三峡水库消落带植物汞的分布特征

Distribution of Mercury in Plants at Water-Level-Fluctuating Zone in the Three Gorges Reservoir

以三峡库区重庆段忠县石宝寨、涪陵珍溪和开县汉丰湖消落带为主要研究地点,调查并采集了植物样品,分析样品总汞和甲基汞,探讨三峡水库消落带植物汞的分布特征及植物汞库存量.结果表明,调查区域消落带植物总汞含量在(1.62±0.57)^(49.42±3.93)μg·kg-1范围,植物各部位总汞的含量呈根>叶>茎的趋势分布;植物甲基汞含量在(15.27±7.09)^(1 974.67±946.10)ng·kg-1范围,植物根部甲基汞含量高于茎和叶.同类植物中,开县汉丰湖消落带植物总汞和甲基汞含量均较忠县石宝寨、涪陵珍溪镇消落带植物略高;不同高程植物总汞及甲基汞储存量存在差异,145~150、150~160、160~170和170~175 m高程的植物总汞储存量分别为145.3、166.4、124.3和88.2 mg·hm-2,甲基汞储存量分别为1.9、2.7、3.6和3.2 mg·hm-2.消落带优势种植物对总汞的富集能力相对较弱(BAF<1),而对甲基汞的富集能力相对较强(BAF>1).

The mercury( Hg) distribution and storage in plants at water-level-fluctuating zone( WLFZ) in the Three Gorges Reservoir were investigated by analyzing the total mercury( THg) and methylmercury( Me Hg) levels in different parts of plants collected from three typical sites including Shibaozhai,Zhenxi and Hanfeng Lake in WLFZ. The results indicated that THg and Me Hg concentrations in plants ranged from( 1. 62 ± 0. 57) to( 49. 42 ± 3. 93) μg·kg- 1and from( 15. 27 ± 7. 09) to( 1 974. 67 ± 946. 10) ng·kg- 1,respectively. In addition,THg levels in different plant parts followed the trend: root > leaf > stem,and similar trend for Me Hg was observed with the highest level in root. An obvious spatial distribution was also found with the THg and Me Hg levels in plants in Hanfeng higher than those in the same plants in the other two sampling sites( Shibaozhai and Zhenxi),and there was a difference of THg and Me Hg storage in plants in various attitudes. The corresponding THg and Me Hg storages were 145. 3,166. 4,124. 3 and 88. 2mg·hm- 2,and 1. 9,2. 7,3. 6 and 3. 2 mg·hm- 2in 145-150,150-160,160-170 and 170-175 m attitudes. The accumulation ability of dominant plants in WLFZ for THg( bioaccumulation factor,BAF < 1) was weaker than that for Me Hg( BAF > 1).