Quantification of intrinsic water use efficiency along a moisture gradient in Northeastern China

Water use efficiency (WUE) is an important ecophysiological characteristic of plants, especially in semiarid and arid regions. At the scale of community or ecosystem, WUE is difficult to quantify because the amount of water used per unit dry mass production is a function of microclimatic variables and species composition. In this study, we analyzed corrected intrinsic water use efficiency (IWUE(s)) of grass and shrub species along the western segment of the Northeast China Transect (NECT) and the relationship between IWUE(s) and mean annual rainfall, habitat degradation status, vegetation type, and plant functional type (C3 versus C4) at 22 survey sites. Site intrinsic water use efficiency (IWUE(v)) and its relationship with the aforementioned site variables were analyzed based on species frequencies at each site. First, it was concluded that photosynthetic pathway played a very important role in determining species IWUE(s). Mean IWUE(s) for C4 species was approximately double that of C3 species. Second, mean annual rainfall, vegetation type, and site degradation status significantly affected IWUE(s) (p < 0.01). Mean IWUE(s) at degraded sites was twice as high as that at nondegraded sites. The mean IWUE(s) for meadows was significantly higher than those for other vegetation types (p < 0.05). Third, the frequency of occurrence of C4 plants explained 36% of the variance in IWUE(v) across the survey sites. The mean frequency of C4 occurrence at degraded sites was more than double that at nondegraded sites. Consequently, mean IWUE(v) at degraded sites was more than double that at nondegraded sites. Dominant C4 species in saline-alkaline areas tended to have higher intrinsic WUE than dominant C4 species in sandy shrub communities.     

城镇供热管道隐患辨识研究

近年来,因供热管道老化腐蚀、外部自然环境、施工活动等导致的事故时有发生,给居民的冬季供暖造成了严重的危害和影响。本文在分析供热管道自身安全特性的基础上,运用事故树等系统安全分析方法对供热管道隐患进行辨识分析,结合供热管道影响因素明确隐患辨识重点,并针对隐患排查内容及手段等提出对策建议,以支撑供热管道单位更系统、更科学的开展隐患排查治理工作,保障管线的安全运行。     

The Trump administration’s decision to withdraw the United States from the Paris Climate Agreement

<正>After years of complex and challenging negotiations,197countries reached a landmark climate agreement during the 2015 United Nations Framework Convention on Climate Change summit in Paris(the 21st Conference of the Parties(COP21)).Under the Paris Agreement,countries announced actions they plan to take to mitigate their greenhouse gas emissions known as Intended Nationally Determined Contributions.Although there is     

Full-scale blending treatment of fresh MSWI leachate with municipal wastewater in a wastewater treatment plant

Fresh leachate, generated in municipal solid waste incineration (MSWI) plants, contains various pollutants with extremely high strength organics, which usually requires expensive and complex treatment processes. This study investigated the feasibility of blending treatment of MSWI leachate with municipal wastewater. Fresh MSWI leachate was pretreated by coagulation–flocculation with FeCl₃ 2 g/L and CaO 25 g/L, plate-and-frame filter press, followed by ammonia stripping at pH above 12. After that, blending treatment was carried out in a full-scale municipal wastewater treatment plant (WWTP) for approximately 3 months. Different operational modes consisting of different pretreated leachate and methanol addition levels were tested, and their performances were evaluated. Results showed that throughout the experimental period, monitored parameters in the WWTP effluent, including COD (<60 mg/L), BOD₅ (<20 mg/L), ammonium (<8 mg/L), phosphorus (<1.5 mg/L) and heavy metals, generally complied with the Chinese sewage discharged standard. Under the experimental conditions, a certain amount of methanol was needed to fulfill TN removal. An estimation of the operation cost revealed that the expenditure of blending treatment was much lower than the total costs of respective treatment of MSWI leachate and municipal wastewater. The outcomes indicated that blending treatment could not only improve the treatability of the MSWI leachate, but also reduce the treatment cost of the two different wastewaters.     

Effects of taxonomy,sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes,China

Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

     

Insight into metal binding properties of biochar-derived DOM using EEM-PARAFAC and differential absorption spectra combined with two-dimensional correlation spectroscopy

Environmental Science and Pollution Research - A large amount of biochar-derived dissolved organic matter (BDOM) will be released into the environment with biochars application into repairing...     

Using geographically temporally weighted regression to assess the contribution of corruption governance to global PM2.5

Environmental Science and Pollution Research - In the face of the global haze crisis, exploring the driving force of political factors for controlling minute atmospheric particles has become...     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

Knowledge spillovers and subsequent innovation in green energy: the role of public R&D

Environmental Science and Pollution Research -     

Groundwater geochemical signatures and implication for sustainable development in a typical endorheic watershed on Tibetan plateau

Environmental Science and Pollution Research - Groundwater resource is significantly important for sustainable development of the world, especially for arid endorheic watersheds. A total of 28...