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1.
大亚湾营养物质变异特征 总被引：38，自引：0，他引：38
利用大亚湾现场调查和室内模拟数据,以及大亚湾生态网络17～18年8个航次的现场调查资料,采用营养状态质量指数(NQI)的方法评价大亚湾海域富营养化水平,结果表明,大亚湾海域除部分养殖海区为中营养状态外,大部分为贫营养状态;溶解态的无机磷和硅在过去10a多有较大幅度的下降,而溶解态的无机氮、溶解氧和叶绿素a则上升;浮游植物生长由过去认为由氮控制转变为现在由磷控制.分析了养殖海区底层海水、上覆水、沉积物间隙水中营养盐的含量及其化学形态.估算了沉积物-海水界面营养盐扩散通量,NH4+,NO2-,NO3-,HPO42-,H4SiO4平均通量分别为302.0,-0.06,-1.82,2.53,47.6μmol/(m2·d).室内模拟了天然海水体系表层沉积物营养盐的吸附-解吸及其磷酸盐在沉积物上的吸附等温线.论述了大亚湾海域营养盐与赤潮的关系. 相似文献
2.
为探讨浒苔绿潮消亡腐败过程中的营养盐释放规律以及浒苔绿潮聚积腐烂对海水水质的影响，在室外模拟近岸浒苔绿潮聚积腐烂过程，并于2018年6月在浒苔绿潮靠岸前开始对主要浒苔绿潮聚积地(鳌山湾、鳌山湾口的海参池、石老人海域)进行观测，实时记录浒苔腐烂状况及对周边环境的影响。模拟实验结果表明:各形态氮、磷营养盐在浒苔腐烂分解过程中升高明显，且以溶解有机态、颗粒态为主。其中生物量为5 g/L实验组溶解有机氮(Dissolved Organic Nitrogen，DON)、颗粒态氮(Particulate Nitrogen，PN)、溶解有机磷(Dissolved Organic Phosphorus，DOP)、颗粒态磷(Particulate Phosphorus，PP)的浓度在浒苔腐烂分解过程中达本底浓度的5～10倍以上。现场调查结果显示，随着浒苔绿潮在青岛近岸聚积，各调查站点的溶解无机氮(Dissolved Inorganic Nitrogen，DIN)、DON、DOP受浒苔绿潮吸收影响均降至最低值，后随着浒苔绿潮腐烂逐渐上升，水质恶化。其中鳌山湾受浒苔绿潮腐烂影响最为严重，在调查期间水体甚至劣于二类水质。PN、PP为调查区内营养盐的主要赋存形式，其中鳌山湾海域PP变化最为明显，随着浒苔绿潮聚积腐烂达到最高值(2.02 μmol/L)。相比于鳌山湾，石老人海域海水交换能力强且在浒苔绿潮靠岸后进行了及时拦截打捞，受浒苔绿潮消亡腐烂影响较小。浒苔绿潮靠岸聚积腐烂，使海域内营养盐含量与结构明显变化，影响海域浮游植物群落结构的稳定,可能引发赤潮等次生生态灾害。因此需要及时清理聚积在青岛近岸的浒苔，避免其腐烂对周边环境造成影响。 相似文献
3.
人类活动引起的营养物质输入导致大亚湾出现海水富营养化、赤潮频发和生物多样性下降等生态问题。为探究陆源输入影响下大亚湾湾顶淡澳河输入对湾内浮游植物粒级结构和种类组成的影响, 2016年10月在大亚湾进行了原位观测和培养试验。原位观测结果显示, 淡澳河口的总溶解态氮、磷浓度分别达到85.3μmol·L-1和1.5μmol·L-1。加富培养试验结果表明, 淡澳河河口水加富对总叶绿素a (Chl a)和总浮游植物丰度有显著促进作用, 并导致浮游植物粒级结构由小粒级Chl a (0.7~20μm)占主导; 浮游植物丰度中甲藻比例升高, 主要种类为锥状斯氏藻(Scrippsiella trochoidea)和原甲藻(Prorocentrum spp.)。同样, 尿素加富也促进了浮游植物群落中小粒级Chl a和甲藻的比例增加, 且主要甲藻种类与河口水加富结果一致。无机氮、磷同时加富促进了总Chl a和浮游植物总丰度增加, 而对浮游植物粒级结构和甲藻丰度则没有明显影响。对照河口水和氮、磷营养盐加富试验结果, 说明河口水携带的溶解性有机氮源可能是导致大亚湾浮游植物群落小型化, 促进甲藻生长的关键营养盐形态, 其携带的无机氮、磷同时促进总浮游植物丰度增加。本研究结果表明有机形态营养组分对大亚湾富营养化和有害藻华可能产生重要影响。 相似文献
4.
