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Despite bryophytes being well adapted to various ecological settings, they are rarely considered in reclamation projects. In this study, propagation regenerative capabilities of bryophytes on different substrates (sand, amphibolite, and pegmatite) and conditions (with or without peat amendment, shade and shredding) were tested in greenhouse and field experiments. In the greenhouse trial, after 6 months of reintroduction, Racomitrium species (Racomitrium canescens (Hedw.) Brid. and Racomitrium elongatum Frisvoll.) had higher regeneration compared to Polytrichum species (Polytrichum juniperinum Hedw. mixed with Polytrichum piliferum Hedw.; a combination of shade (65% shading) and peat amendment (0.5 cm depth) was found to be particularly effective, resulting in up to 100% of Racomitrium species regeneration; shredding the stems of Polytrichum species into small pieces of 0.5–1.0 cm inhibited its regeneration. In the field trial, peat amendment had no effect on moss regeneration. The addition of fluvioglacial sand or till on waste rocks promoted bryophytes regeneration in both the greenhouse and field. These results provide science-based practical knowledge to support the inclusion of native bryophytes in waste rock restoration plans for mines located in northern boreal forests. [ABSTRACT FROM AUTHOR]

Soil salinity is a destructive environmental stressor that greatly reduces plant growth and productivity. In recent years, large tracts of farmland in arid and semiarid regions have been simultaneously affected by salinity and heavy metal pollution, arousing widespread environmental concern. Phytoremediation, defined as the use of plants to remove pollutants from the environment and (or) to render them harmless, is a low cost, environmentally friendly, and effective method for the decontamination of soils polluted by heavy metals. Halophytes, which can survive and reproduce in high-salt environments, are potentially ideal candidates for phytoremediation of heavy metal contaminated saline soils. In this review, we discuss the current progress on the use of halophytes, their tolerance mechanisms to salt and heavy metal toxicity, and their potential for phytoremediation in heavy metal contaminated saline soils. The relative mechanisms are discussed and the future perspectives are proposed. [ABSTRACT FROM AUTHOR]

The plant-growth-promoting rhizobacterium (PGPR) Y4-4 was isolated from plant rhizosphere soil and identified as Pantoea sp. by 16S rRNA sequence analysis. The effects of strain Y4-4 on alfalfa grown in heavy-metals-contaminated soil was investigated using a pot experiment. In a Cu-rich environment, the shoot dry mass and total dry mass of plants inoculated with strain Y4-4 increased by 22.6% and 21%, and Cu accumulation increased by 15%. In a Pb-Zn-rich environment, the shoot dry mass and total dry mass of plants inoculated with strain Y4-4 increased by 23.4% and 22%, and Zn accumulation increased by 30.3%. In addition, the salt tolerance and biomass of wheat seedlings could be improved by applying strain Y4-4 mixed with plant residue as a result of the Cu-rich plant residues providing copper nutrition to wheat. This study offers an efficient PGPR with strong salt tolerance and a safe strategy for the post-treatment of plant residue. [ABSTRACT FROM AUTHOR]

Phytoremediation combined with suitable microorganisms and biodegradable chelating agents can be a means of reclaiming lands contaminated by toxic heavy metals. We investigated the ability of a lead- and cadmium-resistant bacterial strain (JB12) and the biodegradable chelator ethylenediamine- N, N′-disuccinic acid (EDDS) to improve absorption of these metals from soil by tall fescue and red clover. Strain JB12 was isolated from contaminated soil samples, analysed for lead and cadmium resistance, and identified as Burkholderia cepacia. Tall fescue and red clover were grown in pots to which we added JB12, ( S, S)-EDDS, combined JB12 and EDDS, or water only. Compared with untreated plants, the biomass of plants treated with JB12 was significantly increased. Concentrations of lead and cadmium in JB12-treated plants increased significantly, with few exceptions. Plants treated with EDDS responded variably, but in those treated with combined EDDS and JB12, heavy metal concentrations increased significantly in tall fescue and in the aboveground parts of red clover. We conclude that JB12 is resistant to lead and cadmium. Its application to the soil improved the net uptake of these heavy metals by experimental plants. The potential for viable phytoremediation of lead- and cadmium-polluted soils with tall fescue and red clover combined with JB12 was further enhanced by the addition of EDDS. [ABSTRACT FROM AUTHOR]

