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761.
海洋工程竣工投产后,其造成的海洋环境负面影响往往超过工程施工前开展的海洋环境影响评价中的预测值,开展海洋工程海洋环境影响后评价工作是近几年来国外海洋发达国家海洋工程管理方面应用较为成熟的一种管理手段。温州灵霓北堤工程是我国首个实施海洋环境影响后评价的工程,在其竣工通车2 a后,为了检验灵霓北堤对瓯江口南北两侧海域的实际海洋环境影响以及前期环境评价单位,温州市发改委委托中国海洋大学展开环境影响后评价工作。中国海洋大学根据海域现状和历史调查资料,采用有无对比、前后对比和数学模型预测的方法,针对工程前期评价单位的预测与结论,评价了灵霓北堤两侧海域海洋环境质量现状,并对前期环评结论的合理性和正确性开展了分析。后评价结果表明,前期评价单位的预测结果基本都已得到体现,但其部分预测值较保守,例如部分区域的冲淤量和灵霓北堤对两侧生物的影响等。  相似文献   
762.
Rice-wheat cropping systems of the Indo-Gangetic plains (IGP) occupying 12 million ha of productive land are important for the food security of South Asia. There are, however, concerns that yield and factor productivity trends in these systems are declining/stagnating in recent years. Decrease in soil organic carbon is often suggested as a reason for such trends. A field experiment was conducted to study the soil organic carbon (SOC) and soil microbial biomass carbon (MBC) dynamics in the rice-wheat systems. Use of organic amendments and puddling of soil before rice transplanting increased SOC and MBC contents. Microbial biomass carbon showed a seasonal pattern. It was low initially, reached its peak during the flowering stages in both rice and wheat and declined thereafter. Microbial biomass carbon was linearly related to SOC in both rice and wheat indicating that SOC could be used as a proxy for MBC.  相似文献   
763.
为了研究不同的施肥方式对土壤全氮变化及氮储量的影响,1981年在湖北省农业科学院南湖试验站设置了施用有机肥与化肥的长期定位田间试验,2006年水稻收获后田间取样分析每个处理不同土层的全氮含量与氮储量。研究结果表明:与对照相比,单施化肥与单施有机肥0~20cm土层土壤的容重下降,化肥添加有机肥比相应的单施化肥的容重要低一些。除了对照之外,其它处理都是0~20cm土层土壤全氮含量高于其它土层,氮肥配施有机肥处理0~20cm土层土壤全氮含量最高。除了氮磷钾肥配施过量有机肥处理外,化肥配施有机肥处理土壤的全氮含量都高于单施化肥或单施有机肥处理,20~40cm土层土壤全氮含量具有相似的规律。在0~20cm土层,与对照相比,单施氮肥及氮磷肥不能增加土壤全氮储量,但是化肥配施有机肥能够增加土壤全氮的储量。单施氮磷钾肥及单施有机肥也能够增加土壤全氮的储量。在0~20cm土层,氮肥配施有机肥处理的土壤全氮储量最多,达8.82t·hm-2,而氮肥处理的氮储量最低,仅为5.38t·hm-2。在100cm深度,与单施化肥及单施有机肥相比,化肥配施有机肥都增加了土壤全氮的储量。  相似文献   
764.
The New York Bight is perhaps one of the most used and abused coastal areas in the world as a consequence of urbanization and the disposal of the waste of some 20 million people who reside by its shores and surrounding bays and estuaries. A variety of sources, including those associated with sewage wastes, industrial wastes, contaminated dredged material, urban runoff, and atmospheric fallout contaminate these coastal waters. Many of the stresses of excess population and industrialization as measured by pollutant loadings and ecosystem impacts can be crudely quantified in terms of use impairments-use impairments that have measurable social and economic relevance. Five broad categories of impairment attributed to pollution in the Bight that are causing significant losses of ecological, economic, or social values are: beach closures, unsafe seafoods, hazards to commercial and recreational navigation, loss of commercial and recreational fisheries, and declines in birds, mammals and turtles. These impairments are generally caused by floatable wastes, nutrients, toxicants, pathogens and habitat loss. Measures of such impairments are not standard, nor in many cases totally quantifiable. We have examined specific subsets of these impairments in terms of their spatial and temporal changes and as a first approximation determined the economic and social significance of these changes. the cost of these impaired uses of the Bight are measured in terms of billions of dollars annually for New York and New Jersey.  相似文献   
765.
