The worldwide occurrence of sites contaminated with toxic metals and the associated high costs of remediating them using chemical and mechanical methods have led to calls to develop inexpensive and sustainable approaches based on the use of plants that naturally accumulate large amounts of metals in their tissues. The ability of plants to remediate metals has been rigorously studied and some species have been identified as excellent phytoremediators. However, the growth of phytoremediators is often retarded under high soil metal concentrations, rendering them ineffective. Meanwhile, some plants do not have remediating abilities but are capable of growing in contaminated environments with little or no sign of stress. Despite the volume of research dedicated to the screening and evaluation of phytoremediators, major questions remain about why some plants survive but do not remediate while the growth of phytoremediators is mostly hindered. The growth and metal-remediating efficiency of plants exposed to toxic concentrations of metals can be enhanced by inoculating phytoremediating plants with certain bacteria but the mechanisms behind this process remain unclear. Furthermore, the use of leguminous plants to improve the growth of a target plant under a mixed planting system has long been recognised as an effective yield-enhancing cropping system. However, the possibility of a non-remediating but tolerant leguminous plant conferring metal tolerance to a phytoremediator has not been explored. This thesis reports results from repeated glasshouse and lab-based growth experiments on the phytoremediating plant Brassica juncea exposed to 400 – 600 mg Zn kg-1. The aim was to investigate the abilities of two plant growth promoting bacteria (PGPB) species Pseudomonas brassicacearum and Rhizobium leguminosarum, and a leguminous plant Vicia sativa to promote B. juncea growth and enhance remediation of Zn-contaminated soil. B. juncea plant roots were analysed using synchrotron based micro-focus X-ray Fluorescence (μXRF) imaging and X-ray Absorption Near Edge Structure (μXANES) analysis to probe Zn speciation. P. brassicacearum exhibited the poorest plant growth promoting ability, while R. leguminosarum alone and in combination with P. brassicacearum significantly enhanced B. juncea growth and Zn bioaccumulation. X-ray Absorption Spectroscopy (XAS) analysis showed that reduced plant growth was due to root accumulation of Zn as Zn sulphate, Zn oxalate and Zn polygalacturonic acids. The better growth and increased metal accumulation observed in plants inoculated with R. leguminosarum and its combination with P. brassicacearum was attributed to root storage of Zn in the chelated forms of Zn phytate and Zn cysteine. A subcellular analysis of plant root also showed that the PGPB enhanced tolerance to Zn contamination by enhancing epidermal Zn compartmentalisation depending on the nature of root colonization, and induced changes in Zn speciation to less toxic Zn species in the epidermis and endodermis of plant root. The thesis therefore identifies enhanced Zn compartmentalization at the root epidermis and bacterial mediated changes in Zn toxicity through changes in Zn speciation as key complimentary mechanisms of plant growth promotion and enhanced Zn accumulation in plants by PGPB. Further experiments investigating alternative phytoremediation strategies showed that the use of the leguminous plant V. sativa in a mixed planting system with B. juncea plants completely out performed the effects of bacteria in promoting the growth and remediation potential of B. juncea under Zn contamination. By combining PGPB with mixed planting, B. juncea recovered full growth while also achieving maximum phytoremediation efficiency. The novel legume assistedmicrobial phytoremediation method that is reported in this thesis is the first to demonstrate complete plant growth recovery in plants exposed to 400 – 450 mg kg-1 soil Zn contamination for 5 weeks. Survival of V. sativa was attributed to its root storage of Zn in the chelated forms of Zn histidine and cysteine whereas in the roots of stunted B. juncea plants the majority of Zn was present as Zn oxalate and toxic Zn sulphate. Although the use of natural and synthetic chelates has been reported to enhance phytoremediation, this thesis recommends a legume-assisted-microbialphytoremediation system as a more sustainable method for Zn bioremediation.

