Mercury is recognized as a global pollutant. A large amount of elemental mercury was used in the Manhattan Project in Oak Ridge, TN and Hg is still present in the water-shed surrounding the Y-12 facility and East Fork Poplar Creek. Soil erosion during rainfall-runoff events result in nonpoint source Hg transport from floodplain soils to aquatic ecosystems. This study investigated transport mechanisms of Hg through surface runoff processes from floodplain soils in Oak Ridge, TN into water with a simulated rainfall laboratory pilot scale experiment. The experiments simulated rainfall intensity (50–140 mm/h), the ground grass coverage (5 %-85 %), the soil moisture conditions and the slopes (7.5–16.32 degrees) producing soil runoff erosion processes. Results show that high grass coverage, decreased landscape slope and low rainfall resulted in the decreased Hg concentrations in sediments transported through runoff from the floodplain soil. Hg loss was strongly correlated with and controlled by soil loss. The order of environmental factors on Hg loss was the slope > rainfall intensity > grass cover. As grass cover increased from 5 % to 85 %, Hg in sediment decreased from 124 to 72.3 µg/kg and Hg in penetrating water decreased from 4.7 to 2.8 µg/kg on wet soil condition at the slope 12.560. Hg loss and soil loss significantly increased with the increase of the soil slope. As the slope increased from 7.550 to 12.560, Hg loss increased from 364 to 2905 mg/m2 in the dry soil condition with 5 % grass cover. Meanwhile Hg loss and soil loss significantly decreased with the increase of grass cover. The Hg concentration in sediment increased with increasing initial soil moisture from Dry Soil, to Wet Soil and Very Wet Soil. The roots of grasses stabilized soil Hg and the Hg content in soil rhizosphere were significantly higher than that in non-rhizosphere. This study indicates that rainfall intensity, ground grass coverages, landscape slopes and initial soil moisture content strongly controlled Hg transport from the floodplain ecosystem and its flux into stream water. Mercury associated with sediment was the major Hg input into stream waters from floodplain soils in Oak Ridge, TN. Proper onsite management, such as increasing ground coverages with local low lying grasses and decreasing landscape slopes may significantly reduce potential Hg transport into local stream water in Oak Ridge TN.

Cyanuric acid is a widely used fine chemical intermediate that acts as a free chlorine buffer in swimming pool water, wherein it is often used as a stabilizer to maintain the germicidal efficacy of chlorinated disinfectants. However, it has also been associated with health risks. Herein, we introduced the sources and functions of cyanuric acid in swimming pool water, focusing on potential health risks associated with excessive concentration of the component and the current control standards worldwide. Also, the prevention and control measures were summarized in terms of physical chemistry, biodegradation, and ultraviolet radiation to provide a basis for the development of public health policies for swimming pool management.

Heavy metal contamination of soils became a major global problem in recent years due to increase in geological and anthropogenic activities. Phytoremediation is a relatively low-cost and environmentally friendly method of cleaning up of environmental pollutants by using green plants. However, the plants must be carefully screened and selected to optimize the process of phytroremediation for selected heavy metals. Excess metal exposure negatively affects photosynthetic processes and typically induces plant stress. Ultrastructural changes in the chloroplast of leaves, xylem, and phloem vessels of shoot and root will typically increase with metal exposure, which has obvious consequences on photosynthesis and plant growth. Spectral reflectance and remote sensing of large metal contaminated areas can be efficiently used to monitor the progress of phytoremediation. Specific applications of spectral reflectance and remote sensing include early recognition of contaminated areas through plant stress monitoring, assessment of phytoremediation and restoration efforts, spatial, and temporal variation of metal contamination, and assessment of risk to human and environmental health. This chapter summarizes the studies to investigate the feasibility of using spectral reflectance to monitor As and Cr accumulation in Chinese Brake Fern ( Pteris Vittata ) and Indian mustard ( Brassica juncea ) plants, and to search for spectral indices sensitive to structural changes caused by metal accumulation during the process of phytoremediation. These studies reflect that the infrared reflectance spectrum of plant canopy and the derived spectral indices may provide a nonintrusive monitoring method to assess the physiological status of plants grown in heavy metal-contaminated soil. These results also systematically illustrate the physiological implications of ultrastructural alterations caused by As and Cr at higher concentrations in mustard and brake fern plants.

