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281.
282.
In arc-type geothermal systems along the circum-Pacific rim, low pH well discharges in the geothermal systems of Japan and the Philippines are more enriched in oxygen-18 or deuterium or both as compared to neutral pH waters found in the same systems. Isotope enrichment of both oxygen-18 and deuterium means higher percentage of magmatic vapour contribution to the well discharges due to the fact that un-neutralized magmatic water carries much abundant hydrogen ions to keep the water at a lower pH. This is consistent with the observation that acid geothermal waters usually occur near the volcanic heat source of a geothermal system, where the magmatic component tends to reach a higher percentage.  相似文献   
283.
Samples of green lipped mussels (Perna viridis) were collected from three sites (Huoshao, I’Maluan and Tong’an) around Xiamen coastal waters, where levels of various trace organic pollutants have been studied. Samples were also collected at a “cleaner” reference site near Dongshan Island for comparison. Clearance rate, absorption efficiency and oxygen consumption of the mussels were measured under controlled laboratory condition; organic pollutants in their tissues were also analyzed. Scope for growth (SFG) was employed as a general biomarker to evaluate the stress of pollutants. Specimens from Tong’an site had the lowest SFG values (1.14 J/h/g); while specimens from the I’Maluan site and Huoshao site had SFG values of 5.01 and 6.72 J/h/g, respectively. Specimens from Dongshan (reference site) had a relatively high SFG value of 10.96 J/h/g. There was a significant negative correlation between the SFG of the different populations of green lipped mussels and the concentration of DDT in their tissues.  相似文献   
284.
Organochlorine compounds (OCs) such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane related compounds, hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), tris(4-chlorophenyl) methane (TCPMe) and tris(4-chlorophenyl) methanol were determined in the blubber of Dall's porpoises (Phocoenoides dalli) collected from Japanese coastal waters in 1998/1999. Among OCs analyzed, PCBs were the predominant contaminants with concentrations ranging from 1.5 to 39 microg/g on a wet weight basis. OCs concentrations were relatively low and less variable in mature females possibly due to the lactational excretion from their bodies, while in males the concentrations were increased with body length. Concentrations and compositions of DDTs and HCHs showed significant differences between the truei-type population off the Pacific coast of northern Japan and dalli-type from the Sea of Japan/Okhotsk, suggesting its usefulness to discriminate different populations. OCs levels detected in truei-type porpoises collected in 1998/1999 were lower than those collected in 1984, except TCPMe. On the other hand, except DDTs, the residue levels of other organochlorines in dalli-type porpoises showed no significant decrease since 1984.  相似文献   
285.
Disturbed acid sulphate soils are potent sources of acidity in coastal waterways. Monitoring studies of the drainage water for sites at East Trinity, Cairns and Pimpama, south-east Queensland indicate that considerable acidity is found in the drainage water from these sites. Hydrogen (H+), ferrous (Fe2+) and aluminium (Al) ions are the dominant acid cations involved. When drainage water is mixed with fresh or marine waters the effect of H+ on acidity generation is immediate. Aluminium can release acidity on hydrolysis, while the oxidation of Fe2+ to Fe3+ both acidifies and removes dissolved oxygen from the water. Strongly acidic waters with low levels of dissolved oxygen concentration are undesirable for most forms of aquatic life. Export of acidity from acid sulphate soil is likely to have a major effect on inshore fisheries and breeding grounds especially in periods of flood following drought or periods of low rainfall, where large volumes of acidity can be flushed/leached into sensitive aquatic/marine habitats. Impacts may include low dissolved oxygen, fish kills, epizootic ulceration syndrome and damage to oysters. During the processes of oxidation and hydrolysis, iron and aluminium flocs form, that can smother benthic communities. Heavy metals are found in the drainage water at elevated levels and may also be of concern for aquatic organisms. Chronic effects such as habitat degradation, mortality of marine worms, bivalves, invasion of acid tolerant species (both plant and animal) and avoidance of habitat have been documented elsewhere. These areas require further research.  相似文献   
286.
