共查询到20条相似文献，搜索用时 346 毫秒
1.
根据2018年7月、11月和2019年1月、4月对广东考洲洋牡蛎养殖海域进行4个季节调查获得的pH、溶解无机碳(DIC)、水温、盐度、溶解氧(DO)及叶绿素a(Chla)等数据,估算该区域表层海水溶解无机碳体系各分量的浓度、初级生产力(PP)、表层海水CO2分压[p(CO2)]和海-气界面CO2交换通量(FCO2),分析牡蛎养殖活动对养殖区碳循环的影响。结果表明:牡蛎养殖区表层海水中Chla、DIC、HCO3–和PP显著低于非养殖区;养殖淡季表层海水中pH、DO、DIC、HCO3–、和CO32–显著大于养殖旺季,养殖旺季的p(CO2)和FCO2显著大于养殖淡季。牡蛎养殖区表层海水夏季、秋季、冬季和春季的海-气界面CO2交换通量FCO2平均值分别是(42.04±9.56)、(276.14±52.55)、(–11.59±18.15)和(–13.02±6.71)mmol/(m2·d),冬季各站位FCO2值离散度较大,其中位数是–10.73mmol/(m2·d)。在全年尺度,表层海水p(CO2)及FCO2与水温呈显著正相关,与盐度呈显著负相关。在非养殖区,浮游植物光合作用可能对影响表层海水p(CO2)及FCO2起主导作用。养殖牡蛎钙化、呼吸作用等生理因素释放的CO2对表层海水p(CO2)及FCO2未产生显著影响。考洲洋养殖海域养殖旺季为CO2的源,养殖淡季整体为CO2的弱汇。 相似文献
2.
为了评估海洋酸化和富营养化耦合作用对近海浮游生态环境的影响,本研究以天津市近岸海域浮游植物群落的生物地球化学指标为研究对象,分别采用一次性及连续培养的方式模拟自然水华及稳态条件,探究其对二氧化碳(CO2)和硝酸盐浓度变化及二者耦合作用的响应。实验条件设置如下:1)对照:二氧化碳分压p(CO2)40.53 Pa、无硝酸盐添加;2)酸化:p(CO2)101.3 Pa、无硝酸盐添加;3)加N:p(CO2)40.53 Pa、添加硝酸盐50 μmol·L–1;4)酸化加N:p(CO2)101.3 Pa、添加硝酸盐50 μmol·L–1。实验结果表明,硝酸盐加富比酸化更加显著地促进浮游植物群落总叶绿素(Chl a)生物量及颗粒有机碳(POC)和颗粒有机氮(PON)积累,酸化和加N使浮游植物群落粒径大小升高。连续培养实验表明,酸化和N加富对Chl a、生物硅(BSi)、PON浓度、PON与颗粒有机磷(POP)比值(N/P)、POC与BSi比值(C/BSi)及沉降速率有协同交互作用,对POP和POC浓度及POC与PON比值(C/N)有拮抗性交互作用。在一次性培养后,酸化显著降低了浮游植物群落的沉降速率;而在连续培养后,酸化和N加富使浮游植物群落沉降速率显著升高。这些结果表明酸化和N加富对与近岸浮游植物相关的生物地球化学循环及在不同生长阶段的种群碳沉降存在不同的潜在影响及交互效应。 相似文献
3.
4.
应用高效液相色谱结合二极管阵列检测器分析技术，研究了西太平洋雅浦Y3海山区域2014年冬季浮游植物的光合色素组成。结果表明：100m以浅，玉米黄素（Zeax）是水柱中浓度最高的光合色素，浓度为22.64—84.31ng/L，叶绿素a（chl a）浓度在水柱中均值为（37±34） ng/L，在贫营养海区的数值范围内，水柱积分高值分布区与海山走向一致，二乙烯基叶绿素a（Dvchl a）和19''-丁酰氧岩藻黄素（19''BF）也是调查海区较高浓度的色素，在水柱中均值分别为（27±22）和（31±30） ng/L。其他色素新黄素（Neox）、叶黄素（Lute）、叶绿素b（chl b）、青绿素（Pras）平均水柱含量极低（<1.00ng/L）。通过CHEMTAX程序因子分析估算了浮游植物群落结构，调查区浮游植物群落以原绿球藻为优势藻，贡献率与环境因子不具有相关性，其次主要为蓝细菌和金藻，蓝细菌贡献率高值区分布在海山东南和东北侧0和30m水层，金藻贡献率高值区分布在75和100m水层，两者贡献率均与环境因子显著相关。 相似文献
5.