Uranium is a naturally occurring trace element and radionuclide. Uranium is introduced to the environment anthropogenically as a result of industrial, military, and nuclear energy activities. The approach of coupled electrokinetic phytoremediation has been used to remove other heavy metals from contaminated soil. The objectives of this study are to investigate the distribution and solubility of uranium in soils with UO2, UO3, and uranyl and to examine the processes of coupled electrokinetic phytoremediation in removing U from soils with perennial ryegrass at a laboratory pilot scale. A low-intensity direct electric current field (typically 2 V.cm(-1)) was applied to the contaminated soil for 7 d at 8 h.d(-1) after ryegrass was grown for 2 weeks, and then, polarity reversal was employed for another 7 d at 8 h.d(-1). The uranium redistribution took place among various solid-phase components due to changes in the pH and the chemistry of the electrolyte solution. The electrokinetic field (EKF) increased the U bioavailability in soils as water-soluble U and exchangeable U in contaminated soils with all U species. Thus, the EKF significantly increased the U uptake and bioaccumulation by ryegrass. The current laboratory pilot-scale test confirmed our previous observation from the pot greenhouse study-that the coupled electrokinetic phytoremediation may have potential for application in remediating U-contaminated sites.

Lead and mercury are two of the most toxic heavy metals in environments. Mesosilicate-templated magnetic nanocarbons with ascorbic acid as carbon precursor were developed through nanocasting processes. The nanocarbon showed effective magnetic separation and the maximum adsorption capacity of 80.6 and 66.3 mg/g for Hg and Pb, respectively. Langmuir model well described adsorption processes of both Hg and Pb from water. Magnetic nanocarbon could be easily separated and incinerated, reducing the volume requiring the disposal. This study indicates that mesosilicate-templated nanocarbons with easy disposal potentials may be good candidates for cleansing Hg and Pb from contaminated water.

Heavy metal contamination of soils became a major global problem in recent years due to an increase in geological and anthropogenic activities. Metal processing, mining activities, uncontrolled dumping of waste in landfills, and industrial waste releases are some of the prominent sources of metal contamination around the world. Phytoremediation, where plants are used to clean up metal-contaminated soils, is a widely accepted method for in situ soil remediation. Plants growing on metal-contaminated soils often show an alteration in their physiological, chemical, and anatomical characteristics due to enhanced metal uptake and accumulation. Consequences of increased metal concentrations on the internal structure of plant leaf, stem, and root is an important determinant of the physiological adoptability and the phytoremediation potential of the plant. The variation in the plant leaf size, changes in the orientation and intercellular spaces of mesophyll cells, orientation, and shape of the vascular bundles in leaf, root, and stem will all impact the metal uptake characteristics of the plant. This chapter pays attention to some of the newly developed plant imaging methods that can be employed for continuous monitoring of the metal accumulation in different plants and quantification of the resulting internal structural and physiological changes during the process of phytoremediation. Due to the fact that large areas are often contaminated with multiple metal pollutants, special attention is being paid to the metal-specific effects on the internal structure of broad leaf and grass leaf plants during the process of metal accumulation. This chapter summarizes the studies that investigate the feasibility of using spectral reflectance to monitor Zn and Cd accumulation in Indian mustard (Brassica juncea) and barley (Hordeum vulgare) plants, and to search for spectral indices sensitive to structural changes caused by metal accumulation during the process of phytoremediation. Zn accumulation at high concentrations results in a decrease in biomass, a decrease in relative water content (RWC), and changes in the internal structure of the leaves in both plants. The structural and spectral results show significant changes in Zn-treated plants, while the changes are minimal in Cd-treated plants when compared with the untreated plants. These studies reflects that the infrared reflectance spectrum of the plant canopy and the derived spectral indices may provide a nonintrusive monitoring method to assess the physiological status of plants grown in heavy metal–contaminated soil. These results also systematically illustrate the physiological implications of structural alterations caused by Zn and Cd at higher concentrations in mustard and barley plants.

