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Résultats 3541-3550 de 5,152
PBPK/PD assessment for Parkinson’s disease risk posed by airborne pesticide paraquat exposure Texte intégral
2018
Cheng, Yi-Hsien | Chou, Wei-Chun | Yang, Ying-Fei | Huang, Jiwei | How, ChunMing | Chen, Szu-Chieh | Chen, Wei-Yu | Hsieh, Nan-Hung | Lin, Yi-jun | You, Shu-Han | Liao, Chung-Min
Exposure to several specific pesticides has led to an increase of Parkinson’s disease (PD) risk. However, it is difficult to quantify the PD population risk related to certain pesticides in regions where environmental exposure data are scarce. Furthermore, the time trend of the prevalence and incidence of PD embedded in the background relationship between PD risk and pesticide exposures has not been well characterized. It has been convincingly identified that a key pesticide associated significantly with an increased risk trend of PD is paraquat (PQ). Here, we present a novel, probabilistic population-based exposure-response approach to quantify the contribution from PQ exposure to prevalence risk of PD. We found that the largest PQ exposure contributions occurred in its positive trend during 2004–2011, with the PQ contributing nearly 21 and 24%, respectively, to the PD prevalence rates among the age groups of 70–79 and ≥ 80 years in Taiwan. We also employed the present population risk model to predict the PQ-induced PD prevalence based on the projected rates of increase in PQ exposure associated with age-specific population. The predicted outcome can be used as an early warning signal for public health authorities. We suggest that a mechanistic understanding of the contribution of a specific pesticide exposure to PD risk trends is crucial to enhance our insights into the perspective on the impacts of environmental exposure on the neurodegenerative diseases.
Afficher plus [+] Moins [-]Insight into litter decomposition driven by nutrient demands of symbiosis system through the hypha bridge of arbuscular mycorrhizal fungi Texte intégral
2018
Kong, Xiangshi | Jia, Yanyan | Song, Fuqiang | Tian, Kai | Lin, Hong | Bei, Zhanlin | Jia, Xiuqin | Yao, Bei | Guo, Peng | Tian, Xingjun
Arbuscular mycorrhizal fungi (AMF) play an important role in litter decomposition. This study investigated how soil nutrient level affected the process. Results showed that AMF colonization had no significant effect on litter decomposition under normal soil nutrient conditions. However, litter decomposition was accelerated significantly under lower nutrient conditions. Soil microbial biomass in decomposition system was significantly increased. Especially, in moderate lower nutrient treatment (condition of half-normal soil nutrient), litters exhibited the highest decomposition rate, AMF hypha revealed the greatest density, and enzymes (especially nitrate reductase) showed the highest activities as well. Meanwhile, the immobilization of nitrogen (N) in the decomposing litter remarkably decreased. Our results suggested that the roles AMF played in ecosystem were largely affected by soil nutrient levels. At normal soil nutrient level, AMF exhibited limited effects in promoting decomposition. When soil nutrient level decreased, the promoting effect of AMF on litter decomposition began to appear, especially on N mobilization. However, under extremely low nutrient conditions, AMF showed less influence on decomposition and may even compete with decomposer microorganisms for nutrients.
Afficher plus [+] Moins [-]Rarasaponin-bentonite-activated biochar from durian shells composite for removal of crystal violet and Cr(VI) from aqueous solution Texte intégral
2018
This paper presents the preparation of composite material and its application for the adsorption of crystal violet and Cr(VI) from aqueous solution onto acid-activated bentonite (AAB) and rarasaponin–bentonite-activated biochar from durian shells composite (RBAB). The influence of initial pH of the solution and the temperature of adsorption on the adsorbents adsorption performance was also studied. Langmuir and Freundlich models could represent the adsorption equilibria equally well. Thermodynamic parameters such as ∆G°, ∆H°, and ∆S° were evaluated based on the adsorption isotherms. The values of ∆G°, ∆H°, and ∆S° for crystal violet adsorption system demonstrate behavior contrary to the Cr(VI) adsorption system. Where crystal violet adsorption is preferred at high temperatures with qₘₐₓ, value is 518.64 mg/L; while adsorption Cr(VI) is better at low temperature with qₘₐₓ, value is 106.30 mg/L. Pseudo-first-order and pseudo-second-order kinetic models could represent the kinetic data well.
Afficher plus [+] Moins [-]Fast trace determination of nine odorant and estrogenic chloro- and bromo-phenolic compounds in real water samples through automated solid-phase extraction coupled with liquid chromatography tandem mass spectrometry Texte intégral
2018
A fast and reliable method was developed for simultaneous trace determination of nine odorous and estrogenic chloro- and bromo-phenolic compounds (CPs and BPs) in water samples using solid-phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). For sample preparation, the extraction efficiencies of two widely applied cartridges Oasis HLB and Sep-Pak C18 were compared, and the Oasis HLB cartridge showed much better extraction performance; pH of water sample also plays important role on extraction, and pH = 2–3 was found to be most appropriate. For separation of the target compounds, small addition of ammonium hydroxide can obviously improve the detection sensitivity, and the optimized addition concentration was determined as 0.2%. The developed efficient method was validated and showed excellent linearity (R ² > 0.995), low limit of detection (LOD, 1.9–6.2 ng/L), and good recovery efficiencies of 57–95% in surface and tap water with low relative standard deviation (RSD, 1.3–17.4%). The developed method was finally applied to one tap and one surface water samples and most of these nine targets were detected, but all of them were below their odor thresholds, and their estrogen equivalent (EEQ) were also very low.
