南黄海冷水团海域溶解氧和叶绿素最大现象值及营养盐累积的季节演变   总被引：7，自引：0，他引：7  

韦钦胜  傅明珠  李艳  王保栋  于志刚 《海洋学报》2013,35(4):142-154

基于2006-2007年在南黄海冷水团海域开展的4个季度月的调查资料, 重点研究了该海域溶解氧(DO)、叶绿素a(Chl a)最大值现象和营养盐累积的季节演变规律。结果表明:春至秋季黄海冷水团海域DO和Chl a最大值层深度具有先加深后变浅的趋势, 出现最大值层的海域面积呈现出先增大后缩小的变化过程, DO和Chl a最大值层的深度及面积在夏季均达到最大, 至冬季DO和Chl a最大值现象消失;夏季冷水团海域深水区DO最大值处的氧含量整体高于春季, 而冷水团边界附近氧最大值处的氧含量整体低于春季;春至秋季冷水域深水区次表层Chl a最大值处的Chl a含量先降低后升高, 于夏季时最低, 入秋后开始升高, 而一年四季中冷水域边界附近Chl a最大值处的Chl a含量却在夏季时最高, 而且显著高于深水区。黄海冷水团海域的底层营养盐储库具有一定的空间异质性, 冷水域底层通常分别在深水区和西部边界处存在营养盐高值核心, 其中位于深水区的高值核心位置季节变化不明显, 而位于冷水域西部边界附近的高值核心位置则呈现出自春季至夏季向西移动、入秋后又向东部移动的季节变化特征。水文物理因素和生物化学过程对DO、Chl a最大值及营养盐储库的季节演变具有重要的调控作用。  相似文献   

黄海西部沿岸冷水在夏季南黄海西部底层冷水形成和季节演变过程中作用的化学水文学分析     

韦钦胜  于志刚  葛人峰  王辉武  王保栋 《海洋与湖沼》2013,44(4):890-905

以金枪鱼碎肉为原料, 采用双酶分步水解法制备高F值酶解液, 通过Box-Behnken试验设计, 分别确定两步酶解的最佳条件, 酶解液经活性炭静态吸附去除游离芳香族氨基酸, 对脱芳后的酶解液进行氨基酸组成分析并测定F值。结果表明, 胃蛋白酶为第一步水解用酶, 酶解的最佳工艺条件为酶用量650U/g, 料水比1∶7(g/mL), 温度35.9℃; 风味蛋白酶为第二步水解用酶, 酶解的最佳工艺条件为酶用量50700U/g, pH 6.51, 温度51℃, 最终水解度达到36.87%±0.54%; 酶解液在pH 3.0, 温度35℃条件下, 经5%(质量体积分数)的活性炭吸附时间3h后, 脱芳率达到63.18%, F值为30.33, 符合高F值肽的要求。  相似文献   

黄海冷水团新生产力及微食物环作用分析   总被引：8，自引：0，他引：8  

李杰  吴增茂  万小芳 《中国海洋大学学报(自然科学版)》2006,36(2):193-199

为了进一步揭示黄海冷水团水域浮游生态系统能流、物流循环的基本动力学特征,利用水层-底栖耦合生态系统垂直3层模型,模拟分析了该水域生源要素的基本特征及年变化特点,并着重分析了初级生产力、新生产力及微食物环作用。通过对黄海冷水团水域初级生产力和新生产力的模拟分析,估算出黄海冷水团年平均初级生产力为228.47mg.m-2.d-1,并根据模型中营养盐的来源估算出f比约为33%。分析模拟结果还表明,在黄海冷水团存在的季节,冷水团水域水层营养盐匮乏,浮游植物生产受限制,仅在晚秋出现了不十分明显的“秋华”。然而,在此时段内,浮游动物的生物量基本和浮游植物为同一量级且量值比较接近,由此可推断微食物环在黄海冷水团能流、物流循环过程中担当了重要的角色。模拟结果表明,浮游动物生长所需的碳约有60%是通过微食物环供给的。与实测及文献结果相比较,模型的模拟结果是合理可信的。  相似文献   

Absolute parameters of four W UMa stars with extreme low mass ratios     

《New Astronomy》2022

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石河子市空气质量特征及其气象影响因素的研究          下载免费PDF全文