长期施肥对五氯酚在红壤性水稻田中消解的影响研究   总被引:1,自引:0,他引:1  
在种稻和未种稻2种条件下,研究了五氯酚(PCP,初始浓度85 mg/kg)在长期不同施肥处理红壤性水稻田中的消解特征.长期不同施肥方式为:不施肥(CK)、施无机肥尿素(N)、施有机肥(OM)和无机有机肥配施(N+OM).结果表明,到收割水稻时,在未种稻情况下,CK、N、OM和N+OM处理表层土壤中可提取PCP残留分别为28.3、 34.2、 19.3、 18.7 mg/kg,在亚表层土壤中可提取PCP残留分别为6.3、 9.1、 5.1和4.1 mg/kg;在种稻情况下,表层土壤中可提取PCP残留分别为19.4、 30.9、 16.7和8.7 mg/kg,在亚表层土壤中可提取PCP残留分别为3.7、 6.1、 2.6和2.8 mg/kg.长期单施有机肥或无机有机肥配施显著加速表层土壤中PCP的消解,减缓表层土壤中PCP向下迁移;长期施尿素抑制表层土壤中PCP的消解,加速表层土壤中PCP向下迁移.与未种稻相比,种稻对表层土壤中PCP的消解呈现不同程度的促进作用,除N处理外,在其它3种长期施肥处理(CK、OM、N+OM)中均达到显著的水平.同时,种稻显著减少表层土壤中PCP向下迁移.无论种稻与否,PCP在稻田系统中均能发生还原脱氯降解生成2,3,4,5-四氯酚 (2,3,4,5-TeCP)和3, 4, 5-三氯酚(3,4,5-TCP);在未种稻情况下, 2,3,4,5-TeCP是PCP脱氯降解的主要产物,而在种植水稻的情况下, 3,4 5-TCP是PCP脱氯降解的主要产物.  相似文献   
766.
侯马市酸雨长期变化趋势分析   总被引:6,自引:2,他引:4  
根据1992年至2008年的酸雨观测记录,对侯马市的酸雨变化特征及其长期趋势进行了统计分析.结果表明,17年间,除个别年份外,侯马地区的降水pH值长期低于5.6,2006年以来甚至低于4.5,多年平均pH值为4.88,是我国长江以北地区酸雨污染最严重的地区.降水pH值的平均月际变化幅度为0.8pH单位,呈不规则起伏变化.在降水集中的7、8、9月间,酸沉降量约占全年的60%.作为出现在我国北方的区域性酸雨地区,侯马地区降水酸度2002年前后呈现不同的变化趋势,2002年前,降水pH值平均年变率约为0.10a-1,酸雨污染呈现减弱趋势,而之后的pH值平均年变率约为-0.28a-1,呈现酸雨污染快速加重的变化趋势.该地区降水量的变化不仅对单次降水的酸性有较明显的影响,而且对降水酸度的季节变化和年际变化也有明显影响,显示当地的大气颗粒物具有显著的碱性中和能力.2007年对降水离子成分的加强观测分析结果显示,SO42-、NO3-、Ca2+、NH4+是降水中最主要的离子;[1/2]SO42-与NO3-的比值约为6.9,说明当地的酸雨为较明显的硫酸型污染;降水中NH4+含量较高,大约与[1/2]Ca2+的离子含量相当;主成分因子分析显示,[1/2]SO42-、NO3-、[1/2]Ca2+、NH4+4种离子含量的变化存在显著相关,当地的焦煤、煤化工等高污染排放可能是其重要的共同来源.  相似文献   
767.
