流动沙漠地形起伏区尼龙网方格沙障破损程度的空间分异

在塔克拉玛干沙漠油田公路K287 km处,对设置在纵向复合沙垄区次级新月形沙丘上不同地貌部位的尼龙网方格沙障破损状况进行了调查研究,并对破损程度进行了综合评价。研究结果表明,(1)平沙地上的尼龙网方格沙障破损类型相对单一,以半埋型式为主;流动沙丘上的尼龙网方格沙障破损类型多样,而且不同地貌部位的破损类型不同。(2)沙丘个体及不同地貌部位的破损程度值远远高于平沙地,破损程度值排序为迎风坡脚迎风坡中部沙丘两翼落沙坡迎风坡中上部丘顶。(3)沙丘不同地貌部位尼龙网方格沙障受损的空间分异主要与沙丘对近地表风流场的强烈扰动有关。(4)尼龙网方格沙障更适宜布设在平坦的地形,提高尼龙网方格沙障对地形起伏适应性的关键在于其布设模式以及布设配件的改进。     

三维粒子电极填充方式对焦化废水深度处理能耗的影响

采用钌钛网(Ti/Ru O2)为阳极、钛网(Ti)为阴极、活性炭颗粒为三维粒子电极的电催化氧化装置深度处理焦化废水,通过分析处理效果和能耗研究了三维粒子电极填充方式的影响。结果显示三维悬挂电极填充方式的处理效果和能耗与传统三维电极填充方式相近,但所需材料质量及反应器容积分别为后者的34%与67%。新的填充方式在电流密度2.5 m A/cm2、悬挂电极总质量49.4g、流速100 m L/min的条件下处理120 min后,焦化废水ρ(COD)由99 mg/L降至53 mg/L,COD去除率为46.5%,单位COD处理能耗为68.5 k W·h/kg,吨水能耗为3.15 k W·h/t。     

Effects of elevated atmospheric CO2 concentration and temperature on the soil profile methane distribution and diffusion in rice-wheat rotation system

The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice–wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO_2 concentration elevated to ~ 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO_2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m~2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO_2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice–wheat field annual rotation ecosystem(p 0.05).     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet(China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

河流中碳、硫稳定同位素的研究进展

河流系统是全球生物地球化学循环的关键环节,是将陆地侵蚀物质输入海洋的主要通道.自然风化是河流水物源的主要营力,人为活动的影响使河流污染物的来源更加复杂,仅仅依靠主要离子组成不能很好的区分河流中物质的不同来源,而稳定碳、硫同位素可以示踪河流中物质的来源.本文综述了当代河流系统中碳、硫同位素的研究现状和分析方法,并对未来河流研究中碳-硫耦合循环研究进行了展望.     

Antibiotic resistomes in water supply reservoirs sediments of central China: main biotic drivers and distribution pattern

Environmental Science and Pollution Research - Water supply reservoirs form one of the critical drinking water resources. Their water quality directly affects human health. However, reservoir...     

Ni-Co bimetallic catalysts on coconut shell activated carbon prepared using solid-phase method for highly efficient dry reforming of methane

Ni-Co bimetallic catalysts supported on coconut shell activated carbon are synthesized using solid-phase method and investigated for dry reforming of methane, to explore the impact of Ni:Co ratio on the catalyst activity and stability. The catalyst performances are evaluated under the temperature varying from 600 to 900 °C and gas hourly space velocity (GHSV) of 7200 mL/h·g-cat. The characterization results show that metal nanoparticles are produced on the support, and the bimetallic catalyst with an explicit Ni:Co ratio (2:1) is the most beneficial for metal particle dispersion and acquires the minimum particle size of 4.41 nm. The bimetallic catalysts with an explicit Ni:Co ratio of 1:2 and 1:1 exhibit a synergistic effect towards the conversions of CH₄ and CO₂, respectively. The experimental results reveal that the highest CH₄ and CO₂ conversions rise to 94.0% and 97.5% within 12 h at 900 °C on average, respectively, assisted with the two bimetallic catalysts. The intensity of disordered carbon and thermal stability are enhanced with the extension of reforming process, contributing to a long-term catalytic stability. Besides, no obvious carbon deposition is detected, leading to a highly catalytic stability for the bimetallic catalysts.

     

Effect of different carbon sources on performance of an A<Subscript>2</Subscript>N-MBR process and its microbial community structure

Effect of different carbon sources on purification performance and change of microbial community structure in a novel A₂N-MBR process were investigated. The results showed that when fed with acetate, propionate or acetate and propionate mixed (1:1) as carbon sources, the effluent COD, NH₄ ⁺-N, TN and TP were lower than 30, 5, 15 and 0.5 mg?L^–1, respectively. However, taken glucose as carbon source, the TP concentration of effluent reached 2.6 mg?L^–1. Process analysis found that the amount of anaerobic phosphorus release would be the key factor to determine the above effectiveness. The acetate was beneficial to the growth of Candidatus Accumulibacter associated with biological phosphorus removal, which was the main cause of high efficiency phosphorus removal in this system. In addition, it could eliminate the Candidatus Competibacter associated with glycogen-accumulating organisms and guarantee high efficiency phosphorus uptake of phosphorus accumulating organisms in the system with acetate as carbon source.

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Microalgae cultivation and culture medium recycling by a two-stage cultivation system

Nutrients and water play an important role in microalgae cultivation. Using wastewater as a culture medium is a promising alternative to recycle nutrients and water, and for further developing microalgae-based products. In the present study, two species of microalgae, Chlorella sp. (high ammonia nitrogen tolerance) and Spirulina platensis (S. platensis, high growth rate), were cultured by using poultry wastewater through a two-stage cultivation system for algal biomass production. Ultrafiltration (UF) or centrifuge was used to harvest Chlorella sp. from the first cultivation stage and to recycle culture medium for S. platensis growth in the second cultivation stage. Results showed the two-stage cultivation system produced high microalgae biomass including 0.39 g·L^–1Chlorella sp. and 3.45 g·L^–1S. platensis in the first-stage and second-stage, respectively. In addition, the removal efficiencies of NH₄⁺ reached 19% and almost 100% in the first and the second stage, respectively. Total phosphorus (TP) removal reached 17% and 83%, and total organic carbon (TOC) removal reached 55% and 72% in the first and the second stage, respectively. UF and centrifuge can recycle 96.8% and 100% water, respectively. This study provides a new method for the combined of pure microalgae cultivation and wastewater treatment with culture medium recycling.

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