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Résultats 231-240 de 2,459
Soil physical characteristics after EDTA washing and amendment with inorganic and organic additives
2014
Zupanc, Vesna | Kastelec, Damijana | Lestan, Domen | Grcman, Helena
Soil washing has been established as suitable remediation technology, with most research focused on metal removing efficiency and toxic effect on plants, less on the influence on soil physical characteristics, which was the focus of this study. In soil column experiment highly contaminated soil and soil washed with EDTA, mixed with additives (gypsum, hydrogel, manure, peat) were tested. White clover was used as a soil cover. Yield, metal concentration in soil and plant, aggregate fractionation and stability, saturated hydraulic conductivity and soil water retention of the soil were measured. Soil washing decreased metal concentration in soil and plants, but yield of white clover on remediated soil was significantly lower compared to the original soil. Significant differences in water retention characteristics, aggregate fractionation and stability between original and remediated soil have been determined. Gypsum, hydrogel and peat increased plant available water, manure and peat increased yield on remediated soil.
Afficher plus [+] Moins [-]Passive sampling: An effective method for monitoring seasonal and spatial variability of dissolved hydrophobic organic contaminants and metals in the Danube river
2014
Vrana, Branislav | Klučárová, Veronika | Benická, Eva | Abou-Mrad, Ninette | Amdany, Robert | Horáková, Soňa | Draxler, Astrid | Humer, Franko | Gans, Oliver
Application of passive samplers is demonstrated for assessment of temporal and spatial trends of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and priority metals in the middle stretch of the Danube river. Free dissolved concentrations of PAHs, measured using SPMD samplers, ranged from 5 to 72 ng L−1. Dissolved PCBs in water were very low and they ranged from 5 to 16 pg L−1. Concentration of mercury, cadmium, lead and nickel, measured using DGT samplers, were relatively constant along the monitored Danube stretch and in the range <0.1, <1–20, 18–74, and 173–544 ng L−1, respectively. Concentrations of PAHs decreased with increasing temperature, which reflects the seasonality in emissions to water. This has an implication for the design of future monitoring programs aimed at assessment of long term trends. For such analysis time series should be constructed of data from samples collected always in the same season of the year.
Afficher plus [+] Moins [-]Occurrence of phthalic acid esters in source waters: a nationwide survey in China during the period of 2009–2012
2014
Liu, Xiaowei | Shi, Jianghong | Bo, Ting | Zhang, Hui | Wu, Wei | Chen, Qingcai | Zhan, Xinmin
The first nationwide survey of six phthalic acid esters (PAEs) (diethyl phthalate (DEP); dimethyl phthalate (DMP); di-n-butyl phthalate (DBP); butyl benzyl phthalate (BBP); bis(2-ethylhexyl) phthalate (DEHP); di-n-octyl phthalate (DnOP)) in source waters was conducted in China. The results showed these PAEs were ubiquitous in source waters. DBP and DEHP were the most frequently detected with high concentrations ranging nd–1.52 μg/L and nd–6.35 μg/L, respectively. These PAEs concentrations (except DBP) in surface water (rivers, lakes and reservoirs) were generally higher than those in groundwater; DBP had high concentrations in groundwater in Northeast China (Liao River Basin) and North China (Hai River Basin). Their concentrations in the northern regions were generally higher than those in the southern and eastern regions; particularly, in North China. Three short-chain PAEs (DMP, DEP and DBP) were detected with high concentrations in Hai River Basin, Pearl River Basin and Yellow River Basin.