Informal (visitor-created) trails represent a threat to the natural resources of protected natural areas around the globe. These trails can remove vegetation, displace wildlife, alter hydrology, alter habitat, spread invasive species, and fragment landscapes. This study examines informal and formal trails within Great Falls Park, VA, a sub-unit of the George Washington Memorial Parkway, managed by the U.S. National Park Service. This study sought to answer three specific questions: 1) Are the physical characteristics and topographic alignments of informal trails significantly different from formal trails, 2) Can landscape fragmentation metrics be used to summarize the relative impacts of formal and informal trail networks on a protected natural area? and 3) What can we learn from examining the spatial distribution of the informal trails within protected natural areas?  相似文献   
768.
The invasion spread of the emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is characterized by the formation of satellite populations that expand and coalesce with the continuously invading population front. As of January 2010, satellite infestations have been detected in 13 states and two Canadian provinces. Understanding how newly established satellite populations may affect economic costs can help program managers to justify and design prevention and control strategies. We estimate the economic costs caused by EAB for the 10-yr period from 2010 to 2020 for scenarios of fewer EAB satellite populations than those found from 2005 to 2010 and slower expansion of satellite populations found in 2009. We measure the projected discounted cost of treatment, removal, and replacement of ash trees (Fraxinus spp.) growing in managed landscapes in U.S. communities. Estimated costs for the base scenario with the full complement of satellites in 2005-2010 and no program to mitigate spread is $12.5 billion. Fewer EAB satellites from 2005 to 2010 delay economic costs of $1.0 to 7.4 billion. Slower expansion of 2009 satellite populations delays economic costs of $0.1 to 0.7 billion. Satellite populations that are both distant from the core EAB infestation and close to large urban areas caused more economic costs in our simulations than did other satellites. Our estimates of delayed economic costs suggest that spending on activities that prevent establishment of new satellite EAB populations or slow expansion of existing populations can be cost-effective and that continued research on the cost and effectiveness of prevention and control activities is warranted.  相似文献   
769.
It is commonly recognized that there are constraints to successful regional-scale assessment and monitoring of cumulative impacts because of challenges in the selection of coherent and measurable indicators of the effects. It has also been sensibly declared that the connections between components in a region are as important as the state of the elements themselves. These have previously been termed “linked” cumulative impacts/effects. These connections can be difficult to discern because of a complicated set of interactions and unexpected linkages. In this paper we diagnose that a significant cause of these constraints is the selection of indicators without due regard for their inter-relationships in the formulation of the indicator set. The paper examines whether the common “forms of capital”, i.e., natural (renewable and non-renewable), manufactured, social, human and financial capitals, framework is a potential organizing structure. We examine a large region in western NSW Australia where the predominant production systems are mining and grazing for production of wool, beef and lamb. Production in both is driven by consumption of a non-renewable resource, i.e., ore for mining and topsoil for grazing, the latter on the basis that loss rate estimates far exceed soil formation rates. We propose that the challenge of identifying connections of components within and between capital stores can be approached by explicitly separating stores of capital and the flows of capital between stores and between elements within stores, so-called capital fluxes. We attempt to acquire data from public sources for both capital stores and fluxes. The question of whether these data are a sufficient base for regional assessment, with particular reference to connections, is discussed. The well-described challenge of a comparative common currency for stores and fluxes is also discussed. We conclude that the data acquisition is relatively successful for stores and fluxes. A number of linked impacts are identified and discussed. The potential use of money as the common currency for stores and fluxes of capital is considered. The basic proposition is that replacement or preservation costs be used for this. We conclude that the study is sufficiently positive to consider further research in fully-coupled models of capital stores and fluxes.  相似文献   
770.
我国海水利用现状及其对环境的影响   总被引:5,自引:1,他引:4  
海水利用为解决全球水资源短缺提供了重要途径.本文综述了世界范围内海水利用方面的进展情况,评述了大生活用水和工业冷却水等海水直接利用及海水淡化过程对海洋环境的影响,特别是高温冷却海水和海水淡化浓盐水的排放以及化学物质的加入对海水水质、海洋生物的影响,并提出了预防和减轻这些影响的措施和方法.  相似文献   
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