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91.
福建近海主要经济渔业生物营养级和有机碳含量研究 总被引:2,自引:0,他引:2
本文研究了福建近海52种鱼类、6种虾类、4种蟹类、1种虾蛄和4种头足类的食性和营养级及其有机碳含量。结果表明:营养级以鱼类最高,为2.1~3.7级,平均2.65级;头足类为2.04~2.88级,平均2.60级;蟹类2.38~2.73级,平均2.58级;虾类最低,为1.64~2.21级,平均1.96级.干样有机碳含量百分率也以鱼类最高,为33.0%~76.2%(m/m),平均46.25%(m/m);头足类为27.80%~46.16%(m/m),平均40.24%(m/m);虾类为30.60%~38.40%(m/m),平均34.90%(m/m);蟹类最低,为25.00%~30.78%(m/m),平均28.24%(m/m),鲜样有机碳含量百分率还是以鱼类最高,为4.80%~29.55%(m/m),平均13.75%(m/m);蟹类为8.90%~12.68%(m/m),平均10.74%(m/m);虾类为6.97%~11.53%(m/m),平均9.55%(m/m);头足类最低仅为7.38%~8.52%(m/m),平均7.95%(m/m),干样有机碳含量百分率和鲜样有机碳含量百分率与营养级均成正相关,但前者的相关性高于后者。 相似文献
92.
Resolving physically and biologically driven suspended particulate matter dynamics in a tidal basin with a distribution-based model 总被引:1,自引:0,他引:1
Understanding suspended particulate matter (SPM) dynamics in coastal waters is crucial to assess changes in coastal sediment budgets and biogeochemical fluxes. SPM dynamics are subject to various physical and biological factors and processes such as, e.g. tidal currents and aggregation which can be enhanced by extracellular polymeric substances (EPS) that are produced by algae and bacteria. It is still unclear how the different factors and processes interact and together determine SPM dynamics. To unravel the interacting processes and factors, we propose a new distribution-based modeling approach. Based on the derivation of explicit equations for size distribution characteristics of SPM such as the average radius, we derived a model of reduced complexity characterized by low initialization and parameterization effort as well as low computational cost. The proposed 0D model includes the processes of aggregation and fragmentation due to shear, aggregation due to differential settling, deposition, resuspension and tidal exchange, and describes the evolution of the SPM concentration in the water column linked by the settling velocity to the change of the mass average radius of the aggregate distribution. A systematic parameter variation for critical bottom shear stress of erosion, the size of resuspended aggregates, the fractal dimension, the collision efficiency, and the aggregate strength has been performed and compared to observations in the back-barrier basin of Spiekeroog Island in the German Wadden Sea. This analysis confirms the hypothesis that in winter biological influences on SPM dynamics are smaller compared to summer. This is mainly reflected by a significant shift in the various parameters. We hence conclude that biological control mechanisms have a much more quantitative relevance for SPM dynamics than currently represented by state-of-the-art SPM transport models. 相似文献
93.
Stable isotopes of water have been widely used in understanding the hydrological functions of alpine inland catchments. This study identifies dominant runoff generation mechanisms based on isotopic data (δ18O and δ2H) of 487 rainwater and river-water samples from three tributaries in the Tarim River Basin in China for the period May–September 2013. The isotope hydrograph separation results provide a comprehensive overview of the rainfall influence on hydrological processes. Stream water and groundwater have varied responses to different intensities of rainfall events. Only a small proportion of rainfall is directly transported to the stream during such events. An inconsistent temporal trend of event water contribution is observed in the three catchments. The average fractional contributions of rainfall for the Tizinafu, Kumalak and Huangshuigou rivers are 10.3% (±1.1%), 9.7% (±2.9%) and 8.7% (±2.4%), respectively. 相似文献
94.
东昆仑阿拉克湖地区第四纪水系演化过程及其趋势 总被引:6,自引:0,他引:6
根据第四系沉积物的沉积时代、沉积类型及盆山耦合与迁移规律,将东昆仑阿拉克湖地区第四纪水系变迁划分了4个阶段:早更新世小型内陆盆地无序水系阶段;中更新世冰川水系与东流水系阶段;晚更新世柴达木盆地内陆水系向南溯源侵蚀阶段;全新世黄河外泄水系形成与发展阶段。根据研究区及相邻地区黄河水系和柴达木盆地内陆水系的溯源侵蚀发展历史及趋势分析,认为研究区未来水系发展趋势不一定是加鲁河袭夺鄂陵湖、扎陵湖两湖及黄河水系,而可能是黄河加快下蚀作用和溯源侵蚀,鄂陵湖和扎陵湖将逐渐消失成为河流,黄河水系最终将袭夺柴达木内陆盆地水系。 相似文献
95.