Afficher plus [+] Moins [-]Response of detoxification gene mRNA expression and selection of molecular biomarkers in the clam Ruditapes philippinarum exposed to benzo[a]pyrene
2014
Liu, Dong | Pan, Luqing | Cai, Yuefeng | Li, Zhen | Miao, Jingjing
Benzo[a]pyrene (B[a]P) has a high carcinogenic potential. B[a]P concentrations and molecular biomarkers (mRNA expressions of Pgp, AhR, CYP4, CYP414A1, GST-pi, GST-S2, Cu/Zn-SOD and Mn-SOD) were assayed in gills and digestive glands of the clam Ruditapes philippinarum exposed to 0.03, 0.3 and 3 μg/L B[a]P for 21 days and then exposed to natural seawater for 15 days. Results showed that B[a]P was rapidly accumulated in and then eliminated from tissues of the clams. All gene mRNA expressions in the treated groups were induced significantly with the exception of CYP414A1 and Cu/Zn-SOD in the 0.03 μg/L B[a]P group. According to correlation analysis, mRNA expressions of AhR, GST-pi and Mn-SOD in gills and GST-pi in digestive glands had good correlations with B[a]P concentrations and could be used as molecular biomarkers of B[a]P exposure. This study investigated the molecular response of the genes mentioned above and selected useful molecular biomarkers for B[a]P pollution monitoring.
Afficher plus [+] Moins [-]Investigating the need for complex vs. simple scenarios to improve predictions of aquatic ecosystem exposure with the SoilPlus model
2014
Ghirardello, Davide | Morselli, Melissa | Otto, Stefan | Zanin, Giuseppe | Di Guardo, Antonio
A spatially-explicit version of the recent multimedia fate model SoilPlus was developed and applied to predict the runoff of three pesticides in a small agricultural watershed in north-eastern Italy. In order to evaluate model response to increasing spatial resolution, a tiered simulation approach was adopted, also using a dynamic model for surface water (DynA model), to predict the fate of pesticides in runoff water and sediment, and concentrations in river water. Simulation outputs were compared to water concentrations measured in the basin. Results showed that a high spatial resolution and scenario complexity improved model predictions of metolachlor and terbuthylazine in runoff to an acceptable performance (R2 = 0.64–0.70). The importance was also shown of a field-based database of properties (i.e. soil texture and organic carbon, rainfall and water flow, pesticides half-life in soil) in reducing the distance between predicted and measured surface water concentrations and its relevance for risk assessment.
Afficher plus [+] Moins [-]Identification of lead sources in residential environments: Sydney Australia
2014
Laidlaw, M.A.S. | Zahran, S. | Pingitore, N. | Clague, J. | Devlin, G. | Taylor, M.P.
Interior and exterior dust, soil and paint were analysed at five brick urban Sydney homes over 15 months to evaluate temporal variations and discriminate sources of lead (Pb) exposure. Exterior dust gauge Pb loading rates (μg/m2/28 days), interior vacuum dust Pb concentrations (mg/kg) and interior petri-dish Pb loading rates (μg/m2/28 days), were correlated positively with soil Pb concentrations. Exterior dust gauge Pb loading rates and interior vacuum dust Pb concentrations peaked in the summer. Lead isotope and Pb speciation (XAS) were analysed in soil and vacuum dust samples from three of the five houses that had elevated Pb concentrations. Results show that the source of interior dust lead was primarily from soil in two of the three houses and from soil and Pb paint in the third home. IEUBK child blood Pb modelling predicts that children's blood Pb levels could exceed 5 μg/dL in two of the five houses.
Afficher plus [+] Moins [-]Bacterial metal resistance genes and metal bioavailability in contaminated sediments
2014
Roosa, Stéphanie | Wattiez, Ruddy | Prygiel, Emilie | Lesven, Ludovic | Billon, Gabriel | Gillan, David C.
In bacteria a metal may be defined as bioavailable if it crosses the cytoplasmic membrane to reach the cytoplasm. Once inside the cell, specific metal resistance systems may be triggered. In this research, specific metal resistance genes were used to estimate metal bioavailability in sediment microbial communities. Gene levels were measured by quantitative PCR and correlated to metals in sediments using five different protocols to estimate dissolved, particle-adsorbed and occluded metals. The best correlations were obtained with czcA (a Cd/Zn/Co efflux pump) and Cd/Zn adsorbed or occluded in particles. Only adsorbed Co was correlated to czcA levels. We concluded that the measurement of czcA gene levels by quantitative PCR is a promising tool which may complement the classical approaches used to estimate Cd/Zn/Co bioavailability in sediment compartments.
