Role of Bacteria in the Carbon and Nitrogen Flow between Water-Column and Sediment in a Shallow Marine Bay (Bay of Piran, Northern Adriatic Sea)   总被引：2，自引：0，他引：2  

G. J. Herndl    J. Faganeli    N. Fanuko    P. Peduzzi  V. Turk 《Marine Ecology》1987,8(3):221-236

Abstract. The interdependences between phytoplankton standing crop, bacterial biomass and the dissolved organic matter (DOM) pool in the water column were investigated and related to sediment parameters in a shallow marine bay (Bay of Piran, Northern Adriatic Sea) over an annual cycle. Bacterioplankton density varied between 1–10 × 10⁵ cells ml^-1, with lowest density observed in March corresponding to the low Chi a concentrations during this period. Generation times as determined by dialysis incubations ranged between 4h (June) and 82 h (March). Mean bacterial secondary production rates during summer were about 40 mg C m^-1 d^-1 and 5mg C m^-3.d^-1 during winter. With a short time lag, DOM concentrations followed the fluctuation in Chi a.
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m^-2 d^-1 during summer and 100–200 mg C m^-2 d^-1 in winter. Sediment bacterial density varied between 10⁸ - 10⁹ cells g (sediment dry wt)^-1 in the top 5 cm sediment layer or, in terms of biomass, 4.3 g C m^-l during summer and 0.6 g C m^-2 during winter. Highest concentrations of DOM in pore waters were measured in September, coinciding with high rates of sediment oxygen demand.  相似文献   

Limited nutritional benefit to the seagrass Halophila ovalis, in culture, following sediment organic matter enrichment     

K.L. Kilminster  D.I. Walker  P.A. Thompson  J.A. Raven 《Estuarine, Coastal and Shelf Science》2006,68(3-4):675

Essential nutrients for seagrass growth may be derived from benthic decomposition of organic matter. To test this idea, cores of Halophila ovalis (seagrass-vegetated) and unvegetated sediment (control) were amended with either particulate organic matter (POM) or dissolved organic matter (DOM) to test whether a positive feed-back loop exists, where increased organic matter results in increased seagrass nutrients. POM was added in the form of seagrass wrack (0, 1, 5, 12 g core⁻¹) and DOM was added with sucrose diffusion tubes at the root zone (0, 0.8, 2.4, 5.2 g core⁻¹). Cores were incubated under saturating light conditions (12 h light/12 h dark) at 18 °C, for 4 weeks. Results suggest a complex balance between positive and negative effects of organic matter enrichment. Whilst leaf molar concentrations of N and P of H. ovalis increased (by 15 and 30% respectively), plant growth declined (up to 50% relative to control) for both DOM and POM enrichments. Phosphate was removed from sediment porewater following POM addition and most likely translocated to the leaves. Stressors other than nutrient limitation (e.g. biogeochemical constraints) reduce growth and affect the nutrient dynamics of the seagrass and should be the focus of future work.  相似文献   

黄海南部的溶解无机氮     

吴强明  陈淑珠  于志刚  刘素美  米铁柱  郭军艇  邹立 《中国海洋大学学报(自然科学版)》2001,31(1):122-128

根据 1998年 5月的调查资料 ,分析并讨论了春季黄海南部海区溶解无机氮的分布特征。结果表明 :( 1)因受长江冲淡水及沿岸流的影响 ,NH+4 - N、NO-2 - N浓度的平面分布基本呈周边高、中央低 ,NO-3 - N的浓度则基本呈长江口外海域高、中北部深水区低的分布规律。 ( 2 )调查海域深水区的溶解无机氮存在明显的层化现象 ,且底层等值线上凸密集。 10 m以浅水体 ,NO-3 - N的浓度分布均匀 ,10 m以深水体 ,NO-3 - N的浓度急剧增加 ,且呈现出随深度增加而增加的趋势 ,NH+4 - N、NO-2 - N浓度的垂直分布比较均匀。 ( 3)黄海南部表层叶绿素 a的浓度呈现周边高、中央低的分布特征。  相似文献   