Afficher plus [+] Moins [-]Water quality in simulated eutrophic shallow lakes in the presence of periphyton under different flow conditions Texte intégral
2018
Although the effects of periphyton on water quality and its relationship with flow conditions have been studied by researchers, our understanding about their combined action in eutrophic shallow lakes is poor. In this research, four aquatic model ecosystems with different water circulation rates and hydraulic conditions were constructed to investigate the effect of periphyton and flow condition on water quality. The concentrations of NH₄⁺, TP, and chlorophyll–a and flow conditions were determined. The results show that, as a result of the rising nutrient level at the early stage and the decline in the lower limit, the presence of periphyton can make the ecosystem adaptable to a wider range of nutrients concentration. In terms of the flow condition, the circulation rate and hydraulic condition are influential factors for aquatic ecosystem. Higher circulation rate in the ecosystem, on one hand, facilitates the metabolism by accelerating nutrient cycling which is beneficial to water quality; on the other hand, high circulation rate leads to the nutrient lower limit rising which is harmful to water quality improvement. At low velocities, slight differences in hydraulic conditions, vertical velocity gradient and turbulence intensity gradient could affect the quantity of phytoplankton. Our study suggests that, considering environmental effect of periphyton, flow conditions and their combined action is essential for water quality improvement and ecological restoration in eutrophic shallow lakes.
Afficher plus [+] Moins [-]On the flocculation and settling characteristics of low- and high-concentration sediment suspensions: effects of particle concentration and salinity conditions Texte intégral
2018
Zhu, Zhongfan | Xiong, Xiangzhong | Liang, Chaohuang | Zhao, Ming
It remains unclear how the primary particle concentration and salinity conditions influence the flocculation and settling characteristics of water-sediment suspensions. In this study, two sets of experiments were performed to examine the flocculation and settling properties of low- and high-concentration sediment suspensions. In low-concentration suspensions, the sediment concentration undergoes a rapid initial decrease followed by a slow decrease until it approaches zero with increasing flocculation time. Increases in salinity or the valence of cations from the saline solution added to the suspension lead to a more rapidly decreasing sediment concentration with flocculation time. The valence of cations from the saline solution has a larger influence on the flocculation-settling behaviours of the suspension than the salinity. In high-concentration sediment suspensions, the height of the clear water-turbid water interface in the water-sediment suspension experiences an initial, rapidly decreasing phase followed by a slowly decreasing phase with increasing flocculation time. Increasing the primary particle concentration, salinity or valence of cations from the saline solution added to the suspension causes the height reduction of the clear water-turbid water interface to become gentler. Finally, the valence of cations from the saline solution has a greater influence on the settling characteristics of the high-concentration water-sediment suspension than the salinity.
Afficher plus [+] Moins [-]Effect of microalgae storage conditions on methane yields Texte intégral
2018
Barreiro-Vescovo, Santiago | de Godos, Ignacio | Tomás-Pejó, Elia | Ballesteros, Mercedes | Gonzalez-Fernandez, Cristina
During the last decade, a lot of research has been focused on identifying the methane yields achievable when using microalgae biomass (fresh and pretreated) as a substrate in anaerobic digestion. Encountered differences are frequently attributed to the different microalgae strains (cell walls and macromolecular profiles) or the different metabolic activities of anaerobic sludge used as inoculum. Nevertheless, under the hypothesis that the state of microalgae upon biomass storage may also play a significant role, this study was designed to evaluate the effect of biomass processing and storage on methane yields and hydrolysis kinetics in batch mode assays. Slight changes in the macromolecular profile distribution of the different tested biomass were observed. Regardless of the time that the biomass was stored, results revealed that frozen biomass doubled the hydrolysis constant and enhanced methane yield by 1.56-fold compared to fresh microalgae biomass (82.4 mL CH₄ g COD in⁻¹). Similar enhancement was obtained with the freeze-dried biomass, and slightly lower values were obtained (1.34-fold) for the biomass kept at 4 °C longer than a week. Likewise, the semi-continuously operated reactor fed with microalgae biomass stored for 28 days at 4 °C did not show any effect in terms of methane production, although nitrogen mineralization was higher than expected. Remarkably, the initial stage of the biomass should be carefully considered for comparison purposes with the available literature on batch mode assays. This study highlights the importance of considering how the biomass is stored before the anaerobic digestion process to avoid misleading conclusions.
