Biocorrosion by Bivalves

Abstract. A survey of the historical background of chemically boring bivalves and the proposed methods of boring, indications for biocorrosion, observations, and experimental results are provided. The regional impact to the ecosystem is discussed with examples from the N. Adriatic, Caribbean, and E. Pacific. The fossil record of the geologically oldest biocorroders extends back into the Mesozoic, i.e ., U. Triassic for Lithophaga and Jurassic for gastrochaenids.     

微波消解在环境样品分析中的应用

微波消解是近年来兴起的一种样品分析手段,具有快速、高效、试剂用量少、样品不易被沾污、节约能源等优点。对当前微波消解技术在环境样品分析领域的应用和研究现状进行了综述,介绍了微波消解技术的基本原理、特点和设备,尤其对它在环境样品分析中的应用作了较为详细的介绍,并对该技术的应用前景进行了展望。     

中国西部环境与生态科学数据中心：面向西部环境与生态科学的数据集成与共享

国家自然科学基金委员会“中国西部环境与生态科学研究计划”自2001年启动以来,有力地推动了西部区域环境演化、陆地生态过程和人类活动对环境的影响等方面的研究,积累了丰富的基础数据。国家自然科学基金委员会“中国西部环境与生态科学数据中心”承担“西部计划”项目数据产出的收集、管理、集成,并面向西部环境与生态科学的各个领域提供科学数据服务。“西部数据中心”的总体框架是以“西部计划”和地球系统科学发展的科学需求为导向,建成以数据共享、知识积累、合作交流和数据科学为主要内容的集成平台,为“西部计划”多学科的交叉研究和成果的综合集成及地球科学发展的长远目标服务。以共建共享的指导思想集成针对西部环境与生态现状与变化的基础背景数据、环境与生态观测数据、模型数据集、数据工具及数据文档;并以完全与开放的数据共享原则为用户提供推送式数据服务。目前,“西部数据中心”已完成了数据共享平台、知识积累平台与合作交流平台的开发和集成,初步形成了科学数据平台,整理并发布了大量的西部环境生态科学所需的关键数据集。     

Fluid Geochemistry as Indicator of Tectonically-Related,Deep Water Circulations in the Sardinian Rift-Campidano Graben (Italy): New Insights from Environmental Isotopes

The EC funded Geochemical Seismic Zonation program (EEC GSZ Project 1996–1998) chose Sardinia as a low-seismicity site, in which the relationships between fluid geochemistry and seismo-tectonics had to be investigated and results compared with outcomes from other selected high-seismicity sites. A first article, examining the role of fault segmentation and seismic quiescence on the geochemical composition of groundwaters and gases, has already been presented (Angelone et al. 2005). This article deals with environmental isotopes which, together with selected hydrochemical data, give hints on tectonically-related fluid circulations. Four water-dominated hydrothermal systems were considered, all located along regional fault systems and discharging groundwaters belonging to the Na–HCO₃ and Na–Cl facies. In the considered systems, groundwater circulation takes place, principally, in the Palaeozoic Crystalline Basement (PCB), with the exception of the Logudoro system, where hydrological circuits develop in the Mesozoic Carbonate Platform (MCP). The high CO₂ contents, the non-attainment of fluid-rock equilibrium and the large lithological variability prevent the construction of a unique hydrogeological–geochemical conceptual model. In this case, stable isotopes provide a useful tool to describe the origin of fluids and their subterranean movements. Stable isotopes of water, integrated with hydrochemical data, indicate that fluids are derived from three main end members. The dominant component is a relatively recent local meteoric water; the second one is marine water; and the third one is a fossil freshwater, depleted in heavy isotopes with respect to modern rains. The latter end member entered the aquifer system in the past, when climatic conditions were greatly different from today. At least two circulation systems can be recognised, namely a shallow cold system and a deep hydrothermal system, as well as two distinct hydrological processes: (1) gravity-controlled descent of cold water towards greater depths and (2) convection linked to a thermal gradient, causing deep fluids to rise up from the hydrothermal reservoir towards the surface. The highly variable δ¹³C_TDIC values suggest the presence of two distinct CO₂ sources, namely, a biogenic one and a thermogenic one. The relation between the isotopic compositions of CO₂ and He indicates an increased mantle signature in uprising CO₂-rich fluids.     

