Vertical distribution characteristics of dust aerosol mass concentration in the Taklimakan Desert hinterland

The different height mass concentrations of dust aerosol data from the atmosphere environment observation station （Ta- zhong Station） was continuously observed by instruments of Grimm 1.108, Thermo RP 1400a and TSP from January of 2009 to February of 2010 in the Taklimakan Desert hinterland. Results show that： （1） The mass concentration value of 80 m PMl0 was higher, but PM2.5 and PM1.0 concentrations at 80 m was obviously lower than 4 m PMl0, and the value of 80 m PM1.0 mass concentration was the lowest. （2） The PM mass concentrations gradually decreased from night to sunrise, with the lowest concentration at 08：00, with the mass concentration gradually increased, up to the highest concentration around 18：00, and then decreased again. It was exactly the same with the changes of wind speed. （3） The high monthly average mass concentration of TSP mainly appeared from March to September, and the highest concentration was in April and May, subsequently gradually decreased. Also, March-September was a period with high value area of PM monthly average mass concentration, with the highest monthly average mass concentration of 846.0 p.g/m3 for 4 m PM^0 appeared in May. The concentration of PM10 was much higher than those of PM2.5 and PM1.0 at 80 m. There is a small difference between the concentration of PM2.5 and PM~ 0. Dust weather was the main factor which influenced the concentration content of the different diameter dust aerosol, and the more dust weather days, the higher content of coarse particle, conversely, fine particle was more. （4） The mass concentration of different diameter aerosols had the following sequence during dust weather： clear day 〈 blowing dust 〈 floating and blowing dust 〈 sandstorm. In different dust weather, the value of PM^o/TSP in fine weather was higher than that in floating weather, and much higher than those in blowing dust and sandstorm weather. （5） During the dust weather process, dust aerosol concentration gradually decreased with particle size decreasing. The dust aerosol mass concentration at different heights and diameter would have a peak value area every 3-4 days according to the strengthening process of dust weather.

Vertical distribution of sediment concentration

A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sediment concentration has an infinitely large value at the channel bottom and a zero value at the water surface. Based on this formula and the logarithmic ve- locity profile, a theoretical elementary function for the transport rate of a suspended load is developed. This equation improves the Einstein equation in which the unit-width suspended sediment discharge must be solved by numerical integration and a contra- diction between the lower limit of the integral and that of velocity distribution exists.

Estimating total leaf nitrogen concentration in winter wheat by canopy hyperspectral data and nitrogen vertical distribution

The use of remote sensing to monitor nitrogen(N) in crops is important for obtaining both economic benefit and ecological value because it helps to improve the efficiency of fertilization and reduces the ecological and environmental burden.In this study,we model the total leaf N concentration(TLNC) in winter wheat constructed from hyperspectral data by considering the vertical N distribution(VND).The field hyperspectral data of winter wheat acquired during the 2013–2014 growing season were used to construct and validate the model.The results show that:(1) the vertical distribution law of LNC was distinct,presenting a quadratic polynomial tendency from the top layer to the bottom layer.(2) The effective layer for remote sensing detection varied at different growth stages.The entire canopy,the three upper layers,the three upper layers,and the top layer are the effective layers at the jointing stage,flag leaf stage,flowering stages,and filling stage,respectively.(3) The TLNC model considering the VND has high predicting accuracy and stability.For models based on the greenness index(GI),mND705(modified normalized difference 705),and normalized difference vegetation index(NDVI),the values for the determining coefficient(R2),and normalized root mean square error(nRMSE) are 0.61 and 8.84%,0.59 and 8.89%,and 0.53 and 9.37%,respectively.Therefore,the LNC model with VND provides an accurate and non-destructive method to monitor N levels in the field.

Experimental Study on Suspended Sediment Concentration and Its Vertical Distribution under Spilling Breaking Wave Actions in Silty Coast

In this paper, flume experiments are focused on sediment transport inside and outside the surf zone. According to the energy dissipation balance principle of sediment-laden flow and the similarity between energy dissipation of spilling breaking wave and hydraulic jump, formulas are proposed to predict time averaged suspended sediment concentration under both non-breaking and breaking waves. Assuming that the sediment diffusion coefficient, which is related with energy dissipation, is proportional to water depth, formulas are proposed to predict close-to-bed suspended sediment concentration and vertical distribution of suspended sediment under spilling breaking waves, and the prediction shows a good agreement with the measurement.

