摘要:
近年来,海洋重金属污染日益严重,为考察重金属对海洋藻类的生物毒性效应,进而评估其对海洋生态环境的影响,本研究采用一次性培养的实验方法,测定了2种重金属Hg (Ⅱ)和Pb (Ⅱ)对8种海洋单细胞藻的急性毒性效应,包括赤潮异弯藻(Heterosigma akashiwo Hada)、旋链角毛藻(Chaetoceros curvisetus Cleve)、海洋原甲藻(Prorocentrum micans Ehrenberg)、裸甲藻(Gymnodinium sp.)、中肋骨条藻(Skeletonema costatum (Greville) Cleve)、三角褐指藻(Phaeodactylum tricornutumBohlin)、青岛大扁藻(Platymonas helgolanidica)和亚心型扁藻(Platymonas subcordiformis),测定出Hg (Ⅱ)对8种海洋藻的96 h-EC50分别为16、42、24、37、31、12、385和161μg·L-1,而Pb (Ⅱ)对赤潮异弯藻、旋链角毛藻、海洋原甲藻和裸甲藻的96 h-EC50分别为9 516、8 373、12 002和10 128μg·L-1。在本研究的培养条件下,Hg (Ⅱ)对受试海洋藻的毒性效应明显大于Pb (Ⅱ),Pb (Ⅱ)对赤潮异弯藻、旋链角毛藻、海洋原甲藻和裸甲藻的96 h-EC50与Hg (Ⅱ)对这4种藻的96 h-EC50的比值分别为594.75、199.36、500.08和273.73,而中肋骨条藻、三角褐指藻、青岛大扁藻和亚心型扁藻在有效浓度范围内未能检测到Pb (Ⅱ)对其相应的96 h-EC50,说明Pb (Ⅱ)对这4种藻的生物毒性作用比较小;比较重金属对各种藻作用的96 h-EC50,可知饵料藻对重金属的耐受性高于赤潮藻。同时发现,低浓度的Pb (Ⅱ)对藻类生长有一定的促进作用;在f/2营养液的培养条件下,重金属对海洋单细胞藻96 h-EC50值高于自然海水条件下相应的值。
Abstract:
Heavy metal pollution is becoming more and more serious in marine environment recently.In order to evaluate the impact of heavy metals on marine eco-environment,the biotoxicity of heavy metals to marine algae was investigated.Using batch culture method,acute toxicity of Hg(Ⅱ) and Pb(Ⅱ) to 8 species of marine unicellular algae,Heterosigma akashiwo Hada,Chaetoceros curvisetus Cleve,Prorocentrum micans Ehrenberg,Gymnodinium sp.,Skeletonema costatum(Greville) Cleve,Phaeodactylum tricornutum Bohlin,Platymonas helgolanidica and Platymonas subcordiformis,was measured.The results showed that the 96 h-EC50 of Hg(Ⅱ) for the tested algal species were 16,42,24,37,31,12,385 and 161 μg·L-1,respectively;and the 96 h-EC50 of Pb(Ⅱ) for Heterosigma akashiwo,Chaetoceros curvisetus,Prorocentrum micans and Gymnodinium sp.were 9 516,8 373,12 002 and 10 128 μg·L-1,respectively.The toxicity of Hg(Ⅱ) was significantly higher than that of Pb(Ⅱ) under the f/2 culture condition;the ratios of 96 h-EC50 values of Pb(Ⅱ) to Hg(Ⅱ) for Heterosigma akashiwo,Chaetoceros curvisetus,Prorocentrum micans and Gymnodinium sp.were 594.75,199.36,500.08 and 273.73,respectively.However,the 96 h-EC50 of Pb(Ⅱ) for Skeletonema costatum,Phaeodactylum tricornutum,Platymonas helgolanidica and Platymonas subcordiformis could not be detected accurately in the effective concentration range under the f/2 culture condition,which suggested that the toxicity of Pb(Ⅱ) to these four algae was very low.Based on the value of 96 h-EC50,the tolerance of feed algae to heavy metals was estimated to be higher than that of harmful bloom algae.Moreover,it is found that Pb(Ⅱ) could stimulate the growth of algae at relatively lower concentration,and the tolerance of algae to heavy metal was higher under the f/2 culture condition than that in natural environment.
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