基于浮游植物吸收光谱提取粒径参数

在南海北部、大亚湾及珠江口3个不同水体生物-光学数据的基础上, 研究了浮游植物粒径结构的变化特征, 建立了基于浮游植物吸收光谱提取的浮游植物粒径参数(S<f>)的混合光谱模型。南海海区不同的水体环境下浮游植物的粒级结构有着很大的差异: 在河口和沿岸水体小型浮游植物占优势, 在外海水体微微型浮游植物占优势。浮游植物粒径参数随小型浮游植物增多而减少, 随微微型浮游植物增多而增大。叶绿素a浓度从外海到沿岸逐渐增大, 浮游植物粒径参数随叶绿素a浓度的增大而减小, 它们之间呈幂函数关系。结果表明, 利用混合光谱模型得到的浮游植物粒径参数与南海海区不同水体的生物-光学特征(粒级结构Rpico和Rmicro、粒级指数SI、叶绿素a浓度)有一定的相关性。具体的相关性表示为: S<f>与粒级结构(Rpico和Rmicro)存在一定的关系, 与小型浮游植物和微微型浮游植物之间的线性相关系数分别是0.55和0.65; S<f>与浮游植物粒级指数(SI)有较好的线性关系, 相关系数是0.57; S<f>与叶绿素a浓度呈幂函数关系, 相关系数是0.64。这个混合光谱模型为从光学参数反演浮游植物种群的生态学信息提供了有效的手段, 同时又可用于分析浮游植物优势粒径结构对光学特性的影响。     

用多层感知器模型由吸收光谱反演浮游植物色素

浮游植物吸收光谱已逐渐成为高光谱水色遥感的可获取参量。文章采用了多层感知器模型, 由珠江口担杆群岛附近水体的浮游植物吸收光谱进行了色素浓度的反演, 感知器的输入量是浮游植物吸收光谱, 输出量分别对应叶绿素a、叶绿素b、叶绿素c、光保护类胡萝卜素和非光保护类胡萝卜素五大类主要色素的浓度。分析结果表明, 叶绿素a和叶绿素c估算结果的平均相对偏差比较低, 在测试数据集中两者的偏差分别为19.06%和15.90%; 光保护类胡萝卜素和非光保护类胡萝卜素的估算浓度的相对偏差比较高, 对于测试数据而言, 分别为37.62%和36.96%; 叶绿素b浓度在测试数据集中的估算相对偏差约为27.47%。五大类色素在测试数据集和训练数据集的估算偏差比较接近, 已训练好的多层感知器可用于担杆岛水体中色素信息的反演。同时, 此色素反演方法也为遥感监测水体浮游植物种群动态提供了重要的手段。     

基于南海北部海区浮游植物吸收光谱斜率变化的粒级结构反演

浮游植物的粒级结构是一个重要的生物参数。基于南海北部海区不同水体环境下测量的生物光学数据, 作者深入研究了粒级结构对浮游植物吸收光谱的影响。结果表明, 选择443和510nm波段计算得到的浮游植物光谱斜率S对粒级结构的变化具有较高的敏感性, 其随着小型浮游植物比例的增大呈不断增加的趋势。S与水体叶绿素a浓度、浮游植物吸收系数(aph(443))之间表现出明显的正相关特征。以40%为界对不同粒级浮游植物的优势进行定义, 发现在S与叶绿素a浓度、aph(443)的关系分布中小型(Micro)和微微型(Pico)浮游植物占据优势的水体表现出较为明显的分界, 叶绿素a浓度和aph(443)分别在0.70mg•m-3和0.05m-1附近, 相应的S在0.0004(m•nm)-1左右。基于实测数据建立的遥感反射率蓝绿波段比值与S之间的统计关系, 决定系数高达0.91, 为从水色遥感数据反演浮游植物粒级结构提供了重要手段。     

基于db7小波的活体浮游植物荧光识别分析技术研究

通过小波变换可对信号的不同频率成分进行分解,为弱信号特征提取提供了有效途径。通过db7小波对分属7个门32个属的43种浮游植物的三维荧光光谱进行分析,后经Bayes判别分析选择小波分解后的第三层尺度分量作为最佳荧光识别特征谱,并通过系统聚类法将最佳特征谱在不同的条件下聚类进而得到门、属上的标准谱库。基于此,运用多元线性回归辅以非负最小二乘法建立浮游植物三维荧光光谱识别技术。利用该技术对4128个单种浮游植物样品和636个混合浮游植物样品进行识别分析。单种浮游植物样品在属水平上的识别正确率为75%,门水平上的识别正确率为95%;浮游植物混合样品中的优势种在属水平上的识别正确率为83%,门水平上的识别正确率为91%。结果表明:该技术可以实现对浮游植物的快速准确识别。     

