济南市近年酸雨特征及其影响因素   总被引：1，自引：0，他引：1  

杨何著 《山东农业大学学报(自然科学版)》2015,(1):23-27

根据2008~2012年济南市酸雨观测资料、探空资料和大气监测资料,分析了济南市酸雨的年、季变化特征,同时研究了酸性降水与气象条件和大气污染物的关系。统计资料证明:近5年济南市的酸雨无论从频率还是从强度上都呈现减弱趋势。降水pH值秋季最低,夏季最高;酸雨频率秋季最高,冬季最低。分析得出,影响济南市酸雨的主要大气污染物是PM10和SO2;在偏东风影响下,酸雨污染严重;酸雨的发生也会受逆温影响,降水前1 d及当天均出现逆温时,酸雨出现频率最高;随着降水量的增加,pH值逐渐降低,中雨时酸雨频率最高;另外,雾和轻雾也容易导致酸雨的发生。  相似文献   

西双版纳热带雨林国家公园野象谷片区规划环境影响评价     

杨韩 《林业调查规划》2011,36(5):90-95,106

以西双版纳热带雨林国家公园野象谷片区(简称"项目区")规划作为规划环境影响评价的基础,规划确定的目标、功能区划、服务设施与基础设施及对野象谷生态环境、大象生存、繁衍生息影响作了分析与评价.指出项目区作为旅游会带来的正、负面影响,从而提出了补充"完善规划"的建议与环境保护预防性对策.  相似文献   

垄沟集雨对紫花苜蓿草地土壤水分、容重和孔隙度的影响   总被引：6，自引：1，他引：5  

寇江涛  师尚礼  王琦  尹国丽 《中国生态农业学报》2011,19(6):1336-1342

在旱作条件下, 将垄沟集雨措施应用于紫花苜蓿种植, 研究沟垄宽比和覆膜方式对2年龄紫花苜蓿草地土壤水分状况、土壤容重及孔隙度的影响。结果表明: 全越冬期, 膜垄和土垄处理0~120 cm土壤水分平均散失量分别低于CK(平作)28.43 mm和13.61 mm。膜垄处理整个集雨期的蓄墒增加率为59.03%~99.27%, 产流效率为53.43%~91.72%; 2009年集雨前期(4月上旬~6月上旬)土垄处理的蓄墒增加率、产流效率分别为1.92%~2.74%和1.71%~2.55%, 2009年集雨中后期(6月中旬~9月下旬)土垄处理的蓄墒增加率、产流效率较集雨前期显著升高, 分别为8.85%~36.77%和8.01%~35.82%; 膜垄和土垄处理的蓄墒增加率、产流效率均随垄面宽度增加而显著增加, 且膜垄的蓄墒增加率、产流效率显著高于土垄处理。垄沟集雨种植能够显著降低0~40 cm土壤层容重, 且0~20 cm土壤层容重降幅表现为膜垄大于土垄。垄沟集雨种植也能够显著增加0~40 cm土壤层孔隙度, 且0~20 cm土壤层孔隙度增幅表现为膜垄大于土垄。  相似文献   

Review and quantitative assessment of ex situ household rainwater harvesting systems in Ethiopia     

Girma Moges  H. Hengsdijk  H.C. Jansen 《Agricultural Water Management》2011,98(8):1215-1227

Ex situ household rainwater harvesting (RWH) systems have been introduced at a large scale in Ethiopia to increase the water availability for smallholders through supplementary irrigation. The first objective of this paper is to review the performance of these systems in Ethiopia based on various assessment studies. The second objective is to provide quantitative biophysical and socio-economic analyses of ex situ household RWH systems contributing to the better understanding of their performance and the identification of options to improve their performance. Uptake of RWH systems by smallholders in Ethiopia is limited and the available information suggests that this is associated among others with poor planning and implementation, poorly functioning input and output markets and the lack of farmers’ skills to use these systems effectively. Our quantitative meta-analyses illustrate that water availability of three studied RWH systems is low in relation to crop water needs, particularly for maize. The variation in area that can be irrigated across years exposes users of RWH systems to considerable risks as the availability of irrigation water depends on prevailing rainfall conditions. The area that can be irrigated varies greatly depending on amount and distribution of rainfall, type of RWH system and crop type. The economics of onion (cash crop) are promising only for plastic lined RWH systems, but those for maize are unfavourable independent of the studied RWH systems. Associated labour requirements especially for water lifting and application are high and possibly constraining the sustainable use of RWH systems. The potential of ex situ household RWH systems to increase agricultural production and income is site-specific depending on biophysical, institutional and socio-economic conditions, and depends on household-specific conditions.  相似文献   

双向步进式全射流喷枪水力性能试验     

李红  王超  杨炎财  陈超 《农业机械学报》2011,42(3):91-95,149

对核心部件射流元件依靠水流的科恩达效应驱动并控制喷头步进转动的PXSB型双向步进式全射流喷枪的水力性能进行了研究。分析了影响喷枪射程、射高、水量分布的主要因素,试验分析了工作压力及射流元件结构参数对喷枪主要水力性能的影响规律,获得双向步进全射流喷枪最佳工作结构尺寸,为建立双向步进式全射流喷枪设计方法提供了依据。通过国内外大中型旋转式喷枪的水力性能对比,表明双向步进式全射流喷枪结构简单、喷洒性能优良。  相似文献   

酸雨及大气污染对马尾松木材材性影响的研究──Ⅰ．木材化学性质与基本密度     

泰特夫 《林业科学》1995,(6)

