Showing papers on "Trace metal published in 2010"

Geochemical distribution of trace metal pollutants in water and sediments of downstream of an urban river

Abstract: A study was conducted to investigate the trace metal pollution of water and sediments of downstream of Tsurumi River, Yokohama, Japan. Twenty samples of water and sediments were collected from the river starting from Tokyo bay side up to the junction point of the Yagami River. Results show that the mean concentrations of chromium, cupper and nickel in water greatly exceed (>100 times) the surface water standard. The concentration of molybdenum and lead was also higher than standard values while iron and manganese was lower than that of surface water standard. The mean concentration of zinc, cupper, cadmium, lead, chromium, vanadium, bromine and iodine was 381.1, 133.0, 1.0, 40.8, 102.9, 162.0, 71.5 and 10.6 µg/g sediments, respectively and was greatly exceed the average worldwide shale concentrations and average Japanese river sediment values. However, mean concentration of arsenic, nickel and strontium was 11.0, 36.6 and 164.6 µg/g sediments, respectively which was lower than the average shale value. Other analyzed trace metals, including barium, zirconium, rubidium, yttrium, tin, antimony, cesium, lanthanum, cerium, praseodymium and neodymium were detected in river sediments; the concentration of which was close to the Japan's river sediment average values. Pollution load index values of the sites of the studied area ranged from 1.24 to 7.65 which testify that the river sediments are polluted. The PLI value of the area was, however, high (6.53) as the concentration of trace metals like zinc, cupper, cadmium, lead and chromium were very high and were the major pollutants.

