光照和硝酸盐浓度对东海原甲藻和三角褐指藻释放挥发性卤代烃的影响

海洋中产生的挥发性卤代烃(Volatile Halocarbons，VHCs)是氯、溴和碘进入大气的重要载体。海洋藻类能够产生损耗大气中臭氧的VHCs，尤其是海洋微藻已被证明是大气中一些VHCs的主要贡献者。环境因素对海洋微藻产生VHCs的影响研究较少，本文主要研究了光照和硝酸盐浓度对微藻释放VHCs的影响。将海洋微藻东海原甲藻(Prorocentrum donghaiense)和三角褐指藻(Phaeodactylum tricornutum)置于密封的玻璃容器中，并在不同光照条件(20 μmol/(m²·s)、70 μmol/(m²·s)和140 μmol/(m²·s))及不同硝酸盐浓度(1 mg/L、5 mg/L、10 mg/L和50 mg/L)下进行无菌单种培养，分析碘甲烷(CH₃I)、二溴甲烷(CH₂Br₂)、一氯二溴甲烷(CHBr₂Cl)和三氯乙烯(C₂HCl₃)4种VHCs的生产。采用吹扫−捕集气相色谱技术对其中的VHCs进行提取和分析。结果表明，光照强度和硝酸盐浓度会影响两种微藻对VHCs的释放，但是对不同VHCs的影响效果不同，其中CH₃I的释放受光照强度和硝酸盐浓度变化的影响比较显著。一定范围内，光照强度越大，两种微藻对CH₃I的释放量越大。适当的硝酸盐浓度(> 5 mg/L)在一定程度上促进了两种微藻对CH₃I的释放。

Influences of nitrate concentration and light intensity on the production of volatile halocarbons by Prorocentrum donghaiense and Phaeodactylum tricornutum

Volatile halocarbons (VHCs) produced in the oceans are important carriers for chlorine, bromine, and iodine to enter into the atmosphere. Marine algae can produce VHCs that have an ozone-depleting potential. Marine microalgae in particular have been shown to be major contributors of VHCs in the atmosphere. However, little is known about the influences of environmental factors on the production of VHCs by marine microalgae. In this study we examined the influence of different light intensities (20 μmol/(m2·s), 70 μmol/(m2·s) and 140 μmol/(m2·s)) and nitrate concentrations (1 mg/L, 5 mg/L, 10 mg/L and 50 mg/L) on the growth of Prorocentrum donghaiense and Phaeodactylum tricornutum and the releases of four VHCs (CH₃I, CH₂Br₂, CHBr₂Cl and C₂HCl₃) by these two microalgae. Unialgal cultures of these two kinds of microalgae were conducted in axenic and sealed glass vessels. The VHCs were extracted and analyzed by gas chromatography coupled to purge-and-trap preconcentration system. The releases of VHCs by these two microalgae were affected by light intensity and nitrate concentration, while their influences on different VHCs were various. The release of CH₃I was significantly affected by light intensity and nitrate concentrations. Within a certain range, the amount of CH₃I released from the two microalgae raised with the increase of light intensity. Moreover, our results showed that increasing the nitrate level above 5 mg/L could promote the production of CH₃I by these two microalgae.