安冬亮  李霞  雷薇 《沙漠与绿洲气象(新疆气象)》2023,17(2):74-80

运用石河子市2015—2020年6种污染物浓度，研究了石河子市近6年空气质量及污染物浓度时间变化特征。结果显示：石河子市近6年空气质量有所改善，首要污染物主要以可吸入颗粒物和臭氧为主，并有明显的采暖期和非采暖期之分。冬季空气质量对全年空气质量优良天数占比为负贡献，各污染物浓度的峰值多出现在白天。分析石河子市相对湿度、气压、温度等气象要素和空气质量指数的相关性，并建立拟合方程，结果显示石河子市除冬季外其他时间最小相对湿度、最低气温和空气质量指数相关性较好，在预报空气质量过程中可重点考虑。  相似文献   

Paleo- and Mesoarchean TTG-sanukitoid to high-K granite cycles in the southern São Francisco craton,SE Brazil     

《地学前缘(英文版)》2022,13(5):101372

The generation of the continental crust is widely accepted to have taken place predominantly in the Archean, when TTG magmatism associated with greenstone-belt supracrustal succession development was typically followed by emplacement of high-K granites before crustal stabilization. This study focuses on the Campos Gerais complex (CGC), which is an Archean granite-greenstone belt lithological association in a tectonic window located in the southwesternmost portion of the São Francisco craton (SFC). The CGC is an important segment of Paleo- to Mesoarchean continental crust to be integrated into paleogeographic reconstructions prior to the transition into the Paleoproterozoic. This investigation reports field relationships, 28 major and trace element compositions, U–Pb (zircon) geochronological results, and Hf and Sm–Nd isotope data for orthogneiss and amphibolite samples. The results indicate that the CGC records a complex Archean crustal evolution, where voluminous 2.97 Ga TTG tonalites and trondhjemites (ε_Nd(t) =  ? 4.7; T_DM = 3.24 Ga) were followed by 2.89 Ga sanukitoid tonalite production (ε_Nd(t) =  ? 1.9; T_DM = 3.02 Ga), broadly coeval with the development of the Fortaleza de Minas and Pitangui greenstone-belts. These events are interpreted to represent the initial stage of an important subduction-accretion tectonic cycle, which ended with the emplacement of 2.82–2.81 Ga high-K leucogranites and migmatization of the TTG-sanukitoid crust, with hybrid and two-mica, peraluminous compositions (ε_Nd(t) =  ? 8.0 to ? 8.6; T_DM = 3.57 – 3.34 Ga). The presence of inherited zircons with ²⁰⁷Pb/²⁰⁶Pb ages of 3.08 Ga, 3.29 Ga, 3.55 Ga and 3.62 Ga indicates that the Mesoarchean tectonic processes involved reworking of Meso- to Eo-archean crust. Renewed TTG magmatism took place at ca. 2.77 Ga represented by juvenile tonalite stocks (ε_Nd(t) = +1.0 to ? 1.5; T_DM = 2.80 – 2.88 Ga) which intrude the TTG-greenstone belt association. Crustal stabilization was attained by 2.67 Ga, allowing for the emplacement of within-plate tholeiitic amphibolites (ε_Nd(t) =  ? 3.1; T_DM = 2.87 Ga). The CGC shows important tectonic diachronism with respect to other Archean terrains in the southern São Francisco craton, including an independent Meso- to Neoarchean crustal evolution.  相似文献   

Exposure to extreme climate decreases self-rated health score: Large-scale survey evidence from China     

《Global Environmental Change》2022

High temperature is a growing threat and impacts public health through different exposure mechanisms. Our study constructs a comprehensive exposure measurement based on temperature variability, duration, and effective influence range. We investigate human responses to high temperatures through self-rated health scores based on individual-level data from China Labor-force Dynamic Survey (CLDS). Results show that higher temperature and temperature variability significantly decrease self-rated health scores. Subjective health risk is most significantly related to the cumulative temperature in the previous two weeks. We also find that the exposure effects at night and on weekdays are more severe. Workers who experience greater exposure from commuting and work environments are negatively impacted by high temperatures. In addition, men, the elderly, middle and low education groups, rural residents are more likely to be impacted by high temperatures.  相似文献