Kenaf (Hibiscus cannabinus L.) is a warm-season, annual, fiber crop. Two distinct fibers from kenaf stalks (long, jute-like bast fibers from the bark and short and balsawood-like fiber from the stem core) have been extensively used in various applications for remediation. Bast fibers are used to manufacture products such as burlap, carpet padding, and pulp, while the short-fibered core is processed into animal house bedding, packing materials, and oil-adsorbent mats. With the increase in demand for energy consumption, the US coal-fueled electric power industry annually produces 72 million tons of fly ash and 55 million tons of other coal combustion products (CCP) with a total production of 131 million tons in 2007. These by-products include mainly fly ash, bottom ash, boiler slag, flue gas desulphurization (FGD) gypsum, and FGD material dry/wet scrubbers. Moreover, the total CCP production increased linearly from 1966 through the early 21 st century. In 1966, the total CCP production generated by the US coal-fueled electric power industry was about 25 million tons; it reached about 130 million in 2007. At the same time, a vast amount of processing water from power plants has been discharged into ponds or rivers. This waste water requires a cost-effective remediation technology. The current study was to explore the potential of kenaf materials to remove heavy metals from waste water. Both batch and column experiments were designed to remove heavy metals such as Cr(VI), Pb, U, Cd, Ni, Hg, Sr, Ni, and metalloids As and Se. The column study results indicate that kenaf fibers can effectively remove the majority of Cr (VI) (84%), Pb (96%), U (93%) and almost all Hg (98%) from contaminated water. Current and previous studies suggest that that kenaf biofiltration could be incorporated into the early stages of wastewater processing to remove heavy metals from wastewater ponds and/or other water bodies. Adsorption mechanisms and methodology(s) to enhance filtration efficiency warrant further systematic studies. We are working toward development of a field-deployable biofiltration system that meets the remediation requirements for CCP-related and other relevant wastewater. In addition to cost saving for power plants, benefits will include creating new revenues for farmers and businesses that grow and process kenaf.

Structural and ultrastructural changes caused by bioaccumulation of As and Cr in brake fern (Pteris vittata), a known arsenic hyperaccumulator, were investigated. Potted plants of brake fern were exposed to metal treatments of As and Cr for three weeks. Leaf, stem and root samples were collected periodically and fixed for LM (Light Microscopy), SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) to evaluate anatomical changes. The fresh weights, dry weights, RWC (Relative Water Content) and plant heights were obtained before the brake fern plants were harvested for metal accumulation analysis. The As accumulated mainly in the shoots while Cr accumulated mainly in the roots of the metal-treated plants. Significant changes in the ferns physical characters, including fresh weight, dry weight, RWC, and plant height were observed for only Cr-treated plants but not for As-treated plants. Microscopic studies reveal the Cr accumulation resulted in dehydration and collapse of internal structure of leaves and cellular breakdown of roots. The As-treated plants showed no significant structural changes in leaves, stems and roots compared to control plants. Clotted depositions were observed in roots and stems of plant groups treated with highest concentration of Cr and As when compared to control (T0) group. Our study indicates that Cr has a profound impact on physiology and structure of fern plants. The accumulation of Cr resulted in decrease in growth rate, total biomass and RWC. We believe that brake fern plants can uptake, translocate and sequester As because it caused no significant structural changes in leaves, stems and roots of the plants.

