典型泥炭源酚铁络合物的藻类可利用性——以铜绿微囊藻为例

Algae availability of typical peat-derived iron phenol complexes:A study based on Microcystis aeruginosa

铁是影响水生态系统初级生产力的关键微量元素.泥炭沼泽普遍含有丰富的溶解有机质,其中酚酸类物质具有稳定的芳香环结构,与铁有较强的络合能力,提高了陆源溶解性铁向水生态系统的有效输出.泥炭沼泽源酚铁配合物的生物可利用性对藻类生长及铁的生物地球化学循环有重要影响.本文通过一系列培养试验,研究了泥炭源典型酚铁络合物的藻类可利用性及其影响因素.结果表明,4种酚酸对藻类生长的影响均呈现“低促高抑”的规律,从藻类生物量和叶绿素含量来看,抑藻效果从高到低:水杨酸>对羟基苯甲酸>对香豆酸>咖啡酸.当水杨酸浓度达到20 mg·L^(−1)时,对藻类的光合作用抑制最强.对照试验表明,水杨酸络合态铁更难被藻类利用,这与其络合物稳定性较高有关.利用不同分子量段泥炭源DOM-Fe的培养试验显示,对藻类生长的促进作用从高到低依次为:>3 KD,1—3 KD,<1 KD.低分子量DOM(<1KD)络合态铁,由于其在培养体系中更加稳定,相对不易被藻类利用.

Iron is a key trace element that affects the primary productivity of aquatic ecosystems.Pealands are generally rich in dissolved organic matter.Among them,phenolic acids have a stable aromatic ring structure and have a high complexing ability with iron,which improves the effective output of terrestrial dissolved iron to the water ecosystem.The bioavailability of the peat-derived phenol-iron complex has an important impact on the growth of algae and the biogeochemical cycle of iron.In this paper,through a series of culture experiments,the algae availability and influencing factors of typical phenolic iron complexes from peat sources were studied.The results show that the effects of the four phenolic acids on the growth of algae present the law of“low concentration promotes,and high concentration inhibits”.From the perspective of algal biomass and chlorophyll content,the algae inhibitory effect is from high to low:salicylic acid>p-hydroxybenzoic acid>To coumaric acid>caffeic acid.When the concentration of salicylic acid reaches 20 mg·L^(−1),the photosynthesis inhibition of algae is the strongest.Control experiments show that the iron in the complexed form of salicylic acid is more difficult to be used by algae,which is related to the higher stability of the complex.Cultivation experiments using peat DOM-Fe of different molecular weights showed that the promotion of algae growth from high to low was:>3 KD,1—3 KD,<1 KD.Low molecular weight DOM(<1 KD)complexed iron,because it is more stable in the culture system,is relatively difficult to be used by algae.