Determination of the chlorophyll-a concentration vertical profile by the spectra of incident solar radiation in the ocean

Methods of rapid analysis of the chlorophyll-a concentration vertical profile by the spectra of incident solar radiation are suggested. The methods are applicable for the ocean layerz=20–80 m containing waters of type 1 (by Morel's classification). Testing of the methods underin situ conditions showed that they can be used to reconstructC _ch(z) profiles, with a relative error of 10% and a root-meansquare error of 20–30% at most, provided the data are calibrated using field observations conducted at two or three sites in the test area.Translated by Vladimir A. Puchkin.     

Rare earth elements in seawater during an iron-induced phytoplankton bloom of the western subarctic Pacific (SEEDS-II)

During an iron-enrichment experiment in the western subarctic Pacific (SEEDS-II), concentrations of dissolved and acid-soluble rare earth elements (REEs) were determined in shallow waters. Detailed vertical profiles of dissolved REEs were compared with those of nutrients in a preliminary survey. The results showed good correlation, except for Ce and Y. Along with phytoplankton growth within the iron-enriched patch, dissolved REEs were decreased in surface waters. The changes in REE concentrations were small but systematic: light REEs were adsorbed preferentially over heavy REEs. This systematic trend is consistent with results of earlier studies of REE adsorption onto biogenic particle surfaces. However, we were unable to detect a decrease of acid-soluble REEs in surface waters. During the phytoplankton bloom decline phase, dissolved REEs were elevated to concentration levels at the preliminary survey, although nutrients were decreased. The liberation of REEs from the suspended particles might be related to disaggregation from large particles to colloid particles, desorption from the particulate phase, and remineralization from organic matter. Outside the Fe-patch, time variations of REEs were also observed during SEEDS-II, indicating that both artificially induced phytoplankton blooms and natural variation of biogenic particles can affect the biogeochemical cycles of REEs in shallow waters within a short time.     

绿藻浒苔对浮游植物群落结构影响研究

为了解浒苔(Enteromorpha prolifera)对浮游植物群落的影响,于2011年7月末在青岛第三海水浴场附近海域,现场采集了浒苔鲜组织和含自然浮游植物群落的海水,进行了10d 的浒苔与浮游植物群落室内受控共培养实验。设计4个处理,包括1个对照组和3个实验组,每个处理设置3个平行。对照组未添加浒苔,实验组分别按照0.8(低)、2.4(中)和7.2 g/L(高)的湿质量进行添加。研究结果表明,在整个共培养期间,硅藻的生长受到了浒苔明显的抑制,在3个不同的实验组细胞丰度显著降低(ANOVA, P<0.05),降幅分别达到84.1%、92.1%和95.3%。优势种长菱形藻(Nitzschia longissima)在高实验组的第10天,细胞丰度更是低至对照组的0.38%。甲藻丰度在各组皆表现出先升高后降低的趋势,优势种利玛原甲藻(Prorocentrum lima)在高实验组的第3天,细胞丰度高达对照组的98.7倍。浒苔通过影响浮游植物细胞丰度和优势种演替,改变了浮游植物的群落结构。高密度浒苔的存在会使浮游植物优势种组成趋于单一,物种多样性程度和群落稳定性大为降低。但是,浒苔对单细胞浮游植物的克生作用可以抑制赤潮藻的过度繁殖,有益于赤潮的生物防治和水域环境的生态修复。     

海水中矿物质颗粒吸收和散射特性Mie理论分析

利用Mie理论模型对不同粒径分布和复折射率的矿物质颗粒吸收和散射特性进行了模拟计算.颗粒的衰减和散射效率随着参数ρ的增大呈现出振幅依次减小的一系列有规则的振荡变化,而吸收效率则随着ρ的增加而增大;随着颗粒吸收性的增强,散射效率和吸收效率随着ρ的增大最终都将趋近极限值1.对于矿物质颗粒群,颗粒群的粒度分布变化对散射和后向散射特性影响很大,小粒径粒子对散射和后向散射的贡献比较大;折射率实部以及虚部变化对散射特性均有影响,颗粒的吸收性越强,则散射会相应地减弱;粒度分布以及折射率虚部对吸收系数也存在较大的影响,但是折射率实部对吸收系数的影响不大.     