Trace elements in soils

Abstract: 1. Introduction Peter S. Hooda 2.Trace Elements: General Soil Chemistry, Principles and Processes Filip M.G. Tack 2.1 Introduction 2.2 Distribution of trace elements in the soil 2.3 Chemical species 2.4 Sorption and desorption 2.5 Precipitation and dissolution 2.6 Mobilisation of trace elements 2.7 Transport 2.8 Plant uptake 2.9 Concluding remarks References 3. Soil Sampling and Sample Preparation Anthony C. Edwards 3.1 Introduction 3.2 Soil sampling 3.3 Errors associated with soil sampling and preparation 3.4. Overview of the current situation 3.5 Scale and variability 3.6 Conclusions References 4. Analysis and Fractionation of Trace Elements in Soils Gijis Du Laing 4.1. Introduction 4.2. Total Analysis 4.3. Fractionation of Trace Elements 4.4. Species-retaining and Species-selective Leaching Techniques 4.5. Equipment for Direct Speciation of Trace Elements in Soil 4.6. Conclusions References 5. Fractionation and Speciation of Trace Elements in Soil Solution Gijis Du Laing 5.1. Introduction 5.2. Soil Solution Sampling, Storage and Filtration 5.3. Particle Size Fractionation 5.4. Liquid-liquid Extraction 5.5. Ion Exchange Resins and Solid Phase Extraction 5.6. Derivatisation Techniques to Create Volatile Species 5.7. Chromatographic Separation of Trace Element Species 5.8. Capillary Electrophoresis (CE) 5.9. Diffusive Gradients in Thin Films (DGT) 5.10. Ion-selective Electrodes 5.11. Donnan Membrane Technique 5.12. Voltammetric Techniques 5.13. Microelectrodes and Microsensors 5.14. Models for Predicting Metal Speciation in Soil Solution 5.15. Conclusions References 6. Long-Term Issues, Impacts And Predictive Modelling Weiping Chen, Andrew C. Chang, Laosheng Wu, Albert L. Page and Bonjun Koo 6.1 Introduction 6.2 Biosolids-borne Trace Elements in Soils 6.3 Assessing Availability of Trace Elements in Biosolids-amended Soils 6.4 Long-Term Availability Pool Assessment through a Root Exudates-based Model 6.5 Conclusions References 7. Fertilizer-borne Trace Element Contaminants in Soils Samuel P. Stacey, Mike J. McLaughlin and Ganga Hettiarachchi 7.1 Introduction 7.2. Phosphatic Fertilisers 7.3. Micronutrient Fertilisers 7. 4. Long-term Accumulation of Fertilizer-borne Trace Element Contaminants 7.5. Trace Elemental Contaminant Transfer to Crops and Grazing Animals 7.6. Conclusions References 8. Trace Metal Exposure and Effects on Soil Dwelling Species and their Communities David J. Spurgeon 8.1 Introduction 8.2 Hazards and Consequences of Trace Metal Exposure 8.3. Routes of Exposure, Uptake and Detoxification 8.4. Conclusions References 9. Trace Element Deficient Soils Rainer Schulin, Annette Johnson, and Emmanuel Frossard 9.1 Introduction 9.2. The concept of trace element deficient soils 9.3. Methods to identify and map soil trace element deficiencies 9.4. Soil factors associated with trace element deficiencies 9.5. Treatment of soils deficient in trace elements References 10. Application of Chemical Speciation Modelling to Studies on Toxic Element Behaviour in Soils Les J. Evans, Sarah J. Barabash, David G. Lumsdon and Xueyuan Gu 10.1. Introduction 10.2. The structure of chemical speciation models 10.3. The species/component matrix 10.4. Aqueous Speciation Modeling 10.5. Surface Complexation Modeling to Mineral Surfaces 10.6. Surface Complexation Modelling to Soil Organic Matter 10.7. Discussion References Bioavailability, Risk Assessment and Remediation 11. Assessing Bioavailability of Soil Trace Elements Peter S. Hooda 11.1. Introduction 11.2. Speciation, Bioavailability and Bioaccumulation Definitions and Concepts 11.3. Bioavailability Assessment Approaches 11.4.Discussion and Conclusions References Bioavailability: Exposure, Dose and Risk Assessment 12. Assessing Bioavailability of Soil Trace Elements Rupert L. Hough 12.1 Introduction 12.2 Hazard Identification 12.3. Exposure Assessment 12.4. Dose-Response 12.5. Risk Characterisation 12.6 Assessment of mixtures and disparate risks 12.7 Conclusions References 13. Regulatory Limits for Trace Elements in Soils Graham Merrington, Sohel Saikat and Albania Grosso 13.1. Introduction 13.2. Derivation of regulatory limits for trace elements 13.3. National and international initiatives in setting limit values 13.4. Forward look 13.5. Conclusions 14 Phytoremediation of Soil Trace Elements Rufus L. Chaney, C. Leigh Broadhurst and Tiziana Centofanti 14.1. Introduction 14.2. Nature of soil contamination where phytoextraction may be applied 14.3. Need for metal tolerant hyperaccumulators for practical phytoextraction 14.4. Phytoremediation strategies applications and limitations 14.5. Phytostabilization of Zn-Pb, Cu, or Ni mine waste or smelter contaminated soils 14.6. Recovery of elements from phytoextraction biomass 14.7. Risks to wildlife during phytoextraction operations? 14.8 Conclusions References 15. Trace Element Immobilization in Soil Using Amendments Jurate Kumpiene 15.1 Introduction 15.2 Soil Amendments for Trace Element Immobilization 15.3 Method Acceptance 15.4 Concluding remarks References Characteristics and Behaviour of Individual Elements 16. Arsenic and Antimony Yuji Arai 16.1. Introduction 16.2. Geogenic Occurrence 16.3. Sources of Soil Contamination 16.4. Chemical Behaviour in Soils 16.5 Arsenic retention in soils 16.6 Risks from As and Sb in Soils 16.7 Conclusions and Future Research Needs References 17. Cadmium and Zinc Rufus L. Chaney 17.1. Introduction 17.2. Geogenic occurrence and sources of soil contamination 17.3. Chemical behavior in soils 17.4. Plant accumulation of soil Cd and Zn 17.5. Risk implications for Cd in soil amendments 17.6. Plant uptake of Cd and Zn in relation to food-chain Cd risk 17.7. Food-chain Zn issues References 18. Copper and Lead Rupert L. Hough 18.1 Introduction 18.2. Copper 18.3. Lead 18.4. Risks from copper and lead 18.5 Concluding remarks References 19. Chromium, Cobalt and Nickel Yibing Ma and Peter S. Hooda 19.1. Introduction 19.2. Geogenic Occurrences 19.3. Sources of Soil Contamination 19.4. Chemical Behaviour in Soils 19.5. Environmental and Human Heath Risks 19.6. Concluding Remarks References 20. Manganese and Selenium Zhenli L. He, Jiali Shentu, and Xiao E. Yang 20.1 Introduction 20.2 Concentrations and Sources of Mn and Se in soils 20.3. Chemical Behavior of Mn and Se in soils 20.4. Effects on Plant, Animal and human Health References 21. Tin and Mercury Martin J. Clifford, Gavin M. Hilson and Mark E. Hodson 20.1. Introduction 21.2. Geogenic Occurrence 21.3. Sources of Soil Contamination 21.4. Chemical Behaviour in Soils 21.5. Risks from Tin and Mercury in Soils References 22. Molybdenum, Silver, Thallium,and Vanadium Les J. Evans and Sarah J. Barabash 22.1. Introduction 22.2. Molybdenum 22.3. Silver 22.4. Thallium 22.5. Vanadium 22.6. Environmental and Human Health Risks References 23. Gold and Uranium Ian D. Pulford 23.1. Introduction 23.2. Geogenic Occurrence 23.3. Soil Contamination 23.4. Chemical Behaviour in Soils 23.5. Risks from Gold and Uranium in Soils 23.6. Concluding Comments References 24. Platinum Group Elements in Soil F. Zereini and C.L.S. Wiseman 24.1. Introduction 24.2. Sources of PGE in soils 24.3. Emissions, Depositional Behavior and Concentrations in Soils 24.4. Geochemical Behaviour in Soils 24.5. Bioavailability 24.6. Conclusions References

