首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献，搜索用时 109 毫秒
1.
The source and significance of three nutrients – nitrogen, phosphorous and silicon – were investigated by a modified dilution method performed on seawater samples from the Central Yellow Sea (CYS), in spring blooming period of 2007. This modified dilution method accounted for the phytoplankton growth rate, microzooplankton grazing mortality rate, the internal and external nutrient pools, as well as nutrients supplied through remineralization by microzooplankton grazing. The results indicate that phytoplankton growth during the bloom is mostly contributed by internal nutrient pools (KI=0.062–1.730). The external nutrient pools (KE=<0–0.362) are also of importance for phytoplankton growth during the bloom at some sampling sites. Furthermore, the contribution of the recycled-nutrient pool by remineralization (KR=<0–0.751) is significant when microzooplankton grazing rate was higher than 0.5 d−1 during the spring phytoplankton blooms in the Central Yellow Sea. Compared with internal phosphorus, internal nitrogen and silicon contribute more to the phytoplankton production at most sampling stations.  相似文献   

2.
2010-2011年胶州湾叶绿素a与环境因子的时空变化特征   总被引：2，自引：1，他引：1  
王玉珏  刘哲  张永  汪岷  刘东艳 《海洋学报》2015,37(4):103-116
2010年4、6、8、10月和2011年1、3月在胶州湾开展了6个航次的综合调查,研究了表层海水温度、盐度、营养盐和叶绿素a浓度的时空变化特征。调查期间,总无机氮(DIN)、磷酸盐(PO4)和硅酸盐(SiO3)多呈现东北部湾边缘高,而湾内和湾口低的空间分布特征。季节变化表明,DIN和PO4主要受养殖排放、河流径流输入和浮游植物生长消耗的影响,呈现初夏和秋季高,夏末和冬季低的特点;而SiO3主要受河流径流输入和浮游植物消耗的影响,呈现夏、秋高,而冬、春低的特点。营养盐浓度和结构分析表明,胶州湾存在PO4和SiO3的绝对和相对限制;SiO3限制尤其严重,是控制胶州湾浮游植物生长的主要环境因子。SiO3和PO4的限制主要表现在冬季,几乎遍布整个海湾;夏季降水可有效缓解海域的SiO3限制。叶绿素a浓度呈现春、夏季高,秋、冬季低的季节分布,温度、营养盐浓度与结构和季节性贝类养殖活动是控制胶州湾叶绿素a浓度时空分布的关键因素。  相似文献   

3.
据2016年胶州湾水质自动监测的数据结果,分析了水质变化趋势,并统计和评价其水质超标情况。结果表明:2016-04—11水质自动站海域溶解氧质量浓度和pH的日均值均达到二类海水水质标准,达标率为100%;活性磷酸盐年均值为0.023 mg/L,无机氮年均值为0.154 mg/L,以硝酸盐为主(64.9%);无机氮和活性磷酸盐超标率均为16.7%,而且集中在降雨量较大的8月、9月,营养盐指标超标基本与海泊河的淡水输入有关;叶绿素a质量浓度与溶解氧、pH和浊度呈显著正相关,浮游植物光合作用对该海域表层海水的水质参数影响较大;自动站监测和人工监测的营养盐在年际变化上呈现较一致的趋势,说明运用水质自动站监测该海域的营养盐变化趋势较为准确。  相似文献   