Temporal and vertical distribution of microphytobenthos biomass in mangrove sediments of Zhujiang (Pearl River) Estuary

Being a primary producer, Microphytobenthos （MPB） play an important role in the benthic ecosystem of mangrove swamps. The temporal and vertical distribution of MPB biomass, expressed as chlorophyll a （Chl a）, was investigated in mangrove swamps on the Qi＇ao island and the Futian Mangrove Nature Reserve, Guangdong Province, South China. Both locations are situated in the Zhujiang （Pearl River） Estuary. For each location, bi-monthly sampling was carried out at four sites during low tide period. Except one site on the Qi＇ao Island, which was in Phragrnites australis marsh, all sites were in mangrove swamps. The Chl a concentration in surface （0-1 cm） sediment ranged from 0.2/2g/cm3 to 8.3 #g/cm3 in the Qi＇ao Island and from 2.1/zg/cm3 to 15.6/2g/cm3 in the Futian Mangrove Reserve. The peak Chl a concentration occurred in winter or early spring, while the lowest Chl a concentration, with a value of about one quarter of the peak, was observed in summer or early autumn. The vertical distribution of Chl a concentration exhibited an exponential decline with depth, which indicated a muddy sediment with high organic matter, and the slope of the curve was positively related to Chl a concentration in the surface sediment. The MPB biomass of the Qi＇ao Island was significantly lower than that of the Futian Mangrove Reserve. Our results suggest that the overlaying water quality might influence the MPB biomass in surface sediments.

夏季香溪河库湾溶解氧与叶绿素a日间垂向分布特征及影响因子初探

为了解三峡水库水华爆发时空特征,于2020年6月在三峡库区香溪河库湾未发生水华的条件下通过日间高频次连续加密监测,分析溶解氧、叶绿素a等指标的时空变化,甄别藻类生长特性。结果表明,温跃层和表中层倒灌异重流的存在阻碍了垂向水动力交换,进而促使水体表底均存在氧跃层;夏季连续的晴天可能会导致07:00~11:00、14:00~17:00爆发水华的几率增加;水华爆发存在滞后性,仅通过单层水体藻密度无法表征藻类生长状况,需通过藻类垂向迁移范围内的平均藻密度作进一步水华预警判断。

Sediment-copper distributions in hyper-concentrated turbulent solid-liquid system

This study presents a special problem on vertical distribution for sediment and copper in hyper-concentrated turbulent solid-liquid system that is essentially different from the ordinary low-concentrated turbulent system. A resonance type turbulent simulation equipment is used for the experimental study in which a vertically uniform turbulent field of the mixture of loess and water is produced in a testing cylinder with a grille stirrer that moves up and down harmoniously with varying vibration frequencies, in order to compare the variations of the vertical profiles of sediment and copper in low- and hyper-concentratod solid-liquid system, different scenarios for input sediment content ranging from 5 to 800 kg/m^3 was considered in the experimental studies. It was found that solids copper content increases with input sediment content, So, and reaches its peak as So goes to 10 kg/m^3 and then decreases rapidly with increasing input sediment content. Such a behavior is possibly resulted from the joint effect of the specific adsorption of copper on loess, precipitation of carbonate and hydroxide of copper due to high carbonate content in the loess and the so-called ＂particulate concentration effect＂ due to the present of the sediment variation in water. The vertical sediment concentration distribution resulted from the uniform turbulence is generally uniform, but slight non-uniformity does occur as sediment concentration exceeds certain value. However, the vertical concentration distributions of soluble copper seem not to be affected much by the variation of sediment concentrations.

狮子洋水域浮游植物丰度与叶绿素a浓度的分布特征

为探究河口水域初级生产者群落特征,本研究于2019年10月(秋季)与2020年3月(春季)对狮子洋水域浮游植物群落进行调查研究。结果显示,浮游植物总丰度与叶绿素a浓度季节间均无显著差异,空间分布上均呈现出自北向南逐渐降低的趋势。皮尔逊分析结果显示,浮游植物总丰度与pH呈显著正相关,与磷酸盐浓度呈显著负相关;叶绿素a浓度与石油类污染物、浮游植物丰度、硅藻门丰度呈显著正相关,与盐度呈显著负相关。上述结果表明,狮子洋水域浮游植物总丰度与叶绿素a浓度分布特征趋于一致,pH、磷酸盐浓度是影响总丰度的关键因素,盐度、石油类污染物浓度是影响叶绿素a浓度的关键因素。