Geochemical and statistical approach for evaluation of heavy metal pollution in core sediments in southeast coast of India

Abstract: Industrialization coupled with urbanizaton has led to stress in the Buckingham Canal which runs parallel to Bay of Bengal at a distance of around 1 km from the coastline. 4 sediment cores were collected along Ennore - Pulicat stretch to determine acid leachable trace metal concentration. Core samples were collected using gravity corer. The cores were sliced horizontally at 2.5 cm to determine the grain size, sediment composition, pH, organic matter, calcium carbonate, acid leachable trace metals; cadmium, chromium, copper, lead, zinc. The trace metals were extracted using acid mixture containing hydro fluoric acid, nitric acid and sulphuric acid and analysed by atomic emission spectrophotometer. In an attempt to infer anthropogenic input from geogenic input, several approaches including comparison with sediment quality guidelines - ecotoxicological sense of heavy metal contamination and classification by quantitative indexes such as geoaccumalation index, anthropogenic factor, enrichment factor, contamination factor and degree and pollution load index was attempted. Grain size analysis and sediment composition of core samples shows Ennore is sandy in nature having a neutral pH. Organic matter enrichment is observed to a higher extent in core 3. Core 2 at a depth of 5 cm shows organic matter of 9.4 %. calcium carbonate is totally absent at the surface sediments in core 2. Cores collected within the canal showed a higher heavy metal concentration than the cores collected from Pulicat lagoon and 2 km into the Ennore Sea. The trace metal concentration for cadmium, lead and zinc in Ennore does not pose a threat to the sediment dwelling fauna whereas chromium and copper are likely to pose a threat. Quantitative indexes place Ennore under moderately polluted. Ennore is likely to face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted.

Trace metal phytotoxicity in solution culture: a review

Abstract: Solution culture has been used extensively to determine the phytotoxic effects of trace metals. A review of the literature from 1975 to 2009 was carried out to evaluate the effects of As(V), Cd(II), Co(II), Cu(II), Hg(II), Mn(II), Ni(II), Pb(II), and Zn(II) on plants grown in solution. A total of 119 studies was selected using criteria that allowed a valid comparison of the results; reported toxic concentrations varied by five orders of magnitude. Across a range of plant species and experimental conditions, the phytotoxicity of the trace metals followed the trend (from most to least toxic): Pb approximately Hg >Cu >Cd approximately As >Co approximately Ni approximately Zn >Mn, with median toxic concentrations of (muM): 0.30 Pb, 0.47 Hg, 2.0 Cu, 5.0 Cd, 9.0 As, 17 Co, 19 Ni, 25 Zn, and 46 Mn. For phytotoxicity studies in solution culture, we suggest (i) plants should be grown in a dilute solution which mimics the soil solution, or that, at a minimum, contains Ca and B, (ii) solution pH should be monitored and reported (as should the concentrations of the trace metal of interest), (iii) assessment should be made of the influence of pH on solution composition and ion speciation, and (iv) both the period of exposure to the trace metal and the plant variable measured should be appropriate. Observing these criteria will potentially lead to reliable data on the relationship between growth depression and the concentration of the toxic metal in solution.