Seasonal Study of Methane and Nitrous Oxide in the Coastal Waters of the Southern Baltic Sea 总被引:2,自引:0,他引:2
H.W. Bange S. Dahlke R. Ramesh L.-A. Meyer-Reil S. Rapsomanikis M.O. Andreae 《Estuarine, Coastal and Shelf Science》1998,47(6):807-817
Atmospheric and dissolved methane (CH4) and nitrous oxide (N2O) were measured in the unique coastal ecosystem of theBoddenwaters, including the western Oder estuary, (southern Baltic Sea) during five campaigns between 1994 and 1997. The CH4saturations, ranging from 105–15 500%, showed great spatial and temporal variability with maximum values in September and minimum values in December. The N2O saturations were in the range of 91–312% with a maximum in March. Enhanced concentrations of both gases were observed only in the western Oder estuary near the mouth of the Peene River. Thus, we conclude that the distributions of CH4and N2O in the investigatedBoddenwaters are, directly or indirectly, linked to the Peene River runoff and not to the Oder River. Our estimate of the annual CH4emissions from theBoddenwaters to the atmosphere indicates a significant contribution (c. 17%) to the overall CH4emissions from the Baltic Sea. In contrast, theBoddenwaters represent only a small source for atmospheric N2O.CH4production rates estimated from sediment slurry experiments revealed a significant spatial variability and indicated that methanogenic activity was related to acetate consumption in the surface sediment layer. Sedimentary CH4production might depend on different amounts of accumulation of organic material. 相似文献
96.
南极冰盖对海平面影响巨大,高程变化测量是南极物质平衡监测的重要手段。采用欧空局CryoSat-2雷达高度计数据,通过提取卫星升降轨的地面交叉点,监测了南极内陆冰盖的高程变化(物质平衡)。结果表明,后向散射能量对Ku波段的CryoSat-2雷达高度计的高程数据具有一定的影响,经后向散射能量校正后,时间序列上的高程变化变得平缓,高程变化与已有的降雪数据相比,更加符合实际情况。2010年11月至2017年11月南极内陆冰盖高程变化趋势为(-1.1±0.2)cm·a-1。西南极的Kamb冰流高程变化率为(38.7±1.1)cm·a-1,Moeller冰流高程变化率为(-10.3±1.2)cm·a-1,部分Thwaites冰川区域高程变化率为(-13.4±1.8)cm·a-1,东南极的Wilkes Land出现高下降区,最高达-20 cm·a-1。Dronning Maud Land虽然出现变化异常的点,但整体并没有显著的高程变化。南极内陆冰盖质量变化为(-10.6±6.2)Gt·a-1,整体上南极内陆冰盖质量变化平缓,部分区域变化较大,Kamb冰流达到(17.9±0.5)Gt·a-1,Moeller冰流达到(-3.4±0.4)Gt·a-1,部分Thwaites冰川区达到(-3.7±0.5)Gt·a-1。 相似文献
97.
利用山东数字地震台网的地震波形记录,选取2007年以来台网记录清晰的ML≥2.0数字地震波形资料,计算每次地震的环境剪应力值τ0和矩震级MW,并分析其相关关系;结合山东地区地质构造和地震活动性特点,对胶东半岛及北部海域、南黄海北部地区、沂沭带地区、冀鲁豫交界地区应力场分布和时空变化进行细致分析,并探讨其区域特征及与地震活动性的关系。 相似文献
98.
Björn S. Frengstad Kaj Lax Timo Tarvainen Øystein Jæger Börge J. Wigum 《Journal of Geochemical Exploration》2010
Twenty-two bottled mineral and spring waters from Norway, Sweden, Finland and Iceland have been analysed for 71 inorganic chemical parameters with low detection limits as a subset of a large European survey of bottled groundwater chemistry (N = 884). The Nordic bottled groundwaters comprise mainly Ca–Na–HCO3–Cl water types, but more distinct Ca–HCO3, Na HCO3 and Na–Cl water types are also offered. The distributions for most elements fall between groundwater from Fennoscandian Quaternary unconsolidated aquifers and groundwater from Norwegian crystalline bedrock boreholes. Treated tap waters have slightly lower median values for many parameters, but elements associated with plumbing have significantly higher concentrations in tap waters than in bottled waters. The small dataset is able to show that excessive fluoride and uranium contents are potential drinking water problems in Fennoscandia. Nitrate and arsenic displayed low to moderate concentrations, but the number of samples from Finland and Northern Sweden was too low to detect that elevated concentrations of arsenic occur in bedrock boreholes in some regions. The data shows clearly that water sold in plastic bottles is contaminated with antimony. Antimony is toxic and suspected to be carcinogenic, but the levels are well below the EU drinking water limit. The study does not provide any health-based arguments for buying bottled mineral and spring waters for those who are served with drinking water from public waterworks. Drinking water from crystalline bedrock aquifers should be analysed. In case of elevated concentrations of fluoride, uranium or arsenic, most bottled waters, but not all, will be better alternatives when treatment of the well water is not practicable. 相似文献
99.
100.