首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
The seasonal dynamics of nutrient ratios and abundance of phytoplankton cells from the central (CB) and western (WB) Bay of Bengal (BOB) were studied during the fall intermonsoon (FIM; September-October 2002) and spring intermonsoon (SpIM; April-May 2003). The nutrient molar ratios of macronutrients such as nitrate to phosphate (N:P), nitrate to silicate (N:Si) and silicate to phosphate (Si:P) in the top 120m were calculated for both FIM and SpIM. During both the seasons, the N:P ratios along the CB and WB were lower than 16, indicating nitrate deficiency. Whereas, along both transects the N:Si ratio was <1 and Si:P >3 in the top 20 and 40m during FIM and SpIM, respectively, indicating Si enrichment. Relatively greater nutrient concentrations along the WB than the CB appear to contribute to higher phytoplankton abundance. The preponderance of diatoms in the Bay could be attributed to rapid utilization of available nutrients in particular during FIM thus resulting in low N:Si ratios in the water column. Among diatoms, pennales were predominantly controlled by nutrients and their ratios. While, apart from nutrients, physical stratification, light and eddies also seem to influence the distribution and abundance of centrales.  相似文献   

2.
Using chemometrics to evaluate anthropogenic effects in Daya Bay, China   总被引:9,自引:0,他引:9  
In this work, we have monitored 12 stations to study the effects caused by natural, marine and anthropogenic activities on water quality in Daya Bay, China. Results show that the N:P ratios are 71.54, 41.29, 81.50 and 98.27 in winter, spring, summer and autumn, respectively. Compared with the data of the past 20 years, the atomic N:P ratios have increased, indicating increased potential for P limitation; the atomic Si:N ratios have decreased; the nutrient structure has substantially changed over a period of 20 years. These findings show that the nutrient structure may be related to anthropogenic influence. The data matrix has been built according to the results, which were analyzed by principal component analysis (PCA). This analysis extracted the first four principal components (PC), explaining 73.58% of the total variance of the raw data. PC1 (25.53% of the variance) is associated with temperature, salinity and nitrate. PC2 (21.64% of the variance) is characterized by dissolved oxygen and silicate. PC3 (15.91% of the variance) participates mainly by nitrite (NO2-N) and ammonia (NH4-N). PC4 explaining 10.50% of the variance is mainly contributed by parameters of organic pollution (dissolved oxygen, 5-day biochemical oxygen demand and chemical oxygen demand).PCA has found the important factors that can describe the natural, marine and anthropogenic influences. Temperature and salinity are important indicators of natural and marine characters in this bay. The northeast monsoons from October to April and southwest monsoons from May to September have important effects on the waters in Daya Bay. It has been demonstrated that anthropogenic activities have significant influence on nitrogen form character. In spatial pattern, a marine aquaculture area and a non-aquaculture area are widely identified by the scores of stations. In seasonal pattern, dry and wet season characters have been demonstrated.  相似文献   

3.
杭州湾营养盐时空分布特征及其影响研究   总被引:1,自引:0,他引:1       下载免费PDF全文
文章基于2015年1—12月杭州湾海域12个航次的调查资料,对杭州湾海域营养盐溶解无机氮(DIN)和活性磷酸盐(PO_4~(3-))的月度时空分布特征及其影响进行了探讨。结果表明,杭州湾表层海水DIN和PO_4~(3-)含量空间分布月际间变化明显,其变化受湾内、沿岸径流输入和长江冲淡水影响显著。杭州湾海域12个月DIN含量均超第四类海水水质标准,硝酸盐氮(NO_3~-)占DIN的94%及以上。N/P值处于较高水平,内湾(IB)和外湾(OB)的N/P值季节性变化幅度比中湾(CB)大,海湾生态系统对磷的变化敏感。营养盐-盐度对研究区域的水体混合状况有明显的指示作用,杭州湾营养盐的分布主要受物理混合作用所控制,浮游生物活动对营养盐分布的影响相对较小。  相似文献   

