象山港水体的磷酸盐及其对赤潮的潜在影响

正近些年来,受人类活动的影响,过量的营养盐(主要是N、P)被输入到河口和近岸水体中,导致河口和近岸水体富营养化,藻类及其他浮游生物大量繁殖(赤潮)。藻类和这些生物死亡后,细菌会分解这些生物有机体,导致水体溶氧量下降,鱼类及其他生物由于缺氧而大量死亡。鉴于富营养化给水体环境带来的危害,水体富营养化已经成为全球关注的重大环境问题之一。磷酸盐作为主要的营养盐之一,认清其在河口及近     

曹妃甸近岸海域垂向悬沙含量遥感反演

利用遥感技术监测水体悬浮泥沙含量是海洋水色遥感的一个重要研究方向。本文以曹妃甸近岸海域4个剖面35个站点开展的现场光谱测量、同步采集的不同深度悬浮泥沙含量样品数据为基础,采用Landsat-5 TM遥感数据,建立水体表、中、底层悬沙含量遥感反演模型,并研究悬沙垂向上的空间分布规律。结果表明,曹妃甸近岸海域泥沙含量在垂向上有明显的相关性,以Landsat-5 TM影像反射率比值（R_TM3/R_TM2）为因子,构建优化的悬浮泥沙含量遥感反演模型,各层模型平均相对误差都在30%以内,表层和中层的平均绝对误差在6 mg/L以下,均方根误差小于10 mg/L,底层的精度略低于表层和中层。研究结果为进一步研究海洋环境泥沙运移规律、优化水动力作用下泥沙运移模型提供支持。     

陆表水体遥感监测研究进展

江河湖泊等陆表水体在工农业生产、气候调节、生态系统维持等方面扮演着至关重要的角色。在气候变化与人类活动的作用下,陆表水体的空间分布始终在发生着变化,因而对其进行快速精准的时空变化监测对水资源管理与保护、未来气候变化预测等有着重要的意义。遥感技术为大范围水体动态监测提供了全新的技术手段,特别是在当前地球大数据背景下,水体提取算法不断改进,遥感数据源急剧增加,但缺乏对算法和数据演化过程的系统整理。鉴于此,本文对现有水体提取算法与遥感数据进行了综合梳理,归纳了单波段阈值法、多波段谱间关系法、水体指数与阈值法、支持向量机、随机森林、深度学习等常用算法的演变,以及遥感数据源由低（MODIS等）到中（Landsat等）和高（高分1/2号等）空间分辨率的发展过程,并在此基础上讨论了各算法与数据源在水体变化研究中的差异。此外,本文论述了数据处理平台由本地计算到高性能云计算平台（如谷歌地球引擎）的发展,云计算促进地表水变化研究由基于时间片段到基于时间序列连续过程分析的转变,以及云计算在大尺度范围的应用。最后,本文还对多源遥感数据融合与云计算平台的结合在地表水体连续变化监测中的应用进行了展望,并对不同类型水体提取的不确定性进行了讨论。     

湛江港水体夏季后向散射特性

【目的】研究湛江港水体夏季后向散射特性。【方法】利用2017年夏季湛江港海域的航次数据,采用实验与对比分析的方法,研究湛江港海域水体的后向散射系数的光谱特性、空间分布,分析后向散射系数与悬浮泥沙浓度的关系。【结果】湛江港海域水体的后向散射系数的光谱模型符合乘幂的形式,波长指数(n)为1.61。后向散射系数的空间分布呈现近岸高值,外海低值的特点。后向散射系数与悬浮泥沙浓度存在良好的线性回归关系,决定系数(R2)为0.707 2。【结论】水体的后向散射系数可用于水体悬浮泥沙浓度的遥感反演。     