Recent investigations involving intact rabbit renal proximal tubules indicated that organic anion transporter 3 (OAT3) may be involved in the transport of 2,3-dimercapto-1-propanesulfonic acid (DMPS). Therefore, we evaluated the interaction of OAT3 with DMPS to determine the effect of OAT3 on basolateral DMPS uptake. We used stably transfected HEK293 cells expressing human and rabbit orthologs of the exchanger OAT1 and OAT3. Using 6-carboxyfluorescein (6-CF) as a substrate, the IC50 determinations for reduced DMPS (DMPSH) revealed a stronger interaction with OAT1 than with OAT3 (rbOAT1, 123.3 ± 13.7; hOAT1, 85.1 ± 8.8; rbOAT3, 171.7 ± 22.3; and hOAT3, 172.2 ± 36.4 µmol/L). However, inhibition of 6-CF uptake by the oxidized form of DMPS (DMPSS), the main form of DMPS in the blood, showed a greater affinity for OAT3 (rbOAT1, 237.4 ± 23; hOAT1, 104.6 ± 13.1; rbOAT3, 52.4 ± 7.6; and hOAT3, 31.6 ± 6.6 µmol/L). To determine whether DMPSH and DMPSS are substrates for OAT3, we performed efflux studies with [14C]glutarate and inwardly directed gradients of glutarate. The inhibitors trans-stimulated the efflux of [14C]glutarate, suggesting that OAT3 may be able to transport both forms of DMPS. On the basis of the substantial interaction of OAT3 with DMPSS, we conclude that OAT3 represents the dominant basolateral player in renal detoxification processes resulting from use of DMPS. [ABSTRACT FROM AUTHOR]

Levels of the heavy metal cadmium (Cd) in food products are a food safety concern. Grain Cd is higher in durum (Triticum turgidum L. var. durum) than in common wheat, so reduction of Cd in durum grain is a priority of breeding programs. Previous research demonstrated that a single dominant gene, Cdu1, confers the low grain Cd phenotype, but the map location of the gene is not known. A doubled haploid population segregating for Cd concentration, developed from the cross of W9262-260D3 (a Kyle*2/Biodur inbred selection with low Cd uptake) and Kofa (high Cd uptake) and mapped with microsatellite markers, was used to locate Cdu1. Grain Cd concentration was determined by standard laboratory methods on field grain samples in 2000 and 2001. The Cd concentration segregated bimodally, allowing Cdu1 to be mapped qualitatively as well as quantitatively with quantitative trait locus analysis. The Cdu1 gene mapped to the long arm of chromosome 5B. [ABSTRACT FROM AUTHOR]

A detailed characterization of the different types of air pollution control residues (APCR) produced in municipal waste incinerators has been performed. The analysis of the Pb distribution in boiler and electrofilter ashes has shown that the separation of these ashes in two fractions (<125 µm and >125 µm) allows to get a coarse fraction slightly contaminated and a finer fraction more heavily contaminated, which can be treated by chemical means. Scanning electron microscope – energy-dispersive spectrometry (SEM-EDS) techniques have been used to identify the most dominant forms of the lead particles. Lead present in used lime is principally associated with oxides in a carrying phase of calcium chloride or phosphate. Lead present in boiler and electrofilter ashes is principally associated with silicates and phosphates. Finally, only one leaching step in alkaline aqueous solution is required to remove a large proportion of the leachable lead in APCR and to reach the allowed level by the toxicity characteristic leaching procedure test (TCLP) and neutral water test. [ABSTRACT FROM AUTHOR]