4.
The changes in the concentrations of silicate, phosphate and inorganic nitrogen in Elefsis Bay, an intermittently anoxic basin, are described and related to the changes in the physical properties of the water for two seasonal cycles. Winter convection resulted in a very small vertical gradient of temperature, salinity, oxygen and nutrients. Stratification started to develop in May and persisted for about 6 months. In Elefsis Bay, high values of silicate, phosphate and ammonia occurred during the anoxic conditions prevailing in summer. The consumption of oxygen in the lower water column was directly related to density differences in it. The regeneration of nutrients was related to the consumption of oxygen, with seasonal differences in the regeneration of nitrate and silicate. A stoichiometric model indicates that plankton organisms in Elefsis Bay have approximate ratios for C:N:P of 105:14:1, whereas the ratio for nitrogen and phosphorus in the water is only 2:1. The water/plankton relationship in Elefsis Bay appears to be very similar to that in the Baltic Sea.  相似文献   

5.
从研究胶州湾沉积物中生源硅入手,利用对比分析对其限制的原因进行了探讨.研究表明,相对于邻近的黄海和渤海沉积物,胶州湾沉积物中的生源硅含量较高,在湾内外的三个站表层沉积物中生源硅的含量分别为1.58%、1.44%、1.48%,在整个柱状样中的平均含量分别为1.54%、1.48%和1.39%,属于高生源硅含量区.沉积物中BSi∶TN远远大于1,BSi∶TP也远远大于16,与水体中Si∶TN〈1,BSi∶16P〈1相反,同时沉积物中的OC∶BSi值远远小于Redfield比值(106∶16),表明沉积物中有机质的分解速率远大于BSi的分解速率,生源硅分解的较慢.研究还发现,生源硅和有机碳的含量有明显的正相关关系,二者共同作用的结果是造成相当大的一部分BSi被埋藏,不能参与再循环,从而水体中的硅被永久地“清除”,造成水体硅的缺乏,这可能是造成胶州湾浮游植物生长硅限制的根本原因.湾外BSi较湾内低的主要原因是湾外的沉积物因其有机质含量低,且沉积物的颗粒粗而造成BSi的溶解速率比湾内的高.根据沉积物中生源硅的沉积通量和初级生产力的对比可推知,由硅藻形成的生源硅在沉降过程中平均只有15.5%被分解重新进入水体,其余的84.5%可被埋葬而形成沉积物.而胶州湾沉积物中的硅通过沉积物-海水界面返回到水体中的速率也小于生源硅的沉积速率,这进一步证明了海水中的硅不断向沉积物迁移,导致水体中硅含量持续的低水平,进而使Si成为浮游植物生长限制因子的主要原因.  相似文献   

6.
To investigate the impacts of nutrient concentrations and N:P:Si ratios on the ecosystem of the Huanghai Sea (Yellow Sea), the current status and long-term variation of nutrients concentrations and ratios as well as phytoplankton community structure in the Huanghai Sea were collected and analyzed. The results reveal great annual and seasonal fluctuations in the nutrient concentrations and N:P:Si ratios during 1998-2008 with no clear pattern observed in the whole region. Yet on a seasonal scale of spring and in the coastal regions such as the Jiaozhou Bay and Sanggou Bay, the increase of DIN concentration and N:P ratio as well as the decrease of phosphate and silicate concentrations and Si:N ratios were relatively significant. Many pelagic ecosystem changes have occurred concurrent with these changes of the nutrient regime, such as the recent increase of primary production, changes of phytoplankton chlorophyll a biomass and abundance, an increase of eutrophication, and occurrence of HABs. In addition, new trends in the variation of nutrients seem to be developing in some particular transect such as 36°N, which suggests that long-term and systematic ecosystem monitoring in the Huanghai Sea is necessary.  相似文献   