海面溢油光学卫星遥感监测能力分析

 海面溢油对海洋生态的影响具有频率高、范围广和危害大的特点。卫星遥感已成为海面溢油监测的重要手段。本文从海面油膜光谱特性出发,与常用的光学卫星传感器建立对应关系,根据对不同光学遥感卫星的空间分辨率、时间分辨率、幅宽和波段数等主要物理参数的对比分析认为,MODIS传感器和HJ-1卫星有较强的海面溢油监测能力。故此,采用MODIS、BJ-1、HJ-1和FY-3光学卫星影像,对2006年3月和2011年6月渤海海面溢油污染事故进行了遥感监测。MODIS遥感图像可以清晰反映出2006年和2011年这2次溢油污染事故中海面油膜信息,HJ-1卫星遥感影像则能反映出2011年溢油污染事故中海面油膜信息,而BJ-1和FY-3卫星遥感影像不能反映出海面油膜信息。HJ-1、BJ-1和FY-3卫星在波段设置上相似,但是,BJ-1和FY-3卫星不能反映出油膜信息,所以,本文进一步对这2次溢油事件中的MODIS遥感影像的油水光谱反差和海水光谱方差进行计算,并对结果进行比较分析,实验结果表明,当MODIS某一波段的海水光谱方差小于油水光谱反差时,则该波段可以显示出油膜信息;而当油水光谱反差小于或接近海水方差时,则不能反映出海面油膜信息。从波谱响应、空间分辨率和时间分辨率,以及监测实例中说明MODIS传感器有较强的海面溢油监测能力。     

斯里兰卡近海海洋生态环境变化遥感监测分析

斯里兰卡是海上丝绸之路沿线重要的节点国家,其周边海域生态环境变化与经济发展、休闲生活和食品安全密切相关。利用2002—2017年的MODIS遥感反演产品对斯里兰卡岛周边海域、关键节点港口科伦坡的生态环境参数年际变化规律分别进行分析和2003—2012年的MERIS遥感反射率产品对保克海峡进行水体类型时空分析,结论如下：① 研究区内光合作用有效辐射高值出现在马纳尔湾,海域沿岸浮游植物生物量相对较高,与海表温度负相关,外海浮游植物生物量极低,与透明度负相关。② 科伦坡港附近水温（海表温度）、海面光照强度（光合作用有效辐射）、水体清洁度（海水透明度）、海洋食物网基础的浮游植物生物量（叶绿素浓度）和浮游植物净初级生产力最大值分别出现在4月、3月、3月、8月、7月,致灾因素重点关注8月潜在的赤潮。③ 保克海峡浑浊带的源头是印度的卡里梅尔角,由高韦里河携带大量泥沙造成。这有助于了解和认识高时空变化的保克海峡及斯里兰卡周边海域在不同时间-空间的海洋生态环境。     

海南岛近岸海域COD时空变化及其富营养化贡献

【目的】研究海南岛近岸海域表层海水化学需氧量(COD)的时空分布特征,评价COD污染水平,研究区域COD浓度与多种环境因子之间的关系。【方法】根据2016年枯水季、丰水季和平水季海南岛近岸海域表层海水现场调查资料,进行单因子指数法和综合指数法分析。【结果】海南省近岸海域表层海水COD的平均质量浓度为(0.75±0.43) mg/L,浓度范围为0.14～2.74 mg/L;COD浓度高值区主要分布在龙尾河口临近小海海域,枯水季研究海域表层海水COD污染水平高于丰水季节;COD对富营养化的贡献范围为38.2%～69.7%,平均贡献率为(51.0±5.1)%,贡献率随着富营养化指数的增加而减小;3个季节COD与盐度均存在显著负相关(P<0.01)。【结论】COD时空分布主要受陆源输入和水动力过程的影响。COD是影响海南岛近岸海域富营养化的重要因子但非决定性因子。随着富营养化程度增加,来自营养盐对富营养化贡献更为显著。     

晚泥盆世大陆风化作用增强及其海洋环境效应:来自华南碳酸盐岩锶同位素的制约

上泥盆统弗拉斯阶和法门阶界线附近发生了大规模的生物灭绝, 其起因被认为是植物登陆导致的陆地化学风化作用加强及其引起的海洋水体缺氧所致, 但其直接证据还比较缺乏。运用广西地区广泛发育的浅海碳酸盐岩中锶元素(Sr)和同位素(87Sr/86Sr)、铀钍比值(U/Th)记录, 探究了从中泥盆统到下石炭统的陆地化学风化速率及海水氧化还原条件的变化。研究结果表明, 在晚泥盆世(法门阶早期)陆地化学风化作用加强, 导致海水中Sr浓度升高, 及更富集重的Sr同位素组分; 低的U/Th比值也显示该时期水体缺氧严重, 海水中U元素被还原到沉积物中, 导致海水中的U浓度降低。陆地表面化学风化的加强对晚泥盆世海洋水体氧化还原条件的波动以及海洋生物的灭绝有重要影响。      

