摘要:
研究测定了百朗地下河大石围天坑段沉积柱芯中金属元素和沉积有机质(SOM)浓度,结合210 Pb定年和历史事件记载,恢复了1932-2007年间百朗地下河流域的污染历史.研究结果表明,地下河沉积柱中主要有毒重金属Cd、Hg分别超过广西土壤背景值3.4和0.6倍,超过中国土壤背景值11.2和2.7倍;1932年至2007年间;总体上沉积柱中各重金属元素的垂直分布趋势相似,呈现不同程度的上升趋势;并推演了历史上农民运动、抗日战争、大跃进、改革开放初期和经济快速发展期等事件是造成百朗地下河流域金属元素变化的主要原因;尤其是沉积柱中钙与镁的垂直变化显示了1983年以来流域岩溶石山地区进入一个新的建设高潮.相关性分析和聚类分析表明,Cr、Pb主要来源于自然环境;Fe、Cu、Ni、Zn、As、MgO来源为自然和人为混合源;Cd、Hg、Mn、CaO和SOM主要来源于人为污染源;与多环芳烃相关性分析显示Zn、Cd和As部分来源为人为的燃煤污染.因此沉积柱较好地记录了百朗地下河流域重金属污染历史.
Abstract:
In this work,the concentration of metal elements and sediment organic matter (SOM)in sediment cores of the Dashiwei sinkhole section from the Bailang underground river has been studied,and the pollution history of the river basin from 1932 to 2007 has been reconstructed by combining the 210 Pb dating and histori-cal records.The results show that concentrations of main toxic heavy metals Cd and Hg in the sediment cores are high,which are 3.4 and 0.6 times than the soil background values of Guangxi,respectively,even more than 11.2 and 2.7 times of the soil background value throughout China,respectively.On the whole, the distributions of heavy metal elements have a similar increase tendency in the sediment cores.The vertical distribution of metal elements in the sediment cores shows that metal element pollution in the underground river were associated with many events in history,such as peasant movement,the war of Anti-Japanese, Great Leap Forward age,the early stage of reform and opening up ,and the rapid development of economy. Especially,the vertical variation of Ca and Mg in the sediment core records indicates that a new construction climax has begun in this karst mountain area since 1983.Correlation and clustering analyses show that,(1) Cr and Pb came mainly from natural environment,(2)Cu,Ni,Zn,As and MgO originated from natural en-vironment and artificial sources,(3)Cd,Hg,Mn,CaO and SOM stemmed from artificial pollution sources. Correlation analysis with polycyclic aromatic hydrocarbons suggests that part of Zn,Cd and As came from coal combustion.In a nutshell,metal elements in the sediment cores better recorded pollution history of the Bailang underground river.
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