Long-term changes of phytoplankton community in Xiagu waters of Xiamen, China

Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.     

Speciation, distribution, and potential ecological risk assessment of heavy metals in Xiamen Bay surface sediment

Based on the survey of surface sediment in Xiamen Bay in October 2011, the speciation, distribution, and potential ecological risk assessment of heavy metals （Cu, Pb, Zn, Cd, and Cr） in this area were studied us-ing the sequential extraction method and ecological risk assessment method. The results indicated：（1） the total concentrations of these heavy metals were influenced by runoff, industrial wastewater, and sewage, and were all higher in the coastal area than the offshore area while the highest area of Pb was a little far-ther away from the coastal water due to atmosphere deposition;（2） sequential extractions suggested that Cu was mainly composed with residual and Fe/Mn-oxide bound fractions, Pb was bound to Fe/Mn-oxide, Zn and Cr were dominated by residual, and Cd bound to exchangeable and carbonate fractions; （3） the order of migration and transformation sequence was Cd＆gt;Pb＆gt;Cu＆gt;Zn＆gt;Cr and the degree of pollution was Cd＆gt;Pb＆gt;Cu＆gt;Zn＆gt;Cr;and （4） the ratios of the secondary and primary phases showed that Zn and Cr were both clean, Cu may be polluted, Pb was moderately polluted, while Cd was heavily polluted.     

厦门地震台数字化仪器零点台阶产生原因探讨

自使用数字化仪器观测以来,厦门地震台多套仪器的记录曲线均出现台阶现象,大部分出现在当日数据之间。也有一种台阶非常特殊,它出现在当日00h00m数据和昨日23h59m数据之间,称为“零点台阶”。本文对台阶产生的原因简单分析,重点对零点台阶出现的时间进行统计,试图寻找这种台阶的产生规律,讨论出现的可能原因。     

厦门海域废弃物倾倒区表层沉积物重金属富集特征及其生态危害评价

根据浯屿临时倾倒区和厦门港临时倾倒区表层沉积物中重金属的监测结果,采用富集系数法和Hakanson潜在生态危害系数法对其富集程度和潜在生态危害程度进行分析和评价,结果表明:2个倾倒区表层沉积物中各重金属含量值都在一类沉积物标准范围内,沉积物类别属于一类沉积物;重金属富集程度不大,对海洋生态系统的潜在生态危害非常轻微,属于轻微潜在生态危害的范畴.从重金属元素的评价结果看,2个临时倾倒区仍然可以继续使用.     

厦门两类地震现场动态图像传输系统的对比分析

地震现场图像传输对于全面了解震灾现场情况有着重要作用。通过对厦门市地震局两套地震现场动态图像传输系统进行比较,提出改进设想。     

厦门市住房市场的空间分割及其成因解析

以住房子市场理论为框架建立研究假设,用主成份分析和聚类分析法刻画厦门市的住房市场特征。对住房类型子市场与聚类划分子市场进行对比分析,并采用Hedonic多重回归法对不同子市场划分方式的合理性进行验证。在此基础上,采用特征价格函数和子市场样本密度分布展开空间分析。结果显示:厦门市区划分为四个住房子市场,由城市中心地区向外呈现非均衡的层级化空间分布特征。城市中心与外围局部地区子市场的极化分布形成了"空间分割",降低了住房消费的空间替代性。多元产权结构下的市场环境、非均衡的住房用地拓展以及缺乏弹性的住房开发控制共同导致了空间分割。充分认识住房市场的结构与特征,将有助于提高城市住房公共政策的效率。     

厦门海底隧道顶板厚度选择及其开挖稳定性分析

在厦门海底隧道轴线的地质剖面图上,选取了4个典型的剖面,应用多裂隙岩体三维弹塑性本构关系和损伤演化方程进行数值分析研究,得到了应力分布、洞周位移、塑性区、损伤区等结果。通过对应力扰动区的分析,以及隧道轴线位置、轴线升高或降低后各剖面应力扰动范围与弱风化层厚度的对比,很容易确定厦门海底隧道的最小顶板厚度;根据应力分布、洞周位移、塑性区、损伤区结果,评价了海底隧道的开挖稳定性。二者的有机结合,说明了将设计方案的轴线位置提高4 m后隧道是稳定的。     

中华假磷虾碳氮收支的实验研究

实验室培养条件下,以新近孵化的卤虫(Artemiasalina)为食物,观测中华假磷虾(Pseudeuphau siasinica)雌性成体、仔虾和后期带叉幼体的碳氮收支.实验表明摄食率随食物浓度的升高呈线性提高,成体未出现饱和现象,反映其较高的摄食潜力.呼吸率(碳消耗率)与碳的摄食率及同化率分别呈线性正相关,比动力作用分别为9%~16%(摄入碳)和10%~17%(同化碳)以后期幼体更小.总氮排泄率与氮的摄食率及同化率也分别呈显著正相关,但仔虾例外.排粪率随摄食率升高而提高,从而同化效率与摄食率无关,介于0.84~0.95.食物氮源是中华假磷虾生长的主要限制因子,当摄食率低于10μg/(mg·d)(干重)时,假磷虾呈负生长.同化的氮以排泄消耗为主,体质生长次之,而蜕皮损失最少.同化的碳也以呼吸消耗和体质生长居多,但随摄食率有变化,蜕皮损失最少.在成熟雌体,估算的生殖生长(碳、氮)比蜕皮损失略高.净生长效率随摄食率(及同化率)升高而升高.达一定值后,仔虾和后期带叉幼体净生长效率略有下降.     

厦门海域水体中胶体多糖的醛糖组成

利用切向超滤技术从厦门海域水体中提取制备出不同来源(海洋、河口与河流)的胶体及不同粒径的海洋胶体,分析并比较其多糖的醛糖组成。结果表明,各种胶体含有相同的醛糖组分,即鼠李糖、岩藻糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖,粒径相同的高分子量胶体以葡萄糖和半乳糖为优势组分,海洋胶体与河流胶体的醛糖组成相似,低分子量海洋胶体的鼠李糖丰度是高分子量海洋胶体的2倍多。这些结果进一步说明了浮游植物和陆源输入是胶体有机物的重要来源,微生物作用和原生动物的摄食可能使天然水体中胶体物质的醛糖组成趋于一致。     

厦门海沧经济开发区环境地质条件及其变化趋势预测──Ⅰ.地质环境特征与环境地质条件

在野外调查和考察工作的基础上,通过对所获实验数据的综合分析并参考有关资料,研究了厦门海沧经济开发区的地质环境特征与环境地质条件。结果表明,该区原生地质环境良好,确系海内外投资者不可多得的施展鸿图的理想之地。