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排序方式: 共有95条查询结果,搜索用时 187 毫秒
71.
泰安基准地震台在“十五”台站改造中,综合信息网络的建设是其重要的组成部分,使台站现代化、信息化、数字化进程上了一个新台阶,对整个台站的环境面貌变化起到了很大作用。本文通过我台综合信息网络建设实例的介绍,为正在进行台站改造的同行们提供借鉴。  相似文献   
72.
The Doñana National Park contains highly complex microbial communities that play critical roles in the bioavailability and biogeochemical cycling of elements. In this study, we analyzed the formation of Fe-rich films on the surface of shallow waters at Doñana National Park as a model for future applications in bioremediation. Phytoplankton composition and abundance, physicochemical measurements, culture enrichments, and molecular detection of microorganisms were determined during this study. Natural samples were incubated in the laboratory and enrichments producing similar phenomena were obtained. Bacteria belonging to the genera Enterobacter were the major participants in surface Fe-film formation in laboratory enrichments. Film formation was dependent on wind exposure and only those sites protected from the direct influence of wind developed these films. A higher concentration of euglenophytes was found in the proximity of film-covered waters. Available iron (Fe2+) and total Fe concentrations were high (18.8 and 46.6 mg/L, respectively) underneath the surface film, and higher than in film-free waters and pore-sediment water. The concentration of phosphate and its availability were higher in the iron-rich film sediment, as 61% of total P was bound to iron oxy-hydroxides. Our results provide evidence of the link between P and Fe biogeochemical cycling in aquatic systems on sandy soils at the Doñana National Park. In addition, they provide significant insights into the bioavailability of these elements with potential interest in the role of microorganisms for metal sequestration in natural environments and utilization in bioremediation processes.  相似文献   
73.
The relationship between individual performance and nonrandom use of habitat is fundamental to ecology; however, empirical tests of this relationship remain limited, especially for higher orders of selection like that of the home range. We quantified the association between lifetime reproductive success (LRS) and variables describing lifetime home ranges during the period of maternal care (spring to autumn) for 77 female roe deer (Capreolus capreolus) at Trois-Fontaines, Champagne-Ardenne, France (1976-2000). We maintained population growth rate (adjusted to account for removals of non-focal animals) near rmax, which enabled us to define the fitness-habitat relationship in the absence of density effects. Using a negative binomial model, we showed that a roe deer's incorporation into its home range of habitat components important to food, cover, and edge (meadows, thickets, and increased density of road allowances) was significantly related to LRS. Further, LRS decreased with increasing age of naturally reclaimed meadows at the time of a deer's birth, which may have reflected a cohort effect related to, but not entirely explained by, a decline in quality of meadows through time. Predictive capacity of the selected model, estimated as the median correlation (rs) between predicted and observed LRS among deer of cross-validation samples, was 0.55. The strength of this relationship suggests that processes like selection of the site of a home range during dispersal may play a more important role in determining fitness of individuals than previously thought. Individual fitness of highly sedentary income breeders with high reproductive output such as roe deer should be more dependent on home range quality during the period of maternal care compared to capital breeders with low reproductive output. Identification of the most important habitat attributes to survival and reproduction at low density (low levels of intraspecific competition) may prove useful for defining habitat value ("intrinsic habitat value").  相似文献   
74.
川西高山森林生态系统林下生物量及其随林窗的变化特征   总被引:1,自引:0,他引:1  
作为森林生态系统的重要组成部分,林下植被及其残体的分布受到林冠层的影响,但迄今有关林窗对林下植被和残体生物量的影响尚无研究报道.于2013 年8 月2 日至20 日,以海拔3 600 m 的川西岷江冷杉原始林林下植被为研究对象,根据区域内的坡向和林分组成等因素设置3 个100 m×100 m 的典型样地,调查其生物量及其随林窗的变化特征.在每个样地内选择3 个大林窗,在林窗、林缘和林下分别设置3 个20 m×20 m 的样方,调查粗木质残体长度或高度、大小头直径、枯立木记录胸径、腐烂等级等;在林窗、林缘和林下分别设置3 个5 m×5 m 的样方,采用“收获法”收集样方内直径在2.5-10 cm之间的细木质残体和灌木生物量;在林窗、林缘和林下分别设置3 个1 m×1 m 的样方来调查凋落物储量和草本生物量;在1m×1 m 的样方内随机选择1 个20 cm×20 cm 的小样方来调查地被植物生物量.结果表明,(1)川西高山森林生态系统总生物量为72.75 t·hm^-2,其中林下生物量为67.92 t·hm^-2,占生态系统生物量的95.17%.活体植被以灌木为主,其生物量为9.81t·hm^-2;残体部分以粗木质残体为主,其储量为53.00 t·hm^-2;(2)林窗对灌木、草本、地被植物的影响各不相同,且不同物种的灌木生物量表现出不同的分布规律;草本生物量表现出明显的“边缘效应”,在林缘显著高于林下;林窗和林缘的地被植物生物量相对较低;(3)粗木质残体储量从林下到林窗呈现减小的趋势,但总体储量仍然较大,林窗和林缘的细木质残体储量高于林下.这些结果为认识高山森林生态系统林下生物量及其格局,以及林窗在森林生态系统的重要作用提供了基础理论依据.  相似文献   
75.