Improving estuarine net flux estimates for dissolved cadmium export at the annual timescale: Application to the Gironde Estuary     

Aymeric Dabrin  Jrg Schfer  Grard Blanc  Emilie Strady  Matthieu Masson  Ccile Bossy  Sabine Castelle  Naïg Girardot  Alexandra Coynel 《Estuarine, Coastal and Shelf Science》2009,84(4):429-439

Dissolved Cd (Cd_D) concentrations along the salinity gradient were measured in surface water of the Gironde Estuary during 15 cruises (2001–2007), covering a wide range of contrasting situations in terms of hydrology, turbidity and season. During all situations dissolved Cd concentrations displayed maximum values in the mid-salinity range, reflecting Cd addition by chloride-induced desorption and complexation. The daily net Cd_D fluxes from the Gironde Estuary to the coastal ocean were estimated using Boyle's method. Extrapolating Cd_D concentrations in the high salinity range to the freshwater end member using a theoretical dilution line produced 15 theoretical Cd concentrations (Cd_D⁰), each representative of one distinct situation. The obtained Cd_D⁰ concentrations were relatively similar (201 ± 28 ng L⁻¹) when freshwater discharge Q was >500 m³ s⁻¹ (508 ≤ Q ≤ 2600 m³ s⁻¹), but were highly variable (340 ± 80 ng L⁻¹; 247–490 ng L⁻¹) for low discharge situations (169 ≤ Q ≤ 368 m³ s⁻¹). The respective daily Cd_D net fluxes were 5–39 kg day⁻¹, mainly depending on freshwater discharge. As this observation invalidates the existing method of estimating annual Cd_D net fluxes, we proposed an empirical model, using representative Cd_D⁰ values and daily freshwater discharges for the 2001–2007 period. Subsequent integration produced reliable Cd_D net flux estimates for the Gironde Estuary at the annual timescale that ranged between 3.8–5.0 t a⁻¹ in 2005 and 6.0–7.2 t a⁻¹ in 2004, depending on freshwater discharge. Comparing Cd_D net fluxes with the incoming Cd_D fluxes suggested that the annual net Cd_D addition in the Gironde Estuary ranged from 3.5 to 6.7 t a⁻¹, without any clear temporal trend during the past seven years. The annual Cd_D net fluxes did not show a clearly decreasing trend in spite of an overall decrease by a factor 6 in Cd gross fluxes during the past decade. Furthermore, in six years out of seven (except 2003), the annual Cd_D net fluxes even exceeded river borne total (dissolved + particulate) gross Cd fluxes into the estuary. These observations were attributed to progressive Cd desorption from both suspended particles and bottom sediment during various sedimentation–resuspension cycles induced by tidal currents and/or continuous dredging (navigation channel) and diverse intra-estuarine sources (wet deposition, urban sources, and agriculture). Provided that gross fluxes remain stable over time, dissolved Cd exportation from the Gironde Estuary to the coastal ocean may remain at the present level for the coming decade and the estuarine sedimentary Cd stock is forecast to decrease slowly.  相似文献   

贻贝外套膜富硒液的研究     

毛文君  管华诗  李八方 《中国海洋大学学报(自然科学版)》1995,(Z1)

提出以贻贝的外套膜为主要原料，通过多种酶水解及其它工艺处理，研制出贻贝外套膜富硒液。分析表明，提取液富含天然有机硒、锌、铁、铜、锰微量元素及丰富的维吐素Ａ、维生素Ｅ、必需氨基酸等多种天然营养物质。  相似文献   

几种海洋生物中硒存在形式初探   总被引：1，自引：0，他引：1  

毛文君  管华诗  李八方 《中国海洋大学学报(自然科学版)》1995,(Z1)

