应用有机碳同位素技术研究湛江湾生态环境的变化过程

随着工业化进程的加快,湛江湾的生态环境承载力受到了极大的考验。为了解湛江湾生态环境的变化过程,文中利用湛江湾表层柱状沉积物样品中总有机碳含量(TOC)及其稳定同位素、总氮含量(TN)和C/N值的测定,结合端元混合模型,分析了湛江湾沉积物中有机质的来源,探讨了沉积物有机碳同位素的主要影响因素。结果表明,湛江湾沉积物中有机质主要来源为自生藻类,同时也受一定程度陆源输入的影响。沉积序列的元素地球化学参数表明,沉积物δ13C值呈现短暂的负偏随后长期正偏的趋势。底部的负偏可能与大气CO2浓度增加有关,随后δ13C主体正偏的趋势主要受控于气候转暖、生产力增加以及富营养化程度增加的共同影响,暗示了人类活动对湛江湾的生态环境的影响逐渐加剧。其中,人类活动相关的工业、农业有机污染物排放可能是不断加剧海水富营养化的主要原因。

Study on the Change Process of the Ecological Environment in the Zhanjiang Bay through the Organic Carbon Isotope Technique

With the acceleration of industrialization,the carrying capacity of the ecological environment in the Zhanjiang Bay has been under great challenge.To understand the change process of the ecological environment in the Zhanjiang Bay,this study used total organic carbon content(TOC)and its stable isotopes,total nitrogen content(TN)and C/N in the surface columnar sediment samples of the Zhanjiang Bay,combined with the end-element mixed model,to analyze the source of organic matter in the sediments of Zhanjiang Bay and the main influencing factors of organic carbon isotopes in the sediments.The results show that the organic matter in the sediments of Zhanjiang Bay mainly come from authigenic algae and is also affected by terrestrial input to a certain extent.The element geochemistry parameters in sedimentary sequence show a short negative excursion inδ13C followed by an increasing trend of theδ13C value.The negative excursion at the bottom of the section may be related to an increase in the atmospheric CO2 concentration.The positive excursion in theδ13C value is mainly controlled by the combined effects of climate warming,productivity increase and eutrophication degree,which indicate that the influence of human activities on the ecological environment of Zhanjiang Bay is gradually aggravated.Among them,organic pollutant emissions from industrial and agricultural discharges related to human activities may constitute the main reason for increasing eutrophication of the sea water.