共查询到18条相似文献，搜索用时 125 毫秒
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秋季太湖水下光场结构及其对水生态系统的影响 总被引：3，自引：1，他引：2
水生态系统中光能的分配很大程度上决定了水生态系统的结构和功能,利用2007年11-12月太湖水体光学特性和组分浓度数据,对秋季太湖水下光场结构特征和水体组分光竞争能力的表征光学量(漫衰减系数、平均余弦)和影响因素(吸收系数比重)进行了分析研究.结果表明,秋季太湖水下辐照度呈现单峰分布,最高值为583nm左右:根据Kd可将黄质和非色素物质主导程度的强弱分为弱、较强、强三个等级;Kd(PAR)平均值为4.61±1.54m-1,水体真光层厚度平均值为1.11±0.35m;太湖水下光场的光能主要分布在青光和黄绿光波长范围内,约占总能量的60%,蓝光和红光波长范围内的能量约占30%,这样的光谱结构有利于铜绿微囊藻和斜生栅藻的生长. 相似文献
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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
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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
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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
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长江中下游浅水湖泊沉积物再悬浮对水下光场的影响研究--以龙感湖和太湖为例 总被引：6，自引：0，他引：6
基于2003年7月在龙感湖、太湖梅梁湾以及2004年7月在太湖站栈桥的连续不同风浪条件下水下光场原位观测资料,分析风浪作用引起的沉积物再悬浮对PAR衰减,吸收系数及真光层深度的影响.结果表明,在龙感湖,小风浪、中风浪和大风浪的PAR衰减系数分别是1.74,2.02,2.45 m-1,400～700 nm光谱衰减系数变化范围分别为0.98～2.97,1.34～3.95,1.82～5.40 m-1;在太湖梅梁湾,小风浪、中风浪和大风浪PAR衰减系数分别是2.63,3.72,4.37 m-1,从小风浪到、中风浪、大风浪衰减系数分别增加了41％,66％;太湖站栈桥边PAR波段积分CDOM吸收系数在中风浪和大风浪的值分别为0.26,0.28 m-1,浮游植物吸收系数从中风浪到大风浪反而由0.76降低到0.49m-1,沉积物再悬浮引起非藻类颗粒物的吸收则由0.94增加到1.73 m-1,增加了84％,总悬浮物颗粒物吸收由1.70增加到2.22 m-1,增加了30.6％.非藻类颗粒物吸收对总吸收系数贡献最大,中风浪、大风浪下贡献率分别达44.14％,65.05％.龙感湖,梅梁湾,栈桥边3站点从中风浪到大风浪,PAR真光层深度分别降低0.40,0.19,0.20 m.透明度、PAR衰减系数、真光层深度与悬浮物浓度、风速、波高等均存在显著性线性相关,并且与悬浮物中无机颗粒物相关性最好,而与叶绿素a、脱镁叶绿素及溶解性有机碳相关性很低.由此可见,在龙感湖和太湖等长江中下游浅水湖泊,风浪扰动引起悬浮物浓度的增加尤其是无机颗粒物的增加是影响水下光场的主导因素. 相似文献
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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
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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
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Zhang Yunlin Qin Boqiang Zhu Guangwei Gao Guang Luo Liancong Chen Weimin 《中国科学D辑(英文版)》2006,49(1):114-125
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 particulate matter, wind velocity, wave height. Most significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and inorganic suspended particulate matter but low correlations for chlorophyll a, dissolved organic carbon. Increase of total suspended particulate matter, especially inorganic suspended particulate 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
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D.A. Pilgrim 《Continental Shelf Research》1987,7(11-12)
Measurement of the depth-mean PAR (photosynthetically active radiation) extinction coefficient, ° Ko, is important in the study of estuarine productivity. Measurements of ° Ko, beam attenuation coefficient and Secchi disc depth are presented for the turbid waters of the Tamar Estuary. Equations are formulated which allow good estimates of ° Ko to be determined both from the beam attenuation coefficient (at 660 nm) and from the Secchi disc depth. For comparison, similar data are presented for the clearer waters of the northeast Atlantic. 相似文献
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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
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Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance 总被引：5，自引：0，他引：5
ZHANG Yunlin QIN Boqiang HU Weiping WANG Sumin CHEN Yuwei CHEN Weimin 《中国科学D辑(英文版)》2006,49(4):431-442
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
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《Limnologica》2020
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
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湖泊光学研究进展及其展望 总被引：11，自引：4，他引：7
从湖泊光学研究理论框架、研究方法、水体生物光学特性、有色可溶性有机物(CDOM)生物地球化学循环、光与浮游植物相互关系、沉积物再悬浮光学效应、湖泊水色遥感等几个方面全面回顾了湖泊光学研究进展.湖泊光学研究理论框架主要包括各光学组份吸收、散射、漫射衰减及辐射传输方程;近年来,逐步发展了野外时空格局调查、水动力水华过程连续... 相似文献
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本文首先由Christoffel方程推导出黏弹性EDA介质中均匀、 非均匀P波、 SV波和SH波的相速度表达式, 然后参照极端各向异性介质的相关计算方法, 推导出EDA介质中均匀、 非均匀地震波相衰减系数和群衰减系数的表达式, 并通过数值计算分析了相速度、 相衰减系数、 群衰减系数与裂隙方位的关系. 结果表明: 均匀介质中SH波的相速度和相衰减系数均可指示裂隙的走向; 非均匀介质中SH波相衰减系数随非均匀角的增大而增大, 且其对称轴与介质对称轴的夹角也相应增加; 由于地震波振幅的衰减随岩石物理性质的变化比地震波速度的变化更为灵敏, 而且携带了更多的岩石物理性质信息, 因此可用来探明裂隙走向、 密度及含水特性, 进而应用于预测、 预防地下工程地质灾害事故. 相似文献