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21.
During late February to mid-March, 1991, when mature N. japonica swarmed in the sea surface off Jimo County, Qingdao, seawater containing numerous early embryos was pumped into a nearby 2.7 ha. muddy-sand shrimp pond, where the embryos continued to develop. 800000 Penaeus chinensis seedlings were introduced into the pond on May 30, 1991. Monthly benthic samplings were carried out to determine the population dynamics and production of N. japonica in this atypical environ -ment.The density of N. japonica varied from 0 to 20400 ind./m2. The predation of P. chinensis was considered to be responsible for the mass mortality of N. japonica in June through July, when the worms were 2.2-3.3cm in length and lived in the top 2-4cm sediment. From August to September of 1991, the hottest period in the site, there was no substantial mortality of N. japonica as reported in earlier literature. This was explained by the deeper burrowing of the' worms that protected them from predation by shrimps.Monthly biomass ranged f 相似文献
22.
A linear regression analysis of 28 selected tide-gauge stations of the Zhujiang Estuary shows that there has been a tendency of local sea level rise at a rate of 2.028 mm per year. The origin of the variation is significantly attributed to the local tectonic movement of discrepant fault-block. Based on this, four types of relative local sea level changes are classified. According to calculation, half of the fertile land, or 800 km2 of the delta plain will have been submerged by sea water by about 2040. This will yield a significant influence on the economic construction and human activities. 相似文献
23.
鞍山市东部陈台沟村附近,有一套以斜长角闪岩类、石英岩类和长英质片麻岩类等组成的变质表壳岩(陈台沟表壳岩),它虽被划归为鞍山群但同该地区公认的鞍山群明显不同。它同白家坟花岗岩(3.8Ga)和陈台沟花岗岩(3.3Ga-3.1Ga)为断层接触。采用Kober提出的单颗粒锆石逐层蒸发-沉积方法,测定了侵入陈台沟表壳岩的两条花岗岩脉(A9212-3,Ch10)中锆石的年龄,A9212-3测定了8粒锆石,年龄为3357±4Ma-3315±4Ma(误差均为2d,Ch10测定了3粒锆石,结果为3337±12Ma,3228±37Ma和1813±7Ma。3357Ma和3337Ma是这两条花岗岩脉侵位时间。1813Ma是后期地质作用的时间。陈台沟表壳岩的年龄大于3.35Ga,建议将陈台沟表壳岩从鞍山群分离出来单独建群。 相似文献
24.
Spatial pattern and regional types of rural settlements in Xuzhou City, Jiangsu Province, China 总被引:3,自引:1,他引:3
This paper principally focuses on the morphological differences,spatial pattern and regional types of rural settlements in Xuzhou City of Jiangsu Province in China.Using satellite images of Xuzhou City taken in 2007 and 2008 and models of exploratory spatial data analysis(ESDA) and spatial metrics,the paper conducts a quantitative analysis of the morphological pattern of rural settlements,and finds significant characteristics.First,rural settlements in Xuzhou City are significantly agglomerated in terms of their spatial distribution;meanwhile,there is significant variation in the geographical density distribution.Second,the scale of rural settlements in Xuzhou City is larger than the average in Jiangsu Province,and the histogram of the scale data is more even and more like a gamma distribution.There are a significant high-value cluster in the scale distribution,and local negative correlation between the scale and density distribution of rural settlements in Xuzhou City.Third,the morphology of rural settlements in Xuzhou City shows relative regularity with good connection and integrity,but the spatial variation of the morphology is anisotropic.Finally,according to the characteristics of density,scale,and form of rural settlements,the rural settlements of Xuzhou City are divided into three types:A high-density and point-scattered type,a low-density and cluster-like type and a mass-like and sparse type.The research findings could be used as the scientific foundation for rural planning and community rebuilding,particularly in less-developed areas. 相似文献
25.
Patinopecten yessoensis is a commercial valuable species. This study deals with the effect of nutrient effects of the broodstock(mainly ovaries) on the larvae. Concentrations of total carbohydrate, total protein and total lipid in the gonads of P. yessoensis from three Hatcheries(Hatchery 1, Hatchery 2, and Hatchery 3) were determined before and after spawning. The relationship between the nutrient concentration in ovaries before spawning(BC) and that of larvae(LC) was assessed as well as the change in nutrient levels in ovaries after spawning(DC). Results indicate that the BC of total carbohydrate(7.66%) and total lipid(14.48%) in ovaries were significantly higher than in testes(5.20%, 5.20% respectively), whereas the BC of total protein in the ovaries was lower(61.76%) than in the testes(81.67%). The different gonadal composition suggests the different nutrient demands between male and female broodstocks in breeding season. P atinopecten yessoensis gonads contained a higher proportion of lipids, in comparison to other bivalves, which might be a response to the low ambient water temperatures. Further analysis of fatty acids showed that the concentrations of n-3PUFA, EPA and DHA in larvae(LC) were positively correlated with BC and DC, indicating the significant nutrient influence of broodstocks on the larvae. As these fatty acids are important in metabolism, and have been demonstrated to be influential to the viability of the larvae, larval growth and the settlement, spat growth, and juvenile survival in many bivalves, they could possibly be used as indexes to evaluate, and predict condition of broodstocks and larvae. 相似文献
26.