浮游植物是水生生态系统的基础生产者, 其群落结构直接影响到生态系统的健康和安全。河流输入是人类活动影响大亚湾水体环境最重要的途径之一, 淡水输入改变了水体温度、盐度、浊度和营养盐等环境因子, 对浮游植物群落结构产生影响。文章调查研究了2015年河流输入最强的夏季丰水期大亚湾的水体环境因子和浮游植物群落结构, 分析了在较强河流输入影响下浮游植物群落结构的动态变化及其对环境因子的响应。结果发现, 夏季大亚湾淡澳河的输入使湾顶淡澳河口区域形成层化的低盐、高温、低透明度、高营养盐的水体, 湾中部表层水体则受一定强度河流羽流影响, 而湾口和湾中部底层水体主要受外海水影响。淡澳河淡水输入是夏季大亚湾外源性氮、磷营养盐的主要来源, 而硅酸盐除河流输入外, 外海水也输入较多的营养盐使得底层水体硅酸盐浓度较高。夏季大亚湾水体营养比例失衡较严重, 溶解无机磷是限制浮游植物生长的重要因子。硅藻是大亚湾夏季浮游植物的优势类群, 调查发现3种优势种[极小海链藻(Thalassiosira minima)、中肋骨条藻(Skeletonema costatum)和圆海链藻(Thalassiosira rotula)]均为硅藻。通过聚类分析, 可将大亚湾夏季浮游植物群落主要分为3种类型, 分别为: 浮游植物丰度较大的极小海链藻藻华暴发的群落, 位于淡澳河口, 受河流输入影响明显; 中肋骨条藻占据优势的群落, 分布在受一定强度的河流及其羽流影响的湾顶和湾中部区域; 浮游植物丰度较低的群落, 无明显优势种, 主要分布在湾口海水影响区域。淡澳河口的水体环境有利于小型链状硅藻极小海链藻的快速繁殖并暴发了藻华, 藻华发生时的海水环境条件为: 温度30~31°C, 盐度17‰~31‰, 水体透明度0.45~1.2m。硅藻对不同营养盐利用的差异以及随后的生物碎屑和颗粒沉降过程导致藻华发生区域Si∶N值略降低, N∶P值显著升高。河流输入影响下, 单一物种大量生长使得浮游植物群落种类组成丰度分布极不均匀, 从而导致淡澳河口浮游植物群落的种类多样性和均匀度指数降低, 种类多样性和均匀度指数均从淡澳河口向湾口逐渐增大。 相似文献
5.
The Zhelin Bay is one of the most important bays for large-scale mariculture in Guangdong Province, China. Owing to the increasing human population and the expanding mariculture in the last two decades, the ecological environment has greatly changed with frequent harmful algal blooms. A monthly survey of water content, organic matter （TOM）, and various forms of nitrogen and phosphorous in sediment from July 2002 to July 2003 in the bay was conducted. The results showed that the water content was correlated significantly with TOM and various forms of nitrogen and phosphorus and can be used as proxy for quick and rough estimate of these factors in the future surveys. TOM was also correlated significantly with various forms of nitrogen and phosphorus, indicating that it was one of the key factors affecting the concentrations and distributions of nitrogen and phosphorus in the investigated waters. Average total Kjeldhal nitrogen （TkN） content was（ 1 113.1 ± 382.5）μg/g and average total phosphorus （TP） content was（567.2± 223.3）μg/g, and both were much higher than those of similar estuaries in China and elsewhere. Average nitrogen and phosphorus tended to be higher inside than outside the bay, higher at aquaculture than non-aquaculture areas, and higher at fish-cage culture than oyster culture areas, suggesting that large-scale mariculture inside the bay played an important role in the eutrophication of the Zhelin Bay. Various forms of nitrogen and phosphorus concentrations were higher during the warm season （July--September）, which was due to the increased decomposition and concentration of organic matter resulted from the fast growth and high mortality of the cultured species. Compared with July 2002, TkN and TP contents were much higher in July 2003, in consonance with the eutrophication of the Zhelin Bay. Because exchangeable phosphorus （Ex-P）, iron-bounded phos- phorus （Fe-P） and organic phosphorus （OP） combined accounted for 34.3% of the TP and authigenic phosphorus （Au-P 相似文献
6.
