利用污泥熟肥作为高含水率污泥堆肥调理剂

采用静态强制通风好氧堆肥的方法,以木屑作为对比,考察了利用污泥熟肥作为调理剂对污泥堆肥过程的影响。结果表明,与以木屑作为调理剂的污泥堆体(对照组)相比,以污泥熟肥作为调理剂的污泥堆体(实验组)升温快,高温阶段(>50℃)持续时间长达10 d,满足粪便无害化卫生标准的要求,而对照组仅持续了2 d;实验组腐熟的堆肥含水率从60%降到39%,下降了21%,pH维持在7.5～8.5范围内,微生物活性较强,而对照组含水率仅下降15%,pH始终低于7.5;实验组种子发芽指数(GI)在第14天就回升到80%以上,基本上去除了植物毒性,而对照组GI在第22天才回升到50%。总体而言,污泥熟肥能显著改善堆肥中微生物的微环境,促进有机物的降解,缩短堆肥腐熟时间,是一种优质的调理剂。     

惊世奇闻:人蚁大厮杀

这是发生在100年前一种特殊战斗,但许多人都觉得好像是发生在昨天的故事。一个夏日的早晨,亚马逊河畔的一个农场。场长西蒙,站在他办公室的窗前,一边凝望着窗外的绿树红花,一边细心地倾听着。正在这时,警察前来通知说:"根据邻近地区得来的消息,有一个长约10公里、宽约5公里的褐色     

Soil warming effect on net ecosystem exchange of carbon dioxide during the transition from winter carbon source to spring carbon sink in a temperate urban lawn

The significant warming in urban environment caused by the combined effects of global warming and heat island has stimulated widely development of urban vegetations. However, it is less known of the climate feedback of urban lawn in warmed environment. Soil warming effect on net ecosystem exchange (NEE) of carbon dioxide during the transition period from winter to spring was investigated in a temperate urban lawn in Beijing, China. The NEE (negative for uptake) under soil warming treatment (temperature was about 5℃ higher than the ambient treatment as a control) was -0.71 μmol/(m².sec), the ecosytem was a CO₂ sink under soil warming treatment, the lawn ecosystem under the control was a CO₂ source (0.13 μmol/(m².sec)), indicating that the lawn ecosystem would provide a negative feedback to global warming. There was no significant effect of soil warming on nocturnal NEE (i.e., ecosystem respiration), although the soil temperature sensitivity (Q₁₀) of ecosystem respiration under soil warming treatment was 3.86, much lower than that in the control (7.03). The CO₂ uptake was significantly increased by soil warming treatment that was attributed to about 100% increase of α (apparent quantum yield) and A_max (maximum rate of photosynthesis). Our results indicated that the response of photosynthesis in urban lawn is much more sensitive to global warming than respiration in the transition period.     

Assessing Impact of Urbanization on River Water Quality In The Pearl River Delta Economic Zone, China

The Pearl River Delta Economic Zone is one of the most developed regions in China. It has been undergoing a rapid urbanization since the reformation and opening of China in 1978. This process plays a significant impact on the urban environment, particularly river water quality. The main goal of this present study is to assess the impact of urban activities especially urbanization on river water quality for the study area. Some Landsat TM images from 2000 were used to map the areas for different pollution levels of urban river sections for the study area. In addition, an improved equalized synthetic pollution index method was utilized to assess the field analytical results. The results indicate that there is a positive correlation between the rapidity of urbanization and the pollution levels of urban river water. Compared to the rural river water, urban river water was polluted more seriously. During the urban development process, urbanization and urban activities had a significant negative impact on the river water quality.     

稳定碳同位素示踪农林生态转换系统中土壤有机质的含量变化

为了观察生态系统的转变对土壤有机质的影响,在贵州茂兰喀斯特原始森林保护区内农林生态系统发生转变的地域,分析了土壤有机质含量和土壤有机质的δ¹³C值森林点土壤有机碳含量普遍较高(1.81%～16.00%),而农田点土壤有机碳含量在0.43%～2.22%之间,表明毁林造田加速了土壤有机质的降解,使土壤有机质总量减少;利用C₃植物与C₄植物δ¹³C值的显著差异,对比森林点与农田点的δ¹³C值(森林点:-23.86‰～-27.12‰;农田点:-19.66‰～-23.26‰),计算表明,毁林造田同时也降低了土壤有机质中活性大的组分的比例,使土壤肥力下降.     

Are servant leaders appreciated? An investigation of how relational attributions influence employee feelings of gratitude and prosocial behaviors

Multisource data collected at three time phases were used in investigating when servant leadership elicits gratitude and then promotes prosocial behaviors. We tested a moderated mediation model, contending that relational attributions moderate the relationship between servant leadership and gratitude, and then gratitude sequentially predicts interpersonal citizenship behaviors and upward voice. As hypothesized, when employees do not highly rely on relational attributions for servant leadership, they feel more gratitude and subsequently engage in more interpersonal citizenship behaviors and upward voice than the employees who rely on relational attributions to explain their interactions with the leader. The sequential indirect effect from servant leadership to upward voice via gratitude and then interpersonal citizenship behaviors was significant when relational attributions are low rather than high.     

Interactive effects of natural and human disturbances on vegetation dynamics across landscapes.

Accurate measures of human effects on landscape processes require consideration of both the direct impacts from human activities and the indirect consequences of the interactions between humans and the landscape. This is particularly evident in systems experiencing regular natural disturbances such as in the mountainous areas of southwestern China, where the remaining population of giant pandas (Ailuropoda melanoleuca) is supported. Here the spatiotemporal patterns of human impacts, forests, and bamboo episodic die-offs combine to determine the distribution of panda habitat. To study the complex interactions of humans and landscapes, we developed an integrated spatiotemporally explicit model of household activities, natural vegetation dynamics, and their impacts on panda habitat. Using this model we examined the direct consequences of local fuelwood collection and household creation on areas of critical giant panda habitat and the indirect impacts when coupled with vegetation dynamics. Through simulations, we found that over the next 30 years household impacts would result in the loss of up to 30% of the habitat relied on by pandas during past bamboo die-offs. The accumulation and spatial distribution of household impacts would also have a considerable indirect influence on the spatial distribution of understory bamboo. While human impacts influence both bamboo die-off and regeneration, over 19% of pre-existing low-elevation bamboo habitat may be lost following an episodic die-off depending on the severity of the impacts and timing of the die-offs. Our study showed not only the importance of the spatial distribution of direct household impacts on habitat, but also the far-reaching effects of the indirect interactions between humans and the landscapes they are modifying.     

铁屑微电解-共沉淀法处理屠宰场废水的研究

利用铁屑微电解-共沉淀法处理屠宰场废水,介绍其作用机理,考察了废水pH值、铁屑用量、反应时间、曝气时间和操作方式等因素对色度和CODCr去除率的影响.结果表明,在废水pH值为4,铁屑用量为15%,常温反应4 h,曝气时间2 h条件下,色度去除率可达100%,CODCr去除率达92.68%.     

水库温室气体排放及其影响因素

水库是温室气体的一个重要排放源.探讨水库温室气体排放及其影响因素有利于精确估算水库温室气体排放量、减少水利工程与水电开发过程中水库温室气体排放.本文阐述r水库中温室气体的产生机制.总结了水库温室气体的3个排放途径:水库自然排放、水轮机和溢洪道、大坝下游河流,从水库特征、气候、水体pH值、水库中植被状况等角度深入探讨了水库温室气体排放的影响因素.最后,重点分析了水库温室气体排放的空间异质性以及研究结果不确定性的产生根源,并对今后的研究重点进行了展望.