首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Based on three continuous in situ underwater light field measurement under different wind waves conditions in Longgan Lake, Meiliang Bay of Taihu Lake in July 2003 and littoral zone near TLLER in July 2004, respectively, the effects of sediment resuspension caused by wind waves on PAR diffuse attenuation, absorption coefficients and euphotic depths are analyzed. In Longgan Lake, PAR diffuse attenuation coefficients during small, middle and large wind waves were 1.74, 2.02 and 2.45 m-1, respectively, and the corresponding PAR spectral diffuse attenuations ranged from 0.98 to 2.97, 1.34 to 3.95 and 1.80 to 5.40 m-1, respectively. In Meiliang Bay, PAR diffuse attenuation coefficients were 2.63, 3.72, 4.37 m-1 during small, middle and large wind waves. PAR diffuse attenuation coefficients increased by 41% and 66% from small to middle, large wind waves, respectively. Absorption coefficients integrated over the range of PAR of CDOM, phytoplankton were 0.26, 0.28 m-1; 0.76, 0.49 m-1, respectively during middle and large wind waves. Absorption coefficients integrated over the range of PAR of non-algal particulate matter and total suspended particulate matter increased from 0.94 to 1.73 m-1, and from 1.70 to 2.22 m-1, respectively during middle and large wind waves. Relative contributions of absorption coefficients of non-algal particulate matter to total absorption coefficient integrated over the range of PAR were 44.14%, 65.05%, respectively, during middle and large wind waves. PAR euphotic depths decreased by 0.40, 0.19, 0.20 m from middle to large wind waves in Longganhu Lake, Meliang Bay and littoral zone near TLLER. Significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and total suspended paniculate matter, wind velocity, wave height. Most significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and inorganic suspended paniculate matter but low correlations for chlorophyll a, dissolved organic carbon. Increase of total suspended paniculate matter, especially inorganic suspended paniculate matter caused by wind waves was the dominant factor affecting underwater light field in shallow lakes in the middle and lower reaches of the Yangtze River based on observations at three stations.  相似文献   

2.
水下光照分布是影响水生态系统的重要因素,研究光合有效辐射衰减特征对于沉水植物恢复具有一定的指导意义.根据沉水植物生物量资料,将东太湖划分为沉水植物茂盛区、沉水植物稀疏区和无植物区3种区域.基于2019年夏季原位水下光场资料,探讨了东太湖光衰减特性和光照衰减因子的空间差异以及不同区域内的主导衰减因子,分析了东太湖的稳态阶段和富营养化水平,并阐述了真光层深度与透明度的关系,以期为东太湖沉水植物恢复和保护提供相关资料.结果表明:东太湖不同区域光衰减特性差异显著,光合有效辐射衰减系数(k d(PAR))在0.73~11.80 m^-1之间变化,真光层深度范围为0.39~6.31 m.不同区域的无机悬浮物和有机悬浮物浓度存在显著性差异,稀疏区叶绿素a浓度显著高于茂盛区,而与无植物区没有显著差异,有色可溶性有机物(CDOM)吸收系数在3种区域无显著性差异.k d(PAR)与无机、有机悬浮物的线性拟合效果较好,而与叶绿素a、CDOM拟合较差.水体吸收和散射作用是茂盛区光衰减的主要原因,无植物区域主导衰减因子仅有无机悬浮物,稀疏区由叶绿素a和无机悬浮物共同主导,是生态修复需要重点关注的区域,有机悬浮物和CDOM对东太湖光照衰减没有太大影响.东太湖目前正处于从草型稳态向藻型稳态过渡的阶段,整个湖泊属于富营养水平,真光层深度大约为透明度的2.7倍.  相似文献   

3.
Euphotic depth can be defined as the portion of wa- ter column that supports the net primary productivity. Its lower end is the critical depth, namely, the depth measured when the daily net primary productivity is zero[1]. In the ecosystems of oceans, lakes and rivers, phytoplankton live in the euphotic depth and euphotic depth is usually taken as the lower boundary, when studying the primary productivity and biomass of phytoplankton; therefore the corresponding depth is sometimes called the t…  相似文献   

