Direct shear behaviors of excavated clay reinforced with geocomposite drainage layer encapsulated in thin sand layers.

The objective of this study is to assess the effectiveness of a novel structure comprising a geocomposite drainage layer and a thin sand layer (GDL + sand) in mitigating the rapid dumping of excavated clay and its associated issues, such as landslides. Two sets of direct shear tests were conducted to investigate the influence of sand layer thickness and compaction degree on the interface shear behavior of the GDL + sand structure. As the sand layer thickness increased, both the interface shear strength and friction angle gradually increased, first more sharply and then at a slower rate toward stability, while the interface cohesion decreased gradually. The optimal sand layer thickness for achieving the most effective reinforcement in stabilizing the clay was identified as 10 mm. A higher sand layer compaction degree was found to result in increased interface shear strength, interface friction angle, and interface cohesion. Building on these findings, the reinforcing efficiency of the GDL + sand structure was investigated through mechanism analysis in comparison to that of a geogrid + sand structure and GDL structure as per the interface friction coefficient. The ranking of interface friction coefficients among the three structures emerged as: geogrid + sand > GDL + sand > GDL. These results suggests that the GDL + sand structure exhibits superior reinforcement efficiency compared to the GDL structure and offers better drainage efficiency than the geogrid + sand structure.

One-dimensional consolidation of highly saturated abandoned-soil under time-dependent stress: An analytical study.

A thorough knowledge of the consolidation behavior of highly saturated soil under time-dependent stress is essential for the design and construction of abandoned-soil dump sites in the soft soil regions of China. In this study, one-dimensional consolidation analytical solutions are derived for such soil under one-way and two-way drainage conditions, accommodating the time-dependent stress created by various dumping protocols. Representative soil samples are obtained, and consolidation tests are conducted with various saturation degrees (one-way drainage) and loading protocols (two-way drainage), to verify the consolidation equation and determine its range of applicability to various saturation degrees. The effects of layer thickness, dumping type, and compaction degree on the consolidation behaviors of highly saturated abandoned-soil dumps are investigated. The one-dimensional consolidation equation is applicable to soil with saturation degree not lower than 75% under instantaneous stress, stepped stress, and linear stress. The pore pressure distribution with depth is not symmetrical; the eccentric distance of consolidation degree increases with increasing layer thickness in the stress application stage and is approximately zero in the stress keeping stage. The pore pressure at middle of the soil layer increases with increasing layer thickness and decreases with increasing dumping rate from the completion of soil dumping. With increasing compaction degree, the middle pore pressure increases, while the surface settlement decreases. In the premise of the stability of an abandoned-soil dump, where the goals are to reduce post-construction settlement and to shorten the consolidation process of the entire soil layer, the important factors are smaller layer thickness, higher dumping rate, and larger compaction degree.

Characterization of compression behaviors of high food waste content (HFWC) MSW and no food waste content (NFWC) MSW in China.

In this paper, three sets of laboratory tests were conducted on high-food-waste-content (HFWC-), no-food-waste-content (NFWC-) and decomposed (D-) MSWs to characterize their compression behaviors. The immediate compression ratios C'c were 0.30, 0.23 and 0.18 for HFWC-MSW, NFWC-MSW and D-MSW respectively, and tended to increase with the increasing food waste content of MSW. The release of intra-particle water contained in food waste contributed over 23.6-29.2% to immediate compression for HFWC-MSW. The mechanical creep ratios C'sc were 0.02, 0.015 and 0.01 for HFWC-MSW, NFWC-MSW and D-MSW respectively. A prediction model for C'sc was proposed which incorporated the effects of moisture content, dry unit weight and organic waste content. The bio-compression ratios C'sbI, C'sbII and C'sbIII in response to degradation stage I, II and III were 0.12, 0.10 and 0.02 for HFWC-MSW, and were 0.01, 0.15 and 0.01 for NFWC-MSW. Bio-compression is dominant in stage I and II and mechanical creep is the major contributor in stage III for HFWC-MSW, but to NFWC-MSW, mechanical creep is dominant in stage I and III, and bio-compression takes the main position in stage II. The bio-compression tended to increase linearly with leachate draining rate for HFWC-MSW, and the release of intra-particle water contributed 61.9-65.6% to bio-compression. A new model was proposed that can well capture the highly non-linear behavior of bio-compression for both HFWC-MSW and NFWC-MSW. Based on the above findings, the settlement behavior of HFWC-MSW and NFWC-MSW landfills was compared, and suggestions for technique-efficient and cost-effective design of a NFWC-MSW landfill were discussed.

