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61.
耕层以下包气带中氮素蓄积的原位修复治理   总被引:2,自引:0,他引:2  
耕层以下包气带土层中的氮素蓄积再释放是引起地下水污染的主要原因之一。将已优化制备的生物脱氮菌剂与白糖碳源共同施用,并于常规的田间施肥后在一定灌水量下以一定时段(3个月左右)观测,进行了现场原位修复治理试验研究。结果显示,实施该方法可有效去除耕层以下2.0m以浅主要发生氮蓄积的土壤层段中的高含量氮素,为防范地下水污染,消除潜在隐患,提供了科学依据。  相似文献   
62.
基于主成分分析法,利用SPSS19.0软件对福建省的资源环境承载力进行了研究分析。结果表明:从总体上看,沿海地区资源环境承载力综合得分大于内陆地区,但沿海地区内部差异较大,其中,厦漳泉地区以及福州地区资源环境承载力明显高于其它地区。为了促进经济社会的可持续发展,必须充分合理地利用资源环境。  相似文献   
63.
水生植物控制湖泊底泥营养盐释放的效果与机理   总被引:50,自引:5,他引:50  
通过人工模拟的方法,进行了用狐尾藻、凤眼莲2种水生植物来控制湖泊底泥营养盐释放的研究。结果表明,水生植物能有效抑制底泥中TN、TP、硝态氮和氨态氮的释放;沉水植物狐尾藻比漂浮植物凤眼莲的效果好。底泥采取物理处理(塑料包被)后在短期内(15—20d)能暂时控制底泥中营养盐的释放,但不能保持长久,并在随后表现出一定的“补偿效应”。物理措施如底泥包被不是控制底泥营养盐释放的有效方法和根本途径,水生植物修复才能有效抑制底泥中营养盐的释放,今后将成为控制底泥中营养盐释放的发展方向。  相似文献   
64.
多效抗旱驱鼠剂的苗木处理方法与效果   总被引:8,自引:6,他引:8  
研究结果显示,利用多效抗旱驱鼠剂150倍水溶液兑成泥浆,对裸根苗进行蘸根处理,或用多效抗旱驱鼠剂400~800倍水溶液,在容器苗出圃前进行浇灌,可有效地预防甘肃鼢鼠、草兔和牛羊的危害,同时,能显著地提高苗木定植后的抗旱能力.2 a生油松和侧柏定植3 a后,苗木保存率比对照分别提高80.8和73.2,综合预防效果分别为83.7和90.7.苗木保存率及综合预防效果与造林方式、林型和试验地所处的立地有直接的关系,苗木保存率林缘、路旁低于林中,但其综合预防效果差异不明显.施用多效抗旱驱鼠剂的苗木,促长增益指数为0  相似文献   
65.
[Objectives]This study aimed to investigate the effects of ropivacaine-sufentanil epidural analgesia on labor and maternal and neonatal outcomes.[Methods]A tota...  相似文献   
66.
本研究利用筛选出的10对多态性高、条带清晰的SSR引物,以海南岛68份红毛丹种质为材料,进行遗传多样性分析和SSR指纹图谱的构建。结果表明:10对引物在供试材料中共检测出20个等位位点,多态性条带比例为100%,平均多态性信息含量(PIC)为0.393;对68份红毛丹种质做聚类分析,遗传相似系数为0.290~0.664;采用引物?带型组合法构建了68份红毛丹种质的指纹图谱。该结果为今后红毛丹种质鉴定和分子育种提供重要依据。  相似文献   
67.
Marine protected areas (MPAs) are often promoted as tools for biodiversity conservation as well as for fisheries management. Despite increasing evidence of their usefulness, questions remain regarding the optimal design of MPAs, in particular concerning their function as fisheries management tools, for which empirical studies are still lacking. Using 28 data sets from seven MPAs in Southern Europe, we developed a meta‐analytical approach to investigate the effects of protection on adjacent fisheries and asking how these effects are influenced by MPA size and age. Southern European MPAs showed clear effects on the surrounding fisheries, on the ‘catch per unit effort’ (CPUE) of target species, but especially on the CPUE of the marketable catch. These effects depended on the time of protection and on the size of the no‐take area. CPUE of both target species and the marketable catch increased gradually by 2–4% per year over a long time period (at least 30 years). The influence of the size of the no‐take area appeared to be more complex. The catch rates of the entire fishery in and around the MPA were higher when the no‐take areas were smaller. Conversely, catch rates of selected fisheries that were expected to benefit most from protection increased when the no‐take area was larger. Our results emphasize the importance of MPA size on its export functions and suggest that an adequate, often extended, time frame be used for the management and the evaluation of effectiveness of MPAs.  相似文献   
68.
Recent advances in crayfish feeding have enabled the development of size grading studies from the start of first‐feeding. A 180‐day experiment aimed at intensive rearing of Pacifastacus leniusculus was carried out under controlled conditions, evaluating the effects of size grading at two different periods from the onset of exogenous feeding. Stage 2 juveniles were stocked in fibreglass tanks at a density of 100 m2, and fed a dry diet for salmonids combined with restricted amounts of Artemia cysts. Five groups were tested: no grading, grading at 60 days (large and small size) and grading at 100 days (large and small size). After 6 months, no significant differences were found in the survival among groups (mean: 73.06%). The highest final growth (pooled results from upper and lower classes: 17.39 mm carapace length, 1.43 g weight) was achieved by the crayfish sorted at 60 days, showing significant differences from the ungraded group. Smaller crayfish graded at 60 days grew significantly faster than smaller crayfish graded at 100 days. The food conversion ratio was lower in the graded groups (mean: 2.64), showing significant differences from the ungraded group (3.23). This study shows that size grading allows a better performance and an improved feeding efficiency.  相似文献   
69.
70.

Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha?1 of KCl compared with that of 2125 kg ha?1 of phonolite rock powder (equivalent to 170 kg ha?1 of K2O in both treatments); (2) application of 139 kg ha?1 of NaCl compared with that of 183 kg ha?1 of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.

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