4.
龙感湖水体光学特性的观测   总被引：1，自引：0，他引：1  
基于2002—2003年秋、夏季原位水下光场巡测及连续定点观测资料分析了龙感湖不同湖区及不同风浪条件下水体的光学特性,探讨了光衰减系数、辐照度比的光谱分布、空间差异及不同风浪条件对水下光场的影响.结果表明,水下光谱在紫光波段衰减最强烈,其次是蓝光,红、绿光衰减最弱,并且向下辐照度衰减系数一般要大于向上辐照度衰减系数.秋季L1-L3点向下辐照度400—700nm波段衰减系数的变化范围分别为0.71—3.60、1.06—3.72、0.78—2.89m-1;光衰减系数的空间分布是位于湖中心的12点要略大于两边的L1、L3点;辐照度比的变化趋势极为一致,最低值出现在短波蓝光波段,最高值出现在550—600nm之间;从小风浪到中风浪、大风浪其PAR衰减系数分别是1.74、2.02、2.45m-1;透明度、衰减系数与悬浮物浓度相关性最好,决定系数在0.7以上,但其变化除受悬浮物影响外还要受制于溶解性有机物和浮游植物;440nm波长衰减系数(Kd(440))与悬浮物(SS)、溶解性有机碳(DOC)、叶绿素a(Chl.a)的多元线性回归方程为:Kd(440)=0.514—0.075SS 0.125DOC 0.100Chl.a(R2=0.87,N=8,P≤0.05)  相似文献   

5.
青藏高原地区分布的湖泊数量众多、面积较大、分布范围广泛.受制于恶劣的自然条件,对该地区湖泊的光学吸收特性以及光合有效辐射衰减系数(Kd(PAR))的研究鲜有成果.本文依据2014和2015年间采集的13个典型高海拔、湖泊面积较大的湖库的现场实测数据和实验室测定数据,分析了采样湖库各个采样点的Kd(PAR)特征以及有色可溶性有机物(CDOM)、藻类颗粒物吸收及非色素颗粒物吸收特性,计算并分析了Kd(PAR)与透明度以及光学活性物质的关系.研究结果表明:青藏高原地区各湖库平均各项颗粒物吸收系数均较低,总颗粒物吸收系数在400~700 nm波段内不超过0.14 m~(-1)、CDOM吸收系数在355 nm波长处最高,为1.23 m~(-1)、最低接近于0、藻类颗粒物吸收特性不明显;实验数据完整的巴木错、格仁错和班公错的主导吸收组分各异,其中巴木错为CDOM吸收主导,格仁错与班公错为非色素颗粒物吸收主导;青藏高原采样湖泊总体Kd(PAR)平均值较小,仅为0.26 m~(-1),样点最大值出现在可鲁克湖(1.17 m~(-1)),最小值出现在普莫雍错(0.10 m~(-1));在采样湖泊中Kd(PAR)与透明度呈显著相关;Kd(PAR)与CDOM的相关性最强,叶绿素a浓度次之,与总悬浮颗粒物浓度的相关性最不显著.  相似文献   

6.
Seasonal and spatial aspects of the net settling velocities of particles in Lake Constance were investigated by measurements of settling fluxes and estimates of the concentrations of suspended matter. Annual mean sinking velocities ranged from 2.6 m d?1 in the euphotic zone to 7.5 m d?1 in the aphotic zone. Summer maxima of 36.6 m d?1 were caused by settling calcite crystals, while minima of 0.4 m d?1 during the clear water phase resulted from particulate matter consisting mostly of phytoplankton and organic debris. Winter settling velocities averaged 1,2 m d?1. The mean residence time for the bulk of particles calculated on an annual basis was 27.8 days. The net settling velocities in this study were higher than those calculated for phytoplankton in other investigations but agreed with estimates for particles from Lake Zürich obtained by an approach similar to this study.  相似文献   