随着经济社会快速发展, 中国湖泊表现出不同程度的富营养化, 湖泊生态正面临着严峻挑战。叶绿素a是评价水体营养状态的重要指标, 可以反映湖泊中浮游植物生物量情况。基于Landsat系列数据集, 对1986~2022年间中国范围内面积在10 km2以上湖泊叶绿素a浓度分布状况进行研究, 并对各区域叶绿素a浓度演变趋势进行分析, 结果表明: (1) 中国湖泊叶绿素a浓度存在地域性空间分布差异。叶绿素a浓度分布整体呈现东南高, 西北低的态势, 大约69%的湖泊处于轻富营养化程度, 中富营养化状态约占17%。以35°N和100°E为分界线, 各区域叶绿素a浓度随经纬度呈现出一定的变化规律。(2) 近40年间中国湖泊叶绿素a浓度年均值处于缓慢波动上升趋势, 时间序列呈现先降低后升高, 再降低的变化状态。所有湖泊叶绿素a浓度显著上升的数量占比约为30%, 显著下降的占比约为24.8%, 变化不显著的约占45.2%。整体变化较为稳定, 变异系数处于中等波动水平以下, 波动较大的区域位于青藏高原, 东北地区和长江中下游的部分地区。(3) 各流域内湖泊叶绿素a浓度时空分异特征表现为: 空间分布上, 内陆流域和西南流域普遍较低, 珠江流域和东南流域较高。时间变化上, 除了西南流域和内陆流域的湖泊叶绿素a浓度呈现下降趋势外, 其他流域均为上升趋势。中国湖泊叶绿素a浓度呈现出明显的地域性差异和时间变化趋势, 这主要归因于地区气候、水文条件、土地利用以及人类活动变化等因素。受温暖湿润气候和较强人类活动的影响, 东南部地区的湖泊叶绿素a浓度相对较高。西北部地区气温偏低, 降水较少, 湖泊叶绿素a浓度普遍较低。近40年的时间尺度上, 受城市化、工业化快速发展和全球气候变化的共同影响, 中国整体湖泊叶绿素a浓度呈缓慢上升趋势。 相似文献
6.
2008年夏季西北冰洋表层水浮游植物群落结构的色素表征及其对不同水团的响应 总被引：1，自引：0，他引：1
本文依托2008年夏季中国第三次北极科学考察航次,对西北冰洋海盆区和楚科奇海陆架营养盐及光合色素进行了测定和分析。根据海水理化性质将研究海区分为5个区,并使用CHEMTAX软件（Mackery et al.,1996）讨论了西北冰洋不同海区浮游植物群落组成结构及其与环境因子之间的关系。结果显示在楚科奇海陆架区,太平洋入流显著影响浮游植物生物量和群落结构。高营养盐Anadyr水团以及白令陆架水控制海域,表现出高Chl a且浮游植物以硅藻为主,相反,低营养盐如阿拉斯加沿岸流控制海域,Chl a生物量低且以微型,微微型浮游植物为主。在外陆架海区,海冰覆盖情况影响着水团的物理特征及营养盐浓度水平,相应地显著影响浮游植物群落结构。在海冰覆盖区域,硅藻生物量站到总Chl a生物量的75%以上;在靠近门捷列夫深海平原海区,受相对高盐的冰融水影响（MW-HS）,营养盐浓度和Chl a浓度相对海冰覆盖区略高,浮游植物结构中微型、微微型藻类比重增加,硅藻比例则降至33%;南加拿大海盆无冰海区（IfB）,表层水盐度最淡,营养盐浓度最低,相应地显示出低Chl a生物量,表明海冰消退,开阔大洋持续时间延长,将导致低生物量及激发更小型浮游植物的生长,并不有利于有机碳向深海的有效输出。 相似文献
7.
