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Using devitalized moss for active biomonitoring of water pollution Texto completo
2016
Debén, S. | Fernández, J.A. | Carballeira, A. | Aboal, J.R.
This paper presents the results of an experiment carried out for the first time in situ to select a treatment to devitalize mosses for use in active biomonitoring of water pollution. Three devitalizing treatments for the aquatic moss Fontinalis antipyretica were tested (i.e. oven-drying at 100 °C, oven-drying with a 50-80-100 °C temperature ramp, and boiling in water), and the effects of these on loss of material during exposure of the transplants and on the accumulation of different heavy metals and metalloids were determined. The suitability of using devitalized samples of the terrestrial moss Sphagnum denticulatum to biomonitor aquatic environments was also tested. The structure of mosses was altered in different ways by the devitalizing treatments. Devitalization by boiling water led to significantly less loss of material (p < 0.01) than the oven-drying treatments. However, devitalization by oven-drying with a temperature ramp yielded more stable results in relation to both loss of material and accumulation of elements. With the aim of standardizing the moss bag technique, the use of F. antipyretica devitalized by oven-drying with a temperature ramp is recommended, rather than other devitalization treatments or use of S. denticulatum.
Mostrar más [+] Menos [-]Elemental sulfur amendment decreases bio-available Cr-VI in soils impacted by leather tanneries Texto completo
2016
Shi, Jingjing | Chen, Hualin | Arocena, Joselito M. | Whitcombe, Todd | Thring, Ronald W. | Memiaghe, Jeff Nze
This study investigated the potential use of elemental S (S0) to convert Cr-VI to Cr-III which should decrease the bio-availability hence, toxicity of Cr-VI in soils. The bio-available fraction of Cr in soil was measured by phosphate buffer extraction (PBE) and the results showed that the fraction is about 10% of the total Cr-VI and varied from 12.8 to 42.5 mg kg−1. The addition of 4.0 mg g−1 S0 decreased PBE Cr-VI to <0.4 mg kg−1 limit established for Cr-VI toxicity in soils. Synchrotron-based X-ray absorption near-edge structure (XANES), X-ray fluorescence (XRF) and micro-XRD revealed that Cr-III was the dominant species (99% of total Cr) and Cr was retained by hematite and goethite in soil. Fe-containing minerals may have provided sufficient protection to render the dominant Cr-III species biochemically inert to redox processes in soils. It is concluded that S0amendment is a promising approach to remediate Cr-VI contaminated soils.
Mostrar más [+] Menos [-]Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates Texto completo
2016
Zhu, Zengyin | Xie, Jiawen | Zhang, Mancheng | Zhou, Qing | Liu, Fuqiang
Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R2 = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications.
Mostrar más [+] Menos [-]Ecotoxicity and genotoxicity of cadmium in different marine trophic levels Texto completo
2016
Pavlaki, Maria D. | Araújo, Mário J. | Cardoso, Diogo N. | Silva, Ana Rita R. | Cruz, Andréia | Mendo, Sónia | Soares, Amadeu M.V.M. | Calado, Ricardo | Loureiro, Susana
Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems – the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.
Mostrar más [+] Menos [-]Endosulfan inhibits proliferation through the Notch signaling pathway in human umbilical vein endothelial cells Texto completo
2016
Wei, Jialiu | Zhang, Lianshuang | Ren, Lihua | Zhang, Jin | Yu, Yang | Wang, Ji | Duan, Junchao | Peng, Cheng | Sun, Zhiwei | Zhou, Xianqing
Our previous research showed that endosulfan triggers the extrinsic coagulation pathway by damaging endothelial cells and causes hypercoagulation of blood. To identify the mechanism of endosulfan-impaired endothelial cells, we treated human umbilical vein endothelial cells (HUVECs) with different concentrations of endosulfan, with and without an inhibitor for Notch, N-[N-(3, 5-difluorophenacetyl)-1-alanyl]S-Phenylglycinet-butylester (DAPT, 20 μM), or a reactive oxygen species (ROS) scavenger, N-Acetyl-l-cysteine (NAC, 3 mM), for 24 h. The results showed that endosulfan could inhibit cell viability/proliferation by increasing the release of lactate dehydrogenase (LDH), arresting the cell cycle in both S and G2/M phases, and inducing apoptosis in HUVECs. We also found that endosulfan can damage microfilaments, microtubules, and nuclei; arrest mitosis; remarkably increase the expressions of Dll4, Notch1, Cleaved-Notch1, Jagged1, Notch4, Hes1, and p21; and significantly induce ROS and malondialdehyde production in HUVECs. The presence of DAPT antagonized the above changes of cycle arrest, proliferation inhibition, and expressions of Dll4, Notch1, Cleaved-Notch1, Hes1, and p21 caused by endosulfan; however, NAC could attenuate LDH release; ROS and malondialdehyde production; apoptosis; and the expression levels of Dll4, Notch1, Cleaved-Notch1, Notch4, and Hes1 induced by endosulfan. These results demonstrated that endosulfan inhibited proliferation through the Notch signaling pathway as a result of oxidative stress. In addition, endosulfan can damage the cytoskeleton and block mitosis, which may add another layer of toxic effects on endothelial cells.
