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61.
In South Africa, rare geological specimens are protected by the National Heritage Resource Act (1999). These portable geoheritage objects are neither defined nor described in this Act making their geoheritage status questionable. Thirteen categories and criteria for establishing a geological specimen's rarity status are discussed and include (1) rarity as defined by abundance per se; (2) rarity of a particular habit (external shape or form) of a mineral; (3) rare pseudomorphs; (4) rarity of a particular variety of a mineral; (5) rarity of a particular colour of a common mineral; (6) rarity defined by size; (7) rarity defined by quality; (8) a common species, but rare for a particular locality; (9) rarity of associations of minerals; (10) rarity determined by source being depleted, exhausted or mined out; (11) rare inclusions in minerals; (12) previously rare, now common specimens and (13) miscellaneous criteria that produce rare specimens. Geological specimens (resources) are complex objects when defining their rarity status and multiple rarity factors can apply to single specimens. A lack of clear criteria for defining rare geological specimens appears to place the National Heritage Resource Act (1999) in direct conflict with the more recent Mineral and Petroleum Resources Development Act (2002) which legitimizes the legal exploitation of any mineral resource.  相似文献   
62.
This paper presents an analysis of the main environmental impact factors (noise, vibration, fumes, dust, vehicle traffic) associated with marble quarrying and processing in the Orosei industrial area and their effects. Solutions are also proposed to prevent, mitigate and, where possible, eliminate the impact on the environment. Using three-dimensional topographic models, the authors simulated quarry and industrial processing development, with projections over the next 10, 30 and 50 years. The aim of these simulations was to establish land management planning guidelines for the optimal and environmentally sustainable development of the Orosei Marble industrial area. Lastly, careful quarry development planning is important both for enhancing LCA and for improving production processes through sustainable technologies that yield green label products meeting environmental performance standards.  相似文献   
63.
细菌信息素研究进展   总被引:6,自引:0,他引:6  
有关细胞信号的研究一直是生物学研究中的热点课题,尤其是动物细胞信号系统的研究已很深入,发现了许多信号分子和信号传导途径.但对微生物而言,长期以来的认识都是微生物,特别是细菌,一般只能被动地感受环境的变化,而没有群体的效应.其中唯一的特例是粘细菌(myxobacteria),在营养缺乏的条件下,通过释放cAmp等信号分子,促使营养细胞聚集,形成子实体和粘孢子[1].直至70年代,Hasting等通过对海洋发光细菌Vibriofischeri和Vibrioharveyi的发光机制的研究,发现发光细菌本身能产生一类小分子物…  相似文献   
64.
太湖叶绿素a浓度分布的时空特征及其影响因素   总被引:8,自引:0,他引:8  
基于2005—2009年20次太湖采样期间的水质监测数据,研究了太湖叶绿素a浓度的主要分布特征,分析了水环境因子对叶绿素a浓度分布的季节性和空间性影响.结果表明,太湖叶绿素a浓度分布的空间差异较大,主要表现为梅梁湾、竺山湾、太湖西部和西南部湖区为叶绿素a浓度距平经验正交分解(EOF)第一模态空间分布的显著正值区,太湖湖心和东南湖区则为负值区;影响叶绿素a浓度的因子有水温、溶解氧、总氮、磷酸根和总磷,但总磷和水温的影响相对更为显著,而各季节叶绿素a浓度的影响因子则略有差异;影响藻类生长的因子存在较大的空间分布差异,但总磷、水温和溶解氧是其主要限制性因子,氮类营养盐的影响则处于次要地位.  相似文献   
65.
西藏高原草原化小嵩草草甸生长季土壤微生物呼吸测定   总被引:9,自引:2,他引:9  
以西藏当雄县草原化小嵩草草甸生态系统为研究为对象,利用Li6400-09对生长季土壤微生物异养呼吸进行了测定。土壤异养呼吸R(h)动态与土壤温度T()变化趋势一致,尤其与5cm地温相关性最强,说明5cm地温是土壤微生物异养呼吸的主要限制因子。在生长季中土壤异养呼吸与5cm土壤温度呈现不同的函数关系:在降水比较集中的雨季(6~8月),函数关系是Rh=0.106exp0.133T;在降水相对较少的旱季(5月,9~10月),函数关系是Rh=0.18exp0.0833T。在生长季中,雨季土壤日异养呼吸量为2.4g CO2.m-2,雨季异养呼吸总量为219.6g CO2.m-2,Q 10为3.8;旱季日异养呼吸量为1.8g CO2.m-2,呼吸总量为160.2gCO 2.m-2,Q 10值为2.3。结果表明,土壤异养呼吸在降水集中的雨季对土壤温度反应更敏感,在生长季不同时期由于降水格局的影响,土壤水分对土壤微生物异养呼吸对温度的响应有调节作用。2004年生长季(5~10月)土壤异养呼吸总量达379.8gCO2.m-2。  相似文献   
66.