不同磷源对米氏凯伦藻生长和碱性磷酸酶活性的影响 总被引：1，自引：0，他引：1
为了解米氏凯伦藻(Karenia mikimotoi)赤潮形成的磷营养机理,作者研究了不同磷源[三磷酸腺苷二钠盐(Adenosine disodium triphosphate,ATP)、甘油磷酸钠(sodium glycerophosphate,G-P)、卵磷脂(lecthin,LEC)和Na H2PO4·2H2O]对其生长和藻细胞碱性磷酸酶活性(alkaline phosphatase activity,APA)的影响。结果表明:(1)米氏凯伦藻可以有效利用无机磷(Na H2PO4·2H2O),对有机磷源如三磷酸腺苷二钠盐(ATP)、甘油磷酸钠(G-P)也能有效利用,但不能有效利用卵磷脂(LEC);(2)米氏凯伦藻碱性磷酸酶的检测中,在起始阶段,不同磷源(ATP,G-P,LEC和Na H2PO4·2H2O)的米氏凯伦藻APA达到最大值,米氏凯伦藻的APA分别为6.0,10.5,8.0和0.4 pmol/(个·h)。随培养时间的持续,各有机磷培养基中米氏凯伦藻的APA均表现出先逐渐减小,而后增强,最后在最大值维持的趋势,而以Na H2PO4·2H2O为磷源的米氏凯伦藻的APA没有明显的增加;(3)单个细胞的米氏凯伦藻的APA位点分布明显,大致位于细胞表面。通过研究发现,米氏凯伦藻在外界环境无机磷限制的条件下,能够较好地吸收利用有机磷维持生长,印证了近年来米氏凯伦藻赤潮频繁地发生在磷限制海域的事实。 相似文献
7.
近岸海域水体和沉积物是营养盐迁移转化的重要场所。2016年8月对渤海湾水体和沉积物进行采样监测,分析了渤海湾水体和沉积物中不同形态氮、磷的含量,并研究了营养盐在水体和沉积物中的分布特征及其相互关系。结果表明:渤海湾水体中的营养盐在西部近岸地区含量较高,而在离海岸线较远的开阔海域含量较低,表现出一个明显的质量浓度梯度。说明人类活动对近岸海域水体中营养盐含量的贡献较为明显。水体中营养盐主要是以无机态为主,无机氮和无机磷分别占到总氮和总磷的76.65%和76.46%。沉积物中氮、磷营养盐表现出和水体中营养盐含量类似的空间分布特征,但形态主要以有机氮为主,无机磷的含量也仅占到30.42%。这说明夏季渤海湾水体中氮、磷营养盐主要由水中有机体通过同化作用将无机态营养盐合成为有机态营养盐进入沉积物,渤海湾西北海域的富营养化过程是水体中营养盐向沉积物迁移的一个主要驱动力。 相似文献
8.
广西北海半岛夏季营养盐及水质状况分析 总被引：1，自引：0，他引：1
近年北部湾藻华灾害频发,为了解与藻华暴发密切相关的营养盐及水质状况,2020年8月作者对北部湾北海半岛铁山港、营盘、涠洲岛、斜阳岛及涠洲岛西部远岸海域共21个站位采集表层海水,分析营养盐含量和结构特征,并利用富营养化指数和有机污染指数对该海域水质进行等级划分与评价。结果表明：北海半岛海域DIN、PO4-P和SiO3-Si均值分别为0.210、0.021和0.270 mg/L。其中,铁山港营养盐由港内至港外呈递减趋势,营盘海域由近岸至远岸,DIN和SiO3-Si含量先递减再增加,PO4-P则表现为递增,涠洲岛海域及远岸各站位营养盐分布无明显特征。北海半岛海域N/P、Si/N和Si/P均值分别为11.8、1.7和14.6,显示47.6%海域为潜在N限制,而潜在P限制和Si限制海域均为9.5%;叶绿素a仅与COD显著相关,相关系数为0.475。调查海域富营养化指数均值1.82,以铁山港港内富营养化程度最高,由港内严重富营养至港外贫营养递减,营盘近岸7号站位中度富营养,其余76.2%调查站位仍处于贫营养水平;有机污染指数均值1.85,良好和较好水质共占38.1%,其余61.9%水质受到不同程度有机污染,亦以铁山港水质污染最为严重,重度污染仅在该海域发现。可见,北海半岛夏季表层海水以潜在N限制为主,铁山港和营盘近岸富营养化和有机污染较严重,其余站位基本良好,影响表层水体叶绿素a含量的主要因素是有机质,可能与海域微生物强烈降解作用相关。本研究可为北部湾海洋环境保护和赤潮研究提供基础环境数据。 相似文献
9.
