湘江湘潭段河床沉积物元素地球化学特征

发布时间：2018-11-15 12:45

【摘要】：本研究利用X射线荧光仪(XRF)和电感耦合等离子质谱仪(ICP-MS)分析技术,对湘江湘潭段河床沉积物主量元素和微量元素进行地球化学分析。结果表明,研究区沉积柱主量元素含量变化相对稳定,其中SiO2、Al2O3、Fe2O3、K2O、MgO、TiO2、Na2O的变化系数皆小于0.2。河床沉积物经历了中等风化程度,表现为:大量Na、Ca被淋失,且投影点有沿着A-K线向A端富集的趋势,表明着沉积物钾长石已得到初步的风化,并且表现出脱K富Al的趋势。重金属污染富集系数表明沉积物重金属元素V、Cr、Cu、Th、U为中度污染程度,Mn、Zn、Pb达到严重污染程度。稀土元素配分模式中表现为轻稀土元素富集、重稀土元素亏损;轻稀土元素有较高的分馏程度,而重稀土元素却有较低的分馏程度,Eu元素表现出明显的负异常。研究区沉积柱稳定元素地球化学特征,推断湘潭段的沉积物物源主要是由上游的花岗岩和沉积岩等多元物源风化而来。地累积指数评价湘潭河段沉积物重金属污染表明,研究区沉积物Ba元素为清洁无污染。重金素元素Sc、Cr、Co、Ni、Th、U、V为轻度污染。重金属Mn、Pb、Zn元素介于偏中度污染等级到中度污染等级之间。沉积物矿物分析结果显示,湘江湘潭段沉积物中矿物主要由石英、粘土矿物(伊利石、高岭土)、磁铁矿、长石(正长石、钙长石、钠长石)、钛铁矿、锆石、紫苏辉石、磷灰石、金红石云母,橄榄石、角闪石、软锰矿、石灰岩等矿物组成。湘江湘潭段沉积物重金属的赋存状态分析显示,轻度污染的重金属元素中Sc、Co、Ni、V、Co可能赋存在粘土矿物、磷灰石中,较容易被释放出来,Th、U赋存在钛铁矿或者金红石中,重金属的活性会大大减弱。偏中度污染重金素元素Cu、Pb、Zn与各主量元素相关性都比较弱,可能为人为源引起的,应引起注意。Mn为中度污染可能与当地富集富含Mn的矿物有关。综上所述,重金属Cu、Pb、Zn、Mn污染应引起关注。
[Abstract]:The main elements and trace elements of Xiangtan river sediment in Xiangjiang River were analyzed by means of X-ray fluorescence instrument (XRF) and inductively coupled plasma mass spectrometer (ICP-MS). The results show that the main element content of the sedimentary column in the study area is relatively stable, in which the variation coefficient of SiO2,Al2O3,Fe2O3,K2O,MgO,TiO2,Na2O is less than 0.2. The sediment of river bed experienced moderate weathering, which showed that a large amount of Na,Ca was eluted, and the projection point was enriched to A terminal along A-K line, which indicated that the potassium feldspar in sediment had been preliminarily weathered. And show the trend of K rich Al. The enrichment coefficient of heavy metal pollution indicated that the heavy metal element VCU was moderately polluted, while Mn,Zn,Pb reached a serious pollution level. In the REE partition model, the REE is enriched and the heavy REE is depleted, the LREE has a higher fractionation degree, but the heavy REE has a lower fractionation degree, and the Eu element shows a negative anomaly. Based on the geochemical characteristics of stable elements in sedimentary columns in the study area, it is inferred that the sediment provenance in Xiangtan section is mainly weathered from the upper reaches of granite and sedimentary rocks. The evaluation of heavy metal pollution in Xiangtan reach shows that the Ba element in the sediment of the study area is clean and pollution-free. The heavy element Sc,Cr,Co,Ni,Th,U,V was slightly polluted. Heavy metal Mn,Pb,Zn elements ranged from moderate to moderate pollution levels. The results of sediment mineral analysis show that the minerals in Xiangtan section of Xiangjiang River are mainly composed of quartz, clay minerals (Illite, kaolin), magnetite, feldspar (orthoclase, calcium feldspar, albite), ilmenite, zircon, perilla pyroxene, etc. Apatite, rutile mica, olivine, hornblende, pyrolusite, limestone and other mineral composition. The analysis of the occurrence of heavy metals in the Xiangtan section of Xiangjiang River shows that Sc,Co,Ni,V,Co may occur in clay minerals, apatite and Th, in the mildly polluted heavy metals. U occurs in ilmenite or rutile, and the activity of heavy metals decreases greatly. The correlation between heavy gold element Cu,Pb,Zn and major elements is relatively weak, which may be caused by human being and should be paid attention to. The moderate pollution of Mn may be related to the enrichment of Mn rich minerals in the area. In conclusion, heavy metal Cu,Pb,Zn,Mn pollution should be concerned.
【学位授予单位】：湖南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X142;X52

【引证文献】