Trace metal dynamics in fishes from the southwest coast of India.

Abstract: The concentration of Fe, Co, Ni, Cu, Zn, Cd, and Pb in the muscle tissue of marine fishes like Lates calcarifer, Nemipterus japonicus, Caranx melampygus, Rastrelliger kanagurta, and Cyanoglossus macrostomus was estimated from samples collected in the continental shelf waters off Kochi and Mangalore on southwest coast of India. Species-specific and spatially heterogeneous patterns of tissue metals loads were apparent within the pelagic and demersal fish species for the two regions. The concentration ranges of Fe (541.60 to 649.60 ppm), Ni (12.12 to 13.92 ppm), and Cu (3.09 to 3.62 ppm) were higher in the demersal species C. melampygus, whereas Co (9.10 to 11.80 ppm) and Zn (79.30 to 84.30 ppm) were higher in the pelagic species L. calcarifer and Cd (4.35 to 6.38 ppm) were higher in the demersal species N. japonicus, possibly due to enhanced bioavailability of these metals from ecological processes associated with upwelling during the summer monsoon. The fish species showed a great capacity to accumulate metals, with highest bioaccumulation for the essential element iron and lowest bioaccumulation for the non-essential element lead. Among the demersal species, C. melampygus and N. japonicus had high concentration factors for the metals Fe (280,268 to 322,808), Ni (88,252 to 96,891), Cu (2,351 to 2,600), and Cd (29,637 to 32,404). In contrast, the pelagic species L. calcarifer and R. kanagurta had high concentration factors for the metals Zn (40,812 to 46,892), Co (280,285 to 423,037), and Pb (854 to 1,404).

Distribution pattern of trace metal pollutants in the sediments of an urban wetland in the southwest coast of India

Abstract: A study was carried out to invstigate the concentrations and spatial distribution of trace metals in the sediments of Kottuli Wetland,whuich is in the south west coast of India Eight stations were strategically positioned along the length of wetland and sampled for trace metals (Cu, Mn, Cd, Ni, Pb, Zn &Cr) content. From the analysis, it was observed that the mean concentration of all the analysed trace metals exceeded the average world wide shale concentrations and average Japanese river sediment values. Pollution load index value (PLI) of the studied area ranged from 0.10 to 58.78 which indicated that the wetland sediments were polluted. From the study, PLI of the downstream area of the wetland had the highest values of Cu, Mn, Cd, Zn & Cr. According to the index of Geoaccumulation, Igeo, all the sampling stations may face a severe trace metal pollution contamination problem in the future.

Microbial activities and trace element contents in an urban soil.

Abstract: Soil biological properties are influenced by trace metals. The main sources of these pollutants in the urban areas are industrial plants, power stations, domestic heating systems and motor vehicles. The aim of this work was to evaluate, in relation to distance from urban roads, soil trace metal concentrations (Pb, Cu, Cr, Cd and V) and their influence on C-microbial biomass as well as on soil respiration and enzyme activities (phosphatase glucosidase, galactosidase, xylanase, cellulase, trealase, protease and invertase). The samplings were carried out at four sites, along a route that goes from Giannone Street to Passionisti Street, two heavily travelled roads at two different times of the year (spring and autumn). Heavy metal contents and microbial activities were highest at the sites near the roads. The highest values of microbial activities were found in the inner site; here, on the contrary, the lowest concentrations of heavy metals were measured. Significant and negative correlations were found between microbial activity and heavy metal contents.