Sofia Loureiro Esther Garcs Margarita Fernndez-Tejedor Dolors Vaqu Jordi Camp 《Estuarine, Coastal and Shelf Science》2009,83(4):539-549
Samples were collected during one annual cycle (April 2007–March 2008) at Alfacs Bay (NW Mediterranean Sea) central station in order to assess the influence of organic nutrients in the growth of the microalgae assemblage, with special reference to Pseudo-nitzschia spp. This potentially toxic diatom forms natural and recurrent blooms in the study area. To assess further the relationship between Pseudo-nitzschia spp. and nutrients an enrichment experiment with high molecular weight dissolved organic matter (HMWDOM) was performed with field samples obtained during a Pseudo-nitzschia spp. bloom. HMWDOM was extracted from water collected at Alfacs Bay. Five bioassays were prepared: N + P (seawater with addition of nitrate and phosphate), DOM (addition of HMWDOM), (−N + P) + DOM (nitrogen deficient, with addition of phosphate and HMWDOM), (N + P) + DOM (addition of nitrate, phosphate and HMWDOM), seawater control (without added nutrients), and B + DOM (control of bacteria, without microalgae). The experiment was run in batch mode over 4 days. Results from the field study revealed that the concentrations of organic nutrients mostly surpassed the inorganic pool. Pseudo-nitzschia spp. was the most frequent and abundant taxa of the microalgae community. The micro-planktonic assemblage was arranged according to a seasonal factor (ANOSIM and cluster analysis). DON, nitrate and silicate were the most important abiotic parameters contributing to the dissimilarities between seasons (SIMPER analysis) and thereby potentially influencing the seasonal distribution of microalgae in the representative station. In the experimental investigation, Pseudo-nitzschia cells increased by the end of the experiment in the DOM bioassay but no respective increase was observed for chlorophyll a. This could point to an acquisition of nutrients through the DOM fraction that would conjointly reduce the need of chlorophyll a. The data obtained suggest that organic nutrients may exert an important role in the development of microalgae, including Pseudo-nitzschia spp., in the selected location. 相似文献
10.
近百年来大亚湾沉积物有机质的沉积记录及对人为活动的响应 总被引：1，自引：1，他引：0
通过对沉积物中粒度组成、总有机碳（TOC）、总氮（TN）、碳氮比（TOC/TN）和碳、氮稳定同位素丰度（δ13C、δ15N）等的分析，结合沉积年代学信息与端元混合模型结果，解析了百年尺度下大亚湾沉积物中不同来源有机质的演变过程及控制因素。结果表明，大亚湾沉积物特性在20世纪70年代末至80年代初发生了显著改变:在此之前，TOC、TN、δ13C和δ15N表现稳定，陆源与海源有机碳的比例维持在3∶7，而自此之后，TOC与TN含量显著升高，TOC/TN持续下降，在1980—2000年和2010年至今都出现了陆源有机碳比例升高，海源有机碳比例降低的现象。上述显著变化表明大亚湾海洋环境自20世纪70年代末至80年代初已经发生了重大变化。近20年来GDP与沉积柱中TN和δ15N呈现出的显著正相关，与TOC/TN呈现出的显著负相关，表明沿岸经济的迅猛增长，水产养殖业的快速发展，周边人口的急速增加等人为活动，是造成大亚湾生态环境变化的重要原因。未来的研究应更密切关注人为活动对海湾生态环境的影响，通过法律法规约束行为，加强海湾生态环境保护与修复治理工作。 相似文献
11.