MODIS红外水汽校正及其在InSAR大气改正中的应用

提出使用差分线性校正模型(DLCM)对MODIS红外波段大气水汽产品进行校正。利用在中国获取的两幅MODIS红外波段水汽产品进行分析后发现,在中国西部地区,受水汽参考值精度较差的影响,DLCM模型和传统线性校正(LS)方法均难以获得稳定、理想的校正结果;而在中国东部地区,DLCM模型可有效提高大气水汽的估计精度,且与LS方法相比,进行内符合精度评定时STD和RMS可以额外降低32.6%和15.7%,进行外符合精度评定时STD和RMS可额外降低32.3%和21.7%。此外,DLCM模型校正后的MODIS红外水汽产品在InSAR大气改正中的实验研究,亦证实了DLCM模型的有效性和将其用于InSAR大气改正的可行性。     

太湖水质参数MODIS的遥感定量提取方法

本文利用MODIS数据的可见光、近红外波段和准实时的地面采样数据,分别利用线性回归模型和神经网络模型反演了太湖的叶绿素a和悬浮物浓度.结果表明,利用MODIS数据的波段组合(M2/M8)和(M2/M9)可估算太湖的叶绿素a浓度;而MODIS数据的波段组合(M12/M17)、(M13/M17)及MODIS(M4)波段能定量估算太湖的悬浮物浓度,但估算精度仍不能满足实际需要.因此,构建了一个以MODIS可见光及近红外波段为输入,以太湖水质参数为输出的2层BP神经网络模型反演太湖的水质参数,大大提高了反演精度.     

RESEARCH ON RED TIDE OCCURRENCES USING ENCLOSED EXPERIMENTAL ECOSYSTEM IN WEST XIAMEN HARBOR, CHINA RELATIONSHIP BETWEEN NUTRIENTS AND RED TIDE OCCURRENCE

ＩＮＴＲＯＤＵＣＴＩＯＮＰｈｏｓｐｈｏｒｕｓｉｓａｋｅｙｎｕｔｒｉｔｉｖｅｅｌｅｍｅｎｔｆｏｒｔｈｅｇｒｏｗｔｈｏｆｍａｒｉｎｅｐｈｙｔｏｐｌａｎｋｔｏｎ .Ｒｅｃｅｎｔｌｙ ,ｂｅ ｃａｕｓｅｏｆｅｎｖｉｒｏｎｍｅｎｔａｌｐｏｌｌｕｔｉｏｎ ,ｔｈｅｅｕｔｒｏｐｈｉｃａｔｉｏｎｐｒｏｂｌｅｍｓｉｎｃｏａｓｔａｌａｎｄｏｃｅａｎｉｃｗａｔｅｒｓｈａｖｅｂｅ ｃｏｍｅｍｏｒｅａｎｄｍｏｒｅｓｅｒｉｏｕｓ.Ｔｈｅｅｎｖｉｒｏｎｍｅｎｔｅｃｏｌｏｇｉｃａｌｒｅｓｐｏｎｓｅｉｎｔｈｅｌｏｎｇ ｔｅｒｍｔｏｔｈｅｆ…     

STUDY OF RED TIDE PREDICTION MODEL FOR THE CHANGJIANG ESTUARY

ＩＮＴＲＯＤＵＣＴＩＯＮＡｑｕｉｃｕｌｔｕｒｅａｒｅａｒｅｄｔｉｄｅｓｉｇｎａｌｓｏｃｅａｎｐｏｌｌｕｔｉｏｎａｎｄｄｉｓａｓｔｅｒ.Ａｌｔｈｏｕｇｈｅｎｖｉｒｏｎｍｅｎｔｓｃｉｅｎｔｉｓｔｓｈａｖｅｃｏｎｄｕｃｔｅｄｍａｎｙｉｎ ｄｅｐｔｈｒｅｓｅａｒｃｈｅｓｏｎｔｈｅｃａｕｓｅａｎｄｆｏｒｍａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｒｅｄｔｉｄｅ ,ｍａｎｙｏｆｉｔｓａｓｐｅｃｔｓａｒｅｓｔｉｌｌｕｎｋｎｏｗｎｂｅｃａｕｓｅｒｅｄｔｉｄｅｉｓａｃｏｍｐｌｅｘｐｈｅｎｏｍｅｎｏｎａｎｄｔｈｅｅｃｏｌｏｇｉｃ…     

Research on red tide occurrences using enclosed experimental ecosystem in West Xiamen Harbor, China —Relationship between nutrients and red tide occurrence

