聚丙烯酸钠作为调理剂对好氧堆肥的保氮影响

实验以污泥、锯末、猪粪为原料,以聚丙烯酸钠(PAAS)为调理剂,利用自制好氧堆肥反应器,研究了PAAS在污泥好氧堆肥中的保氮效果。实验显示,PAAS会提高堆体的pH水平,抑制氨氮的生成,从而减少NH3的挥发源,在PAAS对水溶性氨的吸附作用下,堆肥产品的最终氨氮水平依然得到提高;PAAS对硝化反应有一定的促进作用,添加PAAS的堆体在堆肥周期内的硝氮平均增幅可达到未添加PAAS的空白堆体的4.64倍;添加PAAS的堆体在堆肥周期内全氮平均降幅只有空白堆体的52.24%。PAAS做为堆肥调理剂起到了较为明显的保氮效果。     

二氧化钛脱除高温烟气中的氯化氢

HCl是城市垃圾焚烧产生的主要气体污染物之一。将一种新型脱氯剂TiO2引入到垃圾焚烧系统中,并与其他脱氯剂的性能进行比较。研究了不同脱氯剂使用量、不同反应温度和不同HCl气体浓度对TiO2、CaO和CaTiO3脱氯效果的影响。结果显示,TiO2能在高温(800~1 000℃)、高HCl浓度(1 303.6~1 629.5 mg/m3)下获得较好的脱氯效果。与传统的脱氯剂CaO相比,TiO2更适合于高温烟气脱氯,其在1 000℃时的氯容(36.3 mg HCl/g TiO2)几乎是相同情况下的CaO氯容(9.3 mg HCl/g CaO)的4倍。而CaTiO3的脱氯效果不但受到自身分解效率的影响,还受到TiO2和CaO脱氯效果的影响,其脱氯效果较差。     

Effects of dimethoate on rotifer Brachionus calyciflorus using multigeneration toxicity tests

As important members of the zooplankton community and sources of food for fish, rotifers are used extensively in ecotoxicological research to assess the health of the environment and safety of compounds. However, most rotifer toxicity tests are only conducted using rotifer neonates derived from unexposed mothers, thus ignoring the potential transfer of contaminants from mother to offspring. To understand better the mother to offspring exposure, a multigenerational study was conducted using three successive generations (F₀, F₁ and F₂) of the common freshwater rotifer Brachionus calyciflorus to investigate the toxic effects of the widely used organophosphate pesticide, dimethoate (O, O-dimethyl S-methylcarbamoylmethyl phosphorodithioate). When the F₀ generation was exposed to five pesticide concentrations, the population growth rate (r) displayed symptoms of hormesis, characterized by the conversion of low-concentration stimulation to high-concentration inhibition. Despite this observation, the exposure to any given concentration of dimethoate reduced the population growth rates of the F₁ and F₂ generation rotifers. Significant differences existed between the F₀, F₁ and F₂ rotifers for the population growth rate under dimethoate stress: F₂ individuals were more sensitive than F₁, whereas the F₁ individuals were more sensitive than F₀. The results indicated that the parental exposure to a given toxic stress could result in increased sensitivity and decreased fitness in the offspring. This study illustrates the utility of multigenerational toxicity tests, which may better reflect and more accurately predict the effects of long-term pesticide exposure to aquatic organisms at the population level.     

The Wind-Frequency Allocation Method on Discharge Loading of Function Zones

Abstract

This paper introduces a new allocation method on discharge loading of each function zone in a total emission control region. The wind frequency, the position of each district, and the pollutant’s influence area were taken into account in this new method. The concept of “average downwind distance” was brought forward in this paper. The method here is more reasonable than the original method of area distribution, which was proposed by the “A-value” method in regulation of total emissions in China, by means of the simulation of annual average concentration in the total emission control region.     

Causes of decreased reference evapotranspiration and pan evaporation in the Jinghe River catchment, northern China

This study focused on the changes of reference evapotranspiration (ET₀) and pan evaporation (ET_pan) to study the impacts of climate change on the hydrological cycle in the Jinghe River catchment. Based on the Penman–Monteith equation, the ET₀ was calculated. The temporal trend and spatial distribution of ET₀ and E_pan measured with a 20-cm pan were examined at the 14 stations during 1957–2005. The effects of meteorological factors on the variation of ET₀ were determined by analyzing the trends in themselves with comparison between original climate and detrended climate scenarios and then their sensitivity to ET₀. Both the ET₀ and E_pan showed remarkable decreasing trends from 1957 to 2005 and their decreasing rate was 40.9 and 17.7 mm per 10 years, respectively. Trend analysis of meteorological factors exhibited that the reduction in ET₀ and ET_pan was principally caused by both significant decreases in wind speed and sunshine hours. Furthermore, the decreasing trend of ET₀ was mainly dominated by the significant decrease in wind speed with high sensitivity, to a less extent, by the decrease in net radiation. Although relative humidity is one of the most sensitive variables, its effect on ET₀ was negligible because of its temporal constancy. The contribution of wind speed reduction to decreased ET₀ has increased from 50 to 76.1%, but net radiation, by contrast, decreased from 50 to 23.9%.     

污泥中重金属的稳定化研究进展与去除方法简述

通过"十一五"污水处理厂的建设,我国污泥产量也随之大幅增长,污泥的处理处置已经成为制约社会经济发展的重要问题。国际上的经验表明土地利用是污泥最终处置的主要发展方向,然而污泥中的重金属成为其土地利用的主要障碍。越来越多的研究者意识到,重金属的环境危害不仅仅取决于其总量,更取决于重金属存在形态。目前,Tessier分步提取法作为主流的污泥重金属划分方法,取得了广泛应用,该法将污泥中的重金属分成5种形态,分别为可交换态、碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态。本文以此为基础综述了目前国内外主要的污泥重金属稳定和去除方法的原理及研究进展,比较了不同重金属稳定及去除方法的优点与不足,并提出了新的展望。     

重庆乡村旅游发展的实证分析

在我国提出大力发展乡村旅游的背景下,乡村旅游已成为社会主义新农村建设和城乡统筹发展的主要内容,并成为解决“三农”问题的一条重要途径。由于乡村旅游良好的“城乡联动”机制和广阔发展前景,将成为重庆城市带农村发展的重要举措。但从旅游学的角度看,乡村旅游产品具有一般旅游产品的特征,其发展历史较短而速度过快,已出现了众多棘手的问题。通过对重庆市乡村旅游资源及其发展现状分析,对发展中存在的问题进行了重点分析,从规划编制、精品培育、设施完善、资源保护、市场拓展、人才培养、示范带动等方面对乡村旅游发展对策进行了探讨。     

作业机废气减排技术研究

柴油发动机尾气排放中含有比汽油发动机更多的颗粒污染物。文章叙述了尾气净化装置反应原理,触媒及化学稳定性,柴油氧化催化剂和颗粒催化过滤器优点。通过外部加装尾气净化装置,解决了尾气污染问题,具有较好的发展前景、较强的实用性和可操作性。     

油井远程监控与综合评价系统开发

为解决油田管理中面临的用工总量多、生产建设成本高和管理难度大的问题,胜利油田进行了大规模数字化建设。通过电参数、示功图、产液量自动采集传输,对油井进行综合评价分析,提出节电意见,确保油井安全正常运转,有效地减少了油田生产用工需求,进一步促进了油田管理的现代化。     

海上平台采油工艺设计浅析

文章通过实例,简要阐述了滩海、浅海、深海三种开发模式的特点、主要工艺及其适用性。指出各自存在的问题,并提出相应的建议,为海上勘探开发提供借鉴。