7.
Light attenuation is considered as a sentinel for environmental change in lakes and has a profound influence on aquatic ecosystems. However, the spatial distribution of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) attenuation, and the underlying mechanisms are still not fully understood. We carried out a field investigation with 60 sampling sites covering the entire Lake Qiandaohu from November 29 to December 1, 2013, during the weak stratification period to elucidate the spatial pattern and driving mechanisms. The diffuse attenuation coefficient of UVB (Kd(313)), UVA (Kd(340)) and PAR (Kd(PAR)) varied from 1.48 to 4.63 m−1, 1.09 to 3.43 m−1, and 0.26 to 0.94 m−1, respectively. The corresponding ranges for the 1% attenuation depths were from 0.10 to 3.11 m, 1.34–4.21 m and 4.87–17.58 m, respectively. Total suspended matter (TSM) concentration was highly significantly correlated with Kd(313), Kd(340) and Kd(PAR) indicating that TSM was the main driver of UVR and PAR attenuation in Lake Qiandaohu in the late autumn and early winter. TSM concentration, Kd(313), Kd(340) and Kd(PAR) had obvious horizontal spatial heterogeneity presenting a decreasing trend from the estuary area to the center area in the lake. These results suggested that the spatial distribution of TSM from the inflow drived the spatial distribution of UVR and PAR attenuation. Significantly positive correlations were also observed between the chromophoric dissolved organic matter (CDOM) absorption coefficient and Kd(313). TSM and CDOM absorption spectra showed that in the UVR waveband (350–400 nm), the mean relative contribution rates of CDOM (ag(λ)), non-algal particles (anap(λ)), phytoplankton (aph(λ)) and pure water (aw(λ)) to the total absorption were 67.5 %, 24.0 %, 5.0 % and 3.5 %, respectively. In the PAR waveband, the mean relative contribution rates of ag(λ), anap(λ), aph(λ) and aw(λ) to the total absorption were 25.4 %, 18.6 %, 9.4 % and 46.6 %, respectively. Our findings could provide support for ecological environment protection in Lake Qiandaohu considering the importance of UVR and PAR attenuation in aquatic ecosystems.  相似文献   

8.
程海位于云南省丽江市永胜县,是高原封闭型深水湖泊的典型代表.为了揭示程海真光层深度的时空分布及其影响因子,于2016年3月-2017年2月在程海布设9个点位开展逐月调查.结果显示：光合有效辐射漫射衰减系数、真光层深度的年均值分别为1.06±0.25 m-1、4.64±1.27 m;空间变化方面,无论"北、中、南部"还是"西、中、东部",全年、逐月及雨旱季的真光层深度均无显著差异;时间变化方面,5月的真光层深度最高（6.49±1.03 m）、7月的最低（3.63±0.48 m）,且全年、雨季、旱季的各月份间差异显著;回归分析发现,浮游植物生物量是程海真光层深度的最主要影响因子,悬浮物浓度次之（主要在雨季）,有色可溶性有机物的影响甚微.为进一步识别程海真光层深度的间接影响因子,本文还分析了浮游植物生物量与生态因子的相关性.本研究可为程海的保护和治理积累数据并提供借鉴.  相似文献   

9.
湖泊中有色可溶性物质对近紫外及蓝光衰减的影响   总被引：13，自引：3，他引：10  
研究巢湖(藻型湖泊)和龙感湖(草型湖泊)的有色可溶性物质(CDOC)对近紫外及蓝光衰减的影响时发现：巢湖水体中可溶性有机碳含量比龙感湖大。2个湖泊中来源不同的可溶性有机碳对光的吸收极其相似,只是在量上有差异。在巢湖水体中,光的衰减曲线在355—400nm之间有一个峰,且Kd值较大,而在龙感湖水体中,光的衰减曲线在500nm以下时随着波长的递减而增加。从CDOC对Kd的贡献来看,它们之间最大的相关是在355nm左右,这是悬浮质、叶绿素以及CDOC共同作用的结果。  相似文献   

