铑作基体改进剂石墨炉原子吸收法测定海洋生物样品中的痕量砷   总被引：10，自引：1，他引：9  

饶竹  李梅 《岩矿测试》1998,17(1):33-36

采用铑作基体改进剂,消除样品中共存磷酸盐基体的干扰,实现了用塞曼石墨炉原子吸收法测定贻贝、虾粉、牡蛎等海洋生物样品中痕量砷。方法的ＬＤ为２５ｐｇ（１０μＬ进样）,线性范围在０～１２５μｇ／ＬＡｓ。标准加入法测定砷的回收率为８５％～１０２％,１０－６水平Ａｓ的测定ＲＳＤ（ｎ＝６）小于７％,分析结果与标准样品的标准值和氢化物原子吸收法测定结果相符。  相似文献   

A possible feedback mechanism involving the Arctic freshwater, the Arctic sea ice, and the North Atlantic Drift   总被引：1，自引：0，他引：1  

Odd Helge OTTER  Helge DRANGE 《大气科学进展》2004,21(5):784-801

Model studies point to enhanced warming and to increased freshwater fluxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined effect of increased freshwater input to the Arctic Ocean and Arctic warming--the latter manifested as a gradual melting of the Arctic sea ice--is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runoff, and a third more extreme case, where the river runoff is five times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5-2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift.Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensified Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.  相似文献   

三江平原泥炭沼泽沉积物中营养物质的分布规律   总被引：7，自引：4，他引：7  

于君宝  刘景双  王金达 《湿地科学》2004,2(1):31-35

采用冬季采样，现场分层的方法，系统地研究了三江平原沼泽中河床一河漫滩型泥炭地和谷底洼地型泥炭沉积中总氮、总磷和有机质等营养物质的分布特征。结果表明，在不同沉积层中，总磷明显在草根层富集，总氮和有机质在泥炭上层含量最高，其他营养物质含量随着深度的增加而逐渐降低。河床一河漫滩型和谷底洼地型泥炭沉积物中总氮和总磷含量随着泥炭粒级的减小而明显增加。河流型泥炭沉积物不同机械组分中总氮的变化幅度远远大于谷底洼地型，两种类型泥炭地不同机械组分中总磷含量的变化差异幅度不大。有机质含量随着泥炭粒级的减小而明显减少。河床一河漫滩型泥炭地和谷底洼地型泥炭地中总氮含量与有机质含量呈显著的正相关，相关系数分别为0.953和0.944，泥炭中的氮主要以有机氮形态存在，而总磷含量与有机质含量的关系不显著。  相似文献   

The sedimentary coastal basin of Togo: example of a multilayered aquifer still influenced by a palaeo-seawater intrusion   总被引：3，自引：0，他引：3  

Ari Akouvi  Martial Dray  Sophie Violette  Ghislain de Marsily  Gian Maria Zuppi 《Hydrogeology Journal》2008,16(3):419-436

In Togo, the hydrogeology of the sedimentary coastal aquifers along the Gulf of Guinea has been studied for the last three decades to define the recharge processes and the origin and evolution of the salinity. Isotope hydrology and fluid geochemistry suggest that the current recharge of all aquifers, both confined and unconfined, occurs through the crystalline basement and the Plio-Quaternary deposits. Two main groundwater mineralization processes are observed: the first one, in recharge areas, is due to farming, village and city life and concerns unconfined aquifers (crystalline basement, Continental Terminal and Quaternary sediments); the second one is a mixing process between recent freshwater and fossil saline water still present in the deep confined aquifers inland, several kilometers away from the coast. Brackish water was trapped in low-permeability lenses of confined aquifers (Eo-Palaeocene and Maastrichtian) during the Quaternary, in periods of low recharge, notably during the last glacial maximum (LGM), and has not yet been flushed out. Hydrodynamic simulations indicate that, at that time, the aquifers experienced a maximum seawater intrusion as far as 20–22 km inland, depending on the palaeo-recharge value at the outcrops.  相似文献   

Accumulation and depuration of pectenotoxins in brown crab Cancer pagurus     

LI Zhaoxin 《中国海洋湖沼学报》2009,27(2)

Pectenotoxins (PTXs) are a group of marine algal toxins. In this study, the accumulation and depuration of pectenotoxins in brown crab Cancer pagurus were investigated. Crabs were fed with toxic blue mussels Mytilus edulis for 21 days and then depurated for 42 days. Toxins were extracted with methanol from the digestive glands of contaminated crabs, uncontaminated crabs (control group) and from blue mussels for comparison. Extracts were analyzed by liquid chromatograph coupled with tandem mass spectrometry (LC-MS-MS). The concentrations of PTX-2, PTX-2 SA, 7-epi-PTX-2 SA, and PTX-12 were analyzed in two batches of toxic blue mussels and the crabs. A one-compartment model was applied to describe the depuration of PTXs. The half-life of PTXs was estimated to be 6-7.5 days. After depuration for 42 days, the amount of PTXs measured in the crab digestive glands was less than 1 μg/kg.  相似文献   

Length-weight relationships for six freshwater fish species in Iran   总被引：2，自引：0，他引：2  