WUSCHEL-related homeobox gene PagWOX11/12a responds to drought stress by enhancing root elongation and biomass growth in poplar.

In plants, a large root system improves the uptake of water and nutrients, and is important for responding to drought stress. The poplar WUSCHEL-related homeobox (WOX) transcription factor promotes adventitious rooting, but its regulation of root growth in response to drought stress remains elusive. In this study, we found that PagWOX11/12a from hybrid poplar 84K (Populus alba×Populus glandulosa) is expressed predominantly in the roots and is strongly induced by drought stress. Compared with non-transgenic 84K plants, transgenic poplar plants overexpressing PagWOX11/12a displayed increased root biomass and enhanced drought tolerance, while opposite phenotypes were observed for PagWOX11/12a dominant repression plants. PagWOX11/12a functions as a nuclear transcriptional activator with a transactivation domain at the C-terminus. In addition, PagERF35 was found to specifically bind to a dehydration-responsive element (DRE) within the PagWOX11/12a promoter and activate PagWOX11/12a gene expression. These results indicate that PagERF35 may activate PagWOX11/12a expression in response to drought stress by promoting root elongation and biomass, thereby increasing drought tolerance of poplar.

Laboratory method of microbial induced solidification/stabilization for municipal solid waste incineration fly ash.

This paper presents a method to solidify/stabilize the municipal solid waste incineration (MSWI) fly ash by originally employing the microbial induced carbonate precipitation (MICP) technique. In this method, the rich endogenous calcium in the MSWI fly ash was utilized to induce calcite precipitation, which is different from the operation of adding extra calcium source in previous researches. The fly ash sample had a CaO content of 44.5%, and its leaching concentrations of Zn, Cr and Pb exceed the limits of the identification standard for hazardous wastes in China. The optical density at 600 nm (OD600) of the bacterial solution was about 1.0 after the processes of bacterial activation and reproduction. The prepared fly ash sample was well mixed with bacterial solution at an ash-liquid ratio of 1 kg: 0.3 L and cured at a temperature of 20 °C and a humidity of ≥95% for 7 days. After treatment, the heavy metal leachability significantly reduced to meet the standard for pollution control of landfill site, and the unconfined compressive strength increased approximately 40%. The precipitated carbonates were verified by SEM-EDS analysis and quantified by measurement of carbonate content via acid-dissolving method. The results shone a light on the possibility of using MICP technique as a useful and efficient tool to stabilize the MSWI fly ash before being reused or properly stored in landfills. •The MICP method is efficient to reduce the heavy metal leachability and increase the compressive strength of MSWI fly ash.•The endogenous calcium in MSWI fly ash was utilized to induce calcite precipitation.•The heavy metals in MSWI fly ash were well immobilized by the formation of carbonates.

[Regional Transport Matrix Study of PM2.5 in Jingjinji Region, 2015].

By coupling particle source apportionment technology (PSAT) with a comprehensive air quality model with extensions (CAMx), the regional transport matrix of PM2.5 was built for 13 cities in the Jingjinji Region in 2015. Results showed that the major contributor to PM2.5 was local source emissions, contributing 21.49%-68.74%, The internal transport from in-region sources contributed 13.31%-54.62% and the external transport from out-region sources contributing 13.32%-45.02% were also significant. The spatio-temporal distribution of the PM2.5 transport matrix was characterized by geographical, meteorological, and source patterns. Local emissions exerted the most significant impact on the central part of Jingjinji in winter, while regional transport contributed more to the southern region in other seasons. By assessing the input/output and activity of PM2.5 transport, Langfang, Hengshui, Chengde, Qinhuangdao, and Xingtai were receptors; Tianjin, Cangzhou, Tangshan, Beijing, Shijiazhuang, and Handan were sources, and Zhangjiakou and Baoding had a balanced transportation mode. The seasonal matrix of PM2.5 showed significant transport between Beijing and Langfang, Baoding, Chengde, Tianjin, Cangzhou, while the city list for Tianjin and Shijiazhuang differed slightly.

Pollution control costs of a transboundary river basin: Empirical tests of the fairness and stability of cost allocation mechanisms using game theory.