Rhizobium leguminosarum bv. viciae strains expressing different degrees of tolerance to metal stress were used in this work to study the basic mechanisms underlying heavy metal tolerance. We used various parameters to evaluate this response. The strains' growth responses under different Cd2+ concentrations were determined and we reported variation in Cd2+ tolerance. Total soluble protein content decreased drastically, revealing the toxic effects that intracellular Cd2+ imposes on cellular metabolism, but this decrease in protein content was particularly evident in sensitive and moderately tolerant strains. Tolerant strains presented the highest intracellular and wall-bound Cd2+ concentrations. Cd2+ induced increases in the expression of some specific proteins, which were identical in all tolerant strains. Glutathione levels remained unaltered in the sensitive strain and increased significantly in tolerant and moderately tolerant strains, suggesting the importance of glutathione in coping with metal stress. This work suggests that efflux mechanisms may not be the only system responsible for dealing with heavy metal tolerance. A clear correlation between glutathione levels and Cd2+ tolerance is reported, thus adding a novel aspect in bacteria protection against heavy metal deleterious effects. [ABSTRACT FROM AUTHOR]

Bacterial strain 5bvl1, isolated from a chromium-contaminated wastewater treatment plant and identified as Ochrobactrum tritici, was resistant to a broad range of antibiotics, to Cr(VI), Ni(II), Co(II), Cd(II), and Zn(II), and was able to grow in the presence of 5% NaCl and within the pH range 4–10. Characterization showed that strain 5bvl1 could be considered a halotolerant and alkalitolerant microorganism resistant to high concentrations of Cr(VI). This strain was able to grow aerobically in up to 10 mmol·L–1 Cr(VI). Cr(VI) resistance was independent of sulphate concentration. Under aerobic conditions strain 5bvl1 was also able to reduce high Cr(VI) concentrations (up to 1.7 mmol·L–1). Increasing concentrations of Cr(VI) in the medium lowered the growth rate of strain 5bv11 but the reduction in growth rate could not be directly correlated with the amount of Cr(VI) reduced. Unlike the type strain, which was only able to reduce Cr(VI), strain 5bvl1 was resistant to Cr(VI) and able to reduce it. Moreover, in strain 5bvl1, the rate and extent of Cr(VI)-reduction were higher than in the other strains of the genus Ochrobactrum. Ochrobactrum strain 5bvl1 resists high Cr(VI) concentrations and has a high Cr(VI)-reducing ability, making it a valuable tool in bioremediation. [ABSTRACT FROM AUTHOR]

