摘要
采用化学逐步提取法和叶绿素荧光技术,在实验室无底泥条件下研究了镉(Cd)在热带海草泰来藻(Thalassia hemprichii)不同组织(叶、茎、根)中的累积规律,以及Cd对其光合作用的影响。结果表明:Cd在泰来藻体内的累积模式是叶>根>茎;在各处理条件下,泰来藻各组织中氯化钠、醋酸和盐酸提取态的Cd均是优势形态,三者之和占总量的80%～99%,表明活性较低且迁移能力较弱的形态是主要形态;随着Cd暴露浓度的增加,泰来藻各组织中盐酸提取态所占的比例下降7%～24%,而氯化钠和醋酸提取态的分配比例总和增加2%～24%,叶片中活性较高的乙醇和水提取态所占比例之和不断减小,而茎、根则呈现相反的趋势,这说明泰来藻通过改变各形态Cd在细胞和组织中的分配比例来降低高浓度Cd胁迫的毒性;高浓度Cd胁迫显著降低有效光量子产量ΔF/Fm'、叶绿素a、b和总叶绿素含量,表明其光合作用受到严重抑制。总之,在较低浓度Cd胁迫下,泰来藻存在一定的保护机制,但在高浓度Cd胁迫下,这种保护机制已不足以维持内环境的稳定,从而引起一系列毒性效应。
By the methods of sequential extraction and chlorophyll fluorescence,a laboratory experiment with no sediments was conducted to study the cadmium（Cd） accumulation in different organs of tropical seagrass Thalassia hemprichii and the effects of Cd on the photosynthesis of the seagrass.The Cd accumulation in T.hemprichii organs was in the order of leaf root rhizome.In all treatments,the Cd in the T.hemprichii organs was dominated by the 1 mol·L-1 NaCl-,2% HAc-,and 0.6 mol·L-1 HCl-extractable Cd,occupying 80%-99% of the total Cd,indicating that the less active and weakly migrated forms were the main forms of Cd in T.hemprichii.Under the exposure of increasing concentration Cd,the proportion of 0.6 mol·L-1 HCl-extractable Cd in different organs of T.hemprichii decreased by 7%-24%,while the proportion of 1 mol·L-1 NaCl-and 2% HAc-extractable Cd increased by 2%-24%.On the other hand,the 80% ethanol-and d-H2O-extractable Cd,the high active Cd forms,decreased in T.hemprichii leaf but increased in root and rhizome.These results suggested that T.hemprichii could weaken the toxicity of Cd by changing the proportion of different Cd forms in cells and/or organs.Under the exposure of high concentration Cd,the effective quantum yield（ΔF/Fm＇） and the chlorophyll a,chlorophyll b and total chlorophyll contents declined significantly,suggesting that the photosynthesis of T.hemprichii was seriously impaired.It seemed that the protective mechanisms evolved by T.hemprichii could play an important role in Cd detoxification when exposed to relatively low concentration Cd,but became restricted under higher Cd stress.
出处
《生态学杂志》
CAS
CSCD
北大核心
2012年第11期2828-2833,共6页
Chinese Journal of Ecology
基金
国家自然科学基金项目(41076069和40776086)
南海区海草床环境质量综合评价方法项目(DOMEP-(MEA)-01-03)资助
关键词
镉
泰来藻
累积
化学形态
光合作用
Cd
Thalassia hemprichii
accumulation
chemical form
photosynthesis.
