广西北海市南岸滩涂主要大型植物及表层沉积物的稳定性碳和氮同位素丰度

The Abundance of Carbon and Nitrogen Stable Isotope of the Important Plant and Sediment in Inter-tidal Zone of the South Coast of Beihai,Guangxi

关键词:  北海市南岸  滩涂  植物  沉积物  碳稳定性同位素  氮稳定性同位素

Key words:  south coast of Beihai  intertidal zone  plant  sediment  carbon stable isotope  nitrogen stable isotope

摘要:

为调查广西北海市南岸滩涂主要大型植物和表层沉积物的稳定性碳和氮同位素丰度，并为沿海滩涂动物食物与营养来源研究提供数据，采用野外现场采样和室内样品处理检测结合的方法，对山口镇英罗村、北暮盐场、营盘镇青山头村、竹林盐场、大冠沙等5个地点采集到的红树落叶（秋茄Kandelia candel和白骨壤Avicennia marina）、互花米草Spartina alterniflora、条浒苔Enteromorpha clathrata、细基江蓠Gracilaria tenuistipitata及表层沉积物样品进行处理，测定总有机碳（TOC）、总氮（TN）、稳定性碳同位素丰度（δ¹³C）和稳定性氮同位素丰度（δ¹⁵N），并进行统计分析与比较。结果显示，山口镇英罗村和大冠沙红树落叶的δ¹³C和δ¹⁵N均没有显著差异，北暮盐场和营盘镇青山头村互花米草的δ¹³C和δ¹⁵N也没有显著差异。5个地点表层沉积物的TOC、TN、δ¹³C、δ¹⁵N均没有显著差异，表明北海市南岸滩涂表层沉积物的TOC、TN、δ¹³C、δ¹⁵N分布较为均匀。沿海滩涂高等植物的δ¹³C主要受均匀的大气影响，不同区域和地点间差异较小，因此不同地点高等植物红树和互花米草的δ¹³C变幅也较小。本次调查的北海南岸沿岸较为开阔，并且没有大型河流注入，因此滩涂沉积物中δ¹⁵N差异较小。由于植物对氮同位素吸收没有分馏作用，本次调查中不同地点的红树和互花米草δ¹⁵N差异也很小。山口镇英罗村、北暮盐场、竹林盐场和大冠沙的条浒苔δ¹³C没有显著差异，但δ¹⁵N有显著差异，竹林盐场的条浒苔δ¹⁵N显著低于北暮盐场。北暮盐场和营盘镇青山头村的细基江蓠δ¹³C没有显著差异，竹林盐场的细基江蓠δ¹³C显著低于另外两个地点；3个地点的δ¹⁵N均没有显著差异。不同地点大型海藻的δ¹³C或δ¹⁵N差异出现的原因有待进一步研究。本研究结果为分析北海南岸大型植物和沉积物对滩涂饵料和营养来源的影响提供了参考数据。

Abstract:

In order to investigate the abundance of carbon and nitrogen stable isotope of the important plant and sediment in inter-tidal zone of the south coast of Beihai,Guangxi,and to provide data for the study the food and nutrition sources of the animals inhabited in inter-tidal zone,the research adopted a combination methods of field sampling and indoor treating and measuring of samples.The samples of mangrove leaves (Kandelia candel and Avicennia marina),Spartina alterniflora,Enteromorpha clathrata,Gracilaria tenuistipitata, and sediments collected from five sites of Yingluo Village of Shankou Town,Saltern of Beimu,Qingshantou Village of Yingpan Town,Saltern of Zhulin,and Daguansha were processed to measure the contents of total organic carbon (TOC,%),total nitrogen (TN,%),abundance of stable isotope of carbon δ¹³C,‰),and abundance of stable isotope of nitrogen (δ¹⁵N,‰),and the statistical analysis and comparison were performed.The results showed that the δ¹³C of mangrove leaves at Yingluo Village of Shankou Town and Daguansha showed no significant difference between sites.The δ¹³C of Spartina alterniflora at Saltern of Beimu and Qingshantou Village of Yingpan Town were not obviously different from each other.The TOC,TN,δ¹³C,and δ¹⁵N of the surface sediments at the five sampling sites were not significantly different,indicating that the TOC,TN,δ¹³C,and δ¹⁵N of the surface sediments on the south coast of Beihai City were relatively evenly distributed.The δ¹³C of higher plants along the beach was mainly affected by the even atmosphere,and the difference between different areas and sites was small.Therefore,the δ¹³C of higher plants of mangroves and S.alterniflora in different locations also varied slightly.The southern coast of Beihai in this survey was relatively open and there was no large river inflow to it,so the difference of δ¹⁵N in tidal flat sediment was small.Since plants had no fractional distillation on nitrogen isotope absorption,the difference in δ¹⁵N between mangroves and S.alterniflora in different locations in this survey was also very small.There was no significant difference in the δ¹³C of E.clathrata in Yingluo Village,Beimu Saltworks,Zhulin Saltworks and Daguansha,but there was a significant difference in δ¹⁵N.The δ¹⁵N of E.clathrata in Zhulin Saltworks was significantly lower than that in Beimu Saltworks.There was no significant difference in the δ¹³C of G.gracilis in Beimu Salt Farm and Qingshantou Village of Yingpan Town.The δ¹³C of G.gracilis in Zhulin Salt Farm was significantly lower than that of the other two sites.There was no significant difference in δ¹⁵N of the three sites.The reasons for the difference of δ¹³C or δ¹⁵N of macroalgae between different sites need to be further studied.The results of this study provide reference data for analyzing the effects of macrophytes and sediments on the tidal flat bait and nutrient sources on the southern coast of the North Sea.