The UK contains 5000 unlined historical landfills in the coastal zone currently at risk of erosion within the next 50 years. These rely on natural attenuation in surrounding sediment to reduce the contaminant load to the environment. This thesis investigates the extent and magnitude of sediment metal contamination from historical estuarine landfills. An intensive investigation of Newlands historical landfill, Essex, indicated elevated metal concentrations in surface and sub-surface sediments. Surface sediment concentrations were similar to other industrially impacted estuaries, whilst peak metal concentrations at c. 50 cm depth were indicative of industrial activity in the mid-20th Century. Below this depth, sediments were enriched with Pb (EF > 2) and Zn (EF = 1.5) indicative of an historic leachate plume that extends c. 15 m from the landfill site boundary. These sediments present a secondary source of diffuse pollution and a site contamination load of c. 1200 kg Pb. In-situ XRF was demonstrated as a rapid contamination screening tool for Fe, Pb, Sr and Zn enabling a broad-scale investigation of historical landfills across SE England. Sediment cores from eight sites containing both hazardous and inert waste were screened. Concentrations and EFs of Pb and Zn at depth were significantly higher in hazardous sites compared to inert sites. Spatial distributions of Pb and Zn were comparable to Newlands historical landfill. This indicates that diffuse pollution from historical landfill sites with similar chemical and physical attributes to Newlands is likely to present a regional, if not national problem, with UK historical landfills presenting contaminated sediments, comprising a significant, previously unidentified and unquantified diffuse pollution source in the coastal zone.

Emerging infectious diseases, pollution and climate change are associated with amphibian extinction events worldwide; however, direct causation is often obscured by the interactions of these stressors. Elucidating the possible synergies between metal contamination and disease is, therefore, critical in advancing our knowledge of the co-evolutionary mechanisms in host-pathogen systems and helping with the ability to better forecast the spread of diseases in metal-stressed environments. Additionally, increasing ecotoxicological research has improved our understanding of the complex influence trace metals may have on the physico-chemical nature of aquatic systems; however, the discrepancy in concentration-response within the toxicological literature makes it difficult to accurately define the range of toxicity, often due to the variability in media used in experimentation. The first chapter of this thesis reports an evaluation of copper, nickel and copper/nickel concentrations on several Northern Leopard Frog (Lithobates [Rana] pipiens) larvae life history traits within field collected smelting effluent water. Overall, results indicated that copper had a stronger negative impact on survival than nickel. However, tadpoles exposed to copper displayed increased growth and developmental patterns while those exposed to nickel demonstrated opposing life history traits. These results indicate that tadpoles are displaying different fitness strategies, in terms of survival and life history, in the presence of increased copper and/or nickel stress.

The acidification and metal contamination of freshwater resources are major environmental concerns in many areas, with Sudbury (Ontario, Canada) having been amongst the most severely impacted. Many scientific investigations have examined the effects of these environmental stressors on aquatic systems, but relatively little is known about the biological recovery process following smelter emission reductions. Therefore, paleolimnological techniques were utilized to determine if diatom and scaled chrysophyte assemblages have recovered toward their pre-disturbance conditions as a result of reduced anthropogenic inputs. Pre-industrial algal assemblages were primarily dominated by circumneutral to alkaline and pH-indifferent taxa. However, there was a shift toward acid-tolerant species in all study lakes with the onset of open pit roasting and smelting operations. Coinciding with emission reductions, scaled chrysophyte assemblages in two of the three study sites have shown evidence of biological recovery. Given the population growth of the city of Sudbury over the last century, and the lack of scientific information regarding cultural eutrophication trends in the region, paleolimnological techniques were also used to track long-term biological changes within diatom assemblages related to cultural disturbances. Historically, oligotrophic diatom taxa primarily dominated the algal assemblages in each of the four study lakes. With the onset of urban environmental stressors there was a shift toward taxa which thrive in more productive systems. In addition, diatom assemblages appear to track increased lakewater pH through time. Finally, geochemical analysis tracked the increase in copper and nickel concentrations in lake sediment with the onset of open pit roasting and smelting activities and the subsequent decline in concentration with emission controls. Metal concentrations in recently deposited lake sediments remain elevated compared to pre-industrial concentrations. Paleolimnological studies comparing pre- and post-disturbance algal assemblages are of interest to lake managers as these data will aid in setting realistic mitigation targets for freshwater systems impacted by acidification, cultural eutrophication, and metal contamination, and will help gauge biological recovery mechanisms. Furthermore, this study provides insight in to the role other environmental stressors (e.g., climate change) may play in the biological recovery process. / Thesis (Master, Biology) -- Queen's University, 2008-07-10 12:04:59.828