7.
In the Baltic Sea, the Gulf of Bothnia is the only sub-basin with only minor effects of eutrophication mainly due to physical factors. Most evaluations of the state of the Gulf of Bothnia are based on offshore investigations. In the present study the coastal zone of the eastern Gulf of Bothnia is analysed. Long-term data (1980–2007) of total nitrogen and phosphorus, turbidity and oxygen are analysed using principal component analysis (PCA) for spatial and temporal patterns in the trophic situation. The coastal zone is divided into six regions: inner and outer areas of the Bothnian Sea and the Quark, and the outer areas of the southern and northern Bothnian Bay. The results show a degradation of water quality from north to south, and from outer to inner coastal areas. Eutrophication changes from an almost non-existing problem in the Bothnian Bay in the north to clear signs of nutrient over-enrichment in the Bothnian Sea. This shows that even if eutrophication in the Gulf of Bothnia is not serious, the increasing trends in nutrient levels should be seen as warning signals for the future, and remedies to combat eutrophication should be taken rapidly.  相似文献   

8.
The occurrence of the invasive nonindigenous copepod Oithona davisae Ferrari and Orsi, 1984, is reported for the first time in the Aegean Sea. The data we collected in August 2017 from 14 stations along the Turkish coast of the Aegean Sea reveal the spatial distribution of O. davisae between the openning of the Dardanelles Strait in the north and the Izmir Bay in the south. The O. davisae individuals, in seven mesozooplankton samples collected from a single station, were consistently found in the inner part of the Izmir Bay from April 2015‐October 2016. The abundance of female O. davisae ranged from 4 ind./m3 in April 2015 to 31,524 ind./m3 in July 2016 and contributed to the total oithonid female population by 10.8% in April 2015 and 92.8% in September 2016. Our results show that this species is well established in the inner part of Izmir Bay and that it has become a permanent component of the copepod community in the area.  相似文献   

9.
根据2005年4-5月(春季)、8月(夏季)和11月(秋季)对大亚湾大鹏澳海区表层的现场调查结合营养盐加富实验,探讨了不同季节氮(NO3-或脲氮 (urea))和无机磷(PO43-)营养元素对浮游植物种类组成的潜在影响。大鹏澳海区浮游植物优势种有明显季节变化,秋季种类组成的平面变化最明显。春季浮游植物平均细胞密度最高但多样性指数最低。实验结果显示,春季至夏季浮游植物优势种翼根管藻模式变型Rhizosolenia alata f. genuina、丹麦细柱藻Leptocylindrus danicus和绕孢角毛藻Chaetoceros cinctus之间的演替可能受氮、磷条件变化的控制。夏季优势种菱形海线藻Thalassionema nitzschioides和威氏海链藻Thalassiosira weissflogii之间的演替可能受营养条件外的因素控制。尽管磷被认为是该海区浮游植物生长的主要限制因子,但夏季无机氮磷比值较高的实验组中未出现磷限制现象,无机氮磷比值的变化对浮游植物种类组成也没有显著影响,而秋季氮对浮游植物种类组成有较明显的潜在影响。  相似文献   

10.
Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.  相似文献   

11.
We measured benthic and water column fluxes in a hypersaline coastal system (Baffin Bay, Texas) in 1996–1997, a period of decreasing salinity (increased freshwater input) and turbidity. Salinity decreased from a mean of 60 to 32 practical salinity units (psu) and turbidity decreased from a mean of 78 to 25 NTU over the study period. Associated with hydrological changes, there were important changes in nutrient fluxes and metabolism. There was a shift of total respiration from the water column to the sediments and an increased amount of the benthic metabolism (2–67%) was attributed to sulfate reduction in this system when salinity was lowest, perhaps a consequence of increased benthic light levels and photosynthetic production of labile carbon in the sediments. The sediments were a large sink for both N and P. Sediment particulate C:N (9.8) and C:P (119) ratios were lower than those in the water column. However, ammonium:phosphate fluxes increased coincident with increased sulfate reduction rates and porewater sulfide concentrations. Efficient N-retention mediated through dissimilative nitrate reduction to ammonium, and high rates of N-fixation in shallow, hypersaline systems may facilitate transitions from N-limitation to P-limitation. During the most hypersaline period, seston exhibited some of the most extreme nutrient ratios ever reported for a marine ecosystem (C:N 10–37 and C:P 200–1200) and suggest that plankton are likely to be P-limited or are very well adapted to low P availability. When salinity and N:P and C:P ratios were highest, the plankton was dominated by a brown tide alga (Aureoumbra lagunensis), supporting evidence that this organism is adapted to low P, long residence time systems.  相似文献   