The U.S. Biomass Roadmap set forth a goal that, by the year 2030, biomass will supply energy approximately equivalent to 30% of current petroleum consumption. Here we report on the amount of nutrient fertilizers required to meet the proposed 1-billion tons of sustainable bioenergy biomass production annually. To meet this goal, U.S. agriculture (assuming a scenario with high yield increase and land use change) will have net removals of 40.3, 12.7, and 36.2 Tg (million tons) of N, P2O5, and K2O, respectively. The 1-billion tons of bioenergy biomass production alone will remove 16.9, 5.2, and 18.2 Tg of N, P2O5, and K2O, respectively, from U.S. agricultural land. Considering the efficiencies of fertilizers in soils and the contribution of biomass residuals in fields, the overall bioenergy-focused agriculture would require 58.2, 27.3, and 31.7 Tg of N, P2O5 and K2O fertilizers, respectively; this corresponds to an overall nutrient fertilizer application increase by a factor of 5.5 over the base line (1997). This study indicates an increased need for domestic and/or international production facilities for fertilizers if the goal of the Biomass Roadmap is to be attained. (C) 2010 Elsevier Ltd. All rights reserved.

Historically as part of its national security mission, the U.S. Department of Energy's Y-12 National Security Facility in Oak Ridge, TN acquired a significant fraction of the world's supply of elemental mercury. During the 1950s and 1960s, a large amount of elemental mercury escaped confinement and is still present in the watershed surrounding the Y-12 facility. Earthworms are key components in natural food chains, providing a food source for many small mammals and important food sources for small birds. The objectives of this study were to investigate the current status of mercury distribution and speciation and determination of mercury bioavailability to native earthworms in floodplain soils of East Fork Poplar Creek (EFPC) after decades of U.S. Department of Energy's remediation. The present study clearly shows that the total mercury in a tested floodplain field of EFPC was significantly below the US Department of Energy target 400mg Hg/kg. The major mercury form in the current floodplain soils of EFPC is mainly the non-cinnabar mercury bound form in soil silicates (4M HNO3-extractable residual fraction). The results show strong linear relationships between mercury concentrations in native earthworms (both mature and immature groups) and the non-cinnabar mercury form. Native earthworms may be used as a potential mercury ecological bio-indicator (bio-marker) for demonstrating mercury bioavailability and ecotoxicity in the ecosystem.

The objectives of this study were to investigate the current status of mercury distribution, speciation and bioavailability in the floodplain soils of Lower East Fork Poplar Creek (LEFPC) after decades of US Department of Energy's remediation. Historically as part of its national security mission, the U.S. Department of Energy's Y-12 National Security Facility in Oak Ridge, TN, USA acquired a significant fraction of the world's supply of elemental mercury. During the 1950s and 1960s, a large amount of elemental mercury escaped confinement and is still present in the watershed surrounding the Y-12 facility. A series of remediation efforts have been deployed in the watersheds around the Oak Ridge site during the following years. The sampling fields were located in a floodplain of LEFPC of Oak Ridge, TN, USA. A series of surface soils (1020 cm) were sampled from both wooded areas and wetland/grass land. Two 8x8 m fields were selected in the woodland. Five profiles each consisting of three layers were randomly taken from each field. The three layers were the surface layer at 0-10cm, subsurface layer at 50-60 cm, and bottom layer at 100-110 cm. Soil in both wood and wetland areas was well developed with a clear B horizon. The present study clearly shows that the total mercury in floodplain soils of LEFPC significantly decreased after the series of remediation. This study confirmed the long-term effectiveness of these remediation actions, especially after excavation of highly contaminated floodplain soils. However, the average total mercury level of all soil samples collected are in the range of 50-80 mg/kg, still significantly above toxic level (> 5mg/kg). Furthermore, contrary to conventional believing, the major mercury form in current soils of this particular area of floodplain of LEFPC is mainly in non-cinnabar mercury bound in clay minerals (after decades of remediation). The floodplains can act both as a medium-term sink and as long-term sources. Native North American earthworms (Diplocardia spp.) and adjacent soils were taken from each spot in each field. Our results show strong linear relationships between mercury concentrations in earthworms (both mature and immature groups) and non-cinnabar mercury form, while cinnabar mercury is less bioavailable to native earthworms. Earthworms may be used as a potential mercury ecological bio-indicator (bio-marker) for demonstrating mercury bioavailability and ecotoxicity in the ecosystem. The long-term stability, mobility and bioavailability of mercury contaminants in these floodplains still needs to be monitored continuously and closely.