2株苯胺降解的分离鉴定及其降解特性研究   总被引:8,自引:0,他引:8  
任随周  郭俊  曾国驱  岑英华  孙国萍 《环境科学》2006,27(12):2525-2430
从处理印染废水的活性污泥中分离得到2株苯胺降解菌,从菌落、细胞形态、生理生化及16S rRNA基因扩增测序等方面对2株菌进行了鉴定,并比较分析2株菌在好氧与缺氧条件下的苯胺降解、偶氮染料脱色及苯胺脱氨氧化酶基因tdnQ和黄素还原酶基因(fre)的携带情况.结果表明,2株菌属于Pseudomonas属和Shewanella属,分别命名为Pseudomonas sp.AN30和Shewanella sp.DN425.AN30菌株在振荡好氧条件下72h内对250mg/L苯胺的降解率为96.1%,DN425菌株的降解率为13.8%;在静置缺氧条件下AN30菌株的苯胺降解率为39.6%,DN425菌株的降解率仅为8.6%.DN425菌株在静置缺氧条件下4h内可将初始浓度为50 mg/L的偶氮染料酸性大红彻底脱色,而AN30菌株对酸性大红不具有脱色能力.以总DNA为模板,分别用tdnQ基因和fre基因特异性引物进行扩增,2株菌均能扩增出大小分别为380bp和630bp左右的目标条带,显示2菌株均携带有苯胺脱氨氧化酶基因和黄素还原酶基因.  相似文献   
67.
华西雨屏区不同密度巨桉人工林土壤呼吸特征   总被引:9,自引:0,他引:9  
从2008-03至2009-02,采用闭合动态法(LI-6400-09)对华西雨屏区不同密度中龄巨桉人工林土壤呼吸进行了研究。结果表明:①该林分土壤呼吸具有明显的季节动态,各密度林分土壤呼吸速率最高值均出现在7月份,最低出现在1月,且密度为883株·hm-2(1.5 m×8 m)的巨桉林土壤呼吸速率最大,2 222株·hm-2(1.5 m×3 m)的最小;②2008年4、7、10月土壤呼吸速率24 h平均值均表现为883株·hm-2> 1 333株·hm-2> 2 222株·hm-2,且7月>4月>10月;③土壤微生物生物量碳氮、土壤有机质含量和10 cm根系生物量都表现出相同的趋势,即林分密度越小,土壤微生物生物量碳氮越高,草本植物越多,根系生物量越大,有机质含量越多;④温度是巨桉林土壤呼吸变异的主导因子,土壤呼吸速率与土壤温度和湿度的双因素模型优于单因素模型,两者共同解释了土壤呼吸速率月动态的78.3%~91.5%;⑤各密度林分土壤呼吸Q10值随巨桉林分密度增大而降低,大小顺序为3.65(883株·hm-2)>2.60(1 333株·hm-2)>2.55(2 222株·hm-2)。  相似文献   
68.
We formally study the determinants, magnitude and distribution of efficiency gains generated in multilateral linkages between permit markets. We provide two novel decomposition results for these gains, characterize individual preferences over linking groups and show that our results are largely unaltered with strategic domestic emissions cap selection or when banking and borrowing are allowed. Using the Paris Agreement pledges and power sector emissions data of five countries which all use or considered using both emissions trading and linking, we quantify the efficiency gains. We find that the computed gains can be sizable and are split roughly equally between effort and risk sharing.  相似文献   
69.
钾素Q/I特性是表征土壤钾素状况的一个重要指标,它能同时度量土壤钾素的强度和容量.本文研究了广东不同质地水稻土Q/I特性与大田钾肥施用技术的关系.结果表明:(1)不同质地土壤的Q/1曲线差异明显,砂土类曲线较平缓.粘土类曲线较陡。(2)PBCk与土壤粘粒含量呈极显著正相关(r=0.653).(3)-△K0与作物相对百分产量呈极显著正相关(r=0.873),可作为预测当季作物需钾量的参数.(4)AR_e ̄k与土壤粘粒含量呈显著负相关(r=-0.520),AR_e ̄k的大小可作为钾肥合理分配的依据.  相似文献   
70.
An experimental study on the formation and transport of ozone in ambient air was performed in Tenerife (Canary Islands) in order to investigate the processes affecting ozone levels and air quality. The special features of Tenerife (prevalence of the trade wind pattern (NE), orography and the specific location of the local ozone sources) permit to quantify the role of the ‘long-range transport from northern latitudes' versus the ‘formation and transport of ozone downwind of the main urban areas' of Tenerife. Levels of O3, NO2 and OX were monitored in different types of environments to achieve this purpose. The results showed that: (1) upwind of the urban areas ozone is mainly transported from the ocean by trade winds, (2) local ozone titration (by NO) and ozone replenishment from the ocean are the main causes of ozone variations in urban and suburban areas, and (3) photochemical ozone production occurs downwind of the urban areas. Photochemical production causes daylight O3 and OX levels downwind of urban areas to be frequently (60% and 35% days/year, respectively) higher than upwind of the urban sites (O3 and OX excess frequently in the range 5–20 ppbv). Due to the above processes, different daily ozone cycles occur in short distances (<30 km), with maximum O3 levels during daylight or night depending on the site. Ozone phytotoxicity was assessed by calculating the AOT40 index upwind and downwind of the main urban areas. The critical value for the 5-day-AOT40 index was simultaneously exceeded at the two sites (few times/year) during long-range transport events. During the additional exceedances of the critical value downwind of the urban area, relatively high 5-day-AOT40 values were recorded upwind of the urban site. Thus, long-range transport from northern latitudes may produce relatively high 5-days-AOT40 levels in the oceanic boundary layer. These results are important for the protection of the large number of endemic plants in the Canaries. The conceptual model discussed in this study may be qualitatively applied to other islands which possess features similar to those of Tenerife.  相似文献   
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