Plant communities in the verges of major roadways (roadsides) are similar to those of abandoned farm fields undergoing succession (oldfields). However, roadsides are subject to distinctive stresses. Here, we look at local adaptation in Hesperis matronalis L. to salinity and manganese (Mn). Plants collected from three roadside and three oldfield populations were grown in a greenhouse under controlled, high-salinity, and high-Mn conditions, and several life history traits were measured. In addition, we imposed a density treatment after vernalization. Mortality was high in both the salt (43% survival) and Mn treatments (53% survival) compared with the control (71% survival). Distinct family, population, and site variation was found in measures of plant size. There were also family-level differences in response to soil treatments. However, none of our results were consistent with local adaptation. In general, larger plants were more likely to bolt, and oldfield plants were less likely to bolt than roadside plants in all treatments (in the low-density treatment, 56% of roadside plants had bolted compared with only 16% of oldfield plants). We found that the high-density treatments resulted in earlier bolting and longer internodes, a result consistent with the shade avoidance hypothesis.Key words: biennial, salinity, phenotypic plasticity, heavy metal, local adaptation.Les communautés végétales en marge des routes principales (bords de route) sont semblables à celles des terres agricoles abandonnées en succession (vieilles prairies). Cependant, les bords de route sont soumis à des stress particuliers. Les auteurs examinent l'adaptation locale de l'Hesperis matronalis L. à la salinité et au manganèse (Mn). Ils ont cultivé en serres, sous des conditions contrôlées impliquant de fortes teneurs en sel et en manganèse, des plantes récoltées sur les bords de trois routes et à partir de trois populations de vieilles prairies, et ont mesuré plusieurs aspects de leur cycle vital. De plus, ils ont imposé un traitement de densité après vernalisation. La mortalité est élevée dans les deux traitements avec le sel (43%) et le Mn (53%), comparativement aux témoins (71%). On observe une variation au niveau de la famille, de la population et du site, dans les mesures des dimensions des plantes. Il y a également des différences au niveau de la famille en réaction aux traitements du sol. Cependant, aucun des résultats n'est congru avec une adaptation locale. En général, les grandes plantes sont plus susceptibles de monter en graines, et les plantes de vieilles prairies sont moins susceptibles de le faire que les plantes des bords de route, quel que soit le traitement (dans le traitement à faible densité, 56% des plantes de bords de route ont monté à la graine, comparativement à seulement 16% pour les plantes de vieilles prairies). On constate que les traitements à haute densité conduisent à une montée en graines plus hâtive et des entrenoeuds plus longs, un résultat qui concorde avec l'hypothèse d'intolérance à l'ombre.Mots clés : bisannuel, salinité, plasticité phénotypique, métal lourd, adaptation locale.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

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Although chemical measurement techniques and geochemical speciation modelling may detect and predict the different forms of copper in aquatic systems and hence provide some information about the likely toxicity of the water to aquatic organisms, they do not give direct quantitative data on adverse biological effects. Bioassays or toxicity tests are generic tests that use living organisms as indicators of contaminant bioavailability in aquatic systems. The microbial community, including protozoa, algae, bacteria, and fungi, provides a useful toolfor directly assessing the hazard of copper in natural ecosystems. Most of our information on copper toxicity in aquatic systems comes from single-species tests using cultured organisms. However, whole community bioassays with natural phytoplankton and bacterial populations are finding increasing use. Although laboratory toxicity tests using ionic copper spiked into pristine seawater or synthetic softwater provide information on copper toxicity under controlled conditions, their usefulness for estimating bioavailable copper is limited in naturalwaters, where copper toxicity is ameliorated by complexation and adsorption. Careful selection of appropriately sensitive test species, bioassay endpoints, and test protocols is necessary to ensure the environmental relevance of the bioassays used. An understanding of metal speciation, metal-cell binding, mechanisms of toxicity, and limitations of the bioassays is required to understand copper bioavailability in natural waters and sediments. In this review, the use of bioassayswith bacteria and microalgae for assessing copper bioavailability inmarine and fresh waters and sediments is discussed, with particular emphasis on the limitations of current techniques. There is an urgentneed for more environmentally relevant tests with sufficient sensitivity to detect bioavailable copper at concentrations close to water and sediment quality guideline values. [ABSTRACT FROM AUTHOR]

A literature review is given of atmospheric trace metal concentrations in aerosols above the North Sea and the English Channel over the period 1971-1994. Literature data have been gathered and intercomparedto look for possible trends in the reported concentrations. Six trace metals are considered: Cd, Cu, Pb, Zn, Ni, and Cr. A distinction ismade between measurements in different regions of the North Sea, andbetween coastal and marine areas. The majority of the data deals with the Southern Bight, providing the most reliable trends. Strong decreasing trends are observed for the Pb and Zn concentrations above theNorth Sea during the years 1971-1994. For Cd, Cu, Ni, and Cr, much less data are available in the literature. Despite this, also for Cd and Cu a decreasing trend is present. Cr and Ni concentrations are fluctuating, mostly without a certain pattern. The trends in the concentrations are also compared to changes in the European emission profiles. [ABSTRACT FROM AUTHOR]

