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Effects of alkaline and bioorganic amendments on cadmium, lead, zinc, and nutrient accumulation in brown rice and grain yield in acidic paddy fields contaminated with a mixture of heavy metals
2016
He, Huaidong | Tam, Nora F. Y. | Yao, Aijun | Qiu, Rongliang | Li, Wai Chin | Ye, Zhihong
Paddy soils and rice (Oryza sativa L.) contaminated by mixed heavy metals have given rise to great concern. Field experiments were conducted over two cultivation seasons to study the effects of steel slag (SS), fly ash (FA), limestone (LS), bioorganic fertilizer (BF), and the combination of SS and BF (SSBF) on rice grain yield, Cd, Pb, and Zn and nutrient accumulation in brown rice, bioavailability of Cd, Pb, and Zn in soil as well as soil properties (pH and catalase), at two acidic paddy fields contaminated with mixed heavy metals (Cd, Pb, and Zn). Compared to the controls, SS, LS, and SSBF at both low and high additions significantly elevated soil pH over both cultivation seasons. The high treatments of SS and SSBF markedly increased grain yields, the accumulation of P and Ca in brown rice and soil catalase activities in the first cultivation season. The most striking result was from SS application (4.0 t ha⁻¹) that consistently and significantly reduced the soil bioavailability of Cd, Pb, and Zn by 38.5–91.2 % and the concentrations of Cd and Pb in brown rice by 20.9–50.9 % in the two soils over both cultivation seasons. LS addition (4.0 t ha⁻¹) also markedly reduced the bioavailable Cd, Pb, and Zn in soil and the Cd concentrations in brown rice. BF remobilized soil Cd and Pb leading to more accumulation of these metals in brown rice. The results showed that steel slag was most effective in the remediation of acidic paddy soils contaminated with mixed heavy metals.
显示更多 [+] 显示较少 [-]Calcium signaling and copper toxicity in Saccharomyces cerevisiae cells
2016
Ruta, Lavinia L. | Popa, Claudia V. | Nicolau, Ioana | Farcasanu, Ileana C.
To respond to metal surpluses, cells have developed intricate ways of defense against the excessive metallic ions. To understand the ways in which cells sense the presence of toxic concentration in the environment, the role of Ca²⁺ in mediating the cell response to high Cu²⁺ was investigated in Saccharomyces cerevisiae cells. It was found that the cell exposure to high Cu²⁺ was accompanied by elevations in cytosolic Ca²⁺ with patterns that were influenced not only by Cu²⁺ concentration but also by the oxidative state of the cell. When Ca²⁺ channel deletion mutants were used, it was revealed that the main contributor to the cytosolic Ca²⁺ pool under Cu²⁺ stress was the vacuolar Ca²⁺ channel, Yvc1, also activated by the Cch1-mediated Ca²⁺ influx. Using yeast mutants defective in the Cu²⁺ transport across the plasma membrane, it was found that the Cu²⁺-dependent Ca²⁺ elevation could correlate not only with the accumulated metal, but also with the overall oxidative status. Moreover, it was revealed that Cu²⁺ and H₂O₂ acted in synergy to induce Ca²⁺-mediated responses to external stress.
显示更多 [+] 显示较少 [-]Elemental sulfur in sediments: analytical problems
2016
Rogowska, Justyna | Sychowska, Joanna | Cieszynska-Semenowicz, Monika | Wolska, Lidia
In the paper, a modified method for elemental sulfur (S₈) determining using gas chromatography coupled with mass spectrometry (GC-MS) is proposed with estimation of selected validation parameters. The aim of this work was a review of problems associated with the determination of S₈ and selection of the most optimal conditions for S₈ analysis with GC-MS. The presented studies have shown that the temperature of the injector and the chromatographic column during S₈ determination should not exceed 180 °C. At temperatures over 180 °C, the sulfur S₈ is decomposed to the other sulfur species such as S₂, S₃, S₄, S₅, and S₆. During decreasing injector and column temperature below 180 °C the chromatographic peak eluted as S₈ is badly extended and asymmetric. To minimize the problems of S₈ decomposition to other sulfur species during chromatographic process also other parameters of the GC-MS have been selected. In order to apply the proposed method for real sediments samples, determination of sulfur S₈ in bottom sediments, collected in the Gulf of Gdansk (southern Baltic Sea), has been performed. The concentration of S₈ fell in the range from below the limit of detection to 0.1432 ± 0.0095 mg/g d.w. The research has also shown that addition of approx. 200 mg of activated copper is effective for removing sulfur from bottom sediment extracts.
