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A cost compensation model for construction and demolition waste disposal in South China
2019
Liu, Jingkuang | Teng, Yue | Jiang, Yuhan | Gong, Enqin
Construction and demolition waste (C&D waste) is a worldwide issue that concerns the sustainable development of the construction industry. In this paper, detailed formulas are listed for calculating the costs of four typical kinds of disposal routes of C&D waste. They are illegal dumping, controlled dumping (landfill), centralized recycling, and on-site recycling. Through the specific formulas, the costs of the new construction project in Guangzhou are also estimated. Then, a cost compensation model of construction waste disposal is constructed, which serves to calculate the amount of compensation that the government shall make to the contractor’s disposal cost. The results of this study include the following: (1) steps taken to ensure the appropriate measures for C&D waste disposal sites and recycling centers; (2) the on-site recycling will become the future trend of C&D waste disposal due to its lowest cost; (3) the brick cement mortar and scattered concrete take a relatively larger proportion in the total C&D waste generated during the new construction project, and their disposal costs are higher; (4) we find that the cost of illegal dumping is the lowest among four varieties of waste treatment options if only the direct cost of waste treatment is taken account. However, the cost of on-site recycling becomes the lowest if the total cost is considered; (5) according to the case study, the full estimated cost of construction waste disposal is 9074.56 CNY and the total cost compensation is 15,084.21 CNY. The amount of compensation is greater than the disposal cost and contractors make a profit, thus stimulating them to recycle and reuse construction waste. Based on the empirical findings, we make several policy proposals. The research puts forward some operational advice as a reference for decision-makers of C&D waste management.
显示更多 [+] 显示较少 [-]Diversity in flower colorations of Ranunculus asiaticus L. revealed by anthocyanin biosynthesis pathway in view of gene composition, gene expression patterns, and color phenotype
2019
Liu, Yanfang | Zhang, Jianhua | Yang, Xiaohong | Wang, Jiangmin | Li, Yangang | Zhang, Peng | Mao, Jin | Huang, Qingmei | Tang, Hao
Anthocyanin biosynthesis is one of the best studied secondary metabolisms. However, related pathways were generally concluded based on anthocyanin components; most studies focused on the backbone forming of anthocyanidins (cyanidin, delphinidin, and pelargonidin) of model or commercial plants, while anthocyanin modification was less discussed, and non-model plants with abundant colorations were less researched either. Ranunculus asiaticus L. has great diversity in flower colorations, not only indicating its value in researching anthocyanin biosynthesis but also implying it is unique in this regard. Based on transcriptome sequencing and gene annotation of three varieties (10 samples) of Ranunculus asiaticus L., 176 unigenes from 151,136 unigenes were identified as involved in anthocyanin biosynthesis, among which, 74 unigenes were related to anthocyanin modification; 61 unigenes were responsible for glycosylation at C3 and C5 with 3-monosaccharides of glucose, 3-biosides of rutinose, sophorose, or sambubiose to form 3Gly-, 3Gly5Gly-, 3Gly3′Gly-, 3Gly2′′Gly-, 3Gly2′′Xly-, 3Gly2′′Rly-glycosylated anthocyanins, etc.; 2 unigenes transferred –CH₃; 11 unigenes of BAHD family catalyzd the aromatic or malonyl acylation at 6′′ / 6′′′′position of 3/5-O-glucoside. Based on gene composition, a putative pathway was established. The pathway was validated by flower colorations, and gene expression patterns where F3H, F3′H, 3GT, 5GT, and FMT2 were highly expressed in varieties colored as lateritious and carmine, while variety with purple flowers had high expression of F3′5′H and 3MAT. In view of anthocyanin biosynthesis pathway of Ranunculus asiaticus L., great diversity in its flower colorations was illustrated via the complete branches (F3H, F3′H and F3′5′H) as well as complete modifications (glycosylation, methylation, and acylation), and besides, via the higher percentage of C3 glycosylation than C5 glycosylation.