4.
This investigation focused on the weaker and less well understood of the two Arabian Sea monsoonal wind phases, the NE Monsoon, which persists for 3–4 months in the October to February period. Historically, this period has been characterized as a time of very low nutrient availability and low biological production. As part of the US JGOFS Arabian Sea Process Study, 17 stations were sampled on a cruise in January 1995 (late NE Monsoon) and, 15 stations were sampled on a cruise in November 1995 (early NE Monsoon). Only the southern most stations (10° and 12°N) and one shallow coastal station were as nutrient-depleted as had been expected from the few relevant prior studies in this region. Experiments were conducted to ascertain the relative importance of different nitrogenous nutrients and the sufficiency of local regeneration processes in supplying nitrogenous nutrients utilized in primary production. Except for the southern oligotrophic stations, the euphotic zone concentrations of NO3− were typically 5–10-fold greater than those of NO2− and NH4+. There was considerable variation (20–40-fold) in nutrient concentration both within and between the two sections on each cruise. All nitrogenous nutrients were more abundant (2–4-fold) later in the NE Monsoon. Strong vertical gradients in euphotic zone NH4+ concentration, with higher concentrations at depth, were common. This was in contrast to the nearly uniform euphotic zone concentrations for both NO3− and NO2−. Half-saturation constants for uptake were higher for NO3− (1.7 μmol kg−1 (s.d.=0.88, n=8)) than for NH4+ (0.47 μmol kg−1 (s.d.=0.33, n=5)). Evidence for the suppressing effect of NH4+ on NO3− uptake was widespread, although not as severe as has been noted for some other regions. Both the degree of sensitivity of NO3− uptake to NH4+ concentration and the half-saturation constant for NO3− uptake were correlated with ambient NO3− concentration. The combined effect of high affinity for low concentrations of NH4+ and the effect of NH4+ concentration on NO3− uptake resulted in similarly low f-ratios, 0.15 (s.d.=0.07, n=15) and 0.13 (s.d.=0.08, n=17), for early and late observations in the NE Monsoon, respectively. Stations with high f-ratios had the lowest euphotic zone NH4+ concentrations, and these stations were either very near shore or far from shore in the most oligotrophic waters. At several stations, particularly early in the NE Monsoon, the utilization rates for NO2− were equal to or greater than 50% the utilization rates for NO3−. When converted with a Redfield C : N value of 6.7, the total N uptake rates measured in this study were commensurate with measurements of C productivity. While nutrient concentrations at some stations approached levels low enough to limit phytoplankton growth, light was shown to be very important in regulating N uptake at all stations in this study. Diel periodicity was observed for uptake of all nitrogenous nutrients at all stations. The amplitude of this periodicity was positively correlated with nutrient concentration. The strongest of these relationships occurred with NO3−. Ammonium concentration strongly influenced the vertical profiles for NO3− uptake as well as for NH4+ uptake. Both NO2− and NH4+ were regenerated within the euphotic zone at rates comparable to rates of uptake of these nutrients, and thus maintenance of mixed layer concentrations did not require diffusive or advective fluxes from other sources. Observed turnover times for NH4+ were typically less than one day. Rapid turnover and the strong light regulation of NH4+ uptake allowed the development and maintenance of vertical structure in NH4+ concentration within the euphotic zone. In spite of the strong positive effect of light on NO2− uptake and its strong negative effect on NO2− production, the combined effects of much longer turnover times for this nutrient and mixed layer dynamics resulted in nearly uniform NO2− concentrations within the euphotic zone. Responses of the NE Monsoon planktonic community to light and nutrients, in conjunction with mixed layer dynamics, allowed for efficient recycling of N within the mixed layer. As the NE Monsoon evolved and the mixed layer deepened convectively, NO2− and NO3− concentrations increased correspondingly with the entrainment of deeper water. Planktonic N productivity increased 2-fold, but without a significant change the new vs. recycled N proportionality. Consequently, NO3− turnover time increased from about 1 month to greater than 3 months. This reflected the overriding importance of recycling processes in supplying nitrogenous nutrients for primary production throughout the duration of the NE Monsoon. As a result, NO3− supplied to the euphotic zone during the NE Monsoon is, for the most part, conserved for utilization during the subsequent intermonsoon period.  相似文献   

5.
Time series changes in sea surface temperature (SST), chlorophyll a (Chl a), nutrients (PO4, NO3), and sea winds, which correlated with the passage of Typhoon Shanshan in the East/Japan Sea (EJS), are illustrated using satellite data for Chl a, SST, sea winds, and in situ data for nutrients and water temperature. The sea-surface cooling (SSC) effect by the passage of the typhoon was higher at stations nearer to the center compared to stations further from the center. The SSC effect at stations in the colder water region (on the left side of the typhoon’s track) was higher than at stations in the Tsushima Warm Current region (on the right side of the typhoon). The SSC effect continued for approximately 10 days after the passage of the typhoon. The Chl a concentration at all stations increased after the passage of the typhoon. This increase continued for a period of approximately 10 days, but the duration period at each station varied with distance from the typhoon center. Changes in Chl concentrations at stations within a 2° distance on both sides from the typhoon’s center were higher than that at other stations. The changes in Chl a by the passage of the typhoon were measured at approximately 0.3–1.0 mg/m3 along the moving path of the typhoon. Phosphate and nitrate changes were inversely correlated with the water temperature changes; the nutrient concentration increased with the passage of the typhoon. Like the changes in SST, changes in nutrient concentrations on the left side of the typhoon’s track were higher compared to those at the center and the right side.  相似文献   