Afficher plus [+] Moins [-]Effects of oil dispersant and oil on sorption and desorption of phenanthrene with Gulf Coast marine sediments
2014
Gong, Yanyan | Zhao, Xiao | O'Reilly, S.E. | Qian, Tianwei | Zhao, Dongye
Effects of a model oil dispersant (Corexit EC9500A) on sorption/desorption of phenanthrene were investigated with two marine sediments. Kinetic data revealed that the presence of the dispersant at 18 mg/L enhanced phenanthrene uptake by up to 7%, whereas the same dispersant during desorption reduced phenanthrene desorption by up to 5%. Sorption isotherms confirmed that at dispersant concentrations of 18 and 180 mg/L, phenanthrene uptake progressively increased for both sediments. Furthermore, the presence of the dispersant during desorption induced remarkable sorption hysteresis. The effects were attributed to added phenanthrene affinity and capacity due to sorption of the dispersant on the sediments. Dual-mode models adequately simulated sorption isotherms and kinetic data in the presence of the dispersant. Water accommodated oil (WAO) and dispersant-enhanced WAO increased phenanthrene sorption by up to 22%. This information is important for understanding roles of oil dispersants on the distribution and transport of petroleum PAHs in seawater-sediments.
Afficher plus [+] Moins [-]Effect of model dissolved organic matter coating on sorption of phenanthrene by TiO2 nanoparticles
2014
Wang, Xilong | Ma, Enxing | Shen, Xiaofang | Guo, Xiaoying | Zhang, Meng | Zhang, Haiyun | Liu, Ye | Cai, Fei | Tao, Shu | Xing, Baoshan
Dissolved organic matter (DOM) may alter the sorption of hydrophobic organic contaminants (HOC) to metal oxide nanoparticles (NPs), but the role of DOM and NP types is poorly understood. Here, phenanthrene sorption was quantified on four types of nano-TiO2 (three rutile, one anatase), and a bulk, raw TiO2 powder. Prior to the sorption experiments, these nanoparticles were coated using four different organic materials: Lignin (LIG), tannic acid (TAN), Congo red (CON), and capsorubin (CAP). Lignin, tannic acid, congo red and capsorubin coating substantially enhanced phenanthrene sorption to various TiO2 particles. After coating with a specific DOM, Kd values by the DOM-coated TiO2 particles on percent organic carbon content and surface area (SA) basis (Koc/SA) generally followed the order: TiO2 NPs with hydrophobic surfaces > bulk TiO2 particles > other TiO2 NPs. Different Koc/SA values of various DOM-TiO2 complexes resulted from distinct conformation of the coated DOM and aggregation.
Afficher plus [+] Moins [-]Metal composition of fine particulate air pollution and acute changes in cardiorespiratory physiology
2014
Cakmak, Sabit | Dales, Robert | Kauri, Lisa Marie | Mahmud, Mamun | Van Ryswyk, Keith | Vanos, Jennifer | Liu, Ling | Kumarathasan, Premkumari | Thomson, Errol | Vincent, Renaud | Weichenthal, Scott
Studying the physiologic effects of components of fine particulate mass (PM2.5) could contribute to a better understanding of the nature of toxicity of air pollution.We examined the relation between acute changes in cardiovascular and respiratory function, and PM2.5-associated-metals.Using generalized linear mixed models, daily changes in ambient PM2.5-associated metals were compared to daily changes in physiologic measures in 59 healthy subjects who spent 5-days near a steel plant and 5-days on a college campus.Interquartile increases in calcium, cadmium, lead, strontium, tin, vanadium and zinc were associated with statistically significant increases in heart rate of 1–3 beats per minute, increases of 1–3 mmHg in blood pressure and/or lung function decreases of up to 4% for total lung capacity.Metals contained in PM2.5 were found to be associated with acute changes in cardiovascular and respiratory physiology.
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