显示更多 [+] 显示较少 [-]Redox status and fatty acid composition of Mactra corallina digestive gland following exposure to acrylamide
2019
Trabelsi, Wafa | Chetoui, Imene | Fouzai, Chaima | Bejaoui, Safa | Rabeh, Imen | Telahigue, Khaoula | Chalghaf, Mohamed | El Cafsi, Mhamed | Soudani, Nejla
Acrylamide (ACR), a ubiquitous agent, has various chemical and industrial applications, and it is found in backed or fried carbohydrate-rich food. It has been related to multiple toxicological effects, and it causes high cytotoxicity through oxidative stress. The present study aimed to investigate the potential effect of ACR toxicity administered at different concentrations (5, 10, and 20 mg/L), during 5 days, in order to evaluate the fatty acid (FA) composition and redox state in the digestive gland of Mactra corallina. The results showed, in ACR-treated clams, a significant increase in malondialdehyde, hydrogen peroxide, protein carbonyl, and metallothionein levels, as well as an alteration of the enzymatic (superoxide dismutase, glutathione peroxidase, and catalase) and non-enzymatic (reduced glutathione and ascorbic acid) antioxidant status. However, acetylcholinesterase activity was inhibited in a concentration-dependent manner. In our experiment, the n-3 (Omega-3) and n-6 (Omega-6) polyunsaturated fatty acid levels were significantly changed in all ACR-treated groups. A decrease in eicosapentaenoic acid (C20:5n-3, EPA) and docosahexaenoic acid (C22:6n-3, DHA) was observed in 10-mg/L and 20-mg/L ACR-treated groups. Nevertheless, arachidonic acid (C20:4n-6, ARA) and its precursor linoleic acid (C18:2n-6, LA) were increased. Besides oxidative stress parameters, FA composition may be an additional tool for assessing ACR contamination.
显示更多 [+] 显示较少 [-]The toxicological analysis of secondary organic aerosol in human lung epithelial cells and macrophages
2019
Ito, Tomohiro | Bekki, Kanae | Fujitani, Yuji | Hirano, Seishiro
Secondary organic aerosol (SOA) is a component of airborne particulate matter in urban areas. However, their toxicities remain incompletely understood. In this study, we investigated the oxidative and inflammatory potency of SOA derived from three different volatile organic compounds (α-pinene, m-xylene, and trimethylbenzene) using human bronchial epithelial cells (BEAS-2B) and macrophages (U937). In BEAS-2B cells, all types of SOA extracts increased the expression of the heme oxygenase 1 (HMOX1) and interleukin-8 (IL8) genes, a typical marker for oxidative stress and inflammatory responses, respectively. Among the three types of SOA, m-xylene-derived SOA showed the strongest induction of the HMOX1 and IL8 genes, and transcriptional activity via the antioxidant response element (ARE). A causal candidate for SOA induction of oxidative stress is 2,6-dimethyl-1,4-benzoquinone (DMBQ) because only this quinone compound increased the transcriptional activity via ARE among components tested in this study. Similar to the case of BEAS-2B cells, SOA extracts increased the expression of HMOX1 and IL8 genes in U937 cells, mainly through oxidative stress, but these responses in U937 cells were prolonged when compared with BEAS-2B cells. Together, these results show that SOA affects lung epithelial cells and macrophages mainly through oxidative stress and inflammation, suggesting their contribution to the development of respiratory diseases.
显示更多 [+] 显示较少 [-]Lateral distribution of sediment and phosphorus in a two-stage ditch with partial emergent vegetation on the floodplain
2019
Bai, Yu | Zeng, Yuhong
Two-stage channels are effective drainage facilities because they can decrease soil erosion and nutrient loss effectively. The lateral distribution of streamwise velocity in two-stage channels has been substantially studied. However, knowledge about the lateral distribution of sediment and phosphorus in two-stage channels with emergent vegetation on the floodplain are limited. In this work, flume experiments were conducted to investigate the relationship between current and transport of sediment and phosphorus. Results show that lateral distributions of total suspended sediment (TSS), particulate phosphorus (PP), and dissolved phosphorus (DP) are affected by the lateral variation of streamwise velocity, i.e., larger TSS and DP were found in the main channel, while larger PP appeared in the floodplain. Besides, theoretical models for the lateral distribution of TSS and DP were presented. Three models were adopted to predict the depth-averaged streamwise velocity, and corresponding results have been used to predict the TSS and DP. Comparisons indicated that with a high-precision velocity model, the newly presented analytical models can give satisfied predictions of the lateral distributions of TSS and DP.