Mostrar más [+] Menos [-]Effects of soil acidification and liming on the phytoavailability of cadmium in paddy soils of central subtropical China Texto completo
2016
Zhu, Hanhua | Chen, Cheng | Xu, Chao | Zhu, Qihong | Huang, Daoyou
Intensive and paired soil and rice grain survey and multiple-field liming experiments were conducted to assess soil acidification in the past 30 years, quantify the relationships of Cd phytoavailability with soil acidity, and determine efficacies of liming on soil acidity and Cd phytoavailability in paddy soils of central subtropical China at a regional scale. Soil pH, total and extractable Cd (Cdtot and Cdext), rice grain Cd were determined, and all measured data were analyzed separately in groups of 0.1 pH units intervals. Paddy soil pH averagely declined at 0.031 unit yr−1 between 1980s and 2014 (P < 0.01). Piecewise means of log Cd transfer ratio kept around −0.062 between soil pH 4.0 and 5.5 and around −1.31 between pH 6.9 and 7.3, whereas linearly decreased by a factor of 0.76 with pH 5.5–6.9, and by a factor of 1.38 with pH 7.3–8.2 (P < 0.01), respectively. Similar responses to soil pH were observed for soil Cdext to Cdtot ratio. However, the former exhibited a lag effect to soil acidification in the acidic soils and a leading effect in alkaline soils. Liming increased soil pH by 0.50 units, and decreased rice grain Cd by 35.3% and log Cd transfer ratio by a factor of 0.76 (P < 0.01). The piecewise relationship based on the survey precisely predicted the changes in Cd transfer ratio across the multiple-field liming experiments. In conclusion, soil acidification occurred and accelerated in the past 30 years, and piecewise-linearly increased Cd phytoavailability of paddy soils in central subtropical China. Mitigating soil acidification, i.e. liming, should be preferentially implemented to minimize Cd phytoavailability.
Mostrar más [+] Menos [-]Quantifying sources of elemental carbon over the Guanzhong Basin of China: A consistent network of measurements and WRF-Chem modeling Texto completo
2016
Li, Nan | He, Qingyang | Tie, Xuexi | Cao, Junji | Liu, Suixin | Wang, Qiyuan | Li, Guohui | Huang, Rujin | Zhang, Qiang
We conducted a year-long WRF-Chem (Weather Research and Forecasting Chemical) model simulation of elemental carbon (EC) aerosol and compared the modeling results to the surface EC measurements in the Guanzhong (GZ) Basin of China. The main goals of this study were to quantify the individual contributions of different EC sources to EC pollution, and to find the major cause of the EC pollution in this region. The EC measurements were simultaneously conducted at 10 urban, rural, and background sites over the GZ Basin from May 2013 to April 2014, and provided a good base against which to evaluate model simulation. The model evaluation showed that the calculated annual mean EC concentration was 5.1 μgC m−3, which was consistent with the observed value of 5.3 μgC m−3. Moreover, the model result also reproduced the magnitude of measured EC in all seasons (regression slope = 0.98–1.03), as well as the spatial and temporal variations (r = 0.55–0.78). We conducted several sensitivity studies to quantify the individual contributions of EC sources to EC pollution. The sensitivity simulations showed that the local and outside sources contributed about 60% and 40% to the annual mean EC concentration, respectively, implying that local sources were the major EC pollution contributors in the GZ Basin. Among the local sources, residential sources contributed the most, followed by industry and transportation sources. A further analysis suggested that a 50% reduction of industry or transportation emissions only caused a 6% decrease in the annual mean EC concentration, while a 50% reduction of residential emissions reduced the winter surface EC concentration by up to 25%. In respect to the serious air pollution problems (including EC pollution) in the GZ Basin, our findings can provide an insightful view on local air pollution control strategies.
