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Changes in susceptibility of beech (Fagus sylvatica) seedlings towards Phytophthora citricola under the influence of elevated atmospheric CO2 and nitrogen fertilization Texte intégral
2010
Fleischmann, F. | Raidl, S. | Oßwald, W.F.
The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO2- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO2-treatment, whereas elevated CO2 enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO2 and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root–shoot ratios, and by enhanced specific root tip densities. Susceptibility of Fagus sylvatica to the root pathogen Phytophthora citricola increased under elevated CO2
Afficher plus [+] Moins [-]Mercury transport between sediments and the overlying water of the St. Lawrence River area of concern near Cornwall, Ontario Texte intégral
2010
Delongchamp, Tania M. | Ridal, Jeffrey J. | Lean, David R.S. | Poissant, Laurier | Blais, Jules M.
Contaminated sediments in the St. Lawrence River remain a difficult problem despite decreases in emissions. Here, sediment and pore water phases were analyzed for total mercury (THg) and methyl mercury (MeHg) and diffusion from the sediment to the overlying water was 17.5 ± 10.6 SE ng cm−2 yr−1 for THg and 3.8 ± 1.7 SE ng cm−2 yr−1 for MeHg. These fluxes were very small when compared to the particle-bound mercury flux accumulating in the sediment (183 ± 30 SE ng cm−2 yr−1). Studies have reported that fish from the westernmost site have higher Hg concentrations than fish collected from the other two sites of the Cornwall Area of Concern, which could not be explained by differences in the Hg flux or THg concentrations in sediments, but the highest concentrations of sediment MeHg, and the greatest proportions of MeHg to THg in both sediment and pore water were observed where fish had highest MeHg concentrations.
Afficher plus [+] Moins [-]Chemical fluxes in time through forest ecosystems in the UK - Soil response to pollution recovery Texte intégral
2010
Vanguelova, E.I. | Benham, S. | Pitman, R. | Moffat, A.J. | Broadmeadow, M. | Nisbet, T. | Durrant, D. | Barsoum, N. | Wilkinson, M. | Bochereau, F. | Hutchings, T. | Broadmeadow, S. | Crow, P. | Taylor, P. | Houston, T Durrant
Long term trend analysis of bulk precipitation, throughfall and soil solution elemental fluxes from 12 years monitoring at 10 ICP Level II forest sites in the UK reveal coherent national chemical trends indicating recovery from sulphur deposition and acidification. Soil solution pH increased and sulphate and aluminium decreased at most sites. Trends in nitrogen were variable and dependant on its form. Dissolved organic nitrogen increased in bulk precipitation, throughfall and soil solution at most sites. Nitrate in soil solution declined at sites receiving high nitrogen deposition. Increase in soil dissolved organic carbon was detected - a response to pollution recovery, changes in soil temperature and/or increased microbial activity. An increase of sodium and chloride was evident - a possible result of more frequent storm events at exposed sites. The intensive and integrated nature of monitoring enables the relationships between climate/pollutant exposure and chemical/biological response in forestry to be explored.
Afficher plus [+] Moins [-]Relationship between heavy metals pollution and genetic diversity in Mediterranean populations of the sandhopper Talitrus saltator (Montagu) (Crustacea, Amphipoda) Texte intégral
2010
Ungherese, G. | Mengoni, A. | Somigli, S. | Baroni, D. | Focardi, S. | Ugolini, A.
Trace metals are one of the groups of pollutants that reduce genetic variability in natural populations, causing the phenomenon known as "genetic erosion". In this study we evaluate the relationship between trace metals contamination (Hg, Cd and Cu) and genetic variability, assessed using fluorescent Inter-Simple Sequence Repeats (fISSRs). We used eight populations of a well-established biomonitor of trace metals on sandy beaches: the amphipod Talitrus saltator. The trace metals analysis confirmed the ability of sandhoppers to accumulate Hg, Cd and Cu. Moreover, populations from sites with high Hg availability had the lowest values of genetic diversity. Our results validate the use of fISSR markers in genetic studies in sandhoppers and support the "genetic erosion" hypothesis by showing the negative influence of Hg contamination on sandhopper genetic diversity. Therefore, genetic variability assessed with fISSR markers could be successfully employed as a biomarker of Hg exposure.