近年来,东海原甲藻赤潮在我国东海近岸海域频繁发生。本研究利用生物-物理耦合模型对发生于2005年的东海原甲藻赤潮进行后报模拟,并对控制其起始与发展的因素展开研究。该模型由东海原甲藻种群动力学模型与多层嵌套的水动力模型组合。通过对比模拟结果与室内实验结果,证实种群动力学模型能够很好地重现东海原甲藻在不同光照与磷营养限制条件下的生长过程,同时能够再现藻细胞内部磷含量及藻类对外部营养盐浓度的影响。耦合模型能够较好地再现模拟海域水动力（见Sun et al.,2016）与东海原甲藻赤潮的时空分布。模拟的赤潮发展过程与此前研究中的观测结果一致,且模拟结果表明模型能够捕捉到赤潮初期种群的次表层孕育现象。随后模拟结果被用于诊断决定赤潮垂直分布的决定性因素,结果表明磷酸盐是控制这一现象的关键因素。同时,表层风场在决定赤潮的分布中扮演着重要角色。模拟结果强调了营养盐限制在东海原甲藻次表层孕育及消散过程中的作用,本文所建立的耦合模型需要进一步优化并应用于其它条件下东海原甲藻赤潮的研究中。 相似文献
12.
敌百虫是使用最为广泛的有机磷农药之一,在水产养殖中主要用于防治甲壳类寄生虫。本文研究了72 h的急性暴露以及25 d的亚慢性暴露下,敌百虫对两种赤潮微藻海洋卡盾藻和锥状斯氏藻生长的影响,以了解敌百虫对海洋微藻的毒性及海洋初级生产力的影响。在急性暴露下,高质量浓度敌百虫能明显抑制两种藻细胞的生长,而低质量浓度则对藻细胞的生长影响不明显,敌百虫对海洋卡盾藻和锥状斯氏藻生长的72 h EC50分别为32.1 mg/L和22.1 mg/L。在亚慢性暴露下,两种藻细胞对敌百虫的敏感性相近,高质量浓度组(25 mg/L)的藻细胞在暴露的第7~9天就全部死亡;1 mg/L的低质量浓度组,藻细胞的生长状况与对照组相近;5 mg/L和10 mg/L质量浓度组在暴露初期对藻细胞生长具有抑制作用,但在暴露后期则明显刺激了藻细胞的生长。本研究说明水环境背景质量浓度下的敌百虫不会抑制浮游植物的生长,但施药一段时间后,可刺激藻细胞的生长,从而增加了引发赤潮的风险。 相似文献
13.
The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released by the decomposition of jellyfish on the ecosystem in the field. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai was examined in a series of experiments under different incubation conditions such as different p H values, salinity values, temperatures and nitrogen and phosphorus concentrations. The results showed that the complete decomposition of Nemopilema nomurai generally took about 4–8 d. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai could be divided into two stages: the early stage and the later stage, although the efflux rate of nitrogen was one order more than phosphorus. In the early stage of the decomposition of Nemopilema nomurai, the concentrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in seawater increased rapidly, and the concentration of nitrogen could reach the highest level in the whole degradation process. In the later stage of the decomposition, the concentrations of dissolved nitrogen and total nitrogen declined slowly, while the concentration of phosphorus in water could reach a maximum in the degradation process. High p H, low salinity,high temperature and N/P will promote the release of nitrogen; low p H is unfavorable to the release of nitrogen but favorable to the release of phosphorus. In addition, we found the concentrations of ammonium and phosphate in the bottom water were higher than those in the surface water during the period of jellyfish bloom in the Jiaozhou Bay, proving that nutrients released by the decomposition of jellyfish have significant influence on nitrogen and phosphorus in the field. For the whole Yellow Sea, nutrients released by jellyfish carcasses may reach up to(2.63±2.98)×107 mol/d of dissolved nitrogen(DN) and(0.74±0.84)×106 mol/d of dissolved phosphorus(DP) during the period of jellyfish bloom. The values are comparable to riverine inputs in a day, but much higher than sediment–water exchange flux in the Yellow Sea. The great amounts of nutrients must have significant influence on the nutrients balance of the Yellow Sea during the period of jellyfish dead and decomposition. Both the experimental data and field observations proved that the decomposition of jellyfish may release a great amount of nutrient to the surrounding environment during the period of jellyfish decomposition. 相似文献
14.
1 IntroductionNitrogen and phosphorus together constitute thematerial basis used by phytoplankton for photosyn-thesis; however, if the ratio of nitrogen atomic massto phosphorus atomic mass in an aquatic environmentmarkedly deviates, whether above or bell… 相似文献
15.