显示更多 [+] 显示较少 [-]Stability and heavy metal distribution of soil aggregates affected by application of apatite, lime, and charcoal
2016
Cui, Hongbiao | Ma, Kaiqiang | Fan, Yuchao | Peng, Xinhua | Mao, Jingdong | Zhou, Dongmei | Zhang, Zhongbin | Zhou, Jing
Only a few studies have been reported on the stability and heavy metal distribution of soil aggregates after soil treatments to reduce the availability of heavy metals. In this study, apatite (22.3 t ha⁻¹), lime (4.45 t ha⁻¹), and charcoal (66.8 t ha⁻¹) were applied to a heavy metal-contaminated soil for 4 years. The stability and heavy metal distribution of soil aggregates were investigated by dry and wet sieving. No significant change in the dry mean weight diameter was observed in any treatments. Compared with the control, three-amendment treatments significantly increased the wet mean weight diameter, but only charcoal treatment significantly increased the wet aggregate stability. The soil treatments increased the content of soil organic carbon, and the fraction 0.25–2 mm contained the highest content of soil organic carbon. Amendments’ application slightly increased soil total Cu and Cd, but decreased the concentrations of CaCl₂ -extractable Cu and Cd except for the fraction <0.053 mm. The fractions >2 and 0.25–2 mm contained the highest concentrations of CaCl₂-extractable Cu and Cd, accounted for about 74.5–86.8 % of CaCl₂-extractable Cu and Cd in soil. The results indicated that amendments’ application increased the wet soil aggregate stability and decreased the available Cu and Cd. The distribution of available heavy metals in wet soil aggregates was not controlled by soil aggregate stability, but possibly by soil organic carbon.
显示更多 [+] 显示较少 [-]Glial markers and emotional memory in rats following acute cerebral radiofrequency exposures
2016
Barthélémy, Amélie | Mouchard, Amandine | Bouji, Marc | Blazy, Kelly | Puigsegur, Renaud | Villégier, Anne-Sophie
The widespread mobile phone use raises concerns on the possible cerebral effects of radiofrequency electromagnetic fields (RF EMF). Reactive astrogliosis was reported in neuroanatomical structures of adaptive behaviors after a single RF EMF exposure at high specific absorption rate (SAR, 6 W/kg). Here, we aimed to assess if neuronal injury and functional impairments were related to high SAR-induced astrogliosis. In addition, the level of beta amyloid 1–40 (Aβ 1–40) peptide was explored as a possible toxicity marker. Sprague Dawley male rats were exposed for 15 min at 0, 1.5, or 6 W/kg or for 45 min at 6 W/kg. Memory, emotionality, and locomotion were tested in the fear conditioning, the elevated plus maze, and the open field. Glial fibrillary acidic protein (GFAP, total and cytosolic fractions), myelin basic protein (MBP), and Aβ1–40 were quantified in six brain areas using enzyme-linked immunosorbent assay. According to our data, total GFAP was increased in the striatum (+114 %) at 1.5 W/kg. Long-term memory was reduced, and cytosolic GFAP was increased in the hippocampus (+119 %) and in the olfactory bulb (+46 %) at 6 W/kg (15 min). No MBP or Aβ1–40 expression modification was shown. Our data corroborates previous studies indicating RF EMF-induced astrogliosis. This study suggests that RF EMF-induced astrogliosis had functional consequences on memory but did not demonstrate that it was secondary to neuronal damage.
