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Preferential retention of POPs on the northern aspect of mountains Texto completo
2009
Tremolada, Paolo | Parolini, Marco | Binelli, Andrea | Ballabio, Cristiano | Comolli, Roberto | Provini, Alfredo
Soils are the main reservoirs of POPs in mountain ecosystems, but the great variability of the concentrations, also at small scale, leaves some uncertainties in the evaluation of environmental burdens and exposure. The role of the aspect of the mountain side and the seasonal variation in the contamination levels was analysed by means of several soil samples taken from central Italian Alps. A greater contamination content was present in northern soils with a mean ratio between the north vs. south normalised concentration of around a factor of 2 (North–South Enrichment Factor). Experimental factors agreed with theoretical calculations based on temperature-specific calculated Ksa values. From May to November consistent differences in normalised concentrations up to 5-fold were observed. A dynamic picture of the POP contamination in high altitudinal soils is derived from the data in this work, with spring-summer half-lives between 60 and 120 days for most of the compounds. This paper discusses the accumulation of POPs in soils in relation to the aspect of the mountain side and supports the idea of a seasonal cycle of POPs in this matrix.
Mostrar más [+] Menos [-]Origin of polluted air masses in the Alps. An overview and first results for MONARPOP Texto completo
2009
Kaiser, August
The contribution of ZAMG to MONAROP consists of special weather forecasts to control the SOCs sampling procedure and of the analysis of the specific transport processes for SOCs, which is still in progress. In this paper, air pollutant transport into the Alps is demonstrated by examples of inorganic pollutants: Measurements of NOx and ozone provide evidence for air pollutant transport by local wind systems (valley and slope winds), especially at low elevated sites of the Alps. In addition, trajectory analyses for the high elevation sites demonstrate the importance of large scale synoptic air pollutant transport. The effects of these transport processes with different spatial and temporal scales are governed by the physical and chemical properties of the particular pollutant. First results for the high alpine MONARPOP stations show that air masses from east Europe influence mostly Sonnblick (Austria), whereas the influence of the Po basin is strongest at Weissfluhjoch (Switzerland). Effects of meteorological transport processes on air pollution in the Alps are demonstrated by examples of inorganic pollutants and first conclusions for SOCs are drawn.
Mostrar más [+] Menos [-]Sediment processes and mercury transport in a frozen freshwater fluvial lake (Lake St. Louis, QC, Canada) Texto completo
2009
Canário, João | Poissant, Laurier | O'Driscoll, Nelson | Vale, Carlos | Pilote, Martin | Lean, D. R. S. (David R. S)
An open-bottom and a closed-bottom mesocosm were developed to investigate the release of mercury from sediments to the water column in a frozen freshwater lake. The mesoscosms were deployed in a hole in the ice and particulate mercury (HgP) and total dissolved mercury (TDHg) were measured in sediments and in water column vertical profiles. In addition, dissolved gaseous mercury (DGM) in water and mercury water/airflux were quantified. Concentrations of TDHg, DGM, and mercury flux were all higher in the open-bottom mesocosm than in the closed-bottom mesocosm. In this paper we focus on the molecular diffusion of mercury from the sediment in comparison with the TDHg accumulation in the water column. We conclude that the molecular diffusion and sediment resuspension play a minor role in mercury release from sediments suggesting that solute release during ebullition is an important transport process for mercury in the lake. In a frozen lake Hg is released from contaminated sediments mainly due to gas ebullition and molecular diffusion plays a minor role.
Mostrar más [+] Menos [-]Compatibility of hydroxypropyl-β-cyclodextrin with algal toxicity bioassays Texto completo
2009
Fai, Patricia Bi | Grant, Alastair | Reid, Brian J.
