双向标记培养植物测定大气二氧化碳稳定碳同位素组成

Determination of the stable carbon isotope composition in atmospheric carbon dioxide based on plants cultured in bidirectional tracers

关键词:  植物  碳酸酐酶  大气二氧化碳  全球气候变化  稳定碳同位素组成

Key words:  plants  carbonic anhydrase  atmospheric carbon dioxide  global climate change  stable carbon isotope composition

摘要:

基于植物能够利用体内的碳酸酐酶来催化碳酸氢根离子生成二氧化碳和水作为底物进行光合作用的特性,采用两种δ¹³C_PDB值差值大于10‰的碳酸氢钠分别作为外源碳酸氢根离子的碳同位素标记物,通过室内双向水培诸葛菜和芥菜型油菜实验,分别向水培处理液里添加已知δ¹³C_PDB值的碳酸氢钠并培养24 h,利用同位素比值质谱(IRMS)技术,测定并计算了两个时间、两种环境下的大气二氧化碳稳定碳同位素日平均组成。结果表明:在环境1(不同浓度的NaHCO₃处理液)下所得到的δ_Ca值与添加到处理液中的碳酸氢根离子的浓度有关; 在环境2(不同浓度的PEG处理液)下所得到的δ_Ca值与添加到处理液中的PEG的浓度无关; 两种环境下所测得的大气二氧化碳稳定碳同位素日平均组成δ_Ca值与实验中培养的植物种类无关,而与添加到培养液中碳酸氢根离子的浓度及植物的生长速率有关。数据重现性好,结果准确可靠,可以高精度的测定不同待测环境下大气二氧化碳稳定碳同位素比值,其可为以后监测不同时间、不同地点的大气二氧化碳碳同位素组成及来源提供非常有效的方法和信息。

Abstract:

Based on the characteristics that plants can take advantage of carbonic anhydrase enzyme to catalyze the bicarbonate ions into carbon dioxide and water,which can serve as substrates for photosynthesis,two sodium bicarbonate whose δ¹³C_PDB value differences were greater than 10‰ were used as the carbon isotope labeling and to bidirectional water culture Orychophragmus violaceus and Brassica juncea lasted for 24 h in this study,respectively. The daily mean stable carbon isotope compositions in two different times and environments were investigated and analyzed according to isotope ratio mass spectrometry(IRMS)technique. In particular,Environment 1 represented adding some sodium bicarbonate to solutions to get different concentrations of bicarbonate solution and Environment 2 represented adding some polyethylene glycol to solutions to get different concentrations of PEG solutions. These results showed that δ_Ca values in the Environment 1 were related to the concentrations of added exogenous sodium bicarbonate to solution,but these in the Environment 2 had no significant correlation with PEG concentration in the treatment solution,these results in this study suggested that the daily mean stable carbon isotope composition of atmospheric carbon dioxide had no relationship with the cultured plant species,but was related to the concentration of exogenous bicarbonate ion added to the culture solution and growth rate of the two plants. The data obtained with good reproducibility and reliability,accurately determined the stable carbon isotope composition of atmospheric carbon dioxide in test environments. This study confirmed that the method was a very powerful tool for monitoring the carbon isotope composition and sources of atmospheric carbon dioxide in different times and places for further.