Effects of dietary supplementation with algal astaxanthin on growth,pigmentation, and antioxidant capacity of the blood parrot ( Cichlasoma citrinellum × Cichlasoma synspilum )     

Li  Feng  Huang  Shuiying  Lu  Xiaoxia  Wang  Jun  Lin  Mingwei  An  Yu  Wu  Shaoting  Cai  Minggang 《中国海洋湖沼学报》2018,36(5):1851-1859

Journal of Oceanology and Limnology - An algal astaxanthin feeding trial was carried out to investigate the effects of natural astaxanthin from Haematococcus pluvialis as feed additives on growth,...  相似文献   

Modification of the Sm–Nd isotopic system in garnet induced by retrogressive fluids          下载免费PDF全文

Shi‐Chao An  Shu‐Guang Li  Zhen Liu 《Journal of Metamorphic Geology》2018,36(8):1039-1048

Garnet, as a major constitutive mineral of eclogite, is important for Sm–Nd dating of eclogite due to its high Sm/Nd ratio and its stability during retrogression. However, a comprehensive study of the petrography, mineral chemistry, garnet water content, and Sm–Nd isotopic composition of eclogites from the Bixiling massif, Central Dabie Zone (CDZ), reveals significant modification of the Sm–Nd isotopic system in garnet as a result of retrogression. This problem constitutes a challenge for Sm–Nd dating of the Bixiling eclogites, with the Sm–Nd isochron ages of 218 ± 4 to 210 ± 9 Ma reported in the literature being younger than 226 ± 3 Ma, which is the generally accepted peak metamorphic age of the CDZ. Petrographic analysis reveals heterogeneity in colour within single fractured garnet grains. There are light‐pink garnet (Grt‐P) and red garnet (Grt‐R) types that possess distinct chemical compositions. Compared to Grt‐P, Grt‐R has higher Fe and andradrite contents but lower Al and grossular contents. Grt‐P also has lower water contents (15–35 ppm) than Grt‐R (34–65 ppm), which, together with the spatial association between Grt‐R and fractures, suggests that the colour change is related to fluid alteration. Grt‐P is an ultra‐high‐pressure (UHP) mineral, and Grt‐R is the product of the interaction between Grt‐P and a fluid during retrogression. Moreover, Grt‐R features lower Sm and Nd contents but higher Sm/Nd ratios than Grt‐P. The Sm–Nd isochrons defined by UHP minerals (Grt‐P+Omp+Rt or Grt‐P+Cpx+WR) from three eclogite samples yield consistent ages of 226.0 ± 3.8 Ma, 225.0 ± 3.9 Ma and 226.2 ± 6.9 Ma, which are identical to the peak metamorphic age of 226 ± 3 Ma for the CDZ. The retrogressed garnet (i.e., Grt‐R), omphacite and rutile, together define a pseudoisochron with younger ages of 218.9 ± 5.9 to 202.8 ± 4.8 Ma, which are geologically meaningless. The increase in the Sm/Nd ratio with constant or lower ¹⁴³Nd/¹⁴⁴Nd ratios during the transformation of Grt‐P to Grt‐R was probably the cause of these younger ages.  相似文献   

雷达波段对多极化SAR海面溢油检测极化特征参数的影响   总被引：1，自引：1，他引：0  

宋莎莎  赵朝方  安伟  赵宇鹏 《海洋学报》2018,40(9):125-136

多极化SAR数据海面溢油检测研究日益受到重视。本文研究不同波段极化SAR数据的海面溢油检测能力，为最大程度减小观测条件、环境因素等的影响，选取准同步获取的SIR-C/X多极化SAR数据。针对海面油膜、生物油膜和低风区疑似溢油现象，研究L波段和C波段的共极化相位差、一致性系数、极化熵、各向异性和平均散射角等极化特征对海面油膜以及不同海面暗斑现象的检测能力。研究结果表明:在海面溢油检测以及探测不同暗斑现象间差异方面，C波段总体优于L波段；L波段，极化分解特征各向异性参数优于共极化相位差和一致性系数；C波段，共极化相位差、一致性系数特征优于极化分解特征各向异性和极化熵，结合平均散射角特征有助于滤除生物油膜和低风区。  相似文献   