In response to sulphur dioxide emission reductions in North America and Europe, there has been a recent shift in research focus towards understanding ecosystem recovery. Evidence for reversibility in the effects of acidification on lake ecosystems within North America has been, for the most part, constrained to a single locality (Sudbury, Ontario). Lakes in a fume-kill area near Wawa, Ontario, present a new and rare opportunity for studying potentially rapid chemical and biological recovery patterns from extreme acidification. Several lakes acidified (pH ~3) during a period of local iron sintering from 1939 to 1998, and although minimal historical data are available, striking biological recovery has recently been observed. This study used paleolimnological techniques to track diatom (class Bacillariophyceae) responses to historical water quality changes in five fume-kill lakes near Wawa. Prior to the onset of iron sintering, the sediment-recorded diatom assemblages were dominated by species that are typically found in circumneutral or slightly alkaline lakes. Following the known occurrence of lake acidification, there was a striking shift in the sediment record towards dominance by acid- and metal-tolerant species. Water quality of the fume-kill lakes has since improved (i.e. pH has increased from ~3 to ~7 and metal concentrations have decreased). In four of the five lake cores, this was reflected by a decrease in the relative abundance of acid-tolerant species. Surprisingly, diatom communities were not progressing towards pre-disturbance species assemblages. Factors impeding the return of native species might include metal enrichment in surface sediment and potentially altered lake thermal regimes. Documenting and understanding recovery trajectories is necessary to help lake managers evaluate policy decisions regarding the efficacy of emission reduction programs and mitigation measures. This thesis provides evidence from one location in addition to Sudbury that the ecological effects of severe lake acidification can be reversed if SO2 emissions are sufficiently reduced. It also further demonstrates the complexity of recovery patterns in acidified and metal-contaminated lakes. / Thesis (Master, Biology) -- Queen's University, 2009-04-26 18:38:20.58

Heavy metals are of great concern when released into the environment, especially at high concentrations. Because of their persistence and toxicity, they have the ability to impact organisms both directly and indirectly via bioaccumulation in the food chain. In this report the effects on aquatic insect composition and abundance as well as possible effects on metamorphosis from larvae to adults were examined in six lakes – three with elevated Zn and Pb concentrations and three reference lakes - situated in Arjeplog municipality. Aquatic larvae and adult aquatic insects were sampled one year apart, and the number of individuals and community composition of both life stages were compared. Contrary to my hypothesis, the results showed no significant differences in abundance, taxa richness or number of individuals in pollution sensitive taxa (EPT) due to contamination. However, the result showed that the effect of contamination on the number of insects is different at different life stages (larval or adult), with fewer adults than expected emerging from contaminated lakes. This is likely explained by detrimental effects, caused by high metal concentrations, obstructing metamorphosis and decreasing emergence success. In this study, the negative effects on emergence could foremost be observed in chironomids (Chironomidae), which was the most abundant insect taxon in both reference and contaminated sites. This leads to the conclusion that including effects on metamorphosis can provide useful insights when assessing effects of a contaminant on the health of freshwater ecosystems.

The purpose of this study was to evaluate different types of metal decontamination from waste water. Specifically, to evaluate water from the mire located at Slagnäs railway depot. Through a literature review from Swedish authorities and entrepreneurs regarding water remediation methods have been compiled and compared. Methods for waste water remediation are chemical methods, sedimentation and filtration. Standardized methods for decontamination are constantly updated with new materials and improved methods. Neither one of these methods are relevant on their own. The idea behind the experiment was to use Fenton reaction on the mire water which would contribute to precipitation of metals. Within the study an experiment with hydrogen peroxide and sodium hydroxide was performed. The idea behind the experiment was to use Fenton reaction on the mire water which would contribute to precipitation of metals. No conclusions can be drawn about hydrogen peroxide also known as Fentons reaction due to lack of analysis results. Trials with sodium hydroxide shown that the best results occur when pH is moderately adjusted at pH 6 and 7. Due to incomplete analytical results no conclusion about Fenton reaction as a waste water treatment method can be drawn based on this experiment. The lack of results is probably due to the continuous reaction between Fentons and organic matter.

