Effects of mariculture on macrobenthic assemblages in a western mediterranean site   总被引：2，自引：0，他引：2  

Paolo Tomassetti  Emma Persia  Isabel Mercatali  Danilo Vani  Veronica Marussso  Salvatore Porrello 《Marine pollution bulletin》2009,58(4):533-541

The effects of solid organic wastes from a marine fish farm on sediment was tested using macrobenthic fauna as biological indicators. Impact on benthic fauna was evaluated in the vicinity of a fish farm in the Tyrrhenian Sea (Western Mediterranean) between July 2001 and October 2002. Changes in benthic community structure were investigated using multivariate, distributional and univariate analyses (diversity indices, AMBI and M-AMBI). The results showed sharp disturbance of assemblages under the cages and no effects in the area more than 25 m from the cages. Sediment alterations were related to an increase in farmed biomass and its wastes, as well as to low current speed that allowed accumulation of organic matter on the sea floor. It was possible to follow the ecological succession from slightly altered assemblages to heavily polluted ones in the very short period of a single fish fattening cycle (15 months).  相似文献   

四川丹巴独狼沟金矿中金与碲铋矿物的赋存状态及金的富集机制     

马天祺  张燕  陈翠华  李引  陈曦  杨玉龙  刘舒月  辜鹰  赖翔 《岩石矿物学杂志》2023,42(4):541-554

独狼沟金矿是位于丹巴成矿带中穹窿边缘的典型的石英脉型金矿,矿床中发育大量明金与碲铋矿物。本文以独狼沟金矿中碲铋矿物及自然金为主要研究对象,通过显微岩相学观察、扫描电镜、能谱以及电子探针分析,对矿床中碲铋矿物和自然金的赋存状态进行了较为详细的研究,并对金的富集机制进行了探讨。结果表明,碲铋矿物与自然金主要在成矿Ⅱ、Ⅲ阶段产出,矿石中自然金主要为含银自然金,成色整体偏高,平均为881,碲铋矿物主要有楚碲铋矿、叶碲铋矿、赫碲铋矿、硫碲铋矿B、未命名碲铋矿物(Bi₂Te、Bi₈Te₃、Bi₃Te)以及自然铋,碲铋矿物与自然金具密切的时空关系。结合前人流体包裹体的研究结果,认为成矿Ⅱ阶段到Ⅲ阶段过渡的过程中温度以及体系中碲逸度的降低是矿床中多种碲铋矿物相形成的关键,独狼沟金矿成矿的物理化学条件以及碲铋矿物与自然金的矿物特征均指示成矿过程中金-铋-碲熔体对热液中金的抽取是导致自然金富集的关键。  相似文献   

Organic carbon and nutrient fluxes to the coastal zone from the Sepik River outflow     

Kathryn A. Burns  Gregg BrunskillDiane Brinkman  Irena Zagorskis 《Continental Shelf Research》2008

The Sepik River is a major contributor of water, sediment and associated organic loads to the coastal waters of northern New Guinea and the Bismarck Sea. We compare dissolved and particulate organic carbon data from September 1997 during an extremely dry El Nino year with those from 1996, 1999 and 2000 during La Nina wet season discharges. Estimated Sepik River flux of DOC is 3.2×10¹⁰ mol yr⁻¹ and POC is 1.1×10¹¹ mol yr⁻¹. The estimates for total river nutrient fluxes to the sea are 1.1×10¹⁰ mol yr⁻¹ for nitrogen and 4.6×10⁸ mol yr⁻¹ for phosphorus. The Sepik DOC flux is about equal to that combined from all four major rivers that enter the Gulf of Papua on the south coast of PNG. The Sepik inorganic PIC flux is low (1.4×10⁸ mol yr⁻¹) as the river does not drain carbonate soils. With a narrow continental shelf, and strong coastal currents, much of this exported material is available for long distance transport into the coastal Bismarck Sea and beyond.  相似文献   

流沙地恢复过程中土壤特性演变研究   总被引：11，自引：4，他引：7  

谭明亮  段争虎  陈小红 《中国沙漠》2008,28(4):685-689

以毛乌素沙地西南缘的盐池县沙边子及位于腾格里沙漠东南缘的沙坡头地区为例,研究了该地区不同程度沙漠化土地恢复过程中土壤机械组成及土壤养分的动态变化。结果表明:不同地区或同一地区不同区域的沙漠化土地中,随着植被盖度的增加及恢复程度的增强,土壤中的粉粒、粘粒含量都有显著增加（P<0.05）,土壤质地向着壤质化和细粒化方向发展;土壤的有机质、全氮、全磷含量也有显著增加（P<0.05）;速效氮、速效磷含量也有相应的增加。土壤有机质、全氮和全磷的含量与土壤粉粒、粘粒含量呈显著正相关,且前三者之间也呈极显著正相关;但是土壤粉粒和粘粒含量与速效氮、速效磷和速效钾之间的关系则因区域和土地利用的不同表现出明显的差异。  相似文献   