6.
This study aimed to assess the contribution of different salt marsh halophytes (Spartina maritima, Scirpus maritimus, Halimione portulacoides, Sarcocornia fruticosa, and Sarcocornia perennis) to nutrient cycling and sequestration in warm-temperate salt marshes. Carbon, nitrogen and phosphorus concentration in plant organs and rhizosediment, as well as plant biomass were monitored every two months during one year. Results show that the C retained in the rhizosediment does not seem to be species or site specific. However, some halophytes seem to have a higher contribution to retain C from external sources, namely S. perennis and S. maritima. Regarding N, halophytes colonizing the upper and middle marsh areas had the highest NBPP (net belowground primary production) as well as the retention of N in the rhizosediment. Yet, excluding S. maritimus, all halophytes seem to contribute to the retention of N from external sources. The P retained in the rhizosediment does not seem to be species or site specific. Still, only S. maritima colonizing the lower marsh areas, which also had comparatively lower NBPP, seem to have a higher contribution to retain P from external sources. Additionally, it seems that there is no relation between plants sequestration capacity for nutrients and plant photosynthetic pathway. This work shows that nutrient cycling and accumulation processes by salt marsh halophytes contribute to reduce eutrophication (N and P retention) and also to reduce atmospheric CO2 (C retention), highlighting salt marsh ecosystems services and the crucial role of halophytes in maintaining ecosystem functions and health.  相似文献   

7.
An algorithm is presented for estimating near-surface SPM concentrations in the turbid Case 2 waters of the southern North Sea. The single band algorithm, named POWERS, was derived by parameterising Gordon's approximation of the radiative transfer model with measurements of Belgian and Dutch inherent optical properties. The algorithm was used to calculate near-surface SPM concentration from 491 SeaWiFS datasets for 2001. It was shown to be a robust algorithm for estimating SPM in the southern North Sea. Regression of annual geometric mean SPM concentration derived from remote sensing (SPMrs), against in situ (SPMis) data from 19 Dutch monitoring stations was highly significant with an r2 of 0.87. Further comparison and statistical testing against independent datasets for 2000 confirmed the consistency of this relationship. Moreover, time series of SPMrs concentrations derived from the POWERS algorithm, were shown to follow the same temporal trends as individual SPMis data recorded during 2001. Composites of annual, winter and summer SPMrs for 2001 highlight the three dominant water masses in the southern North Sea, as well as their winter–fall and spring–summer variability. The results indicate that wind induced wave action and mixing cause high surface SPM signals in winter in regions where the water column becomes well mixed, whereas in summer stratification leads to a lower SPM surface signal. The presented algorithm gives accurate near-surface SPM concentrations and could easily be adapted for other water masses and seas.  相似文献   

8.
The δ13C of ΣCO2 along with dissolved oxygen and nutrients in seawater collected near the Luzon Strait were analyzed to provide new data regarding water exchange between the South China Sea and the Pacific. Sampling covered the area 20–22°N and 118–120°E in April, June, and October 1995. Three stations were repeated during these cruises. In addition, sections along 119° and 120°E near the entrance of Luzon Strait were constructed. The depth profiles of δ13C from the nine stations presented in this study are similar to those reported from the open ocean. Correlation with chemical parameters (apparent oxygen utilization and phosphate) aids in the interpretation of the δ13C data. An apparent shift of δ13C profiles between cruises but at the same site was observed and was concluded to be related not to the seasonal change, but to the presence of different water masses exhibiting distinct θ-S relationships.  相似文献   

9.
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   

10.
长江口及邻近海区营养盐结构与限制   总被引：5，自引：0，他引：5  
通过研究长江口及邻近海域溶解无机氮(DIN=NO3-+NO2-+NH4+)、磷酸盐(PO43-)、硅酸盐(SiO32-)所表征的营养盐区域结构特征及影响因素,在分析营养盐绝对限制情况的基础上,划分了潜在相对营养限制区域。结果表明,123°E以西近岸表层区域DIN/P比值全年均高于16,而Si/DIN除秋季外基本小于1,显示出长江冲淡水影响下"过量氮"的特征。春夏季河口锋面区(31°~32.5°N,122.5°~124°E)硅藻的大量生长可使DIN/P异常升高和Si/DIN异常降低。秋季研究区域北部DIN/P西低东高且Si/DIN西高东低是由于在高DIN、低PO43-的长江冲淡水影响下,近岸受相对低DIN、高SiO32-的苏北沿岸流南下入侵影响而被分割而成。冬季长江口门东北部存在的高DIN/P和低Si/DIN区则主要由于寡营养盐的黑潮水深入陆架,向东北输送的部分长江冲淡水和增强的苏北沿岸流共同作用造成DIN升高所致。利用Redfield比值进行了不同站位表层潜在相对营养限制情况的区分。近岸123°E以西受高DIN、SiO32-长江冲淡水影响,四季多呈现PO43-潜在相对限制,而在春夏季由于浮游植物的大量吸收PO43-,造成局部PO43-绝对限制及潜在相对限制。春夏季氮限(DIN潜在相对限制)一般发生在外海部分站位,但较为零散。秋季除了东南外海大部分站位外,受苏北沿岸流影响在长江口北部近岸也存在氮限。随着低DIN/P的黑潮表层水(KSW)的入侵加强,冬季外海氮限站位增多。硅限(SiO32-潜在相对限制)在夏季发生在赤潮高发区,而冬季南部存在较多硅限站位表明KSW中SiO32-相对较为缺乏。  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