 Mineral and thermal waters occur at Kalinciakovo, Santovka, Dudince, Slatina and Turovce, in the inner side of the Western Carpathian arc, the south-western margin of the Central Slovak Neovolcanics, and on the so-called Levice spring line. They are important sources of mineral waters for Slovakia, which are used for different purposes (bathing therapy, bottling, recreation). The mineral and thermal waters of Dudince have an extraordinary position among them. The mineral water with its physico-chemical composition and content of gasses enables its wide use for bathing therapy and it occupies a special position among the mineral waters of the Carpathian arc. Received: 9 November 1998 · Accepted: 2 March 1999  相似文献   
287.
厦门东侧海域浮游植物的种类组成与分布   总被引:5,自引:0,他引:5  
共鉴定厦门东侧海域浮游植物43属111种,其主体是广温性种类(56种),占浮游植物总种数的50%。主要优势种的季节性演替明显。四季浮游植物的平均细胞总量达36500千个/m^3,最重要的优势种是施链角毛藻(Chaetocerosc curvisetus)(占总量的53.3%)和中肋骨条藻(Skeletonema costatum)(占20.0)。浮游植物的繁盛时期在春、夏两季,但高峰期出现在春季,不同于相邻的厦门外港和厦门西港。  相似文献   
288.
During 1998 an experimental gillnet fishing survey was carried out in a Mexican Central Pacific inshore zone. One-hundred and thirty fish species belonging to 51 families and 18 orders were identified. The most abundant species wereMicrolepidotus brevipinnis (29·0% of the total abundance) and Caranx caninus (19·2%), followed by C. caballus (6·3%), Kyphosus analogus (4·3%) and C. sexfasciatus (3·4%). Thermal SST anomalies showed the existence of two periods. The first, from January to April with positive anomalies, defines the end of an El Niño episode. The second period, from May to December, constitutes the beginning of the La Niña episode. The typical seasonality in a non-anomalous year continued for a large percentage of the inshore fish community, and the effects of the anomalous event consisted of changes in seasonality of occurrence in some individual species and the unusual abundance of some uncommon species. The species richness was higher during the El Niño–La Niña event than in a non-anomalous year, and therefore the event could be considered an interannual environmental mechanism that favours fish diversity in inshore waters.  相似文献   
289.
我国沿海地区生态城市建设评价   总被引:17,自引:2,他引:15  
本文从城市生态系统的结构、功能和协调度三个方面构建了生态城市的指标体系,提出了生态城市的评价方法,并选取沿海16个城市进行城市生态化建设的综合评价与比较分析。采用适合生态城市建设的数学模型对这些城市的复合生态系统进行定量分析,其中指标涉及人口指标、生态环境指标、经济指标与社会指标4个方面,构建3个一级指标,10个二级指标,25个三级指标。得出了16个沿海城市生态化水平的比较结果,因之深圳在城市结构、城市功能方面明显高于其它城市,其生态化综合水平位居首位,其值超过标准值达到了1.19,营口市在工业废水达标率、环境噪声达标率、人均生活用水、人均国民生产总值与失业率方面得分最低是导致其生态化综合水平最低的主要原因。16市在城市环境方面得分普遍较低,表明大气质量与环境噪声是限制这些城市生态建设的主要因素。  相似文献   
290.
中国近岸部分海域海水中金属络合配位体浓度的研究   总被引:7,自引:0,他引:7  
采用阳极溶出伏安法对黄河口、青岛近海、大亚湾和南海海域海水中的金属络合配位体的浓度进行了测定,同时探讨了其分布规律与相关参量的关系.结果发现:南海海域海水中的金属络合配体的浓度稍高于其他3个海域,且都明显高于大洋水的浓度;在微表层存在富集现象;在垂直分布上表层最大,然后随深度增加而降低,在底层有较大值;各海域配位体的性质呈复杂性;铜的络合配位体浓度大于镉和铅;总的来说与世界其他海域的分布规律是一致的.同时发现铜络合配位体浓度与BOD(生化需氧量)、COD(化学需氧量)、DOC(溶解有机碳)及黏度存在显著的正相关性.  相似文献   
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