M. S. HEYDARNEJAD 《中国海洋湖沼学报》2009,27(1):61-62

The aim of this study is to report the length-weight relationship parameters (a and b) for some economically important fish species from Iranian freshwaters. The length-weight relationships (LWR) are calculated for six freshwater fish species collected during 2006 and 2007 in Iran. The values of the exponent b in the LWR (W=aLb) vary between 2.985 and 3.543. The LWR with high correlation coefficient (r2) is significant for all the species. These parameters are of great importance to evaluate the relative condition of populations, biology, species management and their fisheries and stock assessment. The application of the length-weight relationships presented here should be limited to the observed length ranges.  相似文献   

Structure and Dynamics of Fisheries in Nigeria     

Nwafili Sylvanus A. GAO TianXiang 《中国海洋大学学报(英文版)》2007,6(3):281-291

The changes that have taken place in Nigerian fisheries are reviewed. Artisanal fishery has continued to dominate the fisheries,contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Aquaculture potentials remain untapped as much as deep-sea fisheries. The combined potential of the fisheries resources-freshwater,marine and aquaculture can meet over 90% of the nation's demand for fish. Opportunities for invest-ments,therefore,exist in the various subsectors,especially in the areas of storage,processing and preservation for the capture fishery and fish seed multiplication for aquaculture.  相似文献   

磨刀门河口水沙变化与地貌响应   总被引：2，自引：1，他引：1  

王世俊  易小兵  李春初 《海洋工程》2008,26(3)

以西江磨刀门河口为研究对象,应用马口站1960～2000年月平均流量及含沙量资料,1980、1981和2003年洪枯季实测水文及表层沉积物采样资料,分析磨刀门河口近几十年来的水沙变化,建立磨刀门河口水沙变化与纵、横断面及口门形态的响应模式.结论认为,西江磨刀门河口径流量年际变化不大;含沙量及输沙总量在1993年前后发生变异,有减少的趋势,悬浮泥沙中值粒径偏细;总体上形成了丰水少沙的水沙组合.磨刀门河口形态响应滞后于水沙变化,存在洪淤枯冲的年内变化.由于上游来沙量减少、人工护岸的作用下,河口口门断面趋于窄深.总体上,磨刀门河口深槽变浅,拦门沙在波浪作用下加高变薄;口门向外海延伸较快,使得河口口门动力相对强弱发生了较大变化,波浪动力及沿岸流对泥沙转运的作用增强,磨刀门河口正逐渐向河流-波浪型河口转变.  相似文献   

低径流量条件下海平面上升对长江口淡水资源的影响   总被引：3，自引：0，他引：3  

裘诚  朱建荣 《气候变化研究进展》2015,11(4):245-255

基于长江口水动力及盐水入侵三维数值模式ECOM-si,统筹考虑气候变化导致流域极端低径流量的前提下,研究在未来（2030、2050和2100年）海平面上升过程中,长江口淡水资源分布及总量变化过程,探讨河口三大重要水库取水活动对海平面上升的响应,对防范未来可能出现的盐水入侵危害具有重要作用,也为长江口水源地建设与水库取水调度提供理论依据和技术支持。1999年冬季、2006年秋季和2011年春季期间长江径流量均为自1980年以来的同期最低,且长江口均发生了极为严重、影响巨大的盐水入侵,考虑到径流量的季节变化特点,选取上述3个时期的径流量作为上游边界条件。结果表明,长江口淡水资源在1999年冬季径流量条件下随海平面上升而减少,至2100年大、小潮期间淡水总量相比于2012年分别减少42%和41%,水库最长不宜取水天数增加70%以上;在2006年秋季径流量条件下,淡水资源随海平面上升而减少,但在海平面上升至2050年情况下,河道水位抬升使进入北支的径流量增加,削弱盐水倒灌,水库最长不宜取水天数减少40%~50%;在2011年春季径流量条件下,淡水资源在海平面上升至2100年后大、小潮期间分别减少43%和20%,水库最长不宜取水天数增加1~3 d。  相似文献   

Influence of stock origin and environmental conditions on the survival and growth of juvenile freshwater pearl mussels (Margaritifera margaritifera) in a cross-exposure experiment     

《Limnologica》2015

The freshwater pearl mussel (Margaritifera margaritifera) is a highly specialized and sensitive freshwater bivalve, whose survival in the juvenile phase is indicative of high quality habitats. This contribution investigates the use of juvenile freshwater pearl mussels as bioindicators, considering the influence of mussel stock and study stream conditions on juvenile performance, as described by survival and growth rates. A standardized cross experiment was carried out investigating juvenile performance in four different pearl mussel stocks originating from the Rhine, Danube and Elbe drainages, representing distinct genetic conservation units. The juveniles were exposed in five study streams which were selected to integrate pearl mussel streams with different water qualities and recruitment status of the mussel population. Per study stream, five standard mesh cages containing an equal number of 20 (10 × 2) juvenile pearl mussels per stock in separate chambers were installed. Survival and growth rates of juveniles were checked after three months (i.e. before their first winter) and after nine months (i.e. after their first winter). Mussel stock and study stream conditions significantly influenced juvenile performance. Growth rates were determined by study stream conditions and increased with stream water temperature, organic carbon and C/N ratios. Survival rates varied stock-specifically, indicating different levels of local adaptation to their native streams. Due to the detection of stream-specific differences in juvenile performance, freshwater pearl mussels appear suitable as bioindicators. However, a careful consideration of stock-specificity is necessary to avoid false interpretation of bioindication results. The comparison of stock-specific survival in native versus non-native streams implicates that exposure of juveniles outside their native habitats is able to increase breeding success or else serve for risk spreading in breeding programs.  相似文献