<p>Trafik utgör en stor föroreningskälla av tungmetaller i vägnära jordar och särskilt är det koppar (Cu), bly (Pb) och zink (Zn) som associeras med fordonstrafik. I ett historiskt perspektiv härrör blyutsläpp främst från bränsleförbränning, medan kopparemissioner (i första hand från slitage av bromsbelägg) och zinkutsläpp (från däck) från trafik står för så mycket som hälften av det urbana utsläppet av koppar och zink till omgivningen.</p><p>Koppar-, bly- och zinkkoncentrationer i vägnära jord och sediment undersöktes inom avrinningsområdet för Grand River North West i Mauritius. Eftersom totalmetall utgör en dålig indikator på den mängd metall som finns potentiellt tillgänglig för biota användes extraktion med hjälp av 0.5 M HCl tillsammans med totalkoncentrationer.</p><p>Den rumsliga variationen längsmed transekt vinkelrätt mot vägar undersöktes liksom variationen med djupet. Observerade kopparkoncentrationer var jämförbara med bakgrundsnivåer. Till skillnad från Cu var koncentrationer av Pb och Zn förhöjda i den omedelbara närheten till vägar med relativt stor trafikintensitet, men halterna minskade snabbt med avståndet. Resultat från platserna för jordreferenser visar på storskalig förorening av Pb på ön. Uppmätta kopparkoncentrationer kunde inte knytas till trafikens påverkan.</p><p>Vid regn kan metaller som finns i förorenat vägdamm och förorenad jord övergå till löslig form, eller sköljas bort i partikulär form, och transporteras till närliggande vattendrag. I Mauritius är det här av speciell vikt eftersom flodsediment till slut kommer att deponeras i de känsliga kustområdena som omger ön. Dock tyder inte resultaten på förhöjda metallhalter i sediment nära de studerade vägarna.</p><p>Även om erhållna resultat av Cu inte visar på någon förhöjning och zonen med hög förorening av Pb och Zn är relativt smal, är det angeläget att följa utvecklingen eftersom antalet fordon växer snabbt i Mauritius, vilket kan förändra dagens situation och ge upphov till större miljöpåverkan. För att undvika eventuella ekologiska skador är det därför av stor vikt att i fortsättningen övervaka situationen längs landets vägar.</p> / <p>Traffic has been identified as a significant heavy metal polluter of roadside soils, and copper (Cu), lead (Pb) and zinc (Zn) in particular are associated with road travel. In a historic perspective, the Pb contribution from anthropogenic sources to nature has predominantly been a result of fuel combustion. There are indications that Cu (mainly through braking system) and Zn (emissions from tires) released from traffic give rise to as much as half of the total urban contribution of copper and zinc to the environment.</p><p>Concentrations of Cu, Pb and Zn in roadside soils and sediment have been determined at selected roads within the Grand River North West watershed in Mauritius. As total metal concentrations are not a suitable indicator of the metal concentrations that are potentially available to biota, metals extractable in 0.5 M HCl have been determined along with total concentrations. The spatial variation in metal concentration along soil transects perpendicular to roads were investigated, as was the variation with depth.</p><p>Observed Pb and Zn concentrations exhibited elevated levels in topsoil in the immediate vicinity of roads with relatively large traffic densities, but the decrease in concentration with distance was rapid. Results from soil reference sites pointed to a large scale Pb pollution on the island. In comparison, observed Cu concentrations could not be assigned any influence from traffic at the selected study sites.</p><p>In the event of rain, metals contained in polluted road dust and soil may be released into soluble form, or flushed from roadways as particulate matter, and transported to nearby water courses. In Mauritius, this is of particular importance as sediment in rivers eventually may be deposited in the sensitive coastal areas of the island. However, results do not indicate that there were any elevated levels of heavy metals in sediment close to roads that were investigated in this study.</p><p>Although Cu concentrations in roadside soils did not show any enrichment and the zone of elevated Pb and Zn concentrations was not wide, there is a concern that the continuing rapid increase in the number of vehicles in Mauritius will change the situation, possibly resulting in greater impact on the surrounding environment. Hence, in order to avoid any ecological damage, it is desirable to continue monitoring the situation along highways in the country.</p>

As the miniaturization keeps decreasing in semiconductor device fabrication, metal contamination on silicon surfaces becomes critical. An investigation of the fundamental mechanism of metal contamination process on silicon surface is therefore important. Kinetics and thermodynamics of the copper out-plating process on silicon surfaces in diluted HF solutions are both evaluated by several analytical methods.

The Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) have announced that the 1997 review of the Australian Water Quality Guidelines will include for the first time, consideration of sediment quality guidelines. For this reason, it is timely to review the methods for establishing such guidelines, and the manner in which they could be used in managing the quality of sediments in Australian rivers, lakes and drainage systems. In this thesis, the problem of the development of sediment quality guidelines is introduced and basic questions relating to the development of such guidelines are addressed. The importance of sediment monitoring and sediment quality assessment in aquatic ecosystem management is demonstrated, and the role of sediment quality guidelines in the process of sediment quality assessment is discussed. The arguments considered in this thesis are illustrated by specific reference to the setting and use of sediment quality guidelines for heavy metal contamination. A number of physico-chemical factors (grain size distribution, pH, redox potential, alkalinity and hardness, salinity, organic matter) can affect the bioavailability and toxicity of contaminants in sediments, and these factors may vary spatially and temporally within and between sediment deposits. Changes in physico-chemical conditions as a result of natural or anthropogenic processes may lead to major changes in bioavailability of sediment contaminants. The variability of these physico-chemical factors has ramifications for the way in which sediment quality guidelines are derived and used. Factors affecting the way in which toxicity is measured (test species chosen, toxicological end-point measured, duration of test relative to life-cycle), and toxicity data is interpreted, are also important to the development of useful sediment quality guidelines. All of these factors must be taken into account in deriving sediment quality guidelines for Australian conditions. The large number of factors affecting the sensitivity and efficiency of sediment quality guidelines means that a simple set of numerical guidelines, as has been used in the past, is not appropriate. A multi-step assessment procedure will be required. Methods of setting sediment quality guidelines that have been used by authorities in overseas jurisdictions were reviewed. Advantages and disadvantages of the various methods were compared. None of the methods used overseas has been shown to be applicable to Australian conditions. In the absence of a suitable method for deriving Australian sediment quality guidelines in the short term, the adoption of the Canadian Interim Sediment Quality Guidelines as interim sediment quality guidelines for Australia is recommended. Sediment quality guidelines need to be viewed in the context of the overall environmental management process, of which they form an integral part. The policy background to environmental management in Australia, and the management frameworks that have been put in place to implement the policy, are outlined. The AS/NZS/ISO 14000 series of standards for environmental management systems provides a framework which is consistent with the principles and objectives of environmental management in Australia. It therefore provides an appropriate framework within which to develop and use sediment quality guidelines. Within the broad AS/NZS/ISO 14000 policy, a framework for the development and use of sediment quality guidelines is proposed, which will provide a technically and legally defensible basis for the management of aquatic sediments in Australia, in the short term and long term. The proposed framework involves the setting of Interim Sediment Quality Guidelines for Australia, based on the best scientific knowledge currently available. The framework recognises that the factors affecting the bioavailability and toxicity of sediment contaminants are complex, and that the current level of knowledge of sediment processes is incomplete. Therefore, a conservative approach to setting guidelines is taken, and a highly sensitive guideline based on that used in Canada, is proposed. The framework further recognises that this approach will lead to over protection of the environment in some cases, so a "Decision Tree" approach is taken. The "decision tree" allows the consideration of more complex interactions than can be incorporated into simple numeric guidelines, while attempting to simplify the assessment process. In keeping with the ISO 14000 series of standards for environmental management, the framework also explicitly includes steps designed to ensure that monitoring data are regularly collated, and analysed, and where necessary, guidelines are able to be updated in light of new knowledge gleaned from the review process. The proposed framework is appropriate to, and supportive of, the principles of environmental management as set out in Australian Government policy documents, inter governmental and international agreements, and legislation. It provides a basis for the on-going collection of data suited to increasing our understanding of the factors influencing the behaviour of contaminants in sediments, and thereby lead to continual improvement in sediment quality guidelines for use in Australian conditions.