黑龙江省鸡西盆地南、北两带城子河组精细对比

鸡西盆地被平麻断裂分割成南、北两个条带,多数研究者将南带1煤之下的海相层叠伏于北带海相层或底砾岩之下,称为“城子河组下段”或“石河北组”。利用事件地层学的原理,分析盆地内城子河组早期盆地裂陷、海侵、火山喷发、聚煤等重大事件在地层精细对比方面的意义,甄别出了盆地中重大事件的地层记录．以等时层为基础建立对比框架。通过大量钻井资料追溯对比,认为盆地中坳陷部位的渴湖海湾沉积是南北两带的沉积过渡类型,根据微体古生物研究,南北两带海相层中的沟鞭藻类化石面貌基本一致,南北带的海相层应是同一层位,初步实现了盆地内南、北两个条带城子河组的精细对比,为恢复盆地古地理环境奠定了可靠的基础。     

上海城市发展的环境问题及其对策研究

上海市的发展战略;空间布局模式和环境管理是文章讨论的三个主要问题。作者认为:(1)战略设想要立足于上海的发展,“开发浦东、振兴上海、服务全国、面向世界;”(2)新的空间布局模式应为“逐步形成新的CBD,强化和完善金融和服务功能”;(3)城市发展和环境建设要协调。文章着重讨论了上海城市发展中出现的环境问题及其治理的对策和措施。     

Hydrochemical and isotopical tracers in the lacustrine aquifer of the Cerro Prieto area, Baja California, México

A series of patterns in the chemical and isotopic composition of the groundwater of the Cerro Prieto area have been recognized. These patterns were used to define four hydrochemical and isotopical zones in the area. One of these areas located at the east side was found to be the source of recharge, while another in the central part is where an older aquifer exist in lacustrine deposits. The low permeability of the area causes the aquifer to act as an aquitard, which at least is partly surrounded by an interface zone where mixing of waters occurs. Tritium and radiocarbon method revealed that the aquitard is an isolate system whose residence time is of 32 ka.     

Developments in the characterisation of waste materials for environmental impact assessment purposes

The characterisation of waste is entering a new phase with the latest developments of characterisation leaching tests and associated modelling capabilities. The currently applied too simple testing approaches lead to poor choices in waste management. With the increased insight in release controlling processes chemical speciation aspects can be addressed even in the most complex and heterogeneous waste materials. From a composition perspective materials may be highly variable, but often materials are far more consistent in their leaching behaviour. This aspect should be exploited more extensively as it holds the key to treat waste materials in such a way that long term solutions are achieved rather than reaching temporary gains.     

Phytoliths as indicators of pedogenesis and paleoenvironmental changes in the Brazilian cerrado

This paper presents the preliminary results of phytolith analyses of a peat located in the cerrado of the Uberaba municipality, State of Minas Gerais, Brazil. The phytolith soil sequence is discussed by comparison with phytolith assemblages extracted from dominant plants (Cyperaceae and Poaceae). Increasing mean age of phytolith assemblages with depth is assumed. Poaceae Cuneiform bulliform cell, Parallelepiped bulliform cell and Elongate smooth long cell types dominate up to 80 cm, rapidly drop to 42% at 80 cm and regularly decrease from 42% to 2% upwards. Cyperaceae Rondel concave type shows the inverse trend, being dominant in the upper part of the profile. This pattern can be assigned to increasing selective dissolution of the Cyperaceae phytolith type with depth, or/and to a decrease of water stress suffered by the grasses, leading to a decrease of bulliform cell silicification. Soil processes and paleo-environmental changes hypotheses are discussed.     

High-resolution sedimentary record of lead in the coastal mud of the East China Sea in the past one hundred and fifty years

In the East China Sea （ECS）, there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence （XRF） techniques and Thermal Ionization Mass Spectrometry （TIMS） were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the ＂Reform and Open Policy＂ in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River （Yangtze River） catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition.