{"title":"Dissolved organic matter released from beach wrack is source-specific and molecularly highly diverse","authors":"Hannelore Waska, Hanne M. Banko-Kubis","doi":"10.1007/s10533-024-01159-7","DOIUrl":null,"url":null,"abstract":"<div><p>Beach wrack is an important supplier of nutrients and organic matter to sandy beach ecosystems and underlying subterranean estuaries (STEs), producing metabolic hotspots in these otherwise organic carbon- and nutrient-poor environments. To assess the impact of beach wrack type (e.g., marine, terrestrial, plant, animal) and environmental settings (e.g., tidal inundation, precipitation, and solar irradiation) on nutrient and dissolved organic matter (DOM) release, a series of leaching experiments was conducted. Quantities of leached nutrients and dissolved organic carbon (DOC) were determined, and DOM molecular composition was investigated using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Millimolar—to molar amounts of DOC and dissolved nitrogen were released from the beach cast per kg dry weight, with type of wrack and leaching medium (fresh- vs. saltwater) exerting the biggest influences. Exemplary for animal cast, jellyfish leached up to two 100-fold more, mostly organic, nitrogen compared to all other beach wrack types. FT-ICR-MS data of solid-phase extracted DOM indicated that beach wrack releases compounds with putative mono- and oligosaccharide-, amino acid- and vitamin-type molecular formulae, which likely serve as valuable substrate for heterotrophic microorganisms. DOM from the brown seaweed <i>Fucus</i> sp. was more aromatic than seawater DOM and even beach wrack of terrestrial origin, probably from structural components and secondary metabolites such as phlorotannins. We conclude that DOM and nutrient release from beach wrack strongly depends on wrack type and leaching medium, may obscure molecular provenance proxies (e.g., terrestrial indices), and adds a nutritional boost to infiltrating sea- and rainwater which likely impact microbial respiration rates in the STE.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 8","pages":"1057 - 1078"},"PeriodicalIF":3.9000,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01159-7.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biogeochemistry","FirstCategoryId":"93","ListUrlMain":"https://link.springer.com/article/10.1007/s10533-024-01159-7","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Beach wrack is an important supplier of nutrients and organic matter to sandy beach ecosystems and underlying subterranean estuaries (STEs), producing metabolic hotspots in these otherwise organic carbon- and nutrient-poor environments. To assess the impact of beach wrack type (e.g., marine, terrestrial, plant, animal) and environmental settings (e.g., tidal inundation, precipitation, and solar irradiation) on nutrient and dissolved organic matter (DOM) release, a series of leaching experiments was conducted. Quantities of leached nutrients and dissolved organic carbon (DOC) were determined, and DOM molecular composition was investigated using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Millimolar—to molar amounts of DOC and dissolved nitrogen were released from the beach cast per kg dry weight, with type of wrack and leaching medium (fresh- vs. saltwater) exerting the biggest influences. Exemplary for animal cast, jellyfish leached up to two 100-fold more, mostly organic, nitrogen compared to all other beach wrack types. FT-ICR-MS data of solid-phase extracted DOM indicated that beach wrack releases compounds with putative mono- and oligosaccharide-, amino acid- and vitamin-type molecular formulae, which likely serve as valuable substrate for heterotrophic microorganisms. DOM from the brown seaweed Fucus sp. was more aromatic than seawater DOM and even beach wrack of terrestrial origin, probably from structural components and secondary metabolites such as phlorotannins. We conclude that DOM and nutrient release from beach wrack strongly depends on wrack type and leaching medium, may obscure molecular provenance proxies (e.g., terrestrial indices), and adds a nutritional boost to infiltrating sea- and rainwater which likely impact microbial respiration rates in the STE.
海滩裹挟物是沙滩生态系统和地下河口（STEs）的重要营养物质和有机物质供应者，在这些原本缺乏有机碳和营养物质的环境中产生新陈代谢热点。为了评估海滩褶皱类型（如海洋、陆地、植物、动物）和环境背景（如潮汐淹没、降水和太阳辐射）对养分和溶解有机物（DOM）释放的影响，进行了一系列浸出实验。测定了浸出养分和溶解有机碳（DOC）的数量，并使用傅立叶变换离子回旋共振质谱法（FT-ICR-MS）研究了 DOM 的分子组成。每千克干重的海滩弃置物释放出的 DOC 和溶解氮的摩尔至摩尔量，对其影响最大的是栅栏类型和沥滤介质（淡水和海水）。与其他所有类型的海滩缠绕物相比，水母沥滤的动物粪便中的氮含量（主要是有机氮）要高出两倍到 100 倍。固相萃取 DOM 的 FT-ICR-MS 数据表明，海滩鞭痕释放出的化合物具有假定的单糖和寡糖、氨基酸和维生素类分子式，这些化合物可能是异养微生物的宝贵底物。褐藻 Fucus sp.产生的 DOM 比海水 DOM 甚至是陆源海滩栅栏产生的 DOM 更芳香，这可能是结构成分和次生代谢物（如绿单宁）的作用。我们的结论是，海滩栅栏释放的 DOM 和营养物质在很大程度上取决于栅栏类型和沥滤介质，可能会掩盖分子来源代用指标（如陆地指数），并为渗入的海水和雨水增加营养，这可能会影响 STE 中的微生物呼吸速率。
期刊介绍：
Biogeochemistry publishes original and synthetic papers dealing with biotic controls on the chemistry of the environment, or with the geochemical control of the structure and function of ecosystems. Cycles are considered, either of individual elements or of specific classes of natural or anthropogenic compounds in ecosystems. Particular emphasis is given to coupled interactions of element cycles. The journal spans from the molecular to global scales to elucidate the mechanisms driving patterns in biogeochemical cycles through space and time. Studies on both natural and artificial ecosystems are published when they contribute to a general understanding of biogeochemistry.
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