Assessment of trace metal pollution in surface sediments of Nemrut Bay, Aegean Sea.

Abstract: Surface sediments collected from nine stations in Nemrut Bay, Aegean Sea were analyzed for trace metals (Hg, Cd, Pb, Cr, Cu, Zn, Mn, Ni, Fe, As, and Mg) and grain sizes. The results were compared with the numerical sediment guidelines used in North America as well as literature values reported for similar studies conducted in Izmit Bay and Izmir Bay. The metal levels were also evaluated according to the enrichment factor and contamination factor analyses. The analyses revealed significant anthropogenic pollution of Hg, Pb, Zn, and As in the surficial sediments of Nemrut Bay.

Using FlFFF and aTEM to determine trace metal-nanoparticle associations in riverbed sediment.

Abstract: Environmental context. Determining associations between trace metals and nanoparticles in contaminated systems is important in order to make decisions regarding remediation. This study analysed contaminated sediment from the Clark Fork River Superfund Site and discovered that in the <1-μm fraction the trace metals were almost exclusively associated with nanoparticulate Fe and Ti oxides. This information is relevant because nanoparticles are often more reactive and show altered properties compared with their bulk equivalents, therefore affecting metal toxicity and bioavailability. Abstract. Analytical transmission electron microscopy (aTEM) and flow field flow fractionation (FlFFF) coupled to multi-angle laser light scattering (MALLS) and high-resolution inductively coupled plasma mass spectroscopy (HR-ICPMS) were utilised to elucidate relationships between trace metals and nanoparticles in contaminated sediment. Samples were obtained from the Clark Fork River (Montana, USA), where a large-scale dam removal project has released reservoir sediment contaminated with toxic trace metals (namely Pb, Zn, Cu and As) which had accumulated from a century of mining activities upstream. An aqueous extraction method was used to recover nanoparticles from the sediment for examination; FlFFF results indicate that the toxic metals are held in the nano-size fraction of the sediment and their peak shapes and size distributions correlate best with those for Fe and Ti. TEM data confirms this on a single nanoparticle scale; the toxic metals were found almost exclusively associated with nano-size oxide minerals, most commonly brookite, goethite and lepidocrocite.

Integrated Environmental Quality Assessment of Kizilirmak River and its Coastal Environment

Abstract: Kizilirmak River receives substantial loads of nutrients, trace metals and other compounds, resulting from anthropogenic activities within its catchment. The main aims of this research were to evaluate spatial and seasonal trends in water discharge, nutrients and trace metals and also to compare data with water and sediment quality criteria and with certain quality indices such as water quality index (WQI), sediment quality index (SQI) and trophic state index (TSI), identifying the environmental pressures and assessing the impact of the loads to the coastal environment. Nine stations were sampled within the main stream of Kizilirmak River near to the Black Sea. Field measurements and routine laboratory water analysis were carried on the eight sampling stations seasonally. Wet sediment sample analyses were also performed for EC, pH, organic matter and moisture content within the range of 1.13-1.76 mS; 7.52-8.80; 1.41-4.60%; 18.92-33.65%, respectively. However, trace metal analyses including Cd, Ni and Pb were done by Atomic Absorption Spectroscopy (AAS) both on water and sediment samples with the total digestion methods. Since the analytical cost involved could be a limiting factor for river quality assessments in developing countries, certain quality indices were used in this study. For each type of indices calculations, different approaches from the literature were selected and compared. Calculated NSFWQI, WQInew and WQI min. values are in good agreement and the water quality of the river is considered at medium level. For the Derbent Dam of Kizilirmak River, two different trophic level index calculations have also the same results indicating eutrophic conditions where algal growth and blooms can occur. However, certain metal quality indices both for water and sediment measurements indicate that the river has medium quality of lead pollution which may be caused by automobile exhausts and urban storm run-off.

