锆石He扩散模型与中国典型克拉通盆地古老层系热史重建

沉积盆地古老层系已成为我国油气勘探的重要领域,但由于缺乏有效古温标,其热史研究一直很薄弱.本文在系统综述锆石He扩散动力学模型及差异性基础上,探讨了锆石(U-Th)/He热定年技术在我国克拉通盆地古老层系热史恢复中的适用性.目前常用的锆石He扩散动力学模型包括简单模型、锆石辐射损伤积累和退火模型及扇形线性模型.基于不同...     

秦至宋时粤北经济与文化概观--对《粤北区域经济地理的历史变迁》的不同意见

自秦朝至宋朝（221BC～1279AD）,古广东经济与文化发展深受中原与海外的影响,利用本地的地理位置、优美的自然环境和丰富的自然资源,发展农业、手工业、商业、交通业和文化事业,在中国占有重要的地位。粤中广州地区的经济与文化发展在广东乃至岭南长期处于领先地位,促进广东乃至岭南其他各地区的发展,而粤北自宋至隋经济文化处于广东领先地位说和唐宋时期除粤北外岭南大部分地区还比较荒凉落后之说都不能令人信服。     

梵净山西麓古茶树立地岩-土系统地球化学特征分析

以梵净山西麓印江县紫薇镇古茶树立地剖面上的岩石和土壤为研究对象,使用ICP-MS和ICP-AES测定21种元素的含量,分析古茶树立地岩石-土壤系统的地球化学特征,以期为印江县古茶树保护及开发提供科学依据。结果表明：古茶树生长地岩石-土壤系统的主量、微量和重金属元素富集程度低（EF <3）,受人为因素影响程度小,可为古茶树提供安全的生长环境。其中主量元素K和Al在岩石-土壤系统中含量丰富,Ca、Mg、Na元素含量较少,符合茶树喜钾嫌钙的生理特征;微量元素在岩石-土壤系统中含量变化均匀,但与地球化学丰度值和中国土壤背景值相比,其含量较少;重金属元素含量均低于无公害农产品种植业产地环境条件限定值。同时研究发现该岩土系统中Se元素含量丰富,可为当地发展富硒茶提供参考。     

River channel evolution and tsunami impacts recorded in local sedimentary archives – the ‘Fiume Morto’ at Ostia Antica (Tiber River,Italy)

Ostia, the ancient port of Rome at the mouth of the river Tiber (Italy), flourished until the 2nd Century ad , although massive siltation had already caused the abandonment of its lagoonal harbour in the 1st Century bc . In search of an alternative harbour site, geomorphological and geoarchaeological research was carried out in the ‘Fiume Morto’, an abandoned Tiber meander to the immediate north of the town. To reconstruct its complex development and evaluate the suitability of the river channel as a fluvial harbour, a transect perpendicular to the former river channel's flow axis was systematically explored by a new methodological approach combining electrical resistivity tomography, direct push-electrical conductivity sensing and vibracores. Together with microfossil, mineralogical and geochemical analyses of sediment samples and 50 radiocarbon dates, in-depth stratigraphic data support a detailed reconstruction of different Tiber channel generations. Results reveal a meander development closely related to distinct ‘cut and fill’ dynamics. Inactive river channels were repeatedly filled with lagoonal sediments, abruptly followed by phases of intense incision. Yet, the overall Fiume Morto channel structure remained stable and almost in situ over centuries, showing nearly no lateral changes since the southward shift of the Tiber River mouth in the first millennium bc . In the 1st Century bc , channel conditions favoured navigation and transportation of goods with large ships. Open-water conditions, suitable for anchoring and landing activities, dominate from the 1st Century ad until 1557 ad , when the Fiume Morto meander was finally cut off and silted up within a short time. Within the fluvial deposits, sediments most likely related to tsunami inundations are preserved. These events occurred sometime before the 2nd Century bc , in the early 1st Century ad and in the 17th Century ad or later. Results are consistent with traces of tsunami influence found in Ostia's western lagoonal harbour.     

东山湾鱼类食物网研究

本文分析了东山湾８５种经济鱼类的食物关系，结果表明，东山湾鱼类的食性类型可分为：浮游生物食性；底栖生物食性；游泳动物食性；浮游生物和底栖生物食性；底栖生物和游泳动物食性及浮游生物，底栖生物和游泳动物食性等６种，这些鱼类可分为４个营养级：（１）杂食性鱼类；（２）低级肉食性鱼类；（３）中级肉食性鱼类；（４）高级肉食性鱼类，其中低级肉食性鱼类占优势。东山湾 鱼类食物网的能量流动可简要归纳为６种途径，小公     

长江口邻近洋山港工程海域无机氮和磷的时空变化特征

根据2004～ 2008年间2月和8月的营养盐监测资料,分析了长江口邻近洋山港工程海域无机氮和磷浓度的时空变化特征,结果表明:亚硝酸盐和氨氮浓度呈波动特征,硝酸盐和无机氮浓度很高,均超过四类海水水质标准;硝酸盐占无机氮总量的90.2％以上,活性磷酸盐浓度较高且基本稳定,其浓度均值处于四类海水水质标准范围.水体氮磷比值为...     