A preliminary study of the variation of phytoplankton absorption coefficients in the northern South China Sea

The temporal and spatial variabilities of phytoplankton absorption coefficients (a ph (λ)) and their relationships with physical processes in the northern South China Sea were examined, based on in situ data collected from two cruise surveys during May 14 to 25, 2001 and November 2 to 21, 2002. Significant changes in the surface water in a ph values and B/R ratios (a ph (440)/a ph (675)) were observed in May, which were caused by a phytoplankton bloom on the inner shelf stimulated by a large river plume due...     

Light absorption by phytoplankton,non-algal particles and dissolved organic matter at the Patagonia shelf-break in spring and summer

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 (S_cdom), with means of 0.015 (spring) and 0.012 nm^?1 (summer). Nonetheless, the mean S_cdm 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 (S_f) 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.     

硅的间接跃迁双光子吸收系数谱

利用皮秒Nd:YAG脉冲激光器作为激发光源,测量出光子能量介于1.36 μm (0.912 eV)—1.80 μm (0.689 eV)之间的硅间接跃迁双光子吸收系数谱.尽管此波段范围内的激光光子能量小于硅间接带隙,但当激光辐照在硅基光电二极管受光面时,在二极管两电极端仍然探测到了显著的脉冲光伏信号.光伏信号峰值强度与入射光强呈二次幂函数关系,表明其是双光子吸收过程.采用pn结等效结电容充放电模型,将光伏响应信号峰值与入射光强相关联,从中提取出硅的间接跃迁双光子吸收系数,改变入射波长得到系数谱.研究表明:     

长江口外海水中有色溶解有机物（CDOM）的光吸收特性

基于2008年5、11月2次调查数据,研究了长江口邻近海域水体有色溶解有机物（CDOM）的光吸收特性及其时空分布特征,探讨了CDOM含量、光谱斜率Sg值及其与特征波长下吸收系数a（440）的关系.结果表明,春季该海域有色溶解有机物的吸收系数a（440）的范围为2.232~8.671 m-1,平均值为4.523 m-1;秋季其吸收系数a（440）的变化范围为0.390~6.135 m-1,平均值为2.209 m-1.该水体CDOM吸收曲线基本呈指数衰减趋势.在400~440 nm波段内,春季其光谱斜率Sg值范围为0.002 0~0.014 2 nm-1,平均值为0.008 7 nm-1秋季的介于0.020 8~0.052 6 nm-1之间.平均值为0.037 5 nm-1.同时有色溶解有机物吸收系数a（440）与Sg值存在着较显著的负相关关系.     

南海北部藻类粒级结构及色素成分对浮游植物吸收系数的影响

在珠江口、广东沿岸及南海北部三个航次生物-光学数据的基础上,研究了色素打包效应和色素成分的变化对浮游植物吸收系数的影响,结果表明,两种因素对吸收系数都有较大的贡献,但在不同的水体它们的影响程度各有不同.对网采浮游植物含量较高的珠江口和广东沿岸的水体而言,色素打包效应较强,对675 nm处比吸收系数的贡献平均分别为40%和20%;对微型浮游植物占主导地位的南海北部航次的水体,打包效应较弱,对675 nm处比吸收系数的影响平均仅为6%.采用多元线性回归的方法对吸收光谱进行分析,发现除叶绿素a之外的辅助色素对吸收系数的贡献主要表现在蓝绿光波段,三个航次440 nm波长处对总吸收的贡献平均分别为44%,43%和53%,其中对珠江口和广东沿岸航次的水体主要是光合类胡萝卜素的吸收贡献,而对南海北部航次的水体除了光合类胡萝卜素以外还要受到光保护类胡萝卜素的影响.由于河口、近岸和外海水体藻类粒级结构和辅助色素成分对浮游植物吸收系数的贡献有明显的差异,在南海北部水体建立比较精确的生物光学模型时,需考虑藻类粒级结构及色素成分对浮游植物吸收系数的影响.     

Chlorophyll-specific absorption coefficients and pigments of phytoplankton off Sanriku, northwestern North Pacific

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.     

大鹏湾海水环境要素与浮游植物增殖的灰色模型研究

通过浮游植物的增殖态势与理化因子的友关联比较,以空间理论数学为基础,按规范性、偶对称性、整体性、接近性和光滑离散函数等原则,并定义灰导数和灰微分方程,由此建立灰色动态模型,研究大鹏湾浮游植物增殖与海水环境要素间的关系结果表明,浮游动物、Fe、Mn和溶解氧对浮游植物增殖密度有比较重要的影响.