DMSP-OLS与NPP-VIIRS夜间灯光数据测算统计指标能力评估——以京津冀地区县域GDP、人口及能源消耗为例     

李峰  张晓博  廖顺宝  钱安 《测绘通报》2020,(9):89

夜间灯光数据记录了地球表面的人造灯光强度，是估计社会统计指标的有效手段之一。为了评估DMSP-OLS和NPP-VIIRS 2种夜间灯光数据对社会统计指标的模拟潜力，采用4种常用的灯光校正方法分别对2种夜间灯光数据进行灯光饱和性校正，根据校正后的夜间灯光数据分别建立与京津冀地区县域GDP、人口和能源消耗3种社会统计指标间的线性回归模型，从模型拟合的相关系数、F统计量值与概率p值中分析并评价了2种夜间灯光数据对GDP、人口和能源消耗3种社会统计指标的测算能力。本文研究结果表明：EANTLI法是2种夜间灯光数据的最佳校正方式，而HSI法不适用于夜间灯光数据校正后与县域社会统计指标的线性关系拟合2种夜间灯光数据对GDP的拟合效果都较好，NPP-VIIRS夜间灯光数据估算社会统计指标的拟合能力要优于DMSP-OLS数据。  相似文献   

南海岛礁羊鲍(Haliotis ovina)资源及其栖息地环境研究     

王公嗣  符翔超  黄勃  罗安 《海洋与湖沼》2020,51(3):536-540

鲍是重要的海珍品,羊鲍(Haliotisovina)是主要生活在热带岩岸潮间带大型经济鲍类底栖动物。为了研究南海岛礁羊鲍资源及其栖息环境,我们在宣德群岛的永兴岛和七连屿,永乐群岛的羚羊礁、甘泉岛和晋卿岛进行了羊鲍资源分布及其栖息水环境研究。按照《海岛调查技术规程》中潮间带岩岸大型底栖生物调查方法,对羊鲍进行取样调查。按照《海洋调查规范第4部分:海水化学要素调查》(GB T 12763.4-2007),对羊鲍栖息地水环境的总无机氮、活性磷酸盐、悬浮物和叶绿素a等海水化学要素进行分析。结果表明,羊鲍在永乐群岛和宣德群岛都有分布,这些岛礁按永兴岛、七连屿、羚羊礁、甘泉岛和晋卿岛的顺序,分布密度依次增加,个头大小依次增大,总体来说羊鲍资源量小,有的岛礁海区几乎绝迹,亟需开展生态增殖和资源养护研究工作。水质调查表明,除永兴岛站位的悬浮物指标因填海作业未达标外,各站位的水质指标均达一类水标准且具有一定稳定性。因此,尽管南海岛礁受人类活动的影响,但该海域仍适合羊鲍栖息,是羊鲍资源养护、底播生态增殖和生态养护的适宜场所,符合建立海洋保护区的国家水质标准和环境条件。  相似文献   

Spatial and temporal variability of 0‐ to 5‐m soil–water storage at the watershed scale          下载免费PDF全文

Zihuan Fu  Yunqiang Wang  Zhisheng An  Wei Hu  Khan M.G. Mostofa  Xuezhang Li  Bingxia Liu 《水文研究》2018,32(16):2557-2569

Dynamic relationships among rainfall patterns, soil water distribution, and plant growth are crucial for sustainable conservation of soil and water resources in water‐limited ecosystems. Spatial and temporal variation in deep soil water content at a watershed scale have not yet been characterized adequately due to the lack of deep soil water data. Deep soil–water storage (SWS) up to a depth of 5 m (n = 73) was measured at 19 sampling occasions at the LaoYeManQu watershed on the Chinese Loess Plateau (CLP). At a depth of 0–1.5 m, the annual mean SWS was highly correlated with rain intensity, and the correlation decreased with depth, but within the layers at 1.5–5.0 m, the changes in SWS indicated a lag between precipitation and the replenishment of soil water. Geostatistical parameters of SWS were also highly dependent on depth, and the mean SWS presented similar spatial structures in two adjacent layers. Temporal stability of SWS as indicated by mean relative difference, standard deviation of the relative difference (SDRD), and mean absolute bias error (MABE) was significantly weaker at the shallow than at deeper layers. Soil separates and organic carbon content controlled the spatial pattern of SWS at the watershed scale. One representative location (Site 57) was identified to estimate the mean SWS in the 1‐ to 5‐m layer of the watershed. Semivariograms of the SDRD and MABE were best fitted by an isotropic spherical model, and their spatial distributions were depth‐dependent. Both temporal stability and spatial variability of SWS increased over depth. This study is helpful for deep SWS estimation and sustainable management of soil and water on the CLP, and for other similar regions around the world.  相似文献   