With rapid economic growth, transboundary river basin pollution in China has become a very serious problem. Based on practical experience in other countries, cooperation among regions is an economic way to control the emission of pollutants. This study develops a game theoretic simulation model to analyze the cost effectiveness of reducing water pollutant emissions in four regions of the Jialu River basin while considering the stability and fairness of four cost allocation schemes. Different schemes (the nucleolus, the weak nucleolus, the Shapley value and the Separable Cost Remaining Benefit (SCRB) principle) are used to allocate regionally agreed-upon water pollutant abatement costs. The main results show that the fully cooperative coalition yielded the highest incremental gain for regions willing to cooperate if each region agreed to negotiate by transferring part of the incremental gain obtained from the cooperation to cover the losses of other regions. In addition, these allocation schemes produce different outcomes in terms of their fairness to the players and in terms of their derived stability, as measured by the Shapley-Shubik Power Index and the Propensity to Disrupt. Although the Shapley value and the SCRB principle exhibit superior fairness and stabilization to the other methods, only the SCRB principle may maintains full cooperation among regions over the long term. The results provide clear empirical evidence that regional gain allocation may affect the sustainability of cooperation. Therefore, it is implied that not only the cost-effectiveness but also the long-term sustainability should be considered while formulating and implementing environmental policies.

[Satellite retrieval of a heavy pollution process in January 2013 in China].

By simulating vertical stratification data of PM2.5 with the third-generation air quality model CMAQ and high resolution relative humidity data with mesoscale meteorological model WRF, MODIS AOD data were revised by vertical and humidity correcting method, respectively. A linear regression model between revised AOD and PM2.5 was built, and the linear correlation coefficient was r = 0.77 (n = 57, P < 0.01). Based on this model, the average monthly concentrations of PM2.5 in 10 km resolution in January 2013 were firstly retrieved in the country, and the population exposure level was analyzed. The results showed that the areas where average monthly concentrations of PM2.5 was greater than 100 µg x m(-3) and 200 µg x m(-3) in January 2013 were 10.99% and 1.34% of the national terrestrial area, respectively, and the ratios of exposed population were as high as 45.01% and 6.31%, respectively.

[Environmental damages assessment: establishment of system framework in China].

Health injury, properties compensation and ecological and environmental destruction caused by environmental pollutions have become the focuses of the government, the public and the society at present in China. The experiences of developed countries have revealed that the environmental damage assessment system must be established through development of environmental damage assessment legislations, technologies and funding guarantee system suitable for the nation's conditions based on the specific environmental situation and main issues. China has some experience in marine ecological environment, fishery resources damage assessment, forest resources damage assessment and remediation management of contaminated sites; however, the managing function of environmental damage assessment is assigned to different governmental departments. There are also shortcomings such as few cases of environmental public compensation, insufficient environmental privacy determination and compensation, etc. Based on the methods of materials and information collections, questionnaires, visiting environmental court and government sectors, interviews to assessment organizations and professionals, launching practical assessments to related cases and participating in environmental public lawsuits, the situation of environmental pollution damages in China was analyzed, the related legislation and management mechanism were reviewed, the corresponding assessment organizations regarding environmental damages were sort out, and the funding sources of environmental damage assessment were explored. Aiming at the main issues in Chinese environmental damage management, a standard and unified system for environmental damage assessment based on current managing and technological systems is important to improve the practical work in determination, assessment and compensation of environmental pollution damage in China, and to further explore the feasible environmental damage quantitative management.

[Assessment of haze-related human health risks for four Chinese cities during extreme haze in January 2013].

OBJECTIVE: To evaluate the human health risks (premature death risk as an indicator) in Beijing, Shanghai, Guangzhou and Xi'an during extreme haze in January 2013. METHODS: The daily average particulate matter ≤ 2.5 µm in aerodynamic diameter (PM2.5) concentrations of Beijing, Shanghai, Guangzhou and Xi'an in January 2013 were collected and their characteristics explored. The populations and mortality rate of four cities in 2010 were collected from the statistical yearbook, the exposure-response relationships selected from the reference and then the premature death calculated according to the proportion risk model of Poisson regression. RESULTS: In January 2013, the 24 h mean concentrations of PM2.5 in Beijing, Shanghai, Guangzhou and Xi'an were (240 ± 165) , (83 ± 27), (94 ± 49) and (210 ± 98) µg/m(3) respectively and they were all above the secondary level of Ambient Air Quality Standards (GB 3095-2012). The 24 h mean concentrations of PM2.5 in Beijing and Xi'an were much higher than those in Shanghai and Guangzhou. Approximately 86.4% (19/22) , 58.1% (18/31), 54.8% (17/31) and 93.5% (29/31) of 24 h mean PM2.5 concentrations in Beijing, Shanghai, Guangzhou and Xi'an respectively exceeded the secondary level of Ambient Air Quality Standards (GB 3095-2012). The number of premature death due to the exposure to haze were 725 (95%CI: 457-977) for Beijing, 296 (95%CI: 96-502) for Shanghai, 310 (95%CI: 189-434) for Guangzhou and 85 (95%CI: 21-141) for Xi'an respectively in January 2013. CONCLUSION: The PM2.5 pollutions of four cities in January 2013 were serious enough to pose elevated risks of human health.