Rhizosphere pH dynamics in trace-metal-contaminated soils, monitored with planar pH optodes

Abstract: The present study presents new insights into pH dynamics in the rhizosphere of alpine pennycress (Noccaea caerulescens (J. Presl & C. Presl) F.K. Mey), maize (Zea maysL.) and ryegrass (Lolium perenneL.), when growing on three soils contaminated by trace metals with initial pH values varying from 5.6 to 7.4. The pH dynamics were recorded, using a recently developed 2D imaging technique based on planar pH optodes. This showed that alpine pennycress and ryegrass alkalinized their rhizosphere by up to 1.7 and 1.5 pH units, respectively, whereas maize acidified its rhizosphere by up to −0.7 pH units. The alkalinization by the roots of alpine pennycress and ryegrass was permanent and not restricted to specific root zones, whereas the acidification along the maize roots was restricted to the elongation zone and thus only temporary. Calculations showed that such pH changes should have noticeable effects on the solubility of the trace metal in the rhizosphere, and therefore on their uptake by the plants. As a result, it is suggested that models for trace metal uptake should include precise knowledge of rhizospheric pH conditions.

Heavy metal incorporation in foraminiferal calcite: results from multi-element enrichment culture experiments with Ammonia tepida

Abstract: . The incorporation of heavy metals into carbonate tests of the shallow water benthic foraminifer Ammonia tepida was investigated under controlled laboratory conditions. Temperature, salinity, and pH of the culture solutions were kept constant throughout the duration of this experiment, while trace metal concentrations were varied. Concentrations of Ni, Cu, and Mn were set 5-, 10-, and 20 times higher than levels found in natural North Sea water; for reference, a control experiment with pure filtered natural North Sea water was also analysed. The concentrations of Cu and Ni from newly grown chambers were determined by means of both μ-synchrotron XRF and Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS). The results of both independent analytical techniques agreed within the analytical uncertainty. In general, the concentration of the analysed elements in the tests increased in line with their concentration in the culture solutions. Potential toxic and/or chemical competition effects might have resulted in the decreased incorporation of Ni and Cu into the calcite of the specimens exposed to the highest elemental concentrations. Mn incorporation exhibited large variability in the experiment with the 20-fold increased element concentrations, potentially due to antagonistic effects with Cu. The partition coefficients of Cu and Ni were calculated to be 0.14 ± 0.02 and 1.0 ± 0.5, respectively, whereas the partition coefficient of Mn was estimated to be least 2.4. These partition coefficients now open the way for reconstructing past concentrations for these elements in sea water.

Macroalgae and DGT as indicators of available trace metals in marine coastal waters near a lead–zinc smelter

Abstract: The levels of Cd, Cu, Pb, and Zn were determined in the commonest species of green, red, and brown algae collected from five coastal sites in south-western Sardinia (Italy), an area with a long history of mining and smelting. The usefulness of employing Enteromorpha sp. and Padina pavonica (L.) Thivy to monitor metal pollution was evaluated, while diffusive gradients in thin films (DGT) devices were used to measure dissolved metals in seawater. Levels of Cd and Pb were high enough to be of environmental concern in the whole study area. A significant relationship was found between the content of Pb in P. pavonica and DGT-labile Pb in seawater, suggesting that gross elemental concentrations of nonessential metals such as Pb in algal tissues are apparently controlled by the abundance of dissolved metal species in the ambient seawater. The results pointed out the usefulness of using both DGT and algal methods for a better understanding of trace metal availability in coastal waters.

A baseline study of trace metals in a coral reef sedimentary environment, Lakshadweep Archipelago

Abstract: Surficial and core samples collected from the sedimentary microenvironments of Lakshadweep Archipelago were analysed for their trace metal contents. The synoptical relations in spatial distributions with respect to environmental conditions such as pH, organic carbon and sediment texture were inter-correlated. Some of the metals exhibited good correlations with Fe/Mn, which reflect their similarity in distribution rather than anthropogenic enrichment. Inter-relating the variations in metal—pH relationships with metal—organic carbon, in general, those which exhibited positive correlations with pH, displayed negative interactions with organic carbon content and vice versa. Comparatively, higher values of Fe in the mangrove area of one of the islands highlight the possibility of precipitation of Fe as iron sulphides, which are common in mangrove ecosystem. Based on the contamination factors for Pb, Zn and Cd, as well as the geo-accumulation index of Cd, it can be generalised that some of the islands remain polluted with respect to these elements. An evaluation based on pollution load index shows that none of the islands surveyed for this study posed a serious threat in trace metal pollution. Bray Curtis similarity index was computed to find out the similarity among metals/islands, using non-transformed data of metal concentrations. Group linkage clustering technique was used for drawing dendrograms to show the similarity among them.