显示更多 [+] 显示较少 [-]Simultaneous wet desulfurization and denitration by an oxidant absorbent of NaClO2/CaO2
2019
Wang, Zhiping | Lun, Liyong | Tan, Zhongchao | Zhang, Yanguo | Li, Qinghai
The simultaneous wet removal performance of NO and SO₂ was studied using the oxidant absorbent NaClO₂/CaO₂. The factors were studied including NaClO₂ and CaO₂ concentrations, reaction temperature, and gaseous components, such as SO₂, NO, O₂, and CO₂. The products in liquid and solid phases were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and ion chromatography to determine the mechanism of simultaneous desulfurization and denitration by NaClO₂/CaO₂. The results indicated that the removal efficiency of SO₂ was in the range of 98–99.9%, and the removal efficiencies of NO and NOₓ were 99.4% and 95.0%, respectively. The removal efficiencies of NO and NOₓ increased with the increase of NaClO₂ and CaO₂ concentration and reaction temperature. The gaseous components had a stronger effect on NOₓ removal efficiency, followed by NO removal efficiency, and SO₂ removal efficiency. As SO₂ concentration increased, the generation of sulfite species promoted the removal of NO and NOₓ. Competition for NO₂ and SO₂ absorption by absorbent inhibited the removal efficiencies of SO₂ and NOₓ. The presence of O₂ was beneficial for removing SO₂, NO, and NOₓ, while the presence of CO₂ was not. The main products in the liquid and solid phases were NO₃⁻, NO₂⁻, SO₄²⁻, and CaSO₄. The reaction mechanism for simultaneous wet removal of SO₂ and NO by NaClO₂/CaO₂ is proposed and discussed.
显示更多 [+] 显示较少 [-]The impact of textual and pictorial warnings on tumbac (waterpipe tobacco) boxes on the motivation and intention to quit waterpipe smoking in Lebanon: a cross-sectional study
2019
Hallit, Souheil | Layoun, Nelly | Malaeb, Diana | Outayek, Miguella | Boueid, Marie-Josée | Waked, Mirna | Bacha, Zeina Aoun | Salameh, Pascale
Few published studies have examined the impact of waterpipe tobacco pictorial health warnings worldwide but none of these papers assessed the motivation and intention to quit among Lebanese waterpipe smokers. To examine factors associated with the motivation and intention to quit waterpipe smoking (WS) in Lebanon, particularly the impact of textual vs. pictorial warnings on tumbac boxes. A cross-sectional study was conducted between January and May 2018, involving 520 participants. Having smokers at work (OR = 0.92) and increasing number of waterpipes per week (ORa = 0.94) were associated with decreased motivation to quit WS. Thinking that shocking images on tumbac packages would have more effect than textual warnings (ORa = 2.96) and those who would change the tumbac if the company decides to change the look of the box with shocking images about health damage (ORa = 1.98) were significantly associated with increased motivation to quit WS. Having a high motivation (ORa = 2.61), thinking that using shocking images on tumbac boxes can have more effect than textual warnings (ORa = 2.12), those who stopped smoking because of the warnings (ORa = 2.62), those who would choose pictorial warnings alone (ORa = 2.11), and both pictorial and textual warnings (ORa = 3.41) on tumbac packages were associated with higher intention to quit WS in two months. Pictorial and textual warnings on tumbac packs were associated with higher intention and motivation to stop WS. Public health education programs for this purpose seem warranted.
显示更多 [+] 显示较少 [-]Low-carbon electricity generation–based dynamic equilibrium strategy for carbon dioxide emissions reduction in the coal-fired power enterprise
2019
Xu, Jiuping | Feng, Qing | Lv, Chengwei | Huang, Qian
Climate change is already resulting in extreme devastation in the earth, with carbon dioxide emissions produced by coal-fired power plants being the largest contributor. Therefore, integrated coal purchasing, blending, and distribution strategies are playing a more important role in large-scale coal-fired power enterprises due to the need to reduce carbon dioxide emissions and operational costs. In this study, a dynamic equilibrium strategy for integrated coal purchasing, blending, and distribution under an uncertain environment is proposed to reduce carbon dioxide emissions in large-scale coal-fired powered enterprises; the practicality and efficiency of which are verified using a real-world case. Sensitivity analyses under different carbon dioxide emissions levels and satisfactory degrees were also conducted to give insights into the conflict between economic development and environmental protection for large-scale coal-fired power enterprises, and balance short-term and long-term production plans. The results indicated that the proposed method was able to achieve economic-environmental coordination and sustainable development. Compared to previous studies, the developed model was found to be able to reduce carbon emissions by about 30% compared with the maximum carbon emissions and improve carbon emissions reduction performance to assist in mitigating climate change.
