沉积物中碳酸盐(方解石和白云石)测定方法的研究

研究河流和浅海陆架沉积物中的碳酸盐成因和生成环境,探讨河流和陆架沉积物中碳酸盐含量的影响因素和测定方法。结果表明,沉积物中碳酸盐含量明显受沉积物粒度组成和物源的影响。1mol/LHAc lmol/LNaAc(在沸水浴加热30min),0.3mol/LHAc(室温下5h)和1mol/LHCl(室温下2h)分别做碳酸盐相 离子交换相的浸取液,lmol/LNaAc(在沸水浴加热30min)做离子交换相的浸取液,然后用ICP-AES测得浸取液中Ca和Mg离子含量,差减法计算样品碳酸盐相中Ca,Mg离子和碳酸盐含量。其中前两者与第四种相结合的方法,都能得到河流沉积物碳酸盐相中的Ca离子含量。而第三种方法,即1mol/LHCl(室温下2h),破坏了沉积物中的粘土矿物,不能用来作为沉积物碳酸盐相 离子交换相中Ca和Mg离子的浸取液。与使用ICP-AES测定离子含量计算得出的碳酸盐含量的方法相比较,容量法是1种操作简单、花费低廉且有效的方法。     

现代黄河水下三角洲地质灾害现象的空间分布

利用浅地层剖面、旁扫声纳剖面及测深资料对现代黄河水下三角洲的地质灾害现象进行了研究,发现三角洲不同的形成时期对应发育不同的地质灾害现象:①在现行河口地区,高浓度泥沙下潜海底形成了黄河口独特的浊流现象,河口泥沙的快速堆积和欠固结导致河口三角洲叶瓣以台阶状滑塌陡坎的形式向海尖灭;②由于河口物源断绝和受到冬季北风或偏北风作用,海底滑坡、冲蚀构造等大型地质灾害现象在老河口废弃三角洲叶瓣北侧大量发育;③埕北地区与孤东地区情况较为相似,经过长时间改造之后多种灾害地质现象大量分布,且在水深5~10 m的三角洲陡坡上最为发育。     

区域防震减灾能力评估方法研究

本文通过对影响减灾能力的因素分析,建立了宏观地震减灾能力层次分析模型。其中目标层为生命损失;准则层为工程抗震能力、社会经济减灾能力、应急救援与恢复能力;指标层为抗震设防能力、防御次生灾害能力、居住地类型、人均GDP、三产比例、地震预报、工程预警、救援医疗、物资储备。用层次分析法得到在遭遇第一水准烈度、第二水准烈度和第三水准烈度时各项指标减灾能力的权重值。结果表明,三种情况下抗震设防能力的权重都是最大的,因此加强建筑物的抗震能力,是减少人员伤亡的最佳解决方案。     

土层分层厚度对设计地震动参数的影响

对同一场地改变土层分层厚度分别建立四种土层反应分析计算模型,输入人工合成的基岩地震波,分别进行土层地震反应分析计算,得到相应的地表加速度峰值和反应谱。对计算得到的结果进行分析比较,最终得出分层厚度对地震动参数的影响。     

Biomarker evidence for paleoenvironmental changes in the southern Yellow Sea over the last 8200 years

Previous studies have indicated that the Yellow Sea underwent significant environmental changes during the Holocene, but many questions remain concerning the timing of the establishment of the modern circulation system, which would have major implications for the Yellow Sea ecosystem and carbon cycle. In this study, marine and terrestrial biomarkers were analyzed in Core YE-2 from a muddy area in the southern Yellow Sea to reconstruct Holocene environmental and phytoplankton community change. The content of three individual marine phytoplankton biomarkers (alkenones, brassicasterol and dinosterol) all display a similar trend, and their total contents during the early Holocene (362 ng/g) were lower than those during the mid-late Holocene (991 ng/g). On the other hand, the contents of terrestrial biomarkers (C27+C29+C31n-alkanes) during the early Holocene (1 661 ng/g) were about three times higher than those during the mid-late Holocene (499 ng/g). Our biomarker results suggest that the modern circulation system of the Yellow Sea was established by 5-6 ka, and resulted in higher marine productivity and lower terrestrial organic matter inputs. Biomarker ratios were used to estimate shifts in phytoplankton community structure in response to mid-Holocene (5-6 ka) environmental changes in the Yellow Sea, revealing a transition from a dinoflagellate-diatom dominant community structure during the early Holocene to a coccolithophore-dominant community structure during the mid-late Holocene.