Seasonal monitoring of the levels of carbon, nitrogen and phosphorus in two green macroalgae (Ulva and Enteromorpha) was carried out at 22 sampling sites in four embayments (rías) on the northwest coast of Spain. Sediments were also analysed to determine the concentrations of these elements as well as organic matter, organic carbon, iron and texture. In addition, accumulations of Ulva were monitored. Nitrogen levels in algae were similar to those found in comparable studies, whereas carbon concentrations were generally higher and those of phosphorus were lower. As a result the macroalgae were relatively enriched by carbon and nitrogen compared with phosphorus. Seasonal variations in algal tissue nitrogen and phosphorus followed the usual pattern for temperate zones, with minimum levels in summer and maximum levels in winter. Variations in carbon concentrations were much less accentuated. The low levels of P in the algae appear to indicate limitation by this element, however, comparison of the monthly changes in nitrogen and phosphorus in Ulva with the critical concentrations of these elements suggests dual nutrient limitation in this alga in summer. By contrast, the sediments were more enriched by phosphorus; high retention of this element by the sediment may explain the low levels in algae. The highest accumulations of Ulva occurred in spring and summer; hydrodynamic factors appeared to be important in determining the extent of these accumulations. 相似文献
16.
At four stations in Tokyo Bay, pore water profiles of dissolved organic carbon (DOC), nitrogen (DON), phosphorus (DOP), and inorganic nutrients were determined at 3-month intervals over 6 years. Concentrations of dissolved organic matter (DOM) and nutrients were significantly higher in pore waters than in the overlying waters. Pore water DOC, DON, and DOP concentrations in the upper most sediment layer (0–1 cm) ranged from 246 to 888 μM, from 14.6 to 75.9 μM, and from 0.02 to 9.83 μM, respectively. Concentrations of DOM and nutrients in pore waters occasionally showed clear seasonal trends and were highest in the summer and lowest in the winter. The seasonal trends in the pore water DOM concentrations were coupled with trends in the overlying water temperature and dissolved oxygen concentration. Benthic effluxes of DON and DOP were low compared with those of inorganic nutrients, accounting for only 1.0 and 1.5 % of the total benthic effluxes of nitrogen and phosphorus, respectively; thus benthic DOM fluxes were quantitatively insignificant to the inorganic nutrient fluxes in Tokyo Bay. The DOM fluxes represented about 7, 3, and 10 % of the riverine discharge of DOC, DON, and DOP to Tokyo Bay, respectively. 相似文献
17.
Marguerite S. Koch Demetris C. Kletou Rosanna Tursi 《Estuarine, Coastal and Shelf Science》2009,83(4):403-413
Few phosphorus-depleted coastal ecosystems have been examined for their ability to hydrolyze phosphomonoesters. We examined seasonal (August 2006–April 2007) alkaline phosphatase activity in Florida Bay, a phosphorus-limited shallow estuary, using fluorescent substrate at low concentrations (≤2.0 μM). In situ dissolved inorganic and organic phosphorus levels and phosphomonoester concentrations were also determined. Water column alkaline phosphatase activity was partitioned into two particulate size fractions (>1.2 and 0.2–1.2 μm) and freely dissolved enzymes (<0.2 μm). Water column alkaline phosphatase activity was also compared to leaf and epiphyte activity of the dominant tropical seagrass Thalassia testudinum. Our results indicate: (1) potential alkaline phosphatase activity in Florida Bay is high compared to other marine ecosystems, resulting in rapid phosphomonoester turnover times (2 h). (2) Water column alkaline phosphatase activity dominates, and is split equally between particulate and dissolved fractions. (3) Alkaline phosphatase activity was highest during cyanobacterial blooms, but not when normalized to chl a. These results suggest that dissolved, heterotrophic and autotrophic alkaline phosphatase activity is stimulated by phytoplankton blooms. (4) The dissolved alkaline phosphatase activity is relatively constant, while the particulate activity is seasonally and spatially dynamic, typically associated with phytoplankton blooms. (5) Phosphomonoester concentrations throughout the bay are low, even though potential hydrolysis rates are high. We propose that bioavailable dissolved organic P is hydrolyzed by dissolved and microbial alkaline phosphatase enzymes in Florida Bay. High alkaline phosphatase activity in the bay is also promoted by long hydraulic residence times. This background activity is primarily driven by carbon and phosphorus limitation of microorganisms, and regeneration of enzymes associated with cell lysis. Pulses of inorganic phosphorus and labile organic phosphorus and nitrogen may stimulate autotrophs, particularly cyanobacteria, which in turn promote biological activity that increase alkaline phosphatase activity of both autotrophs and heterotrophs in the bay. 相似文献
18.