Bingwen Qiu Canying Zeng Chongcheng Cheng Zhenghong Tang Jianyang Gao Yinpo Sui 《中国地理科学(英文版)》2014,24(3):317-327
Most evaluation of the consistency of multisensor images have focused on Normalized Difference Vegetation Index (NDVI) products for natural landscapes, often neglecting less vegetated urban landscapes. This gap has been filled through quantifying and evaluating spatial heterogeneity of urban and natural landscapes from QuickBird, Satellite pour l'observation de la Terre (SPOT), Ad- vanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) and Landsat Thematic Mapper (TM) images with variogram analysis. Instead of a logarithmic relationship with pixel size observed in the corresponding aggregated images, the spatial variability decayed and the spatial structures decomposed more slowly and complexly with spatial resolution for real multisensor im- ages. As the spatial resolution increased, the proportion of spatial variability of the smaller spatial structure decreased quickly and only a larger spatial structure was observed at very coarse scales. Compared with visible band, greater spatial variability was observed in near infrared band for both densely and less densely vegetated landscapes. The influence of image size on spatial heterogeneity was highly dependent on whether the empirical sernivariogram reached its sill within the original image size. When the empirical semivariogram did not reach its sill at the original observation scale, spatial variability and mean characteristic length scale would increase with image size; otherwise they might decrease. This study could provide new insights into the knowledge of spatial heterogeneity in real multisen- sor images with consideration of their nominal spatial resolution, image size and spectral bands. 相似文献
27.
Changes in sea surface temperature(SST), seawater oxygen isotope(δ 18 O sw), and local salinity proxy(δ 18 O sw-ss) in the past 155 ka were studied using a sediment core(MD06-3052) from the northern edge of the western Pacifi c Warm Pool(WPWP), within the fl ow path of the bifurcation of the North Equatorial Current. Our records reveal a lead-lag relationship between paired Mg/Ca-SST and δ 18 O during Termination II and the last interglacial period. Similarity in SST between our site and the Antarctic temperature proxy and in CO 2 profi le showed a close connection between the WPWP and the Antarctic. Values of δ 18 O sw exhibited very similar variations to those of mean ocean δ 18 O sw, owing to the past sea-level changes on glacial-interglacial timescale. Calculated values of δ 18 O sw-ss refl ect a more saline condition during high local summer insolation(SI) periods. Such correspondence between δ 18 O sw-ss and local SI in the WPWP may refl ect complex interaction between ENSO and monsoon, which was stimulated by changes in solar irradiance and their infl uence on the local hydrologic cycle. This then caused a striking reorganization of atmospheric circulation over the WPWP. 相似文献
28.
Acute toxicities of potassium permanganate, formalin, and Lugol’s iodine solution to a commonly occurred marine ciliate Pleuronema coronatum (Ciliophora, Scuticociliatida) were measured. Linear regression analysis of the results highlighted the close relationships
between doses of the medicines and mortalities of the organisms, thus providing a capability to predict toxicity effects from
the dose. Toxic effects of the medicines on the ciliates were described in the present paper, and the median lethal concentrations
(LC50 values) were given. Results of measurements indicated that 2 h-LC50 and 12 h-LC50 values of formalin on P. coronatum were 59.00×10−6 and 43.57×10−6, while those of Lugol’s solutions were 90.13 and 67.84×10−6 respectively. The tolerance of P. coronatum to formalin is apparently lower than that to Lugol’s iodine solution and potassium permanganate is a suitable medicine to
kill ciliates in short time. 相似文献
29.
Issues on China Regional Metallogeny 总被引:2,自引:0,他引:2
Zhai Yusheng Deng Jun Peng Runmin Faculty of Earth Sciences Mineral Resources China University of Geosciencs Beijing China 《中国地质大学学报(英文版)》2000,11(3)
In recent years,the study of regional metallogeny,anim portant field in the study of ore deposit geology,has at-tracted much attention from worldwide geologists.Its purposeis to illustrate regularities of m ineralization and distribution ofore deposits and provide a scientific basis for regional explo-ration and appraisementof potential minerals.This paper pro-poses several tentative opinions pertaining to regional metal-logeny of China.The discussion in this paper may improve ourunderstanding… 相似文献
30.
中巴经济走廊是"一带一路"建设的旗舰项目,对中巴经济走廊地质灾害进行敏感性分析与区划,可为中巴经济走廊地质灾害的防治提供参考。基于此,文章选取高程、坡度、地形起伏度、地震密度、多年平均降雨量、距断裂带的距离、地层岩性、距河流的距离和距公路的距离等9个指标,采用加权信息量模型和证据权法,综合分析中巴经济走廊地质灾害敏感性。并运用ROC曲线验证对比两种模型分析的敏感性结果,选取精度较高的模型分析的地质灾害敏感性进行研究区区划,最后对区划结果进行相关验证。研究结果表明:1)中巴经济走廊容易诱发地质灾害的条件为:高程在2660~3470 m之间,坡度为29°~35°,地形起伏度在45~70 m之间,地震密度在2~4个/102 km2之间,多年平均降雨量在430~530 mm之间,距断裂带距离小于5 km,地层岩性为软岩和极软岩,距河流距离小于2 km,距公路距离小于2 km。2)基于加权信息量模型和证据权法分析的中巴经济走廊地质灾害敏感性精度分别为0.821和0.795,表明本研究选取的地质灾害敏感性分析模型具有较高的准确性,但是运用加权信息量模型分析的敏感性更符合实际情况。因此,运用加权信息量模型分析的结果进行研究区地质灾害敏感性区划。3)研究区地质灾害不敏感区、低敏感区、中等敏感区、高度敏感区和极高敏感区所占面积比分别为26.3%、23.1%、21.6%、18.8%和10.2%,以中、低敏感性为主;且敏感性呈现出南低北高的空间分布特征。4)运用实地调研的地质灾害点对本文区划的中巴经济走廊地质灾害敏感性结果验证,表明区划的结果具有一定的科学、可信性,可以为中巴经济走廊重大工程建设、交通线路选线、城市规划、资源开发等方面提供科学依据。 相似文献