森林影响河川径流的流域因素

国内外所进行的小区或小流域试验表明,砍伐森林径流量增加,增加森林植被覆盖则径流量减少。但是,在大流域,砍伐森林并不一定能增加河川径流量。小面积试验得出的结论不适于推而广之到大的流域。其主要原因是流域因素——所处的自然气候地带、地质地貌特别是水文地质条件的不同。大面积种树种草或砍伐森林,对一个较大流域总水量的影响是比较复杂的。在什么样的条件下水量减少、增加或者变化不大,要对整个流域进行详细地调查和观测,只进行简单的小流域试验是不可能得出正确结论的。     

东海区小黄鱼总允许渔获量初探

根据1991~2003年中国渔业统计年鉴以及东海区渔业资源动态监测网各网站监测产量和捕捞努力量(投网次数)数据,通过同时期东海区小黄鱼产量对海区总捕捞努力量进行标准化,运用剩余产量模型中的Fox模型估算东海区小黄鱼最大持续产量(MS Y)、最适产量(Y0.1)和总允许渔获量(TAC)。结果表明,东海区小黄鱼的最大持续产量为116 565 t,相应捕捞努力量(fMSY)为4 988 315网次,最适产量为113 068 t,相应捕捞努力量(f0.1)为3 890 886网次,TACMSY=99 317 t,TAC0.1=77 468 t。建议以东海区小黄鱼总允许渔获量(TAC0.1)作为渔获量限额指标,对小黄鱼的总允许渔获量进行管理。     

村镇建设中农村污水处理设施的选择

有机废弃物是村镇环境的主要污染源,污水处理已成为村镇建设中亟待解决的问题。受经济发展水平限制,常规的污水处理设施在村镇难以实施,为此必须采用适合村镇经济水平和管理水平的污水处理方式。针对村镇的实施条件,在对几类小型简易污水处理设施特点进行分析的基础上,提出在村镇建设中易推行结构简单、费用低廉、便于管理、实施方便的沼气发酵池和地埋式无动力污水处理设施,以初步解决村镇污水问题。     

小水电资源区域开发环境影响回顾性评价案例分析——以海南省为例

在小水电资源区域开发规划环境影响报告书编制中应设置小水电资源区域开发环境影响回顾性评价专题,对规划区域小水电资源开发过程产生的环境问题进行调查和回顾性评价,从中发现小水电资源开发存在的环境问题,并提出规避的对策。海南省小水电资源开发规划环境影响报告书小水电资源区域开发环境影响回顾性评价专题案例。通过遥感影像判读及现场调查发现,选址不当、断流、减水、沙化、景观破坏、植被覆盖率降低及外来物种入侵、水土流失、用水矛盾、影响渔业资源等环境问题普遍存在,主要原因是环境行政管理虚位。主要对策有：在小水电资源开发规划及项目可行性研究报告中,应将环境法规符合性及环保投资列为重要内容;实施工程环境监理;加强竣工环保验收;将水电站下泄生态流量等环保措施执行情况的现场检查纳入常态工作范畴。     

小城镇污水处理厂升级改造技术分析

随着城镇化进程加快,经济快速发展的同时严重的环境污染问题随之出现,主要表现在小城镇污水处理率较低,各地区发展不平衡等方面。因此对小城镇的污水处理厂的升级改造势在必行。根据小城镇工业污水的特征及处理要求,提出了几种易于在小城镇推广的经济、高效、节能和简便易行的污水处理改造工艺。针对江阴市小城镇污水集中处理水质特点及工艺的进行研究,根据新的排放标准,提出与改造相应的技术组合思考,达到进一步改善小城镇污水处理效率的目的。     

小城镇环境保护规划现状及对策——以铁岭市八棵树镇为例

小城镇环境保护规划的编制是实现科学发展,积极探索中国农村环境保护新道路的必要举措。文章以铁岭市八棵树镇为典型,通过对环境现状及存在问题的分析,提出了八棵树镇环境保护规划,并为搞好小城镇环保规划和生态建设给出一些合理的对策和建议。     

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities: A laboratory study

A laboratory study was conducted to investigate volatile organic compound(VOC) emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition(5924 ng C/(kg·hr)) was significantly higher than that under the flooded condition(2211 ng C/(kg·hr)). One "peak emission window" appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis(DGGE) showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.     

Hydro-abrasive erosion in hydro turbines: a review

The flow of sediment particles in rivers is a big challenge to develop hydropower plants across the sediment-laden rivers. Hard particles such as quartz and feldspar are available in high amount in the Asian mountain range. The abrasive action of these particles causes the hydro turbines to suffer from erosion in particular at high- and medium-head hydroelectric power plants. This has become a serious economic issue due to maintenance costs and production losses. The treatment without prevention is simply unsustainable. Facilities for sediment exclusion, typically sand traps as well as turbine design, and materials have been improved considerably. In the present paper, studies have been discussed extensively undertaken by several investigators in this field. Based on literature survey several aspects related to reducing the sediment load on turbines, useful ways to improve the turbine surface performance and various erosion models to characterize the effect of erosion on the performance of turbines have been discussed. To calibrate and validate the developed erosion models, more measurements from both physical model tests in laboratories and continuous monitoring of sediment parameters and their impact on the operational hydro turbines are required. As well as the state-of-art in the modeling and simulation using computational fluid dynamics (CFD) has made it possible to optimize the hydraulic design of hydro turbines in order to minimize the erosion level without much sacrifice in the efficiency. To mitigate the hydro-abrasive erosion effects on the performance of turbines, significant improvements have been achieved so far and development is ongoing.     

基于节约法的村镇生活垃圾收运路线优化研究

为了降低垃圾收运成本,减少垃圾收运过程产生的环境和社会影响,对含有多种级别道路的村镇生活垃圾收运路线进行了优化。综合考虑垃圾收运过程的运输距离、路况、环境污染等因素,利用层次分析法确定了不同级别道路的综合权重,并对实际运输距离进行修正,得到综合运输距离。以节约综合运输距离为目标,使用节约法对收运路线进行优化,得出了节约路程多、发生拥堵少、环境污染小的村镇生活垃圾收运路线。并以蒙城县岳坊镇为例,对该地区的垃圾收运路线进行优化设计,验证了方法的可行性。     

复合式生物滴滤池技术在小城镇生活污水处理中的应用

介绍了几种常规污水处理工艺的基本情况,提出了复合式生物滴滤池污水处理工艺在处理小城镇生活污水方面具有的优势,并对实践中的应用效果进行分析。