小秦岭五里村金矿867号脉成因研究     

丁渊洪 《黄金地质》1999,5(1):45-50

小秦岭金矿田地处华北地台华熊台缘坳陷与秦岭褶皱系的北秦褶皱带接壤部位。８６７号矿脉赋存于太古宇太华群焕池峪组深变质岩中,形成了于晚燕山期热液活动石英脉经过后期构造活动顶底板一定位置形成扁豆体状构造泥夺,长期的氧化淋滤,石英脉中的金发生迁移,在尼砾岩中发生次生富集,形成金的富矿体。构造泥夺是重要的找矿标志。  相似文献   

Seasonal Variations in Nutrient Budgets of Hakata Bay, Japan     

Tetsuo Yanagi 《Journal of Oceanography》1999,55(3):439-448

Seasonal variations in freshwater, salt, phosphorus and nitrogen budgets of Hakata Bay, Japan were investigated from April 1993 until March 1994. The internal sink of dissolved inorganic phosphorus (DIP) and nitrogen (DIN), and the internal source of dissolved organic phosphorus (DOP) and nitrogen (DON) predominate in the bay. This means that the production of organic matter is larger than respiration, and atmospheric CO₂ is absorbed in the water column of Hakata Bay. Denitrification is more dominant than nitrogen fixation in the bay. Compared to Tokyo and Mikawa Bays, Hakata Bay is harder to eutrophicate, mainly due to the shorter residence time of freshwater.  相似文献   

鱿鱼营养成分分析     

韩素珍  董明敏 《海洋学研究》1999,17(2):64-68

对黑鱿与阿根廷鱿的营养成分作了分析,并评价了它们的营养价值。研究表明：两种鱿所含营养成分大致接近。鱿的蛋白质含量高达７３．３％～７８．８％,而脂肪含量小于４．２０％,这有利于鱿鱼干制品的加工与贮存。两种鱿的氨基酸含量比较丰富,其中谷氨酸、天冬氨酸含量特别高。阿根廷鱿氨基酸含量更为丰富,其亮氨酸稍高于鸡蛋白  相似文献   

南大洋磷虾富氟机制Ⅰ.氟的化学赋存形态研究   总被引：1，自引：0，他引：1  

潘建明  张海生  刘小涯 《海洋学报》2000,22(2)

通过对南极大磷虾（Ｅｕｐｈａｕｓｉａ ｓｕｐｅｒｂａ）进行活体生长培养,对其不同部位及生长过程中不同阶段样品进行了氟的形态赋存分析,研究表明磷虾中９０％的氟集中在甲壳中,在其生长脱壳周期中,甲壳和肌肉中的氟含量呈相对应的周期性变化,在脱壳后最初新甲壳和肌肉中氟含量较低,通过生物主动吸收,海水中氟迅速被有效吸收和转化,而磷虾所吸收的氟最终又以存在于旧甲壳中随磷虾脱壳而丢失．在磷虾的生长周期中甲壳和肌肉中的不同化学形态氟赋存变化充分证明了这一点．最后提出了磷虾富氟机制的一个过程模式．  相似文献   

长江口区浮游植物营养限制因子的研究 Ⅰ.秋季的营养限制情况   总被引：3，自引：1，他引：2  

蒲新明  吴玉霖  张永山 《海洋学报》2000,22(4):60-66

1998年11月在长江口及周围海域进行了一个航次的环境调查,并在室内以中肋骨条藻为实验藻种,应用营养加富生物测定法对本海域浮游植物的营养需求状况进行了研究．结果表明,可大致根据离河口的远近将此海域分为3个部分：近河口光限制区、过渡带光和磷酸盐限制区、远河口氮盐限制区．P与N分别为潜在营养限制因子的界线大致沿盐度为31的等盐线．并指出,以溶解无机氮磷比的判断标准,在悬浮物浓度较高的区域会高估磷的限制作用．  相似文献   

Middle Layer Intrusion as an Important Factor Supporting Phytoplankton Productivity at a Tidal Front in Iyo Nada, the Seto Inland Sea, Japan     

Tamiji Yamamoto  Toshiya Hashimoto  Hidetaka Takeoka  Tenji Sugiyama  Osamu Matsuda 《Journal of Oceanography》2000,56(2):131-139

Field observations were conducted to examine the processes governing the phytoplankton distribution and photosynthetic activity in and around a tidal front formed in Iyo Nada, the Seto Inland Sea, Japan. The existence of a middle layer intrusion, which, it has been suggested, moves from the mixed region to the stratified region of the tidal front, was ascertained by the phytoplankton distribution in addition to a T-S diagram. Skeletonema costatum, which originally inhabited the mixed region, was used as the indicator to reveal the intrusion. However, the tip of water containing the S. costatum population did not extend deeply into the stratified region. The velocity of the intrusion seemed to be slow enough to make biological processes, such as nutrient uptake by phytoplankton and subsequent growth, as well as the decrease in cell density due to zooplankton grazing, dominate during the transportation. The patchy distribution of copepod nauplii implied that grazing has an influence on the distribution pattern of phytoplankton. The location of high photosynthetic activity did not coincide spatially with the center of high phytoplankton biomass, suggesting the importance of these biological processes. Therefore, it is considered that the middle layer intrusion plays a role as an inducer of subsequent biological processes at the tidal front by not only supplying nutrients from the mixed region but also by increasing the vertical diffusivity.  相似文献