12.
Different environmental conditions in various nearshore waters dynamically determine the speciation of iron, its solubility, removal and hence bioavailability to phytoplankton. The iron speciation, the impact of phytoplankton blooms and the effects of organic matter on iron speciation and transformation were studied in four different coastal systems: the Trondheim Fjord, Norway, which is a coastal system that is open to a vast riverine impact; Hopevågen, Norway, a pristine coastal basin, which has negligible river and anthropogenic impact; zmir Bay, Turkey, a Mediterranean embayment with heavily polluted eutrophic inner–middle section, and the oligotrophic outer section. In this paper, we compare iron speciation in these different coastal systems. While colloidal iron (ColFe) was the predominant species especially in the Trondheim Fjord and to some degree also in Hopavågen, Chelex labile iron (ClxLFe) and hydrophobic organic-iron complex (HpOFe) were predominate species in both the inner–middle and the outer section of zmir Bay. The impact of phytoplankton blooms on the ClxLFe was significant especially in the Trondheim Fjord, in the inner–middle section of zmir Bay and in Hopevågen.  相似文献   

13.
对胶州湾底层水溶解氧、总氮、总磷、溶解无机氮、活性磷酸盐、铁及孔隙水中溶解无机氮、磷酸盐、铁和沉积物粒度、有机碳进行了分析。结果显示除铵氮外,孔隙水浓度明显高于底层水中浓度,其中硝酸氮、亚硝酸氮、活性磷酸盐、铁在孔隙水中的浓度分别为在底层水中浓度的17.8、9.3、12.5、7.7倍,暗示孔隙水中的物质可能向上覆水体扩散。在横向上,底层水及孔隙水中硝酸氮、亚硝酸氮、铵氮、活性磷酸盐都呈东岸高西岸低的分布规律,在西南部出现低值。Fe在底层水及孔隙水中的分布规律为东低西高,然而在沉积物中则与此正好相反。氮、磷、铁主要补给源有河流输入、工业生活污染排放、海洋生物自身分解以及孔隙水的释放。影响氮、磷、铁分布的主要因素为物源、河流输入及水动力条件,同时受到沉积物粒度的制约。相关分析显示,溶解氧、有机碳、铁对水体中磷及氮的分布具有某种制约作用。  相似文献   

14.
《Marine Chemistry》2001,73(3-4):215-231
In-situ benthic flux studies were conducted at three stations in Upper Galveston Bay twice during March 1996 to directly measure release rates of dissolved Mn, Fe, Ni and Zn from the sediments. Results showed reproducible increases with time in both replicate light and light–dark benthic chambers, resulting in average fluxes of −1200±780, −17±12, −1.6±0.6 and −2.4±0.79 μmol m−2 day−1 for Mn, Fe, Ni and Zn, respectively. Sediment cores collected during 1994–1996 showed that surficial pore water concentrations were elevated compared to overlying water column concentrations, suggesting diffusive release from the sediments. Diffusive flux estimates of Mn and Zn agreed in direction with chamber fluxes measured on the same date, but only accounted for 5–38% of the measured flux. Diffusive fluxes of Fe agreed with measured fluxes at the near Trinity River station but overestimated actual release in the mid and outer Trinity Bay regions, possibly due to inaccurate determination of the Fe pore water gradients or rapid oxidation processes in the overlying water at these stations.In general, measured fluxes of Mn and Ni were higher in the mid Trinity Bay region and suggested a mechanism for the elevated trace metal concentrations previously reported for this region of Galveston Bay. However, the fluxes of Fe were highest in close proximity to the Trinity River, supporting the elevated Fe concentrations measured in this region during this and other studies, and decreased towards middle and outer Trinity Bay. Trace metal turnover times were between 0.1 and 1.2 days for Mn, between 1.3 and 4.6 days for Fe, and between 27 and 100 days for Ni and 12–20 days Zn, and were considerably shorter than the average Trinity Bay water residence time (1.5 years) for this period. Comparing area averaged benthic inputs to Trinity River inputs shows the sediments to be a significant source of trace metals to Galveston Bay. However, while benthic inputs of trace metals were measured, water column concentrations remained low despite rapid turnover times for Mn and Fe, suggesting removal of these metals from the water column after release from the sediments.  相似文献   

