The environmental implication of diatom fossils in the surface sediment of the Changjiang River estuary(CRE) and its adjacent area

In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang(Yangtze) River estuary and its adjacent waters, the diatom fossils from 34 surface sediment samples and their relationship with environmental variables were analyzed by principal component analysis and redundancy correspondence analysis. The diversity and abundance of diatom fossils were analyzed. Some annual average parameters of the overlying water(salinity, temperature, turbidity, dissolved oxygen, depth, dissolved inorganic nitrogen,dissolved inorganic phosphate and dissolved inorganic silicate) were measured at each sampling site. A total of 113 diatom taxa and one silicoflagellate species were identified in the investigation area. Diatom fossils were better preserved in fine sediments. The absolute abundance of diatom fossils did not significantly dif fer between inshore and of fshore areas, the species diversity decreased from inshore to of fshore. This may be because high nutrients and low salinity promoted the growth of more brackish species in coastal waters. The diatom taxa were divided into three groups, on the basis of their response and indication to environmental changes. For example, Actinocyclus ehrenbergii and Cyclotella stylorum were dominant in coastal waters(Group 1 and Group 3) with high nutrients and low salinity; the relative abundances of Paralia sulcata and Podosira stelliger were significantly higher in of fshore sites(Group 2, average 39.5%),which were characterized by high salinity and deep water. Four environmental variables(salinity, dissolved inorganic nitrogen, temperature and water depth) explained the composition and distribution of diatom taxa independently( P 0.05), this finding can be applied in further paleoenvironmental reconstruction research in this area.     

Application and comparison of two symptom-based eutrophication-assessment methods in Jiaozhou Bay,China

Increasing numbers of approaches to assess eutrophication,such as estuarine trophic status,the Oslo-Paris Commission Common Procedure,and the Water Framework Directive,focus on the symptoms of eutrophication.In China,however,nutrient index methods dominate the assessment of coastal waters.In this study,an integrated method that includes both water quality and ecological response was compared with the Northwest Pacific Action Plan(NOWPAP)Common Procedure.Observation data from Jiaozhou Bay,Shandong,China,were used in a comparison of the two methods in a trophic status study.Overall,both clearly revealed a high level of nutrient enrichment in the bay,indicated by high nutrient concentrations.Though the two methods differed in their methodological design in the assessment of the ecological effects of nutrient enrichment,they have acquired similar results:the integrated method suggested that the status was good,and the NOWPAP Common Procedure suggested that the status was low(indicating that the bay had no serious eutrophication problem).The introduction of filter feeders(shellfish aquaculture)into the bay on a reasonable scale may have been effective in mitigating eutrophic conditions,and perhaps explains the low ecological impacts there.Our results will be useful to ecosystem-based eutrophication management in the bay and in similar areas.     

改性粘土絮凝法对太平洋牡蛎(Crassostrea gigas)稚贝的影响

本实验以太平洋牡蛎稚贝(Crassostrea gigas,～0.2cm)为对象,研究了HDTMA有机改性粘土和PAC无机改性粘土絮凝法治理赤潮时对海洋底栖生物的影响。96h急性毒性实验中二者对牡蛎稚贝的半致死浓度(LC50)分别为4.62g/L和2.67g/L。在能够有效去除赤潮微藻的浓度条件下(0.10g/L),经慢性毒性实验发现改性粘土对牡蛎稚贝成活率无影响,牡蛎生长速度较对照组没有明显差异,滤食率比培养实验初始时升高了3～4倍,同时在牡蛎超微组织结构中未发现机械损伤。通过模拟改性粘土去除赤潮生物(Heterosigma akashiwo和Prorocentrum donghaiense)过程中对生物体的影响,发现改性粘土絮凝法通过去除赤潮藻能显著提高牡蛎的存活率,所以HDTMA有机改性粘土和PAC无机改性粘土絮凝法在赤潮生物防控中可以作为一项有效的应急措施。     