Heavy metal contamination has become a great concern worldwide. Although phytoremediation as a novel, cost-effective, and environmental-friendly technique to clean up heavy metal-contaminated soils, regulatory requirements and site assessment are indispensable to optimize its application. Site assessment relies on collecting information on the physical and chemical characteristics of the site's environment and of the metal contaminants. The collected information can be integrated and analyzed by surface geophysical or geochemical techniques to build a mathematical model that can be used for hazard assessment, risk management, feasibility analysis, and remedial engineering. Secondly, phytoremediation requirements must be considered on a site-by-site basis because regulatory standards have not yet been developed. Some useful tips about regulatory requirements will be reviewed. In addition, remote sensing has been developed and applied rapidly in many fields, such as agriculture, forestry, and ecology. This chapter will also present a discussion of the feasibility of using remote sensing, including spectral reflectance, for long-term monitoring of the process of phytoremediation on remediation sites.

In the environment, metallic uranium readily oxidizes to form uranium compounds that contain the uranyl (UO2+2) moiety. For more than a hundred and fifty years, it has been known that when illuminated with ultraviolet (UV) light, uranyl compounds exhibit characteristic fluorescence in the visible region (450–650 nm). We report our efforts to develop a transportable, quantitative Fluorescence Spectral Imaging (FSI) system as a tool for locating and quantifying uranyl compounds dispersed in soils and on other surfaces. A project is underway to develop a set of sensors to locate expended depleted uranium (DU) rounds and to process soil and debris to recover the material from domestic firing ranges. The FSI system can also be utilized to monitor excavation of DU munitions and separation of uranyl compounds from soils. FSI images are acquired by illuminating a surface with a UV light and using a narrow bandpass filter on a camera, recording an image of the resulting fluorescence. The FSI image provides both spatial and spectral information. The FSI system is described and its performance characterized using field samples.

The Hanford Site in western Washington state is currently in the process of an extensive effort to empty and close its radioactive single-shell and double-shell waste storage tanks. Before this can be accomplished, it is necessary to know how much residual material is left in a given waste tank and the chemical makeup of the residue.The Institute for Clean Energy Technology (ICET) at Mississippi State University is currently developing an quantitative in-tank inspection system based on Fourier Transform Profilometry, FTP. FTP is a non-contact, 3-D shape measurement technique. By projecting a fringe pattern onto a target surface and observing its deformation due to surface irregularities from a different view angle, FTP is capable of determining the height (depth) distribution (and hence volume distribution) of the target surface, thus reproducing the profile of the target accurately under a wide variety of conditions. Hence FTP has the potential to be utilized for quantitative determination of residual wastes within Hanford waste tanks. We report the results of a technical feasibility study to document the accuracy and precision of quantitative volume determination using the Fourier transform profilometry technique under simulated Hanford waste tank conditions.