为检验辐射传输方程改进算法推广用于反演LandSAT8 海表温度(SST)的可行性及适用条件,本研究在修订算法部分参数的基础上,分别反演出算法改进前后的LandSAT8 SST并进行比较。MODIS SST验证表明改进算法对大气透过率偏差和SST偏差均有明显改善,除2019-08-21图像外,其他3景图像SST偏差在0.5℃左右;浮标SST验证表明改进算法在近岸海域对SST偏差改善效果同样显著,其平均偏差bias和均方根误差rmse分别减少到0.14、0.18℃,基本可以忽略不计;进一步研究发现,改进算法SST反演精度与研究海域大气透过率分布均匀程度呈显著的正相关关系,R2[bias(SST)]=0.920 7,R2[rmse(SST)]=0.934 0。使用改进算法遥感监测电厂温排水：嵩屿电厂表层海水温升羽流不明显;而后石电厂表层温升现象最显著,温升幅度和扩散影响范围最大,在其排水口附近存在稳定的高温水体(温升＞3℃);晋江电厂表层温升羽流呈扇形分布,流轴短,主要集中在排水口附近。 相似文献
8.
甘油二烷基甘油四醚(glycerol dialkyl glycerol tetraethers, GDGTs)作为一种重要的膜脂化合物, 广泛存在于海洋水体和沉积物中。基于GDGTs对温度的敏感性, TEX86(TetraEther indeX of tetraethers consisting of 86 carbons)指标被广泛用于海洋古温度重建。然而, 研究表明GDGTs母源生物古菌也会受到环境中溶解氧(DO)变化的影响, 进而影响其膜脂组成, 但边缘海DO对GDGTs组成的影响仍不清楚。本文研究了夏季长江口及其邻近海域颗粒物与表层沉积物中GDGTs的含量与组成, 探讨了表层沉积物中GDGTs的来源及其组成对底层DO的响应。结果表明, 长江口及其邻近海域颗粒物GDGTs的含量随水深的增加而增加, 同时表层沉积物中的GDGT-2/GDGT-3和GDGT-0/Cren比值均与底层颗粒物相近, 表明沉积物中GDGTs主要来源于底层颗粒物的沉降输入。进一步对受陆源有机质输入影响较小的站位研究发现[有机质来源BIT(Branched and Isoprenoid Tetractter)指标<0.2]研究发现, 随着底层DO的降低, 表层沉积物中GDGT-0/Cren比值与底层DO具有较好的正相关性(R2=0.57,P<0.01), 提示GDGT-0/Cren具有指示夏季长江口及邻近海域底层DO变化的潜力。未来还需结合颗粒物与表层沉积物中古菌生物群落和完整极性GDGTs的分析, 进一步阐明GDGTs指示DO的机制及适用性。 相似文献
9.
从上行控制角度,通过野外采样和围隔培养实验,研究了水母的代谢及分解过程对水体环境中pH、溶解氧、营养盐组成的影响,以及该过程中浮游植物的变化。实验结果表明,沙海蜇在代谢过程中短时间内会大量消耗水体中的溶解氧（dissolved oxygen,DO）,使水体出现低氧和轻度酸化。代谢过程释放出大量营养盐,使水体中的溶解无机氮（dissolved inorganic nitrogen,DIN）浓度在24h内增加为原来的12倍,溶解无机磷（dissolved inorganic phosphorus,DIP）浓度增加了40多倍,进而引起水体中叶绿素a（chlorophyll a,chl a）浓度的增加。沙海蜇的分解过程使水体表现出明显的低氧（缺氧）和酸化现象。沙海蜇生物量越大,分解时间越长,对水体的改变程度越明显,此外,还释放出大量的营养盐并改变原有的营养盐结构,可以刺激甲藻和绿藻的生长,甚至可能引发藻华。 相似文献
10.