探地雷达技术在古城墙修缮中的应用

平遥古城墙是我国珍贵的文化遗产。由于古城墙经历年代久远以及近代人为破坏,其内部结构发生了很大改变,目前已有部分马面和墙体出现裂缝,甚至发生了严重的跨塌事故。本文以探地雷达技术的应用为基础,简述了探地雷达在古城墙修缮中的基本原理及应用。通过讨论探地雷达技术对目标体的检测,分析古城墙雷达剖面,得出了城墙内部存在松软土体、孔洞、裂缝等结构缺陷,并给出危险等级,为制定修缮计划提供了可靠的依据。     

镇远古城意象空间与旅游规划探讨

从2002年联合国世界乡土文化组织确定的全球"回归自然,返璞归真"旅游圣地中提取贵州的黔东南--镇远进行分析,从意象空间理论与方法的角度,分析镇远古城的旅游周边环境,赏识用意象空间的概念,获取基本数据进行旅游规划基础与应用研究方向的开拓,用照片辨认与公众意象草图分析的结果,完善旅游规划,重视旅游无形因素的规划,做到以人为本,公众的参与,找出合理规划旅游地的依据     

Some Observations on the Changes of Physico-Chemical and Biological Factors in Victoria Harbour and Vicinity, Hong Kong, 1988–1996

This study analysed monthly physico-chemical and biological data collected from 18 marine monitoring stations in Victoria Harbour and its vicinity in Hong Kong, from 1988 to 1996. Cluster analysis based on all water quality parameters measured shows that the 18 monitoring stations can be grouped into four clusters: Cluster I consists of stations located in the Harbour proper; Cluster II consists of stations located west of the Harbour and along the Rambler Channel; Cluster III consists of stations located east of the Harbour near Junk Bay and Cluster IV consists of stations located west of the Harbour and near the Ma Wan, Kap Shui Mun and Western Fairways. Factor analysis shows high positive loadings for nutrients in the first two factors of the four clusters. This suggests that effluents from the 11 outfalls of sewage screening plants influence the water quality of Victoria Harbour and its vicinity. Other factors such as storm water runoff, marine traffic, construction and industrial activities and the Pearl River discharges also appear to play an important role in determining local water quality. Five stations located along an east–west transect across the Harbour were selected for trend analysis. The three stations located in the Harbour exhibit an increasing trend for temperature and levels of total phosphorus (TP), ortho-phosphate phosphorous (PO₄-P) and faecal bacteria and a decreasing trend for pH and levels of total nitrogen (TN), total kjeldahl-nitrogen (TKN), 5-day biochemical oxygen demand (BOD₅) and chlorophyll a. For the station located east of the Harbour, an increasing trend is observed for levels of TP, PO₄-P, but no decreasing trend in TN and TKN is detected. For the station located west of the Harbour, no decreasing trend in TN, TKN and chlorophyll a is observed. Changes in levels of phosphorus and nitrogen in Victoria Harbour and the immediate vicinity have led to significant increases in the ratios of Total Silica (TSi) to TN, as well as a decrease in TN to TP and TSi to TP in most stations. Results of the present study show that Victoria Harbour and its immediate vicinity remain polluted.     

Red-Pelaged Harbour Seals, in Humboldt County, California: why some Seals Rust

In this paper we present data on the occurrence of red-pelaged harbour seals, Phoca vitulina, at a haul-out in Humboldt County, California. Density of red seals ranged from 4% to 17.5% (n=21) and was comparable to that reported for San Francisco Bay, being the highest documented worldwide. The red colouration is the result of natural inorganic iron oxide/hydroxide pigments (limonite), which are present in small patches on the beach sand of the seals haul-out at the mouth of the Mad River. Thorough analysis of the river water and ocean water excluded these as possible sources for the iron oxide/hydroxide pigments. We found that the manmade reinforcement of the river bank adjacent to the haul-out consisted of greenshist boulders with a very high iron content. Weathering of these rocks produces red iron oxide/hydroxide particles which are then redeposited by rain or river action in small patches across the haul-out. Seals receive their red colouration through direct physical contact with these patches. SEM examination showed that these particles can adhere lastingly to the seals’ hair. Other studies provide reason for concern that this situation may detrimentally impact the seals’ health.