Streamwater chemistry and flow dynamics along vegetation-soil gradient in a subalpine Abies fabri forest watershed, China

Streamwater chemistry and spatial flow dynamics from a subalpine Abies fabri forest in an experimental watershed located in the east slope of Gongga Mountain were analyzed to gain insights into the gradient effect of primary community succession on the stream biogeochemical process. Results showed that high sand content (exceeding 80%) and porosity in the soil(exceeding 20% in A horizon and 35% in B horizon), as well as a thick humus layer on the soil surface, made the water exchange quickly in the Huangbengliu (HBL) watershed. Consequently, no surface runoff was observed, and the stream discharge changed rapidly with the daily precipitation. The flow trends of base ions in the stream water were influenced by the Abies fabri succession gradient. Ca^2 , HCO3^- and SO4^2,- were the dominant anions in the streamwater in this region. A significant difference of Ca^2 , HCO3^- and SO4^2- concentration exported between the succession stages in the watershed can be found. But they had the similar temporal change in the stream flow. Ca^2 , HCO3^- and SO4^2- showed significantly negative correlations with the daily precipitation and the stream discharge. Concentrations of Cl^- , Na^ , K^ , and Mg^2 were low in all streamwaters monitored and we observed no differences along the Abies fabri succession gradient. Low ratios of Na. (Na Ca) (range from 0.1 to 0.2) implied cations were from bedrock weathering (internal source process in the soil system) in this region. But, a variance analysis showed there were almost no differences between rainwater and streamwaters for Mg^2 , Na^ , K^ , and Cl^- concentrations. This indicated that they might be come from rainfall inputs(external source). The highly mobile capacity, rapid water exchange between precipitation and discharge, and long-term export lead to this observed pattern were suggested.     

反应温度对自热式高温好氧消化(ATAD)中试系统运行的影响

城市污水污泥是城市污水处理厂的副产物,需要稳定化处理。本试验设计了由2个圆罐串联的自热式高温好氧消化中试系统处理城市污水污泥。通过批式试验探讨反应器温度对污泥稳定化处理效果的影响,以及影响反应器自升温的因素。试验发现①反应温度对挥发性的有机物的去除有显著影响,反应温度越高,VSS去除率越高。②影响反应温度的主要因素有进泥浓度、消化时间和曝气量。当进泥的VSS浓度为37.2g/L时,ATAD反应器最高温度可到49℃,只需14～17d的消化时间VSS的去除率可达到41.7%,污泥能达到稳定化。     

铁屑去除地下水中Cr6+的试验研究

以铁屑和纯Fe0为供试介质处理地下水中Cr6 ,在不调节原水pH值情况下,通过室内对比试验发现铁屑比纯Fe0的去除效率高,且可使处理后水中Cr6 达到地下水质量标准的Ⅲ类标准,确定出铁屑去除Cr6 的最佳运行参数:铁屑与Cr6 的重量比为1395:1,反应时间为40 min,并分析讨论了其去除机理.     

生物表面活性剂及其在环境修复中的研究进展

生物表面活性剂是由微生物分泌的天然产物,由于其物理性质和化学结构与许多人工合成的表面活性剂相似,并且对土壤、淡水、海洋等生态系统毒性较低,因而在环境污染治理方面,特别是在重金属和石油等有机溶剂污染的原位和异位生物修复方面具有极大的应用潜力.主要综述了近年国内外生物表面活性剂在廉价制备、作用机理、环境修复中的研究进展.     

微絮凝-超滤工艺处理微污染水源水的中试研究

进行了微絮凝-超滤工艺处理微污染水源水的中试研究.试验结果表明:在微絮凝-超滤工艺中,相同混凝剂投加量(相同金属摩尔浓度)下铁盐比铝盐的混凝效果好;微絮凝-超滤工艺的最佳絮凝时间为120 s左右;最佳混凝剂投加量为2.2 mg/L(以Fe计).微絮凝-超滤工艺在改善出水水质和缓解膜污染方面均优于直接超滤工艺.微絮凝-超滤工艺的出水水质均符合建设部<城市供水水质标准>(CJ/T206-2005)要求.     