Afficher plus [+] Moins [-]Tissue S/N ratios and stable isotopes (δ34S and δ15N) of epilithic mosses (Haplocladium microphyllum) for showing air pollution in urban cities in Southern China Texte intégral
2010
Xiao, Hua-Yun | Tang, Cong-Guo | Xiao, Hong-Wei | Wang, Yan-Li | Liu, Xue-Yan | Liu, Cong-Qiang
In urban cities in Southern China, the tissue S/N ratios of epilithic mosses (Haplocladium microphyllum), varied widely from 0.11 to 0.19, are strongly related to some atmospheric chemical parameters (e.g. rainwater SO42−/NH4+ ratios, each people SO2 emission). If tissue S/N ratios in the healthy moss species tend to maintain a constant ratio of 0.15 in unpolluted area, our study cities can be divided into two classes: class I (S/N > 0.15, S excess) and class II (S/N < 0.15, N excess), possibly indicative of stronger industrial activity and higher density of population, respectively. Mosses in all these cities obtained S and N from rainwater at a similar ratio. Sulphur and N isotope ratios in mosses are found significantly linearly correlated with local coal δ34S and NH4+–N wet deposition, respectively, indicating that local coal and animal NH3 are the major atmospheric S and N sources.
Afficher plus [+] Moins [-]The rhizosphere and PAH amendment mediate impacts on functional and structural bacterial diversity in sandy peat soil Texte intégral
2010
Yrjälä, Kim | Keskinen, Anna-Kaisa | Akerman, Marja-Leena | Fortelius, Carola | Sipilä, Timo P.
The rhizosphere and PAH amendment mediate impacts on functional and structural bacterial diversity in sandy peat soil Texte intégral
2010
Yrjälä, Kim | Keskinen, Anna-Kaisa | Akerman, Marja-Leena | Fortelius, Carola | Sipilä, Timo P.
To reveal the degradation capacity of bacteria in PAH polluted soil and rhizosphere we combined bacterial extradiol ring-cleavage dioxygenase and 16S rRNA analysis in Betula pubescens rhizoremediation. Characterisation of the functional bacterial community by RFLP revealed novel environmental dioxygenases, and their putative hosts were studied by 16S rRNA amplification. Plant rhizosphere and PAH amendment effects were detected by the RFLP/T-RFLP analysis. Functional species richness increased in the birch rhizosphere and PAH amendment impacted the compositional diversity of the dioxygenases and the structural 16S rRNA community. A shift from an Acidobacteria and Verrucomicrobia dominated to an Alpha- and Betaproteobacteria dominated community structure was detected in polluted soil. Clone sequence analysis indicated catabolic significance of Burkholderia in PAH polluted soil. These results advance our understanding of rhizoremediation and unveil the extent of uncharacterized functional bacteria to benefit bioremediation by facilitating the development of the molecular tool box to monitor bacterial populations in biodegradation.
Afficher plus [+] Moins [-]The rhizosphere and PAH amendment mediate impacts on functional and structural bacterial diversity in sandy peat soil Texte intégral
2010 | 2011
Yrjälä, Kim | Keskinen, Anna-Kaisa | Åkerman, Marja-Leena | Fortelius, Carola | Sipilä, Timo P. | University of Helsinki | Metropolia | Metropolia | Metropolia | University of Helsinki
v | ok | MAA
Afficher plus [+] Moins [-]Perfluorinated compounds in water, sediment, soil and biota from estuarine and coastal areas of Korea Texte intégral
2010
Naile, Jonathan E. | Khim, Jong Seong | Wang, Tieyu | Chen, Chunli | Luo, Wei | Kwon, Bong-Oh | Park, Jinsoon | Ko, Chʻŏr-hwan | Jones, Paul D. | Lü, Yonglong | Giesy, John P.