本研究利用吸收光谱和荧光激发-发射矩阵光谱-平行因子分析(EEMs-PARAFAC),研究了养马岛附近海域海水中有色溶解有机质(CDOM)的浓度、组成、来源和生物可利用性,并估算了浮游植物生长繁殖对CDOM及具有生物可利用性CDOM的贡献。结果表明,表、底层海水中CDOM浓度(以吸收系数a350计)平均值分别为1.62±0.42 m-1和1.30±0.47 m-1,光谱斜率(S275-295)平均值分别为0.022±0.003 nm-1和0.023±0.003 nm-1。利用PARAFAC模型识别出4种荧光组分,分别为陆源类腐殖酸C1、类色氨酸C2、类酪氨酸C3和微生物源类腐殖酸C4。荧光指数(FIX)、腐殖化指数(HIX)和生物指数(BIX)显示,CDOM受陆源输入和海洋自生源的综合影响。降解实验结果显示,表、底层海水中生物可利用性CDOM百分比(%△a350)平均值分别为(23.36%±17.94%)和(8.93%±20.30%)。C1、C2和C4组分的荧光强度在培养之后降低,而C3组分的荧光强度上升。各荧光组分生物可利用性依次递减的顺序为:%△C1(23.75%±8.96%)＞%△C4(20.83%±11.71%)＞%△C2(11.67%±38.87%)＞%△C3(-29.61%±39.90%),显示培养之后CDOM的平均分子量和腐殖化程度降低。表层海水中a350、%△a350与Chl a之间存在显著线性相关关系,据此可以估算出浮游植物生长繁殖对CDOM的贡献为36.9%,对具有生物可利用性CDOM的贡献为85.0%。 相似文献
11.
Amábile Ferreira Virginia M.T. Garcia Carlos A.E. Garcia 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2162-2174
Satellite image studies and recent in situ sampling have identified conspicuous phytoplankton blooms during spring and summer along the Patagonia shelf-break front. The magnitudes and spectral characteristics of light absorption by total particulate matter (phytoplankton and detritus) and colored dissolved organic matter (CDOM) have been determined by spectrophotometry in that region for spring 2006 and late summer 2007 seasons. In spring, phytoplankton absorption was the dominant optical component of light absorption (60–85%), and CDOM showed variable and important contributions in summer (10–90%). However, there was a lack of correlation between phytoplankton biomass (chlorophyll-a concentration or [chl a]) and the non-algal compartment in both periods. A statistically significant difference was found between the two periods with respect to the CDOM spectral shape parameter (Scdom), with means of 0.015 (spring) and 0.012 nm?1 (summer). Nonetheless, the mean Scdm values, which describe the slope of detritus plus CDOM spectra, did not differ between the periods (average of 0.013 nm?1). Phytoplankton absorption values in this work showed deviations from mean parameterizations in previous studies, with respect to [chl a], as well as between the two study periods. In spring, despite the microplankton dominance, high specific absorption values and large dispersion were found (a*ph(440)=0.04±0.03 m2 mg [chl a]?1), which could be attributed to an important influence of photo-protector accessory pigments. In summer, deviations from general trends, with values of a*ph(440) even higher (0.09±0.02 m2 mg [chl a]?1), were due to the dominance of small cell sizes and also to accessory pigments. These results highlight the difficulty in deriving robust relationships between chlorophyll concentration and phytoplankton absorption coefficients regardless of the season period. The validity of a size parameter (Sf) derived from the absorption spectra has been demonstrated and was shown to describe the size structure of phytoplankton populations, independently of pigment concentration, with mean values of 0.41 in spring and 0.72 in summer. Our results emphasize the need for specific parameterization for the study region and seasonal sampling approach in order to model the inherent optical properties from water reflectance signatures. 相似文献
12.
Chlorophyll-specific absorption coefficients and pigments of phytoplankton off Sanriku, northwestern North Pacific 总被引：4，自引：0，他引：4
Koji Suzuki Motoaki Kishino Kousei Sasaoka Sei-Ichi Saitoh Toshiro Saino 《Journal of Oceanography》1998,54(5):517-526
The variety in shape and magnitude of thein vivo chlorophyll-specific absorption spectra of phytoplankton was investigated in relation to differences in pigment composition
off Sanriku, northwestern North Pacific. Site-to-site variations of the absorption coefficients,a
ph
* (λ), and pigment composition were clearly observed. At warm-streamer stations, higher values ofa
ph
* (440) anda
ph
* (650) were found with relatively high concentrations of chlorophyllb (a green algae marker). At stations located in the Oyashio water (cold streamer),a
ph
* (440) values were lower and fucoxanthin (a diatom marker) concentrations were higher, compared to the other stations. The
peak in the absorption spectra at the Oyashio stations was shifted toward shorter wavelengths, which was probably due to the
presence of phaeopigments. In a Kuroshio warm-core ring, the magnitude ofa
ph
* (440) was in between those at the warm-streamer and Oyashio stations, and the diagnostic pigment was peridinin (a dinoflagellate
marker). These findings indicated that major differences in phytoplankton absorption spectra of each water mass were a result
of differences in the phytoplankton pigment composition of each water mass, which was probably related to the phytoplankton
community. 相似文献
13.
