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31.
Preliminary study on the dissolved and colloidal organic carbon in the Zhujiang River estuary 总被引:3,自引:0,他引:3
INTRODUCTIONEstuariescompriseamajorbiogeochemicalinterfaceconnectingthelandandthesea (Man toura,1 987) .Thebehaviorandfateofaparticularriver bornesubstanceintroducedintoanestuaryisdeterminedtoalargeextentbythebiogeochemicalpropertiesofthesubstanceaswellasp… 相似文献
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Sulfotransferase (ST) is the first enzyme discovered in association with paralytic shellfish poisoning (PSP) toxin biosynthesis in toxic dinoflagellates. This study investigates the ST activity in crude enzyme extraction of a toxic dinoflagellate species, Alexandrium tamarense CI01. The results show that crude enzyme can transfer a sulfate group from 3’-phosphoadenosine 5’-phosphosulfate (PAPS) to N-21 in the carbamoyl group of gonyautoxin 2/3 (GTX2/3) to produce C1/C2, but is inactive toward STX to produce GTX5. The crude enzyme is optimally active at pH 6.0 and 15°C. The activity is enhanced by Co2 , Mg2 , Mn2 and Ca2 individually, but is inhibited by Cu2 . Moreover, the activity shows no difference when various sulfur compounds are used as sulfate donors. These results demonstrate that the ST specific to GTX2/3 is present in the cells of A. tamarense CI01 and is involved in PSP toxin biosynthesis. In addition, the ST from different dinoflagellates is species-specific, which explains well the various biosynthesis pathways of the PSP toxins in toxic dinoflagellates. 相似文献
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A VERTICAL DISTRIBUTION MODEL OF NUTRIENTS AND DISSOLVED OXYGEN IN THE SOUTHERN TAIWAN STRAIT 总被引:3,自引:0,他引:3
Sinoe vertical transport of nutrients and dissolved oxygen are quite important in the water col-umn and have drawn serious attention these recent years, a one-dmension numerical model is tried to simulate the vertical distribution of nutrients and dissolved oxygen in June at two research sites in the southemTaiwan Strait. Physical transport parameters are calibrated by temperature simulation, and thenare used to simulate the profiles of NO_3, PO_4 and dissolved oxygen. The simulation was generally success-ful for both stations. The importance of various factors, such as upwelling tidal current andbiogeochemical activities, which influence the vertical distribution of nutrients and dissolved oxygen, is revealed by analysis of the modeling results. Some important rates, fluxes and ratios are also estimated anddiscussed on the basis of simulation. 相似文献
34.
Study on respiratory electron transport system (ETS) of phytoplankton in Taiwan Strait and Xiamen Harbour 总被引:1,自引:0,他引:1
Phytoplankton respiratory electron transport system (P-ETS) activities were studied in two cruises in Taiwan Strait (Aug. 1997 and Feb. -Mar.1998) and two cruises in Xiamen Harbour (Oct., 1997 and Apr.,1998). Results showed that P-ETS activity in the surface water of southern Yaiwan Strait in summer was homogeneous [mean value of 0.106 μ102/(L.h)], inhomogeneous in northern Yaiwan Strait in winter. Variation of P-ETS activity in middle part of the Strait was not obvious between summer and winter. Mean P-ETS activity of Xiamen Harbour in autumn was 0.255 μ102/(L.h) with a little higher value in Jiulong River estuary areas. In spring, P-ETS activity was more homogeneously distributed and the mean value was 1.076 μ102/(L.h). P-ETS activity in spring was obviously higher than in autumn in Xiamen Harbour. Vertical distribution of P-ETS in Taiwan Strait was homogeneous at some stations in winter and in summer. An obvious daily variation of P-ETS activity was recorded at Stn 9837, high at midnight and low in the early morning. Significant correlation between P-ETS activity and Chl-a was observed. Results also showed that the ratio of estimated respiratory rate to photosynthetic rate varied seasonally, high in winter (0.41) and low in summer (0.12). 相似文献
35.
台湾海峡真光层有机碳动力学研究──DOC大幅度的日变化 总被引:3,自引:0,他引:3
1994年8月和1995年2月在台湾海峡对DOC作定点连续观测,发现DOC日变化很大(2~4mg/dm3),且变化的幅度有季节差异和空间差异;DOC昼夜变化的总的规律是白天比晚上高,夜晚始终处于低值;依据DOC的昼夜变化可将DOC分为DOCnew和DOCold两部分;D0Cnew在真光层中快速地产生、消耗、再循环;DOCold则相对稳定,可从真光层底部输出;DOC的快速变化表明DOC的产生和被细菌消耗利用的速度都非常快.文中还尝试快速富丽叶变换(FFT)来分离引起DOC日变化的物理因子和生物因子,并依据实验结果讨论了初级生产力,微生物对DOC的利用,DOC输出生产力等问题. 相似文献
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珠江口伶仃洋海区表层沉积物稀土元素分布特征及配分模式 总被引:12,自引:2,他引:12
珠江口伶仃洋海区表层沉积物中的稀土元素的含量变化范围较大(170.34~344.60μg/g),平均含量为272.02μg/g,远高于陆壳平均含量(200μg/g)和华南地区花岗岩中稀土元素的平均含量,接近于全球沉积物平均稀土元素含量上限。以轻稀土富集为主,富集系数在1.51~2.43之间。经北美页岩标准化后,伶仃洋海区沉积物配分模式呈负斜率配分型;与南海沉积物中稀土分布具有相似性,说明二者具有同源性。 相似文献
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