Soil, sediment, water, and biota collected from the western coast of Korea were analyzed to determine occurrence and sources of perfluorinated compounds (PFCs). PFCs were significantly concentrations of PFCs were measured in some water and biological samples, while concentrations of PFCs in soils and sediments were relatively low. The most widely detected compound was found to be perfluorooctanesulfonate (PFOS), with a maximum concentration in water of 450 ng/L and in fish of 612 ng/g, dw. PFOS concentrations in water and biota were both less than those thought to cause toxicity. However, in both cases concentrations were within a factor of 10 of the toxicity threshold concentration. Concentrations of PFCs were significantly greater downstream than those upstream on the same river, suggesting point sources. Overall, the detection of PFCs at relatively great concentrations in various environmental matrixes from this region of Korea suggests that further studies characterizing PFCs and their potential risk to both humans and wildlife are needed.
Afficher plus [+] Moins [-]Effects of amendments on the uptake and distribution of DDT in Cucurbita pepo ssp pepo plants Texte intégral
2010
Åslund, Melissa L Whitfield | Lunney, Alissa I. | Rutter, Allison | Zeeb, Barbara A.
The effects of soil amendments on the phytoextraction of ∑DDT (DDT + DDD + DDE) from soil ([∑DDT] not, vert, similar 1500 ng/g) by a pumpkin variety of Cucurbita pepo ssp pepo were tested and the patterns of ∑DDT storage throughout the plant shoot were examined. The soil amendments did not increase the total amount of ∑DDT extracted into plant shoots, but new information about ∑DDT distribution in the plants was obtained. As observed previously, the ∑DDT concentration in plant leaves (mean 290 ng/g) was significantly lower than in plant stems (mean 2600 ng/g). Further analysis revealed that ∑DDT composition was consistent throughout the plant shoot and that ∑DDT concentration in leaves and stems decreased exponentially as distance from the root increased, which was previously unknown. This new information about the patterns of ∑DDT uptake and translocation within pumpkin plants highlights the need for appropriate plant sampling strategies in future POPs phytoextraction research. Patterns of ∑DDT storage in a pumpkin plant are elucidated and specific surfactant and mycorrhizal soil amendments did not increase the total amount of ∑DDT phytoextracted into plant shoots.
Afficher plus [+] Moins [-]Pb isotopes as tracers of mining-related Pb in lichens, seaweed and mussels near a former Pb-Zn mine in West Greenland Texte intégral
2010
Søndergaard, Jens | Asmund, Gert | Johansen, Poul | Elberling, Bo
Identification of mining-related contaminants is important in order to assess the spreading of contaminants from mining as well as for site remediation purposes. This study focuses on lead (Pb) contamination in biota near the abandoned ‘Black Angel Mine’ in West Greenland in the period 1988-2008. Stable Pb isotope ratios and total Pb concentrations were determined in lichens, seaweed and mussels as well as in marine sediments. The results show that natural background Pb (207Pb/206Pb: 0.704-0.767) and Pb originating from the mine ore (207Pb/206Pb: 0.955) have distinct isotopic fingerprints. Total Pb in lichens, seaweed, and mussels was measured at values up to 633, 19 and 1536 mg kg-1 dry weight, respectively, and is shown to be a mixture of natural Pb and ore-Pb. This enables quantification of mining-related Pb and shows that application of Pb isotope data is a valuable tool for monitoring mining pollution.
Afficher plus [+] Moins [-]Current status of agricultural and rural non-point source Pollution assessment in China Texte intégral
2010
Ongley, E. D. | Xiaolan, Zhang | Tao, Yu
Estimates of non-point source (NPS) contribution to total water pollution in China range up to 81% for nitrogen and to 93% for phosphorus. We believe these values are too high, reflecting (a) misuse of estimation techniques that were developed in America under very different conditions and (b) lack of specificity on what is included as NPS. We compare primary methods used for NPS estimation in China with their use in America. Two observations are especially notable: empirical research is limited and does not provide an adequate basis for calibrating models nor for deriving export coefficients; the Chinese agricultural situation is so different than that of the United States that empirical data produced in America, as a basis for applying estimation techniques to rural NPS in China, often do not apply. We propose a set of national research and policy initiatives for future NPS research in China.
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