Afficher plus [+] Moins [-]Polycyclic aromatic hydrocarbons in a bakery indoor air: trends, dynamics, and dispersion Texte intégral
2018
Ielpo, Pierina | Taurino, Maria Rosaria | Buccolieri, Riccardo | Placentino, Claudia Marcella | Gallone, Francesco | Ancona, Valeria | Di Sabatino, Silvana
Indoor air pollution assessment in work environments remains challenging due to a combination of logistic reasons and availability of costly instrumentation for data acquisition and post-processing. Existing literature focuses on energy production environments, hospitals, and less so on food production spaces. Studies on indoor air quality in bakeries are scarce or even absent. Motivated by this, the present study investigates indoor air quality in a bakery located in Bari province in South Italy, using a combination of approaches including analytical chemistry analyses and computational fluid dynamics to reconstruct the air ventilation in response to air temperature gradients within the working environment. PM₂.₅ indoor samplings were collected every 6 h from 7 to 19 April 2013 in the proximity of two bakery ovens powered by gas and wood, respectively. For each sampling day, 4 PM₂.₅ samples were collected: from 3:00 to 9:00 h (first), from 9:00 to 13:30 h (second), from 14:00 to 21:00 h (third), and from 21:00 to 3:00 h (fourth). In total, 40 samples were collected. On each sample, several polycyclic aromatic hydrocarbons (PAHs) were determined such as benzo[a]anthracene (228), benzo[b]fluoranthene (252), benzo[k]fluoranthene (252), benzo[a]pyrene (252), benzo[g,h,i]perylene (276), indeno[1,2,3-cd]pyrene (276), and dibenzo[a,h]anthracene (278), the main compounds of 16 priority US Environmental Protection Agency (US-EPA) PAHs in particulate phase. The PAH mean concentrations showed higher values during the first (from 3:00 to 9:00 h) and fourth (from 21:00 to 3:00 h) sampling intervals than the other two with benzo[a]pyrene mean values exceeding the Italian law limit of 1 ng/m³. Taking into account benzo[a]pyrene mean concentration for the first interval and the first plus the second one, which are the hours with the largest working activity, we have estimated that the baker and co-workers are exposed to a cancer risk of 4.3 × 10⁻⁷ and 5.8 × 10⁻⁷, respectively (these values are lower than US-EPA recommended guideline of 10⁻⁶). Our study was complemented by numerical analyses using state-of-the-art computational fluid dynamics to reconstruct at high resolution air movement from the various working places, i.e., the bakery and the selling area which were connected via a door. The numerical simulations were possible given that surface temperature using infrared thermography as well as air temperature was continuously recorded throughout the sampling acquisition. The use of this approach allowed us to estimate the transport and diffusion of benzo[a]pyrene from one area to the other thus complementing the point sampling information. Computational fluid dynamic simulation results confirm the presence of benzo[a]pyrene in the laboratory as obtained from the measurements and suggests its presence in the sales’ area of the bakery with concentrations similar those found in the laboratory.
Afficher plus [+] Moins [-]Effectiveness of nutrient remotion and cell physiology of Amphora sp. cultured in shrimp farm effluents Texte intégral
2018
Sassi, Patrícia Giulianna Petraglia | Calixto, Clediana Dantas | Tibúrcio, Viviane Pereira | da Silva Nonato, Nyelson | Abrahão, Raphael | Hégaret, Hélène | da Costa Sassi, Cristiane Francisca | Sassi, Roberto
Shrimp farm effluents are one of the principal causes of eutrophication in coastal environments. Integrated processes of bioremediation involving the culturing of purifying organisms have been suggested, but very few studies have focused on microalgae. For that purpose evaluated the growth potential of Amphora sp. in the residual waters of shrimp farm activity fulfilled on the Paraíba State, Brazil. The experiments were performed using Conway medium as the control and wastewaters from shrimp farm at 100% concentrations. Amphora sp. demonstrated good growth in the shrimp farm effluents under test conditions, although less than that observed in the control medium. This diatom was found to removed 73.357 and 72.572% of PO₄⁻ and NO₃⁻, respectively, demonstrating a high mitigation potential for this type of effluent. Comparisons of the physiological responses measured by flow cytometry demonstrated higher cell densities of Amphora sp. in the control medium, but a higher lipid content was observed in Amphora cultured in shrimp farm effluents.
Afficher plus [+] Moins [-]Comparative habitat use by takin in the Wanglang and Xiaohegou Nature Reserves Texte intégral
2018
Kang, Dongwei | Li, Shuang | Wang, Xiaorong | Huang, Jian | Li, Junqing
We investigated the habitat use characteristics of takin in Wanglang and Xiaohegou Nature Reserves to detect whether takin has the different habitat use patterns in different environments. We found that takin has similarities and differences in habitat use in these two nature reserves. Takin at Wanglang usually used the habitats with greater bamboo coverage and bamboo density, whereas takin at Xiaohegou usually used the habitats with a lower canopy. The results of a logistic regression analysis showed that bamboo density, herb-cover proportion, and tree size contributed significantly to the difference between takin plots at Wanglang and Xiaohegou, with an overall correct prediction rate of 92.3%, indicating that these are the main factors discriminating habitat use characteristics of takin in these two nature reserves. Considering takin has different habitat use characteristics in different areas, different protection measures should be taken to protect different takin populations. Based on the habitat use characteristics of takin at Wanglang and Xiaohegou, we summarized adaptation of takin to environments as general adaptation, regional adaptation, and special adaptation.
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