A Sensitivity Analysis of Nitrogen Losses from Dairy Farms

International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms.     

填料式浮选柱操作参数的研究

在实验室装置上研究了不锈钢波纹板填料柱的主要操作参数对除油率的影响。研究结果表明：填料可以明显改善气体在柱内的径向分布，可以明显提高浮选柱的操作稳定性。实验确定了波纹板填料式浮选柱的主要操作参数是：最低气体表现线速度3．8cm／s，污水停留时间为5min，浮选剂投加量为5～10mg／L。     

PREDICTIVE MODEL FOR NITRATE LOAD IN THE BULL RUN WATERSHED,OREGON1

ABSTRACT: Predictive models for nitrate in four streams in the Bull Run Watershed in the Cascade Mountains of Oregon were developed from a record of 17 years of nitrate samples. The models are time series regression models written in terms of Log(nitrate load). The independent variables are logarithm of 14-day mean daily stream discharge, current day's precipitation, logarithm of the previous day's precipitation, total precipitation for the previous seven days, a hydrograph position variable that indicates rising or falling limb, and average maximum air temperature for the preceding 14 days. The models describe annual cycle and seasonable trends and variations in nitrate load, but are unable to describe large day to day variations like those associated with hydrograph peaks.     

1996年2月3日云南丽江7.0级地震震害调查和损失评估

对1996年2月3日云南丽江7．0级地震进行了震害调查和损失评估，此次地震造成了重大灾害，死亡309人，重伤4070人，轻伤12987人。房屋破坏、室内财产和生命线工程的直接经济损失总计为30．49亿元。     

新疆伽师6级强震群综述

本文对伽师成丛发生强震的机因，伽师地震的预报以及地震灾害损失与应力场状态等给出了结果。并就伽师地区防震减灾对策和重建问题提出了讨论及具体对策意见。     

Quantitative Assessment of the Intertidal Environment of Kuwait I: Integrated Environmental Classification

Quantitative analysis of physical, chemical and biological data of the intertidal zone in Kuwait was undertaken to develop an integrated basis for assessing and protecting this sensitive coastal ecosystem. Cluster analyses were performed to determine the resemblance between the sampling stations based on the sediment composition, the benthic macrofauna and the physico-chemical characteristics of the intertidal sediment/water. Five distinct sub-environments were delineated within the intertidal zone of Kuwait. Each sub-environment was described in terms of number of taxa, mean density of organisms, sediment type, tidal level and dominant organisms. The physico-chemical parameters investigated were found to be unimportant in the distribution of the intertidal benthic macrofauna. On the other hand, sediment type was found to be a major factor in the overall composition of the benthic community. The benthic fauna and related characteristics of the sub-environments could be used as indicators to monitor changes in the intertidal ecosystem and as guides to protection and management of the different coasts. The approach described in this paper could also be adopted elsewhere to provide a sound basis for evaluating environmental impacts and for developing sustainable coastal management.     

The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

燃煤锅炉排烟脱硫技术

本文介绍了治理燃煤排烟除脱ＳＯ２的主要技术和工艺流程，并对其进行了比较。     

Review of information on pesticide residues in the Canadian environment

Summary Pesticide residues in soil, water, food, wildlife and other media have been analysed in several monitoring studies. The purpose was to establish the distribution of these residues across a defined area, ascertain their trend over a specific period and use the results to assess environmental compliance and safety. In the present review the availability of information on pesticide residues in various Canadian environmental components was sought. With the possible exception of localized pesticide contamination of some private water supply wells, ground and surface water, most analyses revealed concentrations below guideline limits. Only a few cases were reported of mishandling, misuse and poisoning from pesticides. Continuing surveillance programmes and in-depth and well-organized monitoring studies, with special focus on areas that are vulnerable to contamination, by both provincial and federal governments, are largely responsible for the encouraging results. This experience in the control of pesticide use and monitoring of residues in the environment should be of particular interest in developing countries.Dr A.Y. Sangodoyin is a senior lecturer in the Department of Agricultural Engineering at the University of Ibadan. He was recently involved in a study visit to the University of Alberta, Edmonton, Alberta, Canada T6G 2G7, where his co-author Dr D.W. Smith is a member of staff in the Department of Civil-Engineering.