[Environmental damage assessment: international regulations and revelation to China].

As the whole society gradually realizes the scarcity of nature resources and environmental value, countries all over the world have evolved and improved the system of environmental damage assessment through the practices of pollution prevention and ecological environmental protection. On one hand, in the research prospective, the practices of environmental damage assessment brought new challenges to environmental law, environmental economics, environmental science, environmental engineering, etc. On the other hand, they constantly promoted and developed relevant laws and regulations, techniques, working mechanism, and guidelines on procedure in practice. On the hasis of comparison and analysis of international practices and experiences from US, EU, and Japan, etc., this article identified relevant concepts, content, and scope of environmental damage assessment, and presented its scientific positioning and development direction. At present, both theory and practice of environmental damage assessment in China are in their infancy period. Considering current environmental situation and socioeconomic development features of China, learning international practices and experiences and raising the orientation of environmental damage assessment have great meaning in exploring the suitable environmental damage assessment system.

[Simulation of air pollution characteristics and estimates of environmental capacity in Zibo City].

To develop a new pattern of air pollution control that is based on the integration of "concentration control, total amount control, and quality control", and in the context of developing national (2011-2015 air pollution control plan for key areas) and (Environmental protection plan of Zibo municipality for the "12th Five-Year Plan" period), a simulation of atmospheric dispersion of air pollutants in Zibo City and its peripheral areas is carried out by employing CALPUFF model, and the atmospheric environmental capacity of SO2, NO(x) and PM10 is estimated based on the results of model simulation and using multi-objective linear programming optimization. The results indicates that the air pollution in Zibo City is significantly related to the pollution sources outside of Zibo City, which contributes to the annual average concentration of SO2, NO2 and PM10 in Zibo City by 26.34%, 21.23%, and 14.58% respectively. There is a notable interaction between districts and counties of Zibo municipality, in which the contribution of SO2, NO(x) and PM10 emissions in surrounding counties and districts to the annual average concentrations of SO2, NO2 and PM10 in downtown area are 35.96%, 43.17%, and 17.69% respectively. There is a great variation in spatial sensitivity of air pollutant emission, and the environmental impact of unit pollutant emissions from Zhoucun, Huantai, Zhangdian and Zichuan is greater than that released from other districts/counties. To meet the requirement of (Ambient air quality standard) (GB 3095-2012), the environmental capacities of SO2, NO(x) and PM10 of Zibo City are only 8.03 x 10(4) t, 19.16 x 10(4) t and 3.21 x 10(4) t, respectively. Therefore, it is imperative to implement regional air pollution joint control in Shandong peninsula in order to ensure the achievement of air quality standard in Zibo City.

HPLC/HPSEC-FLD with multi-excitation/emission scan for EEM interpretation and dissolved organic matter analysis.

The need to track and characterize dissolved organic matter (DOM) has made fluorescence excitation-emission matrix (EEM) spectroscopy extensively used. In this work, reverse phase high-performance liquid chromatography (RP-HPLC) and high-performance size exclusion chromatography (HPSEC) with fluorescence detector (FLD) were used for EEM interpretation and DOM analysis. Given that fluorescence detectors can scan with multi-excitation or multi-emission mode, HPLC-FLD with multi-excitation scan directly verified the prevalence of multi-peak fluorophores in EEM, which provides a corrective insight for the current fluorescence regional integration (FRI) methods; whereas HPLC-FLD with multi-emission scan provided more informative fluorescence fingerprints for identification of DOM species, which is a chromatographic surrogate for determining the proper number of PARAFAC components. Besides providing a deep insight for the current EEM interpretation, the HPLC/HPSEC-FLD results also directly related physiochemical properties to DOM species, including polarity and molecular weight (MW) distribution, which is helpful for further characterization their behavior in water and wastewater treatment process. A chromatography technique with multi-excitation and multi-emission fluorescence scan can be an informative method for EEM interpretation and DOM identification and characterization.

[Application of linear programming in the allocation of environmental capacity resources].

This paper analyzes the application of optimization approaches, particularly the application types of the linear programming (LP) model in environmental planning and management; put forwards the objective function models and their constraint conditions. Based on the formulation of linear programming model related to environmental planning the paper develops the allocation model of environmental purification capacity (EPC), and identifies the constraints to EPC allocation and their parameters or co-efficiencies. It is proved that LP approach is a practical and scientific tool for allocating EPC in specific region.