长牡蛎新型模式识别受体CgLRRC69的克隆和功能鉴定

在双壳类软体动物中, 血淋巴细胞介导的吞噬作用是清除入侵微生物的主要方式。本文在长牡蛎中鉴定了一个包含富含亮氨酸重复序列(Leucine-rich repeat, LRR)结构域的新型基因, 命名为CgLRRC69。对该基因的组织分布分析表明, CgLRRC69 mRNA在血淋巴细胞、鳃、肌肉、外套膜、心脏、消化腺和性腺中广泛表达。副溶血弧菌感染可以显著地刺激CgLRRC69在血淋巴细胞中表达, 并且在感染后6h达到峰值。同时, 酶联免疫吸附实验发现CgLRRC69可以特异性结合脂多糖(lipopolysaccharide, LPS), 表明它可能在免疫防御中有功能。吞噬实验结果显示, CgLRRC69重组蛋白可以显著地提高血淋巴细胞的吞噬能力; RNAi干扰CgLRRC69在牡蛎体内的表达, 显著降低了血淋巴细胞对细菌的清除能力。因此, 这些结果揭示了CgLRRC69作为一种新型模式识别受体, 可以特异性识别革兰氏阴性菌的主要成分LPS, 通过调理作用有效地清除细菌。     

台湾海峡地震定点形变的异常分析

结合定点形变前兆异常的常用判定标准,用多种数学方法处理了厦门台与漳州台1991～1995年水平摆地倾斜资料,发现在9,16海峡地震之前,两个台站的资料都表现出不同程度的年变规律畸变、γ因子异常、一阶差分法异常、滤波法异常等多种地形变前兆指标异常。     

蒙城地震台地磁核旋观测数据b值初步分析

利用蒙城地震台地磁核旋观测资料,进行b值统计分析,得出了其短期、长期以及周期性变化基本规律。与华东地区中强震做震例对应分析,结果表明,该台b值异常可能具有孕震效应,对中强震具有一定的预测意义。     

蒙城地震台观测环境保护案例分析及思考

简要介绍了蒙城地震台自1992年以来发生的观测环境保护案例,分析了台站观测环境保护工作的重点和难点,深入探讨了新时期地震台站观测环境保护的特点及其引发的思考。     

中国人口分布的密度分级与重心曲线特征分析

依据2000年全国第五次人口普查数据,利用ArcGIS的空间分析功能,将人口密度图分层显示,并形成中国人口分布图系.在此基础上,建立人口重心曲线,根据人口重心曲线上点的邻近性实施人口密度再分级,由此获得了更具空间集聚特征的人口密度图.基于人口密度分级的多圈层迭加分析表明:随着人口密度增大,人口分布重心逐渐由西北向东南移动,由稀疏趋于稠密,中国人口分布多圈层集聚特征明显.人口重心曲线表明,人口分布总体上是从高密度向低密度分布过渡的,其中在低密度中也有高密度地区分布,高密度地区也有相对稀疏的地区.基于人口重心曲线的中国人口密度再分级表明,中国人口密度可以适度划分为9级,据此可以将中国人口地理分布划分为集聚核心区、高度集聚区、中度集聚区、低度集聚区、一般过渡区、相对稀疏区、绝对稀疏区、极端稀疏区、基本无人区等9大类型区.统计表明,中国3/4以上的人口集中分布在不到1/5的国土面积上,半数以上的国土面积上居住着不到2%的人口,研究结果较好地揭示了中国人口分布的空间规律性.     

一种基于卫星编队InSAR的基线检测方法

研究的是基于卫星编队InSAR的基线检测技术,利用高精度的地面实验场数据,对高动态、分布式卫星条件下合成孔径雷达系统的InSAR基线参数进行检测。通过分析,提出一种改进的基于基线线性拟合的基线检测方法,并采用ERS真实数据进行基线检测实验,通过比较检查点高程和进行精度分析表明,采用该基线检测方法基线精度有很大提高,具有很高的实际应用价值。     

江苏宜兴市地质资源环境承载能力评价

当前资源环境承载能力的研究多针对区域尺度,县域尺度地质资源环境承载能力评价较少。以江苏宜兴市为例,基于承载本底和承载状态建立了评价指标体系,并从地质资源、水土环境和地质安全3个方面,开展了地质资源环境承载能力评价,为县市地质资源环境承载能力评价技术要求制定提供了支撑和参考。评价结果显示,宜兴南部丘陵山区地质资源承载能力大于北部平原区,地质安全承载能力则小于北部平原区,水土地质环境承载能力总体为中等水平,提出宜兴市应加强南部山区资源环境保护与地质灾害防范,中部地区水土污染重点防控,为宜兴市地质资源合理利用与地质环境安全保障提供科学依据。