汕头近岸海域叶绿素a的时空分布

基于2021年11月(秋季)和2022年3—4月(春季)汕头近岸海域表层水质调查数据,分析了叶绿素a(Chl-a)的时间空间分布。研究结果显示,秋季表层叶绿素a浓度为0.97~15.62μg/L,平均值为3.73μg/L,春季叶绿素a浓度为0.76~8.87μg/L,平均值为2.65μg/L。表层水叶绿素a含量呈现秋季>春季的季节变化现象,水平分析发现,春秋季均表现为近岸向外海递减趋势;春秋两季叶绿素a含量均呈现垂直向下递减趋势。叶绿素a的时空分布受陆地径流稀释、营养盐外源输入和养殖环境状况等的共同影响,是一个整体影响的结果。

太湖叶绿素a浓度时空分异及其定量反演

利用2005年实测叶绿素a浓度数据分析了太湖叶绿素a浓度的时空分布特征,并利用同步光谱数据,分季节对太湖叶绿素a浓度的反演模型进行研究,从而分析叶绿素a的时空变化对反演模型的影响.首先分析1 a内叶绿素a浓度随时间的变化规律,然后利用反距离加权插值法绘制叶绿素a浓度不同季节空间分布图,分析叶绿素a浓度在不同季节的空间分布规律,在此基础上分春、夏、秋3个季节和中营养化、轻度富营养化、中度富营养化、重度富营养化4个营养状态进行叶绿素a浓度定量反演模型研究.结果表明,太湖叶绿素a浓度具有明显的时空分布特征.夏季叶绿素a浓度最高,冬季最低,平均浓度分别为56.29μg/L、13.61μg/L.秋季由于受到夏季高浓度的影响,叶绿素a浓度高于春季,平均值分别为26.43μg/L3、4.78μg/L;夏季叶绿素a浓度空间变化最大,冬季全湖叶绿素a浓度含量较为均一,空间变化不明显,秋季空间差异要大于春季;全年北部湖区的空间差异较大,而南部湖区相对较小.不同季节叶绿素a反演算法模型不同,春、秋季波段比值法反演效果较好;而夏季微分法反演效果明显好于其它反演算法,不同营养状态条件下反演算法差异相对较小.

施氮对半湿润农田夏玉米冠层氮素及叶绿素相对值(SPAD值)垂直分布的影响

以半湿润地区土垫旱耕人为土为供试土壤,采用田间试验,研究了不同施氮水平下夏玉米(Zeamays L.)拔节期、灌浆期和成熟期3个生育期冠层叶片氮素、叶绿素相对值(SPAD值)的垂直分布规律及其差异;同时对各层叶片含氮量、SPAD值与施氮量进行相关分析。结果表明,在各生育期不同叶层叶片含氮量按上、中、下层顺序呈明显递减规律,从全生育期不同施氮处理看,上层比中层增加6.64%,中层比下层增加5.18%。随施氮量增加,中上层叶片含氮量差异增大,中下层叶片含氮量差异减小。冠层内叶片SPAD值垂直分布规律与叶片含氮量分布规律相类似。相关分析表明,全生育期各层叶片SPAD值与叶片含氮量呈极显著线性正相关关系(R=0.503**)。进一步分析发现,各层叶片SPAD值、叶片含氮量与施氮量的相关性以上层叶关系最为密切,揭示了夏玉米氮素营养诊断的较好叶片是上层叶位。

南海叶绿素a浓度垂直分布的统计估算

分析整理了1993—2006年近10 a南海北部海域、南沙海域和南海其他海域的叶绿素a浓度历史航次调查资料,基于前人提出的全球叶绿素浓度垂直分布的统计分析模式,根据南海表层叶绿素a浓度大小的不同分级,对南海叶绿素a浓度进行了参数化处理,拟合估算了南海各水层剖面的叶绿素a浓度分布值,并结合不同海区的环境特征,分析了南海叶绿素a浓度垂直分布与其海水物理环境的关系。初步分析结果表明,叶绿素a浓度随深度垂直变化的拟合曲线呈一定倾斜的正态分布特征,当表层叶绿素a浓度较低时,作为南海深水海盆区的代表,拟合值更接近实测平均值的分布,叶绿素a浓度高值集中在次表层剖面上;当表层叶绿素a浓度较高时,作为近岸区和河口区的代表,高值多集中在表层海水,拟合误差偏大。该统计估算模式对于揭示南海叶绿素a浓度垂直分布结构进行了有益的尝试,为发展适合不同海区特点的模式以及校正参数奠定了基础。利用该模式与海洋水色卫星遥感数据有效结合,将对南海叶绿素a浓度时空分布格局的研究具有重要的意义。