显示更多 [+] 显示较少 [-]Competitive adsorption of phthalate esters on marine surface sediments: kinetic, thermodynamic, and environmental considerations
2016
Mohammadian, Somaye | Ghanemi, Kamal | Nikpour, Yadollah
In this study, the sorption behavior of six widely used phthalate esters (PEs) on marine sediments was investigated. The adsorption of PEs was fast and reached the equilibrium within 6 h. The forward and backward rate constants of all PEs on sediments were calculated. Several kinds of kinetic and thermodynamic models have been investigated; the pseudo-second-order model and the partition isotherm model were best fitted to the adsorption behavior of PEs. The rate-limiting step of sorption was controlled by the film diffusion mechanism. After treating sediments with H₂O₂, the partition coefficients of all PEs were significantly reduced and indicated that the amorphous organic carbon has a major role in adsorption process. The negative values of ΔH° and ΔG° for these compounds showed that the sorption process is exothermic and spontaneous. The adsorption capacities of all PEs were slightly influenced by increasing the salinity from 0 to 40 g L⁻¹. These research findings have a prime importance on assessment of the fate and transport of PEs in seawater-sediment systems.
显示更多 [+] 显示较少 [-]Characteristic variation and original analysis of emergent water source pollution accidents in China between 1985 and 2013
2016
Qu, Jianhua | Meng, Xianlin | Ye, Xiuqing | You, Hong
China has suffered various water source pollution incidents in the past decades, which have resulted in severe threats to the safety of the water supply for millions of residents. From the aspects of quantity fluctuation, temporal volatility, regional inequality, pollutant category variation, and accident type differences, this study first characterizes the current status of water source contaminations in China by analyzing 340 pollution events for the period spanning from 1985 to 2013. The results show a general increase in the number of accidents during the period 1985–2006 and then a rapid decline starting in 2007. Spring and summer are high-incidence seasons for pollution, and the accident rate in developed southeastern coastal areas is far higher than that in the northwestern regions. Hazardous chemicals and petroleum are the most frequently occurring pollutants, whereas heavy metals and tailings are becoming emerging contaminants during occasional pollutions. Most of the accidents that occurred before 2005 were blamed on illegal emissions or traffic accidents; however, leakage in production has gradually become a major accident type in the past decade. Then, in combination with government actions and policy constraints, this paper explores the deep inducements and offers valuable insight into measures that should be taken to ensure future prevention and mitigation of emergent source water pollution.
显示更多 [+] 显示较少 [-]Effect of cadmium accumulation on mineral nutrient levels in vegetable crops: potential implications for human health
2016
Yang, Danping | Guo, Zhiqiang | Green, Iain D. | Xie, Deti
Consumption of vegetables is often the predominant route whereby humans are exposed to the toxic metal Cd. Health impacts arising from Cd consumption may be influenced by changes in the mineral nutrient content of vegetables, which may occur when plants are exposed to Cd. Here, we subjected model root (carrot) and leaf (lettuce) vegetables to soil Cd concentrations of 0.3, 1.5, 3.3, and 9.6 μg g⁻¹ for 10 weeks to investigate the effect of Cd exposure on Cd accumulation, growth performance, and mineral nutrient homeostasis. The findings demonstrated that Cd accumulation in lettuce (20.1–71.5 μg g⁻¹) was higher than that in carrot (3.2–27.5 μg g⁻¹), and accumulation exceeded the maximum permissible Cd concentration in vegetables when soil contained more than 3.3 μg g⁻¹ of Cd. There was a marked hormetic effect on carrot growth at a soil Cd concentration of 3.3 μg g⁻¹, but increasing the Cd concentration to 9.6 μg g⁻¹ caused decreased growth in both crops. Additionally, in most cases, there was a positive correlation between Cd and the mineral nutrient content of vegetables, which was due to physiological changes in the plants causing increased uptake and/or translocation. This may suggest a general mechanism whereby the plant compensated for disrupted mineral nutrient metabolism by increasing nutrient supply to its tissues. Increased nutrient levels could potentially offset some risks posed to humans by increased Cd levels in crops, and we therefore suggest that changes in mineral nutrient levels should be included more widely in the risk assessment of potentially toxic metal contamination. Graphical abstract The Cd concentration (μg g-1 in dry matter) in the root, shoot and translocation factor (TF) of Cd from root to shoot in the carrot and lettuce, and the percentage of root Cd to the gross Cd contents (%) in carrot (C) and lettuce (D) exposed to soil Cd (0 (control), 1, 3, and 9 μg g-1) for 70 days. Values are means ± SD (n = 5).