对生长在酸雨及大气污染严重危害地区、轻度危害地区和未受危害地区三种条件下马尾松的木材化学性质和基本密度的对照研究表明，生长在受危害地区试材的心、边材生材含水率比在未受危害条件下生长的树木分别低３０％和２２％左右；基本密度与未受危害的树木无明显的差异。酸雨及大气污染危害对木材的化学性质有较为明显的影响，主要表现在：生长在受危害地区试木中的抽提物和木素含量高；而α－纤维素含量则比生长在未受危害地区的试材约低１％至３％；在严重危害条件下生长的试材中组成纤维素的葡萄糖比在受轻度危害和未受危害条件下生长的试材约低２％；在受酸雨和大气污染条件下生长的树木中的纤维素相对结晶度比在来受危害条件下生长的树木含量约低８％。在受危害严重地区生长的试材中的钾、钠、钙、镁、铝、铁、钛和锌的含量高于在轻度危害和未受危害地区生长的试材。其中铝和铁的含量比未受害地区的试材高一倍多，锌的含量高近三倍。生长在受酸雨和大气污染严重地区的试材各年轮中的淀粉和游离糖含量均低于生长在未受危害地区的试材。  相似文献   

西吉县聂家河坝窖池田联网补灌模式与集雨节水抗旱途径     

马尚明  缑佐亚  吴璇 《甘肃农业科技》2005,(11):19-22

介绍了宁夏西吉县聂家河流域实施的“坝窖池田”联网补灌模式及其效益。总结提出的农业集雨节水抗旱途径是大力实施淤地坝工程,拦截集蓄降水,济缺水之困,发展种养业;开挖大口井和土圆井,开发浅层地下水;修建薄壁水泥窖,充分利用天然降水资源;大力实施坡改梯工程,使降水就地拦蓄利用;大力实施科技入户工程,在节水上下功夫。  相似文献   

旱地夏闲期利用一年两作种植制度的研究   总被引：1，自引：0，他引：1  

张松令  张建平 《山西农业科学》1997,25(2):22-25

利用裂区设计方法，从生物学产量、小麦耗水规律及水分利用率方面对旱区小麦夏闲期的利用进行了探讨，论证了旱区小麦夏闲期利用的可能性。试验结果表明：小麦夏闲期种植玉米、子粒苋等作物既可于夏用期生产较多的干物质，对全年生物产量也有显著的增益作用。这种模式对于加强旱区小麦生产系统的生物循环，增强该系统在资源、生产及经济方面的可持续性都有重要的现实意义。试验结果还进一步说明这种模式对保证旱区麦农的短期利益，即保证小麦生产的稳定性，也无统计学上的显著影响。  相似文献   

Conserving Africa’s rain forests: problems in protected areas and possible solutions     

Thomas T. Struhsaker  Paul J. Struhsaker 《Biological conservation》2005,123(1):45-54

Problems and correlates of success in the conservation of Africa’s rain forests were evaluated for 16 protected areas in 11 countries, representing approximately half of all protected areas in this biome. Data were obtained from questionnaires, published and unpublished accounts, and direct observations. Despite numerous problems, all protected areas conserved indigenous rain forest biodiversity more effectively than did alternative land uses. More than half the protected areas suffered extensive ecological isolation. Effective management of protected areas was seriously compromised by inadequate funding and government support. Dense human populations, often resulting from immigration, constituted major threats to protected areas. Perceived conservation success was greatest for large protected areas surrounded by similar habitat with strong public support, effective law enforcement, low human population densities, and substantial support from international donors. Contrary to expectations, protected area success was not directly correlated with employment benefits for the neighboring community, conservation education, conservation clubs, or with the presence and extent of integrated conservation and development programs. Studies are needed to better understand what shapes positive pubic attitude towards protected areas because none of the conventional public outreach programs were correlated with public attitude. We also identify apparent deficiencies in foreign assistance to these protected areas. The single most important short-term strategy was considered to be the improvement of law enforcement effectiveness through greater technical and financial support. Nine medium-term strategies are identified, including provision of adequate and secure long-term funding, establishing research and monitoring programs, and developing more appropriate conservation and development programs. Long-term strategies deal with two ultimate causal factors, mainly attitudes and value systems, and stabilizing human populations. Future success of Africa’s protected areas is contingent upon long-term international assistance including contingencies mandating realistic performance standards.  相似文献   

模拟酸雨对南方红豆杉生理特性的影响     

刘建福  杨晨  王明元 《热带作物学报》2012,33(6):1046-1050

研究模拟酸雨对南方红豆杉叶片形态和生理特性的影响.结果表明:酸雨胁迫下南方红豆杉叶尖出现伤害症状,叶片发生脱落,随着酸雨胁迫程度的加剧,叶片损伤程度加重;酸雨胁迫下叶绿素、类胡萝卜素、丙二醛和可溶性糖含量变化不明显;酸雨胁迫下超氧化物歧化酶(SOD)活性变化不明显;中度胁迫(pH4.0)和轻度胁迫(pH5.6)时过氧化氢酶(CAT)活性显著高于对照,而重度胁迫(pH2.5)的CAT活性显著低于对照;轻度胁迫时过氧化物酶(POD)活性显著高于对照,而中度胁迫和重度胁迫的POD活性显著低于对照.这说明南方红豆杉对pH4.0～5.6的酸雨胁迫有一定的适应性和抵抗力.  相似文献