Diffuse attenuation coefficients Kd(PAR) at the estuarine North Sea–Baltic Sea transition: time-series, partitioning, absorption, and scattering
Diffuse attenuation coefficients Kd(PAR) at the estuarine North Sea–Baltic Sea transition: time-series, partitioning, absorption, and scattering
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DOI：
10.1016/j.ecss.2004.05.004
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发表时间：
2004-10
影响因子：
2.8
通讯作者：
L. Lund-Hansen
中科院分区：
文献类型：
--
作者：
L. Lund-Hansen
该研究是基于一个1年的记录（n=46）的扩散衰减系数Kd（PAR）（m−1）-结合CTD-在一个位置在卡特加特海峡，北海-波罗的海河口过渡的阿洛胡斯湾铸造。不定期采集水样，测定悬浮颗粒物（SPM）和有色形态溶解有机物（CDOM）。Kd（PAR）在0.152 ~ 0.557（m−1）之间变化，平均值为0.293（m−1）。透光区的深度（1%光照水平）在8.3和15.7米之间变化，最大和平均Kd（PAR）。最大的Kd（PAR）值发生在高浓度的chl-a的时期。CDOM的平均吸收系数为0.232（m−1），而叶绿素a和无机SPM的平均浓度分别为3.3（mg m−3）和4.5（g m−3）。在平均条件下，光衰减分配百分比为：水（9），CDOM（17），SPM（42）和浮游植物（32）。浮游植物的衰减达到74%，在高叶绿素a浓度，而SPM光衰减达到45%，在高SPM浓度。结果表明，在海湾的光衰减是由浮游植物和SPM浓度，而CDOM的意义不大。PAR范围内的光吸收a（PAR）-介于平均条件下的0.262（m−1）和浮游植物最大浓度下的0.49（m−1）之间。在平均条件下，散射由SPM控制，而在chl-a浓度>4.5（mg m−3）时，浮游植物散射高于SPM散射。
The study is based on a 1 year record (n=46) of the diffuse attenuation coefficient—Kd(PAR) (m−1)—in combination with CTD-casts at one position in Århus Bay, Kattegat, the North Sea–Baltic Sea estuarine transition. Water samples were collected occasionally for determination of suspended particulate matter (SPM) and chromomorphic dissolved organic matter (CDOM). The Kd(PAR) varied between 0.152 and 0.557 (m−1) with an average of 0.293 (m−1). The depth of the photic zone (1% light level) varied between 8.3 and 15.7 m at maximum and average Kd(PAR). Maximum Kd(PAR) values occurred in periods of high chl-a concentrations. The average CDOM absorption coefficient was 0.232 (m−1) whereas the average chl-a and inorganic SPM concentrations equalled 3.3 (mg m−3) and 4.5 (g m−3). Light attenuation partitioning in percent was: water (9), CDOM (17), SPM (42), and phytoplankton (32) at average conditions. Attenuation by phytoplankton reached up to 74% at high chl-a concentrations whereas SPM light attenuation reached 45% at high SPM concentrations. Results show that light attenuation in the bay is governed by phytoplankton and SPM concentrations whereas CDOM is of less significance. Light absorption in the PAR range—a(PAR)—ranged between 0.262 (m−1) at average conditions and 0.49 (m−1) at maximum phytoplankton concentrations. Scattering was governed by SPM at average conditions whereas phytoplankton scattering was higher than SPM scattering at chl-a concentrations >4.5 (mg m−3).