This survey represents a review of current knowledge concerning nickel and its compounds in the Finnish environment. Nickel, a naturally occurring element, is ubiquitous in the environment, especially in the divalent state. It was identified in the middle of the 18th centuryand its extraction process developed in the middle of the 19th century. In Finland, primary nickel production takes place by the direct high-grade nickel matte flash smelting process. Domestic production ofnickel increased from 16 900 t in 1990 to 35 285 t in 1997. As a result of its versatile properties, more than 300 000 end-use applications of nickel have been reported. Its major use in Finland is in the production of stainless steel. In 1996 the release of nickel from industrial sources in Finland was as follows: 47 t to the atmosphere, 19 t to the aquatic environment, and 150 t to landfills and soils. The highest emissions stemmed from fuel-fired utility boilers. Nickel emissions to the atmosphere from the Harjavalta nickel smelter decreased from 7 t in 1993 to 1.2 t in 1996 as a result of technological developments and better gas cleaning equipment. In this study, nickel in the air, stream waters, soils, and lake and river sediments have been examined. It is noted that the background concentration of nickel in the air is about 0.5 ng7m-3, and nickel in stream water varies from 0.14 to 4.0 mug7L-1. There was no significant change of nickel concentration in arable lands between 1974 and 1987. Inaddition, nickel concentrations in terrestrial and aquatic species in Finland have been touched upon. [ABSTRACT FROM AUTHOR]

Dendrochemical techniques have been used to monitor historical changes in soil and atmospheric chemistry since the early 1970s. The development of dendrochemistry in environmental monitoring was prompted byearly studies which reported that changes in Pb deposition along roadsides and in industrial areas were reflected by changes in the Pb content of tree rings. Early studies were inconclusive; some authors have stated that tree-ring chemistry is not a useful indicator of pollution episodes and that some tree species are clearly better spatial indicators of pollution than historical monitors. This is due to a number of complicating factors, including potential radial translocationof elements, radial tendencies in element concentration from pith tobark, and physiological differences between heartwood and sapwood. Amore detailed understanding of element cycling in trees is needed, as at present, the application of dendrochemistry to historical environmental monitoring is strongly dependent on the choice of tree species and the elements to be studied. There is no general consensus as towhich tree species are best suited for dendrochemical studies. Thereare many reports in which the analyses of tree-ring chemistry have been successfully used to reconstruct trace-metal deposition from a variety of sources, including automobiles, metal refineries, and coal burning. Changes in tree-ring chemistry in recent decades have coincided with hypothesized changes in soil chemistry believed to be a result of acidic deposition onto poorly buffered soils. Indications of changes in groundwater quality, volcanic eruptions, and even climate change have been reported to be preserved in the chemical composition oftree rings. An improvement in analytical techniques has allowed multielement analysis on whole wood samples, with very low detection limits and extremely high spatial resolution, enabling intra-annual changes in element composition of tree rings to be determined. The application of [ABSTRACT FROM AUTHOR]

The response of red maple (Acer rubrum L.) to elevated heavy metal concentrations in surface soil, arising from either atmospheric deposition or mining activities, was investigated using callus tissue studies. Callus cell lines were established from shoot tips of mature red maple growing at sites in rural and industrial locations in Ontario and Quebec differing in metal contamination. At Sudbury and Rouyn-Noranda, the trees were stunted and were established before smelting operations began. Surface soil in the rooting zone of many of the trees in the industrial areas was heavily contaminated with metals, and large differences in soil metal concentration at the bases of different trees were found. A significant positive linear relationship between Ni resistance, measured as an increase in fresh weight of callus on Ni- amended media, and total extractable Ni in soil at the base of trees was identified. Resistance to Ag and Co was also significantly greater in cell lines established from trees growing in soils containing highly elevated concentrations of these metals. It appears that red maple is able to produce an adaptive response to metal exposure which is identified in cells derived from shoot tips. This metal-specific, adaptive response may be particularly crucial for the survival of trees to rapid environmental changes. [ABSTRACT FROM AUTHOR]