Historically as part of its national security mission, the U.S. Department of Energy’s Y-12 National Security Facility in Oak Ridge, TN, USA acquired a significant fraction of the world’s supply of elemental mercury. During the 1950’s and 1960’s, a large amount of elemental mercury escaped confinement and is still present in the buildings and grounds of the Y-12 Facility and in the Y-12 Watershed. Because of the adverse effects of elemental mercury and mercury compounds upon human health, the Oak Ridge Site is engaged in an ongoing effort to monitor and remediate the area. The main thrust of the Oak Ridge mercury remediation effort is currently scheduled for implementation in FY09. In order to more cost effectively implement those extensive remediation efforts, it is necessary now to obtain an improved understanding of the role that mercury and mercury compounds play in the Oak Ridge ecosystem. Most recently, concentrations of both total mercury and methylmercury in fish and water of lower East Fork Poplar Creek (LEFPC) of Oak Ridge increased although the majority of mercury in the site is mercury sulfide. This drives the US DOE and the Oak Ridge Site to study the long-term bioavailability of mercury and speciation at the site. The stability and bioavailability of mercury sulfide as affected by various biogeochemical conditions –presence of iron oxides have been studied. We examined the kinetic rate of dissolution of cinnabar from Oak Ridge soils and possible mechanisms and pathways in triggering the most recent increase of mercury solubility, bioavailability and mobility in Oak Ridge site. The effects of pH and chlorine on oxidative dissolution of cinnabar from cinnabar-contaminated Oak Ridge soils is discussed. On the other hand, aquatic plants might be good candidate for phytoremediate contaminated waste water and phytofiltration of collective storm water and surface runoff and river. Our greenhouse studies on uptake of Hg by water lettuce (Pistia stratiotes) show that water lettuce is effectively removing Hg from water solution and Hg was mostly stored in roots. One day of growing could remove 93–98% of Hg from water solutions. However, Hg shows acute toxicity to water lettuce as indicated by decreases in fresh biomass and moisture contents.

The objective of our research is to screen and search for suitable plant species for phytoremediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phytoremediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phytoextraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phytoextraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyperaccumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl(2), and Hg(NO(3))(2), were used as contaminant sources. Different types of soil were examined. and chosen for phytoremediation experiments.We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phytoremediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (< 65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg/kg). Consequently, this plant species may not be suitable for mercury phytoremediation. Other plant species, such as Indian mustard (Brassica juncea), a well-studied metal accumulator, exhibited severe chlorosis symptoms during some experiments. Among all the plant species studied, Chinese brake fern (Pteris vittata) accumulated significant amount of mercury in both roots and shoots and hence may be considered as a potential candidate for mercury phytoextraction. During one experiment, Chinese brake ferns accumulated 540 mg/kg and 1469 mg/kg in shoots after 18 days of growing in soils treated with 500 parts-per-million (ppm) and 1000 ppm HgCl(2) powder, respectively; no visual stress symptoms were observed. We also studied mercury phytoremediation using aged soils that contained HgS, HgCl(2), or Hg(NO(3))(2). We have found that up to hundreds of ppm mercury can be accumulated in the roots of Indian mustard plants grown with soil contaminated by mercury sulfide; HgS is assumed to be the most stable and also the predominant mercury form in floodplain soils. We have also started to investigate different mercury uptake mechanisms, such as root uptake of soil contaminant and foliar mercury accumulation from ambient air. We have observed mercury translocation from roots to shoot for Chinese fern and two Indian mustard varieties.

Anatomical, histochemical and biochemical approaches were used to study mercury uptake and phytotoxicity as well as anti-oxidative responses in two species of ferns [Chinese brake fern (Pteris vittata) and Boston fern (Nephrolepis exaltata)], grown in a hydroponic system. The roots of both cultivars accumulated large amounts of mercury, but exhibited limited mercury translocation to shoots. Mercury exposure led to more pronounced phytotoxicity accompanied by stronger oxidative stress in the shoots of P. vittata than in N. exaltata. N. exaltata established a more effective anti-oxidative system against mercury-induced oxidative stress than did P. vittata. The activity of anti-oxidative enzymes (superoxide dismutase, catalase and glutathione reductase) increased. The reduced ascorbate (ASA) and oxidized ascorbate (DHA) are regulated. Mercury exposure led to an increase in the concentration of glutathione (GSH) in both fern species. The present study suggests that N. exaltata is more tolerant to mercury exposure than P. vittata, which has been also reported to be more tolerant to arsenic exposure. N. exaltata may thus have potential for phytostabilization of soils or phytofiltration of waste water contaminated with mercury.