负载型纳米TiO2光催化剂的制备及其光催化活性

采用悬浮聚合法制备粉煤灰-聚苯乙烯微珠载体,通过矿化接枝技术将水热法制备的纳米TiO2负载在粉煤灰-聚苯乙烯微珠载体上,制成负载型纳米TiO2光催化剂。用x射线衍射仪、扫描电子显微镜对负载型纳米TiO2光催化剂进行了表征;通过光催化降解甲醛实验评价了负载型纳米TiO2光催化剂的活性。实验结果表明,纳米TiO2在载体上分散良好,平均粒径为36．4nm;该催化剂活性较高,明显优于粉体纳米TiO2光催化剂,重复使用10次左右,该催化剂的活性无明显下降。     

Nonionic surfactant enhanced biodegradation of m-xylene by mixed bacteria and its application in biotrickling filter

In this study, m-xylene biodegradation was examined in bacteria-water mixed solution and biotrickling filter (BTF) systems amended with the nonionic surfactant Tween 80. The mixed bacteria were obtained from the activated sludge of a coking plant through a multisubstrate acclimatization process. High-throughput sequencing analysis revealed that Rhodanobacter sp. was the dominant species among the mixed bacteria. In the bacteria-water mixed solution, the bacterial density increased with increasing Tween 80 concentration. Hence, Tween 80 could be utilized as substrate by the mixed bacteria. Tween 80, with concentrations of 50–100 mg L^?1, could enhance the bioavailability of m-xylene and consequently improve the degradation efficiency of m-xylene. However, further increasing the initial concentration of Tween 80 would decrease the degradation efficiency of m-xylene. At concentrations exceeding 100 mg L^?1, Tween 80 was preferentially degraded by the mixed bacteria over m-xylene. In BTF systems, when the m-xylene inlet concentration was 1200 mg m^?3 and the empty bed residence time was 20 sec, the removal efficiency and elimination capacity of BTF1 with Tween 80 addition were at most 20% and 24% higher than those of BTF2 without Tween 80 addition. Overall, the integrated application of the mixed bacteria and surfactant was demonstrated to be a highly effective strategy for m-xylene waste gas treatment.

Implications: The integrated application of mixed bacteria and surfactant was demonstrated to be a promising approach for the highly efficient removal of m-xylene. Surfactant can activate mixed bacteria to degrade m-xylene by increasing its bioavailability. Besides, surfactant can be utilized as carbon source by the mixed bacteria so that the growth of mixed bacteria can be promoted. It is expected that the integrated application of both technologies will become more common in future chemical industry.     

Soil conservation practices and production efficiency of smallholder farms in Central China

The aim of this paper is to evaluate and analyze the impact of adoption of soil conservation practices (SCPs) on the technical efficiency of smallholder rice producers in Central China. We address self-selection bias and unobserved heterogeneity problems by estimating a switching regression model for the adoption decision function and separate stochastic production frontiers for SCP and Conventional farms while allowing for production inefficiency. SCP farms exhibit statistically higher average technical efficiency than Conventional farms. Education, extension services, membership in cooperatives, access to credit, and alternative income sources are positively and significantly associated with technical efficiency for both groups. Conventional farms display higher partial output elasticity for land, while only SCP farms show significant elasticity for capital.     

环保监测应急系统的发展及应用分析

随着我国社会的不断发展,人们生活水平的不断提高,人们对于资源的索取以及对环境的污染、生态的破坏都愈发的严重,雾霾、酸雨等极端、恶劣的天气频发,对人们的日常生活带来了严重的影响。近些年我国也逐渐开始意识到环境污染的严重后果,开始采取相应的环保监测以及环保措施来保护我们赖以生存的环境,而环保监测应急系统的运用就是其中之一。本文就针对环保监测应急系统在我国的发展以及应用进行了分析,并就其存在的问题以及注意事项进行了阐述,旨在为我国创造良好的生态环境提供一点帮助。     

太湖入湖河流中精神活性物质污染特征与生态风险

精神活性物质是一类摄入人体后对中枢神经系统具有强烈兴奋或抑制作用的新型污染物,其在水环境中的存在可能对水生生物、水生态系统甚至人体健康产生潜在的危害。为评价太湖中精神活性物质的污染水平和生态风险,利用超高效液相色谱-质谱联用法检测了太湖19条入湖河流中13种典型精神活性物质的质量浓度和空间分布规律。结果表明,在太湖19条入湖河流中除苯甲酰牙子碱(BE)和去甲氯胺酮(NK)外,其余11种目标物均有检出,质量浓度范围为n.d.～43.2 ng·L~(-1)。其中麻黄碱(EPH)的检出率和中间浓度最高,分别为100%和11.0 ng·L~(-1);其次为甲基苯丙胺(METH),检出频率为58%,浓度中值为1.0 ng·L~(-1);苯丙胺(AMP)在东部湖区均未检出。大部分精神活性物质浓度水平较高的河流分布在竺山湾和西太湖,而海洛因(HR)的高值区主要在南太湖。运用风险熵方法对其进行风险评估,结果显示,太湖流域地表水中检出的13种精神活性物质的风险熵值均<0.1,生态风险较低,但其对水生生态系统的长期和综合风险值得关注。