東海和黃海表層沉積物中類(lèi)脂生物標(biāo)志物的分布特征和古生態(tài)重建

1、東海和黃海表層沉積物中類(lèi)脂生物標(biāo)志物的分布特征和古生態(tài)重建        【中文摘要】多參數(shù)生物標(biāo)記物法已被廣泛用于重建浮游植物生產(chǎn)力和種群結(jié)構(gòu),其比值可以用來(lái)反映浮游植物種群結(jié)構(gòu)。但目前還缺乏這一應(yīng)用的現(xiàn)代證據(jù),尤其是西太平洋邊沿海地區(qū)。本文通過(guò)對(duì)東/黃海陸架區(qū)表層沉積物樣中的生物標(biāo)志物進(jìn)行分析來(lái)確證生物標(biāo)志物方法在邊沿海區(qū)域的應(yīng)用。同時(shí)我們也對(duì)東/黃海沉積物柱狀樣進(jìn)行生物標(biāo)志物分析,對(duì)200年以來(lái)古表層海水溫度、海洋低級(jí)生產(chǎn)力及浮游植物種群結(jié)構(gòu)的變化近行探討。主要研究結(jié)果如下:1.表層沉積物生物標(biāo)志物的分布特征

2、東/黃海表層沉積物中生物標(biāo)志物總量分布具有近岸高,離岸低的趨勢(shì)。這主要是由于陸源輸送營(yíng)養(yǎng)鹽而引起的高低級(jí)生產(chǎn)力所導(dǎo)致。所以沉積物中生物標(biāo)志物含量可以用來(lái)半定量的重建古生產(chǎn)力的變化。東/黃海表層沉積物中生物標(biāo)志物比例被用來(lái)作為生物種群的替換指標(biāo),其變化趨勢(shì)與已有資料相符,既長(zhǎng)江口方向離岸越遠(yuǎn)菜子甾醇比例下降,長(zhǎng)江口以南離岸越遠(yuǎn)菜子甾醇比例升高,長(zhǎng)江口以北生物標(biāo)志物比例變化不明顯;黃海浮游植物種群結(jié)構(gòu)總體呈現(xiàn)顆石藻比例由西向東升高,硅藻比例由西向東降低的趨勢(shì)。但東/黃海表層沉積物中生物標(biāo)志物所重建的生物種群結(jié)構(gòu)的盡對(duì)值與現(xiàn)有資料存在差異。與現(xiàn)代的表層海水年均勻溫度相比,東/黃海U_(37)(K&#

3、39;)-SST高于現(xiàn)代年均勻溫度,且東海的差距要大于黃海。東海的U_(37)(K')-SST與其夏季的均勻溫度接近,而黃海U_(37)(K')-SST與其秋季的均勻溫度接近。由于U_(37)(K')-SST重建受顆石藻種類(lèi)及其生產(chǎn)力的季節(jié)性變化等因素的影響,上述溫度的差異可能與顆石藻種類(lèi)和生產(chǎn)力的季節(jié)性變化有關(guān)。2東海和黃海古生態(tài)研究利用長(zhǎng)鏈不飽和烯酮獲取了210年來(lái)黃海古表層海水溫度(SST),10694溫度變化范圍為13.517.5,其均勻值為15.4。從210年來(lái)溫度逐漸降低持續(xù)降低,在168年溫度降低至13.9,而后溫度略有波動(dòng),在104年前溫度降至最低13.

4、5,隨后溫度快速上升。對(duì)生物標(biāo)志物的研究表明:黃海過(guò)往的200多年來(lái),海洋低級(jí)生產(chǎn)力呈上升趨勢(shì);同時(shí)陸源生物標(biāo)志物中的正構(gòu)醇含量也是呈上升趨勢(shì)。這表明生產(chǎn)力的增加可能與陸源輸進(jìn)增多有關(guān),而陸源輸進(jìn)增多有可能與東亞冬季風(fēng)的變化有關(guān)。東海過(guò)往130年來(lái)海洋低級(jí)生產(chǎn)力也呈現(xiàn)上升趨勢(shì),這種生產(chǎn)力的上升可能與人類(lèi)活動(dòng)有關(guān)。對(duì)東/黃海浮游植物種群結(jié)構(gòu)的研究發(fā)現(xiàn):南黃海10694巖芯浮游植物種群結(jié)構(gòu)從在210約100年前,顆石藻相對(duì)比例下降,甲藻增大,硅藻比例在低值波動(dòng)。此后約100年間,甲藻相對(duì)比例快速下降的,硅藻的相對(duì)比例迅速增大,顆石藻相對(duì)比例處于低值。東海陸架H1-18巖芯浮游植物種群結(jié)構(gòu)在過(guò)往的1

