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761.
分析了苏、皖石炭系石灰岩的胶结作用。查明了胶结物的晶形、碳、氧同位素成分、发光特征及包体均一化温度。指出胶结作用主要发生在大气淡水补给较充分的含水层内,这与本区属海退成岩序列有关。 相似文献
762.
胶州湾菲律宾蛤仔死壳分布与生态环境关系的研究 总被引:1,自引:0,他引:1
胶州湾菲律宾蛤仔栖息地带由于近年受拖耙捕生产,底质遭到频繁骚动。同时沿岸带局部水域环境污染严重,以及河口盐度突发性骤降等因素,直接影响了蛤仔的存活率。因而蛤仔死壳逐年增多。据1990年调查,9月份幼蛤和成蛤死壳平均密度比同年4月分别增加3.5倍和1.8倍,蛤仔资源量亦受一定损失。 相似文献
763.
山东省9216号强热带气旋风暴期间的海岸侵蚀灾害 总被引:14,自引:0,他引:14
本文比较详细地报导了山东省沿岸在9216号强热带气旋风暴潮期间的海岸侵蚀灾害情况,分析了灾害的形成原因、特点。最后讨论了与之有关的问题。 相似文献
764.
两种荧光分析法在海洋浮游植物叶绿素测定中的应用 总被引:3,自引:0,他引:3
以湛江叉鞭金藻为材料.用普通荧光分析法测定了chla、chic的荧光发射光谱,以四乳突扁藻为材料,用普通荧光分析法和同步荧光分析法测定了chla、chlb的荧光发射光谱,结果表明:chla、chlb、chic的荧光发射峰分别为670nm、655nm、640nm,普通荧光分析法适于进行浮游植物所含的chla、chlc的定性、定量测定,而不适于进行chla、chlb的同时测定;同步荧光法则适于进行浮游植物中chla、chlb的定性、定量的同时测定。 相似文献
765.
为了探讨琼东南盆地华光凹陷海底天然气水合物稳定带的分布规律,定量研究了静水压力、底水温度、地温梯度和气源组分对水合物稳定带的影响程度。在此基础上,分析了华光凹陷现今甲烷水合物稳定带的厚度分布。最后,综合各因素的历史演化过程,初步探讨了华光凹陷1.05 Ma BP以来天然气水合物稳定带的演化。结果表明:(1)气源组分和海底温度的变化对研究区内水合物稳定带的影响较大;水合物稳定带厚度与海底温度呈良好的线性负相关性。(2)水深超过600 m的海域具备形成天然气水合物的温压条件;超过600 m水深的海域水合物稳定带厚度大部分超过 100 m,其中西北部稳定带的最大厚度超过300 m,是有利的水合物勘探区。(3)华光凹陷1.05 Ma BP以来天然气水合物稳定带厚度经历了快速增厚–窄幅变化–快速减薄和恢复的过程。麻坑群与水合物稳定变化敏感区在空间上具有较好的叠合关系。结合前人的研究成果,推测其形成与天然气水合物的分解释放有关。 相似文献
766.
The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle. It is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the atmosphere. Methane bubbles produce strong acoustic impedance in water bodies, and bubble strings released from deep sea cold seeps are called "gas flares"which expressed as flame-like strong backscatter in the water column. We characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold seeps. The result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ, 850 m), while methane bubbles at site II passed through the top of the GHSZ(597 m) and entered the non-GHSZ(above 550 m). By applying two methods on the multibeam data, the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s, respectively. Bubble velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the water. Combined with numerical simulation, we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies, while other factors, including water depth, bubble velocity, initial kinetic energy and bubble size, also influence the bubble residence time in the water and the possibility of methane entering the atmosphere. We estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body, however, methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold seeps. In addition, although methane entering the atmosphere is not observed, further research is still needed to understand its potential impact on increasing methane concentration in the surface seawater and gas-water interface methane exchange rate, which consequently increase the greenhouse effect. 相似文献
767.
Yunquan Li Silin Wu Shi Shu Yiyan Lv Yan Cui 《Marine Georesources & Geotechnology》2020,38(5):604-610
AbstractWith the growing demand for underwater refill engineering, the construction technology of implementing fluidized solidification in underwater pouring has recently received increased attention. However, the environmental impact of underwater casting on surrounding water bodies, especially when the silt is polluted, is still unclear. In this study, a simulated underwater pouring test and a static immersion release test were conducted separately to study the quality of the surrounding water during and after pouring. The results showed that fluidized-solidified silt casting could increase the pH of the surrounding water, even after the pouring had stopped, by approximately 1.0 and the turbidity could reach 200 NTU. No diffusion of Zn and Cu into the surrounding water was observed and while Ni and Cr exhibited slight diffusion, this was at a level well below international water quality standard. During construction, reducing the distance from the seafloor to the bottom of the pouring catheter could reduce the level of pollution. After construction, the use of neutral solidified materials can effectively reduce the pH of the surrounding water and the potential risk of heavy metal dissolution. 相似文献
768.
天水-秦安一带中新世黄土堆积区沉积-地貌演化 总被引:5,自引:0,他引:5
前人的构造地质学研究,将天水-秦安一带的中新世黄土分布区划归两个不同的构造单元.文章基于野外调查和已有年代地层学工作,结合前人成果,对该区新生代沉积-地貌演化历史进行研究,并划分为以下主要阶段:1)古近纪初南部秦岭山地的剥蚀,使本区在原有基岩准平原地形的基础上,形成以冲洪积平原为主的地形.古近纪末-新近纪初的构造活动使冲洪积平原解体,在秦安地区形成基岩台地与沉陷盆地相间、天水-西和地区形成拉分盆地与隆起山地交错的地貌景观,这些高地为中新世黄土堆积提供了地形基础.2)中新世从22Ma到11Ma,基岩台地和相对平缓的高地上堆积典型黄土-古土壤序列,盆地内则主要发育次生黄土等洼地沉积,表明研究区类似于今天的黄土高原.3)中新世晚期约11Ma起发生的一次侵蚀事件,使研究区的一些小盆地内发育河流相和间歇性浅湖相沉积,秦安一带的黄土堆积也遭到侵蚀,形成的洼地内发育黄土状土或洼地静水沉积,其中包含较多哺乳动物化石,而大范围的相对平坦高地上一直继续发育黄土-古土壤序列.这次侵蚀对本区内甘肃群的沉积多样性有重要贡献,但一直没有深水湖泊发育的条件.4)发生于3.5Ma以后的另一次重大侵蚀,奠定了该区今天狭窄长墚地形的基础,是第四纪黄土堆积在本区保存较差的主要原因. 相似文献
769.
770.
长江三角洲城市带扩展对区域温度变化的影响 总被引:7,自引:0,他引:7
Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional cli- matic trend of temperature in the Yangtze River Delta (YRD) was analyzed. Conclusions are as follows: 1) There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing–Zhenjiang–Yangzhou, Suzhou–Wuxi–Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28–0.44℃/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2) The urban heat island (UHI) effect on regional mean air temperature in different seasons is summer>autumn>spring>winter. 3) The UHI intensity and the urban total population logarithm are creditably correlated. 4) The UHI effect made the regional annual mean air temperature increased 0.072℃ from 1961 to 2005, of which 0.047℃ from 1991 to 2005, and the annual maximum air temperature increased 0.162℃, of which 0.083℃ from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal. 相似文献