Numerous reports have indicated that hydrophobic organic compound bioaccessibility in sediment and soil can be determined by extraction using aqueous hydroxypropyl-β-cyclodextrin (HPCD) solutions. This study establishes the compatibility of HPCD with Selenastrum capricornutum and assesses whether its presence influences the toxicity of reference toxicants. Algal growth inhibition (72 h) showed no significant (P > 0.05) difference at HPCD concentrations up to and including 20 mM. HPCD presence did not influence the toxicity of the inorganic reference toxicant (ZnSO4), with IC50 values of 0.82 μM and 0.85 μM, in the presence and absence of HPCD (20 mM), respectively. However, HPCD presence (20 mM) reduced the toxicity of 2,4-dichlorophenol and the herbicides diuron and isoproturon. These reductions were attributed to inclusion complex formation between the toxicants and the HPCD cavity. Liberation of complexed toxicants, by sample manipulation prior to toxicity assessment, is proposed to provide a sensitive, high throughput, bioassay that reflects compound bioaccessibility. Compatibility of the biomimetic HPCD extraction method with algal cell growth inhibition bioassays to assess toxicity of reference toxicants and environmental relevant herbicides.
Mostrar más [+] Menos [-]Sorption behavior of bensulfuron-methyl on andisols and ultisols volcanic ash-derived soils: Contribution of humic fractions and mineral–organic complexes Texto completo
2009
Espinoza, Jeannette | Fuentes, Edwar | Báez, Maria E.
Bensulfuron-methyl sorption was studied in Andisol and Ultisol soils in view of their characteristic physical and chemical properties, presenting acidic pH and variable charge. Humic and fulvic acids (HA and FA) and humin (HUM) contributions were established. Sorption was studied by using two synthetic sorbents, an aluminum-silicate with iron oxide coverage and the same sorbent coated with humic acid. Freundlich model described Bensulfuron-methyl behavior in all sorbents (R2 0.969–0.998). Kf for soils (8.3–20.7 μg1−1/n mL1/n g−1) were higher than those reported in the literature. Organic matter, halloysite or kaolinite, and specific surface area contributed to the global process. The highest Kf for HA, FA and HUM were 539.5, 82.9, and 98.7 μg1−1/n mL1/n g−1. Model sorbents described the participation of variable charge materials with high adsorption capacity. The constant capacitance model was used to assess effects of Bensulfuron-methyl adsorption on the distribution of SOH, SOH2+ and SO− sites of sorbents. Organic matter, phyllosilicates, variable charge minerals and organo-mineral complexes contribute to bensulfuron-methyl sorption on volcanic ash-derived soils.
Mostrar más [+] Menos [-]Plant cell death and cellular alterations induced by ozone: Key studies in Mediterranean conditions Texto completo
2009
Faoro, Franco | Iriti, Marcello
An account of histo-cytological and ultrastructural studies on ozone effect on crop and forest species in Italy is given, with emphasis on induced cell death and the underlying mechanisms. Cell death phenomena possibly due to ambient O3 were recorded in crop and forest species. In contrast, visible O3 effects on Mediterranean vegetation are often unclear. Microscopy is thus suggested as an effective tool to validate and evaluate O3 injury to Mediterranean vegetation. A DAB-Evans blue staining was proposed to validate O3 symptoms at the microscopic level and for a pre-visual diagnosis of O3 injury. The method has been positively tested in some of the most important crop species, such as wheat, tomato, bean and onion and, with some restriction, in forest species, and it also allows one to gain some very useful insights into the mechanisms at the base of O3 sensitivity or tolerance. Ozone-induced cell death is a frequent phenomenon in Mediterranean conditions, not only in the most sensitive crops but also in forest species.
Mostrar más [+] Menos [-]Heavy metal contamination in surface sediments of Yangtze River intertidal zone: An assessment from different indexes Texto completo
2009
Zhang, Weiguo | Feng, Huan | Chang, Jinna | Qu, Jianguo | Xie, Hongxia | Yu, Lizhong
Surface sediments (0-5 cm) from 59 stations within the Yangtze River intertidal zone (YRIZ) were sampled for metal contamination analysis in April and August 2005. The concentrations ranged (in mg kg-¹ dry weight): Al, 40,803-97,213; Fe, 20,538-49,627; Cd, 0.12-0.75; Cr, 36.9-173; Cu, 6.87-49.7; Mn, 413-1,112; Ni, 17.6-48.0; Pb, 18.3-44.1; and Zn, 47.6-154; respectively. Among the 59 sampling stations, enrichment factors (EF) indicate enrichment of Cd (52 stations), Cr (54 stations), Cu (5 stations), Ni (26 stations), Pb (5 stations) and Zn (5 stations). Geoaccumulation indexes (Igeo) also suggest individual metal contamination in localized areas. This study indicates that Cd, Cr and Ni enrichment in the YRIZ sediment is widespread whereas Cu, Mn, Pb and Zn enrichment is localized or nonexistent. Factor and cluster analyses indicate that Cd is associated with total organic carbon whereas Cu, Cr, Ni, Pb and Zn have a close association with Mn. Surface sediment metal enrichment is evidenced for Cd, Cr and Ni in the Yangtze River intertidal zone.