Chlorophyll a concentrations (chla) and the absorption coefficients of total particulate matter [a
p()], phytoplankton [a
ph()], detritus [a
d()], and colored dissolved organic matter: CDOM [a
CDOM()] were measured in seawater samples collected in the subarctic North Pacific and the southern Bering Sea during the summer of 1997. We examined the specific spectral properties of absorption for each material, and compared the light fields in the Western subarctic Gyre (area WSG) with those in the Alaskan Gyre (area AG), and the southern Bering Sea (area SB). In the area WSG, the irradiance in the surface layer decreased markedly, indicating high absorption. In the area AG, the radiant energy penetrated deeply, and the chl a and absorption values were low throughout the water column. In the area SB, light absorption was high in the surface layer on the shelf edge and decreased with increasing depth; on the other hand, light absorption was low in the surface layer in the shelf area and increased with increasing depth. 相似文献
14.
Óscar A. Barocio-León Roberto Millán-Núñez Eduardo Santamaría-del-Ángel Adriana González-Silvera Charles C. Trees 《Journal of Oceanography》2006,62(6):873-885
We have estimated the spatial variability of phytoplankton specific absorption coefficients (a*
ph
) in the water column of the California Current System during November 2002, taking into account the variability in pigment
composition and phytoplankton community structure and size. Oligotrophic conditions (surface Chl < 0.2 mg m−3) dominated offshore, while mesotrophic conditions (surface Chl 0.2 to 2.0 mg m−3) where found inshore. The specific absorption coefficient at 440 [a*
ph
(440)] ranged from 0.025–0.281 m2mg−1 while at 675 nm [a*
ph
(675)] it varied between 0.014 and 0.087 m2mg−1. The implementation of a size index based on HPLC data showed the community structure was dominated by picoplankton. This
would reduce the package effect in the variability of a*
ph
(675). Normalized a
ph
curves were classified in two groups according to their shape, separating all spectra with peaks between 440 and 550 nm as
the second group. Most samples in the first group were from surface layers, while the second group were from the deep chlorophyll
maximum or deeper. Accessory photoprotective pigments (APP) tended to decrease with depth and accessory photosynthetic pigments
(APS) to increase, indicating the importance of photoprotective mechanisms in surface layers and adaptation to low light at
depth. Samples with higher ratios of APP:APS (>0.4) were considered as phytoplankton adapted to high irradiances, and lower
ratios (<0.26) as adapted to low irradiances. We found a good relationship between APP:APS and a*
ph
(440) for the deeper layer (DCM and below), but no clear evidence of the factors causing the variability of a*
ph
(440) in the upper layer. 相似文献
15.
C. Dupouy J. Neveux J.M. Andre 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)
Spectral absorption coefficients of total particulate material and detritus were measured throughout the euphotic zone along the equator between 165°E and 150°W and during time-series for each of these two longitudes in October 1994 (JGOFS-FLUPAC cruise). The sum of pigments obtained by spectrofluorometry (tChla=DV−chla+Chla) was used for normalization (and was also compared to fluorometric and HPLC measurements as an intercalibration study). In order to assess the specific absorption coefficient of photosynthetically active pigments (aps) from the pigment-specific absorption coefficient for phytoplankton (aph*), we made a multiple regression analysis of measured phytoplankton absorption spectra onto publishedin vivo spectra of pure pigments. This made it possible to calculate the concentrations of photoprotective carotenoids (tPPC) when HPLC measurements were not available and thus to subtract their contribution to absorption from the total phytoplanktonic absorption coefficient (aph). Methodological uncertainties in both coefficients used for calculating absorption coefficients and in pigment measurements are discussed. Pigments and absorption measurements made during the cruise enabled us to describe two typical trophic regimes in the equatorial Pacific ocean: oligotrophic waters of the ”warm pool“ west of 170°W and high-nutrient, low-chlorophyll waters (HNLC) of the upwelling east of 170°W. The vertical decreasing gradient of aph* from the surface to the deep chlorophyll maximum (DCM) was due to a high tPPC/tChla ratio at the surface and was higher in the oligotrophic (0.14-0.065 m2 mg (tChla)−1 biomass dominated byProchlorococcus, rich in zeaxanthin) than in the mesotrophic area (0.07-0.06 m2 mg (tChl a)-' biomass dominated by picoeucaryotes). Below the DCM,aph* reached a similar minimum value in both oligotrophic and mesotrophic areas.a*ps varied less than a*ph from the surface layer to the DCM in both oligotrophic and mesotrophic areas. The difference in a*ph and a*ps from west to east of the transect could be interpreted as a shift in the phytoplankton composition, with a dominance of procaryotes in the west and a dominance of eucaryotes in the upwelling area. Higher aps in well-lit typical oligotrophic waters indicated that phytoplankton communities dominated byProclorococcus might be more efficient for capturing light usable for photosynthesis than those present in the HNLC situation. 相似文献
16.