15.
为了定性定量提供大蚝养殖区环境健康状况咨询,使用联合评价法对钦州湾大蚝养殖育苗区、育肥区、育成区环境健康状况进行评价。结果表明:①钦州湾养殖育成区、育肥区、育苗区的综合评价值为0.62、0.75、1.03,对应环境健康状况分别为良好、良好、不合格。健康状况呈现出由东南外湾的育成区向西北内湾的育苗区方向递减趋势,各养殖海区环境健康状况优先次序为:育成区、育肥区、育苗区。②制约钦州湾养殖区环境健康状况既有共性制约因素石油类,其环境健康状况均为不合格;也有特性制约因子COD、活性磷酸盐。其中,育苗区内COD单因素评价指标值变化范围1.34~2.21,对应健康状况为差,海域大多位于海湾内、外湾交界处以及河海口交汇处,而处于外湾的育肥区、育成区则处于海湾开阔的海域受到COD影响则较小。育肥区内活性磷酸盐单因素评价指标值对应健康状况也存在不合格和差的情况。  相似文献   

16.
海水碳酸盐体系参数是反映碳循环调控机理和季节性酸化过程的重要海水化学参数.本文根据2011年3月、7月、11月和12月4个不同季节航次获取的长江口海域海水碳酸盐体系参数,探讨了长江口-东海P断面溶解无机碳(DIC)和总碱度(T A)的空间分布特征及其影响因素.结果表明:内陆架区,DIC和T A的平均值均表现为:夏季<秋季<冬季<春季;垂直分布上,夏季和秋季受长江冲淡水影响出现层化现象,春季和冬季均垂直混合较均匀.东海内陆架DIC与温度和DO呈显著负相关;T A则受温度和DO变化影响较小,与盐度呈正相关.结合2011年东海外陆架的PN断面数据分析,DIC和pH分别与表观耗氧量(AOU)呈显著正相关和负相关,东海外陆架的pH/AOU的斜率为-0.0027 pH/(μmol·kg-1);而内陆架区的pH/AOU的斜率为-0.0018 pH/(μmol·kg-1),低于黑潮次表层水中pH/AOU的斜率.东海内陆架区由于存在季节性的通风作用以及较强的海水碳酸盐体系缓冲能力,底层水体中因有机质耗氧降解导致的季节性酸化信号在一定程度上得到了缓解.  相似文献   

17.
Abstract. A two year benthic sampling program of a 2000 km2 area, covering 22 stations, showed a dominance of deposit-feeding polychaetes. The quantitative structure of the three infaunal assemblages was related to a salinity gradient: the inner and outer regions were inhabited by, respectively, mixohaline and euhaline associations, both quantitatively related to granulometric facies of sediment. Species diversity was very low in the inner region, although abundance of opportunistic species was high. In the outer region, abundance and diversity were more stable, with an increasing number of species. A comparison of species number and abundance with Species-Abundance-Biomass curves from enriched environments showed that the inner region of Bianca Bay may be considered as an organically enriched environment. Scoloplos, a species associated with organic enrichment, and dense terebellid belts were present in great abundances in front of sewage outflows. The spatial distribution of heterotrophic bacteria and the bivalves Corbula and Nucula also followed this pattern.  相似文献   

