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The Peruvian altiplano is a marginal agricultural region with limited infrastructure, climate constraints, and high levels of poverty. Data were collected from 265 farms in four different agricultural regions, and data from three of those regions are analyzed here. Regressions were run with soil nutrient loss, soil depth loss, and yield loss over the past 20 years, as perceived by farmers. Location, topographical and management factors were considered. Additional regressions were run to examine the determinants of two agricultural management practices which were found to affect soil quality, namely fallowing and ploughing vertical furrows. Use of traditional fallowing (aynoca) was associated with helping to preserve soil quality, and was practiced by households with more education, with higher non-farm income, and in villages which had benefitted from natural resource development projects. Vertical furrowing similarly was associated with helping preserve soil quality, and was practiced by households with fewer unmet basic needs. These results have implications for the agricultural and development strategies to be followed in the region. 相似文献
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V. A. Yakovlev 《Russian Journal of Ecology》2002,33(4):268-272
Classification of the mode of life and behavior of zoobenthic, nektobenthic, and neustonic organisms was used as a basis for elucidating the formation of ethological structure of their communities in small lakes and streams of northeastern Fennoscandia. It is shown that the general response of these communities to anthropogenic impact is manifested in the reduction of the number of ethological groups. The specific response to eutrophication and heat pollution involves a decrease in the relative biomass of clingers and burrowers and an increase in the biomass of sprawling–walking and wormy animals; the response to toxic pollution and acidification is manifested in the prevalence of sprawlers–walkers. 相似文献
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Serena Risica 《Chemistry and Ecology》1996,12(4):225-230
Following a similar project performed for the Northern European Seas in the years 1985-1990, a study on the radioactive contamination of the Mediterranean Sea has recently been conducted by a group of experts of the European Union (MARINA-MED Project). Its aim was to assess the radiological exposure of the population of the European Union, due both to natural and man-made radionuclides in the Mediterranean Sea. A review of the conclusions of this study is presented, with special attention to the environmental radioactive data. the Italian radioactive monitoring organisation is described. Starting from this experience, some proposals for new research projects are presented. 相似文献
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根据几十年来武汉东湖水质监测资料和数据 ,在东湖截污工程完成后 ,没有新的污染物进入水体的前提下 ,对东湖水体通过自然净化恢复到健康状态所需要的时间进行了详细的数学推导和科学论证。结果表明 ,在不考虑地泥营养物质的情况下 ,东湖水体通过工业、农业、生活用水以及收获鱼类和高等植物造成的营养物的输出 ,只需要 3a左右的时间就能恢复。然而如果考虑地泥的影响 ,几十年沉积在地泥的营养物质持续向水体中释放 ,然后再通过用水及生物输出 ,东湖水质需要35a以上才能得到恢复。可见 ,截污后东湖在相当长的时间内还将处于富营养化状态 ,地泥是造成东湖长期富营养化的关键。解决东湖污染问题的关键是清除地泥 ,因此得出结论 :挖底泥后引入长江水源来加速东湖水体改善的最佳途径 相似文献
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Vegetative mercury emissions were estimated within the framework of Biogenic Emission Inventory System (BEIS3 V3.11). In this estimation, the 19 categories of U.S. Geological Survey landcover data were incorporated to generate the vegetation-specific mercury emissions in a 81-km Lambert Conformal model grid covering the total Chinese continent. The surface temperature and cloud-corrected solar radiation from a Mesoscale Meteorological model (MM5) were retrieved and used for calculating the diurnal variation... 相似文献
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盐城市沿海的适宜开发空间选择研究 总被引:2,自引:1,他引:1
开发空间选择通过辨识适宜开发空间,使得工业发展、城市建设活动尽可能地配置在弱自然生态阻力、强经济引力的空间,实现区域生态、经济效益的最大化。借鉴以往研究,结合案例区特点,建立指标体系,基于乡镇单元,运用GIS工具综合分析盐城市域自然生态阻力和经济引力的空间分异特征,运用矩阵列联分类方法划分空间开发适宜类型,并根据适宜开发空间的地域特点将其分为城市区域和临港区域。研究认为,盐城沿海的适宜开发空间主要分布于204国道沿线的县市城区、部分临近乡镇及沿海陈家港、滨海港、海通镇等地区;临海部分乡镇凭借其资源潜力宜作为临港区域,是未来的主要产业空间载体;其它地区应定位于城市化空间,未来建设用地指标应优先向这些区域投放,引导人口、产业向这些地区的集聚。 相似文献