Hiroaki Sasaki Akihiko Tanaka Mitsunori Iwataki Yasuharu Touke Eko Siswanto Chun Knee Tan Joji Ishizaka 《Journal of Oceanography》2008,64(4):511-523
Remote sensing reflectance [R
rs(λ)] and absorption coefficients of red tides were measured in Isahaya Bay, southwestern Japan, to investigate differences in
the optical properties of red tide and non-red tide waters. We defined colored areas of the sea surface, visualized from shipboard,
as “red tides”. Peaks of the R
rs(λ) spectra of non-red tide waters were at 565 nm, while those of red tides shifted to longer wavelengths (589 nm). The spectral
shape of R
rs(λ) was close to that of the reciprocal of the total absorption coefficient [1/a(λ)], implying that the R
rs(λ) peak is determined by absorption. Absorption coefficients of phytoplankton [a
ph(λ)], non-pigment particles and colored dissolved organic matter increased with increasing chlorophyll a concentration (Chl a), and those coefficients were correlated with Chl a for both red tide and non-red tide waters. Using these relationships between absorption coefficients and Chl a, variation in the spectrum of 1/a(λ) as a function of Chl a was calculated. The peak of 1/a(λ) shifted to longer wavelengths with increasing Chl a. Furthermore, the relative contribution of a
ph(λ) to the total absorption in red tide water was significantly higher than in non-red tide water in the wavelength range 550–600
nm, including the peak. Our results show that the variation of a
ph(λ) with Chl a dominates the behavior of the R
rs(λ) peak, and utilization of R
rs(λ) peaks at 589 and 565 nm may be useful to discriminate between red tide and non-red tide waters by remote sensing. 相似文献
17.
We measured the absorption coefficients of suspended particles (ap(λ)) during three cruises from coastal waters to open ocean in the northern South China Sea (NSCS). The absorption contributions of phytoplankton (aph(λ)) and nonalgal particles (aNAP(λ)) were determined using the methanol extraction method. Based on the dataset of about 360 samples, we examined the spectral relationships of the particle absorption coefficients. The results show that ap(λ) spectra are well linearly correlated with ap(443) over the wavebands between 420–650 nm; aph(λ) could be well expressed as the second-order quadratic equations of aph(443) among the blue-green wavebands, and aNAP(λ) follows the general exponential function. Based on these spectral relationships, a model was proposed for partitioning the total particulate absorption coefficients into the contributions of phytoplankton and nonalgal particles using the nonlinear optimization method. The model was validated by comparing the computed results with in situ absorption coefficients. In some wavebands, such as 412 nm, 443 nm, 490 nm and 683 nm, we obtained good correlations with the percentage root mean square error (RMSE) values being controlled within 25% and the slopes being closer to 1.0. For samples from coastal waters, the discrepancy was a little large, which might be due to the higher absorption contributions from certain pheopigments. Overall, this model provides us much insight into phytoplankton absorption retrieval from in situ measurements and remote sensing ocean color data. 相似文献
18.
