排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
2.
Bioremediation, is an effective and environment-friendly method of cleaning up crude oil pollution after an oil spill. However, the in situ bioremediation of crude oil is usually inhibited by deficiency of inorganic nutrients. To understand the effects of nutrient addition on the bioremediation of crude oil and the succession of bacterial communities during process of bioremediation, microcosms containing oilcontaminated sediments were constructed and biodegradation of crude oil was assessed based on the depletion of different ingredients. We used two culture-independent methods, denaturing gradient gel electrophoresis and a 16 S rRNA gene based clone library, to analyze the succession of bacterial communities. The results suggested n-alkanes were degraded after 30 days and that nutrient amendments significantly improved the efficiency of their biodegradation. Moreover, oil contamination and nutrient amendments could dramatically change bacterial community structures. Lower diversity was detected after being contaminated with oil. For instance, bacterial clones affiliated with the phylum Armatimonadetes, Firmicutes, Gemmatimonadetes, and Planctomycetes and the class Deltaproteobacteria and Epsilonproteobacteria could not be identified after 30 days of incubation with crude oil. However, "professional hydrocarbonocastic bacteria" became abundant in samples treated with oil during the bioremediation period, while these clones were almost completely absent from the control plots. Interestingly, bioinformatics analysis showed that even when dramatic differences in oil biodegradation efficiency were observed, bacterial communities in the plots with nutrient amendments were not significantly different from those in plots treated with oil alone. These findings indicated that nutrient amendments could stimulate the process of biodegradation but had less impact on bacterial communities. Overall, nutrient amendments might be able to stimulate the growth of n-alkane degrading bacteria. 相似文献
3.
4.
5.
本文利用神经网络模型、多元线性回归模型和马尔科夫模型分别建立了统计预报模型,对热带印度洋海表温度异常(SSTA)和印度洋偶极子(IOD)指数进行了63 a的长时间回报实验,并详细比较了线性和非线性统计预报模型的差异。结果表明:统计模型对IOD指数的预报技巧和现有动力模式预报技巧相差不大,对偶极子指数(DMI)有效预报时效为3个月,东极子指数(EIO)为5~6个月,西极子指数(WIO)达到8~9个月。IOD事件强烈的季节锁相特性使得对秋季的DMI指数可以提前4个月做出有效预报。加入同期的ENSO指数来预报IOD指数,能有效地提高IOD预报技巧,特别是对IOD峰值的预报。复杂的神经网络模型和简单的多元线性回归模型在对SSTA和IOD指数的预报具有同等的效果。 相似文献
6.
7.
南祁连成矿带北缘东段区域地球化学扫面及异常查证均有较好的Au、As、Sb、Hg组合异常显示,但该区金矿找矿工作多年来一直未能取得突破性进展。通过对该区成矿地质环境、地球化学异常和已有成矿事实等因素分析,认为该区金矿成矿地质环境有利,具有进一步扩大资源量的潜力和前景,建议对该区进一步开展以寻找Au(Sb)矿为目的普查找矿工作。同时,应对该区带具有相似金矿成矿环境的刚察大寺、拉仁哇耳玛-拉仁修玛等地区的金矿找矿工作引起重视。 相似文献
8.
9.
10.
在金塘水道西口门2006年冬季和2007年夏季大、小潮期间应用美国RDI公司生产的300 kHz声学多普勒流速剖面仪(ADCP)进行25 h的走航式断面观测,同步采集水样过滤获得悬沙浓度.实测断面流速、流向表明:落潮时流向为东南向,涨潮时分两股,靠近北仑为西南向,靠近金塘岛为西北向;夏季大潮最大流速为260 cm/s,大于冬季大潮;观测期间断面悬沙浓度为0.4~1.5 g/L,冬季大于夏季约0.3~0.5 g/L;ADCP后向散射强度冬季大于夏季约5 dB.应用实测CTD数据进行声吸收系数校正,通过计算,断面后向散射强度分布趋势基本不变.后向散射强度与悬沙浓度成正比,与水深成正比,垂向分布与潮时有关,冬季小潮水深增大时,后向散射强度反而减小.回归ADCP后向散射强度与水样悬沙浓度之间半经验半理论统计关系,发现冬季不成线性关系,夏季成线性关系,且相关性较好,相关系数为0.7,说明夏季较高浓度下后向散射强度可以表示悬沙浓度的大小.夏季大、小潮期间高分辨率的悬沙浓度断面数据分析表明,反演后的悬沙浓度值与流速成正比;近岸悬沙浓度大于断面中部;涨急和落急时同一水深高低含沙量值错落分布,涨憩和落憩则分层明显;大潮悬沙浓度大于小潮流约0.05 g/L.断面两端点反演后的悬沙浓度与实测值比较,呈现半日潮含沙量双峰特征,夏季大潮反演后的悬沙浓度与实测值分布一致,实测值大于0.9 g/L时,两者量值相差大,小潮则拟合很好.因此,应用走航式ADCP测量高悬沙浓度是可行的,它可大大提高测量效率,为获取现场悬沙浓度提供了一种新方法. 相似文献