王冰  郭书海  李凤梅  王卅  吴波 《环境科学学报》2018,38(10):4133-4141
我国开采原油的稠油比重大、胶质含量高、环境风险突出,亟需解决石油污染土壤中胶质组分的解毒问题.由于胶质结构复杂、难以降解,所以对胶质结构变化的研究较少,其降解率也并不足以说明胶质污染土壤的修复效果,因此本文着重分析了修复过程中胶质结构与毒性的变化,为污染土壤修复体系提供重要指标.本文从辽河油田原油中提取胶质配制污染土,并加入构建的混合菌群.设计微生物修复(Bio)、电动-微生物修复(EK+Bio1)、电动-微生物补充营养修复(EK+Bio2)及间断电动-微生物修复(EK+Bio3)共4种处理.结果表明,胶质平均降解率EK+Bio2EK+Bio3EK+Bio1Bio,降解率最高为9.67%,为Bio处理的3.05倍(3.15%).元素分析结果表明,修复前后胶质平均化学式为C_(106)H_(157)N、C_(96)H_(174)N,碳氢比降低,不饱和度降低.光谱分析与~1H-核磁共振结果表明,修复后胶质碳链变短,芳香环、羧基与酚类结构数量减少.根据B-L法计算胶质芳碳率(f_A)由0.28减少到0.11,可推测胶质的结构模型.MicroResp~(TM)与小麦种子发芽实验结果表明,修复后土壤中微生物活性增强,小麦种子发芽率大大提高,说明结构的变化使胶质毒性降低.因此,电动-微生物修复使胶质结构发生变化,并在一定程度上有效削减了胶质毒性,较好的对胶质污染土壤进行了修复.  相似文献   
76.
77.
Estimates of soil erosion using cesium-137 tracer models   总被引:1,自引:0,他引:1  
The soil erosion was studied by 137Cs technique in Yatagan basin in Western Turkey, where there exist intensive agricultural activities. This region is subject to serious soil loss problems and yet there is not any erosion data towards soil management and control guidelines. During the soil survey studies, the soil profiles were examined carefully to select the reference points. The soil samples were collected from the slope facets in three different study areas (Kırtas, Peynirli and Kayısalan Hills). Three different models were applied for erosion rate calculations in undisturbed and cultivated sites. The profile distribution model (PDM) was used for undisturbed soils, while proportional model (PM) and simplified mass balance model (SMBM) were used for cultivated soils. The mean annual erosion rates found using PDM in undisturbed soils were 15 t ha−1 year−1 at the Peynirli Hill and 27 t ha−1 year−1 at the Kırtas Hill. With the PM and SMBM in cultivated soils at Kayışalan, the mean annual erosion rates were obtained to be 65 and 116 t ha−1 year−1, respectively. The results of 137Cs technique were compared with the results of the Universal Soil Loss Equation (USLE).  相似文献   
78.
In the present study the spatial and the vertical distributions of 210Pb were investigated in the soils around a uranifereous coal fired power plant (CPP) in Yatagan Basin, in Western Turkey. The variation of 226Ra activity along the soil profiles was studied to assess the unsupported 210Pb distribution in the same samples. 226Ra was measured by gamma spectroscopy and 210Pb activities were determined from 210Po activities using radiochemical deposition and alpha spectroscopy. The total 210Pb activity concentrations in bulk core samples varied in the range of 38-250 Bq kg(-1) in the study sites and of 22-78 Bq kg(-1) in reference site. In the sectioned cores sampled from the study areas the ranges for activity concentrations of 226Ra, total 210Pb and unsupported 210Pb are 24-77; 39-344 and 4-313 Bq kg(-1), respectively. Corresponding ranges for reference site are 37-39; 39-122 and 1-83 Bq kg(-1).  相似文献   
79.
80.
文章对油田外排废水中的石油类、COD_(Cr)等第二类污染物的排放标准进行分区、分级划定的研究,同时选择对西部干旱区生态环境有重要影响作用的总盐指标排放标准进行分区分级研究,为新疆油田公司实施"分区保护、分级防治、分类管理"提供科学依据。研究成果在石西油田、六九区大沙河排放口等地进行试点应用,为最终实现油田环境保护与经济发展双赢提供有益的借鉴。  相似文献   
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