Enhanced nitrogen removal in filled-and-drained vertical flow constructed wetlands: microbial responses to aeration mode and carbon source

Environmental Science and Pollution Research - For the purpose of enhancing the removal rate of nitrogen (N) and organic matters, intermittent aeration and carbon source were used in...     

区域PM2.5时空回归建模与预测

基于区域PM_(2.5)时空建模和预测的需要及PM_(2.5)浓度呈现明显的时空分布趋势的状况,以苏南地区2014年PM_(2.5)日监测数据为实验数据,使用回归克里格对区域PM_(2.5)进行时空建模和估值。利用最小二乘法建立了PM_(2.5)与时空位置的三元二次回归趋势模型,建模点趋势值与实测值间的平均误差接近于0,表明趋势模型拟合效果较好;拟合了样点残差的理论变异函数模型,表明该地区PM_(2.5)的空间和时间相关性范围分别为150 km和4 d;基于该模型,使用时空普通克里格对残差进行时空插值;插值结果与趋势项相加,得到PM_(2.5)回归克里格估值结果;通过对比不考虑趋势的时空普通克里格估值结果,发现考虑时空趋势的时空回归克里格法精度提高了1. 29%。对所提方法进行了创新性分析,并对不足之处进行了讨论。     

Effects of Land Use Changes on the Ecosystem Service Values of a Reclamation Farm in Northeast China

Intensive agricultural development can change land use, which can further affect regional ecosystem services and functions. With the rapid growth of the population and the national demand for food, the northeast of China, which is located in the high latitudes, has experienced four agricultural developments since the 1950s. The original wetlands of this area were developed for farmland. The evaluation of ecosystem services is conducted to reveal the ecosystem status and variable trends caused by land reclamation. The aim of this study is to provide scientific basis for environmental management and for the sustainable development of agriculture in Northeast China. With GIS-RS technology, a typical farm was chosen to analyze variations in the ecosystem service value in response to land use changes during the study period. The total ecosystem service value of the farm decreased from 7523.10 million Yuan in 1979 to 4023.59 million Yuan in 2009 with an annual rate of ?1.6?% due to the decreasing areas of woodland and wetland. The increased areas of cropland, water area and grassland partly offset the loss of the total value, but the loss was still greater than the compensation. Waste treatment and climate regulation were the top two service functions with high service values, contributing to approximately 50?% of the total service value. The spatial difference of the ecosystem service value also was analyzed. The wetlands located in the central and northeastern sections of the farm changed significantly. From the aspect of ecosystem service value, the wetland and water area should be conserved, as they have the highest value coefficients. The accuracy of the value coefficient, however, needs to be studied further in future research.     

利用有效微生物菌群控制蓝藻水华研究

蓝藻水华污染在我国和世界都呈现迅猛的发展趋势,如何治理是环境科学研究领域的热点。2008年7～8月在北京市延庆县妫水湖的现场围隔水体中,通过投加筛选和培养土著有效微生物菌群(EM菌),对控制蓝藻水华污染形成的效果进行研究。结果表明,与对照相比,投加EM菌不仅可以控制蓝藻水华的暴发,使蓝藻生物量降低70%以上,而且可以快速降低水体中的氮和磷浓度,因此,明显控制了蓝藻水华的形成,在治理湖泊蓝藻水华污染方面具有重要的应用前景。     

城市污水厂污泥替代营养盐培养海水小球藻的研究

为了城市污水厂污泥的资源化利用,对污泥替代F/2培养基培养海水小球藻(Chlorella pacifica)进行了研究。首先采用研磨-离心法制备污泥抽提液,将其与F/2培养基按体积比7∶3混合,接种微藻并在优化的条件下培养6 d,逐日测定混合液中无机氮、磷的浓度,培养结束后测定微藻生物量以及干藻中蛋白质、氨基酸和重金属含量。结果表明,将微藻在最佳条件下培养6 d后,混合液中PO34--P、NO2--N、NH4+-N和NO3--N的吸收率分别达到97.32%、96.72%、97.55%和78.13%;与F/2培养基对照组相比,混合液中微藻的生物量增加11.5%;蛋白质、必需氨基酸和非必需氨基酸的含量变化不大。另外,干藻中的重金属含量符合饲料行业标准的要求。     

