant focus on disconnecting mine spoils from groundwater and managing the quantity and quality of runoff. A remaining task is ensuri...
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A former mining site has been the subject of extensive remediation and restoration, with a significant focus on disconnecting mine spoils from groundwater and managing the quantity and quality of runoff. A remaining task is ensuring concentrations of zinc (Zn) in the stream outflow of a pit lake are reduced below water quality standards. The efficacy of multiple capping materials for decreasing Zn dissolution from sediments was conducted under natural and reasonable worst-case conditions (pH = 5.5). Capping materials included AquaBlok (TM), limestone, and limestone-bone char. Field exposures were conducted in limnocorrals that isolated overlying water columns above the sediment and capping treatments. Simultaneous in situ and ex situ toxicity tests were conducted using Daphnia magna, Hyalella azteca, and Chironomus dilutus. In situ caged organisms were protected from temperature shock (warm epilimnetic waters) by deploying within a Toxicity Assessment Container System (TACS). Organisms were exposed to surficial sediments, caps, and hypolimnetic overlying waters for 4 d. Ex situ testing was conducted in core tube mesocosms containing sediments and caps at similar temperatures (15-19 degrees C). Results demonstrated the usefulness of TACS deployment in stratified lake systems. There were no differences in responses between treatments involving sediment capping materials in both in situ and ex situ tests. The lack of differences was likely due to dissolved Zn in surface water being below the hardness-adjusted threshold effects levels (164 mu g L-1). This field- and laboratory-based weight-of-evidence study provided site-specific data to support the selection of an effective remedy, with reduced uncertainty compared to laboratory and chemistry-only approaches. Environ Toxicol Chem 2019;00:1-10. (c) 2019 SETAC
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The growth in world energy demand for oil has provided an increase in its exploration, production, and transportation in onshore or offshore operations. However, during these activities, oil spills can occur due to leaks, corrosio...
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The growth in world energy demand for oil has provided an increase in its exploration, production, and transportation in onshore or offshore operations. However, during these activities, oil spills can occur due to leaks, corrosion of pipes, blow-outs, among others. Oil spills contaminate the environment, affecting soil, surface water, and even beaches sands. The remediation of contaminated sediments, such as sand and soils, is an arduous task since the oil adsorbs on the surfaces of the grains and is difficult to remove. Currently, the remediation of contaminated sediments can be carried out by physical, chemical, biological methods, or a combination of them. Among the methods applied for treatment, the use of microemulsified systems has stood out in the scientific scope due to the good results of removal efficiency, reduction of the amount of surfactant, and the possibility of using biodegradable surfactants. Therefore, this paper provides a comprehensive review of the application of microemulsified systems for the remediation of sediments contaminated by hydrocarbons. Also, we discussed the limitations of the existing methodologies and the action of the microemulsion in the sediment.
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The physicochemical properties of sediments and their ability to retain pollutants are affected by both contamination and remediation processes. The aim of this study is to determine structural and physicochemical changes in real ...
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The physicochemical properties of sediments and their ability to retain pollutants are affected by both contamination and remediation processes. The aim of this study is to determine structural and physicochemical changes in real sediment contaminated with metals, subjected to bioleaching processes in a previous study. The sediment contaminated with heavy metals and samples of the same sediment treated with different heap leaching tests were used. They were characterised by potentiometric titrations, electrophoretic mobility, organic matter (OM), nuclear magnetic resonance (NMR), volatile solids and sulphides. For contaminated and treated sediment samples, the results of OM, sulphides, volatile solids to 600��, potentiometric titrations and zeta potential values depended on the bioleaching treatment performed previously. The contaminated sediment sample without any bioleaching treatment presented the greatest amount of OM and sulphides. Moreover, metal adsorption isotherms were performed. The contaminated sediment without bioleaching treatment was the one with the highest adsorption capacity. The baseline sample did not present a noticeable adsorption capacity. This study indicates the importance of the contribution of OM and sulphides to sediments and structural and physicochemical studies after remediation treatments.
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The consequences of elevated Se accumulation at the Kesterson Reservoir National Wildlife Refuge in the Central Valley of California created adverse effects on wildlife and led to extensive research on the behavior of Se in both t...