显示更多 [+] 显示较少 [-]Parameters determining the performance of passive flux samplers proposed as a tool to estimate N2O emissions: evaluation at farm level and perspectives
2019
Larios, Araceli D. | Godbout, Stéphane | Brar, Satinder Kaur | Palacios, Joahnn H. | Zegan, Dan | Sandoval-Salas, Fabiola | Predicala, Bernardo | Avalos-Ramírez, Antonio
The passive flux sampling is an economic and easy way to estimate gas emissions from agriculture sources. In the last decade, specific passive flux samplers (PFSs) have been developed to estimate nitrous oxide (N₂O) emissions from agriculture sources. Packed with silica gel and zeolite 5A, the PFSs were placed facing the emission source direction close to the ventilation shafts. For validation, air samples were taken at different sampling time during 3 days on two commercial sites. The adsorbed mass of N₂O in PFSs was recovered by thermal desorption in the laboratory. Results indicated that the mass of N₂O adsorbed in PFSs was from 1.5 to 5.5 μg. A specific adsorption pattern was observed for each sampling. In farm 1, the mass of N₂O adsorbed in the PFSs presented a linear behavior as a function of sampling time, and the most determined coefficient values were higher than 0.80. In farm 2, in addition to the sampling time, the N₂O concentration and the air flow rate presented an effect on the mass adsorbed in the PFSs. On the other hand, comparison of PFSs versus other techniques indicated that PFSs offer different advantages. However, the selectivity and capacity of the adsorbent bed used need to be improved to enhance the use of PFSs proposed as a tool to estimate N₂O emissions. Graphical Abstract PFSs enabled N₂O sampling that followed a linear behavior as a function of sampling time. Sampling time, [N₂O], and air flow rate determined the mass of N₂O collected in PFSs
显示更多 [+] 显示较少 [-]Inter-comparison of carbon content in PM10 and PM2.5 measured with two thermo-optical protocols on samples collected in a Mediterranean site
2019
Merico, Eva | Cesari, Daniela | Dinoi, Adelaide | Gambaro, Andrea | Barbaro, Elena | Guascito, Maria R. | Giannossa, Lorena C. | Mangone, Annarosa | Contini, Daniele
Scientific interest is focusing on different approaches for characterising organic carbon (OC), elemental carbon (EC) and equivalent black carbon (eBC), although EUSAAR2 protocol has been established and frequently used in EU for regulatory purposes. Discrepancies are observed due to thermal protocols used for OC/EC determinations and the effect of the chemical-physical properties of aerosol using optical measurements for eBC. In this work, a long-term inter-comparison of carbon measurements with two widely used protocols (EUSAAR2 and NIOSH870) was performed on PM₂.₅ and PM₁₀ samples. The influence of the protocol on the evaluation of secondary organic aerosol (SOC) and on the correlation between EC and eBC was investigated. An extensive check of repeatability gave typical uncertainties of ~ 5% for TC and OC, and ~ 10% for EC for both thermal protocols. Results show that OC is statistically comparable between the two protocols but EC is significantly higher with EUSAAR2, especially during the warm season. The ratio OC/EC is lower with EUSAAR2, also showing a seasonality (lower values in the warm season) not observed with NIOSH870. Despite the differences in OC/EC ratios, the contribution of SOC to OC (~ 50%), evaluated using the EC-tracer method, did not differ significantly between the two protocols and for both size fractions. Further, SOC/OC ratios were comparable in cold and warm periods. eBC/EC ratios larger than one for both protocols were obtained, 1.62 (EUSAAR2) and 1.92 (NIOSH870), and also correlated with the ratio OC/EC for both protocols, especially in the cold season.
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