南极长城湾夏季叶绿素a变化的研究

１９９２年１２月～１９９３年３月、１９９３年１２月～１９９４年２月、１９９４年１２月／１９９５年３月连续３个夏季期间在南极长城湾进行了海洋生态系统调查，利用获得的浮游植物现存量（叶绿素ａ）资料进行分析研究发现：１９９２／１９９３年夏季叶绿素ａ含量最高，平均值为３．７９ｍｇ／ｍ３，变化幅度也最大，为１０．１０ｍｇ／ｍ３。连续３个夏季的年际变化趋势是３．７９ｍｇ／ｍ３（１９９２／１９９３）＞１．８０ｍｇ／ｍ３（１９９３／１９９４）＞１．２０ｍｇ／ｍ３（１９９４／１９９５）。而变化的幅度也同样依次为１０．１０ｍｇ／ｍ３＞６．５７ｍｇ／ｍ３＞２．４１ｍｇ／ｍ３。所获得的结果与南极地区相同季节其它近海海水中的叶绿素ａ含量进行比较得知：除Ｇｅｒｌａｃｈｅ海峡（１９５９年１月）１１．６０ｍｇ／ｍ３和ＭｃＭｕｒｄｏ海峡（１９６１年１２月）５６．１０ｍｇ／ｍ３外，这次调查结果属中上水平。本文还对该海域叶绿素ａ的垂直分布状况进行了分析。

南海中部海域夏季叶绿素a浓度垂向分布特征

根据2014年7月~8月南海中部海域(12°N^18°N,110°E^117°E)调查获得的水柱方向上连续的叶绿素a浓度(Chl-a)数据,分析了南海中部海域夏季Chl-a垂向分布特征。结果表明:1)南海中部海域Chl-a垂向分布呈现先增加后减小的趋势,在30~70 m水层出现Chl-a高浓度区;2)次表层Chl-a最大值(subsurface chlorophyll a concentration maximum,SCM)强度变化为0.94~4.69 mg·m-3,平均为1.90 mg·m-3,是遥感表层Chl-a平均值的18.10倍,SCM深度变化为4~75.36 m,SCM厚度变化为19.01~80.36 m;3)从断面分布来看,局部海域Chl-a垂向分布受到上升流的显著影响,断面A上沿岸上升流区表现出明显的SCM强度大、深度浅和厚度大的特征,而断面B上中沙群岛岛礁上升流区同样表现出SCM强度大、深度浅的特征,但是厚度相对较小。

海水混合和层化对叶绿素a垂直分布的影响

根据长江口海区、近岸浅水区、黄海冷水团海区和水深超过200m的陆架区等四个区域的定点调查获得的数据,分析了温度、盐度与叶绿素a垂直分布的相互关系。结果表明,长江口海区,陆源径流与海水混合不充分,表层营养盐含量较高,表层叶绿素a含量高于中下水层。近岸浅水区的苏北近岸海水垂向没有温跃层和盐跃层,叶绿素a的垂向分布也均匀,东海西部沿岸出现逆温跃层和逆盐跃层,海水垂直混合不充分,叶绿素a含量(6.72mg/m3)在10m深水域最高。黄海冷水团海区海水的垂直混合不充分,叶绿素a的垂直变化显著,高值区出现在温跃层下方(4.37mg/m3)。水深超过200m的陆架区,温度的阶梯状结构、营养盐跃层、光照等因素共同导致整个水层叶绿素a含量普遍较低。同时,结合历史资料分析认为,海水的混合、温度和盐度的层化将影响营养盐的浓度和分布,从而影响海水中叶绿素a的垂直分布。