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The consequences of elevated Se accumulation at the Kesterson Reservoir National Wildlife Refuge in the Central Valley of California created adverse effects on wildlife and led to extensive research on the behavior of Se in both the wetland and upland ecosystems. Selenium concentrations in water entering the Kesterson Reservoir averaged 300 μg L~(-1). In pond waters 20-30% of the Se was selenate, while only 2% was selenite in the drainage water entering the reservoir. Submerged rooted aquatic plants fed on by water birds were found to contain 18-390mg Se kg~(-1) dry weight. Mosquitofish collected from the San Luis Drain contained 332mg Se kg~(-1), and those collected from the ponds ranged from 339 to 380 mg kg~(-1). Livers of water birds had Se concentrations ranging from 19.9 to 127 mg kg~(-1). The high concentrations of Se accumulation in the food chain of the wetland strongly suggest that Se bioaccumulation was the cause of death and deformity of embryos of the waterfowl nesting at the wetland habitat. In June 1986, the Kesterson Reservoir was closed to drain-water inputs, and the wetland was transformed to an upland grassland. New remedial plans were proposed. These new plans involved soil, water, and vegetation management to dissipate Se by bioaccumulation and volatilization through soil microorganisms and plants. The investigations of the potential transfer of Se from farm land into the crop and vegetables in the Central Valley indicated that plant tissue Se concentrations generally fall in a nonseleniferous category, except that the highest Se concentration of cotton was at a threshold where toxicity in animals could occur at a relatively low frequency. At the Kesterson upland grassland habitat, average total Se concentrations ranged from 500 to 8000 μg kg~(-1) and water-extractable Se ranged from 10 to 700 μg kg~(-1) in the top 15 cm of soil and varied greatly, by a factor greater than 100, among soil samples. Uptake of Se by the plants was profoundly affected by the soil available Se concentration, soil moisture, pH, soil salinity, soil sulfate concentration, soil reoxidation condition, kind of plant species, and soil-management practices. The rate of soil Se dissipation at the Kesterson grassland system was from 1% (low methylation rate) to 5% (high methylation rate) Se inventory per year and it will take from 46 to 230 years to bring the soil Se down to a normal level, 4 mg Se kg~(-1) soil. However, the Kesterson upland grassland habitat had Se bioaccumulation values less than 10% of those of the previous wetland. The potential food-chain contamination at the existing Kesterson grassland is much less problematic. No negative impact on wildlife has been reported for the upland habitat. Plants may contribute to the Se reoxidation process and be able to reduce the movement of Se in the soil. At the Kesterson grassland, the distribution of soil Se is extremely uneven; high levels of soil Se concentrated only in isolated spots. Therefore, leaching of soil Se is not at an area level. It is unlikely that problems of transport of Se from the Kesterson soil to the adjacent uncontaminated environment by leaching can occur.
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The present intensive aquaculture results in an excessive accumulation of nutrient and organic residues in sediment. Then, pollutants accumulated in sediment would strongly affect water quality and increase the occurrence of patho...
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The present intensive aquaculture results in an excessive accumulation of nutrient and organic residues in sediment. Then, pollutants accumulated in sediment would strongly affect water quality and increase the occurrence of pathogenic microorganisms. Thus, remediation of sediment is needed for removing excess nutrient and preventing aquatic animal diseases. In the present research, sediment in cement tanks was remediated with a combined method: crushed oyster shells (OS) and bottom microporous aeration (MA) treatment. The experiment included the control group (CK), treatment 1 (bottom MA), treatment 2 (crushed OS), and treatment 3 (bottom MA and crushed OS, MA+OS). The experimental results showed that from the second week after the experiment began, the organic matter (OM) content in the sediment from MA+OS was lower than that of the CK. From the eighth week, the total nitrogen (TN) and ammonia nitrogen (NH4-N) levels in the sediment from MA+OS were lower than those of CK, and the remediation experiments on sediment had little effect on the water quality in the experimental groups. Functional bacteria in the water column, including the families Erythrobacteraceae and Microbacteriaceae and the genera Phenylobacterium and Beggiatoa, were elevated in MA+OS. Thus, crushed OS and bottom aeration could promote nitrification in water, reducing the levels of OM, (NH4-N), and TN in sediment, through affecting the microbiota in the water column and promoting nutrient circulation, and could improve the overall benthic environment. The method has been demonstrated to be easy and effective for nitrogen removal from sediment.
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The Pine River downstream of the Velsicol Superfund site has been contaminated with various hydrophobic organic pollutants for more than 50 years. Remediation and sediment dredging near the site began in spring of 1999, and was co...
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The Pine River downstream of the Velsicol Superfund site has been contaminated with various hydrophobic organic pollutants for more than 50 years. Remediation and sediment dredging near the site began in spring of 1999, and was completed in 2006. In 2011, the Michigan Department of Environmental Quality completed a baseline assessment report long-term monitoring plan for the Pine River. However, there has been limited assessment of the benthic community since this evaluation. The objective of this research was to evaluate the risk of Pine River sediment to aquatic macroinvertebrates downstream from the Superfund site after decades of degradation and dredging using the Triad approach. Three sites were selected downstream from the Superfund site, and an upstream reference site was used. At each site, macroinvertebrates surveys were conducted and sediments were collected for chemical analysis of DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane) and its degradation products and for laboratory toxicity testing for mortality and sublethal effects using Hyalella azteca and Chironomus dilutus. Sediment concentrations of DDT, DDD, and DDE were below levels expected to cause toxicity, and there was no observed toxicity in laboratory tests. Additionally, there were no statistically significant differences in richness, richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) species, total EPT abundance, percent EPT, or percent dominant taxa between the reference site and the downstream sites. There was an observed decrease in abundance of macroinvertebrate taxa at all downstream sites and a shift in macroinvertebrate structure when comparing the reference with most impaired sites. Although the sites downstream of the Superfund site remain different than the upstream control, there are improvements in species composition and abundance. However, more research is needed to evaluate the potential effects on ecosystem function.
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