This study on the distribution of phosphate and its relation to phytoplankton biomass in Western Xiamen Harbor using marine ecosystem enclosures to isolate the culture water from the tidal currents and salinity changes outside indicated that the phytoplankton biomass variation closely related to dissolved inorganic phosphorus (DIP) in the seawater as described by the equation: [Chl-a]=A×e^−B[PO4]. The biomass changes lagged by about two days the corresponding DIP. The research also dealt with the minimal DIP concentration for stopping diatom bloom and the possible maximal diatom biomass was estimated from the DIP external concentration in the seawater. The threshold of DIP initiatingSkeletonema costatum red tide was calculated for use as an index to forecast its red tides. In addition, the relationships between a dinoflagellate red tide and nutrients are discussed. The results showed that the multiplication of dinoflagellate was not entirely dependent on the nutrients in the seawater. Project 39570145 supported by the NSFC and Fujian Science Foundation (No. D94010).     

Dissolved organic matter and its role in red tide succession in the East China Sea in spring

Dissolved fluorescent organic matter was measured using fluorescence excitation-emission matrix spectroscopy at three temporal points during a Synechococcus bloom after diatom bloom dispersion in spring, 2007. Carbohydrate and dissolved organic carbon were also analyzed. The relationship between organic matter and red tide succession was examined. The results show that after the diatom bloom, tyrosine-like fluorescence B intensity was very high within the water column and exhibited a negative correlation wi...     

Nutrient and chlorophyll a anomaly in red-tide periods of 2003-2008 in Sishili Bay, China

Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll (chl-a) during high frequency red tide period (May to September). The results show that the chl-a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen (TIN) and silicate (SiO3-Si) increased lineally from 5.18 and 1.45 μmol/L in 2003 to 18.57 and 9.52 μmol/L in 2008, respectively, and the annual phosphate (PO4-P) varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons.     

A dinoflagellate <Emphasis Type="Italic">Cochlodinium geminatum</Emphasis> bloom in the Zhujiang (Pearl) River estuary in autumn 2009

A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species, accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation, and severe saline intrusion were likely responsible for the bloom of C. geminatum.     

TEMPORAL VARIATIONS OF HYDROLOGY AND LIGHT TRANSMISSION AT TWO FIXED OBSERVATION STATIONS IN THE EAST CHINA SEA

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Research on red tide occurrences using enclosed experimental ecosystems in west Xiamen Harbor, China—Relationship between various factors and red tide occurrences

A series of enclosed ecosystem experiments were conducted in a land-based tank near the seaside of West Xiamen Harbor. The results of experiments conducted in different seasons and years showed a repeatable phytoplankton succession. In this relatively stable ecosystem with added nutrients and trace metals, diatoms dominated initially, dinoflagellates dominated in the later stage, and dinoflagellate red tides eventually occurred. Vitamin B₁₂ enrichment may speed up this succession process. Stirring the water column could stop this process. Soluble Mn at a level of 3–4 μg/L in seawater, which also is the existing concentration of soluble Mn in Xiamen Harbor seawater, is sufficient for the multiplication of algae and occurrence of red tide. The present study showed that excessive soluble Mn in Xiamen Harbor cannot cause red tide, and that Fe was one of the important factors causing diatiom red tide in this present study. Project 39570145 supported by NSFC.     

The recognition of ocean red tide with hyper-spectral-image based on EMD

A new technique is introduced in this paper regarding red tide recognition with remotely sensed hyper-spectral images based on empirical mode decomposition （EMD）, from an artificial red tide experiment in the East China Sea in 2002. A set of characteristic parameters that describe absorbing crest and reflecting crest of the red tide and its recognition methods are put forward based on general pictre data, with which the spectral information of certain non-dominant alga species of a red tide occurrence is analyzed for establishing the foundation to estimate the species. Comparative experiments have proved that the method is effective. Meanwhile, the transitional area between red-tide zone and non-red-tide zone can be detected with the information of thickness of algae influence, with which a red tide can be forecast.     

The Monitoring of Red Tides Based on Modular Neural Networks Using Airborne Hyperspectral Remote Sensing

This paper proposes a red tide monitoring method based on clustering and modular neural networks. To obtain the features of red tide from a mass of aerial remote sensing hyperspectral data, first the Log Residual Correction （LRC） is used to normalize the data, and then clustering analysis is adopted to select and form the training samples for the neural networks. For rapid monitoring, the discriminator is composed of modular neural networks, whose structure and learning parameters are determined by an Adaptive Genetic Algorithm （AGA）. The experiments showed that this method can monitor red tide rapidly and effectively.