18.
Nutrients, chlorophyll a, primary production (14C), and standard oceanographic parameters were measured seasonally from 1983 to 1988 along the axis of a karstic estuary of the central Adriatic Sea (the Krka River estuary). Because of anthropogenic phosphorus discharges, the surface-layer orthophosphate concentrations (up to 1.7 mmol m−3), phytoplankton biomass (chlorophyll a up to 23 mg m−3) and primary production (up to 108 mg C m−3 h−1) were significantly higher in ibenik Bay (lower estuary) than in the other estuarine subregions, and the coastal sea in particular. In contrast, nitrate and orthosilicate (up to 59 and 65 mmol m−3, respectively) distributions during autumn and winter were ascribed to dilution of Krka River nutrients along the estuary. As a consequence, the surface-layer inorganic N/P ratio was extremely high in the upper estuary (averages up to 180), but this ratio was reduced up to three times in ibenik Bay and the coastal sea. In spring and summer, nitrate and orthosilicate, but not orthophosphate, were almost exhausted from the water because of biological utilization. In the saline layer below the halocline (depth 2–5 m) oxygen saturation varied over a large range, particularly in the upper estuary (16–176%), and nutrient concentration ratios differed from those in the surface layer. A nutrient regeneration stoichiometric model was derived, based on a linear regression analysis: AOU:Si:N:P = 276:16:6:0.4. Anthropogenic nutrient inputs should be urgently reduced to re-establish a natural nutrient environment.  相似文献   

19.
山东半岛南部近岸海域富营养化状况的多元评价研究   总被引:8,自引:0,他引:8  
周斌  王悠  王进河  刘泳  唐学玺 《海洋学报》2010,32(2):128-138
于2006年至2007年分四个季度月对山东半岛南部近岸海域(35.5°~36.7°N,119.8°~121.3°E)的营养盐和叶绿素a进行了设站调查,分析了该海域上述因子时空分布特征,同时应用主成分分析(PCA)和潜在富营养化评价方法对该海域的富营养化状况进行了分析,初步确定了影响该海域富营养化状况的主要驱动因子。结果表明:(1)在时间分布上,总氮、总磷、活性磷酸盐、溶解态氮与总无机氮和活性硅酸盐的季节变化类似,均表现出秋冬季浓度较高而春夏季较低的趋势,而总磷、溶解态磷的浓度则在冬季最高,在夏秋季较低,叶绿素a浓度的季节变化趋势为春夏季较高,而冬季最低;该海域营养盐与叶绿素a浓度空间分布以胶州湾和丁字湾为中心,总体呈现出由近岸向离岸海域逐渐递减的趋势;(2)应用主成分分析对调查结果进行分析,结果显示10项调查指标(营养盐与叶绿素a)可以转换提取4个主成分,解释82.00%的结果。主成分综合得分可以作为富营养化程度的评价指标,据此得到调查海域富营养化状况的季节变化趋势由高到低依次为秋季、冬季、春季、夏季,总体呈现出以胶州湾和丁字湾为中心,沿岸及北部海域富营养化程度较高的格局;分析结果还表明总无机氮是该海区富营养化形成的主要驱动因子;(3)利用潜在富营养化评价方法对调查海域富营养化状况进行了初步分析,结果表明该海区仅于秋季表现为总体中度营养,在其他季节总体趋势均为贫营养,胶州湾与丁字湾附近海域在春秋季表现为磷限制潜在富营养化。主成分分析法较潜在富营养化评价方法更敏感,不仅能够定量表述海区富营养化状况,而且能够有效确定富营养化驱动因子。  相似文献   

20.
广东流沙湾4个测站2个周日潮流观测的准调和分析   总被引:2,自引:0,他引:2  
采用短期资料的潮流准调和分析方法,对水深为4.4~17.0 m的流沙湾4个测站2个周日潮流观测获得的表、中、底层的潮流资料进行了分析,分别计算了4个测站O1、K1、M2、S2、M4、MS4共6个主要分潮的潮流调和常数,并给出了各观测站位在各层的潮流椭圆要素.计算结果表明:流沙湾主要为日潮流海区,其中湾外为规则日潮流,湾内为不规则日潮流;湾外主要分潮流的北分量一般大于东分量,而湾内主要分潮流的北分量一般小于东分量.观测期间余流的流向主要呈西北向,最大余流流速出现在湾内地形突然收窄处,且在湾内中层余流流速要大于表、底层余流流速.整个海区潮流的可能最大流速表层在57~107 cm/s之间,中层在53~106 cm/s之间,底层在34~98 cm/s之间.流沙湾湾外潮流主要为顺时针的旋转流运动,湾内为带有旋转流的往复流运动.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号