Ex situ echo sounder target strengths of ice krill Euphausia crystallorophias     

Hyoung Sul LA  Hyungbeen LEE  Donhyug KANG  SangHoon LEE  Hyoung Chul SHIN 《中国海洋湖沼学报》2015,33(3)

Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean,where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength(TS in d B re 1 m 2) with the different body size to accurately estimate ice krill stocks. However,there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual,formalin-preserved,tethered ice krill was measured in a freshwater test tank at 38,120,and 200 k Hz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths(L :13–36 mm). The length( L,mm) to wet weight( W; mg) relationship for ice krill was W =0.001 218×103 × L 3.53( R 2= 0.96). The mean TS-to-length relationship were TS3 8 k Hz =-177.4+57log 10( L),( R 2 = 0.86); TS 120 k Hz =-129.9+31.56 log 10( L),( R 2 =0.87); and TS 200 k Hz =-117.6+24.66log1 0( L),( R 2 =0.84). Empirical estimates of the relationship between the TS and body length of ice krill were established at 38,120,and 200 k Hz and compared with predictions obtained from both the linear regression model of Greene et al.(1991) and the Stochastic Distorted Wave Born Approximation(SDWBA) model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.  相似文献   

Biomarkers of exposure and effect in the Brazilian flounder Paralichthys orbignyanus (Teleostei: Paralichthyidae) from the Patos Lagoon estuary (Southern Brazil)     

Amado LL  Robaldo RB  Geracitano L  Monserrat JM  Bianchini A 《Marine pollution bulletin》2006,52(2):207-213

Biomarkers of exposure (liver metallothionein-like proteins content and catalase and glutathione S-transferase activities) and effect (liver lipoperoxidation and blood cell DNA damage) of contaminants were analyzed in the Brazilian flounder Paralichthys orbignyanus from the Patos Lagoon estuary (Southern Brazil). Flounders were collected for a year in two sites: "Coroa do Boi" (polluted site) and "Saco do Justino" (non-polluted site). Results indicated that micronucleated cells frequency was the best biomarker to distinguish flounders from the two sites. Taken together, data from DNA damage analyses (micronucleus test and comet assay) indicated that flounders from the non-polluted site efficiently repaired the DNA breaks, contrary to those from the polluted site, which probably had their DNA repair system inhibited or exhausted. Furthermore, data from enzyme activities (catalase and GST) and lipid peroxidation indicated that flounders from the polluted site were under oxidative stress in summer and autumn.  相似文献   

气候变暖背景下祁连山西部山区水循环要素的变化——以疏勒河干流上游山区为例   总被引：1，自引：0，他引：1  

蓝永超  胡兴林  丁宏伟  喇承芳  宋洁 《山地学报》2012,30(6)

根据祁连山区西部托勒气象站与疏勒河上游昌马堡水文站、鱼儿红雨量站的气温、降水、径流等观测数据,对近50年来疏勒河山区流域气温、降水、径流等水循环要素的变化特征与趋势进行了分析.结果表明,近50年来祁连西部山区年平均气温呈持续上升的态势,并在1990年代中期后出现一个突变,突变后气温上升速率较突变前明显加快.从气温的季节变化上看,冬季升温的幅度明显大于其他各季,从气温的区域变化来看,中低山地带的气温升幅要大于中高山地带.分析结果还显示,祁连山区西部年降水量总体上亦呈增长的态势,但年际波动比较剧烈.少雨年主要在1990年代以前,多雨年在近20 a;从季节变化上看,夏季降水量变化比较稳定,增减趋势不明显,其他各季降水量均有明显的上升趋势,冬季降水量增幅明显.受降水与气温加速上升所带来的冰雪融水增加的影响,疏勒河出山径流的年平均与四季流量亦呈显著增加的态势.考虑到山区夏季降水并未增加,故占年径流量比重较大的夏季径流量的增加主要是冰雪融水的贡献.  相似文献   

近50年疏勒河流域山区的气候变化及其对出山径流的影响   总被引：3，自引：0，他引：3  

蓝永超  胡兴林  肖生春  文军  王国亚  邹松兵  喇承芳  宋洁 《高原气象》2012,31(6):1636-1644

利用祁连山区水文站和气象站的观测数据,分析了近50年河西走廊西部疏勒河流域山区的气候变化及其对出山径流的影响。结果表明,受全球变暖的影响,疏勒河山区气候持续向暖湿转化,且各季气温均呈持续的上升趋势,山区降水量总体上亦呈增加趋势,年际波动比较剧烈。在各季降水量中,除夏季外其他各季降水量的增加比较显著,海拔3 000m以上中高山地带夏季降水量变化不大,3 000m以下中低山地带夏季降水量略有减少。受山区降水,尤其是3 000m以下中低山地带的降水量显著增加与气温上升所引起的冰雪融水补给的影响,疏勒河出山径流呈持续的增加趋势。由于夏季降水量并未增加,在年径流总量中所占比重最大的夏季径流量的增加主要是由于气温上升所引起的冰雪融水补给的增加所致。  相似文献   

LA CHINE EST-ELLE PLACEE ENTRE DEUX GRANDES FRACTURES DE LA CROUTE TERRESTRE ?     