自来水污泥堆肥化研究

研究了自来水污泥脱水防粘预处理技术、高温好氧堆肥技术及其应用于园林种植效果。机械组成测定和电镜扫描结果表明,调理剂QS可以显著改善自来水污泥的粘结性及脱水性能;堆肥实验结果表明,预处理的自来水污泥与枯枝落叶按体积比3∶7混匀,加入尿素调节碳氮比,27 d后,可达腐熟,EM菌可以加快堆肥物料腐熟,19 d后,即可达腐熟要求;桉树盆栽实验结果表明,自来水污泥经堆肥化处理后,保水性提高,促进桉树生长,而且堆肥过程中添加EM菌可以进一步促进桉树生长。     

国内外冷却服的发展现状及关键技术

本文论述了国内外冷却服的发展现状,介绍了3种制冷技术路线,指出了其各自的关键技术,有利于人们对冷却服的发展趋势进一步的了解和认识.     

Properties of lightweight aggregate concrete prepared with PVC granules derived from scraped PVC pipes

This paper aims to investigate the fresh and hardened properties of lightweight aggregate concretes that are prepared with the use of recycled plastic waste sourced from scraped PVC pipes to replace river sand as fine aggregates. A number of laboratory prepared concrete mixes were tested, in which river sand was partially replaced by PVC plastic waste granules in percentages of 0%, 5%, 15%, 30% and 45% by volume. Two major findings are identified. The positive side shows that the concrete prepared with a partial replacement by PVC was lighter (lower density), was more ductile (greater Poisson's ratios and reduced modulus of elasticity), and had lower drying shrinkage and higher resistance to chloride ion penetration. The negative side reveals that the workability, compressive strength and tensile splitting strength of the concretes were reduced. The results gathered would form a part of useful information for recycling PVC plastic waste in lightweight concrete mixes.     

Concentration and composition variations of metals in the outdoor PM10 of elementary schools during river dust episodes

Aeolian river dust can seriously affect the air quality in central Taiwan. The main purpose of this study was to assess the concentration variations of PM₁₀ and metals at different elementary schools during river dust episodes. River dust samples were taken from eight sites in the main bare soil areas of the Choshui River. PM₁₀ aerosols from four elementary schools in Yulin County were collected by means of high-volume samplers. Fifteen elements (Fe, Al, Ca, Mg, Mn, Zn, Ti, Ni, V, Cr, As, Pb, Cu, Co, and Cd) in the river dust and PM₁₀ were analyzed in this study. The coefficients of divergence (CDs) were obtained by comparing the metal compositions in PM₁₀ aerosols at the four schools on the sampling days with the mean metal contents in the river soil samples as reference. The CD values showed that metal compositions in the aerosols at high-exposure sites during river dust episodes were similar to those compositions in the river dust. The concentrations of PM₁₀ at the high-exposure schools during river dust episodes were much higher than those during non-river-dust episodes. This study also indicated that at the high-exposure sites, both the PM₁₀ and metal concentrations were higher than at the low-exposure and control sites, not only during the river dust episodes, but also after the river dust episodes. The concentrations of toxic metals (Ni, Cr, As, and Cd) at the high-exposure sites were about 11.3 times higher during the river dust episodes (189 ng/m³) than during non-river-dust episodes (16.7 ng/m³) and about 8.9 times higher during the same periods at the control site (21.3 ng/m³).     

Annual input fluxes and source identification of trace elements in atmospheric deposition in Shanxi Basin: the largest coal base in China

Industrialization and urbanization have led to a great deterioration of air quality and provoked some serious environmental concerns. One hundred and five samples of atmospheric deposition were analyzed for their concentrations of 13 trace elements (As, Cd, Cu, Fe, Al, Co, Cr, Hg, Mn, Mo, Pb, Se, and Zn) in Shanxi Basin, which includes six isolate basins. The input fluxes of the trace elements in atmospheric deposition were observed and evaluated. Geostatistical analysis (EF, PCA, and CA ) were conducted to determine the spatial distribution, possible sources, and enrichment degrees of trace elements in atmospheric deposition. Fe/Al and K/Al also contribute to identify the sources of atmospheric deposition. The distribution of trace elements in atmospheric deposition was proved to be geographically restricted. The results show that As, Cd, Pb, Zn, and Se mainly come from coal combustion. Fe, Cu, Mn, Hg, and Co originate mainly from interactions between local polluted soils and blowing dust from other places, while the main source of Al, Cr, and Mo are the soil parent materials without pollution. This work provides baseline information to develop policies to control and reduce trace elements, especially toxic elements, from atmospheric deposition. Some exploratory analytical methods applied in this work are also worth considering in similar researches.