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561.
Sulphide-bearing Ca-carbonate, Na-carbonate, Na-hydroxide, Na-chloride and Ca-sulphate waters from Northern Apennines were investigated in order to determine their main chemical and isotopic composition and draw inferences on water-rock interaction. 2H and 18O values suggest an origin mostly meteoric for the analysed waters but a well drilled in Miocenic sediments. The Na-carbonate and the Ca-sulphate waters are the most interesting geochemically. Na-carbonate type, which sometimes reaches extreme composition (Na/Ca up to 228, equivalent ratio), may have been derived through prolonged interaction of Ca-carbonate waters with rocks containing feldspar, montmorillonite and illite under calcite saturation/oversaturation; the high F and pH and the very low PCO
2 agree with prograde dissolution of silicates and lasting water-rock interaction. However, Ca–Na ion exchange, involving clays of marine origin, cannot be excluded in addition. The Ca-sulphate waters, occurring in Messinian gypsum-bearing sediments, are saturated in gypsum and calcite and exhibit very high total H2S (up to 219 mg dm-3) and PCO
2 (up to 0.32 bar). Mass balance of sulphate sulphur, sulphide sulphur and delta34S suggests sulphate – derived from gypsum – as source for H2S; CH4 and organic matter generate the reducing conditions and sulphate reduction is mediated by bacteria. One Na-chloride water from a well in Miocenic sediments has unusual composition, containing about 700 mgdm-3 of potential CaCl2 and having 2H and 18O (-47.5 and -4.9 respectively) which plot far from the meteoric water lines; probably it is derived by mixing of meteoric and formation waters. The Na-hydroxide water, with very high pH (11.2), is generated through protracted interaction of meteoric waters with ultramafites. 相似文献
562.
Silicon limitation on primary production and its destiny in Jiaozhou Bay, China V: Silicon deficit process 总被引:1,自引:0,他引:1
Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased seawater silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considered that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern. 相似文献
563.
564.
Tadeusz Andrzej Przylibski Krystian Mroczkowski Adam Zebrowski Paweł Filbier 《Environmental Geology》2001,40(4-5):429-439
Radon is a significant component of the groundwaters that discharge in the springs of Szczawno Zdrój and are recognized as
medicinal. However, among the five exploited springs adjoining each other, it is only in Marta Spring that radon occurs in
large concentrations (up to 325.6 Bq/dm3). Therefore, the authors have made an attempt to describe and clarify this fact. They found out from their own research and
archival data that 222Rn dissolves in the waters of Marta Spring after acidulous waters of deep circulation have mixed with poorly mineralized shallow
waters in their outflow zone. The genesis of the gas is determined by the content of its parent nuclide, 226Ra, in the sandstones in the vicinity of the intake. The volume of the rocks providing radon to the waters of this intake
has been estimated at several hundred cubic metres. No seasonal fluctuations in radon concentration have been observed and
222Rn concentration changes do not seem to be influenced by changes in the concentration of other chemical components of the
waters or by the discharge of the intake. The process of dissolving 222Rn in the medicinal groundwaters of Marta Spring is the last, the shortest, and the most local of the processes that form
the chemical composition and the physical properties of these waters.
Received: 7 January 2000 · Accepted: 12 August 2000 相似文献
565.
566.
Massimo Civita Adriano Fiorucci Roberta Miè 《Geostandards and Geoanalytical Research》2001,25(2-3):431-439
Aluminium was determined in surface and ground waters in the Alba region of NW Italy to provide information on natural and anthropogenic sources of contamination. Determinations were made by a spectrophotometric method based on the aluminium-pyrocatechol complex. The total aluminium content of waters was determined as well as the toxic form of monomeric aluminium, obtained from samples that had been passed through 0.20 μm cellulose filters to remove colloidal and particulate material. Results were correlated with mortality data associated with Alzheimer's disease. There appeared to be a correlation between mortality data and areas having the highest aluminium content of water. 相似文献
567.
鉴于海域覆盖面积大而污水排放形成混合区相对集中的特点,基于四叉树网格布设的思想,分层次对不同研究区域按不同尺度网格对近海水域进行嵌套网格联合布置,重点模拟污水排放形成的混合区范围,在此基础上建立了Godunov型通量差分裂(FDS)格式有限体积法计算模式,实现了在不同尺寸的网格联立求解,提高了数值计算效率,又保证了计算精度.以海州湾近海水域为例,对海州湾近海水域流场及污染物混合区的范围进行了模拟计算,由此建立了排污量与混合区面积之间的响应关系,为环境管理部门对入海排污量的总量控制提供了依据. 相似文献
568.
二类水体水色遥感的主要进展与发展前景 总被引:18,自引:3,他引:18
Ⅱ类水体水色遥感是海洋水色遥感的难点和热点。针对Ⅱ类水体的光谱特性和海洋现象的特点,综述了水色卫星传感器在光谱波段配置、辐射探测性能和时空分辨率等方面的设计要求与技术进步。从水色遥感资料反演的两大关键技术——大气校正和生物光学算法两个方面,概述了Ⅱ类水体水色反演算法的研究现状和发展方向。根据我国近海的水体特点,提出了我国水色遥感研究需要解决的关键问题。 相似文献
569.
O. Hertel C. Ambelas Skjøth L.M. Frohn E. Vignati J. Frydendall G. de Leeuw Uwe Schwarz Stefan Reis 《Physics and Chemistry of the Earth》2002,27(35):1507-1515
The atmospheric chemistry and deposition model has been applied for calculation of nitrogen and sulphur depositions to the entire North Sea area for the year 1999. The total atmospheric nitrogen and sulphur depositions to the North Sea area were determined to 709 kton (kt) N and 551 kt S, respectively. Since the North Sea area was calculated to be 747,988 km2, this is equivalent to an average deposition of 0.9 ton N km?2 and 0.7 ton S km?2, respectively. The depositions decrease strongly from the south end (about 2–3 kt N km?2) to the north end (about 0.2 kt N km?2) of the North Sea, due to increasing distance to the large source areas in the northern part of the European continent. The territorial waters of Belgium, the Netherlands and Germany receive about 50% higher deposition densities than the average value for the entire North Sea area. For the remaining territorial waters of the North Sea the depositions follow more or less the fraction of the area. The results furthermore show that about 60% of the total nitrogen deposition is related to emissions from combustion sources (nitrogen oxides) and about 40% from emissions related to agricultural activities (ammonia). 相似文献
570.
稀有气体同位素地球化学研究进展 总被引:8,自引:1,他引:8
火山玻璃及地幔包体中的稀有气体是地内信息的有效示踪剂,对其研究对追溯岩浆起源、探讨地幔特征与结构等具有重要意义。在此对稀有气体同位素地球化学研究现状、稀有气体在不同构造环境中的表现及其在岩浆起源、成因、地幔结构等方面的探讨,以及对稀有气体在油气、金属矿体、地表水位、测年、地震等灾害中的研究与应用情况进行简述。 相似文献