风电场风机噪声监测方法初探

据现场实测,风电场300 m范围内社会噪声测值水平较低,且昼夜变化较小,对风电场背景噪声贡献不大;风机停运时背景噪声值随风速递增,二者之间存在较好的多项式回归性。在测得风机运行时噪声值和测点风速的情况下,根据回归方程式得到背景噪声,当风机运行时测得的噪声值与背景噪声之差大于1.5 dB(A)时,可以运用噪声叠加原理计算风机噪声,并且其计算误差在可接受范围之内。     

THE OPPORTUNITY COST OF TIME AND AVERTING EXPENDITURES FOR SAFE DRINKING WATER1

ABSTRACT: A survey of individuals during a Giardia contamination incident provided data to calculate the cost of boiling, hauling, or purchasing water to avoid infection. Three different approaches to the valuation of time were used to assess the implications of the opportunity cost of time for the measurement of averting costs. Mean monthly household averting costs were $33.47 using family income to value time, $13.07 using the minimum wage to value time, and $5.60 using zero opportunity cost of time. Comparisons of the mean costs for different sources and household characteristics indicated the value of time from family income was too high and that the other methods of valuing time were superior.     

城郊菜园土污染状况调查与评价

南京市郊菜园土中Ａｓ、Ｈｇ、Ｃｄ、Ｐｂ四种元素的含量呈逐年上升趋势。除Ａｓ外，其余３种元素的含量均为土壤背景值的２￣３倍。综合评价表明，供试土样中约５０％以上的样点不再适宜种植蔬菜作物而只宜作林业用地或城建、道路及工矿用地。     

SBR用于高浓度有机污水的处理——单级与两级处理系统的比较研究

对单级和两级序批式反应器 (SBR)用于牛场高浓度有机污水的处理进行了试验研究 ,对其污水处理性能进行了比较。结果表明 ,与单级SBR相比 ,两级SBR处理系统可使用较短的水力停留时间而获得较高的污染物去除率和较好的出水水质 ,并可通过硝化过程实现氨氮的完全硝化。     

养猪场恶臭污染的预测模型及感官评估研究

现代化、集约化养殖技术促进了养猪业的高效发展,但养殖过程中产生的恶臭污染对环境的影响也逐渐显露出来.为正确识别养猪场恶臭物质组成、建立基于关键致臭物质的恶臭气体预测模型、感官评估恶臭对人产生的心理影响,对天津市某养猪场母猪舍、育肥舍及舍外的恶臭气体进行采样.应用GC-MS,分析物质组成;根据阈稀释倍数计算结果,确定关键致臭物质;通过研究各组分对复合恶臭的影响,建立复合恶臭气体预测模型;结合臭气浓度与人群实际心理感受,提出养猪场厌恶临界点.结果表明:①该养猪场共检出恶臭物质48种,各类型恶臭物质质量分数大小依次为w（氨）> w（含氧烃）> w（硫化物）> w（烷烃）> w（卤代烃）> w（烯烃）> w（芳香烃）.②该养猪场关键致臭物质为氨与乙醇,其中氨对复合臭气浓度的影响最大.③养猪场复合恶臭气体预测模型为O=0.34I₁+0.75I₂+5.81（其中,O为复合臭气浓度指数,I₁、I₂分别为乙醇和氨的恶臭气体指数）,经实际样品检验该模型具有良好的预测效果.④养猪场气味属厌恶范畴,厌恶程度随臭气浓度的增加而增强.⑤养猪场厌恶临界点为13,即臭气浓度大于13时,就会对人群产生干扰.研究显示,养猪场恶臭气体组成复杂,对人群的干扰可以用愉悦度进行评价,根据关键致臭物质可以预测感官恶臭污染.      

Reclamation of abandoned shrimp pond soils in southern Thailand for cultivation of Mauritius grass (Brachiaria mutica)

A study on soil reclamation for cultivation of Mauritius grass was conducted on soils obtained from abandoned shrimp ponds at Ranote District, Songkhla Province, southern Thailand. A glass house experiment on the reclamation of the soils included desalination by leaching soils using various amounts of deionised water, rice husk, plant nutrients and gypsum as well as an omission pot trial experiment. The result showed that Mauritius grass survived in the treatment with 15 L of water, 2% of rice husk with gypsum added or 8% of rice husk without gypsum added. The yield of Mauritius grass increased with increases in the amounts of water for desalination and rice husk. Thus, the highest yield of grass with a height of 148.3 cm, 12.7 tillers/pot and dry weight of 46.43 g/pot was observed in the gypsum added treatment with the highest amount of water and rice husk (25 L of water and 8% by weight of rice husk). Therefore, salinity and unfavourable structure of the abandoned pond soils were major factors governing the survival ability and growth of the grass. The omission pot trial experiment revealed that growth of the grass responded to the application of P, Ca, Mg and S, though existing amounts of such plant nutrient elements in the soils were adequate for plant growth. The anomalous characteristics were probably explained by soil pH, salinity and imbalance of plant nutrient elements.     

Groundwater quality: Responsible agriculture and public perceptions

The chief sources of groundwater contamination on farms come from point sources and diffuse sources. Possible point sources are feedlots, poorly-sited manure piles, septic sewage-treatment systems—all of which can release nitrate, phosphates and bacteria— and sites of chemical spills. Diffuse sources are typified by excess fertilizer leaching from a number of arable fields. The basis of quality standards for drinking-water is discussed in relation to common contaminants present on farms. Samples of drinking-water were collected in 1991–1992 from wells on about 1,200 farms in order to study the quality of rural groundwater in Ontario. Analysis showed that approximately one third of wells were contaminated with bacteria, 14% were contaminated with nitrate, two wells were contaminated with pesticide, but 40% were considered unsafe because of the presence of at least one contaminant. These values were similar to those reported for similar regions in the U.S. There was no significant effect of agricultural practice on the proportion of contaminated samples. One response of Ontario's farmers to information on water quality has been to initiate their own program, the Environmental Farm Plan, which has 23 modules by which the risk of environmental contamination can be assessed. Government policies for agriculture can be expected to influence farming practices. However, the literature suggests that the consequences of policies aimed at reducing environmental contamination are poorly understood, not least because the instruments used for implementation can have widely differing impacts. The need for discussions on the ethics surrounding the relationship between food producers and consumers with regard to environmental contamination is identified.     

Emission of nitrous oxide from rice-wheat systems of Indo-Gangetic plains of India

Nitrous oxide (N₂O) accounts for 5%of the total enhanced greenhouse effect and responsiblefor the destruction of the stratospheric ozone. The rice-wheat cropping system occupying 26 million ha ofproductive land in Asia could be a major source ofN₂O as most of the fertilizer N in this region isconsumed by this system. Emission of N₂O asinfluenced by application of urea, urea plus farm yardmanure (FYM), and urea plus dicyandiamide (DCD), anitrification inhibitor, was studied in rice-wheatsystems of Indo-Gangetic plains of India. Total emissionof N₂O-N from the rice-wheat systems varied between654 g ha^-1 in unfertilized plots and 1570 g ha^-1 in urea fertilized plots. Application of FYM and DCDreduced emission of N₂O-N in rice. The magnitude ofreduction was higher with DCD. In wheat also N₂O-Nemission was reduced by DCD. FYM applied in rice had noresidual effect on N₂O-N emission in wheat. In riceintermittent wetting and drying condition of soilresulted in higher N₂O-N emission than that ofsaturated soil condition. Treatments with 5 irrigationsgave higher emissions in wheat than those with 3irrigations. In rice-wheat system, typical of a farmer'sfield in Indo-Gangetic plains, where 240 kg N isgenerally applied through urea, N₂O-N emission is1570 g ha^-1 (0.38% of applied N) and application ofFYM and DCD reduced it to 1415 and 1096 g ha^-1,respectively.     

浅析山地型风力发电场生态环境影响

随着中国风电产业的迅速发展,风电场建设越来越多,风电场的建设对调节能源结构,减轻环境污染,减少温室气体排放,缓解电力紧张都有着重要的意义.风力发电对生态环境的不利影响主要表现在施工期和运行期,施工期生态影响为植物量损失,运行期生态影响为对鸟类和景观影响.以五凤山风电场为例,探讨了山地型风电场对生态环境的影响.主要为对植被、鸟类和景观的影响,并提出了有效的环境保护措施.     

Using deep-belief networks to understand propensity for livelihood change in a rural coastal community to further conservation

Overharvesting of terrestrial and marine resources may be alleviated by encouraging an alternative configuration of livelihoods, particularly in rural communities in developing countries. Typical occupations in such areas include fishing and farming, and rural households often switch livelihood activities to suit climate and economic conditions. We used a machine-learning tool, deep-belief networks (DBN), and data from surveys of a rural Philippine coastal community to examine household desire to change livelihood. This desire is affected by a variety of factors, such as income, family needs, and feelings of work satisfaction, that are interrelated in complex ways. In farming households, livelihood changes often occur to diversify resources, increase income, and lessen economic risk. The DBN, given its multilayer perceptron structure, has a capacity to model nonlinear relationships among factors while providing an acceptable degree of accuracy. Relative to a set of 34 features (e.g., education, boat ownership, and work satisfaction), we examined the binary response variables desire to change work or not to change work. The best network had a test set accuracy of 97.5%. Among the features, 7 significantly affected desire to shift work: ethnicity, work satisfaction, number of persons in a household in ill health, number of fighting cocks owned, fishing engagement, buy-and-sell revenue, and educational level. A cross-correlation matrix of these 7 features indicated households less inclined to change work were those engaged in fishing and retail buying and selling. For fishing, provision of economic and other incentives should be considered to encourage changing from this occupation to allow recovery of fishery resources.