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181.
分光光度法快速测定水中的COD 总被引:2,自引:0,他引:2
本实验改用小样本恒温箱加热,用分光光度法分析水中的 COD,与标准重铬酸钾法,库仑法比较,具有设备简单,操作方便、节省水、电,及同时分析批量样品等优点。 相似文献
182.
我国小城镇水污染控制战略的思考 总被引:6,自引:0,他引:6
我国广大小城镇的水污染形势目前正处在加刷状态,而由于我国小城镇的具体国情,决定了小城镇的小污染不能采取与大中城市“同构”的控制措施,本文结合我国小城镇的具体特点,从战略角提出了以建设生态型小城镇为导向,以控制乡镇企业水污染为核心,以控制导流-生态工程为最终出路的小城镇水污染控制模式。 相似文献
183.
介绍了一种针对小流量污水现场处理的工艺--OxiSequencer。解释了工艺的基本原理、特点和应用等情况。说明OxiSequencer是一种适于分散小流量污水现场处理的系统。 相似文献
184.
185.
Importance of Assessing Population Genetic Structure before Eradication of Invasive Species: Examples from Insular Norway Rat Populations 总被引:2,自引:0,他引:2
JAWAD ABDELKRIM†‡ MICHEL PASCAL† CLAIRE CALMET SARAH SAMADI 《Conservation biology》2005,19(5):1509-1518
Abstract: Determining the inter-island migration abilities of pest species and delimiting eradication units enable more viable long-term eradication campaigns because recurrent colonization from neighboring islands is avoided. We examined the genetic structure of the invasive Norway rat ( Rattus norvegicus ) to identify gene flow between islands and delimit population units at different geographical scales. We investigated variation in eight microsatellite loci in rat populations from 18 islands, representing five archipelagos off the Brittany coast (France). Although most of the islands are isolated from each other, short genetic distances, weak FST values between close islands, and a high level of cross-assignment showed that individuals collected on different islands could represent a single population unit. A Bayesian clustering method also supported the existence of high levels of gene flow between some neighboring islands. Thus, the statement "one island equals one population" can be false when inter-island distances are less than a few hundred meters. Genetic studies enable the definition of island clusters among which migration may occur that should be considered eradication units. To avoid reinvasion and to minimize ecological and economic costs, rats on all islands in an eradication unit should be eradicated simultaneously. We suggest that the genetic monitoring we performed here can be applied for management of any pest. 相似文献
186.
Nicos S. Margaris 《Environmental management》1992,16(5):569-574
The development of intensive agriculture in the plains of mainland Greece provides products with lower cost than those obtained
from terrace agriculture in the islands. The result is the abandonment of the islands' agriculture followed by collapse of
the traditional agropastoral systems of management. When fires and overgrazing follow, desertification becomes a new reality
in the islands of the Aegean. 相似文献
187.
Population viability analysis as a tool in wildlife conservation policy: With reference to Australia
David B. Lindenmayer Tim W. Clark Robert C. Lacy Virginia C. Thomas 《Environmental management》1993,17(6):745-758
Wildlife conservation policy for endangered species restoration follows a six-phase process. Population viability analysis
(PVA) can play a major contributing role in four of these. PVA, as discussed here, is a technique where extinction vulnerabilities
of small populations are estimated using computer simulation modeling. The benefits and limitations of using PVA in wildlife
decision and policy processes are reviewed based on our direct experience. PVA permits decision makers to set time frames
for management, estimate the required magnitude of restoration efforts, identify quantitative targets for species recovery,
and select, implement, monitor, and evaluate management strategies. PVA is of greatest value for rare species policy and management.
However, a limitation of PVA simulation models is that they are constrained by the amount of biological data available, and
such data are difficult to obtain from small populations that are at immediate risk of extinction. These problems may be overcome
with improved models and more data. Our experience shows benefits of PVA far outweigh its limitations, and applications of
the approach are most useful when integrated with decision analysis and completed within an adaptive management philosophy.
PVAs have been carried out for 14 Victorian species and less used elsewhere in Australia. Management and recovery plans are
developed from these PVAs. We recommend that PVA be used to guide research programs, develop conservation strategies, and
inform decision and policy making for both endangered and nonendangered species because it can significantly improve many
aspects of natural resource policy and management. 相似文献
188.
Maryanne Heafey 《Journal of Environmental Planning and Management》1989,32(1):35-42
The paper reports the study of a group of twenty‐two new firm founders in the retail sector, in the Merchant City, an historic part of inner Glasgow that has recently undergone a miraculous revitalisation in a vein similar to that of the Docklands areas of London and Liverpool. The principal aim is to indicate how far the long term unemployed will be involved in this particular part of the enterprise culture, whether directly, or indirectly as a result of expanded employment opportunities. The results provide an upper limit of what we could expect this type of economic development to achieve in less attractive areas. The study provides a useful comparison to previous work concentrated on the manufacturing sector and suggests that the results from such work apply across sectors. 相似文献
189.
Jay M. Ver Hoef 《Environmental and Ecological Statistics》2008,15(1):3-13
Classical sampling methods can be used to estimate the mean of a finite or infinite population. Block kriging also estimates
the mean, but of an infinite population in a continuous spatial domain. In this paper, I consider a finite population version
of block kriging (FPBK) for plot-based sampling. The data are assumed to come from a spatial stochastic process. Minimizing
mean-squared-prediction errors yields best linear unbiased predictions that are a finite population version of block kriging.
FPBK has versions comparable to simple random sampling and stratified sampling, and includes the general linear model. This
method has been tested for several years for moose surveys in Alaska, and an example is given where results are compared to
stratified random sampling. In general, assuming a spatial model gives three main advantages over classical sampling: (1)
FPBK is usually more precise than simple or stratified random sampling, (2) FPBK allows small area estimation, and (3) FPBK
allows nonrandom sampling designs. 相似文献
190.
Over the last three decades, China’s coal industry has achieved dramatic increases in coal production, both in absolute terms and relative to the world as a whole. This achievement is due largely to its coal policies. Yet facing increasing pressures of environmental sustainability and market transition, the Chinese government was forced to make deep reforms and adjustments to regulate the coal industry effectively. This paper presents an historical overview of China’s coal economic policies, paying particular attention to the current reform policy of closing mines and restricting the yield for the small coal mines (SCMs) in the context of economic theories and methods. We argue that the SCM closure policy would not likely be efficiently enforced if a feasible market mechanism were not built up. The failure of closure policy is due largely to problems of property rights, coal pricing, ownership, and objectives. 相似文献