2000年秋季黄、东海典型海区叶绿素a的时空分布及其粒径组成特征

分析了 2 0 0 0年秋季黄、东海几个典型海区的叶绿素 a调查资料 ,结果表明 :在没有温跃层存在的海区 ,叶绿素 a的垂直分布是均匀的 ,昼夜 (2 4 h)变化的幅度也很小 ,且上、下层不同粒径的浮游植物所含叶绿素 a的比例变化也不大。但在明显存在温跃层的海区中 ,叶绿素 a的垂直变化明显 ,昼夜变化的幅度较大 ,且在温跃层的上、下方显示相反的变化规律 ;不同粒径浮游植物叶绿素 a的比例组成在温跃层上、下方明显不同 ,在温跃层的下方 ,较大粒径 (2～ 2 0μm,>2 0μm)的叶绿素

2008年夏季南黄海叶绿素a垂向分布格局初探

根据2008年8月南黄海海域的温度、盐度、光照和叶绿素a的观测资料,分析了叶绿素a垂向分布特征及其与温度、盐度、光照的关系。结果表明,叶绿素a垂向有1个、2个或多个峰区,按其所在水团和垂向特征可分为10个类型;叶绿素a垂向分布格局与海水层化、光照和营养盐等环境因子有关。

大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化

为了较为系统地研究大亚湾水域叶绿素a和营养盐的垂直分层状况,并为大亚湾海洋生态系统的数值模拟提供基础数据,作者于大亚湾大辣甲和桑洲之间连线的中间点附近海域选点,在2007年～2008年进行了4个季度的垂直采样监测。本次研究分析了大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化,并分析了叶绿素a与DIN、PO4-P和SiO3-Si的关系。结果表明:在整个监测时段内,叶绿素a和DIN、PO4-P、SiO3-Si的浓度范围分别为0.50～5.80 mg·m-3、0.023～0.159mg·L-1、1.606～19.69μg·L-1和0.065～1.13 mg·L-1,营养盐和叶绿素a在4个季度里的垂直变化趋势各有不同;在季节变化上,SiO3-Si与DIN比较相似,总体呈现夏、冬、秋季高,春季较低的特征,PO4-P恰好相反,夏季的浓度最低,叶绿素a总体呈现夏、春、冬季高,秋季较低的特征;在整个垂直水柱内,DIN和SiO3-Si对叶绿素a的影响相对较小,PO4-P和叶绿素a呈显著正相关关系。

低压浑水管道输沙规律研究及水流挟沙力计算

【目的】确定输水工程适宜运行的水力条件。【方法】以巴音沟河流域输水工程为研究对象,通过数值模拟的方法研究不同泥沙质量浓度、压力条件下浑水管道输沙规律及水流挟沙力特性。【结果】(1)管道断面垂向泥沙质量浓度分布受压力、体积含沙量及管径等因素的影响;当压力及管径较小时,泥沙淤积厚度为6.3~8.0 mm,压力及管径较大时,在Y=-0.07区域以下淤积较多,淤积厚度达到8.6~9.4 mm;(2)同一管径及流速下,随着体积含沙量的增大,该区域流速梯度增大,最大增幅为14%;(3)随着水流速度增大,水流挟沙力增大,悬移质质量浓度也越大,但是悬浮指标逐渐变小。【结论】在低压浑水管道中,管径越大、泥沙质量浓度越大、压力越小,水流挟沙力越小,泥沙越容易淤积。

基于Argo数据和MODIS数据的海水漫射衰减系数的垂直廓线研究

叶绿素浓度是反映海水营养状况的重要参数,光谱漫射衰减系数是反映水中表观光学特性的参数,且这两个参数之间关系密切。光谱漫射衰减系数的垂直分布反映了垂直方向的光衰减特性,对水下激光通信的信道特性研究具有重要意义。本文根据现有的MODIS(Moderate-Resolution Imaging Spectroradiometer)数据建立的叶绿素浓度垂直分布模型和单参数(叶绿素浓度)的光谱漫射衰减系数模型,提出了一种新的垂直方向的衰减模型,并建立了位于第二岛链日本附近海域的漫射衰减系数垂直分布。该分布与实际测量的关于叶绿素浓度垂直分布的Argo(Array for Real-time Geostrophic Oceanography)数据并结合单参数的光谱漫射衰减系数模型所建立的漫射衰减系数垂直分布进行比较,其结果大致相同,验证了该模型的可行性。此外还对不同叶绿素浓度下的漫射衰减系数光谱进行了分析,结果表明浑浊海域采用绿色波段和清澈海域采用蓝色波段得到的衰减系数值最小。对比Argo数据,MODIS数据实时性更高且较容易获得,因此本文提出的垂直分布的衰减模型应用更方便。