Enrichments with five types of organic carbon, differing in nitrogen content and type of organic carbon, were made to a marine sediment in order to study effects on nitrogen fluxes. The enrichments used were Ulva lactuca, Ascophyllum nodosum, Zostera marina, Ceratium spp., lignin, and mixtures of U. lactuca and A. nodosum. Fluxes of ammonium, nitrate, and phosphate were measured in short-term (48 h) microcosm experiments, using a carbon enrichment loading similar to that at the sampling site. Changes in microbial community growth and structure due to three types enrichments were also detected using molecular methods in a microcosm experiment run for 4 days to allow for detection at DNA-level.Ammonium fluxes changed from an efflux in the control to an influx for all enrichments apart from U. lactuca. The change was significantly related to the added material's C:N ratio when Ceratium spp. was excluded. All enrichments induced an influx of nitrate suggesting the formation of anoxic micro zones, but there was no relationship with C:N ratio. Instead, the magnitude of the nitrate influx is suggested to be related to the structure of the organic carbon, where enrichments containing a large pool of cellulose and lignin (Z. marina and lignin) gave rise to a lower influx, compared to algal material with more easily degraded organic matter like lipids and starch, which induced the highest influx of nitrate (Ceratium spp., U. lactuca, and A. nodosum). The occurrence of an ammonium influx together with increased nitrate influx and a lower efflux of phosphate in the enrichments suggests a growth of heterotrophic bacteria. This was also confirmed using molecular methods (PCR-DGGE) where the relative abundance of bacterial species in the enrichments increased.The sum of ammonium and nitrate fluxes showed that total nitrogen removal was enhanced in all enrichments compared to the nonenriched control sediment, but in different ways. Ceratium spp. induced the highest removal followed by A. nodosum, U. lactuca, Z. marina, and lastly, by lignin. The same pattern was observed also in a second experiment. These results indicate that easily degradable organic carbon, together with a lower C:N ratio of the added material, will remove nitrogen from the water phase, making the recycling of nitrogen to the overlying water mass smaller. 相似文献
19.
大亚湾微表层和次表层海水营养盐的研究 总被引：11，自引：0，他引：11
根据1998年秋季（10、11月）、1999年春、秋季（4、5、10月）5个航次对大亚湾海区微、次表层的调查结果，分析了微表层海水对氮、磷、硅营养盐的富集概况，讨论了营养盐与环境因子的关系。结果表明：大亚湾海区微表层海水对氮、磷、硅营养盐均有富集作用，因海况及季节不同，富集因数（EF）与其他海区的有所差别；无论夏季或秋季，大亚湾海区微表层海水中无机氮都以NH4－N为主要存在形态；其余水层则以NO3－N为主要存在形态。结果还表明，微表层、次表层海水中NH4－N与BOD5、COD测值都呈高度显著正相关，与PO4－P和SiO3-Si含量均无相关，说明大亚湾海区水中含氮有机物较含磷有机物丰富。 相似文献
20.
Jutarat Kittiwanich Tamiji Yamamoto Toshiya Hashimoto Keiko Tsuji Osamu Kawaguchi 《Journal of Oceanography》2006,62(4):493-509
A numerical ecosystem model expressing both phosphorus and nitrogen cyclings in the pelagic system of Hiroshima Bay, Japan,
was developed in order to investigate the seasonal variations of these elements and their annual budgets. Based on the geophysical
and chemical structures of the bay, Hiroshima Bay was divided into northern and southern boxes, themselves divided into two
layers of an upper 5 m and a lower layer according to the stratification of the water column. The model consists of equations
representing all relevant physical and biological processes. The results revealed that the internal regeneration of materials
was an important source of bioavailable nutrients for phytoplankton growth in the water column. The incorporation of phytoplankton
aggregation improved the accuracy of the outputs in comparison to the observed data, especially during the stratified summer
season. The results also indicated that phosphorus limitation of phytoplankton growth occurs in the upper layer during summer
while light limitation occurs in the lower layer. In addition, physical processes such as diffusion and advection were also
important as they ensured that most of regenerated nutrients in the lower layer were transported to the upper layer. Thus,
these processes might support the high primary production and the production of oysters that are extensively cultured in this
bay. Considering the informative results obtained, the model used in this study provides a sound basis and tool to describe
the dynamics of phosphorus and nitrogen cyclings in Hiroshima Bay. 相似文献