10.
沈明  段洪涛  曹志刚  薛坤  马荣华 《湖泊科学》2017,29(6):1473-1484
下行漫衰减系数(K_d)是描述水下光场的重要参数,决定水体真光层深度,影响着浮游藻类初级生产力及其分布特征.基于2008—2013年太湖4次大规模野外试验数据,分析太湖水体漫衰减系数特征及其影响因素,建立适用于多种卫星数据且较高精度的太湖水体490 nm处下行漫衰减系数估算模型.结果表明:无机悬浮物是太湖水体漫衰减系数的主要影响因素;红绿波段比值(674 nm/555 nm)最适合于太湖K_d(490)估算,模型反演精度较高(N=72,R~2=0.72,RMSE=0.89 m~(-1),MAPE=21.58%);利用实测光谱数据,模拟得到MODIS/EOS、OLCI/Sentinel-3、GOCI/COMS和MSI/Sentinel-2等主要传感器波段的信号,构建适用于多种卫星传感器K_d(490)估算的红绿波段模型,建模精度较高(N=72,R~20.7,RMSE0.9 m~(-1),MAPE22.0%),且进行了验证(N=37,R~20.7,RMSE0.9 m~(-1),MAPE22.0%).  相似文献   

11.
滆湖水体光学性质初步研究   总被引：3，自引：1，他引：2  
基于2009年7月至2010年6月滆湖全湖15个采样点的水体光学参数及相关水质理化因子数据,分析滆湖水体周年光合有效辐射(PAR)衰减特性,以期为滆湖沉水植物生态修复提供相关水体光学资料.结果表明,滆湖水体PAR衰减系数(Kd)周年变化范围为1.32～17.42 m-1.秋季Kd相对最小,平均值为2.35 m-1,变化范围为1.32 ～3.70 m-1;夏季Kd相对最大,平均值为6.23 m-1,变化范围为3.68～17.42 m-1.春、秋、冬季,滆湖水体真光层平均深度均满足沉水植物的生长需求,而在夏季滆湖水体真光层平均深度仅为0.84m,小于全湖平均水深(1.20 m),因此夏季PAR是限制沉水植物恢复的因子之一.滆湖水体Kd与透明度(SD)在秋、冬季的关系为:Kd =2.089 +0.705/SD.叶绿素a浓度和悬浮物浓度是影响滆湖水体Kd的重要因子之一.  相似文献   

12.
兴凯湖春季水体悬浮颗粒物和CDOM吸收特性   总被引：1，自引：0，他引：1  
为了分析兴凯湖水体光学活性物质的吸收特性、来源和空间分布以及对400~700 nm范围内总吸收的贡献,于2013年5月对该水体进行野外实验,对水体中浮游藻类、非藻类颗粒物和有色可溶性有机物的吸收特性和水质参数进行测定.结果表明:总悬浮颗粒物的吸收光谱与非藻类颗粒物相似,色素颗粒物含量较少且单一,非藻类颗粒物在总悬浮颗粒物吸收中占主导地位,其贡献率始终在50%以上.CDOM吸收曲线的拟合函数斜率值Sg均高于其它水体.440 nm处总悬浮颗粒物和非藻类颗粒物的吸收系数ap(440)、ad(440)与总悬浮颗粒物、无机悬浮颗粒物和有机悬浮颗粒物浓度相关性均较好,与叶绿素a(Chl.a)浓度的相关性较差.兴凯湖与其它Ⅱ类水体的差异性表现在440 nm处CDOM吸收系数ag(440)与Chl.a浓度、溶解性有机碳(DOC)浓度均无显著相关性,说明DOC以无色部分为主.总体上,大兴凯湖各吸收系数和水质参数均值均低于小兴凯湖,后者水质受农耕区退水及周围渔业、旅游业的影响较大.  相似文献   

13.
  相似文献   

14.
The internal source, especially resuspension process of the sediments in lakes and its environ- mental effect has been paid shining attention in the West as well as in China[1—6] although the influence of external source is important to water environment[7]. S鴑dergaard et al. compared the releases of soluble reactive phosphorus (SRP) in the surface sediments of Lake Arres before and after disturbance and they found that disturbing can increase the release by 20—30 times[3]. Robarts and ot…  相似文献   

