| Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance |
| |
| 摘 要： | 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 zero1]. 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…
|
| 收稿时间： | 25 August 2004 |
| 修稿时间： | 23 November 2005 |
Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance |
| |
| Authors: | ZHANG Yunlin QIN Boqiang HU Weiping WANG Sumin CHEN Yuwei CHEN Weimin |
| |
| Institution: | 1. Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China;Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
2. Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China |
| |
| Abstract: | By using the data of underwater irradiance measured in the different lake regions of Lake Taihu during 1998–2004 and total
suspended solids (TSS), wind speeds of the total 13 stations in typical lake regions during 1993–2003, this paper analyzes
the factors of influencing on PAR (photosynthetically available radiation) attenuation, euphotic depth, and presents the temporal
and spatial variations of euphotic depth of typical lake regions in Lake Taihu, and the spectral distributions of euphotic
depth at station 2. The results show that the concentration of TSS is the most important factor impacting PAR attenuation,
followed by chlorophyll a; chromophoric dissolved organic matter (CDOM) has little impact on the PAR euphotic depth. During 1993–2003, the mean yearly
PAR euphotic depths of the typical lake regions ranged from 1.04 to 1.95 m with a mean value of 1.35±0.23 m. The PAR euphotic
depth fell into 3 spatial zone types: Type I, the lowest, including the lake center and the inflows of rivers; Type II, intermediate,
including Meiliang Bay, Wulihu Lake and Gonghu Bay; Type III, the greatest, including the East Lake Taihu; corresponding mean
depths were approximately 1.1, 1.4, 2.0 m, respectively. The seasonal variations of euphotic depths were not quite the same
in different lake regions. In the lake center, the mean values of PAR euphotic depth in summer and autumn were significantly
greater than those in winter and spring; in the Meiliang Bay, winter means were significantly greater than in the other three
seasons; in the East Lake Taihu, winter means were significantly less than in the other three seasons. However, no distinct
seasonal change was recorded in the Wulihu Lake, Gonghu Bay and the inflows of rivers. The spectral distributions of euphotic
depth present a minimal value at the blue light wave band of 400 nm, and a peak at the green light wave band of around 580
nm. In 1998 and 1999, based on the seasonal many-day continuous measurements, the PAR euphotic depths at station 2 were recorded
2.00±0.21, 2.52±0.45, 1.58±0.24, 2.00±0.15 m in spring, summer, autumn and winter, respectively. The peak value of 440 nm
absorbed by phytoplankton corresponded to a euphotic depth of only 0.81–1.47 m (mean 1.07±0.29 m), which was much lower than
the mean PAR euphotic depth of 1.98±0.41 m. |
| |
| Keywords: | Lake Taihu euphotic depth diffuse attenuation coefficient total suspended solid ecologicalenvironmental significance |
| 本文献已被 万方数据 SpringerLink 等数据库收录！ |
|
