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91.
Bennett EM 《Environmental management》2003,32(4):476-487
Understanding the magnitude and location of soil phosphorus (P) accumulation in watersheds is a critical step toward managing runoff of this pollutant to aquatic ecosystems. Here, I examine the usefulness of urban–rural gradients, an emerging experimental design in urban ecology, for predicting extractable soil P concentrations across a rapidly urbanizing agricultural watershed in southern Wisconsin. I compare several measures of an urban–rural gradient to predictors of soil P such as soil type, slope, topography, land use, land cover, and fertilizer and manure use. Most of the factors that were expected to drive differences in soil P concentrations were found to be poor predictors of Bray-1 (extractable) soil P, which ranged from 4 to 660 ppm; while there were several significant relationships, most explained only a small proportion of the variation. A multiple linear regression model captured approximately 37% of the variation in the data using the urban–rural gradient, topography, land use, land cover, manure use, and soil type as predictors. There was a significant relationship between Bray-1 P concentration and each of the urban–rural gradients, but these relationships explained only between 2.6% and 3.3% of the variation in P concentrations. Extractable P concentration in soils, unlike some other ecosystem properties, is not well predicted by urban–rural gradients. 相似文献
92.
本文在对鉴湖水域保护工作历史回顾的基础上,分析了存在的主要问题,提出了在构筑“三大组团、绿色空间”城市框架中,加快鉴湖两岸城中村改造,建设“鉴湖生态林带”,形成联结越城、柯桥两大组团的“绿色生态走廊”的建议,重现“山阴道上走,如在镜中游”。 相似文献
93.
Anderson AB 《Environmental management》2002,29(3):428-436
The Land Condition Trend Analysis (LCTA) program is the US Army's standard for land inventory and monitoring, employing standardized
methods of natural resources data collection, analyses, and reporting designed to meet multiple goals and objectives. Critical
to using LCTA data in natural resources management decisions is the ability of the LCTA protocols to detect changes in natural
resources. To quantify the ability of LCTA protocols to detect resource changes, power analysis techniques were used to estimate
minimum detectable effect sizes (MDES) for selected primary and secondary management variables for three Army installations.
MDES for a subset of primary variables were estimated using data from 27 installation LCTA programs. MDES for primary and
secondary variables varied widely. However, LCTA programs implemented at larger installations with lower sampling intensities
detected changes in installation resources as well as programs implemented at smaller more intensively sampled installations.
As a national monitoring program that is implemented at individual installations, LCTA protocols provide relatively consistent
monitoring data to detect changes in resources despite diverse resource characteristics and implementation constraints. 相似文献
94.
The results of a study on morphophysiological variation in fish inhabiting a subarctic lake exposed to chronic industrial pollution are described using an example of cisco, Coregonus lavaretus. It is shown that indices of the heart, liver, kidneys, gills, and fatness in these fish are increased significantly and have retained increased values for the past 20 years. The observed changes are analyzed on the basis of biochemical data. The results of studies on the dynamics of hematological parameters in fish are used for characterizing the development of toxicosis. Adaptive rearrangements associated with an increase in the metabolic rate and the activation of protective systems in the fish are explained in the context of S.S. Schvarts' concept. The idea is proposed that the additional energy cost of detoxification may be responsible for morphophysiological variation in fish under conditions of water pollution. 相似文献
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97.
Peter E. Black 《Journal of the American Water Resources Association》1998,34(4):723-728
ABSTRACT: This paper explores a range of forest hydrology issues and identifies my concepts of the field's most pressing research needs. I extend the topic to include teaching and education in the broader sense because current teaching is usually part of the researcher's portfolio and because education involves that of both the research scientist and a broader audience. I consider the primary research, education, and service roles of the forest hydrologist also within a range of domains or, as I prefer to identify them, scales: (1) the molecular or pore level; (2) hydrological process; (3) watershed function; (4) global considerations, and (5) the human dimension which, while not actually a scale itself, embraces, is important to, and is affected by the first four. All are topics screaming for attention by researchers, educators, and practitioners. I shall here focus on the middle three. 相似文献
98.
木本植物休眠的诱导因子及其细胞内Ca2+水平的调节作用 总被引:9,自引:0,他引:9
本研究揭示 ,越冬木本植物在夏秋转变过程中对光周期变化十分敏感 .在北纬 4 5°的明尼苏达州圣保罗地区 ,当日照变短 72min时 (2 0 0 0年 8月 8日 ) ,桑树顶芽细胞质浆和细胞核内即出现Ca2 流入 ,而在夏天长日照时期 (7月上、中旬 )很少有Ca2 存在的细胞质和细胞核 .12d后 (8月 2 0日 ) ,观测到桑树和杨树芽已经开始进入生理休眠 .从 9月上旬到 11月中旬 ,细胞质和细胞核内的Ca2 浓度显著升高 ,11月中旬达到高峰 .与此同时 ,芽的生理休眠深度也迅速增加 ,并于 11月达到高峰 ,4 2d培养也不见萌芽迹象 .到 12月中旬 (12月 2 0日 ) ,细胞核和细胞质中的Ca2 浓度又恢复到夏季观察到的低水平 ,显示早先进入细胞质和细胞核中的Ca2 已经被排出 .此后 ,在 12月下旬 (2 5日 ) ,检测到生理休眠的终结 .室外补充光照实验进一步证明 ,只有日照缩短才会引发植物进入自然生理休眠 ;保持日照长度不变 ,晚夏时期的自然温度降低 ,不能诱导植株停止生长和进入休眠 .这些结果表明 ,越冬木本植物在晚夏到冬季的生理休眠发展过程中 ,日照缩短引起的核和质内Ca2 的流入不仅起着传递日照变短信号的作用 ,导致生理休眠的起始 ;而且 ,高水平的核 /质Ca2 浓度还起着发展和保持深度生理休眠的作用 .图版 1图 1表 2参 相似文献
99.
Study of urban population attitudes towards various wastewater reuse options: Israel as a case study
This paper summarizes the findings of a survey (256 participants) conducted to determine the attitude of the Israeli urban public towards various urban water reuse options. Israel is known for its long and successful agricultural water reuse scheme, but to date no large-scale urban reuse projects have been implemented. The survey included 21 reuse options, which were clustered into three reuse categories, namely: low, medium, and high contact levels. Results show that a high proportion of the participants supported medium contact reuse options such as sidewalk landscaping (95%), domestic WC flushing (85%) and firefighting (96%). Higher contact reuse options such as domestic laundry (38%), preserved food (13%), and potable aquifer recharge (11%) found much lesser support. Less than expected support was found for low contact reuse options with 86% for field crop irrigation, 62% for aquifer recharge for agricultural irrigation, and as low as 49% for orchard irrigation. This low support is surprising, since all three options have been practiced on a large scale for over three decades in Israel without any adverse effects to the public. No correlation was found between any biographical characteristic examined (education, gender, income, marital status, having young children, and age) and support for medium contact options. For the medium contact options, the results suggest that perceived financial gain (individual and/or communal) and positive public opinion enhances support, while perceived health effects negatively affects the degree of support. Technology, trust in authorities and awareness of water and environmental issues were found to not have a significant effect on support for medium contact reuse options. Analyzing the four possible reasons for support given by participants who identified themselves as supporters of wastewater reuse revealed that the most important reason for support was "water saving", followed by "minimization of importing water from abroad". These were followed by "infrastructure cost saving" together with "environmental improvement". 相似文献
100.