15.
为了研究抚仙湖紫外辐射(UVR)和光合有效辐射(PAR)衰减的时空特征及其与有色可溶性有机物(CDOM)、悬浮物(SS)、浮游植物(叶绿素a表征)等因子的关系,于2014年10月(秋季)、2015年1月(冬季)开展现场调查,结果显示:秋季不同波长(段)的漫射衰减系数Kd(305)、Kd(340)和Kd(PAR)分别为1.27±0.12、0.68±0.11和0.32±0.13 m-1,冬季分别为1.13±0.10、0.63±0.07和0.36±0.07 m-1;秋季CDOM的不同波长吸收系数ag(254)、ag(305)和ag(340)分别为4.09±0.26、1.18±0.09和0.57±0.05 m-1,冬季分别为2.95±0.24、0.61±0.11和0.11±0.07 m-1,秋季ag(254)、ag(305)和ag(340)显著高于冬季;秋季Kd(305)显著大于冬季,这与秋季(雨季)较高的CDOM丰度、浮游植物生物量(及SS浓度)有关.秋季ag(305)/Kd(305)、ag(340)/Kd(340)均显著高于冬季;秋季及秋冬季整体而言,ag(254)与Kd(305)、Kd(340)呈显著正相关,各多元逐步回归方程中均包含ag(254),说明CDOM吸收对UVR的衰减有重要贡献.空间差异方面,秋季北部的ag(254)、Kd(305)和Kd(340)显著高于南部,冬季南北部无明显差异,或与雨旱季北岸河流输入的CDOM和SS的情况有关.此外,浮游植物对UV-B衰减的影响和SS(与CDOM的交互作用)对UV-A衰减的影响更在于季节变化方面,而影响UVR、PAR衰减的各因子的相对贡献有待进一步量化.  相似文献   

16.
Wang  Qiao  Jin  Xin  Li  YunMei  Wu  ChuanQing  L&#;  Heng  Wang  YanFei  Zhang  Hong  Yin  Bin  Zhu  Li 《中国科学:地球科学(英文版)》2011,53(1):58-66

Synchronization experiment was conducted in June, 2009 to get Inherent Optical Properties (IOP) of water component in Chaohu Lake. Water bio-optical mechanism was studied combined with multispectral data of Environmental Satellite 1 (CCD), and then inversion models of total suspended matter (TSM), inorganic suspended matter (ISM) and organic suspended matter (OSM) concentration were built. The data indicated that: the absorption ratio of suspended particulate matter and CDOM to total were almost no change from band 1 to band 2 with about 85% and 9%, respectively. The ratio of pure water to total increased from 0.4% to 5.6%. Water reflectance in these two bands were influenced by absorption of three kinds of components: algae particles absorption surpassed non-algal particles in band 3, and so played an important role in total absorption with about 35.7%; the proportion of pure water absorption and particles matter backscattering both were 99% in band 4, so these two components decided the main inherent optical properties in band 4. The models of TSM and ISM concentration inversion based on band combination (band 3 + band 4)/(band 1 + band 2) were built, while OSM concentration was estimated by band 4/(band 1 + band 2) index. Inversed by image data, RE of TSM concentration between modeled and measured was 33.4%, and RMSE was 18.68 mg/L. RE of ISM and OSM concentration were 39.9% and 35.2% respectively. The inversion was more accurate when satellite-ground data were just in the same day. At this situation, RE of ISM concentration dropped to 25.4%, and that of TSM and OSM reduced to 26.5% and 26.8% as well.

