百年来海州湾沉积物中黑碳分布特征及环境意义

Distribution characteristics and environmental significance of black carbon in sediments of Haizhou Bay over 100 years

沉积物中黑碳记录了百年来区域生物质燃烧特征变化。本文以海州湾入海潮滩采集的岩芯沉积物样品为研究对象,采用热光反射法(TOR)分别对沉积物黑碳、焦炭和烟炱进行测定,分析探讨海州湾近百年来生物质燃烧演变过程。利用相关性分析、主成分分析和特征比值法分析黑碳含量的历史变化和可能来源,试图揭示该区域百年来能源结构的转变过程。结果表明,近百年来沉积物黑碳、焦炭、烟炱质量分数垂直变化幅度较大,分别在0.507~1.281 mg·g^(-1),0.395~1.080 mg·g^(–1),0.112~0.389 mg·g^(-1)范围内变化。其中,黑碳质量分数高值出现在20世纪80年代中后期(0.873~1.029 mg·g^(-1)),而低值出现在20世纪20年代到20世纪中叶期间(0.675~0.751 mg·g^(-1))。不同区域黑碳分布比较发现,我国东部边缘海地区比青藏高原和瑞典湖泊高出10倍,但发达国家黑碳通量峰值出现时间早,反映了黑碳沉积与区域工业化水平和人类活动相关性显著。黑碳特征比值法(char/soot)的源解析结果表明,黑碳的来源中化石燃料燃烧占48.8%,是生物质燃烧的4.2倍。根据相关性分析、主成分分析和char/soot比值结果分析,黑碳在1950年以前主要来源是生物质燃烧,在1950年以来煤炭燃烧、工业源、交通源比重增加,主要和区域人口、工业总产值、能源消费等因素有关,人类活动占据主导。研究结果为进一步理解该区域黑碳污染状况及制定未来海州湾地区的生态环境管理政策提供参考。

Black carbon in sediments has reflected changes in local biomass-burning characteristics for over a century.In this work,the progress of biomass burning in Haizhou Bay during the past 100 years was analyzed via independent measurement of sediment black carbon,char,and soot in sediment core samples using the thermal–optical reflectance(TOR)method.Furthermore,correlation analysis,principal component analysis,and the characteristic ratio approach were employed to discover the transformation of the region’s energy structure over the past century and examine histori-cal variations and potential sources of black carbon contents.The data demonstrated a remarkable vertical change in the mass fration of sediment black carbon,char,and soot over the past 100 years,revealing range variations of 0.507–1.281,0.395–1.080,and 0.112–0.389 mg·g^(-1),respectively.The highest concentrations of black carbon(0.873–1.029 mg·g^(-1))were recorded in the mid-late 1980s,whereas the lowest mass fration(0.675–0.751 mg·g^(-1))were reported in the 1920s and the middle of the 20th century.The peak black carbon flux in developed areas emerged earlier,reflecting the significant correlation between black carbon deposition,regional industrialization level,and human activities;for instance,the contents in China’s eastern marginal sea area are 10 times higher than those in the Qinghai-Xizang Plateau and Swedish lakes.The results of the source analysis using the char/soot characteristic ratio method revealed that black carbon sources from fossil fuel combustion represented 48.8%of the total,which was 4.2 times more than sources from biomass burning.Moreover,the results of the correlation analysis,principal component analysis,and char/soot ratio indicated the following.The main source of black carbon was biomass combustion before 1950,and the percentages of coal combustion,industrial sources,and transportation sources increased after 1950.The population of the region and the value of its gross industrial output,energy consumption,and other factors influenced these findings,and human activities predominated.The findings of this study serve as a guide for effective comprehension of the local black carbon pollution issues and the development of imminent ecological and environmental management strategies in the Haizhou Bay region.