The proportions and variations of the light absorption coefficients of major ocean color components in the East China Sea 总被引：2，自引：2，他引：0
The East China Sea (ECS),one of the largest continental seas,has dynamic hydrology and complex optical characteristics that make ocean color remote-sensing retrieval difficult.The distributions and proportions of the light absorption coefficients of major ocean color components based on two large-scale investigations in the ECS are presented,showing these features in typical summer and winter seasons.The absorption coefficient a CDOM,a NAP and a phy of colored dissolved organic matter,non-algal particle,and pigment of phytoplankton show a decreasing trend from the coast to the outer shelf.According to the a CDOM distribution at 440 nm,the Changjiang River plume shows an abnormal southeastward transport.An extremely high a NAP value patch at 440 nm is present in the middle coast.The chlorophyll-a-specific phytoplankton pigment absorption (a phy) is much higher in winter than in summer,which may cause serious underestimated results when applying the averaged a phy into remote-sensing algorithms for chlorophyll concentration retrieval.The importance of phytoplankton size was evident in outer shelf waters.The absorption of a CDOM (440) is a dominant component accounting for over half of the total seawater absorption in summer.The a NAP (440) accounts for 64% of the absorption of the ECS coastal area in winter. 相似文献
19.
Specific absorption coefficient and phytoplankton community structure in the southern region of the California Current during January 2002 总被引：1，自引：0，他引：1
Measurements of the specific absorption coefficients of phytoplankton (a*ph) are currently required to estimate primary productivity at regional to global scales using satellite imagery. The variability in a*ph and phytoplankton size fraction was determined during January 2002 in the southern region of the California Current. Median values of a*ph at 440 nm and 674 nm were 0.061 and 0.028 m2 (mg Chl-a)?1 and significant variability was found between inshore and offshore stations. A decrease of a*ph is associated with increased phytoplankton abundance and larger species. The a*ph tends to be high when the photoprotector zeaxanthin is present in elevated concentrations and phytoplankton abundance lower. The nano-microphytoplankton (>5 µm) community consisted of 28 diatom and 15 dinoflagellate genera with mean abundance values of 2.8 and 1.6 × 103 cells l?1, respectively. The picophytoplankton (<5 µm) community consisted of Prochlorococcus sp. (mean 8.2 × 106 cells l?1) and Synechococcus sp. (mean 19.5 × 106 cells l?1), as well as a mixture of picoeukaryotes (mean 8.6 × 106 cells l?1). The contributions of nano-microphytoplankton and picophytoplankton to the total biomass (µg C l?1) were 46% and 54%, respectively. This study showed that picophytoplankton cells increased 2.5 times up during January 2002 compared with the previous year. It was concluded that the waning of La Niña conditions had a clear effect on the pelagic ecosystem in January 2002 and that the higher microphytoplankton abundance in the California Current was dominated by local and regional seasonal processes. 相似文献
20.
Jesús M. Mercado Teodoro Ramírez Dolores Corts Marta Sebastin Andreas Reul Begoa Bautista 《Estuarine, Coastal and Shelf Science》2006,69(3-4):459
The changes in the phytoplankton absorption properties during a diurnal cycle were investigated at one station located in the north-western area of the Alborán Sea. The experiment was performed in spring when the water column was strongly stratified. This hydrological situation permitted the establishment of a deep chlorophyll a (chl a) fluorescence maximum (DFM) which was located on average close to the lower limit of the mixed layer and the nutricline. The relative abundance of pico-phytoplankton (estimated as its contribution to the total chl a) was higher in the surface, however, micro-phytoplankton dominated the community at the DFM level. Chl a specific absorption coefficient (a*(λ)) also varied with optical depth, with a* (the spectrally average specific absorption coefficient) decreasing by 30% at the DFM depth with respect to the surface. A significant negative correlation between the contribution of the micro-phytoplankton to the total chl a and a* was obtained indicating that a* reduction was due to changes in the packaging effect. Below the euphotic layer, a* increased three-fold with respect to the DFM, which agrees with the expected accumulation of accessory pigments relative to chl a as an acclimation response to the low available irradiance. The most conspicuous change during the diurnal cycle was produced in the euphotic layer where the chl a concentration decreased significantly in the afternoon (from a mean concentration of 1.1 μg L−1 to 0.7 μg L−1) and increased at dusk when it averaged 1.4 μg L−1. In addition, a* and the blue-to-red absorption band ratio increased in the afternoon. These results suggest that a*(λ) diurnal variability was due to increase in photo-protective and accessory pigments relative to chl a. The variation ranges of a*(λ) at 675 and 440 nm (the absorption peaks in the red and blue spectral bands, respectively) in the euphotic layer were 0.01–0.04 and 0.02–0.10 m2 mg−1 chl a, respectively. Approximately 30% out of this variability can be attributed to the diurnal cycle. This factor should therefore be taken into account in refining primary production models based on phytoplankton light absorption. 相似文献