Mostrar más [+] Menos [-]Under fungal attack on a metalliferous soil: ROS or not ROS? Insights from Silene paradoxa L. growing under copper stress Texto completo
2016
Taiti, Cosimo | Giorni, Elisabetta | Colzi, Ilaria | Pignattelli, Sara | Bazihizina, Nadia | Buccianti, Antonella | Luti, Simone | Pazzagli, Luigia | Mancuso, Stefano | Gonnelli, Cristina
We investigated how the adaptation to metalliferous environments can influence the plant response to biotic stress. In a metallicolous and a non-metallicolous population of Silene paradoxa the induction of oxidative stress and the production of callose and volatiles were evaluated in the presence of copper and of the PAMP fungal protein cerato-platanin, separately and in combination. Our results showed incompatibility between the ordinary ROS-mediated response to fungal attack and the acquired mechanisms of preventing oxidative stress in the tolerant population. A similar situation was also demonstrated by the sensitive population growing in the presence of copper but, in this case, with a lack of certain responses, such as callose production. In addition, in terms of the joint behaviour of emitted volatiles, multivariate statistics showed that not only did the populations respond differently to the presence of copper or biotic stress, but also that the biotic and abiotic stresses interacted in different ways in the two populations.Our results demonstrated that the same incompatibility of hyperaccumulators in ROS-mediated biotic stress signals also seemed to be exhibited by the excluder metallophyte, but without the advantage of being able to rely on the elemental defence for plant protection from natural enemies.
Mostrar más [+] Menos [-]Environmental concentrations of prednisolone alter visually mediated responses during early life stages of zebrafish (Danio rerio) Texto completo
2016
McNeil, Paul L. | Nebot, Carolina | Cepeda, Alberto | Sloman, Katherine A.
The development of the eye in vertebrates is dependent upon glucocorticoid signalling, however, specific components of the eye are sensitive to synthetic glucocorticoids. The presence of synthetic glucocorticoids within the aquatic environment may therefore have important consequences for fish, which are heavily reliant upon vision for mediating several key behaviours. The potential ethological impact of synthetic glucocorticoid oculotoxicity however has yet to be studied. Physiological and behavioural responses which are dependent upon vision were selected to investigate the possible toxicity of prednisolone, a commonly occurring synthetic glucocorticoid within the environment, during early life stages of zebrafish. Although exposure to prednisolone did not alter the morphology of the external eye, aggregation of melanin within the skin in response to increasing light levels was impeded and embryos exposed to prednisolone (10 μg/l) maintained a darkened phenotype. Exposure to prednisolone also increased the preference of embryos for a dark environment within a light dark box test in a concentration dependent manner. However the ability of embryos to detect motion appeared unaffected by prednisolone. Therefore, while significant effects were detected in several processes mediated by vision, changes occurred in a manner which suggest that vision was in itself unaffected by prednisolone. Neurological and endocrinological changes during early ontogeny are considered as likely candidates for future investigation.
Mostrar más [+] Menos [-]Perfluorinated compounds in soil, surface water, and groundwater from rural areas in eastern China Texto completo
2016
Chen, Shu | Jiao, Xing-Chun | Gai, Nan | Li, Xiao-Jie | Wang, X. C. | Lu, Guo-Hui | Piao, Hai-Tao | Rao, Zhu | Yang, Yong-Liang
Little research on perfluorinated compounds (PFCs) has been conducted in rural areas, although rural PFC sources are less complicated than in urban and industrial areas. To determine the levels and geographical distribution of 17 PFC compounds, samples of soil, surface water, and groundwater were collected from eight rural areas in eastern China. The total PFC concentrations (∑PFCs) in soils ranged from 0.34 to 65.8 ng/g ∑PFCs in surface waters ranged from 7.0 to 489 ng/L and ∑PFCs in groundwater ranged from 5.3 to 615 ng/L. Ratios of perfluorononanoic acid/perfluorooctanoic acid (PFNA/PFOA), perfluoro-n-butyric acid/perfluorooctanoic acid (PFBA/PFOA), and perfluoroheptanoic acid/perfluorooctanoic acid (PFHpA/PFOA) in rainwater increased due to the fluorine chemical plants in the surrounding rural and urban areas, suggesting that atmospheric precipitation may carry PFCs and their precursors from the fluorochemical industrial area to the adjacent rural areas.
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