极地冰下生物地球化学过程研究进展     

马红梅  孙波  姜苏  安春雷  史贵涛  李院生 《地球科学进展》2012,27(2):147-153

已有的研究结果表明:极地冰下存在生命活动的证据。生物地球化学过程以其独特的视角,从生物学和地球化学学科交叉的角度,对于诠释冰下环境微生物生存及其对全球气候的影响提供了一条新途径。目前对于冰下生命的研究多集中在温型冰川和多温型冰川,关于冷型冰川冰下环境的生物起源、生存条件、能源转化方式和生物体的空间分布特征及种属关系等研究均还处在起步阶段。在简要阐述冰下化学风化机理发展历程的基础上,对近年应用生物地球化学过程研究极地冰下环境的研究成果进行总结和分析。此外,针对该领域目前研究上的空白和热点,分别对利用生物地球化学过程研究冰下环境微生物生存和繁衍,冰下温室气体释放,重大古气候事件探索及星际生命探索等科学命题进行展望。  相似文献   

基于突变模型的泥石流危险度评价     

安玉华  王清  张晨  赵传海 《吉林大学学报(地球科学版)》2012,(Z1):355-361

基于突变理论模拟了乌东德地区泥石流的爆发。突变模型适于表达开放系统,假设危险度的影响因子是突变模型中的控制变量,利用初等突变模型对泥石流危险度进行多目标评估,根据当地的实际情况制定对应的评价标准。结果表明,模型在奇点处发生突变时泥石流爆发,该结果与传统的灰关联法计算结果基本一致,且与实际调查的情况较为吻合。  相似文献   

A Holocene dust record in arid central Asia inferred from Lake Barkol,northwest China   总被引：1，自引：1，他引：0  

Yanbin Lu  Chengbang An  Jiawu Zhang  Zongli Wang  Shichen Tao  Jiaju Zhao 《Environmental Earth Sciences》2012,65(1):213-220

Grain-size distributions and detrital minerals were investigated for modern dust and for lacustrine sediment in Lake Barkol region, northwest China. Characteristics of the modern dust and lacustrine sediments, principle component analysis, and changes of quartz contents all suggest grain size 45–138 μm in the core sediment is the dust sensitive component. It indicates that high dust flux climate occurred at mid-Holocene (5.5–4.5 cal ka BP), corresponding to the high dust flux record in northwest Pacific and the drought interval of deserts in northwest China during the mid-Holocene. The strong dust activity is in contradiction with the climatic optimum recorded by the lacustrine evidence in Xinjiang. Different responses of the dust source region and watershed to the regional climate may have led to the inconsistency between dust and climate records during the mid-Holocene in arid central Asia.  相似文献   

Hot spots of wetland vegetation reduction in relation to human accessibility: differentiating human impacts on natural ecosystems at multiple scales     

Sheng Sheng  Chi Xu  Shaowei Zhang  Shuqing An  Maosong Liu  Xuejiao Yang 《Environmental Earth Sciences》2012,65(7):1965-1975

Human activities have profoundly influenced natural ecosystems, especially wetlands. This study attempted to differentiate the impact of human activities on reductions in wetland vegetation in the Lixiahe wetlands, China, at multiple spatial scales. The reduction in wetland vegetation from 1988 to 2006 was quantified using Landsat data, and moving window analysis was used to detect hot spots of vegetation reduction in the wetlands at window sizes of 150, 1,000 and 2,500 m. Logistic regression was used to examine the influence on occurrence of the hot spots of landscape variables representing accessibility to human settlements and roads. Over the study period, wetland vegetation declined by 69%, which was largely attributable to aquaculture development. The hot spots of wetland vegetation reduction exhibited increasing patch size, but decreasing patch number with increasing window size. The occurrence probability of the hot spots rose significantly with increasing proximity to rural settlements and secondary roads, with only a minor response to the presence of towns. With increasing window size, however, the density of secondary roads and rural settlements were less influential, whereas the presence of major roads had more influence on hot spot occurrence. These trends are reasonable in that wetland use activities in the study area are directly associated with the settlements and roads in the rural areas at local scales, but are also indirectly associated with the major transportation network from a regional perspective. Overall, these results suggested that different human activities, as distinguished by their sources on the landscape, could have different environmental consequences at different scales for scale-dependent features.  相似文献