  相似文献   

17.
The optical properties and spatial distribution of chromophoric dissolved organic matter (CDOM) in Meiliang Bay of Lake Taihu were evaluated and compared to the results in literature. Concentrations of dissolved organic carbon (DOC) ranged from 8.75 to 20.19 mg L?1 with an average of (13.10 ± 3.51) mg L?1. CDOM absorption coefficients a(λ) at 280 nm, 355 nm, and 440 nm were in the range 11.28...33.46 m?1 (average (20.95 ± 5.52) m?1), 2.42...7.90 m?1 (average (4.92 ± 1.29) m?1), and 0.65...2.44 m?1 (average (1.46 ± 0.44) m?1), respectively. In general, CDOM absorption coefficient and DOC concentration were found to decrease away from the river inflow to Meiliang Bay towards the lake center. The values of the DOC‐specific absorption coefficients a*(λ), given as absorption coefficient related to mass concentration of organic carbon (C) ranged from 0.28 to 0.47 L mg?1 m?1 at 355 nm. The determination coefficients between CDOM absorption and DOC concentration decreased with the increase of wavelength from 280 to 550 nm. The linear regression relationship between CDOM absorption at 280 nm and DOC concentration was following: a(280 nm) = 1.507 L mg?1 m?1 · DOC + 1.215 m?1. The spectral slope S values were dependent on the wavelength range used in the regression. The estimated S values decreased with increasing wavelength range used. A significant negative linear relationship was found between CDOM absorption coefficients, DOC‐specific absorption coefficients and estimated S values especially in longer wavelength range. The linear regression relationship between DOC‐specific absorption coefficients at 440 nm and estimated S values during the wavelength range from 280 to 500 nm was following: a*(440 nm) = (–0.021 μm · S + 0.424) L mg?1 m?1.  相似文献   

18.
水体光学衰减特性直接影响湖泊的清澈程度和沉水植被的生存,利用遥感技术获取湖泊光学衰减分布特性能极大提高效率.基于2017-2019年的原位调查数据,利用Landsat 8 OLI影像开发了大冶湖水体光学衰减系数(Kd)的遥感反演模型,并分析大冶湖水体Kd的多年时空分布特性与驱动机制,以期为大冶湖流域的修复与管理提供参考...  相似文献   

19.
河蚬(Corbicula fluminea)为太湖优势大型底栖动物,通过受控实验研究其对富营养水体的水质改善效果.根据太湖河蚬的自然丰度设置4组密度处理,分别为无河蚬对照组、低密度河蚬组(生物量为130 g/m2)、中密度河蚬组(260 g/m2)和高密度河蚬组(520 g/m2).结果表明:河蚬滤食显著降低悬浮物浓度与叶绿素a含量,低、中、高密度河蚬组水体悬浮物浓度较对照组分别降低了20.85%、34.90%和53.79%,叶绿素a浓度分别降低了23.29%、48.32%和71.17%;放置河蚬还降低了水体TN、TP浓度,但是中密度河蚬组与高密度河蚬组没有显著差异.分析认为,河蚬通过滤食作用降低水体浊度、改善光照条件,有利于底栖藻类的生长及沉水植物的恢复,对富营养水体的生态修复具有重要意义;就太湖而言,河蚬对水质的改善效果可能受沉积物再悬浮造成的营养盐释放等因素的制约.  相似文献   

20.
Annual phytoplankton productivity in Lake Constance is about 300 g C m−2, a value typical for mesoeutrophic lakes. Seasonal variations in phytoplankton biomass and productivity are exceptionally great because of a sequence of factors controlling the production process. During winter productivity is controlled by low energy inputs and high respiratory losses due to deep water column mixing. Biomass is low and water transparancy high. The spring phytoplankton growth is triggered by the thermal stabilization of the water column. The summer phytoplankton biomass maximum mainly depends on phosphorus availability. However, biomass yields comprise only 15–20% of values to be expected from the Redfield ratio because large proportions of POM are detritus and non-algal biota. Moreover, sedimentation during the second half of the year removes biomass from the euphotic zone. Water transparency and thus vertical distribution of algal photosynthesis is highly dependent on phytoplankton biomass. Self-shading causes considerably smaller seasonal variations in areal biomass and photosynthetic rates than in volume-based values. By light-shade adaptation effects of seasonal fluctuations in mean daily surface radiance fluxes on algal photosynthesis can to a significant extent be compensated for. At any given level of biomass daylength is the major determinant of daily production rates. Dedicated to Professor Elster on his 80th birthday.  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