Mostrar más [+] Menos [-]Chelating agent-assisted electrokinetic removal of cadmium, lead and copper from contaminated soils Texto completo
2009
Giannis, Apostolos | Nikolaou, Aris | Pentari, Despina | Gidarakos, Evangelos
An integrated experimental program was conducted to remove Cd, Pb and Cu from contaminated soil. The chelate agents nitrilotriacetic acid (NTA), diethylenetriamine pentaacetic acid (DTPA) and ethyleneglycol tetraacetic acid (EGTA) were used as washing solutions under different pH conditions and concentrations. Results showed that the extraction efficiency for Cd in decreasing order was NTA > EGTA > DTPA, while for Pb and Cu it was DTPA > NTA > EGTA. The use of higher chelate concentrations did not necessarily result in greater extraction efficiency. Electrokinetic remediation was applied by conditioning anolyte–catholyte pH to neutral values in order to avoid any potential alterations to the physicochemical soil properties. The removal efficiency for Cd was 65–95%, for Cu 15–60%, but for Pb was less than 20%. The phytotoxicity of the treated soil showed that the soil samples from the anode section were less phytotoxic than the untreated soil, but the phytotoxicity was increased in the samples from the cathode section. Cadmium, lead and copper were extracted from contaminated soil by integrated electrokinetic and soil washing studies.
Mostrar más [+] Menos [-]Equilibrium partitioning theory to predict the sediment toxicity of the anionic surfactant C12-2-LAS to Corophium volutator Texto completo
2009
Rico-Rico, Angeles | Temara, Ali | Hermens, Joop L.M.
The study of the effect of the sorption of linear alkylbenzene sulfonates (LAS) on the bioavailability to marine benthic organisms is essential to refine the environmental risk assessment of these compounds. According to the equilibrium partitioning theory (EqP), the effect concentration in water-only exposure will be similar to the effect concentration in the sediment pore water. In this work, sorption and desorption experiments with two marine sediments were carried out using the compound C12-2-LAS. The effect of the sediment sorption on the toxicity of benthic organisms was studied in water-only and in sediment bioassays with the marine mud shrimp Corophium volutator. In addition, three common spiking methods were tested for its application in the toxicity tests, as well as the stability of the surfactant during the water-only and sediment-water test duration. LC50 values obtained from water-only exposure showed a good correspondence with the pore water concentrations calculated from the sorption and desorption isotherms in the spiked sediments.
Mostrar más [+] Menos [-]Microbial transformation of synthetic estrogen 17α-ethinylestradiol Texto completo
2009
Cajthaml, Tomáš | Křesinová, Zdena | Svobodová, Kateřina | Sigler, Karei | Řezanka, Tomáš
Natural estrogens such as estrone, 17β-estradiol, estriol, and the particularly recalcitrant synthetic estrogen 17α-ethinylestradiol used as oral contraceptive, accumulate in the environment and may give rise to health problems. The processes participating in their removal from soil, wastewater, water-sediments, groundwater-aquifer material, and wastewater or sewage treatment plant effluents may involve the action of bacterial and microbial consortia, and in some cases fungi and algae. This review discusses the different efficiencies of bacterial degradation of 17α-ethinylestradiol under aerobic and anaerobic conditions, the role of sulfate-, nitrate-, and iron-reducing conditions in anaerobic degradation, and the role of sorption. The participation of autotrophic ammonia oxidizing bacteria and heterotrophic bacteria in cometabolic degradation of estrogens, the estrogen-degrading action of ligninolytic fungi and their extracellular enzymes (lignin peroxidase, manganese-dependent peroxidase, versatile peroxidase, laccase), and of algae are discussed in detail. Current knowledge of 17α-ethinylestradiol microbial transformation is summarized.
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