显示更多 [+] 显示较少 [-]Effects of agricultural fungicides on microorganisms associated with floral nectar: susceptibility assays and field experiments
2016
Bartlewicz, Jacek | Pozo, María I. | Honnay, O. (Olivier) | Lievens, Bart | Jacquemyn, Hans
Pesticides have become an inseparable element of agricultural intensification. While the direct impact of pesticides on non-target organisms, such as pollinators, has recently received much attention, less consideration has been given to the microorganisms that are associated with them. Specialist yeasts and bacteria are known to commonly inhabit floral nectar and change its chemical characteristics in numerous ways, possibly influencing pollinator attraction. In this study, we investigated the in vitro susceptibility of nectar yeasts Metschnikowia gruessi, Metschnikowia reukaufii, and Candida bombi to six widely used agricultural fungicides (prothioconazole, tebuconazole, azoxystrobin, fenamidone, boscalid, and fluopyram). Next, a commercial antifungal mixture containing tebuconazole and trifloxystrobin was applied to natural populations of the plant Linaria vulgaris and the occurrence, abundance, and diversity of nectar-inhabiting yeasts and bacteria was compared between treated and untreated plants. The results showed that prothioconazole and tebuconazole were highly toxic to nectar yeasts, inhibiting their growth at concentrations varying between 0.06 and 0.5 mg/L. Azoxystrobin, fenamidone, boscalid, and fluopyram on the other hand exhibited considerably lower toxicity, inhibiting yeast growth at concentrations between 1 and 32 mg/L or in many cases not inhibiting microbial growth at all. The application of the antifungal mixture in natural plant populations resulted in a significant decrease in the occurrence and abundance of yeasts in individual flowers, but this did not translate into noticeable changes in bacterial incidence and abundance. Yeast and bacterial species richness and distribution did not also differ between treated and untreated plants. We conclude that the application of fungicides may have negative effects on the abundance of nectar yeasts in floral nectar. The consequences of these effects on plant pollination processes in agricultural systems warrant further investigation.
显示更多 [+] 显示较少 [-]Physical properties of particulate matter from animal houses—empirical studies to improve emission modelling
2016
Mostafa, Ehab | Nannen, Christoph | Henseler, Jessica | Diekmann, Bernd | Gates, Richard | Buescher, Wolfgang
Maintaining and preserving the environment from pollutants are of utmost importance. Particulate matter (PM) is considered one of the main air pollutants. In addition to the harmful effects of PM in the environment, it has also a negative indoor impact on human and animal health. The specific forms of damage of particulate emission from livestock buildings depend on its physical properties. The physical properties of particulates from livestock facilities are largely unknown. Most studies assume the livestock particles to be spherical with a constant density which can result in biased estimations, leading to inaccurate results and errors in the calculation of particle mass concentration in livestock buildings. The physical properties of PM, including difference in density as a function of particle size and shape, can have a significant impact on the predictions of particles’ behaviour. The aim of this research was to characterize the physical properties of PM from different animal houses and consequently determine PM mass concentration. The mean densities of collected PM from laying hens, dairy cows and pig barns were 1450, 1520 and 2030 kg m⁻³, respectively, whilst the mass factors were 2.17 × 10⁻³, 2.18 × 10⁻³ and 5.36 × 10⁻³ μm, respectively. The highest mass concentration was observed in pig barns generally followed by laying hen barns, and the lowest concentration was in dairy cow buildings. Results are presented in such a way that they can be used in subsequent research for simulation purposes and to form the basis for a data set of PM physical properties.
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