5、30年以來(lái),主要表現(xiàn)在顆石藻和硅藻減少,甲藻相對(duì)含量上升。黃海與東海的生態(tài)結(jié)構(gòu)的不同變化趨勢(shì)與天氣變化和人類(lèi)活動(dòng)對(duì)它們的影響不同有關(guān)。');【Abstract】 Multi-biomarkers have been applied for the reconstruction of phytoplankton productivity and community structure. Their ratios can be used for community structure reconstruction. However there is not sufficient evide

6、nce to verify this method, especially in the marginal seas of the West Pacific. In this *, the distributions of biomarkers in su*ce sediments of the East China Sea and the Yellow Sea were studied to further validate the use of biomarkers in the studied area. And we also carries out the analysis of b

7、iomarkers in core drilled from the East China Sea and the Yellow Sea, and discuss the variations of biomarker-based records for the past 200y: sea su*ce temperature (SST), marine productivity and community structure.1. The distribution of biomarkers in su*ce sedimentsThe results indicate the content

8、s of biomarkers (C37alkenones, brassicasterol and dinosterol) of the East China Sea ranged from 357 to 3115ng/g. The contents biomarkers of the Yellow Sea varied between 2898 and 6714ng/g .The results show that total phytoplankton biomarker contents decrease away from the coast, consistent with resu

9、lts from modern water column phytoplankton surveys. And the varieties are caused by higher productivity brought from the terrestrial input. So the contents of biomarkers from sediments can be used for semi-quantitative reconstruction of paleoproductivity.The biomarker ratio can be used as the proxie

10、s of phytoplankton community structure, and the biomarkers ratio shows that the relative diatom contribution decreased away from the Changjiang River mouth, but in the southern part of the East China Sea, the relative diatom contribution increased away from the coast. Coccolithophorid contribution w

11、as minor, but reveals a trend of increases with depth. These biomarker-based community structure trends are in agreement with field survey result, but the absolute values by the two methods differ.Compared with modern mean annual temperature, theU_(37)(K')-SST is higher in the East China Sea and

12、 the Yellow Sea. TheU_(37)(K')-SST in the East China Sea is similar to the mean temperature in summer, but U_(37)(K')-SST in the Yellow Sea accords with the mean temperature in autumn. These differences may be correlated with the species of coccolithforid and the seasonal variety of producti

13、vity and the calibration of U_(37)(K')-SST equation.2 Paleoecology Reconstruction of the East China Sea and the Yellow SeaThe U_(37)(K')-SST in the Yellow sea varied from 13.5 to 17.5over the last 210y, and the mean value was 15.4. The lowest SST (13.5) appeared at 104y before present, and t

14、hen SST increased rapidly.Marine phytoplankton productivity in the Yellow Sea reveals a increasing trend which is similar to the trend of the contents of alcohols indicating terrestrial input during the past 200y,. The changes of productivity in the Yellow Sea could be controlled by winter monsoon.

15、Similarly, the productivity in the East China Sea increased over the last 130y. The productivity changes in the East China Sea probably relates to human activity.The reconstructed phytoplankton community structure shows obvious variations in the Yellow Sea. The contributions of coccolithforids decre

16、ased, and the contributions of dinoflagellates increased, and the relative abundances of diatoms varied at low values from 210 to 100y before present. During the last 100y, the ratios of coccolithforids were low, the contributions of dinoflagellates decreased rapid, and that of diatom increased. Over the last 130y, the biomarker ratios show that the relat