Climate-driven mobilisation of acid and metals from acid sulfate soils

Abstract: The recent drought in south-eastern Australia has exposed to air, large areas of acid sulfate soils within the River Murray system. Oxidation of these soils has the potential to release acidity, nutrients and metals. The present study investigated the mobilisation of these substances following the rewetting of dried soils with River Murray water. Trace metal concentrations were at background levels in most soils. During 24-h mobilisation tests, the water pH was effectively buffered to the pH of the soil. The release of nutrients was low. Metal release was rapid and the dissolved concentrations of many metals exceeded the Australian water quality guidelines (WQGs) in most tests. The concentrations of dissolved Al, Cu and Zn were often greater than 100× the WQGs and strong relationships existed between dissolved metal release and soil pH. Attenuation of dissolved metal concentrations through co-precipitation and adsorption to Al and Fe precipitates was an important process during mixing of acidic, metal-rich waters with River Murray water. The study demonstrated that the rewetting of dried acid sulfate soils may release significant quantities of metals and a high level of land and water management is required to counter the effects of such climate change events.

Baseline Trace Metals in Seagrass, Algae, and Mollusks in a Southern Tyrrhenian Ecosystem (Linosa Island, Sicily)

Abstract: Trace elements were analyzed in organisms collected at five sampling stations along coastal areas of Linosa Island, Sicily (southern Tyrrhenian Sea, Italy). Concentrations of Cd, Cr, Cu, Pb, and Zn were measured in Posidonia oceanica L. Delile tissues, the two brown algae Padina pavonica (L.) Thivy and Cystoseira sp., and the two gastropod mollusks Monodonta turbinata Born and Patella caerulea L. Seawater samples were also collected at each site to assess soluble metal concentrations and to gain relevant information on their bioaccumulation ability. Data were processed by multivariate techniques, such as principal component analysis (PCA) and linear discriminant analysis on PCA factors. The scoreplots obtained showed that the pollutant distribution is more significantly correlated with species than with sites. For seaweeds, P. oceanica was associated with higher Cd, Cu, and Zn levels; Padina species had higher Cr concentrations, and Cystoseira had higher Pb levels. For mollusks, Monodonta species had high concentrations of Cu and Cr and Patella species were associated with Cd. Some general metal bioaccumulation patterns are described but no one sampling site was more contaminated than the others. The hypothesis of Linosa island serving as a reference ecosystem for baseline trace metal levels in southern Tyrrhenian areas is indeed supported by the statistical comparison among other southern Tyrrhenian ecosystems performed with Kruskall Wallis and Mann-Whitney tests. For P. oceanica leaves, P. pavonica, M. turbinata, and P. caerulea, this study confirms their usefulness as possible cosmopolitan biomonitors of trace metals in marine Mediterranean areas.

The Association of Cobalt with Iron and Manganese (Oxyhydr)oxides in Marine Sediment

Abstract: Formation and dissolution of authigenic Fe and Mn (oxyhydr)oxides influence cycling of trace metals in oxic/suboxic surface sediments. We used the diffusive gradients in thin films technique (DGT) to estimate the association of cobalt with iron and manganese oxides. We compared Co, Fe and Mn maxima measured by DGT in the pore waters of fresh and aged marine sediment cores and estimated the Co/Fe and Co/Mn ratios in the metal oxides. A Mn maximum was not visible in DGT concentration profiles of freshly collected sediment cores, but after ageing the sediment, we observed a distinct Mn peak, presumably due to broadening of the depth range over which the various electron acceptors occur. Estimated Co/Mn ratios from both experiments are within the range of literature values for marine sediments, but the value from the aged experiment is at the lower end of the range. This is attributed to stimulation of sulphate reduction and precipitation of cobalt sulphides. The good correlation between Co and Fe maxima in the fresh sediments is attributed to the similarity of their reactions with sulphide rather than Co being released during authigenic Fe oxide reduction.