PAR E.GHERZI 《地质学报》1925,4(2):81-86

Hest bien clair que toute reponse a cette question, sera du plus haut interet pour les geologues de la Chine, vu que les resultats de la geodesie semblent bien indiquer que la croute terrestre est divisee en plusieurs blocs independants, juxtaposes et equilibres isostatiquement.  相似文献   

REGULATION CONCERNING THE GRABAU MEDAL OF THE GEOLOGICAL SOCIETY OF CHINA     

PAR E.AHNERT 《地质学报》1925,4(2):95-97

Je me permets de soumettre a votre attention ce rapport, dont le sujet peut paraitre trop ordinaire—sur la decouverte d'une flore fossile. Mais dans les couches honilleres de la Russie de l'Extreme Orient et de la Manchourie du Nord, la decouverte de debris fossiles assez considerables pour per-  相似文献   

近40 a西藏那曲当惹雍错湖泊面积变化遥感分析   总被引：2，自引：2，他引：0  

拉巴卓玛  德吉央宗  拉巴  陈涛  次珍  邱玉宝  普布次仁 《湖泊科学》2017,29(2):480-489

西藏著名圣湖之一的当惹雍错,是藏北高原腹地内陆封闭大湖,对湖泊面积变化的长时间序列研究较少,本文通过高分辨率陆地资源卫星Landsat TM/ETM+数据源,利用遥感和地理信息系统软件,通过人工目视解译方法对1977-2014年当惹雍错湖泊面积变化进行系统分析,并结合流域临近气象站资料,流域冰川等辅助数据对其湖泊面积变化原因进行综合分析.结果表明,1977-2014年当惹雍错湖泊平均面积为835.75 km~2,1977-2014年湖泊面积总体呈上升趋势,1970s湖泊平均面积为829.15 km~2,1980s和1990s湖泊平均面积分别为827.50和826.42 km~2,2000年之后湖泊面积明显增加,2000s湖泊平均面积与1970s相比,增幅为8.04 km~2.当惹雍错湖泊空间变化特点是,位于最大河流入口处达尔果藏布的湖泊东南部扩大明显,湖泊西南部小湖1于2014年9月开始明显扩大并与当惹雍错有相连趋势;流域冰川融水是当惹雍错主要补给源,近40 a当惹雍错湖泊面积变化是在气温升高的背景下,冰川、降水量和蒸发量三者共同变化作用的结果.  相似文献   

东昆仑东段杨树沟金矿地质特征及找矿方向     

田永革  陈秉芳  韩晓龙  喇品贤 《地质与资源》2017,26(3):248-252

杨树沟金矿位于东昆仑成矿省伯喀里克-香日德印支期金、铅、锌、铁、石墨（铜、稀有、稀土）成矿带的东段.矿体严格受近东西向、北东向断裂构造控制.成矿类型为构造蚀变岩型金矿床,成矿时代为印支早期.矿区中已发现的金矿带深部及矿区东南部断裂发育地区具有较好的找矿空间,下一步工作应针对含矿构造破碎带,采用探矿工程与化探工作相结合等手段开展矿区东南部及深部找矿工作,寻找金矿体,争取该矿区找矿的更大突破.  相似文献   

Relating a recruitment shift of Patagonian grenadier (Macruronus magellanicus Lönnberg) to large-scale environmental changes off Southern Chile     

LA Cubillos  EJ Niklitschek  S Cahuin 《新西兰海洋与淡水研究杂志》2013,47(2):284-293

The SE Pacific stock of Patagonian grenadier (Macruronus magellanicus) showed evidence of an abrupt reduction in recruitment after 2000. This drop exceeded expectations from changes in the spawning stock biomass (SSB), indicating a change in the stock-recruitment relationship (S-R). We evaluated whether variability in recruitment could be explained by concurrent changes in three environmental indices: sea-surface temperature anomaly (SSTA); southern oscillation index (SOI); and latitudinal position of the west wind drift bifurcation (WWDL). Continuous and discrete effects of these indices were tested as covariates in linear log-log and non-linear Ricker's S-R models. Discrete effects represented regime shifts detected in SSTA (1998), SOI (1998) and WWDL (1995). While SSTA was the only continuous variable found to be significant, the discrete 1998 regime shift supported the most informative model. The best Ricker's model considered a discrete intercept change in the same year: 1998. Although a spurious correlation between SSTA and S-R changes is possible, SSTA may be reflecting major physical or biological changes relevant to M. magellanicus juveniles in the SE Pacific.  相似文献   

137Cs示踪法研究湟水上游和布哈河下游区域土壤侵蚀强度          下载免费PDF全文

陶炳德  沙占江  郭丽霞  拉本  肖景义 《干旱区地理》2013,36(6):997-1005

通过¹³⁷Cs示踪技术,并采用土壤剖面核素单位面积浓度与背景值之间的理论模型,对布哈河下游和青海湖东北岸湟水上游区域的土壤侵蚀进行了研究,结果表明：¹³⁷Cs面积活度与植被盖度之间存在着正相关关系,两区域相关系数为0.93。湟水上游河谷土壤侵蚀模数在87.62～1 458.41 t·km^-2·a^-1之间,采样点平均土壤侵蚀模数为933.31 t·km^-2·a^-1。布哈河下游区域土壤侵蚀模数在431.03～2 072.39 t·km^-2·a^-1之间,采样点平均土壤侵蚀模数为1 256.97 t·km^-2·a^-1。布哈河下游区域较湟水上游区域侵蚀严重,在较长的时期内两地大部分区域均处于轻度侵蚀阶段,湟水上游北部和布哈河下游西北部处于微度侵蚀阶段。  相似文献