采用不同提取分离方法，分析几种海洋生物中硒的存在形式。结果表明，贻贝、扇贝及海藻中硒有相似的分布特点，大部分硒是以蛋白质和氨基酸形式存在。  相似文献   

南黄海溶解有机碳的生物地球化学特征分析   总被引：1，自引：5，他引：1  

贺志鹏  宋金明  张乃星 《海洋科学进展》2006,24(4):477-488

依据1997-2003年每年1次的南黄海调查得到的溶解有机碳(DOC)数据,重点分析了2002年秋末冬初季节南黄海DOC的分布特征及其生物地球化学控制机制。结果表明,2002年秋末冬初南黄海表层海水DOC质量浓度为1.62~2.42 mg/L,平均值为2.02 mg/L,高于大洋的平均值,具有典型近海特征;南黄海DOC分布呈现北部高,南部低,在量值上,A断面>B断面>C断面,且有显著近岸高、远离海岸中部海区低的特点。近岸高值区主要受陆源输入影响,包括径流输入和人类活动两个方面,陆源输入相对生物生产过程更为重要;中部低值区主要受控于来自东海低DOC海流的冲淡作用。垂直方向上DOC质量浓度变化不大,这明显与南黄海海水混合较好有关。7 a中南黄海DOC质量浓度总体上呈略微下降趋势,北部海域表现尤为明显,南黄海生物生产量的下降及近年来南黄海整体环境质量的提高是引起DOC下降的主要原因。  相似文献   

深圳大鹏湾、珠江口海水有害重金属分布特征   总被引：16，自引：0，他引：16  

黄向青  张顺枝  霍振海 《海洋湖沼通报》2005,(4):38-44

本文利用“深圳—珠海近岸海洋地质环境调查及地质灾害防治的调查研究”项目海水样品有害重金属测试数据,分析了深圳大鹏湾、珠江口海水有害重金属的分布特点,并与沉积物中的有害重金属含量进行综合比较,最后根据国家标准进行了水质评价。结果表明,研究区有害重金属含量、比例以及分布特征不尽相同,深圳大鹏湾超标有害重金属主要是Cr^＋6、Cu、Pb,珠江口则主要是Pb、Cr^6＋,其中以Pb是超标最为严重,其来源不仅与地球化学本底值有关,也与人类活动直接联系。  相似文献   

Degree of nutrient consumption as an aging index of upwelling or vertically mixed water in the northern Taiwan Strait     

CHEN Chentung Arthur  HSING Liyu 《海洋学报(英文版)》2005,24(1):115-124

In order to determine the relative aging slams of upwelled or vertically mixed water in the northern Taiwan Strait, a recently developed method of calculating the degree of nutrient consumption (DNC) was employed. Upwelling was detected at a water depth of about 75m in summer. Bottom waters in the aphotic zone and newly-upwelled waters in the euphotic zone were found to be low in terms of their DNC. In general, a low DNC was noted alongside the other traditional upwelling indicators, such as lower temperature and degree of oxygen saturation, but higher salinity, apparent oxygen utilization, nutrient contents and chlorophytt-a. Enhanced vertical mixing, but without an apparent upwelling signal, was detected near the same location in winter.  相似文献   

硒在极大螺旋藻细胞中的分布特点及对生化组成的影响          下载免费PDF全文

张跃平  王大志  高亚辉  程兆第 《海洋科学》2007,31(2):31-34

研究了极大螺旋藻(Spirulina maxima)在实验室培养和规模化中试培养条件下,在其培养基中添加20×10-6Na2SeO3后,硒在其细胞中的分布特点及对生化组成的影响。结果表明,硒在细胞中的质量比可达126.7μg/g(实验室培养),甚至高达606.5μg/g(中试培养),其中主要分布于细胞中的蛋白质中,占总硒的69.4%(实验室培养),甚至可达94%(中试培养),比对照组增长了33.4%;糖类和脂类中硒仅占小部分,糖类1.4%,脂类2.7%~3.5%。20×10-6Na2SeO3的存在没有影响极大螺旋藻的生长,生物量反而提高了6.0%;其中糖类提高了49.6%,脂类25.0%,但蛋白质下降了11.1%。  相似文献